Failure analysis based on microstructural features of thermal barrier coatings under creep and fatigue loadings

研制了热障涂层失效行为原位观察装置，研究了热障涂层在蠕变和疲劳载荷作用下的裂纹萌生部位和裂纹扩展行为与热障涂层微观结构的关系。破坏行为与加载条件和TBC的微观结构密切相关。在静态蠕变载荷作用下，无论涂层组织如何，TBC都表现出典型的蠕变断裂行为。另一方面，在动态疲劳载荷下，许多疲劳裂纹不仅起源于顶涂层的切分裂纹尖端，而且起源于顶涂层/粘结层界面。在此基础上，对TBC的抗剥落性能进行了研究，提出了不同载荷下TBC的多因素评价方法。

An in-situ observation apparatus of failure behavior of thermal barrier coating (TBC) was developed and crack initiation sites and the crack propagation behavior in connection with the microstructure of TBCs under creep and fatigue loadingswas investigated. The failure behavior was found to depend strongly on the loading conditions and the microstructure of TBC. Under static creep loadings, the TBC exhibited the typical creep rupture behavior regardless of the top-coat microstructure. Under dynamic fatigue loadings, on the other hand, many fatigue cracks initiated not only from the tips of segmentation cracks in the top-coat but also from the top-coat/bond-coatinterface. Furthermore, the spalling resistance of TBC was investigated and the multifactor evaluation method of TBC under various loadings was proposed.