高能微波辐照条件下SiC晶粒的生长过程分析

利用高能真空微波辐照, 仅以SiO₂和人造石墨粉为原料, 便捷快速地合成得到结晶良好的β-SiC晶粒。在利用各种表征手段综合分析SiC晶粒微观结构的基础上, 确认高能微波辐照条件下, β-SiC晶粒的生长过程符合“光滑界面的二维形核生长”机制。借助于电子背散射衍射技术(EBSD)进行的原位解析发现, 生长最快的{211}面在晶粒长大过程中逐渐被超覆, 通过形成{421}过渡晶面而最终演变为{220}晶面, 并成为晶粒的侧面; 而生长最慢的{111}面则成为最后保留下来的六角形规则晶面。EBSD的解析结果为SiC晶粒生长过程中晶面演变提供了直接的实验证据。

Growth Process of SiC Grains Prepared by High-energy Microwave Irradiation

High-energy vacuum microwave irradiation was directly applied to synthesize silicon carbide (SiC). Results indicated that the well-crystallized β-SiC grains can be obtained rapidly and conveniently via microwave approach, even simply constituents covering silica dioxide powders and artificial graphite were employed as raw materials. Based on the comprehensive micro-structural characterizations, the formation of β-SiC, under high-energy vacuum microwave irradiation, could be properly explained by the mechanism of two-dimension nucleation and growth. Besides, the technology of electron backscattered diffraction (EBSD) was particularly used to characterize the crystal plane of the observed SiC grains. The corresponding calculation of Euler angles suggested that the fastest-growing crystal planes {211} should be overlapped gradually, and the evolution from {211} to {220} crystal planes should be realized through the formation of {421} transformation plane. The most stable crystal planes of {111} became the regular hexagonal planes in the end, which can be explained by the Bravis rule. Correspondingly, the {220} crystal planes were finally existed as the side-planes of SiC grains. The detailed EBSD investigation provided the experimental evidences for the evolution of crystal planes in the growth process.