甘油磷酸钙浓度对钛合金MAO涂层性能的影响OA北大核心CSTPCD

Titanium alloys have been widely used as implant materials due to their low density and elastic modulus,good biocompatibility and excellent corrosion resistance.However,they belong to bio-inert materials,which prevents the titanium implant from tightly bonding with the bone tissue.As a surface treatment method,micro-arc oxidation(MAO)can effectively improve the property of titanium alloys but may generate industrial wastewater.Therefore,selecting environmental friendly electrolytes to prepare high bioactive MAO coatings on the surface of titanium alloys will become the investigation focus.In this study,the environmentally friendly sodium phytate(Na12Phy)was used as the organic phosphorus-containing electrolyte.In addition,calcium gluconate(CaGlu2),magnesium gluconate(MgGlu2)and calcium glycerophosphate(Ca-GP),commonly used in food and pharmaceutical industries,were separately selected as the calcium and magnesium sources in the coatings.Three anodic coatings were prepared by MAO treatment under constant voltage mode in a base solution containing 20.19 g/L CaGlu2,6.24 g/L MgGlu2,5 g/L Na12Phy and 1.3 g/L phosphoric acid(H3PO4)added with 8,10 and 12 g/L Ca-GP.Coating surface morphology,chemical composition,phase structure,elemental existing stage,and roughness were analyzed by scanning electron microscope(SEM),energy dispersive X-sight spectrophotometer(EDS),X-ray diffraction(XRD),X-ray photoelectron spectrophotometer(XPS)and Atomic Force Microscope(AFM).In addition,static contact angle,bond strength and in vitro bioactivity of three MAO coatings were also measured.After MAO treatment,ceramic coatings with porous characteristics were successfully developed on titanium alloys and Ca-GP took part in coating formation.When Ca-GP was 8 g/L,the developed coating was very rough with evident micro cracks and its amounts of Ca and Mg elements were separately 7.56at.%and 1.74at.%.With the increasing Ca-GP concentration,the coating uniformity about surface micro pores became well with less micro cracks.The increasing Ca-GP concentration could improve the Ca content in MAO coatings,indicating that Ca ions entered the MAO coating by diffusion.Ca-GP concentration could significantly increase the calcium-phosphorus ratios(Ca/P)of MAO coatings and the values fabricated in the base solution with 8,10 and 12 g/L Ca-GP were separately 0.98,1.33 and 1.77.The developed MAO coatings in the solution added with 8 and 10 g/L Ca-GP were mainly composed of Ti,rutile,and anatase-type TiO2.However,in the base solution added with 12 g/L Ca-GP,the fabricated MAO coating contained TiP2O7,Mg3(PO4)2 and a small amount of hydroxyapatite(HA).Ca-GP significantly improved the coating roughness but slightly increased the bonding strength between the substrate and coating.The results obtained by measuring contact angle indicated that Ca-GP could significantly improve the hydrophilicity of MAO coatings.According to phase structure and the similar Ca/P ratio to that of HA,the prepared coating in the solution containing 12 g/L Ca-GP exhibits excellent bioactivity.The results obtained through immersion experiments in simulated body fluids show that a large amount of granular HA is formed on the surface of MAO coating fabricated in the base solution added with 12 g/L Ca-GP,which further shows that the MAO coating achieves excellent in vitro bioactivity.