The Preparation Of Composite Coating Of Nano-hydroxyapatite/TiO₂Nanotube Arrays

In order to improve the biological activity and biocompatibility of titanium implants, the paper describes the preparation of titanium nanotube arrays in the surface of titanium by two-step electrochemical anodization. In addition, the nano HA/TiO2nanotube array composite coating was prepared by the simulated body fluid immersion method and the electrochemical deposition under magnetic fields respectively. The composite materials has high strength and toughness of metal materials, and exhibits good biological properties of HA.The TiO2nanotube arrays coating growing perpendicular to the titanium surface was prepared, which was continuous distribution and dense arrangement. The results show that the surface topography of nanotube arrays was affected by HF concentration in electrolyte, oxidation time, oxidation voltage, and so on. In addition, the mechanism of TiO2nanotube arrays formation was studied by the dynamic change of anodic oxidation rate uelectro and dissolution rate UdiS in the oxidation process. SEM images of nanotubes show that:in a certain range of concentration, HF concentration determined the wall thickness of TiO2nanotube, thereby affecting the diameter; oxidation time could determine the length of TiO2nanotubes; anodizing voltage controlled the diameter of TiO2nanotubes.HA/TiO2nanotube arrays composite coatings was obtained by putting nanotube arrays coating immersed in simulated body fluid (SBF). TiO2nanotube arrays substrate was dipping treatmented before the SBF immersion test, which resulting in shorting the immersion time effectively.4-day immersion test showed that, TiO2nanotube arrays could induce the formation of dense HA coating. The optimum preparation conditions of nano-HA/TiO2nanotube array composite coating is obtained by investigating the following factors which influence the property of composite coating:the phase of nanotubes, shaking in immersion, dipping before immersion and surface topography of nanotube arrays.Moreover, nHA/TiO2composite coating is prepared on the titanium substrate with the nanotube array by the electrochemical deposition under the magnetic field. The characteristics of the composite materials show that:with the increasing of the diameter of the nanotube scale, the bonding force between the nanotube array and nHA is higher. In addition, the advantages and disadvantages of two methods for preparing nHA/TiO2nanotube arrays composite coating were compared. Tension test show that:In the nHA/TiO2nanotube array coating fabricated by electrodeposition under the magnetic fields, nHA crystal implant in the nanotube, which resulting that the bond strength between the nHA and substrate was significantly higher than the HA coatings adhering to the surface of nanotubes arrays prepared by simulated body fluid method.