Is Corrosion a natural process?

By Corrosion Science Doctor

Corrosion is a natural process that occurs when metals are exposed to oxygen and moisture in the environment. It is an electrochemical reaction between the metal and its environment, which results in the formation of oxides on the surface of the metal. The corrosion process can be divided into three stages: initiation, propagation, and passivation.

The initiation stage is when the corrosion reaction begins. This stage involves the formation of anodic and cathodic sites on the metal surface, which are areas where oxidation and reduction reactions occur. The anodic sites are areas where oxidation occurs, while the cathodic sites are areas where reduction occurs. These sites form due to differences in potential between different parts of the metal surface.

The propagation stage is when the corrosion reaction continues to spread across the metal surface. During this stage, electrons flow from anodic sites to cathodic sites, resulting in further oxidation and reduction reactions. This stage is also known as galvanic corrosion because it involves a current flow between two different metals or alloys.

The passivation stage is when the corrosion reaction slows down or stops completely due to a protective layer forming on the metal surface. This layer prevents further oxidation and reduction reactions from occurring by blocking electron transfer between anodic and cathodic sites. Passivation can be achieved through various methods such as painting or coating with a protective material, applying a protective film or coating, or using inhibitors that prevent oxidation reactions from occurring.