热障涂层热循环过程中的界面扩散系数

Interfacial Diffusion Coefficients of EB-PVD Thermal Barrier Coatings During Thermal Cycling

采用磁控溅射方法在镍基单晶高温合金基体上沉积Ni-3 0Cr-12Al-0 .3Y(质量分数 ,% )粘结层 ,采用电束物理气相沉积方法 (EB -PVD)沉积 7%Y2 O3(质量分数 ,%ZrO2 )陶瓷层 .对粘结层与陶瓷层界面在 10 5 0℃循环 10 0次时的元素扩散 ,提出了电子探针与最小二乘法相结合的研究方法 ,求出元素在界面的扩散系数 .继续热循环 ,粘结层中Al贫化 ,Ni和Cr参与氧化 ,加速氧化反应 ,增加氧化膜内应力 ,使氧化膜破裂、陶瓷层剥落 ,最终导致热障涂层失效 .

Depositing Ni-30Cr-12Al-0.3Y (Mass fraction,%)bond coat on a Ni-base single crystal super-alloy by magnetron sputtering,a ceramic top coat (7%Y_(2)O_(3)-ZrO_(2)) was deposited by electronbeam-physical vapor deposition (EB-PVD). The interfacial diffusion of alloy elements between coating and substrate has been studied by electron-probe microanalysis and least square method. With increasing thermal cycles, Al was depleted,and Ni, Cr wouldbe be oxidized near the interface between thermal growth oxidation(TGO)and bond coat. Stress concentration due to the existence of thermal growth oxidation would weaken the combination between top ceramic coat and bond coat, and consequently, the stresses would result in the spallation of thermal barrier ceramic coating.