A Transient Hot-Wire Instrument for the Measurement of the Thermal Conductivity of Solids up to 590 K

A novel application of the transient hot-wire technique for measurements of the thermal conductivity of solids up to 590 K is described. The method makes use of a soft silicone material between the hot wires and the solid of interest. Measurement of the transient temperature rise of the wires in response to electrical step heating over a period of 20 s to 20 s allows an absolute determination of the thermal conductivity of the solid, as well as of the silicone paste. The method is based on a full theoretical model with equations solved by a finite-element method applied to the exact geometry. Two sets of thermal-conductivity measurements up to 590 K, employing different silicone pastes and samples of Pyroceram 9606, are reported. At the 95% confidence level, the standard deviation of the thermal conductivity measurements is less than 1.5%.