Sliding wear behaviour of eutectic Al-Si alloy under lubricated conditions: An investigation on the effect of ethanol (E85) addition
Bio-fuels such as E85 (85% ethanol and 15% gasoline) are clean and cost effective alternative fuel sources. Their effects on the tribological performance of the IC Al-Si engine alloy needs to be investigated. This study explores the ultra mild wear (UMW) mechanisms of an Al-12.6%Si alloy operating under a mixture of E85 fuel and motor oil (5W30) blended at a 1:1 ratio and only engine oil using boundary lubricated condition. Wear tests were conducted at room temperature using a pin-on-disk configuration and 52100 steel balls counterface. They show that samples lubricated with only engine oil and an engine oil E85 blend exhibited similar UMW characteristics. Lower wear rates were obtained when the engine oil was mixed with E85 fuel. Although the oil residue layer is of reduced thickness it is tribologically effective due to the formation of a protective tribochemical film by the alcohol.