Nano-Tribological Analysis by Molecular Dynamics Simulation—A Review

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The advent of super computers for large scale atomic simulations and the invention of proximal testing devices such as atomic force microscope, friction force microscope, surface force apparatus, nanoScratcher etc., have led to the development of micro- and nano-tribology. This paper reviews some fundamental concepts and steps involved in molecular dynamics modeling of nanotribology together with some significant aspects such as the mechanisms of wear and friction, the scale effect of asperity contact size on friction, and the deformation induced by two-body and three-body contact sliding on the atomic scale with a focus on the authors' work on copper and silicon. Studies on diamond-copper sliding reveal that there exist four distinct regimes of deformation, and that no-wear deformation can be achieved by using a lower sliding speed, a smaller tip radius and a better lubrication. The variation of the frictional force is a function of contact area in all regimes except that in the cutting regime where the conventional friction law still holds. Investigations into the diamond-silicon sliding show that the amorphous phase transformation is the main deformation in silicon. In a two-body contact sliding, the deformation of silicon falls into no-wear, adhering, ploughing, and cutting regimes while in a three-body sliding it falls into no-wear, condensing, adhering, ploughing and no-damage wear regimes.