中文摘要：

以高纯二氧化硅为原料,高纯石墨为阳极,磁场中旋转的镁锌合金为阴极,电解制备镁硅锌合金。通过真空蒸馏分离合金得到了纯度较高的多晶硅。采用熔盐电解监控仪和Teslameter对电流密度、槽电压、反电动势和磁场强度参数进行测量,研究了电磁搅拌在阴极合金反应过程中的作用,电解过程中的反电动势、电流效率及产物硅浓度的变化。结果表明：1 000℃,25 mT的磁场强度下,0.56 A/cm2电解4 h制得硅含量高达35.7%的Mg-Zn-Si合金。将该合金在1 050℃真空蒸馏3 h,最终制得硅纯度达99.98%的多晶硅。

英文摘要：

Mg-Zn-Si alloys were prepared with a high purity graphite as an anode,the rolling Mg-Zn alloys in magnetic field as a cathode and high purity silicon dioxide as raw material in an electrolysis method.Then polysilicon obtained was separated from Mg-Zn-Si alloys by vacuum distillation.The current density,cell voltage and back electromotive force were measured by a DD-A testing device of molten salt electrolysis,and the magnetic field strength was determined by a Teslameter.The electromagnetic stirring effect on cathode alloy reaction,the change of back electromotive force,current efficiency and silicon concentration were investigated.The silicon content of 35.7%（mass fraction） in Mg-Zn-Si alloy was firstly obtained by electrolyzing for 4 h in the current density of 0.56 A/cm2 at 1 000 ℃ and 28 mT,and then the polysilicon of 99.98% was obtained by vacuum distillation for 3 h at 1 050 ℃.