Shearing Nanometer-Thick Confined Hydrocarbon Films: Friction and Adhesion

Sivebæk, Ion Marius; Persson, B. N. J.

doi:10.1007/s11249-016-0656-0

Cited by 6 publications

(5 citation statements)

References 30 publications

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“…Figure 11 shows that σ 0 increases approximately linearly with logarithmic shear rate for all of the n-alkanes studied, in agreement with previous simulations of atomic fluids at high shear rate [72]. In Figure 11, σ 0 is larger for longer n-alkanes, as observed in previous NEMD simulations of n-alkanes (C 20 -C 100 ) [73]. For short n-alkanes at low shear rate, a negative σ 0 is extrapolated from Figure 8, which was also noted from previous NEMD simulations of atomic fluids [72] and C 16 [67].…”

Section: Accepted Manuscriptsupporting

confidence: 89%

“…Unlike branched alkane films [19], most of the n-alkanes show a finite σ 0 in Figure 11, suggesting some adhesion at the solid-liquid interface [68]. Non-zero values of σ 0 have also been obtained from previous NEMD simulations and experiments of a range of confined fluids [72,67,68,73,24]. Figure 11 shows that σ 0 increases approximately linearly with logarithmic shear rate for all of the n-alkanes studied, in agreement with previous simulations of atomic fluids at high shear rate [72].…”

Section: Accepted Manuscriptsupporting

confidence: 61%

See 1 more Smart Citation

Behaviour of n-alkanes confined between iron oxide surfaces at high pressure and shear rate: A nonequilibrium molecular dynamics study

Restrepo

Eijk

Ewen

2019

Tribology International

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The behaviour of n-alkanes confined and sheared between iron oxide surfaces has been studied using nonequilibrium molecular dynamics simulations. The molecular extension, orientation, film structure, flow, and friction have been investigated for a range of n-alkanes chain lengths under conditions representative of the elastohydrodynamic lubrication regime. At high pressure, the molecules show strong layering and long-range order, suggesting solid-like films. Conversely, high shear rates result in less elongated, layered, and ordered molecules; indicating more liquid-like films. Although Couette flow is usually observed for short n-alkanes, the flow is often non-linear for long n-alkanes. The friction coefficient increases logarithmically with shear rate, but the slope decreases with increasing pressure such that it becomes insensitive to shear rate for long n-alkanes.

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Section: Accepted Manuscriptsupporting

confidence: 89%

Section: Accepted Manuscriptsupporting

confidence: 61%

Behaviour of n-alkanes confined between iron oxide surfaces at high pressure and shear rate: A nonequilibrium molecular dynamics study

Restrepo

Eijk

Ewen

2019

Tribology International

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“…We note that this study, and that in [2], involve fluid squeeze-out between a curved surface and a nominally flat surface. This differs from our earlier (frictional) studies involving flat surfaces [3][4][5][6].…”

Section: Introductioncontrasting

confidence: 99%

The effect of surface nano-corrugation on the squeeze-out of molecular thin hydrocarbon films between curved surfaces with long range elasticity

Sivebæk

Persson

2016

Nanotechnology

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Document VersionThe effect of surface nano-corrugation on the squeeze-out of molecular thin hydrocarbon films between curved surfaces with long range elasticity. The properties of linear alkane lubricants confined between two approaching solids are investigated by a model that accounts for the roughness, curvature and elastic properties of the solid surfaces. We consider linear alkanes of different chain lengths from C3H8 to C16H34, confined between corrugated solid walls. The pressure necessary to squeeze out the lubricant increases rapidly with the alkane chain length, but is always much lower than in the case of smooth surfaces. The longest alkanes form domains of ordered chains and the squeeze-out appear to nucleate in the more disordered regions between these domains. The short alkanes stay fluid-like during the entire squeeze out process which result in a very small squeeze-out pressure which is almost constant during the squeeze-out of the last monolayer of the fluid. In all cases we observe lubricant trapped in the valley of the surface roughness, which cannot be removed independent of the magnitude of the squeezing pressures.

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“…In particular, this type of systems have been extensively studied through SFA experiments by Israelachvilli, who, among other things, found that friction at the nano-scale could be correlated with the adhesion hysteresis phenomenon [6]. Furthermore, in order to achieve a fundamental understanding of these processes, efforts have and are still been made from both experimental [7][8][9][10][11][12][13][14][15] as well as theoretical and simulations points of view, such as through Molecular Dynamic Simulations (MDS) [16][17][18][19][20][21][22][23][24][25][26][27][28]. However, a satisfactory explanation of the friction mechanisms involved in this type of systems is still lacking, for example, with respect to the origin of phase transitions evidenced by the SS behavior and the effects of the adhesion hysteresis phenomenon.…”

Section: Introductionmentioning

confidence: 99%