Tribological Performance of Sub-Micron Al₂O₃-Reinforced Aluminum Composite Brake Rotor Material

Friction and wear characteristics of 6061 Al alloy composite reinforced with sub-micron Al₂O₃ particles (Al/Al₂O₃ submicron composite) against commercial semi-metallic brake pad material were determined in dry sliding condition at different loads and sliding speeds using a pad-on-disc configuration. The tribological performance of Al/Al₂O₃ submicron composite was evaluated against conventional grey cast iron brake rotor material under same conditions. The Al/Al₂O₃ submicron composite exhibited lower wear rate than grey cast iron, specifically at brake power intensity (PV) lower than 6 MPa-m/s. Al/Al₂O₃ submicron composite also resulted in much lower wear of the semi-metallic brake pad material at higher brake power intensity (above PV = 6 MPa-m/s) compared to grey cast iron. This is attributed to the better heat dissipation in Al/Al₂O₃ submicron composite causing the brake pad material to operate at much lower temperature. Up to a sliding speed of 2 m/s, a 20% higher coefficient of friction was observed with brake pad material sliding against grey cast iron. Higher sliding speeds were marked with negligible difference in friction. The scanning electron microscope (SEM) with energy-dispersive spectrum (EDS) analyzer was used to examine the morphology and chemical composition of worn surfaces and then investigate the underlying wear mechanisms.