Tribological behaviour at various temperatures of WC-Co coatings prepared using different thermal spraying techniques

Tribological performance of WC-12Co coatings prepared via air plasma spraying (APS), low-pressure plasma spraying (LPPS) and high-velocity air-fuel spraying (HVAF) at temperatures ranging from room temperature (RT, ~25 °C) to 650 °C was investigated. Relationships between the microstructure and tribological behaviour of coatings were discussed. Results show that the plasma-sprayed coatings exhibited more brittle phases, pores and microcracks, which provided the coatings with low hardness, toughness and oxidation resistance, promoted the coating splat delamination during friction and consequently led to the high wear rate. The HVAF coating had fewer brittle phases, fewer pores and more WC particles, which improved the mechanical properties and oxidation resistance, avoided the coating splat delamination, promoted CoWO4 formation and consequently exhibited the better wear resistance.