SiC颗粒的氧化行为研究

研究了SiC颗粒氧化前后的微观形貌及元素变化,SiC颗粒氧化增重趋势及其影响因素。结果表明:氧化反应使SiC颗粒形貌发生很大改变,对SiC颗粒有钝化作用,使其失去了很尖锐的边角,更趋于圆滑;氧化后SiC颗粒表面有SiO_2生成;氧化前期SiC氧化增重随氧化时间的延长和氧化温度的升高而呈线性关系增加,氧化速度主要受界面化学反应速率影响,氧化后期氧化增重缓慢,受O_2和CO等在表层氧化膜中的扩散速率控制。并提出了一种简单估算SiC颗粒氧化层厚度的公式。

Study on oxidation behavior of SiC particles

The changes of microstructure and elements in SiC particles before and after oxidation were studied;the oxidation weight gain trend and influencing factors were also presented. The results show that,oxidation reac-tion makes the morphology of SiC particles changed greatly,which has passivation effect on the SiC particles, and makes SiC particles lose sharp edges,tending to be smoother. SiO2 forms on SiC particles surface after oxida-tion. During the early oxidation stage,the weight of SiC increases with the increasing oxidation temperature and oxidation time,the oxidation rate is mainly controlled by the interfacial chemical reaction rate. During later oxida-tion stage,the weight of the SiC increases slowly,and the oxidation rate is controlled by the diffusion rate of O2 and CO in the surface oxide film. A simple estimation formula for oxide thickness of SiC particles was proposed.