Cathodic Corrosion

Definition - What does Cathodic Corrosion mean?

Cathodic corrosion is a process in which one metal (the anode) acts as a sacrificial metal to protect another metal (the cathode) in an electrochemical cell. It is the underlying premise of a corrosion control technique called cathodic protection.

For cathodic corrosion occur, three components must be present: an anode (usually a more reactive metal), a cathode (the metal to be protected) and an electrolyte (any liquid that facilitates the transfer of electrons).

Trenchlesspedia explains Cathodic Corrosion

Cathodic corrosion, they key element of cathodic protection, is a common technique to mitigate the corrosion of lengthy pipelines, offshore platforms, ships and underwater storage tanks.

This type of corrosion often occurs when two dissimilar metals are in contact with each other to form a circuit called an electrochemical cell. In the case of pipelines, zinc, aluminum, and magnesium are commonly used as sacrificial anodes to protect buried steel pipelines which act as the cathode.

The anode and the cathode are connected to an external power source which provides sufficient current to initiate the reaction. Electrons are then shuffled from the anode to the cathode, which causes the anode to corrode in a series of complex chemical reactions. Protection of the cathode continues until the anode is depleted.

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