anodizing One of the obvious and lasting characteristics of most metals to which they have a strong and high tendency is the property of oxidation or rusting of metals. Oxidation of metals creates layers of metal oxide that are generally stable and cover the surface of the metal. The presence of this layer on the metal surface makes the rest of the metal parts more protected from corrosion. Aluminum is no exception to this rule, and a non-porous layer of alumina of the formula Al2O3 is formed on it immediately after cutting the metal surface.
This layer has high adhesion and protection and is very thin. Anodizing is actually an operation in which the thickness of the oxide layer of the coating is increased to several thousand times in relation to the original layer in order to multiply its positive properties. Strengthening the thickness of the metal oxide layer is possible in two ways.
In the first method, also called the anodizing or anodizing method, a dense metal oxide is formed under controlled conditions or after a metal oxide is formed, it is impermeable and compacted during operation. In another method, known as the chemical method, metal oxides create stability on the metal surface by methods such as chromatization.
aluminium anodizing process paint anodizing for industry
• Sulfuric acid anodizing operation
This method is one of the most common methods of anodizing metal. The layer created by this method on metals is very suitable for use as a base for painting and has good absorption. The thickness of the layer through the operation of anodizing with sulfuric acid is between 0.01 to 0.001 inches.
This type of anodizing operation is energetic and economical compared to other methods, has a high color absorption capacity and is heavier than anodizing with chromic acid. This type of anodizing is used in the body of hydraulic valves, hard equipment, mechanical tools, optical components to eliminate light reflection in these components, computer and electronic components and military equipment.
aluminium anodizing process paint anodizing for industry
• Chromic acid anodizing operation
This type of operation is suitable for parts with closed tolerances, for galvanizing and for assembly and welding of parts, and is used for the manufacture of aerospace components, high-precision machine components and for painting.
• Hard anodizing operation or hard disk
This type of anodization creates a layer of aluminum oxide on the metal surface and is an electrochemical method. Features of this method include corrosion resistance, electrical resistance, thickness greater than 200 microns, and high hardness and wear.
The use of anodized parts in hard anodizing operations includes use in the automotive and motor industries, the aerospace and military industries, electronics and kitchen appliances, medicine, textiles, chemicals, construction and marine industries, etc.
aluminium anodizing process paint anodizing for industry
Aluminum anodizing material
Anodizing operations are classified into three types according to MIL-8625:
• Sulfuric acid anodizing operation
This method is one of the most common methods of anodizing metal. The layer created by this method on metals is very suitable for use as a base for painting and has good absorption. The thickness of the layer through the operation of anodizing with sulfuric acid is between 0.01 to 0.001 inches.
This type of anodizing operation is energetic and economical compared to other methods, has a high color absorption capacity and is heavier than anodizing with chromic acid. This type of anodizing is used in the body of hydraulic valves, hard equipment, mechanical tools, optical components to eliminate light reflection in these components, computer and electronic components and military equipment.
• Chromic acid anodizing operation
This type of operation is suitable for parts with closed tolerances, for galvanizing and for assembly and welding of parts, and is used for the manufacture of aerospace components, high-precision machine components and for painting.
• Hard anodizing operation or hard disk
aluminium anodizing process paint anodizing for industry
Advantages of anodizing
The Andean process has many advantages that are mentioned in this article: • Increases the absorption and adhesion of paints to metal
With the addition of metal, the layers that form on the surface of the metal are chemically active and create a suitable background for the metal to be painted.
• Makes the appearance of metal more suitable for use in decoration
The layers that form on the surface of the aluminum metal after the anodizing operation have the appropriate silver color and the desired shine and luster. Therefore, this surface can be used as part of home decoration, even for painting and decoration, even without painting.
• Increases the resistance of metals to oxidation and corrosion
As we know, metals corrode and oxidize quickly in certain weather conditions, and a layer of metal oxide covers them, but unfortunately this layer is very thin and can be scratched. Now with the anodizing process, the thickness of this layer can be increased even several times. Increasing the thickness of the oxide layer on the metal increases the protection of the metal from atmospheric and environmental conditions.
• Increase the ability to reflect light and heat dissipation in metal
If the oxidized layer on the metal surface is created by the anodizing process thicker than 0.032 mm, it will increase the light reflectivity and heat dissipation in the metal. For example, if molten aluminum is painted black, it can absorb heat up to about 230 degrees Celsius.
The anodizing process is one of the laying steps
After the aluminum part undergoes anodizing operation, porous layers are formed on it, which will increase the payment ability of these parts.
• Used as insulation
Aluminum oxide has insulating properties and, depending on the type of alloy and the thickness of the layer of aluminum oxide formed by the anodizing process, it can withstand electric currents of up to several thousand volts.
• Increase wear resistance
A layer of aluminum oxide, which has a high hardness and is very resistant to abrasion, is formed on aluminum parts that are subjected to hard anodizing methods. The greater the thickness of this layer, the greater the wear resistance of the aluminum piece.
For this purpose, the same resistant parts can be easily used in industry and in parts that are under pressure and wear, rotating parts and bearings, etc. It is important to note that not all anodizing methods cause this hardness of the aluminum part. For example, the anodizing operation with chromic acid creates a layer that is soft and not at all suitable for parts that later have to undergo abrasion.
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Aluminum anodizing steps
The anodizing operation is performed on aluminum surfaces in several steps, the first of which is the preparation of the work, then the anodizing process itself, and then the posteloxing steps. The steps are as follows:
1. In the first step, the surface of the part is cleaned with alkali and other solvents and all grease and dirt are removed.
2. Then, with the help of soda solution, the work surface is peeled off, which is also called etching. The product of this step is a piece that has a matte surface.
3. The next step is the main step. At this point, a direct current flows through the electrolyte fluid. In this operation, aluminum acts as an anode, and another metal, which can be titanium, lead or steel, acts as a cathode. At this stage, the metal oxide layer acts on the metal surface.
4. The fourth phase is the phase of electrocalorization or painting of the metal part. As mentioned, after performing anodizing on a metal surface, the ability to paint and absorb paint in it increases. During this phase, the porous surface of the oxidized metal layer is colored with electricity using mineral salts.
5. But the last phase is known as the sealing and sealing phase. The holes in the porous layer are hydrated and filled to create a smooth, polished surface.
aluminium anodizing process paint anodizing for industry
Anodizing alloys
Choosing the right alloy in the process of aluminum anodizing is not easy because different aluminum alloys behave differently depending on the type of alloy and alloying elements as well as the production process.
It should be borne in mind that the standardization of the production process and finally the quality and homogeneity of the metallurgical structure and the arrangement of alloying elements and sediments is the most important point in the choice of products. Therefore, if you plan to produce an aluminum product that needs to be anodized, pay attention to the points in this article.
Anodizing 1050 aluminum alloy
This aluminum alloy is known as pure aluminum (impurities less than 0.5%). Alloy 1050 is mainly used in the production of kitchen utensils and as an electrical conductor.
The anodizing of pure aluminum is very good and of good quality, while due to the softness of pure aluminum it does not have a good processing ability. This alloy accepts a very good hard silver anodized coating (hard anodized) provided it is produced in the standard way.
Anodizing of aluminum alloy 2024
This alloy has high strength and excellent workability due to the presence of copper. On the other hand, the presence of copper in the alloy leads to a decrease in corrosion resistance, so anodizing aluminum 2024 will be difficult. Anodized paint weighs from silver to olive due to the presence of copper. It is recommended that this group of aluminum not be used as a decorative use (anodizing of colored aluminum) because the anodizing of group 2024 will be opaque and opaque.
Aluminum alloy 2024, due to its high strength, low weight, is often used in aerospace applications. The important thing about the hard anodizing of the 2024 group is that due to the presence of copper in the alloy there is a possibility of corrosion and destruction of the part during anodizing, but the quality of the hard anodizing of the 2024 alloy is acceptable.
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It is necessary to explain that due to the weight of this alloy in production (rolling or extrusion), non-compliance with scientific principles in the production of reinforcement or aluminum sheet causes many problems in the anodizing process, so the preparation of these products requires reliable sources.
aluminium anodizing process paint anodizing for industry
Anodizing 3105 aluminum alloy
This group of aluminum contains a small percentage of manganese, which gives aluminum anti-corrosion properties. Therefore, this type of alloy is used in exterior architectural applications of buildings, kitchen utensils that are in contact with corrosive materials. Alloy 3105 is also used in heat exchangers or even in drinking cans.
Anodizing 3105 gives significant properties to the part by creating a corrosion-resistant oxide layer. The remarkable thing about anodized 3105 is that due to the presence of manganese in the alloy, the anodized color of the piece tends to turn from silver to brown. This problem is manifested when you notice a change in the final color of the parts after anodizing when anodizing parts made of alloy 3105.
Anodizing of 5000 series aluminum alloys
5000 series alloys give high mechanical and anticorrosive properties to the part due to the presence of magnesium. This type of alloy is used in marine applications and in the construction of vessels and near sea water. These alloys are capable of anodizing silver and color.
They also have the ability to harden anodized, which is why these alloys are used for facades of buildings and structures near corrosive and humid environments. An important point during anodizing is that only the difference in the amount of magnesium in the alloys can change the color of the anodizing.
Anodizing of aluminum alloy 6063
This series of alloys contains little magnesium and silicon. This alloy has medium strength. High corrosion resistance is another characteristic of this alloy. However, its corrosion resistance does not reach alloy 5754. One of its characteristic features is high extrusion ability and ductility compared to other alloys. Therefore, this alloy is used as a profile in the window and bridge industry.
On the other hand, the anodizing of alloy 6063 is done easily and qualitatively, which leads to the fact that the oxide layer protects part from corrosion and wear. The small amount of iron in this alloy leads to the opacity of the final color of the anodized part.
Anodizing of aluminum alloy 7075
The main element is zinc alloy 7075, which gives this alloy very high strength (as well as steels) after heat treatment. This alloy is not the best option for anodizing silver, but it accepts very good coverage in hard anodizing. After hard anodization, alloy 7075 is used in various other industries such as the production of medical equipment, the production of aircraft, oil and gas and refineries, the textile industry and the production of industrial machinery.
It is necessary to explain that due to the weight of this alloy in production (rolling or extrusion), non-compliance with scientific principles in the production of reinforcement or sheet metal causes many problems in the anodizing process, so the preparation of these products from reliable sources is necessary.
aluminium anodizing process paint anodizing for industry
What is anodized paint?
Anodized paint is a very special type of paint. Which completely paints the surface of aluminum and increases its strength And under no circumstances will the anodized paint be removed.
Sodium hydrosulfite is a white crystalline powder with a sulfur taste.
As mentioned in the introduction, anodizing is an electrical and chemical (electrochemical) process. Elevator weight In this method, the paint layer is covered with aluminum. The thicker this layer of paint, the longer it will last. Due to the special combination of this paint with the desired metal, this paint becomes a part of the material that will not be erased.
But other paints have a coating regime and cover only the metal surface and after a while due to sunburn, rain, rain, physical damage and… will be erased.
After anodizing, the metal surface is evenly painted
aluminium anodizing process paint anodizing for industry
Advantages of anodized paint
• This color increases the strength of aluminum. Increased hardness • Rust resistant • Resistant to corrosive air
When we anodize the desired surface, this surface reflects two separate wavelengths when it comes in contact with the sun, which react to each other due to reflection.
Anodized champagne color
Anodized aluminum paint
Under normal conditions, aluminum becomes oxidized.
In the presence of air, moisture and a layer of oxide are placed on the surfaces And it is responsible for the protection of aluminum.
But in the anodizing method, it is more resistant than normal and more resistant to corrosion.
Reasons for anodizing aluminum surface
• Increase resistance • Increase color adhesion • One of the coating steps • Create a beautiful look for decoration • Insulation • More light and heat reflections
aluminium anodizing process paint anodizing for industry
Anodized paint and powder
In powder coating, the paint sticks only to the outer layer of the object and after the object wears out, the paint can be removed.
But in the anodizing method, the dye is electrochemically absorbed by the object and combined with the object, and under no circumstances will the dye separate from it.
The resistance of metals in the anodizing method is much higher than in the powder method
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