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Volume 1986 (1986)
- Issue 127 Pages 157-
- Issue 126 Pages 89-
- Issue 125 Pages 45-
- Issue 124 Pages 2-
Volume 1986, Issue 126
Displaying 1-9 of 9 articles from this issue
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Isao Mochida, Harry Marsh1986 Volume 1986 Issue 126 Pages 89-95
Published: July 25, 1986
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe phenomenon of puffing is related to the rates of gas evolution and graphitization, molecular size of evolved gas, and porosity, texture and graphitizability of coke. Evolution of gases containing sulfur, nitrogen or metals (in the secondary puffing) causes the problem at the graphitization process by pressing the pore wall of the carbon which exhibits some local plastisity. The pressure induced is a function of the pore size relative to the rate of gas evolution and its molecular size. Thus, the timing of the gas evolution and graphitization is a key factor. The rapid heating for the graphitization allows more overlap-ping of these phenomena and increases the gas evolution at a time to produce higher pres-sure, enhancing the extent of puffing.
Cokes of low GTE often with large-sized optical texture of flow orientation are most susceptible to puffing because of its smallest resistivity against pressure for expansion.The macroscopic shrinkage of the coke due to the graphitization is known small with the coke of flow texture. Since such shrinkage can compensate the puffing to some extent, the needle coke suffers more puffing than the regular coke.Based on such understandings, the preferable structure of coke is proposed for the smaller puffing trend. Additives can also reduce the extent of puffing through the acceleration of graphitization, trapping the evolved gas molecules, and gasification. The former two roles changes the timing of graphitization and gas evolution and the last increases the porosity in the coke to allow the free gas evolution.
The puffing of carbon artifact is briefly discussed from the view of its composite natures.View full abstractDownload PDF (1135K) -
The Reaction Rate and Oxidation Profile in the BlockTakeshi Meguro, Ichiro Midorikawa, Naochika Torikai, Takashi Ohno1986 Volume 1986 Issue 126 Pages 96-103
Published: July 25, 1986
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSIn order to elucidate the influence of baking temperatures of carbon blocks in the oxidation with carbon dioxide, the gasification rates and exidation profiles inside of the carbon rods were investigated. The carbon materials used in this experiment were obtained from the moldings, 50×50×85mm, made from pulverized pitch cokes and binder pitch.The moldings were baked at different temperatures, 1000°C (D-1000), 1400°C (D-1400), 1800°C (D-1800) and 2200°C (D-2200), respectively. The carbon blocks produced in these manners were machined in the shape of rod, ∅20×30mm. Each of the carbon rods had almost the same pore size distribution, centering at around 4μm in radius, The oxidation was carried out on these carbon rods at 850°-1000°C in the flow of carbon dioxide and the reacted rod samples of burn-off 3.5% and 5% were obtained.
The relative gasification rates of carbon rod samples were as follows:
D-1000, D-1400>D-1800>>D-2200 at 850°and 900°C,
D-1400>D-1000>D-1800>>D-2200 at 950°and 1000°C.
After the reaction, the rod was lathed and thin layers were cut off from the surface of the rod at every0.5mm thickness. For each of the cuts, the weight loss and size change of the rod was measured and bulk density of the thin layer was calculated.The BET surface area for each of the thin layers was determined by the gas adsorption method applied to the cut off powder.
The decreasing of bulk density, which proceeds rapidly at the surface and gradually inside of the rod, was observed on each of the samples. Particular decreasing of the bulk density at the surface was found in the case of D-1000. It seems the density gradient suggests the evidence for the concentration gradient of reactant from the surface toward the inside of the rod. In the results of BET surface area, the samples heat-treated at the lower temperatures, such as 1000°C or 1400°C, had higher surface areas than those of the other samples. And rapid decreasing for D-1000and slight decreasing for D-1400were observed from the surface toward the inside of the rods. On the other hand, no remarkable changes in the surface area were found throughout the rods of samples heat-treated at the higher temperatures.
Discussion was given on these results and an equation of gasification rate was presented.View full abstractDownload PDF (1191K) -
Akira Yoshida, Yutaka Kaburagi, Yoshihiro Hishiyama1986 Volume 1986 Issue 126 Pages 104-107
Published: July 25, 1986
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSEvolution of FT-IR spectrum for three kinds of graphitizing carbon precursors (bulk mesophase samples of purified petroleum pitch, quinoline soluble component of coal tar pitch and polyvinyl chloride pitch) by heat treatment has been investigated. The precursors were heat-treated at temperatures 430-900°C. Drastic change in whole spectrum is observed at a characteristic heat treatment temperature TF for each precursor. TF depends on the starting material of the precursor, and can be correlated to the graphitizability of the carbon derived from the precursor.View full abstractDownload PDF (517K) -
Michio Inagaki, Kazuo Muramatsu1986 Volume 1986 Issue 126 Pages 108-110
Published: July 25, 1986
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSElectrical conductivity of ternary graphite intercalation compounds containing organic molecules was measured by non-contact technique and compared with those of the original graphite sheet and binary potassium compounds KC8 and KC24. By the intercalation of organic molecules (tetrahydrofuran, benzene, dioxane, and furan) into the binary compounds, the conductivity decreased; the lower the conductivity the larger the content of organic molecules.View full abstractDownload PDF (415K) -
Michio Inagaki, Kaneharu Goto, Mototsugu Sakai1986 Volume 1986 Issue 126 Pages 111-113
Published: July 25, 1986
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe behavior of mesophase formation at 480 and 500°C under a pressure of 30 MPa was studied on the fractionated pitches with different molecular weights, and compared with that of the original pitch. The formation of mesophase spheres was in a quite different way in each fractionated pitch; the fraction with high molecular weight resulted in a small number of large spheres, some of which were coalesced, and high concentration of small spheres was found in the fraction with low molecular weight.View full abstractDownload PDF (4479K) -
Kazuro Kawamura1986 Volume 1986 Issue 126 Pages 114-116
Published: July 25, 1986
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSExplosive shock compression of about 8.52×104 atom was given to acetylene black packed into a mild steel container by a low density of 0.094g/cm3. The acetylene black was graphitized by this shock compression and variety of shapes could be seen in it by the observation of electron microscope. It is the most interesting morphologycal change that the spherule of graphite produced in the shocked acetylene black. The spherule might be formed from droplet. The formation of droplet suggests that the temperature rises above 4000°C.View full abstractDownload PDF (2802K) -
Kazuro Kawamura1986 Volume 1986 Issue 126 Pages 117-119
Published: July 25, 1986
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSDamages on acetylene black (AB) and natural graphite (GP) exposed to the detonation reaction of PETN were examined by X-ray measurement and electron microscopic observation. Their surfaces were covered by amorphous carbons but they could be removed by treatment of hydrochloric acid. On AB the carbon structure disappeared but the graphitization proceeded inside. On the other hand, GP was reduced in size and damaged in structure.View full abstractDownload PDF (678K) -
History and ProspectsHidemasa Honda1986 Volume 1986 Issue 126 Pages 120-138
Published: July 25, 1986
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe study of carbonaceous mesophase began with a study in coking process of coals. Many studies about mesophase in heat-treated pitches have been done since those of Brooks and Taylor.
Mesophase has a soluble one and a fusible one in addition to an insoluble and infusible one. These have been cleared up with the physicochemical properties of quinoline-soluble and quinoline-insoluble mesophase, and the heat-treating properties of mesophase by polarized micrograph observation under heating stage.
As an utilization of mesophase now, there are high performance pitch-based carbon fiber and meso-carbon microbeads as a filler of high performance liquid chromatography.
The future utilization of mesophase will depend on the control of mesophase properties.View full abstractDownload PDF (21995K) -
[in Japanese]1986 Volume 1986 Issue 126 Pages 139-151
Published: July 25, 1986
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSDownload PDF (12468K)
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