退火处理对离子镀NiCrAlY涂层热腐蚀性能的影响

Influence of Annealing on Hot Corrosion Behavior of Ion-plating NiCrAlY Coating

为了进一步改善离子镀NiCrAlY涂层的抗热腐蚀性能,对NiCrAlY涂层在1050℃进行真空退火2h,研究了涂层退火前后的热腐蚀行为。结果表明,退火处理消除了离子镀NiCrAlY涂层的一些孔洞,涂层形成了γ/γ′+β多相平衡组织,使涂层组织更致密;在25%NaCl+75%Na2SO4(质量分数)盐膜下850℃热腐蚀20h时,未退火的NiCrAlY涂层生成的是外层Cr2O3、内层Al2O3的双层氧化膜,退火后的NiCrAlY涂层仅生成一层Al2O3膜,孕育期增长,在一定程度上提高了抗热腐蚀寿命。

A NiCrAIY coating was deposited on a Nickel-based superalloy K38G by arc ion plating. The influence of vacuum annealing on the microstructures and corrosion behaviors of the coating was investigated. The results show that annealing can annihilate some micro-pores in the coatings, and lead to the formation of γ/γ′＋β phases. In 25wt%NaCl＋75wt%a2SO4 salt film at 850℃, double layer Cr2O3/α-Al2O3 scales forms on NiCrAIY coating at 20 h, while a single layer of α-Al2O3 scale forms on the coating aRer annealing. Annealing can prolongate the incubation period and improve corrosion resistance of the coatings to some extent.