Study on the oxidation resistance mechanism of self-healable NiAl coating deposited by atmospheric plasma spraying

Abstract

AbstractA dense NiAl coating with low oxide content was deposited on the GH4202 superalloy substrate by atmospheric plasma spraying (APS) using carbon-containing Ni/Al composite powders. Compared with traditional APS NiAl coatings with high oxide content, this coating exhibits better long-term oxidation resistance at 900 °C in air. For the NiAl coating with low oxide content, it was found that the improved inter-splat bonding, due to limited oxide inclusions, promotes the formation of a continuous protective Al2O3 layer on the coating surface during oxidation. During long-term oxidation, the dispersion of oxide scales within the coating and element diffusion across splats result in the in-situ healing of unbonded inter-splat interfaces.