Macroscopic Evidence of Thermally Activated Friction with Polytetrafluoroethylene

Burris, David L.; Perry, Scott S.; Sawyer, W. Gregory

doi:10.1007/s11249-007-9237-6

Cited by 30 publications

(33 citation statements)

References 28 publications

(36 reference statements)

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“…Michael et al [1], Theiler et al [2], and Hubner et al [3] compared results of ambient lab air testing with those of test submerged in cryogenic liquids and have shown either no trend or trends of reduced friction at cryogenic temperatures. Recent constant environment macroscale studies of various solid lubricants [4][5][6][7], and atomic-scale studies with terraces of graphite [8] show consistent trends of increased friction with decreased temperature, and the notion of thermally activated friction has been proposed [4,8,9]. Variable temperature experiments conducted on beds of aligned carbon nanotubes [10] and various high temperature polymer studies [11][12][13][14][15][16] have also demonstrated behavior that is well fit by an activated process at the macroscale.…”

Section: Introductionmentioning

confidence: 78%

“…In systems that are low wear and thought to have interfacial sliding in macroscopic experiments monotonic temperature dependences in the direction of increasing friction coefficient with decreasing temperature have been observed. Fits to activation energy give values between 2 and 12 kJ/mol [4,5,10].…”

Section: Measurements Of Steady-state Wear Rates In Mos 2 Coatingsmentioning

confidence: 99%

“…The liquid nitrogen volatilizes prior to arrival at the disk surface. Experiments and discussion in Burris et al [4] suggest that this technique is likely free of frost down to approximately -100°C. Figure 1 shows a plot that is produced at the end of four experimental runs on self-mated MoS 2 /C/Sb 2 O 3 coatings.…”

Section: Introductionmentioning

confidence: 95%

“…Due to water adsorption and frost, macroscopic measurements of friction coefficient in cryogenic temperature ranges requires that experiments are performed in either vacuum or a gas environment with very little water vapor (this was discussed and demonstrated in detail by Burris et al [4]). Clean graphitic terraces provide model surfaces on which to perform nanotribology measurements, but they suffer from high wear in the dry environments necessary for cryogenic experiments.…”

Section: Introductionmentioning

confidence: 99%

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A Possible Link Between Macroscopic Wear and Temperature Dependent Friction Behaviors of MoS2 Coatings

et al. 2008

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Studies to explore the nature of friction, and in particular thermally activated friction in macroscopic tribology, have lead to a series of experiments on thin coatings of molybdenum disulfide. Coatings of predominately molybdenum disulfide were selected for these experiments; five different coatings were used: MoS 2 /Ni, . The temperatures were varied over a range from -80°C to 180°C. The friction coefficients tended to increase with decreasing temperature. Activation energies were estimated to be between 2 and 10 kJ/mol from data fitting with an Arrhenius function. Subsequent room temperature wear rate measurements of these films under dry nitrogen conditions at ambient temperature demonstrated that the steady-state wear behavior of these coatings varied dramatically over a range of K = 7 9 10 -6 to 2 9 10 -8 mm 3 /(Nm). It was further shown that an inverse relationship between wear rate and the sensitivity of friction coefficient with temperature exists. The highest wearrate coatings showed nearly athermal friction behavior, while the most wear resistant coatings showed thermally activated behavior. Finally, it is hypothesized that thermally activated behavior in macroscopic tribology is reserved for systems with stable interfaces and ultra-low wear, and athermal behavior is characteristic to systems experiencing gross wear.

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Section: Introductionmentioning

confidence: 78%

Section: Measurements Of Steady-state Wear Rates In Mos 2 Coatingsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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A Possible Link Between Macroscopic Wear and Temperature Dependent Friction Behaviors of MoS2 Coatings

et al. 2008

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“…The general hypothesis of thermally activated friction involves the notion that local potential barriers on contacting surfaces may be overcome thermally, thereby facilitating slippage [18,21]. A logical extension of this hypothesis suggests a reduction in friction with increasing temperature.…”

Section: Introductionmentioning

confidence: 99%

Effect of Temperature on the Friction and Wear of PTFE by Atomic-Level Simulation

et al. 2015

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The tribological behavior of oriented, selfmated poly(tetrafluoroethylene) (PTFE) sliding surfaces is examined as a function of temperature from 25 to 300 K. Three distinct sliding configurations are considered: sliding perpendicular to the chain alignment in both PTFE surfaces, sliding parallel to chain alignment in both PTFE surfaces and sliding parallel to the chain alignment on one surface but perpendicular to chain alignment on the other. Our simulations reveal a general trend of increasing friction coefficient with decreasing temperature for configurations where the chains are aligned in the direction of sliding or crossed. However, for conditions where the chains are aligned but the sliding motion is perpendicular to this alignment, gross deformation and athermal friction behaviors are observed. The atomic-level processes associated with these increases in friction at low temperatures are characterized.

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Lubricating performance of polytetrafluoroethylene hybrid fabric composites with removed thermosetting resin at cryogenic temperatures

Wang

2023

J of Applied Polymer Sci

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At cryogenic temperatures, the higher friction coefficient of conventional fabric composites severely inhibits the application of hybrid polytetrafluoroethylene (PTFE)/amide fabric composites in pivotal tribological pairs such as plain bearings operated at low temperatures. In order to improve the lubricating properties of fabric composites at cryogenic and wide temperature ranges, a novel hybrid PTFE/Nomex fabric composite is prepared by peeling off the facial phenolic formaldehyde resin through the Hot-Press Mechanical Stripping method, which is named Phenolic Formaldehyde Mechanical Stripping (PFMS). The friction coefficient of PFMS is 0.06 at 296 K, and can be as low as 0.1 at 123 K, reduced by up to 58% compared to conventional fabric composite without resin removal. Furthermore, the friction coefficient of PFMS first increases and then decreases as the temperature decreases, the turning point falls in the range around the temperature of 181 K, corresponding to the γ relaxation transition of the PTFE. The wear of the fabric composites, the microstructure, and the chemical composition of the transfer film are comprehensively investigated. The results demonstrate that thermal activation and increased mechanical properties contribute to friction coefficient variation above and below the temperature of 181 K, respectively.

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Macroscopic Evidence of Thermally Activated Friction with Polytetrafluoroethylene

Cited by 30 publications

References 28 publications

A Possible Link Between Macroscopic Wear and Temperature Dependent Friction Behaviors of MoS2 Coatings

A Possible Link Between Macroscopic Wear and Temperature Dependent Friction Behaviors of MoS2 Coatings

Effect of Temperature on the Friction and Wear of PTFE by Atomic-Level Simulation

Lubricating performance of polytetrafluoroethylene hybrid fabric composites with removed thermosetting resin at cryogenic temperatures

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