Alumina-based coating with dimples as enabling sustainable technology to reduce wear and emission of brake system

Brake wear has been recognized as one of the most significant non-exhaust traffic-related sources and considerable contributors to particulate matter emissions. However, brake rotors and pads have to wear for the brakes to harness their braking power. The present research prepares an alumina-based oxide ceramic coating on cast iron brake rotors using plasma electrolytic aluminating (PEA) process. A ceramic pad is used as the counterpart of the tribological coupling. Tribotests show that the PEA coating changed the friction type of brake rotors from abrasive friction to adhesive friction. A thin transfer layer of the brake pad material was formed on the top of PEA coating, and the dimple-like coating surface enhanced the bonding of the transfer layer. Subsequently, only the brake pad was the primary wear component. Compared with uncoated brake rotors in the laboratory test conditions, the coated ones showed almost no wear and led to a reduced wear rate of brake pads to some degree, which indicates that bra...