Understanding the role of surface roughness on the tribological performance and corrosion resistance of WC-Co coating

Abstract

The use of nanofinished cermet coating has extensively increased in various industries to impede operational wear and corrosion of engineering components. In the present study, the wear and corrosion behaviours of the as-sprayed, ground and nanofinished coatings are investigated. The effect of compressive residual stress on the microhardness of the coatings is also evaluated. A modified model for the specific wear rate of WC-Co coating is proposed by incorporating the areal surface roughness parameter, mechanical properties and WC grain diameter. In the case of the as-sprayed and ground coatings, three-body abrasion is found as the dominant wear mechanism. The effect of three-body abrasion is found insignificant in the case of nanofinished coating. Moreover, the presence of tribofilm and tribo-oxide film reduces the wear rate of the later coating. The lower interfacial area owing to the nanoscale surface roughness and the presence of protective oxide films lead to slower corrosion for the nanofinished coating. It is perceived that surface roughness plays a significant role in wear and corrosion resistance of the coatings.