Nano-hBN incorporated WC-Co-Cr composite coatings deposited by HVOF technique: exploring friction and wear behaviour

Stainless steel is used abundantly in industry, and undergoes wear over time. Continuous wear of components leads to malfunctioning or failure in machinery. The present research is focused on enhancing wear resistance of stainless steel using novel coatings. WC-10Co-4Cr-nano hBN coatings have been developed on stainless steel (SS304) substrate by High-Velocity Oxygen-Fuel (HVOF) thermal spray technique. Nano-hBN, a conventional solid lubricant, was uniformly dispersed (0.2–0.6 wt.%) in the WC-10Co-4Cr base powder by ball milling. The developed coatings were mechanically, physically, metallurgically, and tribologically characterised. The wear and friction study of the coating was carried out using a ball-on disc tribometer. With the addition of nano hBN to WC-Co-Cr, the resulting coatings exhibited ≈40% increased hardness compared to WC-Co-Cr coatings. Further, the developed coatings gave decreased coefficient of friction with increase in hBN weight percentage. The wear resistance of the composite coatings also increased with the increase in weight percentage of nano-hBN. Microscopic analysis of worn coating surfaces revealed that adhesion, ploughing, and delamination are the predominant wear mechanisms.