Theoretical modelling of porous oxide growth on aluminium

Abstract

A theoretical model for porous structure formation during electrochemical anodization of aluminium is developed taking into account anodic oxide growth at the oxide/electrolyte and oxide/aluminium interfaces, electrochemical and field-enhanced oxide dissolution, and a three-dimensional configuration of electric field and current in the scalloped barrier oxide layer at pore bottoms. A system of equations ensuring a general description of the porous structure formation is evolved and is further applied to the analysis of stationary pore growth on aluminium. In this particular case analytical expressions are obtained establishing the relations of pore geometry and electric field in oxide with the parameters of anodic process (voltage, temperature, pH). They are found to be in agreement with existing experimental data.