Effects of aramid fiber concentration on the friction and wear characteristics of non-asbestos organic friction composites using standardized braking tests

• Aramid fibers benefited almost all properties of friction materials, the extent depended on amount.
• There was no strict linearity in property enhancement and amount.
• In general, higher the amount better were the properties.
• 6 wt% of AF proved optimum for best tribo-performance and cost.

Aramid fiber/pulp (AF*) is one of the most important ingredients, of non-asbestos organic (NAO) friction materials (FMs). In spite of its relatively high cost, it is invariably added to good quality FMs (~3 wt%) because it improves their wear resistance and processability. The present research was prompted by the need to optimize the amount of the pulp required to achieve the best performance. Six FMs were prepared. They contained aramid fiber/pulp additions from 0 to 10 wt% and were characterized for their physical, mechanical, chemical and tribological performance. Composites were evaluated on a full-scale brake inertia dynamometer following the procedure in a Japanese automobile testing standard (JASO C406). The 10 wt% aramid FM showed best overall performance while the composite without fibers was worst. Worn surfaces were characterized using scanning electron microscopy and energy-dispersive X-ray analysis.