Corrosion is defined as;
Destroy or damage (metal, stone, or other materials) slowly by chemical action. Oxford Dictionary.
Put more simply, Corrosion is the process by which something deteriorates because of oxidation, a chemical action that creates oxides on the surface of the parent material. Although the word is usually associated with the rusting metal, the erosion of rock by wind and water is also a form of corrosion.
So why should you be worried?
Well corrosion may usually occour on the surface of the parent material but often this surface is hidden from view by coatings or another structure.
Good examples of this is Filiform corrosion. This is corrosion of a material when water gets under the surface coating, such as paint. It is very common to see on mine sites cracked and peeling paint. If you peel off one of these flakes you will likely find the material underneath has significant surface corrosion.
The reason the paint cracks and peels from the surface is the corrosion process. The oxides cause in the corrosion process expand.
This ‘General attack’ corrosion is not the only kind. Another seen on mine sites is Galvanic corrosion. Galvanic corrosion occors when 2 different materials are close to each other with an electrolyte in between. No not just the electrolytes found in your favourite hangover cure, but any fluid that transfers electrons.
One of the material’s electrons are attracted to the other material, slowly causing a material loss. Galvanic corrosion though can also be used as a protection method. By putting a ‘sacrificial’ block of material that is more susceptible to corrosion in the vicinity of the material you are trying to protect, the sacrificial material corrodes first.