难熔金属表面高温防护涂层抗热震性能研究现状

Research Status on the Thermal Shock Resistance of High-Temperature Protective Coatings for Refractory Metal Surface

难熔金属及其合金具有高温强度优异、加工塑性好、耐腐蚀性好等优点,在航空、航天和核工业领域中得到了广泛应用,是一种重要的高温结构材料。但难熔金属及其合金因其自身易氧化的缺点,导致材料在未达到服役温度时就发生严重氧化,从而快速失效。目前,高性能高温防护涂层是保障难熔合金服役性能的关键,然而难熔金属及其合金表面高温防护涂层的实际服役工况非常苛刻,往往伴随着强热震,是导致涂层失效的重要原因。因此,难熔金属表面高温防护涂层在具备优异恒温抗氧化性能的前提下,还需具备良好的抗热震性能。综述了难熔金属表面高温防护涂层的热震失效机制,讨论了影响涂层抗热震性能的关键参数;阐述了难熔金属表面硅化物、金属和复合涂层3类主要涂层体系抗热震性能的研究现状,重点回顾了优化涂层结构、添加陶瓷颗粒以及设计复合涂层等提高涂层抗热震性能的方法及其改善效果;最后,从降低涂层与基体间的热膨胀系数失配度、改善基体/涂层界面结合性能以及设计复合梯度涂层3个方面展望了未来难熔金属高温防护涂层的发展方向。

Due to their excellent high-temperature strength,good processing plasticity and corrosion resistance,refractory metals and their alloys are extensively utilized in the aviation,aerospace and nuclear industries,serving as important high-temperature structural materials.However,their susceptibility to oxidation often causes serious oxidation before reaching service temperatures,leading to rapid failure.High performance high-temperature protective coatings are essential for maintaining the performance of these refractory alloy materials at present.However,the actual service conditions of high-temperature protective coatings on surfaces of refractory metals and their alloy are very harsh,often accompanied by strong thermal shock,which is an important reason for coating failure.Therefore,a high-temperature protective coating on refractory metals must have excellent constant temperature oxidation resistance and good thermal shock resistance.In this paper,the thermal shock failure mechanism of high-temperature protective coatings on the surfaces of refractory metals was reviewed,and the key parameters affecting the coatings’thermal shock resistance were discussed.The research status of the thermal shock resistance of three main coating systems,including silicides,metals and composite coatings on the surface of refractory metals,was expounded.Additionally,the modification methods and their improvement effects,such as optimizing the coating structure,adding ceramic particles and designing composite coatings to improve the thermal shock resistance of coatings,were reviewed.Finally,the future development direction of high-temperature protective coatings for refractory metals was prospected from three aspects:reducing the mismatch of thermal expansion coefficient between the coating and the substrate,improving the interface bonding performance between the substrate and coating and designing composite gradient coatings.