Increased growth rate of anodic porous alumina by use of ionic liquid as electrolyte additive

The use of ionic liquids 1-Butyl-3-methylimidazolium 2-(2-methoxyethoxy) ethyl sulfate and 1-Butyl-3-methylimidazolium tetrafluoborate has been tested in the fabrication of anodic porous alumina. The anodizations of the aluminium substrate have been carried out in oxalic acid in galvanostatic mode. During anodization with 1-Butyl-3-methylimidazolium tetrafluoborate added electrolyte, proper tuning of the current density and of the additive concentration resulted in a three-fold increase of the growth rate as compared to the bare acidic solution with the same acid concentration. This did not cause cracks in the film during growth, and did not affect the regular structure of the pores at the interface with the substrate.