INFLUENCE OF COBALT CONTENT ON THE MECHANICAL AND EROSION PERFORMANCE OF HVOF-SPRAYED WC-Co COATINGS ON INCONEL 718 SUPERALLOY

This study presents a detailed analysis of the microstructure and erosion behavior of WC-Co composite coatings with different cobalt levels: WC-10Co, WC-13Co, and WC-16Co, applied on nickel-based Inconel 718 steel superalloy using the HVOF spray process. The research shows that the coatings’ hardness increases with cobalt content, with WC-16Co reaching the highest microhardness of 825 Hv. XRD analysis indicates that the WC-16Co coating displays notably sharper cobalt peaks as the cobalt content increases, indicating improved phase visibility. This correlates with a distinct layered structure exhibiting minimal porosity of 1.1±0.15%, compared to 1.4±0.20% for WC-10Co and 1.3±0.15% for WC-13Co. The increased hardness and lower porosity of WC-16Co suggest better wear and erosion resistance relative to the other coatings. Overall, this study emphasizes the impact of cobalt content on the microstructural and mechanical properties of WC-Co coatings, identifying WC-16Co as the most durable option for applications demanding superior erosion resistance.