Subsequent work demonstrated that friction between smooth metal surfaces principally arises from adhesive force fields acting within the junctions of the contacting asperities. Rabinowicz characterizes the force fields as atom-to-atom in strength and sphere of influence. They can be very strong, but are significant only over a short distance. Bowden and Tabor found that this adhesion depends on three principal factors: the real area of solid contact discussed above (Ar), the bulk material properties of the metals involved, and the nature of any contaminants present. The findings of Bowden and Tabor [3,4] and Rabinowicz led to the acceptance of this model by most workers in the field where it comprises the traditional adhesion theory of metallic friction.
The work done, or reported, by Bowden and Tabor [3,4] was carried out in the 1940s and 1950s. In 1995, Rabinowicz reviewed additional adhesion research conducted at that time. He opined that both the empirical and rational bases for the theory had been strengthened. Such adhesion is considered by Rabinowicz to be a direct form of cold welding effectuated by the surface energy forces inherent in the metals in contact.
