Dry sliding wear response of zinc-based alloy Influence of heat treatment, sliding speed and pressure.

An attempt was made to study the dry sliding wear behaviour of a Zn-27.5 Al-2.5Cu-0.03Mg alloy over a range of applied pressures and sliding speeds. The influence of T6 heat treatment (solutionising followed by artificial aging) on the wear characteristics of the alloy was also examined under identical test conditions. Wear rate increased with pressure and sliding speed while seizure resistance followed an opposite trend. At the three lower speeds (i.e. 0.42, 1.38, and 2.68 m s-l) two wear regimes, namely mild and severe, were exhibited by the as cast and heat treated specimens wherein low wear rates initially occurred up to a specific pressure. This was followed by the attainment of severe wear at higher pressures. However at the highest speed of 4.60 m s-l, the specimens showed only the severe wear regime. Heat treatment caused improved wear response of the alloy up to the sliding speed of 1.38 m s-1. Further, the heat treated alloy performed better than the as cast alloy before seizure at 2.68 m s-1, while it showed identical wear characteristics in both conditions at 4.60 m s -1. The wear behaviour of the alloy is explained on the basis of the nature of its micro constituents. The results are supplemented with analyses of the wear surfaces, subsurface regions, and the debris particles which have also been able to throw light on the operative wear mechanisms