Performance Evaluation of Composite Friction Materials: Influence of Nature and Particle Size of Graphite

This article deals with the role of graphite in friction materials on fade and recovery (F & R) properties especially in the context of its origin and particle size. Two series of composites with identical composition differing only in the type of graphite were developed and evaluated for their performance. These two series of composites, designated as S N and S S , were based on natural and synthetic graphites (of the same crystallinity ~75%), respectively and contained graphites which differed in particle size (460, 130, and 20 μm in S N and 460, 160, and 35 μm in S S ). These friction composites were evaluated for their F & R performance following ECE R-90 regulation. The μ-performance, μ-fade, and μ-recovery were significantly influenced by the nature and particle size of graphites. It was observed that natural graphite was more effective to boost the μ-performance than the synthetic graphite. The fade property remained appreciably unaffected by the particle size in the series S N whereas in S S the fade resistance tended to increase with the decrease in particle size. The disc temperature rise in S S was observed to be larger than that in S N . Worn surface analysis by SEM proved to be useful in understanding the wear mechanisms.