Which of the following best describes galvanic corrosion?

Galvanic corrosion occurs when two dissimilar metals are in electrical contact with each other in the presence of an electrolyte, such as water. This type of corrosion arises from the electrochemical reaction that takes place when one metal becomes anodic (losing electrons) and the other becomes cathodic (gaining electrons). The flow of electric current between these two metals causes the anodic metal to corrode more rapidly than it would on its own.

In this context, understanding galvanic corrosion is crucial for preventing damage in systems where different metals are used together, such as in piping, electrical connections, and marine applications. Effective techniques to mitigate galvanic corrosion include using insulating materials to separate the metals, applying protective coatings, or using sacrificial anodes to protect the more valuable metal from corrosion.

The other choices describe causes of corrosion but do not specifically identify the mechanism involved in galvanic corrosion. For instance, moisture and excessive heat can contribute to general corrosion processes, while chemical reactions can alter material integrity, but these are not directly related to the galvanic action between dissimilar metals.