Comparative Evaluation of the Tribological Performance of Al-MMC and GCI Brake Rotors Through AK Master Dynamometer Testing

The increasing demand for lightweight and high-performance brake rotors has led to the exploration of aluminum–metal matrix composites (Al-MMCs) as alternatives to conventional cast iron rotors. This study evaluated the tribological performance of squeeze-cast Al-MMC brake rotors using an AK Master dynamometer test and compared it with that of conventional gray cast iron (GCI) rotors. The Al-MMC rotors demonstrated stable coefficients of friction (CoFs) with reduced wear rates, compared to the GCI rotors. Surface analysis identified the predominant wear mechanisms, including abrasive and oxidative wear. The Al-MMC rotors exhibited sensitivity to pressure and speed, with a CoF range of 0.35–0.47 that decreased at higher pressures and speeds, whereas the GCI rotors maintained a stable CoF range of 0.38–0.44. At elevated temperatures, the GCI rotors displayed superior thermal stability and fade resistance compared to the Al-MMCs, which experienced a 40–60% loss in CoF. Wear analysis indicated material transfer from brake pads to Al-MMC rotors, resulting in protective tribofilm formation, whereas GCI rotors exhibited conventional abrasive wear. These findings highlight the potential of squeeze-cast Al-MMCs for automotive braking applications, offering advantages in weight reduction and wear resistance, but also suggest the need for further material optimization to enhance high-temperature performance and friction stability.