The effect of applied current density on the surface morphology of deposited calcium phosphate coatings on titanium

Electrochemical deposition of calcium phosphate coatings on titanium was performed galvanostatically from the aqueous solution of Ca(NO3)(2) and NH4H2PO4 with the current densities between 5.0 and 10 mA cm(-2), for different deposition times, at room temperature. The coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD results showed that dicalcium phosphate dihydrate (DCPD), brushite (CaHPO4 center dot 2H(2)O) coatings were deposited. The influence of applied current density and the deposition time on the phase composition, crystallite domain size and the morphology of brushite coatings were investigated. It was shown that brushite coating of the greatest mass was obtained for the longest deposition time, while the increase in current density over 7 mA cm(-2) does not affect significantly the mass of brushite coatings. The finest crystallites, with the smallest crystallite domain size of 15.6nm, were deposited at the current density of 9.0 mA cm(-2). Brushite coatings were fully converted to hydroxyapatite in simulated body fluid (SBF) which was confirmed by XRD and SEM. The crystallite domain size of HA coatings is controlled by applied current density for brushite coatings deposition: crystallization of HA at more porous brushite coatings, deposited at higher current density, caused the formation of smaller crystallites of hydroxyapatite

Electrochemical synthesis and characterization of hydroxyapatite powders

Electrochemical synthesis of hydroxyapatite powders was performed galvanostatically from homogeneous solution of Na(2)H(2)EDTA center dot 2H(2)O, NaH2PO4 and CaCl2 at a concentration relationship Ca/EDTA/PO43- of 0.25/0.25/0.15 M at current densities of 137 and 207 mA cm(-2) and pH values of 9.0 and 12.0. The hydroxyapatite powders were characterized by X-ray diffraction, size distribution measurements, transmission electron microscopy, scanning electron microscopy and thermogravimetric and differential thermal analysis. The influence of the electrochemical synthesis parameters, e.g. applied current density and pH value, on the phase composition, crystallite size, morphology and thermal characteristics of hydroxyapatite powders were investigated. (c) 2008 Elsevier B.V. All rights reserved

Electrodeposited hydroxyapatite thin films modified by ion beam irradiation

Surface modification of hydroxyapatite (HA) thin films electrodeposited on titanium was conducted by ion implantation, using nitrogen and argon ions at different constant fluences of 1x10(15), 1x10(16) and 1x10(17) ions/cm(2). SEM and XRD analysis, as well as SRIM calculation, were used to monitor the changes induced by ion bombardment. In the case of HA film implanted with N(4+) ions, the unit cell parameters and unit cell volume increase with increasing nitrogen ion fluences. Similarly, the unit cell parameters and unit cell volume increase after Ar(6+) ions irradiation to a 1x10(15) ions/cm(2). At higher fluences, the unit cell parameters and unit cell volume decrease when argon ion fluences increase to 1x10(16) and 1x10(17) ions/cm(2). These structural changes are consequence of different mechanism of energy transfer of nitrogen and argon ions to HA film. For nitrogen ion irradiation electron energy loss is predominant, while for argon ion irradiation nuclear energy transfer to HA film prevails

Electrochemical synthesis of nanosized monetite powder and its electrophoretic deposition on titanium

Electrochemical synthesis of nanosized monetite powder was performed galvanostatically from homogeneous Solution of Na(2)H(2)EDTA center dot 2H(2)O, NaH2PO4 and CaCl2 at a concentration relationship Ca/EDTA/PO43- of 0.25/0.25/0.15 M at current density of 137 mA cm(-2) and pH value of 5.0. The synthesized monetite powder was characterized by X-ray diffraction, infrared spectroscopy, size distribution measurements, thermogravimetric and differential thermal analysis and scanning electron microscopy. Monetite powder was electrophoretically deposited on titanium from ethanol Suspension, using constant voltage method. The deposition was performed at constant voltage between 10 and 50 V and for a constant deposition time between 1 and 30 min. The influence of the applied voltage and deposition time on the mass and morphology of monetite deposits was investigated. It was shown that monetite deposits of the highest thickness and the lowest porosity can be formed at lower applied voltage (30 V) and for longer deposition time (20 min) and then converted to hydroxyapatite. (C) 2009 Elsevier B.V. All rights reserved