High-temperature oxidation resistance of (Al_2O_3-Y_2O_3)/(Y_2O_3-stabilized ZrO_2) laminated coating on 8Nb-TiAl alloy prepared by a novel spray pyrolysis

摘要

A novel spray pyrolysis with two-step cycles has been developed to fabricate (Al_2O_3-Y_2O_3)/(Y_2O_3-stabi-lized ZrO_2) (YSZ) laminated coating on 8Nb-TiAI 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 ℃, 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 Al_2O_3-Y_2O_3 layers, the decrease of thermal stresses and the increase of fracture toughness in such laminated coating.