Self-ordered porous alumina by two-step anodizing at constant current: Behaviour and evolution of the structure

The paper focuses on the two-step anodizing of 1050 aluminium alloy at constant current under self-ordered regime. The evolution of the structural parameters of the anodic aluminium oxide and the correlation between self-ordering growth regime, aluminium surface nanotexturing and anodizing operating conditions are analyzed in oxalic acid bath, as well as the effect of intermetallic compounds from the aluminium matrix. The paper shows that a proper choice of the operating conditions allows the tuning of self-ordering regime, control of local catastrophic phenomena and achievement of a more uniform growth. Therefore, alumina membranes are obtained with a defined structure and a degree of order that is comparable to those obtained with anodizing at constant voltage.

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► A wide range of operation conditions in anodization at constant current provides self-ordering regime.
► Growth of porous alumina layer at constant current slightly differs from growth at constant voltage.
► Intermetallic particles influence self-ordering during anodization at constant current in AA1050.