Spot-Pulse-Heating Method for Measuring Thermal Conductivity and Thermal Diffusivity of Silica Thin Sheets

The spot-pulse-heating method is based on the relationship between the surface-temperature increase of a sample at the end of each heating interval, the thermal conductivity and the thermal diffusivity of the sample. The relationship is obtained by solving the Fourier’s equation. The surface-temperature increase at the end of each heating interval is proportional to the reciprocal of square root of time. The intercept and the slope of this straight line give the values of thermal conductivity and thermal diffusivity.This method was examined by measuring the thermal conductivity and the thermal diffusivity of fused-SiO2 and PbO–SiO2 with about 10 mm thickness at room temperature. The obtained values were in good agreement with ones in literatures.Next, this method has been successfully applied to fused-SiO2 with 1 mm to 60 μm thickness without the influence of substrates. The thermal conductivity and the thermal diffusivity of thin sheets of fused-SiO2 are independent of the thickness and constant at about 1.05 W·m−1·K−1 and 6.5×10−7 m2·s−1, respectively.