What Are The Common Colors of Anodized Aluminum?

What are the common colours of anodized aluminum?

Brown: brown oxide film has good cathodic stripping resistance, the thickness of deposition is generally 3-25μm, the colour is darker and the quality is better.

Black: the thickness of black oxide film is generally 5-20μm, the colour is deep and uniform, with good abrasion resistance and corrosion resistance.

Gold: the thickness of gold oxide film is thinner, generally 1.5-5μm, the colour is sharp and soft, with certain decorative properties.

Red: red oxide film is formed on the basis of gold oxide film after special treatment, the thickness is generally between 2-5μm, bright colour.

Natural colour: natural colour oxide film is formed without dyeing or special treatment, with uniform and detailed silver appearance.

Silver-white: Aluminum profile oxide film will appear silver-white or light grey when the thickness is less than 10μm.

Blue: blue anodized aluminum sheets are generally dyed by adding blue dyes, which are brightly coloured and have a youthful and energetic visual effect.

Green: Green anodized aluminum sheets are dyed by adding green dye, presenting a natural and fresh feeling.

Purple: purple anodized aluminum sheets are obtained by adding purple dye, which is a mysterious and aristocratic colour.

Colorless: Colorless anodize oxidation refers to the formation of transparent oxide film on the surface of aluminum alloy, which does not change the surface colour of aluminum alloy and produces a transparent and colorless effect.

How does good or bad paint affect anodized aluminum sheets?

Positive effects

Enhanced protection: High-quality paint provides an additional layer of protection for anodized aluminum sheets, increasing their corrosion and weathering resistance. The paint layer extends the life of the aluminum sheet by effectively blocking the ingress of moisture, oxygen and other corrosive substances.

Appearance beautification: Paint can provide a rich choice of colors and textures, making the appearance of anodized aluminum sheets more beautiful and varied. Appropriate paint treatment can also enhance the overall grade and value of the product.

Enhancement of functionality: certain special function paints, such as anti-fingerprint, wear-resistant, anti-slip, etc., can further enhance the functionality of anodized aluminum sheets to meet the use requirements in specific scenarios.

Negative effects

Adhesion problems: If the paint has poor adhesion, it is easy to flake and peel during use, which not only affects the aesthetics, but also may damage the protective layer on the surface of the anodized aluminum plate and accelerate its corrosion.

Impact on electrical conductivity: For anodized aluminum sheets that need to maintain good electrical conductivity, improper paint treatment may affect their electrical conductivity. Although anodizing itself forms an oxide film on the surface of the aluminum sheet, the presence of a paint layer may increase the resistance and reduce the conductivity efficiency.

Environmental pollution: The use of poor-quality paints or paints that do not meet environmental standards may be harmful to the environment and human health. These paints may contain hazardous substances, such as volatile organic compounds (VOCs), which are released into the air during use, posing a potential threat to the environment and human health.

Countermeasures

Choose high-quality paints: When choosing paints for anodized aluminum sheets, priority should be given to products with reliable quality, strong adhesion and good weather resistance. At the same time, it is also necessary to pay attention to the environmental performance of the paint to ensure that it meets the relevant standards and regulatory requirements.

Strict construction control: In the process of paint construction, the construction environment and conditions should be strictly controlled to ensure that the paint can be uniformly and firmly attached to the surface of the anodized aluminum sheet. At the same time, it is also necessary to pay attention to the safety protection measures in the construction process to avoid the paint causing harm to human body and environment.

Regular maintenance and inspection: For the anodized aluminum plate which has been painted, regular maintenance and inspection should be carried out to find and deal with the problems of paint flaking and peeling in time. In addition, attention should be paid to keep the surface of aluminum sheet clean and dry to avoid the accumulation and erosion of moisture and other corrosive substances.

What are the international standards for anodized aluminum sheets?

International standards for anodized aluminum sheets cover a wide range of aspects, including properties of the oxide film, testing methods, production processes and more. The following is an overview of some major international standards:

1. Performance standards

Performance standards for anodized aluminum sheets usually include requirements for oxide film thickness, hardness, corrosion resistance, abrasion resistance, appearance and so on. These standards are designed to ensure that anodized aluminum sheets exhibit good performance in a variety of application environments.

2. Testing method standards

For the detection of anodized aluminum plates, there are various international standard methods. These methods are used to assess the thickness of the oxide film, sealing quality, wear resistance, corrosion resistance and other key indicators. The following are some specific testing method

standards:

Oxide film thickness inspection:

ISO 2128:2010: Measurement of anodic oxide film thickness by non-destructive testing with split-beam microscopy.

Sealing quality inspection:

ISO 2931:2010: Evaluation of the sealing quality of anodic oxide films by impedance or conductivity methods.

ISO 3210:2010: Evaluation of the sealing quality of anodic oxide films by using the mass loss after impregnation with phosphorus chromic acid solution.

Abrasion resistance test:

Usually follow GB/T 5237.4-2008 ‘Determination of abrasion resistance of anodic oxide film of architectural aluminum profiles’ or other similar standards.

Corrosion resistance test:

ISO standards and ASTM standards (such as ASTM B117) have test methods on corrosion resistance, such as salt spray corrosion test.

3. Production process standards

Although specific production processes may not be directly specified in international standards, requirements for the quality of the final product will be set out, thus indirectly guiding the development of production processes. In addition, some industry associations or organizations may issue recommended practices or best practices for the production process of anodized aluminum sheets.

4. Other Related Standards

In addition to the above performance, testing methods and production process standards, there are some other international standards related to anodized aluminum sheets, such as the standard for terms and definitions (e.g. ISO 7583-2013) and the general specification for aluminum anodic oxide film (e.g. ISO 7599:2010). These standards help to unify industry terminology, standardise product quality, and facilitate international trade and technical exchanges.

Which companies are strongest in the field of anodized aluminum sheets?

Aluminum Corporation of China Limited (Chalco): As the world's second largest alumina producer, Chalco has a prominent position in the anodized aluminum sheet sector. Its main businesses are located in more than 20 countries and regions around the world, and it has leading alumina, electrolytic aluminum and aluminum processing capacities. Chalco Group not only occupies an important position in the domestic market, but also enjoys a strong reputation in the international market.