Do you know the method of anodizing aluminium alloy?

Source:http://www.tenta-alu.com/news/4471.html  Release time:2019-02-20

There are many ways to anodize aluminium and its alloys. Here we mainly introduce the commonly used sulfuric acid anodization. Other anodic oxidation methods for aluminium and its alloys include chromic acid anodization, oxalic acid anodization, hard anodization and ceramic anodization.

Sulphuric acid anodization: Aluminum and its alloys are anodized by DC or AC in dilute sulfuric acid electrolyte. A colorless transparent oxide film with a thickness of 5-20 um and good adsorptivity can be obtained. The process is simple, the solution is stable and the operation is convenient.




(1) The influence of sulfuric acid mass concentration: the sulfuric acid mass concentration is high, the chemical dissolution speed of the membrane is accelerated, the film formed is thin and soft, with many voids, strong adsorption and good dyeing performance; the oxidation film growth rate is faster when the sulfuric acid mass concentration is reduced, but the void ratio is low, the hardness is higher, the wear resistance and the reflectivity are higher. Good sex.

(2) Temperature: The temperature of the electrolyte has a great influence on the quality of the oxide film. When the temperature is 10-20 degree C, the oxide film is porous, has good adsorption performance, is elastic and suitable for dyeing, but its hardness is low and its wear resistance is poor. If the temperature is higher than 20 degree C, the oxide film becomes loose and its hardness is low. When the temperature is below 10 degree C, the thickness of the oxide film increases, the hardness is high, the wear resistance is good, but the void ratio is low. Therefore, the temperature of electrolyte must be strictly controlled in production.

(3) Effect of current density: Increasing current density accelerates the growth of film, shortens oxidation time, reduces the chemical solubility of film, makes the film hard and has good wear resistance. However, if the current density is too high, the dissolution of the film will increase due to the influence of Joule heat, and the growth rate of the film will decrease instead. Low current density and long oxidation time make the film loose and the hardness reduced. The effect of

(4) time: The anodic oxidation time can be determined by the mass concentration, temperature, current density and required film thickness of the electrolyte. Under the same conditions, the thickness and voids of the oxide film increase with time. However, when the thickness reaches a certain level, the growth rate slows down and does not increase at last.

(5) The influence of stirring: stirring can promote the convection of solution, make the temperature uniform, and will not cause the quality of oxide film to decline due to the local temperature rise of metal. The mixing equipment is air compressor and water pump.

(6) Effect of alloy composition: Aluminum alloy composition has a very important impact on the quality, thickness and color of the film. In general, other elements in the aluminum alloy make the quality of the film decline. For Al-Mg alloys, when the mass fraction of magnesium exceeds 5% and the alloy structure is heterogeneous, proper heat treatment must be adopted to homogenize the alloy, otherwise the transparency of the oxide film will be affected. For Al-Mg-Si alloys, with the increase of silicon content, the color of the film will change from colorless transparency to gray, purple, and finally to black. For Al-Cu-Mg-Mn alloys, copper decreases the hardness of the film, increases the void fraction, loosens the film and decreases its quality. Under the same oxidation conditions, the oxide film obtained on pure aluminium has the thickest thickness, the highest hardness and the best corrosion resistance. There are many methods of anodic oxidation of

aluminium and its alloys. This paper mainly introduces the commonly used sulfuric acid anodic oxidation. Other anodic oxidation methods for aluminium and its alloys include chromic acid anodization, oxalic acid anodization, hard anodization and ceramic anodization.

Sulphuric acid anodization: Aluminum and its alloys are anodized by DC or AC in dilute sulfuric acid electrolyte. A colorless transparent oxide film with a thickness of 5-20 um and good adsorptivity can be obtained. The process is simple, the solution is stable and the operation is convenient.

(1) The influence of sulfuric acid mass concentration: the sulfuric acid mass concentration is high, the chemical dissolution speed of the membrane is accelerated, the film formed is thin and soft, with many voids, strong adsorption and good dyeing performance; the oxidation film growth rate is faster when the sulfuric acid mass concentration is reduced, but the void ratio is low, the hardness is higher, the wear resistance and the reflectivity are higher. Good sex.

(2) Temperature: The temperature of the electrolyte has a great influence on the quality of the oxide film. When the temperature is 10-20 degree C, the oxide film is porous, has good adsorption performance, is elastic and suitable for dyeing, but its hardness is low and its wear resistance is poor. If the temperature is higher than 20 degree C, the oxide film becomes loose and its hardness is low. When the temperature is below 10 degree C, the thickness of the oxide film increases, the hardness is high, the wear resistance is good, but the void ratio is low. Therefore, the temperature of electrolyte must be strictly controlled in production.

(3) Effect of current density: Increasing current density accelerates the growth of film, shortens oxidation time, reduces the chemical solubility of film, makes the film hard and has good wear resistance. However, if the current density is too high, the dissolution of the film will increase due to the influence of Joule heat, and the growth rate of the film will decrease instead. Low current density and long oxidation time make the film loose and the hardness reduced. The effect of

(4) time: The anodic oxidation time can be determined by the mass concentration, temperature, current density and required film thickness of the electrolyte. Under the same conditions, the thickness and voids of the oxide film increase with time. However, when the thickness reaches a certain level, the growth rate slows down and does not increase at last.

(5) The influence of stirring: stirring can promote the convection of solution, make the temperature uniform, and will not cause the quality of oxide film to decline due to the local temperature rise of metal. The mixing equipment is air compressor and water pump.

(6) Effect of alloy composition: Aluminum alloy composition has a very important impact on the quality, thickness and color of the film. In general, other elements in the aluminum alloy make the quality of the film decline. For Al-Mg alloys, when the mass fraction of magnesium exceeds 5% and the alloy structure is heterogeneous, proper heat treatment must be adopted to homogenize the alloy, otherwise the transparency of the oxide film will be affected. For Al-Mg-Si alloys, with the increase of silicon content, the color of the film will change from colorless transparency to gray, purple, and finally to black. For Al-Cu-Mg-Mn alloys, copper decreases the hardness of the film, increases the void fraction, loosens the film and decreases its quality. Under the same oxidation conditions, the oxide film obtained on pure aluminium has the thickest thickness, the highest hardness and the best corrosion resistance. Eight hundred and eighty-eight thousand one hundred and eleven

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