Microstructure and cavitation-silt erosion behavior of high-velocity oxygen-fuel (HVOF) sprayed Cr3C2-NiCr coating

In this paper, a Cr3C2-NiCr coating was prepared by means of high-velocity oxygen-fuel (HVOF) thermal spraying process and analyzed with regard to their cavitation-silt erosion (CSE) behavior under different sediment concentration conditions. It is found that Cr3C2, Cr7C3, Cr2O3 and (Cr, Ni) phases are obtained in the coating. The binder matrix contains amorphous phase and nanocrystalline grains. The crystallization temperature of the amorphous phase is about 559 °C. The coating exhibits low porosity and high microhardness. After being eroded for 20 h, the CSE mass loss of the coating in 40 kg·m− 3 is 1.15 and 1.23 times to that in 20 kg·m− 3 and in 0 kg·m− 3, respectively. Due to increase in interaction area of sand particles with specimen, the CSE rate is found to increase progressively as sediment concentration increases. Signatures of lips, craters, microcutting, cracks and micropores are observed on the eroded surface of the coating. The CSE mechanism for the coating is a composite ductile and brittle mode.