Effect of vacuum remelting on microstructure and wear resistance of NiCrMoY coatings deposited by supersonic atmospheric plasma spraying

In this study, vacuum remelting was applied on the supersonic atmospheric plasma sprayed NiCrMoY coating with the aim of improving its wear resistance. The microstructure, surface roughness, phase composition, micro-hardness and wear resistance of NiCrMoY coatings before and after vacuum remelting were studied. The results showed that the vacuum remelting eliminated the defects (such as pores and cracks) of plasma sprayed coating and improved its relative density and micro-hardness. Meanwhile, Cr2B and Cr7C3 in the as-sprayed coating transformed to CrB and Cr23C6 after remelting, and some other new phases including Ni3B, Mo2C and NbC were also detected in the remelted coating. The average wear weight loss of remelted coating was about 1.34 mg, compared with the 11.88 mg of as-sprayed coating indicating that the wear resistance of coating was improved by the vacuum remelting treatment.