Effects of epoxidized natural rubber–alumina nanoparticles (ENRAN) composites in semi-metallic brake friction materials

A group of semi-metallic friction composites (SMFC) consisting of epoxidized natural rubber–alumina nanoparticles (ENRAN), steel wool, graphite, and benzoxazine were prepared using a melt mixing method. The mixing work was carried out at 90 °C. The composites were vulcanized by electron beam irradiation. The samples were then subjected to mechanical and physical tests to determine the tribological properties of SMFC. Detailed examinations on the worked layer were analyzed using a scanning electron microscopy with an energy dispersive X-ray. Samples with 29% of ENRAN exhibited the best friction coefficient (∼0.437) with low specific wear rates (0.27×10−7 cm3/Nm). An iron oxide formation was prominent on the friction surfaces, implying the occurrence of interactions between the contacting surfaces and the environment.