What is galvanic corrosion?

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 –

• Choosing materials with similar corrosion potentials
• Insulating the two metals from each other to break the electrical connection
• Apply coatings to both materials – remember the coating on the cathode is the most important and needs to be in good condition or this could worsen galvanic corrosion
• Insert a suitably sized spacer to separate the two materials
• Install a sacrificial anode which is anodic to each metal
• Add corrosion inhibitor to the environment

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.

Got any more questions? Get in Touch

If you have any more questions about corrosion-resistant alloys, please contact us today. A member of our team will be more than happy to help and can also advise you on the best option for your application.