Influence of fly ash and waste tire rubber particles on mechanical and tribological properties of composite brake linings

To investigate the influence of waste tire rubber (WTR) and fly ash (FA) on mechanical and tribological properties of composite brake linings, 8 different formulations of 8–40 wt% FA and 10–12 wt% WTR were selected. The mechanical tests showed that high amounts of resin and FA result in the highest hardness. The inclusion of WTR, decreased hardness and internal shear strength; however, increased the acetone extraction and resistance to coefficient of friction (COF) fluctuations. With the use of WTR, steady COF fluctuations with the temperature changes are achieved. The tribological properties were evaluated with both a drum-type and disc-type dynamometer by the SAE-J661 standard. Reduced COF fluctuations were observed in <15 wt% FA and 10 wt% WTR containing samples. The highest COF was obtained for the 14 wt% FA and the lowest wear rate for the samples containing 8 wt% FA. The brake composites exhibited consistent COF in the range of 0.34–0.52, and wear rates lower than 7 wt%. Two compositions containing 40 and 25 wt% FA (no WTR), and one containing 10 wt% WTR and 8 wt% FA provided the best results. Finally, four best compositions were selected and worn surfaces were analyzed with SEM after full-scale dynamometer tests. Highlights: Three composites with high waste percentage were successfully manufactured Fly ash and waste rubber are used without any post-processing to cut costs Waste rubber increased resistance to COF fluctuations with temperature change Full-scale dynamometer tests are performed for friction and wear properties Worn surfaces were analyzed with SEM method.