Study On Silicon-substituted Hydroxyapatite Synthesized By Hydrothermal Method And Coatings Prepared By Electrophoretic Deposition

Bioactive ceramic-coated metal has the predominance of both metal and ceramic, so it is considered as a kind of the most promising bone replacement material. Many efforts have been made in recent years in the development of processing methods for depositing HA on the implant alloy substrate in order to have high strength as well as excellent biocompatibility and bioactivity. Electrophoretic deposition of HA bioceramic coatings has recently attracted considerable attention because of a variety of advantages of the method of the coating fabrication, such as a low process temperature, ability to deposit on porous or complex shapes of substrate, the simple control of deposit thickness.In this paper,Silicon-substituted Hydroxyapatite (Si-HA), formulated asCa₁₀(PO₄)_6-x(SiO₄)_x(OH)_2-x, was coated on titanium by electrophoretic deposition technique.Nanometer silicon-substituted hydroxyapatite materials were fabricated by a hydrothermal method.X-ray fluorescence spectroscopy(XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy(FTIR), Transmission electron microscopy (TEM) and Differential scanning calorimetry(DSC)were used to characterized the silicon-substituted hydroxyapatite. The results show that the substitution of the silicate groups for the phosphate groups caused some OH" loss to maintain the charge balance and changed the lattice parameters of HA , furthermore, the substitution of the silicate groups restrained the growth of Si-HA crystal. DSC analysis show that the small amount of silicon incorporated into HA lattice didn't influence the thermal stability of HA.Si-HA coatings were prepared on titanium substrate by electrophoretic deposition.The influence of the coating technique conditions on adhesion strength of the coatings were studied,and the phase constitutes, microstructure, morphology,adhesion strength of coatings were studied too.The results indicate that the coatings were uniform and dense with high adhesion strength by electrophoretic deposition,the adhesion strength between coating and substrate was high to 20MPa. Furthermore,Si-HA/PCL composite coatings were prepared on titanium substrate by electrophoretic deposition.Test in simulated body fluid indicate that the coatings possessed good biological properties.