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

• (Al2O3–Y2O3)/YSZ laminated coatings were fabricated as the bond coat of TBC.
• The top coat and substrate were bonded together effectively by such bond coat.
• This TBC exhibits very good resistance to oxidation, cracking and spallation.
• Such bond coat can suppress oxygen inward diffusion stepwise to avoid oxidation.
• Such bond coat exhibits good stress tolerance by its toughening effects.

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.