The Thermal and Electrical Conductivity of Fused Quartz as a Function of Temperature

Thermal conductivity of fused quartz.—The thermal conductivity as a function of the temperature has been determined for clear fused quartz by the radial flow method from 235°K to 1225°K. The specimen was in the form of a hollow cylinder closed hemispherically at one end. Energy to maintain a steady temperature gradient was supplied by means of an electrically heated filament mounted axially inside the specimen. Thermal contact with the specimen was made with mercury inside and outside at the lower temperatures and with the tin-lead eutectic at the higher temperatures. Inside and outside temperatures were obtained with thermocouples. A guard ring scheme was used to prevent heat loss or gain at the open end of the cylinder and correction was made for the heat flow through the hemispherical end cap. The results may be represented by the linear equation: $K=3.83\mathrm{}\times {10}^{-6\mathrm{}}T+0.00163\mathrm{}$. An abrupt change in the thermal conductivity was noted in the vicinity of 1140°K which is attributed to heat treatment i.e. annealing or partial crystallization.