What is anodizing?

Anodizing is a process of electrochemical oxidation of metals or alloys. In this process, a metal or alloy part is used as an anode to form an oxide film on its surface by the action of an applied electric current under specific electrolyte and process conditions. This oxide film has protective, decorative and other functional properties. If not otherwise specified, anodizing usually refers to sulfuric acid anodizing.


Anodizing working principle

The principle of anodizing mainly utilizes electrolysis. In the process of anodic oxidation, the metal product is first placed in an acidic or alkaline electrolyte as an anode and connected to a piece of more active metal (such as aluminum) as a cathode to form an electrolytic cell. Then, under the action of an applied voltage, an oxidation reaction begins to take place on the surface of the anode, and an oxide layer gradually forms on the surface of the metal. At the same time, the metal ions in the electrolyte gradually decrease with the formation of oxidation products.

Anodizing is divided into three different types:

There are various methods of anodizing, including electrochemical anodizing, high-temperature oxidizing, electron beam radiation oxidizing, wet oxidizing, and mixed oxidizing. These methods are based on different materials and requirements, and different treatments can be selected to obtain the best oxide layer effect

Aluminum and titanium are the most commonly anodized metals, but other non-ferrous metals can also be subjected to this process. According to the anodizing standard MIL-A-8625, there are three different types of anodizing:

  • Type I: Chromic acid is used to produce a very thin oxide layer.、
  • Type II: Sulfuric acid is used to produce a thicker oxide layer suitable for coloring.
  • Type III: Uses the same process as Type II, but produces a thicker oxide layer. This is often referred to as “hard anodizing”.

Benefits of anodized aluminum

Superior anti-corrosion performance

The oxide film on the surface of aluminum can effectively isolate the external oxygen and moisture erosion, thus improving the corrosion resistance of aluminum and prolonging its service life. This kind of oxide film has better performance than the naturally formed oxide film, and the thickness of the film and the quality of the sealing hole directly affect its corrosion resistance.

Enhanced hardness and wear resistance

After anodic oxidation treatment of aluminum, the hardness of the oxide film on its surface is significantly increased, much higher than that of untreated aluminum. This increase in hardness enables aluminum to resist the physical and chemical influences of the external environment in the process of use, and has excellent wear resistance.

Improved aesthetics

Anodic oxide films can change the color and gloss of aluminum to a certain extent, making it more aesthetically pleasing and attractive. In addition, the oxide film can be dyed and tinted, so as to obtain and maintain a colorful appearance and increase the decorative effect and use value of aluminum.

Excellent insulation performance

Aluminum anodic oxide film is an insulating film with high electrical resistance, which can effectively prevent the electrochemical reaction when the aluminum material is in contact with other metal materials or electrolyte, and improve the safety of using aluminum material.

Good processing performance

The hardness of anodized aluminum sheet is moderate, easy for bending and forming and continuous high-speed stamping, and it can be directly processed into products without complicated follow-up treatment, thus shortening the product production cycle and reducing the production cost.

Strong applicability

Anodized aluminum has a wide range of applicability and can be used in a variety of fields such as metal aluminum ceilings, curtain wall aluminum panels, aluminum-plastic panels, fireproof panels, honeycomb aluminum panels, aluminum veneer, electrical panels, cabinet panels, furniture panels and so on.

Anodizing Applications


Construction Industry

Anodic oxidation process is widely used in the construction industry for the surface treatment of building materials, such as aluminum alloy doors and windows, curtain walls, stair handrails and so on. This treatment can significantly enhance the corrosion resistance and aesthetics of these materials, and improve the overall quality and appearance of the building.

Electronic products

Anodizing is also widely used in the field of electronic products. It can be used in the production of electronic product shells, such as cell phones, tablet PCs, televisions, etc., to enhance their scratch resistance and durability. The anodizing process not only enhances the physical properties of the product, but also gives it a beautiful appearance.

Automotive Industry

In automotive manufacturing, the anodizing process is commonly used in the surface treatment of automotive wheels, decorative strips, grills and other parts. This not only improves the corrosion resistance and beautiful appearance of the parts, but also helps to improve the overall quality and market competitiveness of the automobile.


Anodizing also plays an important role in the aerospace field. It can be applied to the surface treatment of aerospace materials to improve the performance stability, quality reliability, environmental adaptability and service life of materials, thus ensuring the safety and reliability of aircraft.

In addition, anodizing also has a wide range of applications in other fields, such as CNC machine tools and robots, marine engineering equipment and high-tech ships, kitchenware, lighting equipment, and nameplates and decorative panels. All these applications fully demonstrate the superiority of anodizing process in enhancing material performance, aesthetics and extending service life.

The surface properties of anodized aluminum are significantly enhanced, allowing the application range and service life of aluminum to be significantly expanded. This process technology has become an important method for surface treatment of non-ferrous metals and alloys, providing strong support for the development of many industries.

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