Electrochemical assisted deposition of calcium phosphate coatings for orthopaedic applications

Abstract

Calcium phosphate (CP) coatings on Ti6Al4V alloy were grown at controlled current densities (from 3 to 10 mA cm−2) during electrochemical deposition (ECD). The thickness, structure and composition of the coatings were investigated by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results showed that the thickness (ranging from 3 to 16 μm) shows a parabolic increase with the applied deposition current density. The hexagonal hydroxyapatite (HA) structure was the main phase at the current density of 10 mA cm−2 during ECD. The potential–time curves showed that the CP deposition progresses due to the initial reduction of alloy surface oxide layer, after which a reduction of nitrate ions takes place on the active free surface sites. The kinetics of this process is enhanced by sufficiently high current densities. Such current densities have a direct influence on the local pH of the solution and determine the morphology, structure and composition of ECD products.