Comparative study of the dry sliding wear behaviour of HVOF-sprayed WC-(W,Cr)2C-Ni and WC-CoCr hardmetal coatings

The dry unidirectional sliding wear behaviour of the coatings, studied according to ASTM G99 against Al2O3 counterbodies at four different temperatures (25 °C, 400 °C, 600 °C, 750 °C) and at two sliding speeds, was interpreted on the basis of their microstructure, micromechanical properties and oxidation behaviour. The morphology and composition inside the wear scars were also studied by SEM and micro-Raman spectroscopy. The results show that the WC-(W,Cr)2C-Ni coating exhibits good wear resistance up to 750 °C, whereas WC-CoCr, in spite of its very mild wear at low temperature, suffers from catastrophic oxidation at 750 °C.