Investigations Of Self-organized Porous Anodic Alumina With Large Pores

In this work, aluminum oxalate is employed as an additive in the solution of phosphoric acid to suppress breakdown of PAA films at high anodization voltage (180-230 V) and high temperature (up to 10-20℃). The continuously pore intervals from 410 to 530 nm with large self-assembly domains (up to 5μm)have been obtained. With this window, PAA films with pore size larger than 100 nm could be achieved using the wet-chemical etching method. The growth rate of PAA films can be increased up to 40-50μm h-1, being five times faster than usual mild anodization. The function of oxalate anions and aluminum ions in the process of anodization was also investigated. It may facilitate understanding of the effects of anions in the process of anodic oxidation. Meanwhile, micrometer domain projection at the bottom surface of PAA film was observed at 20℃, which provides an experimental evidence for the theory foundation of the self-assembly PAA.