Impact Wear Behavior of HVOF-Sprayed WC-10Co-4Cr Coating on Medium Carbon Steel Under Controlled Kinetic Energy

A compact WC-10Co-4Cr coating with a thickness of about 210 μm was prepared by HVOF spraying, which is mainly composed of WC, W2C, Co6W6C, Co and W phases. By taking an Si3N4 ball as counterpart, the impact wear behavior of the WC-10Co-4Cr coating and its substrate (medium carbon steel) is systematically studied under the ball-on-flat contact mode. The results show that the increase in impact velocity will significantly change the peak stress, kinetic energy and absorbed energy fraction, while the impact time remains almost unchanged. With the increase in collision cycle, the impact energy absorption of WC-10Co-4Cr coating and medium carbon steel decreased first and then remained stable. In addition, the WC-10Co-4Cr coating has higher microhardness and kinetic energy rebound effect, which inhibits plastic deformation during repeated collision, and the initiation, propagation and connection of microcracks, as well as the crushing and spalling of surface materials. When the impact velocity reaches 150 mm/s, the depth and width of the wear mark, the wear rate and the wear loss of the WC-10Co-4Cr coating are 4.61 and 75.16, 11.96 and 7.51% than those of medium carbon steel, respectively. The dominant wear mechanism of the WC-10Co-4Cr coating is delamination wear and slight oxidation, while the primary wear damage of medium carbon steel is plastic deformation, which is followed by the gradual onset of additional oxidation and fatigue wear.