Which of the following is NOT a factor affecting the extent of accelerated corrosion resulting from galvanic coupling?

• A. Potential difference between the metals
• B. The specific nature of the environment
• C. Polarization behavior of the coupled materials
• D. Color of the metals

Answer: (D)

Galvanic corrosion occurs when two dissimilar metals are in electrical contact in an electrolyte, and the driving force is the potential difference between the metals. A larger potential difference pushes more current through the circuit, accelerating the anodic metal’s dissolution. The environment matters because the electrolyte's composition, temperature, and conductivity influence ion movement and protective film formation, which in turn affect the rate. Polarization behavior of the metals also plays a role: metals with resistant polarization can limit current and slow the corrosion rate, while those that polarize less readily allow higher currents and faster attack. The color of the metals has no effect on their electrochemical properties or on galvanic current, so it does not influence the extent of accelerated corrosion.