THE QUASI-HYDRODYNAMIC MECHANISM OF POWDER LUBRICATION .3. ON THEORY AND RHEOLOGY OF TRIBOPARTICULATES

The present work is the third part of a three-part investigation into the systematic development of the concept of powder lubrication as a viable tribological process. The quasi-hydrodynamic nature of powder lubrication is deduced from the observation that a number of basic features of powder flowing in narrow gaps exhibit the characteristics of fluid film lubrication. The concept of quasi-hydrodynamic lubrication of solid particulates forms the continuum basis for the phenomenological unification of solid particulates and liquid states of matter from the point of view of their mechanical (viscoelastic) properties. The first two parts of the investigation provided evidence of the quasi-hydrodynamic nature of powder lubricants. The current paper presents the theoretical development of the empirical quasi-rheological model to predict the behavior and performance of quasi-hydrodynamic films. The present theoretical model takes pressure-dependent powder properties into account, as well as variation of constants of the rheological model. Sample solutions are presented for a converging wedge, slider bearing lubricated with TiO2 powder.