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Copper matrix composites reinforced with various contents (10-20 wt-%) and sizes (1-9 mm) of tungsten carbide particles (WC p ) and cobalt particles (Co p , 1 . 5 mm and 5 wt-%) were fabricated by hot pressing. The effects of WC p 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/WC p composites increase with a decrease of WC p size or with an increase of WC p content. Also, the corrosion current density I corr increases with a decrease of WC p size or with an increase of WC p content, and the corrosion potential E corr exhibits no specific trend with varying WC p content and size.The wear corrosion rate increases with an increase in WC p content, yet shows no direct correlation with WC p size. On the other hand, Cu/WC p /Co p composites exhibit better wear resistance in both dry wear and corrosive wear conditions.

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Matrix composites of Al-Si containing dispersed lead and copper particles were fabricated by hot pressing. The effects of the addition of 5 and 10 wt-% lead and 3 wt-% copper particles on the wear and wear corrosion properties of Al-Si composites have been evaluated. Wear testing was conducted at ambient temperature without lubricant, and wear corrosion testing was executed in 3 . 5 wt-%NaCl solution (pH 6 . 7). The results show that the dry wear loss of Al-Si/Pb and Al-Si/ Cu-Pb composites decreased as the lead content increased. The hardness increased and the dry wear loss was reduced with the addition of copper particles. The corrosion potential E corr decreased with the presence of copper and with an increase of the lead content, for both pressed and heat treated conditions. The corrosion current density I corr increased with copper and lead incorporation into composites in the as pressed state, and decreased after heat treatment for Al-Si/Cu and Al-Si/Cu-Pb composites. Wear corrosion properties were improved by addition of the lead phase to Al-Si and Al-Si/Cu composites. The Al-Si/Cu-Pb composites exhibited better dry wear and wear corrosion resistance than those of other composites in the present study. The lead containing composites (Al-Si/Pb and Al-Si/Cu-Pb) possessed lower E corr values compared with other Al-Si composites.

The wear and corrosion properties of SiC p /graphite reinforced copper metal matrix composites (MMCs) fabricated by hot pressing have been evaluated. Electron microscopic studies were conducted to clarify the micromechanisms of wear and corrosion. The experimental results indicate that the hardness and wear loss increase with increasing SiC p content but decrease with increasing graphite content. In particular, the wear loss decreases with increasing graphite up to a content of 5 vol.-% then remains approximately constant as the graphite content is further increased to 7 . 5 vol.-%. The material porosity of the composites increased with the content of foreign particles (SiC p and/or graphite).The composites were immersed in an aqueous solution of 3 . 5 wt.-%NaCl at pH 6?7 for potentiodynamic and corrosion rate measurements. Pure copper exhibited the best corrosion resistance. The Cu/SiC p composite showed lower resistance, and the Cu/SiC p /graphite composite had the lowest resistance to corrosion. The poor corrosive properties of the composites were the result of galvanic and crevice corrosion, which were influenced by residual stress/strain and differences in electrochemical potential between the additions (SiC p and/or graphite) and the copper matrix. Furthermore, the weight loss due to corrosion increased with increasing SiC p and graphite content.CEST/2092