Combined kinetic and X-ray electron probe microanalysis characterization of local porosity variation and pore shape across anodic alumina films

Porous anodic alumina films on Al were prepared by anodic oxidation of Al in H 2SO 4 electrolyte at a constant temperature and current density and different thicknesses, up to ≈ 41 μm. Their cross section was examined by EPMA for revealing the variation of local porosity across the films and shape of pores while a kinetic model for film growth was developed describing the variation of pore diameter. It was found that the pores open, and local porosity increases, towards the film surface, predicting a conical pore shape, while the results coincided with those obtained by kinetic study. The EPMA analysis combined with kinetic results emerges as a promising tool for studying structural features of these films.