Sliding temperature and wear behaviour of cast Al-Si base alloy

The influence of sliding interface temperature on friction and wear behaviour of eutectic (LM13) and hypereutectic (LM28) Al-Si base alloy in as cast and heat treated condition has been investigated. LM13 and LM28 alloys having nominal composition Al-12Si-1Ni-0.8Cu-0.6Mg and Al-17Si-1Ni-0.8Cu-0.6Mg used in this study. Wear and friction tests were performed under dry sliding conditions using a pin on disc type of friction and wear monitor with the data acquisition system conforming to ASTM G99 standard. It was found that sliding interface temperature,has a close relation with wear and friction response of these alloys. Initial rise in temperature reduces the wear rate and as soon as a critical temperature (CT) is crossed, wear rate abruptly increases. The friction coefficient of both alloys first decreases with rise in temperature then subsequently increases beyond a certain temperature. The influence of temperature on wear behaviour in particular was found to be a function of alloy composition and heat treatment. For as cast LM28 alloy, the critical temperature (140degreesC) was found to be lower than that in the heat treated condition (180degreesC). A temperature-wear mechanism is proposed for these alloys.