Search2024 Vol. 31, No. 2
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2024, vol. 31, no. 2, pp.
217-230.
https://doi.org/10.1007/s12613-023-2753-z
Abstract:
Coal gasification fine slag (FS) is a typical solid waste generated in coal gasification. Its current disposal methods of stockpiling and landfilling have caused serious soil and ecological hazards. Separation recovery and the high-value utilization of residual carbon (RC) in FS are the keys to realizing the win-win situation of the coal chemical industry in terms of economic and environmental benefits. The structural properties, such as pore, surface functional group, and microcrystalline structures, of RC in FS (FS-RC) not only affect the flotation recovery efficiency of FS-RC but also form the basis for the high-value utilization of FS-RC. In this paper, the characteristics of FS-RC in terms of pore structure, surface functional groups, and microcrystalline structure are sorted out in accordance with gasification type and FS particle size. The reasons for the formation of the special structural properties of FS-RC are analyzed, and their influence on the flotation separation and high-value utilization of FS-RC is summarized. Separation methods based on the pore structural characteristics of FS-RC, such as ultrasonic pretreatment–pore-blocking flotation and pore breaking–flocculation flotation, are proposed to be the key development technologies for improving FS-RC recovery in the future. The design of low-cost, low-dose collectors containing polar bonds based on the surface and microcrystalline structures of FS-RC is proposed to be an important breakthrough point for strengthening the flotation efficiency of FS-RC in the future. The high-value utilization of FS should be based on the physicochemical structural properties of FS-RC and should focus on the environmental impact of hazardous elements and the recyclability of chemical waste liquid to establish an environmentally friendly utilization method. This review is of great theoretical importance for the comprehensive understanding of the unique structural properties of FS-RC, the breakthrough of the technological bottleneck in the efficient flotation separation of FS, and the expansion of the field of the high value-added utilization of FS-RC.
Coal gasification fine slag (FS) is a typical solid waste generated in coal gasification. Its current disposal methods of stockpiling and landfilling have caused serious soil and ecological hazards. Separation recovery and the high-value utilization of residual carbon (RC) in FS are the keys to realizing the win-win situation of the coal chemical industry in terms of economic and environmental benefits. The structural properties, such as pore, surface functional group, and microcrystalline structures, of RC in FS (FS-RC) not only affect the flotation recovery efficiency of FS-RC but also form the basis for the high-value utilization of FS-RC. In this paper, the characteristics of FS-RC in terms of pore structure, surface functional groups, and microcrystalline structure are sorted out in accordance with gasification type and FS particle size. The reasons for the formation of the special structural properties of FS-RC are analyzed, and their influence on the flotation separation and high-value utilization of FS-RC is summarized. Separation methods based on the pore structural characteristics of FS-RC, such as ultrasonic pretreatment–pore-blocking flotation and pore breaking–flocculation flotation, are proposed to be the key development technologies for improving FS-RC recovery in the future. The design of low-cost, low-dose collectors containing polar bonds based on the surface and microcrystalline structures of FS-RC is proposed to be an important breakthrough point for strengthening the flotation efficiency of FS-RC in the future. The high-value utilization of FS should be based on the physicochemical structural properties of FS-RC and should focus on the environmental impact of hazardous elements and the recyclability of chemical waste liquid to establish an environmentally friendly utilization method. This review is of great theoretical importance for the comprehensive understanding of the unique structural properties of FS-RC, the breakthrough of the technological bottleneck in the efficient flotation separation of FS, and the expansion of the field of the high value-added utilization of FS-RC.
2024, vol. 31, no. 2, pp.
231-244.
https://doi.org/10.1007/s12613-023-2761-z
Abstract:
Tin(IV) oxide (Sn3O4) is layered tin and exhibits mixed valence states. It has emerged as a highly promising visible-light photocatalyst, attracting considerable attention. This comprehensive review is aimed at providing a detailed overview of the latest advancements in research, applications, advantages, and challenges associated with Sn3O4 photocatalytic nanomaterials. The fundamental concepts and principles of Sn3O4 are introduced. Sn3O4 possesses a unique crystal structure and optoelectronic properties that allow it to absorb visible light efficiently and generate photoexcited charge carriers that drive photocatalytic reactions. Subsequently, strategies for the control and improved performance of Sn3O4 photocatalytic nanomaterials are discussed. Morphology control, ion doping, and heterostructure construction are widely employed in the optimization of the photocatalytic performance of Sn3O4 materials. The effective implementation of these strategies improves the photocatalytic activity and stability of Sn3O4 nanomaterials. Furthermore, the review explores the diverse applications of Sn3O4 photocatalytic nanomaterials in various fields, such as photocatalytic degradation, photocatalytic hydrogen production, photocatalytic reduction of carbon dioxide, solar cells, photocatalytic sterilization, and optoelectronic sensors. The discussion focuses on the potential of Sn3O4-based nanomaterials in these applications, highlighting their unique attributes and functionalities. Finally, the review provides an outlook on the future development directions in the field and offers guidance for the exploration and development of novel and efficient Sn3O4-based nanomaterials. Through the identification of emerging research areas and potential avenues for improvement, this review aims to stimulate further advancements in Sn3O4-based photocatalysis and facilitate the translation of this promising technology into practical applications.
Tin(IV) oxide (Sn3O4) is layered tin and exhibits mixed valence states. It has emerged as a highly promising visible-light photocatalyst, attracting considerable attention. This comprehensive review is aimed at providing a detailed overview of the latest advancements in research, applications, advantages, and challenges associated with Sn3O4 photocatalytic nanomaterials. The fundamental concepts and principles of Sn3O4 are introduced. Sn3O4 possesses a unique crystal structure and optoelectronic properties that allow it to absorb visible light efficiently and generate photoexcited charge carriers that drive photocatalytic reactions. Subsequently, strategies for the control and improved performance of Sn3O4 photocatalytic nanomaterials are discussed. Morphology control, ion doping, and heterostructure construction are widely employed in the optimization of the photocatalytic performance of Sn3O4 materials. The effective implementation of these strategies improves the photocatalytic activity and stability of Sn3O4 nanomaterials. Furthermore, the review explores the diverse applications of Sn3O4 photocatalytic nanomaterials in various fields, such as photocatalytic degradation, photocatalytic hydrogen production, photocatalytic reduction of carbon dioxide, solar cells, photocatalytic sterilization, and optoelectronic sensors. The discussion focuses on the potential of Sn3O4-based nanomaterials in these applications, highlighting their unique attributes and functionalities. Finally, the review provides an outlook on the future development directions in the field and offers guidance for the exploration and development of novel and efficient Sn3O4-based nanomaterials. Through the identification of emerging research areas and potential avenues for improvement, this review aims to stimulate further advancements in Sn3O4-based photocatalysis and facilitate the translation of this promising technology into practical applications.
2024, vol. 31, no. 2, pp.
245-260.
https://doi.org/10.1007/s12613-023-2773-8
Abstract:
Organic contaminants have posed a direct and substantial risk to human wellness and the environment. In recent years, piezoelectric catalysis has evolved as a novel and effective method for decomposing these contaminants. Although piezoelectric materials offer a wide range of options, most related studies thus far have focused on inorganic materials and have paid little attention to organic materials. Organic materials have advantages, such as being lightweight, inexpensive, and easy to process, over inorganic materials. Therefore, this paper provides a comprehensive review of the progress made in the research on piezoelectric catalysis using organic materials, highlighting their catalytic efficiency in addressing various pollutants. In addition, the applications of organic materials in piezoelectric catalysis for water decomposition to produce hydrogen, disinfect bacteria, treat tumors, and reduce carbon dioxide are presented. Finally, future developmental trends regarding the piezoelectric catalytic potential of organic materials are explored.
Organic contaminants have posed a direct and substantial risk to human wellness and the environment. In recent years, piezoelectric catalysis has evolved as a novel and effective method for decomposing these contaminants. Although piezoelectric materials offer a wide range of options, most related studies thus far have focused on inorganic materials and have paid little attention to organic materials. Organic materials have advantages, such as being lightweight, inexpensive, and easy to process, over inorganic materials. Therefore, this paper provides a comprehensive review of the progress made in the research on piezoelectric catalysis using organic materials, highlighting their catalytic efficiency in addressing various pollutants. In addition, the applications of organic materials in piezoelectric catalysis for water decomposition to produce hydrogen, disinfect bacteria, treat tumors, and reduce carbon dioxide are presented. Finally, future developmental trends regarding the piezoelectric catalytic potential of organic materials are explored.
2024, vol. 31, no. 2, pp.
261-267.
https://doi.org/10.1007/s12613-023-2674-x
Abstract:
The efficient separation of chalcopyrite (CuFeS2) and galena (PbS) is essential for optimal resource utilization. However, finding a selective depressant that is environmentally friendly and cost effective remains a challenge. Through various techniques, such as microflotation tests, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) observation, X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy measurements, this study explored the use of ferric ions (Fe3+) as a selective depressant for galena. The results of flotation tests revealed the impressive selective inhibition capabilities of Fe3+ when used alone. Surface analysis showed that Fe3+ significantly reduced the adsorption of isopropyl ethyl thionocarbamate (IPETC) on the galena surface while having a minimal impact on chalcopyrite. Further analysis using SEM, XPS, and Raman spectra revealed that Fe3+ can oxidize lead sulfide to form compact lead sulfate nanoparticles on the galena surface, effectively depressing IPETC adsorption and increasing surface hydrophilicity. These findings provide a promising solution for the efficient and environmentally responsible separation of chalcopyrite and galena.
The efficient separation of chalcopyrite (CuFeS2) and galena (PbS) is essential for optimal resource utilization. However, finding a selective depressant that is environmentally friendly and cost effective remains a challenge. Through various techniques, such as microflotation tests, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) observation, X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy measurements, this study explored the use of ferric ions (Fe3+) as a selective depressant for galena. The results of flotation tests revealed the impressive selective inhibition capabilities of Fe3+ when used alone. Surface analysis showed that Fe3+ significantly reduced the adsorption of isopropyl ethyl thionocarbamate (IPETC) on the galena surface while having a minimal impact on chalcopyrite. Further analysis using SEM, XPS, and Raman spectra revealed that Fe3+ can oxidize lead sulfide to form compact lead sulfate nanoparticles on the galena surface, effectively depressing IPETC adsorption and increasing surface hydrophilicity. These findings provide a promising solution for the efficient and environmentally responsible separation of chalcopyrite and galena.
2024, vol. 31, no. 2, pp.
268-281.
https://doi.org/10.1007/s12613-023-2728-0
Abstract:
The paper proposes a biomass cross-upgrading process that combines hydrothermal carbonization and pyrolysis to produce high-quality blast furnace injection fuel. The results showed that after upgrading, the volatile content of biochar ranged from 16.19% to 45.35%, and the alkali metal content, ash content, and specific surface area were significantly reduced. The optimal route for biochar production is hydrothermal carbonization–pyrolysis (P-HC), resulting in biochar with a higher calorific value, C=C structure, and increased graphitization degree. The apparent activation energy (E) of the sample ranges from 199.1 to 324.8 kJ/mol, with P-HC having an E of 277.8 kJ/mol, lower than that of raw biomass, primary biochar, and anthracite. This makes P-HC more suitable for blast furnace injection fuel. Additionally, the paper proposes a path for P-HC injection in blast furnaces and calculates potential environmental benefits. P-HC offers the highest potential for carbon emission reduction, capable of reducing emissions by 96.04 kg/t when replacing 40wt% coal injection.
The paper proposes a biomass cross-upgrading process that combines hydrothermal carbonization and pyrolysis to produce high-quality blast furnace injection fuel. The results showed that after upgrading, the volatile content of biochar ranged from 16.19% to 45.35%, and the alkali metal content, ash content, and specific surface area were significantly reduced. The optimal route for biochar production is hydrothermal carbonization–pyrolysis (P-HC), resulting in biochar with a higher calorific value, C=C structure, and increased graphitization degree. The apparent activation energy (E) of the sample ranges from 199.1 to 324.8 kJ/mol, with P-HC having an E of 277.8 kJ/mol, lower than that of raw biomass, primary biochar, and anthracite. This makes P-HC more suitable for blast furnace injection fuel. Additionally, the paper proposes a path for P-HC injection in blast furnaces and calculates potential environmental benefits. P-HC offers the highest potential for carbon emission reduction, capable of reducing emissions by 96.04 kg/t when replacing 40wt% coal injection.
2024, vol. 31, no. 2, pp.
282-291.
https://doi.org/10.1007/s12613-023-2730-6
Abstract:
Direct reduction based on hydrogen metallurgical gas-based shaft furnace is a promising technology for the efficient and low-carbon smelting of vanadium–titanium magnetite. However, in this process, the sticking of pellets occurs due to the aggregation of metallic iron between the contact surfaces of adjacent pellets and has a serious negative effect on the continuous operation. This paper presents a detailed experimental study of the effect of TiO2 on the sticking behavior of pellets during direct reduction under different conditions. Results showed that the sticking index (SI) decreased linearly with the increasing TiO2 addition. This phenomenon can be attributed to the increase in unreduced FeTiO3 during reduction, leading to a decrease in the number and strength of metallic iron interconnections at the sticking interface. When the TiO2 addition amount was raised from 0 to 15wt% at 1100°C, the SI also increased from 0.71% to 59.91%. The connection of the slag phase could be attributed to the sticking at a low reduction temperature, corresponding to the low sticking strength. Moreover, the interconnection of metallic iron became the dominant factor, and the SI increased sharply with the increase in reduction temperature. TiO2 had a greater effect on SI at a high reduction temperature than at a low reduction temperature.
Direct reduction based on hydrogen metallurgical gas-based shaft furnace is a promising technology for the efficient and low-carbon smelting of vanadium–titanium magnetite. However, in this process, the sticking of pellets occurs due to the aggregation of metallic iron between the contact surfaces of adjacent pellets and has a serious negative effect on the continuous operation. This paper presents a detailed experimental study of the effect of TiO2 on the sticking behavior of pellets during direct reduction under different conditions. Results showed that the sticking index (SI) decreased linearly with the increasing TiO2 addition. This phenomenon can be attributed to the increase in unreduced FeTiO3 during reduction, leading to a decrease in the number and strength of metallic iron interconnections at the sticking interface. When the TiO2 addition amount was raised from 0 to 15wt% at 1100°C, the SI also increased from 0.71% to 59.91%. The connection of the slag phase could be attributed to the sticking at a low reduction temperature, corresponding to the low sticking strength. Moreover, the interconnection of metallic iron became the dominant factor, and the SI increased sharply with the increase in reduction temperature. TiO2 had a greater effect on SI at a high reduction temperature than at a low reduction temperature.
2024, vol. 31, no. 2, pp.
292-300.
https://doi.org/10.1007/s12613-023-2713-7
Abstract:
Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter. However, the release of chromium from stainless steel slag (SSS) during SSS stockpiling causes detrimental environmental issues. To prevent chromium pollution, the effects of iron oxide on crystallization behavior and spatial distribution of spinel were investigated in this work. The results revealed that FeO was more conducive to the growth of spinels compared with Fe2O3 and Fe3O4. Spinels were found to be mainly distributed at the top and bottom of slag. The amount of spinel phase at the bottom decreased with the increasing FeO content, while that at the top increased. The average particle size of spinel in the slag with 18wt% FeO content was 12.8 µm. Meanwhile, no notable structural changes were observed with a further increase in FeO content. In other words, the spatial distribution of spinel changed when the content of iron oxide varied in the range of 8wt% to 18wt%. Finally, less spinel was found at the bottom of slag with a FeO content of 23wt%.
Chromium plays a vital role in stainless steel due to its ability to improve the corrosion resistance of the latter. However, the release of chromium from stainless steel slag (SSS) during SSS stockpiling causes detrimental environmental issues. To prevent chromium pollution, the effects of iron oxide on crystallization behavior and spatial distribution of spinel were investigated in this work. The results revealed that FeO was more conducive to the growth of spinels compared with Fe2O3 and Fe3O4. Spinels were found to be mainly distributed at the top and bottom of slag. The amount of spinel phase at the bottom decreased with the increasing FeO content, while that at the top increased. The average particle size of spinel in the slag with 18wt% FeO content was 12.8 µm. Meanwhile, no notable structural changes were observed with a further increase in FeO content. In other words, the spatial distribution of spinel changed when the content of iron oxide varied in the range of 8wt% to 18wt%. Finally, less spinel was found at the bottom of slag with a FeO content of 23wt%.
2024, vol. 31, no. 2, pp.
301-314.
https://doi.org/10.1007/s12613-023-2705-7
Abstract:
The variation characteristics of bubble morphology and the thermal-physical properties of bubble boundary in the top-blown smelting furnace were explored by means of the computational fluid dynamics method. The essential aspects of the fluid phase (e.g., splashing volume, dead zone of copper slag, and gas penetration depth) were explored together with the effect of sinusoidal pulsating gas intake on the momentum-transfer performance between phases. The results illustrated that two relatively larger vortices and two smaller vortices appear in the bubble waist and below the lance, respectively. The expansion of larger ones as well as the shrinking of smaller ones combine to cause the contraction of the bubble waist. Compared to the results of the case with a fixed gas injection velocity (Vg = 58 m/s), the splashing volume and dead zone volume of the slag under the Vg = 58 + 10sin(2πt) condition are reduced by 24.9% and 23.5%, respectively, where t represents the instant time. Gas penetration depth and slag motion velocity of the latter are 1.03 and 1.31 times higher than those of the former, respectively.
The variation characteristics of bubble morphology and the thermal-physical properties of bubble boundary in the top-blown smelting furnace were explored by means of the computational fluid dynamics method. The essential aspects of the fluid phase (e.g., splashing volume, dead zone of copper slag, and gas penetration depth) were explored together with the effect of sinusoidal pulsating gas intake on the momentum-transfer performance between phases. The results illustrated that two relatively larger vortices and two smaller vortices appear in the bubble waist and below the lance, respectively. The expansion of larger ones as well as the shrinking of smaller ones combine to cause the contraction of the bubble waist. Compared to the results of the case with a fixed gas injection velocity (Vg = 58 m/s), the splashing volume and dead zone volume of the slag under the Vg = 58 + 10sin(2πt) condition are reduced by 24.9% and 23.5%, respectively, where t represents the instant time. Gas penetration depth and slag motion velocity of the latter are 1.03 and 1.31 times higher than those of the former, respectively.
2024, vol. 31, no. 2, pp.
315-322.
https://doi.org/10.1007/s12613-023-2698-2
Abstract:
Lithium recovery from spent lithium-ion batteries (LIBs) have attracted extensive attention due to the skyrocketing price of lithium. The medium-temperature carbon reduction roasting was proposed to preferential selective extraction of lithium from spent LiCoO2 (LCO) cathodes to overcome the incomplete recovery and loss of lithium during the recycling process. The LCO layered structure was destroyed and lithium was completely converted into water-soluble Li2CO3 under a suitable temperature to control the reduced state of the cobalt oxide. The Co metal agglomerates generated during medium-temperature carbon reduction roasting were broken by wet grinding and ultrasonic crushing to release the entrained lithium. The results showed that 99.10% of the whole lithium could be recovered as Li2CO3 with a purity of 99.55%. This work provided a new perspective on the preferentially selective extraction of lithium from spent lithium batteries.
Lithium recovery from spent lithium-ion batteries (LIBs) have attracted extensive attention due to the skyrocketing price of lithium. The medium-temperature carbon reduction roasting was proposed to preferential selective extraction of lithium from spent LiCoO2 (LCO) cathodes to overcome the incomplete recovery and loss of lithium during the recycling process. The LCO layered structure was destroyed and lithium was completely converted into water-soluble Li2CO3 under a suitable temperature to control the reduced state of the cobalt oxide. The Co metal agglomerates generated during medium-temperature carbon reduction roasting were broken by wet grinding and ultrasonic crushing to release the entrained lithium. The results showed that 99.10% of the whole lithium could be recovered as Li2CO3 with a purity of 99.55%. This work provided a new perspective on the preferentially selective extraction of lithium from spent lithium batteries.
2024, vol. 31, no. 2, pp.
323-336.
https://doi.org/10.1007/s12613-023-2736-0
Abstract:
Heavy components of low-alloy high-strength (LAHS) steels are generally formed by multi-pass forging. It is necessary to explore the flow characteristics and hot workability of LAHS steels during the multi-pass forging process, which is beneficial to the formulation of actual processing parameters. In the study, the multi-pass hot compression experiments of a typical LAHS steel are carried out at a wide range of deformation temperatures and strain rates. It is found that the work hardening rate of the experimental material depends on deformation parameters and deformation passes, which is ascribed to the impacts of static and dynamic softening behaviors. A new model is established to describe the flow characteristics at various deformation passes. Compared to the classical Arrhenius model and modified Zerilli and Armstrong model, the newly proposed model shows higher prediction accuracy with a confidence level of 0.98565. Furthermore, the connection between power dissipation efficiency (PDE) and deformation parameters is revealed by analyzing the microstructures. The PDE cannot be utilized to reflect the efficiency of energy dissipation for microstructure evolution during the entire deformation process, but only to assess the efficiency of energy dissipation for microstructure evolution in a specific deformation parameter state. As a result, an integrated processing map is proposed to better study the hot workability of the LAHS steel, which considers the effects of instability factor (IF), PDE, and distribution and size of grains. The optimized processing parameters for the multi-pass deformation process are the deformation parameters of 1223–1318 K and 0.01–0.08 s−1. Complete dynamic recrystallization occurs within the optimized processing parameters with an average grain size of 18.36–42.3 μm. This study will guide the optimization of the forging process of heavy components.
Heavy components of low-alloy high-strength (LAHS) steels are generally formed by multi-pass forging. It is necessary to explore the flow characteristics and hot workability of LAHS steels during the multi-pass forging process, which is beneficial to the formulation of actual processing parameters. In the study, the multi-pass hot compression experiments of a typical LAHS steel are carried out at a wide range of deformation temperatures and strain rates. It is found that the work hardening rate of the experimental material depends on deformation parameters and deformation passes, which is ascribed to the impacts of static and dynamic softening behaviors. A new model is established to describe the flow characteristics at various deformation passes. Compared to the classical Arrhenius model and modified Zerilli and Armstrong model, the newly proposed model shows higher prediction accuracy with a confidence level of 0.98565. Furthermore, the connection between power dissipation efficiency (PDE) and deformation parameters is revealed by analyzing the microstructures. The PDE cannot be utilized to reflect the efficiency of energy dissipation for microstructure evolution during the entire deformation process, but only to assess the efficiency of energy dissipation for microstructure evolution in a specific deformation parameter state. As a result, an integrated processing map is proposed to better study the hot workability of the LAHS steel, which considers the effects of instability factor (IF), PDE, and distribution and size of grains. The optimized processing parameters for the multi-pass deformation process are the deformation parameters of 1223–1318 K and 0.01–0.08 s−1. Complete dynamic recrystallization occurs within the optimized processing parameters with an average grain size of 18.36–42.3 μm. This study will guide the optimization of the forging process of heavy components.
2024, vol. 31, no. 2, pp.
337-350.
https://doi.org/10.1007/s12613-023-2679-5
Abstract:
This work constructed a machine learning (ML) model to predict the atmospheric corrosion rate of low-alloy steels (LAS). The material properties of LAS, environmental factors, and exposure time were used as the input, while the corrosion rate as the output. 6 different ML algorithms were used to construct the proposed model. Through optimization and filtering, the eXtreme gradient boosting (XGBoost) model exhibited good corrosion rate prediction accuracy. The features of material properties were then transformed into atomic and physical features using the proposed property transformation approach, and the dominant descriptors that affected the corrosion rate were filtered using the recursive feature elimination (RFE) as well as XGBoost methods. The established ML models exhibited better prediction performance and generalization ability via property transformation descriptors. In addition, the SHapley additive exPlanations (SHAP) method was applied to analyze the relationship between the descriptors and corrosion rate. The results showed that the property transformation model could effectively help with analyzing the corrosion behavior, thereby significantly improving the generalization ability of corrosion rate prediction models.
This work constructed a machine learning (ML) model to predict the atmospheric corrosion rate of low-alloy steels (LAS). The material properties of LAS, environmental factors, and exposure time were used as the input, while the corrosion rate as the output. 6 different ML algorithms were used to construct the proposed model. Through optimization and filtering, the eXtreme gradient boosting (XGBoost) model exhibited good corrosion rate prediction accuracy. The features of material properties were then transformed into atomic and physical features using the proposed property transformation approach, and the dominant descriptors that affected the corrosion rate were filtered using the recursive feature elimination (RFE) as well as XGBoost methods. The established ML models exhibited better prediction performance and generalization ability via property transformation descriptors. In addition, the SHapley additive exPlanations (SHAP) method was applied to analyze the relationship between the descriptors and corrosion rate. The results showed that the property transformation model could effectively help with analyzing the corrosion behavior, thereby significantly improving the generalization ability of corrosion rate prediction models.
2024, vol. 31, no. 2, pp.
351-361.
https://doi.org/10.1007/s12613-023-2733-3
Abstract:
Co–Ni-based superalloys are known for their capability to function at elevated temperatures and superior hot corrosion and thermal fatigue resistance. Therefore, these alloys show potential as crucial high-temperature structural materials for aeroengine and gas turbine hot-end components. Our previous work elucidated the influence of Ti and Ta on the high-temperature mechanical properties of alloys. However, the intricate interaction among elements considerably affects the oxidation resistance of alloys. In this paper, Co–35Ni–10Al–2W–5Cr–2Mo–1Nb–xTi–(5−x)Ta alloys (x = 1, 2, 3, 4) with varying Ti and Ta contents were designed and compounded, and their oxidation resistance was investigated at the temperature range from 800 to 1000°C. After oxidation at three test conditions, namely, 800°C for 200 h, 900°C for 200 h, and 1000°C for 50 h, the main structure of the oxide layer of the alloy consisted of spinel, Cr2O3, and Al2O3 from outside to inside. Oxides consisting of Ta, W, and Mo formed below the Cr2O3 layer. The interaction of Ti and Ta imparted the highest oxidation resistance to 3Ti2Ta alloy. Conversely, an excessive amount of Ti or Ta resulted in an adverse effect on the oxidation resistance of the alloys. This study reports the volatilization of W and Mo oxides during the oxidation process of Co–Ni-based cast superalloys with a high Al content for the first time and explains the formation mechanism of holes in the oxide layer. The results provide a basis for gaining insights into the effects of the interaction of alloying elements on the oxidation resistance of the alloys they form.
Co–Ni-based superalloys are known for their capability to function at elevated temperatures and superior hot corrosion and thermal fatigue resistance. Therefore, these alloys show potential as crucial high-temperature structural materials for aeroengine and gas turbine hot-end components. Our previous work elucidated the influence of Ti and Ta on the high-temperature mechanical properties of alloys. However, the intricate interaction among elements considerably affects the oxidation resistance of alloys. In this paper, Co–35Ni–10Al–2W–5Cr–2Mo–1Nb–xTi–(5−x)Ta alloys (x = 1, 2, 3, 4) with varying Ti and Ta contents were designed and compounded, and their oxidation resistance was investigated at the temperature range from 800 to 1000°C. After oxidation at three test conditions, namely, 800°C for 200 h, 900°C for 200 h, and 1000°C for 50 h, the main structure of the oxide layer of the alloy consisted of spinel, Cr2O3, and Al2O3 from outside to inside. Oxides consisting of Ta, W, and Mo formed below the Cr2O3 layer. The interaction of Ti and Ta imparted the highest oxidation resistance to 3Ti2Ta alloy. Conversely, an excessive amount of Ti or Ta resulted in an adverse effect on the oxidation resistance of the alloys. This study reports the volatilization of W and Mo oxides during the oxidation process of Co–Ni-based cast superalloys with a high Al content for the first time and explains the formation mechanism of holes in the oxide layer. The results provide a basis for gaining insights into the effects of the interaction of alloying elements on the oxidation resistance of the alloys they form.
2024, vol. 31, no. 2, pp.
362-373.
https://doi.org/10.1007/s12613-023-2764-9
Abstract:
The main objective of this work was to modify the microstructure and enhance the tribological properties of a new Zn–4Si alloy through a high solidification cooling rate (SCR). According to the results, by increasing the SCR from 2.0 to 59.5°C/s the average size of primary Si particles and that of the grains reduced from 76.1 and 3780 μm to less than about 14.6 and 460 μm, respectively. Augmenting the SCR also enhanced the microstructural homogeneity, decreased the porosity content (by 50%), and increased the matrix hardness (by 36%). These microstructural changes enhanced the tribological behavior. For instance, under the applied pressure of 0.5 MPa, an increase in the SCR from 2.0 to 59.5°C/s decreased the wear rate and the average friction coefficient of the alloy by 57% and 23%, respectively. The wear mechanism was also changed from the severe delamination, adhesion, and abrasion in the slowly-cooled alloy to the mild tribolayer delamination/abrasion in the high-cooling-rate-solidified sample.
The main objective of this work was to modify the microstructure and enhance the tribological properties of a new Zn–4Si alloy through a high solidification cooling rate (SCR). According to the results, by increasing the SCR from 2.0 to 59.5°C/s the average size of primary Si particles and that of the grains reduced from 76.1 and 3780 μm to less than about 14.6 and 460 μm, respectively. Augmenting the SCR also enhanced the microstructural homogeneity, decreased the porosity content (by 50%), and increased the matrix hardness (by 36%). These microstructural changes enhanced the tribological behavior. For instance, under the applied pressure of 0.5 MPa, an increase in the SCR from 2.0 to 59.5°C/s decreased the wear rate and the average friction coefficient of the alloy by 57% and 23%, respectively. The wear mechanism was also changed from the severe delamination, adhesion, and abrasion in the slowly-cooled alloy to the mild tribolayer delamination/abrasion in the high-cooling-rate-solidified sample.
2024, vol. 31, no. 2, pp.
374-383.
https://doi.org/10.1007/s12613-023-2701-y
Abstract:
In recent years, the addition of Ni has been widely acknowledged to be capable of enhancing the mechanical properties of Al–Si alloys. However, the effect of Ni on the wear behaviors of Al–Si alloys and Al matrix composites, particularly at elevated temperatures, remains an understudied area. In this study, Al–Si–Cu–Mg–Ni/20wt% SiC particles (SiCp) composites with varying Ni contents were prepared by using a semisolid stir casting method. The effect of Ni content on the dry sliding wear behavior of the prepared composites was investigated through sliding tests at 25 and 350°C. Results indicated that the θ-Al2Cu phase gradually diminished and eventually disappeared as the Ni content increased from 0wt% to 3wt%. This change was accompanied by the formation and increase in δ-Al3CuNi and ε-Al3Ni phases in microstructures. The hardness and ultimate tensile strength of the as-cast composites improved, and the wear rates of the composites decreased from 5.29 × 10−4 to 1.94 × 10−4 mm3/(N∙m) at 25°C and from 20.2 × 10−4 to 7 × 10−4 mm3/(N∙m) at 350°C with the increase in Ni content from 0wt% to 2wt%. The enhancement in performance was due to the presence of strengthening network structures and additional Ni-containing phases in the composites. However, the wear rate of the 3Ni composite was approximately two times higher than that of the 2Ni composite due to the fracture and debonding of the ε-Al3Ni phase. Abrasive wear, delamination wear, and oxidation wear were the predominant wear mechanisms of the investigated composites at 25°C, whereas delamination wear and oxidation wear were dominant during sliding at 350°C.
In recent years, the addition of Ni has been widely acknowledged to be capable of enhancing the mechanical properties of Al–Si alloys. However, the effect of Ni on the wear behaviors of Al–Si alloys and Al matrix composites, particularly at elevated temperatures, remains an understudied area. In this study, Al–Si–Cu–Mg–Ni/20wt% SiC particles (SiCp) composites with varying Ni contents were prepared by using a semisolid stir casting method. The effect of Ni content on the dry sliding wear behavior of the prepared composites was investigated through sliding tests at 25 and 350°C. Results indicated that the θ-Al2Cu phase gradually diminished and eventually disappeared as the Ni content increased from 0wt% to 3wt%. This change was accompanied by the formation and increase in δ-Al3CuNi and ε-Al3Ni phases in microstructures. The hardness and ultimate tensile strength of the as-cast composites improved, and the wear rates of the composites decreased from 5.29 × 10−4 to 1.94 × 10−4 mm3/(N∙m) at 25°C and from 20.2 × 10−4 to 7 × 10−4 mm3/(N∙m) at 350°C with the increase in Ni content from 0wt% to 2wt%. The enhancement in performance was due to the presence of strengthening network structures and additional Ni-containing phases in the composites. However, the wear rate of the 3Ni composite was approximately two times higher than that of the 2Ni composite due to the fracture and debonding of the ε-Al3Ni phase. Abrasive wear, delamination wear, and oxidation wear were the predominant wear mechanisms of the investigated composites at 25°C, whereas delamination wear and oxidation wear were dominant during sliding at 350°C.
2024, vol. 31, no. 2, pp.
384-394.
https://doi.org/10.1007/s12613-023-2715-5
Abstract:
Pure cobalt (Co) thin films were fabricated by direct current magnetron sputtering, and the effects of sputtering power and pressure on the microstructure and electromagnetic properties of the films were investigated. As the sputtering power increases from 15 to 60 W, the Co thin films transition from an amorphous to a polycrystalline state, accompanied by an increase in the intercrystal pore width. Simultaneously, the resistivity decreases from 276 to 99 μΩ·cm, coercivity increases from 162 to 293 Oe, and in-plane magnetic anisotropy disappears. As the sputtering pressure decreases from 1.6 to 0.2 Pa, grain size significantly increases, resistivity significantly decreases, and the coercivity significantly increases (from 67 to 280 Oe), which can be attributed to the increase in defect width. Correspondingly, a quantitative model for the coercivity of Co thin films was formulated. The polycrystalline films sputtered under pressures of 0.2 and 0.4 Pa exhibit significant in-plane magnetic anisotropy, which is primarily attributable to increased microstress.
Pure cobalt (Co) thin films were fabricated by direct current magnetron sputtering, and the effects of sputtering power and pressure on the microstructure and electromagnetic properties of the films were investigated. As the sputtering power increases from 15 to 60 W, the Co thin films transition from an amorphous to a polycrystalline state, accompanied by an increase in the intercrystal pore width. Simultaneously, the resistivity decreases from 276 to 99 μΩ·cm, coercivity increases from 162 to 293 Oe, and in-plane magnetic anisotropy disappears. As the sputtering pressure decreases from 1.6 to 0.2 Pa, grain size significantly increases, resistivity significantly decreases, and the coercivity significantly increases (from 67 to 280 Oe), which can be attributed to the increase in defect width. Correspondingly, a quantitative model for the coercivity of Co thin films was formulated. The polycrystalline films sputtered under pressures of 0.2 and 0.4 Pa exhibit significant in-plane magnetic anisotropy, which is primarily attributable to increased microstress.
2024, vol. 31, no. 2, pp.
395-404.
https://doi.org/10.1007/s12613-023-2726-2
Abstract:
The development of anode materials with high rate capability and long charge–discharge plateau is the key to improve performance of lithium-ion capacitors (LICs). Herein, the porous graphitic carbon (PGC-1300) derived from a new triply interpenetrated cobalt metal-organic framework (Co-MOF) was prepared through the facile and robust carbonization at 1300°C and washing by HCl solution. The as-prepared PGC-1300 featured an optimized graphitization degree and porous framework, which not only contributes to high plateau capacity (105.0 mAh·g−1 below 0.2 V at 0.05 A·g−1), but also supplies more convenient pathways for ions and increases the rate capability (128.5 mAh·g−1 at 3.2 A·g−1). According to the kinetics analyses, it can be found that diffusion regulated surface induced capacitive process and Li-ions intercalation process are coexisted for lithium-ion storage. Additionally, LIC PGC-1300//AC constructed with pre-lithiated PGC-1300 anode and activated carbon (AC) cathode exhibited an increased energy density of 102.8 Wh·kg−1, a power density of 6017.1 W·kg−1, together with the excellent cyclic stability (91.6% retention after 10000 cycles at 1.0 A·g−1).
The development of anode materials with high rate capability and long charge–discharge plateau is the key to improve performance of lithium-ion capacitors (LICs). Herein, the porous graphitic carbon (PGC-1300) derived from a new triply interpenetrated cobalt metal-organic framework (Co-MOF) was prepared through the facile and robust carbonization at 1300°C and washing by HCl solution. The as-prepared PGC-1300 featured an optimized graphitization degree and porous framework, which not only contributes to high plateau capacity (105.0 mAh·g−1 below 0.2 V at 0.05 A·g−1), but also supplies more convenient pathways for ions and increases the rate capability (128.5 mAh·g−1 at 3.2 A·g−1). According to the kinetics analyses, it can be found that diffusion regulated surface induced capacitive process and Li-ions intercalation process are coexisted for lithium-ion storage. Additionally, LIC PGC-1300//AC constructed with pre-lithiated PGC-1300 anode and activated carbon (AC) cathode exhibited an increased energy density of 102.8 Wh·kg−1, a power density of 6017.1 W·kg−1, together with the excellent cyclic stability (91.6% retention after 10000 cycles at 1.0 A·g−1).
2024, vol. 31, no. 2, pp.
405-411.
https://doi.org/10.1007/s12613-023-2692-8
Abstract:
For present solid oxide fuel cells (SOFCs), rapid performance degradation is observed in the initial aging process, and the discussion of the degradation mechanism necessitates quantitative analysis. Herein, focused ion beam-scanning electron microscopy was employed to characterize and reconstruct the ceramic microstructures of SOFC anodes. The lattice Boltzmann method (LBM) simulation of multiphysical and electrochemical processes in the reconstructed models was performed. Two samples collected from industrial-size cells were characterized, including a reduced reference cell and a cell with an initial aging process. Statistical parameters of the reconstructed microstructures revealed a significant decrease in the active triple-phase boundary and Ni connectivity in the aged cell compared with the reference cell. The LBM simulation revealed that activity degradation is dominant compared with microstructural degradation during the initial aging process, and the electrochemical reactions spread to the support layer in the aged cell. The microstructural and activity degradations are attributed to Ni migration and coarsening.
For present solid oxide fuel cells (SOFCs), rapid performance degradation is observed in the initial aging process, and the discussion of the degradation mechanism necessitates quantitative analysis. Herein, focused ion beam-scanning electron microscopy was employed to characterize and reconstruct the ceramic microstructures of SOFC anodes. The lattice Boltzmann method (LBM) simulation of multiphysical and electrochemical processes in the reconstructed models was performed. Two samples collected from industrial-size cells were characterized, including a reduced reference cell and a cell with an initial aging process. Statistical parameters of the reconstructed microstructures revealed a significant decrease in the active triple-phase boundary and Ni connectivity in the aged cell compared with the reference cell. The LBM simulation revealed that activity degradation is dominant compared with microstructural degradation during the initial aging process, and the electrochemical reactions spread to the support layer in the aged cell. The microstructural and activity degradations are attributed to Ni migration and coarsening.
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