Porous Anodic Alumina Films Obtained by Two Step Anodization

Abstract

The paper presents a preliminary study on the obtaining of nanoporous alumina membranes by two-step anodization. Using this process, self-ordered porous structures can be obtained with variable distances between pores, and high pore density on the surface compared to membranes obtained by other methods. After the first anodization, the formed aluminum oxide was removed by chemical etching in a mixture of phosphoric acid and chromium trioxide. The second anodization, intended to obtain the self-ordered porous structure, was done at the same conditions as the first one. These membranes can be used for microfluidic separation, and sensor elements, as ideal templates for the formation of various nanostructured materials.