Nanotribology: experimental facts and theoretical models

Nanotribology is a new physical discipline in which friction, adhesion, wear and lubrication are studied within a unified framework at the nanoscopic level. In this paper, the experimental and theoretical problems of topical interest in this field are reviewed. In the analysis of the experimental data, emphasis is placed on 'dry' adhesive friction between the probe of a scanning frictional microscope and an atomically smooth surface. On the theoretical side, studies related to the mechanisms of adhesive (static) and dynamic (velocity proportional) friction are discussed and results on the electromagnetic, electron, and phonon effects as well as molecular dynamics results are presented. Studies using the method of quartz crystalline microbalance and the 'surface force' concept are briefly reviewed.