TRIBOLOGY OF AL-SI ALLOY-GRAPHITE COMPOSITES - TRIBOINDUCED GRAPHITE FILMS AND THE ROLE OF SILICON MORPHOLOGY

Al-Si (LM6) alloy and 3 wt.% graphite particle composites were synthesised using a solidification processing technique. The morphology of silicon was altered by sodium modification and heat treatment. Wear tests were conducted under dry and partially liquid lubricated conditions using a pin-on-disc wear test apparatus. Wear surfaces and debris were examined by scanning electron microscopy. Under both dry and partially liquid lubricated conditions, the performance of heat-treated composites was found to be superior to the rest. Wear surfaces of heat-treated composites showed the presence of patchy layers of graphite. The role of silicon morphology in the formation of triboinduced graphite films is explained.