Interfacial contact resistance of single-crystal ceramics for solar concentrators

An experimental investigation was conducted to determine the thermal conductivity and overall thermal resistance of stacks of single-crystal alumina and magnesia, and zirconia. From these data, the interfacial thermal resistance between the ceramic materials was evaluated over a range of pressures of 70-1720 kPa, and at two temperatures of 20 and 60 degrees C. For all three materials, the interfacial thermal resistance decreases significantly with an increase in pressure at lower pressures, beyond which it decreases more gradually. Further, the effect of temperature on the interfacial thermal resistance is negligible for the temperature range investigated. These data were used to develop an equation relating the dimensionless interfacial thermal resistance to the crystal material properties, surface characteristics, crystal thickness, apparent interface pressure, and mean interface temperature.