【Basic Knowledge 18】Briefly explain the differences between cathodic protection and anodic protection (prize quiz)

Anodic protection: A metal that is more reactive than the metal to be protected is used to form a galvanic cell, with the more reactive metal acting as the anode where electrons are lost, and the metal to be protected acting as the cathode where electrons are gained, such as zinc protecting iron. Cathodic protection: The metal to be protected is oxidized in a strongly oxidizing solvent, resulting in the formation of a passivation film on its surface that provides protection, such as the passivation film formed on the surface of stainless steel.

Both cathodic protection and anodic protection belong to electrochemical protection methods, but they each have distinct characteristics. As follows: ① In the case of cathodic protection, a deviation in potential only leads to a reduction in the effectiveness of protection; it does not accelerate the rate of corrosion. In the case of anodic protection, if the potential deviates from the passivation region, it will result in increased corrosion； ②In strongly oxidizing media, such as sulfuric acid and *ao acid, a very large current is required when cathodic protection is employed. However, strongly oxidizing media are more conducive to the formation of a passivation film, thereby enabling anodic protection. For example, the anodic protection of sulfur trioxide generators. ③During cathodic protection, if the potential becomes too negative, hydrogen embrittlement can occur in the equipment, which is extremely dangerous for pressurized systems. ④The auxiliary electrode for cathodic protection is the anode, which needs to dissolve. Chemical media are highly corrosive, and it is not easy to find a material that can resist corrosion under the action of anodic current in such highly corrosive environments; as a result, the use of cathodic protection in certain chemical media is limited. However, the auxiliary electrode of anodic protection is the cathode, which is also protected to a certain extent.

Both cathodic protection and anodic protection belong to electrochemical protection methods, but they each have distinct characteristics. As follows: ① In the case of cathodic protection, a deviation in potential only leads to a reduction in the effectiveness of protection; it does not accelerate the rate of corrosion. In the case of anodic protection, if the potential deviates from the passivation region, it will result in increased corrosion； ②In strongly oxidizing media, such as sulfuric acid and *ao acid, a very large current is required when cathodic protection is employed. However, strongly oxidizing media are more conducive to the formation of a passivation film, thereby enabling anodic protection. For example, the anodic protection of sulfur trioxide generators. ③During cathodic protection, if the potential becomes too negative, hydrogen embrittlement can occur in the equipment, which is extremely dangerous for pressurized systems. ④The auxiliary electrode for cathodic protection is the anode, which needs to dissolve. Chemical media are highly corrosive, and it is not easy to find a material that can resist corrosion under the action of anodic current in such highly corrosive environments; as a result, the use of cathodic protection in certain chemical media is limited. However, the auxiliary electrode of anodic protection is the cathode, which is also protected to a certain extent.

Cathodic protection: The metal is connected to the cathode of a power source; since the cathode continuously supplies electrons, it prevents the metal atoms from losing electrons, thus protecting the metal. Anodic protection: Place the more reactive metal A in contact with this metal B. Because A has stronger reactivity, AB forms a galvanic cell; during the reaction, it is A that loses electrons, thereby protecting B.

Anodic protection involves using a metal that is more reactive than the metal to be protected, thereby forming a galvanic cell. The more reactive metal acts as the anode, where electrons are lost, while the metal to be protected acts as the cathode, where electrons are gained; for example, zinc is used to protect iron. Cathodic protection protects the metal being protected by oxidizing it in a strongly oxidizing solvent, thereby forming a passivation film on its surface for protection, such as the passivation film that forms on the surface of stainless steel.

Both cathodic protection and anodic protection belong to electrochemical protection methods, but they each have distinct characteristics. As follows: ① In the case of cathodic protection, a deviation in potential only leads to a reduction in the effectiveness of protection; it does not accelerate the rate of corrosion. In the case of anodic protection, if the potential deviates from the passivation region, it will result in increased corrosion； ②In strongly oxidizing media, such as sulfuric acid and *ao acid, a very large current is required when cathodic protection is employed. However, strongly oxidizing media are more conducive to the formation of a passivation film, thereby enabling anodic protection. For example, the anodic protection of sulfur trioxide generators. ③During cathodic protection, if the potential becomes too negative, hydrogen embrittlement can occur in the equipment, which is extremely dangerous for pressurized systems. ④The auxiliary electrode for cathodic protection is the anode, which needs to dissolve. Chemical media are highly corrosive, and it is not easy to find a material that can resist corrosion under the action of anodic current in such highly corrosive environments; as a result, the use of cathodic protection in certain chemical media is limited. However, the auxiliary electrode of anodic protection is the cathode, which is also protected to a certain extent.

Anodic protection: A metal that is more reactive than the metal to be protected is used to form a galvanic cell, with the more reactive metal acting as the anode where electrons are lost, and the metal to be protected acting as the cathode where electrons are gained. Cathodic protection: The metal is connected to the cathode of a power source; since the cathode continuously supplies electrons, it prevents the metal atoms from losing electrons, thus protecting the metal.

Cathodic protection: The metal is connected to the cathode of a power source; since the cathode continuously supplies electrons, it prevents the metal atoms from losing electrons, thus protecting the metal. Anodic protection: Place the more reactive metal A in contact with this metal B. Because A has stronger reactivity, AB forms a galvanic cell; during the reaction, it is A that loses electrons, thereby protecting B.

①During cathodic protection, a deviation in potential only leads to a reduction in the effectiveness of protection; it does not accelerate the rate of corrosion. After the deterioration of anodic protection, if the potential deviates from the passivation region, corrosion will increase； ②In strongly oxidizing media, such as sulfuric acid and *ao acid, a very large current is required when cathodic protection is employed. However, strongly oxidizing media are more conducive to the formation of a passivation film, thereby enabling anodic protection. For example, the anodic protection of sulfur trioxide generators. ③During cathodic protection, if the potential becomes too negative, hydrogen embrittlement can occur in the equipment, which is extremely dangerous for pressurized systems. ④The auxiliary electrode for cathodic protection is the anode, which needs to dissolve. Chemical media are highly corrosive, and it is not easy to find a material that can resist corrosion under the action of anodic current in such highly corrosive environments; as a result, the use of cathodic protection in certain chemical media is limited. However, the auxiliary electrode of anodic protection is the cathode, which is also protected to a certain extent.

Cathodic protection: The metal is connected to the cathode of a power source; since the cathode continuously supplies electrons, it prevents the metal atoms from losing electrons, thus protecting the metal. Anodic protection: Place the more reactive metal A in contact with this metal B. Because A has stronger reactivity, AB forms a galvanic cell; during the reaction, it is A that loses electrons, thereby protecting B.