Surface and cross–section characteristics and friction–wear properties of high velocity oxy fuel sprayed WC–12Co coating

A WC–12Co coating was sprayed on H13 hot work mould steel using a high velocity oxy fuel (HVOF). The surface and cross–section morphologies, chemical compositions, and phases of obtained coatings were analyzed using a field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS), and X–ray diffraction (XRD), respectively. The friction–wear properties were investigated using a wear test, the wear mechanism of WC–12Co coating was also discussed. The results show that the WC–12Co coating primarily is composed of WC hard phase with high hardness and Co as a binder, which is evenly distributed on the coating surface, no atom–rich zones. There is no W₃O phase appearing in the HVOF spraying, showing that the WC–12Co coating has high oxidation resistance, the new phases of W₂C and C are produced due to the decarburization of WC. The coating thickness is ~200 μm, which is combined the substrate with the mechanical binding and local micro–metallurgical bonding. The average coefficient of friction (COF) of WC–12Co coating is 0.272, showing good friction performance, the wear mechanism is primarily abrasive wear, accompanied with fatigue wear.