The Division of Frictional Heat—A Guide to the Nature of Sliding Contact

The work of Jaeger [1] and Barber [2] indicates that the division of frictional heat between sliding solids should be sensitive to the interfacial boundary conditions. Thus it should provide a guide to the nature of asperity interactions and a more accurate statement of the boundary conditions for any subsequent analysis. Measurement of the division of heat in a symmetric “cylinder on cylinder” system was frustrated by the widespread occurrence of thermoelastic instability. An alternative specimen geometry has been developed which has permitted the division of heat between sliding solids of various materials to be investigated experimentally. The characteristics of the microscopic thermal resistance at the surface of a sliding solid have been investigated theoretically for several types of asperity interaction. An approximate method has been employed to estimate the thermal resistance of an oxidized surface. The observed division of heat is interpreted with reference to the characteristic behavior associated with the various types of asperity interaction. It is shown that in the mild wear regime oxide films have an appreciable effect on the microscopic thermal resistance and hence, on the thermal behavior of the sliding solids, particularly the division of heat between them.