Abrasive and lubricant materials for brake pads

Lubricants and abrasives are key components in brake discs, as the former plays a significant role in maintaining brake pad friction and the latter affects stopping distance, noise sensitivity, and disc wear. This chapter provides an in-depth analysis of brake pad lubricants and abrasives, highlighting their impact on friction, stability, and wear behavior, based on recent research. Commercial brake friction materials utilize abrasives like zircon, quartz, alumina, magnesia, and zirconia based on their hardness, size, shape, fracture toughness, wear resistance, and aggressiveness against counter discs. Information on abrasive effects on brake performance is limited due to difficulties in analyzing abrasive behavior in multiphase composites and proprietary reasons. As far as lubricants are concerned, graphite is the most commonly used in friction materials. Besides graphite, other lubricants such as h-boron nitride (h-BN), MoS2, and other sulfides are widely used in friction materials. As with abrasives the size and shape of lubricants also influence performance by modifying wear resistance and coefficient of friction at different loads and speeds