Tribological performance and high temperature oxidation behaviour of thermal sprayed Ni- and NiCrAlY-based composite coatings

Abstract

Mechanical, tribological performance, and high temperature oxidation behaviour of Ni- and NiCrAlY-based composite coatings with the addition of TiO2/ZnO were investigated. NiCrAlY-based composite coating presents a higher microhardness value than that of the Ni-based composite coatings. The tribological performance of composite coatings is improved by incorporating TiO2/ZnO. In particular, the NiCrAlY- based composite coatings present the lowest friction coefficient (0.24) and wear rate (7.3 × 10−6 mm3 N−1 m−1) at 800 °C. The results of high-temperature oxidation experiments show that the ZnO within the coating diffuses gradually to the surface with the extension of holding time at 800 and 1000 °C. The diffusion behaviour at 800 °C can be inhibited by the substitution of the metal matrix from Ni to NiCrAlY, while it was accelerated as temperature rising up to 1000 °C and have no difference in Ni- and NiCrAlY-based composite coatings.