Friction and vibration of automotive brake pads containing different abrasive particles

Automotive brake friction materials with four different abrasive particles were investigated. The abrasives used in this study were commercial grade silicon carbide, zircon, quartz and magnesia. For microscopic understanding of friction and wear by abrasive particles in the brake friction material, single-particle scratch tests followed by scratch tests with multiple particles were performed first to understand the behavior of abrasive particles at the sliding interface during brake applications. The results showed that the fracture toughness of the abrasives played a crucial role in determining the friction level, wear debris formation and stick–slip. The friction material with silicon carbide exhibited a microcutting mode with considerable stick–slip behavior, indicating a possible high propensity of noise occurrence during brake applications. On the other hand, the quartz and magnesia particles with low fracture toughness showed relatively small stick–slip amplitudes, suggesting that the fracture toughness of the abrasives can play important roles on the noise and vibration occurred during brake applications.