Formation of Ultrathin Film Between Two Molecularly Smooth Surfaces

Abstract

The forces between surfaces determine the properties of many biological systems. This makes them an important field of study. Measurements and numerical work of many researchers showed that in ultrathin lubricating films the net interaction between two surfaces separated by a polar lubricant involves both the electrostatic double layer force and the Van der Waals' force and at small separation solvation pressure is aided. In this work a numerical solution of the Reynolds' equation was developed using NewtonRaphson technique to obtain the film shape and pressure distribution caused by the hydrodynamic viscous action in addition to double layer electrostatic force, Van der Waals' inter-molecular forces and solvation pressure due to inter-surface forces. The numerical results showed that the effect of changing rolling speed and surface potential on the formation of ultrathin lubricating film thickness for polar lubricant confined
between two Mica surfaces. The numerical results showed that the film thickness increase by the increasing the rolling speed and surface potential. The increased value of the film thickness is due to the effect of double layer electrostatic force. At small separation the effect of solvation pressure dominates.