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In the application of the sacrificial anode protection method, Nanjing Xuhang provides you with escort services. Let's analyze it for you:

The cathodic protection method using sacrificial anodes, also known as the sacrificial anode protection method, is a technique to prevent metal corrosion. It involves connecting a more reactive metal as the protective electrode to the metal to be protected, forming a galvanic cell. The more reactive metal acts as the anode, undergoing oxidation and being consumed, while the protected metal serves as the cathode, thus avoiding corrosion. The specific method of sacrificial anodes is as follows: a more reactive metal is used as the protective electrode and connected to the metal to be protected to form a galvanic cell. The more reactive metal, acting as the anode, is oxidized and consumed, while the protected metal, as the cathode, avoids corrosion. This method sacrifices the anode (the negative electrode of the galvanic cell) to protect the cathode (the positive electrode of the galvanic cell), hence the name sacrificial anode protection method.
Sacrificial anodes are typically used economically only for structures with low protection current requirements and in low-resistivity environments. They are valuable when power supply conditions are unavailable or uneconomical. The primary materials for sacrificial anodes in soil are magnesium, while in seawater, zinc and aluminum are used. To maintain stable current output and reduce anode grounding resistance, chemical backfill materials, mainly composed of 75% calcium sulfate, 20% bentonite, and 5% sodium sulfate, should be used around sacrificial anodes in soil. Sacrificial anodes should not be buried in coke. When used in groups, the spacing between anodes should be at least 3 meters, and the soil cover thickness above the anodes should be at least 0.6 meters. To measure the off-potential, sacrificial anodes should be connected to the pipeline through a test station. When sacrificial anodes are used near AC traction systems, the continuous AC induced voltage on the anode body should not exceed 20V.

For underwater metal structures using sacrificial anodes, measurements are typically taken every three months, primarily to assess the potential at various measurement points and the output current of the anodes. It is also important to note that anodes connected to underwater structures via cables should have their cables regularly inspected to avoid damage caused by waves or vessels and to ensure timely repairs. When the protection potential of the structure relative to water is not sufficiently negative, the anodes need to be replaced, and other anodes should be considered for inspection. For sacrificial anodes fixed to underwater structures, output current cannot be measured directly and must be inferred from protection potential measurements. The degree of seawater pollution can sometimes affect the performance of the anodes.

In metal protection, we learn about the "sacrificial anode cathodic protection method" and the "impressed current cathodic protection method." Regardless of the method, there is always an anode involved. In the sacrificial anode method, a more reactive metal than the cathode is used as the "scapegoat anode." The anode in the impressed current method is called the auxiliary anode, which seems to have fewer requirements, as almost any material can serve as the anode. However, chemistry is a discipline closely linked to practical applications, and we must consider real-world conditions.

Sacrificial anodes are destined to be "sacrificed," while auxiliary anodes may not necessarily be "sacrificed." If auxiliary anodes experience significant損耗, replacing them in large-scale equipment would be time-consuming, labor-intensive, and costly.

Pei Yingying    1862587   9268