碳热还原二氧化硅过程的机理分析

Abstract

本文将C(石墨)和SiO2制成扩散偶，在高温下研究了SiO2的还原机理。结果表明，C(石墨)和SiO2的界面反应主要为SiO2 + C(graphite ) = Si + CO，C的气化反应的存在抑制了C(石墨)和SiO2之间的其他反应的发生。Si层厚与时间的反应关系表明，在最初的2 h过程中，线性生长机理占优势，其斜率接近于1，反应为界面反应控制；但是，当生长相厚度超过一个临界值时，生成层以抛物线机理生长，斜率接近于0.5，反应为扩散控制。 In this paper, the Carbothermal reduction mechanism of SiO2 at high temperature is studied under diffusion couple of C(graphite) and SiO2. It was found that the solid reaction of SiO2 + C(graphite) = Si + CO is the main reduction process. The gasification reaction of C suppresses other reaction between SiO2 and C(graphite). The relation between Si layer thickness and time shows that the linear growth mechanism is dominant in the initial 2 h process, the slope is close to 1, and the reaction is con-trolled by the interfacial reaction; However, when the appearance thickness exceeds a critical value, the growth layer grows in a parabolic mechanism, slope is close to 0.5, and the reaction is controlled by the C diffusion.