Slurry erosion behavior of HVOF sprayed GNP on Co-Ni and WC-based coatings over AISI 304 steel

This study investigates the slurry erosion behavior of hydropower plant components, focusing on WC-based coatings with graphene nanoparticle (GNP) reinforcement applied to AISI 304 steel using the High-Velocity Oxy-Fuel (HVOF) process. Three coatings were developed: Coating A (50% WC, 50% Co-Ni), Coating B (49% WC, 49% Co-Ni, 2% GNP), and Coating C (48% WC, 48% Co-Ni, 4% GNP). The microhardness of the coatings increased from 1354 HV (Coating A) to 1498 HV (Coating C), while porosity reduced from 3.6% to 1.5%, indicating the densification effect of GNP. Slurry erosion tests revealed that Coating C demonstrated a significant reduction in material loss compared to Coatings A and B, particularly under high slurry concentrations (45,000 ppm) and jet velocities (40 m/s). These results highlight the potential of GNP-reinforced WC coatings to enhance erosion resistance, motivating further optimization for long-term applications in hydropower environments.