Recent understanding of solid-liquid friction in ionic liquids

He, Yizhuo; Li, Han; Qu, Cangyu; Cao, Wu; Ma, Ming

doi:10.1016/j.gce.2020.10.006

Cited by 27 publications

(22 citation statements)

References 154 publications

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“…Ionic liquids (ILs) are salts with melting points below 100 °C. , ILs have attracted increasing research interests as lubricants and lubricant additives to reduce friction and wear for various solid surfaces due to physical properties including low vapor pressure, high chemical and thermal stability, and high thermal and electrical conductivity. − In addition, the distinct interfacial nanostructures of ILs make them superior lubricant candidates, especially in the boundary lubrication regime, in which the applied normal load is high and the bulk lubricant liquid has been squeezed out …”

Section: Introductionmentioning

confidence: 99%

Potential-Dependent Superlubricity of Ionic Liquids on a Graphite Surface

et al. 2021

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The lubricities of four quaternary phosphonium ionic liquidstrihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate ([P6,6,6,14][(iC8)2PO2]), trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate ([P6,6,6,14][BEHP]), trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide ([P6,6,6,14][TFSI]), and tributylmethylphosphonium bis(trifluoromenthylsulfonyl)imide ([P4,4,4,1][TFSI])were measured as a function of potential on highly oriented pyrolytic graphite (HOPG) by using atomic force microscopy (AFM). The shear strength and surface contact radius values fitted from JKR model indicate the AFM probe slides on an IL boundary layer rather than bare HOPG. Frictions change as the compositions of the boundary layers switch from cation enriched to anion enriched when the potential changes from negative to positive. Superlubricity, which refers to near zero increase in friction with load, is achieved for the [P6,6,6,14]+ cation at −1.0 V and the [TFSI]− anion at +1.0 V. The lubricities of ILs are mainly influenced by three factors: the alkyl chain length, chemical composition, and ion sizes.

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Section: Introductionmentioning

confidence: 99%

Potential-Dependent Superlubricity of Ionic Liquids on a Graphite Surface

et al. 2021

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“…Ionic liquids (ILs) as lubricant additives offer the opportunity to improve the performance due to its properties such as low volatility, flammability, high thermal stability, viscosity, corrosion inhibition, ashless, conductivity, customised molecular structure and tribological efficiency [4][5][6][7][8]. Recently, development of environmentally friendly lubricants including carboxylates and fatty acids have been used as neat or as an additives either in aqueous phase or mineral oil [9][10][11][12]. Avilés et al studied protic ILs such as bis (2-hydroxy ethyl) ammonium palmitate (DPA) for which ultra-low friction was found at high temperature [13].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Oil Miscible Novel Silane Functionalised Imidazoline-Based ILs as Lubricant Additives: Characterization and Tribological Evaluations

et al. 2022

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The present study investigated the synthesis of novel, oil miscible, multifunctional, silane functionalized imidazoline-based ionic liquids (ILs) with an emphasis towards halogen, sulfur and phosphorous free lubricant additives to replace the conventional additives (ZDDP, MoDTC, etc.), for which there are environmental concerns. These ILs were prepared in different concentrations and proved to be oil miscible for a short time. This stability was improved to over a year using sorbitan trioleate as an emulsifier additive. These additives performed well in reducing friction and wear when investigated on steel-steel contacts at a 5 wt% concentration, with improvements for the TPEIPS BEHP containing blend of up to 39% and 53%, respectively, as compared to the base oil. SEM and EDS analysis shows a phosphorous and oxygen rich tribo-film formation for this combinations. These ILs were further tested to determine their effect on properties such as viscosity, thermal stability, elastomeric and antifoaming compatibility. These new ILs work towards the discovery of environmentally friendly additives for tribological processes.

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“…Since the discovery of graphene, which is a honeycomb sheet of sp 2 -bonded carbon atoms, it has received great attention because of its excellent mechanical, thermal, and electric properties. − For both single-layer graphene (SLG) and few-layer graphene (FLG), a large portion of the carbon atoms are surface atoms, and thus the properties of graphene can be largely modified through the decoration of nanoparticles (NPs) on its surface. Significant research efforts have been devoted to the practical application of graphene with a functionally decorated surface.…”

Section: Introductionmentioning

confidence: 99%

Diffusion Induced Different Distributions of Sulfur Clusters on Suspended and Supported Graphene

Shi

et al. 2021

J. Phys. Chem. C

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The distribution of nanoparticles (NPs) on graphene is crucial for the performance of the graphene-based device. Such a distribution would be obviously influenced by the supporting substrates of graphene which are essential for the device. However, there are only a few relevant studies. In this paper, we report the distinct difference in the distributions of sulfur clusters at the submicrometer scale on the suspended graphene compared to a supported one. With vapor deposition of sulfur onto graphene with a patterned substrate, we find that the density of sulfur clusters on the supported regions is 3–8 times larger than that on the suspended ones. While the density decreases as the number of graphene layers increases for the supported regions, the opposite trend is observed within the suspended ones. The density also increases with the area of the suspended regions. The mechanism underlying these phenomena is attributed to the diffusion of small sulfur NPs which coalesce into larger sulfur clusters at the submicrometer scale on graphene, with faster diffusion on the suspended regions due to the more pronounced ripples in suspended graphene. Our results highlight the importance of the supporting substrates and provide guidelines for the fabrication of the graphene-based device.

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Recent understanding of solid-liquid friction in ionic liquids

Cited by 27 publications

References 154 publications

Potential-Dependent Superlubricity of Ionic Liquids on a Graphite Surface

Potential-Dependent Superlubricity of Ionic Liquids on a Graphite Surface

Synthesis of Oil Miscible Novel Silane Functionalised Imidazoline-Based ILs as Lubricant Additives: Characterization and Tribological Evaluations

Diffusion Induced Different Distributions of Sulfur Clusters on Suspended and Supported Graphene

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