In corrosion protection, what is a cathode?

In the context of corrosion protection, a cathode refers to the electrode at which reduction occurs, which is a crucial concept in electrochemistry. During the electrochemical reactions involved in corrosion, oxidation happens at the anode, where electrons are released, while at the cathode, these electrons are accepted by species in the environment that undergo reduction.

This process is fundamental to understanding how corrosion can be mitigated. When a protective coating, such as paint, is applied to a metal surface, it acts to isolate the metal from corrosive elements that could facilitate oxidation. However, if the coating is compromised, the exposed metal can become an anode in the electrochemical cell, while the surrounding areas remain cathodic, which can further accelerate corrosion processes.

Understanding that the cathode is the site of reduction helps in forming corrosion protection strategies, such as cathodic protection, which involves applying a more easily oxidizable metal (anodes) to the structure, thus protecting the cathodic areas from corrosion. This concept is key not just in theory, but also for practical applications in maintenance and inspection of coated surfaces.