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Correlation between Defect Density and Corrosion Parameter of Electrochemically Oxidized Aluminum.
- Source :
- Coatings (2079-6412); Jan2020, Vol. 10 Issue 1, p20-20, 1p
- Publication Year :
- 2020
-
Abstract
- It has been recognized that a connection may exist between defects of oxide coating and its corrosion protection. Such a link has not been substantiated. We prepare two coatings of anodized aluminum oxide (AAO) and plasma electrolytic oxidation (PEO), and analyze them with Mott-Schottky plots and potentiodynamic polarization scans. The as-grown and annealed AAO coatings exhibit both p-type and n-type semiconductor behaviors. Polarization resistance of the AAO coating increases from (1.8 ± 1.7) × 10<superscript>8</superscript> to (4.3 ± 0.5) × 10<superscript>8</superscript> Ω·cm<superscript>2</superscript>, while corrosion current decreases from (6.1 ± 3.6) × 10<superscript>−7</superscript> to (2.3 ± 0.9) × 10<superscript>−7</superscript> A·cm<superscript>−2</superscript>, as annealing temperature increases from room temperature to 400 °C. The parameter analysis on AAO indicates a positive correlation between corrosion current and donor density, a negative correlation between polarization resistance and donor density. The attempt on correlating corrosion potential gives rise to considerable deviation from a linear fit. The results suggest protection of AAO hinges on its donor density, not acceptor. On the PEO coatings, only the n-type behavior is observed. Intriguingly, the donor density of PEO coating is influenced by the annealing temperature of its pre-anodized layer. The most resistant PEO coating, with pre-anodized and 400 °C annealed AAO, exhibits polarization resistance (2.1 ± 0.4) × 10<superscript>9</superscript> Ω·cm<superscript>2</superscript> and corrosion current (1.7 ± 0.4) × 10<superscript>−8</superscript> A·cm<superscript>−2</superscript>. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 20796412
- Volume :
- 10
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- Coatings (2079-6412)
- Publication Type :
- Academic Journal
- Accession number :
- 141411135
- Full Text :
- https://doi.org/10.3390/coatings10010020