The Controllable Preparation And Optimization Of Nanotube Arrays On Ti And Ti Alloy

Ti and Ti alloys are widely used as the implants in biomedical filed dueto its good biocompatibility, bio-inertness, high strength, modulus closing tobone’s modulus. One key problem of implanting joint prosthesis into humanbody is that titanium prosthesis does not bind tobones well; thus, it’s necessaryto modify the surface of titanium implants for improving its biocompatibility.Recently, vertically grown TiO2nanotubes on Ti and Ti alloys have beendeveloped. The tubular structure can serve as the site of drug loading as wellas the growing point of osteoblasts, and we can control the diameter and lengthof nanotube by altering the experimental conditions, which is useful forregulating the drug loading and release.Firstly, TiO2nanotube arrays on Ti substrate were prepared byanodization method, and the influence of voltage and time on the morphologyof nanotube arrays fabricated in inorganic and organic electrolyte wereinvestigated. It was found that TiO2nanotube arrays could be obtained when voltage was from10V to25V, and the diameter and length of nanotube bothbecame larger with increasing voltage, because the horizontal and verticalelectric field intensity was bigger. And anodizing time had an effect on thelength of nanotube, the TiO2nanotube grew from187nm to279nm when thetime increased from30min to120min. The morphology of nanotube arraysprepared in inorganic solution was irregular and the length only reachedseveral hundred nanometers due to high concentration of H+, and we achievedordered and longer nanotube arrays by changing the electrolyte into ethyleneglycol containing0.09M NH4F.Compared with the TiO2nanotube arrays obtained on pure Ti, thenanotube fabricated on Ti-35Nb-2Ta-3Zr alloy had higher surface roughness,and elements Nb, Ta, Zr existed in nanotube. Different from the nanotubes withvarious sizes in previous researches, nanotube arrays with uniform diameterwere achieved by using ethylene glycol (EG)/NH4F organic electrolyte,indicating the electrolyte composition influenced the arrangement of TiO2nanotube arrays.In addition, the effect of deformation of Ti-35Nb-2Ta-3Zr alloy on themorphology, crystal phase and grain size of nanotubes was studied. When thedegree of deformation became larger, the corrosion potential Ecorrof the alloysshifted to the positive direction, which suggested an enhanced anticorrosion ability and resulted in nanotubes with smaller diameter. After heat treatment,anatase TiO2was obtained. Because of the existence of lattice distortion, thegrain size of TiO2nanotubes prepared by Ti-35Nb-2Ta-3Zr alloy withdeformations was smaller than that of with no deformation. However, whenthe reductions of alloy increased, there was a tendency to make the grain sizelarger, which was probably caused by the restriction of the wall thickness ofnanotubes.Finally, we conducted the structural optimization for TiO2nanotube. TheTiO2nanotube arrays with highly order were achieved by two-step anodization,and the multi-layer nanotube arrays were obtained by simple multi-anodizationmethod, which provides a basis for its application on the drug-loading in thebiomedical field.