The porosity and roughness of electrodeposited calcium phosphate coatings in simulated body fluid

Abstract

Calcium phosphate coatings were electrochemically deposited on titanium from an aqueous solution of Ca(NO3)(2) and NH4H2PO4 at a current density of 10 mA cm(-2) for a deposition time of 15 mm. The obtained brushite coatings (CaHPO4 center dot 2H(2)O), were converted to hydroxyapatite (HA) by soaking in simulated body fluid (SBF) for 2, 7 and 14 days. The brushite and hydroxyapatite coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). It was shown that increasing the soaking time increased the porosity, roughness and crystallite domain size of the HA coatings and decreased the unit cell parameters and unit cell volume, while the mean pore area of HA was unaffected. The calcium and phosphorus ions concentrations in SBF were determined by atomic absorption spectroscopy (AAS) and UV-Vis spectroscopy, respectively, and a mechanism of HA growth based on dissolution-precipitation was proposed.