WC-10Co4Cr coatings were prepared by high velocity oxy-fuel with different spray distances. The internal structure and wear/corrosion resistance of the coating were studied. The internal structure and phase composition of the coating were analyzed by Metallographic microscope, SEM and XRD. The microscopic structure, microhardness, porosity, density, wear/ corrosion resistance properties were tested. The results showed that the particle stayed in the jet for longer time and in the process of spraying it enlarged the melting degree as the distance increased. As a result, complete flattening of particles was gained which increased the density of coating and the property of wear resistance and corrosion resistance. The coating showed the best property of wear resistance and corrosion resistance at the spray distance of 380 mm.

Cermet coatings of NiCr-Cr ₃C ₂  were thermally sprayed on 304 sink roll by high velocity oxygenfuel spraying technique. The corrosion resistance of prepared sample was tested at 600 ℃ in a molten zinc-aluminum containing 55% of aluminum. The inactivation process of sink roll was studied. SEM was used to determine the morphology changes of initial powder and the sample after the corrosive experiment. EDS was used to determine the element composition of initial powder and the coating after corrosion. The data showed that the porosity, bonding strength and micro hardness were 2.9%, 82.76 MPa and 1 078.67 HV respectively before corrosion. While after 1 day's corrosion, NiCr in NiCr-Cr ₃C ₂  cermet was found to be dissolved in Zn, thus the protection ability of Cr ₃C ₂was lost.