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Aluminum alloy oxide film formation process

Release time:

2022-05-16 16:03

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First stage of anodizing

In the formation stage of the non-porous layer, in section AB, the voltage increases sharply during the power-on start-off time (a few seconds to tens of seconds) and reaches the critical voltage (the maximum value of the voltage), which indicates that a continuous, non-porous thin film layer is formed on the anode surface at this time. The non-porous layer has a large resistance, which hinders the continuous thickening of the film. The thickness of the non-porous layer is proportional to the formation voltage, and the dissolution rate of the oxide film in the electrolyte is inversely proportional. The thickness is about 0.01~0.1 microns.

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Second stage of anodizing

In the stage of porous layer formation, bc section, holes will be dissolved first in the thinnest part of the membrane, and the electrolyte can reach the fresh surface of aluminum through these holes. The electrochemical reaction can continue, the resistance decreases, the voltage decreases (the decrease range is 10-15% of the highest value), and a porous layer appears on the membrane.

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Third stage of anodizing

The porous layer thickens, the cd section, then the voltage rises steadily and slowly, then the non-porous layer is continuously dissolved into a porous layer, and the new non-porous layer is growing again, so the porous layer is continuously thickening, when the generation speed and dissolution speed reach dynamic equilibrium, the thickness of the membrane will no longer increase, then the reaction should stop.

anodic oxidation treatmentThe surface of aluminum and its alloys can obtain a dense film layer which is much thicker than the natural oxide film, so that the metal surface gloss can remain unchanged for a long time, the corrosion resistance and mechanical strength are improved, and the decorative appearance can be obtained by dyeing.

Baianmei focuses on the research of aluminum anodizing dyes and additives, which has been widely concerned and praised by the industry.