Pyrolytic
carbon deposits were produced in a fluidized bed between 1900" and 2400°C from a carrier gas containing between 1 o/0 and 15 o/0 methane. The carbons had either a 'granular', 'laxninar' or 'isotropic' microstructure. Formation of "granular" carbon occurred at low methane partial pressures and low bed surface areas. Increasing the deposition temperature decreased the metallographic grain size and increased the density, X-ray apparent crystallite size, and preferred orientation of the granular deposits so that at the highest temperature, the deposits took on a laminar appearance. Increasing the deposition temperature increased the crystallite size and density of the isotropic and transition deposits. The elastic moduli and fracture stresses of the carbons deposited from 3% methane rose from 1.5 to 1.8~ 10s psi and 18 to 32X lOa psi, respectively, as the deposition temperature was increased from 1900" to 2400°C. The isotropic and transition carbons had fracture stresses of -30x lo* psi and elastic moduli that decreased from ~2.2 to -1.6~ lOa psi over the deposition temperature range of 1900" to 2400°C. The carbons had thermal conductivities perpendicular to the deposition plane in the range of 1 to 6 x 1O-a Cal/cm set "C. The conductivities were highest for the isotropic carbons and lowest for the most highly oriented laminar carbons. The relations between deposition conditions, structure, and properties are discussed.