Ⅰ:Show details about Color Anodized Aluminum.
Ⅰ-A: What is Color Anodized Aluminum?
Aluminium is one of the most commonly used metals in the manufacturing industry, be it sheet metal, metal parts, machine parts or any decorative item. It is durable and has excellent resistance to corrosion and rust. Perhaps, this is why this metal is so popular as a raw material in most markets.
The process of converting raw mined elements into final products involves many steps. Of these, the most important is the application of color to the surface through the process of anodizing. It ensures durability of surface finish and overall appearance, and enhances appearance and texture.
If you are curious about the anodizing process of colored aluminum, please dig into this upcoming discussion to clarify all your doubts and gain a deeper understanding of it.
According to the product type, it can be divided into
- Color anodized aluminum sheet plate
- Color anodized aluminum coil
- Color anodized aluminum foil
- Color anodized aluminum strip
Ⅰ-B: How do you color anodized aluminum?
There are four ways to color anodized aluminum:
- 1. Dye: The freshly anodized section is immersed in a liquid solution containing dissolved dye. The porous anodic coating absorbs the dye. The intensity of the color is related to factors such as the thickness of the anode film, dye concentration, soaking time and temperature.
- 2. Electrolytic coloring (aka "two-step"): This is the process used by SAF. After anodization, the metal is immersed in a bath containing inorganic metal salts. A current is applied, causing the metal salt to deposit on the bottom of the hole. The final color depends on the metal used and processing conditions (the range of colors can be expanded by over-dying with organic dyes). Commonly used metals include tin, cobalt, nickel and copper.
- 3. Overall Tinting: This so-called one-step process combines anodizing and tinting to simultaneously form and color oxide cell walls in bronze and black shades, while being more wear-resistant than conventional anodizing.
- 4. Interference Coloring: An additional coloring procedure recently introduced that involves changes in the pore structure produced in sulfuric acid. Pore enlargement occurs at the bottom of the pores. Metal deposition at this location produces lightfast colors ranging from blue, green, yellow to red. Color is caused by optical interference effects, not light scattering as in the basic electrolytic coloring process.
Ⅰ-C: Benefits of using the anodized aluminum .
Ⅰ-C-1: Enhance beauty.
Anodizing will help improve the aesthetics of different aluminum end products. For example, decorative products made from this raw material have colored anodized surfaces so they can have the desired visual appeal to the end user.
Ⅰ-C-2: Reduce maintenance hassles.
Anodized material covers the surface of the material, so you don't have to worry about long-lasting maintenance troubles. So you can easily use the final product without worrying about regular maintenance and upkeep. Also, unlike bare metal surfaces, anodized surfaces will retain their surface texture for a long time without scratches, abrasions, etc.
Ⅰ-C-3: stable color.
The anodizing process introduces stability to the chromium as the particles are injected into the grooves on the surface generated by electricity. Therefore, the chromium layer is not subject to direct corrosion, further improving the color retention performance.
Ⅱ: Anodizing and Coloring of Color Anodized Aluminum.
Ⅱ-A: Anodized Aluminum Basics - Process Overview.
Anodization of aluminum is based on an electrolytic reaction, in which the material to be coated acts as the anode (positive electrode), while the material to be coated forms the cathode (negative electrode). The electrolyte (the liquid part of the battery) is primarily acidic, which facilitates and accelerates the process.
When current flows through the terminals into the electrolyte, an ionic reaction occurs, forming a coating on the anode's material surface.
Ⅱ-B: Process of anodizing aluminum with different colors.
The aluminium surface is coated with different chromes by anodizing, this series of steps will be explained in the next section. This will help you understand what's going on at the plant and how it ensures improvements in overall material strength, longevity and durability.
Step 1: Surface Cleaning and Etching.
The product is thoroughly washed in a large sink to remove any physical impurities from the metal surface. Liquid detergents are used because they do not cause leaching or surface corrosion of pure metals.
After cleaning is complete, blow dry the wet surface with a hair dryer and then etch. Etching is a process by which the surfaces of different products are polished multiple times until they become shiny and smooth in texture. Additionally, etching removes any other traces of metal on the aluminum surface, as they would cause an inappropriate chemical reaction.
Step 2: Apply the Thin Film Layer.
Once the surface is etched, an appropriate thin film is added as a base coat. Since there are three processes to form this build layer, the best process must be selected to help achieve all desired properties and characteristics. Since aluminum is primarily used in the manufacture of products in alloy form, the type of alloy will determine the size and shape of the membrane pores. On the other hand, electrolyte concentration, supply voltage and bath temperature determine the pore depth or total coating thickness.
Step 3: Add Color.
Four different methods were applied to add color to the build layer on the aluminum surface. Depending on the chosen process, several factors are affected, such as:
depth of film
Color retention ability
As the visual appeal and strength of the product will depend on the color coating, make sure to choose the coating process according to the requirements.
Step 4: Surface Sealing.
Sealing is always done at the end of the anodizing process. Since the color layers added to the constructed membrane will have many pores, it is important to seal their ports so that corrosive agents cannot directly contact the original metal surface.
For this, powder dyes are poured onto the surface of the product so they can seal all pores and maintain structural and visual integrity.