Friction delamination mechanism of EB-PVD thermal barrier coatings in high-temperature and high-speed rotating service environment.

High-speed rotation is an indispensable working state in the service process of aero-engines, therefore, the centrifugal load cannot be ignored in the failure analysis of thermal barrier coatings. However, due to the lack of service environment simulators that can realize high-temperature as well as high-speed rotation, the failure mechanism of high-speed rotation thermal barrier coatings is still unclear. Here, the effects of rotational speed variation on the service life and failure mode of thermal barrier coatings at high temperatures are studied by experiments and finite element method (FEM). The results show that the service life of high-speed rotating thermal barrier coatings decreases with the increase of rotational speed. The failure is mainly governed by the thinning and spalling of the columnar crystal region of the ceramic layer and the delamination and exfoliation of the equiaxed crystal region, rather than the abnormal growth of TGO. Further in-depth analysis shows that the failure of high-speed rotating thermal barrier coatings is mainly due to the joint driving of centrifugal force and wall shear stress, as well as the contribution of thermal fatigue at high temperatures. This work adds to the understanding of the failure mechanism of thermal barrier coatings under extreme working conditions, and also provides guidance for the safe and reliable service of thermal barrier coatings on working blades. [ABSTRACT FROM AUTHOR]