Effects of Stone-Wales and vacancy defects in atomic-scale friction on defective graphite

XY Sun and RN Wu and R Xia and XH Chu and YJ Xu, APPLIED PHYSICS LETTERS, 104, 183109 (2014).

DOI: 10.1063/1.4876055

Graphite is an excellent solid lubricant for surface coating, but its performance is significantly weakened by the vacancy or Stone-Wales (SW) defect. This study uses molecular dynamics simulations to explore the frictional behavior of a diamond tip sliding over a graphite which contains a single defect or stacked defects. Our results suggest that the friction on defective graphite shows a strong dependence on defect location and type. The 5-7-7-5 structure of SW defect results in an effectively negative slope of friction. For defective graphite containing a defect in the surface, adding a single vacancy in the interior layer will decrease the friction coefficients, while setting a SW defect in the interior layer may increase the friction coefficients. Our obtained results may provide useful information for understanding the atomic-scale friction properties of defective graphite. (C) 2014 AIP Publishing LLC.

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