航天发动机用铌钨合金高温抗氧化复合涂层的制备研究

Study on Preparation of High Temperature Oxidation-resistant Composite Coating on Nb-W Alloy Used in Aerospace Engine

采用料浆熔烧法,在航天发动机用铌钨合金Nb521-1表面制备高温抗氧化防护涂层,通过两次熔烧依次制备底层和面层,得到硅化物复合涂层。利用SEM及EDS分析涂层的微观形貌和元素含量,对涂层1 700℃高温抗氧化性能和室温～1 600℃热循环性能进行测试,并初步探讨涂层失效机理。结果表明,制备的复合涂层和基体之间通过互扩散形成扩散层,达到冶金结合;涂层在1 700℃下可连续工作22h,室温～1 600℃热循环测试完成了1 124次。在高温条件下,复合涂层可有效阻止外界氧向基体进一步扩散,对基体形成了良好的保护。

High-temperature oxidation-resistant protective coating was prepared by slurry fusion sintering on the surface of Nb-W alloy Nb521-1 used in aerospace engine.The bottom layer and surface layer were successively prepared by twice slurry fusion sintering processes to obtain silicide composite coating.Morphology and element content of the coating were analyzed by SEM and EDS.High temperature oxidation resistance at 1 700 ℃ and thermal cycling performance from room temperature to 1 600 ℃ of the coating were tested.And the failure mechanism of the coating was preliminarily discussed.The results show that there is a diffusion layer between the composite coating and the substrate attributed to their mutual diffusion,and the interface is of metallurgical bond.The coating can be continuously used at 1 700 ℃ for 22 h,and its limit frequency of thermal cycling tests from room temperature to 1 600℃ is 1 124 times.The composite coating can effectively prevent the external oxygen from further diffusion to the substrate,and therefore the substrate is well protected in high temperature environment.