EFFECTS OF SUBSTRATE SURFACE FINISH ON TRI- BOLOGICAL PERFORMANCE AND SURFACE TOPOGRA- PHY OF THERMALLY SPRAYED WC CERMET COATING

Abstract

In this study, tribological characteristics and surface topographies of thermally sprayed WC-Cr-Ni cermet coating were investigated experimentally under lubricated rolling with sliding contact conditions. Hi-HVOF sprayed WC cermet coatings were deposited onto the axially ground, blasted and circumferentially ground roller specimens made of an induction hardened carbon steel. It was found that under a contact pressure 1.4 GPa, cermet coating showed a high durability and life of the coating was not influenced by the substrate surface finish. It was also found that coefficient of friction and surface temperature were hardly affected by the substrate surface finish. On the other hand, after running, surface topographical parameters such as skewness, kurtosis and surface roughness were significantly influenced depending on the substrate surface finish. Namely, after the running-in process, the skewness in the case of circumferentially ground substrate became much more negative than that in the case of axially ground or blasted substrate. In addition, kurtosis and surface roughness of the coated surface were much more influenced in the case of circumferentially ground substrate than that in the case of axially ground or blasted substrate.