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采用电子束熔炼工艺提纯了冶金级硅材料。硅中重要杂质元素Al在制备铸锭中的分布不均匀,呈现出由底部到顶部、由边缘到中心的富集趋势。铸锭边缘部位的杂质Al含量最低,已经低于ICP-AES的探测极限(1×10~(-5)%)。对杂质Al的挥发去除过程进行了理论分析。由Langmuir方程和Henry定律导出了杂质Al的去除率与熔体表面温度、熔炼时间的关系式,该关系式表明杂质Al的去除率会随着熔体表面温度升高、熔炼时间延长而增加,其理论计算值与实测结果符合的较好。
Purification of metallurgical grade silicon by electron beam melting process. The distribution of Al, which is an important impurity element in silicon, is not uniform in the preparation of ingot. It shows the tendency of enrichment from the bottom to the top and from the edge to the center. The lowest Al content in the ingot edge is below the detection limit of ICP-AES (1 × 10 -5%). The volatilization removal process of impurity Al was theoretically analyzed. According to the Langmuir equation and the Henry’s law, the relationship between the removal rate of Al and the surface temperature and the melting time is deduced. The relationship shows that the removal rate of Al increases with the increase of the surface temperature and melting time, The calculated value is in good agreement with the measured data.