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

Abstract

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.