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# ENG3010DL Corrosion Analysis

## Question :

1. a) Name the three main constituents of a typical paint coating prior to application.
b) What two important functions do the pigments in the primer coat fulfill?
c)  What are the mechanisms by which these functions operate?

2. Using a sketch or schematic labeled Evans Diagram and mixed potential theory explain what happens with regards to Corrosion potential (Ecorr) and Corrosion Current (ICorr) when two dissimilar metals are joined as a couple in the presence of an electrolyte environment .

a) Using copper and steel as an example with free potentials of -0.35 and -0.72 respectively, estimate the Couple potential .

b) How does this relate to corrosion rates of the two individual metals?

c) List four factors affecting galvanic or dissimilar metal corrosion that make calculating exact corrosion rates difficult when data is extrapolated into large scale engineering situations.

d) Give two situations where mixed potential is used to advantage.

3. a) Why is -850 mV SSC (electrode potential) used for the cathodic protection potential for many steel structures?
b)  What are the dangers of using greater negative potentials with regards to the effects on the metal?

4. Compute the voltage (in V) at 25°C produced by an electrochemical cell consisting of pure copper (which has a standard electrode potential of -0.340 V) immersed in a 0.003 M solution of Cu2+ ions, and pure iron (which has a standard electrode potential of -0.440 V) in a 0.30 M solution of Fe2+ ions. Show all working and formula.

Hint:(This question is based around equation 4.18, it is a laboratory cell consisting of two different metals in their own ionic, solutions connected by a salt bridge. As such the products and reactants can be substituted by the Molar values, and Eo will be a mixed potential)

5. Describe in detail an electrochemical test procedure that could be used to assess an organic coating and compare it to another electrochemical or physical test. [You will need to look back at earlier learning packages and possibly do some extra research to answer this question fully].

Explain how the test is conducted, the parameters used and what you are actually measuring. What are the advantages and disadvantages compared to the other choice you have described. How can data be treated to obtain useful information? How does this relate to your understanding of the corrosion protection and degradation mechanisms of organic coatings used on metal substrates?

6. Explain the difference between pitting and crevice corrosion with regards mechanism? In your answer you should differentiate between the initiation stages and stable stages of these mechanisms using diagrams where appropriate.

### Cite This Work

My Assignment Help (2020) Corrosion Analysis [Online]. Available from: https://myassignmenthelp.com/free-samples/eng3010dl-corrosion-analysis/protecting-corrosion.html
[Accessed 17 August 2022].

My Assignment Help. 'Corrosion Analysis' (My Assignment Help, 2020) <https://myassignmenthelp.com/free-samples/eng3010dl-corrosion-analysis/protecting-corrosion.html> accessed 17 August 2022.

My Assignment Help. Corrosion Analysis [Internet]. My Assignment Help. 2020 [cited 17 August 2022]. Available from: https://myassignmenthelp.com/free-samples/eng3010dl-corrosion-analysis/protecting-corrosion.html.

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