A Novel Plasma-Sprayed Durable Thermal Barrier Coating with the Well-Bonded YSZ Interlayer between Porous YSZ and Bond Coat

Abstract

Abstract Atmospheric plasma-sprayed YSZ thermal barrier coatings (TBCs) are widely used in industrial gas turbine engines to prevent the superalloy blades from failure. The failure of TBCs in service occurs by the spalling of YSZ coating. Crack propagation leading to the failure of plasma-sprayed thermal barrier coatings usually occurs within YSZ coating near the YSZ/Bond coat interface. In the present study, a novel durable TBCs consisting of a YSZ interlayer of the well-bonded interlamellae between the bond coat and conventional YSZ top porous coat was introduced. The YSZ interlayer was deposited at different coating surface temperatures, which resulted in the formation of YSZ with significantly improved interlamellar bonding. The result shows that thermal cyclic lifetime of the novel TBCs with the 20-30 µm thick YSZ interlayer increased by factor of 4 compared with that of the conventional one. The improved thermal cyclic lifetime was attributed to the controlled transition of cracking path from the near YSZ/bond coat interface to YSZ top layer. The effect of thickness of the YSZ interlayer on the lifetime of TBCs was also investigated.