C/SiC复合材料表面抗氧化涂层的制备与性能表征

摘要

为了提高航空发动机用C/SiC复合材料抗氧化性能,采用溶胶-凝胶法合成了Ba0.25Sr0.75Al2Si2O8粉末,利用等离子喷涂技术在C/SiC复合材料表面制备了Si/莫来石/Ba025Sr0.75Al2Si2O8复合涂层;利用X射线衍射仪、扫描电镜等测试手段分析涂层的物相组成和涂层表面及截面的微观形貌;测试了涂层在1 000℃大气条件下的抗氧化性能.结果表明:1 000℃下氧化5h,无涂层C/SiC复合材料基体失重率为30.8％,具有Si/莫来石/Ba0.25Sr0.75Al2Si2O8复合涂层的C/SiC复合材料基体失重率为16.0％,表明Si/莫来石/Ba0.25Sr0.75Al2Si2O8复合涂层能有效提高C/SiC复合材料的高温抗氧化性能.%In order to improve the oxidation resistance of C/SiC composites for aircraft engine,high purity Ba0.25Sr0.75Al2Si2O8 powder was synthesized by sol-gel method.A composite coating of Si/mullite/Ba0.25 Sr0.75Al2Si2O8 was prepared on the surface of C/SiC composite by plasma spraying technique.The phase composition of the coating and micro morphology of the coating surface and cross section were analyzed by X-ray diffraction,scanning electron microscopy and other testing means.The oxidation resistance of the coating at 1 000 ℃ under atmospheric conditions was tested.Results showed that after oxidation for 5 h at 1 000 ℃,the weight loss of the composite matrix without coating was 30.8％ while the weight loss of the composite matrix with Si/mullite/Ba0.25Sr0.75 Al2Si2O coating was 16.0％.It is indicated that the composite coating of Si/Mul/Ba0.25Sr0.75Al2Si2Os can improve the high-temperature oxidation resistance of C/SiC composites.