Search2023 Vol. 30, No. 12
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2023, vol. 30, no. 12, pp.
2281-2296.
https://doi.org/10.1007/s12613-023-2716-4
Abstract:
Hypo-peritectic steels are widely used in various industrial fields because of their high strength, high toughness, high processability, high weldability, and low material cost. However, surface defects are liable to occur during continuous casting, which includes depression, longitudinal cracks, deep oscillation marks, and severe level fluctuation with slag entrapment. The high-efficiency production of hypo-peritectic steels by continuous casting is still a great challenge due to the limited understanding of the mechanism of peritectic solidification. This work reviews the definition and classification of hypo-peritectic steels and introduces the formation tendency of common surface defects related to peritectic solidification. New achievements in the mechanism of peritectic reaction and transformation have been listed. Finally, countermeasures to avoiding surface defects of hypo-peritectic steels duiring continuous casting are summarized. Enlightening certain points in the continuous casting of hypo-peritectic steels and the development of new techniques to overcome the present problems will be a great aid to researchers.
Hypo-peritectic steels are widely used in various industrial fields because of their high strength, high toughness, high processability, high weldability, and low material cost. However, surface defects are liable to occur during continuous casting, which includes depression, longitudinal cracks, deep oscillation marks, and severe level fluctuation with slag entrapment. The high-efficiency production of hypo-peritectic steels by continuous casting is still a great challenge due to the limited understanding of the mechanism of peritectic solidification. This work reviews the definition and classification of hypo-peritectic steels and introduces the formation tendency of common surface defects related to peritectic solidification. New achievements in the mechanism of peritectic reaction and transformation have been listed. Finally, countermeasures to avoiding surface defects of hypo-peritectic steels duiring continuous casting are summarized. Enlightening certain points in the continuous casting of hypo-peritectic steels and the development of new techniques to overcome the present problems will be a great aid to researchers.
2023, vol. 30, no. 12, pp.
2297-2309.
https://doi.org/10.1007/s12613-023-2690-x
Abstract:
This review offers an overview of the latest developments in metal–covalent organic framework (MCOF) and covalent metal–organic framework (CMOF) materials, whose construction entails a combination of reversible coordination and covalent bonding adapted from metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), respectively. With an emphasis on the MCOF and CMOF structures, this review surveys their building blocks and topologies. Specifically, the frameworks are classified based on the dimensions of their components (building blocks), namely, discrete building blocks and one-dimensional infinite building blocks. For the first category, the materials are further divided into collections of two- and three-dimensional networks based on their topologies. For the second category, the recently emerging MCOFs with woven structures are covered. Finally, the state-of-the-art in MCOF and CMOF chemistry has been laid out for promising avenues in future developments.
This review offers an overview of the latest developments in metal–covalent organic framework (MCOF) and covalent metal–organic framework (CMOF) materials, whose construction entails a combination of reversible coordination and covalent bonding adapted from metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), respectively. With an emphasis on the MCOF and CMOF structures, this review surveys their building blocks and topologies. Specifically, the frameworks are classified based on the dimensions of their components (building blocks), namely, discrete building blocks and one-dimensional infinite building blocks. For the first category, the materials are further divided into collections of two- and three-dimensional networks based on their topologies. For the second category, the recently emerging MCOFs with woven structures are covered. Finally, the state-of-the-art in MCOF and CMOF chemistry has been laid out for promising avenues in future developments.
2023, vol. 30, no. 12, pp.
2310-2320.
https://doi.org/10.1007/s12613-023-2667-9
Abstract:
Engineering geological disasters such as rockburst have always been a critical factor affecting the safety of coal mine production. Thus, residual stress is considered a feasible method to explain these geomechanical phenomena. In this study, electron backscatter diffraction (EBSD) and optical microscopy were used to characterize the rock microcosm. A measuring area that met the requirements of X-ray diffraction (XRD) residual stress measurement was determined to account for the mechanism of rock residual stress. Then, the residual stress of a siliceous slate-containing quartz vein was measured and calculated using the sin2ϕ method equipped with an X-ray diffractometer. Analysis of microscopic test results showed homogeneous areas with small particles within the millimeter range, meeting the requirements of XRD stress measurement statistics. Quartz was determined as the calibration mineral for slate samples containing quartz veins. The diffraction patterns of the (324) crystal plane were obtained under different ϕ and φ. The deviation direction of the diffraction peaks was consistent, indicating that the sample tested had residual stress. In addition, the principal residual stress within the quartz vein measured by XRD was compressive, ranging from 10 to 33 MPa. The maximum principal stress was parallel to the vein trend, whereas the minimum principal stress was perpendicular to the vein trend. Furthermore, the content of the low-angle boundary and twin boundary in the quartz veins was relatively high, which enhances the resistance of the rock mass to deformation and promotes the easy formation of strain concentrations, thereby resulting in residual stress. The proposed method for measuring residual stress can serve as a reference for subsequent observation and related research on residual stress in different types of rocks.
Engineering geological disasters such as rockburst have always been a critical factor affecting the safety of coal mine production. Thus, residual stress is considered a feasible method to explain these geomechanical phenomena. In this study, electron backscatter diffraction (EBSD) and optical microscopy were used to characterize the rock microcosm. A measuring area that met the requirements of X-ray diffraction (XRD) residual stress measurement was determined to account for the mechanism of rock residual stress. Then, the residual stress of a siliceous slate-containing quartz vein was measured and calculated using the sin2ϕ method equipped with an X-ray diffractometer. Analysis of microscopic test results showed homogeneous areas with small particles within the millimeter range, meeting the requirements of XRD stress measurement statistics. Quartz was determined as the calibration mineral for slate samples containing quartz veins. The diffraction patterns of the (324) crystal plane were obtained under different ϕ and φ. The deviation direction of the diffraction peaks was consistent, indicating that the sample tested had residual stress. In addition, the principal residual stress within the quartz vein measured by XRD was compressive, ranging from 10 to 33 MPa. The maximum principal stress was parallel to the vein trend, whereas the minimum principal stress was perpendicular to the vein trend. Furthermore, the content of the low-angle boundary and twin boundary in the quartz veins was relatively high, which enhances the resistance of the rock mass to deformation and promotes the easy formation of strain concentrations, thereby resulting in residual stress. The proposed method for measuring residual stress can serve as a reference for subsequent observation and related research on residual stress in different types of rocks.
2023, vol. 30, no. 12, pp.
2321-2333.
https://doi.org/10.1007/s12613-023-2680-z
Abstract:
The 3D reconstruction and quantitative characterization of drainage channels and coarse tailings particles in a bed were conducted in this study. The influence of variations in the azimuthal angle (θ) and polar angle (φ) of coarse particles on drainage channel structure was analyzed, and the drainage mechanism of the bed was studied. Results showed that water discharge in the bed reduced the size of pores and throat channels, increasing slurry concentration. The throat channel structure was a key component of the drainage process. The φ and θ of particles changed predominantly along the length direction. The changes in φ had a cumulative plugging effect on the drainage channel and increased the difficulty of water discharge. The rake and rod formed a shear ring in the tailings bed with shear, and the θ distribution of particles changed from disorderly to orderly during the rotation process. The drainage channel was squeezed during the shearing process with the change in θ, which broke the channel structure, encouraged water discharge in the bed, and facilitated a further increase in slurry concentration. The findings of this work are expected to offer theoretical guidance for preparing high-concentration underflow in the tailings thickening process.
The 3D reconstruction and quantitative characterization of drainage channels and coarse tailings particles in a bed were conducted in this study. The influence of variations in the azimuthal angle (θ) and polar angle (φ) of coarse particles on drainage channel structure was analyzed, and the drainage mechanism of the bed was studied. Results showed that water discharge in the bed reduced the size of pores and throat channels, increasing slurry concentration. The throat channel structure was a key component of the drainage process. The φ and θ of particles changed predominantly along the length direction. The changes in φ had a cumulative plugging effect on the drainage channel and increased the difficulty of water discharge. The rake and rod formed a shear ring in the tailings bed with shear, and the θ distribution of particles changed from disorderly to orderly during the rotation process. The drainage channel was squeezed during the shearing process with the change in θ, which broke the channel structure, encouraged water discharge in the bed, and facilitated a further increase in slurry concentration. The findings of this work are expected to offer theoretical guidance for preparing high-concentration underflow in the tailings thickening process.
2023, vol. 30, no. 12, pp.
2334-2346.
https://doi.org/10.1007/s12613-023-2725-3
Abstract:
With the intensified depletion of high-grade iron ores, the increased aluminum content in iron ore concentrates has become unavoidable, which is detrimental to the pelletization process. Therefore, the effect mechanism of aluminum on pellet quality must be identified. In this study, the influence of aluminum occurrence and content on the induration of hematite (H) and magnetite (M) pellets was investigated through the addition of corresponding Al-containing additives, including alumina, alumogoethite, gibbsite, and kaolinite. Systematic mineralogical analysis, combined with the thermodynamic properties of different aluminum occurrences and the quantitative characterization of consolidation behaviors, were conducted to determine the related mechanism. The results showed that the alumina from various aluminum occurrences adversely affected the induration characteristics of pellets, especially at an aluminum content of more than 2.0wt%. The thermal decomposition of gibbsite and kaolinite tends to generate internal stress and fine cracks, which hinder the respective microcrystalline bonding and recrystallization between Fe2O3 particles. The adverse effect on the induration characteristics of fired pellets with different aluminum occurrences can be relieved to varying degrees through the formation of liquid phase bonds between the hematite particles. Kaolinite is more beneficial to the induration process than the other three aluminum occurrences because of the formation of more liquid phase, which improves pellet consolidation. The research results can further provide insights into the effect of aluminum occurrence and content in iron ore concentrates on downstream processing and serve as a guide for the utilization of high-alumina iron ore concentrates in pelletization.
With the intensified depletion of high-grade iron ores, the increased aluminum content in iron ore concentrates has become unavoidable, which is detrimental to the pelletization process. Therefore, the effect mechanism of aluminum on pellet quality must be identified. In this study, the influence of aluminum occurrence and content on the induration of hematite (H) and magnetite (M) pellets was investigated through the addition of corresponding Al-containing additives, including alumina, alumogoethite, gibbsite, and kaolinite. Systematic mineralogical analysis, combined with the thermodynamic properties of different aluminum occurrences and the quantitative characterization of consolidation behaviors, were conducted to determine the related mechanism. The results showed that the alumina from various aluminum occurrences adversely affected the induration characteristics of pellets, especially at an aluminum content of more than 2.0wt%. The thermal decomposition of gibbsite and kaolinite tends to generate internal stress and fine cracks, which hinder the respective microcrystalline bonding and recrystallization between Fe2O3 particles. The adverse effect on the induration characteristics of fired pellets with different aluminum occurrences can be relieved to varying degrees through the formation of liquid phase bonds between the hematite particles. Kaolinite is more beneficial to the induration process than the other three aluminum occurrences because of the formation of more liquid phase, which improves pellet consolidation. The research results can further provide insights into the effect of aluminum occurrence and content in iron ore concentrates on downstream processing and serve as a guide for the utilization of high-alumina iron ore concentrates in pelletization.
2023, vol. 30, no. 12, pp.
2347-2355.
https://doi.org/10.1007/s12613-023-2681-y
Abstract:
The demand for alternative low-grade iron ores is on the rise due to the rapid depletion of high-grade natural iron ore resources and the increased need for steel usage in daily life. However, the use of low-grade iron ores is a constant clinical task for industry metallurgists. Direct smelting of low-grade ores consumes a substantial amount of energy due to the large volume of slag generated. This condition can be avoided by direct reduction followed by magnetic separation (to separate the high amount of gangue or refractory and metal parts) and smelting. Chromite overburden (COB) is a mine waste generated in chromite ore processing, and it mainly consists of iron, chromium, and nickel (<1wt%). In the present work, the isothermal and non-isothermal kinetics of the solid-state reduction of self-reduced pellets prepared using low-grade iron ore (COB) were thoroughly investigated via thermal analysis. The results showed that the reduction of pellets followed a first-order autocatalytic reaction control mechanism in the temperature range of 900–1100°C. The autocatalytic nature of the reduction reaction was due to the presence of nickel in the COB. The apparent activation energy obtained from the kinetics results showed that the solid-state reactions between COB and carbon were the rate-determining step in iron oxide reduction.
The demand for alternative low-grade iron ores is on the rise due to the rapid depletion of high-grade natural iron ore resources and the increased need for steel usage in daily life. However, the use of low-grade iron ores is a constant clinical task for industry metallurgists. Direct smelting of low-grade ores consumes a substantial amount of energy due to the large volume of slag generated. This condition can be avoided by direct reduction followed by magnetic separation (to separate the high amount of gangue or refractory and metal parts) and smelting. Chromite overburden (COB) is a mine waste generated in chromite ore processing, and it mainly consists of iron, chromium, and nickel (<1wt%). In the present work, the isothermal and non-isothermal kinetics of the solid-state reduction of self-reduced pellets prepared using low-grade iron ore (COB) were thoroughly investigated via thermal analysis. The results showed that the reduction of pellets followed a first-order autocatalytic reaction control mechanism in the temperature range of 900–1100°C. The autocatalytic nature of the reduction reaction was due to the presence of nickel in the COB. The apparent activation energy obtained from the kinetics results showed that the solid-state reactions between COB and carbon were the rate-determining step in iron oxide reduction.
2023, vol. 30, no. 12, pp.
2356-2363.
https://doi.org/10.1007/s12613-023-2722-6
Abstract:
Separated preparation of prealloys and amorphous alloys results in severe solidification–remelting and beneficial element removal–readdition contradictions, which markedly increase energy consumption and emissions. This study offered a novel strategy for the direct production of FePC amorphous soft magnetic alloys via smelting reduction of high-phosphorus iron ore (HPIO) and apatite. First, the thermodynamic conditions and equilibrium states of the carbothermal reduction reactions in HPIO were calculated, and the element content in reduced alloys was theoretically determined. The phase and structural evolutions, as well as element migration and enrichment behaviors during the smelting reduction of HPIO and Ca3(PO4)2, were then experimentally verified. The addition of Ca3(PO4)2 in HPIO contributes to the enrichment of the P element in reduced alloys and the subsequent development of Fe3P and Fe2P phases. The content of P and C elements in the range of 1.52wt%–14.63wt% and 0.62wt%–2.47wt%, respectively, can be well tailored by adding 0–50 g Ca3(PO4)2 and controlling the C/O mole ratio of 0.8–1.1, which is highly consistent with the calculated results. These FePC alloys were then successfully formed into amorphous ribbons and rods. The energy consumption of the proposed strategy was estimated to be 2.00 × 108 kJ/t, which is reduced by 30% when compared with the conventional production process. These results are critical for the comprehensive utilization of mineral resources and pave the way for the clean production of Fe-based amorphous soft magnetic alloys.
Separated preparation of prealloys and amorphous alloys results in severe solidification–remelting and beneficial element removal–readdition contradictions, which markedly increase energy consumption and emissions. This study offered a novel strategy for the direct production of FePC amorphous soft magnetic alloys via smelting reduction of high-phosphorus iron ore (HPIO) and apatite. First, the thermodynamic conditions and equilibrium states of the carbothermal reduction reactions in HPIO were calculated, and the element content in reduced alloys was theoretically determined. The phase and structural evolutions, as well as element migration and enrichment behaviors during the smelting reduction of HPIO and Ca3(PO4)2, were then experimentally verified. The addition of Ca3(PO4)2 in HPIO contributes to the enrichment of the P element in reduced alloys and the subsequent development of Fe3P and Fe2P phases. The content of P and C elements in the range of 1.52wt%–14.63wt% and 0.62wt%–2.47wt%, respectively, can be well tailored by adding 0–50 g Ca3(PO4)2 and controlling the C/O mole ratio of 0.8–1.1, which is highly consistent with the calculated results. These FePC alloys were then successfully formed into amorphous ribbons and rods. The energy consumption of the proposed strategy was estimated to be 2.00 × 108 kJ/t, which is reduced by 30% when compared with the conventional production process. These results are critical for the comprehensive utilization of mineral resources and pave the way for the clean production of Fe-based amorphous soft magnetic alloys.
2023, vol. 30, no. 12, pp.
2364-2374.
https://doi.org/10.1007/s12613-023-2723-5
Abstract:
Photocatalytic processes are efficient methods to solve water contamination problems, especially considering dyeing wastewater disposal. However, high-efficiency photocatalysts are usually very expensive and have the risk of heavy metal pollution. Recently, an iron oxides@hydrothermal carbonation carbon (HTCC) heterogeneous catalyst was prepared by our group through co-hydrothermal treatment of carbohydrates and zinc extraction tailings of converter dust. Herein, the catalytic performance of the iron oxides@HTCC was verified by a non-biodegradable dye, methylene blue (MB), and the catalytic mechanism was deduced from theoretical simulations and spectroscopic measurements. The iron oxides@HTCC showed an excellent synergy between photocatalysis and Fenton-like reactions. Under visible-light illumination, the iron oxides@HTCC could be excited to generate electrons and holes, reacting with H2O2 to produce\begin{document}$\cdot\mathrm{O}\mathrm{H}$\end{document}
Photocatalytic processes are efficient methods to solve water contamination problems, especially considering dyeing wastewater disposal. However, high-efficiency photocatalysts are usually very expensive and have the risk of heavy metal pollution. Recently, an iron oxides@hydrothermal carbonation carbon (HTCC) heterogeneous catalyst was prepared by our group through co-hydrothermal treatment of carbohydrates and zinc extraction tailings of converter dust. Herein, the catalytic performance of the iron oxides@HTCC was verified by a non-biodegradable dye, methylene blue (MB), and the catalytic mechanism was deduced from theoretical simulations and spectroscopic measurements. The iron oxides@HTCC showed an excellent synergy between photocatalysis and Fenton-like reactions. Under visible-light illumination, the iron oxides@HTCC could be excited to generate electrons and holes, reacting with H2O2 to produce
2023, vol. 30, no. 12, pp.
2375-2385.
https://doi.org/10.1007/s12613-023-2651-4
Abstract:
Bipolar electrochemistry is used to produce a linear potential gradient across a bipolar electrode (BPE), providing direct access to the anodic and cathodic reactions under a wide range of applied potentials. The occurrence of pitting corrosion, crevice corrosion, and general corrosion on type 2205 duplex stainless steel (DSS 2205) BPE has been observed at room temperature. The critical pit depth of 10–20 μm with a 55%–75% probability of pits developing into stable pits at potential from +0.9 to +1.2 V vs. OCP (open circuit potential) are measured. All pit nucleation sites are either within ferritic grains or at the interface between austenite and ferrite. The critical conditions for pitting and crevice corrosion are discussed with Epit (critical pitting potential) and Ecre (critical crevice potential) decreasing from 0.87 and 0.80 V vs. OCP after 150 s of exposure to 0.84 and 0.76 V vs. OCP after 900 s of exposure, respectively. Pit growth kinetics under different applied bipolar potentials and exposure times have been obtained. The ferrite is shown to be more susceptible to general dissolution.
Bipolar electrochemistry is used to produce a linear potential gradient across a bipolar electrode (BPE), providing direct access to the anodic and cathodic reactions under a wide range of applied potentials. The occurrence of pitting corrosion, crevice corrosion, and general corrosion on type 2205 duplex stainless steel (DSS 2205) BPE has been observed at room temperature. The critical pit depth of 10–20 μm with a 55%–75% probability of pits developing into stable pits at potential from +0.9 to +1.2 V vs. OCP (open circuit potential) are measured. All pit nucleation sites are either within ferritic grains or at the interface between austenite and ferrite. The critical conditions for pitting and crevice corrosion are discussed with Epit (critical pitting potential) and Ecre (critical crevice potential) decreasing from 0.87 and 0.80 V vs. OCP after 150 s of exposure to 0.84 and 0.76 V vs. OCP after 900 s of exposure, respectively. Pit growth kinetics under different applied bipolar potentials and exposure times have been obtained. The ferrite is shown to be more susceptible to general dissolution.
2023, vol. 30, no. 12, pp.
2386-2396.
https://doi.org/10.1007/s12613-023-2714-6
Abstract:
The hot deformation behaviours of 316LN-Mn austenitic stainless steel were investigated by uniaxial isothermal compression tests at different temperatures and strain rates. The microstructural evolutions were also studied using electron backscatter diffraction. The flow stress decreases with the increasing temperature and decreasing strain rate. A constitutive equation was established to characterize the relationship among the deformation parameters, and the deformation activation energy was calculated to be 497.92 kJ/mol. Processing maps were constructed to describe the appropriate processing window, and the optimum processing parameters were determined at a temperature of 1107–1160°C and a strain rate of 0.005–0.026 s−1. Experimental results showed that the main nucleation mechanism is discontinuous dynamic recrystallization (DDRX), followed by continuous dynamic recrystallization (CDRX). In addition, the formation of twin boundaries facilitated the nucleation of dynamic recrystallization.
The hot deformation behaviours of 316LN-Mn austenitic stainless steel were investigated by uniaxial isothermal compression tests at different temperatures and strain rates. The microstructural evolutions were also studied using electron backscatter diffraction. The flow stress decreases with the increasing temperature and decreasing strain rate. A constitutive equation was established to characterize the relationship among the deformation parameters, and the deformation activation energy was calculated to be 497.92 kJ/mol. Processing maps were constructed to describe the appropriate processing window, and the optimum processing parameters were determined at a temperature of 1107–1160°C and a strain rate of 0.005–0.026 s−1. Experimental results showed that the main nucleation mechanism is discontinuous dynamic recrystallization (DDRX), followed by continuous dynamic recrystallization (CDRX). In addition, the formation of twin boundaries facilitated the nucleation of dynamic recrystallization.
2023, vol. 30, no. 12, pp.
2397-2410.
https://doi.org/10.1007/s12613-023-2706-6
Abstract:
The hot compression behavior of as-extruded Mg–0.6Mn–0.5Al–0.5Zn–0.4Ca alloy was studied on a Gleeble-3500 thermal simulation machine. Experiments were conducted at temperatures ranging from 523 to 673 K and strain rates ranging from 0.001 to 1 s−1. Results showed that an increase in the strain rate or a decrease in deformation temperature led to an increase in true stress. The constitutive equation and processing maps of the alloy were obtained and analyzed. The influence of deformation temperatures and strain rates on microstructural evolution and texture was studied with the assistance of electron backscatter diffraction (EBSD). The as-extruded alloy exhibited a bimodal structure that consisted of deformed coarse grains and fine equiaxed recrystallized structures (approximately 1.57 μm). The EBSD results of deformed alloy samples revealed that the recrystallization degree and average grain size increased as the deformation temperature increased. By contrast, dislocation density and texture intensity decreased. Compressive texture weakened with the increase in the deformation temperature at the strain rate of 0.01 s−1. Most grains with {0001} planes tilted away from the compression direction (CD) gradually. In addition, when the strain rate decreased, the recrystallization degree and average grain size increased. Meanwhile, the dislocation density decreased. Texture appeared to be insensitive to the strain rate. These findings provide valuable insights into the hot compression behavior, microstructural evolution, and texture changes in the Mg–0.6Mn–0.5Al–0.5Zn–0.4Ca alloy, contributing to the understanding of its processing–microstructure–property relationships.
The hot compression behavior of as-extruded Mg–0.6Mn–0.5Al–0.5Zn–0.4Ca alloy was studied on a Gleeble-3500 thermal simulation machine. Experiments were conducted at temperatures ranging from 523 to 673 K and strain rates ranging from 0.001 to 1 s−1. Results showed that an increase in the strain rate or a decrease in deformation temperature led to an increase in true stress. The constitutive equation and processing maps of the alloy were obtained and analyzed. The influence of deformation temperatures and strain rates on microstructural evolution and texture was studied with the assistance of electron backscatter diffraction (EBSD). The as-extruded alloy exhibited a bimodal structure that consisted of deformed coarse grains and fine equiaxed recrystallized structures (approximately 1.57 μm). The EBSD results of deformed alloy samples revealed that the recrystallization degree and average grain size increased as the deformation temperature increased. By contrast, dislocation density and texture intensity decreased. Compressive texture weakened with the increase in the deformation temperature at the strain rate of 0.01 s−1. Most grains with {0001} planes tilted away from the compression direction (CD) gradually. In addition, when the strain rate decreased, the recrystallization degree and average grain size increased. Meanwhile, the dislocation density decreased. Texture appeared to be insensitive to the strain rate. These findings provide valuable insights into the hot compression behavior, microstructural evolution, and texture changes in the Mg–0.6Mn–0.5Al–0.5Zn–0.4Ca alloy, contributing to the understanding of its processing–microstructure–property relationships.
2023, vol. 30, no. 12, pp.
2411-2420.
https://doi.org/10.1007/s12613-023-2676-8
Abstract:
Mg–Zn–Ca–Mn series alloys are developed as promising candidates of 5G communication devices with excellent thermal conductivities, great ductility, and acceptable strength. In present paper, Mg–xZn–0.4Ca–0.2Mn (x = 2wt%, 4wt%, 6wt%) alloys were prepared by a near-solidus extrusion and the effect of Zn content on mechanical and thermal properties were investigated. The results showed that the addition of minor Ca led to the formation of Ca2Mg6Zn3 eutectic phase at grain boundaries. A type of bimodal microstructure occurred in the as-extruded alloys, where elongated coarse deformed grains were embedded in refined recrystallized grains matrix. Correspondingly, both yield strength and ductility of the alloys were significantly enhanced after extrusion due to the great grain refinement. Specially, higher Zn content led to the increment in yield strength and a slight reduction in elongation due to the larger fractions of second phase particles. The room temperature thermal conductivity of as-extruded alloys was also improved compared with that of as-cast counterparts. The increment of Zn content decreased the thermal conductivity of both as-cast and as-extruded alloys, which was due to the increased second phase fraction and solution atoms in the matrix, that hindering the motion of electrons. The as-extruded Mg–2Zn–0.4Ca–0.2Mn (wt%) alloy exhibited the highest elongation of 27.7% and thermal conductivity of 139.2 W/(m·K), combined with an acceptable ultimate tensile strength of 244.0 MPa. The present paper provides scientific guidance for the preparation of lightweight materials with high ductility and high thermal conductivity.
Mg–Zn–Ca–Mn series alloys are developed as promising candidates of 5G communication devices with excellent thermal conductivities, great ductility, and acceptable strength. In present paper, Mg–xZn–0.4Ca–0.2Mn (x = 2wt%, 4wt%, 6wt%) alloys were prepared by a near-solidus extrusion and the effect of Zn content on mechanical and thermal properties were investigated. The results showed that the addition of minor Ca led to the formation of Ca2Mg6Zn3 eutectic phase at grain boundaries. A type of bimodal microstructure occurred in the as-extruded alloys, where elongated coarse deformed grains were embedded in refined recrystallized grains matrix. Correspondingly, both yield strength and ductility of the alloys were significantly enhanced after extrusion due to the great grain refinement. Specially, higher Zn content led to the increment in yield strength and a slight reduction in elongation due to the larger fractions of second phase particles. The room temperature thermal conductivity of as-extruded alloys was also improved compared with that of as-cast counterparts. The increment of Zn content decreased the thermal conductivity of both as-cast and as-extruded alloys, which was due to the increased second phase fraction and solution atoms in the matrix, that hindering the motion of electrons. The as-extruded Mg–2Zn–0.4Ca–0.2Mn (wt%) alloy exhibited the highest elongation of 27.7% and thermal conductivity of 139.2 W/(m·K), combined with an acceptable ultimate tensile strength of 244.0 MPa. The present paper provides scientific guidance for the preparation of lightweight materials with high ductility and high thermal conductivity.
2023, vol. 30, no. 12, pp.
2421-2431.
https://doi.org/10.1007/s12613-023-2683-9
Abstract:
The conversion of agricultural residual biomass into biochar as a sulfur host material for Li–S batteries is a promising approach to alleviate the greenhouse effect and realize waste resource reutilization. However, the large-scale application of pristine biochar is hindered by its low electrical conductivity and limited electrocatalytic sites. This paper addressed these challenges via the construction of Fe–N co-doped biochar (Fe–NOPC) through the copyrolysis of sesame seeds shell and ferric sodium ethylenediaminetetraacetic acid (NaFeEDTA). During the synthesis process, NaFeEDTA was used as an extra carbon resource to regulate the chemical environment of N doping, which resulted in the production of high contents of graphitic, pyridinic, and pyrrolic N and Fe–Nx bonds. When the resulting Fe–NOPC was used as a sulfur host, the pyridinic and pyrrolic N would adjust the surface electron structure of biochar to accelerate the electron/ion transport, and the electropositive graphitic N could be combined with sulfur-related species via electrostatic attraction. Fe–Nx could also promote the redox reaction of lithium polysulfides due to the strong Li–N and S–Fe bonds. Benefiting from these advantages, the resultant Fe–NOPC/S cathode with a sulfur loading of 3.8 mg·cm−2 delivered an areal capacity of 4.45 mAh·cm−2 at 0.1C and retained a capacity of 3.45 mAh·cm−2 at 1C. Thus, this cathode material holds enormous potential for achieving energy-dense Li–S batteries.
The conversion of agricultural residual biomass into biochar as a sulfur host material for Li–S batteries is a promising approach to alleviate the greenhouse effect and realize waste resource reutilization. However, the large-scale application of pristine biochar is hindered by its low electrical conductivity and limited electrocatalytic sites. This paper addressed these challenges via the construction of Fe–N co-doped biochar (Fe–NOPC) through the copyrolysis of sesame seeds shell and ferric sodium ethylenediaminetetraacetic acid (NaFeEDTA). During the synthesis process, NaFeEDTA was used as an extra carbon resource to regulate the chemical environment of N doping, which resulted in the production of high contents of graphitic, pyridinic, and pyrrolic N and Fe–Nx bonds. When the resulting Fe–NOPC was used as a sulfur host, the pyridinic and pyrrolic N would adjust the surface electron structure of biochar to accelerate the electron/ion transport, and the electropositive graphitic N could be combined with sulfur-related species via electrostatic attraction. Fe–Nx could also promote the redox reaction of lithium polysulfides due to the strong Li–N and S–Fe bonds. Benefiting from these advantages, the resultant Fe–NOPC/S cathode with a sulfur loading of 3.8 mg·cm−2 delivered an areal capacity of 4.45 mAh·cm−2 at 0.1C and retained a capacity of 3.45 mAh·cm−2 at 1C. Thus, this cathode material holds enormous potential for achieving energy-dense Li–S batteries.
2023, vol. 30, no. 12, pp.
2432-2440.
https://doi.org/10.1007/s12613-023-2677-7
Abstract:
Exploring and designing a high-performance non-noble metal catalyst for hydrogen evolution reaction (HER) are crucial for the large-scale application of H2 by water electrolysis. Here, novel catalysts with NiMo nanoparticles decorated on reduced graphene oxide (NiMo@rGO) synthesized by a two-step hydrothermal method were reported. Physical characterization results showed that the prepared NiMo@rGO-1 had an irregular lamellar structure, and the NiMo nanoparticles were uniformly dispersed on the rGO. NiMo@rGO-1 exhibited outstanding HER performance in an alkaline environment and required only 93 and 180 mV overpotential for HER in 1.0 M KOH solution to obtain current densities of −10 and −50 mA·cm−2, respectively. Stability tests showed that NiMo@rGO-1 had a certain operating stability for 32 h. Under the same condition, the performance of NiMo@rGO-1 can be comparable with that of commercial Pt/C catalysts at high current density. The synergistic effect between NiMo particles and lamellate graphene can remarkably promote charge transfer in electrocatalytic reactions. As a result, NiMo@rGO-1 presented the advantages of high intrinsic activity, large specific surface area, and small electrical impedance. The lamellar graphene played a role in dispersion to prevent the aggregation of nanoparticles. The prepared NiMo@rGO-1 can be used in anion exchange membrane water electrolysis to produce hydrogen. This study provides a simple preparation method for efficient and low-cost water electrolysis to produce hydrogen in the future.
Exploring and designing a high-performance non-noble metal catalyst for hydrogen evolution reaction (HER) are crucial for the large-scale application of H2 by water electrolysis. Here, novel catalysts with NiMo nanoparticles decorated on reduced graphene oxide (NiMo@rGO) synthesized by a two-step hydrothermal method were reported. Physical characterization results showed that the prepared NiMo@rGO-1 had an irregular lamellar structure, and the NiMo nanoparticles were uniformly dispersed on the rGO. NiMo@rGO-1 exhibited outstanding HER performance in an alkaline environment and required only 93 and 180 mV overpotential for HER in 1.0 M KOH solution to obtain current densities of −10 and −50 mA·cm−2, respectively. Stability tests showed that NiMo@rGO-1 had a certain operating stability for 32 h. Under the same condition, the performance of NiMo@rGO-1 can be comparable with that of commercial Pt/C catalysts at high current density. The synergistic effect between NiMo particles and lamellate graphene can remarkably promote charge transfer in electrocatalytic reactions. As a result, NiMo@rGO-1 presented the advantages of high intrinsic activity, large specific surface area, and small electrical impedance. The lamellar graphene played a role in dispersion to prevent the aggregation of nanoparticles. The prepared NiMo@rGO-1 can be used in anion exchange membrane water electrolysis to produce hydrogen. This study provides a simple preparation method for efficient and low-cost water electrolysis to produce hydrogen in the future.
2023, vol. 30, no. 12, pp.
2441-2450.
https://doi.org/10.1007/s12613-023-2703-9
Abstract:
The multiple quantum transitions within d-band correlation oxides such as rare-earth nickelates (RENiO3) triggered by critical temperatures and/or hydrogenation opened up a new paradigm for correlated electronics applications, e.g. ocean electric field sensor, bio-sensor, and neuron synapse logical devices. Nevertheless, these applications are obstructed by the present ineffectiveness in the thin film growth of the metastable RENiO3 with flexibly adjustable rare-earth compositions and electronic structures. Herein, we demonstrate a metal-organic decompositions (MOD) approach that can effectively grow metastable RENiO3 covering a large variety of the rare-earth composition without introducing any vacuum process. Unlike the previous chemical growths for RENiO3 relying on strict interfacial coherency that limit the film thickness, the MOD growth using reactive isooctanoate percussors is tolerant to lattice defects and therefore achieves comparable film thickness to vacuum depositions. Further indicated by positron annihilation spectroscopy, the RENiO3 grown by MOD exhibit large amount of lattice defects that improves their hydrogen incorporation amount and electron transfers, as demonstrated by the resonant nuclear reaction analysis and near edge X-ray absorption fine structure analysis. This effectively enlarges the magnitude in the resistance regulations in particular for RENiO3 with lighter RE, shedding a light on the extrinsic regulation of the hydrogen induced quantum transitions for correlated oxides semiconductors kinetically via defect engineering.
The multiple quantum transitions within d-band correlation oxides such as rare-earth nickelates (RENiO3) triggered by critical temperatures and/or hydrogenation opened up a new paradigm for correlated electronics applications, e.g. ocean electric field sensor, bio-sensor, and neuron synapse logical devices. Nevertheless, these applications are obstructed by the present ineffectiveness in the thin film growth of the metastable RENiO3 with flexibly adjustable rare-earth compositions and electronic structures. Herein, we demonstrate a metal-organic decompositions (MOD) approach that can effectively grow metastable RENiO3 covering a large variety of the rare-earth composition without introducing any vacuum process. Unlike the previous chemical growths for RENiO3 relying on strict interfacial coherency that limit the film thickness, the MOD growth using reactive isooctanoate percussors is tolerant to lattice defects and therefore achieves comparable film thickness to vacuum depositions. Further indicated by positron annihilation spectroscopy, the RENiO3 grown by MOD exhibit large amount of lattice defects that improves their hydrogen incorporation amount and electron transfers, as demonstrated by the resonant nuclear reaction analysis and near edge X-ray absorption fine structure analysis. This effectively enlarges the magnitude in the resistance regulations in particular for RENiO3 with lighter RE, shedding a light on the extrinsic regulation of the hydrogen induced quantum transitions for correlated oxides semiconductors kinetically via defect engineering.
2023, vol. 30, no. 12, pp.
2451-2458.
https://doi.org/10.1007/s12613-023-2738-y
Abstract:
The commercialized poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) is usually used as hole transport layers (HTLs) in tin-based perovskite solar cells (TPSCs). However, the further development has been restricted due to the acidity that could damage the stability of TPSCs. Although the PEDOT:PSS solution can be diluted by water to decrease acidity and reduce the cost of device fabrication, the electrical conductivity will decrease obviously in diluted PEDOT:PSS solution. Herein, potassium thiocyanate (KSCN) is selected to regulate the properties of PEDOT:PSS HTLs from the diluted PEDOT:PSS aqueous solution by water with a volume ratio of 1:1 to prepare efficient TPSCs. The effect of KSCN addition on the structure and photoelectrical properties of PEDOT:PSS HTLs and TPSCs have been systematically studied. At the optimal KSCN concentration, the TPSCs based on KSCN-doped PEDOT:PSS HTLs (KSCN-PSCs) demonstrate the champion power conversion efficiency (PCE) of 8.39%, while the reference TPSCs only show a champioan PCE of 6.70%. The further analysis demonstrates that the KSCN additive increases the electrical conductivity of HTLs prepared by the diluted PEDOT:PSS solution, improves the microstructure of perovskite film, and inhibits carrier recombination in TPSCs, leading to the reduced hysteresis effect and enhanced PCE in KSCN-PSCs. This work gives a low-cost and practical strategy to develop a high-quality PEDOT:PSS HTLs from diluted PEDOT:PSS aqueous solution for efficient TPSCs.
The commercialized poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) is usually used as hole transport layers (HTLs) in tin-based perovskite solar cells (TPSCs). However, the further development has been restricted due to the acidity that could damage the stability of TPSCs. Although the PEDOT:PSS solution can be diluted by water to decrease acidity and reduce the cost of device fabrication, the electrical conductivity will decrease obviously in diluted PEDOT:PSS solution. Herein, potassium thiocyanate (KSCN) is selected to regulate the properties of PEDOT:PSS HTLs from the diluted PEDOT:PSS aqueous solution by water with a volume ratio of 1:1 to prepare efficient TPSCs. The effect of KSCN addition on the structure and photoelectrical properties of PEDOT:PSS HTLs and TPSCs have been systematically studied. At the optimal KSCN concentration, the TPSCs based on KSCN-doped PEDOT:PSS HTLs (KSCN-PSCs) demonstrate the champion power conversion efficiency (PCE) of 8.39%, while the reference TPSCs only show a champioan PCE of 6.70%. The further analysis demonstrates that the KSCN additive increases the electrical conductivity of HTLs prepared by the diluted PEDOT:PSS solution, improves the microstructure of perovskite film, and inhibits carrier recombination in TPSCs, leading to the reduced hysteresis effect and enhanced PCE in KSCN-PSCs. This work gives a low-cost and practical strategy to develop a high-quality PEDOT:PSS HTLs from diluted PEDOT:PSS aqueous solution for efficient TPSCs.
Research ArticleOpen Access
2023, vol. 30, no. 12, pp.
2459-2468.
https://doi.org/10.1007/s12613-023-2655-0
Abstract:
In the last decades, vanadium alloyed coatings have been introduced as potential candidates for self-lubrication due to their perfect tribological properties. In this work, the influence of V incorporation on the wear performance and oxidation resistance of TiSiN/CrN film coatings deposited by direct current (DC) reactive magnetron sputtering is investigated. The results show that vanadium incorporation significantly decreases the oxidation resistance of the coatings. In general, two layers are formed during the oxidation process: i) Ti(V)O2 on top, followed by a protective layer, which is subdivided into two layers, Cr2O3 and Si–O. ii) The diffusion of V controls the oxidation of V-containing coatings. The addition of vanadium improves the wear resistance of coatings, and the wear rate decreases with increasing V content in the coatings; however, the friction coefficient is independent of the chemical composition of the coatings. The wear of the V-containing coatings is driven by polishing wear.
In the last decades, vanadium alloyed coatings have been introduced as potential candidates for self-lubrication due to their perfect tribological properties. In this work, the influence of V incorporation on the wear performance and oxidation resistance of TiSiN/CrN film coatings deposited by direct current (DC) reactive magnetron sputtering is investigated. The results show that vanadium incorporation significantly decreases the oxidation resistance of the coatings. In general, two layers are formed during the oxidation process: i) Ti(V)O2 on top, followed by a protective layer, which is subdivided into two layers, Cr2O3 and Si–O. ii) The diffusion of V controls the oxidation of V-containing coatings. The addition of vanadium improves the wear resistance of coatings, and the wear rate decreases with increasing V content in the coatings; however, the friction coefficient is independent of the chemical composition of the coatings. The wear of the V-containing coatings is driven by polishing wear.
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