A brake pad material used in a popular, commercially available vehicle that consisted of steel wool, iron powder, graphite, coke, styrene-butadiene rubber, MgO, BaSO 4 , and phenolic resin was tested with the friction assessment and screening test. The average friction coefficient (0.357) and total wear (19.75 wt %) were measured. An alternative friction material formulated with identical constituents but optimized with the golden section principle and relational grade analysis was produced in a laboratory environment. This material exhibited an average friction coefficient of 0.419 and a low total wear of 6.25 wt %. An analysis of component costs indicated that the large volume price of the commercial material, $1.01/kg, was less than that of the laboratory material, $1.21/kg. However, the performance/cost ratio of the new material was appreciably greater.

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Two important factors, good friction performance and low cost, were considered for the selection of raw materials. Ternary composites (A þ B þ C systems where A is steel wool or aramid pulp belonging to good wear resistant raw material group, B is an organic binder benzoxazine and C is an ingredient belonging to poor wear resistant raw material group) were designed to evaluate the interaction effects of A and C on friction performance. Seventeen ingredients, BaSO 4 , B 2 O 3 , BN, brass chips, CaCO 3 , Ca(OH) 2 , copper chips, CuS, Cu 2 S, H 3 BO 3 , iron powder, MgO, oxidized polyacrylonitrile (PAN) fiber, PMF (slag fiber), Sb 2 S 3 , Ultrafibe (wollastonite) and ZrSiO 4 combined respectively with steel wool or aramid pulp, tested using Friction Assessment and Screening Test (FAST) were classified into good (FAST can be lasted for 90 min), intermediate (FAST can be lasted for 90 min at one given composition) and poor (FAST cannot be lasted for 90 min at two given compositions) wear resistant performance. CaCO 3 , Ca(OH) 2 , MgO, oxidized PAN fiber, Sb 2 S 3 and Ultrafibe with lighter density have good wear resistant performance when they combined with steel wool. BaSO 4 , PMF and Ultrafibe have good wear resistant performance when they are combined with aramid pulp. The roles of steel wool and aramid pulp in the ternary friction materials were identified. The formation of iron-containing friction layer is an important factor to improve wear in steel wool based ternary composites and the excellent wear resistant performance of aramid pulp contributes to aramid pulp based ternary composites.

A semimetallic friction material formulation consisting of Al 2 O 3 , B 2 O 3 , brass chips, graphite, NBR (nitrile rubber), steel wool, and benzoxazine (a ring-opening polymerized phenolic) with high friction coefficient () and low wear was developed using the Golden Section approach to search the optimal volume fraction of each ingredient in the formulations. All raw materials used were divided into three groups: fibers, fillers, and binder. The volume fraction of each ingredient in the formulations was calculated by means of, were proposed to correlate the compositional dependence of wear and . The least-squares error method was utilized to calculate the effect of each ingredient on and wear. Experimental and calculated results proved that both brass chips and B 2 O 3 play important roles in enhancing . After doing 18 formulation experiments that preformed using Friction Assessment and Screening Test (FAST), an optimized formulation (BB-17) with high (average ¼ 0.701) and low wear (w ¼ 4.74%) was obtained.

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