Ceramic Abrasives in Brake Friction Materials

The role of the ceramic abrasives including zircon (ZrSiO₄), alumina (Al₂O₃), and silicon carbide (SiC) in non-asbestos organic (NAO) brake friction composites were summarized through preparation of friction composites, friction performance tests, and friction surface analysis. The characteristic of the abrasives is higher hardness compared with the cast iron disc. The brake friction composites without abrasives show the lower friction coefficient (μ) and lower specific wear rate due to the adhesion friction effect. Adding the abrasives to friction composites, the values of μ can be enhanced and the wear rate was higher due to the abrasion friction effect. According to friction surface characterized by SEM with EDX, the friction layers were observed and analyzed. A model related to both adhesion and abrasion friction effects to explain the friction performance of the brake friction materials varied as the function of the content of abrasives is proposed and the critical (optimized) volume fraction of the abrasives can be found by the intersection point around 0.034-0.056.