Anodize
"What is aluminum anodizing?"
Anodizing is a process in which a stable layer—generally an oxide with protective or decorative properties—is formed on the surface of metals.
Aluminum anodizing, or anodic aluminum oxide, is an electrochemical process in which a thin oxide layer is formed on aluminum parts. This results in the following changes:
Increased strength and resistance to corrosion
Enhanced surface hardness
Creation of electrical insulation
Alteration of surface appearance
Modification of certain physical properties
Anodizing has been performed for many years on metals such as titanium, zinc, tungsten, and especially aluminum. This process is also applied to ferrous metals, but it is not as common as with aluminum. Coloring anodized aluminum parts offers many advantages in terms of aesthetics and mechanical properties. Visually, the effects are quite striking, and the finish is permanent. It never scratches or fades and does not require touch-ups. Additionally, it is environmentally friendly.
Aluminum anodizing steps
To ensure a more effective and uniform or porous anodized coating, surface defects on the metal must first be removed before starting the anodizing process.
Mechanical finishing: In the first step, the part is shaped as needed so that the oxide layer does not get damaged due to hammering or deformation.
Cleaning the part: Next, the part must be thoroughly degreased and cleaned with alkaline solutions to prevent corrosion and ensure the anodizing process is effective.
Desmutting or acid cleaning: After degreasing and cleaning, it is recommended to remove any smut or residues on the aluminum using nitric acid to improve the quality of the process.
Polishing: In the fourth step, the part is polished and brightened using an electrochemical method.
Anodizing: After completing the previous steps properly, we move on to the main phase. As explained at the beginning, the part is anodized in an electrolyte bath using electrical current, forming a layer of aluminum oxide that enhances corrosion resistance.
Coloring: It is recommended to coat the anodized part with a layer of color. This can be done in two ways: using organic salt-based dyes or inorganic pigment dyes.
Sealing: After coloring, the part is sealed to prevent any potential corrosion and to preserve the color. There are various sealing methods, but the most common one involves using boiling water along with a metal salt solution. In this step, the pores are hydrated and sealed.
Drying the part: At the end of the anodizing process, the part should be dried quickly at a low temperature to prevent cracking of the oxide layer or the color coating.
Aluminum anodizing services
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Hard anodized aluminum
The choice between hard chrome plating and hard anodizing is highly relevant in certain specialized industries. This applies both in the aerospace industry, where parts are made for harsh conditions, and in the automotive industry, where both visual appeal and flexibility are very important.
Hard anodizing of aluminum occurs when the aluminum oxide coating has a thickness greater than 25 microns. Hard anodizing is applied to aluminum parts that require increased resistance to wear and corrosion or specific electrical and thermal properties. For example, this method is used in the aerospace and petrochemical industries, as well as in the manufacturing of marine equipment.
