Exploring the beneficial role of tribofilms formed from an epoxy-based hybrid nanocomposite

Österle, Werner; Дмитриев, А. И.; Gradt, Thomas; Häusler, Ines; Hammouri, B.; Guzmán, P. I. Morales; Wetzel, Bernd; Yiğit, Deniz; Zhang, G.

doi:10.1016/j.triboint.2015.03.006

Cited by 38 publications

(22 citation statements)

References 22 publications

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“…The low friction observed if such a film had formed was attributed to the mixing of the silica with a soft constituent such as graphite or epoxy particles [13]. An additional experiment performed with pure silica nanoparticles did not provide low friction during sliding at an ambient temperature of approximately 300 K [15]. This coincides in principle with results of the MD simulations (Figure 7), showing unstable and initially high friction forces at 300 K. Also shown in Figure 7, performing the simulation at 1100 By applying 4 GPa pressure the density of the amorphous carbon is increased, reaching almost the density of diamond.…”

Section: Discussionmentioning

confidence: 94%

MD Sliding Simulations of Amorphous Tribofilms Consisting of either SiO2 or Carbon

2016

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Abstract:The sliding behaviors of two simplified tribofilms with amorphous structure consisting either of SiO 2 molecules or C atoms were simulated by molecular dynamics modeling. The objective was to identify mechanisms explaining the experimentally observed lubricating properties of the two amorphous films. The impacts of layer thickness, normal pressure, temperature and different substrate materials were studied systematically, while the sliding velocity was kept constant at 30 m/s. While the layer thickness was not critical, all the other parameters showed special effects under certain conditions. Normal pressure impeded void formation and could even eliminate voids if applied at high temperature. Stick-slip sliding was changed to smooth sliding at high temperature due to void healing. Considering the carbon film, high friction forces and shearing of the entire film was observed with diamond substrates, whereas interface sliding at low friction forces and an amorphous layer of iron mixed with carbon was observed if the supporting substrates consisted of α-Fe. Both films show a decrease of friction forces and smooth sliding behavior at elevated temperature, corresponding well to the tribological behavior of an advanced nanocomposite sliding against a steel disc under severe stressing conditions when high flash temperatures can be expected.

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Section: Discussionmentioning

confidence: 94%

MD Sliding Simulations of Amorphous Tribofilms Consisting of either SiO2 or Carbon

2016

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“…Since only acetone-cleaned discs were considered during this previous study, we repeated the tests with freshly ground discs. Although, first results of this comparison were already presented in a separate paper [4], we have decided to discuss them here once more in the context of new findings. The following materials acted as reference materials for taking "fingerprint" Raman spectra: SiO 2 nanopowder (Sigma Aldrich, Taufkirchen, Germany), pure epoxy (IVW, Kaiserslautern, Germany) and the original 100Cr6 discs treated with silicone oil by the manufacturer (INA, Schaeffler group, Germany).…”

Section: Methodsmentioning

confidence: 99%

“…The standard cleaning procedure is immersion in acetone, wrapping with acetone-soaked paper and rinsing with isopropanol. A study described in [4] has shown that this procedure leads to the same tribological behaviour as mechanical removal of a surface layer by grinding. Despite that, we observed an indication of silicone oil residue by analytical TEM while investigating a thin lamella prepared from a wear scar of a disc which was previously cleaned with acetone.…”

Section: Introductionmentioning

confidence: 98%

“…Discs made of 100Cr6 are widely used as counterbodies for all kinds of polymer matrix composites (PMCs) by the present authors [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and others as well. The steel discs are usually supplied with a grinded surface providing an average surface roughness of R a ¼ 0.3 mm.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies with SEM/EDS [5] and TEM/ EDS [4] revealed the importance of silica nanoparticles (SNPs) for film formation, but the extent to which carbonaceous species contribute to tribofilm structure and functionality were not scrutinized. Therefore, we applied Raman spectroscopy as additional method because of its high sensitivity towards both polymer and carbonaceous materials.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Exploring the potential of Raman spectroscopy for the identification of silicone oil residue and wear scar characterization for the assessment of tribofilm functionality

Österle

Giovannozzi

Gradt

et al. 2015

Tribology International

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Effect of lubricant functional groups on tribological properties of epoxy/graphene composites

Zheng,

Zhang,

et al. 2024

J of Applied Polymer Sci

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The functional group in the molecular chain of lubricants is a key factor for a boundary lubricating film, which can further enhance the friction performance by interfacial tribochemistry. In this paper, the tribological behavior of epoxy/graphene (EP/Gra) composites was investigated through varying lubrication conditions, including dry friction, or different lubricants (such as water, hexadecane, oleylamine, and oleic acid). The porosity and Shore hardness (SHD) of the EP composites were significantly improved by the addition of graphene. Results showed that the porosity of the EP/0.75 wt.% Gra composites was reduced by 75.6% and their SHD increased by 5.4 compared with the EP/0.05 wt.% Gra composites. The average coefficient of friction (COF) of the composites was reduced by at least 27.3% under dry friction conditions. For water as lubricant, the EP/0.5 wt.% Gra composite exhibited the lowest COF (0.0455). The EP/0.75 wt.% Gra composite displayed the lowest COF (0.0466) when hexadecane acted as lubricant. By contrast, EP/0.05 wt.% Gra showed the lowest COF (0.0389) with oleylamine as lubricant, and the EP/0.25 wt.% Gra composites gave the lowest COF (0.0433) under oleic acid. The amine group of oleylamine reacted with the EP group to form a hydroxyl group, resulting in a polymer with low friction adhered to the friction interface. Simultaneously, the EP group reacted with the carboxyl group, forming a network of hydrogen bonds with graphene, which reduced the shear stress on the friction interface. Therefore, the functional groups of lubricants have a vital influence on the tribological properties of frictional composites, which may provide a new approach to solving the problem of wear.

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Exploring the beneficial role of tribofilms formed from an epoxy-based hybrid nanocomposite

Cited by 38 publications

References 22 publications

MD Sliding Simulations of Amorphous Tribofilms Consisting of either SiO2 or Carbon

MD Sliding Simulations of Amorphous Tribofilms Consisting of either SiO2 or Carbon

Exploring the potential of Raman spectroscopy for the identification of silicone oil residue and wear scar characterization for the assessment of tribofilm functionality

Effect of lubricant functional groups on tribological properties of epoxy/graphene composites

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