The Preparation And Characterization Of Bioactive Coating On Titanium

Titanium(Ti) and its alloys are widely used in restorative surgery such as artificial knee joint,Loin,orthopedic implants and false tooth,because of their high mechanical properties and biocompatibility.However,there are still some drawbacks in practice that have limited the further use of titanium.Because of bio-inertia,titanium implant can't form firm chemical bond with surrounding tissue.Furthermore,it can release metallic ions into surrounding tissue,and damage them.In order to overcome the problems mentioned above,researchers have been trying to modify the surface of titanium.Much research has been done towards to raising the bioactive of titanium implants by prepared HA coatings on titanium,and promoting growth of tissue surrounding the implant to lessen pain.In the present work,the HA coating was prepared by sol-gel.TiO₂ coating was deposited on titanium by MAO.FHA coating was prepared on TiO₂ to form FHA/TiO₂ by sol-gel.The influences of aged time of HA gel and High-energy shot peening(HESP) on titanium substrate on hydroxyapatite coating by sol-gel was discussed.It has also been investigated that the influences of micro-arc oxidation time on microstrure,composition of TiO₂ coating,and F content of fluoride hydroxyapatite on bioactivity.During the formation process of HA coatings,the HA sol was prepared with P₂O₅-Ca (NO₃)₂-anhydrous ethanol.The DSC,TG,rotation viscometer were used to analyze the HA sol.The results show HA sol after 3 days aged fit better for coating.Because it has higher ability to cling to titanium substrate,reduce flaw of the coating.HA coatings were prepared on HESP and Polishing substrates.XRD and the trail of dynamic-clotting blood show the coating on HESP substrate has strong integrality,fewer flaws,and better biocompatibility.HA coating is more likely to deposit on HESP substrate,which can reduce deposit frequency.And the cohesion of coating and substrate is higher,enhanced from 13 MPa of polishing sample to 25MPa of HESP sample.In addition,TiO₂ coating containing a few Ca,P elements was prepared by micro-arc oxidation.Our research was focused on the influence of oxidation time on the coatings.XRD, SEM,Contact angle meter,contour graph and electrochemical corrosion were used to analyze to coating.The results show that phase transformation from anatase to rutile happens during MAO treatment,the thickness,surface porosity and pores size and roughness concentration of the film increases with the extension of oxidation time.The electrochemical studies show that corrosion resistance of TiO₂ coating improves the oxidation time extension,the coating has best corrosion resistance about 3min,and then reduce as the time extension.FHA coating was deposited on titanium substrate after MAO treatment to form FHA/TiO₂ composite coating by Ca(NO₃)₂-P(C₂H₅O)₃-NH₄F-anhydrous ethanol.Control the content of fluorine in apatite through introducing different fluoride additives.The cohesion of coating and substrate is about 35MPa,was measured by tensile test.Biological mineralization experiment shows that FHA enjoying mineralization ability approximate to HA.Results of analysis show F1 is fit better as implant material.