Wear behaviour of HVOF thermally sprayed WC–14Co–3Cr coatings

Abstract

The present study describes the tribological properties of thermal sprayed WC–14Co–3Cr (wt-%) coatings produced by using the high velocity oxyfuel (HVOF) deposition process. The coatings have been characterised with respect to their chemical composition and microstructural features (SEM-EDX) and roughness (profilometry). Experiments using a tribometer (pin on disk configuration) under non-lubricating conditions have been performed with the aim of determining the wear resistance of these coatings. To ensure reproducibility of the wear tests, the coated samples have been ground to an average superficial roughness R_a of 0·230 μm. Steel balls of AISI 1086, 6 mm in diameter, were tested against coated and uncoated samples. The morphology of the wear tracks on both pins and discs was characterised using SEM and three-dimensional profilometry. An average friction coefficient of 0·596 and average wear rate of 1·21 × 10^-4 mm³ Nm^-1 werefound for the tribological pair AISI 1086 pin/ WC–14Co–3Cr coated disc. For this pair a mixed wear mechanism of both abrasive and adhesive wear was observed for the pin with unidirectional material transfer from the pin toward the coating.