What Is an Anode?

In a chemical battery, an electrode that can cause an oxidation reaction of an electrolyte is called an anode ^[1] . In addition, the electrode used in the electron tube to receive or accelerate electrons emitted from the cathode is also called the anode ^[2] .

Chinese name: anode
Foreign name: anode

Application range: Electrochemistry, electricity, etc.
Antonym: cathode

Basic concept of anode

Anode is a term for electrochemical reaction. The anode always exists corresponding to the cathode. The anode that is oxidized is called the anode. In the original cell, the anode is the negative electrode, and the electrons flow from the negative electrode to the positive electrode, and the current flows from the positive electrode to the negative electrode. In the anion. Corresponds to the cathode.

The anode refers to the electrode in the electrolytic cell that is connected to the positive electrode of the power supply. The power supply current enters the electrolytic cell through the anode along the external circuit. The electron moves in the opposite direction to the current. It leaves the anode under the action of an external power source and flows to the cathode through an external circuit. The anode always appears to be deficient due to the flow of electrons, so an oxidation process is performed on the anode to release electrons. There are two types of anodes: soluble anodes and insoluble anodes. Anodes for electrolytic refining, electroplating, and electrolytic liquid production (see copper electrolyte purification) are soluble anodes. They continue to undergo electrochemical dissolution during electrolysis, and eventually become residual poles. ^[3]

The adjective of this word is Anodic. For example, Anodic Cleaning is to place the work on the anode of the electrolyte, and use its corrosion effect and the oxygen bubbles generated at the same time to perform organic frictional cleaning actions. De translates as "anode" or "positive" and cathode translates as "cathode" or "negative". However, in the fields of chemistry and electricity, the concepts and principles of anode and cathode, and cathode and anode are different.

Anodizing

Anodizing refers to a process in which a certain metal (mainly aluminum) article is used as an anode, and electrolysis is performed in a suitable electrolyte to form an inorganic oxide film on the surface of the article. Metal oxide film has corrosion resistance, wear resistance, insulation and other properties, and can be used as a protective layer of metal or a bottom layer of paint. The oxide film can also absorb a variety of organic and inorganic dyes, making the surface of metal products appear bright colors and play a decorative role. Non-ferrous metals aluminum, magnesium and their alloys can be anodized. Aluminum oxide films have the best corrosion resistance. They are widely used in the surface treatment of aircraft, automobiles, electronic appliances, instrument parts, and daily necessities and crafts. ^[4]

Anodizing is the electrochemical oxidation of a metal or alloy. A metal or alloy article is used as an anode, and an oxide film is formed on its surface by electrolysis. Metal oxide films change the surface state and properties, such as surface coloration, increase corrosion resistance, enhance wear resistance and hardness, and protect metal surfaces. For example, aluminum anodization, aluminum and its alloys are placed in the corresponding electrolyte (such as sulfuric acid, chromic acid, oxalic acid, etc.) as the anode, and electrolysis is carried out under specific conditions and applied current. The aluminum of the anode or its alloy is oxidized, and a thin layer of alumina is formed on the surface, the thickness of which is 5-20 microns, and the hard anodized film can reach 60-200 microns. Anodized aluminum or its alloy has improved its hardness and abrasion resistance, up to 250-500 kg / mm2, good heat resistance, melting point of hard anodized film as high as 2320K, excellent insulation and impact resistance The breakdown voltage is as high as 2000V, which enhances the corrosion resistance and does not corrode for thousands of hours in the salt spray of = 0.03NaCl. The thin layer of the oxide film has a large number of micropores, which can absorb various lubricants, which is suitable for manufacturing engine cylinders or other wear-resistant parts. The film micropores have strong adsorption ability and can be colored into various beautiful colors. Non-ferrous metals or their alloys (such as aluminum, magnesium and their alloys) can be anodized. This method is widely used in mechanical parts, aircraft and automobile parts, precision instruments and radio equipment, daily necessities and architectural decoration.

Anode anode material

General anode materials include the following magnesium and magnesium alloys, zinc and zinc alloys, and aluminum alloys.

The characteristics of magnesium are particularly low polarizability, very negative potential, small density, and particularly large amount of power generation per unit weight. It is an ideal material for sacrificial anodes. It also has its shortcomings. The current efficiency is particularly low. Generally, it is only five percent Around ten. Magnesium also has a high self-dissolving tendency. When magnesium contains certain impurities, this self-dissolving tendency will increase.

Magnesium alloy is also one of the materials of sacrificial anode. Generally, the addition of manganese to magnesium can increase the potential of the alloy, and the dissolution of the anode of magnesium-manganese alloy is easier than that of high-purity distilled magnesium. Manganese can improve the corrosion resistance of magnesium. The principle is that manganese is easy to form compounds that are deposited on the bottom of the pot due to specific gravity segregation.

Anode application

Anode main performance

Extremely high electrochemical performance, uniform anode consumption, long life, and large power generation per unit mass. It is an ideal sacrificial anode material, suitable for cathodic protection of metal structures in soil and freshwater media.

Anode use range

In the sacrificial anode cathodic protection method, the magnesium anode can be used in soil or fresh water environment with a resistivity of 20 ohm.m to 100 ohm.m.