Corrosion caused by galvanic action results from what condition?

Galvanic corrosion occurs when two dissimilar metals are in electrical contact with each other in the presence of an electrolyte, such as water or moisture. This creates a galvanic cell, where one metal acts as an anode (which corrodes) and the other as a cathode (which is protected). The difference in electrode potential between the two metals leads to an electrochemical reaction that accelerates the corrosion of the anode.

Understanding this principle is essential in aircraft construction and maintenance, where different metals are often used for their unique properties. Proper material selection and protective measures are critical to preventing galvanic corrosion, ensuring the structural and operational integrity of aircraft components.

The other conditions presented do not specifically relate to galvanic corrosion. Excessive etching, for instance, pertains to the alteration of surfaces due to chemical processes rather than metal interactions. The contact of highly-loaded surfaces could lead to wear rather than galvanic corrosion. An attack on grain boundaries relates more to intergranular corrosion, which is a different mechanism altogether.