Section B$.$ Assessing Pitting Corrosion

$18$ Marks

A polarization diagram for C$89$ in a simulated sea water is shown in Figure B$.$ Only the Tafel line for anodic dissolution is shown. Table B$1$ shows the measured parameters needed to define the passive corrosion of the metal.

B$1.$ Draw the full polarization curve for C$89$ onto Figure B$.$ Use a stick diagram style $($straight lines$).$ If a parameter is missing, use a dotted line to indicate an expected behavior. Assume all metal dissolution reactions have the same Tafel slope.

$5$ Marks

B$2.$ Include on Figure B the cathodic process for HER and ORR given the parameters in Table B$1.$ Again, use stick figures.

$5$ Marks

B$3.$ Determine the corrosion rate in a bulk, aerated sea water environment.

$3$ Marks

B$4.$ Will this material pit or crevice corrode and is it suitable for use with a sea water input? Explain your opinion based on the information provided in this question and Question C$.$

$5$ Marks

Figure B: Partial Polarization Diagram for corroding system in Question B$.$

Table B$1$: Passive Corrosion Parameters for C$89$ and Environmental Factors

$\backslash$table$[[$Parameter$,C89,\frac{H^{+}}{H_2},\frac{O_2}{O}{H}^{-},$unit$],[E,-0\mathrm{.}350,0\mathrm{.}000,1\mathrm{.}229,V$