Investigation of intrinsic mechanisms of aluminium anodization processes by analyzing the current density

Abstract

The intrinsic mechanisms of aluminium anodization processes have been investigated in detail by analyzing the anodization current density (i_a). The characteristics and general chemical reactions of mild anodization (MA) and hard anodization (HA) have been discussed, and the avalanche of the electronic current is considered to be the main reason to trigger the HA process. Moreover, the formation mechanisms of the maximum anodization voltage (U_max) in different electrolytes have been studied in detail, and it is found that the electrolyte dissociation constant can have a direct impact on the avalanche electronic current density (i_e) and U_max. Based on the above arguments, the electrolyte modifying process has been investigated. In addition, the representative microstructural morphologies of anodic aluminium oxides (AAO) together with their intrinsic formation mechanisms have also been studied.