Galvanic Corrosion

Definition

Galvanic corrosion occurs when two dissimilar metals are in electrical contact and immersed in an electrolyte, causing the less noble metal to corrode preferentially. It raises voltage by electrically coupling metals of different nobility.

It requires dissimilar metals, metal-to-metal contact, and a shared electrolyte; the more noble metal becomes the protected cathode while the less noble metal becomes the rapidly corroding anode. The farther apart the metals sit on the galvanic series, the higher the voltage and the faster the anode dissolves, and dielectric unions are used to break the electrical path. Severity also depends on the surface area ratio, with a small anode and big cathode being far more dangerous, often causing rapid catastrophic failure of the anodic component.

Related concepts

Galvanic Series · Current Density · Nobility

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Part of The Blueprint of Water · ⚡ electrochemistry