Tribological Properties of Automotive Brake Friction Composites with Nanoadditives: Al2O3, Boron, CuO, Graphite, and ZrO2

Abstract This study experimentally investigates the effects of nanomaterial additions on the tribological and physical properties of automotive brake friction composites. Composites were formulated using identical constituents (binder, fiber, solid lubricant, abrasive, and filler), while varying only the nanomaterial type. Five nanomaterials (Al 2 O 3 , B, CuO, graphite, and ZrO 2 ) were individually added at 2 wt.%, together with a reference composite without nanomaterials. Tribological performance was evaluated using a laboratory-scale brake test rig under a 253 N normal load (≈ 0.5 MPa) and a sliding speed of 6 m/s. The results indicate that nanomaterial incorporation improved friction stability (up to 9%) and significantly reduced specific wear rate (9-81%) and weight loss (up to 82%) compared to the reference composite. The ZrO 2 -containing composite exhibited the highest average friction coefficient (≈ 0.51), while nano-Al 2 O 3 provided the highest wear resistance. Nanographite slightly reduced friction but enhanced surface smoothness and stability due to its lubricating effect. Interface temperatures remained below 100 °C, preventing thermal degradation of the phenolic binder. Overall, nanomaterial reinforcement effectively enhances the tribological performance of brake friction composites and offers valuable insight for advanced brake pad design.