Mitigation of friction coefficient fade and enhancement of friction stability in PEEK fiber-reinforced resin-based friction materials fabricated by wet granulation

This study investigated the effects of silane coupling agent (SCA) treatment and Polyether-ether-ketone (PEEK) fiber content on the performance of resin-based friction materials (RBFMs) fabricated by wet granulation. Surface modification of PEEK fiber with three different SCA was characterized, and KH-550 exhibited the most effective improvement in interfacial compatibility. The regulatory mechanism of KH-550 on the interfacial bonding between PEEK fiber and phenolic resin was elucidated which was beneficial for the cumulative heat fade resistance and braking stability. The tribological properties and wear mechanisms of RBFMs with varying PEEK fiber contents (0–8 wt%) were systematically evaluated under simulated braking conditions. The results demonstrated that an optimal PEEK fiber content of 6 wt% significantly reduced the friction coefficient at lower temperatures and minimized its fluctuations, leading to more stable braking performance. Moreover, RBFMs with 6 wt% PEEK fiber exhibited superior resistance to heat fade during repeated braking cycles, attributed to the high strength and intrinsic thermal stability of PEEK fiber, and at the same time, it achieved a 15.69% reduction in wear loss compared to the control sample at 193–216 °C. The enhanced wear resistance and stable friction behavior were attributed to improved fiber-matrix bonding and verified by the formation of continuous secondary plateaus on worn surface, as revealed by SEM analysis. This work provides a practical strategy for designing high-performance RBFMs with enhanced thermal and frictional stability.