Effect of pulsed electrodeposition time on the characteristics of calcium phosphates coating on TiO₂ nanostructures

To improve the biological performance of titanium alloys calcium phosphates (CaP) coatings are applied to the surface. Those coatings were grown by pulsed current electrodeposition on TiO₂ nanostructures, as a material proposed for biomedical implants. This study evaluated the effect of electrodeposition time variation on the morphology and the electrochemical properties of the coating. Several TI6Al4V-ELI samples were anodized using an electrolyte of NH₄F and NH₄H₂PO₄ obtaining TiO₂ nanotubes and characterizing them by scanning electron microscopy. After that, calcium phosphates were deposited using a solution of Ca(NO₃)₂ and NH₄H₂PO₄ with a pH of 6.5; the coatings were annealed at 550°C per 1h. Finally, the coatings were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and Electrochemical impedance spectroscopy techniques. The analysis of X-ray diffraction and Fourier transform infrared spectroscopy confirmed the formation of calcium phosphates (Hydroxyapatite and β-tricalcium phosphate). The results revealed that the coatings morphology was modified with the electrodeposition time variation. Furthermore, it was observed that an increase in galvanostatic electrodeposition time leads to a higher electrochemical stability of the samples in simulated body fluid. (paper)