Investigation of the pore formation in anodic aluminium oxide

• Published in: Journal of materials chemistry Vol. 18; no. 47; pp. 5787 - 5795
• Main Authors: Su, Zixue, Hahner, Georg, Zhou, Wuzong
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2008
• Subjects: Applied sciences; Corrosion; Corrosion mechanisms; Exact sciences and technology; Metals. Metallurgy; Aluminium oxide; Voltage current curve; Oxide layer; Aluminium; Nanoporous materials; Dissolution; Layer thickness; Thin film; Pore size; Anodic oxidation; Self organization; Electrolyte; Anodizing; Ordering; Porosity; Diffusion; Electric field effect; Microstructure; Alumina; Interface
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/b812432a

The mechanism accounting for the self-organization of nanoscale pores during anodic oxidation of aluminium is studied. Microstructural studies support the equifield strength model, which can be used to explain the formation of the hemispherical electrolyte/oxide and oxide/metal interfaces, uniform thickness of the oxide layer, as well as self-adjustment of the pore size and pore ordering. The fundamentals of the model are the electric field enhanced oxide dissolution rate and oxygen anion migration rate. The most important factor for determining the porosity of anodic alumina films with both ordered and disordered pores is the relative dissociation rate of water. The relationships between the porosity and anodization conditions, such as voltage, current density, and electric field strength, are also estimated.