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).
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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