Effect of heat treatment on wear behaviour of WC–(W,Cr)₂C–Ni coating

Tungsten carbide (WC)–(W,Cr)₂C–Ni coatings have been deposited by high velocity oxyfuel spraying. The influence of post-vacuum heat treatment on the microstructure, phase composition, microhardness and wear resistance of the coatings has been investigated, which is conducted based on analyses of the microstructure and phase composition evolution of the coatings by scanning electron microscopy and X-ray diffraction, as well as measurement of their microhardness with a microhardness tester and evaluation of their friction and wear behaviour with an oscillating friction and wear tester. Results show that after heat treatment above 600°C, crystallisation of amorphous phases occurs, and some new phases rich of Fe and C are generated in the coatings. Moreover, the microhardness and wear resistance of WC–(W,Cr)₂C–Ni coatings increase with increasing heat treatment temperature up to 600 and 700°C, but they tend to decrease with further elevating heat treatment temperature.