| Summary: The study consists of two stages. In the first stage, experiments were made to evaluate the effects of graphite and hexagonal boron nitride as solid lubricant and aluminum oxide and boron carbide as abrasives on mechanical and tribological properties of brake friction materials. Mechanical tests were done according to the related ASTM standarts at room temperature and tribological tests were performed on a Chase friction material testing machine according to the brake lining quality test procedure as per SAE J661. The friction coefficient and specific wear rate of the composites increased with decreasing solid lubricant and increasing abrasive content. The atomic fraction of Fe on the worn surfaces and wear debris of the composites increased with decreasing solid lubricant and increasing abrasive content. In the second stage, the effects of abrasive particle size on friction and wear characteristics of automotive brake materials were studied. Different particle sizes of Al2O3, SiC and B4C were used as abrasive. The results showed that the friction coefficient of the composites increased and the specific wear rate decreased with increasing abrasive particle sizes. The friction materials showing high wear resistance exhibited a plate shape wear debris, while the materials showing low wear resistance produced fine spherical wear particles. Key Words: Friction, Wear, Brake pad, Solid lubricant, Abrasive, Abrasive particle size |
