Cavitation Erosion Behavior and Mechanism of HVOF Sprayed WC-10Co-4Cr Coating in 3.5 wt% NaCl Solution

A WC-10Co-4Cr coating was prepared by high-velocity oxygen-fuel (HVOF) thermal spraying process. The cavitation erosion (CE) characteristics of the coating as well as the stainless steel 1Cr18Ni9Ti were investigated in 3.5 wt% NaCl solution. The coating exhibited higher CE resistance than that of the stainless steel 1Cr18Ni9Ti. After being eroded for 20 h, the CE volume loss of the stainless steel 1Cr18Ni9Ti is 3.22 times to that of the coating. The removal mechanism for the coating was erosion of the binder phase first, followed by brittle detachment of hard phases as a result of the action of corrosion and mechanical effect. The cracks were found to initiate at the carbide-binder interface and the edge of the pores, leading to craters on the surface and accelerating the damage of the coating. Fatigue and plastic deformation were found to be the material removal mechanism for the substrate steel 1Cr18Ni9Ti.