Anodic oxidation of construction aluminum in different electrolyte systems and performance comparison of oxide films
The 6063 aluminum alloy commonly used in the construction industry was anodized in pure sulfuric acid electrolyte,sulfuric acid and boric acid mixed electrolyte,sulfuric acid and citric acid mixed electrolyte,sulfuric acid and glycerol mixed electrolyte,and sulfuric acid,boric acid,citric acid and glycerol mixed electrolyte in order to further improve the corrosion resistance of 6063 aluminum alloy and then extend the service life of construction components.And the morphology characteristics,thickness,phase structure and corrosion resistance of the different oxide films were compared.The results showed that the different oxide films had the morphology characteristics of dense porosity with similar thickness and consisted of ɑ-Al2O3 and γ-Al2O3 phase.However,the porosity and surface compactness of the different oxide films were obviously different,resulting in different corrosion resistance.The oxide film prepared in mixed acid electrolyte system had the lowest porosity of 12.1%,the best surface compactness,the most positive corrosion potential of-0.511 V,the lowest corrosion current density of 1.15×10-6 A/cm2 and the highest polarization resistance of 22.05 k Ω·cm2.After 96 h salt spray experiment,the corrosion degree of the oxide film was lighter.Adding appropriate amount of boric acid,citric acid and glycerol had a synergistic corrosion inhibition effect,so the mixed acid electrolyte system had a weak ability to dissolve the oxide film,and can significantly improve the surface compactness of the oxide film to further improve its corrosion resistance.As a surface modifica-tion layer,the oxide film prepared in mixed acid electrolyte system can better protect aluminum alloy matrix and delay corrosion.
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