Enhancement of thermal contact conductance: Effect of metallic coating

Thermal contact resistance exists in any joint due to the imperfections of the surfaces. Several methods may be employed to enhance the thermal performance of joints. One of these methods is to coat the surfaces in contact with a layer of suitable metal. The coating material may have a low hardness, which increases the total contact area of the joint, and higher thermal conductivity, which enhances the heat transfer in the contact region. The described experimental investigation examined four coating materials: tin, copper, aluminum, and silver. Two methods of coating were used: electroplating and filtered are vapor deposition, It was confirmed that all four coating materials enhanced thermal contact conductance. However, the optimum coating thickness varied with the coating material used. It was the hardness of the coating material that determined the optimum coating thickness. The higher the hardness of coating material, the thicker the coating needs to be for better performance, It was also found that the methods of coating affected the enhancement factor.