Dry sliding wear behavior of Al2O3 fiber reinforced aluminum composites

Dry sliding wear behavior of die-cast ADC12 aluminum alloy composites reinf orced with short alumina fibers were investigated by using a pin-on-disk we ar tester. The Al2O3 fibers were 4 mu m in diameter and were present in vol ume fractions (T-f)ranging from 0.03 to 0.26, The length of the fiber varie d from 40 to 200 mu m. Disks of aluminum-alumina composites were rubbed aga inst a pin of nitrided stainless steel SUS440B with a load of 10 N at a sli ding velocity of 0.1 m/s. The unreinforced ADC 12 aluminum alloy and their composites containing low volume fractions of alumina (V-f approximate to 0 .05) showed a sliding-distance-dependent transition from severe to mild wea r. However, composites containing high volume fractions of alumina ( V-f > 0.05) exhibited only mild wear for all sliding distances. The duration of o ccurrence of the severe wear regime and the wear rate both decrease with in creasing volume fraction. In MMCs the wear rate in the mild wear regime dec reases with increase in volume fraction: reaching a minimum value at V-f = 0.09 Beyond V-f = 0.09 the wear rate increases marginally. On the other han d, the wear rate of the counterface (steel pin) was found to increase moder ately with increase in V-f. From the analysis of wear data and detailed exa mination of (a) worn surfaces, (b) their cross-sections and (c) wear debris , two modes of wear mechanisms have been identified to be operative, in the se materials and these are: (i) adhesive wear in the case of unreinforced m atrix material and in MMCs with low Vf and (ii) abrasive wear in the case o f MMCs with high V-f. (C) 2000 Elsevier Science Ltd. All rights reserved.