Thermal contact resistance modeling of non-flat, roughened surfaces with non-metallic coatings

Essentially all models for prediction of thermal contact conductance or the rmal contact resistance have assumed optically flat surfaces for simplifica tion. A few thermal constriction models have been developed which incorpora te uncoated optically non-flat surfaces based on the bulk mechanical proper ties of the material. Investigations have also been conducted which incorpo rate the thermophysical properties of metallic coatings and their effective surface microhardness to predict the overall thermal contact conductance. However, these studies and subsequent models have also assumed optically fl at surfaces; thus, the application of these models to optically non-flat, c oated surface conditions is not feasible without modifications. The present investigation develops a thermomechanical model that combines both microsc opic and macroscopic thermal resistances for non-flat roughened, surfaces w ith non-metallic coatings. The thermomechanical model developed as a result of this study predicts the thermal contact resistance of several non-metal lic coatings deposited on metallic aluminum substrates quite well.