Measurement and evaluation of the high-temperature physical properties of carbon and graphite products (Part II): Thermal and electrical transport properties

For carbon and artificial graphite products, the history of methods for measuring and evaluating the temperature dependence of thermal and electrical transport properties is briefly reviewed. In thermal conductivity measurement, the transition from steady-state methods, such as heat-flow comparison, to the transient flash method is discussed. Measurement of the high-temperature electrical resistance is categorized into two methods: the direct current heating method, detecting potential difference generated by a large electrical current, and the constant-current four-terminal method, where the measurement jig is externally heated in an electric furnace. A thermal property evaluation instrument utilizing the high-temperature laser flash method is introduced, as is a high-temperature electrical resistance apparatus using the constant-current four-terminal method, both developed by the author. Measurements of the temperature dependences of thermal conductivity λ and electrical resistivity ρ in carbon and graphite products manufactured by different processes (extruded graphite electrodes, isotropic graphite, and glass-like carbon) are presented, and several factors that influence these results are discussed.