Influence of CeO2 Addition on Microstructure and Wear Behavior of Plasma Spray-Welded Stellite6/WC Composite Coatings

This study systematically investigates the influence of CeO2 content (0–0.6 wt.%) on the microstructure and mechanical properties of Stellite6/WC composite coatings fabricated by plasma spray welding. The phase composition and microstructure of the coatings were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), while microhardness and tribological performance were evaluated using a semi-automatic Vickers microhardness tester and a ball-on-disk tribometer. The results indicate that the coating with 0.4 wt.% CeO2 exhibits the optimal combination of mechanical and tribological properties, achieving a maximum microhardness of 1107.62 HV0.3—a 50.5% improvement over the unmodified coating—and a minimum wear mass loss of 1.4 mg, corresponding to a 78.1% reduction compared to the CeO2-free counterpart. These findings demonstrate that appropriate CeO2 addition significantly enhances both the microhardness and wear resistance of Stellite6/WC coatings, offering an effective strategy to mitigate surface degradation and extend the service life of 45 steel substrates under demanding operating conditions.