Effects of silicon carbide particle sizes on friction-wear properties of friction composites designed for car brake lining applications

Apart from the service conditions during the braking (e.g. applied pressure, velocity of rotor) the friction-wear properties of friction composites used as a car brake lining are directly influenced by their composition. Among the components used for a car brake lining, the chemical and structural nature of the abrasives, jointly with the morphology and size of the particles, influence the friction parameters and stability of the composite. In the present paper the effect of silicon carbide abrasive of various particle sizes (40, 10, and 3 μm) on the friction-wear properties of friction composites based on potassium titanate ceramics is summarized. The composites with an increasing amount of the abrasive in composition (3.4, 5.6, 9.0, and 14.6 vol%) for each SiC size were prepared. The highest values of friction coefficient as well as the lowest fade for the composites containing the finest SiC fraction (median value 3 μm) were obtained. Contrary to the friction coefficient, the values of specific wear rate decrease with increasing SiC particle size. Transport of the iron particles, originated from the cast iron rotor, increases with SiC particle size and decreases with the testing temperature.