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Invited Review
Advances in Noble Metals Modified g-C3N4 Heterostructures towards Enhanced Photocatalytic Redox Ability
Xiao Zhang and  Ping Yang
, Available online 20 April 2024, https://doi.org/10.1007/s12613-024-2924-6
Abstract:
The photocatalytic activities of catalysts depend on energy harvesting ability and the separation/transport of photogenerated carriers. The surface plasmon resonance (SPR) of noble metal nanoparticles (e.g., Cu, Au, Pd etc.) can be adjusted in the entire visible region via varying the nanocomponents of the material to attain enhanced light absorption capacity of graphitic carbon nitride (g-C3N4) based composites. With the SPR of noble metals been able to enhance the local electromagnetic field and improve the interband transition as well as the resonant energy transfer occurred from the plasmonic dipoles to electron-hole pairs via near-field electromagnetic interactions, noble metals have been quite popular nanocomponents materials in the case of g-C3N4 modification for the applications of CO2 photoreduction and water splitting. Herein, recent key advances in noble metals (either in single atom, cluster, or nanoparticle forms) and inorganic/organic nanocomponents incorporated g-C3N4 nanosheets based composite photocatalysts with improved photoinduced charge mobility are systematically discussed, particularly, the significant applications of these photocatalysts in CO2 photo-conversion and H2 production. Issues related to the different types of multi-nanocomponent heterostructures (involving Schottky junctions, Z-/S-scheme heterostructures, composed of noble metals and additional semiconductor nanocomponents) as well as the adjustment of dimensionality of the heterostructures (by incorporating noble metal nanoplates on g-C3N4 forming 2D/2D heterostructures) are also discussed. The current prospects and possible challenges of the noble metal (e.g., Au, Pt, Pd, and Cu) incorporated g-C3N4 composite photocatalysts, particularly in water splitting, CO2 reduction, pollution degradation, and chemical conversion applications are summarized.
Invited Review
Deep eutectic solvents for separation and purification applications in critical metals metallurgy: Recent Advances and Perspectives
Shuo Chen, Shengpeng Su, Yanfang Huang, Bingbing Liu, Hu Sun, Shuzhen Yang, and  Guihong Han
, Available online 19 April 2024, https://doi.org/10.1007/s12613-024-2923-7
Abstract:

As a separation and purification technology, solvent extraction is crucial in the field of critical metals metallurgy. At present, organic solvents mostly utilized in solvent extraction have the disadvantages of high volatility, high toxicity, and flammability, causing a spectrum of hazards for human health and environmental protection. Neoteric solvents are being recognized as preferable alternatives to these harmful organic solvents. In the past two decades, several neoteric solvents have been proposed involving ionic liquids (ILs) and deep eutectic solvents (DESs). DESs have gradually become the focus of green solvents owing to several advantages including low toxicity, degradability, and low cost. In this critical review, a systematic description on their classification, formation mechanisms, preparation methods, characterization technologies, and special physicochemical properties based on the most recent advancements in research. Afterwards, the major separation and purification applications of DESs in critical metals metallurgy and other fields were comprehensively summarized. Finally, the future opportunities and challenges about DESs were prospected in the current area of research. In conclusion, this review provides valuable insights for improving our overall understanding of deep eutectic solvents, and it has important significance for expanding separation and purification applications in critical metals metallurgy.

Invited Review
Review on the design of high-strength and hydrogen embrittlement resistant steels
Zhiyu Du, Rongjian Shi, Xingyu Peng, Kewei Gao, and  Xiaolu Pang
, Available online 3 April 2024, https://doi.org/10.1007/s12613-024-2900-1
Abstract:

Given the carbon peak and carbon neutrality era, there is an urgent necessity to develop high-strength steel with remarkable hydrogen embrittlement resistance. This is crucial to enhance toughness and ensure the secure utilization of hydrogen in emerging iron and steel materials. Simultaneously, the pursuit of enhanced metallic materials presents a cross-disciplinary scientific and engineering challenge. Developing high-strength, toughened steel that can enhance both strength and HE resistance holds significant theoretical and practical implications. This ensures secure hydrogen utilization and further carbon neutrality objectives within the iron and steel sector. Based on the design principles of high-strength steel HE resistance, this review provides a comprehensive overview of research on designing surface HE resistance and employing nano-sized precipitate as intragranular hydrogen trapping. It also proposes feasible recommendations and prospects for designing high-strength steel with enhanced HE resistance.

Invited Review
Recent Advances and Perspectives in MXene-Based Cathodes for Aqueous Zinc-Ion Batteries
Aiduo Wu, Tianhao Wang, Long Zhang, Chen Chen, Qiaomin Li, Xuanhui Qu, and  Yongchang Liu
, Available online 23 February 2024, https://doi.org/10.1007/s12613-024-2859-y
Abstract:

Aqueous zinc-ion batteries (AZIBs) hold great promise for grid-scale energy storage applications due to their intrinsic safety, cost effectiveness, environmental friendliness, and impressive electrochemical performance. However, the strong electrostatic interactions between zinc ions and host materials place obstacles in the development of advanced cathode materials that can accommodate the efficient, rapid, and stable Zn-ion storage. MXenes and their derivatives, which feature large interlayer spacing, excellent hydrophilicity, outstanding electronic conductivity, and high redox activity, are considered as the “rising star” cathode candidates for AZIBs. Herein, we comprehensively review the recent advances in MXenes as cathodes for AZIBs from the perspectives of crystal structures, Zn-storage mechanisms, surface modification, interlayer engineering, and conductive network design to elucidate the correlations among composition, structure, and electrochemical performance. Then, we outline the remaining challenges facing MXenes for aqueous Zn-ion storage such as the urgent need for improvement of the toxic preparation methods, the exploration of potential novel MXene cathodes, and the suppression of restacking of layered MXenes upon cycling, and foresee the bright prospects of MXene-based cathode materials for high-performance AZIBs.

Invited Review
Research progress and future prospects in the service security of key blast furnace equipment
Yanxiang Liu, kexin jiao, Jianliang Zhang, Cui Wang, Lei Zhang, and  Xiaoyue Fan
, Available online 7 February 2024, https://doi.org/10.1007/s12613-024-2850-7
Abstract:

The stable and low-carbon production of iron relies on the safety and longevity of key blast furnace equipment. This paper presents an analysis of the heat transfer characteristics of these components, as well as the uneven distribution of cooling water in parallel pipes based on hydrodynamic principles. Feasible methods for improving blast furnace cooling intensity are also discussed. Additionally, this study reviews the preparation process, performance, and damage characteristics of three key pieces of equipment: coolers, tuyeres, and hearth refractories. To better control these critical components under high-temperature working conditions, optimized technologies such as blast furnace operation and maintenance technology, self-repair technology, and full life cycle management technology are proposed. Finally, further research into safety assessments and predictions for key blast furnace equipment under new operating conditions is proposed.

Invited Review
Electrospinning-hot pressing technique for the fabrication of thermal and electrical storage membranes and applications
Panpan Che, Baoshan Xie, Penghui Cao, Youfu Lv, Daifei Liu, Huali Zhu, Xianwen Wu, Zhangxing He, Jian Chen, and  Chuanchang Li
, Available online 30 January 2024, https://doi.org/10.1007/s12613-024-2842-7
Abstract:

Electrospinning-hot pressing technique (EHPT) by integrating electrospinning with hot pressing is an efficient and convenient method in the synthesis of nanofibrous composite material with good performance in energy storage. The emerging composite membrane prepared by EHPT which exhibits characteristics of large surface area, controllable morphology, and compact structure, has received tremendous attention. In this paper, we systematically discuss the conduction mechanism of composite membranes in thermal and electrical energy storage and the performance enhancement method based on the fabrication process of EHPT. Simultaneously, the state-of-the-art and applications of composite membranes in these two fields are introduced respectively. Particularly, in the field of thermal energy storage, the membranes obtained by EHPT have longitudinal and transverse nanofibers, which form unique thermal conductivity pathways; besides, the longitudinal and transverse nanofibers also provide sufficient space for the filling of functional materials. electrospinning-hot pressing membranes can be used in thermal management systems and building energy conservation. In the area of electrical energy storage, the composite membranes produced by EHPT improve the electrochemical properties of the separators while enhancing the mechanical and thermal stability. the application of electrospinning-hot pressing membranes on capacitors, lithium-ion batteries (LIBs), fuel cells, sodium-ion batteries (SIBs) and hydrogen-bromine flow batteries (HBFBs) are still needed to be explored. In the future, EHPT is expected to bring new life through its own technological breakthroughs, or then combined with other technologies to produce smarter materials.

Invited Review
Nonreciprocal thermal metamaterials: Methods and applications
Zhengjiao Xu, Chuanbao Liu, Xueqian Wang, Yongliang Li, and  Yang Bai
, Available online 15 December 2023, https://doi.org/10.1007/s12613-023-2811-6
Abstract:

The nonreciprocity of thermal metamaterials holds significant potential applications in isolation protection, unidirectional transmission, and energy harvesting. However, due to the inherent isotropic diffusion law of heat flow, it is extremely difficult to achieve nonreciprocity of heat transfer. This review presents the recent advancements on thermal nonreciprocity. The second section explores the fundamental theories that underpin the design of nonreciprocal thermal metamaterials: Onsager reciprocity theorem. Subsequently, the third, fourth and fifth sections elucidate three methods for realizing nonreciprocal metamaterials in the thermal field: through nonlinearity, spatiotemporal modulation, and angular momentum bias, as well as the applications of nonreciprocal thermal metamaterials. In sixth section, we discuss nonreciprocal thermal radiation. In seventh section, we discuss the potential applications of nonreciprocity to other Laplacian physical fields. Finally, prospects for advancing nonreciprocal thermal metamaterials are discussed including advancements in device design and manufacturing techniques as well as machine learning-assisted material design.

Invited Review
Effect of bipolar plates design on corrosion and mass and heat transfer in proton exchange membrane water electrolyzers: A review
Jiuhong Zhang, Xiejing Luo, Yingyu Ding, Luqi Chang, and  Chaofang Dong
, Available online 1 December 2023, https://doi.org/10.1007/s12613-023-2803-6
Abstract:

Attaining a decarbonized and sustainable energy system, the core solution to global energy issues, has proven to be accessible by developing hydrogen energy. Proton exchange membrane water electrolyzers (PEMWEs) are promising techniques for hydrogen production considering their high-efficiency, rapid responsiveness and compactness. Bipolar plates account for a relatively high percentage of the total cost and weight compared to other components in PEMWEs, so optimizing their design may accelerate the promotion of PEMWEs. In this paper, advances in material selection and flow field design for bipolar plate design are reviewed. Firstly, the working conditions of proton exchange membrane fuel cells (PEMFCs) and PEMWEs are compared. Then, the current research status of bipolar plate substrates and surface coatings are summarized, and new structures that have recently emerged in flow field design are presented. Furthermore, the interaction between material selection and structural design is explored to provide guidance for advanced bipolar plate design. Finally, it looks at potential directions of development for bipolar plate design: material fabrication and flow field geometry optimization using 3D printing and surface coating composition optimization based on computational materials science.

Invited Review
Current research progress of heat-resistant Mg alloys: A review
Hong Yang, Wenlong Xie, Jiangfeng Song, Zhihua Dong, Yuyang Gao, Bin Jiang, and  Fusheng Pan
, Available online 1 December 2023, https://doi.org/10.1007/s12613-023-2802-7
Abstract:

With the increasing attention to the lightweight metals, many essential fields have put forward higher requirements for the Mg alloys with both good room-temperature (RT) and high-temperature mechanical properties. However, the high-temperature mechanical properties of the commonly used commercial Mg alloys, such as AZ91D, decrease significantly with increasing temperatures. Over the decades, extensive efforts have been devoted to developing the heat-resistant Mg alloys. They either inhibit the generation of thermally unstable phase or promote the formation of thermally stable precipitates/phases in the matrix by solid solution or precipitation strengthening. In this review, substantial number of researches are systematically introduced and discussed. Different alloy systems, including Mg-Al, Mg-Zn and Mg-RE based alloys are carefully classified and compared to reveal their mechanical properties and strengthening mechanisms. The research emphasis, limitations and future perspectives of these heat-resistant Mg alloys are also pointed out and discussed to develop future heat-resistant Mg alloys and to broaden their potential application areas.

Invited Review
Using cemented paste backfill to tackle the phosphogypsum stockpile in China: A down-to-earth technology with new vitalities in pollutants retention and CO2 abatement
Yikai Liu, Yunming Wang, and  Qiusong Chen
, Available online 1 December 2023, https://doi.org/10.1007/s12613-023-2799-y
Abstract:

Phosphogypsum (PG), a hard-to-dissipate by-product of the phosphorus fertilizer production industry, places strain on the biogeochemical cycles and ecosystem functions of the storage sites, which is already a pervasive problem worldwide and needs careful stewardship. In this review, we examine the presence of potentially toxic elements (PTEs) in PG and describe their associations with soil properties, anthropogenic activities, and surrounding organisms. We then review different ex-/in-situ solutions for promoting the sustainable management of PG, with an emphasis on in-situ cemented paste backfill, which offers a cost-effective and highly scalable opportunity to advance the value-added recovery of PG. However, the concerns related to the PTEs retention capacity and long-term effectiveness limit the implementation of this down-to-earth strategy. In addition, the technology has recently undergone additional scrutiny in order to meet the climate mitigation ambition of the Paris Agreement and China's Carbon Neutrality Economy, as the large-scale demand for ordinary Portland cement from this conventional option has resulted in significant CO2 emissions. We therefore next discussed how to integrate innovative strategies, including complementary cementitious materials, alternative binder solutions, CO2 curing, CO2 mineralization, and optimization of the supply chain for the profitability and sustainability of PG remediation. Future research will need to bridge the gap between the feasibility of expanding these advanced pathways and the multidisciplinary needs to maximize the co-benefits in environmental, social, and economic.

Invited Review
Research progress of CO2 capture and mineralization based on natural minerals
Chenguang Qian, Chunquan Li, Peng Huang, Jialin Liang, Xin Zhang, Jifa Wang, Jianbing Wang, and  Zhiming Sun
, Available online 21 November 2023, https://doi.org/10.1007/s12613-023-2785-4
Abstract:

Natural minerals, such as kaolinite, halloysite, montmorillonite, attapulgite, bentonite, sepiolite, forsterite, wollastonite, etc., are considered to have significant potential in CO2 capture and mineralization due to their abundant reserves, low prices, high mechanical properties, and chemical stability. Over the past decades, various methods such as heat, acid, alkali, organic amine, amino silane, and ionic liquid have been employed to enhance the CO2 capture performance of natural minerals to achieve high specific surface area, a large number of pore structures and rich active sites. It is pointed out that making full use of the properties of natural minerals, adopting suitable modification methods and preparing composite materials with higher specific surface area and rich active sites will be the main direction of CO2 capture by natural minerals in the future. In addition, regarding the CO2 mineralization by natural minerals, we have provided a summary of the principle and technical route of direct and indirect mineralization. This involves the use of minerals with a high calcium and magnesium content, such as forsterite (MgSiO4), serpentine [Mg3Si2O(OH)4], and wollastonite (CaSiO3). The research status of indirect mineralization of CO2 by using hydrochloric acid, acetic acid, molten salt, and ammonium salt as media is also introduced in detail. It is pointed out that the recovery of additives and high-value-added products in the mineralization process to increase economic benefits will be the focus of future research on CO2 mineralization by natural minerals.

Invited Review
A review on linear friction welding of Ni-based superalloys
Xiawei Yang, Tingxi Meng, Qiang Chu, Yu Su, Zhenguo Guo, Rui Xu, Wenlong Fan, Tiejun Ma, and  Wenya Li
, Available online 10 November 2023, https://doi.org/10.1007/s12613-023-2782-7
Abstract:

Ni-Based superalloys have become one of the most important materials in high-temperature applications in aerospace, nuclear energy, or gas turbines due to their excellent corrosion resistance, radiation resistance, fatigue resistance and high temperature strength. In recent years, a new joining technology of linear friction welding (LFW) with near-net-forming characteristics can be used for the manufacture and repair of a wide range of aerospace components. In this paper, the published works on LFW of Ni-Based superalloys are reviewed with the objective to understand the characteristics of frictional heat generation and extrusion deformation, the simulation of physical fields, the microstructures, the mechanical properties, the flash morphology, the residual stresses, the creep, and the fatigue of the Ni-based superalloy weldments. The purpose of this article is to provide industry and academia with an understanding of the macroscopic characteristics, deformation mechanisms, microstructures, and mechanical properties of LFW joints so that the LFW process can be better utilized and practiced in the future.

Invited Review
Recent progress in visualization and digitization of the coherent transformation structures and application in high-strength steel
Xuelin Wang, Zhenjia Xie, Xiucheng Li, and  Chengjia Shang
, Available online 10 November 2023, https://doi.org/10.1007/s12613-023-2781-8
Abstract:

At present, high-strength steel is mainly composed of medium or low temperature microstructures such as bainite or martensite with coherent transformation characteristics. This type of microstructure has high density of dislocation and fine crystallographic structural units, making it easy to achieve coordinated matching of high strength, high toughness, and high plasticity. Meanwhile, due to the excellent welding performance, high-strength steel has been widely used in major engineering construction such as pipelines, ships, and bridges. However, it is difficult to visualize and digitize the effective units of these coherent transformation structures using traditional methods (optical microscope and scanning electron microscope) due to the complex morphology, and it is even more difficult to establish quantitative relationships with macroscopic mechanical properties and key process parameters. This article reviews the latest progress in microstructural visualization and digitization of high-strength steel, with a focus on the application of crystallographic methods in the development of high-strength steel plate and its welding. By obtaining crystallographic data (Euler angle) of the transformed microstructures through EBSD (electron back-scattering diffraction) and combining it with the calculation of inverse transformation from bainite or martensite to austenite, the reconstruction of high-temperature parent austenite and orientation relationship (OR) during continuous cooling transformation can be determined. Furthermore, visualization of the crystallographic packets, blocks, and variants based on actual OR, as well as digitization of the various grain boundaries, can be effectively completed to establish quantitative relationships with alloy composition and key process parameters, thereby providing reverse design guidance for the development of high-strength steel.

Invited Review
The relationship between the microstructures and unique behavior in high-entropy alloys
Yaqi Wu, Peter K. Liaw, Ruixuan Li, Weiran Zhang, Guihong Geng, Xuehui Yan, Guiqun Liu, and  Yong Zhang
, Available online 3 November 2023, https://doi.org/10.1007/s12613-023-2777-4
Abstract:

High-entropy alloys (HEAs), introduced as a pioneering concept in 2004, captured the keen interest of numerous researchers. Entropy, in this context, can be perceived as representing disorder and randomness, while the elemental compositions within the alloy system occupy specific structural sites in space, a concept referred to as structure. According to Shannon entropy, this structure is analogous to information. Generally, the arrangement of atoms within a material, termed its structure, plays a pivotal role in dictating its properties. In addition to expanding the array of options for alloy composites, HEAs also afford ample opportunities for diverse structural designs. Numerous examples underscore the profound influence of distinct structural features on exceptional behaviors of alloys, including remarkably high fracture strength with excellent ductility, antiballistic capability, exceptional radiation resistance, and corrosion resistance etc. In this paper, we delve into various unique material structures and properties, while also elucidating the intricate relationship between structure and performance.

Invited Review
State of the art in oxide metallurgy technology for improving weldability of high-strength low alloy steel
Tingting Li and  Jian Yang
, Available online 28 September 2023, https://doi.org/10.1007/s12613-023-2754-y
Abstract:

The mechanisms of oxide metallurgy technology include inducing IAF using micron-sized inclusions and restricting the growth of prior austenite grains (PAGs) by nano-sized particles during the welding process. The typical oxide metallurgy technologies include the HTUFF technology, JFE EWEL, KST technology, the ETISD technology, and so on. The complex deoxidation of Ti with other strong deoxidant elements such as Mg, Ca, Zr and rare earth metals (REM) can improve the HAZ toughness. The Mg addition is more effective in promoting the precipitation of TiN particles to refine the PAG size. The Ca addition can effectively improve the IAF nucleation due to the formation of Ca oxysulfide. Zr-containing inclusions are also effective in inducing IAF nucleation. REM can refine precipitates and induce IAF. Increasing C, Si, Al, Nb, Cr content will all impair the HAZ toughness. Higher C content usually increase the number of coarse carbides and decrease the potency of the IAF formation. The Si and Cr addition both lead to the formation of undesirable microstructures. The high Al content in steel is not beneficial to the IAF nucleation due to the formation of Al2O3 inclusions. Nb is soluble in TiN particles to form (Ti,Nb)(C,N) particles which have poor high-temperature stability. On the other hand, Mo, V and B can enhance the HAZ toughness. Mo-containing precipitates seem to present better thermal stability, and increasing Mo content can refine precipitates. VN or V(C, N) prefers to be effective in promoting the nucleation of IAF due the good crystallographic coherent relationship with ferrite. The segregation of B atoms at the PAG boundary and the B depleted zone around inclusion will promote the formation of IAF.

Invited Review
Microstructure and forming mechanism of metal by ultrasonic vibration plastic forming
Qinghe Cui, Xuefeng Liu, Wenjing Wang, Shaojie Tian, Vasili Rubanik, Vasili Rubanik Jr., and  Dzmitry Bahrets
, Available online 13 September 2023, https://doi.org/10.1007/s12613-023-2745-z
Abstract:

Compared with the traditional plastic forming technology, ultrasonic vibration plastic forming has the advantages of reducing the forming force and improving the surface quality of the workpiece. It has a very broad application prospect in the industrial manufacturing field. In recent years, researchers have conducted extensive research in ultrasonic vibration plastic forming of metals. A deep foundation has been laid for the development of this field. This study classified metals according to their crystal structures. The effects of ultrasonic vibration on the microstructure during plastic forming of face centered cubic (FCC), body centered cubic (BCC) and hexagonal close packed (HCP) metals and the forming mechanism of ultrasonic vibration were reviewed. The main problems and future research direction of ultrasonic vibration plastic forming of metals were pointed out.

Research Article
Effects of the extrusion parameters on microstructure, texture and room temperature mechanical properties of extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy
Chenjin Zhang, Guangyu Yang, Lei Xiao, Zhiyong Kan, Jing Guo, Qiang Li, and  Wanqi Jie
, Available online 19 April 2024, https://doi.org/10.1007/s12613-024-2918-4
Abstract:

Microstructure, texture and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures (260 ℃ and 320 ℃), extrusion ratios (10:1, 15:1 and 30:1) and extrusion speeds (3 mm/s and 6 mm/s), respectively. The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy, and the second phase showed streamline distribution along the extrusion direction (ED). With extrusion temperature increased from 260 ℃ to 320 ℃, the microstructure, texture and mechanical properties of alloys changed slightly. The DRX degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 15:1 and 30:1, and the strength gradually decreased but elongation (EL) increased. With the extrusion speed increased from 3 mm/s to 6 mm/s, the grain sizes and DRX degree increased significantly, and both samples presented the typical<21 1="">-<112 3="">rare-earth (RE) textures. The alloy extruded at 260 ℃ with extrusion ratio of 10:1, extrusion speed of 3 mm/s showed the best comprehensive properties with tensile yield strength (TYS) of 213 MPa and EL of 30.6%. After quantitatively analyzing the contribution of strengthening mechanisms, it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening contributions. These results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.

Research Article
Nanostructured ZnO/BiVO4 Ⅰ-scheme heterojunctions for piezocatalytic degradation of organic dyes via harvesting ultrasonic vibration energy
Yiling Li, Xiaoyao Yu, Yingjie Zhou, Yao Lin, and  Ying Wu
, Available online 19 April 2024, https://doi.org/10.1007/s12613-024-2920-x
Abstract:

BiVO4 porous spheres modified by ZnO were designed and synthesized using a facile two-step method. The resulting ZnO/BiVO4 composite catalysts have shown remarkable efficiency as piezoelectric catalysts for degrading Rhodamine B (RhB) under mechanical vibrations, they exhibit superior activity compared to pure ZnO. The 40% ZnO/BiVO4 heterojunction composite displayed the highest activity, along with good stability and recyclability. The enhanced piezoelectric catalytic activity can be attributed to the formation of an Ⅰ-scheme heterojunction structure, which can effectively inhibit the electron-hole recombination. Furthermore, hole (h+) and superoxide radical (·O2-) are proved to be the primary active species. Therefore, ZnO/BiVO4 stands as an efficient and stable piezoelectric catalyst with a broad potential application in the field of environmental water pollution treatment.

Research Article
Developing an Atmospheric Aging Evaluation Model of Acrylic Coatings: A Semi-Supervised Machine Learning Algorithm
Yiran Li, Zhongheng Fu, Xiangyang Yu, Zhihui Jin, Haiyan Gong, Lingwei Ma, Dawei Zhang, and  Xiaogang Li
, Available online 19 April 2024, https://doi.org/10.1007/s12613-024-2921-9
Abstract:

To study the atmospheric aging of acrylic coatings, a two-year aging exposure experiment was conducted in 13 representative climatic environments in China. An atmospheric aging evaluation model of acrylic coatings was developed based on aging data including 11 environmental factors from 567 cities. A hybrid method of random forest and Spearman correlation analysis was used to reduce the redundancy and multicollinearity of the data set by dimensionality reduction. A semi-supervised collaborative trained regression model was developed with the environmental factors as input and the low-frequency impedance modulus values of the electrochemical impedance spectra of acrylic coatings in 3.5% NaCl solution as output. The model improves accuracy compared to supervised learning algorithms model(support vector machines model). The model provides a new method for the rapid evaluation of the aging performance of acrylic coatings, and may also serve as a reference to evaluate the aging performance of other organic coatings.

Research Article
In-situ Deposition and Comparative Study of Electromagnetic Absorption Performance of Mxene (Ti3C2Tx) @ Nano-FeCoNi Composite Materials with Different Compositions
Hong Li, Hongyang Li, Zhenfeng Shen, Shentao Zeng, Feng Yang, Qing Cai, Wenqi Xu, Ran Wang, Cui Luo, and  Ying Liu
, Available online 19 April 2024, https://doi.org/10.1007/s12613-024-2922-8
Abstract:

To effectively investigate the impact of composite relationship of Mxene (Ti3C2Tx) and nano-FeCoNi magnetic particles on the electromagnetic absorption properties of composite, three sets of Mxene (Ti3C2Tx)@nano-FeCoNi composite materials with Mxene content of 15mg, 45mg, and 90mg were prepared with in-situ liquid phase deposition. The microstructure, static magnetic properties, and electromagnetic absorption performance of these composites were studied. The results indicate that the Mxene@nano-FeCoNi composite material was primarily composed of face-centered cubic crystal structure particles and Mxene, with spherical FeCoNi particles uniformly distributed on the surface of the multilayered Mxene. The average particle size of the alloy particles was approximately 100 nanometers, exhibiting good dispersion without noticeable particle aggregation. With the increase of Mxene content, the specific saturation magnetic and coercivity of the composite initially decrease and then increase, displaying typical soft magnetic properties. In comparison with FeCoNi magnetic alloy particles, the addition of Mxene causes an increasing trend in the real and imaginary parts of the dielectric constant of the composite, while the real and imaginary parts of the magnetic permeability exhibit a decreasing trend. The inclusion of Mxene enhances the dielectric loss but reduces the magnetic loss. Additionally, the dielectric loss and magnetic loss performance of the composite material do not show a linear function relationship with the addition of Mxene. Both the FeCoNi magnetic alloy particles and the Mxene@FeCoNi composite material exhibit polarization relaxation loss, and it was found that eddy current loss was not the main mechanism of magnetic loss. The material attenuation constant increases with the addition of Mxene, while the impedance matching decreases. Moreover, the maximum reflection loss increases and the maximum effective absorption bandwidth decreases with the addition of Mxene. When the Mxene addition was 90mg, the composite material exhibits a maximum reflection loss |RLmax| of 46.9dB with sample thickness of 1.1mm, and a maximum effective absorption bandwidth of 3.60GHz with sample thickness of 1.0mm. The effective absorption bandwidth of the composite material shows a decreasing trend with the corresponding sample thickness as the Mxene addition increases, reducing by 50% from 1.5mm without Mxene addition to 1mm with 90mg Mxene addition. These findings provide valuable insights for optimizing absorption coating thickness and weight.

Research Article
Interplay between temperature-dependent strengthening mechanisms and mechanical stability in high-performance austenitic stainless steels
Mohammad Javad Sohrabi, Hamed Mirzadeh, Saeed Sadeghpour, Milad Zolfipour Aghdam, Abdol Reza Geranmayeh, and  Reza Mahmudi
, Available online 19 April 2024, https://doi.org/10.1007/s12613-024-2919-3
Abstract:

The effects of deformation temperature on the transformation-induced plasticity (TRIP)-aided 304L, twinning-induced plasticity (TWIP)-assisted 316L, and highly-alloyed stable 904L austenitic stainless steels were compared for the first time to tune the mechanical properties, strengthening mechanisms, and strength-ductility synergy. For this purpose, the scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), X-ray diffraction (XRD), tensile testing, work-hardening analysis, and thermodynamics calculations were used. The induced plasticity effects led to a high temperature-dependency of work-hardening behavior in the 304L and 316L stainless steels. As the deformation temperature increased, the metastable 304L stainless steel showed the sequence of TRIP, TWIP, and weakening of the induced plasticity mechanisms; while the disappearance of the TWIP effect in the 316L stainless steel was also observed. However, the solid-solution strengthening in the 904L superaustenitic stainless steel maintained the tensile properties over a wide temperature range, surpassing the performance of 304L and 316L stainless steels. In this regard, the dependency of the total elongation on the deformation temperature was less pronounced for the 904L alloy due to the absence of additional plasticity mechanisms. These results revealed the importance of solid-solution strengthening and the associated high friction stress for superior mechanical behavior over a wide temperature range.

Research Article
Construction of attapulgite-based 1D nano-network composites with corrosion resistance for efficient microwave absorption
Kai Xu, Qingqing Gao, Shaoqi Shi, Pei Liu, Yinxu Ni, Zhilei Hao, Gaojie Xu, Yan Fu, and  Fenghua Liu
, Available online 18 April 2024, https://doi.org/10.1007/s12613-024-2917-5
Abstract:

Exploring high-efficient and broadband microwave absorption (MA) materials with corrosion resistance and low cost is urgently needed for widely practical applications. Herein, the natural porous attapulgite (ATP) nanorods embedded with TiO2 and polyaniline (PANI) nanoparticles are synthesized via heterogeneous precipitation and in-situ polymerization. The obtained PANI-TiO2-ATP one-dimensional nanostructures can intertwine into three-dimensional conductive network, which is favored for the energy dissipation. The minimum reflection loss (RLmin) of PANI-TiO2-ATP coating (20wt%) reaches -49.36 dB at 9.53 GHz,and the effective absorption bandwidth (EAB) can reach 6.53 GHz with a thickness of 2.1 mm. The excellent microwave absorption properties are attributed to the interfacial polarization, multiple losses mechanisms and good impedance matching induced by the synergistic effect of PANI-TiO2 nanoparticle shells and ATP nanorods. In addition, salt spray and Tafel polarization curve tests reveal that the PANI-TiO2-ATP coating shows outstanding corrosion resistance performance. This study provides a low-cost and high efficiency strategy to construct one dimensional nano-networks composites for microwave absorption and corrosion resistance applications using natural porous ATP nanorods as a carrier.

Research Article
Heterogeneous information phase space reconstruction and stability prediction of filling body-surrounding rock combination
Dapeng Chen, Shenghua Yin, Weiguo Long, Rongfu Yan, Yufei Zhang, Zepeng Yan, Leiming Wang, and  Wei Chen
, Available online 18 April 2024, https://doi.org/10.1007/s12613-024-2916-6
Abstract:

The traditional research believes that the filling body can effectively control the stress concentration, while ignoring the problem that the stress distribution of the filling body-surrounding rock combination under high stress conditions is complex and changeable, and the stability is unknown. The current monitoring data processing methods can not fully consider the complexity of monitoring objects, the diversity of monitoring methods, and the dynamics of monitoring data. To solve this problem, this paper proposes a phase space reconstruction and stability prediction method for heterogeneous information of backfill-surrounding rock combination. The three-dimensional monitoring system of large-area filling body-surrounding rock combination in Longshou Mine was constructed by using drilling stress, multi-point displacement meter and inclinometer, and the multi-information such as stress and displacement of filling body-surrounding rock combination was continuously obtained. Combined with the average mutual information method and the false nearest neighbour point method, the phase space of the heterogeneous information of the filling body-surrounding rock combination is constructed. In this paper, the distance between the phase point and its nearest point is used as the index evaluation distance to evaluate the stability of the filling body-surrounding rock combination. The evaluated distances show a high sensitivity to the stability of the filling body-surrounding rock combination. The new method is applied to calculate the time series of historical evaluated distances for 12 measuring points at Longshou Mine. The moments of mutation in these time series are at least 3 months ahead of the roadway return dates. In the evaluated distance prediction experiments, the ARIMA model has a higher prediction accuracy than the deep learning models (LSTM and Transformer), and its root-mean-square error distribution of the prediction results peaks at 0.26 and outperforms the no-prediction method in 70% of the cases.

Research Article
Pyrometallurgical Recycling of End-of-Life Lithium-Ion Batteries
Juheon Lee, Kwang Won Park, Il Sohn, and  Sanghoon Lee
, Available online 16 April 2024, https://doi.org/10.1007/s12613-024-2907-7
Abstract:

The global importance of lithium-ion batteries (LIBs) has been increasingly underscored with the advancement of high-performance energy storage technologies. However, the end-of-life of these batteries poses significant challenges from environmental, economic, and resource management perspectives. This review paper focuses on the pyrometallurgy-based recycling process of lithium-ion batteries, exploring the fundamental understanding of this process and the importance of its optimization. Centering on the high energy consumption and emission gas issues of the pyrometallurgical recycling process, we systematically analyzed the capital-intensive nature of this process and the resulting technological characteristics. Furthermore, we conducted an in-depth discussion on the future research directions to overcome the existing technological barriers and limitations. This review will provide valuable insights for researchers and industry stakeholders in the battery recycling field.

Research Article
Effect of Nb-V microalloying on hot deformation behavior of medium Mn steels
Yumeng Wang, Qinyi Guo, Bin Hu, and  Haiwen Luo
, Available online 16 April 2024, https://doi.org/10.1007/s12613-024-2914-8
Abstract:

Influence of Nb-V microalloying on hot deformation behavior and microstructures of medium Mn steel (MMS) was investigated by uniaxial hot compression tests. By establishing the constitutive equations for simulating the measured flow curves, we successfully constructed deformation activation energy (Q) maps and processing maps for identifying the region of flow instability. We may conclude the following consequences as the Nb-V alloying of MMS: (i) The critical strain is increased and the increment diminishes with the increasing deformation temperature, suggesting that NbC precipitates could retard dynamic recrystallization (DRX) in MMS more than the solute Nb; (ii) The deformation activation energy of MMS is significantly increased and even more than high Mn steels, suggesting that it retards DRX more than high content of Mn; (iii) The hot workability of MMS is improved by narrowing the hot processing window for the unstable flow stress, in which the mixed presence of both fine recrystallized and coarse unrecrystallized grains has been confirmed.

Research Article
Numerical simulation on the multiphase flow and reoxidation of the molten steel in a two-strand tundish during ladle change
Jingcheng Wang, Zhentong Liu, Wei Chen, Hongliang Chen, and  Lifeng Zhang
, Available online 16 April 2024, https://doi.org/10.1007/s12613-024-2909-5
Abstract:

In the current study, a three-dimensional mathematical model was proposed to investigate the molten steel-slag-air multiphase flow in a two-strand slab continuous casting (CC) tundish during ladle change, focusing on the exposure of the molten steel and the subsequent occurrence of reoxidation. The exposure of the molten steel was calculated using the coupled realizable k-ε model, volume of fluid (VOF) model. The diffusion of dissolved oxygen was calculated by solving the user defined scalar (UDS) equation. And the user defined function (UDF) was used to define the source term in the UDS equation, determined the oxidation rate and oxidation position. The effect of the refilling speed on the molten steel exposure and dissolved oxygen content was discussed. Increasing the refilling speed during ladle change led to a reduction in both the refilling time and the exposure duration of the molten steel. However, the higher refilling speed resulted in the enlargement of slag eyes and an increase in the average dissolved oxygen content within the tundish, thereby exacerbating the reoxidation phenomenon. Additionally, the time required for the molten steel with a high dissolved oxygen content to exit the tundish varied with the refilling speed. Under refilling conditions with an inlet speed of 3.0 m/s during ladle change, the molten steel with a high dissolved oxygen content exited the outlet in a short period, reaching a maximum dissolved oxygen content of 0.000525wt%. Conversely, when the inlet speed was 1.8 m/s, the maximum dissolved oxygen content was 0.000382wt%. It was recommended to appropriately decrease the refilling speed during ladle change process to minimize reoxidation effects and enhance the quality of the steel product.

Research Article
Viscosity and structure relationship with equimolar substitution of CaO with MgO in the CaO-MgO-Al2O3-SiO2 slag melts
Yong Hou, Shuo Zhang, Jie Dang, Jia Guo, Hanghang Zhou, and  Xuewei Lv
, Available online 16 April 2024, https://doi.org/10.1007/s12613-024-2913-9
Abstract:

Currently, the Al2O3 content in the high-alumina slag systems within blast furnaces is generally limited to 16-18.5wt%, making it challenging to overcome this limitation. Unlike most studies that concentrated on managing the MgO/Al2O3 ratio or basicity, this paper explored the effect of equimolar substitution of MgO for CaO on the viscosity and structure of a high-alumina CaO‐MgO‐Al2O3‐SiO2 slag system, providing theoretical guidance and data to facilitate the application of high-alumina ores. The results revealed that the viscosity first decreased and then increased with higher MgO substitution, reaching a minimum at 15mol% MgO concentration. FTIR results found that the depths of the troughs representing [SiO4] tetrahedra, [AlO4] tetrahedra, and Si-O-Al bending became progressively deeper with increased MgO substitution. Deconvolution of the Raman spectra showed that the average number of bridging oxygens per Si atom and the Q3/Q2 ratio increased from 2.30 and 1.02 to 2.52 and 2.14, respectively, indicating a progressive polymerization of the silicate structure. XPS results highlighted that non-bridging oxygen content decreased from 77.97mol% to 63.41mol% with increasing MgO concentration, whereas bridging oxygen and free oxygen contents increased. Structural analysis demonstrated a gradual increase in the degree of polymerization of the tetrahedral structure with the increase in MgO substitution. However, bond strength is another important factor affecting the slag viscosity. The occurrence of a viscosity minimum can be attributed to the complex evolution of bond strengths of non-bridging oxygens generated during depolymerization of the [SiO4] and [AlO4] tetrahedral structures by CaO and MgO.

Research Article
Structural design and controllable preparation of SiCNWs@Fe3O4@NC nanocomposites for electromagnetic wave absorption
Wenxin Zhao, Meng Zhang, Yukun Miao, Chang Wang, Anguo Cui, Liying Yuan, Zeqing Miao, Xiaoqing Wang, Zhibo Wang, Haoyu Pang, Alan Meng, Zhenjiang Li, and  Ting Wang
, Available online 16 April 2024, https://doi.org/10.1007/s12613-024-2911-y
Abstract:

Using SiC nanowires (SiCNWs) as the substrate, the reflux-annealing method and electro-deposition-carbonization technique were sequentially applied to integrate SiC nanowires with magnetic Fe3O4 nanoparticles and amorphous nitrogen-doped carbon (NC), resulting in the fabrication of SiCNWs@Fe3O4@NC nanocomposite. Comprehensive testing and characterization of this product have provided valuable insights into the impact of structural and composition changes on its electromagnetic wave absorption performances. The optimized SiCNWs@Fe3O4@NC nanocomposite, containing a 30 wt% filler content and a matching thickness of 2.03 mm, demonstrates exceptional performance with a minimum reflection loss (RLmin) of -53.69 dB at 11.04 GHz and an effective absorption bandwidth (EAB) of 4.4 GHz. This investigation thoroughly elucidates the synergistic effects of the enhanced nanocomposites on electromagnetic wave absorption, drawing on theories of multiple scattering, polarization relaxation, hysteresis loss and eddy current loss. Furthermore, a multi-component electromagnetic wave attenuation model has been established, providing valuable insight for designing novel absorbing materials and enhancing their absorption performances. This research demonstrates the significant potential of the SiCNWs@Fe3O4@NC nanocomposite as a highly efficient electromagnetic wave absorbing material, with potential applications in various fields, such as stealth technology and microwave absorption.

Research Article
Al3+ doped CeO2 for proton-conducting fuel cells
Sarfraz Rana, Shahzad Rasool, Khalid Muhammad, M.A.K. Yousaf Shah, Bin Zhu , Sik-Kim Jung, Muhammad Imran Asghar, Nabeela Akbar, and  Wenjing Dong
, Available online 16 April 2024, https://doi.org/10.1007/s12613-024-2910-z
Abstract:

Developing high ionic conducting electrolytes is crucial for applying proton-conducting fuel cell (PCFCs) practically. The current study investigates the effect of alumina on the structural, morphological, electrical and electrochemical properties of CeO2. Lattice oxygen vacancies are induced in CeO2 by a general doping concept that enables fast ionic conduction at low-temperature ranges (300-500 ℃)  for PCFCs. Rietveld refinement of the XRD patterns established the pure cubic fluorite structure of Al-doped CeO2 (ADC) samples and confirmed Al ions integration in the CeO2 lattice. The electronic structure of the alumina-doped ceria of the materials (10ADC, 20ADC, and 30ADC) has been investigated. As a result, it was found that the best composition of 30ADC-based electrolytes induced maximum lattice oxygen vacancies. The corresponding PCFC exhibited a maximum power output of 923 mW/cm2 at 500 ℃. Moreover, the investigation proves the proton-conducting ability of alumina-doped ceria-based fuel cells by using an oxide ion-blocking layer.

Research Article
Enhanced ferroelectric and improved leakage of BFO-based thin films through increasing entropy strategy
Dongfei Lu, Guoqiang Xi, Hangren Li, Jie Tu, Xiuqiao Liu, Xudong Liu, Jianjun Tian, and  Linxing Zhang
, Available online 16 April 2024, https://doi.org/10.1007/s12613-024-2915-7
Abstract:

BiFeO3 (BFO) has received much attention as a lead-free ferroelectric film due to its large theoretical remnant polarization, but it suffers from a large leakage current, resulting in poor ferroelectric properties. Herein, a series of BFO-based thin films were deposited on fluorine-doped tin oxide (FTO) substrates by the sol-gel method, and the effects of the mixed substitution of the elements Co, Cu, Mn (B-site) and Sm, Eu, La (A-site) on the crystal structure, ferroelectricity, and leakage current of the BFO-based thin films were investigated. It is confirmed that the substitution of individual elements in the BFO-based films caused lattice distortion by X-ray diffraction. Sm and Eu substitutions make the lattice distorted to a pseudo-cubic structure, while La is biased toward pseudo-tetragonal. Piezoelectric force microscopy confirms that the prepared films can achieve reversible switching of ferroelectric domains by nearly 180°. The ferroelectric hysteresis loops shows that the order for the polarization contribution is: Cu>Co>Mn (B-site), Sm>La>Eu (A-site). And the current density voltage curves indicate that the order for leakage contribution is: Mn<Cu<Co (B-site), La<Eu<Sm (A-site). The scanning electron microscopy shows that the introduction of Cu element favors the formation of dense grains, and the grain size distribution statistics prove that La element favors the reduction of grain size, which leads to the increase of grain boundaries and the reduction of leakage. Finally, we prepared Bi0.985Sm0.045La0.03Fe0.96Co0.02Cu0.02O3 (SmLa-CoCu) thin film with a qualitative leap in the remnant polarization from 25.5 (Bi0.985Sm0.075FO3) to 98.8 µC/cm2 (SmLa-CoCu) through the synergistic action of Sm, La, Co, and Cu elements. And the leakage current is also significantly reduced from 160 to 8.4 mA/cm2 at a field strength of 150 kV/cm. Thus, the present study focuses on the notion of enhancing ferroelectricity and decreasing leakage current, based on chemical engineering increasing entropy strategy, which provides a promising path for the advancement of ferroelectric devices.

Research Article
Instrumented oscillographic study of impact toughness of an axle steel DZ2 with different tempering temperatures
Shuo Liu, Peng Zhang, Bin Wang, Kaizhong Wang, Zikuan Xu, Fangzhong Hu, Xin Bai, Qiqiang Duan, and  Zhefeng Zhang
, Available online 16 April 2024, https://doi.org/10.1007/s12613-024-2908-6
Abstract:

Compared with the conventional Charpy impact test method, the oscillographic impact test can help analyze the behaviors of the material during the fracture process. This study evaluated the trade-off relationship between strength and toughness of DZ2 axle steel at different tempering temperatures and the reason why impact toughness improved. It is recognized that the tempering process dramatically influenced carbide precipitation behavior, causing different aspect ratios of carbides. It is found that the improvement of impact toughness along with tempering temperature is mainly due to the increase in energy required during the impact crack propagation. The characteristics of the impact crack propagation process are studied through a comprehensive analysis of the stress distribution, oscilloscopic impact statistics, fracture morphology, and carbide morphology. The reason why impact toughness of low tempering temperature specimens is poor are the presence of more stress concentration points due to the morphology of carbides in the small plastic zone during the propagation process, resulting in a mixed distribution of brittle and ductile fractures on the fracture surface.

Research Article
Highly mass activity electrocatalysts with ultra-low Pt loading on carbon black for hydrogen evolution reaction
Shaorou Ke, Yajing Zhao, Xin Min, Yanghong Li, Ruiyu Mi, Yangai Liu, Xiaowen Wu, Minghao Fang, and  Zhaohui Huang
, Available online 16 April 2024, https://doi.org/10.1007/s12613-024-2912-x
Abstract:

Pt-based nanocatalysts have remarkable prospect for industry. However, the low loading of Pt with excellent performance for efficient and stable nanocatalysts still remains highly challenging. Here, nanocatalysts with ultralow Pt content and excellent performance supported on carbon black are designed by in-situ synthesis. These ~2 nm particles uniformly and stably dispersed on carbon black due to the strong s-p-d orbital hybridizations between carbon black and Pt which suppressed the agglomeration of Pt ions. This unique structure is beneficial for the hydrogen evolution reaction. The catalysts exhibited remarkable catalytic activity for hydrogen evolution reaction with a potential of 100 mV at 100 mA cm-2, comparable to commercial Pt/C; and mass activity (1.61 A/mg) is four times higher than that of commercial Pt/C (0.37 A/mg). The ultralow Pt loading of 6.84wt% paves the way for the development of next generation electrocatalysts.

Research Article
Evolution of non-metallic inclusions in 80-tonne 9CrMoCoB large-scale ingots during electroslag remelting (ESR) process
Shengchao Duan, Min Joo Lee, Yao Su, Wangzhong Mu, Dong Soo Kim, and  Joo Hyun Park
, Available online 8 April 2024, https://doi.org/10.1007/s12613-024-2905-9
Abstract:

Experiments to investigate the evolution behavior of non-metallic inclusion (NMI) during the manufacturing of large-scale heat-resistant steel ingot were conducted using 9CrMoCoB heat-resistant steel and CaF2-CaO-Al2O3-SiO2-B2O3 ESR type slag in an 80-tonne industrial electroslag remelting (ESR) furnace in combination with the theoretical calculations. The main types of NMI in the consumable electrode are pure alumina, a multiphase oxide consisting of an Al2O3 core and liquid CaO-Al2O3-SiO2-MnO shell, and M23C6 carbides with MnS core. The precipitation temperatures of the Al2O3 and MnS inclusions was higher than that of M23C6-type carbide under the equilibrium and nonequilibrium solidification process, therefore the inclusions can act as nucleation sites for the precipitation of the carbide layer. The liquid CaO-Al2O3-SiO2-MnO oxide and MnS inclusion with carbide shell were completely removed during the ESR process, only Al2O3 inclusions and Al2O3-core with a carbide shell can be observed in the remelted ingot. The M23C6-type carbides in the steel were determined as Cr23C6 based on the analysis of TEM results, the substitution of W, Fe, or/and Mo for Cr in the Cr23C6 lattice can slightly change the lattice parameter of Cr23C6 carbide, therefore Cr21.34Fe1.66C6, (Cr19W4)C6, Cr18.4Mo4.6C6, and Cr16Fe5Mo2C6 can match the fraction pattern of the Cr23C6 carbide. The formation of Al2O3 inclusions in the remelted ingot could result from the reduction of CaO, SiO2, and MnO components in the liquid inclusion the increased Al content in the liquid steel or the supersaturation degree for the Al2O3 precipitation in the remelted ingot was higher than that in the electrode, the rationale behind the fact is that the evaporation of CaF2 and increase of CaO content in the ESR type slag.

Research Article
Behavior and mechanism of pre-oxidation improvement on fluidization in the fluidized reduction of titanomagnetite
Haoyan Sun, Ajala Adewole Adetoro, zhiqiang Wang, and  Qingshan Zhu
, Available online 8 April 2024, https://doi.org/10.1007/s12613-024-2904-x
Abstract:

The direct reduction process is an important development direction of low-carbon iron-making and efficient comprehensive utilization of poly-metallic iron ore, such as titanomagnetite. However, the defluidization of reduced iron particles with a high metallization degree at a high temperature will seriously affect the operation of fluidized bed reduction. Coupling the pre-oxidation enhancing reduction and the particle surface modification of titanomagnetite, the behavior and mechanism of pre-oxidation improvement on fluidization in the fluidized bed reduction of titanomagnetite are systematically studied in this paper. Pre-oxidation treatment of titanomagnetite can significantly lower the critical stable reduction fluidization gas velocity to 0.17 m/s while achieving a metallization degree > 90%, which is reduced by 56% compared to the critical gas velocity of titanomagnetite without pre-oxidation. Corresponding to the different reduction fluidization behaviors, three pre-oxidation operation regions have been divided, taking oxidation degrees 26% and 86% as the boundaries. Focusing on the particle surface morphology evolution in the pre-oxidation – reduction process, the relationship between the surface morphology of pre-oxidized ore and reduced iron with fluidization properties is built. The improving method of pre-oxidation on the reduction fluidization provides a novel approach to prevent defluidization by particle surface modification, especially for the fluidized bed reduction of poly-metallic iron ore.

Research Article
Study on structure and corrosion behavior of FeCoCrNiMo high-entropy alloy coatings prepared by mechanical alloying and plasma spraying
Yun Tian, Jianing Liu, Mingming Xue, Dongyao Zhang, Yuxin Wang, Keping Geng, Yanchun Dong, and  Yong Yang
, Available online 8 April 2024, https://doi.org/10.1007/s12613-024-2902-z
Abstract:

To overcome the problem of element segregation in high entropy alloys and prepare uniform high entropy alloy coatings, FeCoCrNiMox composite powders were prepared by mechanical alloying technique, and it was prepared into high entropy alloy coatings with FCC phase by plasma spraying. The microstructure and phase composition of the coating were characterized by SEM, TEM, and X-ray diffraction. The coating’s hardness, elastic modulus, and fracture toughness were tested and the corrosion resistance was analyzed in simulated seawater. The results show that the hardness of the coating is 606.15 HV, the modulus of elasticity is 128.42 GPa and the fracture toughness is 43.98 MPa•m1/2. The corrosion potential of the coating in 3.5 wt.% NaCl solution is -0.49 V and the corrosion current density is 1.2×10-6A/〖cm〗^2. The electrochemical system consists of three parts: electrolyte, adsorption film and metallic oxide film produced during immerse, and FeCoNiCrMo high-entropy alloy coating. Over increasingly long periods, the corrosion reaction rate increases first and then decreases, the corrosion product film composed of metal oxides reaches a dynamic balance between formation and dissolution, and the internal reaction of the coating slows down.

Research Article
Alkyl chain modulation of asymmetric hexacyclic fused acceptor synergistically with wide bandgap third component for high efficiency ternary organic solar cells
Shufang Li, Huilan Guan, Can Zhu, Chaoyuan Sun, Qingya Wei, Jun Yuan, and  Yingping Zou
, Available online 8 April 2024, https://doi.org/10.1007/s12613-024-2903-y
Abstract:

Herein, two asymmetric hexacyclic fused small molecule acceptors (SMAs), namely BP4F-HU and BP4F-UU, were synthesized. The elongated outside chains in the BP4F-UU molecule played a crucial role in optimizing the morphology of blend film, thereby improving charge mobility and reducing energy loss within the corresponding film. Notably, the PM6:BP4F-UU device exhibited a higher open-circuit voltage (Voc) of 0.878 V compared to the PM6:BP4F-HU device with a Voc of 0.863 V. Further, a new wide bandgap SMA named BTP-TA was designed and synthesized as the third component to the PM6:BP4F-UU host binary devices, which showed an ideal complementary absorption spectrum in PM6:BP4F-UU system. In addition, BTP-TA can achieve efficient intermolecular energy transfer to BP4F-UU by fluorescence resonance energy transfer (FRET) pathway, due to the good overlap between the photoluminescence (PL) spectrum of BTP-TA and the absorption region of BP4F-UU. Consequently, ternary devices with 15wt% BTP-TA exhibits broader photon utilization, optimal blend morphology and reduced charge recombination compared to the corresponding binary devices. Consequently, PM6:BP4F-UU:BTP-TA ternary device achieved an optimal PCE of 17.83% with simultaneously increased Voc of 0.905 V, short-circuit current density (Jsc) of 26.14 mA/cm2, and fill factor (FF) of 75.38%.

Research Article
Theory, technology and application of grouted bolting in soft rock roadways of deep coal mines
Hongpu Kang, Jianwei Yang, Pengfei Jiang, Fuqiang Gao, Wenzhou Li, Jiafeng Li, and  Huiyuan Chen
, Available online 8 April 2024, https://doi.org/10.1007/s12613-024-2906-8
Abstract:

The grouted bolt combined rock bolting with grouting techniques, providing an effective solution for controlling the surrounding rock in deep soft rock and fractured roadway. It had been extensively applied in numerous deep mining areas with soft rock roadways and achieved remarkable control results. The development history of grouted bolting theory, design methods, materials, construction processes, parameter monitoring instruments, and effect detection methods was systematically introduced. The overview encompassed several key elements. It delved into anchoring theory and grouting reinforcement theory. The new principle of high pre-mining stress-high-pressure splitting grouted bolting collaborative active control was introduced. A fresh method for dynamic information design was also highlighted. The discussion touched on both conventional grouting rock bolts and cable bolts, as well as the innovative grouted rock bolts and cables characterized by their high pre-tension, strength, and sealing hole pressure. There was an examination of the merits and demerits of standard inorganic and organic grouting materials versus the new inorganic-organic composite materials, including their specific application conditions. The article presented various methods and instruments to assess the support effect of grouting rock bolts, cable bolts, and grouting reinforcement. Furthermore, it provided a foundation for understanding the factors influencing the decision on grouted bolting timing, the sequence of grouting, grouting pressure, the volume of grout used, and the arrangement of grouted rock bolts and cable bolts. The application of the pretensoined high-pressure splitting grouted bolting collaborative control technology in the typical kilometer-deep soft rock mine in China—the soft coal seam and soft rock roadway in the Kizidong coal mine, Huainan coal mining area, was introduced. Finally, the problems existing in grouted bolting control technology for the deep soft rock roadways were analyzed, and the future development trend of grouted bolting control technology was anticipated.

Research Article
High-temperature corrosion of sintered RE2Si2O7 (RE = Yb, Ho) environmental barrier coating materials by volcanic ash
Ayahisa Okawa, Son Thanh Nguyen, Tadachika Nakayama, Thi-Mai-Dung Do, Hisayuki Suematsu, Shu Yin, Takuya Hasegawa, Tsuneo Suzuki, Takashi Goto, and  Koichi Niihara
, Available online 3 April 2024, https://doi.org/10.1007/s12613-024-2899-3
Abstract:

Rare earth silicates are promising candidates for environmental barrier coatings (EBCs) to protect SiCf/SiCm substrates in next-generation gas turbine blades. Notably, RE2Si2O7 (RE = Yb, Ho) shows potential due to a coefficient of thermal expansion (CTE) that is compatible with the substrates, as well as its excellent water vapor corrosion resistance. The target operating temperature for next-generation turbine blades is set at 1400 °C. Therefore, the corrosion from adhering molten volcanic ash becomes inevitable, making it crucial to understand this corrosion behavior to ensure reliability. This study investigates the high-temperature corrosion behavior of sintered RE2Si2O7 (RE = Yb, Ho). The samples were prepared using a solid-state reaction and hot press method. They were then exposed to volcanic ash at 1400 °C for 2, 24, and 48 h. After 48 h of exposure, volcanic ash did not react with Yb2Si2O7 but penetrated through its interior, causing damage. Meanwhile, Ho2Si2O7 was partially dissolved in the molten volcanic ash, forming a reaction zone that preventing the penetration of volcanic ash melts into the interior. With increasing heat treatment time, the reaction zone expanded, and the apatite acicular-grain became thicker. The Ca:Si ratios present in the residual volcanic ash were mostly unchanged for Yb2Si2O7 but decreased significantly over time for Ho2Si2O7. The Ca in volcanic ash was consumed to form apatite, indicating that RE3+ ions with large ionic radii (Ho > Yb) easily precipitated apatite from the volcanic ash.

Research Article
Roughness Characterization and Shearing Dislocation Failure for Rock-Backfill Interface
Meifeng Cai, Zhilou Feng, Qifeng Guo, Xiong Yin, Minghui Ma, and  Xun Xi
, Available online 3 April 2024, https://doi.org/10.1007/s12613-024-2901-0
Abstract:

Shearing dislocation is a common failure type for rock-backfill interface due to the backfill sedimentation and rock strata movement in backfill mining goaf. This paper designs a test method for rock-backfill shearing dislocation. By digital image technology and three-dimensional (3D) laser morphology scanning technique, a set of 3D models with rough joint surfaces was established. Further, the mechanical behavior of rock-backfill shearing dislocation was investigated based on the direct shear test. The effects of interface roughness on the shear-displacement curve and failure characteristics of rock-backfill specimens were considered. The 3D fractal dimension, profile line JRC (Joint Roughness Coefficient), profile line two-dimensional fractal dimension and the surface curvature of the fractures were obtained. The correlation characterization of surface roughness was then analyzed, and the shear strength can be measured and calculated through JRC. Results show that: there are 3 failure threshold value points in shearing dislocation of rock-backfill, including 30% to 50% displacement before the peak, 70% to 90% displacement before the peak and 100% displacement before the peak to post-peak, which can be a sign for the shearing dislocation failure of rock-backfill. The surface JRC can be used to judge the shearing dislocation failure of rock-backfill including post-peak sliding, uniform variations and gradient change, corresponding to the dislocation failure of rock-backfill on the field site. The research reveals the damage mechanism for rock-backfill complex based on free joint surface, fills the gap of existing shearing theoretical system for isomerism complex and provides theoretical basis for prevention and control of the possible disasters in backfill mining.

Research Article
A novel low-temperature chlorination roasting technology for simultaneous recovery of valuable metals from spent LiCoO2 cathode material
Junjie Shi, Changle Hou, Jingjing Dong, Dong Chen, and  Jianzhong Li
, Available online 2 April 2024, https://doi.org/10.1007/s12613-024-2898-4
Abstract:

With the continuous rise of the disposal volume for spent lithium-ion batteries (LIBs), properly recycling spent LIBs has become essential for advancing the circular economy. This study presents a systematic analysis of the chlorination-roasting kinetics and proposes a new two-step chlorination-roasting process for recycling lithium-ion battery cathode materials, integrating thermodynamics. The activation energy for the chloride reaction was determined to be 88.41 kJ/mol based on TG-DTG data using model-free, model-fitting, and Z(α) functions. The results indicated that the reaction was dominated by the First order (F1) model when the conversion rate was below 0.5 and shifted the Second order (F2) model when the conversion rate exceeded 0.5. The effects of roasting temperature, roasting time, and the mass ratio of NH4Cl to LiCoO2 were thoroughly investigated to determine the optimal conditions. Under the optimal parameters of 400°C for 20 minutes with a mass ratio of 3:1 for NH4Cl and LiCoO2, the leaching efficiency of Li and Co reached 99.43% and 99.05%, respectively. Analysis of the roasted products revealed that valuable metals in LiCoO2 transformed into CoCl2 and LiCl. Furthermore, to elucidate the reaction mechanism, providing insights into establishing a novel low-temperature chlorination roasting technology based on a crystal structure perspective. This technology can potentially guide the development of low-energy consumption, low-secondary pollution, high-recovery efficiency, and high-added value processes for LIB recycling.

Research Article
Effect of lamellarizing process on the microstructure and mechanical properties of marine 10Ni5CrMoV steel
Tao Zou, Yanwu Dong, Zhouhua Jiang, Shuyang Du, and  Yushuo Li
, Available online 2 April 2024, https://doi.org/10.1007/s12613-024-2897-5
Abstract:

In this work, multi-stage heat treatment involving quenching (Q), lamellarizing (L), and tempering (T) is applied in marine 10Ni5CrMoV steel to study the microstructure and mechanical properties by multi-scale characterizations, kinetics of reverse austenite transformation, strain hardening behavior, and toughening mechanism are further investigated. The specimens treated by lamellarizing process possess low yield strength but high toughness, especially cryogenic toughness. Introducing lamellarizing process leads to the film-like reversed austenite develops at martensite block and lath boundaries, which refines the martensite structure, and possess the lower equivalent grain size. Kinetic analysis of austenite reversion based on JMAK model shows that the isothermal transformation is dominated by the growth of reversed austenite, and there is a peak temperature (750°C) which makes the transformation of reversed austenite reach the maximum. The strain hardening behavior based on the modified Crussad-Jaoul analysis is indicated that reversed austenite obtained by lamellarizing process reduce the proportion of martensite, whereas produce a significant effect to hinder the propagation of cracks via martensitic transformation during the deformation, which are responsible for the QLT specimens exhibit high machinability and low yield strength. The ductile-brittle transition temperature of QLT specimens is decreased from -116°C to -130°C due to the low equivalent grain size and reversed austenite, which increase the cleavage force required for the propagation of cracks, and absorb the energy of external load, respectively. This work provides an idea to improve the cryogenic toughness of marine 10Ni5CrMoV steel, and lays a theoretical foundation for the industrial application and comprehensive performance improvement.

Research Article
Study on the behavior of bubbles escaping from low basicity mold flux for high-Mn high-Al steels using 3D X-Ray microscope
Qiang Liu, Xiang Li, Shen Du, Ming Gao, Yanbin Yin, and  Jiongming Zhang
, Available online 2 April 2024, https://doi.org/10.1007/s12613-024-2896-6
Abstract:

Different types of gases need to escape through the top of the mold during the continuous casting process of high-Mn high-Al steels. The behavior of bubbles passing through the liquid slag is the restrictive link, which is related to the viscosity. Compared with two-dimensional surface observation, three-dimensional analysis is more intuitive, accurate and comprehensive. The spatial distribution and three-dimensional morphological of residual bubbles in mold flux under different basicity, different temperature and different holding time were obtained by three-dimensional X-ray microscope in this paper. The results indicate that when the basicity increases from 0.52 to 1.03, the temperature increases from 1423 K to 1573 K, the holding time increases from 10 s to 30 s, the mean feret diameter of the bubbles solidified in the mold flux gradually decreases. Increasing the basicity and temperature will decrease the viscosity of the mold flux and increase the bubble floating rate, increasing the holding time will increase the bubble floating distance, both leading to an increase in the removal rate of bubbles especially for the large. The findings of bubbles escape behavior provide guidance for the research of functions of low basicity mold flux for high-Mn and high-Al steel.

Research Article
Valuable metals recycling from spent ternary lithium-ion battery: a review
Hao Liao, Shengen Zhang, Bo Liu, Xuefeng He, Jixin Deng, and  Yunji Ding
, Available online 30 March 2024, https://doi.org/10.1007/s12613-024-2895-7
Abstract:

The ternary lithium-ion batteries (LIBs), widely used in new energy vehicles and electronic products, is known for its high energy density, wide operating temperature range, and excellent cycling performance. With the rapid development of the battery industry, the recycling of spent LIBs, due to their economic value and environmental concerns, has become a hot topic. To date, there is a wealth of literature on the recycling of spent LIBs, being designed to provide an efficient, economical, and environmentally friendly method for battery recycling. This article examines the latest developments in various technologies for recycling spent LIBs in both research and practical production, including pretreatment, pyrometallurgy, hydrometallurgy, pyro-hydrometallurgy, and direct regeneration. Suggestions are made for addressing challenges based on the benefits and disadvantages of each method. Finally, through a comparison of the feasibility and economic benefits of various technologies, the challenges faced by battery recycling are summarized, and future development directions are proposed.

Research Article
A study of electromagnetic responses on microstructures of duplex stainless steels using 3D cellular and electromagnetic sensor FE models
Shuaishuai Xiao, Jialong Shen, Jianing Zhao, Jie Fang, Caiyu Liang, and  Lei Zhou
, Available online 29 March 2024, https://doi.org/10.1007/s12613-024-2894-8
Abstract:

Microstructures determine mechanical properties of steels, but in actual steel product process it is difficult to accurately control the microstructure to meet the requirements. General microstructure characterization methods are time consuming and results are not representative for overall quality level as only a fraction of steel sample was selected to be examined. In this paper, a macro and micro coupled 3D model was developed for non-destructively characterization of steel microstructures. For electromagnetic signals analysis, the relative permeability value computed by the micro cellular model can be used in the macro electromagnetic sensor model. The effects of different microstructure components on the relative permeability of duplex stainless steel (grain size, phase fraction and phase distribution) were discussed. The output inductance of an electromagnetic sensor was determined by relative permeability values and can be validated experimentally. The findings indicate that the inductance value of an electromagnetic sensor at low frequency can distinguish different microstructures. This method can be applied to real-time on-line characterize steel microstructures in process of steel rolling.

Research Article
Shear mechanical properties and fracturing responses of layered rough jointed rock-like materials
Xinxin Nie, Qian Yin, Manchao He, Qi Wang, Hongwen Jing, Bowen Zheng, Bo Meng, Tianci Deng, Zheng Jiang, and  Jiangyu Wu
, Available online 29 March 2024, https://doi.org/10.1007/s12613-024-2893-9
Abstract:

This study aims to investigate mechanical properties and failure mechanisms of layered rock with rough joint surfaces under direct shear loading. Cubic layered samples with dimensions of 100 × 100 × 100 mm were casted using rock-like materials, with anisotropic angle (α) and joint roughness coefficient (JRC) ranging from 15° to 75° and 2 ~ 20, respectively. The direct shear tests were conducted under the application of initial normal stress (σn) ranging from 1 ~ 4 MPa. The test results indicate significant differences in mechanical properties, acoustic emission (AE) responses, maximum principal strain fields, and ultimate failure modes of layered samples under different test conditions. The peak stress increases with the increasing α and achieves a maximum value at α = 60° or 75°. As σn increases, the peak stress shows an increasing trend, with correlation coefficients R² ranging from 0.918 to 0.995 for the linear least squares fitting. As JRC increases from 2 ~ 4 to 18 ~ 20, the cohesion increases by 86.32% when α = 15°, while the cohesion decreases by 27.93% when α = 75°. The differences in roughness characteristics of shear failure surface induced by α result in anisotropic post-peak AE responses, which is characterized by active AE signals when α is small and quiet AE signals for a large α. For a given JRC = 6 ~ 8 and σn = 1 MPa, as α increases, the accumulative AE counts increase by 224.31% (α increased from 15° to 60°), and then decrease by 14.68% (α increased from 60° to 75°). The shear failure surface is formed along the weak interlayer when α = 15° and penetrates the layered matrix when α = 60°. When α = 15°, as σn increases, the adjacent weak interlayer induces a change in the direction of tensile cracks propagation, resulting in a stepped pattern of cracks distribution. The increase in JRC intensifies roughness characteristics of shear failure surface for a small α, however, it is not pronounced for a large α. The findings will contribute to a better understanding of the mechanical responses and failure mechanisms of the layered rocks subjected to shear loads.

Research Article
Enhancing the mechanical properties of casting eutectic high entropy alloys via W addition
Xu Yang, Dezhi Chen, Li Feng, Gang Qin, Shiping Wu, and  Ruirun Chen
, Available online 23 March 2024, https://doi.org/10.1007/s12613-024-2892-x
Abstract:

In order to explore the effect of W element on the microstructure evolution and mechanical properties of Al1.25CoCrFeNi3 eutectic high entropy alloy (EHEA), Al1.25CoCrFeNi3-xWx (x=0, 0.05, 0.1, 0.3, 0.5) high entropy alloys (HEAs) were designed and prepared. Results show that Al1.25CoCrFeNi3Wx HEAs are composed of FCC phase and BCC phase. With the increase of W element, the microstructure changes from eutectic to dendrite. The addition of W lowers the nucleation barrier of BCC phase, decreases the valence electron concentration (VEC) of HEAs, and replaces Al in BCC phase, thus facilitating the nucleation of BCC phase. Tensile results show that the addition of W significantly improves the mechanical properties. Solid solution strengthening, heterogeneous interface strengthening and second phase strengthening are the main strengthening mechanisms. Yield strength, tensile strength and elongation of W0.05 HEA are 601.44 MPa, 1132.26 MPa and 15.94%, respectively, realizing a balance of strength and plasticity. Fracture mode of Al1.25CoCrFeNi3-xWx HEAs is ductile-brittle mixed fracture, and the crack propagates and initiates in BCC phase. The eutectic lamellar structure slows down the crack propagation rate and maintains the plasticity.

Research Article
Construction of 3D porous Cu1.81S/nitrogen-doped carbon frameworks for ultrafast and long-cycle life sodium-ion storage
Chen Chen, Hongyu Xue, Qilin Hu, Mengfan Wang, Pan Shang, Ziyan Liu, Tao Peng, Deyang Zhang, and  Yongsong Luo
, Available online 22 March 2024, https://doi.org/10.1007/s12613-024-2890-z
Abstract:

Transition metal sulfides have great potential as anode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacities. However, the inferior intrinsic conductivity and large volume variation during sodiation-desodiation processes seriously affect its high-rate and long-cycle performance, unbeneficial for the application as fast-charging and long-cycling SIBs anode. Herein, the three-dimensional porous Cu1.81S/nitrogen-doped carbon frameworks (Cu1.81S/NC) are synthesized by the simple and facile sol-gel and annealing processes, which can accommodate the volumetric expansion of Cu1.81S nanoparticles and accelerate the transmission of ions and electrons during Na+ insertion/extraction processes, exhibiting the excellent rate capability (250.6 mAh g-1 at 20 A g-1) and outstanding cycling stability (70% capacity retention for 6000 cycles at 10 A g-1) for SIBs. Moreover, the Na-ion full cells coupled with Na3V2(PO4)3/C cathode also demonstrate the satisfactory reversible specific capacity of 330.5 mAh g-1 at 5 A g-1 and long-cycle performance with the 86.9% capacity retention at 2.0 A g-1 after 750 cycles. This work proposes a promising way for the conversion-based metal sulfides for the applications as fast-charging sodium-ion battery anode.

Research Article
A review of in-situ high-temperature characterizations for understanding processes of metallurgical engineering
Yifan Zhao, Zhiyuan Li, Shijie Li, Weili Song, and  Shuqiang Jiao
, Available online 22 March 2024, https://doi.org/10.1007/s12613-024-2891-y
Abstract:

For rationally manipulating the production quality of high-temperature metallurgical engineering, there are great challenges in understanding the processes owing to the dark-box chemical/electrochemical reactors. To overcome this issues, various in-situ characterization methods have been recently developed to study the interactions between the composition, micro-structure and solid-liquid interface of high-temperature electrochemical electrodes and molten salts. In this review, recent progresses of in-situ high-temperature characterization techniques are discussed to summarize the advances of understanding processes in metallurgy engineering. In-situ high-temperature technologies and analytic methods mainly include synchrotron X-ray diffraction (s-XRD), laser confocal microscopy (LSCM) and X-ray computed microtomography imaging (CT), which are important platform for analyzing the structure and morphology of the electrodes to reveal the complexity and variability of the electrode interfaces. In addition, laser-induced breakdown spectroscopy (LIBS), high-temperature Raman microspectroscopy and ultraviolet-visible spectroscopy (UV-vis) provide microscale characterizations on the composition and structure of molten salts. More importantly, the combination of CT and s-XRD techniques enables to investigate the chemical reaction mechanisms at the two-phase interface. Therefore, these in-situ methods are essential for analyzing the chemical/electrochemical kinetics of high-temperature reaction processes, establishing theoretical principles for the efficient and stable operation of chemical/electrochemical metallurgical processes.

Research Article
Effect of two-step solid solution on microstructure and δ phase precipitation of Inconel 718 alloy
Enyu Liu, Qingshuang Ma, Xintong Li, Aoxue Gao, Jing Bai, Liming Yu, Qiuzhi Gao, and  Huijun Li
, Available online 21 March 2024, https://doi.org/10.1007/s12613-024-2887-7
Abstract:

Inconel 718 is the most popular nickel-based superalloy, extensively used in aerospace, automotive and energy industries owing to its extraordinary thermomechanical properties. The effects of different two-step solid solution treatments on microstructure and δ phase precipitation of Inconel 718 alloy were studied, and the transformation mechanism from γ" metastable phase to δ phase was clarified. The precipitates were statistically analysed by X-ray diffractometer test results. The results show that the content of δ phase increased with the increase in second step solid solution temperature. The changes of microstructure and δ phase were studied by scanning electron microscopy and transmission electron microscopy. Intragranular δ phase formed in Inconel 718 alloy with a second step solid solution temperature of 925°C, and its orientation relationship with γ matrix was determined as [1(—)00]δ//[011(—)]γ and (010)δ//(111)γ. Furthermore, Vickers hardness of different heat treatment samples was measured, and hardness of sample treated by second step solid solution treatment at 1010°C reached the maximum value of 446.84 HV.

Research Article
Preparation of FeCoNi medium entropy alloy from Fe3+-Co2+-Ni2+ solution system
Zongyou Cheng, Qing Zhao, Mengjie Tao, Jijun Du, Xingxi Huang, and  Chengjun Liu
, Available online 21 March 2024, https://doi.org/10.1007/s12613-024-2888-6
Abstract:

In recent years, medium entropy alloys have become a research hotspot due to their excellent physical and chemical performances. By controlling reasonable elemental composition and processing parameters, the medium entropy alloys can exhibit similar properties to high entropy alloys and have lower preparation costs. In this paper, a FeCoNi medium entropy alloy precursor was prepared via sol-gel and co-precipitation methods, respectively, and FeCoNi medium entropy alloys were prepared by carbothermal and hydrogen reduction. The phases and magnetic properties of FeCoNi medium entropy alloy were investigated. Results showed that the decompose temperature of the precursor prepared by sol-gel and co-precipitation methods was 369 °C and 834 °C, respectively. FeCoNi medium entropy alloy was produced by carbothermal and hydrogen reduction at 1500 °C. Some carbon was detected in the FeCoNi medium entropy alloy prepared by carbothermal reduction. The FeCoNi medium entropy alloy prepared by hydrogen reduction had uniform composition, and showed a relative high purity. Moreover, hydrogen reduction product exhibited a higher saturation magnetization and lower coercivity.

Research Article
High-entropy ferrite with tunable magnetic properties for excellent microwave absorption
Yuying Huo, Zhengyan Wang, Yanlan Zhang, and  Yongzhen Wang
, Available online 19 March 2024, https://doi.org/10.1007/s12613-024-2883-y
Abstract:

High-entropy design is attracting growing interest as it offers unique structures and unprecedented application potential for materials. In this article, a novel high-entropy ferrite (CoNi)x/2(CuZnAl)(1-x)/3Fe2O4 (x = 0.25, 0.34, 0.40, 0.50) with a single spinel phase of space group Fd-3m was successfully developed by the solid-state reaction method. By tuning the Co-Ni content, the magnetic properties of the material, especially the coercivity, changed regularly, and the microwave absorption properties were improved. In particular, the effective absorption bandwidth of the material increased from 4.8 GHz to 7.2 GHz, and the matched thickness decreased from 3.9 mm to 2.3 mm, while the minimum reflection loss remained below -20 dB. This study provides a practical method for modifying the properties of ferrites used to absorb electromagnetic waves.

Research Article
Effects of cement content, polypropylene fiber length and dosage on fluidity and mechanical properties of fiber–toughened cemented aeolian sand backfill (FCASB)
Shushuai Wang, Renshu YANG, Yongliang Li, and  Zhongwen Yue
, Available online 19 March 2024, https://doi.org/10.1007/s12613-024-2885-9
Abstract:

Using aeolian sand (AS) for goaf backfilling allows coordination of green mining and AS control. Cemented AS backfill (CASB) exhibits brittle fracture. Polypropylene (PP) fibers are good toughening materials. When the toughening effect of fibers is analyzed, their influence on the slurry conveying performance should also be considered. Additionally, cement affects the interactions among the hydration products, fibers, and aggregates. In this study, the effects of cement content (8wt%, 9wt% and 10wt%), PP fiber length (6, 9 and 12 mm) and dosage (0.05wt%, 0.1wt%, 0.15wt%, 0.2wt% and 0.25wt%) on fluidity and mechanical propertity of the fiber–toughened CASB (FCASB) were analyzed. The results indicated that with increases in the three aforementioned factors, the slump flow decreased, while the rheological parameters increased. Uniaxial compressive strength (UCS) increased with the increase of cement content and fiber length, and with an increase in fiber dosage, it first increased and then decreased. The strain increased with the increase of fiber dosage and length. The effect of PP fibers became more pronounced with the increase of cement content. Digital image correlation (DIC) test results showed that the addition of fibers can restrain the peeling of blocks and the expansion of fissure, and reduce the stress concentration of the FCASB. Scanning electron microscopy (SEM) test indicated that the functional mechanisms of fibers mainly involved the interactions of fibers with the hydration products and matrix, and the spatial distribution of fibers. On the basis of single–factor analysis, the response surface method (RSM) was used to analyze the effects of the three aforementioned factors and their interaction terms on the UCS. The influence surface of the two-factor interaction terms and the three-dimensional scatter plot of the three–factor coupling were established. In conclusion, the response law of the FCASB properties under the effects of cement and PP fibers were obtained, which provides theoretical and engineering guidance for FCASB filling.

Research Article
The influence of introducing Zr, Ti, Nb, and Ce elements on the ESCs and mechanical properties of high-pressure die casting Al-Si alloy
Junjie Li, Wenbo Yu, Zhenyu Sun, Weichen Zheng, Liangwei Zhang, Yanling Xue, Wenning Liu, and  Shoumei Xiong
, Available online 15 March 2024, https://doi.org/10.1007/s12613-024-2882-z
Abstract:

High pressure die casting (HPDC) AlSi10MnMg alloy castings are widely used in the automobile industry. Mg can enhance the strength of the alloy with the sacrifice of the ductility. Heat treatment was generally adopted to resolve this drawback. With the development of large integrated die-casting parts, non-heat treatment Al alloys are strongly desired. In addition, the externally solidified crystals (ESCs) are often found in HPDC, which are detrimental to the mechanical properties of castings. In order to achieve high strength and toughness of non-heat treatment die-casting Al-Si alloy, AlSi9Mn alloy is used as matrix with the introduction of Zr, Ti, Nb and Ce elements. Their influences on the ESCs and mechanical properties were systematically investigated by combining three-dimensional reconstruction and thermodynamic simulation. Our results reveal that the addition of Ti element induced the increase of ESCs size and porosity. The following introduction of Nb could refine ESCs and decrease porosity. Meanwhile, the large-sized Al3(Zr, Ti) phases formed and degraded the mechanical properties. It was further confirmed that the subsequent introduction of Ce resulted in the poisoning effect and reduced mechanical properties.

Research Article
NiCoZn/C@melamine sponge-derived carbon composites with high-performance electromagnetic wave absorption
Xiubo Xie, Heshan Wang, Hideo Kimura, Cui Ni, Wei Du, and  Guanglei Wu
, Available online 13 March 2024, https://doi.org/10.1007/s12613-024-2880-1
Abstract:

NiMZn/C@MSDC (M=Co, Fe, Mn, MSDC represents melamine sponge-derived carbon) composites were prepared by the vacuum pumping solution method followed by carbonization process. A large number of carbon nanotubes (CNTs) were homogeneously attached to the surfaces of the 3D cross-linked of the sponge-derived carbon in the NiCoZn/C@MSDC composite, while CNTs can not be detected in NiFeZn/C@MSDC and NiMnZn/C@MSDC composites. Besides the existence of Ni3ZnC0.7, Ni3Fe and MnO in-situ formed in NiFeZn/C@MSDC and NiMnZn/C@MSDC composites. The generated CNTs in NiCoZn/C@MSDC composite efficiently tuned the complex permittivity and thus showed the best microwave absorption performances. The NiCoZn/C@MSDC composite exhibits a RLmin value of -33.1 dB at 18 GHz at a thickness of 1.4 mm. The bandwidth for RL≤-10 dB is up to 5.04 GHz at a thickness of 1.7 mm with a low loading of 25 wt%. The optimized impedance matching, enhanced interfacial and dipole polarization, remarkable conduction loss and multiple reflections and scattering of the incident microwaves improve the microwave absorption performances. The substitution effects of Co, Ni and Fe on the phase and morphology changes provide an alternative way to develop highly efficient and broadband microwave absorbers.

Research Article
A high-strength and thermally stable TiB2-modified Al-Mn-Mg-Er-Zr alloy fabricated via selective laser melting
Jiang Yu, Yaoxiang Geng, Yongkang Chen, Xiao Wang, Zhijie Zhang, Hao Tang, Junhua Xu, Hongbo Ju, and  Dongpeng Wang
, Available online 9 March 2024, https://doi.org/10.1007/s12613-024-2879-7
Abstract:

To increase the processability and plasticity of the selective laser melting (SLM) fabricated Al-Mn-Mg-Er-Zr alloys, a novel TiB2-modified Al-Mn-Mg-Er-Zr alloy with a mixture of Al-Mn-Mg-Er-Zr and nano-TiB2 powders was fabricated via SLM. The processability, microstructure, and mechanical properties of the alloy were systematically investigated by density measurement, microstructure characterization, and mechanical properties testing. The alloys fabricated at 250 W displayed higher relative densities due to a uniformly smooth top-surface and appropriate laser energy input. The maximum relative density value of the alloy reached 99.7±0.1%, demonstrating good processability. The alloy exhibited a duplex grain microstructure consisting of columnar regions primarily and equiaxed regions with TiB2, Al6Mn, and Al3Er phases distributed along the grain boundaries. After directly aging treatment at a high temperature of 400 °C, the strength of the SLM-fabricated TiB2/Al-Mn-Mg-Er-Zr alloy increased due to the precipitation of the secondary Al6Mn phases. The maximum yield strength and ultimate tensile strength of the aging alloy were measured to be 374 ± 1 MPa and 512 ± 13 MPa, respectively. The SLM-fabricated TiB2/Al-Mn-Mg-Er-Zr alloy demonstrates exceptional strength and thermal stability due to the synergistic effects of grain growth inhibition and the incorporation of TiB2 nanoparticles and secondary Al6Mn precipitates.

Research Article
Two-Stage Dynamic Recrystallization and Texture Evolution in an Al-Mg Alloy during Hot Torsion
Kwang-Tae Son, Chang-Hee Cho, Myoung-Gyun Kim, and  Jiwoon Lee
, Available online 8 March 2024, https://doi.org/10.1007/s12613-024-2877-9
Abstract:

Hot torsion tests were performed on the Al-7Mg alloy at temperatures ranging from 300 – 500 °C and strain rates between 0.05 – 5 s-1 to explore the progressive dynamic recrystallization (DRX) and texture behaviors. The DRX behavior of the alloy manifested two distinct stages: Stage 1 at strains of ≤ 2 and Stage 2 at strains of ≥ 2. In Stage 1, there was a slight increase in the DRXed grain fraction (XDRX) with predominance of discontinuous DRX (DDRX), followed by a modest change in XDRX until the transition to Stage 2. Stage 2 was marked by an accelerated rate of DRX, culminating in a substantial final XDRX of ≈ 0.9. EBSD analysis on a sample in Stage 2 revealed that continuous DRX (CDRX) predominantly occurred within the (12 ̅1)[001] grains, whereas the (111)[110] grains underwent a geometric DRX (GDRX) evolution without a noticeable sub-grain structure. Furthermore, a modified Avrami’s DRX kinetics model was utilized to predict the microstructural refinement in the Al-7Mg alloy during the DRX evolution. Although this kinetics model did not accurately capture the DDRX behavior in Stage 1, it effectively simulated the DRX rate in Stage 2. The texture index was employed to assess the evolution of the texture isotropy during hot-torsion test, demonstrating a significant improvement (> 75 %) in texture randomness before the commencement of Stage 2. This initial texture evolution is attributed to the rotation of parent grains and the substructure evolution, rather than to an increase in XDRX.

Research Article
New steelmaking process based on cleaner deoxidation technology
Zhongliang Wang and  Yanping Bao
, Available online 8 March 2024, https://doi.org/10.1007/s12613-024-2878-8
Abstract:

In modern long-process steel production, a blast furnace uses materials such as pulverized coal and coke to reduce iron ore, producing carbon-saturated molten iron. In the converter, molten iron and scrap steel are used as raw materials, and a large amount of oxygen is blown in to achieve decarburization, dephosphorization, and temperature increase, thus obtaining molten steel with high oxygen content. In the refining process, ferroalloys must be added to remove excess oxygen from the initial molten steel. However, this process will cause the deoxidizer added to the molten steel to combine with oxygen, forming a significant amount of oxide inclusions that cannot be completely removed. Furthermore, it requires a substantial consumption of deoxidizing alloys, which increases the carbon emissions in the steel production process. To address these issues, our research team, after years of research, has developed a series of cleaner deoxidation technologies, including carbon deoxidation of molten steel, hydrogen deoxidation of molten steel, and waste plastics deoxidation of molten steel. This technology has undergone multiple hot-state experiments in the laboratory and has been applied in industrial production of non-aluminum deoxidized bearing steel, yielding exce1llent results. This study, through thermodynamic calculations and laboratory hot-state experiments, validated the deoxidation limits of carbon under atmospheric and vacuum conditions. It demonstrated that hydrogen also has the capability to reduce the total oxygen content in molten steel to below 10×10−6. The research also analyzed the deoxidation mechanism and consumption of polyethylene. After adopting cleaner deoxidation technology, the oxygen content of bearing steel can be controlled at 6.3×10−6, reducing the inclusion density by 74.73% compared to aluminum deoxidized bearing steel. In the final deoxidation stage, the use of the cleaner deoxidation technology in non-aluminum deoxidized bearing steel reduces the oxygen content to below 8×10−6. The main composition of oxide inclusions is silicate, along with small amounts of spinel and calcium aluminate. The oxygen content in gear steel can be reduced to 7.7×10−6, with a 54.49% reduction in inclusion density, and it essentially contains no inclusions larger than 5μm. High-speed steel can achieve a total oxygen content as low as 3.7×10−6.

Research Article
Rational construction of heterointerfaces in biomass sugarcane-derived carbon for superior electromagnetic wave absorption
Shijie Zhang, Di Lan, Jiajun Zheng, Xingliang Chen, Ailing Feng, Yaxing Pei, Shichang Cai, Suxuan Du, Guanglei Wu, and  Zirui Jia
, Available online 7 March 2024, https://doi.org/10.1007/s12613-024-2875-y
Abstract:

The pervasive use of 5th generation mobile communication technology is driving electromagnetic wave (EW) absorbents towards high performances. The construction of heterointerfaces is crucial to the improvement of absorption ability. Herein, a series of ultralight composites with rational heterointerfaces (Co/ZnO@N-doped C/layer-stacked C, MSC) are fabricated by calcination with rational construction of sugarcane and CoZn-ZIFs. The components and structures of as-prepared composites were investigated, and their electromagnetic parameters could be adjusted by the content of CoZn-ZIFs. All the composites possess good EW absorption performances, especially for MSC-3. Its optimal minimum reflection loss and effective absorption band can reach to -42 dB and 7.28 GHz at the thickness of just 1.6 mm with 20 wt% filler loading. The excellent performances are attributed to the synergistic effect of dielectric loss stemming from the multiple heterointerfaces and magnetic loss induced by magnetic single Co. And the sugarcane-derived layer-stacked carbon and formed consecutive conductive networks and could further dissipate the electromagnetic energy through multiple reflection and conduction loss. Moreover, the simulated radar cross section (RCS) technology manifests that MSC-3 possesses outstanding EW attenuation capacity under realistic far-field conditions. This study provides a strategy for building efficient absorbents based on biomass.

Research Article
Enhancing corrosion resistance of plasma electrolytic oxidation coatings on AM50 Mg alloy by inhibitor containing Ba(NO3)2 solutions
Jirui Ma, Xiaopeng Lu, Santosh Prasad Sah, Qianqian Chen, You Zhang, and  Fuhui Wang
, Available online 7 March 2024, https://doi.org/10.1007/s12613-024-2876-x
Abstract:

In order to enhance the long-term corrosion resistance of the plasma electrolytic oxidation (PEO) coating on Mg alloy, an inorganic salt is used in combination with corrosion inhibitors for post-treatment of the coating. In this study, corrosion performance of PEO-coated AM50 Mg was significantly improved by sodium lauryl sulfonate (SDS) and sodium dodecyl benzene sulfonate (SDBS) loaded into the Ba(NO3)2 post-sealing solution. SEM, XPS, XRD, FTIR, and UV-Vis analyses showed that the inhibitors enhanced the deposition of BaO2 on the coating surface. Electrochemical impedance showed that the post-sealing in SDS containing electrolyte enhanced corrosion resistance of the sample by three orders of magnitude. After immersing in 0.5wt% NaCl solution for 768 h, the total impedance value remained at 106 Ω/cm². 40 days of continued salt spray test virtually did not show any obvious region of corrosion, proving the excellent corrosion performance of the coatings after performing post-treatment. The corrosion resistance of the coating was enhanced through the synergistic effect of deposition products and adsorption of inhibitors.

Research Article
Thermodynamic theory of flotation for a complex multiphase solid–liquid system and high-entropy flotation
Shuming Wen
, Available online 7 March 2024, https://doi.org/10.1007/s12613-024-2874-z
Abstract:

The flotation of complex solid–liquid multiphase systems involves interactions between multiple components, which is the core problem faced by flotation theory. Meanwhile, the combined use of multi-component flotation reagents to improve mineral flotation has become an important issue in studies on the efficient utilization of refractory mineral resources. However, studying the flotation of complex solid–liquid systems is extremely difficult and no systematic theory has been developed to date. In addition, the physical mechanism associated with combining reagents to improve the flotation effect has not been unified, which limits the development of flotation theory and the progress of flotation technology. In this study, we applied thermodynamics theory to a solid–liquid flotation system and used changes in entropies and Gibbs free energies of the reagents adsorbed on the mineral surface to establish thermodynamic-equilibrium equations that describe interaction between various material components, while also introducing adsorption equilibrium-constants for the flotation reagents adsorbed on the mineral surface. The homogenization effect on the mineral surface in the pulp solution was found to be determined by the chemical potentials of the material components of the various mineral surfaces required to maintain balance. The flotation effect can be improved through synergy between multi-component flotation reagents, its physical essence is the thermodynamic law that the number of components of flotation reagents on the mineral surface increases, the surface adsorption entropy changes increases, and the Gibbs free energy of adsorption decreases. Based on the results obtained using flotation thermodynamics theory, we established high-entropy flotation theory and a technical method, in which increasing the types of flotation reagent adsorbed on the mineral surface, enhancing the adsorption entropy change of the flotation reagents, reducing the Gibbs free energy change, and improving the adsorption efficiency and stability of the flotation reagents, improves refractory-mineral flotation.

Research Article
Role of iron ore in enhancing gasification of iron coke: structural evolution, influence mechanism, and kinetic analysis
Jie Wang, Wei Wang, Xuheng chen, Junfang Bao, Qiuyue Hao, Heng Zheng, and  Runsheng Xu
, Available online 7 March 2024, https://doi.org/10.1007/s12613-024-2873-0
Abstract:

The utilization of iron coke provides a green pathway for low-carbon ironmaking. To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification, the effect of iron ore on the microstructure of iron coke was investigated. Furthermore, a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric method. The findings indicate that compared to coke, iron coke exhibits an augmentation in micropores and specific surface area, and the micropores further extend and interconnect. This provides more adsorption sites for CO2 molecules during the gasification process, resulting in a reduction in the initial gasification temperature of iron coke. Accelerating the heating rate in non-isothermal gasification can enhance the reactivity of iron coke. The metallic iron reduced from iron ore is embedded in the carbon matrix, reducing the orderliness of the carbon structure, which is primarily responsible for the heightened reactivity of the carbon atoms. The kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore structure. Moreover, as the proportion of iron ore increases, the activation energy for the carbon gasification gradually decreases, from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15%.

Research Article
Investigation and optimization of high-valent Ta-doped SrFeO3-δ as air electrode for intermediate-temperature solid oxide fuel cells
Shanshan Jiang, Hao Qiu, Shaohua Xu, Xiaomin Xu, Jingjing Jiang, Beibei Xiao, Paulo Sérgio Barros Julião, Chao Su, Daifen Chen, and  Wei Zhou
, Available online 7 March 2024, https://doi.org/10.1007/s12613-024-2872-1
Abstract:

To explore highly active and thermomechanical stable air electrodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs), 10 mol% Ta5+ doped in the B site of strontium ferrite perovskite oxide (SrTa0.1Fe0.9O3-δ, STF) is investigated and optimized. The effects of Ta5+ doping on structure, transition metal reduction, oxygen nonstoichiometry, thermal expansion, and electrical performance are evaluated systematically. Via 10 mol% Ta5+ doping, the thermal expansion coefficient (TEC) decreased from 34.1.6×10-6 K-1 (SrFeO3-δ) to 14.6×10-6 K-1 (STF), which is near the TEC of electrolyte (13.3×10-6 K-1 for Sm0.2Ce0.8O1.9, SDC), indicates excellent thermomechanical compatibility. At 550-750ºC, STF shows superior oxygen vacancy concentrations (0.262 to 0.331), which is critical in the oxygen-reduction reaction (ORR). Oxygen temperature-programmed desorption (O2-TPD) indicated the thermal reduction onset temperature of iron ion is around 420 ºC, which matched well with the inflection points on the thermos-gravimetric analysis and electrical conductivity curves. At 600 ºC, the STF electrode shows area-specific resistance (ASR) of 0.152 Ωcm2 and peak power density (PPD) of 749 mW cm-2. ORR activity of STF was further improved by introducing 30wt% SDC powder, STF+SDC composite cathode achieving outstanding ASR value of 0.115 Ωcm2 at 600ºC, even comparable with benchmark cobalt-containing cathode, Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF). Distribution of relaxation time (DRT) analysis revealed that the oxygen surface exchange and bulk diffusion were improved by forming a composite cathode. At 650°C, STF+SDC composite cathode achieving an outstanding PPD of 1117 mW cm-2. The excellent results suggest that STF and STF+SDC are promising air electrodes for IT-SOFCs.

Research Article
Wideband microwave absorbing materials synthesized by Carbonized Peanut-shell combined with ferroferric oxide
Guodong Han, Yong Sun, Junxiang Zhou, Yudeng Wang, Jiafu Wang, and  Shaobo Qu
, Available online 27 February 2024, https://doi.org/10.1007/s12613-024-2868-x
Abstract:

Deriving PC materials through biomass sources is a sustainable, ubiquitous, and low-cost method, which comes with many desired features, such as hierarchical texture, periodic pattern, and some unique nanoarchitecture. Herein, a new strategy of using Peanuts as Honeycomb-like carbon precursors and Fe3O4 as magnetic precursor to prepare excellent performance absorbing materials. During the carbonization process, the Peanut-shell changes into the interconnected Honeycomb-like porous carbon materials, and the precursor ferric salt converts into magnetic Fe3O4 nanoparticles. As a result, the obtained MA materials P-C-800@Fe3O4(1:0.5) exhibit outstanding MA performance. When the ration reaches at 4:6, it displays the minimum reflection Loss(RL) of -59.2 dB at 3.36mm, and the effective absorption bandwidth (RL<-10 dB) can reach 7.5 GHz(from 9.5 to 17 GHz) at 2.0 mm. The honeycomb-like composite materials, interfacial polarization, synergistic enhancement between dielectric loss and magnetic loss, multiple reflections, and scatterings make enhancement to the MA capability. This paper might provide an effective and facile strategy to prepare magnetic honeycomb-like porous carbon derived from biomass for MA applications.

Research Article
Preparing lithium-ion battery anode materials from graphitized spent cathode carbon of aluminum electrolysis
Zhihao Zheng, Mingzhuang Xie, Guoiqng Yu, Zegang Wu, Jingjing Zhong, Yi Wang, Hongliang Zhao, and  Fengqin Liu
, Available online 27 February 2024, https://doi.org/10.1007/s12613-024-2866-z
Abstract:

Graphitized spent cathode carbon (SCC) is a hazardous solid waste generated in the aluminum electrolysis process. In this study, a process of flotation-acid leaching is proposed to purify the graphitized SCC, and its use as an anode material for lithium-ion batteries is explored. Optimization of the flotation and acid leaching processes was carried out separately using one-way experiments. The best performance was achieved at 90% flotation particle size of -200 mesh, slurry concentration of 10%, rotation speed of 1600 r/min, inflatable capacity of 0.2 m3/h, and SCC carbon content of 93%. Subsequently, the SCC carbon content reached 99.58% at a leaching concentration of 5 mol/L, a leaching time of 100 min, a leaching temperature of 85 ℃, and an HCl/FSCC volume ratio of 5:1. The purified graphitized SCC(FSCC-CL) was used as an anode material with an initial capacity of 348.2 mAh/g at 0.1C and a reversible capacity of 347.8 mAh/g after 100 cycles. Compared with commercial graphite, FSCC-CL has better reversibility and cycle stability. Therefore, after purification, SCC is an important anode material candidate, and this method also provides a feasible way for the resourceful recycling of SCC.

Research Article
Effect of heating temperature and atmosphere on the element distribution and microstructure in a high-Mn high-Al austenitic low-density steel
Qi Zhang, Guanghui Chen, Yuemeng Zhu, Zhengliang Xue, and  Guang Xu
, Available online 27 February 2024, https://doi.org/10.1007/s12613-024-2867-y
Abstract:

The element distribution and microstructure near surface of a high-Mn high-Al austenitic low-density steel were investigated after isothermal holding at temperatures ranging from 900°C to 1200°C in different atmospheres, including air, N2 and N2 + CO2 mixed atmospheres. The results show that no ferrite formed near the surface of the experimental steel during isothermal holding at 900°C and 1000°C in air, while ferrite formed near the surface when the isothermal temperature reached 1100°C and 1200°C. The fraction of ferrite was larger at 1200°C because more C and Mn diffused to the surface and exuded from steel, which then reacted with N and O to form oxidation products. The thickness of compound scale increased due to the larger diffusion rate at a higher temperature. In addition, after isothermal holding at 1100°C in N2, Al content near the surface reduced slightly, while the contents of C and Mn did not change. Therefore, no ferrite formed near the surface. However, the contents of C and Al near the surface reduced after holding at 1100°C in N2 + CO2 mixed atmosphere, resulting in a small amount of ferrite. The thickness of compound scale was found to be the thickest in N2, followed by N2 + CO2 mixed atmosphere, and the thinnest in air. Overall, the element loss and ferrite fraction were the largest after holding in air at the same temperature. The differences in element loss and ferrite fraction were small in N2 and N2 + CO2 mixed atmospheres, but the compound scale formed in N2 was significantly thicker. Based on these results, the N2 + CO2 mixed atmosphere is the most ideal heating atmosphere for industrial production of high-Mn high-Al austenitic low-density steel.

Research Article
The effect of temperature and time on the precipitation of κ-carbides in Fe-28Mn-10Al-0.8C low-density steels: aging mechanism and its impact on material properties
Yulin Gao, Min Zhang, Rui Wang, Xinxin Zhang, Zhunli Tan, and  Xiaoyu Chong
, Available online 23 February 2024, https://doi.org/10.1007/s12613-024-2857-0
Abstract:

This study investigates the second phase evolution mechanism of κ-carbides during the aging process of Fe-28Mn-10Al-0.8C low-density steel (wt%) and its impact on the material's properties. Under different heat treatment conditions, intragranular κ-carbides exhibit various morphologies and crystallographic characteristics, such as acicular, spherical, and short rod-like shapes. At the initial stage of aging, κ-carbides primarily precipitate in acicular forms, accompanied by a few spherical carbides. With the extension of aging time, κ-carbides grow and coarsen, the spherical carbides significantly reduce, and the rod-like carbides become noticeably coarser. In the literature on low-density steel, κ-carbides primarily precipitate in the form of nanoscale particles from within austenite grains, with limited mention within ferrite matrix grains; furthermore, the second-phase evolution mechanism during the aging process remains unclear in the observations made in this experiment. By adjusting the aging temperature and time, this study thoroughly analyzed the crystallographic characteristics and morphological evolution of κ-carbides and investigated the impact of these changes on the material's microhardness. It comprehensively assessed the influence of different aging conditions on material properties and, based on these findings, proposed potential strategies for improving material strength.

Research Article
Assessing corrosion protection property of coatings loaded with corrosion inhibitors using real-time atmospheric corrosion monitoring (ACM) technique
Xiaoxue Wang, Lulu Jin, Jinke Wang, Rongqiao Wang, Xiuchun Lu, Kai Gao, Jingli Sun, Yong Yuan, Lingwei Ma, Hongchang Qian, and  Dawei Zhang
, Available online 23 February 2024, https://doi.org/10.1007/s12613-024-2860-5
Abstract:

The atmospheric corrosion monitoring (ACM) technique has been widely employed to track the real-time corrosion behavior of metal materials. However, limited studies have employed ACM to monitor the corrosion protection properties of organic coatings. This study focused on comparing a bare epoxy coating with one containing zinc phosphate corrosion inhibitors, both applied on ACM sensors, to observe their corrosion protection properties over time. The coatings underwent artificial damage via scratches and were then exposed to immersion as well as alternating dry and wet environments. This allowed for monitoring the galvanic corrosion currents in real-time. Throughout the corrosion tests, the zinc phosphate/epoxy coating displayed significantly lower ACM currents compared to the blank epoxy coating. The trend in ACM current variations closely matched the results obtained from regular electrochemical tests and surface analysis. This alignment highlights the potential of the ACM technique in evaluating the corrosion protection capabilities of organic coatings. Compared with the blank epoxy coating, the much decreased ACM current values observed on the zinc phosphate/epoxy coating confirmed the effective inhibition of zinc phosphate against steel corrosion beneath the damaged coating.

Research Article
Breaking the Fe3O4-Wrapping-Copper Microstructure for Enhancing the Copper-Slag separation
Xiaopeng Chi, Haoyu Liu, Jun Xia, Hang Chen, Wei Weng, and  Shuiping Zhong
, Available online 23 February 2024, https://doi.org/10.1007/s12613-024-2861-4
Abstract:

Precipitation of Fe3O4 particles and the accompanied formation of the Fe3O4-wrapping-copper structure are the main obstacle for copper recovery from the molten slag during the pyrometallurgical smelting of copper concentrates. Herein, by replacing the commercial powdery pyrite or anthracite with the pyrite-anthracite pellets as the reductants, more Fe3O4 particles in the molten slag can be removed, resulting in the deep fracture of the Fe3O4-wraping-copper microstructure and fully exposure of the copper matte cores. Resultantly, using 1 wt.% composite pellet as the reductant, the copper matte droplets are enlarged greatly from 25 μm to the size being observed by naked eyes, with the copper content being enriched remarkably from 1.2 wt.% to 4.5 wt.%. The DFT calculation results imply that the formation of the Fe3O4-wrapping-copper structure is due to the preferential adhesion of Cu2S on the Fe3O4 particles. The XPS and FTIR as well as Raman spectroscopy results all reveal that the high-efficiency conversion of Fe3O4 to FeO can decrease the volume fraction of solid phase and promote the depolymerization of silicate network structure, which promotes the settling of copper matte droplets due to lowered slag viscosity, contributing to the high-efficiency copper-slag separation for copper recovery. The results can provide new insights for enhanced in-situ enrichment of copper from the molten slag.

Research Article
Iron–nitrogen-doped porous carbon absorbers constructed from hyper-crosslinked ferrocene polymers for efficient electromagnetic wave absorption
Yi Hu, Yijia Zhou, Lijia Liu, Qiang Wang, Chunhong Zhang, Hao Wei, and  Yudan Wang
, Available online 23 February 2024, https://doi.org/10.1007/s12613-024-2863-2
Abstract:

 Herein, ferrocene and a nitrogen heterocyclic compound (either melamine or imidazole) were hyper-crosslinked via an external crosslinker through a straightforward Friedel–Crafts reaction, leading to the formation of nitrogen-containing hyper-crosslinked ferrocene polymer precursors (HCPs). These precursors were subsequently carbonized to produce iron–nitrogen-doped porous carbon absorbers (Fe-NPCs). The Fe-NPCs feature a porous structure comprising aggregated nanotubes and nanospheres, with porosity that can be modulated by adjusting the iron and nitrogen content to optimize impedance matching. The use of hyper-crosslinked ferrocenes in constructing porous carbon ensures the uniform distribution of Fe-NxC, N dipoles, and α-Fe within the carbon matrix, providing the absorber with numerous polarization sites and a conductive network. The specially designed Fe-NPC-M2 absorbers exhibit satisfactory electromagnetic wave absorption performance, with a minimum reflection loss of −55.3 dB at 2.5 mm and an effective absorption bandwidth of 6.00 GHz at 2.0 mm. This research introduces a novel method for developing highly efficient carbon-based absorbing agents by utilizing hyper-crosslinked polymers as precursors.

Research Article
Effect of heat treatment on microstructure, mechanical properties, and fracture behaviors of ultra-high strength SiC/Al-Zn-Mg-Cu composite
Guonan Ma, Shize Zhu, Dong Wang, Peng Xue, Bolv Xiao, and  Zongyi Ma
, Available online 23 February 2024, https://doi.org/10.1007/s12613-024-2856-1
Abstract:

A high-zinc 12vol%SiC/Al-13.3Zn-3.27Mg-1.07Cu (wt%) composite with ultra-high strength of 781 MPa was successfully fabricated by powder metallurgy method followed by extrusion process. The effects of solid solution and aging heat treatments on the microstructure and mechanical properties of the composite were investigated in detail. Compared to the single-stage solution treatment, more sufficient solid solution effect was achieved in two-stage solution treatment (470ºC/1 h+480ºC/1 h) due to the higher solution degree and more uniform microstructure. According to aging harden curves of the composite, the optimized aging parameter (100ºC/22 h) was proposed. By decreasing the aging temperature and shortening the aging time, the nanoscale precipitates became finer and more uniform, but the increase in the tensile strength was insignificant. Based on the fractography analysis, the intergranular cracking and interface debonding were considered as the main fracture mechanisms in the ultra-high strength SiC/Al-Zn-Mg-Cu composites. The SiC/Al interface with many compounds and the precipitate free zone at the high-angle grain boundaries were the relatively weak regions that could clearly limit the strength enhancement of the composite. The interfacial compounds were identified as MgO, MgZn2, and Cu5Zn8, which reduced the interface bonding strength and lead to interfacial debonding.

Research Article
Facile synthesis of Cu-doped manganese oxide octahedral molecular sieve for efficient degradation of sulfamethoxazole via peroxymonosulfate activation
Yuhua Qiu, Yingping Huang, Yanlan Wang, Xiang Liu, and  Di Huang
, Available online 23 February 2024, https://doi.org/10.1007/s12613-024-2858-z
Abstract:

Recently, peroxymonosulfate-based advanced oxidation processes have turned out to be the one of most efficient approaches for the elimination of toxic and refractory organic pollutants from sewage. Because the electron withdrawing group SO4− was easily activated to release reactive species, including sulfate radical (·SO4−), hydroxyl radical (·OH), superoxide radicals (·O2-) and singlet oxygen (1O2), all of which could induce the degradation of organic contaminant. In this work, we had synthesized a variety of M-OMS-2 nanorods (M=Co, Ni, Cu or Fe), by doping of Co2+, Ni2+, Cu2+ or Fe3+ into manganese oxide octahedral molecular sieve (OMS-2), as high-efficiency nano-catalysts for efficient removal of sulfamethoxazole via peroxymonosulfate (PMS) activation. The comparison of catalytic performance of M-OMS-2 in sulfamethoxazole elimination via PMS activization exhibited that the order of sulfamethoxazole removal rate as follow: Cu-OMS-2 (96.4%) > Co-OMS-2 (88.0%) > Ni-OMS-2 (87.2 %) > Fe-OMS-2 (35.0%) > OMS-2 (33.5%). Then, the kinetics and structure-activity relationship of M-OMS-2 nanorods in the elimination of sulfamethoxazole were investigated. The feasible mechanism of sulfamethoxazole degradation via Cu-OMS-2/PMS system was further investigated by quenching experiment, HR-MS and EPR. In addition, we found that sulfamethoxazole degradation efficiency was obviously boosted in both sea water and tap water, demonstrating the great potential application of Cu-OMS-2/PMS system in the real sewage treatment.

Research Article
Spin Logic Devices Based on Negative Differential Resistance Enhanced Anomalous Hall Effect
Hong ming Mou, Ziyao Lu, Yuchen Pu, Zhaochu Luo, and  Xiaozhong Zhang
, Available online 19 February 2024, https://doi.org/10.1007/s12613-024-2855-2
Abstract:

With the fast development of spintronics, spin-based logic devices have emerged as promising candidates for next-generation computing technologies. This paper provides a comprehensive review of recent advancements in spin logic devices, particularly focusing on fundamental device concepts rooted in nanomagnets, magnetoresistive random-access memory (MRAM), spin-orbit torques (SOTs), electric-field modulation, and magnetic domain walls. We will present the thorough analysis of the operation principles of these spin logic devices. Additionally, we summarize recent advances in spin logic devices based on negative differential resistance enhanced anomalous Hall effect. These devices exhibit reconfigurable logic capabilities and integration of non-volatile data storage and computing functionalities. For the current-driven spin logic devices, negative differential resistance elements are employed to nonlinearly enhance anomalous Hall effect signals from magnetic bits, enabling reconfigurable Boolean logic operations. Besides, voltage-driven spin logic devices employ another type of negative differential resistance elements to achieve logic functionalities with excellent cascading ability. By cascading several elementary logic gates, we can obtain the logic circuit of a full adder, verifying the potential of voltage-driven spin logic devices for implementing complex logic functions. This review contributes to the understanding of the evolving landscape of spin logic devices and underscores the promising prospects they hold in shaping the future of emerging computing schemes.

Research Article
Temperature-jump tensile tests to induce optimized TRIP/TWIP effect in a metastable austenitic stainless steel
Mohammad Javad Sohrabi, Hamed Mirzadeh, Saeed Sadeghpour, Abdol Reza Geranmayeh, and  Reza Mahmudi
, Available online 19 February 2024, https://doi.org/10.1007/s12613-024-2852-5
Abstract:

In the present work, plastic deformation mechanisms were initially tailored by adjusting the deformation temperature in the range of 0 to 200 °C in an AISI 304L austenitic stainless steel, aiming to optimize the strength-ductility synergy. It was shown that the combined twinning-induced plasticity (TWIP)/transformation-induced plasticity (TRIP) effects and a wider strain range for the TRIP effect up to higher strains by adjusting the deformation temperature are good strategies to improve the strength-ductility synergy of this metastable stainless steel. In this regard, by consideration of the observed temperature-dependency of plastic deformation, the controlled sequence of TWIP and TRIP effects for archiving superior strength-ductility trade-off was intended by the pre-designed temperature jump tensile tests. Accordingly, the optimum tensile toughness of 846 MJ/m3 and total elongation to 133% were obtained by this strategy via exploiting the advantages of the TWIP effect at 100 °C and the TRIP effect at 25 °C at the later stages of the straining. Consequently, a deformation-temperature-transformation (DTT) diagram was developed for this metastable alloy. Moreover, based on work-hardening analysis, it was found that the main phenomenon constraining further improvement in the ductility and strengthening was the yielding of the deformation-induced α΄-martensite.

Research Article
Oxidation behavior of FeV2O4 and FeCr2O4 particles in the air: non-isothermal kinetic and reaction mechanism
Junyi Xiang, Xi Lu, Luwei Bai, Hongru Rao, Sheng Liu, Qingyun Huang, Shengqing Zhang, GuiShang Pei, and  Xuewei Lv
, Available online 7 February 2024, https://doi.org/10.1007/s12613-024-2851-6
Abstract:

The oxidation behavior of ferrovanadium spinel (FeV2O4) and ferrochrome spinel (FeCr2O4) at high temperature is crucial for the application of energy materials with spinel structure, as well as the cleaner utilization of high-chromium vanadium slag. In this study, the non-isothermal oxidation behavior of FeV2O4 and FeCr2O4 synthesized through high-temperature solid-state reaction, were investigated by thermogravimetry and X-ray diffraction at heating rates of 5, 10, and 15K/min respectively. The apparent activation energy was determined using the Kissinger-Akahira-Sunose (KAS) method, while the Malek method was employed to ascertain the mechanism function. Additionally, in-situ X-ray Diffraction (XRD) analysis was conducted to deduce the phase transformation of the oxidation mechanism for FeV2O4 and FeCr2O4. The results demonstrate a gradual increase in overall apparent activation energies for both FeV2O4 and FeCr2O4 during oxidation. The oxidation process can be divided into four stages based on the reduction conversion rate of each compound. The oxidation mechanisms of FeV2O4 and FeCr2O4 are complex with distinct mechanism functions. Specially, chemical reaction controls the entire oxidation process for FeV2O4 whereas FeCr2O4 it transitions from a three-dimensional diffusion model to a chemical reaction model. In-situ XRD results reveal numerous intermediate products during the oxidation process of both compounds; ultimately resulting in formation of final products such as FeVO4 and V2O5 for FeV2O4, as well as Fe2O3 and Cr2O3 for FeCr2O4.

Research Article
Structural and microwave absorption properties of CoFe2O4/residual carbon composites
Yuanchun Zhang, Shengtao Gao, Xingzhao Zhang, Dacheng Ma, Chuanlei Zhu, and  Jun He
, Available online 6 February 2024, https://doi.org/10.1007/s12613-024-2849-0
Abstract:

Electromagnetic interference is of urgent concern in contemporary society, necessitating the swift advancement of substances with exceptional capabilities in absorbing electromagnetic waves. In this work, a direct hydrothermal method was utilized to create CoFe2O4/residual carbon from coal gasification fine slag (CFO/RC) composites. These composites encompass various mechanisms for microwave absorption, including conductive loss, natural resonance, interfacial dipole polarization, and magnetic flux loss. Consequently, compared with pure residual carbon materials this composite offers superior capabilities in microwave absorption. At 7.76 GHz, the CFO/RC-2 composite achieves an impressive minimum reflection loss (RLmin) of −43.99 dB with a thickness of 2.44 mm. Moreover, CFO/RC-3 demonstrates an effective absorption bandwidth (EAB) of up to 4.16 GHz, accompanied by a thickness of 1.18 mm. This study revealed the remarkable ability of the composite to diminish electromagnetic waves, providing a new method for generating microwave absorbing materials of superior quality.

Research Article
Phase equilibria relations in V2O5-rich part of the Fe2O3-TiO2-V2O5 system at 1200°C related to converter vanadium-bearing slag
Junjie Shi, Yumo Zhai, Yuchao Qiu, Changle Hou, Jingjing Dong, Maoxi Yao, Haiyang Li, Yongrong Zhou, and  Jianzhong Li
, Available online 6 February 2024, https://doi.org/10.1007/s12613-024-2845-4
Abstract:

The efficient recycling of vanadium from converter vanadium-bearing slag is of great significance for sustainable development and circular economy. The key to developing novel processes and improving traditional routes lies in the thermodynamic data. In this study, the equilibrium phase relations for the Fe2O3-TiO2-V2O5 system at 1200 °C in air were investigated using a high temperature equilibrium-quenching technique, followed by analysis using Scanning Electron Microscopy-Energy Dispersive and X-ray Photoelectron Spectroscopy. One liquid phase region, two two-phase regions (liquid-rutile and liquid-ferropseudobrookite), and one three-phase region (liquid-rutile-ferropseudobrookite) were determined. The variation of TiO2 and V2O5 concentrations with Fe2O3 concentration was examined for rutile and ferropseudobrookite solid solutions. However, upon further comparison with the predictions made by FactSage 8.1, significant discrepancies were identified. This highlights the need for greater attention to be given to updating the current thermodynamic database related to vanadium-bearing slag systems.

Research Article
Strengthening strategy for high-performance friction stir lap welded joints of 5083 aluminum alloy
Yujia Shen, Jijie Wang, Beibei Wang, Peng Xue, Fengchao Liu, Dingrui Ni, Bolv Xiao, and  Zongyi Ma
, Available online 6 February 2024, https://doi.org/10.1007/s12613-024-2847-2
Abstract:

During aircraft, ship, and automobile manufacturing, lap structures are frequently produced between aluminum alloy skins, wall panels, and stiffeners. However, the occurrence of lap defects severely decreases mechanical properties during friction stir lap welding (FSLW). This study focuses on investigating the effects of rotation rate, multi-pass welding, and cooling methods on lap defect formation, microstructure evolution, and mechanical properties. It was discovered that the hook defects were eliminated by decreasing the welding speed, applying 2-passes FLSW with a small welding tool, and introducing the additional water cooling, leading to a remarkable increase in effective sheet thickness and lap width. This strategy leads to a defect-free joint with an ultrafine-grained microstructure, elevating the tensile shear force from 298 N/m to 551 N/mm. The fracture behavior of FSLW was systematically studied, and a fracture factor of the lap joint was proposed to predict the fracture mode of the FSLW joint. Through the implementation of decreasing rotation rate, 2-passes welding, and the additional water cooling strategies, the enlarged, strengthened, and defect-free lap zone with refined ultrafine grains was achieved, comparable to the quality of lap welds for 7xxx Al alloys. Importantly, this study provides a valuable welding method for FSLW to eliminate hook defects and improve joint performance.

Research Article
Interconnected microstructure and flexural behavior of Ti2C-Ti composites with superior Young’s modulus
Fengbo Sun, Rui Zhang, Fanchao Meng, Shuai Wang, Lujun Huang, and  Lin Geng
, Available online 6 February 2024, https://doi.org/10.1007/s12613-024-2848-1
Abstract:

In order to enhance Young’s modulus and strength of titanium alloys, titanium matrix composites with interconnected microstructure were designed based on Hashin-Shtrickmen theory. The results showed that the interconnected microstructure composed of Ti2C particles was achieved through in-situ reaction when the Ti2C content reached 50 vol.%. In the prepared composite, intraparticle Ti lamellae exhibited bimodal size distribution with widths of 10 nm and 230 nm due to precipitation and unreacted Ti phase within grown Ti2C particles. The composites with interconnected microstructure achieved superior properties, including a Young’s modulus of 174.3 GPa and an ultimate flexural strength of 1014 GPa. Compared with pure Ti, the Young’s modulus was increased by 55% because of high Ti2C content and the interconnected microstructure. The outstanding strength was mainly attributed to the strong interfacial bonding, load-bearing capacity of interconnected Ti2C particles, and bimodal intraparticle Ti lamellae that minimized the average crack driving force. Interrupted flexural tests revealed that cracks preferentially initiated along {001} cleavage plane and grain boundary of Ti2C in the region with the highest tensile stress, while the propagation can be efficiently inhibited by interparticle Ti grains, preventing the composites from brittle fracture.

Research Article
Efficient energy transfer from self-trapped excitons to Mn2+ dopants in CsCdCl3:Mn2+ perovskite nanocrystals
Anran Zhang, Xinquan Zhou, Ranran Gu, and  Zhiguo Xia
, Available online 30 January 2024, https://doi.org/10.1007/s12613-024-2844-5
Abstract:

Mn2+ doping has been adopted as an efficeint strategy to regulate the luminescence properties of halide perovskite nanocrystals (NCs). However, it remains challenging to understand the interplay of Mn2+ luminescence and the matrix self-trapped excitons (STEs) emission therein. In this work, Mn2+-doped CsCdCl3 NCs are synthesized by a hot injection method, where CsCdCl3 is chosen due to its unique crystal structure conducive to STEs emission. The blue emission at 441 nm of undoped CsCdCl3 NCs originates from defect states in the NCs. Mn2+ doping promotes lattice distortion of CsCdCl3 and genrerates bright orange-red light emission at 656 nm. The energy transfer from STEs of CsCdCl3 to the excited levels of Mn2+ ion is verified to be a significant factor in achieving efficient luminescence in CsCdCl3:Mn2+ NCs. This work underlines the crucial role of energy transfer from STEs to Mn2+ dopants in Mn2+-doped halide NCs and lays the groundwork for modifying the luminescence of other metal halide perovskite NCs.

Research Article
A novel high-Cr CoNi-based superalloy with superior high-temperature microstructural stability, oxidation resistance and mechanical properties
Xiaorui Zhang, Min Zou, Song Lu, Longfei Li, Xiaoli Zhuang, and  Qiang Feng
, Available online 30 January 2024, https://doi.org/10.1007/s12613-024-2843-6
Abstract:

A novel multi-component high-Cr CoNi-based superalloy with superior comprehensive performance was developed and its high-temperature microstructural stability, oxidation resistance and mechanical properties were evaluated mainly by cast polycrystalline alloy. The results indicated that the morphology of γ' phase remained stable and the coarsening rate was slow during the long-term aging at 900~1000°C. The activation energy for γ′ precipitate coarsening of alloy 9CoNi-Cr is determined to be 402 ± 51 kJ/mol, which is higher compared to CMSX-4 and some other Ni-based and Co-based superalloys. Importantly, there was no indication of the formation of Topologically Close-Packed phases during this process. All these demonstrate superior microstructural stability of the alloy. The mass gain of alloy 9CoNi-Cr is 0.6 mg/cm2 after oxidation at 1000°C for 100 h and the oxidation resistance is comparable to advanced Ni-based superalloys CMSX-4, which attributed to the formation of a continuous Al2O3 protective layer. Furthermore, the compressive yield strength of this cast polycrystalline alloy at high temperature is obviously higher than that of conventional Ni-based cast superalloy, and the compressive minimum creep rate at 950°C is comparable to that of conventional Ni-based cast superalloy, showing good mechanical properties of the alloy at high temperature. This is partially due to the high Cr is beneficial on improving the γ and γ' phase strength of alloy 9CoNi-Cr.

Research Article
Microstructures and micromechanical behaviors of high entropy alloys investigated by synchrotron X-ray and neutron diffraction techniques: a review
Yubo Huang, Ning Xu, Huaile Lu, Yang Ren, Shilei Li, and  Yandong Wang
, Available online 25 January 2024, https://doi.org/10.1007/s12613-024-2840-9
Abstract:

High-entropy alloys (HEAs) have excellent characteristics, including corrosion resistance, irradiation resistance, and mechanical properties. A few HEAs have become alternative application materials in various fields, such as aerospace and defense technology. Comprehensive investigation of the deformation mechanisms of HEAs can guide microstructure control and toughness design, which is of vital significance for the understanding and exploration of advanced structural materials. Synchrotron X-ray and neutron diffraction techniques are required tools for materials science research, especially for in situ coupling of physical/chemical fields and for resolving macro/microcrystallographic information about materials. In recent years, many scholars have used synchrotron X-ray and neutron diffraction techniques to investigate the deformation mechanisms, phase transformations, stress behaviors, and in situ processes of HEAs, such as variable-temperature, high-pressure and hydrogenation processes. Herein, we present the principles and development of neutron and synchrotron radiation technology and their applications in the deformation mechanisms of HEAs. The factors influencing the deformation mechanisms of HEAs are also summarized. We focus on their microstructures and micromechanical behaviors during tension/compression or creep/fatigue deformation, and we study the application of synchrotron X-ray and neutron diffraction techniques to the observation of dislocations/stacking faults/twins/phases and intergrain/interphase stress changes. Outlooks on the future development of synchrotron X-ray and neutron diffraction techniques and on the study of deformation mechanisms of new metals are discussed.

Research Article
Chitosan-based triboelectric materials for self-powered sensing at high temperature
Wencan Chen, Chao Li, Yehan Tao, Jie Lu, Jian Du, and  Haisong Wang
, Available online 20 January 2024, https://doi.org/10.1007/s12613-024-2839-2
Abstract:

Biopolymers have been widely used as triboelectric materials in constructing self-powered sensing system, whereas the annihilation of triboelectric charges at high temperatures restricted the output signals as well as the sensitivity of assembled sensors. Herein, a novel chitosan/montmorillonite/lignin (CML) composite film was designed and employed as the tribopositive layers in assembling self-powered sensing system under hot conditions (25-70oC). Originating from the strong intermolecular interaction between biopolymers and nanofillers, the dense contact surface restrained the volatilization of induced electrons. The optimized CML-TENG delivered the highest open circuit voltage (Voc) of 262 V and a maximum instantaneous output power of 429 mW/m2. Furthermore, the best CM5L3-TENG retained 66% of its initial Voc at 70℃, which is much higher than the pristine chitosan film (39%). Our work provides a new strategy to suppress the annihilation of triboelectric charges at high temperatures, boosting the development of self-powered sensing device under hot conditions.

Research Article
Numerical and theoretical study of the large-scale failure of strata overlying sublevel caving mines with steeply-dipping discontinuities
Kaizong Xia, Zhiwei Si, Congxin Chen, Xiaoshuang Li, Junpeng Zou, and  Jiahao Yuan
, Available online 19 January 2024, https://doi.org/10.1007/s12613-024-2838-3
Abstract:

The deformation and fracture evolution mechanisms of the strata overlying such mines mined using sublevel caving were studied via numerical simulations. Moreover, an expression for the normal force acting on the side face of a steeply-dipping superimposed cantilever beam in the surrounding rock was deduced based on limit equilibrium theory. The results show that surface displacement above metal mines with steeply-dipping discontinuities shows significant step characteristics and the behavior of the strata as they fail exhibits superimposition characteristics. Generally, failure first occurs in certain superimposed strata slightly far from the goaf. Then, with the constant downward excavation of the orebody, the superimposed strata become damaged upwards away from, and downwards towards, the goaf. This continues until the deep part of the steeply-dipping superimposed strata form a large-scale deep fracture plane that connects with the goaf. The deep fracture plane generally makes an angle of 12–20° with the normal to the steeply-dipping discontinuities. The effect of the constant outward transfer of strata movement due to the constant outward failure of the superimposed strata in the metal mines with steeply-dipping discontinuities causes the scope of the strata movement in these metal mines to be larger than expected. The strata in the metal mines with steeply-dipping discontinuities mainly show flexural toppling failure. However, the steeply-dipping structural strata near the goaf mainly exhibit shear slipping failure, in which case the mechanical model used to describe them can be simplified by treating them as steeply-dipping superimposed cantilever beams. By taking the steeply-dipping superimposed cantilever beam that first experiences failure to be the key stratum, the failure scope of the strata (and criteria for the stability of metal mines with steeply-dipping discontinuities mined using sublevel caving) can be obtained via iterative computations from the key stratum, moving downward towards and upwards away from the goaf.

Research Article
Oxygen-assisted zinc recovery from electric arc furnace dust using magnesium chloride
Jingdong Huang and  Xiao Yang
, Available online 19 January 2024, https://doi.org/10.1007/s12613-024-2837-4
Abstract:

Electric arc furnace (EAF) dust is an important secondary resource containing metals like zinc (Zn) and iron (Fe). Recovering Zn from EAF dust can contribute to resource recycling and reduces environmental impacts. However, the high chemical stability of ZnFe2O4 in EAF dust poses challenges to Zn recovery. To address this, a facile approach of oxygen-assisted chlorination using molten MgCl2 is proposed. This work focuses on elucidating the role of O2 in the reaction between ZnFe2O4 and molten MgCl2. The results demonstrate that MgCl2 effectively breaks down the structure of ZnFe2O4 and a high O2 atmosphere significantly enhances the separation of Zn as ZnCl2 from other components. The presence of O2 facilitates the formation of MgFe2O4, which stabilizes Fe and prevents its chlorination. Furthermore, the study reveals that excessive use of MgCl2 results in increased evaporation losses, while higher temperatures promote the rapid separation of Zn. Building on these findings, the successful extraction of ZnCl2-enriched volatiles from practical EAF dust through oxygen-assisted chlorination is demonstrated. Under optimized conditions, this method achieves an exceptional Zn chlorination percentage of over 97mass% within a short period, while Fe chlorination remains below 1mass%. The resulting volatiles contain 85mass% of ZnCl2, which can be further processed to produce metallic Zn. These findings provide valuable guidance for the selective recovery of valuable metals, particularly from solid wastes like EAF dust.

Research Article
Bioleaching of vanadium from stone coal vanadium ore by Bacillus mucilaginosus: influencing factors and bioleaching mechanism
Yingbo Dong, Jinyu Zan, and  Hai Lin
, Available online 19 January 2024, https://doi.org/10.1007/s12613-024-2836-5
Abstract:

Vanadium and its derivatives are used in a wide range of industries including steel, metallurgy, pharmaceuticals and aerospace engineering, etc. The reserves of stone coal resources are huge but the grade is low in China. Therefore, the effective extraction and efficient recovery of metal vanadium from stone coal is an important way to realize the efficient resource utilization of stone coal vanadium ore. In this thesis, Bacillus mucilaginosus was selected as the leaching strain and  vanadium leaching reached 35.5% after 20 d of bioleaching under the optimized operating conditions. The cumulative leaching rate of vanadium in the contact group reached 35.5%, which was higher than 9.3% in the non-contact group. The metabolites of B. mucilaginosus, such as oxalic acid, tartaric acid, citric acid, and malic acid played a dominant role in the bioleaching process, contributing 73.2% of the vanadium leaching rate. Interestingly, during the leaching process, the presence of stone coal stimulated the expression of carbonic anhydrase in the bacterial cells and the enzyme activity increased by 4.4442 U. The enzyme activity positively promoted the production of metabolite organic acids, and the total organic acid content increased by 39.31 mg/L, resulting in a decrease of 2.35 in the pH of the leaching system, which favored the leaching of vanadium in stone coal. Atomic force microscopy analysis illustrated the bacterial leaching action led to a deepening of the corrosion on the surface of the stone coal, even exceeding 10 nm. Our study provides a clear strategy to explore the bioleaching mechanism from the perspective of microbial enzyme activity and metabolite which appears very promising for the exploration the bioleaching mechanism.

Research Article
Examining the Impact of Ethanol on Flotation Efficiency of Imidazolium Ionic Liquids as Collectors: Insights from Dynamic Surface Tension and Solvation Analysis
Qian cheng, Zerui lei, Guangjun Mei, and  Jianhua Chen
, Available online 19 January 2024, https://doi.org/10.1007/s12613-024-2835-6
Abstract:

In order to conduct more extensive research on the application of ionic liquids (ILs) as collectors in minerals flotation, ethanol (EtOH) was used as a solvent to dissolve hydrophobic ILs to simplify the reagent regime. Some interesting phenomena were observed that EtOH caused different effects on the flotation efficiency of two ILs with similar structures. When EtOH was used to dissolve 1-Dodecyl-3-methylimidazolium chloride (C12[mim]Cl), and C12[mim]Cl as collector for pure quartz flotation tests at the concentration of 1*10-5mol*L-1, quartz recovery increased from 23.77% to 77.91% compared with ILs dissolved in water. However, quartz recovery of 1-Dodecyl-3-methylimidazolium hexafluorophosphate (C12[mim]PF6) decreased from 60.45% to 24.52% in the same cases. the EtOH concentration tests under 1*10-5mol*L-1 ILs and the ILs concentration tests under 2% EtOH confirmed this. After being affected by EtOH, the mixed ore flotation tests of quartz and hematite showed a decrease in the hematite concentrate grade and recovery for C12[mim]Cl collector, while the hematite concentrate grade and recovery for C12[mim]PF6 collector both increased. Based on these interesting differences and observation in flotation tests, the two-phase bubble observation tests were carried out and it showed that EtOH promoted foam height of two ILs during aeration but accelerated static froth defoaming after aeration stopped, and the foam of C12[mim]PF6 defoaming more quickly. Through the discussion of flotation tests and foam observation, an attempt was made to explain the reasons and mechanisms of various differences phenomenon using the dynamic surface tension effect and solvation effect result from EtOH. The solvation effect was verified by IR, XPS and Zeta potential tests. It can be assumed that although EtOH has a negative effect on the adsorption of ILs on the ore surface during the flotation process, it has application reference value for the inhibition of foam merging during the flotation aeration process and the acceleration of the defoaming of static foam. These effects induced a stronger secondary enrichment in the mixed ore flotation of C12[mim]PF6 collector, so that C12[mim]PF6 obtained good mixed ore separation under the condition of no any inhibitor.

Research Article
Research on the mechanism of rockburst induced by mined coal-rock linkage of sharply inclined coal seams
Xingping Lai, Huicong Xu, Pengfei Shan, Qinxin Hu, Weixi Ding, Shangtong Yang, and  Zhongming Yan
, Available online 17 January 2024, https://doi.org/10.1007/s12613-024-2833-8
Abstract:
In recent years, the mining depth of steeply inclined coal seams in the Urumqi mining area has gradually increased. Local deformation of mining coal-rock results in frequent rockbursts. This has become a critical issue that affects the safe mining of deep, steeply inclined coal seams. In this work, we adopt a perspective centered on localized deformation in coal-rock mining and systematically combine theoretical analyses and extensive data mining of voluminous microseismic data. We describe a mechanical model for the urgently inclined mining of both the sandwiched rock pillar and the roof, explaining the mechanical response behavior of key disaster-prone zones within the deep working face, affected by the dynamics of deep mining. By exploring the spatial correlation inherent in extensive microseismic data, we delineate the “time–space” response relationship that governs the dynamic failure of coal-rock during the progression of the sharply inclined working face. The results disclose that (1) the distinctive coal-rock occurrence structure characterized by a “sandwiched rock pillar-B6 roof” constitutes the origin of rockburst in the southern mining area of the Wudong Coal Mine, with both elements presenting different degrees of deformation localization with increasing mining depth. (2) As mining depth increases, the bending deformation and energy accumulation within the rock pillar and roof show nonlinear acceleration. The localized deformation of deep, steeply inclined coal-rock engenders the spatial superposition of squeezing and prying effects in both the strike and dip directions, increasing the energy distribution disparity and stress asymmetry of the “sandwiched rock pillar-B3+6 coal seam-B6 roof” configuration. This makes worse the propensity for frequent dynamic disasters in the working face. (3) The developed high-energy distortion zone “inner–outer” control technology effectively reduces high stress concentration and energy distortion in the surrounding rock. After implementation, the average apparent resistivity in the rock pillar and B6 roof substantially increased by 430% and 300%, respectively, thus guaranteeing the safe and efficient development of steeply inclined coal seams.
Research Article
Edge effect during MPCVD diamond film deposition: multi-physics simulation and experimental verification
Zhiliang Yang, Kang An, Yuchen Liu, Zhijian Guo, Siwu Shao, Jinlong Liu, Junjun Wei, Liangxian Chen, Lishu Wu, and  Chengming Li
, Available online 17 January 2024, https://doi.org/10.1007/s12613-024-2834-7
Abstract:

The edge effect of diamond films deposited by microwave plasma chemical vapor deposition (MPCVD) was investigated. As a factor that affects edge effect, substrate bulge height ∆h is used to simulate plasma and to guide the diamond film deposition experiments. Using the finite element software COMSOL Multiphysics, a multi-physics (electromagnetic field, plasma field and fluid heat transfer field) coupling model based on electron collision reaction was constructed. The experimental growth provided model validation by characterizing it using Raman spectroscopy and scanning electron microscopy. The simulation results reproduced the experimental trend. The increase in ∆h (∆h = 0−3 mm) accelerates the plasma discharge at the edge of the substrate, and the electron density (n_e), molar concentration of H (C_H), and molar concentration of CH3 (C_(〖CH〗_3 )) are doubled at the edge. (For the special concave sample with ∆h = −1 mm, the molar concentration of active chemical groups decreased at the edge of the substrate.) When ∆h = 0−3 mm, a higher diamond growth rate and a larger diamond grain size are obtained at the edge of the substrate in the experiment, which increases with ∆h. The film thickness uniformity decreased with ∆h. The Raman spectra of all samples show a first-order characteristic peak of the diamond, which was located near 1332 cm−1. When ∆h = −1 mm, all regions in the film experienced a tensile stress. When ∆h = 1−3 mm, all areas in the film show a compressive stress.

Research Article
Effect of hafnium and molybdenum addition on inclusion characteristics in Co-based dual-phase high entropy alloy
Yong Wang, Wei Wang, Joo Hyun Park, and  Wangzhong Mu
, Available online 17 January 2024, https://doi.org/10.1007/s12613-024-2831-x
Abstract:

Specific grades of high entropy alloys (HEA) can provide opportunities for optimization properties towards the high-temperature application. The base HEA used for this work with the chemical composition of Co47.5Cr30Fe7.5Mn7.5Ni7.5 (at.%) was selected. The refractory metals hafnium (Hf) and molybdenum (Mo) were added in small amounts (1.5 at.%) due to their well-known positive effects on high-temperature properties. Inclusion characteristics were comprehensively investigated by a two-dimensional (2D) cross-section method as well as extracted by a three-dimensional (3D) electrolytic extraction method. The results showed that the addition of Hf can reduce Al2O3 inclusions and result in the formation of more stable Hf-rich inclusions as the main phase. Mo addition did not affect the inclusion type, but it can affect the inclusion characteristics by affecting the physical parameters of HEA melt. The calculated coagulation coefficient and collision rate of Al2O3 inclusions were higher than that of HfO2 inclusions, but the inclusion amount played a larger role in the agglomeration behavior of HfO2 and Al2O3 inclusions in this study. The inclusions in HEAs highly depended on the active elements present in the alloys. The impurity level and the active elements in HEA were the key factors that caused inclusion formation.

Research Article
A novel wood-plastic composite fabricated via modified steel slag: preparation, mechanical and flammability properties
Ling Zhao, Kai Zhao, Zhenwen Shen, Yifan Wang, Xiaojie Xia, Hao Zhang, and  Hongming Long
, Available online 16 January 2024, https://doi.org/10.1007/s12613-024-2829-4
Abstract:

A novel method was developed to enhance the utilization rate of steel slag (SS). By treating SS with phosphoric acid and aminopropyl triethoxysulane (KH550), we obtained modified steel slag (MSS), which was used to replace talcum powder (TP) in the preparation of modified steel slag/wood-plastic composites (MSS/WPCs). The composites were fabricated through melting blending and hot pressing. Their mechanical properties were systematically investigated as well as the combustion properties comprising heat release, smoke release, and thermal stability. The MSS could improve the mechanical strength of the composites through grafting reactions between wood powder and thermoplastics. Notably, MSS/WPC#50 (16wt% MSS) with a MSS-to-TP ratio of 1:1 exhibited an optimal comprehensive performance. Compared to WPC#0 without MSS, the tensile, flexural and impact strengths of MSS/WPC#50 were increased by 18.5%, 12.8%, and 18.0%, respectively. Moreover, the MSS/WPC#50 sample achieved the highest limited oxygen index (LOI) of 22.5% among all the samples, the highest UL-94 vertical burning rating at V-1, and the lowest horizontal burning (HB) rate at 44.2 mm/min. The enhanced thermal stability and significant reduction in heat and smoke release of MSS/WPC#50 can be attributed to the formation of a dense and stable char layer. However, partial replacement of TP with MSS slightly compromised the mechanical and flame-retardant properties, possibly due to weak grafting caused by SS powder agglomeration. These findings suggest that MSS/WPCs are suitable for high-value added applications as decorative panels indoors or outdoors.

Research Article
Analysis of explosion wave interactions and rock breaking effect in dual initiation
Renshu Yang, Jinjing Zuo, Liwei Ma, Yong Zhao, Zhen Liu, and  Quanmin Xie
, Available online 16 January 2024, https://doi.org/10.1007/s12613-024-2830-y
Abstract:

In blasting engineering, the location and number of detonation points, to a certain extent, determine the propagation direction of the explosion stress wave and blasting effect. In this study, the explosion wave field and rock-breaking effect are investigated on three aspects: shock wave collision, stress change of the blast hole wall in the collision zone, and crack propagation in the collision zone. The intensity of the resulting shock wave on the collision surface exceeded the sum of the intensities of the two colliding explosion shock waves. At the collision location, the kinetic energy was converted into potential energy with a decrease in the particle velocity at the wave front, and the wave front pressure increased. The expansion form of the superposed shock wave was dumbbell-shaped, the shock wave velocity in the collision area was higher than the radial shock wave velocity, and the average propagation angle of the explosion shock waves was approximately 60°. Accordingly, the relation between the blast hole wall stress and the explosion wave propagation angle in the superposition area was fitted. Under the experimental conditions, the superimposed explosion wave stress of the blast hole wall was approximately 1.73 times the single-explosion wave incident stress. The model test and numerical simulation results showed that large-scale radial fracture cracks were formed on the blast hole wall in the superimposed area, and the crack width increased. The width of the large-scale radial fracture cracks formed by a strong impact was approximately 5% the blast hole length. Based on the characteristics of blast hole wall compression, the mean peak pressure of the strongly superimposed area was approximately 1.48 and 1.84 times those of the weakly superimposed and nonsuperimposed areas, respectively.

Research Article
Rapid Prediction of Flow and Concentration Fields in Solid-Liquid Suspension of Slurry Electrolysis Tank
Tingting Lu, Kang Li, Hongliang Zhao, Wei Wang, Zhenhao Zhou, Xiaoyi Cai, and  Fengqin Liu
, Available online 12 January 2024, https://doi.org/10.1007/s12613-024-2826-7
Abstract:

Slurry electrolysis (SE), as a hydrometallurgical process, has the characteristic of multi-tank series connection, which leads to various stirring conditions and complex solid suspension state. For computational fluid dynamics (CFD) require highly computing resources, it was proposed to use a combination of CFD and machine learning to construct a rapid prediction model for the liquid flow and solid concentration fields in the SE tank. By scientifical selecting calculation samples through orthogonal experiments, the comprehensive dataset covering a wide range of conditions was established while effectively reducing simulation number and providing reasonable weights for each factor. Then a prediction model of the SE tank was constructed using the KNN algorithm. The results shown that with an increase of levels in the orthogonal experiments, the prediction accuracy of the model significantly improves. Among them, the model established with 4 factors and 9 levels can accurately predict the flow and concentration fields, for the regression coefficient of average velocity and solid concentration can achieve 0.926 and 0.937, respectively. Compared with the traditional CFD, the response time of fields information predicting was reduced from 75 hours to 20 seconds, which solves the problem of serious lag in CFD applied to actual production, and meets the real-time production control requirements.

Research Article
Effect of the pyrite content on chalcopyrite flotation in the presence of different regrinding conditions
Zejun Wang, Qing Shi, Guofan zhang, Yuxuan zhu, and  Binbin li
, Available online 12 January 2024, https://doi.org/10.1007/s12613-024-2828-5
Abstract:

This study aimed to investigate the impact of varying contents of pyrite on copper in the presence of different regrinding conditions, which were altered by using two types of grinding media, iron and ceramic balls, followed by flotation in the cleaner stage. It was found that the flotation performance of rougher copper concentrate can be improved by changing the regrinding conditions based on the content of pyrite. SEM-EDS (scanning electron microscope), X-ray spectrometer, EDTA extraction and XPS (X-ray photoelectron spectroscopy) studies illustrated that when the pyrite content was high, using iron media to regrind was beneficial to promote the generation of hydrophilic FeOOH on the surface of pyrite and improve copper grade. While using ceramic media for low pyrite content would avoid too much FeOOH covering the surface of chalcopyrite. Electrochemical studies further showed that the galvanic corrosion current of chalcopyrite-pyrite increased with the addition of pyrite and became stronger with the participation of iron media.

Research Article
Structure characterization of the oxide film on FGH96 superalloy powders with various oxidation degrees
Yang Liu, Yufeng Liu, Sha Zhang, Lin Zhang, Peng Zhang, Shaorong Zhang, Na Liu, Zhou Li, and  Xuanhui Qu
, Available online 3 January 2024, https://doi.org/10.1007/s12613-024-2823-x
Abstract:

The structure of the oxide film on FGH96 alloy powders significantly influence mechanical properties of superalloys. In this study, FGH96 alloy powders with various oxygen contents were investigated by HRTEM and 3DAP techniques to elucidate the structure evolution of the oxide film. EDS analysis reveals the presence of two distinct components in the oxide film of the alloy powders: Amorphous oxide layer covering the γ matrix and amorphous oxide particles above the carbide. The alloying elements within the oxide layer emerges a laminated distribution, followed by Ni, Co, Cr, Al/Ti, which is attributed to the decreasing oxygen equilibrium pressure as oxygen diffuses from the surface into the γ matrix. On the other hand, Ti enrichment was observed in the oxide particles caused by the oxidation and decomposition of the carbide phase. Comparative analysis of the oxide film with oxygen contents of 140 ppm, 280 ppm, and 340 ppm shows similar elements distributions, while the thickness of the oxide film varies approximately at 9 nm, 14 nm, and 30 nm, respectively. These findings provide valuable insights into the structure of FGH96 alloy powders.

Research Article
Recycling arsenic-containing bio-leaching residue in cemented paste backfill after thermal treatment: Structure modification, binder properties and environmental assessment
Dengfeng Zhao, Shiyu Zhang, and  Yingliang Zhao
, Available online 3 January 2024, https://doi.org/10.1007/s12613-024-2825-8
Abstract:

The substantial arsenic (As) content present in arsenic-containing bio-leaching residue (ABR) poses significant environmental challenges. Given its elevated calcium sulfate content, ABR exhib-its considerable promise for industrial applications. This study delved into the feasibility of utilizing ABR as a source of sulfates for producing super sulfated cement (SSC), offering an innovative bind-er for cemented paste backfill (CPB). Thermal treatment at varying temperatures of 150 °C, 350 °C, 600 °C, and 800 °C was employed to modify ABR's performance. The investigation encompassed the examination of phase transformations and alterations in the chemical composition of As within ABR. Subsequently, the hydration characteristics of SSC utilizing ABR, with or without thermal treatment, were studied, encompassing reaction kinetics, setting time, strength development, and microstructure. The findings revealed that thermal treatment changed the calcium sulfate structure in ABR, consequently impacting the resultant sample performance. Notably, calcination at 600 °C demonstrated optimal modification effects on both early and long-term strength attributes. This en-hanced performance can be attributed to the augmented formation of reaction products and a densi-fied microstructure. Furthermore, the thermal treatment elicited modifications in the chemical As fractions within ABR, with limited impact on the As immobilization capacity of the prepared bind-ers.

Research Article
Spray pyrolysis feasibility of tungsten substitution for cobalt in nickel-rich cathode materials
Zihan Hou, Lisheng Guo, Xianlong Fu, Hongxian Zheng, Yuqing Dai, Zhixing Wang, Hui Duan, Mingxia Dong, Wenjie Peng, Guochun Yan, and  Jiexi Wang
, Available online 3 January 2024, https://doi.org/10.1007/s12613-024-2824-9
Abstract:

Cobalt plays an indispensable role in stabilizing the lattice structure of high-capacity Ni-rich cathode materials. However, the extravagant price and toxicity still limit its development. Generally, it is feasible for the use of transition metal substitution to reduce the Co content. Whereas the conventional co-precipitation method could not meet the requirements of multi-element co-precipitation and uniform distribution of elements due to the differences between element concentration and deposition rate. Herein, spray pyrolysis is introduced to prepare LiNi0.9Co0.1-xWxO2 (LNCW). Particularly, the pyrolysis behavior of ammonium metatungstate is studied together with the W substitution for Co. With the feasibility of spray pyrolysis, the Ni-Co-W contained oxide precursor shows a homogeneous distribution of metal elements, which is beneficial to uniform substituting of W in the final materials. It is found that with W substitution, the size of primary particles shows a decreasing trend from 338.06 nm to 71.76 nm and the cation disordering is low to 3.34%. As a result, the prepared LNCW shows significantly improved electrochemical performance. In the optimal conditions, the lithium-ion battery assembled with the LiNi0.9Co0.025W0.075O2 (LNCW-0.75%) sample exhibits enhanced capacity retention of 82.7% after 200 cycles, which provides insight into the development of Ni-rich and low-cobalt materials. The results show that W can compensate for the loss caused by Co deficiency to a certain extent.

Research Article
Study on the interaction of cyanide with pyrite and the decyanation of pyrite cyanide residue
Wenwen Han, Hongying Yang, and  Linlin Tong
, Available online 27 December 2023, https://doi.org/10.1007/s12613-023-2814-3
Abstract:

The toxic cyanides in cyanide residues produced by cyanidation process for gold extraction are harmful to environment. Pyrite (Py) is one of the main minerals in cyanide residues. The interaction of cyanide with pyrite and the decyanation of pyrite cyanide residue were investigated in this study. The results showed that high pH, high cyanide concentration and high pyrite dosage promoted the interaction of cyanide with pyrite. The cyanidation of pyrite was of pseudo-second-order with respect to cyanide. The decyanation of pyrite cyanide residue by Na2SO3/Air oxidation was conducted. The cyanide removal efficiency was 83.9% after 1 h reaction time under optimal conditions: pH 11.2, SO32⁻ dosage of 22 mg∙g⁻1 Py and air flow of 1.46 L∙min⁻1. X-ray Photoelectron Spectroscopy (XPS) analysis of pyrite samples demonstrated the formation of Fe(Ⅲ) and FeSO4 during the cyanidation process. The cyanide adsorbed on the pyrite surface mainly existed in the forms of free cyanide (CN⁻) and ferrocyanide (Fe(CN)64⁻) after cyanidation, which were effectively removed by Na2SO3/Air oxidation. During the decyanation process, the air intake promoted the oxidation of pyrite and weakened the adsorption of cyanide on the pyrite surface. This study has practical significance for the gold enterprises aiming to mitigate the environmental impact associated with cyanide residues.

Research Article
Hydrogen-based mineral phase transformation mechanism investigation of pyrolusite ore
Ruofeng Wang, Shuai Yuan, Yanjun Li, Peng Gao, Hai Ning, and  Ru Li
, Available online 27 December 2023, https://doi.org/10.1007/s12613-023-2819-y
Abstract:

Pyrolusite comprise as the foremost manganese oxides and a major source of manganese production. Application of an innovative hydrogen-based mineral phase transformation technology to pyrolusite is proposed, where 96.44% distribution rate of divalent manganese(Mn2+) at an optimum roasting temperature of 650 °C, a roasting time of 25 min, and an H2 concentration of 20 at.% was observed, at which time the manganese existed predominantly in the form of manganosite. This study investigated the generation mechanism of manganosite from the viewpoint of reduction kinetics, phase transformation and structural evolution of pyrolusite, indicating that the high temperature contributes toward improvement of the distribution rate; while the optimal kinetic model for the reaction the A3/2 model of random nucleation and subsequent growth with an activation energy (E) of 24.119 kJ·mol-1 and a pre-exponential factor A of 0.03229 s-1. Throughout the process of mineral phase transformation, the manganese oxide from the outer layer of particles to move inward to the core. In addition, pyrolusite follows the reduction sequence of MnO2→Mn2O3→Mn3O4→MnO, and the reduction of manganese oxides in each valence state proceeds simultaneously. The findings provide a significant insight into the efficient and clean utilization of pyrolusite.

Research Article
Temperature sensing array utilizing the metal to insulator transition of NdxSm1-xNiO3
Fengbo Yan, Ziang Li, Hao Zhang, Yuchen Cui, Kaiqi Nie, Nuofu Chen, and  Jikun Chen
, Available online 27 December 2023, https://doi.org/10.1007/s12613-023-2816-1
Abstract:

The rare-earth nickelates (ReNiO3) exhibit widely tunable metal-to-insulator transition (MIT) properties with negligible variations in lattice constants and small latent heat across the critical temperature (TMIT). In particular, it is worth noticing that compared to the more commonly investigated vanadium oxides, the MIT of ReNiO3 is less abrupt but is usually across wider range of temperature. This sheds a light on their alternative applications as negative temperature coefficient resistance (NTCR) thermistors with high sensitivity compared to the existing NTCR thermistor, other than their expected usage as critical temperature resistance (CTR) thermistors. Herein, we demonstrate the NTCR thermistor functionality for using the adjustable MIT of NdxSm1-xNiO3 within 200-400 K that shows larger magnitudes of NTCR (e.g., more than 7 %/K) that is unachievable in conventional NTCR thermistor materials. The temperature dependence of resistance (R-T) shows sharp variation during the MIT of NdxSm1-xNiO3 across a temperature range of 200-400 K with no hysteresis via decreasing the content of Nd (e.g., 0<x<0.2), and such ρ-T tendency can be linearized by introducing optimum parallel resistor. The sensitive range of temperature can be further extended to 210-360 K, via combining a series of NdxSm1-xNiO3 with 8 rare-earth co-occupation ratios and TMIT as an array, with high magnitude of NTCR (e.g., 7-14 %/K) covering the entire range of temperature.

Research Article
Ultra-broadband microwave absorber and high-performance pressure sensor based on aramid nanofibers/polypyrrole/nickel porous aerogel
Leyi Zhang, Hongyu Jin, Hanxin Liao, Rao Zhang, Bochong Wang, Jianyong Xiang, Congpu Mu, Kun Zhai, Tianyu Xue, and  Fsuehng Wen
, Available online 27 December 2023, https://doi.org/10.1007/s12613-023-2820-5
Abstract:

With the widespread use of electronic devices, microwave absorbers and wearable sensor devices appear in all walks of life. The aramid nanofibers/polypyrrole/nickel (APN) aerogels can be used as microwave absorber and pressure sensor simultaneously. In this work, aramid nanofibers/polypyrrole (AP15) aerogels (the mass ratio of aramid nanofibers to pyrrole was 1:5) were prepared by the oxidative polymerization method and then the nickel was thermally evaporated on the surface of AP15 aerogels for preparing the ultralight (9.35 mg cm-3) APN aerogel with porous structure. The introduction of nickel was aiming to increase magnetic loss and adjust impedance matching, further improve electromagnetic wave absorption performance. The minimum reflection loss value reached -48.7 dB, and the maximum effective absorption bandwidth was 8.42 GHz with the thickness of 2.9 mm, which was attributed to the three-dimensional network porous structure and perfect impedance matching. Moreover, aramid nanofibers and three-dimensional hole structure made APN aerogels have good insulation, flame retardant, and compression resilience (500 cycles under compression strain of 50%). The polypyrrole and nickel particles enhanced the conductivity, and the final APN aerogel sensor processed highly sensitive (10.78 kPa-1) and thermal stability. APN aerogels have significant potential in ultra-broadband microwave absorbers and pressure sensors.

Research Article
Study on the trip-assisted Si-Mn steel with excellent comprehensive performance obtained through direct strip casting
Hui Xu, Lejun Zhou, Wanlin Wang, and  Yang Yi
, Available online 27 December 2023, https://doi.org/10.1007/s12613-023-2818-z
Abstract:

Two near final shape continuous casting process (direct strip casting (DSC) and compact strip production (CSP)) combined quenching & partitioning (Q&P) heat treatment routes were applied to a low carbon Si–Mn steel to create different initial microstructure before heat treatment and finally obtain a new combination of mechanical properties. The initial structure of the DSC sample is a composite structure of lath martensite and bainite. Compared with the pearlite and ferrite initial structure of CSP sample, the DSC as-cast sample shows higher comprehensive mechanical properties. After the same Q&P treatment, the DSC samples generally showed better comprehensive mechanical properties compared to the CSP samples. An optimum comprehensive mechanical property was achieved in DSC-Pt300 samples with yield strength (YS) ~ 1282 MPa, ultimate tensile strength (UTS) ~ 1501 MPa, total elongation (TE) ~ 21.5% and the production of strength and elongation (PSE) higher to 32.3 GPa%. The enhanced mechanical properties were discussed based on the distribution characteristics of each phase in the matrix, the volume fraction and carbon content of retained austenite (RA). This work has achieved the goal of obtaining excellent mechanical properties in the low-alloy trip-assisted Si-Mn steel through a simple process, demonstrating the superiority of DSC technology in manufacturing AHSSs, which has important guiding significance for the short process production of AHSSs.

Research Article
Cooperative effect of SLS collector and SPP depressant on the flotation separation of lead oxide minerals from hematite
Honghu Tang, Bingjian Liu, Mengshan Li, Qiancheng Zhang, Xiongxing Zhang, and  Feng Jiang
, Available online 27 December 2023, https://doi.org/10.1007/s12613-023-2815-2
Abstract:

As a cornerstone of the national economy, the iron and steel industry also generates a significant amount of sintering dust containing both valuable lead resources and deleterious elements. Flotation is a promising technique for lead recovery from sintering dust, but efficient separation from Fe2O3 is still challenging. This study investigated the cooperative effect of sodium lauryl sulfate (SLS, C12H25SO4Na) and sodium pyrophosphate (SPP, Na4P2O7) on the selective flotation of lead oxide minerals (PbOHCl and PbSO4) from hematite (Fe2O3). Optimal flotation conditions were first identified, resulting in high recovery of lead oxide minerals while inhibiting Fe2O3 flotation. Zeta potential measurements, FTIR analysis, adsorption capacity analysis, and XPS studies offer insights into the adsorption behaviors of the reagents on mineral surfaces, revealing strong adsorption of SLS on PbOHCl and PbSO4 surfaces and remarkable adsorption of SPP on Fe2O3. The proposed model of reagent adsorption on mineral surfaces illustrates the selective adsorption behavior, highlighting the pivotal role of reagent adsorption in the separation process. These findings contribute to the efficient and environmentally friendly utilization of iron ore sintering dust for lead recovery, paving the way for sustainable resource management in the iron and steel industry.

Research Article
Microstructure evolution and strengthening mechanism of high-performance powder metallurgy TA15 titanium alloy by hot rolling
Ying Gao, Ce Zhang, Jiazhen Zhang, and  Xin Lu
, Available online 15 December 2023, https://doi.org/10.1007/s12613-023-2809-0
Abstract:

Hot deformation of sintered billets by powder metallurgy (PM) is one of the effective preparation techniques of titanium alloys, which is more significant for high-alloying alloys. In this study, Ti-6.5Al-2Zr-Mo-V (TA15) titanium alloy plates were prepared by cold pressing sintering combined with high temperature hot rolling, and the microstructure and mechanical properties under different process parameters were investigated, and OM, EBSD et.al were applied to characterize the microstructure evolution and mechanical properties strengthening mechanism. The results indicated that the chemical compositions were uniformly diffused without segregation during sintering, and the closing of the matrix craters were accelerated by increasing the sintering temperature. The block was hot rolled at 1200°C with 80% reduction under only two passes without annealing, and the ultimate strength and elongation of the plate at room temperature after solution and aging were 1247 MPa and 14.0%, respectively, which were increased by 24.5% and 40.0%, respectively, compared with the as-sintered alloy at 1300℃. The microstructure was significantly refined by continuous dynamic recrystallization (CDRX), which was completed by the rotation and dislocations absorption of the substructure surrounded by low angle grain boundaries (LAGBs). The strength and plasticity of PM-TA15 alloy after hot rolling combined with heat treatment were improved, which was resulted from the dense, uniform and fine recrystallization structure and the synergistic effect of multiple slip systems.

Research Article
Upcycling the retired graphite/LiCoO2 batteries for the high voltage graphite/LiCoPO4-co-workable dual-ion batteries
Miao Du, Hongyan Lü, Kaidi Du, Shuohang Zheng, Xiaotong Wang, Xiaotong Deng, Ronghua Zeng, and  Xinglong Wu
, Available online 8 December 2023, https://doi.org/10.1007/s12613-023-2807-2
Abstract:

Worldwide proliferation of portable electronics has created a dramatic increase of retired lithium-ion batteries (LIBs). However, under the premise of such huge amounts of retired LIBs, the traditional recycling methods still have shortcomings. Therefore, we proposed an eco-friendly and sustainable double recycling strategy to concurrent reuse the cathode (LiCoO2) and anode (graphite) materials of retired LIBs and used recycled LiCoPO4/graphite (RLCPG) in Li+/PF6- co-de/intercalation dual-ion batteries. In addition, the recycle-derived dual-ion batteries of Li/RLCPG show an impressive electrochemical performance, e.g., appropriate initial reversible discharge capacity of 86.2 mA h g-1 at 25 mA g-1 and 69% capacity retention after 400 cycles. Dual recycling of cathode and anode from retired LIBs not only avoids wastage of resources, but also yields cathode materials with excellent performance, which provide an eco-friendly and sustainable way to design novel secondary batteries.

Research Article
Particle aggregation and breakage kinetics in cemented paste backfill
Liuhua Yang, Hengwei Jia, Aixiang Wu, Huazhe Jiao, Xinming Chen, Yunpeng Kou, and  Mengmeng Dong
, Available online 8 December 2023, https://doi.org/10.1007/s12613-023-2804-5
Abstract:

The macroscopic flow behavior and rheological properties of cemented paste backfill (CPB) are highly impacted by the inherent structure of the paste matrix. In this study, the effects of shear-induced forces and proportioning parameters on the microstructure of fresh CPB were studied. The size evolution and distribution of floc/agglomerate/particles of paste were monitored by focused beam reflection measuring (FBRM) technique, and the influencing factors of aggregation and breakage kinetics of CPB were discussed. The results indicate that influenced by both internal and external factors, the paste kinetics evolution covers the dynamic phase and the stable phase. Increasing the mass concentration or the cement-tailings ratio can accelerate aggregation kinetics, which is advantageous for the rise of average floc size. Besides, the admixture and high shear can improve breaking kinetics, which is beneficial to reduce the average floc size. The chord length resembles a normal distribution somewhat, with a peak value of approximate 20μm. k1 is positively correlated with the agitation rate, and k2 is five orders of magnitude greater than k1. The kinetics model depicts the evolution law of particles over time quantitatively and provides a theoretical foundation for the micromechanics of complicated rheological behavior of paste.

Research Article
Metallurgical performance evaluation of space-weathered Chang'E-5 lunar soil
Chen Li, Wenhui Ma, Yang Li, and  Kuixian Wei
, Available online 1 December 2023, https://doi.org/10.1007/s12613-023-2800-9
Abstract:

Space metallurgy is an interdisciplinary field of planetary space science and metallurgical engineering, and it is a systematic and theoretical engineering technology for planetary in-situ resource utilization. However, without an atmosphere and magnetic field, lunar surface has experienced space weathering. The microstructure of lunar soil is different from the minerals on Earth, which limits the development of space metallurgy. In this study, SEM and TEM analyses were performed on Chang'e 5 powder lunar soil samples. The characteristics of the lunar soil's microstructure may drastically change its metallurgical performance. The main special structures of the lunar soil minerals include the nano-phase iron formed by the impact of micrometeorites; the amorphous layer by solar-wind injection; radiation tracks modified by high-energy particle rays inside mineral crystals etc. The wide distribution of nanophase iron may have a greater impact on the electromagnetic properties of the lunar soil. Hydrogen ions injected by the solar wind may promote the hydrogen reduction process. The widely distributed amorphous layer and impact glass can help the melting and diffusion process of lunar soil. Therefore, while high-energy events on the lunar surface are transforming the lunar soil, they are also increasing the chemical activity of the lunar soil. This is a property that earth samples and traditional simulated lunar soil do not possess. Carrying out space metallurgy requires comprehensive consideration of the unique physical and chemical properties of the lunar soil.

Research Article
MgO-attached graphene nanosheet (MgO@GNS) reinforced magnesium matrix nanocomposite with superior mechanical, corrosion and biological performance
S. Abazari , Ali Shamsipur, Hamid Reza Bakhsheshi-Rad, M.S. Soheilirad, F. Khorashadizade, and  S.S. Mirhosseini
, Available online 1 December 2023, https://doi.org/10.1007/s12613-023-2797-0
Abstract:

Magnesium (Mg) alloys are gaining great consideration as body implant materials due to their high biodegradability and biocompatibility. However, they suffer from low corrosion resistance and antibacterial activity. In this research, semi-powder metallurgy followed by hot extrusion was utilized to produce the magnesium oxide@graphene nanosheets/magnesium (MgO@GNS/Mg) composite to improve mechanical, corrosion and cytocompatibility characteristics. Investigations have revealed that the incorporation of MgO@GNS nanohybrids into Mg-based composite enhanced microhardness and compressive strength. In vitro osteoblast cell culture tests show that using MgO@GNS nanohybrid fillers enhances osteoblast adhesion and apatite mineralization. The presence of MgO@GNS nanoparticles in the composites decreased the opening defects, micro-cracks and micro-pores of the composites thus prevented the penetration of corrosive solution into the matrix. Studies demonstrated that MgO@GNS/Mg composite possesses excellent antibacterial properties because of the combination of the release of MgO and physical damage to bacterium membranes caused by the sharp edges of graphene nanosheets that can effectively damage the cell wall thereby facilitating penetration into the bacterial lipid bilayer. Therefore, the MgO@GNS/Mg composite with high mechanical strength, antibacterial activity and corrosion resistance is considered to be a promising material for load-bearing implant applications.

Research Article
Self-growing ZnFe2O4 on Cu9S5 surface for enhance multi-polarization to construct 3D flower-like composites with high-performance electromagnetic wave absorption
Wenxiong Chen and  Honglong Xing
, Available online 25 November 2023, https://doi.org/10.1007/s12613-023-2795-2
Abstract:

The development of 3D structural composites with electromagnetic wave absorption properties is a means to attenuate electromagnetic waves. Herein, magnetized flower-like Cu9S5/ZnFe2O4 composites were designed by a multi-step hydrothermal method. The results of crystallographic information, surface phase chemical information, morphological structure, magnetic and electromagnetic parameters of the composites were analyzed. The prepared Cu9S5/ZnFe2O4 composites have multiple loss paths to electromagnetic waves, composites showed an overall 3D flower-like structure. The Cu9S5/ZnFe2O4 composite achieves a minimum reflection loss of −54.38 dB and a broad effective absorption bandwidth of 5.92 GHz. By magnetization modification of the material, ZnFe2O4 particles are self-assembled and grown on the surface of Cu9S5, which is conducive to the generation of more cross-linking contact sites, the introduction of a large number of phase interfaces, crystalline defects, and special three-dimensional floral structures, and the effective introduction of magneto-electrical coupling loss effects, and the synergistic effect of the multiple loss strategies effectively improves the electromagnetic wave absorption performance of the material. This work can provide a strategic for the use of magnetization modified sulfide composite functional materials in the field of electromagnetic wave absorption.

Research Article
Enhancing the mechanical properties and high-temperature oxidation of a press hardened steel by the addition of Cr and Si
Rong Zhu, Yonggang Yang, Baozhong Zhang, Borui Zhang, Lei Li, Yanxin Wu, and  Zhenli Mi
, Available online 25 November 2023, https://doi.org/10.1007/s12613-023-2796-1
Abstract:

Cr and Si are added to a press hardened steel, and their effects on the mechanical properties and oxidation resistance are investigated. Results indicate that the microstructure of the Cr-Si micro-alloyed press hardened steel consisted of lath martensite, M23C6 carbides, and retained austenite. The retained austenite and carbides are responsible for the increase in elongation of the micro-alloyed steel. In addition, after oxidation at 930°C for 5 min, the thickness of the oxide scales on the Cr-Si micro-alloyed press hardened steel is less than 5 μm, much thinner than the 45.50 μm-thick oxide scales on 22MnB5. The oxide scales of the Cr-Si micro-alloyed steel are composed of Fe2O3, Fe3O4, the mixed spinel oxide (FeCr2O4 and Fe2SiO4), and amorphous SiO2. Adding Cr and Si significantly reduces the thickness of the oxide scales and prevents the generation of the FeO phase. Due to the increase of spinel FeCr2O4 and Fe2SiO4 phase in the inner oxide scale and the amorphous SiO2 close to the substrate, the oxidation resistance of the Cr-Si micro-alloyed press hardened steel is improved.

Research Article
Low-firing and temperature stability regulation of tri-rutile MgTa2O6 microwave dielectric ceramics
Chengzhi Xu, Hongyu Yang, Hongcheng Yang, Linzhuang Xing, Yuan Wang, Zhimin Li, Enzhu Li, and  Guorui Zhao
, Available online 21 November 2023, https://doi.org/10.1007/s12613-023-2791-6
Abstract:

A glass frit containing Li2O–MgO–ZnO–B2O3–SiO2 component was used to explore the low-temperature sintering behaviors and microwave dielectric characteristics of tri-rutile MgTa2O6 ceramics in this study. The good low-firing effects are presented due to the high matching relevance between Li2O–MgO–ZnO–B2O3–SiO2 glass and MgTa2O6 ceramics. The pure tri-rutile MgTa2O6 structure remains unchanged, and high sintering compactness can also be achieved at 1150oC. We found that the Li2O–MgO–ZnO–B2O3–SiO2 glass not only greatly improves the low-temperature sintering characteristics of MgTa2O6 ceramics but also maintains a high Q×f value while still improving the temperature stability. Typically, great microwave dielectric characteristics when added with 2wt% Li2O–MgO–ZnO–B2O3–SiO2 glass can be achieved at 1150oC: εr = 26.1, Q×f = 34267 GHz, τf = -8.7 ppm/°C.

Research Article
Synergistic strengthening mechanism of Ca2+ - Sodium silicate to selective separation of feldspar and quartz
Bo Lin, Jingzhong Kuang, Yiqiang Yang, Zheyu Huang, Delong Yang, and  Mingming Yu
, Available online 21 November 2023, https://doi.org/10.1007/s12613-023-2790-7
Abstract:

Enhancing the selectivity of flotation reagents is of utmost importance to improve the effectiveness of separation. In this study, a combined inhibitor was used utilizing Sodium silicate (SS) and Ca2+ to separate quartz and feldspar in near-neutral pulp. Selective inhibition of the combined inhibitor was assessed by micro-flotation experiments. And a series of detection methods were used to detect differences in the surface properties of feldspars and quartz after flotation agents and to put forward a synergistic strengthening mechanism. The outcomes were pointed out that pre-mixing combined inhibitors were more effective than the addition of Ca2+ and SS in sequence under the optimal proportion of 1:5. A concentrate from artificial mixed minerals that was characterized by a high quartz grade and a high recovery was acquired, and was found to be 90.70% and 83.70%, respectively. It was demonstrated that the combined inhibitor selectively prevented the action of the collector and feldspar from FT-IR and adsorption capacity tests. The results of XPS indicated that Ca2+ directly interacts with the surface of quartz to increase the adsorption of collectors. In contrast, the chemistry of Al on the feldspar surface was altered by combined inhibitor, with Na+ and Ca2+ taking the place of K+. It is possible that the composite inhibitor forms a hydrophilic structure, which prevents the adsorption of the collector on the surface of feldspar by interacting with the Al active site. The combination of Ca2+ and SS synergically strengthens the difference of collecting property between quartz and feldspar by collector, thus achieving the effect of efficient separation.

Research Article
Porous high-entropy rare earth phosphates (REPO4, RE = La, Sm, Eu, Ce, Pr, and Gd) ceramic with excellent thermal insulation performance via pore structure tailoring
Peixiong Zhang, Enhui Wang, Jingjing Liu, Tao Yang, Hailong Wang, and  Xinmei Hou
, Available online 21 November 2023, https://doi.org/10.1007/s12613-023-2788-1
Abstract:

Thermal insulation materials are playing an increasingly important role in protecting mechanical parts served at high temperature. In this work, novel porous high-entropy (La1/6Ce1/6Pr1/6Sm1/6Eu1/6Gd1/6)PO4 (HE (6RE1/6)PO4) ceramics have been prepared firstly with the aid of the HE strategy in combination with the pore-forming agent method. The effect of different starch contents (0-60vol%) on the comprehensive properties of porous HE (6RE1/6)PO4 ceramics is systematically investigated. The results show that porous HE (6RE1/6)PO4 ceramics containing 60vol% starch exhibit the lowest thermal conductivity of 0.061 W·m−1·K−1 at room temperature and good pore structure stability with the linear shrinkage of approximate 1.67%. Furthermore, the influence of larger regular spherical pores on thermal insulation performance is discussed and the optimal thermal conductivity prediction model is also screened. The superior comprehensive properties allow porous HE (6RE1/6)PO4 ceramics to be promising insulation materials in the future.

Research Article
A froth velocity measurement method based on improved U-Net++ semantic segmentation in flotation process
Yiwei Chen, Degang Xu, and  Kun Wan
, Available online 21 November 2023, https://doi.org/10.1007/s12613-023-2787-2
Abstract:

During flotation, the features of the froth image are highly correlated with the concentrate grade and the corresponding working conditions. And the static features such as color and size of the bubbles and the dynamic features such as velocity have obvious differences between different working conditions. The extraction of these features is typically relied on the outcomes of image segmentation at the froth edge, making the segmentation of froth image the basis for studying its visual information. Meanwhile, the absence of scientifically reliable training data with label and the necessity to manually construct dataset and label make the study difficult in the mineral flotation. To solve this problem, this paper constructs a tungsten concentrate froth image dataset, and proposes a cGAN-based data augmentation network and a U-Net++-based edge segmentation network. The performance of this algorithm is also evaluated and contrasted with other algorithms in this paper. On the results of semantic segmentation, a phase-correlation based velocity extraction method is finally suggested.

Research Article
Effect of dissolved-oxygen on the flotation behavior of pyrite at high altitude area
Yan Miao, Guangke Ye, and  Guofan Zhang
, Available online 10 November 2023, https://doi.org/10.1007/s12613-023-2784-5
Abstract:

With the continuous development of mineral resources to high altitude areas, the study of sulfide ore flotation in unconventional systems has been emphasized. There is a consensus that moderate oxidation of sulfide ore is beneficial to flotation, but the specific suitable dissolved oxygen value is inconclusive, and there are few studies on sulfide ore flotation under low dissolved oxygen environment at high altitude. In this paper, we designed and assembled an atmosphere simulation flotation equipment to simulate the flotation of pyrite at high altitude by controlling the partial pressure of N2/O2 and dissolved oxygen under atmospheric conditions, and used XPS, AFM, FTIR, UV/VIS, zeta potential and contact angle measurements to reveal the effects of surface oxidation and agent adsorption on pyrite at high altitude (4600m DO=4.0mg/L). The results of pure mineral flotation indicate that the high altitude and low dissolved oxygen environment is favorable for pyrite flotation. Contact angle measurements and XPS analysis showed that the high altitude atmosphere slows down the oxidation of pyrite surface, facilitates Sn2-/S0 production and enhances surface hydrophobicity. Electrochemical calculations and zeta potential analysis showed that the influence of atmosphere on the form of pyrite adsorption was small, and the different atmospheric conditions were consistent with dixanthogen electrochemical adsorption, with lower Zeta potential under high altitude atmosphere and significant potential shift after SIBX adsorption. The results of FTIR, UV/VIS and AFM analysis showed that SIBX adsorbed more on the surface of pyrite under high altitude atmosphere and adsorbed on the surface in a mesh structure composed of column/block. The results of the experimental study reveal the reasons for the easy flotation of sulfide ores at high altitude with less collector dosage, and confirm that the combined DO-pH regulation is beneficial to achieve more efficient flotation of pyrite.

Research Article
A thermodynamic perspective on electrode poisoning in solid oxide fuel cells
Kevin Huang
, Available online 10 November 2023, https://doi.org/10.1007/s12613-023-2783-6
Abstract:

One of the critical challenges to the commercialization of clean and high-efficiency solid oxide fuel cell (SOFC) technology is the insufficient stack lifespan caused by a variety of degradation mechanisms, which are associated with cell components and chemical feedstocks. Cell components related degradation refers to thermal/chemical/electrochemical deterioration of cell materials under operating conditions, whereas the latter regards impurities in feedstocks of oxidant (air) and reductant (fuel). This article provides a thermodynamic perspective on the understanding of the impurities-induced degradation mechanisms in SOFCs. The discussion focuses on using thermodynamic analysis to elucidate poisoning mechanisms in cathodes by impurity species such as Cr, CO2, H2O and SO2 and in the anode by species such as S (or H2S), SiO2, and P2 (or PH3). The author hopes the presented fundamental insights can provide a theoretical foundation for searching for better technical solutions to address the critical degradation challenges.

Research Article
Evolution of microstructure and properties of a novel Ni-based superalloy during stress relief annealing
Lei Jia, Heng Cui, Shufeng Yang, Shaomin Lv, Xingfei Xie, and  Jinglong Qu
, Available online 10 November 2023, https://doi.org/10.1007/s12613-023-2779-2
Abstract:

In this paper, the residual stress reduction, precipitation evolution, and mechanical properties of GH4151 alloy in different annealing temperatures were studied by the scanning electron microscope (SEM), high-resolution transmission electron microscopy (HRTEM), electron backscatter diffraction (EBSD). The results show that annealing treatment can effectively reduce residual stresses. With the increase of annealing temperature from 950 °C to 1150 °C, most of the residual stresses were released from 60.1 MPa to 10.9 MPa, and the corresponding stress relaxation mechanism changed from dislocation slip dominated to both dislocation slip and grain boundary migration. Meanwhile, the annealing treatment promotes the decomposition of the Laves, accompanied by the precipitation of μ-(Mo6Co7) starting at 950°C and reaching a maximum value at 1050°C. The tensile strength and plasticity of the annealing alloy at 1150℃ reached the maximum(1394 MPa, 56.1%) which was 131%, 200% fold than that of the as-cast alloy (1060 MPa, 26.6%), but the oxidation process in the alloy is accelerated at 1150℃. The increase in strength and plasticity are mainly attributed to the dissolution of the brittle phase and the morphology and distribution of the γ' phase.

Research Article
Study on the oxidation mechanism of Al-SiC composite at elevated temperature
Jishuo Han, Yong Li, Chenhong Ma, Qingyao Zheng, Xiuhua Zhang, and  Xiaofang Wu
, Available online 10 November 2023, https://doi.org/10.1007/s12613-023-2778-3
Abstract:

Resin-bonded Al-SiC composite was sintered at 1100°C, 1300°C, and 1500°C in the air, the oxidation mechanism was investigated by XRD and SEM, combined with thermodynamic calculations. The reaction models were also established. The oxidation resistance of the Al-SiC composite was significantly enhanced with temperature increase. SiC in the exterior of the composite was partially oxidized slightly, while the transformation of metastable Al4C3 to stable Al4SiC4 existed in the interior. At 1100°C, Al in the interior reacted with residual C to form Al4C3. Increasing to 1300°C, high temperature and low oxygen partial pressure lead to active oxidation of SiC, and internal gas composition transforms to Al2O(g)+CO(g)+SiO(g) as the reaction proceeds. After Al4C3 is formed, CO(g) and SiO(g) are continuously deposited on its surface, transforming to Al4SiC4. At 1500°C, a dense layer consisting of SiC and Al4SiC4 whiskers was formed which cut off the diffusion channel of oxygen. The active oxidation of SiC is accelerated, enabling more gas to participate in the synthesis of Al4SiC4, eventually forming hexagonal lamellar Al4SiC4 with mutual accumulation between SiC particles. Introducing Al enhances the oxidation resistance of SiC. In addition, the in situ generated non-oxide is uniformly dispersed on a micro-scale and bonds SiC stably.  

Research Article
Improving creep strength of the fine-grained heat-affected zone of novel 9Cr martensitic heat-resistant steel via modified thermo-mechanical treatment
Jingwen Zhang, Liming Yu, Yongchang Liu, Ran Ding, Chenxi Liu, Zongqing Ma, Huijun Li, Qiuzhi Gao, and  Hui Wang
, Available online 12 October 2023, https://doi.org/10.1007/s12613-023-2760-0
Abstract:
The infamous type IV failure within the fine-grained heat-affected zone (FGHAZ) in G115 steel weldments seriously threatens the safe operation of ultra-supercritical (USC) power plants. In this work, the traditional thermo-mechanical treatment was modified via the replacement of hot-rolling with cold rolling, i.e., normalizing, cold rolling, and tempering (NCT), which was developed to improve the creep strength of the FGHAZ in G115 steel weldments. The NCT treatment effectively promoted the dissolution of preformed M23C6 particles and relieved the boundary segregation of C and Cr during welding thermal cycling, which accelerated the dispersed reprecipitation of M23C6 particles within the fresh reaustenitized grains during post-weld heat treatment. In addition, the precipitation of Cu-rich phases and MX particles was promoted evidently due to the deformation-induced dislocations. As a result, the interacting actions between precipitates, dislocations, and boundaries during creep were reinforced considerably. Following this strategy, the creep rupture life of the FGHAZ in G115 steel weldments can be prolonged by 18.6%, which can further push the application of G115 steel in USC power plants.
Research Article
Growth kinetics of titanium carbide coating by molten salt synthesis process on graphite sheet surface
Xiaoyu Shi, Chongxiao Guo, Jiaomiao Ni, Songsong Yao, Liqing Wang, Yue Liu, and  Tongxiang Fan
, Available online 20 September 2023, https://doi.org/10.1007/s12613-023-2749-8
Abstract:

The synthesis of carbide coatings on graphite substrates using molten salt synthesis (MSS), has garnered significant interest due to its cost-effective nature. This study investigates the reaction process and growth kinetics involved in MSS, shedding light on key aspects of the process. The involvement of Ti powder through liquid-phase mass transfer is revealed, where the diffusion distance and quantity of Ti powder play a crucial role in determining the reaction rate by influencing the C concentration gradient on both sides of the carbide. Furthermore, the growth kinetics of the carbide coating are predominantly governed by the diffusion behavior of C within the carbide layer, rather than the chemical reaction rate. To analyze the kinetics, the thickness of the carbide layer is measured with respect to heat treatment time and temperature, unveiling a parabolic relationship within the temperature range of 700~1300℃. The estimated activation energy for the reaction is determined to be 179, 283 J mol−1. These findings offer valuable insights into the synthesis of carbide coatings via MSS, facilitating their optimization and enhancing our understanding of their growth mechanisms and properties for various applications.

Research Article
Process metallurgy and data driven prediction and feedback of blast furnace furnace heat indicators
Quan Shi, Jue Tang, and  Mansheng Chu
, Available online 17 June 2023, https://doi.org/10.1007/s12613-023-2693-7
Abstract:

The prediction and control of furnace heat indicator was of great significance to improve the furnace hot level and furnace condition for the complex and difficult to operate the hour-class delay blast furnace (BF) system. In this work, a prediction and feedback model of furnace heat indicator based on the fusion of data driven and BF ironmaking process was proposed. The data of raw and fuel materials, process operation, smelting state and slag and iron discharge during the whole BF process were comprehensively analyzed, a total of 171 variables, 9223 groups of data. A novel method of delay analysis of furnace heat indicator was established. and the extracted delay variables had played an important role in the modeling. Compared with the traditional machine learning algorithm, the method that combined the Genetic algorithm (GA) and Stacking was efficient to improve the performance. The hit rate for the predicting the temperature of hot metal in the error range of plus or minus 10 ℃ was 92.4%, and that for [Si] in the error range of plus or minus 0.1% was 93.3%. On the basis of the furnace heat prediction model and the expert experience, a feedback model of furnace heat operation was established to push the quantitative operation suggestions to stabilize the BF heat level, which had been highly recognized by the BF operators. Finally, this comprehensive and dynamic model had been successfully applied in the practical BF, and the BF temperature level was improved remarkably with the furnace temperature stability rate increasing from 54.88% to 84.89%, which had achieved significant economic benefits.

Research Article
Stress-assisted corrosion mechanism study of 3Ni steel based on gradient boosting decision tree machining-learning method
Xiaojia Yang, Jinghuan Jia, Qing Li, Renzheng Zhu, Jike Yang, Zhiyong Liu, Xuequn Cheng, and  Xiaogang Li
, Available online 22 April 2023, https://doi.org/10.1007/s12613-023-2661-2
Abstract:

Traditional 3Ni weathering steel cannot fully meet the requirement of offshore engineering development, the design of novel 3Ni steel with the addition of micro-alloy element such as Mn or Nb to enhance the strength has become a trend. In this study, the stress-assisted corrosion behavior of the novel designed high strength 3Ni steel is studied by corrosion big data method. The information of the corrosion process was recorded by using galvanic corrosion current monitoring method. Gradient boosting decision tree (GBDT) machine-learning method was used to mining the corrosion mechanism and the importance of the structure factor was studied. Field exposure tests were held to verify the results calculated by GBDT method. Results depict that GBDT method can be used to effectively study the influence of structural factor on the corrosion process of 3Ni steel. Different mechanism for the addition of Mn and Cu on the stress-assisted corrosion of 3Ni steel suggest that Mn and Cu have no obvious effect on the corrosion rate of non-stressed 3Ni steel in the early stage of corrosion, when the corrosion reaches a stable state, the increase of Mn element content can increase the corrosion rate of 3Ni steel, while Cu reduces the corrosion rate of 3Ni steel. The increase of Mn element content and Cu addition could inhibit the corrosion process in the presence of stress. The corrosion law of outdoor exposure 3Ni steel is consistent with the law based on corrosion big data technology, which verifies the reliability of big data evaluation method and data prediction model selection.

Special issue for the 30th Anniversary of IJMMM
Synergistic effect of gradient Zn content and multi-scale particles on the mechanical properties of Al-Zn-Mg-Cu alloys with coupling distribution of coarse / fine grains
Mingxing Guo and  Linzhong Zhuang
, Available online 1 March 2024, https://doi.org/10.1007/s12613-024-2871-2
Abstract:
The influence of graded Zn content on the evolution of precipitated and iron-rich phases and grain structure of the alloys was investigated, and the Al-8.0Zn-1.5Mg-1.5Cu-0.2Fe (wt.%) alloy with high strength and high formability was designed and developed. With the increase of Zn content, it is easier to form the coupling distribution of multi-scale precipitates and iron-rich phases with a reasonable matching ratio and dispersion distribution characteristics, which can induce the formation of cell-like structure with alternate distribution of coarse and fine grains, and the average plasticity-strain ratio r value (characterizing the formability) of the pre-aged alloy with a high strength is up to 0.708. Finally, the evolution and influence mechanisms of multi-scale second-phase particles, as well as the corresponding high formability mechanism of the alloys were revealed. The developed coupling control process exhibits great potential and can significantly improve the room temperature formability of high strength Al-Zn-Mg-Cu alloys.