Influence of the Real Geometry of the Protrusions in Micro Textured Surfaces on Frictional Behaviour

Recent studies in tribology aim at the development of techniques to improve the microscopic geometry of the functional surface because of their ability to optimize the frictional behaviour. A deterministic surface microtexturing is a possibility to influence the lubrication regime, thus, adjusting friction coefficient and wear. In this study a model based on the equations of hydrodynamic lubrication of a linear wedge bearing was developed to explain the friction behaviour of oil lubricated, textured steel/sapphire pairs sliding unidirectionally with velocities up to 10 m/s. The model explained why, comparing textures with different channel widths, increasing lubrication films caused decreasing coefficient of friction although the model equations were derived from hydrodynamic theory. With the microscopic geometry as the reason for the unusual behaviour a further understanding of the mechanisms of crossed microchannels was gained.