Sliding Wear of a Squeeze Cast Magnesium Composite AM60-(Al2O3)f at Low Loads
Abstract
Mg matrix composites AM60-x% (Al2O3)f (x=9,11,26) were fabricated by Al2O3 fibre preform preparation and squeeze casting technique. Sliding wear behaviour of these composites were studied by conducting boundary lubricated pin-on-disk tests under ultra-mild wear conditions at 25 ºC and 100 ºC against AISI 52100 steel balls. The damage in AM60-9% (Al2O3)f at 25 ºC occurred as follows: Al2O3 fibre fracture and fragmentation, sinking in of the fragmented fibres leading to decrease in fibre elevation, and damage to Mg matrix. The fibre fracture and fragmentation process, leading towards damage to the Mg matrix, was attributed to: i) high applied contact pressure, ii) matrix hardening and, iii) high fibre length. Increasing the Al2O3 fibre volume content delayed the transition to higher rate of material loss but inflicted greater damage to the counterface. At 100 °C, the formation of an oil residue layer on the worn surfaces delayed the wear transition.