Wet abrasive wear behavior of WC-based cermet coatings prepared by HVOF spraying

In this study, three kinds of WC-based cermet coatings including WC-CoCr coating, WC-Ni coating and WC-Cr3C2-Ni coating were prepared by the high-velocity oxygen-fuel (HVOF) spraying process. Scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) and Vickers hardness tester were used to analyze the microstructure and mechanical properties of these coatings. The WC-CoCr coating presented the highest average microhardness of 1205 HV0.3, and then followed by the WC-Cr3C2-Ni coating (1188 HV0.3) and the WC-Ni coating (1105 HV0.3). The abrasive wear behavior of the WC-based coatings under the conditions of different applied loads and sediment concentrations were studied by a wet sand-rubber wheel tester. The results indicated that the abrasive wear loss rates of all the coatings increased with the increment of applied load or sediment concentration. In addition, the coatings with higher microhardness appeared to have higher abrasive wear resistance. The abrasive wear resistance of the WC-based coatings was 4-90 times higher than that of AISI 304 stainless steel under the same testing condition. The abrasive wear mechanism of the WC-based coatings was deduced to be the extrusion and removal of binder phases, as well as the fragmentation and peel-off of hard phases.