钼及钼合金表面高温防护涂层的研究进展

Research Progress of High Temperature Protective Coatings on Molybdenum and Molybdenum Alloy

系统总结了国内外关于钼及钼合金表面高温防护涂层的最新研究成果,分析了钼在不同温度区间的氧化特征,并基于涂层组织结构稳定性、涂层缺陷、涂层与基体界面结合强度、界面物理和化学相容性、氧扩散等多方面,概述了钼及钼合金表面高温防护涂层的性能要求。归纳了现阶段应用于钼及钼合金表面的高温防护涂层体系,主要包括单一硅化物涂层、改性的硅化物涂层、硅化物基梯度复合涂层、铝化物涂层、耐热合金涂层和氧化物涂层,重点讨论了涂层的成分和结构对其抗高温氧化性能的影响。同时,对比介绍了钼及钼合金表面高温防护涂层常用的制备方法,主要包括料浆烧结法、包埋渗法、等离子喷涂法、熔盐法、化学气相沉积法、磁控溅射法等。最后,对钼及钼合金表面高温防护涂层现阶段存在的问题及未来发展方向进行了展望。

In this work,the latest research results of high temperature protective coatings on molybdenum and molybdenum alloy in China and abroad were systematically reviewed.The oxidation characteristics of molybdenum in different temperature ranges were analyzed.Based on the stability of coating microstructure,coating defects,interfacial bonding strength between the coating and substrate,interfacial physical and chemical compatibility and oxygen diffusion,the property requirements of high temperature protective coatings on molybdenum and molybdenum alloy were concluded.The high temperature protective coating systems applied to the surface of molybdenum and molybdenum alloy at present were summarized,including single silicide coating,modified silicide coating,silicide-based gradient composite coating,aluminide coating,heat-resistant alloy coating and oxide coating.The effects of the composition and structure of the coating on its high temperature oxidation resistance were mainly discussed.The low temperature "pest" oxidation of single MoSi2 coating,the difference of thermal expansion coefficient with the substrate,and the formation of Mo5Si3 phase caused by solid phase diffusion made the single component MoSi2 inadequate as a high temperature protective coating.Therefore,the modified silicide coating was prepared by composition optimization and structural design.The composition optimization of the coating was mainly based on the introduction of active elements like B,Al and Ti,and reinforcement phases with comparatively low thermal expansion coefficient like bentonite,YSZ and Si3N4 on the basis of MoSi2 coating.The structural design mainly focused on the preparation of gradient composite coating or diffusion barrier layer to alleviate the thermal expansion coefficient difference between the coating and substrate,and inhibit the diffusion of active components.Meanwhile,the commonly used preparation methods of high temperature protective coatings on molybdenum and molybdenum alloy were also introduced and compared,mainly including slurry sintering,pack cementation,plasma spraying,molten salt method,chemical vapor deposition,and magnetron sputtering.Finally,the existing problems and future development direction of high temperature protective coatings on molybdenum and molybdenum alloy were prospected.