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Volume 2004 (2004)
- Issue 215 Pages 221-
- Issue 214 Pages 179-
- Issue 213 Pages 123-
- Issue 212 Pages 69-
- Issue 211 Pages 4-
Volume 2004, Issue 214
Displaying 1-6 of 6 articles from this issue
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Noboru Akuzawa, Takeshi Tajima, Yasushi Soneda, Yoichi Takahashi2004 Volume 2004 Issue 214 Pages 179-183
Published: September 01, 2004
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSCsC24 samples were prepared from artificial graphite materials, derived from petroleum cokes and additional pitch binder, with different heat-treatment temperatures (HTTs) between 1300 and 2800°C. The sorption isotherms for the systems, CsC24-H2, -D2, -N2 and-Ar at 77K were determined. All the CsC24 samples were able to take up these molecules, irrespective of the HTT of the host materials. The saturated amount of sorption, (nmolecule/nCs) sat., increased with HTT of the host carbons. For H2-and D2-sorption, (nmolecule/nCs) sat. increased monotonically with HTT from HTT-1300 up to-2000, and then stepwise increase was observed from HTT-2000 up to -2800. This behavior was considered to be a manifestation of the drastic change of the structure of host carbons at around HTT-2000. The sorption isotherms were well fitted by the Langmuir equation. This fact suggested the sorbed molecules are accommodated in the interlayer nanospace even for CsC24 samples prepared from carbons with low HTT such as HTT-1300.View full abstractDownload PDF (845K) -
Keiichi Okuyama, Masaru Zako2004 Volume 2004 Issue 214 Pages 184-190
Published: September 01, 2004
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSWhen the phenolic CFRP is heated in a nitrogen gas atmosphere, the phenolic resin is pyrolyzed and the gas containing oxygen is generated. This generated oxygen oxidized the phenolic CFRP. The oxidation of carbonized phenolic CFRP in the nitrogen gas atmosphere was found to be divided into the rate-controlled oxidation region and the diffusion-controlled oxidation region. The boundary temperature was approximately 1600K. The activation-energy E, collision-frequency coefficient ko, and diffusion-controlled oxidation constant Co were determined. They were used for estimating the surface mass loss rate of the carbonized phenolic CFRP in the rate-controlled oxidation region and the diffusion-controlled oxidation region. The activation energy E was estimated to be 182.4kJ/mol, and the ko was expressed as ko=10.0/ (τPe) 0.5, where Pe is the stagnation pressure measured at the specimen surface. C0 could be expressed as a function of the reaction rate I by C0=1.3×10-5ln (τ) +3.3×10-5.View full abstractDownload PDF (1560K) -
Hidetaka Konno, Yukihiro Takahashi, Hiroki Habazaki2004 Volume 2004 Issue 214 Pages 191-193
Published: September 01, 2004
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSAn organic solution of tris (acetylacetonato) iron (III) was impregnated by sorption into exfoliated graphite and dried at 180°C in air. By 1h treatment of this precursor at 900-1200°C in Ar (heating rate to each temperature: 400Kh-1), iron/graphite composites containing 33mass% Fe were obtained. In these composites fine α-Fe particles of several tens to hundreds nanometers were uniformly dispersed, though the surface of some particles may be oxidized by exposure to air. For the 1000°C product, magnetization assigned for iron was 154emu g-1, and the coercive force, Hc, 420Oe.View full abstractDownload PDF (770K) -
Akira Yamashita, Shinsaku Minoura, Takanori Miyake, Naoki Ikenaga, Hir ...2004 Volume 2004 Issue 214 Pages 194-201
Published: September 01, 2004
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSIn order to discuss quantitatively the effect of functional groups of activated carbon fibers (ACFs) on electric double layer characteristics, ACFs with various amounts of functional groups were prepared from the same ACF by redox methods. The amount of functional groups of ACFs was compared between the method by back titration and by X-ray photoelectron spectroscopy (XPS). In the case of the aqueous electrolyte, the electric capacity depended more on oxygen functional groups than on BET surface area. At the greatest 30% of increase in electric capacity was obtained by using ACFs with different amount of oxygen functional groups between the positive electrode and the negative one. It was considered that a larger number of functional group promotes not only the wettability of electrodes but also the negative charge of electrodes leading to an increase in capacity. On the other hand, in the case of the organic electrolyte, pore structure seemed to be a more dominant factor than functional group.Also, the characteristics of the electrodes after 30000 cycle charge-discharge were determined to confirm the reliability in an extended cycle operation. A significant increase in phenolic hydroxyl group was confirmed on the positive electrode.View full abstractDownload PDF (1539K) -
Takeshi Morimoto2004 Volume 2004 Issue 214 Pages 202-209
Published: September 01, 2004
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSElectric double-layer capacitors based on the charge storage at the interface between a high specific surface area activated carbon electrode and an electrolyte solution have been developed, and are widely used as maintenance-free power source for IC memories and microcomputers. Following the production of small size capacitor of the capacitance up to 1F, middle size capacitor having the capacitance up to 100F were produced and applied to power sources combined with solar cell in traffic signal and so on. Recently, large size capacitors of the capacitance about 1500F are being developed for large power sources such as in HEV. However, the energy density of electric double-layer capacitors is smaller than that of batteries such as the lithium ion battery. To solve this problem, new electrolytes, electrode materials and the construction of the cells were developed. As a result, the energy density of available large device (1000-2000F) was enhanced to 6 Wh/l at power density of 800W/1 and expected to be larger in near future.View full abstractDownload PDF (4561K) -
2004 Volume 2004 Issue 214 Pages 218
Published: 2004
Released on J-STAGE: March 01, 2011
JOURNAL FREE ACCESSDownload PDF (71K)
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