Which galvanic corrosion control method uses sacrificial anodes to protect the structure?

• A. Cathodic Protection
• B. Barrier Coatings
• C. Electrical Isolation
• D. Design

Answer: (A)

Sacrificial anodes protect a structure through cathodic protection. In a galvanic couple, the more active metal (the sacrificial anode, such as zinc or magnesium) oxidizes first, forming the anode, while the protected structure becomes the cathode. This electron flow shifts the structure to a more negative potential, suppressing its corrosion because oxidation reactions are inhibited at the cathode. The anode then slowly dissolves, so it must be replaced over time, but the structure remains protected as long as the anode is in good contact and in the same electrolyte.

Other methods don’t rely on a driven galvanic partner. Barrier coatings physically isolate the metal from corrosive environments, electrical isolation removes conductive paths, and design changes modify exposure or risk without introducing sacrificial material. There is also impressed current cathodic protection, which uses an external power source rather than sacrificial anodes.