In galvanic corrosion, the cathodic metal's corrosion rate typically does what?

• A. Increases
• B. Stays the same
• C. Fluctuates
• D. Decreases

Answer: (D)

When two metals with different electrochemical potentials are in contact in an electrolyte, the more noble metal acts as the cathode and is protected from oxidation, while the less noble metal becomes the anode and corrodes faster. The corrosion current mainly drives the anodic dissolution, so the cathodic metal experiences reduced material loss. Therefore, the cathodic metal’s corrosion rate typically decreases. In practice, there can be small, local effects on the cathode, but the overall rate on the cathodic metal is much lower than on the anodic metal.