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17. On-line monitoring of oxygen potential and structure of oxide layer in liquid metals by electrochemical methods

Author

Matsumura Yoshihito, Takahashi Minoru, Muroga Takeo, Sagara Akio, Kondo Masatoshi, Hishinuma Yoshimitsu, Adhi Pribadi Mumpuni, Suzuki Narumi, and Tanaka Teruya

Subjects
Chemical substance, Materials science, Oxide, Nanotechnology, Electrochemistry, Oxygen potential, Line (electrical engineering), law.invention, chemistry.chemical_compound, Chemical engineering, Magazine, chemistry, law, Science, technology and society, Layer (electronics)
Published
2017
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18. In-Situ Evaluation of Functional Layer by Electrochemical Impedance Spectroscopy

Author

Suzuki, Narumi, Matsumura, Yoshihito, and Kondo, Masatoshi

Subjects
コーティング, 核融合炉, 電気化学インピーダンス, 腐食
Abstract

Online evaluation of the electrical properties of oxide layers was studied for the development of liquid breeder blanket of fusion reactors in this paper. The electrochemical impedance spectroscopy was applied for the layers of zirconium oxide formed at 773 K on the substrate of zirconium metal in air or pure oxygen gas atmospheres at the atmospheric pressure. The durations of the oxidation were 360, 900, and 1800 ks. The electrochemical impedance spectra for the oxidized surface of the Zr metals were measured at 773 K using the gold electrode fabricated on the sample surface by a sputtering method. The capacitance, the resistance, and the constant-phase-element parameter p (CPE-p) were evaluated from the measured spectrum of the samples by the comparison with the results of the model simulation for the layer using ZView code. Then, it was found that the thickness of the oxide layers estimated from the electrostatic capacitance was close to that from weight gain of the sample by its oxidation. It was indicated that the behavior of CPE-p depends on the atmospheres in the oxidation process. This result indicated that the composition and the structure of the oxide layers were not uniform and this behavior was influenced by the atmosphere for the oxidation procedure.

Published
2016

19. In-Situ Evaluation of Functional Layer Based on Impedance Behavior

Author

Suzuki, Narumi, Matsumura, Yoshihito, and Kondo, Masatoshi

Subjects
ブランケット, 核融合炉, 電気化学インピーダンス, 機能性被覆, 腐食
Abstract

The characterization of Zr oxide layer formed in Ar and O2 gas mixture at 973 K on the surface of Zr metal was characterized by electrochemical impedance spectroscopy (EIS). The increase of the layer thickness and the formation of the horizontal crack in the layer were evaluated insitu using EIS. The thickness of the Zr oxide layer estimated by EIS agreed well with that by EPMA analysis. It was found that the time constant t of the Zr oxide layer obtained by the EIS increased with the oxidation time. This trend indicated the growth of horizontal crack. The constant phase element (CPE) parameter p was obtained from the results of EIS. The change of p indicated that the Zr oxide layer has the gradient of the chemical composition in its thickness direction. The single horizontal crack and compositionally gradient in the oxide layer was modeled as they electrically functioned in the equivalent circuits. The simulation results indicated that the EIS method can be used as the insitu monitor the gradient of the chemical composition and the crack formation in the oxide layer.

Published
2016

46. Drop-tube法による超磁歪材料TbFe2の作製について

Author

Kano, Shinya, Nakajima, Toshihiro, Kudo, Mitsugu, Matsumura, Yoshihito, 鹿野 真也, 中島 俊浩, 工藤 貢, 松村 義人, Kano, Shinya, Nakajima, Toshihiro, Kudo, Mitsugu, Matsumura, Yoshihito, 鹿野 真也, 中島 俊浩, 工藤 貢, and 松村 義人

Abstract

The giant magnetostrictive materials (GMM) such as TbFe2, SmFe2 and Terfenol-D have been widely studied because of high magnetostrictions at room temperature. An improvement of the magnetostrictive properties may induce wider application fields of electric-mechanical energy conversion. In this study, magnetic properties of TbFe2 alloys solidified under microgravity (micro G) conditions obtained by drop tube systems were investigated. The magnetic characteristics of TbFe2 giant magnetostrictive alloy were found to be influenced by the solidification rate.

Published
2015

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