A combinatorial approach for automotive friction materials: Combined effects of ingredients on friction performance

The combined effects of ingredient A and C in A + B + C systems where A and C are Al2O3, graphite, MoS2, steel wool and Twaron (aramid pulp),. and B is a binder (benzoxazine) on friction performance were studied. Ray design with Golden Section was used for the formulated A + B + C ternary composites. Two combined factors, morphological combinations including fiber/fiber, fiber/filler and filler/filler and combinations by means of material nature including abrasive/abrasive, abrasive/lubricant and lubricant/lubricant, and their composition dependence were considered. Synergetic effects, defined as a minimum wear in wear-composition relationships, were found in morphological combinations of fiber/filler (steel wool/Al2O3/B and Twaron/Graphite/B systems). Synergetic effects producing maximum values in friction coefficient (mu)-composition curves were not found in all combinations. Ail combinations of lubricant/lubricant and abrasive/abrasive. reduce mu and the effects of the combinations of abrasive/lubricant are dependent upon their abrasive or lubricant efficiency. Strong abrasive (Al2O3) plays an important role on the formation of friction layer that the transferred iron from disc to friction materials in combinations. of Al2O3/lubricant/B systems, and there is no such a transfer of iron from disc to friction materials on the surface of lubricant/lubricant combinations. The S type friction transition was observed in MoS2/steel wool/B and graphite/steel wool/B systems and was caused by adhesion friction mechanism.