This paper uses three lubrication models to explore the differential phenomenon in the status of thin film lubrication (TFL). According to the viscous adsorption theory, the modified Reynolds equation for thin film elastohydrodynamic lubrication (TFEHL) is derived. In this theory, the film thickness between lubricated surfaces is simplified as three fixed layers across the film, and the viscosity and density of the lubricant vary with pressure in each layer. Under certain conditions, such as a rough or concentrated contact of a nominally flat surface, films may be of nanometer scale. The thin film elastohydrodynamic lubrication (EHL) analysis is performed on a surface forces (SF) model which includes van der waals and solvation forces. The results show that the proposed TFEHL model can reasonably calculate the film thickness and the average relative viscosity under thin film EHL. The adsorption layer thickness and the viscosity influence significantly the lubrication characteristics of the contact conjunction. The differences in pressure distribution and film shape between surface forces model and classical EHL model were obvious, especially in the Hertzian contact area. The solvation force has the greatest influence on pressure distribution.

Advances in our fundamental understanding of and control over interparticle colloidal forces have enhanced our ability to formulate stable, complex fluids with colloidal and/or nano-sized particles with specific rheological properties. This understanding stems from advances in experimental methods that probe these forces, either directly or indirectly, as well as theoretical treatments and simulation methods linking macroscopic suspension properties to the dynamics and interactions between colloidal particles. This article highlights recent experimental developments in the structure—property relationships for colloidal dispersions, with emphasis on the sensitivity of colloid rheology to nanometer-scale interactions. Examples of applications are used to illustrate these relationships.