Galvanic corrosion is an electrochemical process that exists when two dissimilar metals are in contact with one another via an electrolyte. It is therefore also known as bimetallic corrosion.
In principle, one of the metals will corrode in preference to the other, and the extent of the corrosion depends upon how dissimilar the metals are in terms of their ‘galvanic potential’. Usually, galvanic corrosion occurs by accident, when the interaction of dissimilar metals is overlooked or not anticipated in the original application. However, it can also be exploited in a form of corrosion protection, when a dissimilar metal is deliberately connected to the metal to be protected – with it corroding sacrificially, allowing it to be more easily inspected and replaced as required.
How to Avoid Galvanic Corrosion?
Galvanic corrosion can be avoided by taking the following actions –
If the measures listed above are not practical, the rate of corrosion can be lowered by keeping the anode to the cathode area large or have the anode designed with an appropriate corrosion allowance.
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