Characterization of brake particles emitted from non-asbestos organic and low-metallic brake pads under normal and harsh braking conditions

Development of Dust Collectors to Reduce Brake Wear PM Emissions

“…The mode diameters of BWP mass distributions were 4 µm and 2 µm when using the LM pad or the NAO pad, respectively. Park et al [20] as well as Woo et al [11] also reported that BWPs from the LM pad were larger than those from the NAO pad. Figure 6 shows the particle number concentration variation measured by the CPC and the ELPI during the WLTP-brake.…”

“…It was shown that the number of charges when using the NAO pad was higher than that for the LM pad. Woo et al [11] reported that the Fe composition ratio of BWPs when using the NAO pad was only 40%, and other components such as Ti, Ca, Ba, and Si were largely contained in BWPs. The Fe composition ratio of BWPs when using the LM pad was above 60%, and there were almost no other elements.…”

“…The rotating weight was 120 cm in diameter and had a mass of 280 kg,; it was installed on the brake dynamometer axis. The rotation simulated a moment of inertia of 50.4 kg m 2 , equivalent to the vehicle curb weight plus one passenger, and assuming a brake force distribution (BFD) of 7/3 between the front and rear brakes [11]. The vehicle speed was calculated based on 16-inch wheels fitted with 205/65 tires.…”

“…Atmosphere 2022, 13, x FOR PEER REVIEW 5 of 14 The world harmonized light-duty test cycle (WLTC, Tutuianu et al [29], Figure 3a) and the world harmonized light vehicles test procedure for brake emissions (WLTP-brake, Mathissen et al [30], Figure 3b) were used in this study. Originally, the WLTC was developed to evaluate exhaust emissions; however, multiple studies have used the WLTC to measure BWPs emissions [11,19,20]. Notably, Woo et al [19] reported that the highest emission factor of BWPs was measured when using the WLTC.…”

“…Various studies, including those that concern improvements in the materials that constitute brake discs and pads, coating the brake disc surface with an additional material, resizing the brakes, use of drum brakes, regenerative braking, and aftertreatment devices to directly collect BWPs, have all been conducted in order to reduce brake wear PM emissions [9]. Generally, it is known that BWPs can be significantly reduced by using nonasbestos organic (NAO) brake pads rather than low-metallic (LM) brake pads [10,11]. The addition of a zinc (Zn) component to the brake pad material could reduce brake wear [12], and coating the brake disc surface with nickel (Ni) could enhance wear resistance [13].…”