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Optical spectroscopic and electrochemical characterization of oxide films on a ferritic stainless steel
Author(s) -
Fan Changfeng,
Shi Jianmin,
Sharafeev Azat,
Lemmens Peter,
Dilger Klaus
Publication year - 2020
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201911425
Subject(s) - corrosion , passivation , materials science , oxide , metallurgy , pitting corrosion , polarization (electrochemistry) , electrochemistry , oxidizing agent , composite material , electrode , layer (electronics) , chemistry , organic chemistry
Colored oxide films that form on ferritic stainless steel in a high‐temperature, oxidizing environment and correspond to different chemical compositions can cause a deterioration of pitting resistance and corrosion performance. Herein, optical spectroscopic and electrochemical techniques have been used to reveal the relationship between color, chemical composition, and corrosion resistance of oxide films formed in the temperature range from 400°C to 800°C for 30 min and at 800°C for 10, 20, 30, and 60 min. The substrate with a thin and dense passivation film leads to a low pitting potential but high corrosion resistance. Oxide films of yellowish or brownish color formed below 600°C are mainly iron oxides, which correspond to low corrosion resistance. No passivation characteristics can be observed for polarization curves of oxide films formed at 500°C and 600°C. The color of oxide films varies from blue to dark gray with the increase of oxidation time at 800°C. Corrosion resistance changes with different proportions of Fe 3 O 4 , Cr 2 O 3 , and FeCr 2 O 4 . The gray oxide films formed at 800°C for 30 min exhibit the lowest pitting susceptibility and the highest corrosion resistance.