• Ratoi, Monica
• Spikes, Hugh A.

Abstract

A number of recently-developed experimental techniques, such as force balance, atomic force microscopy and ultrathin film interferometry have enabled the direct study of the properties of very thin liquid lubricating films between solid surfaces. These have been used to demonstrate the structure and rheology, and thus the lubricating ability, of monolayer additive films in rolling and sliding contacts. They have also been used to investigate the thin film properties of simple, additive-free fluids such as hydrocarbon base stocks.<br/><br/>This paper reviews previous work on the thin film-forming properties of simple lubricant base fluids. Newwork is carried out using ultrathin film interferometry and a rolling-sliding friction test apparatus. It is found that the quasi-spherical molecules, cyclohexane and OMCTS form enhanced film thicknesses in high pressure, slow speed, rolling contacts. There is also an indication of a step-wise dependence of film thickness on rolling speed, in accord with finding using atomic force microscopy and surface forces apparatus. Friction measurements in mixed rolling-sliding show that these fluids also reduce friction in the boundary film regime.

Topics

• impedance spectroscopy
• surface
• thin film
• atomic force microscopy
• forming
• interferometry