Galvanic Corrosion

Question 1

What is galvanic corrosion?

Answer 1

(V. brief summary) An electrochemical process were a more active metal in the galvanic series corrodes when connected to a more passive metal in the galvanic series . An electrolyte solution (i.e salt water) will cause electrons to flow from the anode to the cathode to cause corrosion- REDOX reaction

Question 2

What are the parts of an electrochemical or ‘Galvanic cell’

Answer 2

Anode: The site were the metal is corroded (Undergoes oxidation reaction)
Cathode: Part of the same metal or surface or different metal surface which is protected from corrosion (undergoes reduction reaction)
Electrolyte solution: Corrosive medium which is electrically conductive

Question 3

In a galvanic cell, which metal will corrode?

Answer 3

The metal with the more negative electrode potential (the more active metal/least noble) is likely to corrode whilst the other metal (the more passive metal/most noble) remains protected

Question 4

When does galvanic corrosion occur?

Answer 4

When any dissimilar metals are connected in an electrolyte solution this will cause the anode to corrode.
Thus necessary to protect structural designs from corrosion, as corrosion weakens metals

Question 5

How can Galvanic corrosion be prevented?

Answer 5

Do not connect dissimilar metals.
If this can’t be avoided
-electrically isolate one from another with rubber etc
-make the anode large and the cathode small
-eliminate the electrolyte
-make anode easily replaceable