2023 Fiscal Year Final Research Report
Investigation of the lower temperature limit for the formation of hexavalent chromium-containing oxyhydroxide from stainless steel
| Project/Area Number |
21K12282
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 64010:Environmental load and risk assessment-related
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| Research Institution | Oyama National College of Technology |
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Principal Investigator |
Atsumi Taro 小山工業高等専門学校, 物質工学科, 准教授 (40282157)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | ステンレス / 酸化被膜 / 六価クロム |
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| Outline of Final Research Achievements |
Surface oxide film on SUS304 stainless steel has been examined from 473 to 773 K in dry and humid air. The oxidation of a chromium and an iron at 673 K and 773 K results in the formation of a FeCr2O4 film on the SUS304 steel. A chromium oxyhydroxide containing a hexavalent chromium is volatilized from the FeCr2O4 film to heat in humid air for long time. A surface oxide film containing iron and chromium grows on SUS304 and SUS310S stainless steels at 673 K in dry and humid air. After 100 h in humid air, vaporization of a chromium oxyhydroxide containing hexavalent chromium from this oxide film. The oxide film containing iron is formed on SUS316 and SUS430 surface and is a stable in both dry and humid air at 673 K.
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| Free Research Field |
固体化学
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| Academic Significance and Societal Importance of the Research Achievements |
ステンレス鋼の使用上限温度は一般的に機械的性質から決定され，酸化被膜からの六価クロムの生成に注意が払われることはない．本研究では，使用上限温度が1000～1200 Kとされるオーステナイトステンレスの代表的鋼種であるSUS304(18Cr-8Ni)を，673 K，低水蒸気圧の空気中で長時間加熱すると，表面酸化物被膜から六価クロムを含む酸化物水酸化物が生成することを見出した．同様に表面酸化被膜にクロムが含まれるステンレス鋼種では，六価クロム酸化物水酸化物の揮発が見られた．これらステンレス鋼を高湿度環境で長時間使用する場合，環境への影響を考え,使用温度上限は573 K程度が望ましいことがわかった．
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