1300℃下MoSi_2/SiC复合材料氧化性能研究

Study of the Oxidation Behavior of MoSi_2/SiC Composites at 1300℃

对直接浸渗法制备MoSi2/SiC复合材料在1 300℃下的氧化试样的质量变化进行了研究.观察与分析了氧化层的形貌和相组成.结果表明,复合材料在该温度下保温时间较短时其氧化模式为硅、钼同时氧化,复合材料表现为失重,形成的氧化层结构疏松,存在大量气孔;保温时间较长时氧化模式为硅的选择性氧化,材料表面形成致密的SiO2氧化层,复合材料表现为增重.同时复合材料的抗氧化性与材料的孔隙率和SiC颗粒大小有关,孔隙率越高,SiC颗粒越小,抗氧化性越差.研究表明MoSi2/SiC复合材料可用作1 300℃下的抗氧化材料.

The mass change of MoSi2/SiC composites at 1300℃ by melt infiltration was studied, and the microstructure and the phase component of oxidation layer were-observed and analyzed. The result showed that, when oxidation time was shorter, silicon and molybdenum were oxidized simultaneously. The mass of composites decreased and the oxidation layer presented many pores. When oxidation time was longer, only silicon was oxidized. The mass of composites increased and the oxidation layer was compact. The oxidation resistance correlated with the porosity of composites and the particle size of SiC. The oxidation resistance was worse when the porosity was higher or the SiC particle size was smaller.