Anodization of aluminium: Atomic simulations of the initial process steps

In order to get a better control over the anodization process of aluminium, it is necessary to obtain a better understanding of the process at an atomic scale. In order to achieve this, molecular dynamics simulations are performed to study the reactions taking place during the initial formation of an anodic oxide layer, and to determine the influence of the electric field strength, temperature and environment on these reactions and the ion movement in the oxide layer. Simulations are performed regarding the oxidation of aluminium in an atomic oxygen environment under the influence of an external electric field, regarding the anodization of aluminium in water, in an oxalic acid solution and in an ammonium tartrate solution. It was found that applying a higher electric field strength only significantly influences the oxide thickness if this electric field strength is higher than a certain critical value. A higher temperature lowers this critical value. In an ammonium tartrate solution the tartrate ions assist in the formation of an oxide layer, leading to a thicker layer at a lower field strength as compared with anodization in pure water. To improve the modelling of the anodization process the charge equilibration procedure should be adjusted for a more realistic description of the charges and, with that, a more realistic description of the reactions that take place during the anodization process.Mechanical Engineering, track Materials Engineering and ApplicationsMaterials Science & EngineeringMechanical, Maritime and Materials Engineerin