Which approach is least effective for preventing galvanic corrosion in mixed-metal assemblies exposed to marine spray?

• A. Isolating dissimilar metals with non-conductive barriers
• B. Applying compatible coatings
• C. Choosing metals with similar electrochemical potentials
• D. Placing dissimilar metals in direct contact without isolation

Answer: (D)

Galvanic corrosion happens when dissimilar metals are in electrical contact in the presence of an electrolyte, like marine spray, causing the more anodic metal to corrode faster. The best ways to prevent this are to break the electrical path or reduce the driving force: use non-conductive barriers to isolate metals, apply coatings to limit exposed surface and electrolyte access, and choose metals with similar electrochemical potentials so the driving voltage is small. Placing dissimilar metals in direct contact without isolation keeps the galvanic couple intact and lets the corrosion process run, so it’s the least effective approach. In short, prevent the electrical connection and limit exposure to saltwater to minimize galvanic action.