Galvanic corrosion is a type of corrosion that occurs when two different metals are connected in the presence of an electrolyte. The more active metal will corrode while the less active metal will remain relatively unaffected. This can be a major problem when aluminum and stainless steel are connected as they are two very different metals.
Preventing Galvanic Corrosion
Fortunately, there are several steps you can take to prevent galvanic corrosion between aluminum and stainless steel. Here are some tips:
Use a Non-Conductive Barrier
The most effective way to prevent galvanic corrosion is to use a non-conductive barrier such as epoxy, paint, or rubber between the two metals. This will prevent the direct contact between the metals and thus reduce the risk of corrosion.
Apply a Coating of Zinc to the Aluminum Surface
Another option is to apply a coating of zinc to the aluminum surface. This will protect the aluminum from corrosion by forming a protective layer over it. Zinc coatings are often used on boats and other marine vessels to prevent corrosion.
Connect the Two Metals with a Third Metal That Is Less Reactive
If a non-conductive barrier cannot be used, then it is important to connect the two metals with a third metal that is less reactive than either of the two. This will help reduce the risk of corrosion by reducing the electrical current between the two metals.
Increase the Electrical Resistance of the Connection with an Insulating Material
It is also possible to increase the electrical resistance of the connection between the two metals by using an insulating material such as rubber, plastic, or fiberglass. This will further reduce the risk of corrosion by limiting the amount of current that can pass through the connection.
Use a Sacrificial Anode Made of a More Active Metal
A sacrificial anode made of a more active metal such as zinc can also be used to protect the aluminum from corrosion. The anode will corrode instead of the aluminum, thus preventing any damage to the aluminum surface.
Apply a Protective Sealant to the Connecting Area
Applying a protective sealant to the connecting area is another way to prevent corrosion. Sealants such as epoxies, silicones, or paints can be used to create a waterproof barrier between the two metals, thus protecting them from corrosive elements.
Coat the Metals in a Dielectric Grease
Finally, coating the metals in a dielectric grease can help reduce the risk of corrosion. The grease will act as an insulator, thus preventing any current from passing through the connection between the two metals.
Galvanic corrosion between aluminum and stainless steel can be prevented with careful maintenance. By using a non-conductive barrier, applying a zinc coating, connecting with a third metal, increasing electrical resistance, using a sacrificial anode, applying a sealant, and coating in a dielectric grease, you can greatly reduce the risk of corrosion.