Influences of the Liquid/solid Wettability on Thin Hydrodynamic Lubrication Films

This paper describes some experimental studies about the influences of liquid/solid wettability on thin hydrodynamic lubrication film thickness by a custom-made test apparatus. In the experiments, the lubricated contact consisted of a micro-slider plane and a transparent glass disc. The liquid/solid wettability can be differentiated by the contact angle of the lubricant to the lubricated surfaces, and different slider materials and lubricants can generate interfaces of different wettability. Under a fixed load and a constant slider inclination angle, the film thickness at different entrainment speeds was measured. The results showed that for strong liquid-solid wettability the measured film thickness versus speeds was well correlated to the classical lubrication theory. And when the interface of weak wettability is used, significant film thickness variation can be found. By wall-slippage, the experimental finds were tentatively explained.