Evolution of Residual Stresses in PS-PVD TBCs with Thermal Cycling

Cr³⁺ Photoluminescence piezo-spectroscopy (CPLPS) has been developed as a non-destructive inspection technique for the measurement of residual stresses within the thermally grown oxide (TGO) in thermal barrier coatings (TBCs). In this study, plasma spray - physical vapor deposition (PS-PVD) process was used to deposit yttria stabilized zirconia (YSZ) topcoat with quasi-columnar structures. Evolution of the microstructures and residual stress distribution in such kind structured TBCs before and after thermal cycle test on burner rigs were investigated. The accumulated tensile stress in the as-sprayed ceramic topcoat changed to compressive state after 100 cycles, and then gradually increased. In addition, the mapping compressive stresses in the TGO measured through the ceramic topcoat surface decreased rapidly firstly and then essentially maintain at a relatively stable value with further testing. Moreover, the pre-oxidation of the bondcoat could significantly affect the stress distribution in the TGO, in contrast, no obviously influence on the stresses in the YSZ topcoat.