i基板上磷酸钙薄膜的电沉积

It has been well documented that the essential requirement for metallic materials to bond to living bone is the formation of a hydroxyapatite (Ca10(PO4)6(OH)2, HAP) layer on their surfaces. Brushite (CaHPO4•2H2O，DCPD) is a precursor phase of HAP with a general tendency for the following transformation sequence under a broad range of conditions: Brushite→OCP→HAP, where OCP is octacalcium phosphate phase (Ca8H2(PO4)6•5H2O). Electrodeposition has been widely used for the method enabled the formation of coatings of different thickness in the range of up to 100 μm. The composition, microstructure and porosity of deposited coatings can be varied by changing electrolyte concentrations. This study focuses on the influences of the electrolytic conditions on the crystal transformation of electrodeposited calcium phosphate coatings. In the experiment, Ti substrate was used. The electrolytic deposition was carried out in a diluted Ca(NO3)2 and NH4H2PO4 solution with calcium ion concentration of 45 mM and phosphate ion concentration of 25 mM under different conditions such as temperature, deposition time and pH value. The deposited coatings were characterized by XRD and SEM. The results showed that temperature had the strongest impact on the phase transformation. The coating obtained at 37 ℃ had only DCPD phase, With increasing temperature to 60 ℃, the HA phase content in the coating increased. The deposition time did not show obviously affect to the phase of the coating. With pH value increased, both DCPD and OCP phase content increased, showing that high pH has both impacts on phase growth and phase transformation. In the studied conditions, temperature is the most important parameter in phase transformation. Rising of deposition temperature could make calcium phosphate well transformed to HA, which could work better as a surface of artificial implants.