Formation and Annihilation of Stacking Faults in Silicon Carbide

在高温烧结过程中，sic层错的湮灭与晶粒生长同时发生。利用Avrami-Erofeev方程分析了层错的湮灭速率过程，表明层错的湮灭速率受原子扩散过程的控制。另一方面，晶粒的生长速度受到表面扩散率的限制。这两个过程的活化能值的一致表明，层错的湮灭是晶粒生长受表面扩散率控制的微观结构演化的一个明显现象。加热过程中氮的加入抑制了表面扩散系数，从而抑制了层错湮灭的速率。研究了碳热还原法合成β - sic过程中层错的形成，发现合成的粉末中存在晶须和球形两种形貌，晶须中的层错比球形颗粒中的层错多。

Annihilation of stacking faults in beta-SiC was found to occur simultaneously with grain growth during high-temperature sintering. Analyzes of the rate process by use of the Avrami-Erofeev equation indicated that the rate of annihilation of stacking faults was controlled by the atomic diffusion process. The rate of grain growth, on the other hand, was found to be limited by surface diffusivity. Coincidence in the values of activation energy for the two processes suggested that the annihilation of stacking faults is an apparent phenomenon resulting from the microstructural evolution in which the grain growth is controlled by surface diffusivity. Incorporation of nitrogen during heating suppressed the surface diffusivity and hence, the rate of stacking fault annihilation. Formation of stacking faults during the synthesis of beta-SiC by cabothermal reduction of silica was also investigated and we found that two kinds of morphology, whisker and sphere, were always observed for the synthesized powder, and that a larger amount of stacking faults were containde in whiskers than in spherical particles.