Corrosion Midsem

In Seawater severe corrosion may be caused due to pitting corrosion or crevice or stress corrosion cracking.
Evans Diagram for two metals with corresponding hydrogen reductions, involves the individual lines adding up. Using mixed potential theory, total rate of oxidation should equal total rate of reduction.
Pourbaix Diagram for three species in equilibrium has \(\left(\begin{array}{c} 3\\2 \end{array}\right)=3\) lines which intersect at the same point. Passivation region is where MO is stable, Immunity region is where M is stable and corrosion region is where \(M^{+}\) is stable.
For concetration of oxygen in ppm, there is diffusion control hence \(i_{corr}=i_L\). Relating the flux with Diffusivity and concetration using the Fick’s Law gives us \(i_L= D_{O_{2}} \frac{C^{O_2}_B}{\delta} nF\).