A metal ion is a type of atom compound that has an electric charge. Such atoms willingly lose electrons in order to build positive ions called cations. Ions are essentially enclosed by delocalized electrons which are responsible for processes like conductivity.
Corrosion is a natural process that involves reducing a metal’s binding energies. The end result is a metal atom undergoing oxidation. This occurs when the metal atom loses electrons while leaving the bulk metal.
The electrons that are lost throughout the process are carried through the bulk metal to other sites where reduction occurs, and there is a combination of a non-metallic element with metal ions, which are in contact with the bulk metal.
The area where the atoms of metal lose electrons is referred to as the anode, while the side where there is transfer of electrons is the cathode.
Cathode and anode pairs are called corrosion cells, and they appear in different forms such as:
- Concentration cells
- Composition cells
- Galvanic cells
Corrosion is best described as an electric circuit since current flow exists between the anode and cathode sites. A better understanding of electrical conductivity within the circuit, including the action of metal ions and other components, can help in controlling corrosion.