Simultaneous measurement of heat capacity, thermal conductivity, and thermal diffusivity

Abstract

A new instrument is presented for the simultaneous measurement of the specific heat, thermal conductivity, and thermal diffusivity of solids and powdery materials in very wide ranges of their thermal conductivity (0.01 to200 W m - 1 K - 1 ) at temperatures between 100°C and 1750°C. These properties are usually determined by means of transient hot-wire methods, transient hot-strip methods, step-wise or pulse transient plane-source methods. With these methods either thermal diffusivity and thermal conductivity or specific heat and thermal diffusivity can be determined, but with the new procedure all thermophysical properties can be measured simultaneously. The principle of the new method consists of a quasistationary scanning of the sample temperature under adiabatic conditions, which means the chosen temperature transient is constant through the whole sample. By measuring the heat flow rate into the sample and the radial temperature difference in the sample during temperature scanning with a constant heating rate, the absolute values of the specific heat, the thermal diffusivity, and the thermal conductivity can be determined as a function of temperature in a very simple manner. Additionally, kinetic investigations are possible.