A fractional coverage model for gas–surface interaction in reciprocating sliding contacts

Sawyer, W. Gregory; Dickrell, Pamela L.

doi:10.1016/s0043-1648(03)00346-6

Cited by 10 publications

(2 citation statements)

References 32 publications

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“…During heating from 225 K the friction coefficient showed little hysteresis (a deviation thought to be associated with ice melting was observed just below 273 K). Collectively these results suggest that below the frost-points ice formed on the wear tracks-perhaps in a competitive rates fashion [23,24]-and that the presence of ice provides a weaker pathway to interfacial slip.…”

Section: Resultsmentioning

confidence: 87%

Macroscopic Evidence of Thermally Activated Friction with Polytetrafluoroethylene

2007

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Under macroscopic pin-on-disk testing the sliding friction coefficient of Polytetrafluoroethylene (PTFE) was investigated over a temperature range of approximately 200-400 K. This study examines the nature of the temperature dependence by testing PTFE pins at varying temperature and humidity on a linear reciprocating pin-on-disk tribometer. The friction coefficient increased monotonically with decreasing temperature from l = 0.075to l = 0.210 in a manner consistent with thermal activation; it deviated from this trend only during phase and glass transitions in the PTFE and temperatures below the frost-points for the respective environments.

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Section: Resultsmentioning

confidence: 87%

Macroscopic Evidence of Thermally Activated Friction with Polytetrafluoroethylene

2007

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“…There has been considerable progress in understanding the relation between friction coefficient and surface fraction covered by gas species. ,− Heimberg et al revealed that a friction coefficient dependent on exposure time between contacts for self-mated hydrogenated DLC films is essentially relevant to the amount of gas adsorbed on the surface, and then developed a model on the relationship between the transient friction behavior and surface coverage by using an Elovich adsorption model. However, the removal of the adsorbed films during mechanical sliding is not considered, leading to the model not matching experimental data.…”

Section: Introductionmentioning

confidence: 99%

Quantifying Macroscopic Friction of Diamond-like Carbon Films by Microscopic Adsorption and Removal of Water Molecules

Wang

Shang

et al. 2017

Langmuir

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The adsorption and desorption of water molecules, which affect the physical and chemical properties of the sliding interface, are critical for the friction behaviors of two solid contacts in atmosphere environment. The amount of water adsorbed on the open surface is a function of gas pressure according to an adsorption equation. However, for a confined sliding interface, the variation of surface fraction covered by gas molecules with water vapor pressure and its induced effects on friction have not been figured out. In this work, the macroscopic friction of diamond-like carbon (DLC) films in a water vapor atmosphere is quantified on the basis of microscopic adsorption and removal of water molecules. The studies correlate the fraction of water molecules adsorbed on the interface of self-mated DLC films with water vapor pressure to illustrate the direct relationship between friction coefficient and gas pressure by first-principles calculations and model fitting. The calculated results revealed that chemisorption and physisorption of water molecules occur on the surfaces of hydrogen-free DLC films (ta-C) and hydrogenated DLC films (HCF). Then, the relation between friction and gas pressure was built by employing a fractional coverage model based on the linear adsorption equation and gas removal. The obtained model agrees well with the typical experimental results about the steady-state friction coefficient of both highly hydrogenated DLC film (HCF) and tetrahedral amorphous carbon (ta-C) film during sliding at various water vapor pressures. In addition, it gave the curves of fractional surface coverage as a function of water vapor pressure. These results show that the frictional coefficient of DLC films could be predicted on the basis of fractional surface coverage as well as the intrinsic characters on surface chemistry. We suggest that the model may be thus extended to understand and predict the friction of DLC films under a specific gas pressure at a low load and speed.

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Friction of metal-matrix self-lubricating composites: Relationships among lubricant content, lubricating film coverage, and friction coefficient

Xiao

Zhang

et al. 2019

Friction

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Metal-matrix self-lubricating composites can exhibit excellent tribological properties owing to the release of solid lubricant from the matrix and the formation of a lubricating film on the tribosurface. The coverage of the lubricating film on a worn surface significantly influences the sliding process. However, it is difficult to quantify the film coverage owing to the thin and discontinuous character of the lubricating film and the high roughness of the worn surface. A quantitative characterization of the lubricating film coverage based on X-ray photoelectron spectroscopy (XPS) analysis was developed in this study. The friction tests of Cu-MoS 2 composites with a MoS 2 content of 0-40 vol% were conducted, and the worn surfaces of the composites were observed and analyzed. Further, the influence of the MoS 2 volume content on the coverage of the lubricating film on the worn surface was investigated. The relationships among the volume fraction of the lubricant, coverage of the lubricating film, and the friction coefficient were established. The friction model for the metal matrix self-lubricating composites was developed and verified to facilitate the composition design and friction coefficient prediction of self-lubricating composites.

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A fractional coverage model for gas–surface interaction in reciprocating sliding contacts

Cited by 10 publications

References 32 publications

Macroscopic Evidence of Thermally Activated Friction with Polytetrafluoroethylene

Macroscopic Evidence of Thermally Activated Friction with Polytetrafluoroethylene

Quantifying Macroscopic Friction of Diamond-like Carbon Films by Microscopic Adsorption and Removal of Water Molecules

Friction of metal-matrix self-lubricating composites: Relationships among lubricant content, lubricating film coverage, and friction coefficient

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