The effect of temperature and holding time on structural changes during the calcination of raw petroleum cokes was studied by means of X-ray diffraction, microscopic.observations, density measurements and elementary analysis.
From the microscopic observation, it was found that the formation of pores and cracks during calcination depends strongly on the texture of the coke.The average d-spacing of (002) planes showed the highest value in the range from 1200 to 1300°C.This result suggests that thecondensation polymerization and dehydrogenation reactions lead to the formation of crystallites and parallel stacking of carbon layers in this calcination process.By means of the superposition method, apparent activation energy estimated from the changes of real density with holding time during the calcination process was about 70 kcal/mol.The value seems to be reasonable in comparison with those for carbonization and graphitization.

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It is attempted to produce high density, high strength and isotropic carbon made from carbonaceouspowder.The carbonaceous powder was prepared by carbonization of coal-tar pitch at a temperature of 440-500°C and subsequent distillation under reduced pressure.The distillation was performed at a temperature of 300-500°C below the carbonization temperature.In some cases additional quinoline extraction was carried out on the powder.Green carbon body was formed without binder pitch under isostatic pressure at room temperature.The body was heat-treated at a temperature of 1100-2800°C.Bulk density, weight loss, shrinkage, strength, lattice parameter, crystallite size and BAF of the obtained carbon body were measured.It is confirmed that high density, high strength and isotropic carbon made from the carbonaceous powder and the following results were obtained.
1) BS (benzene soluble) fraction, β-resin (benzene insoluble and quinoline soluble) fraction and QI (quinoline insoluble) fraction were able to fractionate by distillation under reduced pressure.Concentration gradient of each fraction seems to exist in the carbonaceous powder.
2) Using the powder prepared by a lower temperature of the carbonization and/or the distillation, the carbon body had higher balk density and higher strength.
3) The β-resin fraction had the effects of increasing the green density and enhancing the shrinkage of carbon body during the heat treatment.

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The thermal expansion coefficient (α_t) of graphite has been measured as a function of temperature between room temperature and1000°C by using a differential dilatometer for the four grades of specimens;AXF-5Q1 (Poco Graphite Co.), 7477PT (Le Carbone Lorraine Co.), SM1-24 (Anglo Great Lakes Co.) and IG-11 (Toyo Carbon Co.).
The measurements have been carried out within an accuracy of1.1×10^-5 (ΔL/L₀) by taking into account the variation of environmental temperature and the temperature distribution in specimens, revealing that the thermal expansion is isotropic in AXF-5Q1, 7477PT and IG-11, and α_t of IG-11 is the lowest among them.

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