(1. 北京理工大学 材料学院，北京 100081；
2. 北京航空材料研究院，北京 100095)
摘 要: 采用化学气相沉积与等离子喷涂相结合的方法在SiC/SiC复合材料基体上制备了Si/莫来石/Er2SiO5环境障涂层。采用扫描电镜(SEM)、能谱分析仪(EDS)与X射线衍射仪(XRD)分析其结构变化，通过氧化试验研究涂层在1350 ℃与1500 ℃下的高温氧化行为。结果表明：Si/莫来石/Er2SiO5环境障涂层可在1350 ℃长时间使用，在1500 ℃短时间使用。涂层在不同高温下的氧化失效机理不同。1350 ℃时，涂层氧化失效主要是由于涂层材料与基体材料热膨胀不匹配使涂层中产生了垂直于表面的裂纹，裂纹成为元素扩散通道，加速环境中O元素扩散至粘结层与基体并将其氧化，降低了涂层与基体之间的粘结强度，从而导致涂层脱落。1500 ℃时，涂层氧化失效主要是元素快速扩散、反应生成大量的气泡状玻璃态物质所致。
关键字: Si/莫来石/Er2SiO5环境障涂层；高温氧化；失效行为
（1. School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081, China;
2. Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:Si/mullite/Er2SiO5 environmental barrier coatings (EBCs) were manufactured by chemical vapor deposition and plasma spraying on the SiC/SiC composites. The oxidation tests at 1350 ℃ and 1500 ℃ were carried out to study the high temperature oxidation behavior the coatings and the structure changes were analyzed by SEM, EDS and XRD. The results show that Si/mullite/Er2SiO5 EBCs can serve at 1350 ℃ for a long time but at 1500 ℃ only for a short time. The oxidation failure mechanisms vary with temperature. The failure cause of the Si/mullite/Er2SiO5 EBCs at 1350 ℃ is that the thermal expansion coefficient of EBCs cannot match well with that of the substrate, resulting in the formation of cracks in EBCs. The atoms of O diffuse through the cracks to the interface between the bond coat and substrate. As a result, the bond strength decreases due to the oxidation of the bond coat and substrate, resulting in falling off of the EBCs. The oxidation failure cause at 1500 ℃ is that elements diffuse fast and react with each other, resulting in the formation of a lot of glassy phase.
Key words: Si/mullite/Er2SiO5 environmental barrier coatings; high temperature oxidation; failure behavior
