By using cyclic and linear sweep voltammetry,the electrochemical deposition behaviors of Mg^2＋ and B^3＋ in fluorides molten salts of KF-MgF2 and KF-KBF4 at 880℃ were investigated,respectively.The results show that ...By using cyclic and linear sweep voltammetry,the electrochemical deposition behaviors of Mg^2＋ and B^3＋ in fluorides molten salts of KF-MgF2 and KF-KBF4 at 880℃ were investigated,respectively.The results show that the electrochemical reduction of Mg^2＋ is a one-step reaction as Mg^2＋＋2e-→Mg in KF-1%MgF2 molten salt,and the electrochemical reduction of B^3＋ is also a one-step reaction as B^3＋＋3e-→B in KF-KBF4 （1%,2% KBF4） molten salts.Both the cathodic reduction reactions of Mg^2＋ and B^3＋ are controlled by diffusion process.The diffusion coefficients of Mg^2＋ in KF-MgF2 molten salts and B^3＋ in KF-KBF4 molten salts are 6.8×10^-7 cm^2/s and 7.85×10^-7 cm^2/s,respectively.Moreover,the electrochemical synthesis of MgB2 by co-deposition of Mg and B was carried out in the KF-MgF2-KBF4 （molar ratio of 6：1：2） molten salt at 750℃.The X-ray diffraction analysis indicates that MgB2 can be deposited on graphite cathode in the KF-MgF2-KBF4 molten salt at 750℃.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
基金Project(50804010) supported by the National Natural Science Foundation of ChinaProject(2007CB210305) supported by the National Basic Research Program of China
文摘By using cyclic and linear sweep voltammetry,the electrochemical deposition behaviors of Mg^2＋ and B^3＋ in fluorides molten salts of KF-MgF2 and KF-KBF4 at 880℃ were investigated,respectively.The results show that the electrochemical reduction of Mg^2＋ is a one-step reaction as Mg^2＋＋2e-→Mg in KF-1%MgF2 molten salt,and the electrochemical reduction of B^3＋ is also a one-step reaction as B^3＋＋3e-→B in KF-KBF4 （1%,2% KBF4） molten salts.Both the cathodic reduction reactions of Mg^2＋ and B^3＋ are controlled by diffusion process.The diffusion coefficients of Mg^2＋ in KF-MgF2 molten salts and B^3＋ in KF-KBF4 molten salts are 6.8×10^-7 cm^2/s and 7.85×10^-7 cm^2/s,respectively.Moreover,the electrochemical synthesis of MgB2 by co-deposition of Mg and B was carried out in the KF-MgF2-KBF4 （molar ratio of 6：1：2） molten salt at 750℃.The X-ray diffraction analysis indicates that MgB2 can be deposited on graphite cathode in the KF-MgF2-KBF4 molten salt at 750℃.
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.
