不同粒度的碳化硅磨料氧化性研究

本文用热重分析仪、X射线衍射仪和扫描电子显微镜（SEM）研究了两种不同粒度（0．28-104．71μm，39．81～954．99μm）的碳化硅粉体在20-1400℃温度范围内非等温氧化的特性，结果表明：（1）粒度较小的1#试样的比表面积是2#试样的20多倍，1#试样氧化开始温度为560℃，而2#试样的氧化开始温度为870μ，1#试样在1400℃的氧化增重率为2．36％，2#试样的增重率为1．14％。这表明在相同实验条件下，碳化硅粒度越小，活性越高，氧化程度越高。（2）粒度较小的碳化硅氧化产物为方石英。（3）SEM表明SiC表面生成SiO2保护膜可封闭部分气孔，阻止O2向内扩散，为保护性氧化。

Oxidation resistance of SiC powder with different particle size

The non-isothermal oxidation characteristics of SiC powder with different particle size （0.28 -104.71 μm, 39.81 -954.99μm） at 20 - 1400℃ were studied by using TG-DTA, X - ray diffraction （XRD） and scanning electron microscope （SEM）. The results show that ： （ 1 ） The specific surface area of sample 1 is more than 20 times that of sample 2. The initial oxidation temperature of sample 1 is 560 ℃, and that of sample 2 is 870 ℃. At 1400 ℃ the weight gain percentage of sample 1 is 2.36% and that of sample 2 is 1.14%. This indicates that under the same conditions , the finer the SiC particles, the higher their activity and their oxidizability. （ 2 ） The reaction product of SiC with smaller particle size is cristobalite. （3.） SEM reveals that there is SiO2 film on the surface of SiC particles which blocks the pores between particles and prevents O2 from diffusing into SiC particles. So this can be considered as protective oxidation.