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

Abstract 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 (μ)‐composition curves were not found in all combinations. All combinations of lubricant/lubricant and abrasive/abrasive reduce μ 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.