Characteristics of liquid lubricant films at the nano-scale

Characteristics of a liquid lubricant film at the nanometer scale nra discu ssed in the present paper The variations of the film thickness in a central contact region between a glass disk and a super-polished steel ball with l ubricant viscosity, rolling speed, substrate surface tension, running time, load, etc. have been investigated. Experimental results show that the vari ation of film thickness in the thin film lubrication (TFL) regime is largel y different from that in the elastohydrodynamic lubrication (EHL) regime. T he critical transition point from EHL to TFL is closely related to lubrican t viscosity, surface energy of substrates, and so on. The film in TFL is mu ch thicker than that calculated from the Hamrock-Dowson formula. An unusual behavior of the lubricant film has also been observed when the effect of t he running time on the film thickness is considered. The time effect and th e formation mechanism of the enhanced film in the running process have been discussed.