1997 Volume 38 Issue 3 Pages 197-204
An attempt has been made in this investigation to characterize the sliding wear response of a modified zinc-based alloy at the sliding speed of 2.68 m/s over a range of applied pressures. A conventional zinc-based alloy (conforming to ZA 27) and a leaded-tin bronze (conforming to SAE 660) were also subjected to identical test conditions in order to assess the (wear) performance of the modified (zinc-based) alloy. A correlation has been established between the nature of the various microconstituents and the wear response of the alloys. Wear mechanisms have also been studied through the examination of wear surfaces, subsurfaces and debris.
The study clearly indicates that the presence of nickel and silicon comprising microconstituents led to a considerably increased wear and seizure resistance of the modified zinc-based alloy over its conventional counterpart. Further, zinc-based alloys attained better wear resistance (prior to seizure) but inferior seizure pressure when compared with those of the bronze. As far as the extent of frictional heating is concerned, the conventional zinc-based alloy suffered from a maximum extent of heating while the bronze experienced the minimum. The response of the modified zinc-based alloy was intermediate between the two in this context. The modified alloy also attained improved thermal stability than the conventional (zinc-based) alloy.
In general, (microcracking assisted) adhesion was the predominant mechanism of material removal. However, abrasion was also observed to contribute to material loss. The zinc-based alloys experienced considerable wear induced subsurface deformation and formation of a stable transfer layer while such observations were weakly made in the case of the bronze due to the cracking tendency of the latter.