CMAS环境下电子束物理气相沉积热障涂层的热循环行为及失效机制

航空发动机涡轮叶片工作时表面经常产生CaO-MgO-Al₂O₃-SiO₂(简称CMAS)等沉积物。本文中研究了电子束物理气相沉积(EB-PVD)制备ZrO₂热障涂层(TBCs)在CMAS环境下的热循环行为及失效机制。结果表明, 在1200℃热冲击条件下, 表面涂覆CMAS的热障涂层的热循环寿命低于100次, 而未涂覆CMAS的涂层寿命达到500次以上, CMAS 的存在加速了热障涂层的剥落失效。在1200℃经过210次循环后, ZrO₂陶瓷层与CMAS之间形成了约8 μm厚的互反应区, 其形成主要与CMAS中Ca²⁺内扩散有关。CMAS环境下热障涂层陶瓷层产生大量横向裂纹, 涂层的失效主要以陶瓷层片状剥落为主。

Thermal cycling behavior and associated failure mechanism of EB-PVD thermal barrier coatings with CMAS deposits

CaO-MgO-Al2O3-SiO2(CMAS in short) deposits are often generated on the surface of in-service aircraft engine blades.In this paper,the thermal cycling behavior and associated failure mechanism of EB-PVD zirconia-based thermal barrier coatings(TBCs) with CMAS deposits were investigated.The results show that the thermal cycling life of TBCs with CMAS deposits at 1200 ℃ is less than 100 cycles,whereas the life of TBCs without CMAS is more than 500 cycles.CMAS deposits accelerate the spallation failure of TBCs.After 210 thermal cycles at 1200 ℃,about 8 μm interaction layer is formed between CMAS and zirconia ceramic layer,which is mainly due to the inward diffusion of Ca2+ from the CMAS deposits.A large number of transverse cracks are generated in the ceramic layer of TBCs with CMAS deposits.The failure of TBCs occurs mainly by chipping spallation of the ceramic layer.