High-temperature oxidation resistance of (Al2O3–Y2O3)/(Y2O3-stabilized ZrO2) laminated coating on 8Nb–TiAl alloy prepared by a novel spray pyrolysis

• (Al2O3–Y2O3)/YSZ laminated coating was fabricated on 8Nb–TiAl alloy.
• Novel ultrasonic spray pyrolysis with two-step cycles was developed.
• The defects in the sub-layer can be healed up by the sub-layer in next cycle.
• The laminated coating is compact and possesses interlocking interfaces.
• 8Nb–TiAl Alloy coated with laminated coating exhibits well oxidation resistance.

A novel spray pyrolysis with two-step cycles has been developed to fabricate (Al2O3–Y2O3)/(Y2O3-stabilized ZrO2) (YSZ) laminated coating on 8Nb–TiAl alloy for resisting high-temperature oxidation. And a crack-free structure, except in the top sub-layer, has been established ultimately, with interlocking adhesion between the layers of coating. It is shown, from cyclic oxidation at 1000 °C, that 8Nb–TiAl alloy with laminated coating exhibits superior oxidation and spallation resistance. These beneficial effects can be attributed to the compact structure, the suppression of oxygen diffusion in Al2O3–Y2O3 layers, the decrease of thermal stresses and the increase of fracture toughness in such laminated coating.