Introduction to alodine
Alodine, also known as chromate anodizing, is a metal surface treatment technology, widely used in the surface treatment of aluminum and aluminum alloys. The process is performed by using chromic acid (CrO;) And other additives in the electrolyte, a voltage is applied to the aluminum to form a dense oxide film on its surface. This layer of oxide film not only has good corrosion resistance, wear resistance and decorative, but also can enhance the adhesion of aluminum and coating, improve the overall performance and service life of the product. Because of its unique properties, chromic acid anodizing has been widely used in aerospace vehicle manufacturing, architectural decoration, electronic communication and other fields.
Alodine process
1.Pretreatment
Cleaning: Remove grease, dust and other contaminants from the surface of the workpiece. This step usually involves degreasing and washing.
Chemical degreasing: Use an alkaline solution to remove oil.
Pickling: Removal of oxide and minor corrosion, sometimes using mechanical methods such as sandblasting to remove surface defects.
Neutralization: If pickling is performed, neutralization is required to remove residual acid.
Activation treatment: The use of appropriate activators to promote the formation of oxide film.
2.Anodizing
Anodizing tank preparation: Prepare an electrolyte containing chromic acid or its salts, commonly a mixture of chromic anhydride (CrO3) and sulfuric acid (H2SO4).
Preheating: preheating the workpiece to a certain temperature helps to form a uniform oxide film.
Power on: the workpiece is placed in the electrolyte as an anode and a direct current is applied. At this point, the aluminum surface begins to form an oxide film.
Control parameters: Adjust parameters such as current density, electrolyte temperature and processing time according to the thickness and quality of the desired film.
3.Post-processing
Sealing treatment: In order to improve the corrosion resistance of the film layer and close the pores, hot water sealing or boiling water sealing is usually carried out, and sometimes substances such as water glass are added to further improve the sealing effect.
Drying: Dry the treated workpiece to remove surface moisture.
4.Test
Check the appearance of the processed workpiece to ensure that there are no defects, such as cracks, spots, etc.
It may also include film thickness testing, adhesion testing, etc.
5.Packing into storage
Proper packaging of qualified workpieces to prevent damage during storage and transportation.
Alodine gallery
Alodine advantages
1. Excellent corrosion resistance
The chromic acid anodizing oxide film is very dense, which can effectively isolate the contact between the metal and the corrosive media in the environment (such as oxygen, water, salt spray, etc.), thus significantly improving the corrosion resistance of aluminum. This is particularly important for components that operate in harsh environmental conditions.
2. Good wear resistance and insulation
The chromic acid anodized film is not only corrosion resistant, but also has high hardness and wear resistance, which can effectively resist mechanical wear and scratches and extend the service life of the product.
Chromic acid anodizing process is relatively mature, the parameter adjustment range is wide, can be customized according to the specific needs of different thickness, color and performance of oxide film, to meet the requirements of different application fields.
3. Excellent decoration
By adjusting the anodizing process parameters, the color depth and uniformity of the film layer can be controlled, so that the aluminum surface presents a rich color and luster, and has a good decorative effect. This feature is especially popular in architectural decoration, household goods and other fields.
4. Enhance the adhesion of the coating
Chromic acid anodized film can improve the microstructure of aluminum surface, improve the adhesion with organic coatings (such as paint, varnish, etc.), ensure that the coating is not easy to fall off, and improve the overall quality and beauty of the product.
5. Low cost and high efficiency
Compared with other surface treatment methods, the chromic acid anodizing process is mature and stable, the production cost is relatively low, and the added value and market competitiveness of the product can be significantly improved.
Alodine application
Aerospace parts: Many parts of an aircraft, such as wings, fuselage structures, interior trim, etc
Military equipment: Tanks, armored vehicles, firearms and other military hardware are often anodized with chromic acid to enhance their protection and ensure normal operation in a variety of harsh environments.
Electronic devices: smart phones, laptops and other consumer electronic products shell, not only can beautify the appearance of the product, but also enhance its scratch resistance and corrosion resistance.
Building hardware: Door and window handles, hinges, slides and other building hardware through chromic acid anodization, can maintain a good appearance and function in the case of long-term exposure to the outdoor environment.
Medical equipment: Medical supplies such as surgical instruments and diagnostic equipment, after anodizing, are easier to clean and disinfect, and can be maintained in good condition under frequent use.
Transportation: The interior decoration parts and external parts of vehicles such as cars, trains and buses can effectively resist wear and environmental erosion in daily use through chromic acid anodizing.
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