Study On Electrolyte Concentration Optimization And Coating Performance Of Micro-arc Oxidation Of Medical Titanium Alloy

Titanium and its alloys are often used as alternative materials f or repairing human bone tissue due to their good corrosion resistance,excellent mechanical properties,and excellent biocompatibility.However,it can not meet all medical needs due to its biological inertia.Many studies have shown that the coating prepa red on the surface of titanium alloys by micro-arc oxidation can effectively improve its osseointegration ability.At present,there is no specific research on the effect of electrolyte concentration on the micro-arc oxidation coating based on the applicat ion of biomedicine,and the coating can be further treated by hydrothermally to improve its biological activity.In this work,Ti-6Al-4V alloy was used as the substrate to orthogonally optimize the micro-arc oxidation electrolyte concentration of Ca(CH₃COO)₂·H₂O,Na H₂PO₄·2H₂O,EDTA and Na OH,and explore the effect of electrolyte concentration on coating properties.The suitable hydrothermal treatment parameters were determined by studying the influence of hydrothermal treatment parameters on the formation of hydroxyapatite,and verified by culturing in simulated body fluids.The optimized electrolyte and hydrothermal treatment parameters were applied to 3D printed entity and porous Ti-6Al-4V alloy.The following results were obtained:The electrolyte concentration was orthogonally optimized to obtain the thickness of the each coatings within 4.47?12.69?m and the roughness of the each coatings surface is in the range of 0.38?0.95?m;the corrosion resistance of the coating samples are better than the Ti-6Al-4V substrate;the order of electrolytes affecting Ca/P is Na OH>EDTA>Ca(CH₃COO)₂·H₂O>Na H₂PO₄·2H₂O;the maximum bonding strength between the coating and the substrate can reached 63.36MPa,and the coating still remained on the sample after the tensile test;the porous coating have a certain hydrophilic properties.The surface morphology of the coatings is porous,and they are composed of rutile and anatase.After orthogonal optimization,the electrolyte concentrations were 11.44g/L Ca(CH₃COO)₂·H₂O?5.72g/L Na H₂PO₄·2H₂O?10g/L EDTA and 15.00g/L Na OH.The surface of the optimized micro-arc oxidation coating formed hydroxyapatite after hydrothermal treatment,and the hydroxyapatite grows better when the hydrothermal treatment temperature is 200°C for 24 h.It was found that the amount of hydroxyapatite formed on the surface of the hydrothermally treated coating was significantly more than the surface of the micro-arc oxidation coating without hydrothermal treatment by culturing in SBF solution.3D printing entity Ti-6Al-4V has good performance and biocompatibility after micro-arc oxidation treatment and hydrothermal treatment.The surface morphology of the 3D printed porous Ti-6Al-4V coating consists of flocculent and porous regions,and less hydroxyapatite is formed in the flocculent area after hydrothermal treatment.