Experimental study of boundary layers formation by thin film colorimetric interferometry

Thin film colorimetric interferometry was applied to the preliminary study of boundary layers formation for a several liquids of known molecular struc ture that have been previously studied by the force balance method. This te chnique intended for the study of very thin lubrication films down to a few nanometers in a point contact between a steel ball and a transparent disk combines powerful film thickness mapping capabilities with high accuracy. C entral and minimum film thickness as well as film shape in the dependence o n rolling speed was studied for hexadecane, oc-tamethylcyclotetrasiloxane ( OMCTS) and n-tetradecane. Results are compared with data obtained from surf ace force apparatus measurements. OMCTS and n-tetradecane were found to for m boundary films that result in a considerable enhancement in film thicknes s at slow speeds.