Which term best describes a protection method that uses electrical means to minimize corrosion of a metal surface?

• A. Salt bridge
• B. Electroplating
• C. Corrosion
• D. Cathodic protection

Answer: (D)

Cathodic protection uses electrical means to minimize corrosion. By forcing the protected metal to act as the cathode, either a more reactive sacrificial metal is connected to it or an external current is applied, electrons are supplied to the metal surface, and oxidation is suppressed. The sacrificial metal (or the external power source) then preferentially corrodes, protecting the metal of interest. This is why metals like steel in pipelines or hulls are safeguarded with zinc, magnesium, or aluminum anodes or an impressed-current system. Salt bridges simply balance charge in a galvanic cell and aren’t a protective method for surfaces in service; electroplating uses electricity to deposit a metal onto a surface to create a protective coating but doesn’t actively shift the surface potential to suppress oxidation. Corrosion is the process we’re trying to prevent, and cathodic protection is the electrical method designed to stop it.