The thermal conductivity of ZTA graphite

Abstract

Measurements of the thermal conductivity of ZTA graphite from −100°C to 2700°C are reported. Three different methods were used to cover the temperature range: a transient technique, a series comparison method, and a radial heat flow method. From room temperature to 2700°C, the thermal conductivity perpendicular to the applied fabrication force (i.e. parallel to the grain) is given by k = 460/ T(° K) + 0.28 W/cm° K In the direction parallel to the applied force the thermal conductivity results are more difficult to deduce since use of the radial heat flow method introduced a two-dimensional heat flow problem with nonlinear boundary conditions, also an inherent variation in the measured values of the thermal conductivity had to be considered. These problems are discussed. The results as a whole are discussed in terms of some current ideas on heat conduction in single crystal graphite. Measurements of thermal expansion and dimensional changes which occur during the course of these measurements are described and analyzed.