The Influence of Thermal Expansion on the Friction and Wear Process

Experimental results are presented for temperatures of two metal surfaces in sliding contact. Considerable fluctuations are observed. It is suggested that temperature gradients, set up by irregular heating at the surface, cause local thermal expansion at the areas of contact, thus perpetuating the irregular contact conditions. The system is limited by the wear at the areas of contact which eventually reduces the level of the contact areas to that of the surrounding surface. Subsequent cooling causes contraction and produces depressions which correspond to the wear volume during the cycle. Further experiments to confirm this explanation show good agreement.