Transitions in porous oxide morphologies on AA2024-T3 anodized under high currents and low temperatures: impact on corrosion behaviour

The surface morphology, cell geometry, and electrochemical response of porous anodic films of comparable thickness, generated on AA2024‐T3 in sulphuric acid electrolyte under hard and soft anodizing conditions, were studied to disclose the impact of the anodizing parameters on corrosion behaviour. Localized oxide growth associated with a transition from sponge-like morphology to linear cells was observed with increasing current density and/or reducing electrolyte temperature. The anticorrosion performance of films with the higher barrier layer thickness was inferior due to the defective surface induced by localized oxide growth at high currents or low temperatures. Viceversa, the films displaying sponge-like morphology performed better due to the beneficial effect of inter-cell porosity in facilitating the self-sealing process.