Tribological and Mechanical Characterisation of Non-Asbestos Brake Pad Composite Materials

Abstract

Brake pad friction materials are safety-critical components that must simultaneously deliver stable, adequate friction coefficient over a wide range of temperatures and sliding speeds, minimal wear (to ensure acceptable service life), low heat generation at the brake interface (to prevent thermal fade and rotor damage), mechanical strength sufficient to resist compressive and shear loading, and environmental acceptability — a requirement that has progressively eliminated asbestos from brake pad formulations worldwide due to its carcinogenic properties. This paper presents the design, fabrication, and comprehensive tribological and mechanical characterisation of five brake pad composite formulations: a conventional asbestos baseline (F1) and four non-asbestos organics (NAO) incorporating Al₂O₃ at 5 and 10 weight percent (F2, F3) and SiC at 5 and 10 weight percent (F4, F5) as ceramic reinforcement particulates in a phenolic resin matrix with barite, copper fibre, and graphite as functional additives. All composites were fabricated by hot compression moulding at 150°C and 15 MPa. Tribological testing followed a Taguchi L9 design on a pin-on-disc tribometer, characterising specific wear rate and coefficient of friction (CoF) across three loads (10, 20, 30 N) and three sliding speeds (2, 6, 10 m/s). ANOVA identifies composition (filler type and weight fraction) as the dominant factor for wear rate (52.4% contribution). The SiC 10 wt% composite (F5) achieves the lowest specific wear rate (1.24 mg/km, 56.3% reduction over asbestos baseline) and highest CoF (0.462), while maintaining a stable CoF fade ratio of 0.91 under thermal loading and interface temperature rise of only 86°C — 39.4% lower than the asbestos baseline. SEM and EDS analysis confirm oxidative-abrasive wear with protective tribofilm formation in F5, compared to severe adhesive wear and fibre pullout in the asbestos composite. All non-asbestos formulations satisfy Indian Standard IS 2742 friction material performance requirements.

Cite as:

Pranmesh B. (2026). Tribological and Mechanical Characterisation of Non-Asbestos Brake Pad Composite Materials. Recent Innovations in Material Engineering, 2(2), 30–39. https://doi.org/10.5281/zenodo.21884038