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2024, vol. 31, no. 12, pp.
2537-2555.
https://doi.org/10.1007/s12613-024-2934-4
Abstract:
Copper, an essential metal for the energy transition, is primarily obtained from chalcopyrite through hydrometallurgical and pyrometallurgical methods. The risks and harmful impacts of these processes pose significant concerns for environmental and human safety, highlighting the need for more efficient and eco-friendly hydrometallurgical methods. This review article emphasizes current processes such as oxidative leaching, bioleaching, and pressure leaching that have demonstrated efficiency in overcoming the complicated chalcopyrite network. Oxidative leaching operates under benign conditions within the leaching media; nevertheless, the introduction of oxidizing agents provides benefits and advantages. Bioleaching, a non-aggressive method, has shown a gradual increase in copper extraction efficiency and has been explored using both primary and secondary sources. Pressure leaching, known for its effectiveness and selectivity in copper extraction, is becoming commercially more viable with increased research investments. This research also provides important data for advancing future research in the field.
Copper, an essential metal for the energy transition, is primarily obtained from chalcopyrite through hydrometallurgical and pyrometallurgical methods. The risks and harmful impacts of these processes pose significant concerns for environmental and human safety, highlighting the need for more efficient and eco-friendly hydrometallurgical methods. This review article emphasizes current processes such as oxidative leaching, bioleaching, and pressure leaching that have demonstrated efficiency in overcoming the complicated chalcopyrite network. Oxidative leaching operates under benign conditions within the leaching media; nevertheless, the introduction of oxidizing agents provides benefits and advantages. Bioleaching, a non-aggressive method, has shown a gradual increase in copper extraction efficiency and has been explored using both primary and secondary sources. Pressure leaching, known for its effectiveness and selectivity in copper extraction, is becoming commercially more viable with increased research investments. This research also provides important data for advancing future research in the field.
2024, vol. 31, no. 12, pp.
2556-2581.
https://doi.org/10.1007/s12613-024-2895-7
Abstract:
Ternary lithium-ion batteries (LIBs), widely used in new energy vehicles and electronic products, are known for their high energy density, wide operating temperature range, and excellent cycling performance. With the rapid development of the battery industry, the recycling of spent ternary LIBs has become a hot topic because of their economic value and environmental concerns. To date, a considerable amount of literature has reported on the recycling of spent ternary LIBs designed to provide an efficient, economical, and environmentally friendly method for battery recycling. This article examines the latest developments in various technologies for recycling spent ternary LIBs in both research and practical production, including pretreatment, pyrometallurgy, hydrometallurgy, pyro-hydrometallurgy, and direct regeneration. Suggestions for addressing challenges based on the benefits and disadvantages of each method are made. Finally, through a comparison of the feasibility and economic benefits of various technologies, the challenges faced during battery recycling are summarized, and future development directions are proposed.
Ternary lithium-ion batteries (LIBs), widely used in new energy vehicles and electronic products, are known for their high energy density, wide operating temperature range, and excellent cycling performance. With the rapid development of the battery industry, the recycling of spent ternary LIBs has become a hot topic because of their economic value and environmental concerns. To date, a considerable amount of literature has reported on the recycling of spent ternary LIBs designed to provide an efficient, economical, and environmentally friendly method for battery recycling. This article examines the latest developments in various technologies for recycling spent ternary LIBs in both research and practical production, including pretreatment, pyrometallurgy, hydrometallurgy, pyro-hydrometallurgy, and direct regeneration. Suggestions for addressing challenges based on the benefits and disadvantages of each method are made. Finally, through a comparison of the feasibility and economic benefits of various technologies, the challenges faced during battery recycling are summarized, and future development directions are proposed.
2024, vol. 31, no. 12, pp.
2582-2606.
https://doi.org/10.1007/s12613-024-2949-x
Abstract:
Safe emplacement of high-level nuclear waste (HLNW) arising from the utilization of nuclear power is a frequently encountered and considerably challenging issue. The widely accepted and feasible approach for the permanent disposal of HLNW involves housing it in a corrosion-resistant container and subsequently burying it deep in a geologic repository. The focus lies on ensuring the durability and integrity of the container in this process. This review introduces various techniques and strategies employed in controlling the corrosion of used fuel containers (UFCs) using copper (Cu) as corrosion barrier in the context of deep geological disposal. Overall, these corrosion prevention techniques and methods have been effectively implemented and employed to successfully mitigate the corrosion challenges encountered during the permanent disposal of Cu containers (e.g., corrosion mechanisms and corrosion parameters) in deep geologic repositories. The primary objective of this review is to provide an extensive examination of the alteration in the corrosion environment encountered by the UFCs when subjected to deep geologic repository conditions and focusing on addressing the potential corrosion scenarios.
Safe emplacement of high-level nuclear waste (HLNW) arising from the utilization of nuclear power is a frequently encountered and considerably challenging issue. The widely accepted and feasible approach for the permanent disposal of HLNW involves housing it in a corrosion-resistant container and subsequently burying it deep in a geologic repository. The focus lies on ensuring the durability and integrity of the container in this process. This review introduces various techniques and strategies employed in controlling the corrosion of used fuel containers (UFCs) using copper (Cu) as corrosion barrier in the context of deep geological disposal. Overall, these corrosion prevention techniques and methods have been effectively implemented and employed to successfully mitigate the corrosion challenges encountered during the permanent disposal of Cu containers (e.g., corrosion mechanisms and corrosion parameters) in deep geologic repositories. The primary objective of this review is to provide an extensive examination of the alteration in the corrosion environment encountered by the UFCs when subjected to deep geologic repository conditions and focusing on addressing the potential corrosion scenarios.
2024, vol. 31, no. 12, pp.
2607-2626.
https://doi.org/10.1007/s12613-024-2960-2
Abstract:
The urgent need for integrated molding and sintering across various industries has inspired the development of additive manufacturing (AM) ceramics. Among the different AM technologies, direct laser additive manufacturing (DLAM) stands out as a group of highly promising technology for flexibly manufacturing ceramics without molds and adhesives in a single step. Over the last decade, significant and encouraging progress has been accomplished in DLAM of high-performance ceramics, including Al2O3, ZrO2, Al2O3/ZrO2, SiC, and others. However, high-performance ceramics fabricated by DLAM face challenges such as formation of pores and cracks and resultant low mechanical properties, hindering their practical application in high-end equipment. Further improvements are necessary before they can be widely adopted. Methods such as field-assisted techniques and post-processing can be employed to address these challenges, but a more systematic review is needed. This work aims to critically review the advancements in direct selective laser sintering/melting (SLS/SLM) and laser directed energy deposition (LDED) for various ceramic material systems. Additionally, it provides an overview of the current challenges, future research opportunities, and potential applications associated with DLAM of high-performance ceramics.
The urgent need for integrated molding and sintering across various industries has inspired the development of additive manufacturing (AM) ceramics. Among the different AM technologies, direct laser additive manufacturing (DLAM) stands out as a group of highly promising technology for flexibly manufacturing ceramics without molds and adhesives in a single step. Over the last decade, significant and encouraging progress has been accomplished in DLAM of high-performance ceramics, including Al2O3, ZrO2, Al2O3/ZrO2, SiC, and others. However, high-performance ceramics fabricated by DLAM face challenges such as formation of pores and cracks and resultant low mechanical properties, hindering their practical application in high-end equipment. Further improvements are necessary before they can be widely adopted. Methods such as field-assisted techniques and post-processing can be employed to address these challenges, but a more systematic review is needed. This work aims to critically review the advancements in direct selective laser sintering/melting (SLS/SLM) and laser directed energy deposition (LDED) for various ceramic material systems. Additionally, it provides an overview of the current challenges, future research opportunities, and potential applications associated with DLAM of high-performance ceramics.
2024, vol. 31, no. 12, pp.
2627-2644.
https://doi.org/10.1007/s12613-024-2946-0
Abstract:
In the realm of proton exchange membrane fuel cells (PEMFCs), the bipolar plates (BPs) are indispensable and serve pivotal roles in distributing reactant gases, collecting current, facilitating product water removal, and cooling the stack. Metal BPs, characterized by outstanding manufacturability, cost-effectiveness, higher power density, and mechanical strength, are emerging as viable alternatives to traditional graphite BPs. The foremost challenge for metal BPs lies in enhancing their corrosion resistance and conductivity under acidic conditions, necessitating the application of various coatings on their surfaces to ensure superior performance. This review summarizes and compares recent advancements in the research of eight distinct types of coatings for BPs in PEMFCs, including noble metal, carbide, nitride, and amorphous carbon (a-C)/metal compound composite coatings. The various challenges encountered in the manufacturing and future application of these coatings are also delineated.
In the realm of proton exchange membrane fuel cells (PEMFCs), the bipolar plates (BPs) are indispensable and serve pivotal roles in distributing reactant gases, collecting current, facilitating product water removal, and cooling the stack. Metal BPs, characterized by outstanding manufacturability, cost-effectiveness, higher power density, and mechanical strength, are emerging as viable alternatives to traditional graphite BPs. The foremost challenge for metal BPs lies in enhancing their corrosion resistance and conductivity under acidic conditions, necessitating the application of various coatings on their surfaces to ensure superior performance. This review summarizes and compares recent advancements in the research of eight distinct types of coatings for BPs in PEMFCs, including noble metal, carbide, nitride, and amorphous carbon (a-C)/metal compound composite coatings. The various challenges encountered in the manufacturing and future application of these coatings are also delineated.
2024, vol. 31, no. 12, pp.
2645-2656.
https://doi.org/10.1007/s12613-024-2835-6
Abstract:
To conduct extensive research on the application of ionic liquids as collectors in mineral flotation, ethanol (EtOH) was used as a solvent to dissolve hydrophobic ionic liquids (ILs) to simplify the reagent regime. Interesting phenomena were observed in which EtOH exerted different effects on the flotation efficiency of two ILs with similar structures. When EtOH was used to dissolve 1-dodecyl-3-methylimidazolium chloride (C12[mim]Cl) and as a collector for pure quartz flotation tests at a concentration of 1 × 10−5 mol·L−1, quartz recovery increased from 23.77% to 77.91% compared with ILs dissolved in water. However, quartz recovery of 1-dodecyl-3-methylimidazolium hexafluorophosphate (C12[mim]PF6) decreased from 60.45% to 24.52% under the same conditions. The conditional experiments under 1 × 10−5 mol·L−1 ILs for EtOH concentration and under 2vol% EtOH for ILs concentration confirmed this difference. After being affected by EtOH, the mixed ore flotation tests of quartz and hematite showed a decrease in the hematite concentrate grade and recovery for the C12[mim]Cl collector, whereas the hematite concentrate grade and recovery for the C12[mim]PF6 collector increased. On the basis of these differences and observations of flotation foam, two-phase bubble observation tests were carried out. The EtOH promoted the foam height of two ILs during aeration. It accelerated static froth defoaming after aeration stopped, and the foam of C12[mim]PF6 defoaming especially quickly. In the discussion of flotation tests and foam observation, an attempt was made to explain the reasons and mechanisms behind the diverse phenomena using the dynamic surface tension effect and solvation effect results from EtOH. The solvation effect was verified through Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and Zeta potential tests. Although EtOH affects the adsorption of ILs on the ore surface during flotation negatively, it holds an positive value of inhibiting foam merging during flotation aeration and accelerating the defoaming of static foam. And induce more robust secondary enrichment in the mixed ore flotation of the C12[mim]PF6 collector, facilitating effective mixed ore separation even under inhibitor-free conditions.
To conduct extensive research on the application of ionic liquids as collectors in mineral flotation, ethanol (EtOH) was used as a solvent to dissolve hydrophobic ionic liquids (ILs) to simplify the reagent regime. Interesting phenomena were observed in which EtOH exerted different effects on the flotation efficiency of two ILs with similar structures. When EtOH was used to dissolve 1-dodecyl-3-methylimidazolium chloride (C12[mim]Cl) and as a collector for pure quartz flotation tests at a concentration of 1 × 10−5 mol·L−1, quartz recovery increased from 23.77% to 77.91% compared with ILs dissolved in water. However, quartz recovery of 1-dodecyl-3-methylimidazolium hexafluorophosphate (C12[mim]PF6) decreased from 60.45% to 24.52% under the same conditions. The conditional experiments under 1 × 10−5 mol·L−1 ILs for EtOH concentration and under 2vol% EtOH for ILs concentration confirmed this difference. After being affected by EtOH, the mixed ore flotation tests of quartz and hematite showed a decrease in the hematite concentrate grade and recovery for the C12[mim]Cl collector, whereas the hematite concentrate grade and recovery for the C12[mim]PF6 collector increased. On the basis of these differences and observations of flotation foam, two-phase bubble observation tests were carried out. The EtOH promoted the foam height of two ILs during aeration. It accelerated static froth defoaming after aeration stopped, and the foam of C12[mim]PF6 defoaming especially quickly. In the discussion of flotation tests and foam observation, an attempt was made to explain the reasons and mechanisms behind the diverse phenomena using the dynamic surface tension effect and solvation effect results from EtOH. The solvation effect was verified through Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and Zeta potential tests. Although EtOH affects the adsorption of ILs on the ore surface during flotation negatively, it holds an positive value of inhibiting foam merging during flotation aeration and accelerating the defoaming of static foam. And induce more robust secondary enrichment in the mixed ore flotation of the C12[mim]PF6 collector, facilitating effective mixed ore separation even under inhibitor-free conditions.
2024, vol. 31, no. 12, pp.
2657-2669.
https://doi.org/10.1007/s12613-024-2950-4
Abstract:
Accurate prediction of molten steel temperature in the ladle furnace (LF) refining process has an important influence on the quality of molten steel and the control of steelmaking cost. Extensive research on establishing models to predict molten steel temperature has been conducted. However, most researchers focus solely on improving the accuracy of the model, neglecting its explainability. The present study aims to develop a high-precision and explainable model with improved reliability and transparency. The eXtreme gradient boosting (XGBoost) and light gradient boosting machine (LGBM) were utilized, along with bayesian optimization and grey wolf optimization (GWO), to establish the prediction model. Different performance evaluation metrics and graphical representations were applied to compare the optimal XGBoost and LGBM models obtained through varying hyperparameter optimization methods with the other models. The findings indicated that the GWO-LGBM model outperformed other methods in predicting molten steel temperature, with a high prediction accuracy of 89.35% within the error range of ±5°C. The model’s learning/decision process was revealed, and the influence degree of different variables on the molten steel temperature was clarified using the tree structure visualization and SHapley Additive exPlanations (SHAP) analysis. Consequently, the explainability of the optimal GWO-LGBM model was enhanced, providing reliable support for prediction results.
Accurate prediction of molten steel temperature in the ladle furnace (LF) refining process has an important influence on the quality of molten steel and the control of steelmaking cost. Extensive research on establishing models to predict molten steel temperature has been conducted. However, most researchers focus solely on improving the accuracy of the model, neglecting its explainability. The present study aims to develop a high-precision and explainable model with improved reliability and transparency. The eXtreme gradient boosting (XGBoost) and light gradient boosting machine (LGBM) were utilized, along with bayesian optimization and grey wolf optimization (GWO), to establish the prediction model. Different performance evaluation metrics and graphical representations were applied to compare the optimal XGBoost and LGBM models obtained through varying hyperparameter optimization methods with the other models. The findings indicated that the GWO-LGBM model outperformed other methods in predicting molten steel temperature, with a high prediction accuracy of 89.35% within the error range of ±5°C. The model’s learning/decision process was revealed, and the influence degree of different variables on the molten steel temperature was clarified using the tree structure visualization and SHapley Additive exPlanations (SHAP) analysis. Consequently, the explainability of the optimal GWO-LGBM model was enhanced, providing reliable support for prediction results.
2024, vol. 31, no. 12, pp.
2670-2680.
https://doi.org/10.1007/s12613-024-2867-y
Abstract:
The elemental distribution and microstructure near the surface of high-Mn/Al austenitic low-density steel were investigated after isothermal holding at temperatures of 900–1200°C in different atmospheres, including air, N2, and N2 + CO2. No ferrite was formed near the surface of the experimental steel during isothermal holding at 900 and 1000°C in air, while ferrite was formed near the steel surface at holding temperatures of 1100 and 1200°C. The ferrite fraction was larger at 1200°C because more C and Mn diffused to the surface, exuded from the steel, and then reacted with N and O to form oxidation products. The thickness of the compound scale increased owing to the higher diffusion rate at higher temperatures. In addition, after isothermal holding at 1100°C in N2, the Al content near the surface slightly decreased, while the C and Mn contents did not change. Therefore, no ferrite was formed near the surface. However, the near-surface C and Al contents decreased after holding at 1100°C in the N2 + CO2 mixed atmosphere, resulting in the formation of a small amount of ferrite. The compound scale was thickest in N2, followed by the N2 + CO2 mixed atmosphere, and thinnest in air. Overall, the element loss and ferrite fraction were largest after holding in air at the same temperature. The differences in element loss and ferrite fraction between in N2 and N2 + CO2 atmospheres were small, but the compound scale formed in N2 was significantly thicker. According to these results, N2 + CO2 is the ideal heating atmosphere for the industrial production of high-Mn/Al austenitic low-density steel.
The elemental distribution and microstructure near the surface of high-Mn/Al austenitic low-density steel were investigated after isothermal holding at temperatures of 900–1200°C in different atmospheres, including air, N2, and N2 + CO2. No ferrite was formed near the surface of the experimental steel during isothermal holding at 900 and 1000°C in air, while ferrite was formed near the steel surface at holding temperatures of 1100 and 1200°C. The ferrite fraction was larger at 1200°C because more C and Mn diffused to the surface, exuded from the steel, and then reacted with N and O to form oxidation products. The thickness of the compound scale increased owing to the higher diffusion rate at higher temperatures. In addition, after isothermal holding at 1100°C in N2, the Al content near the surface slightly decreased, while the C and Mn contents did not change. Therefore, no ferrite was formed near the surface. However, the near-surface C and Al contents decreased after holding at 1100°C in the N2 + CO2 mixed atmosphere, resulting in the formation of a small amount of ferrite. The compound scale was thickest in N2, followed by the N2 + CO2 mixed atmosphere, and thinnest in air. Overall, the element loss and ferrite fraction were largest after holding in air at the same temperature. The differences in element loss and ferrite fraction between in N2 and N2 + CO2 atmospheres were small, but the compound scale formed in N2 was significantly thicker. According to these results, N2 + CO2 is the ideal heating atmosphere for the industrial production of high-Mn/Al austenitic low-density steel.
2024, vol. 31, no. 12, pp.
2681-2691.
https://doi.org/10.1007/s12613-024-2894-8
Abstract:
Microstructures determine mechanical properties of steels, but in actual steel product process it is difficult to accurately control the microstructure to meet the requirements. General microstructure characterization methods are time consuming and results are not representative for overall quality level as only a fraction of steel sample was selected to be examined. In this paper, a macro and micro coupled 3D model was developed for nondestructively characterization of steel microstructures. For electromagnetic signals analysis, the relative permeability value computed by the micro cellular model can be used in the macro electromagnetic sensor model. The effects of different microstructure components on the relative permeability of duplex stainless steel (grain size, phase fraction, and phase distribution) were discussed. The output inductance of an electromagnetic sensor was determined by relative permeability values and can be validated experimentally. The findings indicate that the inductance value of an electromagnetic sensor at low frequency can distinguish different microstructures. This method can be applied to real-time on-line characterize steel microstructures in process of steel rolling.
Microstructures determine mechanical properties of steels, but in actual steel product process it is difficult to accurately control the microstructure to meet the requirements. General microstructure characterization methods are time consuming and results are not representative for overall quality level as only a fraction of steel sample was selected to be examined. In this paper, a macro and micro coupled 3D model was developed for nondestructively characterization of steel microstructures. For electromagnetic signals analysis, the relative permeability value computed by the micro cellular model can be used in the macro electromagnetic sensor model. The effects of different microstructure components on the relative permeability of duplex stainless steel (grain size, phase fraction, and phase distribution) were discussed. The output inductance of an electromagnetic sensor was determined by relative permeability values and can be validated experimentally. The findings indicate that the inductance value of an electromagnetic sensor at low frequency can distinguish different microstructures. This method can be applied to real-time on-line characterize steel microstructures in process of steel rolling.
2024, vol. 31, no. 12, pp.
2692-2705.
https://doi.org/10.1007/s12613-024-2902-z
Abstract:
FeCoCrNiMox composite powders were prepared using the mechanical alloying technique and made into high-entropy alloy (HEA) coatings with the face-centered cubic phase using plasma spraying to address the element segregation problem in HEAs and prepare uniform HEA coatings. Scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry were employed to characterize these coatings’ microstructure and phase composition. The hardness, elastic modulus, and fracture toughness of coatings were tested, and the corrosion resistance was analyzed in simulated seawater. Results show that the hardness of the coating is HV0.1 606.15, the modulus of elasticity is 128.42 GPa, and the fracture toughness is 43.98 MPa·m1/2. The corrosion potential of the coating in 3.5wt% NaCl solution is –0.49 V, and the corrosion current density is 1.2 × 10−6 A/cm2. The electrochemical system comprises three parts: the electrolyte, the adsorption and metallic oxide films produced during immersion, and the FeCoNiCrMo HEA coating. Over increasingly long periods, the corrosion reaction rate increases first and then decreases, the corrosion product film comprising metal oxides reaches a dynamic balance between formation and dissolution, and the internal reaction of the coating declines.
FeCoCrNiMox composite powders were prepared using the mechanical alloying technique and made into high-entropy alloy (HEA) coatings with the face-centered cubic phase using plasma spraying to address the element segregation problem in HEAs and prepare uniform HEA coatings. Scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry were employed to characterize these coatings’ microstructure and phase composition. The hardness, elastic modulus, and fracture toughness of coatings were tested, and the corrosion resistance was analyzed in simulated seawater. Results show that the hardness of the coating is HV0.1 606.15, the modulus of elasticity is 128.42 GPa, and the fracture toughness is 43.98 MPa·m1/2. The corrosion potential of the coating in 3.5wt% NaCl solution is –0.49 V, and the corrosion current density is 1.2 × 10−6 A/cm2. The electrochemical system comprises three parts: the electrolyte, the adsorption and metallic oxide films produced during immersion, and the FeCoNiCrMo HEA coating. Over increasingly long periods, the corrosion reaction rate increases first and then decreases, the corrosion product film comprising metal oxides reaches a dynamic balance between formation and dissolution, and the internal reaction of the coating declines.
2024, vol. 31, no. 12, pp.
2706-2713.
https://doi.org/10.1007/s12613-024-2970-0
Abstract:
The control of oxygen is paramount in achieving high-performance titanium (Ti) parts by powder metallurgy such as metal injection molding (MIM). In this study, we purposely selected the Ti and Ti–6Al–4V powders as the reference materials since these two are the most representative Ti materials in the industry. Herein, hydride–dehydride (HDH) Ti powders were pre-oxidized to examine the effect of oxygen variation on the characteristics of oxide layer on the particle surface and its resultant color feature. The results indicate that the thickness and Ti oxide level (Ti0 → Ti4+) of the oxide layer on the HDH Ti powders increased as the oxygen content increased, leading to the transition of color appearance from grey, brown to blue. This work aids in the powder feedstock selection at the initial stage in powder metallurgy. In addition, the development of oxygen content was comprehensively studied during the MIM process using the gas-atomized (GA) Ti–6Al–4V powders. Particularly, the oxygen variation in the form of oxide layer, the change of oxygen content in the powders, and the relevant parts were investigated during the processes of kneading, injection, debinding, and sintering. The oxygen variation was mainly concentrated in the sintering stage, and the content increased with the increase of sintering temperature. The variation of oxygen content during the MIM process demonstrates the crucial role of powder feedstock and sintering stage in controlling oxygen content. This work provides a piece of valuable information on oxygen detecting, control, and manipulation for the powder and processing in the industry of Ti and its alloys by powder metallurgy.
The control of oxygen is paramount in achieving high-performance titanium (Ti) parts by powder metallurgy such as metal injection molding (MIM). In this study, we purposely selected the Ti and Ti–6Al–4V powders as the reference materials since these two are the most representative Ti materials in the industry. Herein, hydride–dehydride (HDH) Ti powders were pre-oxidized to examine the effect of oxygen variation on the characteristics of oxide layer on the particle surface and its resultant color feature. The results indicate that the thickness and Ti oxide level (Ti0 → Ti4+) of the oxide layer on the HDH Ti powders increased as the oxygen content increased, leading to the transition of color appearance from grey, brown to blue. This work aids in the powder feedstock selection at the initial stage in powder metallurgy. In addition, the development of oxygen content was comprehensively studied during the MIM process using the gas-atomized (GA) Ti–6Al–4V powders. Particularly, the oxygen variation in the form of oxide layer, the change of oxygen content in the powders, and the relevant parts were investigated during the processes of kneading, injection, debinding, and sintering. The oxygen variation was mainly concentrated in the sintering stage, and the content increased with the increase of sintering temperature. The variation of oxygen content during the MIM process demonstrates the crucial role of powder feedstock and sintering stage in controlling oxygen content. This work provides a piece of valuable information on oxygen detecting, control, and manipulation for the powder and processing in the industry of Ti and its alloys by powder metallurgy.
2024, vol. 31, no. 12, pp.
2714-2726.
https://doi.org/10.1007/s12613-024-2980-y
Abstract:
Complex studies of new Mg–Zn–Y–Zr system alloys have been carried out. The content range for the formation of the two-phase structure MgSS (Mg solid solution) + LPSO (long-period stacking ordered) in alloys of the Mg–Zn–Y–Zr system was determined by thermodynamic calculations. The effect of heat treatment regimes on microstructure, mechanical, and corrosion properties was investigated. The fluidity, hot tearing tendency, and ignition temperature of the alloys were determined. The best combination of castability, mechanical, and corrosion properties was found for the Mg–2.4Zn–4Y–0.8Zr alloy. The alloys studied are superior to their industrial counterparts in terms of technological properties, while maintain high corrosion and mechanical properties. The increased level of properties is achieved by a suitable heat treatment regime that provides a complete transformation of the 18R to 14H modification of the LPSO phase.
Complex studies of new Mg–Zn–Y–Zr system alloys have been carried out. The content range for the formation of the two-phase structure MgSS (Mg solid solution) + LPSO (long-period stacking ordered) in alloys of the Mg–Zn–Y–Zr system was determined by thermodynamic calculations. The effect of heat treatment regimes on microstructure, mechanical, and corrosion properties was investigated. The fluidity, hot tearing tendency, and ignition temperature of the alloys were determined. The best combination of castability, mechanical, and corrosion properties was found for the Mg–2.4Zn–4Y–0.8Zr alloy. The alloys studied are superior to their industrial counterparts in terms of technological properties, while maintain high corrosion and mechanical properties. The increased level of properties is achieved by a suitable heat treatment regime that provides a complete transformation of the 18R to 14H modification of the LPSO phase.
2024, vol. 31, no. 12, pp.
2727-2736.
https://doi.org/10.1007/s12613-024-2995-4
Abstract:
The commonly used trial-and-error method of biodegradable Zn alloys is costly and blindness. In this study, based on the self-built database of biodegradable Zn alloys, two machine learning models are established by the first time to predict the ultimate tensile strength (UTS) and immersion corrosion rate (CR) of biodegradable Zn alloys. A real-time visualization interface has been established to design Zn–Mn based alloys; a representative alloy is Zn–0.4Mn–0.4Li–0.05Mg. Through tensile mechanical properties and immersion corrosion rate tests, its UTS reaches 420 MPa, and the prediction error is only 0.95%. CR is 73 μm/a and the prediction error is 5.5%, which elevates 50 MPa grade of UTS and owns appropriate corrosion rate. Finally, influences of the selected features on UTS and CR are discussed in detail. The combined application of UTS and CR model provides a new strategy for synergistically regulating comprehensive properties of biodegradable Zn alloys.
The commonly used trial-and-error method of biodegradable Zn alloys is costly and blindness. In this study, based on the self-built database of biodegradable Zn alloys, two machine learning models are established by the first time to predict the ultimate tensile strength (UTS) and immersion corrosion rate (CR) of biodegradable Zn alloys. A real-time visualization interface has been established to design Zn–Mn based alloys; a representative alloy is Zn–0.4Mn–0.4Li–0.05Mg. Through tensile mechanical properties and immersion corrosion rate tests, its UTS reaches 420 MPa, and the prediction error is only 0.95%. CR is 73 μm/a and the prediction error is 5.5%, which elevates 50 MPa grade of UTS and owns appropriate corrosion rate. Finally, influences of the selected features on UTS and CR are discussed in detail. The combined application of UTS and CR model provides a new strategy for synergistically regulating comprehensive properties of biodegradable Zn alloys.
2024, vol. 31, no. 12, pp.
2737-2748.
https://doi.org/10.1007/s12613-024-2954-0
Abstract:
Iron oxide (Fe2O3) emerges as a highly attractive anode candidate among rapidly expanding energy storage market. Nonetheless, its considerable volume changes during cycling as an electrode material result in a vast reduced battery cycle life. In this work, an approach is pioneered for preparing high-performance Fe2O3 anode materials, by innovatively synthesizing a triple-layer yolk–shell Fe2O3 uniformly coated with a conductive polypyrrole (Ppy) layer (Fe2O3@Ppy-TLY). The uniform polypyrrole coating introduces more reaction sites and adsorption sites, and maintains structure stability through charge-discharge process. In the uses as lithium-ion battery electrodes, Fe2O3@Ppy-TLY demonstrates high reversible specific capacity (maintaining a discharge capacity of 1375.11 mAh·g−1 after 500 cycles at 1 C), exceptional cycling stability (retaining the steady charge-discharge performance at 544.33 mAh·g−1 after 6000 ultrafast charge-discharge cycles at a 10 C current density), and outstanding high current charge-discharge performance (retaining a reversible capacity of 156.75 mAh·g−1 after 10000 cycles at 15 C), thereby exhibiting superior lithium storage performance. This work introduces innovative advancements for Fe2O3 anode design, aiming to enhance its performance in energy storage fields.
Iron oxide (Fe2O3) emerges as a highly attractive anode candidate among rapidly expanding energy storage market. Nonetheless, its considerable volume changes during cycling as an electrode material result in a vast reduced battery cycle life. In this work, an approach is pioneered for preparing high-performance Fe2O3 anode materials, by innovatively synthesizing a triple-layer yolk–shell Fe2O3 uniformly coated with a conductive polypyrrole (Ppy) layer (Fe2O3@Ppy-TLY). The uniform polypyrrole coating introduces more reaction sites and adsorption sites, and maintains structure stability through charge-discharge process. In the uses as lithium-ion battery electrodes, Fe2O3@Ppy-TLY demonstrates high reversible specific capacity (maintaining a discharge capacity of 1375.11 mAh·g−1 after 500 cycles at 1 C), exceptional cycling stability (retaining the steady charge-discharge performance at 544.33 mAh·g−1 after 6000 ultrafast charge-discharge cycles at a 10 C current density), and outstanding high current charge-discharge performance (retaining a reversible capacity of 156.75 mAh·g−1 after 10000 cycles at 15 C), thereby exhibiting superior lithium storage performance. This work introduces innovative advancements for Fe2O3 anode design, aiming to enhance its performance in energy storage fields.
2024, vol. 31, no. 12, pp.
2749-2759.
https://doi.org/10.1007/s12613-024-2875-y
Abstract:
The pervasive adoption of 5th generation mobile communication technology propels electromagnetic wave (EW) absorbents to achieve high-level performance. The heterointerface construction is crucial to the improvement of absorption ability. Herein, a series of ultralight composites with rational heterointerfaces (Co/ZnO@N-doped C/layer-stacked C, MSC) is fabricated by calcination with rational construction of sugarcane and CoZn–zeolitic imidazolate framework (ZIF). The components and structures of as-prepared composites were investigated, and their electromagnetic parameters could be adjusted by the content of CoZn–ZIFs. All composites possess excellent EW absorption performance, especially MSC-3. The optimal minimum reflection loss and effective absorption band of MSC-3 can reach −42 dB and 7.28 GHz at the thickness of only 1.6 mm with 20wt% filler loading. This excellent performance is attributed to the synergistic effect of dielectric loss stemming from the multiple heterointerfaces and magnetic loss induced by magnetic single Co. The sugarcane-derived layer-stacked carbon has formed consecutive conductive networks and has further dissipated the electromagnetic energy through multiple reflection and conduction losses. Moreover, the simulated radar cross section (RCS) technology manifests that MSC-3 possesses outstanding EW attenuation capacity under realistic far-field conditions. This study provides a strategy for building efficient absorbents based on biomass.
The pervasive adoption of 5th generation mobile communication technology propels electromagnetic wave (EW) absorbents to achieve high-level performance. The heterointerface construction is crucial to the improvement of absorption ability. Herein, a series of ultralight composites with rational heterointerfaces (Co/ZnO@N-doped C/layer-stacked C, MSC) is fabricated by calcination with rational construction of sugarcane and CoZn–zeolitic imidazolate framework (ZIF). The components and structures of as-prepared composites were investigated, and their electromagnetic parameters could be adjusted by the content of CoZn–ZIFs. All composites possess excellent EW absorption performance, especially MSC-3. The optimal minimum reflection loss and effective absorption band of MSC-3 can reach −42 dB and 7.28 GHz at the thickness of only 1.6 mm with 20wt% filler loading. This excellent performance is attributed to the synergistic effect of dielectric loss stemming from the multiple heterointerfaces and magnetic loss induced by magnetic single Co. The sugarcane-derived layer-stacked carbon has formed consecutive conductive networks and has further dissipated the electromagnetic energy through multiple reflection and conduction losses. Moreover, the simulated radar cross section (RCS) technology manifests that MSC-3 possesses outstanding EW attenuation capacity under realistic far-field conditions. This study provides a strategy for building efficient absorbents based on biomass.
2024, vol. 31, no. 12, pp.
2760-2769.
https://doi.org/10.1007/s12613-024-2973-x
Abstract:
Silver selenide (Ag2Se) stands out as a promising thermoelectric (TE) material, particularly for applications near room temperatures. This research presents a novel approach for the fabrication of bulk Ag2Se samples at a relatively low temperature (170°C) using the cold sintering process (CSP) with AgNO3 solution as a transient liquid agent. The effect of AgNO3 addition during CSP on the microstructure and TE properties was investigated. The results from phase, composition and microstructure analyses showed that the introduction of AgNO3 solution induced the formation of Ag nano-precipitates within the Ag2Se matrix. Although the nano-precipitates do not affect the phase and crystal structure of orthorhombic β-Ag2Se, they suppressed crystal growth, leading to reduced crystallite sizes. The samples containing Ag nano-precipitates also exhibited high porosity and low bulk density. Consequently, these effects contributed to significantly enhanced electrical conductivity and a slight decrease in the Seebeck coefficient when small Ag concentrations were incorporated. This resulted in an improved average power factor from ~1540 µW·m−1·K−2 for pure Ag2Se to ~1670 µW·m−1·K−2 for Ag2Se with additional Ag precipitates. However, excessive Ag addition had a detrimental effect on the power factor. Furthermore, thermal conductivity was effectively suppressed in Ag2Se fabricated using AgNO3-assisted CSP, attributed to enhanced phonon scattering at crystal interfaces, pores, and Ag nano-precipitates. The highest figure-of-merit (zT) of 0.92 at 300 K was achieved for the Ag2Se with 0.5wt% Ag during CSP fabrication, equivalent to >20% improvement compared to the controlled Ag2Se without extra Ag solution. Thus, the process outlined in this study presents an effective strategy to tailor the microstructure of bulk Ag2Se and enhance its TE performance at room temperature.
Silver selenide (Ag2Se) stands out as a promising thermoelectric (TE) material, particularly for applications near room temperatures. This research presents a novel approach for the fabrication of bulk Ag2Se samples at a relatively low temperature (170°C) using the cold sintering process (CSP) with AgNO3 solution as a transient liquid agent. The effect of AgNO3 addition during CSP on the microstructure and TE properties was investigated. The results from phase, composition and microstructure analyses showed that the introduction of AgNO3 solution induced the formation of Ag nano-precipitates within the Ag2Se matrix. Although the nano-precipitates do not affect the phase and crystal structure of orthorhombic β-Ag2Se, they suppressed crystal growth, leading to reduced crystallite sizes. The samples containing Ag nano-precipitates also exhibited high porosity and low bulk density. Consequently, these effects contributed to significantly enhanced electrical conductivity and a slight decrease in the Seebeck coefficient when small Ag concentrations were incorporated. This resulted in an improved average power factor from ~1540 µW·m−1·K−2 for pure Ag2Se to ~1670 µW·m−1·K−2 for Ag2Se with additional Ag precipitates. However, excessive Ag addition had a detrimental effect on the power factor. Furthermore, thermal conductivity was effectively suppressed in Ag2Se fabricated using AgNO3-assisted CSP, attributed to enhanced phonon scattering at crystal interfaces, pores, and Ag nano-precipitates. The highest figure-of-merit (zT) of 0.92 at 300 K was achieved for the Ag2Se with 0.5wt% Ag during CSP fabrication, equivalent to >20% improvement compared to the controlled Ag2Se without extra Ag solution. Thus, the process outlined in this study presents an effective strategy to tailor the microstructure of bulk Ag2Se and enhance its TE performance at room temperature.
2024, vol. 31, no. 12, pp.
2770-2780.
https://doi.org/10.1007/s12613-024-2858-z
Abstract:
Advanced processes for peroxymonosulfate (PMS)-based oxidation are efficient in eliminating toxic and refractory organic pollutants from sewage. The activation of electron-withdrawing\begin{document}$ {\mathrm{HSO}}_{5}^{-} $\end{document} \begin{document}$ {\text{·}\mathrm{S}\mathrm{O}}_{4}^{-} $\end{document} \begin{document}$ \text{·}\mathrm{O}\mathrm{H} $\end{document} \begin{document}$ {\text{·}\mathrm{O}}_{2}^{-} $\end{document}
Advanced processes for peroxymonosulfate (PMS)-based oxidation are efficient in eliminating toxic and refractory organic pollutants from sewage. The activation of electron-withdrawing
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