Abstract

The graphite crystal, the fundamental building block for manufactured graphite, is one of the most anisotropic bodies known. Anisotropy is the direct result of the layered structure with extremely strong carbon–carbon bonds in the basal plane and weak bonds between planes. Manufactured graphite is semimetallic in character. Conduction is by means of an approximately equal number of electrons and holes that move along the basal planes. Manufactured graphite is strongly diamagnetic. Compared with other refractories, graphite has an unusually high thermal conductivity near room temperature; above room temperature, the conductivity decreases exponentially to approximately 1500°C. The volumetric thermal expansion (VTE) of manufactured graphite is anomalously low when compared to that of the graphite single crystal. The low value of volume expansion of most manufactured graphite has been related to the microporosity within the coke particles. Graphite reacts with oxygen to form CO₂ and CO, with metals to form carbides, with oxides to form metals and CO, and with many substances to form laminar compounds. Of these reactions, oxidation is the most important to the general use of graphite at high temperatures.