Issue 51, 2014

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

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

Supplementary files

Article information

Article type
Paper
Submitted
25 Apr 2014
Accepted
10 Jun 2014
First published
10 Jun 2014

RSC Adv., 2014,4, 26721-26728

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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