On the nature of tribological contact in automotive brakes

Eriksson, Mikael; Bergman, Filip; Jacobson, Staffan

doi:10.1016/s0043-1648(01)00849-3

Cited by 450 publications

(265 citation statements)

References 9 publications

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“…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%

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 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

“…Posebno je pažnja bila usmerena na uticaj udela pojedinih sirovina u sastavu frikcionih materijala na njihove performanse. U [2] je dat opšti pogled na situaciju u kontaktu frikcionih površina disk pločice i diska, pri čemu je posebna pažnja usmerena na mehanizme koji dovode do pojave varijacije koeficijenta trenja tokom kočenja. Pored toga, analizirano je kakav uticaj na promenljivost koeficijenta trenja u kontaktu frikcionog para kočnice imaju fenomeni kao što su rast i razaranje kontaktnih slojeva, nastajanje tzv.…”

Section: P Pr Re Eg Gl Le Ed D Sunclassified

“…Imajući u vidu da predmet istraživanja u ovoj disertaciji ne obuhvata analizu uticaja osobina i sastava frikcionih materijala, ovo se pre svega odnosi istraživanje sinergijskih uticaja složenih triboloških procesa na nivo i stabilnost koeficijenta trenja, a time i na performanse disk kočnica. U skladu sa [2,10,50,106], koeficijent trenja u kontaktu frikcionog para kočnice mora biti relativno visok i stabilan bez obzira na temperaturu kočnice, trenutnu brzinu vozila, vlažnost, stepen istrošenja elemenata frikcionog para, prisustvo vode ili prljavštine u kontaktu. Situacija u kontaktu frikcionog para disk kočnice i dalje nije dovoljno istražena i shvaćena sa stanovišta načina uticaja pojedinih uticajnih faktora (režimi kočenja, karakteristike materijala u kontaktu, itd.)…”

Section: Fenomeni U Kontaktu Frikcionih Površina Kočniceunclassified

“…Veličina kontaktnih slojeva je detaljno istraživana u [2,110,113]. Pokazano je da njihova veličina varira u zavisnosti od pritiska aktiviranja kočnice.…”

Section: Slika 44 Formiranje Primarnih I Sekundarnih Kontaktnih Slounclassified

“…Time se veća količina materijala koji se nalazi u sloju između frikcionog para sabija, a samim tim i pospešuje rast sekundarnih kontaktnih slojeva (slika 4.4). Prema drugom objašnjenju, povećanje temperature u kontaktu zajedno sa povećanjem pritiska dovodi do stvaranja još boljih uslova za razvoj sekundarnih slojeva [2]. Međutim, rast kontaktnih slojeva ne može biti objašnjen kao potreba za većom površinom u kontaktu frikcionog para da bi se prenelo veće normalno opterećenje [106].…”

Section: Slika 45 Promena Veličine Kontaktnog Sloja Prema [106]unclassified

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