熔盐法制备C/C复合材料表面MoSi_2-SiC涂层的结构与性能

Microstructure and property of MoSi_2-SiC coating prepared by molten salt method

采用两步熔盐法于900～1 000℃下在C/C复合材料表面制备MoSi2-SiC复合涂层,即在含仲钼酸铵的熔盐中制备Mo2C涂层,然后通过熔盐渗硅生成MoSi2-SiC复合涂层。用X射线衍射（XRD）、扫描电镜（SEM）与能谱分析（EDS）等方式研究涂层的组织结构,并测试涂层在1 500℃下的抗氧化性能和抗热震性能。同时对涂层氧化后的组织结构进行分析。结果表明：复合涂层主要由MoSi2和SiC两相组成,涂层与C/C基体结合处仅有少量未反应的Mo2C。涂层整体致密,与基体结合良好,均匀地包覆整个基体表面,厚度约为100μm。涂层样品在1 500℃的静态空气中氧化42 h后,涂层表面仍保持完整,质量损失率仅为2.79%。1 500℃下经历30次热震实验后,样品的质量损失率为1.96%,涂层具有良好的抗氧化和抗热震性能。

MoSi2-SiC composite coating was prepared on C/C composites using two-stepped molten salt method at900-1000 ℃.Mo2C layer was prepared in molten salt of ammonium paramolybdate on C/C composite surface firstly,followed by infiltrating Si into the Mo2C by molten salt method to synthesis MoSi2-SiC composite coating.The microstructure of the coating was studied using XRD,SEM and EDS.The oxidation-resistance,thermal shock resistance and change of the coating microstructure were also investigated.The results show that the coating is composed of MoSi2,SiC and residual Mo2C in the bonding region.The dense coating with a thickness of 100 μm bonds well with the matrix.The coating keeps integrity,and the mass loss rate is 2.79%after holding at 1 500 ℃ for 42 h in static air.The mass loss rate is 1.96%after 30 thermal shock tests in 1 500 ℃.Therefore,MoSi2-SiC composite coating has good oxidation-resistance and excellent thermal shock property.