So far, there are three main materials that can provide cathodic protection for carbon steel structures: magnesium, zinc, and aluminum. Each of these anodes has its own characteristics and is suitable for different fields and environments.
1.Applications of magnesium anodes.
Magnesium anode is suitable for soil resistivity less than 50m of the protection of metal components in soil and fresh water, but the maximum resistivity should not exceed 100 m。
According to the different engineering requirements, the magnesium anode can be divided into two types: cast type (block) and extruded type (magnesium strip).
2 Applications of zinc anodes.
The potential difference between the zinc anode and the steel is about 025V, the potential difference is relatively small, so it is generally only used for soil resistivity less than 15m of soil or seawater, the maximum resistivity should not exceed 50 · m. It can also be used as a grounding battery or grounding electrode. Whether it is a block or a strip zinc anode, it should be placed in the filler.
According to different engineering requirements, zinc anodes can be divided into two types: cast type (block) and extruded type (zinc strip). Such as magnesium anode.
3.Applications of aluminum anodes.
The theoretical anode efficiency is affected by the current density on the anode surface. The environment using aluminum anode must contain a certain amount of chloride ions, and the chloride ion content must be greater than 11550 ppm (1ppm=10-6), which is about 33% of the chloride ion content in seawater, and aluminum anode cannot be used in fresh water and soil. Aluminum anode is mainly used for marine structures, ships, docks, bridge steel bars and storage tank inner wall protection, the new aluminum anode can be used in fresh water, but its long-term performance has yet to be verified.