Abstract
A significant fraction of the non-exhaust particulate matter emissions from vehicular traffic comprises fine particles from the wear debris of brake pads and discs. Recent studies have shown that these emissions can be consistently reduced by using wear resistant disc coatings. This study thoroughly analyses the debris produced by a low-met brake pad, which is dyno-bench tested against both cast iron and WC-CoCr-coated brake discs. To achieve this, particles in the size range of 2.5 µm to 30 nm were collected and characterized. The results showed a consistent reduction in the particle emission as well as in the concentration of iron oxides, which are mainly released from the disc tribo-oxidation in the coated disc. Furthermore, a few tungsten carbides, released from the coating, were also observed in the wear fragments. The results of this study can be useful for improving the protective coating and consequently help in reducing particulate matter emission further.
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Acknowledgements
The authors would like to thank their colleague Gloria Ischia, Ph.D, for her valuable technical assistance for the TEM sample preparation and observations. Our colleague, friend, and project leader, Guido Perricone (Brembo S.p.A.) is also acknowledged for his continuous encouragement in pursuing our goals while working together within the H2020 EU Project: LOWBRASYS — a LOW environmental impact BRAke SYStem-GA: 636592. The EU Commission is acknowledged for its financial support.
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Cinzia MENAPACE. She graduated from materials engineering at the University of Trento in 1999. She received Ph.D degree in metallurgical engineering from the University of Padova (Italy) in 2003. She has been working as a junior and senior researcher at the University of Trento for 20 years. Her current position is the research assistant of metallurgy at University of Trento (Italy). Her research interests include the powder metallurgy, friction materials, and hot workability of metals.
Alessandro MANCINI. He obtained his Ph.D in chemistry at the University of Pavia in 2015, after completing bachelor and master degrees in the same university. Following Ph.D period, he joined Brembo as a research scientist in the Advance R&D Department. His main activities focus on solid material characterization, in particular by means of X-ray techniques such as X-Ray Diffraction, Fluorescence, and Computed Tomography.
Matteo FEDERICI. He is currently undertaking doctoral studies at the University of Trento, Italy. His Ph.D project aims at developing and testing new materials for braking systems able to reduce the particulate matter emissions due to the wear of the brake components. His research interests include the study of the frictional, wear behavior of HVOF-sprayed coatings, and friction materials for automotive and aerospace applications.
Giovanni STRAFFELINI. He received his master degree in materials science and engineering from the University of Trento, Italy, in 1989, and his Ph.D in metallurgical engineering from the University of Padova in 1993. He is currently a full professor in metallurgy at the University of Trento. His research interests include the mechanical properties of sintered alloys and weldments, the tribological behavior of materials, including friction materials for automotive and aerospace brakes, the properties of surface engineered surfaces.
Stefano GIALANELLA.He is an associate professor in materials science and technology. His more recent research interests concern: phase transformations, high temperature oxidation and wear of structural alloys and materials for brake systems, nanostructured materials, their microscopy characterisation, archaeometry, and cultural heritage issues. On these and related subjects, he teaches courses for undergraduate and graduate students of the Departments of Industrial Engineering and of Humanities of the University of Trento, Italy.
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Menapace, C., Mancini, A., Federici, M. et al. Characterization of airborne wear debris produced by brake pads pressed against HVOF-coated discs. Friction 8, 421–432 (2020). https://doi.org/10.1007/s40544-019-0284-4
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DOI: https://doi.org/10.1007/s40544-019-0284-4