钽合金高温抗氧化复合涂层制备研究

Study on the Preparation of High Temperature Oxidation-resistent Composite Coating on Ta-based Alloy

目的制备钽合金在高温氧化环境下的防护涂层。方法采用料浆熔烧法，在Ta．12W合金表面依次制备底层和面层，通过两次熔烧处理，获得硅化物复合涂层。分析涂层的形貌、元素含量及成分分布，测试涂层在1800℃下的高温抗氧化性能和室温～1800℃热循环寿命，并初步探讨涂层失效机理。结果制备的复合涂层与基体之间通过扩散形成过渡层，达到冶金结合；涂层在1800℃下可连续工作9h，室温～1800℃热循环寿命为151次。结论在高温氧化环境中，复合涂层表面生成了一层玻璃状薄膜，有效阻止了外界氧向基体的进一步扩散，对基体形成了良好的保护。

Objective To prepare protective coating for Ta-based alloy in the high-temperature oxidation environ- ment. Methods Using slurry firing, the silicide composite coating was prepared on the surface of Ta-12W alloy. The bottom layer and the surface layer were prepared in proportion on the sample. Using two firing process, the silieide composite coating was prepared on the sample. The morphology, element content and composition distribution of the composite coating were investigated by SEM, EDS and XRD. The life of high-temperature oxidation-resistance at 1800 ~C and the times of shock-testing from room temperature to 1800 ~C of the coating were detected. The failure mecha- nism of the coating was discussed. Results The transitional layer between the coating and substrate is formed by dif- fusion, and the interface is metallurgical bond. The coating can be used at 1800 ~C for 9 hours, and the limit time of shock-testing from room temperature to 1800 ~C is 151. Conclusion The glass layer on the surface of the coating, which is formed during the high-temperature oxidation environment, prevents oxygen from further diffusion and protects the material.