Impressed current cathodic protection

Transistor potentiostat output is stable, no noise, high control accuracy, but the circuit is more complex. Many materials can be used as auxiliary anodes, such as scrap steel, graphite, lead-silver alloy, high-silicon cast iron, platinum-coated titanium, platinum-coated niobium, and mixed metal oxide electrodes.

The steel equipment to be protected is used as the cathode and an insoluble electrode as the auxiliary anode. Both are placed in an electrolyte solution and connected to an external DC power supply. After electrification, a large number of electrons are forced to flow to the protected steel equipment, resulting in the accumulation of negative charge (electron) on the steel surface. As long as the applied voltage is strong enough, the galvanic battery current generated by metal erosion can not be transported, thus preventing the erosion of steel.

This is one of the electrochemical protection laws, also known as cathodic protection laws.

Dc power supply

Impressed current cathodic protection system consists of the following parts: (1) DC power supply, (2) auxiliary anode, (3) reference electrode. SCR potentiostat has large power and small volume, but its overload capacity is not strong. Magnetic saturation potentiostat fastening durable, overload capacity is strong, but the volume is relatively large, processing technology is more complex.

3. It has a high risk of causing stray current interference, which can lead to overprotection, damage of anti-corrosion layer and hydrogen embrittleness of pipes.

In an impressed current cathodic protection system, an uninterrupted DC power supply is required to provide the protection current. At present, there are two widely used rectifier and potentiostat. In engineering, the commonly used reference electrodes are copper/saturated copper sulfate, silver/silver halide and zinc reference electrodes, etc., these reference electrodes have their own characteristics, combined for different occasions. Chemical plants in yan clothing acidic solution containers or pipelines, also commonly used this method.

Reference electrode

The role of the auxiliary anode is to transfer the DC current output from the DC power supply from the medium to the metal structure to be protected. Generally, when the working condition of the structure to be protected (such as the immersed area, water quality, etc.) is basically unchanged or changes very little, you can use the manually controlled rectifier; But when the working condition of the structure is often changing, the potentiostat should be used automatically to make the potential of the structure always in the best protection range. In addition, in order to make the anode output protection current more average, to avoid the structure around the anode produced over protection, sometimes near the anode also must be coated with anode shielding layer

Impressed current cathodic protection system (this department is suitable for engineering electronics, not suitable for daily study)

This method is mainly used to prevent erosion of metal equipment in soil, sea water and river water.

Impressed current cathodic protection

Schematic diagram of impressed current cathodic protection

Impressed current cathodic protection

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2, need external power supply, continuous power supply;

1. Compared with the sacrificial anode, higher detection and maintenance costs are required;

disadvantages

7, underground or water pile and sheet pile;

6. Underground storage tank;

5. Outsole of the storage tank on the ground;

4. The inner wall of the water storage tank;