Simultaneous Measurement of Thermal Conductivity, Thermal Diffusivity, and Specific Heat of Oxides at High-Temperature with the Use of Hot Strip Method

A new simultaneous measurement method of thermal conductivity, thermal diffusivity, and specific heat for oxides at high temperature has been proposed with the use of hot strip.The principle of this measurement is based on the two solutions of the Fourier’s partial differential equation solved under the different conditions of time. The response curve of temperature-increase obtained by a long time measurement is proportional to the logarithm of time. The slope of this straight line gives thermal conductivity (λ). On the other hand, the response curve by short time measurement is proportional to the square root of time. The slope of this straight line and the value of thermal conductivity offer thermal diffusivity (κ) and specific heat (Cp), by virtue of ρCp=λ⁄κ (ρ: density).With the use of this method, thermal conductivity, thermal diffusivity, and specific heat of 30Na2O-70SiO2 slag have been measured over the wide temperature range of 300 to 1500 K. The thermal conductivity is in good agreement with that by the hot wire method. The thermal diffusivity is nearly constant at low temperatures but decreases with increasing temperature. The specific heat increases with increasing temperature but the absolute values are 1.1-1.2 times larger than those by the laser-flash method.The hot strip method can be expected to permit a simultaneous measurement of thermal conductivity, thermal diffusivity, and specific heat at high temperatures for various oxides.