Synergistic Effect of Nano- and Micrometer-Size Ceramic Fibers on the Tribological and Thermal Properties of Automotive Brake Lining

Tribological and thermal behavior of both micrometer-sized ceramic fiber and nanometer-sized potassium titanate whisker (PTV) reinforced automotive brake linings were investigated. Friction stability and wear rate were measured by the CHASE test. Morphology and thermal stability were examined by environmental scanning electron microscopy and thermogravimetric analysis, respectively. It is important to emphasize that the friction performances were studied under the application condition. The results revealed that combined fiber-reinforced materials had higher impact strength, friction stability, and wear resistance than those with only one type of fiber. Moreover, combined fiber-reinforced materials exhibited higher thermal stability than materials with only ceramic fiber. The strong synergistic effect is attributed to heat resistance and good filler retention of nanometer-sized potassium titanate whiskers, and hardness of micrometer-sized ceramic fiber. Furthermore, the friction materials reinforced with both ceramic fiber and PTV exhibited a smooth worn surface, resulting from the synergistic effect of combined fibers to improve the wear resistance.