Effect of WC content on the friction and wear properties of Ni-WC coatings on 6082-T6 aluminum alloy

The Ni-WC coatings were prepared on the surface of 6082-T6 aluminum alloy by plasma spraying. The effect of WC content on the microstructure, mechanical properties and wear performance of the coatings was investigated. The wear mechanism was discussed according to the wear surface morphology and phase composition. The results show that with the increase of the WC content, the microhardness of Ni-WC coatings increases and the bond strength first increases and then decreases sharply. The Ni-20WC coating shows the highest bond strength. The friction coefficient decreases with increasing the WC content, while the wear rate first reduces and then increases as the WC content rises. The wear mechanism of Ni-WC coatings is a mixture of adhesive wear and oxidation wear. With WC content increasing from 10 wt% to 20 wt.%, the friction coefficient and wear rate reduce mainly due to the formation of the continuous oxide film on the wear surface. When the WC content reaches to 30 wt%, the severe oxidation and the defects of the coating such as some microcracks and holes, lead to the increase of the wear rate. (paper)