A comparison of the abrasive wear behaviour of HVOF sprayed titanium carbide- and titanium boride-based cermet coatings

Cermet coatings are commonly employed to enhance the wear resistance of a wide range of engineering components. Thermal spray techniques, such as plasma spraying and high velocity oxy-fuel (HVOF) spraying are commonly utilised to deposit these coatings. This work outlines a route for cermet powder production based on the technology of self-propagating high-temperature synthesis (SHS) and subsequent HVOF spraying of coatings from these powders. Reactions of elemental mixtures of Fe, Cr, Ti and either C or B powders have resulted in powders consisting predominantly of an Fe(Cr) matrix with a dispersion of either TiC or TiB2 hard particles, similar to5 mum in size. Coatings similar to 100 mum thick were deposited from these powders and dry sand-rubber wheel abrasive wear tests were performed on these coatings with both alumina and silica abrasives in the 500-600 mum size range. Both coatings exhibited wear rates superior to those of Ni(Cr)-Cr3C2 coatings deposited from commercially available blended powders with the TiB2-containing coating exhibiting lower wear rates than its TiC-based counterpart. Differences in the wear behaviour are rationalised in terms of the coating microstructures. (C) 2001 Elsevier Science BN. All rights reserved.