Friction layers and friction films on PMC brake pads

Österle, Werner; Urban, I.

doi:10.1016/j.wear.2003.12.017

Cited by 162 publications

(101 citation statements)

References 29 publications

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“…These findings well correlate with earlier work of Filip [10,27] and were also supported by Eriksson and Jacobson [16] and Oesterle [17], although the last two referenced authors did not show the complexity of the layer and its variation within one patch. Since the friction layer most likely represents the major part of released wear particles, further analysis was performed.…”

Section: µM µMsupporting

confidence: 91%

“…These findings further support formerly published data by Filip [15] revealing the complex character of the "friction layer". It is necessary to note that the friction layer is called "friction film" by several authors [17,18,19], and it was also described as "transfer layer" [20,21], "transfer film" [22], "third body" layer [17,23], "tribo-layer" [2], "tribofilm" [24], "mechanically mixed layer" (MML) [25], and as "first and secondary plateaus" [16,26]. Former work of Filip [27] clearly demonstrated that the friction layer consists of very fine wear particulates that are pressed and sintered together and chemistry of this layer can vary within one pad and also within one "patch".…”

Section: µM µMmentioning

confidence: 99%

See 1 more Smart Citation

Wear mechanism in automotive brake materials, wear debris and its potential environmental impact

Kukutschová

Roubíček

Malachová

et al. 2009

Wear

150

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A model semi-metallic brake lining was subjected to full scale automotive brake dynamometer tests. The structural properties and surface topography of brake linings were analyzed at different stages of wear testing and correlated to frictional performance. Characteristics of released wear particles were also addressed. A combination of abrasive and adhesive wear with oxidative processes dominated the friction process. Formation of a friction layer adhering to the friction surfaces of pads and discs is the major feature responsible for friction performance. Characteristics of the friction layer depend mostly on surface temperature, normal pressure, and sliding speed. It is a newly formed sintered composite matter consisting of a mixture of wear particulates. Wear rates and friction levels depend on chemistry, structure and hardness of the friction layer covering the surface of a pad or a disc; however, there is no simple Archard-type relationship between wear and measured hardness.Wear debris generated during the dynamometer tests was collected from containers placed under the brake inside dynamometer chamber. The collected debris was compared with ball-milled particles from identical brake lining. It is necessary to combine several analytical methods to characterize wear particles properly. The presence of copper and iron oxides as well as carbonaceous components is typical for all collected debris samples. Chemistry of wear debris resembles chemistry of the friction layer. Composition, mutagenic potency and pulmonary toxicity of wear debris and ball-milled particles were also analyzed. Mutagenic potency of initial friction composite and wear particles was evaluated by two in vitro bacterial microbioassays (SOS Chromotest, Ames test). Obtained results show potency of wear particles for interacting with DNA after metabolic activation, which indicates the presence of indirect mutagens. The pulmonary toxicity test on rats revealed an acute response of the lung tissue to the ball-milled particles. Further research is necessary to address the role of brake wear particles and potential impact of sub-chronic exposure to wear debris.

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Section: µM µMsupporting

confidence: 91%

Section: µM µMmentioning

confidence: 99%

Wear mechanism in automotive brake materials, wear debris and its potential environmental impact

Kukutschová

Roubíček

Malachová

et al. 2009

Wear

150

View full text Add to dashboard Cite

show abstract

“…The mesoscopic contact situation has been numerically simulated and validated by tests conducted in an inertia dynamometer bench by Wahlström [23]. On the microscopic scale, Österle et al [24], [24] observed that the friction is determined by the shearing of a 100 nm thick nanocrystalline tribofilm that covers both the contact surfaces. This tribofilm is formed by a combination of plastic deformation, compaction, oxidation, and mechanical mixing of wear particles.…”

Section: Discussionmentioning

confidence: 99%

Contact Pressure and Sliding Velocity Maps of the Friction, Wear and Emission from a Low-Metallic/Cast-Iron Disc Brake Contact Pair

et al. 2017

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“…Organic pads themselves are widely used to pair with a cast iron brake disc for a brake in a road vehicle. As known already, friction performance of a brake is highly sensible to the composition of such type of friction material 3,4,5,6,7 . However, there is not yet sufficient tribological knowledge published about a friction pair that consists of C f /C-SiC and low metallic friction material, whilst one may expect that extensive testing must have been done in industry to achieve/optimise the required friction performance of a carbon ceramic brake, as noted by Krenkel in the early time 8 .…”

Section: Introductionmentioning

confidence: 86%

“…For a traditional cast iron brake disc, when it is tested against typical organic or sintered pads, a friction transfer layer, typically composed of a dense mixture of iron oxides and compounds such as lubricants, fillers and abrasives that originated from pads 4,17 , is fairly easily developed with a strong bond through fusing with iron matrix. Therefore, the focus of a cast iron brake has always been on the friction layer development on the contact surface of a pad, because it is the friction surface of a pad that largely dictates the bedding time required for a cast iron brake, as well as the level of friction coefficient after bedding.…”

Section: Introductionmentioning

confidence: 99%

Friction performance of carbon/silicon carbide ceramic composite brakes in ambient air and water spray environment

Bian

2015

Tribology International

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Citation: BIAN, G. and WU, H., 2015 AbstractWe have examined friction performance, friction surface structure and chemistry of a carbon/silicon carbide ceramic brake disc tested against an organic pad in air, and water sprayenvironment. An average friction coefficient of 0.52 and 0.4 for a braking stop is achieved after bedding in air for a composite disc comprising 53.1% and 17.7% SiC/Si, respectively. It is identified that 100% SiC/Si and ~50% C f /C regions contribute the friction measurement.Tested in water spray, both brakes show a substantial fall of friction coefficient to a level <0.1.Evidences are provided for the existence of hydrodynamic friction. Friction transfer materials removal, SiC region polishing, and lower real contact pressure reinforce hydrodynamic process that a ceramic composite brake can experience.

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Friction layers and friction films on PMC brake pads

Cited by 162 publications

References 29 publications

Wear mechanism in automotive brake materials, wear debris and its potential environmental impact

Wear mechanism in automotive brake materials, wear debris and its potential environmental impact

Contact Pressure and Sliding Velocity Maps of the Friction, Wear and Emission from a Low-Metallic/Cast-Iron Disc Brake Contact Pair

Friction performance of carbon/silicon carbide ceramic composite brakes in ambient air and water spray environment

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