Combinatorial Screening of Ingredients for Steel Wool Based Semimetallic and Aramid Pulp Based Nonasbestos Organic Brake Materials

Abstract

Two important factors, good friction performance and low cost, were considered for the selection of raw materials. Ternary composites (A + B + 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, BaSO4, B2O3, BN, brass chips, CaCO3, Ca(OH)2, copper chips, CuS, Cu2S, H3BO3, iron powder, MgO, oxidized polyacrylonitrile (PAN) fiber, PMF (slag fiber), Sb2S3, Ultrafibe (wollastonite) and ZrSiO4 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. CaCO3, Ca(OH)2, MgO, oxidized PAN fiber, Sb2S3 and Ultrafibe with lighter density have good wear resistant performance when they combined with steel wool. BaSO4, 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.