The frictional behaviour of materials

A review of friction is made and a general equation of friction, based on dimensional analysis, is presented. The equation takes into account the environment, material properties, surface roughness, the area of real contact, rubbing velocity, deformation and surface energy, and suggests friction to be system dependent. By imposing certain conditions, it was shown that the equation satisfies equations based on the adhesion and agrees with deformation and surface energy theories. A model of friction is presented which suggests that the friction force results from adhesion, plowing and interlocking of asperities, the magnitude of which is governed by surface energy and the nature and magnitude of surface deformation. The experimental results presented suggest the dependence of friction on load and velocity to be heavily influenced by the oxidation characteristics of the materials in rubbing contact.