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Tanigawa, Hiroyasu; Hirose, Takanori; Ando, Masami; Jitsukawa, Shiro; Kato, Yudai*; Koyama, Akira*
Journal of Nuclear Materials, 307-311(Part1), p.293 - 298, 2002/12
Times Cited Count：9 Percentile：51.46(Materials Science, Multidisciplinary)It has been a key issue to get the mechanical understanding of fracture process on microstructure basis, especially on neutron-irradiated materials, but not yet to be understood well enough as for the difficulty of making transmission electron microscope (TEM) thin film sample from mechanical-tested specimen. To solve this technical problem, the focused ion beam (FIB) micro-sampling system was installed to the Research Hot Laboratory of Japan Atomic Research Institute (JAERI), Japan. This system makes it possible to fabricate the TEM specimens from the critical points of mechanical-tested radioactive specimens, such as the crack initiation points of fatigue fracture on neutron irradiated specimen. In this paper, the microstructure of mechanical-tested specimen of Reduced Activation Ferritic/martensitic steels, RAFs are investigated focusing on the helium effects to fatigue fracture.
Ando, Masami; Tanigawa, Hiroyasu; Jitsukawa, Shiro; Sawai, Tomotsugu; Kato, Yudai*; Koyama, Akira*; Nakamura, Kazuyuki; Takeuchi, Hiroshi
Journal of Nuclear Materials, 307-311(Part1), p.260 - 265, 2002/12
Times Cited Count：39 Percentile：90.08(Materials Science, Multidisciplinary)no abstracts in English
Igawa, Naoki; Taguchi, Tomitsugu; Snead, L. L.*; Kato, Yudai*; Jitsukawa, Shiro; Koyama, Akira*; McLaughlin, J. C.*
Journal of Nuclear Materials, 307-311(Part2), p.1205 - 1209, 2002/12
Times Cited Count：16 Percentile：69.83(Materials Science, Multidisciplinary)no abstracts in English
Taguchi, Tomitsugu; Igawa, Naoki; Jitsukawa, Shiro; Nozawa, Takashi*; Kato, Yudai*; Koyama, Akira*; Snead, L. L.*; McLaughlin, J. C.*
Advanced SiC/SiC Ceramic Composites: Developments and Applications in Energy Systems; Ceramic Transactions Vol. 144, p.69 - 76, 2002/00
Process optimization for Forced-thermal gradient Chemical Vapor Infiltration (FCVI) fabrication of 75 mm diameter size SiC composites with advanced SiC fibers; Hi-Nicalon Type S and Tyranno SA, was carried out. The SiC/SiC composites fabricated by FCVI exhibited significant reduction in porosity (15.1%) and more uniform pore distribution by decreasing the MTS and H
gases flow rates in the latter part of the FCVI process. The tensile strength of the both composites using Hi-Nicalon Type S or Tyranno SA fibers was slightly increased with increased thickness of carbon interphase in the range of 75-300 nm. In order to perform the comparative testing required to directly compare the thermomechanical property changes following neutron irradiation, larger composites with uniform microstructural property are required. From the results of process optimization for fabrication of 75 mm diameter size FCVI SiC/SiC composites, the definitive purpose in this study is the fabrication of the 300 mm diameter size SiC/SiC composite with the uniform microstructural properties.
Tanigawa, Hiroyasu; Ando, Masami; Kato, Yudai*; Hirose, Takanori*; Sakasegawa, Hideo*; Jitsukawa, Shiro; Koyama, Akira*; Iwai, Takeo*
Journal of Nuclear Materials, 297(3), p.279 - 284, 2001/09
Times Cited Count：34 Percentile：89.95(Materials Science, Multidisciplinary)no abstracts in English
Tanigawa, Hiroyasu; Jitsukawa, Shiro; Hishinuma, Akimichi; Ando, Masami*; Kato, Yudai*; Koyama, Akira*; Iwai, Takeo*
Journal of Nuclear Materials, 283-287(Part.1), p.470 - 473, 2000/12
Times Cited Count：21 Percentile：77.56(Materials Science, Multidisciplinary)no abstracts in English
Yamada, Reiji; Snead, L. L.*; Kato, Yudai*
Proceedings of 4th International Energy Agency Workshop on SiCf/SiC Ceramic Composites for Fusion Structural Application, p.175 - 180, 2000/00
no abstracts in English
solutionKato, Mizuho*; Adachi, Sadia*; Toyoshima, Atsushi*; Tsukada, Kazuaki; Asai, Masato; Haba, Hiromitsu*; Yokokita, Takuya*; Komori, Yukiko*; Shigekawa, Yudai*; Sueki, Keisuke*
no journal, ,
A few studies have been so far performed on aqueous chemistry of Db, the group-5 superheavy element, by anion-exchange experiments in HF and HF/HNO mixture solutions. Although the distribution coefficient (Kd) of Db was shown to trend to Ta 
Nb Db Pa in the group-5 homologs and pseudo-homolog elements, its chemical species has not been clarified. In this work, for identification of fluoride species of Db, we performed anion-exchange experiments of Nb, Ta, and Db in HF/1.0 M HNO mixture solutions by using an automated rapid chemistry apparatus, ARCA.
