Namgung, Hyeong-Gyu Kim, Jong-Bum Woo, San-Hee Park, Sechan Kim, Minhae Kim, Min-Soo Bae, Gwi-Nam Park, Duckshin Kwon, Soon-Bark 2024-01-20T04:31:47Z 2024-01-20T04:31:47Z 2021-09-05 2016-04-05 0013-936X https://pubs.kist.re.kr/handle/201004/124179 In this study, we measured the size distribution of particles ranging in size from 5.6 to 560 nm that were emitted between brake disks and pads under various braking conditions to observe and analyze changes to the resulting particle size distribution over braking time:A peak of 178-275 nm (200 nm peak) was observed in all braking conditions. However, the generation of spherical particles of a 10 nm range was observed only when the disk speed and brake force were above certain levels and intensified only when speed and brake force further increased. The total number concentration of ultrafine particles (no larger than 0.1 mu m; PM0.1) generated was found to correlate with disk speed and brake force. Thus, the generation of nanoparticles resulting from disk speed and brake force was attributable primarily to increases in the contact surface temperature. The critical temperature for the generation of nanoparticles of a 10 nm range was found to be about 70 degrees C, which is the average temperature between the surface and the inside of the disk. If the speed or brake force was higher, that is, the temperature of the contact surface reached a certain level, evaporation and condensation took place. Vapor then left the friction surface, met with the air, and quickly cooled to form nanoparticles through nucleation. When the newly generated particles became highly concentrated, they grew through coagulation to form agglomerates or the vapor condensed directly onto the surface of existing particles of about 200 nm (formed by mechanical friction). English American Chemical Society AIRBORNE PARTICULATE MATTER SUBWAY PARTICLES ANTIMONY SOURCES METAL EMISSIONS ABRASION DUSTS WEAR DEBRIS SIZE STATIONS Generation of Nanoparticles from Friction between Railway Brake Disks and Pads Article 10.1021/acs.est.5b06252 1 Environmental Science & Technology, v.50, no.7, pp.3453 - 3461 Environmental Science & Technology 50 7 3453 3461 scie scopus 000373655800019 2-s2.0-84964284929 Engineering, Environmental Environmental Sciences Engineering Environmental Sciences & Ecology Article AIRBORNE PARTICULATE MATTER SUBWAY PARTICLES ANTIMONY SOURCES METAL EMISSIONS ABRASION DUSTS WEAR DEBRIS SIZE STATIONS friction railway brake disk nanoparticle wear particle