Dry sliding wear behavior of stir cast aluminium base short steel fiber reinforced composites

Dry sliding wears behavior of die cast aluminium alloy composites reinforced with coppercoated short steel fibers were investigated using a pinon- disk wear-testing machine. The composites were prepared by liquid metal route using vortex method. The weight percentage of copper-coated steel fibers was varied from 2.5 to 10. The density and hardness of the composite increased linearly with increasing wt% of steel fibers. The wear rate decreased by 40% with addition of 10% weight percentage of fibers. A linear dependence of wear rate on fiber content and hardness of MMC is observed. The unreinforced aluminium and composites containing upto 5-wt% of fibers exhibited a sliding distance dependent transition from severe to mild wear. However, composites containing 10-wt% fiber showed only mild wear for all sliding distance. It was also observed that with increase in the fiber content to 10-wt% the coefficient of friction decreased by 22%. The duration of occurrence of the severe wear regime and the wear rate decreased with increasing fiber content. For the composite the wear rate in the mild wear regime decreased with increase in fiber content reaching a minimum. From the analysis of wear data and detail examination of (a) wear surface and (b) wear debris two modes of wear have been identified to be operative, in these materials. These are (i) adhesive wear in the case of unreinforced matrix and in MMC with low wt% (upto 5-wt%) fibers (ii) abrasive wear in case of MMC with high wt% of fibers.