Microstruture and High Temperature Oxidation Resistance of NiCoCrAlYTa Coatings With Different Preparation Processes

NiCoCrAlYTa coatings were prepared on nickel base superalloy (GH4169) by laser cladding and atmospheric plasma spraying. The microstructure and high temperature oxidation properties of the two coatings were studied. The microstructure and phase analysis of the coating were observed by scanning electron microscopy, X-ray diffractometer, and energy dispersive spectrometer. The results show that the equiaxed solidification structure with cellular substructure is formed in the laser cladding coating, which is denser than that of plasma spraying coating. After oxidation at 1100 ℃ for 100 h, the oxidation products of the sprayed coating are mainly Cr₂O₃ and spinel, and the oxidation resistance decreases. However, the laser cladding coating is relatively denser and has less pores, and the oxidation product is γ- Matrix, NiO and a small amount of spinel. The oxidation resistance of laser cladding coating is obviously better than that of plasma spraying coating.