Hypereutectic Al-17.5Si （wt pct） and Al-25Si （wt pct） alloys with various content of rare earth Er were prepared by conventional casting technique. The effect of Er on the microstructure and properties of the hype...Hypereutectic Al-17.5Si （wt pct） and Al-25Si （wt pct） alloys with various content of rare earth Er were prepared by conventional casting technique. The effect of Er on the microstructure and properties of the hypereutectic Al-Si alloys was investigated using optical microscopy, scanning electron microscopy as well as friction and wear tests. It was found that optimal amount of Er exists in modifying the hypereutectic Al-Si alloys. An appropriate addition of Er improved the anti-wear properties, and reduced the friction coefficient of the hypereutectic Al-Si alloys studied. The primary silicon crystals in the hypereutectic Al-Si alloys were refined with the suitable addition of Er element. The modification mechanism was also discussed in this paper.展开更多
Copper was extracted from methylchlorosilane slurry residue by a direct hydrogen peroxide leaching method.A number of experimental parameters were analyzed to determine the extraction efficiency of copper.The extracti...Copper was extracted from methylchlorosilane slurry residue by a direct hydrogen peroxide leaching method.A number of experimental parameters were analyzed to determine the extraction efficiency of copper.The extraction efficiency of copper reached 98.5%under the optimal leaching conditions,such as the hydrogen peroxide concentration of 1.875 mol·L^(-1),the leaching temperature of 323 K,the liquid–solid ratio of 20 ml·g^(-1),and the stirring speed of 300 r·min^(-1).The leaching kinetics of the copper extraction process was then described by the shrinking core model.There were two stages.The first stage was controlled by chemical reactions,while the second stage was controlled by interface transfer and product layer diffusion.The activation energy and kinetic control equations were determined,as well as an explanation of the leaching mechanism of copper extraction based on kinetic analysis and materials characterization.Copper resources can be recovered from the methylchlorosilane slurry residue efficiently and inexpensively with the methods used in this study.展开更多
FeCoxNiCuAl （x values in molar ratio, x=0.2, 0.5, 1, 1.5, 2 and 3） alloys were pre- pared using a suck-casting method. The effect of Co element on phase constituents, microstructure and mechanical properties of the ...FeCoxNiCuAl （x values in molar ratio, x=0.2, 0.5, 1, 1.5, 2 and 3） alloys were pre- pared using a suck-casting method. The effect of Co element on phase constituents, microstructure and mechanical properties of the FeCox NiCuA1 alloys was investigated using X-ray diffraction, scanning electron microscopy, optical microscopy and com- pressive tests. It was found that the Co addition has a significant influence on the structure and properties of the FeCo^NiCuA1 alloys. The alloys have typical den- drite microstructure, and are composed of a simple fcc structure and bcc structure. The addition of Co promotes the formation of fcc phase in the alloys, retards the compressive strength and hardness of the alloys, and enhances the plasticity of the alloys.展开更多
基金supported by the National Key Technology R&D Program of China(No.2009BAE80B00)
文摘Hypereutectic Al-17.5Si （wt pct） and Al-25Si （wt pct） alloys with various content of rare earth Er were prepared by conventional casting technique. The effect of Er on the microstructure and properties of the hypereutectic Al-Si alloys was investigated using optical microscopy, scanning electron microscopy as well as friction and wear tests. It was found that optimal amount of Er exists in modifying the hypereutectic Al-Si alloys. An appropriate addition of Er improved the anti-wear properties, and reduced the friction coefficient of the hypereutectic Al-Si alloys studied. The primary silicon crystals in the hypereutectic Al-Si alloys were refined with the suitable addition of Er element. The modification mechanism was also discussed in this paper.
基金supported by the National Key Research and Development Program of China (2018YFC1901804 and 2018YFC1901805)the National Natural Science Foundation of China (21978045 and U1902219)。
文摘Copper was extracted from methylchlorosilane slurry residue by a direct hydrogen peroxide leaching method.A number of experimental parameters were analyzed to determine the extraction efficiency of copper.The extraction efficiency of copper reached 98.5%under the optimal leaching conditions,such as the hydrogen peroxide concentration of 1.875 mol·L^(-1),the leaching temperature of 323 K,the liquid–solid ratio of 20 ml·g^(-1),and the stirring speed of 300 r·min^(-1).The leaching kinetics of the copper extraction process was then described by the shrinking core model.There were two stages.The first stage was controlled by chemical reactions,while the second stage was controlled by interface transfer and product layer diffusion.The activation energy and kinetic control equations were determined,as well as an explanation of the leaching mechanism of copper extraction based on kinetic analysis and materials characterization.Copper resources can be recovered from the methylchlorosilane slurry residue efficiently and inexpensively with the methods used in this study.
基金supported by the National Natural Science Foundation of China (Grant No.51171041)the Fundamental Research Funds for the Central University (Grant No.N100409001)
文摘FeCoxNiCuAl （x values in molar ratio, x=0.2, 0.5, 1, 1.5, 2 and 3） alloys were pre- pared using a suck-casting method. The effect of Co element on phase constituents, microstructure and mechanical properties of the FeCox NiCuA1 alloys was investigated using X-ray diffraction, scanning electron microscopy, optical microscopy and com- pressive tests. It was found that the Co addition has a significant influence on the structure and properties of the FeCo^NiCuA1 alloys. The alloys have typical den- drite microstructure, and are composed of a simple fcc structure and bcc structure. The addition of Co promotes the formation of fcc phase in the alloys, retards the compressive strength and hardness of the alloys, and enhances the plasticity of the alloys.
