2018 Fiscal Year Final Research Report
In-situ high-resolution observation and analysis of passive film of stainless steel in aqueous solution by atomic force microscopy
| Project/Area Number |
17K18997
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Materials engineering and related fields
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| Research Institution | Hiroshima Institute of Technology |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
土取 功 広島工業大学, 工学部, 教授 (20771801)
福島 千晴 広島工業大学, 工学部, 教授 (30262752)
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| Project Period (FY) |
2017-06-30 – 2019-03-31
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| Keywords | ステンレス鋼 / 不動態皮膜 / その場観察 / 原子間力顕微鏡 |
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| Outline of Final Research Achievements |
The compact passive film protects stainless steel from corrosion and its in-situ thickness should be different in various surroundings. In this study, the in-situ observation by AFM in various aqueous solutions was conducted on SUS304 steel, by removing the present film and then reproducing a new film in designated aqueous solution. The height variation of the steel surface was calculated as the thickness of the reproduced passive film. As a result, the passive film on the steel appeared in solutions with pH equal to or larger than 2.8 and became thicker in solution with larger pH, while the chloride ions caused thinner film. The in-situ thickness measured in water was confirmed to be a little larger than that in vacuum. In addition, the thickness of passive film on sensitized SUS329J4L steel was also measured and compared. The thickness on sigma phase with more Cr content is thinner than that on gamma primer phase with less Cr.
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| Free Research Field |
表面界面工学、腐食防食
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| Academic Significance and Societal Importance of the Research Achievements |
本研究では、種々水溶液中でのステンレス鋼の不動態皮膜の厚さを新しい考えをもってin-situに測定・検証してきた。これは、不動態皮膜に依存するあらゆる機能性金属（例えば、Al合金やTi合金等）にも適用できる。こうしたin-situ測定は、これからの高速FM-AFMやSTMの進化によって不動態皮膜の形成途中での原子像や原子配列の直接観察に活用できる。また、複相、結晶粒、結晶粒界上での不動態皮膜の形成・消失・破壊挙動が解明でき、今後の不動態皮膜の強化方法の開発に繋がる。なお、不動態皮膜の構造解明は、耐食性、耐摩耗性、潤滑性、導電性等の向上に良い影響を与え、コストの削減や生産効率の向上に貢献できる。
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