氧化铝形成合金中活性元素效应的研究进展

Research Progress of Reactive Element Effect in Alumina-forming Alloys

高温金属防护涂层在先进航空发动机上有着广泛应用,其通过生成表面保护性氧化膜为发动机热端部件提供保护,以提高热端部件的抗高温氧化腐蚀能力,延长热端部件的服役寿命。微量活性元素由于能降低涂层材料的高温氧化速率,提高涂层表面氧化膜的粘附性而被广泛用于高温防护涂层的改性上,特别是用于超高温(≥1200℃)金属涂层潜在应用材料NiAl的改性上。但是截至目前,由于活性元素效应的影响因素复杂,相关作用模型并不完善,人们对活性元素效应的微观作用机理还存在较大的争论。从活性元素促进元素的选择性氧化、降低氧化膜生长速率和提高氧化膜粘附性等角度出发,综述了活性元素改性在高温金属防护涂层领域的研究进展,特别是针对以氧化铝形成合金为代表的金属防护涂层材料。重点分析了活性元素改性对氧化膜微观结构、生长机制、界面孔洞、内应力等的影响以及活性元素与杂质元素(如C和S)之间的交互作用。最后,对今后的研究工作进行了展望,希望在原子尺度进行更深入、更细致的研究,为超高温金属防护涂层的发展提供理论指导。

High-temperature metallic protective coatings have been widely used in advanced aero-engines,since they can protect hot components against high-temperature oxidation and corrosion by forming protective oxide scales,thus prolonging their service lifetime.Due to the effect on reducing oxidation rate of coating materials and improving scale adhesion,reactive elements were increasingly used for the modification of high-temperature protective coatings,especially for the modification of NiAl,which was a potential application material of metallic coatings used at ultra-high temperatures(≥1200℃).But up to now,the microscopic mechanism of reactive element effect was still in debate,as the influence factors of reactive element effect were too complex and the relevant action models remained incomplete.An overview on the research progress of reactive element modification in the field of high-temperature metallic protective coatings was given from the view of promoting selective oxidation,reducing scale growth rate and improving scale adhesion,especially for the alumina-forming alloys,typical materials of metallic protective coatings.The effects of reactive element modification on the microstructures,growth mechanisms,interfacial void formation and internal stress accumulation,etc.of oxide scale were emphatically analyzed.Moreover,interactions between reactive elements and impurities(e.g.C and S)were also focused on.Finally,deeper and more detailed future studies on the atomic scale are also anticipated,hoping to provide theoretical support for the development of ultra-high temperature metallic protective coatings.