The reliable chemical characterization of non-exhaust emissions generated by brakes is of fundamental importance in order to provide correct information for source apportionment studies as well as for their toxicological and environmental assessment.[1,2,3] Nowadays, the best option to obtain samples of PM10 emissions composed only by material worn from the tribological interface, i.e. the braking disc (BD) and friction material (FM) rubbing surfaces, is to sample them on suitable collection filters at a dedicated dyno-bench, during a standard braking test cycle. In particular, the use of enclosed dyno-bench is necessary for excluding other spurious contributions from the environment, while defined test cycles are necessary to simulate standard driving conditions.[4] Nevertheless, different braking cycles are usually characterized by different overall temperature profiles or energy indexes, which in the end have significant influence on the wear and the oxidation of the materials involved in the tribological event. Thus, the chemical composition of the PM10 emissions is also expected to be influenced by the temperature and the test cycle. At this regard, the work investigates the difference in terms of chemical composition of two PM10 samples generated by the same tribo-couple (standard cast iron BD and standard ECE R90 FM) during the LACT-3h and the WLTP-Brake test cycles. More in detail, a wide physico-chemical characterization performed by SEM/EDXS and XRD analysis is used to unveil how braking cycles influence both the elemental and phase composition of the generated emissions. This will provide useful insights regarding the correlation between driving conditions, relative consumption of the tribological interface and chemistry of the emitted particulates.
References: [1] C. Menapace, A. Mancini, M. Federici, G. Straffellini, S. Gialanella, “Characterization of Airborne Wear Debris Produced by Brake Pads Pressed against HVOF-Coated Discs”, Friction, 2019. [2] M. Figliuzzi, M. Tironi, L. Longaretti, A. Mancini, F. Teoldi, F. Sangalli, A. Remuzzi, “Copper‑dependent biological effects of particulate matter produced by brake systems on lung alveolar cells”, Archives of Toxicology, 2020, 94, 2965-2979. [3] A. Mancini, B. Tsyupa, S. Pin, F. Bertasi, M. Bandiera, M. Federici, G. Perricone, A. Bonfanti, E. Bolzacchini, “Novel Approaches for Physico-Chemical characterization of Brake Emissions”, EuroBrake2021, 2021, EB2020-EBS-031. [4] G. Perricone, J. Wahlstrom, M. Alemani, U. Olofsson, A. Ciotti, “A Novel Dyno Bench Design Focussing On Measurements In Controlled Air Of Particle Emission From Brakes”, EuroBrake2015, 2015, EB2015-EFP-005.