Study On The Fabrication And Bioactivation Of Titania Nanotube Arrays

In this text, In order to perfect the formation mechanism of the titania nanotubearrays, exploit a suit of new craft for the fabrication of anodic oxidation titania nanotubearrays and exploit various methods for the activation of titania nanotube arrays, thefabrication and activation of the titania nanotube arrays were studied detailed. Thesamples were tested by SEM, TEM, XRD.At the present, HF solution as electrolyte was studied detailed, the results indicatethat titania nanotube arrays could be obtained in 0.1～0.5wt%HF solutions by anodizationof titanium at 10～20V voltage and that more time is needed for the formation of titaniananotube arrays in low concentration of HF solution. A suit of new craft usingNH₄F/H₂SO₄ solution as electrolyte was exploited out. The results indicate that titaniananotube arrays could be obtained in 0.24～1.75mol·L^-1 H₂SO₄+0.5～1wt% NH₄Fmixture solutions at 20V voltage and that longer titania nanotube arrays could be obtainedin low acidity electrolyte by extending the time of anodization. During the formationprocess, the variety of current was observed. The current-time curves implied that theevolvement process of titania nanotube arrays include three stages.The activation of titania nanotube arrays was studied detailed firstly in this text.Various methods were exploited out for the activation of titania nanotube arrays. Thesemethods include heat treatment, NaOH alkali-heat treatment, Ca(OH)₂ hydrothermalprocesses, and hydroxyapatite filling method.In the heat treatment study, the result indicated that titania nanotube arrays changedfrom amorphous to anatase at 300℃～500℃and to rutile ultimately as the rising of thetemperature, the micrographs of titania nanotube arrays took place collapse at 600℃andwas destroyed completely at 700℃, and that the bioactivity of titania nanotube arrays lieson its the crystal structure, ranked in following series: mixture of anatase and futilestructure＞anatase＞amorphous.In NaOH alkali-heat treatment and Ca(OH)₂ hydrothermal processes studies, theresults indicate that existence of titania nanotube arrays on titanium could shorten thetime of NaOH treatment from 24h to 30min to get bioactive titanium, and that saturatedCa(OH)₂ could activate titania nanotube arrays by hydrothermal treatment at 200℃for1h. Hydroxyapatite filling method is that fill hydroxyapatite sol into the tubes of thetitania nanotube arrays and then change it into hydroxyapatite by heat treatment for thefabrication of HA/titania nanotube arrays composite materials, which is bioactivity. Thestudies implied that the optimum fabrication temperature of composite material is 500℃and that hydroxyapatite was successfully filled in the tubes of titania nanotube arrays. Thebioactivity of composite material was investigated by immersion of material in simulatedbody fluid (1.5SBF) for 5 days, a bone-like apatite layer formed on the material surfaceindicating good bioactivity for composite material.All of the activation studies implied that the appearance of titania nanotube arrayswill be propitious to the progress of bioactivity material and will bring the bone implantmaterial into a new date.