Galvanic corrosion can occur between a metal and which type of non-metal?

• A. Graphite
• B. Ceramics
• C. Insulating plastics
• D. Wood

Answer: (A)

Galvanic corrosion happens when a metal is in electrical contact with another material in an electrolyte, allowing electrons to flow and forming a galvanic cell. The non-metal must be conductive to complete the electrical path. Graphite is a conductive non-metal, so a metal in contact with graphite in the presence of an electrolyte can form a galvanic couple and cause the metal to corrode preferentially. Ceramics, insulating plastics, and wood are insulators and do not provide a path for electron flow, so they do not support galvanic corrosion in the same way.