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A study on emission of airborne wear particles from car brake friction pairs
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).ORCID iD: 0000-0002-5259-1426
KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.ORCID iD: 0000-0003-2489-0688
2015 (English)In: SAE International Journal of Materials & Manufacturing, ISSN 1946-3979, E-ISSN 1946-3987, Vol. 9, no 1, 147-157 p., 2015-01-2665Article in journal (Refereed) Published
Abstract [en]

The emission of airborne wear particles from friction material / cast iron pairs used in car brakes was investigated, paying special attention to the influence of temperature. Five low-metallic materials and one non-asbestos organic material were tested using a pin-on-disc machine. The machine was placed in a sealed chamber to allow airborne particle collection. The concentration and size distribution of 0.0056 to 10 μm particles were obtained by a fast mobility particle sizer and an optical particle sizer. The temperature was measured by a thermocouple installed in the disc. The experiments show that as the temperature increases from 100 to 300 °C the emission of ultrafine particles intensifies while that of coarse particles decreases. There is a critical temperature at which the ultrafine particle emission rate rises stepwise by 4 to 6 orders of magnitude. For the friction pairs investigated, the critical temperature was found to be between 165 and 190 °C. Below the critical temperature, fine particles outnumber coarse and ultrafine particles, although coarse particles make up the bulk of the particulate matter mass. The friction pairs differ in the ultrafine particle emission rate by 1 to 2 orders of magnitude. Above the critical temperature, ultrafine particles constitute almost 100% of the total particle number and their relative mass contribution can exceed 50%. Analysis of the particle size distributions revealed peaks at 0.19-0.29, 0.9 and 1.7 μm. Above the critical temperature, one more peak appears in the ultrafine particle range at 0.011-0.034 μm.

Place, publisher, year, edition, pages
2015. Vol. 9, no 1, 147-157 p., 2015-01-2665
National Category
Tribology
Identifiers
URN: urn:nbn:se:kth:diva-169695DOI: 10.4271/2015-01-2665ISI: 000386445700018Scopus ID: 2-s2.0-84975807242OAI: oai:DiVA.org:kth-169695DiVA: diva2:824628
Projects
Rebrake
Funder
EU, FP7, Seventh Framework Programme, 324385
Note

QC 20160211

Available from: 2015-06-22 Created: 2015-06-22 Last updated: 2017-12-04Bibliographically approved
In thesis
1. Particle emissions from car brakes: The influence of contact conditions on the pad-to-rotor interface
Open this publication in new window or tab >>Particle emissions from car brakes: The influence of contact conditions on the pad-to-rotor interface
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Due to their adverse health effects emissions have been regulated for over three decades. Brake wear particulate matter is the most important non-exhaust source, however current knowledge is mainly limited to observational studies. This thesis aims to investigate relations between the brake system contact conditions and the related emissions on a model scale; validate the results on a component level; and understand to what extent they are significant on a full-scale.

Paper A investigates the influence of nominal contact pressure on a model scale. Results show that higher pressure corresponds to higher emissions

Paper B investigates the influence of the nominal contact pressure, for different friction materials, on a model scale. A temperature threshold, responsible for a relevant emission increase, is identified.

Paper C investigates particle characteristics and wear mechanisms for different nominal contact pressures, on a model scale. Results show an enhanced tribo-layer at higher pressure levels.

Paper D investigates the influence of brake system conditions on emissions, on a model scale. Results show that frictional power is the most important parameter. A transition temperature independent of the contact condition is identified.

Paper E investigates similarities occurring on a component scale and a model scale in terms of emissions. Results show a promising correlation, and the possibility of using a pin-on-disc tribometer for R&D activities.

Paper F investigates analogies occurring on a component scale and a model scale, in terms of friction performance, fictional surface and chemical composition. Results show similar phenomena occurring for the two test stands.

Paper G analyses real brake system working conditions in a urban environment defining, by means of an inertia dyno bench, the related emissions. Results reveal emission factors compliant to EURO6 and EURO2 regulations, in terms of number and mass, respectively.

Abstract [sv]

På grund av deras negativa hälsoeffekter har partikel emissioner reglerats i över tre årtionden. Bromsslitagepartiklar är den viktigaste icke-avgaskällan, men nuvarande kunskaper är huvudsakligen begränsade till observationsstudier. Avhandlingen syftar till att undersöka förhållandena mellan bromssystemets kontaktförhållanden och de relaterade utsläppen på modellskala. Validera resultaten på komponentnivå och förstå i vilken utsträckning de är betydande i full skala.

Papper A undersöker påverkan av nominellt kontakttryck i en modellskala. Resultat visar att högre tryck motsvarar högre utsläpp.

Papper B undersöker påverkan av det nominella kontakttrycket, för olika friktionsmaterial, i modellskala. En temperaturtröskel,  för en emissionsökning identifieras.

Papper C undersöker partikelegenskaper och slitagemekanismer för olika nominella kontakttryck, i en modellskala. Resultat visar ett förbättrat triboskikt vid högre trycknivåer.

Papper D undersöker påverkan av bromssystemets förhållanden på utsläpp i en modellskala. Resultat visar att friktionskraften är den viktigaste parametern. En övergångstemperatur oberoende av kontaktförhållandet identifieras.

Papper E undersöker likheter som uppträder på komponentskala och  modellskala när det gäller emissioner. Resultatet visar en lovande korrelation, och möjligheten att använda en pinne-på-skiva-tribometer för FoU-aktiviteter.

Papper F undersöker analogier som förekommer på en komponentskala och en modellskala, vad gäller friktionsprestanda, friktionsyta och kemisk sammansättning. Resultat visar liknande fenomen som förekommer för de två testskalorna.

Papper G analyserar verkliga bromssystem arbetsförhållanden i en stadsmiljö som definierar, med hjälp av en tröghetsdyno bänk, de relaterade utsläppen. Resultatet visar utsläppsfaktorer som är förenliga med EURO6 och EURO2-reglerna, i fråga om antal respektive massa.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. 52 p.
Series
TRITA-MMK, ISSN 1400-1179 ; 2017:03
Keyword
Car brakes emissions, transition temperature, working conditions, environmental design, pin-on-disc, Bilbromsutsläpp, övergångstemperatur, arbetsförhållanden, miljödesign, pinne-på-skiva
National Category
Mechanical Engineering
Research subject
Machine Design
Identifiers
urn:nbn:se:kth:diva-208701 (URN)978-91-7729-462-7 (ISBN)
Public defence
2017-09-29, Gladan, Brinellvägen, 83, Stockholm, 10:00 (English)
Opponent
Supervisors
Projects
REBRAKE Project
Note

QC 20170808

Available from: 2017-08-08 Created: 2017-06-13 Last updated: 2017-09-08Bibliographically approved

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Nosko, OleksiiOlofsson, Ulf

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