Pyrolytic graphite, also known as oriented graphite, is produced by pyrolyzing hydrocarbon gases, primarily methane and propane, at elevated temperatures of 1200–2500°C. A metallic, highly anisotropic carbon is deposited on the surrounding solid surface.
The pyrolytic carbon deposited under these conditions forms a layered structure based on a hexagonal mesh, exhibiting highly selective orientation and a very high density. If the deposition temperature is appropriately chosen, graphite with a density roughly equal to the theoretical density of graphite, namely 2.265 g/cm, can be produced.
When the hydrocarbon pressure is above 5 mmHg and the temperature is around 1700°C, the density reaches its lowest point. This is due to the formation of soot in the gas phase, which is then trapped within the pyrolytic graphite. The structure and properties of the resulting pyrolytic graphite vary significantly due to differences in feed gases and manufacturing conditions. General characteristics are shown below.