FRICTION AND ADHESIVE WEAR STUDY OF HVOF SPRAYED Ni–WC–Co-BASED POWDER COATING

Abstract

Ni-based alloys are being widely used to improve the wear resistance of various industrial components in normal and severe environments and addition of rare earth elements to these alloys further improves the various mechanical and tribological properties of the coatings. In the present work, commercially available MEC 86 (NiCrBSi/WC–Co = 65/35) powder was modified with the optimum addition of 0.4 wt.% La₂O₃. The coatings were deposited by high velocity oxy-fuel (HVOF) spraying process. Rare earth addition refines the microstructure and increases the microhardness of the coatings. The increase in microhardness with the addition of La₂O₃ is approximately 22%. Sliding wear resistance of the coating modified with La₂O₃ is higher than of that without La₂O₃. The average wear resistance increases by approximately 14%. Further, the addition of La₂O₃ to the coating reduces the friction coefficient as compared to the one without the rare earth element. The coefficient of friction was found lower with the addition of La₂O₃, which is approximately 18%.