Sacrificial anode refers to the electrochemical theory that when the metal is used as the anode, the anode (metal) is gradually consumed with the current flowing out. Sacrificial anodes are generally only used economically in structures with low protection current requirements and in low soil resistivity environments.
Sacrificial anodes are generally only used economically in structures with low protection current requirements and in low soil resistivity environments. In addition, it has application value when there are no power supply conditions or uneconomical conditions.
The sacrificial anode materials suitable for use in soil are mainly magnesium, and in seawater are zinc and aluminum. In order to keep the current output as stable as possible and reduce the anode grounding resistance, chemical packing materials should be used around the sacrificial anode in the soil, which is mainly composed of 75 percent calcium sulfate, 20 percent bentonite and 5 percent sodium sulfate. Sacrificial anodes cannot be buried in coke. When used in groups, the distance between anodes should be at least 3m. The thickness of the soil cover on the top of the anode shall be at least 0.6m. In order to be able to measure the power failure potential, the sacrificial anode should be connected to the pipeline through the measuring box. When the sacrificial anode is applied in the vicinity of the AC traction system, the AC induced continuous voltage on the anode body should not exceed 20V.
1. The potential is negative enough, but not too negative to avoid hydrogen evolution reaction in the cathode area;
2. The polarizability of the anode should be small, and the current output of the potential pole should be stable;
3. The capacitance of the anode material should be large;
4. Must have high current efficiency;
5. Dissolve evenly. easy to fall off;
6. The material is cheap and the source is sufficient.
7. The corrosion products produced should be non-toxic and harmless, do not pollute the environment, and have no danger of public nuisance.
