Near-nanostructured WC-18 pct Co coatings with low amounts of non-WC carbide phase: Part II. Hardness and resistance to sliding and abrasive wear

We investigated the mechanical properties, microstructure, and tribological performance of high velocity oxygen fuel (HVOF) deposited WC-18 pct Co coatings, the synthesis of which was presented in Part I. The results show that the hardness of the coatings increases with the temperature of the particle at deposition. Coatings deposited with propylene fuel gas have higher hardness (1100 to 1300 kgf/mm2) than coatings produced with hydrogen (735 to 1000 kgf/mm2). Generally, the sliding-wear resistance increases linearly with the hardness but is decreased by the presence of cracks at splat interfaces. On any given coating, the hardness varies by as much as 400 kg/mm2, which results in corresponding local variations in sliding-wear resistance. Abrasion wear shows the same dependence on hardness and fracture as sliding wear.