Fast fourier transform analysis of pore pattern in anodized alumina formed at various conditions

A quantitative investigation of the effect of process parameters such as electrolyte concentration, temperature, anodization duration and anodization potential on the pore pattern (including pore diameter and distribution) in anodic alumina was performed based on aluminum anodization experiments. Using fast Fourier transform (FFT) analysis, we developed a method to quantify the orderedness of pore distribution. We found that at a lower temperature the anodization protocol of a 1 hr first step followed by a 4 hr second step did not cause any change in pore orderedness as opposed to the anodization protocol of a 12 hr first step followed by a 1 hr second step, but at a higher temperature the former improved the pore orderedness. Increasing the electrolyte concentration, improved the pore orderedness. Varying the electrolyte concentration, temperature, and anodization duration did not have any effect on the pore diameter. Increasing the anodization potential, however, not only improved the pore orderedness but also increased the pore diameter. Linear relationships exist between the pore diameter and anodization potential and between the center to center pore spacing and applied anodization potential.