Hydrothermal and cerium salt sealing of a 6061 aluminum alloy

Abstract

Abstract The influences of the environmentally friendly sealing processes of cerium salt sealing and hydrothermal sealing on the electrochemical behavior of the anodic oxide film of an aluminum alloy were examined by accelerated corrosion of dry-wet alternate immersion corrosion tests, combined with the morphologies observation, chemical composition tests, and electrochemical tests. A severe corrosion environment with high temperature, high humidity, and high salt spray was adopted. The results of electrochemical characteristics show that cerium salt sealing affected the inner barrier layer of the film instead of the outer porous film. The higher impedance of the inner barrier layer is related to the reaction between cerium ions and cathodic reaction products of hydroxyl ions. Hydrothermal sealing, although had some good influence on both the porous layer and the barrier layer of the oxide film, corrosion inhibition on the whole cannot do better than that of cerium salt sealing in the early days. However, as the corrosion time went on, the hydrothermal sealing sample showed better durability.