Research On Preparation And Growth Mechanism Of Ti-6Al-4V Micro-arc Bioceramic Coating

The bioceramic coating was prepared on the surface of Ti6A14V by the method of Micro-arc Oxidation (MAO). The electrolyte solution was not replaced during the MAO process. The oxidation parameters demand of electrolyte met by replacing the Ti6A14V specimens. Oxidation parameters were referred to as oxidation time and area. The effect of electrolyte composition change on the morphology and microstructure composition and properties of the ceramic were studied. Experiment of the ceramic immersion in simulated body fluid (SBF) was processed to verify the biological activity of coating.The affect of electrolyte formula on properties of coating was studied by single factor method in the electrolytes composed of Na2HPO4and KOH. The MAO electric parameters were optimized by orthogonal analysis. The results showed that:the optimal concentrate of the electrolyte solution were4.75g/L Na2HPO4and2.0g/L KOH; The optimal electrical parameters and oxidation time were400V,600Hz,45%,15min. The coating had uniform pore distribution and large specific surface area under the above conditions. The change of electrolyte composition was studied, the results showed that the concentration of the phosphate decreased and titanium ion increased. The rate of changes in the concentration of phosphate decreased. The rate of titanium ion increased first and then decreased which increased to the maximum at level2electrolyte oxidation parameters. The number of surface microporous increased significantly, the discharge aperture and surface roughness decreased, phase composition transformed from the beginning of rutile and anatase mixed crystal type TiO2and a single anatase phase at the end with the change of electrolyte composition.The biological activity of coating was studied by SBF test, it indicated that the coating surface deposited a layer of spheroid calcium deficient apatite which was similar to natural bone in components, and had good biological activity during7days SBF culture. But the apatite deposition size increased, the uniformity of the distribution declined and there were other materials attached to the interface of spheroid deposits with the increase of electrolyte oxidation parameters. The electrolyte was replaced in order to ensure the quality and biological activity of coatings when the electrolyte oxidation parameters reached2level.