Deposition and cavitation erosion behavior of multimodal WC-10Co4Cr coatings sprayed by HVOF

Cavitation erosion is one of the major failure modes for engineering components operating in the marine environment. In this study, WC-10Co4Cr coatings with multi-scale WC particles were prepared on 304 stainless steel substrates by two high velocity oxygen fuel (HVOF) systems differentiated by the types of fuel. The splat formation process of the multimodal cermet particles was investigated, as well as coatings' porosity, microhardness, fracture toughness and electrochemical performance. In addition, the cavitation erosion resistance of the coatings was evaluated by ultrasonic vibratory apparatus in 3.5 wt% NaCl solution. The results show that the splats sprayed by high velocity oxygen liquid fuel (HVOLF) had a more disk-like shape, leading to much lower porosity and superior mechanical properties in the corresponding coating. The low porosity also significantly hindered the formation of cavitation sources and reduced the cavitation rate. More importantly, the synergistic effect of corrosion on cavitation erosion made the coating much more vulnerable in NaCl solution than in fresh water.