Corrosion of Metallic Coatings
263
Therefore, a corrosion-resistant coating is achieved by considering five surface
treatment methods to decrease i corr on the basis of Equation 8.8. Specifically,
1. Decrease in electromotive force (E C – E a ): EMF control protection
2. Increase in cathodic overpotential: η C cathodic control protection
3. Increase in anodic overpotential: η a anodic control protection
4. Increases in both anodic and cathodic overpotential: η a and η C ,
mixed control protection
5. Increase in resistance of corrosion cell: R resistance control
protection.
Resistance Control
Log Current Density
Mixed Control
Cathodic Control
Electrode Potential
Anodic Control
i corr
i corr
i corr
i corr
E corr
E corr
E corr
FigurE 8.4
Four types of corrosion controls.