Effects of braking conditions on nanoparticle emissions from passenger car friction brakes

Vojtíšek-Lom, Michal; Vaculík, Miroslav; Pechout, Martin; Hopan, František; Raj, Alden Fred Arul; Penumarti, Srinath; Horák, Jiří; Popovicheva, Olga; Ondráček, Jakub; Doušová, Barbora

doi:10.1016/j.scitotenv.2021.147779

Cited by 21 publications

(7 citation statements)

References 12 publications

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“…For the GCI discs, particles concentrated between 10 and 80 nm were observed in Ref. [25], similar to the running-in period in the current study (Fig. 8).…”

Section: Particle Characterizationsupporting

confidence: 88%

Characterization of ultrafine particles from hardfacing coated brake rotors

et al. 2022

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Automotive brake rotors are commonly made from gray cast iron (GCI). During usage, brake rotors are gradually worn off and periodically replaced. Currently, replaced brake rotors are mostly remelted to produce brand-new cast iron products, resulting in a relatively high energy consumption and carbon footprint into the environment. In addition, automotive brakes emit airborne particles. Some of the emitted particles are categorized as ultrafine, which are sized below 100 nm, leading to a series of health and environmental impacts. In this study, two surface treatment techniques are applied, i.e., high-velocity oxygen fuel (HVOF) and laser cladding (LC), to overlay wear-resistant coatings on conventional GCI brake rotors in order to refurbish the replaced GCI brake rotor and to avoid the remelting procedure. The two coating materials are evaluated in terms of their coefficient of friction (CoF), wear, and ultrafine particle emissions, by comparing them with a typical GCI brake rotor. The results show that the CoF of the HVOF disc is higher than those of the GCI and LC discs. Meanwhile, HVOF disc has the lowest wear rate but results in the highest wear rate on the mating brake pad material. The LC disc yields a similar wear rate as the GCI disc. The ultrafine particles from the GCI and LC discs appeared primarily in round, chunky, and flake shapes. The HVOF disc emits unique needle-shaped particles. In the ultrafine particle range, the GCI and HVOF discs generate particles that are primarily below 100 nm in the running-in period and 200 nm in the steady state. Meanwhile, the LC disc emitted particles that are primarily ∼200 nm in the entire test run.

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“…For the GCI discs, particles concentrated between 10 and 80 nm were observed in Ref. [25], similar to the running-in period in the current study (Fig. 8).…”

Section: Particle Characterizationsupporting

confidence: 88%

Characterization of ultrafine particles from hardfacing coated brake rotors

et al. 2022

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“…The most dominant elements in the analyzed metallic particles are Fe followed by O, C, and Si. Additionally, metallic particles contain low concentrations of Al, Ca, Mg, Ti, Cr, Mn, Cu, Zn, and S. The obtained elemental compositions and size range are in good agreement with the expected composition and size of brake wear particles (Harrison et al, 2021;Vojtíšek-Lom et al, 2021). Brake discs are normally dominated by iron (Fe), while brake pads have a more variable composition.…”

Section: Metallic Particles (Brake and Vehicle Wear)supporting

confidence: 76%

“…Brake wear particles are formed due to the mechanical interaction between the brake caliper and rotor during braking (Wahlström et al, 2009) and the release of metals is also dependent on driving behavior and the traffic environment (Folkeson, 2005;Hjortenkrans et al, 2007). Thermal processes at higher temperatures, related to hard or frequent braking, result in high emissions of ultrafine particles (Nosko & Olofsson, 2017;Vojtíšek-Lom et al, 2021). Emissions also depend on vehicle weight, where heavier cars emit more brake wear particles at similar deceleration rates (Oroumiyeh & Zhu, 2021).…”

Section: Introductionmentioning

confidence: 99%

Differentiating and Quantifying Carbonaceous (Tire, Bitumen, and Road Marking Wear) and Non-carbonaceous (Metals, Minerals, and Glass Beads) Non-exhaust Particles in Road Dust Samples from a Traffic Environment

Järlskog

Jaramillo‐Vogel²,

Rausch³

et al. 2022

Water Air Soil Pollut

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Tires, bitumen, and road markings are important sources of traffic-derived carbonaceous wear particles and microplastic (MP) pollution. In this study, we further developed a machine-learning algorithm coupled to an automated scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) analytical approach to classify and quantify the relative number of the following subclasses contained in environmental road dust: tire wear particles (TWP), bitumen wear particles (BiWP), road markings, reflecting glass beads, metallics, minerals, and biogenic/organics. The method is non-destructive, rapid, repeatable, and enables information about the size, shape, and elemental composition of particles 2–125 µm. The results showed that the method enabled differentiation between TWP and BiWP for particles > 20 µm with satisfying results. Furthermore, the relative number concentration of the subclasses was similar in both analyzed size fractions (2–20 µm and 20–125 µm), with minerals as the most dominant subclass (2–20 µm x̄ = 78%, 20–125 µm x̄ = 74%) followed by tire and bitumen wear particles, TBiWP, (2–20 µm x̄ = 19%, 20–125 µm x̄ = 22%). Road marking wear, glass beads, and metal wear contributed to x̄ = 1%, x̄ = 0.1%, and x̄ = 1% in the 2–20-µm fraction and to x̄ = 0.5%, x̄ = 0.2%, and x̄ = 0.4% in the 20–125-µm fraction. The present results show that road dust appreciably consists of TWP and BiWP within both the coarse and the fine size fraction. The study delivers quantitative evidence of the importance of tires, bitumen, road marking, and glass beads besides minerals and metals to wear particles and MP pollution in traffic environments based on environmental (real-world) samples

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“…Brake wear emissions and, importantly, the ultrafine fraction can also be mitigated by promoting smoother braking and less aggressive driving. 45 , 221 …”

Section: Future Scenarios and Mitigation Of Non-exhaust Emissionsmentioning

confidence: 99%

“…Technologies to catch brake wear particles at the source through filtering devices mounted on the brake disc are also under development. , It is expected that brake materials will change dramatically in the future and keeping track of composition and tracers is crucial for apportionment studies and identification in environmental samples. Brake wear emissions and, importantly, the ultrafine fraction can also be mitigated by promoting smoother braking and less aggressive driving. , …”

Section: Future Scenarios and Mitigation Of Non-exhaust Emissionsmentioning

confidence: 99%

A Review of Road Traffic-Derived Non-Exhaust Particles: Emissions, Physicochemical Characteristics, Health Risks, and Mitigation Measures

Fussell

Franklin

Green

et al. 2022

Environ. Sci. Technol.

192

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Implementation of regulatory standards has reduced exhaust emissions of particulate matter from road traffic substantially in the developed world. However, nonexhaust particle emissions arising from the wear of brakes, tires, and the road surface, together with the resuspension of road dust, are unregulated and exceed exhaust emissions in many jurisdictions. While knowledge of the sources of nonexhaust particles is fairly good, source-specific measurements of airborne concentrations are few, and studies of the toxicology and epidemiology do not give a clear picture of the health risk posed. This paper reviews the current state of knowledge, with a strong focus on health-related research, highlighting areas where further research is an essential prerequisite for developing focused policy responses to nonexhaust particles.

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Effects of braking conditions on nanoparticle emissions from passenger car friction brakes

Cited by 21 publications

References 12 publications

Characterization of ultrafine particles from hardfacing coated brake rotors

Characterization of ultrafine particles from hardfacing coated brake rotors

Differentiating and Quantifying Carbonaceous (Tire, Bitumen, and Road Marking Wear) and Non-carbonaceous (Metals, Minerals, and Glass Beads) Non-exhaust Particles in Road Dust Samples from a Traffic Environment

A Review of Road Traffic-Derived Non-Exhaust Particles: Emissions, Physicochemical Characteristics, Health Risks, and Mitigation Measures

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