1.Chromizing treatment of aluminium alloy is a common pre treatment method for aluminium products. Chromized Aluminum Coil forms a passivation film on the surface of products by chemical reaction, which enhances the corrosion resistance of products and the adhesion of coatings.
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At present, the commonly used types of chromization are trivalent chromization and hexavalent chromization. Because of the serious environmental pollution of chromium film, the residual chromium compounds are harmful to human body. So trivalent chromium and hexavalent chromium treatment will be gradually converted to chromium-free treatment.
The process of chromized Aluminum Coil is as follows:
1. Degreasing: Degreasing is the removal of grease from metal surface by alkaline degreasing solution. Aluminum alloy is poor in alkali resistance and should not be cleaned with strong alkali. Therefore, the concentration of bath solution should be controlled. The concentration of degreasing solution can be prepared according to the manufacturer's instructions. In addition, proper heating and continuous stirring will accelerate the chemical reaction and enhance the degreasing effect.
Quality Inspection of chromized aluminum coil
1. Appearance of the film: The color of the film is uniform.
2. Corrosion resistance: It can be judged by salt spray test.
3. Chromium weight: The compactness and thickness of chromium layer can be measured by chromium weight test.
