【摘要】 钼网被广泛用作高温催化剂载体,但关于其高温防护涂层的制备及失效机制却鲜有报道。用包埋渗硅方法在钼网表面制备了MoSi₂高温抗氧化涂层,并在静态大气环境中开展了1 500℃恒温氧化试验。利用X射线衍射仪（XRD）、扫描电镜（SEM）、能谱分析（EDS）等对氧化前后涂层的微观形貌和组织结构进行了表征。结果表明:1 500℃氧化2 h,MoSi₂涂层中的Si元素会发生选择性氧化,在涂层表面形成一层连续的、具有"自愈合"功能的熔融态SiO₂保护膜,阻挡氧向基体一侧的扩散,展现出了良好的高温抗氧化性能;高温条件下,涂层中的Si元素会和钼基体发生界面扩散反应生成抗氧化性能差的Mo₅Si₃,同时MoSi₂不断地和氧发生反应生成Mo₅Si₃和SiO₂,当涂层中的MoSi₂完全转化为Mo₅Si₃,涂层将快速氧化失效。更多还原

【Abstract】 MoSi₂ coating with high-temperature antioxidant performance was prepared on Mo net by pack cementation method,and then the coating was evaluated by isothermal oxidation test at 1 500 ℃ in static air.In addition,X-ray diffractometer（XRD）,scanning electron microscope（SEM） and energy dispersive spectrometer（EDS） were employed to characterize the micro morphology and phase structure of coating before and after oxidation treatment.Results revealed that after oxidation treatment at 1 500 ℃ for 2 h,the selective oxidation of Si element in MoSi₂ coating occurred,and a continuous melt-state SiO₂ protective film with self-sealing property that could restrain O₂ spreading toward the substrate was formed on the surface of coating,which resulted in excellent high-temperature antioxidant performance.Moreover,at high temperature,Si element in MoSi₂ could spread around the boundary of Mo substrate and form M₅Si₃ that had bad high-temperature antioxidant performance,and meanwhile MoSi₂ continuously reacted with oxygen into Mo₅Si₃ and SiO₂.Once the MoSi₂ phase of coating was totally consumed,the coating failed quickly by oxidation treatment.更多还原