Effect of ageing in the electrolyte and water on porous anodic films on zirconium

The present study demonstrates the significant influence of ageing in the formation electrolyte on the morphology and composition of anodic films grown on zirconium in 0.35 M ammonium fluoride in glycerol. Ageing after anodizing, by immersion in the electrolyte for 1 h, is shown to promote a transition from a porous to a nanotubular morphology, due to the dissolution of the fluoride-rich intratubular material in which the nanotubes are embedded. The morphological change is accompanied by a significant loss of zirconium and fluorine from the film. In contrast, ageing in deionized water has little influence on the films.

► Porous anodic films are formed on zirconium consisting of nanotubes embedded in a fluoride-rich matrix.
► Ageing in the formation electrolyte transforms the films from porous to nanotubular.
► Ageing causes losses of zirconium and fluorine, due to dissolution of the matrix.
► Ageing in water has negligible influence on the film composition and the film morphology.