A pin-on-disc investigation of novel nanoporous composite-based and conventional brake pad materials focussing on airborne wear particles

Wear particles originating from disc brakes contribute to particulate concentration in the urban atmosphere. In this work novel nanoporous composite-based and conventional brake materials were tested against cast-iron discs in a modified pin-on-disc machine. During testing airborne wear particles were measured online and collected on filters, which were analysed using SEM and EDX. The morphology of airborne wear particles containing elements such as iron, oxygen, and copper is presented. These results show that two of the nanoporous materials generated 3–7 times less airborne wear particles than the conventional materials. Both the conventional and nanoporous materials displayed a bimodal number distribution.