碳化硅超细粉末形核生长过程的研究

NUCLEATION AND GROWTH PROCESS OF SiC ULTRAFINE POWDER

用热化学气相合成法制备的超细SiC粉末的组织结构,保留了许多与形核生长过程直接有关的许多特点,为用高分辨电子显微术研究其形核生长过程提供了有利条件。据此,本文讨论了SiC超细粉末形成的主要机制——均相形核生长过程。它可分为5个主要方面:非晶相核的形成;SiC旋涡状生长及受阻;亚稳的SiC旋涡的析晶;聚结;表面非晶SiC的形成。另外,也分析了固态Si上的SiC的异相成核、外延以及固态Si的碳化过程。

The structure of SiC ultrafine powder synthesised by the thermal chemical vapor-phase reaction method remains a lot of characteristics associated directly with the nucleation and crystal growth. It is favorable for the high resolution electron microscopy (HREM) study of the process of nucleation and crystal growth. The main mechanism of forming SiC ultrafine powder-the process of homogeneous nucleation and growth is discussed in this paper.The process includes five procedures: formation of SiC amorphous nuclei: spiral growth of SiC and its obstruction; crystallization of metastable SiC whirlpool; agglomeration; formation of amorphous SiC on the particle surface. Moreover, the heterogeneous nucleation and epitaxy of SiC on solid Si and the carbonization of solid Si are also analyzed.