Synergistic effects of aramid pulp and potassium titanate whiskers in the automotive friction material

Friction and wear of automotive brake friction materials were investigated using a pad-on-disk type friction tester to study the Synergistic effects of aramid pulp (fibrillated organic fibers) and potassium titanate whiskers (fine ceramic whiskers). The friction materials were based on a simple formulation with five ingredients (phenolic resin, aramid pulp, potassium titanate whiskers, molybdenum disulfide, and barite). Friction stability, wear rate, and morphology of sliding surfaces were carefully examined to investigate the effect of the two different fibrous ingredients in the friction material on various friction properties. The results showed that both aramid pulp and potassium titanate whiskers played a crucial role for the friction characteristics by maintaining the durable friction film on the rubbing surface. The friction film provided improved friction stability and wear resistance. Microscopic observations of the friction material exhibited that the fine ceramic whiskers adhered to the fibrillated aramid fibers, providing heat resistance and strength to the friction film at the rubbing interface. The beneficial synergistic effect from the two fibrous ingredients, however, was significantly diminished when only one of them was employed. (C) 2001 Elsevier Science B.V. All rights reserved.