The growth mechanism of paramorphic SiC whisker (SiCw) and SiC particle (SiCp) produced from rice bulls under the catalytic actions is studied. The results indicate that the growtb mechanism of the SiCw is vapour-liqu...The growth mechanism of paramorphic SiC whisker (SiCw) and SiC particle (SiCp) produced from rice bulls under the catalytic actions is studied. The results indicate that the growtb mechanism of the SiCw is vapour-liquid-solid (VLS) , while the crystalline structure of the SiCw is β-SiC. Some SiCp will be formed during the production of the SiCw. Under the pilot-plant condition, the grade of SiCw is over 20%, and SiCp is over 50%. The micron-grade of SiCw and SiCp are separated successfully by flotation and other traditional mineral separation and purification technology. So the grade of the high purity SiCw is over 95 %.展开更多
The microstructures and properties of A1-45%Si alloy prepared by liquid-solid separation （LSS） process and spray deposition （SD） were studied. The results show that the size, shape and distribution of the primary ...The microstructures and properties of A1-45%Si alloy prepared by liquid-solid separation （LSS） process and spray deposition （SD） were studied. The results show that the size, shape and distribution of the primary Si phase have different influence on the properties of alloys. Comparing with the Si particles with irregular shape, fine size and continuous distribution in SD alloy, the primary Si phase in LSS alloy is sphere-like, coarse and surrounded by the continuous AI matrix. The microstructure features of LSS alloy are beneficial to the higher thermal conductivity and lower thermal expansion coefficient at room temperature. The fine Si particle in SD alloy is advantageous to improving the mechanical properties. The increasing rates of thermal expansion coefficient with temperature are influenced by the distribution of the Si particles, where a lower rate is obtained in SD alloy with continuous Si particles. The agreement of thermal expansion coefficient with the model in LSS alloy differs from that in the SD alloy because of the different microstructure characteristics.展开更多
得益于高效率优势,混合SiC/Si有源钳位(active neutral point clamped,ANPC)三电平电路拓扑在光储发电系统中应用广泛。但传统混合SiC/Si功率模块中,Si器件的使用限制了效率提升,SiC器件引入后又可能导致热分布不均、电压过冲及振荡等...得益于高效率优势,混合SiC/Si有源钳位(active neutral point clamped,ANPC)三电平电路拓扑在光储发电系统中应用广泛。但传统混合SiC/Si功率模块中,Si器件的使用限制了效率提升,SiC器件引入后又可能导致热分布不均、电压过冲及振荡等问题。提出了一种综合设计方法,结合功率器件损耗均衡与功率模块布局寄生电感优化,以提高混合SiC/Si ANPC电路拓扑的功率模块性能。建立了功率模块损耗模型,并进行热性能优化,降低结温与芯片温差;构建了寄生电感模型,通过优化设计减小寄生电感;研制了基于ANPC拓扑的混合SiC/Si功率模块,并开展电热性能测试。实验结果验证了功率模块在损耗、寄生电感及热分布方面的显著优势。展开更多
The iron-rich solids formed during solidification of Al-Si alloys which are known to be detrimental to the mechanical,physical and chemical properties of the alloys should be removed.On the other hand,Al-Si hypereutec...The iron-rich solids formed during solidification of Al-Si alloys which are known to be detrimental to the mechanical,physical and chemical properties of the alloys should be removed.On the other hand,Al-Si hypereutectic alloys are used to extract the pure primary silicon which is suitable for photovoltaic cells in the solvent refining process.One of the important issues in iron removal and in solvent refining is the effective separation of the crystallized solids from the Al-Si alloy melts.This paper describes the separation methods of the primary solids from Al-Si alloy melts such as sedimentation,draining,filtration,electromagnetic separation and centrifugal separation,focused on the iron removal and on the separation of silicon in the solvent refining process.展开更多
The effects of directional solidification parameters and the coupling of directional solidification parameters and alternating electromagnetic fields on separation and enrichment of the C54–TiSi2 phase were investiga...The effects of directional solidification parameters and the coupling of directional solidification parameters and alternating electromagnetic fields on separation and enrichment of the C54–TiSi2 phase were investigated in a directionally solidified hypoeutectic Ti–65 wt.%Si alloy.The results indicated that by increasing the pull-down velocity at a given position within the ingot,the cooling rate,growth rate,and temperature gradient of ingot could be increased.At a pull-down velocity near 5μm/s,the temperature gradient,cooling rate,and growth rate decreased with increasing the thickness of the C54–TiSi2-rich layer.Electromagnetic fields enhanced mass transfer at pull-down velocities of 5,10,15,and 20μm/s,with resulting enriched layer thicknesses of 15,10,10,and 5 mm,respectively.By increasing the percentage of Ti in the Ti–Si alloy from 25 to 35 wt.%,the thickness of the C54–TiSi2-rich layer was increased from 2.5 to 3.3 cm.However,the maximum C54–TiSi2 content obtained experimentally in this layer decreased from 92.06 to 79.49 mass%.展开更多
The recycling of high Fe-content Al-Si alloys is a green industry. Eliminating the harmful effect of Fe, achieving the separation of Al and Fe is one of the key problems. Different from traditional methods for iron re...The recycling of high Fe-content Al-Si alloys is a green industry. Eliminating the harmful effect of Fe, achieving the separation of Al and Fe is one of the key problems. Different from traditional methods for iron removal, a novel method using magnesium melt to separate Al and Fe is proposed. By introducing Al-14Si-5Fe alloy into Mg melt, it was found that the γ-Al3.5FeSi phase evolves to Al3SiFe3.5 and Al5Fe2 through the melting and solidification process. Compared with the primary Al-rich γ-Al3.5FeSi phase, the formation of Fe-rich A13SiFe3.5 is quite beneficial for the separation of Al and Fe. Mg-Si-Al and Mg-Si-Fe alloys can be obtained at the top and bottom of the cooled ingot, respectively. The results in this study provide meaningful suggestions for recycling scrap Al-Si-Fe materials.展开更多
文摘The growth mechanism of paramorphic SiC whisker (SiCw) and SiC particle (SiCp) produced from rice bulls under the catalytic actions is studied. The results indicate that the growtb mechanism of the SiCw is vapour-liquid-solid (VLS) , while the crystalline structure of the SiCw is β-SiC. Some SiCp will be formed during the production of the SiCw. Under the pilot-plant condition, the grade of SiCw is over 20%, and SiCp is over 50%. The micron-grade of SiCw and SiCp are separated successfully by flotation and other traditional mineral separation and purification technology. So the grade of the high purity SiCw is over 95 %.
文摘The microstructures and properties of A1-45%Si alloy prepared by liquid-solid separation （LSS） process and spray deposition （SD） were studied. The results show that the size, shape and distribution of the primary Si phase have different influence on the properties of alloys. Comparing with the Si particles with irregular shape, fine size and continuous distribution in SD alloy, the primary Si phase in LSS alloy is sphere-like, coarse and surrounded by the continuous AI matrix. The microstructure features of LSS alloy are beneficial to the higher thermal conductivity and lower thermal expansion coefficient at room temperature. The fine Si particle in SD alloy is advantageous to improving the mechanical properties. The increasing rates of thermal expansion coefficient with temperature are influenced by the distribution of the Si particles, where a lower rate is obtained in SD alloy with continuous Si particles. The agreement of thermal expansion coefficient with the model in LSS alloy differs from that in the SD alloy because of the different microstructure characteristics.
文摘得益于高效率优势,混合SiC/Si有源钳位(active neutral point clamped,ANPC)三电平电路拓扑在光储发电系统中应用广泛。但传统混合SiC/Si功率模块中,Si器件的使用限制了效率提升,SiC器件引入后又可能导致热分布不均、电压过冲及振荡等问题。提出了一种综合设计方法,结合功率器件损耗均衡与功率模块布局寄生电感优化,以提高混合SiC/Si ANPC电路拓扑的功率模块性能。建立了功率模块损耗模型,并进行热性能优化,降低结温与芯片温差;构建了寄生电感模型,通过优化设计减小寄生电感;研制了基于ANPC拓扑的混合SiC/Si功率模块,并开展电热性能测试。实验结果验证了功率模块在损耗、寄生电感及热分布方面的显著优势。
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF),the Ministry of Education,Science and Technology of Korea(No.2012R1A1A2007476)supported by the Korea University of Technology and Education
文摘The iron-rich solids formed during solidification of Al-Si alloys which are known to be detrimental to the mechanical,physical and chemical properties of the alloys should be removed.On the other hand,Al-Si hypereutectic alloys are used to extract the pure primary silicon which is suitable for photovoltaic cells in the solvent refining process.One of the important issues in iron removal and in solvent refining is the effective separation of the crystallized solids from the Al-Si alloy melts.This paper describes the separation methods of the primary solids from Al-Si alloy melts such as sedimentation,draining,filtration,electromagnetic separation and centrifugal separation,focused on the iron removal and on the separation of silicon in the solvent refining process.
基金This research was supported by the National Natural Science Foundation of China(No.U1702251)Special Funds of State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization(Grant No.CNMRCUTS1604)+2 种基金the Program for Innovative Research Team in University of Ministry of Education of China(No.IRT_17R48)Key Laboratory of Comprehensive Utilization of Vanadium and Titanium Resources in Sichuan Province(2019FTSZ06)the PhD Fund of Panzhihua University,and Funded by the State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization.
文摘The effects of directional solidification parameters and the coupling of directional solidification parameters and alternating electromagnetic fields on separation and enrichment of the C54–TiSi2 phase were investigated in a directionally solidified hypoeutectic Ti–65 wt.%Si alloy.The results indicated that by increasing the pull-down velocity at a given position within the ingot,the cooling rate,growth rate,and temperature gradient of ingot could be increased.At a pull-down velocity near 5μm/s,the temperature gradient,cooling rate,and growth rate decreased with increasing the thickness of the C54–TiSi2-rich layer.Electromagnetic fields enhanced mass transfer at pull-down velocities of 5,10,15,and 20μm/s,with resulting enriched layer thicknesses of 15,10,10,and 5 mm,respectively.By increasing the percentage of Ti in the Ti–Si alloy from 25 to 35 wt.%,the thickness of the C54–TiSi2-rich layer was increased from 2.5 to 3.3 cm.However,the maximum C54–TiSi2 content obtained experimentally in this layer decreased from 92.06 to 79.49 mass%.
基金financially supported by the National Natural Science Foundation of China (No. 51601106)the Fundamental Research Funds of Shandong UniversityChina Postdoctoral Science Foundation (No. 2016M600536)
文摘The recycling of high Fe-content Al-Si alloys is a green industry. Eliminating the harmful effect of Fe, achieving the separation of Al and Fe is one of the key problems. Different from traditional methods for iron removal, a novel method using magnesium melt to separate Al and Fe is proposed. By introducing Al-14Si-5Fe alloy into Mg melt, it was found that the γ-Al3.5FeSi phase evolves to Al3SiFe3.5 and Al5Fe2 through the melting and solidification process. Compared with the primary Al-rich γ-Al3.5FeSi phase, the formation of Fe-rich A13SiFe3.5 is quite beneficial for the separation of Al and Fe. Mg-Si-Al and Mg-Si-Fe alloys can be obtained at the top and bottom of the cooled ingot, respectively. The results in this study provide meaningful suggestions for recycling scrap Al-Si-Fe materials.
