Abstract:
NiCoCrAlYHf (HY5) bond coating was deposited on nickel-base single crystal superalloy (DD32) by vacuum arc ion plating, and then the surface of the bond coating was treated by vibration polishing (VP), grit blasting (GB) and VP+GB, respectively. Lastly YSZ top coating was deposited by electron beam physical vapor deposition (EB-PVD). The evolution of interface structure, composition and residual stress of the thermal barrier coatings during thermal shock at 1100 ℃ was studied with a scanning electron microscope (SEM), an electron probe X-ray microanalyzer (EPMA) and a photo-stimulated luminescence piezo-spectroscope (PLPS). The results indicate that all the surface treatment methods can improve the surface morphology of the bond coating, which has an impact on residual stress and thermal shock life of the TGO layer. The stress level of untreated samples was higher than that of the treated, and the residual stress of untreated samples increased more significantly with the increase of thermal shock cycles. After surface treatment, the thermal shock life of the samples increased, especially those treated by vibration finishing. Grit blasting on the surface of the bond coating caused sand particles to be embedded in the surface layer of the bond coating, which accelerated the local growth of TGO and increased stress concentration. As a result, the thermal shock life of the thermal barrier coatings of the grit-blasted samples was lower than that of the VP samples.