Abstract:In this study, WC-12Co powder with nano WC grain size was used to deposit wear resistant coatings by AC-HVAF (Acukote High Velocity Air-Fuel) spray system. The phase compositions and micro-structure of the coatings were examined. The microhardness, fracture toughness and wear resistance were investigated. According to the X-ray Diffraction (XRD) analysis, the principal phase was WC, and its decomposition products were not found. The sprayed coating has a porosity lower than 1% and the grain sizes of coatings were among 80-100 nm which contributed to an average microhardness as high as 1940.3 HV0.3 on the surface and 1662.1 HV0.3 on the cross-section. At the load of 1.5 kg and rotational speed of 1198 r/min of WC counter body, the nano-sized coatings showed a 40% lower average weight loss and a stable friction coefficient of 0.26-0.28 (micron-sized coatings: 0.25-0.4 ) in the dry wear conditions. It was concluded that the sprayed nano structural WC-12Co coatings had a better wear resistance.