Tribological and Corrosion Behavior of HVOF-Sprayed WC-Co-Based Composite Coatings in Simulated Mine Water Environments

WC-based cermet coatings have been considered as alternative replacements to the more traditional hard chrome plating for improved surface properties. Though these coatings are used in engineering applications requiring superior hardness and improved wear resistance, little is known about their corrosion resistance. In this study, four WC-based composite coatings were deposited onto austenitic stainless steel substrates using high-velocity oxy fuel (HVOF) technology. Wear and potentiodynamic scanning studies in a simulated mine environment were conducted on the coatings. Characterization of the as-received powders, coating structure, composition, and morphology was carried out prior to and after wear studies and corrosion testing using optical microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) elemental analysis. The results showed that the chemical composition of the binder material plays a significant role in influencing the wear and corrosion behavior of HVOF-sprayed WC cermet coatings in an aggressive mine water environment. During wet sliding, addition of Cr in the binder improves the wear resistance of the coating. WC-10Co-4Cr showed the highest wear resistance in a wet sliding environment and also exhibited the best corrosive behavior of the evaluated coatings, due to a Cr2O3 oxide passive film that forms during anodic polarization.