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Volume 1990 (1990)
- Issue 145 Pages 220-
- Issue 144 Pages 171-
- Issue 143 Pages 109-
- Issue 142 Pages 77-
- Issue 141 Pages 2-
Volume 1990, Issue 143
Displaying 1-7 of 7 articles from this issue
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Shigeru Furukawa, Sugio Otani, Akira Kojima, Masao Miyamoto1990 Volume 1990 Issue 143 Pages 109-114
Published: July 20, 1990
Released on J-STAGE: July 05, 2011
JOURNAL FREE ACCESSCarbon fiber/mortar composite (CFRC) was prepared by reinforcing long carbon fiber/cement rods in the tensional side. The mechanical behaviors of CFRC prepared from light-weight sand (CFRC-L) and standard sand (CFRC-S) were compared. Furtheremore, the calculation method of failure bending moment of CFRC and the workablity at the preparation of CFRC were also discussed. The long carbon fiber/cement rod (reinforcement) was prepared by impregnating long carbon fibers with cement paste (water-cement ratio of 50%).
The reinforcement could be easily arranged at the fixed position in the mortar matrix. The measured values of failure bending moment of CFRC-L's prepared from HPCF and from GPCF exhibited 75-90% of that of CFRC-S's. When the CFRC failed in tensile flexural failure by breaking of reinforcement, the measured values of failure bending moment were higher than 90% of the calculated ones.
This reinforcing method is effective not only for lightening of CFRC but also for the improvement of the workability of preparing CFRC. When the CFRC failed in tensile flexural failure, the failure bending moment of CFRC could be calculated in the same way as with reinforced concrete.View full abstractDownload PDF (790K) -
Kazuro Kawamura, Shiro Fujimoto, Tomio Iwata, Seiji Yamanaka, Gunjiro ...1990 Volume 1990 Issue 143 Pages 115-120
Published: July 20, 1990
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe porous and crosslinked polycarbosilane with a powerful affinity for oxygen was obtained by the pyrolysis of polydimethylsilane in N2 gas atmosphere. This polycarbosilane was converted to silicon carbide by heat-treating at the temperatures from 1200 to 1400°C in N2 gas atmosphere, and quartz was formed as a by-product. The addition of polyvinyl butyral as a carbon source to polycarbosilane prevented quartz formation. The chemical analysis of silicon carbide showed that the ratio of Si to C was not theoretical but C content was larger than Si. As the temperature rose, the ratio of Si to C approached theoretical value, and free carbon content increased.View full abstractDownload PDF (767K) -
Kazuro Kawamura, Shiro Fujimoto, Yasuhiro Tanabe, Eiichi Yasuda, Shius ...1990 Volume 1990 Issue 143 Pages 121-127
Published: July 20, 1990
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSCoal-tar pitch was heat-treated at various temperatures up to 1000°C and the weight loss (Δw/w) measurement, CHN analysis, polarized-light microscopic observation, IR and ESR spectra, and X-ray diffraction study were done. These data gave us the feature of structural change of coal-tar pitch through carbonization reaction, especially the change which occurred in the temperature range of pitch solidifying was remarkable. The behavior of structural change varied with the heat-treatment temperature (HTT) 500-600°C as a border. At HTT 600°C the bulk mesophase was formed completely and absorption bands except aromatic rings disappeared in IR spectrum, and the value of interlayer spacing showed for a typical disoriented carbon, that was 3.44Å. The radical concentration (N) was the maximum at this HTT 600°C.
By plotting log N against Δw/w, a linear relationship was observed. This relationship suggests that the amount of released components is in proportion to the amount of breaking hydrocarbon chains, and it brings the radical formation.View full abstractDownload PDF (2313K) -
Akira Kojima, Shinsuke Hoshii, Sugio Otani, Tasuku Satou, Masami Arama ...1990 Volume 1990 Issue 143 Pages 128-131
Published: July 20, 1990
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSCarbon fiber/ceramic composites (CFRC) were prepared with carbon fiber (CF) and organometallic compound (diphenyl borosiloxane).
The CF cloth laminates impregnated with diphenyl borosiloxane were heated at 350-500°C in air, and then re-heated at 1000°C in N2.
The prepared CFRC plates (4cm×1cm×0.24cm) showed the bulk density of 1.06g/cm3 and the bending strength of 33 MPa.
The coated substances on CF after heat-treatment at 1000°C was observed glass like structure by SEM, and the amorphous structure by X-ray diffraction.
The CFRC was showed good oxidation resistance with thermogravimetric analysis from room temperature to 1200°C in air.View full abstractDownload PDF (1919K) -
Masami Toriyabe, Tetsuro Yokono, Yuzo Sanada1990 Volume 1990 Issue 143 Pages 132-135
Published: July 20, 1990
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSPerformance of carbon packed columns for HPLC was tested. Carbons were prepared from PAN, nitrated and sulfonated coal tar pitches over the temperature range 600-900°C. D-glucose, sucrose and raffinose dissolved in distilled water were selected as moving phase.
The highest performance of separation was obtained with the carbons baked at 800°C.View full abstractDownload PDF (450K) -
Toshiaki Enoki, Seiichi Miyajima, Hiroo Inokuchi1990 Volume 1990 Issue 143 Pages 136-148
Published: July 20, 1990
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSAlkali-metal-graphite intercalation compounds absorb hydrogen between graphitic layers through two kinds of absorption mechanisms; physisorption andchemisorption. Below about 200K, large amount of hydrogen molecules are occluded physisorptively, while, above this temperature, chemisorption takes place where hydrogen is accommodated in the gallaries of graphitic sheets through dissociation of hydrogen molecule and charge transfer from the host material. In this article, we discuss the electronic properties and structures of alkali-metal-hydrogen-graphite intercalation compounds prepared through hydrogen chemisorption. Hydrogen chemisorption behaviors depend on the kinds of alkali-metals among K, Rb and Cs. The introduction of hydrogen induces charge transfer from the host alkali-metal-graphite intercalation compounds to hydrogen leading to the enhancement of ionicity in the intercalate lattice consisting of alkali-metal and hydrogen and the reduction in the number of graphitic π electron carriers. Especially, in potassium-hydrogen-graphite ternary systems, two-dimensional metallic hydrogen lattice with novel electronic structure is found to exist between graphitic layers.View full abstractDownload PDF (3188K) -
[in Japanese], [in Japanese]1990 Volume 1990 Issue 143 Pages 149-158
Published: July 20, 1990
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSDownload PDF (1313K)
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