In spite of the extensive experimental investigations reported in the
literature on porous alumina templates, the theoretical mechanisms, and
their dependence on process parameters such as potential difference, current
density and electrolytes, are not well understood. A theoretical model
developed and published for porous structure formation under constant
current electrochemical anodization of aluminum is adopted for constant
voltage anodization. The model is based on the rate equation approach in
which both the alumina formation and etching are considered. The model
employs a minimal number of parameters and yet captures the essence of the
experimental observations. The model yields an analytical solution relating
the model parameters, process parameters and thickness of the film, which is
easy to interpret and use. The results of normalized current versus time
obtained from the model are in good agreement with the experimental results
reported for a range of voltages, 20–40 V. It is also observed that the
thickness of the Al2O3 pore follows V1/2 behavior for anytime
during the anodization.