When stainless steel and aluminum are in contact, they can undergo a reaction known as galvanic corrosion. This occurs when two dissimilar metals contact with each other when an electrolyte is present, such as saltwater or acid. In this situation, the aluminum acts as the anode and the stainless steel acts as the cathode. This causes a flow of electrons from the anode to the cathode, resulting in the degradation of the aluminum.
However, the extent and rate of galvanic corrosion between stainless steel and aluminum depends on several factors, such as the specific types of stainless steel and aluminum, the surface finish, and the environment. For instance, when a layer of paint or anodizing protects the aluminum, the galvanic corrosion can be minimized.
To prevent galvanic corrosion between stainless steel and aluminum, it is recommended to separate the two metals using a non-conductive material or to use a barrier material such as a gasket or a sealant between the two metals.