Thermal barrier coating bonded by (Al₂O₃-Y₂O₃)/(Y₂O₃-stabilized ZrO₂) laminated composite coating prepared by two-step cyclic spray pyrolysis

Thermal barrier coating bonded by (Al₂O₃-Y₂O₃)/(Y₂O₃-stabilized ZrO₂) (YSZ) laminated coating has been developed on Ni-based superalloy by two-step cyclic pyrolysis. It is demonstrated, from cyclic oxidation tests at 1100°C, that YSZ top coat and alloy substrate can be bonded together effectively by the (Al₂O₃-Y₂O₃)/YSZ laminated coating, showing good resistance to oxidation, cracking, spallation and buckling. These beneficial effects can be attributed to the sealing effect of the designed multi-sealed compact bond coat with α-Al₂O₃ layers, the decrease of thermal stresses, the increase of fracture toughness in such bond coat and no interdiffusion between the substrate and bond coat.