Effects of lead and copper particles on corrosion and wear behaviour of Al–Si matrix composites

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.