等离子喷涂-物理气相沉积7YSZ热障涂层形成机制

Feather-like 7YSZ coating has been prepared by plasma spray-physical vapor deposition (PS-PVD) on CoCrAlSiY bond coating with Ni-based superalloy, by using aggllomerated ZrO₂-7%Y₂O₃ (7YSZ) powders. The microstrucutres of 7YSZ coating were analyzed by transmission electron microscope (TEM), where the coating was made up with nano-colomnar grain. Those nano-columnar grains change into dendritc microstruture through multi-layer spray. Thus, feather-like 7YSZ coating can be observed in the 7YSZ coating. Considering the formation process of 7YSZ coating, the 7YSZ vapor nucleation mechanism was presented based on thermodynamic principle. The temperature gradient and vapor concentration gradient were investigated induced by interaction by plasma jet and substrate. The nucleation, growth and branching process of grain were discussed under temperature gradient and vapor concentration gradient. Besides, coating mircrosturcture with diffirent undercooling was investigated. The gap fromation mechanism in feather-like 7YSZ coating was also studied.