WSi_2/MoSi_2复合材料的低温氧化特征

Low-Temperature Oxidation of WSi_2/MoSi_2 Composite

通过热重分析法研究了WSi2 /MoSi2 复合材料在 4 0 0～ 70 0℃的氧化性能 ,采用X 射线和SEM分析了表面氧化相的组成和表面形貌。结果表明 :WSi2 /MoSi2 复合材料具有较低的低温抗氧化性 ,5 0 0～ 70 0℃氧化会发生“PEST”现象 ;6 0 0和 70 0℃氧化时的质量增重与时间近似于线性关系 ;大量MoO3 和WO3 等挥发性氧化相的形成 ,破坏了连续致密保护性SiO2 膜的形成 ,促进了裂纹的产生与扩展 ,导致颗粒分离 ,成为“PEST”

The oxidation properties of WSi 2/MoSi 2 composite at 400～700℃ were investigated by TGA. And the phases in the oxidized film and the surface topography of WSi 2/MoSi 2 composite were analyzed by X ray and SEM, respectively. The results show that WSi 2/MoSi 2 composite has bad low temperature resistance to oxidation and PEST reaction occurs at 500～700℃. When oxidized at 600 and 700℃,the mass weight changes are linear with time. At different temperature, the different main oxidiation reaction dominates the oxidation rate of WSi 2/MoSi 2 composite. A great deal of volatile MoO 3 and WO 3 destroy the formation of glass SiO 2, and accelerate the appearance and development of the cracks that will result in the mass abruption. It is the main reason that PEST reaction occurs.