What Does Differential Aeration Corrosion Mean?
Differential aeration corrosion is a type of corrosion that occurs when oxygen concentrations vary across a metal's surface. The varying concentration of oxygen creates an anode and a cathode on the metal's surface. Oxidation then occurs because an anode and a cathode have been established on the surface.
Corrosionpedia Explains Differential Aeration Corrosion
In differential aeration corrosion, the area with the higher oxygen concentration becomes the cathode. The area with the lower oxygen concentration becomes the anode. Consequently, the portion of the metal that has the lower oxygen concentration is the portion subject to corrosion.
Some examples where varying concentrations of oxygen may be found are metals that are buried, certain joint types, crevices and cracks. Metals that are partially submerged in water are also subject to differential aeration corrosion because the oxygen concentration in the water is typically different from the oxygen concentration in the atmosphere.