Stress recrystallization of pyrolytic graphite

Graphite as deposited by cracking hydrocarbons around 2000 °C shows marked preferred orientation with consequent anisotropy, but still contains numerous structural defects. Procedures have been investigated for removing these by recrystallization around 3000 °C under a shearing stress, resulting from applying uniaxial pressures of about 400 atm to cylindrical specimens. Subsequent annealing at around 3400 °C under light confinement yields blocks of graphite whose crystal properties are comparable with those of small natural single crystals, as indicated by various tests.