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Can 7xxx aluminum sheet be anodized

September 21, 2020

7xxx aluminum sheet, an aluminium zinc magnesium alloy, contains alloys of 7075, 7050 and 7005 etc. As known to all, 5xxx aluminium sheets boast excellent anodizing effect, especially suitable as housing materials for electronic products. Can 7xxx aluminium plates be anodized, too?

7xxx anodized aluminum sheet

The answer is positive. Known as an aircraft aluminum sheet, 7xxx plates are light in weight and strong in hardness. With Zinc and magnesium as the main alloy metals, 7000 alu sheets are a super hard heat treatable alloy 60% stronger than ordinary aluminium materials and 66% lighter than steel. Recent series of I phones have all adopted 7000 anodized aluminium sheets as their housing materials covering the whole frame and most of the back cover. The material of the mobile phone shells should have the characteristics of high strength, good heat and thermal conductivity, strong electromagnetic shielding, stable size, beautiful appearance, thin and durable, in order to achieve the effects of protection, heat dissipation, and beauty. Apple said that the customized 7-series aluminum-zinc-magnesium alloy is processed, polished and sandblasted with tiny zirconia beads to achieve a consistent silk satin texture, while the additional anodizing process helps prevent scratches and corrosion.

Anodized aluminium sheet manufacturers employs several steps to realize anodising of 7xxx aluminum sheets. The first is degreasing, used to remove grease and oil dirt on the surface of sheets. If there are oil and other organic substances on the metal surface, the flatness, adhesion and corrosion resistance of the electrodeposited coating will be affected. Thus the degreasing is very important. The second is polishing, used to eliminate mechanical defects on the sheet. This step is usually carried out with phosphoric acid. The third is activation, used to enlarge the pore, increase the porosity and improve the effect of dye adsorption in the next process. The fourth is dyeing. The dye is adsorbed on the surface of the pores and diffused in the pores. The last is hole sealing, which aims to improve the quality and dyeing fastness of aluminum parts, prevent magnesium oxide appearance deformation, and endow anodized aluminium sheet with the ability to prevent fingerprints, stains and grease. Finished 7xxx anodized aluminum sheets are stronger in hardness and more beautiful in appearance, applied to electronic and home appliance products worldwide.

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