Effect of inert environment on the sliding wear behaviour of the HVOF sprayed WC-12Co coating

Abstract

The reciprocating sliding wear behaviour of high velocity oxy-fuel sprayed WC-12Co coatings in the inert environment at room temperature, and 300 °C temperature with varying load conditions was investigated. The worn-out coatings and the debris were analyzed by scanning electron microscopy and Raman spectroscopy. From the wear test data, the coefficient of friction was measured as lower in the air environment at both room temperature and 300 °C, compared with the argon environment due to the development of self-lubricating tribo-oxide layers. The development of CoWO4 phases at the surface decreases friction and wear and allows the coating to uphold the tribological properties at higher temperatures. Higher loads mechanically damage the coatings and quickly remove the protective oxide layer compared with the lower loads. In the protective environment, abrasive wear and adhesive wear mechanisms were observed to be played predominant role, whereas, in the air environment, the oxidative wear mechanism was found to be significant.