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There is no difference between the two.

Cathodic protection by sacrificial anodes is also known as the method of protecting the cathode by sacrificing the anode. The anode is sometimes referred to as the negative electrode, and the cathode is sometimes referred to as the positive electrode. Cathodic protection by sacrificial anodes is a method to prevent metal corrosion, where a more reactive metal is used as the protective electrode and connected to the protected metal to form a galvanic cell. The more reactive metal, acting as the anode, undergoes oxidation and is consumed, while the protected metal, acting as the cathode, avoids corrosion.

By using a more reactive metal as the protective electrode and connecting it to the protected metal to form a galvanic cell, the more reactive metal, serving as the anode, undergoes oxidation and is consumed, thereby protecting the metal acting as the cathode from corrosion. Because this method sacrifices the anode (the negative electrode of the galvanic cell) to protect the cathode (the positive electrode of the galvanic cell), it is called the sacrificial anode protection method.

Extended Information:

Requirements for Cathodic Protection by Sacrificial Anodes:

Sacrificial anodes are typically only economically applied to structures with low protection current requirements and in environments with low soil resistivity. Additionally, they are valuable when there is no power supply available or when it is not economical to use one.

Sacrificial anode materials suitable for use in soil are primarily magnesium, while in seawater, zinc and aluminum are used. To maintain stable current output and reduce anode grounding resistance, sacrificial anodes in soil should be surrounded with chemical backfill, mainly composed of 75% calcium sulfate, 20% bentonite, and 5% sodium sulfate.

Sacrificial anodes should not be buried in coke. When used in groups, the distance between anodes should be at least 3 meters. The soil cover thickness above the anode should be at least 0.6 meters. To measure the off-potential, sacrificial anodes should be connected to the pipeline through a test box. When sacrificial anodes are used near AC traction systems, the continuous AC induced voltage on the anode body should not exceed 20V.

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