Apparent thermal conductivity is measured by plate steady state method according to ASTM E 1225. A test specimen is inserted under load between two similar specimens of a material of known thermal properties. A temperature gradient is established in the test stack and heat losses minimized using a longitudinal guard having approximately the same temperature gradient conditions.
At equilibrium conditions, the thermal conductivity is derived in terms of the temperature gradients in the respective specimens and the thermal conductivity of the reference materials. In addition, testing can be performed according to modified ASTM E 1225 (for vacuum conditions, for semitransparent materials) and to C 518 Steady State Method.
System for measurement of thermal conductivity at atmospheric gas pressure
The system consists of a measuring cell, system of power control, and a computer system with interfacing board and specially developed software.