What is sacrificial anode protection and how does it protect a structure?

• A. A protective coating applied to shield from oxygen.
• B. An electroplating process to harden surface.
• C. A process of removing rust chemically.
• D. A more active metal is attached to the structure and corrodes instead of the protected metal, protecting it.

Answer: (D)

Sacrificial anode protection is based on galvanic protection: you attach a metal that is more chemically active than the structure you want to protect. In the environment between them (often moist soil or seawater), the more active metal becomes the anode and corrodes first, while the structure becomes the cathode and is protected from corrosion. The electrons flow from the sacrificial metal to the protected metal, so oxidation occurs at the sacrificial metal and not on the protected one. Over time the sacrificial metal is consumed and must be replaced, but the structure stays protected. This isn’t about coatings, plating to harden a surface, or chemically removing rust—it relies on a more active metal taking the hit first to shield the other metal.