Dynamometric Investigation on Airborne Particulate Matter from Brake of Automobile: Impact of Disc Materials on Brake Emission Factor

Non-exhaust airborne particulate matter (PM) from automobiles might lead to potential adverse effects on the respiratory system. In this work, we evaluated the impact of surface properties of disc rotors on brake wear PM emission for passenger vehicles. Dynamometric measurements using the novel cycle were made for gray cast iron (GCI), nitrocarburized (NC), and superhard ceramic coated (SCC) disc rotors using non-steel (N/S) friction materials. The brake emission factors (BEF) for the GCI and NC disc rotors ranged from 1.76 to 1.74 mg/km/vehicle, whereas that of the SCC rotor exhibited a much-reduced value of 0.50 mg/km/vehicle. As the hardness of the SCC rotor increases (> 1150 HV), lower BEF was obtained, whereas the coefficient of friction (COF) of the SCC disc was more than 20 % higher than the NC rotor. Temperature-dependent data indicated that disc temperature (T_disc) for the SCC disc (~115 °C) was lower than that for the GCI and NC (T_disc >130 °C).