Working Principle

The protective potential is the potential required to stop (or negligible) corrosion of a metal during cathodic protection. In practice, the protective potential of steel is often taken as -0.85V (CSE), which means that when the metal is at a more negative potential than -0.85V (CSE), the metal is protected and corrosion can be ignored.

Chemical reaction equation

Anodic reaction: Mg-2e→Mg2+

Cathodic reaction: H2O+ O2+2e →2OH-

The function of magnesium sacrificial anode is to reduce the corrosion rate of the cathode (such as steel and other metals) to achieve the purpose of protecting the cathode.

The basic premise of magnesium alloy protection cathode is the cathode in the absence of external interference in the case of corrosion belongs to the electrochemical corrosion (that is, the process of corrosion with current generation), but not all electrochemical corrosion can be protected by sacrificial anode, the specific application process should have the following conditions:

(1) The corrosion medium must be able to conduct electricity so that a continuous circuit can be established.

(2) The medium in which the protected metal material is located should be easy to carry out cathodic polarisation, otherwise the power consumption is large and it is not easy to carry out cathodic protection.

(3) For complex metal equipment or structures, the geometric shielding effect should be considered to prevent the unevenness of the protection current.

(4) Electrical insulation (between cathode and anode)

(5) Electrical continuity (between cathode systems)

(6) Magnesium alloy sacrificial anodes are prohibited for in-tank protection

Pictures of Magnesium Anode