Effect of copper powder third body on tribological property of copper-based friction materials

L, Su; Gao, Fei; Han, Xiaoming; Chen, Jiguang

doi:10.1016/j.triboint.2015.05.003

Cited by 77 publications

(33 citation statements)

References 20 publications

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“…Then, in the following stage, due to the fact that the speed is still in a high range, the friction film of graphite can be destroyed under forces, which results in the increase of the friction coefficient. Then, after a stage of slight fluctuation of the friction coefficient, when the speed decreases to a certain value in the late test stage, the friction coefficient keeps decreasing, indicating that the destruction of graphite friction films is reduced when the speed decreases to a certain range [ 7 , 13 , 14 , 27 ]. It can also be found that when the speed at each pressure decreases to a value below 80 km/h, the friction coefficient keeps decreasing, as indicated by the olive arrows in Figure 7 c,d.…”

Section: Resultsmentioning

confidence: 99%

Study on the Tribological Performance of Copper-Based Powder Metallurgical Friction Materials with Cu-Coated or Uncoated Graphite Particles as Lubricants

Zhang

et al. 2018

Materials

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The tribological performance of copper-based powder metallurgical material is much influenced by the interfacial bonding between the components and matrix. By adding Cu-coated or uncoated graphite particles as a lubricant, two types of copper-based powder metallurgical materials were prepared via spark plasma sintering (SPS). The hardness, relative density, and thermal conductivity of the two specimens were firstly measured. Using an inertial braking test bench and temperature measuring instrument, the average friction coefficients, instantaneous friction coefficients, and friction temperatures of the two specimens were tested under different test conditions, and the wear rates were calculated accordingly. Based on the analysis of surface morphologies and elements distribution after the tests, the mechanisms of wear and formation of friction films were discussed. The results show that with the lubricant of Cu-coated graphite, the hardness, relative density, thermal conductivity, and interfacial bonding between the graphite and matrix can be greatly improved. Under the same test condition, the average friction coefficient, wear rate, and friction temperature of the specimen with added Cu-coated graphite are both lower than those of the specimen with added uncoated graphite. The two specimens show different variation trends in the instantaneous friction coefficient during the tests, and the variation of the instantaneous friction coefficient at a high initial test speed is also different from that at a low initial test speed for each specimen. The two specimens also show differences in the continuity of friction film and the content of graphite and oxide in the friction film.

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Section: Resultsmentioning

confidence: 99%

Study on the Tribological Performance of Copper-Based Powder Metallurgical Friction Materials with Cu-Coated or Uncoated Graphite Particles as Lubricants

Zhang

et al. 2018

Materials

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“…Zhao et al [5,6] studied the friction and wear characteristics of the CFM by pin-on-disc tests; it was implied that temperature had the greatest influence on the wear loss of lubricated CFM clutches, and the COF witnessed a decrease after an increase with the increase of temperature. Su et al [7,8] investigated the tribological properties of CFM with exogenous copper powder third body. Additionally, Kovalchenko et al [9] studied the influence of the molybdenum disulfide and molybdenum diselenite on the friction and wear mechanisms of CFM under the dry condition.…”

Section: Introductionmentioning

confidence: 99%

Comparison of the Friction and Wear Characteristics between Copper and Paper Based Friction Materials

Chen

et al. 2019

Materials

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Copper-based friction material (CFM) and paper-based friction material (PFM) are the two most commonly used clutch friction materials. The friction and wear characteristics of these two kinds of friction materials under dry conditions were investigated by the pin-on-disc test over a broad range of applied loads, rotating speeds and ambient temperatures. Before experiments, the running-in test was conducted to stabilize the coefficient of friction (COF) and wear amount of the test samples. After experiments, the metallographic micrographs of the tested samples were presented to investigate the wear mechanisms. Experimental results showed that both the COF and wear depth of the CFM are much greater than these of PFM. The COF of CFM decreases with the increase of applied load, and changes slightly with the variation of rotating speed, whereas it increases first and then decreases with the increase of ambient temperature. However, the COF of PFM decreases dramatically with the increase of the rotating speed and ambient temperature, while it remains stable at first and then decreases slowly as the applied load increases. Additionally, under such three working conditions, the wear depth of CFM changes linearly, while the wear depth of PFM varies greatly. This study can be used as a guide for selecting friction materials for clutches with different applications.

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“…For low speeds (similar to the speed used in the present investigation), the copper third body lead to an increase in the values of the CoF, due to heavy adhesion and shearing. They also showed that higher speeds or increased pressure promoted a decrease in the values of the CoF lowers, due better fluidity, adhesive and ductility of the third body [97] .…”

Section: Effect Of Copper Additionmentioning

confidence: 96%

“…These copper patches are schematically presented in figure 61. [97] showed that exogenous copper increases the contact area. For low speeds (similar to the speed used in the present investigation), the copper third body lead to an increase in the values of the CoF, due to heavy adhesion and shearing.…”

Section: Effect Of Copper Additionmentioning

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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Effect of copper powder third body on tribological property of copper-based friction materials

Cited by 77 publications

References 20 publications

Study on the Tribological Performance of Copper-Based Powder Metallurgical Friction Materials with Cu-Coated or Uncoated Graphite Particles as Lubricants

Study on the Tribological Performance of Copper-Based Powder Metallurgical Friction Materials with Cu-Coated or Uncoated Graphite Particles as Lubricants

Comparison of the Friction and Wear Characteristics between Copper and Paper Based Friction Materials

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

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