Any time you’re working with metals, there’s always a risk of corrosion. This corrosion is typically caused by exposure to certain environmental elements, such as excessive moisture or oxygen.
While it’s true that all forms of corrosion are problematic, galvanic corrosion is especially troublesome because of the varying levels of corrosion that it can cause.
Let’s dive into what galvanic corrosion is and how it can be prevented.
What is Galvanic Corrosion?
Galvanic corrosion is corrosion damage that is induced when two different metals are in contact with each other in the presence of an electrolyte, such as moisture. Galvanic corrosion is also known as bimetallic corrosion or dissimilar metal corrosion.
The rate of corrosion will depend on a few factors, including:
- The amount of the electrolyte
- The concentration of the electrolyte
- The difference in electrical potential (anodic-cathodic relationship) of the metals
For example, a highly-anodic metal, such as zinc, combined with a highly-cathodic material, such as silver, will corrode far quicker than two similar metals. In this case, the anodic metal will begin to corrode at a faster rate.
Why is Galvanic Corrosion a Problem?
The most common place where galvanic corrosion occurs is with welds. When the weld metal and the base metal aren’t the same, they have completely different potentials for both releasing and receiving electrons in the presence of a conducting solution, such as saltwater.
In this case, galvanic corrosion can cause the weld to deteriorate and eventually fail, causing all sorts of different problems depending on what the weld is used for.
The steel used in pipes and for bridge construction is especially susceptible to galvanic corrosion. If these welds fail due to galvanic corrosion, serious problems can occur.
Galvanic Corrosion Solutions
There are several different solutions for preventing galvanic corrosion, most of which involve eliminating the elements that cause it in the first place. Here are a few different solutions you can use.
Choose metals with similar corrosion properties
When it comes to galvanic corrosion, the higher the difference in corrosion potential, the faster corrosion will occur. This means that you can prevent galvanic corrosion by choosing two metals with similar corrosion properties. The Galvanic Corrosion Chart tells you where common metals end up on the corrosion potential scale.
Galvanic corrosion is directly caused by electrons flowing from the anode to the cathode. If you break this electrical path, you can prevent galvanic corrosion. Breaking the path is done by placing a non-conductive material between the contact points of the two metals, which prevents this flow of electrons.
Isolating the Electrolyte
The other factor that causes galvanic corrosion is the presence of an electrolyte. Certain measures can be taken to isolate the metals from the electrolyte to prevent galvanic corrosion. For example, there are certain water-repellant compounds, such as paints or oils, that can create a barrier between the electrolyte and the corroding materials.
Looking For More Information on Galvanic Corrosion?
Since Tanner deals with fasteners of varying materials, we understand the detrimental effects of galvanic corrosion (and other types of corrosion as well.) If you’re looking for fasteners with built-in corrosion protection, Elco’s Flex Technology can help.