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伊與田 宗慶*; 松田 朋己*; 佐野 智一*; 茂田 正哉*; 菖蒲 敬久; 湯本 博勝*; Koyama, Takahisa*; Yamazaki, Hiroshi*; 仙波 泰徳*; 大橋 治彦*; et al.
Journal of Manufacturing Processes, 94, p.424 - 434, 2023/05
被引用回数：3 パーセンタイル：57.26(Engineering, Manufacturing)Aluminum alloys are increasingly being applied to automobile bodies to reduce the weight of automobiles. In joining steel materials and aluminum alloys using resistance spot welding (RSW), it is important to control the state of intermetallic compounds due to the temperature at the joining interface. In other words, in RSW of Fe/Al dissimilar materials, it is necessary to clarify the heating and cooling phenomena of the interface temperature during joining. Although the convection behavior of the molten aluminum alloy is thought to influence the temperature distribution at the joining interface, there are no studies that have directly observed this phenomenon. In this study, convection in molten zone of aluminum alloy during RSW of steel and aluminum alloy is discussed. Direct observations were attempted in order to clarify the convection behavior of the molten aluminum alloy in RSW of steel and aluminum alloy. The main feature of this experiment is that a real-scale test piece and an RSW apparatus used in actual production were used to observe convection during actual production. The observation experiments were conducted using synchrotron radiation X-ray at SPring-8. During welding, the specimens were irradiated with synchrotron radiation X-ray, and convection was observed from the behavior of tracer particles placed on the specimens. As a results, three types of convection were observed: radial outward convection from the center of the molten zone at the joining interface, convection from the edge of the molten zone toward its center, and weak circulating convection at the edge of the molten zone. And, small convection velocities were generated at the edge of the molten zone. Furthermore, the convection velocity inside the molten zone was calculated to be approximately 1.75 m/s. In addition, it was shown that there is a correlation between convection behavior and the shape of the molten zone.
坂本 哲夫*; 森田 真人*; 金成 啓太*; 富田 英生*; Sonnenschein, V.*; 齊藤 洸介*; 大橋 雅也*; 加藤 弘太郎*; 井口 哲夫*; 河合 利秀*; et al.
Analytical Sciences, 34(11), p.1265 - 1270, 2018/11
被引用回数：8 パーセンタイル：31.98(Chemistry, Analytical)Characterization of radionuclides in Fukushima is important to determine their origins and current state in the environment. Radionuclides exist as fine particles and are mixed with other constituents. A measurement method with both micro-imaging capability and highly selective element detection is necessary to analyze these particles. We developed such an imaging technique using a time-of-flight secondary ion mass spectrometry and wavelength tunable Ti:Sapphire lasers for resonance ionization of target elements without mass interference. This is called resonant laser ionization sputtered neutral mass spectrometry. The instrument has high lateral resolution and higher ionization selectivity using two-step resonance excitation of Cs with two lasers at different wavelengths. Optimization of the wavelength for resonance ionization using a Cs compound was performed, and a real environmental particle containing radioactive Cs was analyzed. Isotope images of three kinds of Cs were successfully obtained without interfere from Ba isotopes for the first time.
富田 英生*; 齊藤 洸介*; 大橋 雅也*; Sonnenschein, V.*; 加藤 弘太郎*; 鈴木 颯*; 井口 哲夫*; 森田 真人*; 坂本 哲夫*; 金成 啓太*; et al.
no journal, ,
微粒子試料中の同位体分析のために、レーザー共鳴イオン化-二次中性粒子質量分析法の開発を進めている。2色スキームを用いた安定Zr同位体イメージングを実証した。また、放射性同位体分析に向けた高繰り返し率Ti:Sapphireレーザーによる2色共鳴イオン化スキームの検討を行い、Zr/Mo微粒子の混合試料に集束イオンビームを照射し、生成された二次中性原子を2台のTi:Sapphireレーザーにより共鳴イオン化した。飛行時間型質量分析計にて質量数ごとに記録されたイオン計数と、イオンビームのスキャン位置を組み合わせ、マイクロイメージ(イオン計数マップ)を取得した。Zrを共鳴イオン化することで、
Moによる同重体干渉が抑制された92Zr同位体マイクロイメージ(視野30
m)が得られることが示された。
