Micro-scale abrasive wear behaviour of HVOF sprayed and laser-remelted conventional and nanostructured WC-Co coatings

WC-Co coatings were deposited by HVOF spraying from two different feedstock powders, one with a conventionally sized WC grains and one with nanoscale WC grains. The powder feedstock with nanoscale WC grains was employed in the light of published research, which pointed to enhancements in wear resistance associated with nanoscale structures in WC-Co materials. The coatings were subsequently laser remelted in an attempt to realize the benefits observed by other workers, namely a decrease in porosity and an increase in hardness. It was found that under conditions of micro-scale abrasion, the fine WC grain size in the nanostructured material resulted in rapid pullout of the hard phase and thus to high wear rates. Moreover, laser remelting resulted in a decrease in hardness of the coatings and to a corresponding increase in abrasive wear rate.