2 0 0 0 OA 高濃度硫酸中におけるステンレス鋼の腐食機構解析
- 著者
- 松橋 亮 安保 秀雄 阿部 征三郎 紀平 寛
- 出版者
- Japan Society of Corrosion Engineering
- 雑誌
- 防食技術 (ISSN:00109355)
- 巻号頁・発行日
- vol.36, no.9, pp.578-585, 1987-09-15 (Released:2009-10-30)
- 参考文献数
- 7
- 被引用文献数
- 5 8
The mechanism of corrosion of stainless steels in highly concentrated sulfuric acid was studied by the electrochemical method and surface analysis as EPMA and Laser-Raman Spectroscopy. Cyclic potential changes occured in this system about between -0.2V (SCE) (active state) and 0.2V (SCE) (passive state). The anodic reaction was determined as the metal dissolution in both the active and the passive state. The cathodic reaction in the active state near -0.2V (SCE) was mainly dominated by the reduction of hydrogen ion which was clearly indicated by the evolution of hydrogen gas. On the other hand, catholic reaction at the passive state about 0.2V (SCE) was determined as the reduction of molecular sulfuric acid resulting in the formation of sulfur and water. By the analysis of EPMA, precipitated sulfur was found on the specimen surface polarized at 0.2V (SCE) potentiostatically. The in-situ observation of corroding surface by Laser-Raman spectroscopy indicated the formation of precipitated sulfur on the metal surface at the corrosion potential. Cyclic changes in corrosion potentials were considered due to the following mechanisms; dissolved metal ion at the active state formed metal sulfate films on the metal surface, leading the corrosion potential to the passive state. Inversely at the passive state, water as the product of the cathodic reaction accelerated the dissolution of the metal sulfate film to move the corrosion potential to the active state.
1 0 0 0 OA 自然海水中に浸漬したステンレス鋼の電位貴化メカニズムの検討
- 著者
- 伊藤 公夫 松橋 亮 加藤 敏朗 三木 理 紀平 寛
- 出版者
- Japan Society of Corrosion Engineering
- 雑誌
- Zairyo-to-Kankyo (ISSN:09170480)
- 巻号頁・発行日
- vol.50, no.6, pp.285-291, 2001-06-15 (Released:2011-12-15)
- 参考文献数
- 20
- 被引用文献数
- 6 5
Potential ennoblement for stainless steel in natural seawater was analyzed. Open circuit potentials (OCPs) of platinum, gold, palladium, chromium, titanium and nickel ennobled in natural seawater as well as stainless steel, SUS 304 (18Cr-8Ni). Potential ennoblement is not a specific event to only stainless steel. Marine biofilm clearly caused potential ennoblement. Cathodic polarization curves for the ennobled stainless steel elucidated that there were two distinct reduction current increases. One is the limited diffusion current of dissolved oxygen reduction below -500mV vs. Ag/AgCl (KClsat). The other reduction current around 0mV vs. Ag/AgCl (KClsat) was considered to be hydrogen peroxide reduction current in acidic condition. Synergistic effect of hydrogen peroxide and low pH in artificial seawater carried out high OCP of stainless steel like that in natural seawater. Therefore, we concluded that synergistic effect of hydrogen peroxide production and low pH by marine microorganisms is possible cause for potential ennoblement in natural seawater.
1 0 0 0 OA 硫酸水溶液中におけるステンレス鋼の全面腐食速度に及ぼす合金元素濃度の影響
- 著者
- 松橋 亮 伊藤 叡 佐藤 栄次
- 出版者
- Japan Society of Corrosion Engineering
- 雑誌
- Zairyo-to-Kankyo (ISSN:09170480)
- 巻号頁・発行日
- vol.40, no.11, pp.747-753, 1991-11-15 (Released:2009-11-25)
- 参考文献数
- 6
- 被引用文献数
- 7 8
To clarify the physical meaning of general corrosion resistance index (GI) obtained through the alloy contents on general corrosion rate of stainless steels in sulfuric acid solution, the study of the effect of alloy contents, immersion time and temperature on the general corrosion rate was carried out in 10.2mol·kg-1 sulfuric acid solution. It was assured that dependence of alloy contents on corrosion rate of stainless steels was ascribed to the apparent activation energy obtained by Arrhenius plot, and from the thermodynamical consideration of GI value, GI was expressed as a function of alloy contents through the change of apparent activation energy due to corrosion reaction.