Wear mechanism evolution on brake discs for reduced wear and particulate emissions

Brake disc wear contributes heavily to particulate matter as non-exhaust emission in the transportation sector. To tackle this issue, research on this topic has so far been directed at obtaining a hard and dense disc surface to reduce abrasive wear. The present research manipulates the disc surface morphology so that an adhesive transfer layer can be formed during sliding to protect the disc from wear. The designed interlocking surface was prepared using plasma electrolytic aluminating (PEA) process. A non asbestos organic (NAO) brake pad was used for tribotests. The results showed that the PEA-treated brake disc exhibited negligible wear because of the thin protective layer generated by the pad material transfer onto the PEA-treated cast iron. The dimple-like surface, produced through the PEA process, enhanced the bonding of the transfer layer due to mechanical interlocking. The coated surface increased the coefficient of friction of the disc to some extent. The surface also resulted in a reduced wear rate of the brake pad, highlighting the potential for the PEA process to enable reduced wear debris and thus non-exhaust emission through an altered wear mechanism in future brake disc applications.