Third Body Formation on Brake Pads and Rotors

Oesterle, Werner; Urban, I.

doi:10.4271/2004-01-2767

Cited by 24 publications

(38 citation statements)

References 24 publications

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“…The character of the friction layer is in direct relation to bulk composite formulation, and selection of proper ingredients and their combination significantly influences the friction-wear properties of the prepared composite [14][15][16][17]. By studying the friction layer and comparing it with the character of the composite surface before braking, information about the friction process can be obtained.…”

Section: Introductionmentioning

confidence: 99%

Semi-metallic Brake Friction Materials Containing ZrSiO4: Friction Performance and Friction Layers Evaluation

2009

Journal of Composite Materials

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The effect of ZrSiO 4 (zircon) content on friction performance and friction surfaces of semimetallic brake friction materials is discussed. The experimental results indicate that the varying content of zircon affects the friction performance as well as plays crucial role in the iron film formation on the friction surfaces. The friction layers, formed during friction process, were carefully characterized using scanning electron microscopy with energy dispersive X-ray microanalysis, and X-ray diffraction methods. The phenomenon of two different types of iron film formation (film I and film II) on the friction surfaces is proposed and their formation and destruction mechanism is described. Despite the compositions of both iron films being similar, film I is formed by steel wool itself and film II by the debris from either disc or steel wool. The relationships among formulation, friction performance, and friction surfaces are summarized.

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Section: Introductionmentioning

confidence: 99%

Semi-metallic Brake Friction Materials Containing ZrSiO4: Friction Performance and Friction Layers Evaluation

2009

Journal of Composite Materials

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“…A plastically deformed layer was also shown in their study. A comprehensive characterization of this third-body and transfer layers started over a decade ago with the studies of Österle and Urban (2006) [64] on the role of the microstructure and third body on friction properties of brake materials, showing the presence of several nanocrystalline oxide phases on the tribosurfaces for different compositions of the brake pad tribosystems.…”

Section: Tribofilm Microstructural Characterizationmentioning

confidence: 99%

“…By characterizing the transfer layers, it was possible to observe the nanocrystalline microstructure of the third-body on the tribosurfaces [29,64,65] . They concluded that besides mechanical mixing, oxidation is also responsible for the production of wear debris and the formation of the friction layer.…”

Section: Tribofilm Microstructural Characterizationmentioning

confidence: 99%

“…They concluded that besides mechanical mixing, oxidation is also responsible for the production of wear debris and the formation of the friction layer. They suggested one focus for further studies was to work out differences of friction layer formation for selecting new pad material formulations to fulfil the environmental criteria [64] .…”

Section: Tribofilm Microstructural Characterizationmentioning

confidence: 99%

“…Several studies reported the presence of iron and iron oxide within the debris, as well as the presence of copper transferred from the brake pads to the brake disc [65][66][67][68] . Further investigation showed the iron oxide within the wear particles is mostly composed of magnetite (Fe3O4) [64,69] , and that obtaining smooth sliding conditions requires mixing magnetite with the other pad constituents [70] .…”

Section: Tribofilm Microstructural Characterizationmentioning

confidence: 99%

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Effect of nanoparticulate copper, zirconia and graphite: contribution to the friction coefficient and transfer layer formation in dry sliding tests with interfacial media addition.

Rodrigues¹

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Copper is present in brake pads in the form of fibres, tough its suppression from pads' formulations is already a trend compared to the suppression of asbestos in the 1980's.As a contribution to this challenging scenario, this work investigated the behaviour of mixture additions containing copper, zirconia, graphite and magnetite in dry sliding tribotests. Pin-on-disc tribotests with interfacial media addition were performed in order to contribute on the mission of understanding how Cu, graphite and ZrO2 particles act on the oxide transfer layer formation on dry sliding conditions. Thus describing some of the tribological properties that a possible replacement for copper in brake pads should mimic. Tests were performed at 23°C in air, 400°C in air and 400°C in N2.Nanoparticulate Cu, ZrO2 and micron-sized graphite were mixed in a Fe3O4 basedmatrix. The ZrO2 particles were incorporated to the mixtures by two mixing methods: manual mixing and high-energy ball milling. This study sought to explain the coefficient of friction (CoF) behaviour of these additions individually, as well as together, by correlating the CoF with comprehensive characterization of the oxide transfer layer. The transfer layer was characterized by means of scanning electron microscopy (SEM), Focused Ion Beam (FIB) and Transmission electron microscopy. Graphite containing mixtures displayed low average CoF values (0.23 to 0.31) due to selective transfer of graphite films to the first bodies' tribosurfaces. Copper formed agglomerates and patches within the oxide transfer layer that were responsible for raising the CoF values at 23°C and acted as soft copper films at 400°C. The nanoparticulate addition of ZrO2 in the manual mixtures prevented the formation of Cu patches and larger agglomerates, promoting the formation of a smooth and compact oxide tribolayer, though graphite's selective transfer was still observed.

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Brake wear particle emissions: a review

Grigoratos

Martini

2014

Environ Sci Pollut Res

652

346

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Traffic-related sources have been recognized as a significant contributor of particulate matter particularly within major cities. Exhaust and non-exhaust traffic-related sources are estimated to contribute almost equally to traffic-related PM10 emissions. Non-exhaust particles can be generated either from non-exhaust sources such as brake, tyre, clutch and road surface wear or already exist in the form of deposited material at the roadside and become resuspended due to traffic-induced turbulence. Among non-exhaust sources, brake wear can be a significant particulate matter (PM) contributor, particularly within areas with high traffic density and braking frequency. Studies mention that in urban environments, brake wear can contribute up to 55 % by mass to total non-exhaust traffic-related PM10 emissions and up to 21 % by mass to total traffic-related PM10 emissions, while in freeways, this contribution is lower due to lower braking frequency. As exhaust emissions control become stricter, relative contributions of non-exhaust sources—and therefore brake wear—to traffic-related emissions will become more significant and will raise discussions on possible regulatory needs. The aim of the present literature review study is to present the state-of-the-art of the different aspects regarding PM resulting from brake wear and provide all the necessary information in terms of importance, physicochemical characteristics, emission factors and possible health effects.

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Third Body Formation on Brake Pads and Rotors

Cited by 24 publications

References 24 publications

Semi-metallic Brake Friction Materials Containing ZrSiO4: Friction Performance and Friction Layers Evaluation

Semi-metallic Brake Friction Materials Containing ZrSiO4: Friction Performance and Friction Layers Evaluation

Effect of nanoparticulate copper, zirconia and graphite: contribution to the friction coefficient and transfer layer formation in dry sliding tests with interfacial media addition.

Brake wear particle emissions: a review

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