Friction wearless

The studies on friction originated from sliding-induced instability of interfacial atoms and consequent energy dissipation are reviewed in this section, including the author s work to extend the models of wearless friction. This type of friction has been addressed in the literature by different... 

From the discussions on dynamic adhesion and wearless friction, one may realize that the two events originate from... 

Equation (27) provides important information on the nature of wearless friction, which deserves a further discussion. 

The wearless friction consists of two components, namely the adhesion term Cj and the pressure term CiP xt-Similar expressions for the shear stress, e.g., Tc=TQ + iJiP, were also derived by other investigators [26,27], where tq represents the contribution from adhesion and yu, is referred to as the friction coefficient. 

If the surfaces are damaged during sliding so that wear debris and multi-asperity contacts are involved in the process, the mechanism of friction will be substantially different from what we discussed for wearless friction. 

Weiss, M. and Elmer, F. J., "A Simple Model for Wearless Friction The Frenkel-Kontorova-Tomlinson Model, Physics of Friction, B. N. J. Persson and E. Tosatti, Eds., Kluwer Academic Publishers, 1996,pp. 163-178. 

The availability of new experimental methods at the end of the 1980 s allowed us to study friction on the atomic scale and created the new field of nanotribology. The observed wearless friction on this scale can be understood using the model of Tomlinson where the plucking action of one atom on to the other leads to energy dissipation via the generation of phonons. 

The power law found in their simulations for the interaction of an amorphous tip with a crystalline substrate is similar to that observed in AFM experiments in argon atmosphere [75,76]. Also AFM studies of friction on layered materials [77] showed striking similarity with Fig. 6 in the wearless regime, although the experiments were conducted in atmosphere. In the latter case, there is even an order of magnitude agreement between the experimentally measured friction and simulated friction. The prefactors observed in another set of experiments [75,76] are, however, distinctly larger than those in the simulations. Moreover, the experimental results by Schwarz et al. [76] obtained with tips of different radii of curvature seem consistent with a picture in which the friction force is proportional to the area of contact and independent of the normal pressure. It thus remains an open question what friction mechanism is predominant in these experiments. 

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