WEAR AND WEAR MECHANISMS OF AL-22-PERCENT-SI/AL2O3F COMPOSITE

The influence of FP-type alumina fibers on the wear characteristics of a cast Al-22%Si alloy, produced by the squeeze casting technique, has been assessed using a pin-on-ring dry wear test. Pin specimens of 8 mm diameter and 12 mm in length, were machined from Al-22%Si and Al-22%Si containing 26 vol% of alumina fibers, which were rubbed against rotating steel ring (SAE 1045), at a sliding speed of 1 m s(-1) over the load range from 40 to 350 N. It was found that the addition of fibers increases the transition load for severe wear of this alloy by more than three times and decreases the coefficient of friction. The mechanism of wear does not change by the addition of fibers; there are still three regimes of wear; namely, oxidation induced delamination, high strain induced delamination, and sub-surface delamination (microgrooving). In both the matrix and the composite, the transition from mild to severe wear takes place at the same wear rate, about 3.9 X 10(-3) mm(3) m(-1), although the transition load is completely different.