Temperature and velocity dependent friction of a microscale graphite-DLC heterostructure

Gongyang, Yujie; Ouyang, Wengen; Qu, Cangyu; Urbakh, Michael; Quan, Baogang; Ma, Ming; Zheng, Quanshui

doi:10.1007/s40544-019-0288-0

Cited by 32 publications

(23 citation statements)

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“…Graphene is an excellent lubricating coating layer because of its extremely high intrinsic strength, ultralow binding strength with many surfaces, e.g., graphite, hexagonal boron nitride (hBN), MoS 2, and atomically smooth surface . For example, the friction between graphene/graphene, graphene/MoS 2 , graphene/hBN, and graphene/diamond‐like‐carbon (DLC) measured at either nanoscale or microscale could be so small that such layered‐material junctions could reach superlubricity, a state in which the lateral interactions between two incommensurate surfaces are effectively canceled resulting in ultralow sliding friction. The ultralow friction state could also be achieved for tip with radius from 20 to 1000 nm sliding on graphene supported by substrates, e.g., diamond tip with graphene on SiO 2 substrate, Si tip with graphene on SiO 2 substrate, and diamond tip with graphene on Cu substrate and the lubrication properties was robust under different normal load …”

Section: Introductionmentioning

confidence: 99%

The Impacts of Adhesion on the Wear Property of Graphene

Zhao

Zhang

et al. 2019

Adv Materials Inter

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a state in which the lateral interactions between two incommensurate surfaces are effectively canceled resulting in ultralow sliding friction. The ultralow friction state could also be achieved for tip with radius from 20 to 1000 nm sliding on graphene supported by substrates, e.g., diamond tip with graphene on SiO 2 substrate, [11,12] Si tip with graphene on SiO 2 substrate, [13] and diamond tip with graphene on Cu substrate [14] and the lubrication properties was robust under different normal load. [15] The ultralow friction and high intrinsic strength make graphene an ideal candidate for antiwear coating materials. On the nano and microlevel, Shin et al. [11] carried out microscale scratch tests on exfoliated and epitaxial graphene on a silica substrate. When the indenter was pressed into the monolayer graphene sample at a depth of more than 150 times of its thickness, no damage occurred within the graphene. Using atomic force microscope (AFM) tip with a radius about 100 nm sliding on graphene that mechanically exfoliated to SiO 2 substrates, Qi et al. [12] reported that the monolayer graphene still maintained a low friction coefficient of 0.01 for a prolonged period (4096 cycles) with a normal load up to 9150 nN, and the interior region of graphene shows better wear resistance. Qi et al. [16] further found that the wear resistance of the free edge of graphene could be improved by performing air plasma treatment. With a similar setup, Vasic et al. [17] showed that the SiO 2 substrate gets plastically deformed for lower normal loads, followed by a sudden Adhesion plays an important role in the antiwear property of graphene layer on a substrate. Here the wear property of the inner region of monolayer graphene grown on copper foils via chemical vapor deposition is studied. The adhesive strength is controlled by changing the oxidation of the copper substrate into two oxidation degrees with intact graphene preserved. For graphene layers on copper substrates with either low oxidation degree (LOD) or high oxidation degree (HOD), it is found in both systems wear starts at the wrinkle position under similar normal force. However, with the development of wear, for the LOD substrate the covering graphene layer is worn out gradually, while for the HOD substrate the graphene layer is peeled off rapidly. By measuring the adhesion between graphene and substrates indirectly, together with finite element analysis, it is shown that the underlying mechanism for the different wear phenomena is due to the higher adhesion between graphene and LOD substrates than that between graphene and HOD substrates. This study provides insights on the impacts of adhesion between monolayer material and substrates on the antiwear properties, which can benefit the design of lubrication coatings based on layered materials. Wear

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Section: Introductionmentioning

confidence: 99%

The Impacts of Adhesion on the Wear Property of Graphene

Zhao

Zhang

et al. 2019

Adv Materials Inter

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“…3B, Movie S2 and S3). The velocity profiles generated for the bacteria under RMF exhibited the well-studied characteristics of surface walkers under low Reynolds number flows (59)(60)(61). The higher mass density of MTB with respect to the surrounding liquid gives rise to a terminal velocity of the bacteria which results in an offset in the y component.…”

Section: Elucidating the Role Of Torque-driven Motion On Translocation Using Computational Modellingmentioning

confidence: 80%

Magnetic torque-driven living microrobots for enhanced tumor infiltration

Gwisai

Mirkhani

Christiansen

et al. 2022

Preprint

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Bacterial microrobots combining self-propulsion and magnetic guidance are increasingly recognized as promising drug delivery vehicles for targeted cancer therapy. Thus far, control strategies have either relied on poorly scalable magnetic field gradients or employed directing magnetic fields with propulsive forces limited by the bacterial motor. Here, we present a magnetic torque-driven actuation scheme based on rotating magnetic fields to wirelessly control Magnetospirillum magneticum AMB-1 bearing versatile liposomal cargo. We observed a 4-fold increase in conjugate translocation across a model of the vascular endothelium and found that the primary mechanism driving this increased transport is torque-driven surface exploration at the cell interface. Using spheroids as a 3D tumor model, fluorescently labeled bacteria colonized their core regions with up to 21-fold higher signal in samples exposed to rotating magnetic fields. In addition to enhanced transport, we demonstrated the suitability of this magnetic stimulus for simultaneous actuation and inductive detection of AMB-1. Finally, we demonstrated that RMF significantly enhances AMB-1 tumor accumulation in vivo following systemic intravenous administration in mice. Our findings suggest that scalable magnetic torque-driven control strategies can be leveraged advantageously with biohybrid microrobots.

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“…As a rule of thumb for experimentalists, in Table 1, we list the critical radius, r c , for some typical friction pairs with confined liquid at the interface [35]. A potential experimental system could be graphene layers deposited by exfoliation onto a smooth surface (e.g., a Si/SiO 2 surface), which represent a large category of experimental systems [26,36,37]. For such systems, it has been shown experimentally that the few-layer graphene is partly freely suspended between hills of the substrate [26].…”

Section: Resultsmentioning

confidence: 99%

Oscillating friction of nanoscale capillary bridge

Zheng

et al. 2021

Friction

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The presence of a capillary bridge between solid surfaces is ubiquitous under ambient conditions. Usually, it leads to a continuous decrease of friction as a function of bridge height. Here, using molecular dynamics we show that for a capillary bridge with a small radius confined between two hydrophilic elastic solid surfaces, the friction oscillates greatly when decreasing the bridge height. The underlying mechanism is revealed to be a periodic ordered-disordered transition at the liquid–solid interfaces. This transition is caused by the balance between the surface tension of the liquid–vapor interface and the elasticity of the surface. This balance introduces a critical size below which the friction oscillates. Based on the mechanism revealed, a parameter-free analytical model for the oscillating friction was derived and found to be in excellent agreement with the simulation results. Our results describe an interesting frictional phenomenon at the nanoscale, which is most prominent for layered materials.

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Temperature and velocity dependent friction of a microscale graphite-DLC heterostructure

Cited by 32 publications

References 50 publications

The Impacts of Adhesion on the Wear Property of Graphene

The Impacts of Adhesion on the Wear Property of Graphene

Magnetic torque-driven living microrobots for enhanced tumor infiltration

Oscillating friction of nanoscale capillary bridge

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