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Saito, Kei*; Hirade, Tetsuya; Takai, Kenichi*
Key Engineering Materials, 967, p.11 - 16, 2023/07
Hydrogen-enhanced strain-induced vacancy, one of the defects associated with promising hydrogen embrittlement mechanisms, was validated for tempered martensitic steel showing quasi-cleavage fracture with a tensile strength of 1500 MPa level by slow strain rate tensile test in-situ electrochemical hydrogen charging. The effect of newly formed vacancy-type defects on mechanical properties of tempered martensitic steel was also studied. Combined use of low-temperature thermal desorption spectroscopy (L-TDS) and the tensile test revealed the following three things: (i) hydrogen enhanced the accumulation of vacancy-type defects with plastic straining, (ii) accumulated vacancy-type defects deteriorated the ductility of the tempered martensitic steel after hydrogen release, and (iii) aging in the range from 50
C to 150C after applying given plastic strain with hydrogen charging decreased the amount of newly formed vacancy-type defects, and then resulted in the recovery of the ductility.
Futakawa, Masatoshi; Tsutsui, Kihei*; Kogawa, Hiroyuki; Naoe, Takashi
Key Engineering Materials, 715, p.203 - 209, 2016/11
The developments of the high power proton accelerators become a worldwide interest to provide various applications, where the targets are demanded to efficiently produce secondary beams and to survive intensive MW class proton beam power supplied by the accelerators. Solid metal targets might be melted by very high heat flux that is caused by the proton beam bombardment. In fact, the incident occurred at J-PARC, in which the gold solid target was locally melted to explosively jet molten gold. The jet collided with a structural beryllium flange plate that has a function of vacuum boundary. Some parts of gold were splashed and the other stuck on the flange plate. The relationship between the impact velocity and the morphology of the sticking pattern on the plate was quantitatively evaluated by introducing fractal analysis. It was found that the fractal dimension is correlated with the impact velocity and might be a useful factor to indicate the localized impact force and behavior.
Sumita, Junya; Shibata, Taiju; Iyoku, Tatsuo; Ishihara, Masahiro; Nishihara, Tetsuo
Key Engineering Materials, 697, p.797 - 806, 2016/07
Nuclear energy is one of the most promising energy sources to satisfy energy security, environmental protection, and efficient supply. The High Temperature Gas-cooled Reactor (HTGR) has attractive inherent safety features and it can be used as many kinds of heat applications such as hydrogen production, electricity generation, process heat supply, district heating and desalination. Many countries, especially developing countries, show their interests in HTGR. Graphite materials are used for the core components of the HTGR. IG-110 graphite, fine-grained isotropic graphite, with high strength and high oxidation resistance is used in the High temperature Engineering Test Reactor (HTTR) of Japan Atomic Energy Agency (JAEA) and High Temperature Reactor-Pebble-bed Modules (HTR-PM) in China. IG-110 graphite is a major candidate for the core graphite components of the Very High Temperature Reactor (VHTR) which is one of HTGRs and one of the most promising candidates as the Generation-IV nuclear reactor systems. JAEA established the graphite structural design code and inspection standard of graphite to construct the HTTR. JAEA developed an in-service inspection method and a draft graphite structural design code for future HTGR on the basis of the HTTR technologies. Moreover, JAEA are now developing the design data base of IG-110 graphite and IG-430 graphite including irradiation data for HTGR. This paper describes design of core components of HTTR and R&D on nuclear graphite for HTGR.
Kada, Wataru*; Kambayashi, Yuya*; Miura, Kenta*; Saruya, Ryota*; Kubota, Atsushi*; Sato, Takahiro; Koka, Masashi; Kamiya, Tomihiro; Hanaizumi, Osamu*
Key Engineering Materials, 643, p.15 - 19, 2015/05
Miura, Kenta*; Sato, Takahiro; Ishii, Yasuyuki; Kiryu, Hiromu*; Ozawa, Yusuke*; Koka, Masashi; Takano, Katsuyoshi*; Okubo, Takeru; Yamazaki, Akiyoshi; Kada, Wataru; et al.
Key Engineering Materials, 534, p.158 - 161, 2013/00
Times Cited Count：5 Percentile：87.72(Nanoscience & Nanotechnology)
m band using focused proton beamMiura, Kenta*; Machida, Yuki*; Uehara, Masato*; Kiryu, Hiromu*; Ozawa, Yusuke*; Sasaki, Tomoyuki*; Hanaizumi, Osamu*; Sato, Takahiro; Ishii, Yasuyuki; Koka, Masashi; et al.
Key Engineering Materials, 497, p.147 - 150, 2012/00
Times Cited Count：7 Percentile：93.90(Engineering, Electrical & Electronic)m band using focused proton beamMiura, Kenta*; Machida, Yuki*; Uehara, Masato*; Kiryu, Hiromu*; Ozawa, Yusuke*; Sasaki, Tomoyuki*; Hanaizumi, Osamu*; Sato, Takahiro; Ishii, Yasuyuki; Koka, Masashi; et al.
Key Engineering Materials, 497, p.147 - 150, 2011/12
Times Cited Count：6 Percentile：2.48
layersUmenyi, A. V.*; Hommi, Masashi*; Kawashiri, Shinya*; Shinagawa, Teruyoshi*; Miura, Kenta*; Hanaizumi, Osamu*; Yamamoto, Shunya; Inoue, Aichi; Yoshikawa, Masahito
Key Engineering Materials, 459, p.168 - 172, 2011/04
A new type of two-dimensional photonic crystal (2-D PhC) waveguide was designed using finite difference time domain method to operate at a wavelength of 1.55 m applicable to optical fiber-communication systems. We estimated that a triangular-lattice 2-D PhC structure formed by air holes with a diameter of 465 nm and a period of 664 nm suit our purpose. To form a core of the waveguide, Si ions were implanted into a SiO layer by using a 400-kV ion implanter. The implantation energy was 80 keV and the implantation amount was 1
10
ions/cm
. The electron beam resist was spin-coated on a substrate and the designed pattern was written lithographically in the resist using Electron Beam. Atomic force microscope measurements revealed that the diameter and the period of air holes of the waveguide were 466 and 666 nm. These values were nearly equal to the designed ones. We thus succeeded in fabricating 2-D PhC waveguides in a Si-ion-implanted SiO layer.
Yamada, Tomonori; Kushida, Noriyuki; Araya, Fumimasa; Nishida, Akemi; Nakajima, Norihiro
Key Engineering Materials, 452-453, p.701 - 704, 2011/01
The paper describes a component-wise meshing approach and bonding strategy on the interface of components. In order to assemble component-wise meshes, the penalty method is introduced not only to constrain the displacements, but also to introduce classical spring connection on the joint interface. The convergence performance of an iterative solver with penalty method is investigated and the detailed component-wise distributed computation scheme is described with numerical examples.
-poly(NIPAM-
-HEMA) graft copolymersQuynh, T. M.*; Yoneyama, Masaru*; Maki, Yasuyuki*; Nagasawa, Naotsugu; Dobashi, Toshiaki*
Key Engineering Materials, 459, p.51 - 56, 2010/12
Times Cited Count：3 Percentile：79.07(Engineering, Electrical & Electronic)Different poly(
-isopropylacrylamide-
-hydroxyethyl methacrylate) copolymers [P(NIPAM--HEMA)] were synthesized from -isopropylacrylamide (NIPA) and hydroxyethyl methacrylate (HEMA) monomers by both radical and radiation polymerizations for comparison. PLLA-
-P(NIPAM--HEMA) graft copolymers were synthesized from L-lactide and respective P(NIPAM--HEMA) copolymers by ring opening polymerization. Both NMR and FTIR analyses demonstrated the PLLA chains have been grafted on to the P(NIPAM--HEMA) backbone. These graft copolymers revealed the cloud point temperature higher than that of PNIPAM homopolymer as determined by optical transmittance. The graft copolymers self-assembled into micelles with regularly spherical structures as observed by atomic force microscopy (AFM). The properties of these graft copolymers are interesting for the drug delivery system.
Ti)0
Yoneda, Yasuhiro; Saito, Hiroyuki; Yoshii, Kenji; Nishida, Takashi*; Hayakawa, Hironori*; Ikeda, Naoshi*
Key Engineering Materials, 421-422, p.30 - 33, 2010/00
Polycrystalline Bi(MgTi)O samples were prepared under high pressure. A mixed powder of Bi
O, TiO and MgO with a prescribed ratio was packed into platinum cell and was heated a cubic anvil-type apparatus at 6.5 GPa and 1000 
C. The obtained samples were characterized by powder X-ray diffraction measurements. Although some impurity peaks existed, the main peaks were perovskite peaks. The structure of Bi(MgTi)O is rhombohedral, as well as BiFeO. The D-E hysteresis loop was not saturated due to the impurities, but the possibility as ferroelectric can be expected enough.
O
ceramics from precursor polymers by radiation curingWach, R.; Sugimoto, Masaki; Yoshikawa, Masahito
Key Engineering Materials, 317-318, p.573 - 576, 2006/08
no abstracts in English
Tanaka, Hirohisa*; Tan, Isao*; Uenishi, Mari*; Taniguchi, Masashi*; Nishihata, Yasuo; Mizuki, Junichiro
Key Engineering Materials, 317-318, p.827 - 832, 2006/08
no abstracts in English
Tan, Isao*; Taniguchi, Masashi*; Tanaka, Hirohisa*; Uenishi, Mari*; Kajita, Nobuhiko*; Nishihata, Yasuo; Mizuki, Junichiro; Niihara, Koichi*
Key Engineering Materials, 317-318, p.833 - 836, 2006/08
no abstracts in English
Shibata, Taiju; Sumita, Junya; Baba, Shinichi; Yamaji, Masatoshi*; Ishihara, Masahiro; Iyoku, Tatsuo; Tsuji, Nobumasa*
Key Engineering Materials, 297-300, p.728 - 733, 2005/11
no abstracts in English
Ishihara, Masahiro; Yamaji, Masatoshi*; Baba, Shinichi; Hanawa, Satoshi
Key Engineering Materials, 297-300, p.201 - 206, 2005/11
no abstracts in English
Hanawa, Satoshi; Ishihara, Masahiro; Motohashi, Yoshinobu*
Key Engineering Materials, 297-300, p.40 - 46, 2005/11
no abstracts in English
Sumita, Junya; Shibata, Taiju; Ishihara, Masahiro; Iyoku, Tatsuo; Tsuji, Nobumasa*
Key Engineering Materials, 297-300, p.1698 - 1703, 2005/11
no abstracts in English
Sumita, Junya; Shibata, Taiju; Ishihara, Masahiro; Iyoku, Tatsuo; Tsuji, Nobumasa*
Key Engineering Materials, 297-300, p.143 - 147, 2005/11
no abstracts in English
Sugimoto, Masaki; Idesaki, Akira; Tanaka, Shigeru; Okamura, Kiyohito*
Key Engineering Materials, 247, p.133 - 136, 2003/00
no abstracts in English
