Aluminum Cathodic Protection
Definition - What does Aluminum Cathodic Protection mean?
Aluminum cathodic protection is a method of protecting materials from corrosion by using aluminum as an anode.
For galvanic cathodic corrosion protection to be successful, the anode should possess lower electrochemical potential than the cathode or the structure to be protected. Aluminum has a potential of around - 1.05, so when used as the anode, the structures to be protected must have a potential higher than aluminum. This applies to materials such as zinc, magnesium, copper and most metals.
Corrosionpedia explains Aluminum Cathodic Protection
Corrosion occurs when two unlike metals are combined and the following is present:
- Electrolyte (water with dissolved salts or salt itself)
- Metal that conducts between the two unlike metals
The two metals may involve entirely unique alloys like aluminum and steel. In such a case, reactions take place at highly active sites, while free electrons go throughout the metal into the sites that are less active.
Oxygen gas is then transformed into ions of oxygen through joining with at least four free electrons that in turn unite with water to generate hyroxil ions. The reuniting ions located at the active area produce corrosive ferrous hydroxide, made from the combination of oxygen and iron. This type of reaction is typically called current flow to anode, or movement from more active surfaces to less active ones are referred to as the cathode.
Aluminum cathodic protection helps stop corrosion in a way similar to cathodic protection, in the sense that the process halts corrosion by transforming active anode sites of the metal surface to passive or cathodic sites through supplying free electrons from a different source.
This takes place through a sacrificial system that involves galvanic anodes that are highly active compared to steel. In such a case, galvanic anodes serve as the sacrifice in order to offer protection against corrosion.