Nano-scale friction: A review

Frictional force is a resistant force that must be overcome to achieve relative motion between two components in contact. The economical and technological benefits of controlling friction and wear are tremendous. However, due to the complex nature of the phenomena, clear understanding of the mechanisms are yet to be achieved, particularly at the nano-scale where surface forces tend to dominate the tribological behavior of the system. In this paper the results of numerous theoretical, experimental, and numerical works on the fundamental mechanisms of friction at the nano-scale are reviewed. It is shown that friction coefficient values for nano-scale systems are quite varied depending on the conditions under which the system is investigated. As for the mechanism that causes friction at the nano-scale, interaction of the atoms plays a vital role. Furthermore, factors such as atomic radius, interatomic potential energy, and lattice parameters contribute to the degree of atomic interaction.