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

Abstract

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 TiB 2 hard particles, ∼5 μm in size. Coatings ∼100 μm 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 μm size range. Both coatings exhibited wear rates superior to those of Ni(Cr)–Cr 3C 2 coatings deposited from commercially available blended powders with the TiB 2-containing coating exhibiting lower wear rates than its TiC-based counterpart. Differences in the wear behaviour are rationalised in terms of the coating microstructures.