Interfacial contact resistance of single-crystal ceramics for solar concentrators

An experimental investigation was conducted to determine the thermal conduc tivity and overall thermal resistance of stacks of single-crystal alumina a nd magnesia, and zirconia. From these data, the interfacial thermal resista nce between the ceramic materials was evaluated over a range of pressures o f 70-1720 kPa, and at two temperatures of 20 and 60 degrees C. For all thre e materials, the interfacial thermal resistance decreases significantly wit h an increase in pressure at lower pressures, beyond which it decreases mor e 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 th ermal resistance to the crystal material properties, surface characteristic s, crystal thickness, apparent interface pressure, and mean interface tempe rature.