Hybrid Co-Cr/W-WC and Ni-W-Cr-B/W-WC Coating Systems

The mechanical, tribological and corrosion properties of two hybrid coating systems were evaluated. The first coating system consists of a tungsten-tungsten carbide (W-WC) top layer and a laser cladded Stellite 6 interlayer (Co-Cr) deposited onto 316 stainless steel substrate, and the second one consists of the same W-WC top layer and a HVOF spray-and-fused Colmonoy® 88 interlayer (Ni-W-Cr-B) onto Inconel® 718 substrate. XRD, EDS and SEM were used to analyze the microstructure of the coating layers. The micro-indentation technique was utilized to measure surface hardness as well as hardness profile of the coating systems. The Rockwell indentation technique was used to evaluate the adhesion of the coating as per CEN/TS 1071-8. In addition, the load-carrying capacity of the surface was evaluated by performing micro- and macro- hardness measurements. Tribological properties were evaluated by pin-on-flat measurements and corrosion resistance was measured by potentiodynamic polarization and electrochemical impedance spectroscopy EIS.