Abstract
To modify the corrosion protection provided by conversion coated Zn-Al-CO3 layered double hydroxides (LDHs) on electrogalvanized steel sheets (EG steels), methods to intercalate NO3 − during post treatment were explored and the effect of intercalation on corrosion resistance was evaluated. EG steels were immersed in a Na2Al2O4 based solution to form a Zn-Al-CO3 LDH conversion coating layer, and were then immersed in a NaNO3 methanol solvent to intercalate NO3 −. After 2 h of immersion, it was found that NO3 − had completely exchanged with the originally intercalated CO3 2− anions in the conversion coated Zn-Al-CO3 LDHs. Corrosion resistance measurements of the EG steel surfaces protected by the NO3 − intercalated in the LDH layer were performed by a simple immersion test and a droplet test. When the samples were immersed in a large amount of 0.1 M NaCl, the corrosion resistance of the NO3 − intercalated LDH layer was inferior to that of the control sample. In contrast, the samples that were exposed to a 100 μl droplet of 0.1 M NaCl displayed improved corrosion resistance. The difference in these results was attributed to the solubility of the LDH layer and the resulting effect on the release process of NO3 − from the LDH layer.
Original language | English |
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Pages (from-to) | C461-C468 |
Journal | Journal of the Electrochemical Society |
Volume | 165 |
Issue number | 9 |
DOIs | |
State | Published - 2018 |
Bibliographical note
Publisher Copyright:© The Author(s) 2018.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Materials Chemistry
- Surfaces, Coatings and Films
- Electrochemistry
- Renewable Energy, Sustainability and the Environment