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343 results on '"Kaito, T."'

31. Research and Development of Oxide Dispersion Strengthened Ferritic Steels for Sodium Cooled Fast Breeder Reactor Fuels.

Author

Inoue, M., Kaito, T., and Ohtsuka, S.

Abstract

Oxide dispersion strengthened (ODS) ferritic steels is eligible for fuel pin cladding tubes to endure heavy displacement damages to 250 dpa at high temperatures up to 973 K in commercialized sodium cooled fast breeder reactor cores. Japan Atomic Energy Agency has been developing ODS steels since 1987. For ODS steels, powder metallurgy process including mechanical alloying and hot consolidation produces highly stable and fine oxide dispersoids in matrix, and provides excellent dispersion hardening. Although cold rolling process in tube manufacturing tends to cause anisotropic grain growth, alpha to gamma phase transformation for the 9Cr-ODS steel and recrystallization for the 12Cr-ODS steel can modify grain morphology and improve creep rupture strength under internal pressure. Mechanical properties of the tubes have been extensively tested in air and stagnant sodium environments to establish Material Strength Standard for fuel pin mechanical design. Also, hundreds of specimens have been irradiated in the experimental fast reactor JOYO to investtigate irradiation effect on dimensional stability and mechanical properties. Pressurized resistance welding technology has been applied to join a tube and end plugs. Both 9Cr- and 12Cr-ODS steel tubes were assembled into fuel pins, and have been irradiated since 2003 under the collaborative program in the BOR-60 in Russia. [ABSTRACT FROM AUTHOR]

Published
2008
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32. Tungsten Deposited Scanning Probe Microscope Tips for Critical Dimension Measurement.

Author

Yasutake, M., Kaito, T., and Wakiyama, S.

Subjects
*SCANNING probe microscopy, *TUNGSTEN, *ION beam lithography, *SCIENTIFIC apparatus & instruments, *MEASUREMENT, *EQUIPMENT & supplies
Abstract

We fabricated a robust and high aspect ratio tungsten deposited tip (TD tip) using a Focused Ion Beam (FIB). This tip was well controlled during fabrication. Tip diameter is uniform at around 90nm and its growing length is proportional to the irradiation time of the ion beam. Tip shape is a cylindrical pillar and aspect ratio (length/diameter) is greater than 10. Growing angle of the tip is identical to the incident angle of the ion beam. Critical dimension (CD) measurement of shallow trench isolation (STI) was performed using this tip. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2003
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33. Effect of biological agents on cervical spine lesions in rheumatoid arthritis.

Author

Kaito T, Hosono N, Ohshima S, Ohwaki H, Takenaka S, Fujiwara H, Makino T, Yonenobu K, Kaito, Takashi, Hosono, Noboru, Ohshima, Shirou, Ohwaki, Hajime, Takenaka, Shota, Fujiwara, Hiroyasu, Makino, Takahiro, and Yonenobu, Kazuo

Abstract

Study Design: A retrospective cohort analysis. Objective: To determine the effect of biological agents (BAs) on the development and progression of cervical spine lesions and identify predictors of lesion progression. Summary Of Background Data: The introduction of BAs has facilitated advances in the treatment of rheumatoid arthritis (RA). BAs reduce disease activity and limit structural joint damage. However, the effect of BAs on cervical spine lesions remains unclear. Methods: Thirty-eight subjects who received more than 2 years of continuous BA treatment were enrolled. The mean x-ray interval was 4.4 years. RA activity was evaluated by disease activity score (DAS)-C reactive protein (CRP) and matrix metalloproteinase (MMP)-3. Radiographical definitions of cervical lesions were atlanto-dental interval (ADI) more than 3 mm for atlanto-axial subluxation (AAS), Ranawat value less than 13 mm for vertical subluxation (VS), and anterior or posterior listhesis more than 2 mm for subaxial subluxation (SS). Definitions of radiographical progression were an increase of ADI more than 2 mm for AAS, a decrease of both Ranawat and Redlund-Johnell values more than 2 mm for VS, and an increase of listhesis more than 2 mm for SS. Results: RA activity responded dramatically to BA therapy (DAS-CRP from 4.3 to 2.3, P < 0.01; MMP-3 from 207.9 ng/mL to 105.6 ng/mL, P < 0.01). Baseline radiographical evaluation showed no pre-existing cervical spine lesions in 12 cases, AAS in 15 cases, and VS in 11 cases. Radiological progression was found in 1 (8%) patient in the no lesion group, 12 patients (80%) in the AAS group, and 9 patients (80%) in the VS group. The incidence of progression was significantly lower in the no lesion group compared with the other groups. Multivariate regression analysis showed that the presence of pre-existing cervical lesions was the single greatest predictor of progression. Conclusion: BAs prevented the development of de novo cervical spine lesions in patients with RA, but failed to inhibit progression of pre-existing RA lesions. [ABSTRACT FROM AUTHOR]

Published
2012
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37. Effects of aluminum on high-temperature strength of 9Cr–ODS steel

Author

Ohtsuka, S., Kaito, T., Inoue, M., Asayama, T., Kim, S.W., Ukai, S., Narita, T., and Sakasegawa, H.

Subjects
*STRENGTH of materials, *CHROMIUM alloys, *ALUMINUM, *HIGH temperatures, *DISPERSION strengthening, *COMPUTER simulation, *EXTRUSION process, *AUSTENITE
Abstract

Abstract: This paper discusses the effects of small amount of Al contamination (<0.1wt%) on high-temperature strength and microstructure of the 9Cr–ODS steel. Increasing Al concentration degraded the ultimate tensile strength as well as the 0.2% proof stress at 973K and 1073K accompanied by decreasing fraction of the elongated grain, i.e., residual-α ferrite acting as reinforcement phase. The decrease of residual-α ferrite proportion provided by increasing Al is contrary to general behavior of conventional steels. Computer simulation on ferrite to austenite phase transformation suggested that the fine oxide dispersion in the elongated ferrite could be attributable to the preferential partitioning of Ti and W in ferrite than in austenite at hot-extrusion process. [Copyright &y& Elsevier]

Published
2009
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38. In-pile creep rupture properties of ODS ferritic steel claddings

Author

Kaito, T., Ohtsuka, S., Inoue, M., Asayama, T., Uwaba, T., Mizuta, S., Ukai, S., Furukawa, T., Ito, C., Kagota, E., Kitamura, R., Aoyama, T., and Inoue, T.

Subjects
*CREEP (Materials), *DISPERSION strengthening, *FERRITIC steel, *METAL cladding, *TEMPERATURE effect, *GAMMA ray spectrometry
Abstract

Abstract: In order to examine irradiation effect on creep rupture strength of Oxide Dispersion Strengthened (ODS) steel claddings, the in-pile creep rupture test was conducted using Material Testing Rig with Temperature Control (MARICO)-2 in the experimental fast reactor JOYO. Fourteen creep rupture events were successfully detected by the temperature change in each capsule and the gamma-ray spectrometry of the cover gas. Time to creep ruptures of six ODS steel specimens were identified by means of Laser Resonance Ionization Mass Spectrometry (RIMS), and no irradiation effect on creep rupture strength was confirmed within the irradiation condition in the MARICO-2 test. [Copyright &y& Elsevier]

Published
2009
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46. List of contributors

Author

Aitkaliyeva, A., Allen, T., Asayama, T., Bai, X.M., Balbaud, F., Blat-Yrieix, M., Buckthorpe, D., Cabet, C., Dalle, F., David, P., de Carlan, Y., Dubiez-Le Goff, S., Dubuisson, Ph., Fazio, C., Gosset, D., Guzonas, D., Hall, G.N., He, L., Henry, J., Ignatiev, V., Jones, A.N., Kaito, T., Le Flem, M., Malaplate, J., Maloy, S.A., Marsden, B.J., Miller, B., Mummery, P.M., Muroga, T., Novotny, R., Ohtsuka, S., Park, J.Y., Penttilä, S., Ribis, J., Rouillard, F., Sauzay, M., Séran, J.-L., Surenkov, A., Treifi, M., Ukai, S., Wen, H., and Zinkle, S.J.

Published
2017
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