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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*; 小山 貴久*; 山崎 裕史*; 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：7 パーセンタイル：74.72(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.
山下 正人*; 小西 啓之; 高橋 正光; 水木 純一郎; 内田 仁*
Materials Science Research International, Special Technical Publication, 1, p.398 - 401, 2001/05
耐候性低合金鋼のさび層は大気腐食に対して強い保護機能を有する。鉄鋼のさび層を制御するには、さびの詳細な構造及びそれと防食性との関係を知ることが重要である。特にさび層に含まれる合金元素の原子位置は直接さび層の構造と特性を制御していると考えられる。本研究ではFe-Cr合金蒸着膜を硫酸水溶液液膜下で腐食させて得られる生成物について、その局所構造を調べた。メスバウアー分光法及び放射光斜入射X線回折法の結果は、腐食生成物が
-FeOOHと超微細ゲーサイト(
-FeOOH)とから成ることを示している。EXAFS実験より少なくともゲーサイト中にはFe-Cr合金からのCrが存在することがわかった。Feサイトを置換したCrがゲーサイトの結晶粒径を微細化する一方、Fe-O-OH八面対の間に侵入して存在するCrがさび層にイオン選択性を与え、保護機能を増加させていると考えられる。
宗像 信生*; 檜枝 光太郎*; 宇佐美 徳子*; 横谷 明徳; 小林 克己*
Radiat. Res., 131(1), p.72 - 80, 1992/07
被引用回数：16 パーセンタイル：57.62(Biology)0.1
0.6nmの単色シンクロトロン軟X線と枯草菌に真空中で照射し、致死作用を測定した。得られた線量効果曲線より致死作用断面積のスペクトルを得た。その結果、0.31nmと0.58nmに、ピークがあることがわかった。それぞれカルシウムとリンのK殻吸収端に相当するエネルギーであることから、細胞内のカルシウム及びリンが特異的に光吸収することにより、細胞の致死効率が高まることが推測された。リンは、細胞中DNAの構成元素であることから、リンの内殻吸収による特異的なDNA損傷の生成が考えられる。一方カルシウムはDNA中には含まれておらず、細胞質中のカルシウムの光吸収による致死作用機構の解明が今後待たれる。現在、光照射された細胞中DNAを細胞外に抽出し、突然変異を引きおこす遺伝子の変化を分子レベルで解析中である。
菅谷 雄基*; 藤井 健太郎; 横谷 明徳
no journal, ,
We have tried oxygen selective damage induction in DNA by tuning soft X-ray energy. Thin DNA films of closed circular plasmid (pUC18) without any additives were prepared and tested the stability of DNA in the film by observing conformational changes using gel electrophoresis. We performed soft X-ray irradiation to the films at BL23SU in SPring-8. The yields of strand breaks, base lesions, as well as AP sites produced by irradiation of several soft X-ray energies around oxygen K-shell ionization threshold. The yields of base lesions and AP sites are determined by post-irradiation-treatment of the DNA with enzymatic probes. The yield of AP site, as well as those of other lesions, shows a minimum at the resonance excitation energy (538 eV) absorbed by the sample with a highest probability. The results indicate that the resonance excitation of 1s electron does not rather enhance the DNA damage induction.
CuH
齋藤 寛之; 高木 成幸*; 遠藤 成輝*; 町田 晃彦; 青木 勝敏; 折茂 慎一*; 片山 芳則
no journal, ,
Aluminum-based interstitial hydride has not been reported so far, whereas complex aluminum hydrides have been synthesized and investigated. In the present study, we demonstrate the formation of AlCuH interstitial hydride by a hydrogenation reaction of AlCu alloy under high pressure and high temperature.
