Pilling-Bedworth ratio of thick anodic aluminium porous films prepared at high voltages in H2SO4 based electrolyte

Thick porous anodic films have been prepared using high voltages in a sulphuric acid based electrolyte. The use of H2SO4 low concentration, low bath temperature and the boric acid as modifier allows the anodic porous film to be significantly thickened preventing its chemical dissolution. A new relation including the Pilling-Bedworth ratio, especially of the thick anodic porous films, is proposed here to take into account the nanoporosity and the anodic current efficiency.