Structural Modification And Antibacterial Performance Of Ceramic Coatings On Pure Titanium By Microarc Oxidation

Currently,bone tissue or hard tissue implants have the disadvantages that the bio-activity of the implant is insufficient,and implanted in the body after the occurrence of bacterial infection led to the status of failure of surgery,pure titanium with excellent mechanical properties was studied by micro-arc oxidation treatment and hydrothermal treatment.The coatings with good bio-activity and anti-bacterial properties was prepared by micro-arc oxidation and hydrothermal treatment.The microstructures and wettability of the sample surface were measured by scanning electron microscopy(SEM),X-ray energy dispersive spectrometer(EDS),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and contact angle measurement.After immersing in SBF,the biomimetic coatings were deposited on the surface of titanium samples,and the biomimetic coatings were characterized by SEM,EDS and XRD.Gram-negative Escherichia coli(E.coli)and Gram-positive Staphylococcus aureus(S.aureus)and zinc ion release experiments were used to evaluate the anti-bacterial properties of the coatings on titanium samples anti-bacterial experiments.The pure titanium and titanium surfaces were treated with micro-arc oxidation electrolyte composed of EDTA-2Na 、 Ca(CH3COO)2·H2O 、 Ca(H2PO4)2·H2O 、Na2SiO3·9H2O、Zn(CH2COO)2·2H2O、NaOH and H2O2.For the micron-scale porous morphology,the surface consists of calcium,phosphorus,silicon,sodium and zinc elements and anatase phase,rutile phase composition.With the increase of micro-arc oxidation voltage,the micro-arc oxidation coatings of the pores were larger,and the the coatings were thicker.After the hydrothermal treatment of ammonia water,the nanocrystalline phase appeared on the surface of low ammonia concentration,and the gully-like morphology appeared on the surface of the sample after high concentration of ammonia water.With the increase of ammonia concentration,the content of calcium,phosphorus,silicon,sodium and zinc elements is reduced.The presence of zinc in the coatings after microarc oxidation and hydrothermal treatment is Zn2 + in ZnO.The wettability of titanium treated by micro-arc oxidation is worse than pure titanium,but it has been improved after hydrothermal treatment.Samples only treated by micro-arc oxidation were immersed in SBF for 14 days without formation of apatite.The surface treated by hydrothermal treatment of the sample after SBF immersed for 7 days,surface was completely covered with apatite.The anti-bacterial rate of pure titanium,micro-arc oxidation treatment,hydrothermal treatment is in turn increased.The nanocrystalline phase and the gully-like morphology formed on the titanium surface after the hydrothermal treatment provide more nucleation sites and surface energy for the formation of apatite.After the hydrothermal process,the content of zinc element increased on the surface,leading to improve the anti-bacterial properties.In summary,pure titanium after micro-arc oxidation treatment,hydrothermal treatment,biological activity and anti-bacterial properties have improved.