Cati <sub> 4 </ Sub> (po <sub> 4 </ Sub>) <sub> 6 </ Sub> Biological Ceramic Membrane Preparation And Characterization,

The CaTi4(PO4)6 (CTP) bioactivity ceramic film was prepared on pure titanium by microarc oxidation (MAO), and the bioactivity of CTP film was examined by soaking in the simulated body fluid (SBF) in vitro. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse X-ray dpectrometric microanalyzer (EDX), and atomic emission specrometry (ICP-AES) were used to optimum the process of preparation of CTP film. The electrolyte concentration, Ca/P mole ratio, pH value, temperature, and current density were studied on the growth of CTP film. The mechanisms of the growth of microarc oxidized film and bioactivity of the CTP film were studied.The experimental results showed that electrolyte concentration had considerable influence on the MAO process. The breakdown voltage of MAO decreased with increasing electrolyte concentration. And the degree of crystalline of the film became lower when the MAO time decreased. When the electrolyte concentration was low (<40g·L-1), the film weight showed a lineal relationship with oxidation time. While the concentration increased, the two had a complicate relationship. The pH value did not affect the MAO process within a certain range (pH≤12), but it had an important role on the crystallinity of the film, and the film crystallinity decreased with increasing pH value. The surface roughness rose with increasing temperature. Based on the analysis above, the optimized process parameters of MAO were the electrolyte concentration of (NaPO3)6 being 25g·L-1, the Ca/P ratio of electrolyte being 1/6, the electrolyte pH being 12, the current density being 100mA·cm-2, and the reaction temperature being 25℃.Using 1×SBF to assess the CTP film active, the results showed that granule HA was observed on the CTP film surface after soaking for 14 days in SBF. At higher magnification, the film exhibited a reticulin fiber or a plate-like structure, which means the CTP film possed excellent bioactivity.According to the experimental results, the mechanism of inducing HA formation was studied. Firstly, the porous structure of CTP film surface provide a large amount of activate place for HA sediment; Secondly, the hydrophilic of CTP film helps reduce the nucleation energy of HA surface; Thirdly, CTP structure belongs to the sodium zirconium phosphate family (NaZr2P3O12,NZP). This crystal structure has three types of interspaces that can be occupied by different ions. Thus, it is possible for the CTP film to absorb the ions of SBF to increase the local degree of calcium and phosphorus supersaturation, and then the HA can be precipitated on the CTP film surface.