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Anodic oxidation, the electrochemical oxidation of metals or alloys. In the real process, for aluminum alloy anodic oxidation, more, usually used in daily life, military industry, aerospace, communications equipment, and precision instrumentation manufacturing industry. Because of the characteristics of this process, the surface of the aluminum parts to produce a hard protective layer, so that the corrosion resistance of metal materials, wear resistance, decorative, insulation, as well as heat dissipation have been significantly improved.
This article will discuss how anodizing works, its uses, material compatibility, and the advantages and disadvantages it has.
What is anodic oxidation?
Anodic oxidation, the electrochemical oxidation of metals or alloys. Anodic oxidation is an electrochemical process in which a dense oxide film is formed on the surface of aluminum and its alloys by means of an electric current to improve corrosion resistance, abrasion resistance and decorative properties.
Depending on the electrolyte and temperature, it can be divided into acidic, alkaline, normal temperature and high temperature anodic oxidation. It is widely used to improve the corrosion resistance, abrasion resistance, decorative and insulating properties of metals and has development prospects. Controlling the thickness of the protective layer after anodizing is the key, and factors such as metal type, treatment conditions, electrolyte composition and concentration affect its thickness.
When grinding and polishing, it is necessary to choose the appropriate process according to the thickness of the oxidized layer, in order to play the best protection and beautification effect.
How anodizing works？
Through the surface of some non-ferrous metals, the oxidation reaction occurs through the action of the current after the formation of the oxide protective film, such as: aluminum and its alloys in the corresponding electrolyte and specific process conditions, due to the action of the applied current, the formation of a layer of oxide film on the aluminum products (anode) process. Anodizing usually refers to sulfuric acid anodizing.
In order to overcome the defects of aluminum alloy surface hardness and abrasion resistance, expand the application range and prolong the service life, surface treatment technology has become an indispensable link in the use of aluminum alloy, and the anodic oxidation technology is the most widely used and successful.
Classification of anodizing?
According to the difference of electrolyte, anodizing can be divided into two types: acid anodizing and alkaline anodizing. The oxide film formed by acid anodizing is thinner and usually used for decoration and protection, while the oxide film formed by alkaline anodizing is thicker and mostly used in the field of abrasion resistance and insulation.
In addition, according to the temperature of the electrolyte, anodizing can be divided into normal temperature anodizing and high temperature anodizing. The oxide film formed by high temperature anodizing has better hardness and wear resistance, but requires higher energy consumption and equipment investment.
What is the use of anodizing?
One of the main reasons for anodizing is to increase the corrosion resistance of metals. By forming an oxide layer on the surface of the metal, oxygen from the environment cannot reach the metal, thus preventing corrosion. The anodizing process is used for corrosion resistance due to its durability. The oxide layer formed as a result of anodizing is part of the metal rather than a coating applied to it. This makes the oxide layer stronger and more durable than a coating. Finally, anodizing can be used to protect the metal while keeping it dimensionally stable.
This is because anodizing does not significantly increase the thickness of the part compared to coatings used to protect the metal. This thin active layer can be achieved by anodizing because the oxide layer penetrates the metal, as the treatment is part of the metal substrate, rather than a coating applied to the substrate.
1. Improve corrosion resistance: the oxide film formed by anodic oxidation has high density and stability, which can effectively block the erosion of water and corrosive media on the substrate, and improve the corrosion resistance of aluminum and its alloys.
2. Improve abrasion resistance: the anodic oxidation film has high hardness and good abrasion resistance, which can improve the abrasion resistance of aluminum and its alloy and prolong its service life.
3. Improvement of decorative properties: by adjusting the composition of electrolyte and process parameters, anodic oxide film of different colors and textures can be prepared to improve the decorative properties of aluminum and its alloys.
4. Insulation performance: under certain conditions, the anodic oxidation film can have good insulation performance, which can be used to prepare insulating materials and electronic devices.
5. Other applications: In addition to the above applications, anodic oxidation can also be used in the preparation of anti-counterfeiting signs, optical components and other fields.
What are the advantages of anodizing?
1, good corrosion resistance: anodic oxidation film is stable, which can effectively prevent the substrate from being oxidized and corroded, and improve its durability.
2, good mechanical properties: anodic oxidation film hardness, wear resistance, can improve the strength of the substrate, stiffness and wear resistance.
3, good electrical insulation: anodic oxidation film has good electrical insulation properties, can prevent current leakage, improve electrical performance.
4, good decorative performance: anodic oxidation film has good surface treatment effect, can be dyed, color and other treatments according to the need, has good decorative performance.
5、Environmental performance: anodic oxidation process does not require the use of harmful substances, with good environmental performance.
6, simple process: anodic oxidation process has the advantages of simple process, low cost, easy to master, etc., suitable for mass production.
