Understanding of surface corrosion on structural materials by advance of KK-XAFS and corrosion-resistant materials

2019 Fiscal Year Final Research Report

• Project/Area Number: 16H05992
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Quantum beam science
• Research Institution: High Energy Accelerator Research Organization
• Principal Investigator: Abe Hitoshi 大学共同利用機関法人高エネルギー加速器研究機構, 物質構造科学研究所, 准教授 (00509937)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 放射光 / XAFS / 表面反応 / 構造材料

Outline of Final Research Achievements

Under this proposal, KK-XAFS method, which has been originally developed, has been advanced by combining IRRAS in order to observe and to understand oxidation and corrosion reactions occurred at surfaces of structural materials. Thickness of passivation layers on structural materials is several nanometers, and such surface regions should be understood.
Both in situ KK-XAFS and IRRAS measuremetns have been carried out under gaseous conditions and at elevated temperatures to observe surface reactions. Ni/Si wafer and Co/Si wafer films were used for test samples during the development. Fe surfaces were investigated to observe surface reduction and oxidation reactions by in situ measurements under several temperature conditions. In situ measurements were successfully performed with the surface sensitivity of ~2 nm.

Free Research Field

放射光科学

Academic Significance and Societal Importance of the Research Achievements

本研究課題では、独自に開発したKK-XAFS法を高度化し、構造材料等の表面で起こる酸化、腐食反応の観察と理解に取り組んできた。構造材料は表面からの腐食等により寿命を迎えるが、腐食の進行機構の詳細は不明な点も多い。不動態皮膜の典型的な厚みは数nm程度であり、最表面から数nm程度までの表面領域での腐食過程の理解が極めて重要である。
例えば鉄については、250°C, 300°C, 350°Cなど複数の温度条件下で、表面で起こる酸化反応および還元反応について、IRRASと組み合わせて高度化したKK-XAFS法を用いて、~2 nmというユニークな表面感度を活かした観察に成功した。