Which principle is used in cathodic protection to prevent the corrosion of a metal surface?

The principle used in cathodic protection to prevent the corrosion of a metal surface is based on impressed current. This technique involves applying a direct current to the metal intended for protection, which alters the electrochemical reactions occurring on its surface. By supplying an external power source, the electric current helps to counteract the natural corrosion processes that occur in environments where metal is exposed to electrolytes.

In impressed current systems, anodes are placed in the vicinity of the metal structure, and the power supply generates a current that flows from these anodes to the target metal, effectively making it negatively charged. This change in charge reduces the metal's tendency to lose electrons, thereby decreasing the corrosion rate significantly.

Understanding impressed current cathodic protection is crucial, especially in the maintenance and longevity of infrastructure such as pipelines and storage tanks, where corrosion can lead to catastrophic failures if not managed effectively.