EB-PVD工艺中粘结层较薄时热障涂层失效分析

Failure Analysis on TBCs with Thin Bond Coating in EB-PVD Process

采用EB-PVD工艺在高温合金基体上制备了粘结层厚度为12μm左右的YSZ热障涂层,分析粘结层较薄情况下涂层体系的失效模式。通过循环氧化实验发现涂层体系有一定的抗氧化性能,但是寿命较短,且无明显分布规律。采用SEM对试样不同时期微观形貌进行观察,发现试样在热处理之后形成的TGO不够致密,不能有效阻止氧朝基体方向的扩散,使粘结层内部被氧化,导致涂层体系失效。

TBCs with about 12 um thick bond coating were coated on superalloy substrate by EB-PVD processs. The failure molds of TBCs with thin bond coating were analyzed. The micromorphology of the samples under different conditions was analyzed using SEM. The results of cyclic oxidation show that the TBCs have oxidation resistance, but the life of TBCs is short and distributed irregularly. The SEM results show that TGO of as-annealed samples is not dense enough, and can＇t effectively prevent the oxygen diffusing toward the substrate. At last the bondco at is oxidized and the TBCs failed.