Tribological surfaces of organic brake pads

Eriksson, Mikael; Jacobson, Staffan

doi:10.1016/s0301-679x(00)00127-4

Cited by 419 publications

(250 citation statements)

References 7 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%

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

Kukutschová

Roubíček

Malachová

et al. 2009

Wear

151

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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

151

View full text Add to dashboard Cite

show abstract

“…It is known that the real area of contact between a brake disc and pad in operation is much smaller than the apparent contact area [12,13,14]. This is implicit in classical theories of friction, but in brakes it is emphasised by:…”

Section: The Fe Modeling Approach For Analysis Of Pad Temperature Dismentioning

confidence: 99%

“…Eriksson & Jacobson [13] explained that primary and secondary contact plateaux are formed at the contact surface of a friction pad; the primary plateaux form first due to the lower removal rate of the mechanically stable and wear resistant ingredients of the pad, such as metal fibres. The secondary plateaux are formed by compacted wear debris initiated by the protruding hard phase, i.e.…”

Section: The Fe Modeling Approach For Analysis Of Pad Temperature Dismentioning

confidence: 99%

“…For example, as a comparison in Table 6, the maximum temperature changed only by 50 °C when the contact area ratio changed by half (from 1 to 0.55), whereas it changed by 100 °C when the ratio changed by only 0.168 (from 0.55 to 0.39). In an actual friction braking condition, the effective disc/pad contact area would be expected to be less then half of its apparent contact area [12,13].…”

Section: Effect Analysis Of Contact Area Ratios With Fe Approachmentioning

confidence: 99%

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Investigation of disc/pad interface temperatures in friction braking

Qi¹,

Day²

2007

Wear

108

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Maintaining appropriate levels of disc-pad interface temperature is critical for the overall operating effectiveness of disc brakes and implicitly the safety of the vehicle.Measurement and prediction of the distribution and magnitude of brake friction interface temperatures are difficult. A thermocouple method with an exposed hot junction configuration is used for interface temperature measurement in this study.Factors influencing the magnitude and distribution of interface temperature are discussed. It is found that there is a strong correlation between the contact area ratio and the interface maximum temperature. Using a designed experiment approach, the factors affecting the interface temperature, including the number of braking applications, sliding speed, braking load and type of friction material were studied. It was found that the number of braking applications affects the interface temperature the most. The real contact area between the disc and pad, i.e. pad regions where the bulk of the kinetic energy is dissipated via friction, has significant effect on the braking interface temperature. For understanding the effect of real contact area on local interface temperatures and friction coefficient, Finite Element Analysis (FEA) is conducted. It is found that the maximum temperature at the friction interface does not increase linearly with decreasing contact area ratio. This finding is potentially significant in optimising the design and formulation of friction materials for stable friction and wear performance. Tave Change of average temperature of the brake pad body (°C) DoE A statistical design of experiments approach emf ElectroMotive Force WIRE An exposed wire thermocouple configuration for brake disc/pad interface temperature measurement RUB A rubbing thermocouple for brake disc surface temperature measurement Key words

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Tribology of Polymeric Solids and Their Composites

Briscoe¹,

Sinha²

2005

Wear – Materials, Mechanisms and Practice

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Tribological surfaces of organic brake pads

Cited by 419 publications

References 7 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

Investigation of disc/pad interface temperatures in friction braking

Tribology of Polymeric Solids and Their Composites

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