In chemical batteries, the electrode that can cause the electrolyte to oxidize is called anode[1]。In addition, the electrode used to receive or accelerate electrons emitted from the cathode in the electron tube is also called anode[2]。
Anode is a term of electrochemical reaction. Anode always corresponds to cathode.happenoxidationThe pole of is calledanode(Anode), inPrimary batteryMedium, anode isnegative pole, the electron flows from the negative pole to the positive pole, and the current flows from the positive pole to the negative pole;stayElectrolytic cellMedium anode andpositive electrodeIt is the anion in the solution that oxidizes on the anode.Andcathode(category).
Anode refers to the electrode connected to the positive pole of the power supply in the electrolytic cell.The power supply current enters the electrolytic cell through the anode along the external circuit.The movement direction of the electron is opposite to the current. It leaves the anode under the action of the external power supply and flows to the cathode through the external circuit.The anode always appears electron deficient due to the flow of electrons, so the oxidation process of releasing electrons is carried out on it.According to whether the anode material changes during electrolysis, it can be divided into soluble anode and insoluble anode.Anodes used for electrolytic refining, electroplating and electrolytic solution making (see purification of copper electrolyte) are soluble anodes.In the process of electrolysis, they continuously undergo electrochemical dissolution, and finally become residual electrodes.[3]
The adjective of this word is Anodic, for example, Anodic Cleaning is toWork itemsPlaced on the anode of electrolytecorrosionAction, and simultaneously generatedOxygen bubbleOrganicFrictionOfcleanAction is called Anodic Cleaning.De is translated as "anode" or "anode", and "cathode" or "cathode".But in the field of chemistry and electricity, the concepts and principles of anode and cathode, cathode and anode are different.
anodic oxidation
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Anodizing refers to the process of taking a metal (mainly aluminum) product as anode and electrolyzing it in a suitable electrolyte to form an inorganic oxide film on the surface of the product.The metal oxide film has corrosion resistance, abrasion resistance, insulation and other properties, and can be used as the protective layer of metal or the bottom layer of paint.The oxide film can also absorb a variety of organic and inorganic dyes to make the surface of metal products appear bright colors and play a decorative role.Non ferrous metals such as aluminum, magnesium and their alloys can be anodized. Aluminum oxide film has the best corrosion resistance and is widely used for surface treatment of aircraft, automobiles, electronic appliances, instrument parts, daily necessities and handicrafts.[4]
Anodizing is a kind of metal or alloyelectrochemistryOxidation.Take metal or alloy parts asanode, usingelectrolysisTo form the surfaceoxidefilm。The metal oxide film changes the surface state and properties, such as surface coloring, improving corrosion resistance, enhancing wear resistance and hardness, and protecting the metal surface.for exampleAluminum anodizingPlace aluminum and its alloy in corresponding electrolyte (such as sulfuric acidChromic acid、oxalateAs anode under specific conditions and external conditionselectric currentElectrolysis is carried out under the action of.Anodic aluminum or its alloy is oxidized and formed on the surfacealuminaThin layer, the thickness is 5~20 μ m, and the hard anodic oxide film can reach 60~200 μ m.Anodized aluminum or its alloy improves its hardness and wear resistance, up to 250~500 kg/mm2, goodHeat resistanceThe melting point of hard anodic oxide film is up to 2320K, with excellent insulation, and the breakdown resistance voltage is up to 2000V, which enhances the corrosion resistance. It will not be corroded in ω=0.03 NaCl salt spray for thousands of hours.Oxide filmThere are a lot of micropores in the thin layer, which can absorb various lubricants, and is suitable for manufacturing engine cylinders or other wear-resistant parts;The membrane has strong micropore adsorption capacity and can be colored into various beautiful and beautiful colors.Nonferrous 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 material
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General anode materials include the following magnesium and magnesium alloys, zinc and zinc alloys, and aluminum alloys.
Magnesium is characterized by extremely low polarizability, negative potential, low density, and large power generation per unit weight. It is an ideal material for sacrificial anode. It also has its disadvantages: the efficiency of current is extremely low, generally only about 50%.Magnesium also has a high tendency of autolysis, which will increase when there are certain impurities in magnesium.
Magnesium alloy is also one of the materials of sacrificial anode. Generally, manganese is added to magnesium to increase the potential of the alloy, and the dissolution of magnesium manganese alloy anode is easier than that of high-purity magnesium distilled magnesium.Manganese can improve the corrosion resistance of magnesium. The principle is that manganese is easy to form compounds with the paste deposited on the bottom of the pot due to specific gravity segregation.
application
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main performance
With extremely high electrochemical performance, uniform anode consumption, long service life and large power generation per unit mass, it is an ideal sacrificial anode material, which is suitable for cathodic protection of metal structures in soil and fresh water media.
Scope of use
Among sacrificial anode cathodic protection methods, magnesium anode can be used in soil or fresh water environment with resistivity between 20 ohm m and 100 ohm m.
