Corrosion resistance of vacuum re-melted Ni60-NiCrMoY alloy coatings

The aim of this study is to provide a detailed insight into the effect of vacuum re-melting on the microstructure and corrosion resistance of plasma sprayed Ni60-NiCrMoY alloy coatings. The microstructure evolution and corrosion behavior of the coatings after vacuum re-melting treatment were comparatively studied. The results showed that the lamellar structures and defects of as-sprayed coating were significantly eliminated by vacuum re-melting. A dense coating with uniformly distributed fine hard phases was obtained after vacuum re-melting treatment. During the salt spray corrosion test, the corrosion weight of re-melted coating increased slowly due to the dense Cr2O3 passive film formed on the surface of re-melted coating. The re-melted coating exhibited higher corrosion potential, lower corrosion current density and higher polarization resistance, indicating an improved corrosion resistance compared with the as-sprayed coating.