Thermal Contact Resistance Modeling of Non-Flat, Roughened Surfaces With Non-Metallic Coatings

Essentially all models for prediction of thermal contact conductance or thermal contact resistance have assumed optically flat surfaces for simplification. A few thermal constriction models have been developed which incorporate uncoated, optically non-flat surfaces based on the bulk mechanical properties of the material. Investigations have also been conducted which incorporate 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 flat surfaces; thus, the application of these models to optically non-flat, coated surface conditions is not feasible without modifications. The present investigation develops a thermomechanical model that combines both microscopic and macroscopic thermal resistances for non-flat, roughened, surfaces with non-metallic coatings. The thermomechanical model developed as a result of this study predicts the thermal contact resistance of several non-metallic coatings deposited on metallic aluminum substrates quite well.