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2025, vol. 32, no. 1, pp.
1-19.
https://doi.org/10.1007/s12613-024-2923-7
Abstract:
Solvent extraction, a separation and purification technology, is crucial in critical metal metallurgy. Organic solvents commonly used in solvent extraction exhibit disadvantages, such as high volatility, high toxicity, and flammability, causing a spectrum of hazards to human health and environmental safety. Neoteric solvents have been recognized as potential alternatives to these harmful organic solvents. In the past two decades, several neoteric solvents have been proposed, including ionic liquids (ILs) and deep eutectic solvents (DESs). DESs have gradually become the focus of green solvents owing to several advantages, namely, low toxicity, degradability, and low cost. In this critical review, their classification, formation mechanisms, preparation methods, characterization technologies, and special physicochemical properties based on the most recent advancements in research have been systematically described. Subsequently, the major separation and purification applications of DESs in critical metal metallurgy were comprehensively summarized. Finally, future opportunities and challenges of DESs were explored in the current research area. In conclusion, this review provides valuable insights for improving our overall understanding of DESs, and it holds important potential for expanding separation and purification applications in critical metal metallurgy.
Solvent extraction, a separation and purification technology, is crucial in critical metal metallurgy. Organic solvents commonly used in solvent extraction exhibit disadvantages, such as high volatility, high toxicity, and flammability, causing a spectrum of hazards to human health and environmental safety. Neoteric solvents have been recognized as potential alternatives to these harmful organic solvents. In the past two decades, several neoteric solvents have been proposed, including ionic liquids (ILs) and deep eutectic solvents (DESs). DESs have gradually become the focus of green solvents owing to several advantages, namely, low toxicity, degradability, and low cost. In this critical review, their classification, formation mechanisms, preparation methods, characterization technologies, and special physicochemical properties based on the most recent advancements in research have been systematically described. Subsequently, the major separation and purification applications of DESs in critical metal metallurgy were comprehensively summarized. Finally, future opportunities and challenges of DESs were explored in the current research area. In conclusion, this review provides valuable insights for improving our overall understanding of DESs, and it holds important potential for expanding separation and purification applications in critical metal metallurgy.
2025, vol. 32, no. 1, pp.
20-38.
https://doi.org/10.1007/s12613-024-2961-1
Abstract:
As a mathematical analysis method, fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties. Fractal analysis has been used to characterize the shapes of metal materials at various scales and dimensions. Conventional methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and interfaces. However, fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal materials. From the perspective of two-dimensional planes and three-dimensional curved surfaces, this paper reviews the current research status of the fractal analysis of metal precipitate interfaces, metal grain boundary interfaces, metal-deposited film surfaces, metal fracture surfaces, metal machined surfaces, and metal wear surfaces. The relationship between the fractal dimensions and properties of metal material surfaces and interfaces is summarized. Starting from three perspectives of fractal analysis, namely, research scope, image acquisition methods, and calculation methods, this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be developed. It is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future.
As a mathematical analysis method, fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties. Fractal analysis has been used to characterize the shapes of metal materials at various scales and dimensions. Conventional methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and interfaces. However, fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal materials. From the perspective of two-dimensional planes and three-dimensional curved surfaces, this paper reviews the current research status of the fractal analysis of metal precipitate interfaces, metal grain boundary interfaces, metal-deposited film surfaces, metal fracture surfaces, metal machined surfaces, and metal wear surfaces. The relationship between the fractal dimensions and properties of metal material surfaces and interfaces is summarized. Starting from three perspectives of fractal analysis, namely, research scope, image acquisition methods, and calculation methods, this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be developed. It is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future.
2025, vol. 32, no. 1, pp.
39-48.
https://doi.org/10.1007/s12613-024-2944-2
Abstract:
Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude. To investigate the correlation between the rock mass properties and maximum horizontal stress, the three-dimensional (3D) stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted, a newly defined characteristic parameter CERP was proposed as an indicator for evaluating the structural properties of rock masses, and a fuzzy relation matrix was established using the information distribution method. The results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with depth. There is no remarkable correlation between the elastic modulus, Poisson’s ratio and depth, and the distribution of data points is scattered and messy. Moreover, there is no obvious relationship between the rock quality designation (RQD) and depth. The maximum horizontal stress σH is a function of rock properties, showing a certain linear relationship with the CERP at the same depth. In addition, the overall change trend of σH determined by the established fuzzy identification method is to increase with the increase of CERP. The fuzzy identification method also demonstrates a relatively detailed local relationship between σH and CERP, and the predicted curve rises in a fluctuating way, which is in accord well with the measured stress data.
Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude. To investigate the correlation between the rock mass properties and maximum horizontal stress, the three-dimensional (3D) stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted, a newly defined characteristic parameter CERP was proposed as an indicator for evaluating the structural properties of rock masses, and a fuzzy relation matrix was established using the information distribution method. The results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with depth. There is no remarkable correlation between the elastic modulus, Poisson’s ratio and depth, and the distribution of data points is scattered and messy. Moreover, there is no obvious relationship between the rock quality designation (RQD) and depth. The maximum horizontal stress σH is a function of rock properties, showing a certain linear relationship with the CERP at the same depth. In addition, the overall change trend of σH determined by the established fuzzy identification method is to increase with the increase of CERP. The fuzzy identification method also demonstrates a relatively detailed local relationship between σH and CERP, and the predicted curve rises in a fluctuating way, which is in accord well with the measured stress data.
2025, vol. 32, no. 1, pp.
49-57.
https://doi.org/10.1007/s12613-024-2828-5
Abstract:
This study aimed to investigate the effect of varying pyrite (Py) content on copper (Cu) in the presence of different regrinding conditions, which were altered using different types of grinding media: iron, ceramic balls, and their mixture, followed by flotation in the cleaner stage. The flotation performance of rough Cu concentrate can be improved by changing the regrinding conditions based on the Py content. Scanning electron microscopy, X-ray spectrometry, ethylenediaminetetraacetic acid disodium salt extraction, and X-ray photoelectron spectroscopy studies illustrated that when the Py content was high, the use of iron media in regrinding promoted the generation of hydrophilic FeOOH on the surface of Py and improved the Cu grade. The ceramic medium with a low Py content prevented excessive FeOOH from covering the surface of chalcopyrite (Cpy). Electrochemical studies further showed that the galvanic corrosion current of Cpy–Py increased with the addition of Py and became stronger with the participation of iron media.
This study aimed to investigate the effect of varying pyrite (Py) content on copper (Cu) in the presence of different regrinding conditions, which were altered using different types of grinding media: iron, ceramic balls, and their mixture, followed by flotation in the cleaner stage. The flotation performance of rough Cu concentrate can be improved by changing the regrinding conditions based on the Py content. Scanning electron microscopy, X-ray spectrometry, ethylenediaminetetraacetic acid disodium salt extraction, and X-ray photoelectron spectroscopy studies illustrated that when the Py content was high, the use of iron media in regrinding promoted the generation of hydrophilic FeOOH on the surface of Py and improved the Cu grade. The ceramic medium with a low Py content prevented excessive FeOOH from covering the surface of chalcopyrite (Cpy). Electrochemical studies further showed that the galvanic corrosion current of Cpy–Py increased with the addition of Py and became stronger with the participation of iron media.
2025, vol. 32, no. 1, pp.
58-69.
https://doi.org/10.1007/s12613-024-2873-0
Abstract:
The utilization of iron coke provides a green pathway for low-carbon ironmaking. To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification, the effect of iron ore on the microstructure of iron coke was investigated. Furthermore, a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric method. The findings indicate that compared to coke, iron coke exhibits an augmentation in micropores and specific surface area, and the micropores further extend and interconnect. This provides more adsorption sites for CO2 molecules during the gasification process, resulting in a reduction in the initial gasification temperature of iron coke. Accelerating the heating rate in non-isothermal gasification can enhance the reactivity of iron coke. The metallic iron reduced from iron ore is embedded in the carbon matrix, reducing the orderliness of the carbon structure, which is primarily responsible for the heightened reactivity of the carbon atoms. The kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore structure. Moreover, as the proportion of iron ore increases, the activation energy for the carbon gasification gradually decreases, from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.
The utilization of iron coke provides a green pathway for low-carbon ironmaking. To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification, the effect of iron ore on the microstructure of iron coke was investigated. Furthermore, a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric method. The findings indicate that compared to coke, iron coke exhibits an augmentation in micropores and specific surface area, and the micropores further extend and interconnect. This provides more adsorption sites for CO2 molecules during the gasification process, resulting in a reduction in the initial gasification temperature of iron coke. Accelerating the heating rate in non-isothermal gasification can enhance the reactivity of iron coke. The metallic iron reduced from iron ore is embedded in the carbon matrix, reducing the orderliness of the carbon structure, which is primarily responsible for the heightened reactivity of the carbon atoms. The kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore structure. Moreover, as the proportion of iron ore increases, the activation energy for the carbon gasification gradually decreases, from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.
2025, vol. 32, no. 1, pp.
70-79.
https://doi.org/10.1007/s12613-024-2913-9
Abstract:
Currently, the Al2O3 content in the high-alumina slag systems within blast furnaces is generally limited to 16wt%–18.5wt%, making it challenging to overcome this limitation. Unlike most studies that concentrated on managing the MgO/Al2O3 ratio or basicity, this paper explored the effect of equimolar substitution of MgO for CaO on the viscosity and structure of a high-alumina CaO–MgO–Al2O3–SiO2 slag system, providing theoretical guidance and data to facilitate the application of high-alumina ores. The results revealed that the viscosity first decreased and then increased with higher MgO substitution, reaching a minimum at 15mol% MgO concentration. Fourier transform infrared spectroscopy (FTIR) results found that the depths of the troughs representing [SiO4] tetrahedra, [AlO4] tetrahedra, and Si–O–Al bending became progressively deeper with increased MgO substitution. Deconvolution of the Raman spectra showed that the average number of bridging oxygens per Si atom and the\begin{document}$ {X_{{{\text{Q}}^3}}}{\text{/}}{X_{{{\text{Q}}^2}}} $\end{document} \begin{document}$ {X_{{{\text{Q}}^i}}} $\end{document}
Currently, the Al2O3 content in the high-alumina slag systems within blast furnaces is generally limited to 16wt%–18.5wt%, making it challenging to overcome this limitation. Unlike most studies that concentrated on managing the MgO/Al2O3 ratio or basicity, this paper explored the effect of equimolar substitution of MgO for CaO on the viscosity and structure of a high-alumina CaO–MgO–Al2O3–SiO2 slag system, providing theoretical guidance and data to facilitate the application of high-alumina ores. The results revealed that the viscosity first decreased and then increased with higher MgO substitution, reaching a minimum at 15mol% MgO concentration. Fourier transform infrared spectroscopy (FTIR) results found that the depths of the troughs representing [SiO4] tetrahedra, [AlO4] tetrahedra, and Si–O–Al bending became progressively deeper with increased MgO substitution. Deconvolution of the Raman spectra showed that the average number of bridging oxygens per Si atom and the
2025, vol. 32, no. 1, pp.
80-91.
https://doi.org/10.1007/s12613-024-2898-4
Abstract:
With the continuous increase in the disposal volume of spent lithium-ion batteries (LIBs), properly recycling spent LIBs has become essential for the advancement of the circular economy. This study presents a systematic analysis of the chlorination roasting kinetics and proposes a new two-step chlorination roasting process that integrates thermodynamics for the recycling of LIB cathode materials. The activation energy for the chloride reaction was 88.41 kJ/mol according to thermogravimetric analysis–derivative thermogravimetry data obtained by using model-free, model-fitting, and Z(α) function (α is conversion rate). Results indicated that the reaction was dominated by the first-order (F1) model when the conversion rate was less than or equal to 0.5 and shifted to the second-order (F2) model when the conversion rate exceeded 0.5. Optimal conditions were determined by thoroughly investigating the effects of roasting temperature, roasting time, and the mass ratio of NH4Cl to LiCoO2. Under the optimal conditions, namely 400°C, 20 min, and NH4Cl/LiCoO2 mass ratio of 3:1, the leaching efficiency of Li and Co reached 99.43% and 99.05%, respectively. Analysis of the roasted products revealed that valuable metals in LiCoO2 transformed into CoCl2 and LiCl. Furthermore, the reaction mechanism was elucidated, providing insights for the establishment of a novel low-temperature chlorination roasting technology based on a crystal structure perspective. This technology can guide the development of LIB recycling processes with low energy consumption, low secondary pollution, high recovery efficiency, and high added value.
With the continuous increase in the disposal volume of spent lithium-ion batteries (LIBs), properly recycling spent LIBs has become essential for the advancement of the circular economy. This study presents a systematic analysis of the chlorination roasting kinetics and proposes a new two-step chlorination roasting process that integrates thermodynamics for the recycling of LIB cathode materials. The activation energy for the chloride reaction was 88.41 kJ/mol according to thermogravimetric analysis–derivative thermogravimetry data obtained by using model-free, model-fitting, and Z(α) function (α is conversion rate). Results indicated that the reaction was dominated by the first-order (F1) model when the conversion rate was less than or equal to 0.5 and shifted to the second-order (F2) model when the conversion rate exceeded 0.5. Optimal conditions were determined by thoroughly investigating the effects of roasting temperature, roasting time, and the mass ratio of NH4Cl to LiCoO2. Under the optimal conditions, namely 400°C, 20 min, and NH4Cl/LiCoO2 mass ratio of 3:1, the leaching efficiency of Li and Co reached 99.43% and 99.05%, respectively. Analysis of the roasted products revealed that valuable metals in LiCoO2 transformed into CoCl2 and LiCl. Furthermore, the reaction mechanism was elucidated, providing insights for the establishment of a novel low-temperature chlorination roasting technology based on a crystal structure perspective. This technology can guide the development of LIB recycling processes with low energy consumption, low secondary pollution, high recovery efficiency, and high added value.
2025, vol. 32, no. 1, pp.
92-101.
https://doi.org/10.1007/s12613-024-2888-6
Abstract:
In recent years, medium entropy alloys have become a research hotspot due to their excellent physical and chemical performances. By controlling reasonable elemental composition and processing parameters, the medium entropy alloys can exhibit similar properties to high entropy alloys and have lower costs. In this paper, a FeCoNi medium entropy alloy precursor was prepared via sol–gel and co-precipitation methods, respectively, and FeCoNi medium entropy alloys were prepared by carbothermal and hydrogen reduction. The phases and magnetic properties of FeCoNi medium entropy alloy were investigated. Results showed that FeCoNi medium entropy alloy was produced by carbothermal and hydrogen reduction at 1500°C. Some carbon was detected in the FeCoNi medium entropy alloy prepared by carbothermal reduction. The alloy prepared by hydrogen reduction was uniform and showed a relatively high purity. Moreover, the hydrogen reduction product exhibited better saturation magnetization and lower coercivity.
In recent years, medium entropy alloys have become a research hotspot due to their excellent physical and chemical performances. By controlling reasonable elemental composition and processing parameters, the medium entropy alloys can exhibit similar properties to high entropy alloys and have lower costs. In this paper, a FeCoNi medium entropy alloy precursor was prepared via sol–gel and co-precipitation methods, respectively, and FeCoNi medium entropy alloys were prepared by carbothermal and hydrogen reduction. The phases and magnetic properties of FeCoNi medium entropy alloy were investigated. Results showed that FeCoNi medium entropy alloy was produced by carbothermal and hydrogen reduction at 1500°C. Some carbon was detected in the FeCoNi medium entropy alloy prepared by carbothermal reduction. The alloy prepared by hydrogen reduction was uniform and showed a relatively high purity. Moreover, the hydrogen reduction product exhibited better saturation magnetization and lower coercivity.
2025, vol. 32, no. 1, pp.
102-110.
https://doi.org/10.1007/s12613-024-2896-6
Abstract:
During the continuous casting process of high-Mn high-Al steels, various types of gases such as Ar need to escape through the top of the mold. In which, the behavior of bubbles traversing the liquid slag serves as a restrictive link, closely associated with viscosity and the thickness of liquid slag. In contrast to two-dimensional surface observation, three-dimensional (3D) analysis method can offer a more intuitive, accurate, and comprehensive information. Therefore, this study employs a 3D X-ray microscope (3D-XRM) to obtained spatial distribution and 3D morphological characteristics of residual bubbles in mold flux under different basicity of liquid slag, different temperatures, and different holding times. The results indicate that as basicity of slag increases from 0.52 to 1.03, temperature increases from 1423 to 1573 K, the viscosity of slag decreases, the floating rate of bubbles increases. In addition, when holding time increases from 10 to 30 s, the bubbles floating distance increases, and the volume fraction and average equivalent sphere diameter of the bubbles solidified in the mold flux gradually decreases. In one word, increasing the basicity, temperature, and holding time leading to an increase in the removal rate of bubbles especially for the large. These findings of bubbles escape behavior provide valuable insights into optimizing low basicity mold flux for high-Mn high-Al steels.
During the continuous casting process of high-Mn high-Al steels, various types of gases such as Ar need to escape through the top of the mold. In which, the behavior of bubbles traversing the liquid slag serves as a restrictive link, closely associated with viscosity and the thickness of liquid slag. In contrast to two-dimensional surface observation, three-dimensional (3D) analysis method can offer a more intuitive, accurate, and comprehensive information. Therefore, this study employs a 3D X-ray microscope (3D-XRM) to obtained spatial distribution and 3D morphological characteristics of residual bubbles in mold flux under different basicity of liquid slag, different temperatures, and different holding times. The results indicate that as basicity of slag increases from 0.52 to 1.03, temperature increases from 1423 to 1573 K, the viscosity of slag decreases, the floating rate of bubbles increases. In addition, when holding time increases from 10 to 30 s, the bubbles floating distance increases, and the volume fraction and average equivalent sphere diameter of the bubbles solidified in the mold flux gradually decreases. In one word, increasing the basicity, temperature, and holding time leading to an increase in the removal rate of bubbles especially for the large. These findings of bubbles escape behavior provide valuable insights into optimizing low basicity mold flux for high-Mn high-Al steels.
2025, vol. 32, no. 1, pp.
111-118.
https://doi.org/10.1007/s12613-024-2931-7
Abstract:
Densely distributed coherent nanoparticles (DCN) in steel matrix can enhance the work-hardening ability and ductility of steel simultaneously. All the routes to this end can be generally classified into the liquid–solid route and the solid–solid route. However, the formation of DCN structures in steel requires long processes and complex steps. So far, obtaining steel with coherent particle enhancement in a short time remains a bottleneck, and some necessary steps remain unavoidable. Here, we show a high-efficiency liquid-phase refining process reinforced by a dynamic magnetic field. Ti–Y–Mn–O particles had an average size of around (3.53 ± 1.21) nm and can be obtained in just around 180 s. These small nanoparticles were coherent with the matrix, implying no accumulated dislocations between the particles and the steel matrix. Our findings have a potential application for improving material machining capacity, creep resistance, and radiation resistance.
Densely distributed coherent nanoparticles (DCN) in steel matrix can enhance the work-hardening ability and ductility of steel simultaneously. All the routes to this end can be generally classified into the liquid–solid route and the solid–solid route. However, the formation of DCN structures in steel requires long processes and complex steps. So far, obtaining steel with coherent particle enhancement in a short time remains a bottleneck, and some necessary steps remain unavoidable. Here, we show a high-efficiency liquid-phase refining process reinforced by a dynamic magnetic field. Ti–Y–Mn–O particles had an average size of around (3.53 ± 1.21) nm and can be obtained in just around 180 s. These small nanoparticles were coherent with the matrix, implying no accumulated dislocations between the particles and the steel matrix. Our findings have a potential application for improving material machining capacity, creep resistance, and radiation resistance.
2025, vol. 32, no. 1, pp.
119-126.
https://doi.org/10.1007/s12613-024-2860-5
Abstract:
The atmospheric corrosion monitoring (ACM) technique has been widely employed to track the real-time corrosion behavior of metal materials. However, limited studies have applied ACM to the corrosion protection properties of organic coatings. This study compared a bare epoxy coating with one containing zinc phosphate corrosion inhibitors, both applied on ACM sensors, to observe their corrosion protection properties over time. Coatings with artificial damage via scratches were exposed to immersion and alternating dry and wet environments, which allowed for monitoring galvanic corrosion currents in real-time. Throughout the corrosion tests, the ACM currents of the zinc phosphate/epoxy coating were considerably lower than those of the blank epoxy coating. The trend in ACM current variations closely matched the results obtained from regular electrochemical tests and surface analysis. This alignment highlights the potential of the ACM technique in evaluating the corrosion protection capabilities of organic coatings. Compared with the blank epoxy coating, the zinc phosphate/epoxy coating showed much-decreased ACM current values that confirmed the effective inhibition of zinc phosphate against steel corrosion beneath the damaged coating.
The atmospheric corrosion monitoring (ACM) technique has been widely employed to track the real-time corrosion behavior of metal materials. However, limited studies have applied ACM to the corrosion protection properties of organic coatings. This study compared a bare epoxy coating with one containing zinc phosphate corrosion inhibitors, both applied on ACM sensors, to observe their corrosion protection properties over time. Coatings with artificial damage via scratches were exposed to immersion and alternating dry and wet environments, which allowed for monitoring galvanic corrosion currents in real-time. Throughout the corrosion tests, the ACM currents of the zinc phosphate/epoxy coating were considerably lower than those of the blank epoxy coating. The trend in ACM current variations closely matched the results obtained from regular electrochemical tests and surface analysis. This alignment highlights the potential of the ACM technique in evaluating the corrosion protection capabilities of organic coatings. Compared with the blank epoxy coating, the zinc phosphate/epoxy coating showed much-decreased ACM current values that confirmed the effective inhibition of zinc phosphate against steel corrosion beneath the damaged coating.
2025, vol. 32, no. 1, pp.
127-135.
https://doi.org/10.1007/s12613-024-2933-5
Abstract:
This study investigated the microstructure and hydrogen absorption properties of a rare-earth high-entropy alloy (HEA), YGdTbDyHo. Results indicated that the YGdTbDyHo alloy had a microstructure of equiaxed grains, with the alloy elements distributed homogeneously. Upon hydrogen absorption, the phase structure of the HEA changed from a solid solution with an hexagonal-close-packed (HCP) structure to a high-entropy hydride with an faced-centered-cubic (FCC) structure without any secondary phase precipitated. The alloy demonstrated a maximum hydrogen storage capacity of 2.33 H/M (hydrogen atom/metal atom) at 723 K, with an enthalpy change (ΔH) of −141.09 kJ·mol−1 and an entropy change (ΔS) of −119.14 J·mol−1·K−1. The kinetic mechanism of hydrogen absorption was hydride nucleation and growth, with an apparent activation energy (Ea) of 20.90 kJ·mol−1. Without any activation, the YGdTbDyHo alloy could absorb hydrogen quickly (180 s at 923 K) with nearly no incubation period observed. The reason for the obtained value of 2.33 H/M was that the hydrogen atoms occupied both tetrahedral and octahedral interstices. These results demonstrate the potential application of HEAs as a high-capacity hydrogen storage material with a large H/M ratio, which can be used in the deuterium storage field.
This study investigated the microstructure and hydrogen absorption properties of a rare-earth high-entropy alloy (HEA), YGdTbDyHo. Results indicated that the YGdTbDyHo alloy had a microstructure of equiaxed grains, with the alloy elements distributed homogeneously. Upon hydrogen absorption, the phase structure of the HEA changed from a solid solution with an hexagonal-close-packed (HCP) structure to a high-entropy hydride with an faced-centered-cubic (FCC) structure without any secondary phase precipitated. The alloy demonstrated a maximum hydrogen storage capacity of 2.33 H/M (hydrogen atom/metal atom) at 723 K, with an enthalpy change (ΔH) of −141.09 kJ·mol−1 and an entropy change (ΔS) of −119.14 J·mol−1·K−1. The kinetic mechanism of hydrogen absorption was hydride nucleation and growth, with an apparent activation energy (Ea) of 20.90 kJ·mol−1. Without any activation, the YGdTbDyHo alloy could absorb hydrogen quickly (180 s at 923 K) with nearly no incubation period observed. The reason for the obtained value of 2.33 H/M was that the hydrogen atoms occupied both tetrahedral and octahedral interstices. These results demonstrate the potential application of HEAs as a high-capacity hydrogen storage material with a large H/M ratio, which can be used in the deuterium storage field.
2025, vol. 32, no. 1, pp.
136-146.
https://doi.org/10.1007/s12613-024-2918-4
Abstract:
Microstructure, texture, and mechanical properties of the extruded Mg–2.49Nd–1.82Gd–0.2Zn–0.2Zr alloy were investigated at different extrusion temperatures (260 and 320°C), extrusion ratios (10:1, 15:1, and 30:1), and extrusion speeds (3 and 6 mm/s). The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy, and the second phase showed streamline distribution along the extrusion direction (ED). With extrusion temperature increased from 260 to 320°C, the microstructure, texture, and mechanical properties of alloys changed slightly. The dynamic recrystallization (DRX) degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1, and the strength gradually decreased but elongation (EL) increased. With the extrusion speed increased from 3 to 6 mm/s, the grain sizes and DRX degree increased significantly, and the samples presented the typical <\begin{document}$2\bar{1}\bar{1}1 $\end{document} \begin{document}$ 11\bar{2}3 $\end{document}
Microstructure, texture, and mechanical properties of the extruded Mg–2.49Nd–1.82Gd–0.2Zn–0.2Zr alloy were investigated at different extrusion temperatures (260 and 320°C), extrusion ratios (10:1, 15:1, and 30:1), and extrusion speeds (3 and 6 mm/s). The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy, and the second phase showed streamline distribution along the extrusion direction (ED). With extrusion temperature increased from 260 to 320°C, the microstructure, texture, and mechanical properties of alloys changed slightly. The dynamic recrystallization (DRX) degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1, and the strength gradually decreased but elongation (EL) increased. With the extrusion speed increased from 3 to 6 mm/s, the grain sizes and DRX degree increased significantly, and the samples presented the typical <
2025, vol. 32, no. 1, pp.
147-153.
https://doi.org/10.1007/s12613-024-2882-z
Abstract:
High pressure die casting (HPDC) AlSi10MnMg alloy castings are widely used in the automobile industry. Mg can optimize the mechanical properties of castings through heat treatment, while the release of thermal stress arouses the deformation of large integrated die-castings. Herein, the development of non-heat treatment Al alloys is becoming the hot topic. In addition, HPDC contains externally solidified crystals (ESCs), which are detrimental to the mechanical properties of castings. To achieve high strength and toughness of non-heat treatment die-casting Al–Si alloy, we used AlSi9Mn alloy as matrix with the introduction of Zr, Ti, Nb, and Ce. Their influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic simulation. Our results reveal that the addition of Ti increased ESCs’ size and porosity, while the introduction of Nb refined ESCs and decreased porosity. Meanwhile, large-sized Al3(Zr,Ti) phases formed and degraded the mechanical properties. Subsequent introduction of Ce resulted in the poisoning effect and reduced mechanical properties.
High pressure die casting (HPDC) AlSi10MnMg alloy castings are widely used in the automobile industry. Mg can optimize the mechanical properties of castings through heat treatment, while the release of thermal stress arouses the deformation of large integrated die-castings. Herein, the development of non-heat treatment Al alloys is becoming the hot topic. In addition, HPDC contains externally solidified crystals (ESCs), which are detrimental to the mechanical properties of castings. To achieve high strength and toughness of non-heat treatment die-casting Al–Si alloy, we used AlSi9Mn alloy as matrix with the introduction of Zr, Ti, Nb, and Ce. Their influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic simulation. Our results reveal that the addition of Ti increased ESCs’ size and porosity, while the introduction of Nb refined ESCs and decreased porosity. Meanwhile, large-sized Al3(Zr,Ti) phases formed and degraded the mechanical properties. Subsequent introduction of Ce resulted in the poisoning effect and reduced mechanical properties.
2025, vol. 32, no. 1, pp.
154-168.
https://doi.org/10.1007/s12613-024-3003-8
Abstract:
The feasibility of manufacturing Ti–6Al–4V samples through a combination of laser-aided additive manufacturing with powder (LAAMp) and wire (LAAMw) was explored. A process study was first conducted to successfully circumvent defects in Ti–6Al–4V deposits for LAAMp and LAAMw, respectively. With the optimized process parameters, robust interfaces were achieved between powder/wire deposits and the forged substrate, as well as between powder and wire deposits. Microstructure characterization results revealed the epitaxial prior β grains in the deposited Ti–6Al–4V, wherein the powder deposit was dominated by a finer α′ microstructure and the wire deposit was characterized by lamellar α phases. The mechanisms of microstructure formation and correlation with mechanical behavior were analyzed and discussed. The mechanical properties of the interfacial samples can meet the requirements of the relevant Aerospace Material Specifications (AMS 6932) even without post heat treatment. No fracture occurred within the interfacial area, further suggesting the robust interface. The findings of this study highlighted the feasibility of combining LAAMp and LAAMw in the direct manufacturing of Ti–6Al–4V parts in accordance with the required dimensional resolution and deposition rate, together with sound strength and ductility balance in the as-built condition.
The feasibility of manufacturing Ti–6Al–4V samples through a combination of laser-aided additive manufacturing with powder (LAAMp) and wire (LAAMw) was explored. A process study was first conducted to successfully circumvent defects in Ti–6Al–4V deposits for LAAMp and LAAMw, respectively. With the optimized process parameters, robust interfaces were achieved between powder/wire deposits and the forged substrate, as well as between powder and wire deposits. Microstructure characterization results revealed the epitaxial prior β grains in the deposited Ti–6Al–4V, wherein the powder deposit was dominated by a finer α′ microstructure and the wire deposit was characterized by lamellar α phases. The mechanisms of microstructure formation and correlation with mechanical behavior were analyzed and discussed. The mechanical properties of the interfacial samples can meet the requirements of the relevant Aerospace Material Specifications (AMS 6932) even without post heat treatment. No fracture occurred within the interfacial area, further suggesting the robust interface. The findings of this study highlighted the feasibility of combining LAAMp and LAAMw in the direct manufacturing of Ti–6Al–4V parts in accordance with the required dimensional resolution and deposition rate, together with sound strength and ductility balance in the as-built condition.
2025, vol. 32, no. 1, pp.
169-181.
https://doi.org/10.1007/s12613-024-2953-1
Abstract:
S and Co co-doped carbon catalysts were prepared via pyrolysis of MOF-71 and thiourea mixtures at 800°C at a mass ratio of MOF-71 to thiourea of 1:0.1 to effectively activate peroxymonosulfate (PMS) for methylene blue (MB) degradation. The effects of two different mixing routes were identified on the MB degradation performance. Particularly, the catalyst obtained by the alcohol solvent evaporation (MOF-AEP) mixing route could degrade 95.60% MB (50 mg/L) within 4 min (degradation rate: K = 0.78 min–1), which was faster than that derived from the direct grinding method (MOF-DGP, 80.97%, K = 0.39 min–1). X-ray photoelectron spectroscopy revealed that the Co–S content of MOF-AEP (43.39at%) was less than that of MOF-DGP (54.73at%), and the proportion of C–S–C in MOF-AEP (13.56at%) was higher than that of MOF-DGP (10.67at%). Density functional theory calculations revealed that the adsorption energy of Co for PMS was −2.94 eV when sulfur was doped as C–S–C on the carbon skeleton, which was higher than that when sulfur was doped next to cobalt in the form of Co–S bond (−2.86 eV). Thus, the C–S–C sites might provide more contributions to activate PMS compared with Co–S. Furthermore, the degradation parameters, including pH and MOF-AEP dosage, were investigated. Finally, radical quenching experiments and electron paramagnetic resonance (EPR) measurements revealed that 1O2 might be the primary catalytic species, whereas · O2− might be the secondary one in degrading MB.
S and Co co-doped carbon catalysts were prepared via pyrolysis of MOF-71 and thiourea mixtures at 800°C at a mass ratio of MOF-71 to thiourea of 1:0.1 to effectively activate peroxymonosulfate (PMS) for methylene blue (MB) degradation. The effects of two different mixing routes were identified on the MB degradation performance. Particularly, the catalyst obtained by the alcohol solvent evaporation (MOF-AEP) mixing route could degrade 95.60% MB (50 mg/L) within 4 min (degradation rate: K = 0.78 min–1), which was faster than that derived from the direct grinding method (MOF-DGP, 80.97%, K = 0.39 min–1). X-ray photoelectron spectroscopy revealed that the Co–S content of MOF-AEP (43.39at%) was less than that of MOF-DGP (54.73at%), and the proportion of C–S–C in MOF-AEP (13.56at%) was higher than that of MOF-DGP (10.67at%). Density functional theory calculations revealed that the adsorption energy of Co for PMS was −2.94 eV when sulfur was doped as C–S–C on the carbon skeleton, which was higher than that when sulfur was doped next to cobalt in the form of Co–S bond (−2.86 eV). Thus, the C–S–C sites might provide more contributions to activate PMS compared with Co–S. Furthermore, the degradation parameters, including pH and MOF-AEP dosage, were investigated. Finally, radical quenching experiments and electron paramagnetic resonance (EPR) measurements revealed that 1O2 might be the primary catalytic species, whereas · O2− might be the secondary one in degrading MB.
2025, vol. 32, no. 1, pp.
182-190.
https://doi.org/10.1007/s12613-024-2912-x
Abstract:
Pt-based nanocatalysts offer excellent prospects for various industries. However, the low loading of Pt with excellent performance for efficient and stable nanocatalysts still presents a considerable challenge. In this study, nanocatalysts with ultralow Pt content, excellent performance, and carbon black as support were prepared through in-situ synthesis. These ~2-nm particles uniformly and stably dispersed on carbon black because of the strong s–p–d orbital hybridizations between carbon black and Pt, which suppressed the agglomeration of Pt ions. This unique structure is beneficial for the hydrogen evolution reaction. The catalysts exhibited remarkable catalytic activity for hydrogen evolution reaction, exhibiting a potential of 100 mV at 100 mA·cm−2, which is comparable to those of commercial Pt/C catalysts. Mass activity (1.61 A/mg) was four times that of a commercial Pt/C catalyst (0.37 A/mg). The ultralow Pt loading (6.84wt%) paves the way for the development of next-generation electrocatalysts.
Pt-based nanocatalysts offer excellent prospects for various industries. However, the low loading of Pt with excellent performance for efficient and stable nanocatalysts still presents a considerable challenge. In this study, nanocatalysts with ultralow Pt content, excellent performance, and carbon black as support were prepared through in-situ synthesis. These ~2-nm particles uniformly and stably dispersed on carbon black because of the strong s–p–d orbital hybridizations between carbon black and Pt, which suppressed the agglomeration of Pt ions. This unique structure is beneficial for the hydrogen evolution reaction. The catalysts exhibited remarkable catalytic activity for hydrogen evolution reaction, exhibiting a potential of 100 mV at 100 mA·cm−2, which is comparable to those of commercial Pt/C catalysts. Mass activity (1.61 A/mg) was four times that of a commercial Pt/C catalyst (0.37 A/mg). The ultralow Pt loading (6.84wt%) paves the way for the development of next-generation electrocatalysts.
2025, vol. 32, no. 1, pp.
191-200.
https://doi.org/10.1007/s12613-024-2890-z
Abstract:
Transition metal sulfides have great potential as anode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacities. However, the inferior intrinsic conductivity and large volume variation during sodiation–desodiation processes seriously affect its high-rate and long-cycle performance, unbeneficial for the application as fast-charging and long-cycling SIBs anode. Herein, the three-dimensional porous Cu1.81S/nitrogen-doped carbon frameworks (Cu1.81S/NC) are synthesized by the simple and facile sol–gel and annealing processes, which can accommodate the volumetric expansion of Cu1.81S nanoparticles and accelerate the transmission of ions and electrons during Na+ insertion/extraction processes, exhibiting the excellent rate capability (250.6 mAh·g−1 at 20.0 A·g−1) and outstanding cycling stability (70% capacity retention for 6000 cycles at 10.0 A·g−1) for SIBs. Moreover, the Na-ion full cells coupled with Na3V2(PO4)3/C cathode also demonstrate the satisfactory reversible specific capacity of 330.5 mAh·g−1 at 5.0 A·g−1 and long-cycle performance with the 86.9% capacity retention at 2.0 A·g−1 after 750 cycles. This work proposes a promising way for the conversion-based metal sulfides for the applications as fast-charging sodium-ion battery anode.
Transition metal sulfides have great potential as anode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacities. However, the inferior intrinsic conductivity and large volume variation during sodiation–desodiation processes seriously affect its high-rate and long-cycle performance, unbeneficial for the application as fast-charging and long-cycling SIBs anode. Herein, the three-dimensional porous Cu1.81S/nitrogen-doped carbon frameworks (Cu1.81S/NC) are synthesized by the simple and facile sol–gel and annealing processes, which can accommodate the volumetric expansion of Cu1.81S nanoparticles and accelerate the transmission of ions and electrons during Na+ insertion/extraction processes, exhibiting the excellent rate capability (250.6 mAh·g−1 at 20.0 A·g−1) and outstanding cycling stability (70% capacity retention for 6000 cycles at 10.0 A·g−1) for SIBs. Moreover, the Na-ion full cells coupled with Na3V2(PO4)3/C cathode also demonstrate the satisfactory reversible specific capacity of 330.5 mAh·g−1 at 5.0 A·g−1 and long-cycle performance with the 86.9% capacity retention at 2.0 A·g−1 after 750 cycles. This work proposes a promising way for the conversion-based metal sulfides for the applications as fast-charging sodium-ion battery anode.
2025, vol. 32, no. 1, pp.
201-213.
https://doi.org/10.1007/s12613-024-2992-7
Abstract:
Delafossite AgFeO2 nanoparticles with a mixture of 2H and 3R phases were successfully fabricated by using a simple co-precipitation method. The resulting precursor was calcined at temperatures of 100, 200, 300, 400, and 500°C to obtain the delafossite AgFeO2 phase. The morphology and microstructure of the prepared AgFeO2 samples were characterized by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), N2 adsorption/desorption, X-ray absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy (XPS) techniques. A three-electrode system was employed to investigate the electrochemical properties of the delafossite AgFeO2 nanoparticles in a 3 M KOH electrolyte. The delafossite AgFeO2 nanoparticles calcined at 100°C (AFO100) exhibited the highest surface area of 28.02 m2∙g−1 and outstanding electrochemical performance with specific capacitances of 229.71 F∙g−1 at a current density of 1 A∙g−1 and 358.32 F∙g−1 at a scan rate of 2 mV∙s−1. This sample also demonstrated the capacitance retention of 82.99% after 1000 charge/discharge cycles, along with superior specific power and specific energy values of 797.46 W∙kg−1 and 72.74 Wh∙kg−1, respectively. These findings indicate that delafossite AgFeO2 has great potential as an electrode material for supercapacitor applications.
Delafossite AgFeO2 nanoparticles with a mixture of 2H and 3R phases were successfully fabricated by using a simple co-precipitation method. The resulting precursor was calcined at temperatures of 100, 200, 300, 400, and 500°C to obtain the delafossite AgFeO2 phase. The morphology and microstructure of the prepared AgFeO2 samples were characterized by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), N2 adsorption/desorption, X-ray absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy (XPS) techniques. A three-electrode system was employed to investigate the electrochemical properties of the delafossite AgFeO2 nanoparticles in a 3 M KOH electrolyte. The delafossite AgFeO2 nanoparticles calcined at 100°C (AFO100) exhibited the highest surface area of 28.02 m2∙g−1 and outstanding electrochemical performance with specific capacitances of 229.71 F∙g−1 at a current density of 1 A∙g−1 and 358.32 F∙g−1 at a scan rate of 2 mV∙s−1. This sample also demonstrated the capacitance retention of 82.99% after 1000 charge/discharge cycles, along with superior specific power and specific energy values of 797.46 W∙kg−1 and 72.74 Wh∙kg−1, respectively. These findings indicate that delafossite AgFeO2 has great potential as an electrode material for supercapacitor applications.
2025, vol. 32, no. 1, pp.
214-220.
https://doi.org/10.1007/s12613-024-2968-7
Abstract:
Nowadays, force sensors play an important role in industrial production, electronic information, medical health, and many other fields. Two-dimensional material-based filed effect transistor (2D-FET) sensors are competitive with nano-level size, lower power consumption, and accurate response. However, few of them has the capability of impulse detection, which is a path function, expressing the cumulative effect of the force on the particle over a period of time. Herein, we fabricated the flexible polymethyl methacrylate (PMMA) gate dielectric MoS2-FET for force and impulse sensor application. We systematically investigated the responses of the sensor to constant force and varying forces, and achieved the conversion factors of the drain current signals (Ids) to the detected impulse (\begin{document}$ \overrightarrow{I} $\end{document}
Nowadays, force sensors play an important role in industrial production, electronic information, medical health, and many other fields. Two-dimensional material-based filed effect transistor (2D-FET) sensors are competitive with nano-level size, lower power consumption, and accurate response. However, few of them has the capability of impulse detection, which is a path function, expressing the cumulative effect of the force on the particle over a period of time. Herein, we fabricated the flexible polymethyl methacrylate (PMMA) gate dielectric MoS2-FET for force and impulse sensor application. We systematically investigated the responses of the sensor to constant force and varying forces, and achieved the conversion factors of the drain current signals (Ids) to the detected impulse (
2025, vol. 32, no. 1, pp.
221-232.
https://doi.org/10.1007/s12613-024-2849-0
Abstract:
Electromagnetic interference, which necessitates the rapid advancement of substances with exceptional capabilities for absorbing electromagnetic waves, is of urgent concern in contemporary society. In this work, CoFe2O4/residual carbon from coal gasification fine slag (CFO/RC) composites were created using a novel hydrothermal method. Various mechanisms for microwave absorption, including conductive loss, natural resonance, interfacial dipole polarization, and magnetic flux loss, are involved in these composites. Consequently, compared with pure residual carbon materials, this composite offers superior capabilities in microwave absorption. At 7.76 GHz, the CFO/RC-2 composite achieves an impressive minimum reflection loss (RLmin) of −43.99 dB with a thickness of 2.44 mm. Moreover, CFO/RC-3 demonstrates an effective absorption bandwidth (EAB) of up to 4.16 GHz, accompanied by a thickness of 1.18 mm. This study revealed the remarkable capability of the composite to diminish electromagnetic waves, providing a new generation method for microwave absorbing materials of superior quality.
Electromagnetic interference, which necessitates the rapid advancement of substances with exceptional capabilities for absorbing electromagnetic waves, is of urgent concern in contemporary society. In this work, CoFe2O4/residual carbon from coal gasification fine slag (CFO/RC) composites were created using a novel hydrothermal method. Various mechanisms for microwave absorption, including conductive loss, natural resonance, interfacial dipole polarization, and magnetic flux loss, are involved in these composites. Consequently, compared with pure residual carbon materials, this composite offers superior capabilities in microwave absorption. At 7.76 GHz, the CFO/RC-2 composite achieves an impressive minimum reflection loss (RLmin) of −43.99 dB with a thickness of 2.44 mm. Moreover, CFO/RC-3 demonstrates an effective absorption bandwidth (EAB) of up to 4.16 GHz, accompanied by a thickness of 1.18 mm. This study revealed the remarkable capability of the composite to diminish electromagnetic waves, providing a new generation method for microwave absorbing materials of superior quality.
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