Properties of Pyrolytic Graphite

Pyrolytic graphite is a vapor-deposited form of carbon which is characterized by strong anisotropic properties. The anisotropy is caused by the tendency of the individual crystallites to align themselves in such a way that their c axes are perpendicular to the surface of deposition. The Individual crystallites are composed of parallel graphitic layers which are randomly oriented with respect to the c axis. The ultimate strength of pyrolytic graphite in tension, bending, and compression has been found to increase considerably with increasing test temperatures. Other properties such as thermal conductivity and electrical resistivity give extremely high and low conduction parallel and perpendicular to the basal planes, respectively, in addition to varying considerably with increasing test temperatures. Properties are also influenced by the as-deposited microstructure and by the amount of graphitization to which the material has been subjected. The properties and possible uses of this unique material are presented, discussed, and compared with the properties of other high-temperature materials.