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Yoshida, Koji*; Inoue, Takuya*; Torigoe, Motokatsu*; Yamada, Takeshi*; Shibata, Kaoru; Yamaguchi, Toshio*
Journal of Chemical Physics, 149(12), p.124502_1 - 124502_10, 2018/09
Times Cited Count：4 Percentile：17.83(Chemistry, Physical)Differential scanning calorimetry, X-ray diffraction, and quasi-elastic neutron scattering (QENS) measurements of aqueous glycine solutions confined in mesoporous silica (MCM-41) were performed at different glycine concentrations, pH, and loading ratio (= mass of glycine solution / mass of dry MCM-41) in the temperature range from 305 to 180 K to discuss the confinement effect on the thermal behavior, the structure, and the dynamic properties of the solutions.
Kubo, Shinji; Futakawa, Masatoshi; Ioka, Ikuo; Onuki, Kaoru; Yamaguchi, Akihisa*
International Journal of Hydrogen Energy, 38(16), p.6577 - 6585, 2013/05
Times Cited Count：23 Percentile：52.08(Chemistry, Physical)Very harsh environments exist in the iodine-sulfur process for hydrogen production. Structural materials for sulfuric acid vaporizers and concentrators are exposed to high-temperature corrosive environments. Immersion tests were carried out to evaluate the corrosion resistance of ceramics and to evaluate corrosion-resistant metals exposed to environments of aqueous sulfuric acids at temperatures of 320, 380, and 460
C, and pressure of 2 MPa. The aqueous sulfuric acid concentrations for the temperatures were 75, 85, and 95 wt%, respectively. Ceramic specimens of silicon carbides (SiC), silicon impregnated silicon carbides (Si-SiC), and silicon nitrides (Si
N
) showed excellent corrosion resistance from weight loss measurements after exposure to 75, 85, and 95 wt% sulfuric acid. High-silicon irons with silicon content of 20 wt% showed a fair measure of corrosion resistance. However, evidence of crack formation was detected via microscopy. Silicon enriched steels severely suffered from uniform corrosion with a corrosion rate in 95 wt% sulfuric acid of approximately 1 gm
h. Among the tested materials, the ceramics SiC, Si-SiC, and SiN were found to be suitable candidates for structural materials in direct contact with the considered environments.
Kubo, Shinji; Futakawa, Masatoshi; Onuki, Kaoru; Yamaguchi, Akihisa*
Corrosion Engineering, 62(3), p.104 - 111, 2013/03
The iodine-sulfur thermochemical cycle for hydrogen production takes place in very harsh environments. Structural metallic materials for the hydrogen iodide decomposition are exposed in a high temperature halogen corrosion and hydrogen embrittlement environment. To evaluate adaptability of the materials, the corrosion rates and mechanical properties (the yield strength, the tensile strength, and the elongation) were measured. Prepared test specimens were exposed to ambient gas consisting of HI, I
, HO, and H (molar fraction of 1:1:6:0.16) at 450C for 1000 h at atmospheric pressure. After the exposure, the corrosion rates were obtained by the weight loss of each specimen. Nickel-based alloys (Hastelloy C-276, MAT21, Inconel 625) exhibited appropriate corrosion resistance (
0.03 g m h
. In addition, no degradations of the mechanical properties for the MAT21 and the Inconel 625 were observed. The specimens of tantalum and titanium showed hydrogen embrittlement; the specimens of zirconium and niobium exhibited poor corrosion resistance. The specimens of molybdenum (Mo) exhibited good corrosion resistance; however, the strength degradation of Mo is cause for concern. As the results show, the nickel-based alloys are well suited for the structural materials within this environment from the viewpoint of the corrosion resistance. MAT21 among them is an outstanding material with an eye to its corrosion resistance and mechanical properties.
Kubo, Shinji; Futakawa, Masatoshi; Onuki, Kaoru; Yamaguchi, Akihisa*
Zairyo To Kankyo, 62(3), p.122 - 128, 2013/03
The iodine-sulfur thermochemical cycle for hydrogen production takes place in very harsh environments. Structural metallic materials for the hydrogen-iodide decomposition are exposed in the high-temperature halogen corrosion and the hydrogen embrittlement environment. To evaluate adaptability of the materials, corrosion rates and mechanical properties (the yield strength, the tensile strength, and the elongation) were measured. Prepared test specimens were exposed to ambient gas consisting of HI, I
, HO and H (molarfraction, 1:1:6:0.16) at 450C for 1000 hours at the atmospheric pressure. After the exposure, the corrosion rates were obtained by the weight loss of each specimen. Nickel-based alloys (Hastelly C-276, MAT21, Inconel 625) exhibited appropriate corrosion resistance ( 0.03 g m h). In addition, no degradations of the mechanical properties for the MAT21 and the Inconel 625 were observed. The specimens of tantalum and titanium showed the hydrogen embrittlement; the specimens of zirconium and niobium exhibited poor corrosion resistance. The specimens of molybdenum (Mo) exhibited good corrosion resistance, however strength degradation of Mo is causing concern. As the results, the nickel-based alloys are well suited for the structural materials within this environment from the viewpoint of the corrosion resistance. MAT21 among them is the outstanding material with an eye to its corrosion resistance and mechanical properties.
Yamaguchi, Daisuke; Mayama, Hiroyuki*; Koizumi, Satoshi; Tsujii, Kaoru*; Hashimoto, Takeji
European Physical Journal B, 63(2), p.153 - 163, 2008/05
The fractal dimensions of specific porous silica materials were investigated by a wide-q observation using ultra-small-angle neutron scattering technique. In order to control the fractal dimension of porous silica material, flaky particles made of alkylletene dimer (AKD) were employed as moulds and silica matrix was formed by sol-gel process. After the solidification of the silica matrix, the original AKD moulds were completely burnt away at high temperature (ca. 930K) and became pores having a particular fractal dimension. The fractal dimension of the pores was changeable by the compression of the AKD mould at different ratio during the sample preparation. We found that the fractal structure obtained in this study was distinctly different from those of ordinary silica aerogels.
Yamaguchi, Daisuke; Mayama, Hiroyuki*; Koizumi, Satoshi; Tsujii, Kaoru*; Hashimoto, Takeji
European Physical Journal B, 63(2), p.153 - 163, 2008/05
Times Cited Count：12 Percentile：48.4(Physics, Condensed Matter)The unique structure of a set of self-assembled porous silica materials was characterized through a combined small-angle scattering (CSAS) method using small- and ultra-small angle neutron scattering as well as small-angle X-ray scattering. The porous silica specimens investigated were prepared by a sol-gel method under the presence of alkylketene dimer (AKD) template particles and through calcination, which leads to the development of porous silica having a mass-fractal structure over length scales from 10nm to 10
m. Furthermore, the specimens posses a hierarchical structure, which consist of a fractal porous structure, and also contain primary silica particles less than 10 nm in size, which form a continuous silica matrix. To characterize these complex structures, observation over a broad range of length scales is indispensable. We propose a CSAS technique that serves this purpose well.
Tanaka, Nobuyuki; Onuki, Kaoru; Shimizu, Saburo; Yamaguchi, Akihisa*
Zairyo To Kankyo, 55(7), p.320 - 324, 2006/07
Exposure tests of candidate materials were carried out up to 1000 hr in the sulfuric acid environments of thermochemical hydrogen production IS process, focusing on the corrosion of welded portion and of crevice area. In the gas phase sulfuric acid decomposition condition at 850C, welded samples of Alloy 800 and of Alloy 600 showed the same good corrosion resistance as the bare materials. Also, in the boiling condition of 95wt% sulfuric acid solution, negligible corrosion was observed in crevice corrosion test sample of SiC.
Kubo, Shinji; Futakawa, Masatoshi; Tanaka, Nobuyuki; Iwatsuki, Jin; Yamaguchi, Akihisa*; Tsukada, Ryuji*; Onuki, Kaoru
Proceedings of 2006 International Congress on Advances in Nuclear Power Plants (ICAPP '06) (CD-ROM), 6 Pages, 2006/06
no abstracts in English
Tsuzuki, Kazuhiro*; Kimura, Haruyuki; Kusama, Yoshinori; Sato, Masayasu; Kawashima, Hisato; Kamiya, Kensaku; Shinohara, Koji; Ogawa, Hiroaki; Uehara, Kazuya; Kurita, Genichi; et al.
Fusion Science and Technology, 49(2), p.197 - 208, 2006/02
Times Cited Count：11 Percentile：60.27(Nuclear Science & Technology)no abstracts in English
Ogawa, Hiroaki; Yamauchi, Yuji*; Tsuzuki, Kazuhiro; Kawashima, Hisato; Sato, Masayasu; Shinohara, Koji; Kamiya, Kensaku; Kasai, Satoshi; Kusama, Yoshinori; Yamaguchi, Kaoru*; et al.
Journal of Nuclear Materials, 329-333(Part1), p.678 - 682, 2004/08
Times Cited Count：4 Percentile：29.26(Materials Science, Multidisciplinary)no abstracts in English
Futakawa, Masatoshi; Kubo, Shinji; Wakui, Takashi*; Onuki, Kaoru; Shimizu, Saburo; Yamaguchi, Akihisa*
Jikken Rikigaku, 3(2), p.109 - 114, 2003/06
Micro-indentation technique was applied to evaluate the mechanical properties of corroded surface layers of Ni-alloy, 316SS, Ti and Ta, which were exposed into the corrosive gaseous environment consisting of HI+I+HO+H. The corrosion condition was chosen so as to simulate one of the environments in the thermochemical hydrogen production, IS process, where the degradation due to the corrosion attack by HI and the hydrogen embrittlement is a key issue from the viewpoint of material integrity. The micro-indentation tests using a spherical indenter and the inverse analysis with Kalman filter were performed to quantitatively estimate material constants of corroded surface layer. Ni-alloy exhibited good corrosion resistance and Ta was remarkably influenced by the hydrogen embrittlement.
Yamaguchi, Kaoru*; Yamauchi, Yuji*; Hirohata, Yuko*; Hino, Tomoaki*; Tsuzuki, Kazuhiro
Shinku, 46(5), p.449 - 452, 2003/05
no abstracts in English
Onda, Kaoru*; Yamaguchi, Katsuhisa
PNC TN952 83-08, 258 Pages, 1983/12
A Data processing program SISC0, which has capabilities of checking the information of experimental data measurements with little labor and of analyzing the data conveniently using the checked information, was developed to conduct the accurate data processing of the test results of low-flow and low-heat-flux sodium boiling runs and the other runs obtained from the experiments carried out with the Transient Sodium Boiling and Fuel Failure Propagation Test facility. It is devised to use, to the full extent, the utility libraries of the Interactive Data Analysis System AXEL installed in the FACOM M-190/200 computer system at the O-arai Engineering Center. The data managements of the SISCO code are composed of two sub-systems : one is the BSISCO having functions of creating or updating the data bases with batch jobs to prepare for subsequent data analyses, and another is the ISISCO which is in charge of analyzing the data with TSS job under the support of AXEL system. In onder to respond to various kinds of requirements from analysts, seven option routines and thirteen command-macro procedures are available in respective sub-systems. The SISCO code supports following two types of data handling jobs : (i)data calibration job ; to fix and service the information of measurements, which is to be compiled into a preservation data file for the data reproduction, by the statistical analyses of calibration data and the displays of the results, (ii)data analysis job ; to obtain the graphic outputs of the multi-data analyses applied to the specified preservation data files. The data analysis of the SISCO code is so designed that one can use a certain command-macro as a stand-alone utility program appliciable to any test data comprehensively. It is possible to yield (a) summary traces of the test results containing the sub-frames of time series data plots of key signals in one figure, (b) multi-traces of the axial temperatures at required transient times, (c) analytical ...
Kambara, Toyozo; Uno, Hidero; Shoda, Katsuhiko; Hirata, Yutaka; Shoji, Tsutomu; Kohayakawa, Toru; Takayanagi, Hiroshi; Fujimura, Tsutomu; Morita, Morito; Ichihara, Masahiro; et al.
JAERI 1045, 11 Pages, 1963/03
no abstracts in English
Yamaguchi, Daisuke; Miyamoto, Nobuyoshi; Koizumi, Satoshi; Nakato, Teruyuki*; Mayama, Hiroyuki*; Tsujii, Kaoru*; Hashimoto, Takeji
no journal, ,
no abstracts in English
Yamaguchi, Daisuke; Miyamoto, Nobuyoshi*; Koizumi, Satoshi; Hashimoto, Takeji; Nakato, Teruyuki*; Mayama, Hiroyuki*; Tsujii, Kaoru*
no journal, ,
The hierarchical structures composed of two-dimensional particles were observed via ultra-small-angle scattering method. We have investigated two systems: (1) exfoliated KNb
O
nanosheet colloidal dispersion, (2) porous silica fabricated from alkylketene dimer template. Although the physical and chemical structures and properties are largely different in these two systems, a similar point to them is regarded as below. The thickness of the constituent particles is ranging from a few nanometers to several tens of nanometers. Various fractal-like power-law scattering were obtained in the ultra-small angle scattering region reflecting the difference in the self-assembly of the particles.
Yamaguchi, Daisuke; Mayama, Hiroyuki*; Koizumi, Satoshi; Tsujii, Kaoru*; Hashimoto, Takeji
no journal, ,
The fractal dimensions of specific porous silica materials were investigated by ultra-small-angle neutron scattering (USANS). In order to control the fractal dimension of porous silica material, flaky particles made of alkylletene dimer (AKD) were employed as moulds and silica matrix was formed by sol-gel process. The fractal dimension of the pores was changeable by the compression of the AKD mould at different ratio (hereafter designated as r) before the mould was filled with a TMOS solution, which turned to silica matrix, and three specimens, of which r = 1, 2, and 3, were prepared. USANS measurements brought us wide-q observations of the specimens, in the q scale of more than three orders of magnitude, and made it possible to accurate evaluation of the fractal dimension. The resultant mass-fractal dimensions for the specimens of r = 1, 2, and 3 were 2.98, 2.74, and 2.67, respectively.
Yamaguchi, Daisuke; Mayama, Hiroyuki*; Koizumi, Satoshi; Tsujii, Kaoru*; Hashimoto, Takeji
no journal, ,
In this study, the structure of the "novel" porous silica specimens prepared by sol-gel method with alkylketene dimer (AKD) template was characterized on the length scale from nanometers to tens of microns by small-angle neutron scattering measurements. AKD is a kind of wax and has been proven to form a fractal structure by recrystallization. Due to the AKD template, the porous silica product exhibited a distinct mass-fractal structure, which persists over the length scale ten times larger than that of conventional silica aerogel. While on the other hand, the mass fractal dimension is similar between the silica aerogels and the specimen investigated in this study, suggesting that the space symmetry is somewhat similar between those two systems.
