铌表面MoSi2高温涂层的形貌和结构研究

The Morphology and the Structure of MoSi2 High Temperature Coating on Niobium

摘要:

用料浆熔烧法在铌基体表面制备了。MoSi2高温抗氧化涂层。利用SEM，EDS，XRD等仪器分析研究了涂层的结构、元素分布、相分布与抗氧化性能的关系。结果表明：涂层与基体之间达到了冶金结合，通过扩散形成了过渡层，涂层的复合结构有利于提高抗氧化性能，用料浆熔烧法在铌基体表面制备MoSi2涂层是可行的。在氧化环境下，MoSi2涂层能在表面自生成一层SiO2玻璃层，阻止氧的进一步扩散。经2h以上高温氧化后，Si的扩散使涂层主体中形成多孔疏松组织。涂层元素与基体发生互扩散，在界面处形成大量集中孔洞并横向贯穿，使涂层从其主体与过渡层接触的界面处发生横向内部断裂，导致涂层失效。

Abstract:

The high-temperature oxidation-resistant MoSi2 coating on the Nb substrate was prepared by slurry firing. The structure, composition and phase distribution of the coating and the relationship between these features and the oxidation resistance of the coating were investigated by SEM, EDS, and XRD. The results indicate that the interface between the coating and the substrate is metallurgical bond, and a transitional layer was formed by diffusion. The composite multi-layer structures improve the oxidation resistance properties of the coating. The method of slurry firing to prepare the high temperature MoSi2 coating on Nb was feasible. The SiO2 glass layer, which was formed on the surface of the coating by the self-oxidation of MoSi2, prevents oxygen from further diffusion. After a long time exposure in high temperature oxidizing environment, the porous microstructure was formed as a result of the diffusion of silicon in the coating. Due to further interdiffusion of the element, which takes place between the coating and the substrate, a large number of cavities which run through transversely are formed. The coating was broken through the interface between the body of the coating and the transitional layer.