Characterization and High-Temperature Fretting Wear Resistance of HVOF-Sprayed Cr3C2-NiCr, CoCrWC and CoCrWNiC Hardfacing Coatings

In the present study, Cr 3 C 2 -25wt%NiCr, CoCrWC (Stellite-6) and CoCrWC (FSX 414) coatings were deposited by the high-velocity oxy-fuel process on Hastelloy X substrates. The microstructure of the coatings was characterized using field emission scanning electron microscopy. X-ray diffraction was employed to identify the phase composition of the coatings. Tensile bond strength, elastic modulus and Vickers microhardness of the coatings were measured. A self-mated fretting wear test was also carried out on the coatings at room temperature and 550 °C. The results showed that some carbide dissolution occurred during the formation of Cr 3 C 2 -NiCr coating, although the coating displayed the highest bonding strength, Vickers microhardness and elastic modulus. The Stellite-6 coating showed a significant amount of unmelted particles and the most surface roughness. Oxide stringers were the main microstructural defect of the FSX 414 coating. The Stellite-6 and Cr 3 C 2 -NiCr coating had the best fretting wear resistance at the temperature of 25 and 550 °C, respectively. The wear mechanisms of the hardfacing coatings were discussed in detail.