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Volume 1991 (1991)
- Issue 150 Pages 266-
- Issue 149 Pages 191-
- Issue 148 Pages 134-
- Issue 147 Pages 57-
- Issue 146 Pages 2-
Volume 1991, Issue 148
Displaying 1-7 of 7 articles from this issue
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Shiushichi Kimura, Masato Ishizaki, Kouichi Yasuda, Yohtaro Matsuo1991 Volume 1991 Issue 148 Pages 134-141
Published: June 30, 1991
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe dependence of porosity on the fracture toughness of polycrystalline graphite materials was investigated. Two isotropic graphites with different microstructures were pitch-impregnated, carbonized, and then graphitized to change the porosity. The fracture stress σf and the fracture toughness KIC of the graphites were measured by three point bending test and compact tension test, respectively. Both values σf and KIC linearly increased with decreasing porosity P (ranging from 21% to 13%) for each graphite material, and expressed by;
σf=σof (1-bsP)
KIC=KoIC (1-btP)
The linear regression analysis suggested that the parameter bt was nearly equal to the parameter bs for each graphite, and that the values of KoIC were estimated to be about 1.3MPa√m for both graphites. It was elucidated that the dependence of porosity on the fracutre toughness was similar to that on the fracture stress of the polycrystalline graphite materials.View full abstractDownload PDF (2939K) -
Takeshi Kikutani, Kiyoshi Yamamoto, Akira Takaku1991 Volume 1991 Issue 148 Pages 142-150
Published: June 30, 1991
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSA polyacrylonitrile-based carbon fiber tow was heat-treated by directly passing electric current through the tow. The relation between the surface temperature of the tow and supplied electric power was analyzed by an energy balance equation. The rediation became the dominant factor for the heat-loss at high temperatures. The apparent heatconductivity of tow increased with increasing temperature. Temperature distribution in the crosssection of tow was analyzed by considering the temperature dependences of heat-conductivity and specific resistivity. The calculated temperature difference between the center and the surface of the tow increased with increasing surface temperature. The temperature distribution was reduced by installing a reflector around the tow. It is expected that the temperature distribution in a tow gives rise to a certain distribution of the structure of carbon fibers. This subject was also studied by analysing the intensity profiles of wide-angle x-ray diffraction. The integral width of 002 reflection for the tow heat-treated by direct currenting was calculated by using the analyzed temperature distribution and the heat-treatment temperature versus layer thickness relation obtained for the carbon fibers heat-treated with a conventional furnace. The estimated values agreed well with the experimental ones.View full abstractDownload PDF (1154K) -
Kazuji Kushiro, Hirokazu Oda, Chikao Yokokawa1991 Volume 1991 Issue 148 Pages 151-156
Published: June 30, 1991
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe present study deals with elucidating the effect of surface acidic groups of activated carbon on the adsorption rate from aqueous solutions. In order to modify the surface characteristics, a commercial activated carbon was subjected to oxidation reactions with air or aqueous ammonium peroxodisulfate and heat-treatment at 800°C under nitrogen atmosphere. The samples thus obtained were determined the adsorption rates of benzoic acid and phenol from aqueous solutions. The amounts of equiliblium adsorbed of phenol and benzoic acid decrease with increasing the acidities of activated carbon surface. It was found that adsorption rate is retarded considerably by the acidities of activated carbons.View full abstractDownload PDF (800K) -
Yoshio Yamada, Takeshi Furuta, Minoru Shiraishi1991 Volume 1991 Issue 148 Pages 157-161
Published: June 30, 1991
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSCarbonization and graphitization behaviors of anthracene polymers were investigated to characterize the carbon products obtained. The polymers consisting of 3-4 anthracene units (Poly (9, 10-anthracene diylidene)) were synthesized by use of dehydration and polycondensation of polyphosphoric acids. The weight loss of the polymers occurs predominantly between 350-500°C and the yield of the products treated at 1000°C reaches 72-79%. It was found from the analyses of the evoluved gases and the FT-IR spectra that dehydrogenation at the terminal CH2 groups of the polymer and elimination of CO from quinone groups at the anthracene terminal take place at these temperature ranges. The carbonized product from anthrone polymer showed a fine mozaic texture although it melted at 290-300°C. This may be because the anthracene units are twisted with each other. Also, d002 spacing and La values obtained from X-ray diffraction profilesof the heat-treated polymer suggest that the graphitizability of the polymer is less enhanced even at high temperatures.View full abstractDownload PDF (557K) -
Yasuhiro Tanabe, Ryouji Chikugo, Hajime Ishii, Mitsuhiro Munakata, Tos ...1991 Volume 1991 Issue 148 Pages 162-165
Published: June 30, 1991
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSThe effects of bending and tensile tests on the off-axis strengths were investigated using two types of C/C composites; unidirectional and two dimensional woven composites. The tensile strengths of axial direction were nearly equal to the bending ones for both of the composites. However, the tensile strength in off-axis strengths of the unidirectional and of the two dimensional composites were dominated by the tensile strength and shear strengths of the matrix, respectively.View full abstractDownload PDF (445K) -
Fujio Okino1991 Volume 1991 Issue 148 Pages 166-171
Published: June 30, 1991
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSAn image scanner (IS), which is less expensive and more handy than a microphotometer, was successfully used to read Debye-Scherrer (DS) powder diffraction photographs. The data obtained by the IS were comparable to those by a photometer.
The intensities are read in 256 levels with the 600 DPI interval along the 2θ The peak positions and intensities are determined by a personal computer on the CRT with a mouse. Alternatively, the data can be directly processed by softwares such as smoothing, background subtraction, Kα2 elimination, peak search and peak separation. Being put in the same format as that of the automated counter diffractometer equipped with the aforementioned softwares, the storage retrieval and comparison of the DS data are greatly facilitated.
Although the counter diffractometer method is faster, more accurate and more sensitive, the DS method has several advantages over it; the amount of specimen can be very small, and air-sensitive materials can be easily handled with a glass capillary. Furthermore, halos and diffuse scatterings, which might evade the counter method, can be identified by the DS, or film methods in general.
Application of this method to two dimensional photographs can partly substitute for the costly imaging plate system.View full abstractDownload PDF (727K) -
[in Japanese]1991 Volume 1991 Issue 148 Pages 172-184
Published: June 30, 1991
Released on J-STAGE: June 28, 2010
JOURNAL FREE ACCESSDownload PDF (1604K)
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