Resistance of HVOF-Sprayed Cr3C2-25NiCr and WC-10CO-4Cr coatings to cavitation and erosion by mud jetting

Abstract

This study investigates chromium carbide-based coating material’s cavitation and erosion resistance with 25% nickel-chromium. (Cr3C2-25NiCr) and Tungsten carbide coating with 10% cobalt and 4% chromium (WC-10CO-4Cr) coatings deposited by high-velocity oxygen fuel (HVOF) thermal spraying. The coatings were characterized by microstructure, porosity, hardness, and fracture toughness. Cavitation tests were performed in distilled water and water-sand mixtures to assess the synergistic effect of erosion and cavitation. Erosion tests were conducted using a mud jet at different impact angles (30°, 60°, 90°). The Cr3C2-25NiCr coating exhibited higher cavitation resistance due to its higher fracture toughness and lower porosity. However, the WC-10CO-4Cr coating showed superior erosion resistance, attributed to its finer and more homogeneously distributed carbides. The dominant wear mechanisms were micro grooving, carbide detachment, and cracking. The impact angle significantly influenced the erosion rates, with ductile materials like CA6NM steel being more susceptible at lower angles, while brittle coatings showed the opposite behavior. The findings highlight the importance of coating properties and test conditions on the wear performance, providing valuable insights for selecting suitable coatings for hydropower applications.