Bearing characteristics of cast leaded aluminium-silicon alloys

Coefficient of friction characteristics of cast aluminium-silicon alloys varying in lead content from 4 to 16 wt.% have been investigated under lubricated, semi-dry and dry conditions. Under the oil-lubricated test, bearings of all the leaded alloys are able to run without seizure up to the regimes of boundary lubrication and mixed lubrication, whereas the base alloy bearings could not reach boundary lubrication. In the semi-dry test the bearings operate in the boundary lubrication regime. The average value of coefficient of friction in the oil-lubricated test is lower compared with semi-dry and dry tests. In general the influence of morphology of microstructure, lead distribution and addition of lead is helpful in reducing interface friction.