Study on the characterisation of the PTFE transfer film and the dimensional designing of surface texturing in a dry-lubricated bearing system

Liang, Ding; Axinte, Dragoş; Butler-Smith, Paul; Hassan, Ali Abdelhafeez

doi:10.1016/j.wear.2020.203238

Cited by 30 publications

(23 citation statements)

References 35 publications

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“…A reduction of wear debris' size and fewer cracks were observed, both of which likely contributed to the superior wear performance. The effects of area density and depth on wear were also reported in a recent study of Ding et al [182]. They observed that shallow dimples with low area densities demonstrated enhanced film formation ability, thus compensating for negative edge effects that increase abrasion (Figure 11 In an innovative study, Wang et al recently electro-deposited MoS2/PTFE mixtures (PTFE content between 0 and 20 wt.-%) in textures fabricated on a laser-cladded, wear-resistant Fealloy [190].…”

Section: Ptfe and Surface Texturessupporting

confidence: 70%

“…Most of these employed hard textured substrates such as stainless steel [179][180][181][182][183], bronze [184][185][186], silicon [187] or laminated ceramics [188,189], which were rubbing against an untextured PTFE nano-composite. Surface textures were mainly produced by LST using lasers with pulse durations ranging from micro- [179,181,[184][185][186] and nano- [188,189] to pico- [182] and femtoseconds [180,187]. Regarding the geometry of the textures, research effort has focused on dimples [179, 181-183, 185, 186, 188, 189], unidirectional grooves [180], grid-like textures, and circumferentially or radially aligned grooves [184].…”

Section: Ptfe and Surface Texturesmentioning

confidence: 99%

“…Temporal evolution of the (a) COF and (b) wear depth for narrow and shallow dimples having different area densities ranging from 0.4 to 6.4%. Reprinted (adapted) with permission from[182].…”

mentioning

confidence: 99%

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Synergetic effects of surface texturing and solid lubricants to tailor friction and wear – A review

Rosenkranz

Costa

Baykara

et al. 2021

Tribology International

314

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Surface texturing and solid lubricants have demonstrated the ability to substantially reduce friction and wear under dry conditions. In recent decades, these two technologies have been combined to leverage the advantages of both for superior tribological performance. This review article first summarizes the state-of-the-art regarding surface texturing and solid lubricants, including soft metals, polytetrafluoroethylene, diamond-like carbon and 2D layered materials. Then, the synergy between surface textures and solid lubricants is discussed, with particular emphasis on the underlying mechanisms. Finally, gaps in the existing understanding of these synergies are identified and opportunities for future research are suggested.

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Section: Ptfe and Surface Texturessupporting

confidence: 70%

Section: Ptfe and Surface Texturesmentioning

confidence: 99%

See 1 more Smart Citation

Synergetic effects of surface texturing and solid lubricants to tailor friction and wear – A review

Rosenkranz

Costa

Baykara

et al. 2021

Tribology International

314

View full text Add to dashboard Cite

show abstract

“…The formation of the transfer film is affected by the physical properties of the counter surface. For instance, the average roughness [11] or surface texturing [12] can have a great impact on the formation of the transfer film. There is a general consensus about the observation that in sliding PTFE/steel contacts the friction coefficient decreases while the wear rate increases with increasing contact pressure [9,10,13].…”

Section: Introductionmentioning

confidence: 99%

A Combined Experimental and Atomistic Investigation of PTFE Double Transfer Film Formation and Lubrication in Rolling Point Contacts

Goeldel

Reichenbach

König

et al. 2021

Preprint

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Solid lubricants such as polytetrafluoroethylene (PTFE) are used in rolling-element bearings (REBs) when conventional lubrication (i.e. by fluids or greases) cannot be applied owing to extreme operating conditions (e.g. high temperatures or vacuum). Often a double transfer film mechanism is used with a cage acting as a lubricant reservoir resupplying the REB with solid lubricant by cage wear. An increase in service life of such bearings requires a better understanding of the transfer processes in the sliding and rolling contacts. Here, we investigate the effect of PTFE resupply on friction and lubricant film formation in a steel/steel and steel/glass rolling contact by tribometry and classical molecular dynamics (MD). A ball-on-disk tribometer is enhanced by a pin-on-disk sliding contact that transfers PTFE to the disk. The experiment allows simultaneous in situ measurement of friction and film thickness by white light interferometry in the rolling point contact. Increasing the pin load results in an increased PTFE film thickness in the rolling contact accompanied by a significant decrease in friction. To elucidate the observed film transfer and friction mechanism, sliding MD simulations with a newly developed density-functional-based, non-reactive force field for PTFE-lubricated iron oxide surfaces are performed. A strong adhesion of PTFE chains to iron oxide drives transfer film formation, while shear-induced chain alignment within PTFE results in reduced friction. The simulations reveal an anti-correlation between PTFE film thickness and friction coefficient – in agreement with the experiments. These investigations are a first step towards methods to control PTFE transfer film formation in REBs.

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“…Figure19. New seal fracture surface with thin layer separating lip coating from remaining seal material.…”

mentioning

confidence: 99%

Analysis of the tribological interaction of a polytetrafluoroethylene-lined radial lip oil seal, shaft and lubricant sample

Shabbir

Garvey

Dakka

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part J:

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To investigate the tribological interaction and wear mechanisms of polytetrafluoroethylene-lined radial lip oil seals in service, a sleeve, seal and lubricant sample taken off a rotating rig are studied. The test was terminated at 72 h, after severe leakage in the final 15 h of the test. All three components are studied using a coherence scanning interferometer and environmental scanning electron microscopy to investigate wear after testing. Results show a wear band on the aerospace grade case-hardened sleeve, appearing as a ‘polished in’ area by the seal. A study of the filler content of the polytetrafluoroethylene coating uncover glass fibres, calcium carbonate, carbon and graphite layers present, assumed responsible for the wear to the sleeve. The polytetrafluoroethylene coating is a 300 μm coating, distinct from the bulk elastomer. This finding is confirmed after observing this layer on both, the tested and new seal lip. Wear of the seal lip is measured and facilitated by comparison to the identical new seal. Lastly, debris from the seal and sleeve wear are found in the lubricant sample.

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Study on the characterisation of the PTFE transfer film and the dimensional designing of surface texturing in a dry-lubricated bearing system

Cited by 30 publications

References 35 publications

Synergetic effects of surface texturing and solid lubricants to tailor friction and wear – A review

Synergetic effects of surface texturing and solid lubricants to tailor friction and wear – A review

A Combined Experimental and Atomistic Investigation of PTFE Double Transfer Film Formation and Lubrication in Rolling Point Contacts

Analysis of the tribological interaction of a polytetrafluoroethylene-lined radial lip oil seal, shaft and lubricant sample

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