Tailoring Tribological Performance of Brake Friction Composites Using Copper Coated and Annealed Steel Fiber Reinforcements

ABSTRACT This study presents a novel investigation into the tribological behavior of brake friction composites reinforced with copper‐coated mild steel fibers (CMSF) and copper‐coated annealed steel fibers (CASF), targeting improved wear resistance and frictional stability under dynamic braking conditions. Addressing a key research gap in optimizing metallic fiber surface conditions for thermal and mechanical synergy, the work aims to elucidate the structure property performance relationship associated with different coating volumes and thermal treatments. A series of non‐asbestos organic (NAO) brake pad formulations were fabricated by compound molding, incorporating 50 mL and 100 mL of CMSF and CASF into a standardized friction matrix. Tribological evaluations were conducted using a pin‐on‐disc tribometer per ASTM G99 at varying loads (10–50 N) and speeds (1–3 m/s). Worn surface morphologies were analyzed via SEM to decode wear mechanisms. The results revealed that 50CASF composites achieved the lowest specific wear rate (SWR) (1.2 × 10 ⁻⁶ to 2.5 × 10 ⁻⁶ mm ³ /N·m) and a stable Coefficient of Friction (CoF) (0.42–0.47), attributed to dense debris compaction and protective tribolayer formation. In contrast, 100 CMSF composites exhibited higher wear due to fiber matrix decohesion and debris agglomeration. Microstructural features confirmed that annealing promotes ductile interfacial behavior while copper coating enhances thermal transport and smearing effects. The research establishes clear guidelines for tailoring metallic reinforcement architecture in brake pads, with 50CASF emerging as an optimal formulation for high‐performance applications. The findings offer pathways for designing next‐generation tribo‐materials by engineering reinforcement surfaces for enhanced durability, thermal stability, and consistent braking performance.