Effects of tungsten carbide and cobalt particles on corrosion and wear behaviour of copper matrix composite

Copper matrix composites reinforced with various contents (10-20 wt-%) and sizes (1-9 mu m) of tungsten carbide particles (WCp) and cobalt particles (Co-p, 1.5 mu m and 5 wt-%) were fabricated by hot pressing. The effects of WCp and Co-p on the wear and corrosion properties of the copper composites were evaluated. Dry wear testing was conducted in ambient conditions and wear corrosion testing was carried out in 3.5 wt-%NaCl solution (pH 6.7). The results show that the hardness, wear resistance and static corrosion weight loss of Cu/WCP composites increase with a decrease of WCp size or with an increase of WCP content. Also, the corrosion current density /(corr) increases with a decrease of WCP size or with an increase of WCP content, and the corrosion potential E-corr exhibits no specific trend with varying WCp content and size.The wear corrosion rate increases with an increase in WCP content, yet shows no direct correlation with WCp size. On the other hand, Cu/WCp/COp composites exhibit better wear resistance in both dry wear and corrosive wear conditions. The Cu/WCp/COp composites show a much lower E-corr and significantly more passivity than Cu/WCp composites in polarisation tests. The Cu/WCp/COp composites exhibit excellent wear corrosion resistance, especially in the passive potential (E-p) state.