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Jian Gong, and
Available online 14 March 2023, https://doi.org/10.1007/s12613-023-2629-2
[Abstract](29) [PDF 2337KB](3)
Abstract:

The dendrite growth behaviours of high-strength steel during slab continuous casting with travelling-wave magnetic field was studied in this paper. The morphology of solidification structure and composition distribution were analysed in detail. The results showed that the columnar crystals could deflect and break when travelling-wave magnetic field worked with low current intensity. With the increase of current intensity, the secondary dendrite arm spacing and solute permeability decreased, and the columnar crystal transformed to equiaxed crystal. Electromagnetic force caused by travelling-wave magnetic field changed the temperature gradient and velocity magnitude, and promoted the breaking and fusing of dendrites. The order of dendrite compactness and composition uniformity from good to bad was columnar-to-equiaxed transition (high current intensity), columnar crystal zone (low current intensity), columnar-to-equiaxed transition (low current intensity) and equiaxed crystal zone (high current intensity). Additionally, combined with the verified numerical simulation results, as well as the boundary layer theory of solidification front and the dendrite breaking-fusing model, the dendrite deflection mechanism and growth process are revealed. When thermal stress is not considered and there is no obvious narrow segment in dendrite, the velocity magnitude on the solidification front of liquid steel need to reach 0.041 m/s before dendrites can break.

Available online 14 March 2023, https://doi.org/10.1007/s12613-023-2630-9
[Abstract](81) [PDF 2955KB](4)
Abstract:

Satellited CoNiCrAlY-Al2O3 feedstocks with 2, 4, and 6 wt.% of oxide nanoparticles and pure CoNiCrAlY powder were deposited by the HVOF process on Inconel738 superalloy substrate. Oxidation test was done at 1050 ℃ for 5, 50, 100, 150, 200, and 400 h. Microstructure and phase composition of powders and coatings were characterized by scanning electron microscopy and X-ray diffraction, respectively. The bonding strength of the coatings was also evaluated. The results proved that with the increase in the percentage of nanoparticles (from 2 to 6 wt.%), the amount of porosity (from 1 to 4.7 vol.%), unmelted particles, and the roughness of the coating (from 4.8 to 8.8 µm) increased and the bonding strength decreased (from 71 to 48 MPa). The thickness of the TGO layer of pure coating and composite coatings (2, 4, and 6%) after 400 h oxidation was measured as 6.5, 5.5, 7.6, and 8.1 µm, respectively. The CoNiCrAlY-2% Al2O3 coating showed the highest oxidation resistance due to the well-dispersed nanoparticles. The CoNiCrAlY-6% Al2O3 coating had the lowest oxidation resistance caused by its rough surface morphology and porous microstructure.

Zhihong Peng, and
Available online 14 March 2023, https://doi.org/10.1007/s12613-023-2628-3
[Abstract](39) [PDF 1550KB](9)
Abstract:

Goethitic bauxite is a widely used raw materials in the alumina industry. Clarifying the effect of Ti- and Si-containing minerals on goethite transformation in the Bayer digestion process is an essential prerequisite for efficiently utilizing the Fe- and Al-containing minerals in goethitic bauxite. In this work, the interactions between anatase or kaolinite with goethite under various Bayer digestion process were investigated using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscope, scanning electron microscope. The results show that anatase and kaolinite hindered the transformation of goethite. Anatase caused more significant effects by producing a dense sodium titanate layer on the goethite surface after reacting with sodium aluminate solution. While for the case of kaolinite, a loose desilication product adhered to the goethite surface due to the reaction of kaolinite with sodium aluminate solution. Adding the reductants (hydrazine hydrate) could eliminate the retard effect by inducing the transformation of goethite to magnetite, in which titanium is embedded in the magnetite lattice to form Ti-containing magnetite. In contrast, the weakening of the interaction between magnetite and DSP further reduced the influence of kaolinite. As a validation, a reductive Bayer method achieved the transformation of goethite in goethitic bauxite with a 98.87% relative alumina digestion rate. The obtained red mud with a 72.99wt% Fe2O3 content could be further utilized in the steel industry. This work provided a clear understanding of the transformative effects of Ti- and Si-containing minerals to iron minerals transformation and helped with the comprehensive use of iron and aluminum in goethitic bauxite by the reductive Bayer method.

Jianjun He, and
Available online 11 March 2023, https://doi.org/10.1007/s12613-023-2627-4
[Abstract](41) [PDF 1180KB](2)
Abstract:

Sepiolite (ST) was used as a supporting matrix in compiste phase change materials (PCMs) due to its unique microstructure, good thermal stability and other raw material advantages. In this paper, microwave acid treatment were innovatively used in the modification of sepiolite. The modified sepiolite (STm) obtained in different hydrochloric acid concentration (0.25 mol L-1, 0.5 mol L-1, 0.75 mol L-1,and 1.0 mol L-1) treament were added to stearic acid (SA) via vacuum impregnation method. The thermophysical properties of the composites were changed by varying the hydrochloric acid concentration. The SA-STm0.5 obtained by microwave acid treatment at 0.5 mol L-1 hydrochloric acid concentration showed a higher loading capacity (82.63%) than other composites according to the DSC analysis. The melting and freezing enthalpies of SA-STm0.5 were of 152.30 J g-1 and 148.90 J g-1, respectively. The thermal conductivity of SA-STm0.5 was as high as 1.52 times that of pure SA. In addition, the crystal structure, surface morphology and microporous structure of modified sepiolite were studied, and the mechanism of SA-STm0.5 performance enhancement was further revealed by BET analysis. Leakage experiment showed that SA-STm0.5 have good morphological stability. These results demostrate that SA-STm0.5 have potential application in thermal energy storage.

Chaoyue Xu, and
Available online 9 March 2023, https://doi.org/10.1007/s12613-023-2625-6
[Abstract](22) [PDF 852KB](2)
Abstract:

Ting Wang, and
Available online 9 March 2023, https://doi.org/10.1007/s12613-023-2626-5
[Abstract](80) [PDF 1012KB](14)
Abstract:

Metal corrosion brings billions of dollars of economic losses each year. As a smart and new energy harvesting device, triboelectric nanogenerators (TENGs) are able to convert almost all mechanical energies into electricity, leading to great prospects in metal corrosion prevention, cathodic protection, etc. In this work, ﬂexible TENGs were designed utilizing the energy harvested by flexible PDMS films with ZrB2 nanoparticles, dielectric constant was effectively improved by ZrB2, the open-circuit voltage and short-circuit current are 264 V and 22.9 μA, respectively, and the power density of the TENG reaches 6 W/m2. Furthermore, a self-powered anti-corrosion system is designed by the rectifier circuit integrated with the TENGs, and the open circuit potential (OCP) and Tafel curves show that the system has excellent anti-corrosion effect on carbon steel, indicating that the system has broad application prospects in metal cultural relics, ocean engineering, industry and so on.

Zequn Zhang, and
Available online 9 March 2023, https://doi.org/10.1007/s12613-023-2624-7
[Abstract](27) [PDF 1052KB](3)
Abstract:

Seawater splitting is a prospective approach to yield renewable and sustainable hydrogen energy. Currently, complex preparation process and poor repeatability are generally considered to be an insuperable impediment to promote the large-scale production and application of electrocatalysts. Corrosion engineering, avoiding use of the intricate instruments, is an intriguing strategy to reduce the cost and present great potential for electrodes with catalytic performance. In this work, we propose an anode consisting of quinary AlCoCrFeNi layered double hydroxides uniformly decorated on AlCoCrFeNi high entropy alloy via a one-step corrosion engineering method, which directly serves as an extremely active catalyst for boosting oxygen evolution reaction in alkaline seawater. Notably, the best-performing catalyst exhibit the OER activity with overpotential values of 272.3 mV and 332 mV to achieve the current densities of 10 mA cm-2 and 100 mA cm-2, respectively. Deeply, the failure mechanism of obtained catalyst was found for advancing the development of multi-component catalyst.

Junjie Hu, and
Available online 2 March 2023, https://doi.org/10.1007/s12613-023-2621-x
[Abstract](31) [PDF 949KB](10)
Abstract:

The effect of Li2O instead of B2O3 on the viscosity and the melting temperature of the low-reactive mold flux was investigated. The melt structure and precipitation of the crystalline phase were studied using the Raman spectrum and X-ray diffraction to better understand the evolution of viscosity. The viscosity of the mold flux with 2wt% Li2O and 6wt% B2O3 reached the minimum value of 0.07 Pa·s. The break temperature and melting temperature showed a similar trend with the viscosity. With the increase of Li2O content in the mold flux from 0wt% to 6wt%, the degree of polymerization of aluminate and aluminosilicate network structure increased due to the increasing Li+ released by Li2O. The addition of Li2O preferred to associate with Al3+ as a charge compensator. The precipitation of the LiAlO2 crystalline phase led to an increase in mold flux viscosity. Therefore, the content of Li2O should be controlled below 2wt% to avoid the precipitation of LiAlO2, which was harmful to the continuous casting of high-aluminum steels.

Lei Zhang, and
Available online 2 March 2023, https://doi.org/10.1007/s12613-023-2622-9
[Abstract](43) [PDF 915KB](10)
Abstract:

Mold flux serves a crucial metallurgical function of absorbing inclusions, which has a direct impact on the smooth of casting process and the casted slab quality. In this study, the dissolution behavior and mechanism of TiO2 and TiN inclusions in molten CaO-SiO2-B2O3 based fluorine-free mold flux were explored by in-situ Single Hot Thermocouple Technology combined with X-ray Photoelectron Spectroscopy. The results showed that the rutile TiO2 inclusion was effectively dissolved by the molten slag within 76 s, which the original [TiO6] octahedral structure was destroyed and converted to the network former [TiO4] tetrahedral. However, the dissolution rate of TiN inclusion was significantly lower than that of the TiO2 inclusion. This was primarily due to that, during the dissolution process of TiN inclusion, the TiN particle needed to be first oxidized and then dissolved in the molten slag into [TiO4] tetrahedral and [TiO6] octahedral structures, accompanied by the generation of a large amount of N2 gas. Besides, CaTiO3 crystals tended to nucleate and grow on the surface of the bubbles with sufficient [TiO6] octahedral and Ca2+ ions, resulting in the molten slag to be in a solid-liquid mixed state eventually.

Fei Ke, and
Available online 22 February 2023, https://doi.org/10.1007/s12613-023-2617-6
[Abstract](77) [PDF 2623KB](15)
Abstract:

The mechanical properties of cemented paste backfill (CPB) determine its control effect on the goaf roof. In this study, the mechanical strength of polymer-modified cemented paste backfill (PCPB) samples was tested by uniaxial compression tests, and the failure characteristics of PCPB under the compression were analyzed. At the same time, acoustic emission (AE) technology was used to monitor and record the cracking process of the PCPB sample with a curing age of 28 d in real time, and two AE indexes methods (RA and AF values) were used to classify the failure modes of samples under different loading processes. The results show that waterborne epoxy resin can significantly enhance the mechanical strength of PCPB samples (when the PU-C ratio is 0.25, the strength of PCPB samples with a curing age of 28 d is increased by 102.6%); with the increase of polymer content, the mechanical strength of PCPB samples is improved significantly, and the increase of mechanical strength is the most obvious in the early and middle period of curing. Under uniaxial load, the macro cracks of PCPB samples are mostly generated along the axial direction, the main crack runs through the sample, and a large number of small cracks are distributed around the main crack. The AE response of PCPB samples during the whole loading process can be divided into four periods: quiet period, slow growth period, rapid growth period and remission period, which are synchronized with the micro-pore compaction stage, elastic deformation stage, plastic deformation stage and failure instability stage of the sample’s stress-strain curve. The AE events are mainly concentrated in the plastic deformation stage; both shear failure and tensile failure occur in the above four stages, while tensile failure is dominant for PCPB samples. The results of this study can improve the safety of coal pillar recovery in pillar goaf.

Fang Ye, and
Available online 22 February 2023, https://doi.org/10.1007/s12613-023-2619-4
[Abstract](29) [PDF 1365KB](5)
Abstract:

In this work, a polymer-derived ZrC ceramic with excellent electromagnetic interference (EMI) shielding performance was developed to meet the requirement in ultra-high temperature. Thermal decomposition process of ZrC ceramic organic precursor was studied, and the evolution of phase composition, microstructure, and EMI shielding performance was revealed. The carbothermal reduction reaction begins to occur at 1300℃, and the transformation from ZrO2 to ZrC was completely at 1700℃. With the increase of annealing temperature, the tetragonal zirconia (t-ZrO2) gradually transforms into monoclinic zirconia (m-ZrO2), and the transformation is complete at annealing temperature of 1500℃ due to the consumption of large amount of carbon phase. The average total shielding effectiveness was 11.63, 22.67, 22.91, 22.81 and 34.73 dB when the polymer-derived ZrC (PDC-ZrC) was annealed at 900, 1100, 1300, 1500 and 1700℃, respectively. In the thermal decomposition process, the graphitization degree and phase distribution of free carbon plays the dominant role to affect the shielding performance. The typical core-shell structure, composed of carbon and ZrC, can be formed at the annealing temperature of 1700℃, resulting in the excellent shielding performance.

Aziz Habibi-Yangjeh, and
Available online 22 February 2023, https://doi.org/10.1007/s12613-023-2618-5
[Abstract](75) [PDF 1467KB](7)
Abstract:

Novel g-C3N4 nanosheet/Bi5O7Br/NH2-MIL-88B(Fe) photocatalysts (denoted as GCN-NSh/Bi5O7Br/Fe-MOF) with a double S-scheme heterojunctions were synthesized by a facile solvothermal route. The resultant materials were examined by XPS, XRD, SEM, TEM, HRTEM, PL, EDX, FT-IR, UV-vis DRS, photocurrent density, EIS, and BET analyses. After integration of Fe-MOF with GCN-NSh/Bi5O7Br, the removal constant of tetracycline over the optimal GCN-NSh/Bi5O7Br/Fe-MOF (15%) nanocomposite was promoted 33-times in comparison with the pristine GCN. Furthermore, compared to the pure GCN, the GCN-NSh/Bi5O7Br/Fe-MOF (15%) nanocomposite showed supreme photoactivity to azithromycin, metronidazole, and cephalexin removal, which were 36.4, 20.2, and 14.6 times as high as the GCN, respectively. The radical quenching tests showed that ⦁O⁻2 and h⁺ mainly contributed in the elimination reaction. In addition, the nanocomposite had excellent activity after four successive cycles. According to the developed n-n heterojunctions amongst n-GCN-NSh, n-Bi5O7Br, and n-Fe-MOF semiconductors, a double S-scheme charge transfer mechanism was proposed for destruction of the selected antibiotics.

Cheng Zhong, and
Available online 18 February 2023, https://doi.org/10.1007/s12613-023-2614-9
[Abstract](38) [PDF 1229KB](6)
Abstract:

Tetragonal barium titanate was synthesized from barium hydroxide octahydrate and titanium tetrachloride through a simple one-step hydrothermal method. The effect of different solvents on the crystal structure and morphology of barium titanate nanoparticles in the hydrothermal process was investigated. Except for ethylene glycol/water solvent, impurity-free barium titanate is synthesized in pure water, methanol/water, ethanol/water and isopropyl alcohol/water mixed solvents. Compared with other alcohols, ethanol is favorable to the formation of tetragonal structure. In addition, characterization studies confirm that particles synthesized in methanol/water, ethanol/water, isopropyl alcohol/water mixed solvents are smaller in size than those in pure water. In the case of alcohol-containing solvents, the particle size decreases in the order of isopropanol, ethanol and methanol. Among all the media employed, ethanol/water is the optimum reaction media for barium titanate in terms of high tetragonality (c/a=1.0088) and small average particle size (82 nm), which has great potential for practical application in multilayer ceramic capacitors.

Minfang Han, and
Available online 18 February 2023, https://doi.org/10.1007/s12613-023-2616-7
[Abstract](66) [PDF 1933KB](19)
Abstract:

Performance degradation of the solid oxide fuel cell (SOFC) shortens the cell life in practical applications. Revealing the degradation mechanism is crucial for continuous improvement in cell durability. In this work, the effects of cell operating conditions on the terminal voltage and anode microstructure of the Ni-YSZ (yttria-stabilized zirconia) anode-supported single cell are investigated. The microstructure of the anode active area near the electrolyte is characterized by laser optical microscope and focused ion beam-scanning electron microscopy. Ni depletion at the anode/electrolyte interface region is observed after the 100 h discharge tests. In addition, the long-term stability of the single cell is evaluated at 700°C for 3000 h. After the initial decline, the anode-supported single cell exhibits a good durability with a voltage decay rate of 0.72%/kh and an electrode polarization resistance decay rate of 0.17%/kh. The main performance loss of the cells comes from the initial degradation.

Huajun Wang, and
Available online 18 February 2023, https://doi.org/10.1007/s12613-023-2615-8
[Abstract](49) [PDF 846KB](10)
Abstract:

In the past few decades, microbubble flotation has been widely studied in the separation and beneficiation of fine minerals. Compared with conventional flotation, microbubble flotation has obvious advantages such as high grade and recovery, and low consumption of flotation reagents. Hereby, we systematically review the latest advances and research progress in the flotation of fine mineral particles by microbubbles. In general, microbubbles are characteristic of small bubble size, large specific surface area, high surface energy, good selectivity, and are easy to attach to the surface of hydrophobic particles or large bubbles, greatly reducing the detaching probability of particles from bubbles. Microbubbles can be prepared by pressurized aeration and dissolved air (PADA), electrolysis, ultrasonic cavitation, photocatalysis, solvent exchange, temperature difference method (TDM), venturi tube and membrane method, etc. Correspondingly, equipment for fine particle flotation is categorized as microbubble release flotation machine, centrifugal flotation column, packed flotation column, and magnetic flotation machine, etc. In practice, microbubble flotation has been widely studied in the beneficiation of ultrafine coals, metallic minerals, non-metallic minerals, and exhibited superiority than the conventional flotation machine. Mechanisms underpinning the promotion of fine particle flotation by nanobubbles include the agglomeration of fine particles, the high stability of nanobubbles in aqueous solution, the enhancement of particle hydrophobicity and flotation dynamics.

Bo Feng, and
Available online 17 February 2023, https://doi.org/10.1007/s12613-023-2613-x
[Abstract](31) [PDF 1000KB](4)
Abstract:

Due to the depletion of wolframite resources, the development focus of tungsten resources has gradually shifted to scheelite, making the recycling of scheelite resources a hot research topic. Researchers are particularly concerned about the separation of scheelite from calcium-bearing minerals. Because calcium-bearing gangue minerals associated with scheelite (such as apatite, fluorite, and calcite) have similar surface physicochemical properties to scheelite in pulp, it is impossible to separate scheelite from them using oleate collectors selectively. Researchers have made significant progress in recent years by using depressants as a breakthrough in their research. The development status, mechanism, reagent combination, and application of depressants in calcium-containing minerals were reviewed in this research. Their benefits and drawbacks were objectively assessed to offer a theoretical foundation for the future development of scheelite flotation depressants.

Xiaodong Wen, and
Available online 16 February 2023, https://doi.org/10.1007/s12613-023-2612-y
[Abstract](60) [PDF 1124KB](14)
Abstract:

The activation of CO on iron-based materials is a key elementary reaction for many chemical processes. In this work, we investigate CO adsorption and dissociation on a series of Fe, Fe3C, Fe5C2, and Fe2C catalysts through density functional theory calculations. We detect dramatically different performances for CO adsorption and activation on diverse surfaces and sites. The activation of CO is dependent not only on the local coordination of the molecule to the surface but also the bulk phase of the underlying catalyst. The different local bonding environment affects the bulk properties leading to varying interactions between the adsorbed CO and the surface, thus yielding different activation levels of the C-O bond. We also examine the prediction of CO adsorption upon different types of Fe-based catalysts by performing machine learning through linear regression models. We combine the features originating from both surfaces and bulk phases to enhance the prediction of the activation energies. Eight different linear regressions utilizing feature engineering of polynomial representations were performed. Among them, a ridge linear regression with 2nd-degree polynomial feature generation predicted the best CO activation energy with a mean absolute error of 0.269 eV.

Zhanwu Ning, and
Available online 15 February 2023, https://doi.org/10.1007/s12613-023-2611-z
[Abstract](55) [PDF 1568KB](4)
Abstract:

The synthesis of oxygen vacancies (OVs) modified TiO2 under mild conditions is attractive. In this work, OVs were easily introduced in TiO2 lattice during the hydrothermal doping process of trivalent iron ions. Theoretical calculations based on a novel charge-compensation structure model were employed with experimental methods to reveal the intrinsic photocatalytic mechanisms of Fe doped TiO2 (Fe-TiO2). The OVs’ formation energy in Fe-TiO2 (1.12 eV) was only 23.6% of that in TiO2 (4.74 eV), explaining why Fe3+ doping could introduce OVs concentration in TiO2 lattice. The calculation results also indicated that impurity states introduced by Fe3+ and OVs enhanced the light absorption activity of TiO2. Additionally, the charge carriers’ transport was investigated by carriers’ lifetime and relative mass. The carriers’ lifetime of Fe-TiO2 (4.00 ns, 4.10 ns and 3.34 ns for 1%, 2% and 3% doping concentration, respectively) was longer than that of undoped TiO2 (3.22 ns), indicating Fe3+ and OVs could promote the separation of charge carriers, which can be attributed to the bigger relative effective mass of electrons and holes. Herein, the Fe-TiO2 has higher photocatalytic indoor NO removal activity compared with other photocatalysts because it has strong light absorption activity and high carriers’ separation efficiency.

Zepeng Yan, and
Available online 15 February 2023, https://doi.org/10.1007/s12613-023-2610-0
[Abstract](67) [PDF 779KB](11)
Abstract:

Wall slip is a microscopic phenomenon of cemented paste backfill (CPB) slurry near the pipe wall, which has an important influence on the form of slurry pipe transport flow and velocity distribution. Directly probe the wall slip characteristics by conventional experimental methods is difficult. This paper built a non-contact experimental platform for monitoring the microscopic slip layer of CPB pipeline transport independently based on particle image velocimetry (PIV), analyzed the effects of slurry temperature, pipe diameter, solid concentration and slurry flow on the wall slip velocity of CPB slurry, which refined the theory of the effect of wall slip characteristics on pipeline transport. The results showed that CPB slurry had an extensive slip layer at the pipe wall, with significant wall slip. High slurry temperature improved the degree of particle Brownian motion within the slurry and enhances the wall-slip effect. Increasing pipe diameter was not conducive to the formation of the slurry slip layer and led to a transition in the CPB slurry flow pattern. The increase in solid concentration increased the interlayer shear effect of CPB slurry flow and the slip velocity. The slip velocity value increased from 0.025 m·s-1 to 0.056 m·s-1 when the solids content improved from 55wt% to 65wt%. when slurry flow increased, CPB slurry flocculation structure changed, which affected the slip velocity, and the best effect of slip layer resistance reduction was achieved when the transported flow rate was 1.01 m3·h-1. The results had important theoretical significance for improving the stability and economy of CPB slurry in pipeline.

Xinming Chen, and
Available online 12 February 2023, https://doi.org/10.1007/s12613-023-2609-6
[Abstract](87) [PDF 995KB](19)
Abstract:

The development of industry is inseparable from the support of mining, but mining processes consume huge energy, and huge tailings emissions can make a significant impact on the environment. In the past decades, mining industry has also developed many technologies that are related to mineral energy management, of which cemented paste backfill (CPB) is one of the representative technologies. CPB has been successfully applied to mine ground control and tailings management. In the CPB technology, the mixing process is key to achieving materials with a good final quality and controlled properties. However, in the preparation process, mixed homogeneity of the CPB is hard to achieve due to fine tailings, high solid volume fraction, and high viscosity. Most of the research focused on the effect of mixing ingredients on CPB properties rather than on the preparation process of the CPB. Therefor, it is vital to improve the performance and reduce the production cost of CPB by optimizing the mixing process. This review summarizes the current studies on the mixing technology of the CPB and its application status in China. Then it compares the advantages and disadvantages of various mixing equipment and discusses the latest research findings and research hotspots in paste preparation. Finally, the challenges and development trends of mixing technology are concluded based on the relevant application cases in China for the purpose of promoting cement-based material mixing technology development.

Jilin He, and
Available online 10 February 2023, https://doi.org/10.1007/s12613-023-2608-7
[Abstract](46) [PDF 1002KB](3)
Abstract:

The macroscopic characteristics of the molten salt are governed by its microstructure. Research on the structure of molten salt provides the foundation for a full understanding of the physicochemical properties of molten salt as well as a deeper analysis of the microscopic electrolysis process in molten salt. Individuals can obtain information about the microstructure of matter with the help of several speculative and experimental procedures. The advantages and disadvantages of the various test procedures used to determine the microstructure of molten salt are compared in this paper. In the molten salt system, the typical coordination configurations of metal ions are also summarized. Furthermore, the impact of temperature, anion, cation, and metal oxide (O2-) on the structure of molten salt is discussed in detail. It was suggested that the accuracy and completeness of molten salts' structure information need to be investigated by the integration of multiple methods and interdisciplinary. The microstructure and coordination of molten salt deepens the understanding of the elementary elements of the microstructure of matter. This paper, based on the review of coordination states of metal ions in molten salts, is hoped that it can inspire researchers to explore the interrelationship between microstructure and macroscopic properties of materials.

Xun Xi, and
Available online 10 February 2023, https://doi.org/10.1007/s12613-023-2607-8
[Abstract](62) [PDF 882KB](7)
Abstract:

Understanding the in situ stress state is crucial in many engineering problems and Earth science research. The object of the present article is to present new insights into the interaction mechanism between stress state and faults. In situ stresses can be influenced by various factors, one of the most important being the existence of faults. A fault could significantly affect the value and direction of the stress components. Reorientation and magnitude changes of stresses exist adjacent to faults and stress jumps/discontinuities across the fault. In contrast, the change of stress state may lead to the transformation of faulting type and potential fault reactivation. Qualitative fault reactivation assessment using characteristic parameters under the current stress environment provides a method to assess the slip tendency of faults. The correlation between in situ stresses and fault properties enhances the ability to predict fault slip tendency via stress measurements, which can be used to further refine the assessment of fault reactivation risk. In the future, stress measurements at greater depths and long-term continuous real-time stress monitoring near/on key parts of faults are essential. In addition, much attention needs to be paid to distinguishing the genetic mechanisms of abnormal stress states and the type and scale of stress variations, as well as exploring the mechanisms of pre-faulting anomaly and fault reactivation.

Yang Miao, and
Available online 2 February 2023, https://doi.org/10.1007/s12613-023-2605-x
[Abstract](112) [PDF 1901KB](14)
Abstract:

As a heat-resistant wave-absorbing material, silicon carbide (SiC) aerogel has become a research hotspot at present. However, the most common silicon sources are organosilanes, which are costly and toxic. In this work, SiC aerogels were successfully prepared by using water glass as the silicon source. Specifically, the microstructure and chemical composition of SiC aerogels were controlled by adjusting the Si to C molar ratio during the sol-gel process, and the effect on SiC aerogel microwave absorption properties was investigated. The SiC aerogels prepared with the Si:C molar ratio of 1:1 have an effective electromagnetic wave absorption capacity, with a minimum reflection loss value of -46.30 dB at 12.88 GHz, and an effective frequency bandwidth of 4.02 GHz. They also have good physical properties, such as the density of 0.0444 g/cm3, the thermal conductivity of 0.0621 W/(m∙K), and the specific surface area of 1099 m2/g. These lightweight composites with microwave-absorbing properties and low thermal conductivity can be used as thermal protection materials for space shuttles and reusable carriers.

Feng Teng, and
Available online 20 January 2023, https://doi.org/10.1007/s12613-023-2604-y
[Abstract](108) [PDF 1013KB](14)
Abstract:

It is significant for the commercial viability of perovskite solar cells to develop tin-based devices with low toxicity. However, tin halide is a stronger Lewis acid, so that its crystallization rate is very fast, which leads to the formation of many defects that influence the device performance of tin-based perovskite solar cells. In this work, Propylamine hydrobromide (PABr) is introduced into the perovskite precursor solution as an additive to passivate defects, fabricating more uniform and dense perovskite films. Because they are too large to enter the perovskite lattices, propylamine cations just exist in the grain boundary to passivate surface defects and to promotes crystal growth in a favored orientation. The average short circuit current density is enhanced from 19.45 to 25.47 mA per square centimeter due to PABr additive because carrier recombination induced by defects is substantially decreased. In addition, the long-term illumination stability of the device is enhanced after optimization, and the hysteresis effect is negligible. Attributing to the addition of PABr, a power conversion efficiency of 9.35 percent is achieved.

Jian Chen, and
Available online 18 January 2023, https://doi.org/10.1007/s12613-023-2602-0
[Abstract](138) [PDF 2732KB](21)
Abstract:

The corrosion behavior of 304L stainless steel (SS) in 3.5 wt.% NaCl solution after different cavitation erosion (CE) times was evaluated by electrochemical noise and potentiostatic polarization techniques. It was found that the antagonism effect between passivation and depassivation of 304L SS presented significant distinctions in different CE periods. The passivation behavior was predominant in the incubation period of CE, and the surface of 304L SS was mainly characterized by pitting initiation. During the rising period of CE, the steel experienced a process from passivation to depassivation, and a large number of metastable pitting developed into steady-state pitting. The depassivation performance is dominant in the stable period of CE, and serious local corrosion occurred on the surface of the sample.

Qing Chang, and
Available online 11 January 2023, https://doi.org/10.1007/s12613-023-2599-4
[Abstract](62) [PDF 1436KB](13)
Abstract:

CoFe2O4 has been widely used for electromagnetic wave absorption by virtue of high Snoek limit, strong anisotropy and suitable saturation magnetization, yet the inherent shortcomings such as low dielectric loss, high density and magnetic agglomeration limit the pursuit for ideal absorbents. In this study, a microstructure regulation strategy is recommended to resolve the inherent disadvantages of pristine CoFe2O4 via a sol-gel auto-combustion method. A series of CoFe2O4 foams (S0.5, S1.0 and S1.5) constructed by 2D curved surfaces were obtained by changing the ratio of citric acid to Fe3+, in which the electromagnetic parameters were adjusted by morphology regulation. Thanks to the proper impedance matching and conductance loss provided by moderate complex permittivity, the effective absorption bandwidth (EAB) of S0.5 is as high as 7.3 GHz, exceeding most of CoFe2O4-based absorbents. Moreover, the EAB of S1.5 reaches 5.0 GHz (8.9-13.9 GHz) covering most of X band, which is ascribed to intense polarization proffered by lattice defects and heterogeneous interface. The 3D foam structure overcomes the high density and magnetic agglomeration issues of CoFe2O4 nanoparticles, and meanwhile, the good conductivity of 2D curved surfaces can effectively elevate the complex permittivity so as to ameliorate the dielectric loss of pure CoFe2O4. This study provides a fresh idea for the theoretical design and practical production of lightweight and broadband pure ferrite.

Changfeng Chen, and
Available online 30 December 2022, https://doi.org/10.1007/s12613-022-2593-2
[Abstract](46) [PDF 861KB](9)
Abstract:

Fe–S compounds with hexagonal crystal structure are potential hydrogen permeation barrier during H2S corrosion. Hexagonal system Fe–S films were prepared on carbon steel through corrosion and CVD deposition, and the barrier effect of different Fe-S films on hydrogen permeation was tested using electrochemical hydrogen permeation method. After that, the electrical properties of Fe–S compound during phase transformation were measured using thermoelectric measurement system. Results show that the mackinawite has no obvious barrier effect on hydrogen penetration, as a p-type semiconductor, and pyrrhotite (including troilite) has obvious barrier effect on hydrogen penetration, as an n-type semiconductor. Hydrogen permeation tests showed peak permeation performance when the surface was deposited with a continuous film of pyrrhotite (Fe(1-x)S) and troilite. The FeS compounds suppressed hydrogen permeation by the promotion of the hydrogen evolution reaction, semiconducting inversion from p- to n-type, and the migration of ions at the interface.

Saritha G Bhat, and
Available online 30 December 2022, https://doi.org/10.1007/s12613-022-2594-1
[Abstract](75) [PDF 1443KB](11)
Abstract:

Manganese substituted magnetite ferrofluids MnxFe1-xFe2O4 (x=0 to 0.8) are prepared in this work by chemical co-precipitation reaction. The controlled growth of ferrofluids nanomaterials for antibacterial activities is challenging and therefore very few reports are available on the topic. This research focus on stabilizing the aqueous ferrofluids with tetramethylammonium hydroxide (TMAH) surfactant for high homogeneity. Morphological characterization reveals nanoparticles of 5-11 nm formed by the chemical reaction and the nanocrystalline nature as evident from the structural investigation. Mn-substituted magnetic ferrofluids are analyzed for their structural, functional and antibacterial performance according to the concentration of Mn-substituent concentration. Optical studies showed higher blue shift for Mn2+ substituted MnxFe1−xFe2O4 with theoretical correlation of optical band gaps with Mn-concentration. Super paramagnetic nature of substituted ferrofluids causes zero coercivity and remanance, and this influence the particle size, cation distribution and spin canting. The structural and functional performance of the ferrofluids are correlated with the antibacterial activity finally demonstrating the highest inhibition zone formation for MnxFe1-xFe2O4 ferrofluids.

Juanhong Liu, and
Available online 16 December 2022, https://doi.org/10.1007/s12613-022-2587-0
[Abstract](48) [PDF 1491KB](10)
Abstract:

Water-locking flocs formed by ultrafine tailings particles are detrimental to the thickener underflow concentration in the process of gravity thickening operation for paste preparation. The relationship between mesostructure and seepage characteristics of tail mortar is typically ignored in the investigation of deep dehydration stage. Shearing seepage test of unclassified tailings sedimentation bed is carried out with copper tailings, morphology and geometric distribution of micropores are analyzed via computed X-ray tomography technology, and shearing evolution of micropore structure and seepage channel are investigated to evaluate the dewatering performance of underflow slurry using a three-dimensional reconstruction approach. Results showed that porosity decreases significantly with the occurrence of shearing action. Connected pore ratio and the average radius of throat channel obtain a peak value of 0.79 and 31.38 μm, respectively, when the shearing act is adopted for 10 min. However, reverse seepage velocity and absolute permeability in bed decrease in various ranges after the shearing action. Meanwhile, the maximum flow rate reached 1.537 μm/s and absolute permeability increased by 14.16%. Shearing action changes the formation process and pore structure of the seepage channel. Isolated pores relate to the surrounding flocs to form branch channels, which then become the main seepage channel and create the dominant water seepage flow channel.

Bo Zhang, and
Available online 26 October 2022, https://doi.org/10.1007/s12613-022-2563-8
[Abstract](66) [PDF 2147KB](9)
Abstract:

The development of solid waste resources as constituent materials for wet shotcrete has significant economic and environmental advantages. In this study, the concept of using tailings as aggregate and fly ash and slag powder as auxiliary cementitious material is proposed and experiments are carried out by response surface methodology (RSM). Multivariate nonlinear response models are constructed to investigate the effect of factors on the uniaxial compressive strength (UCS) of tailings wet shotcrete (TWSC). The UCS of TWSC is predicted and optimized by constructing gaussian process regression (GPR) and genetic algorithm (GA).  The UCS of TWSC is gradually enhanced with the increase of slag powder dosage and fineness modulus, and it is enhanced first and then decreased with the increase of fly ash dosage. The microstructure of TWSC has the highest gray value and the highest UCS when the fly ash dosage at about 120 kg/m3. The GRP-GA model constructed in this study achieves high accuracy prediction and optimization of the UCS of TWSC under multi-factor conditions.

Huatao Huang, and
Available online 25 October 2022, https://doi.org/10.1007/s12613-022-2560-y
[Abstract](126) [PDF 1130KB](13)
Abstract:

Detecting the pipeline abnormal status, typically blockage and leakage accident, is significant for the continuity and safety of mine backfill. The pipeline system for gravity-transport high-density backfill (GHB) is of complexity. There is rarely a specifically designed, efficient, and accurate pipeline abnormal detection method for GHB. This work presents a Long Short-Term Memory based deep learning (LSTM-DL) model for GHB pipeline blockage and leakage diagnosis. First, an industrial pipeline monitoring system was introduced using pressure and flow sensors. Second, blockage and leakage field experiments were designed to solve the problem of negative sample deficiency. The pipeline statistical characteristics with different working statuses were analyzed to show its complexity. Third, the architecture of the LSTM-DL model was elaborated and evaluated. Finally, the LSTM-DL model was compared with some state-of-the-art (SOTA) learning algorithms. Results show that the backfilling cycle consists of multiple working phases and is intermittent. Although pressure and flow signals fluctuate stably in a normal cycle, their values are diverse in different cycles. Plugging causes a sudden change in interval signal features; leakage results in long variation duration and wide fluctuation range. Among the SOTA models, the LSTM-DL model has the highest detection accuracy of 98.31% for all states and the lowest misjudgment or false positive rate (FPR) of 3.21% for blockage and leakage states. The proposed model can accurately recognize various pipeline statuses for complex GHB systems.

Le Zhou, and
Available online 24 August 2022, https://doi.org/10.1007/s12613-022-2540-2
[Abstract](264) [PDF 1392KB](24)
Abstract:

Cemented paste backfill (CPB) is considered as one of the effective methods for resource utilization of tailings, while the high cost of ordinary Portland cement (OPC) limits its utilization. Considering the poor performance of Na2CO3-activated binders, in this work, supplementary materials including CaO, MgO, and calcined layered double hydroxide (CLDH) were used to modify their properties with the aim of finding an alternative binder to OPC. Isothermal calorimetric, X-Ray Diffraction (XRD) and thermogravimetry (TG) analysis were conducted to explore the reaction kinetics and phase assembles of the binder. Properties of CPB samples such as flowability, strength development and heavy metals immobilization effects were then investigated. The results showed that coupling utilization of MgO and CLDH showed better performance. The strength of sample Mg2-CLDH3 was about 2.94 MPa after curing for 56 days, which was higher than OPC-based sample. Besides, the cost of modified Na2CO3-activated binder was lower than OPC-based binder. Additionally, supplementary materials modified sample showed satisfactory heavy metals immobilization effects.

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Anne-Laure Helbert, and
Available online 3 March 2023, https://doi.org/10.1007/s12613-023-2623-8
Abstract:
Haiqing Wang, and
Available online 25 February 2023, https://doi.org/10.1007/s12613-023-2620-y
Abstract:
Physical vapor deposition (PVD) can be used to produce high-quality Gd2O3-doped CeO2 (GDC) films. Among various PVD methods, reactive sputtering provides unique benefits, such as high deposition rates and easy upscaling for industrial applications. GDC thin films were successfully fabricated through reactive sputtering using a Gd0.2Ce0.8 (at%) metallic target, and their application in solid oxide fuel cells, such as buffer layers between yttria-stabilized zirconia (YSZ)/La0.6Sr0.4Co0.2Fe0.8O3−δ and as sublayers in the steel/coating system, was evaluated. First, the direct current (DC) reactive-sputtering behavior of the GdCe metallic target was determined. Then, the GDC films were deposited on NiO–YSZ/YSZ half-cells to investigate the influence of oxygen flow rate on the quality of annealed GDC films. The results demonstrated that reactive sputtering can be used to prepare thin and dense GDC buffer layers without high-temperature sintering. Furthermore, the cells with a sputtered GDC buffer layer showed better electrochemical performance than those with a screen-printed GDC buffer layer. In addition, the insertion of a GDC sublayer between the SUS441 interconnects and the Mn–Co spinel coatings contributed to the reduction of the oxidation rate for SUS441 at operating temperatures, according to the area-specific resistance tests.
Shengbing Meng, and
Available online 10 February 2023, https://doi.org/10.1007/s12613-023-2606-9
Abstract:
In general, malachite is recovered via sulfidization–xanthate flotation, although many unsatisfactory flotation indexes are frequently obtained as a result of the presence of associated calcite. This phenomenon occurs because the dissolved components of malachite and calcite affect the flotation behavior of both minerals. In this study, the effect of the dissolved components derived from malachite and calcite on the flotation behavior and surface characteristics of both minerals was investigated. Flotation tests indicated that malachite recovery decreased when the calcite supernatant was introduced, while the presence of the malachite supernatant increased the recovery of calcite. Dissolution and adsorption tests, along with zeta potential measurements, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometry, and time-of-flight secondary ion mass spectrometry demonstrated that the Ca species in the calcite supernatant were adsorbed on the malachite surface, which hindered the interaction of Na2S with malachite, thereby resulting in the insufficient adsorption of sodium isoamyl xanthate (NaIX) on the surface of malachite. By contrast, the Cu species in the malachite supernatant were adsorbed on the calcite surface, and they provided active sites for the subsequent adsorption of Na2S and NaIX.
Kaihong Zheng, and
Available online 20 January 2023, https://doi.org/10.1007/s12613-023-2603-z
Abstract:
Mg–3Al–1Zn (AZ31) sheets were produced by transverse gradient extrusion (TGE) process. The flow behavior and dynamic recrystallization during extrusion were systematically analyzed. The microstructures, textures, and mechanical behavior of extruded AZ31 sheet were also analyzed and compared with conventional extruded (CE) sheet. The results showed that fine grain structure and multi-type unique textures were formed in TGE sheet because of the generation of extra flow velocity along transverse direction (TD) and flow velocity gradient along extrusion direction (ED) during extrusion. The basal poles gradually deviated away normal direction (ND) from edge to center of the TGE sheet along TD, and the largest inclination angle at center region reached around 65°. Furthermore, the basal poles inclined from ED to TD 40°–63°, except for the center region of TGE sheet. The TGE sheet presented higher ductility and strain hardening exponent (n-value), but lower yield strength and Lankford value (r-value) in comparison with the CE sheet. Both the basal <a> slip and tensile twins were easy to be activated during deformation, and the largest elongation of 41% and the lowest yield strength of 86.5 MPa were obtained for the ED-center sample in the TGE sheet.
Xue Li, and
Available online 18 January 2023, https://doi.org/10.1007/s12613-023-2601-1
Abstract:
The technology of cemented paste backfill (CPB) is an effective method for green mining. In CPB, mixing is a vital process aiming to prepare a paste that meets the non-stratification, non-segregation, and non-bleeding requirements. As a multiscale granular system, homogenization is one of the challenges in the paste-mixing process. Due to the high shearing, high concentration, and multiscale characteristics, paste exhibits complex rheological properties in the mixing process. An overview of the mesomechanics and structural evolution is presented in this review. The effects of various influencing factors on the paste’s rheological properties were investigated, and the rheological models of the paste were outlined from the macroscopic and mesoscopic levels. The results show that the mechanical effects and structural evolution are the fundamental factors affecting the rheological properties of the paste. Existing problems and future development trends are presented to change the practice where the CPB process comes first and the theory lags.
Weizhuo Yu, and
Available online 11 January 2023, https://doi.org/10.1007/s12613-023-2600-2
Abstract:
Si-based optical position-sensitive detectors (PSDs) have stimulated the interest of researchers due to their wide range of practical applications. However, due to the rigidity and fragility of Si crystals, the applications of flexible PSDs have been limited. Therefore, we presented a flexible broadband PSD based on a WS2/Si heterostructure for the first time. A scalable sputtering method was used to deposit WS2 thin films onto the etched ultrathin crystalline Si surface. The fabricated flexible PSD device has a broad spectral response in the wavelength range of 450–1350 nm, with a high position sensitivity of ~539.8 mV·mm−1 and a fast response of 2.3 μs, thanks to the strong light absorption, the built-in electrical field at the WS2/Si interface, and facilitated transport. Furthermore, mechanical-bending tests revealed that after 200 mechanical-bending cycles, the WS2/Si PSDs have excellent mechanical flexibility, stability, and durability, demonstrating the great potential in wearable PSDs with competitive performance.
Xuelin Wang, and
Available online 10 January 2023, https://doi.org/10.1007/s12613-023-2597-6
Abstract:
This study investigated the influence of band microstructure induced by centerline segregation on carbide precipitation behavior and toughness in an 80 mm-thick 1 GPa low-carbon low-alloy steel plate. The quarter-thickness (1/4t) and half-thickness (1/2t) regions of the plate exhibited similar ductility and toughness after quenching. After tempering, the 1/4t region exhibited ~50% and ~25% enhancements in both the total elongation and low-temperature toughness at −40°C, respectively, without a decrease in yield strength, whereas the toughness of the 1/2t region decreased by ~46%. After quenching, both the 1/4t and 1/2t regions exhibited lower bainite and lath martensite concentrations, but only the 1/2t region exhibited microstructure bands. Moreover, the tempered 1/4t region featured uniformly dispersed short rod-like M23C6 carbides, and spherical MC precipitates with diameters of ~20–100 nm and <20 nm, respectively. The uniformly dispersed nanosized M23C6 carbides and MC precipitates contributed to the balance of high strength and high toughness. The band microstructure of the tempered 1/2t region featured a high density of large needle-like M3C carbides. The length and width of the large M3C carbides were ~200–500 nm and ~20–50 nm, respectively. Fractography analysis revealed that the high density of large carbides led to delamination cleavage fracture, which significantly deteriorated toughness.
Naixing Yang, and
Available online 10 January 2023, https://doi.org/10.1007/s12613-023-2598-5
Abstract:
Natural minerals-based energy materials have attracted enormous attention because of the advantages of good materials consistency, high production, environmental friendliness, and low cost. The uniform distribution of grains can effectively inhibit the aggregation of active materials, improving lithium storage performance. In this work, natural graphite is modified by polyvinylpyrrolidone to obtain modified graphite with reduced size and better dispersion. Natural pyrite composite polyvinylpyrrolidone-modified graphite (pyrite/PG) material with uniform particle distribution is obtained by the ball milling process. The subsequent calcination process converts pyrite/PG into Fe1−xS compounded with polyvinylpyrrolidone-modified graphite (Fe1−xS/PG). The homogeneous grain distributions of active material can facilitate the faster transfer of electrons and promote the efficient utilization of active materials. The as-prepared Fe1−xS/PG electrode exhibits a remarkably reversible specific capacity of 613.0 mAh·g−1 at 0.2 A·g−1 after 80 cycles and an excellent rate capability of 523.0 mAh·g−1 at 5 A·g−1. Even at a higher current density of 10 A·g−1, it can deliver a specific capacity of 348.0 mAh·g−1. Moreover, the dominant pseudocapacitance in redox reactions accounts for the impressive rate and cycling stability. This work provides a low-cost and facile method to fabricate natural mineral-based anode materials and apprise readers about the impact of uniform particle distribution on lithium storage performance.
Ning Peng, and
Available online 6 January 2023, https://doi.org/10.1007/s12613-023-2596-7
Abstract:
Magnesium (Mg) alloys, the lightest metal construction material used in industry, play a vital role in future development. However, the poor corrosion resistance of Mg alloys in corrosion environments largely limits their potential wide applications. Therefore, a micro-arc oxidation/graphene oxide/stearic acid (MAO/GO/SA) superhydrophobic composite coating with superior corrosion resistance was fabricated on a Mg alloy AZ91D through micro-arc oxidation (MAO) technology, electrodeposition technique, and self-assembly technology. The composition and microstructure of the coating were characterized by scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy, and Raman spectroscopy. The effective protection of the MAO/GO/SA composite coating applied to a substrate was evaluated using potentiodynamic polarization, electrochemical impedance spectroscopy tests, and salt spray tests. The results showed that the MAO/GO/SA composite coating with a petal spherical structure had the best superhydrophobicity, and it attained a contact angle of 159.53° ± 2°. The MAO/GO/SA composite coating exhibited high resistance to corrosion, according to electrochemical and salt spray tests.
Xiaoye Zhou, and
Available online 30 December 2022, https://doi.org/10.1007/s12613-022-2595-0
Abstract:
With the rapid development of artificial intelligence technology and increasing material data, machine learning- and artificial intelligence-assisted design of high-performance steel materials is becoming a mainstream paradigm in materials science. Machine learning methods, based on an interdisciplinary discipline between computer science, statistics and material science, are good at discovering correlations between numerous data points. Compared with the traditional physical modeling method in material science, the main advantage of machine learning is that it overcomes the complex physical mechanisms of the material itself and provides a new perspective for the research and development of novel materials. This review starts with data preprocessing and the introduction of different machine learning models, including algorithm selection and model evaluation. Then, some successful cases of applying machine learning methods in the field of steel research are reviewed based on the main theme of optimizing composition, structure, processing, and performance. The application of machine learning methods to the performance-oriented inverse design of material composition and detection of steel defects is also reviewed. Finally, the applicability and limitations of machine learning in the material field are summarized, and future directions and prospects are discussed.
Poovazhagan Lakshmanan, and
Available online 27 December 2022, https://doi.org/10.1007/s12613-022-2592-3
Abstract:
The introduction of in-pipe robots for sewage cleaning provides researchers with new options for pipe inspection, such as leakage, crack, gas, and corrosion detection, which are standard applications common in the current industrial scenario. The question that is frequently overlooked in all these cases is the inherent resistance of the robots to corrosion. The mechanical, microstructural, and corrosion properties of aluminum 7075 incorporated with various weight percentages (0, 0.5wt%, 1wt%, and 1.5wt%) of carbon nanotubes (CNTs) are discussed. It is fabricated using a rotational ultrasonication with mechanical stirring (RUMS)-based casting method for improved corrosion resistance without compromising the mechanical properties of the robot. 1wt% aluminum–CNTs nanocomposite shows good corrosion and mechanical properties, meeting the requirements imposed by the sewage environment of the robot.
Available online 23 December 2022, https://doi.org/10.1007/s12613-022-2589-y
Abstract:
This monograph presents an overview of friction stir processing (FSP) of surface metal-matrix composites (MMCs) using the AZ91 magnesium alloy. The reported results in relation to various reinforcing particles, including silicon carbide (SiC), alumina (Al2O3), quartz (SiO2), boron carbide (B4C), titanium carbide (TiC), carbon fiber, hydroxyapatite (HA), in-situ formed phases, and hybrid reinforcements, are summarized. AZ91 composite fabricating methods based on FSP are explained, including groove filling (grooving), drilled hole filling, sandwich method, stir casting followed by FSP, and formation of in-situ particles. The effects of introducing second-phase particles and FSP process parameters (e.g., tool rotation rate, traverse speed, and the number of passes) on the microstructural modification, grain refinement, homogeneity in the distribution of particles, inhibition of grain growth, mechanical properties, strength–ductility trade-off, wear/tribological behavior, and corrosion resistance are discussed. Finally, useful suggestions for future work are proposed, including focusing on the superplasticity and superplastic forming, metal additive manufacturing processes based on friction stir engineering (such as additive friction stir deposition), direct FSP, stationary shoulder FSP, correlation of the dynamic recrystallization (DRX) grain size with the Zener–Hollomon parameter similar to hot deformation studies, process parameters (such as the particle volume fraction and external cooling), and common reinforcing phases such as ZrO2 and carbon nanotubes.
Limin Yu, and
Available online 23 December 2022, https://doi.org/10.1007/s12613-022-2591-4
Abstract:
Tin-based materials are very attractive anodes because of their high theoretical capacity, but their rapid capacity fading from volume expansions limits their practical applications during alloying and dealloying processes. Herein, the improved binder-free tin-copper intermetallic/carbon nanotubes (Cu6Sn5/CNTs) alloy thin-film electrodes are directly fabricated through efficient in situ electrodeposition from the leaching solution of treated waste-printed circuit boards (WPCBs). The characterization results show that the easily agglomerated Cu6Sn5 alloy nanoparticles are uniformly dispersed across the three-dimensional network when the CNTs concentration in the electrodeposition solution is maintained at 0.2 g·L−1. Moreover, the optimal Cu6Sn5/CNTs-0.2 alloy thin-film electrode can not only provide a decent discharge specific capacity of 458.35 mAh·g−1 after 50 cycles at 100 mA·g−1 within capacity retention of 82.58% but also deliver a relatively high reversible specific capacity of 518.24, 445.52, 418.18, 345.33, and 278.05 mAh·g−1 at step-increased current density of 0.1, 0.2, 0.5, 1.0, and 2.0 A·g−1, respectively. Therefore, the preparation process of the Cu6Sn5/CNTs-0.2 alloy thin-film electrode with improved electrochemical performance may provide a cost-effective strategy for the resource utilization of WPCBs to fabricate anode materials for lithium-ion batteries.
Xiaodi Liu, and
Available online 23 December 2022, https://doi.org/10.1007/s12613-022-2590-5
Abstract:
Because of their large volume variation and inferior electrical conductivity, Mn3O4-based oxide anode materials have short cyclic lives and poor rate capability, which obstructs their development. In this study, we successfully prepared a Mn3O4/N-doped honeycomb carbon composite using a smart and facile synthetic method. The Mn3O4 nanopolyhedra are grown on N-doped honeycomb carbon, which evidently mitigates the volume change in the charging and discharging processes but also improves the electrochemical reaction kinetics. More importantly, the Mn–O–C bond in the Mn3O4/N-doped honeycomb carbon composite benefits electrochemical reversibility. These features of the Mn3O4/N-doped honeycomb carbon (NHC) composite are responsible for its superior electrochemical performance. When used for Li-ion batteries, the Mn3O4/N-doped honeycomb carbon anode exhibits a high reversible capacity of 598 mAh·g−1 after 350 cycles at 1 A·g−1. Even at 2 A·g−1, the Mn3O4/NHC anode still delivers a high capacity of 472 mAh·g−1. This work provides a new prospect for synthesizing and developing manganese-based oxide materials for energy storage.
Qizheng Qin, and
Available online 10 December 2022, https://doi.org/10.1007/s12613-022-2586-1
Abstract:
This study synthesised a zincic salt (ZS) as a depressant for marmatite–galena separation. The effect of ZS on the flotation of marmatite and galena was investigated through micro-flotation tests. 88.89% of the galena was recovered and 83.39% of the marmatite was depressed with ZS dosage of 750 mg·L−1 at pH = 4. The depression mechanism of ZS on marmatite was investigated by a variety of techniques, including adsorption measurements, Fourier transform infrared (FTIR), X-ray photoelectron spectroscopic (XPS) analysis, and time of flight secondary ion mass spectrometry (ToF-SIMS). Results of adsorption tests and FTIR reveal that ZS adsorbed on marmatite surface and impeded the subsequent adsorption of butyl xanthate (BX). The results of XPS and ToF-SIMS indicate that the \begin{document}${\mathrm{Z}\mathrm{n}\mathrm{O}}_{2}^{2-}$\end{document} released by ZS could be chemisorbed on the marmatite surface and depress marmatite flotation.
Tianci Li, and
Available online 9 December 2022, https://doi.org/10.1007/s12613-022-2585-2
Abstract:
To assess the widely used submerged side-blowing in pyrometallurgy, a high-speed camera–digital image processing–statistical approach was used to systematically investigate the effects of the gas flow rate, nozzle diameter, and inclination angle on the space–time distribution and penetration behavior of submerged side-blown gas in an air–water system. The results show that the gas motion gradually changes from a bubbling regime to a steady jetting regime and the formation of a complete jet structure as the flow rate increases. When the flow rate is low, a bubble area is formed by large bubbles in the area above the nozzle. When the flow rate and the nozzle diameter are significant, a bubble area is formed by tiny bubbles in the area above the nozzle. The increased inclination angle requires a more significant flow rate to form a complete jet structure. In the sampling time, the dimensionless horizontal and vertical penetration depths are Gaussian distributed. Decreasing the nozzle diameter and increasing the flow rate or inclination angle will increase the distribution range and discreteness. New correlations for a penetration depth with an error of ±20% were obtained through dimensional analysis. The dimensionless horizontal penetration depth of an argon-melt system in a 120 t converter calculated by the correlation proposed by the current study is close to the result calculated by a correlation in the literature and a numerical simulation result in the literature.
Available online 7 December 2022, https://doi.org/10.1007/s12613-022-2584-3
Abstract:
Pure Ni and its composites with different percentages of Ni–Cr nano-oxides were coated over carbon steel to assess the coating features and mechanical and corrosion behavior. A nano-oxide composite of Ni–Cr was first synthesized through chemical coprecipitation with uniform distribution constituents. Electrodeposition was employed to coat pure Ni and Ni–(Ni–Cr) oxides (10, 20, 30, 40, and 50 g/L) on the steel sheets. Transmission electron microscope and field emission scanning electron microscope were adopted to examine the microstructure of powders and coatings, and X-ray diffraction analysis was employed to study the chemical composition. The microhardness, thickness, and wear resistance of the coatings were assessed, polarization and electrochemical impedance spectroscopy (EIS) tests were conducted to analyze the corrosion behavior, and the corresponding equivalent circuit was developed. Results showed flawless and crack-free coatings for all samples and uniform distribution of nano-oxides in the Ni matrix for the samples of 10–30 g/L. Agglomerated oxides were detected at high concentrations. Maximum microhardness (HV 661), thickness (116 µm), and wear resistance of coatings were found at 30 g/L. A three-loop equivalent circuit corresponded satisfactorily to all EIS data. The corrosion resistance increased with the nano-oxide concentration of up to 30 g/L but decreased at 40 g/L. The sample of 50 g/L showed the best corrosion resistance.
Zihan Zhang, and
Available online 3 December 2022, https://doi.org/10.1007/s12613-022-2583-4
Abstract:
The demand of high-end electromagnetic wave absorbing materials puts forward higher requirements on comprehensive performances of small thickness, lightweight, broadband, and strong absorption. Herein, a novel multi-layer stepped metamaterial absorber with gradient electromagnetic properties is proposed. The complex permittivity and permeability of each layer are tailored via the proportion of carbonyl-iron and carbon-fiber dispersing into the epoxy resin. The proposed metamaterial is further optimized via adjusting the electromagnetic parameters and geometric sizes of each layer. Comparing with the four-layer composite with gradient electromagnetic properties which could only realize reflection loss (RL) of less than −6 dB in 2.0–40 GHz, the optimized stepped metamaterial with the same thickness and electromagnetic properties realizes less than −10 dB in the relevant frequency range. Additionally, the RL of less than −15 dB is achieved in the frequency range of 11.2–21.4 GHz and 28.5–40 GHz. The multiple electromagnetic wave absorption mechanism is discussed based on the experimental and simulation results, which is believed to be attributed to the synergy effect induced by multi-scale structures of the metamaterial. Therefore, combining multi-layer structures and periodic stepped structures into a novel gradient absorbing metamaterial would give new insights into designing microwave absorption devices for broadband electromagnetic protections.
Available online 3 December 2022, https://doi.org/10.1007/s12613-022-2581-6
Abstract:
To protect the AM60B magnesium alloy from corrosion, a sol-gel coating containing hydroxylated g-C3N4 nanoplates was applied. The chemical composition of the hydroxylated g-C3N4 nanoplates was investigated using X-ray photoelectron spectroscopy (XPS). The hydroxylation process did not affect the crystal size, specific surface area, pore volume, average pore diameter, and thermal stability of the g-C3N4 nanoplates. After incorporating pristine and hydroxylated g-C3N4 nanoplates, dense sol-gel coatings were obtained. Transmission electron microscopy (TEM) revealed the uniform distribution of the modified g-C3N4 in the coating. The average roughness of the coating was also reduced after adding the modified nanoplates due to the decreased aggregation tendency. Electrochemical impedance spectroscopy (EIS) examinations in simulated acid rain revealed a significant improvement in the anticorrosion properties of the sol-gel film after the addition of the modified g-C3N4 due to the chemical bonding of the coating to the nanoplates.
He Wan, and
Available online 3 December 2022, https://doi.org/10.1007/s12613-022-2582-5
Abstract:
The flotation separation of chalcopyrite and talc is challenging due to their similar natural floatability characteristics. Besides, it is usually difficult to effectively inhibit talc by adding sodium carboxymethyl cellulose (CMC) alone during chalcopyrite flotation. Here, a combined inhibitor comprising acidified sodium silicate (ASS) and CMC was employed to realize effective flotation separation of chalcopyrite and talc, and the combined inhibition mechanism was further investigated. Microflotation results showed that adding ASS strengthened the inhibitory effect of CMC on talc and improved the separation of chalcopyrite and talc. The zeta potential, Fourier transform infrared, and X-ray photoelectron spectroscopy analysis indicated that CMC was mainly adsorbed on the talc surface via hydroxyl and carboxyl groups. Moreover, the addition of ASS improved the adsorption of carboxyl groups. Furthermore, the adsorption experiments and apparent viscosity measurements revealed that adding ASS dispersed the pulp well, which reduced the apparent viscosity, improved the adsorption amount of CMC on the talc surface, and enhanced the inhibition of talc in chalcopyrite flotation.
Man Jiang, and
Available online 3 December 2022, https://doi.org/10.1007/s12613-022-2580-7
Abstract:
We analyzed a novel cationic collector using chemical plant byproducts, such as cetyltrimethylammonium bromide (CTAB) and dibutyl phthalate (DBP). Our aim is to establish a highly effective and economical process for the removal of quartz from collophane. A microflotation test with a 25 mg·L−1 collector at pH value of 6–10 demonstrates a considerable difference in the floatability of pure quartz and fluorapatite. Flotation tests for a collophane sample subjected to the first reverse flotation for magnesium removal demonstrates that a rough flotation process (using a 0.4 kg·t−1 new collector at pH = 6) results in a collophane concentrate with 29.33wt% P2O5 grade and 12.66wt% SiO2 at a 79.69wt% P2O5 recovery, providing desirable results. Mechanism studies using Fourier transform infrared spectroscopy, zeta potential, and contact angle measurements show that the adsorption capacity of the new collector for quartz is higher than that for fluorapatite. The synergistic effect of DBP increases the difference in hydrophobicity between quartz and fluorapatite. The maximum defoaming rate of the novel cationic collector reaches 142.8 mL·min−1. This is considerably higher than that of a conventional cationic collector.
Meiju Zhang, and
Available online 25 November 2022, https://doi.org/10.1007/s12613-022-2576-3
Abstract:
Magnetization roasting is one of the most effective way of utilizing low-grade refractory iron ore. However, the reduction roasting of siderite (FeCO3) generates weakly magnetic wüstite, thus reducing iron recovery via weak magnetic separation. We systematically studied and proposed the fluidized preoxidation–low-temperature reduction magnetization roasting process for siderite. We found that the maghemite generated during the air oxidation roasting of siderite would be further reduced into wüstite at 500 and 550°C due to the unstable intermediate product magnetite (Fe3O4). Stable magnetite can be obtained through maghemite reduction only at low temperature. The optimal fluidized magnetization roasting parameters included preoxidation at 610°C for 2.5 min, followed by reduction at 450°C for 5 min. For roasted ore, weak magnetic separation yielded an iron ore concentrate grade of 62.0wt% and an iron recovery rate of 88.36%. Compared with that of conventional direct reduction magnetization roasting, the iron recovery rate of weak magnetic separation had greatly improved by 34.33%. The proposed fluidized preoxidation–low-temperature reduction magnetization roasting process can realize the efficient magnetization roasting utilization of low-grade refractory siderite-containing iron ore without wüstite generation and is unlimited by the proportion of siderite and hematite in iron ore.
Yong Liu, and
Available online 25 November 2022, https://doi.org/10.1007/s12613-022-2577-2
Abstract:
With the number of decommissioned electric vehicles increasing annually, a large amount of discarded power battery cathode material is in urgent need of treatment. However, common leaching methods for recovering metal salts are economically inefficient and polluting. Meanwhile, the recycled material obtained by lithium remediation alone has limited performance in cycling stability. Herein, a short method of solid-phase reduction is developed to recover spent LiFePO4 by simultaneously introducing Mg2+ ions for hetero-atom doping. Issues of particle agglomeration, carbon layer breakage, lithium loss, and Fe3+ defects in spent LiFePO4 are also addressed. Results show that Mg2+ addition during regeneration can remarkably enhance the crystal structure stability and improve the Li+ diffusion coefficient. The regenerated LiFePO4 exhibits significantly improved electrochemical performance with a specific discharge capacity of 143.2 mAh·g−1 at 0.2 C, and its capacity retention is extremely increased from 37.9% to 98.5% over 200 cycles at 1 C. Especially, its discharge capacity can reach 95.5 mAh·g−1 at 10 C, which is higher than that of spent LiFePO4 (55.9 mAh·g−1). All these results show that the proposed regeneration strategy of simultaneous carbon coating and Mg2+ doping is suitable for the efficient treatment of spent LiFePO4.
Bin Xu, and
Available online 24 November 2022, https://doi.org/10.1007/s12613-022-2574-5
Abstract:
The use of aeolian sand (AS) as an aggregate to prepare coal mine cemented filling materials can resolve the problems of gangue shortage and excessive AS deposits. Owing to the lack of research on the mechanism of cemented AS backfill (CASB), the response surface method (RSM) was adopted in this study to analyze the influence of ordinary Portland cement (PO) content (x1), fly ash (FA)–AS (FA–AS) ratio (x2), and concentration (x3) on the mechanical and microscopic properties of the CASB. The hydration characteristics and internal pore structure of the backfill were assessed through thermogravimetric/derivative thermogravimetric analysis, mercury intrusion porosimetry, and scanning electron microscopy. The RSM results show that the influence of each factor and interaction term on the response values is extremely significant (except x1x3, which had no obvious effect on the 28 d strength). The uniaxial compressive strength (UCS) increased with the PO content, FA–AS ratio, and concentration. The interaction effects of x1x2, x1x3, and x2x3 on the UCS at 3, 7, and 28 d were analyzed. In terms of the influence of interaction items, an improvement in one factor promoted the strengthening effect of another factor. The enhancement mechanism of the curing time, PO content, and FA–AS ratio on the backfill was reflected in the increase in hydration products and pore structure optimization. By contrast, the enhancement mechanism of the concentration was mainly the pore structure optimization. The UCS was positively correlated with weight loss and micropore content but negatively correlated with the total porosity. The R2 value of the fitting function of the strength and weight loss, micropore content, and total porosity exceeded 0.9, which improved the characterization of the enhancement mechanism of the UCS based on the thermogravimetric analysis and pore structure. This work obtained that the influence rules and mechanisms of the PO, FA–AS, concentration, and interaction terms on the mechanical properties of the CASB provided a certain theoretical and engineering guidance for CASB filling.
Xiaodong Wu, and
Available online 24 November 2022, https://doi.org/10.1007/s12613-022-2575-4
Abstract:
To solve the uneven burden of same-type holes reducing the blasting efficiency due to the limitation of drilling equipment, we need a double-face program-controlled planning method for hole position parameters used on a computer-controlled drilling jumbo. The cross-section splits into even and uneven areas. It also considers the uneven burden at the hole’s entrance and bottom. In the uneven area, various qualifying factors are made to optimize the hole spacing and maximize the burden uniformity, combined with the features of the area edges and grid-based segmentation methods. The hole position coordinates and angles in the even area are derived using recursion and iteration algorithms. As a case, this method presents all holes in a 4.8 m wide and 3.6 m high cross-section. Compared with the design produced by the drawing method, our planning in the uneven area improved the standard deviation of the hole burden by 40%. The improved hole layout facilitates the evolution of precise, efficient, and intelligent blasting in underground mines.
Wenbin Cao, and
Available online 17 November 2022, https://doi.org/10.1007/s12613-022-2573-6
Abstract:
B and N mixed anions co-doped titania with various crystal phases such as anatase, brookite, and rutile were successfully synthesized by a hydrothermal synthesis followed by heat treatment in an ammonia gas atmosphere at 550–650oC (denoted as BN-Ana_x, BN-Bro_x, and BN-Rut_x, x is the treatment temperature). The colors of as-prepared BN-Ana, BN-Bro, and BN-Rut are red, yellow-green, and cyan-green, respectively. The color changing mechanism of titania was related to their various band gap structure and the existence of B–N bonding. The nitridation temperature exhibits effective color changing compared to that of nitridation time. The different phases of the mixed anion co-doped titania possess different photocatalytic deNOx activity. The BN-Ana and BN-Rut show poor photocatalytic deNOx activity, while the BN-Bro shows excellent photocatalytic deNOx activity, better than that of standard titania photocatalyst Degussa P25. The colorful titania with low-photocatalytic activity is heavy metal elements free, indicating their possible applications as nontoxic color pigments or novel cosmetic raw materials.
Yingwei Lü, and
Available online 20 September 2022, https://doi.org/10.1007/s12613-022-2552-y
Abstract:
Copper–indium–gallium–diselenide (CIGS) is a fast-evolving commercial solar cell. The firm demand for global carbon reduction and the rise of potential environmental threats necessitate spent CIGS solar cell recycling. In this paper, the sources and characteristics of valuable metals in spent CIGS solar cells were reviewed. The potential environmental impacts of CIGS, including service life, critical material, and material toxicity, were outlined. The main recovery methods of valuable metals in the various types of spent CIGS, including hydrometallurgy, pyrometallurgy, and comprehensive treatment processes, were compared and discussed. The mechanism of different recovery processes was summarized. The challenges faced by different recycling processes of spent CIGS were also covered in this review. Finally, the economic viability of the recycling process was assessed. The purpose of this review is to provide reasonable suggestions for the sustainable development of CIGS and the harmless disposal of spent CIGS.
Zehua Wang, and
Available online 6 September 2022, https://doi.org/10.1007/s12613-022-2545-x
Abstract:
A backfilling body-coal pillar-backfilling body (BPB) structure formed by pillar-side cemented paste backfilling can bear overburden stress and ensure safe mining. However, the failure response of BPB composite samples must be investigated. This paper examines the deformation characteristics and damage evolution of six types of BPB composite samples using a digital speckle correlation method under uniaxial compression conditions. A new damage evolution equation was established on the basis of the input strain energy and dissipated strain energy at the peak stress. The prevention and control mechanisms of the backfilling body on the coal pillar instability were discussed. The results show that the deformation localization and macroscopic cracks of the BPB composite samples first appeared at the coal–backfilling interface, and then expanded to the backfilling elements, ultimately appearing in the coal elements. The elastic strain energy in the BPB composite samples reached a maximum at the peak stress, whereas the dissipated energy continued to accumulate and increase. The damage evolution curve and equation agree well with the test results, providing further understanding of instability prevention and the control mechanisms of the BPB composite samples. The restraining effect on the coal pillar was gradually reduced with decreasing backfilling body element’s volume ratio, and the BPB composite structure became more vulnerable to failure. This research is expected to guide the design, stability monitoring, instability prevention, and control of BPB structures in pillar-side cemented paste backfilling mining.
Yi Qiang, and
Available online 16 August 2022, https://doi.org/10.1007/s12613-022-2536-y
Abstract:
Higher requirements for the accuracy of relevant models are put throughout the transformation and upgrade of the iron and steel sector to intelligent production. It has been difficult to meet the needs of the field with the usual prediction model of mechanical properties of hot-rolled strip. Insufficient data and difficult parameter adjustment limit deep learning models based on multi-layer networks in practical applications; besides, the limited discrete process parameters used make it impossible to effectively depict the actual strip processing process. In order to solve these problems, this research proposes a new sampling approach for mechanical characteristics input data of hot-rolled strip based on the multi-grained cascade forest (gcForest) framework. According to the characteristics of complex process flow and abnormal sensitivity of process path and parameters to product quality in the hot-rolled strip production, a three-dimensional continuous time series process data sampling method based on time–temperature–deformation was designed. The basic information of strip steel (chemical composition and typical process parameters) is fused with the local process information collected by multi-grained scanning, so that the next link’s input has both local and global features. Furthermore, in the multi-grained scanning structure, a sub sampling scheme with a variable window was designed, so that input data with different dimensions can get output characteristics of the same dimension after passing through the multi-grained scanning structure, allowing the cascade forest structure to be trained normally. Finally, actual production data of three steel grades was used to conduct the experimental evaluation. The results reveal that the gcForest-based mechanical property prediction model outperforms the competition in terms of comprehensive performance, ease of parameter adjustment, and ability to sustain high prediction accuracy with fewer samples.
Yanling Zhang, and
Available online 2 April 2022, https://doi.org/10.1007/s12613-022-2489-1
Abstract:
Augite-based glass ceramics were synthesised using ZnO, FeO, and Fe2O3 as additives, and the spinel formation, matrix structure, crystallisation thermodynamics, and physicochemical properties were investigated. The results showed that oxides resulted in numerous preliminary spinels in the glass matrix. FeO, ZnO, and Fe2O3 influenced the formation of spinel, while FeO simplified the glass network. FeO and ZnO promoted bulk crystallisation of the parent glass. After adding oxides, the grains of augite phase were refined, and the relative quantities of augite crystal planes were also influenced. All samples displayed good mechanical properties and chemical stability. The 2wt% ZnO-doping sample displayed the maximum flexural strength (170.3 MPa). Chromium leaching amount values of all the samples were less than the national standard (1.5 mg/L), confirming the safety of the materials. In conclusion, an appropriate amount of zinc-containing raw material is beneficial for the preparation of augite-based glass ceramics.
Display Method:
2023, vol. 30, no. 5, pp. 791-801. https://doi.org/10.1007/s12613-022-2528-y
Abstract:
High geostress will become a normality in the deep because in-situ stress rises linearly with depth. The geological structure grows immensely intricate as depth increases. Faults, small fractures, and joint fissures are widely developed. The objective of this paper is to identify geostress anomalies at a variety of locations near faults and to demonstrate their accumulation mechanism. Hydrofracturing tests were conducted in seven deep boreholes. We conducted a test at a drilling depth of over one thousand meters to reveal and quantify the influence of faults on in-situ stresses at the hanging wall, footwall, between faults, end of faults, junction of faults, and far-field of faults. The effect of fault sites and characteristics on the direction and magnitude of stresses has been investigated and compared to test boreholes. The accumulation heterogeneity of stresses near faults was illustrated by a three-dimensional numerical simulation, which is utilized to explain the effect of faults on the accumulation and differentiation of in-situ stress. Due to regional tectonics and faulting, the magnitude, direction, and stress regime are all extremely different. The concentration degree of geostress and direction change will vary with the location of faults near faults, but the magnitude and direction of in-situ stress conform to regional tectonic stress at a distance from the faults. The focal mechanism solution has been verified using historical seismic ground motion vectors. The results demonstrate that the degree of stress differentiation varies according to the fault attribute and its position. Changes in stress differentiation and its ratio from strong to weak occur between faults, intersection, footwall, end of faults, and hanging wall; along with the sequence of orientation is the footwall, between faults, the end of faults, intersection, and hanging wall. This work sheds new light on the fault-induced stress accumulation and orientation shift mechanisms across the entire cycle.
2023, vol. 30, no. 5, pp. 802-812. https://doi.org/10.1007/s12613-022-2554-9
Abstract:
To ensure safe and economical backfill mining, the mechanical response of the backfill–rock interaction system needs to be understood. The numerical investigation of the mechanical behavior of backfill–rock composite structure (BRCS) under triaxial compression, which includes deformation, failure patterns, strength characteristics, and acoustic emission (AE) evolution, was proposed. The models used in the tests have one rough interface, two cement–iron tailings ratios (CTRs), four interface angles (IAs), and three confining pressures (CPs). Results showed that the deformation, strength characteristics, and failure patterns of BRCS under triaxial compression depend on IA, CP, and CTR. The stress–strain curves of BRCS under triaxial compression could be divided into five stages, namely, compaction, elasticity, yield, strain softening, and residual stress. The relevant AE counts have corresponding relationships with different stages. The triaxial compressive strengths of composites increase linearly with the increase of the CP. Furthermore, the CP stress strengthening effect occurs. When the IAs are 45° and 60°, the failure areas of composites appear in the interface and backfill. When the IAs are 75° and 90°, the failure areas of composites appear in the backfill, interface, and rock. Moreover, the corresponding failure modes yield the combined shear failure. The research results provide the basis for further understanding of the stability of the BRCS.
2023, vol. 30, no. 5, pp. 813-823. https://doi.org/10.1007/s12613-022-2522-4
Abstract:
This study presents a comparative study of the flocculation behavior of kaolinite induced by chitosan-graft-poly(acrylamide-dimethyl diallyl ammonium chloride) (Chi-g-CPAM) and a commercial cationic polyacrylamide (CPAM). The flocculation behaviour was characterised in terms of both flocculation kinetics and the corresponding morphology changes during flocculation. Both Chi-g-CPAM and CPAM were grafted from silica wafers by means of atom transfer radical polymerization (ATRP). The quartz crystal microbalance with dissipation (QCM-D) tests were conducted. The equilibrium time flocculated by Chi-g-CPAM was found to be 0.46 times as that of CPAM, together with a larger total mass of kaolinite layer. The flocculation behaviour by Chi-g-CPAM can be well captured by a pseudo-first-order model. In contrast, the presence of CPAM leads to a more complex kinetics. A relatively larger fitting slope (0.4663) was obtained at the initial stage but the fitting slope droped to 0.2026 after 800 min, indicating a densification process caused by CPAM. The flocculation kinetics of CPAM can be captured by the Elovich model for the inital stage but the combination of pseudo-first-order and pseudo-second-order models for the latter stages, which can be attributed to the long chain of CPAM. With a dosage of 75 g/t, the settling test with Chi-g-CPAM exhibits the same turbidity in the supernatant but a smaller layer thickness of the settlement compared to CPAM. The study enables a better understanding of the flocculation behavior and contributes to the development of efficient flocculants in mineral processing and tailings treatment.
2023, vol. 30, no. 5, pp. 824-833. https://doi.org/10.1007/s12613-022-2523-3
Abstract:
In order to develop limonite and decrease CO2 emissions, siderite is proposed as a clean reductant for suspension magnetization roasting (SMR) of limonite. An iron concentrate (iron grade: 65.92wt%, iron recovery: 98.54wt%) was obtained by magnetic separation under the optimum SMR conditions: siderite dosage 40wt%, roasting temperature 700°C, roasting time 10 min. According to the magnetic analysis, SMR achieved the conversion of weak magnetic minerals to strong magnetic minerals, thus enabling the recovery of iron via magnetic separation. Based on the phase transformation analysis, during the SMR process, limonite was first dehydrated and converted to hematite, and then siderite decomposed to generate magnetite and CO, where CO reduced the freshly formed hematite to magnetite. The microstructure evolution analysis indicated that the magnetite particles were loose and porous with a destroyed structure, making them easier to be ground. The non-isothermal kinetic results show that the main reaction between limonite and siderite conformed to the two-dimension diffusion mechanism, suggesting that the diffusion of CO controlled the reaction. These results encourage the application of siderite as a reductant in SMR.
2023, vol. 30, no. 5, pp. 834-843. https://doi.org/10.1007/s12613-022-2564-7
Abstract:
2023, vol. 30, no. 5, pp. 844-856. https://doi.org/10.1007/s12613-022-2558-5
Abstract:
A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow, circulation flow rate, and mixing time during Ruhrstahl-Heraeus (RH) refining process. Also, a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up, and measurements were carried out to validate the mathematical model. The results show that, with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min–1, the mixing time predicted by the mathematical model agrees well with the measured values. The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations, where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value. In addition, the circulation flow rate was 9 kg·s–1. When the gas blowing nozzle was horizontally rotated by either 30° or 45°, the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle, due to the rotational flow formed in the up-snorkel. Furthermore, the mixing time at the monitoring point 1, 2, and 3 was shortened by around 21.3%, 28.2%, and 12.3%, respectively. With the nozzle angle of 30° and 45°, the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.
2023, vol. 30, no. 5, pp. 857-867. https://doi.org/10.1007/s12613-022-2436-1
Abstract:
Currently, the process of extracting rubidium from ores has attracted a great deal of attention due to the increasing application of rubidium in high-technology field. A novel process for the comprehensive utilization of rubidium ore resources is proposed in this paper. The process consists mainly of mineral dissociation, selective leaching, and desilication. The results showed that the stable silicon–oxygen tetrahedral structure of the rubidium ore was completely disrupted by thermal activation and the mineral was completely dissociated, which was conducive to subsequent selective leaching. Under the optimal conditions, extractions of 98.67% Rb and 96.23% K were obtained by leaching the rubidium ore. Moreover, the addition of a certain amount of activated Al(OH)3 during leaching can effectively inhibit the leaching of silicon. In the meantime, the leach residue was sodalite, which was successfully synthesized to zeolite A by hydrothermal conversion. The proposed process provided a feasible strategy for the green extraction of rubidium and the sustainable utilization of various resources.
2023, vol. 30, no. 5, pp. 868-876. https://doi.org/10.1007/s12613-022-2527-z
Abstract:
The effects of fluoride ions (F−) on the electrochemical behavior and coordination properties of titanium ions (Tin+) were studied in this work, by combining electrochemical and mathematical analysis as well as spectral techniques. The α was taken as a factor to indicate the molar concentration ratio of F− and Tin+. Cyclic voltammetry (CV), square wave voltammetry (SWV), and open circuit potential method (OCP) were used to study the electrochemical behavior of titanium ions under conditions of various α, and in-situ sampler was used to prepare molten salt samples when α equal to 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, and 8.0. And then, samples were analyzed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The results showed that F− in molten salt can reduce the reduction steps of titanium ions and greatly affects the proportion of valence titanium ions which making the high-valence titanium content increased and more stable. Ti2+ cannot be detected in the molten salt when α is higher than 3.0 and finally transferred to titanium ions with higher valence state. Investigation revealed that the mechanism behind those phenomenon is the coordination compounds (\begin{document}$\text{TiCl}_{j}\text{F}_{i}^{m-}$\end{document}) forming.
2023, vol. 30, no. 5, pp. 877-885. https://doi.org/10.1007/s12613-022-2492-6
Abstract:
Platinum group metals (PGMs), especially Pd, Pt, and Rh, have drawn great attention due to their unique features. Direct separation of Pd and Pt from highly acidic automobile catalyst leach liquors is disturbed by various factors. This work investigates the effect of various parameters including the acidity, extractant concentration, phase ratio A/O, and diluents on the Pd and Pt extraction and their stripping behaviors. The results show that the Pd and Pt are successfully separated from simulated leach liquor of spent automobile catalysts with monothio-Cyanex 272 and trioctylamine (TOA). Monothio-Cyanex 272 shows strong extractability and specific selectivity for Pd, and only one single stage is needed to recover more than 99.9% of Pd, leaving behind all the Pt, Rh, and base metals of Fe, Mg, Ce, Ni, Cu, and Co in the raffinate. The loaded Pd is efficiently stripped by acidic thiourea solutions. TOA shows strong extractability for Pt and Fe at acidity of 6 mol·L–1 HCl. More than 99.9% of Pt and all of the Fe are extracted into the organic phase after two stages of countercurrent extraction. Diluted HCl easily scrubs the loaded base metals (Fe, Cu, and Co). The loaded Pt is efficiently stripped by 1.0 mol·L–1 thiourea and 0.05–0.1 mol·L–1 NaOH solutions. Monothio-Cyanex 272 and TOA can realize the separation of Pd and Pt from highly acidic leach liquor of spent automobile catalysts.
2023, vol. 30, no. 5, pp. 886-896. https://doi.org/10.1007/s12613-022-2569-2
Abstract:
The metallurgical properties of the CaO–SiO2–Al2O3–4.6wt%MgO–Fe2O3 slag system, formed by the co-treatment process of spent automotive catalyst (SAC) and copper-bearing electroplating sludge (CBES), were studied systematically in this paper. The slag structure, melting temperature, and viscous characteristics were investigated by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, FactSage calculation, and viscosity measurements. Experimental results show that the increase of Fe2O3 content (3.8wt%–16.6wt%), the mass ratio of CaO/SiO2 (m(CaO)/m(SiO2), 0.5–1.3), and the mass ratio of SiO2/Al2O3 (m(SiO2)/m(Al2O3), 1.0–5.0) can promote the depolymerization of silicate network, and the presence of a large amount of Fe2O3 in form of tetrahedral and octahedral units ensures the charge compensation of Al3+ ions and makes Al2O3 only behave as an acid oxide. Thermodynamic calculation and viscosity measurements show that with the increase of Fe2O3 content, m(CaO)/m(SiO2), and m(SiO2)/m(Al2O3), the depolymerization of silicate network structure and low-melting-point phase transformation first occur within the slag, leading to the decrease in melting point and viscosity of the slag, while further increase causes the formation of high-melting-point phase and a resultant re-increase in viscosity and melting point. Based on experimental analysis, the preferred slag composition with low polymerization degree, viscosity, and melting point is as follows: Fe2O3 content of 10.2wt%–13.4wt%, m(CaO)/m(SiO2) of 0.7–0.9 and m(SiO2)/m(Al2O3) of 3.0–4.0. This work provides a theoretical support for slag design in co-smelting process of SAC and CBES.
2023, vol. 30, no. 5, pp. 897-907. https://doi.org/10.1007/s12613-022-2571-8
Abstract:
To effectively separate and recover Co(II) from the leachate of spent lithium-ion battery cathodes, we investigated solvent extraction with quaternary ammonium salt N263 in the sodium nitrite system. N\begin{document}${\rm{O}}_2^-$\end{document} combines with Co(II) to form an anion [Co(NO2)3]−, and it is then extracted by N263. The extraction of Co(II) is related to the concentration of N\begin{document}${\rm{O}}_2^-$\end{document}. The extraction efficiency of Co(II) reaches the maximum of 99.16%, while the extraction efficiencies of Ni(II), Mn(II), and Li(I) are 9.27%‒9.80% under the following conditions: 30vol% of N263 and 15vol% of iso-propyl alcohol in sulfonated kerosene, the volume ratio of the aqueous-to-organic phase is 2:1, the extraction time is 30 min, and 1 M sodium nitrite in 0.1 M HNO3. The theoretical stages require for the Co(II) extraction are performed in the McCabe–Thiele diagram, and the extraction efficiency of Co(II) reaches more than 99.00% after three-stage counter-current extraction with Co(II) concentration of 2544 mg/L. When the HCl concentration is 1.5 M, the volume ratio of the aqueous-to-organic phase is 1:1, the back-extraction efficiency of Co(II) achieves 91.41%. After five extraction and back-extraction cycles, the Co(II) extraction efficiency can still reach 93.89%. The Co(II) extraction efficiency in the actual leaching solution reaches 100%.
2023, vol. 30, no. 5, pp. 908-916. https://doi.org/10.1007/s12613-022-2493-5
Abstract:
It was discovered the application of Al2O3 nanofluid as lubricant for steel hot rolling could synchronously achieve oxidation protection of strips surface. The underlying mechanism was investigated through hot rolling tests and molecular dynamics (MD) simulations. The employment of Al2O3 nanoparticles contributed to significant enhancement in the lubrication performance of lubricant. The rolled strip exhibited the best surface topography that the roughness reached lowest with the sparsest surface defects. Besides, the oxide scale generated on steel surface was also thinner, and the ratio of Fe2O3 among various iron oxides became lower. It was revealed the above oxidation protection effect of Al2O3 nanofluid was attributed to the deposition of nanoparticles on metal surface during hot rolling. A protective layer in the thickness of about 193 nm was formed to prevent the direct contact between steel matrix and atmosphere, which was mainly composed of Al2O3 and sintered organic molecules. MD simulations confirmed the diffusion of O2 and H2O could be blocked by the Al2O3 layer through physical absorption and penetration barrier effect.
2023, vol. 30, no. 5, pp. 917-929. https://doi.org/10.1007/s12613-022-2568-3
Abstract:
In the present work, Fe–Mn–Al–C powder mixtures were manufactured by elemental powders with different ball milling time, and the porous high-Mn and high-Al steel was fabricated by powder sintering. The results indicated that the powder size significantly decreased, and the morphology of the Fe powder tended to be increasingly flat as the milling time increased. However, the prolonged milling duration had limited impact on the phase transition of the powder mixture. The main phases of all the samples sintered at 640°C were α-Fe, α-Mn and Al, and a small amount of Fe2Al5 and Al8Mn5. When the sintering temperature increased to 1200°C, the phase composition was mainly comprised of γ-Fe and α-Fe. The weight loss fraction of the sintered sample decreased with milling time, i.e., 8.3wt% after 20 h milling compared to 15.3wt% for 10 h. The Mn depletion region (MDR) for the 10, 15, and 20 h milled samples was about 780, 600, and 370 μm, respectively. The total porosity of samples sintered at 640°C decreased from ~46.6vol% for the 10 h milled powder to ~44.2vol% for 20 h milled powder. After sintering at 1200°C, the total porosity of sintered samples prepared by 10 and 20 h milled powder was ~58.3vol% and ~51.3vol%, respectively. The compressive strength and ductility of the 1200°C sintered porous steel increased as the milling time increased.
2023, vol. 30, no. 5, pp. 930-938. https://doi.org/10.1007/s12613-022-2566-5
Abstract:
The martensitic transformation, mechanical, and magnetic properties of the Ni2Mn1.5−xCuxTi0.5 (x = 0.125, 0.25, 0.375, 0.5) and Ni2−yCoyMn1.5−xCuxTi0.5 [(x = 0.125, y = 0.125, 0.25, 0.375, 0.5) and (x = 0.125, 0.25, 0.375, y = 0.625)] alloys were systematically studied by the first-principles calculations. For the formation energy, the martensite is smaller than the austenite, the Ni–(Co)–Mn–Cu–Ti alloys studied in this work can undergo martensitic transformation. The austenite and non-modulated (NM) martensite always present antiferromagnetic state in the Ni2Mn1.5−xCuxTi0.5 and Ni2−yCoyMn1.5−xCuxTi0.5 (y < 0.625) alloys. When y = 0.625 in the Ni2−yCoyMn1.5−xCuxTi0.5 series, the austenite presents ferromagnetic state while the NM martensite shows antiferromagnetic state. Cu doping can decrease the thermal hysteresis and anisotropy of the Ni–(Co)–Mn–Ti alloy. Increasing Mn and decreasing Ti content can improve the shear resistance and normal stress resistance, but reduce the toughness in the Ni–Mn–Cu–Ti alloy. And the ductility of the Co–Cu co-doping alloy is inferior to that of the Ni–Mn–Cu–Ti and Ni–Co–Mn–Ti alloys. The electronic density of states was studied to reveal the essence of the mechanical and magnetic properties.
2023, vol. 30, no. 5, pp. 939-948. https://doi.org/10.1007/s12613-022-2549-6
Abstract:
The evolution of microstructure, elemental segregation, and precipitation in GH4742 superalloy under a wide range of cooling rates was investigated using zonal melting liquid metal cooling (ZMLMC) experiments. Comparing various nickel-based superalloys, the primary dendrite spacing is significantly linearly correlated with G−1/2V−1/4 at high cooling rates, where G and V are temperature gradient and drawing rate, respectively. As the cooling rate decreases, the primary dendrite spacing increases in a dispersive manner. The secondary dendrite arm spacing is significantly correlated with (GV)−0.4 for all cooling rate ranges. The degree of elemental segregation increases and then decreases as the cooling rate increases, which is due to the competition between solute counter-diffusion and dendrite tip subcooling. With increasing the solidification rate, the size of γ′, carbides, and non-metallic inclusions gradually decreases. The morphology of the γ′ precipitate changes from plume-like to cubic to spherical. The morphology of carbide changes from block to fine-strip then to Chinese-script. The morphology of carbide is controlled by both dendrite interstitial shape and element diffusion. The inclusions are mainly composite inclusions, which usually show the growth of Ti(C,N) with oxide as the heterogeneous nucleation center and carbide on the outer surface of the carbonitride. As the cooling rate increases, the number density of composite inclusions first increases and then decreases, which is closely related to the elemental segregation behavior.
2023, vol. 30, no. 5, pp. 949-958. https://doi.org/10.1007/s12613-022-2572-7
Abstract:
Optimizing the mechanical properties and damping capacity of the duplex-structured Mg–Li–Zn–Mn alloy by tailoring the microstructure via hot extrusion was investigated. The results show that the Mg–8Li–4Zn–1Mn alloy is mainly composed of α-Mg, β-Li, Mg–Li–Zn, and Mn phases. The microstructure of the test alloy is refined owing to dynamic recrystallization (DRX) during hot extrusion. After hot extrusion, the crushed precipitates are uniformly distributed in the test alloy. The yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of as-extruded alloy reach 156 MPa, 208 MPa, and 32.3%, respectively, which are much better than that of as-cast alloy. Furthermore, the as-extruded and as-cast alloys both exhibit superior damping capacities, with the damping capacity (\begin{document}${Q}^{-1}$\end{document}) of 0.030 and 0.033 at the strain amplitude of 2 × 10−3, respectively. The mechanical properties of the test alloy can be significantly improved by hot extrusion, whereas the damping capacities have no noticeable change, which indicates that the duplex-structured Mg–Li alloys with appropriate mechanical properties and damping properties can be obtained by alloying and hot extrusion.
2023, vol. 30, no. 5, pp. 959-969. https://doi.org/10.1007/s12613-022-2542-0