Corrosion - How is corrosion involved?

Corrosion is a natural process when a pure metal degrades into a more chemically stable form such as oxide, hydroxide, or sulphide, usually through a chemical and/or electrochemical reaction with their environment.

Rusting, the formation of iron oxides, is a well-known example of electrochemical corrosion. Corrosion degrades the useful properties of materials and structures including strength, appearance and permeability to liquids and gases. Many structural alloys corrode merely from exposure to moisture in air, but the process can be strongly influenced by exposure to certain substances.

Corrosion usually affects an exposed area but can also be concentrated locally to form a pit or crack. For this reason items are protected by a coating such as a paint or galvanising.

The chemistry of corrosion is quite complex but is essentially an electrochemical phenomenon. Corrosion engineering is the field dedicated to controlling and preventing corrosion.

Corrosion Institute of Southern Africa