Atomic simulation of contact behavior during sliding inception of an asperity

Advances in nanotribology prompt the understanding of lateral junction growth at the nanoscale an emerging issue. Our previous atomistic simulations have presented the atomic origins of the lateral junction growth mechanism at the nanoscale, which is mainly the slips of the atoms within the asperity. In the current study, we reveal that the lateral force increases with an increasing lateral displacement of the flat until the point at which junction growth ceases; corresponding to the maximum value of the tangential force coefficient. The transition of the lateral force profile from a smoothly increasing profile to a periodic sawtooth-like profile coincides with the point at which lateral junction growth ceases and stick-slip motion commences. However, the presence of an adsorbed layer on the nano-asperity surface suppresses the stick-slip motion and prompts a smooth sliding contact between the asperity and the flat.

► We simulate the flat-on-asperity contact of nanoasperity. ► The lateral force increases with an increasing lateral displacement of the flat. ► The transition of the lateral force profile coincides with the point at which lateral junction growth ceases and stick-slip motion commences. ► An adsorbed layer on the nano-asperity surface suppresses the stick-slip motion.