Heat transfer at the interface of dissimilar materials: Evidence of thermal-comparator experiments

Abstract

A recent publication has drawn attention to a marked directional dependence of the heat flow at the interface of certain contacting metals, and considers the effect to be associated with the mechanism of conduction at the points of metallic contact. The effect is now investigated in terms of the reading of a thermal comparator having initial temperatures both above and below that of the test sample. No such directional difference is found in this way for the metal combinations for which the effect had previously been reported, namely steel and aluminium, and steel and aluminium alloy, nor is any difference found for the combinations of a metal (steel) with either a semiconductor (germanium) or an electrical insulator (a ceramic material based on soapstone), for which it is to be expected that differences in the heat conduction mechanism would be more pronounced. It is concluded that the use of the thermal comparator for thermal conductivity determinations is not complicated by any such directional effect.