Friction and wear of friction materials containing two different phenolic resins reinforced with aramid pulp

Friction and wear characteristics of automotive friction materials containing two different phenolic resins (a straight novolac resin and a modified novolac resin) were investigated using a pad-on-disk type friction tester. Six different friction materials with different relative amounts of the phenolic resins and aramid pulp were manufactured and tested. Two different test modes were employed to examine the friction characteristics concerning accumulated thermal history (a constant initial temperature test: test mode I) and friction heat (a constant interval test: test mode II). Friction characteristics such as friction stability and wear resistance were changed significantly according to the type of phenolic resins and to the relative amount of the resin and aramid pulp. Friction materials with the modified novolac resin showed better friction stability than those with the unmodified novolac resin. In particular, the friction materials that were reinforced with 10 vol.% of aramid pulp showed substantial improvement on friction stability regardless of the resin type. However, the friction materials with the modified resin showed significant reduction in wear resistance. (C) 2000 Elsevier Science Ltd. All rights reserved.