Abstract:As the key material of components used in elevated temperature of gas turbines, the mechanism of delamination and failure of thermal barrier coatings (TBCs) under service conditions has been the hot spot of research for a long time. The influences of strain ranges and phase angles on the thermomechanical fatigue (TMF) properties of samples with thermal barrier coatingsTBCs were investigated in this paper. It was is shown that under the same phase angles, the TMF lifetime decreased decreases with the increase of strain ranges. Under the same strain range, the in-phase tests had have longer TMF lifetime than out-of-phase tests. In both samples, cracks were are initiated in thermally grown oxide (TGO) layer, and then propagated along the bond coat/ceramic top coat, forming the delamination cracks. When the delamination cracks connected with the segmentation cracks initiated in ceramic coat, the TBCs spalled. A TMF lifetime model concerning strain ranges and phase angles was is established, and an exponential law exists between TMF lifetime and the maximum stress