低压化学气相沉积MoSi2涂层微观结构及氧化性能

为了防止Mo合金的高温氧化,本研究采用低压化学气相沉积技术在Mo合金表面制备MoSi2抗氧化涂层,借助X射线衍射仪、扫描电镜及能谱仪等分析手段,对涂层的微观结构进行了研究,测试了涂层的抗氧化和抗热震性.结果表明:MoSi2涂层结构致密,仅有少量微裂纹存在,表现出良好的抗热震和抗氧化性能;经20次1300℃-室温循环热震实验后,涂层未出现开裂与脱落现象;涂层试样在1300℃氧化气氛下氧化180 h,失重率小于0.83%,分析揭示了涂层试样氧化失重的主要原因为氧扩散通过涂层与Mo基体发生反应,生成极易挥发的MoO、MoO2、MoO3,氧在涂层中的扩散速率决定了涂层的失重速率.

Microstructures andoxidation resistance of MoSi2 coating prepared by low pressure chemical vapor deposition

To prevent Mo alloy from oxidation,a MoSi2 coating has been prepared by low pressure chemical vapor deposition(LPCVD).Microstructures of the coating were studied through XRD,SEM,EDS.The isothermal oxidation and thermal shock of the coating was also tested.Results show that the MoSi2 coating has compact structure with only a few microcracks and exhibites a nice thermal shock resistance and anti-oxidation ability.The coated samples have just a 0.3% weight loss after 20 times thermal shocks.No spalling and splitting appear in the coating.For 180 h isothermal oxidation at 1300 ℃,the weight loss of sample is less than 0.83%.The weight loss is mainly owing to the generation of volatile MO,MoO2 and MoO3 by the reaction between the oxygen diffused in and Mo at the interface between the coating and matrix.