THE EFFECTS OF ALUMINA FIBERS ON THE SLIDING WEAR OF A CAST-ALUMINUM ALLOY

Dry sliding wear performance of a squeeze cast aluminium alloy-alumina fibre composite has been examined in this investigation using a pin-o n-disc machine. A composite in the form of a pin was evaluated against a rotating EN 25 steel disc. The wear response of the base alloy was also studied to assess the influence of a reinforcing phase over a ran ge of applied pressures until the onset of seizure. Incorporation of a lumina fibres resulted in superior wear performance of the base alloy, i.e. reduced wear loss, improved seizure pressure and reduced rise in temperature near contact surfaces. Onset of seizure in general caused significantly higher wear loss and temperature rise and large adhesio n of the specimen material to the disc surface. A longitudinal cross-s ection of worn samples suggested nominal wear-induced microstructural changes and deformation in the subsurface regions. The wear surfaces r evealed smooth and continuous grooves with less damaged regions prior to onset of seizure, while severe surface damage was observed thereaft er. Similarly, debris particles generated during onset of seizure were coarser. The presence of deeper grooves on the wear surfaces and iron mass in the debris particles indicated abrasion to be one of the wear mechanisms in addition to adhesion. That the debris particles were ma inly of flake type consisting of microcracks indicated that material r emoval occurred mainly by delamination.