TANSO

Study on Carbonization of Green Carbon Body under Pressure

Kanji Matsuo, Shoji Hori, Tadashi Nakamura, Katsushi Fukada

1968 Volume 1968 Issue 55 Pages 114-121
Published: December 10, 1968
Released on J-STAGE: June 28, 2010

DOIhttps://doi.org/10.7209/tanso.1968.114

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Coal tar pitch baked under pressurized Ar gas atmosphere has been found to yield considerably high coking value not only by itself but when blended in the green mix, as compared with the normal process so far utilized. The tests were examined under a variety of conditions of pressure and temperature, and led to the following conclusions: (1) The pressure built up in the vessel lowers the temperature and shortens the time for the completion of carbonization.(2) The baked products obtained in this way exhibit higher density, more strength and lower resistivity than those prepared through the normal process. Such effects on the physical properties have been increased further after graphitization by usual method.

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Paramagnetic Resonance Absorption in Annealing Process of Radiation-Damaged Graphite

Shigemi Yugo, Takuro Tsuzuku

1968 Volume 1968 Issue 55 Pages 121-123
Published: December 10, 1968
Released on J-STAGE: June 28, 2010

DOIhttps://doi.org/10.7209/tanso.1968.121

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An ESR study has been made of the isothermal annealing of radiation damage in a reactor-grade polycrystalline graphite after fast neutron bombardment at room temperature to total dose of 5.8×10²⁰ nvt. The absorption found for the specimens annealed below 950°C is concluded to be due to the unpaired electrons which as pointed out by Mrozowski are localized to the radiation-induced defects. On the other hand, for those annealed above 1450°C the Pauli-McClure type paramagnetism due to conduction carriers takes main part in ESR, while the localized spin centers still participate to some extent. In the annealing range between 1000°C and 1400°C no absorption signals have been observed, which is likely due not to the complete extinction of spin species but to the extreme broadening of line originating from some structural reasons.

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Temperature gradient developed across the thickness of resistance-grown pyrolytic graphite

Toshio Hirai

1968 Volume 1968 Issue 55 Pages 124-129
Published: December 10, 1968
Released on J-STAGE: June 28, 2010

DOIhttps://doi.org/10.7209/tanso.1968.124

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Pyrolytic graphite was prepared by resistance heating of graphite substrate at the deposition temperatures of 1550-2270°C, the gas pressures of 5-50 mmHg, and a gas flow rate of 640 cm³/min. To determine the temperature drop established across a layer of pyrolytic graphite, radial holes about 2 mm in diameter were drilled down to the interface between the deposits 0.36-3.05 mm thick and the graphite substrate. The whole was then heated to various temperatures by passing the requisite currents.
Temperature gradient obtained was 140°C/mm for the deposit (type-(a)) prepared at temperatures below about 1800°C, and 350°C/mm for the deposit (type-(b)) prepared above about 2000°C. An estimate of the c-axis thermal conductivity was made, and it was found to increase from 0.015 to 0.04 w cm^-1 deg C^-1 over the temperature range of 1600-2000°C for the type-(a) pyrolytic graphite and to increase from 0.02 to 0.03 w cm^-1 deg C^-1 over the range 2000-2400°C for the type-(b) pyrolytic graphite. Annealing effect was discussed.

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[title in Japanese]

[in Japanese]

1968 Volume 1968 Issue 55 Pages 130-139
Published: December 10, 1968
Released on J-STAGE: June 28, 2010

DOIhttps://doi.org/10.7209/tanso.1968.130

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