Nanoporous surface treatment of aluminium by anodisation in oxalic acid

Abstract

Purpose: Well-ordered nanoporous anodic surface on aluminium substrate was obtained by anodisation method in 0.3 M of oxalic acid as an electrolyte. The objective of this perusal is to describe a system for the magnifying diameter of pores and resistance of demolition of the oxide layer at various voltages. The effect of voltage and time of anodisation process in which obtaining the required structure in AAO film. Design/methodology/approach: The experiments have been performed on a setup for anodisation considering variables parameters. In this study, AAO Templates were prepared in oxalic acid of 0.3 M concentration under the potential range of anodisation 30-40 V at relatively temperatures range from 20-30°C of an electrolyte. Anodic voltage, current density and temperature of electrolyte were adopted as electrical parameters during anodisation. Before anodisation starts two crucial pre-treatment i.e. annealing and electropolishing are finished. Findings: The diameter of pores and pitch of pores are well-proportional to anodisation voltage and process time. The pore diameters were 85 nm, 138 nm, 184 nm, 248 nm with having 9, 16, 27, 37 porosity % respectively. The thickness of AAO film in all cases has been found to be maximum or constant after one hour in second step anodisation. The anodisation parameters like voltage, the time duration of the anodisation process and temperature are very essential features which influencing the fabrication of an AAO film. Research limitations/implications: The anodisation process is very easy to perform but very complex to understand as there are many parameters which may affect it. Practical implications: After that, the second step anodisation for the next half hour, there will be no change in the thickness of AAO film but after that dissolution rate starts over the formation rate and finally thickness will be decreasing. Originality/value: Therein is numerous macropores in the membrane with the size of pores variation from 163 to 248 nm. The diameter of pores, thickness, and pore density of AAO film was determined through Scanning Electron Microscopy (SEM), which exhibited that homogeneous honeycomb-like structure has appeared on the entire surface where anodisation performed precisely.