On the thermal compatibility of metallic pairs in rubbing applications

This paper presents a theoretical model for the prediction of the variation in heat removal during the dry sliding of metallic surfaces with the inclusion of variable thermal properties, it is shown that the temperature-induced change in the so-called 'coefficient of heat penetration' is influential in the nature of heat dissipation at the interface. This change, termed the 'matching function', is utilised to propose a possible criterion for the choice of 'thermally compatible' materials for rubbing applications. For the optimisation of thermal conditions, this criterion requires the selection of the rubbing pair, so as to maintain. in order of preference, a positive, zero, or slightly negative matching function. A preliminary study of mild steel rubbing against the same material, and against stainless steel. is presented to illustrate the relative effects of both conductivity and the matching function. It is shown that the latter provides an indication of the nature of heat removal during contact. It is proposed that this criterion may be extended to the choice of thermally efficient tribological coatings to enhance the transfer of frictional heat away from the interface. This is directly related to the design of frictional tribe-systems such as brakes and bearings. (C) Elsevier, Paris.