CORROSION IS A NATURAL PHENOMENON
The metal originates from an ore in oxidized form. The purpose of metallurgy is to reduce the oxidized form to the metal state by reduction. However, metals are unstable; in contact with natural elements such as oxygen (O₂), water (H₂O), they tend to want to return to their original state of oxide. Corrosion promoters such as sulfur dioxide (SO₂) and carbon dioxide (CO₂), etc., enhance the natural phenomenon of corrosion by chemical or electrochemical reaction.
Chemical phenomenon :
Under the action of natural elements such as oxygen, water, and corrosion stimulating pollutants such as sulfur dioxide, carbon dioxide, etc., metals can corrode.
Electrochemical phenomenon :
A battery consists of two electrodes, electrically connected in an electrolyte.
- Anode (-) = -> loss of electrons = -> oxidation or corrosion
- Cathode (+) = -> electron gain = -> reduction = protection
The anode will be the metal with the most electronegative dissolution potential. The cathode will be the metal with the least electronegative dissolution potential.
Source: Galvazinc, Corrosion, 13/09/2012
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