The influences of sealing methods on corrosion behavior of anodized aluminum alloys in NaCl solutions

The influences of sealing methods on the corrosion behavior of three anodized aluminum alloys, 1070, 2024 and 7075, in NaCl solutions were studied. The anodic films were sealed by the methods of boiling water, stearic acid, potassium dichromate and nickel fluoride, respectively. Passivation and pitting behaviors resulting from the sealing treatments were studied using the potentiodynamic polarization, and surface morphology was examined by scanning electron microscopy. The results show that boiling water and potassium dichromate sealed films provide relatively higher corrosion resistance in acidic solution, while nickel fluoride sealed film is better in basic solution. Stearic acid sealed film provides good corrosion resistance both in acidic and in basic solutions. The influencing mechanisms of different sealing methods on corrosion resistance of the anodized alloys were discussed. (C)) 2002 Elsevier Science B.V. All rights reserved.