Comparison between tribological behaviour of HVOF coatings produced from conventional Ni+TiC powder mixture and Ni–TiC, Ni–(Ti,W)C composite powders

The specification of the powder mixtures used in any thermal spray process has a significant effect on the coating properties. In this research work, Ni–TiC and Ni–(Ti,W)C composite powders, synthesised by self-propagation high temperature synthesis process, were used to prepare coatings by high velocity oxygen fuel (HVOF) method. The coatings were characterised and compared with that produced from conventional Ni+TiC powder mixture. Using the composite powders resulted in homogeneous coatings with no carbide oxidation during the HVOF process, while a significant oxidation of TiC occurred when conventional powders were used. The coatings produced from composite powders also show superior wear resistance over that of conventional powders. Details of the wear mechanism when using different powders as feedstock were explained.