Enhancing the bioactivity of zirconium with the coating of anodized ZrO2 nanotubular arrays prepared in phosphate containing electrolyte

Bioactive zirconium oxide nanotubular arrays on zirconium alloys are prepared electrochemically in fluoride and phosphate containing electrolyte. Geometric factors of the ZrO2 nanotubular layers, particularly the pore diameter and thickness, are affected by the electrochemical conditions, including applied potential and anodization time. Under specific sets of conditions, highly ordered ZrO2 nanotubular arrays are formed with diameters varying from 30 nm to 75 nm and lengths varying from 2 μm to 12 μm. XPS shows that the nanotubular layer contains a significant amount of phosphate species distributed almost homogeneously over the entire tubular length. The ZrO2 nanotubular layer formed in fluoride and phosphate containing electrolyte highly enhances the formation of bioactive hydroxyapatite coating in simulated biological fluid (SBF).