Ultralow Friction Between Steel Surfaces Achieved by Lubricating with Liquid Crystal After a Running-in Process with Acetylacetone

Chen, Hui; Xu, Chonghai; Xiao, Guangchun; Chen, Zhaoqiang; Yi, Mingdong

doi:10.1007/s11249-018-1020-3

Cited by 18 publications

(8 citation statements)

References 42 publications

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“…Various pressures (P = 26, 260, and 1000 MPa) and velocities (v = 1, 10, and 100 m s −1 ) were applied to the outermost layer of the upper iron wall in order to study the influence of these parameters on 5CB LC. A pressure of 26 MPa is consistent with the pressure in our previous friction experiment, [23] and the pressures of 260 and 1000 MPa are within the common pressure range reported for shearing MD simulations of liquids. [24,25] To obtain a high signal-to-noise ratio and reach a steady state, a high shear rate is needed in shearing MD simulations, [24] and hence the applied velocities are higher than those in the friction experiment.…”

Section: Model and Simulationsupporting

confidence: 88%

Molecular Dynamics Simulations on the Flow Behavior of 5CB Liquid Crystal Sandwiched Between Iron Walls

Chen

Sun

Xiao

et al. 2022

Advcd Theory and Sims

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The 4-n-pentyl-4′-cyano biphenyl (5CB) liquid crystal (LC) sandwiched and sheared between atomically flat and grooved iron walls, respectively, is simulated using molecular dynamics, and the flow behavior of the system under confinement, pressure, and shear is investigated. The order parameter P 2 , velocity, and density of 5CB are profiled as a function of distance from the walls using a block analysis method. The flow-alignment phenomenon is reproduced, and alignment angles ranging from 11.3°to 13.9°are observed. The competition between the elastic effect of the surface and viscous effect of the flow on the orientation of the 5CB molecules is investigated. The P 2 of 5CB located in the vicinity of the grooved walls is higher than that of the flat walls, while this difference is negligible in the case of 5CB distanced from the walls. Instead of boundary slip or Couette flow, the velocity profiles reveal a boundary condition (BC) of central localization, which is very different from the assumed Couette flow BC in most analytical models of LC flow. This work enhances the current molecular-scale understanding of the flow behavior of confined liquid crystals and provides additional insights into the phenomenon.

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Section: Model and Simulationsupporting

confidence: 88%

Molecular Dynamics Simulations on the Flow Behavior of 5CB Liquid Crystal Sandwiched Between Iron Walls

Chen

Sun

Xiao

et al. 2022

Advcd Theory and Sims

Self Cite

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“…As an essential material for mechanical operation, lubricants play a significant role in maintaining the machines running well and improving the life of the machines . With the rapid development of modern industry, it is necessary to develop high-performance tribological materials to meet the ever-increasing demands, such as ultralow friction, higher thermal stability, better high-temperature performance, − and so on.…”

Section: Introductionmentioning

confidence: 99%

Tribological Properties of Cholesteric Fluorinated Liquid Crystal as Lubricant Additives in PAO4 under Elevated Temperatures

Zhang

Jiang

Gao

et al. 2021

Ind. Eng. Chem. Res.

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A series of fluorinated liquid crystal compounds with perfluoroalkyl chains are reported and their properties as lubrication additives are discussed. The structures were characterized by Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR), and mass spectrum (MS). The liquid crystalline properties were examined by differential scanning calorimetry (DSC) and polarized optical microscopy (POM), the tribological properties were tested by a universal mechanical tester (UMT), a friction tester, and a 3D optical microscope, and the worn surfaces were analyzed by scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). The results showed that PAO4 with fluorinated liquid crystals (LCs) led to a significant reduction in friction coefficient (30%) and wear (twice over). And the tribological performance was closely related to mesogenic temperature ranges of liquid crystals. The analysis of EDS and XPS indicated that a protective film can be formed of ferric oxide and ferric fluoride. It can be hypothesized that the tribofilm could avoid the direct contact of the rough material on the metal surface on the metal surface, thus reducing friction and wear.

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“…Although this 1,3-diketone has attracted more and more research interest [32][33] and shows excellent lubricity especially for applications with relatively low contact pressure (e.g. plain bearings [27] ), other aspects of a lubricant such as anti-oxidation, oil detergency, low temperature fluidity and extreme pressure capacity must be also taken into account.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of 1,3-diketone as a novel friction modifier for lubricating oils

Jiang

Amann

et al. 2020

Wear

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Ultralow Friction Between Steel Surfaces Achieved by Lubricating with Liquid Crystal After a Running-in Process with Acetylacetone

Cited by 18 publications

References 42 publications

Molecular Dynamics Simulations on the Flow Behavior of 5CB Liquid Crystal Sandwiched Between Iron Walls

Molecular Dynamics Simulations on the Flow Behavior of 5CB Liquid Crystal Sandwiched Between Iron Walls

Tribological Properties of Cholesteric Fluorinated Liquid Crystal as Lubricant Additives in PAO4 under Elevated Temperatures

Evaluation of 1,3-diketone as a novel friction modifier for lubricating oils

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