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Sogabe, Toshiaki; Ishihara, Masahiro; Baba, Shinichi; Tachibana, Yukio; Yamaji, Masatoshi*; Iyoku, Tatsuo; Hoshiya, Taiji*
Materials Science Research International, 9(3), p.235 - 241, 2003/09
2D-C/C composite is one of the promising materials as a next-generation core material in gas-cooled reactors. Effect of air-oxidation on the thermal diffusivity up to 1673K of the 2D-C/C composite was investigated. The C/C composite specimens for measurement of thermal diffusivity were oxidized from 1 to 11 percent weight loss in air at 823K. Thermal diffusivity at room temperature declined 1020 percent for parallel to lamina direction and 59 percent for that of perpendicular within 11 percent weight loss by oxidation. Thermal diffusivity tended to decrease gradually as the increase of oxidation loss in parallel to lamina, however, it decreased in the beginning of oxidation pretty much and not so changed by further oxidation loss in perpendicular to lamina. Change in thermal conductivity under oxidation condition was also estimated.
Sogabe, Toshiaki; Ishihara, Masahiro; Baba, Shinichi; Kojima, Takao; Tachibana, Yukio; Iyoku, Tatsuo; Hoshiya, Taiji; Hiraoka, Toshiharu*; Yamaji, Masatoshi*
JAERI-Research 2002-026, 22 Pages, 2002/11
Carbon Fiber Reinforced Carbon-carbon Composites, C/C composites, have been developed and extensively studied their characteristics. C/C composites are considered to be promising materials for the application of a control rod in the next high performance high temperature gas-cooled reactors. In the present paper, details of the development of the candidate C/C composite are described. In the course of the development of the material, especially, feasibility of the production, stableness of the supply and cost are much taken into consideration. As the physical properties of the material, high mechanical strength such as tensile and bending, high fracture strain and fracture toughness and low dimensional change by neutron irradiation have to be met. The developed 2D-C/C composite consists of plain-weave PAN-based carbon fiber cloth and pitch derived matrix. Also, high purification up to the level of nuclear grade was successfully attained in the composite.
Ishihara, Masahiro; Kojima, Takao; Hoshiya, Taiji
Proceedings of International Conference on Carbon in 2002 (Carbon2002) (CD-ROM), 6 Pages, 2002/00
Bending failure of two-dimensional C/C composite was studied by both experimental and analytical approaches. In the experiment, a bending test and observation of failure surfaces were performed. From the surface observation, three kinds of fundamental fracture modes were observed; these were tensile, compressive and shear fracture modes. In the analysis, the risk-based statistical fracture theory, so-called the competing risk theory was applied to clarify the bending failure taking account of the competition of these fracture modes. Parameters used in the theory on these fundamental fracture modes were determined by additional experiments, and the theory was applied to the bending failure prediction. As a result of this study, it is concluded that the bending failure was well predicted by the theory, and that the theory would be possible to predict the strength under stress gradient condition. Furthermore, a new strength prediction method combined with FEM code, which is applicable to arbitrary shaped structures with stress gradient, was proposed in this paper.
; *; Araki, Masanori; Nakamura, Kazuyuki; Akiba, Masato
Journal of Nuclear Materials, 258-263, p.318 - 322, 1998/00
Times Cited Count:8 Percentile:57.22(Materials Science, Multidisciplinary)no abstracts in English
Nakamura, Kazuyuki; *; Dairaku, Masayuki; Akiba, Masato; Araki, Masanori; Okumura, Yoshikazu
Journal of Nuclear Materials, 220-222, p.890 - 894, 1995/00
Times Cited Count:19 Percentile:84.35(Materials Science, Multidisciplinary)no abstracts in English