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Issue 51, 2014
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Effects of surface compliance and relaxation on the frictional properties of lamellar materials

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Abstract

We describe the results of atomic-level stick–slip friction measurements performed on chemically-modified graphite, using atomic force microscopy (AFM). Through detailed molecular dynamics simulations, coarse-grained simulations, and theoretical arguments, we report on complex indentation profiles during AFM scans involving local reversible exfoliation of the top layer of graphene from the underlying graphite sample and its effect on the measured friction force during retraction of the scanning tip. In particular, we report nearly constant lateral stick–slip magnitudes at decreasing loads, which cannot be explained within the standard framework based on continuum mechanics models for the contact area. We explain this anomalous behavior by introducing the effect of local compliance of the topmost graphene layer, which varies when interaction with the AFM tip is enhanced. Such behavior is not observed for non-lamellar materials. We extend our discussion toward the more general understanding of the effects of the top layer relaxation on the friction force under positive and negative loads. Our results may provide a more comprehensive understanding of the effectively negative coefficient of friction recently observed on chemically-modified graphite.

Graphical abstract: Effects of surface compliance and relaxation on the frictional properties of lamellar materials

  • This article is part of the themed collection: Tribology
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Publication details

The article was received on 25 Apr 2014, accepted on 10 Jun 2014 and first published on 10 Jun 2014


Article type: Paper
DOI: 10.1039/C4RA03810J
Citation: RSC Adv., 2014,4, 26721-26728
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    Effects of surface compliance and relaxation on the frictional properties of lamellar materials

    A. Smolyanitsky, S. Zhu, Z. Deng, T. Li and R. J. Cannara, RSC Adv., 2014, 4, 26721
    DOI: 10.1039/C4RA03810J

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