Open AccessRoles of Interstitial Nitrogen, Carbon, and Boron in Steel Corrosion: Generation of Oxyanions and Stabilization of Electronic Structure
Author(s) -
Mariko Kadowaki,
Arkapol Saengdeejing,
Izumi Muto,
Ying Chen,
G. S. Frankel,
Takashi Doi,
Kaori Kawano,
Yu Sugawara,
Nobuyoshi Hara
Publication year - 2020
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/ab8926
Subject(s) - materials science
The effects of N, C, and B interstitials on the corrosion resistance of Fe were investigated in chloride-free boric-borate solutions at pH 6.0 and 8.0. In potentiodynamic polarization at pH 8.0, the anodic dissolution resistance of Fe-0.3N and Fe-0.3C in the active and passive regions was higher than that of pure Fe. NH 4 + and NO 2 − are considered to be dissolved chemical species that contribute to the higher corrosion resistance of Fe-0.3N. Potentiodynamic polarization measurements in a solution with HCO 3 − indicated that HCO 3 − also decreases the anodic current densities in the active and passive regions, suggesting that the formation of HCO 3 − contributes to the higher corrosion resistance of Fe-0.3C. First-principles calculations showed that the presence of N, C, and B in the Fe-lattice decreases the electronic density of states (DOS) at and near the Fermi level. The consistency between the active dissolution rates and the DOS at and near the Fermi levels of the specimens suggests that the more stable electronic structures occurred by the presence of N and C also result in the suppression of active dissolution of Fe. For Fe-0.3B and Fe-0.006B, the presence of iron boride precipitates promoted localized corrosion.