Thermal Resistance and Directional Index of Pressed Contacts between Smooth Non - Wavy Surfaces

More than 800 measurements of the thermal resistance for seven fully specified single contacts between non-wavy surfaces of both metals and non-metals in vacua (∼10−5torr) have been obtained and analysed. The effects of period of heating, vacuum pressure, thermal and load cycling, mean contact temperature and heat flux were also determined. Previous correlations obtained using data for rougher surfaces in contact were corroborated. For fully bedded-down contacts, i.e. the majority encountered in engineering practice, the deformation behaviour under load is elastic. Theories based on plastic deformation of the asperities are only applicable to the first loading of freshly assembled contacts.