著者
アギアル デ ソウザ ヴィニシウス 渡邊 育夢 柳田 明
出版者
一般社団法人 日本機械学会
雑誌
M&M材料力学カンファレンス
巻号頁・発行日
vol.2013, pp._OS0805-1_-_OS0805-3_, 2013

The purpose of this study is to improve and extend a method to estimate the friction coefficient in equal channel angular extrusion (ECAE) including cases with back pressure. Employing three dimensional finite element analysis (FEA) and Coulomb friction model with truncated shear stress, the relationship between the friction coefficient and the reaction force is investigated in ECAE with back pressure. Additionally, the deformation state of the billet after ECAE and the pressing load are compared between the experiment and the simulation results with the same friction coefficient for validation of the numerical model.
著者
柳田 明進 池田 榮史 脇谷 草一郎 松田 和貴 髙妻 洋成
出版者
日本銅学会
雑誌
銅と銅合金 (ISSN:13477234)
巻号頁・発行日
vol.59, no.1, pp.167-172, 2020

<p>To evaluate the corrosion mechanism of copper artifacts and to propose the effective reburial method that suppresses the corrosion of copper artifacts at the underwater archaeological site, corrosion tests were carried out at the Takashima underwater archaeological site using copper and copper with wood. The results of the corrosion test specified that corrosion proceeded by the effect of H<sub>2</sub>S or HS<sup>–</sup>even in dissolved oxygen (DO)–depleted conditions at the underwater archaeological site. In the case of the copper with wood, the corrosion rate dramatically increased in comparison with the copper samples due to the effects of wood as nutrient salt for sulfate–reducing bacteria. These results indicate that it is necessary to control the mass transfer of chemical species like H<sub>2</sub>S, HS<sup>–</sup>, and Cu<sup>+</sup> for suppression of corrosion of copper artifacts at underwater in addition to DO–depleted conditions. The results of the study also suggest that covering copper artifacts using porous media like sandy soil is an effective means for the preservation of them.</p>
著者
柳田 明進 池田 榮史 脇谷 草一郎 松田 和貴 髙妻 洋成
出版者
日本銅学会
雑誌
銅と銅合金 (ISSN:13477234)
巻号頁・発行日
vol.59, no.1, pp.167-172, 2020 (Released:2020-11-19)
参考文献数
10

To evaluate the corrosion mechanism of copper artifacts and to propose the effective reburial method that suppresses the corrosion of copper artifacts at the underwater archaeological site, corrosion tests were carried out at the Takashima underwater archaeological site using copper and copper with wood. The results of the corrosion test specified that corrosion proceeded by the effect of H2S or HS–even in dissolved oxygen (DO)–depleted conditions at the underwater archaeological site. In the case of the copper with wood, the corrosion rate dramatically increased in comparison with the copper samples due to the effects of wood as nutrient salt for sulfate–reducing bacteria. These results indicate that it is necessary to control the mass transfer of chemical species like H2S, HS–, and Cu+ for suppression of corrosion of copper artifacts at underwater in addition to DO–depleted conditions. The results of the study also suggest that covering copper artifacts using porous media like sandy soil is an effective means for the preservation of them.