A Study On Hydroxyapatite Coatings Prepared By Electrodeposition In A Modified Simulated Body Fluid

Hydroxyapatite has excellent biocompatibility and bioactivity.Titanium and titanium alloy have been widely applied in orthopedics and dentistry due to their excellent mechanics and biocompatibility.The materials possessing the advantages of both titanium and HA have been hot-topic in recent years.The TiO₂/HA composite coatings were directly prepared in modified simulated body fluid with "anodic oxidation-electrodepositing" two-step method.Firstly,homogenous and porous TiO₂ oxidizing layer was prepared in phosphoric acid solution contain NaF at room temperature and low-voltage. The influence of the anodic oxidation technique condition on component, microstructure,phase constitutes,morphology and corrosion resistance characteristic of oxide film were studied.And the anodic oxidation processing parameter before electrodepositing was determined:oxide voltage about 20V and 5 min ultrasonic washing after oxidation.Secondly,the influence of electrodepositing technique conditions on adhesions strength and surface holography of hydroxyapatite coatings were studied.The anodic oxidation treating influence on performances of hydroxyapatite coatings had been studied too,such as depositing efficiency,surface holography,and adhesion strength and corrosion resistance characteristic.Configurations and structures of coatings were investigated by SEM.The phase structure and compositions of coatings were determined by XRD and FT-IR.The bonding strength of interface between the coatings and the substrate was measured by adhesive-draw shear strength test.Corrosion resistance characteristics were investigated by electrochemical impedance spectroscopy and polization cure. Finally,simulated body fluids were carried out to evaluate the biological properties of hydroxyapatite coatings.The results indicate that the hydroxyapatite coatings were uniform and dense,and the outer coatings were adjacent curled flakes joint together by small needle like crystals and the inner coatings were uniform and porous TiO₂ coating.The deposition efficiency,corrosion resistance,density and adhesions strength were greatly improved after anodic.Test in simulated body fluid indicated that the coatings possessed good biological properties and induce hydroxyapatite growth in simulated body fluid during a short period.