工业硅中杂质相的微观结构及分布规律研究

工业硅中杂质相成分及比例直接影响有机硅单体合成的活性与选择性. 因此，研究杂质相与杂质含量的对应关系尤为重要. 本文通过扫描电镜（SEM）和能量色散X射线光谱仪（EDX）对精炼前和精炼后工业硅中夹杂物微观结构及赋存状态进行了研究. 由于精炼前工业硅的Ca和Al含量较高，其杂质相主要以Si2Al2Ca、Si-Al-Ca和Si8Al6Fe4Ca等为主；而精炼后Fe为主要元素，故其析出相主要包括FeSi2(Al)、FeSi2Ti和Si8Al6Fe4Ca等. 此外，本文通过Image Pro Plus进行统计，得到精炼前硅中Si2Al2Ca和Si8Al6Fe4Ca相分别占夹杂物成分的48%和30%，而精炼后硅中FeSi2(Al)相占比68%，唯一含Ca相（Si8Al6Fe4Ca）仅占夹杂物含量的7%. 本文将精炼前和精炼后的工业硅中杂质相成分及比例进行比较，意为寻找硅中杂质含量对杂质相的影响规律，以制备最佳的下游有机硅用工业硅原料.

Study on the microstructure and distribution of impurity phases in metallurgical grade silicon

The compositions and contents of precipitates in metallurgical grade silicon (MG-Si) directly affect the activity and selectivity of silicone monomer synthesis. Therefore, it is particularly significant to investigate the relationship between impurity content and precipitates correspondence in MG-Si. In this study, the microstructures and distributions of precipitates in MG-Si before and after refining are investigated by using scanning electron microscope (SEM) and energy dispersive X-Ray spectroscopy (EDX). It is found that due to the high content of Ca and Al contents in MG-Si before refining, its impurity phases are mainly Si2Al2Ca, Si-Al-Ca, Si8Al6Fe4Ca etc., but after refining, Fe is the main element in MG-Si, so its phases mainly include FeSi2(Al), FeSi2Ti, Si8Al6Fe4Ca, etc. In addition, the statistics conducted by Image Pro Plus show that the Si2Al2Ca and Si8Al6Fe4Ca phases account for respectively 48% and 30% of the precipitates composition before refining, while the FeSi2(Al) phase accounts for 68% after refining, and the only Ca-containing phase (Si8Al6Fe4Ca) accounts for 7% of the precipitates content. Here we compare the compositions and proportions of precipitates in MG-Si before and after refining, in order to explore the law of impurity content on precipitated phases, so as to prepare the best downstream MG-Si raw material for silicones.