Metal Surface Anticorrosion Treatment Method

Abstract

Metal surface anti-corrosion treatment method, an anodic oxidation layer is first formed on the surface (such as the outer surface) that is easy to form an oxide layer. The thickness of the oxide layer is determined by factors such as the base material, ion concentration of the electrolyte, pH value, temperature, current and voltage. Control, and then carry out chromate passivation; on the surface where an anodic oxidation layer cannot be formed, a chromate passivation film is formed. At the same time, it is also possible to form a chromic acid passivation film in the honeycomb columnar holes on the anodized layer to enhance corrosion resistance and wear resistance, and finally seal the holes with hot water. It can not only provide a certain hardness, wear resistance and good corrosion resistance for the outer surface of aluminum or aluminum alloy, but also provide good corrosion resistance for the internal complex structure. At the same time, it integrates the process of anodic oxidation and chromate passivation, which is easy to operate, reduces the technical limitations of the design structure, and provides corrosion protection for complex structural workpieces that are not suitable for general surface treatment methods.

Description

technical field [0001] The invention relates to a metal surface anticorrosion treatment method, in particular to an anticorrosion surface treatment method for aluminum materials and aluminum alloys in air or other media. Background technique [0002] The natural alumina on the surface of aluminum products is soft and thin, and has poor corrosion resistance, so it cannot be an effective protective layer. The surface treatment methods of aluminum materials in medical equipment generally include artificial oxide film, electrophoretic coating and powder spraying. On some workpieces with cleanliness requirements, only the surface treatment method of artificial oxide film can be used. At present, there are two main methods of artificial oxide film in medical equipment: chromate passivation and anodic oxidation. [0003] The general principle of chromate passivation: put the metal into chromic acid or chromate solution containing certain additives, and make the metal surface gene...

AI Technical Summary

Problems solved by technology

[0005] The chromate passivation film is thinner than the anodic oxide film, the corrosion resistance and surface hardness are relatively low, and it is not easy to color, and the light resistance after coloring is poor

[0006] The current anodizing technology can provide aluminum with a certain hardness and good corrosion resistance, but the biggest disadvantage is that it cannot be applied to complex inner cavities

The important factors affecting the quality of the anodic oxide film are the structural complexity of the workpiece to be processed as the anode and the distribution of the cathode of the electrolytic cell relative to the workpiece to be processed. Uniformity leads to insufficient oxygen ion concentration in the electrolyte in the cavity, and the formed anodic oxide film is too thin or cannot form an anodic oxide film at all, so that it cannot provide comprehensive corrosion protection for the workpiece

The existing solution is to increase the auxiliary cathode to make the electric field distribution more uniform. The disadvantage is that the operation is complicated, the investment is high, the efficiency is low, and the surface of the workpiece is easy to be damaged during the operation.

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