Wear and frictional attributes of Al-alloy hybrid composite dispersed with hard-ceramic (ZrO2) and solid-lubricant (Gr) particles

Abstract

The objective of this study was to investigate the effects of adding two different types of reinforcing particles, hard-ceramic zirconia (ZrO2p: 0, 2, and 4 wt.%) and solid-lubricant graphite (Grp: 0, and 3 wt.%), on the sliding wear and frictional properties of stir-squeeze cast aluminum composites. For this purpose, wear tests were performed using a pin-on-disk wear tester, with emphasis on parameters such as wear rate, seizure resistance, temperature, coefficient of friction, and wear coefficient at varying sliding distances (0-5000 m at an interval of 1000 m) and under different applied pressures (0.5-2.0 MPa). Microstructural analysis showed that the particles were evenly dispersed in the aluminum matrix alloy. The addition of either particles or a combination of both reduced the wear rate significantly compared to the monolithic alloy. The seizure resistance and temperature rise were also improved, from 1.5 MPa to 2.0 MPa and 78 °C to 123 °C, respectively, with the addition of 4% ZrO2 and 3% Gr particles to the aluminum matrix alloy. The friction coefficient increased with the addition of reinforcing particles and was more noteworthy at higher pressures. The wear mechanism observed during wear surface and subsurface analysis was the creation and disintegration of a mechanically mixed layer (MML).