Study On The Microstructure Evolution And Performance Of Copper-containing TiO₂ Ceramic Coating Prepared By Micro-arc Oxidation

Titanium and titanium alloys with high specific strength,good biocompatibility and machining performance are widely used in fields of artificial teeth,artificial joints and other hard tissue implants.However,there are still some shortcomings sush as insufficient antibacterial properties,low biological activity,insufficient corrosion resistance and so on.After implantation in the human body,titanium and its alloys easily lead to implant loosening and implantation failure,which severely restrict titanium in biomedicine.In order to simultaneously enhance the antibacterial performance,biological activity and corrosion resistance of titanium-based implants,the Cu-containing TiO₂ coatings was prepared in the electrolyte including calcium acetate(Ca(C₂H₄O₂)₂·H₂O),sodium dihydrogen phosphate(Na H₂PO₄)and different contents of ethylenediaminetetraacetic acid disodium copper(C₁₀H₁₂Cu N₂Na₂O₈·x H₂O)(expressed by Na₂Cu-EDTA)by the micro-arc oxidation(MAO)method.The surface and cross-sectional morphology,chemical composition and phase structure of the coating were characterized and analyzed.On this basis,the antibacterial property,osteogenic function,cell compatibility and corrosion resistance of coatings were evaluated,and the early corrosion conditions in different simulated human environments were explored.Finally,the formation mechanism of the Cu-doped TiO₂ coating was deeply studied.The colutions are shown as follows:The surface of the TiO₂ coating doped with 0?5 g/L Na₂Cu-EDTA has a uniform porous structure,with pore diameters ranging from tens of nanometers to 6?m.The coating is mainly composed of anatase and rutile phases,and the coating thickness is 9?13?m.The Cu element is evenly distributed in the coating.The Cu-doped TiO₂ coating has an obvious bactericidal effect on Staphylococcus aureus.When the addition amount of Na₂Cu-EDTA reaches 2 g/L or more,the antibacterial rate reaches 90%.When the Na₂Cu-EDTA addition amount does not exceed 2 g/L,it shows better osteogenic performance and better cell compatibility.Compared with untreated pure titanium,the coating after micro-arc oxidation treatment shows better corrosion resistance.At the same time,it is found that the incorporation of Cu slightly improved the corrosion resistance.In addition,the corrosion of different samples in simulated human body fluids in the presence of H₂O₂ or/and bovine serum albumin(BSA)is also studied.The results show that the presence of H₂O₂ or/and BSA has an impact on the corrosion resistance of the coating.In the study of TiO₂ coatings with different Cu contents,it is found that the TiO₂ coatings containing 10 g/L Na₂Cu-EDTA exhibited non-uniform appearance characteristics,that is,black areas at the edges and brown areas at the center.The microstructure characterization shows that the black area is mainly composed of the inner TiO₂ layer and the outer porous Ca and P-rich layer containing nano-hydroxyapatite(HA).The difference in the appearance and color of the coating is mainly related to the existence of copper.The central area mainly contains Cu₂O,and the edge area is dominated by Cu O.Biological examination reveals that the peripheral black area exhibits improved bone formability and enhanced antibacterial capability in comparison to the central brown area.This work discusses the microstructure,formation mechanism and various properties of the copper-doped micro-arc oxidation coating,which provides guidance for the application of micro-arc oxidation in biomedicine.