Effects of microstructure and mechanical properties on cavitation erosion resistance of NiCrWMoCuCBFe coatings

Abstract

NiCrWMoCuCBFe coatings were prepared by high velocity oxy-fuel (HVOF) spraying technology with the microstructures and mechanical properties characterized in detail. Besides, an ultrasonic vibratory apparatus was employed to investigate the cavitation erosion resistance of the coating in deionized water and its cavitation erosion mechanism was revealed. The results show that there were some inherent defects existed on the coating surface but its microhardness was more than triple that of 316 L stainless steel. In the initial stage of cavitation erosion, these inherent defects of coating surfaces were damaged at first, leading the incubation period of the coating was shorter than 10 min. With the prolongation of cavitation erosion time, many cracks interpenetrated and finally led to the exfoliation of coatings. When the cavitation erosion time extended to 10 h, the erosion rate of the coating was almost stable and reached maximum about 1.32 ± 0.08 μm/h, which was less than that of 316 L stainless steel (2.62 ± 0.18 μm/h). That is, the inherent defects influenced the cavitation erosion resistance in the incubation period of the coating but the mechanical properties played a dominant role in the long-term cavitation erosion of the coating.