Preparation And Characterization Of Iron-doped TiO₂ Nanotube Arrays And Their Corrosion Resistance

As a new inorganic semiconductor material, TiO2 nanotube arrays have attracted much attention in the field of material. In this work, TiO2 nanotube arrays ordered arrangement on pure titanium substrate have been prepared by anodic oxidation method. Then, the prepared TiO2 nanotube arrays were doped with iron element by using electrochemical anodic oxidation and chemical immersion method respectively, and the doped samples were treated by annealing. Finally, corrosion resistance of various TiO2 nanotube arrays was analyzed. the work focus on the influence of different experimental conditions and doping methods on the surface morphology and composition of TiO2 nanotubes, the changes of the crystal structure of the iron-doped TiO2 nanotube arrays after annealing treatment and corrosion resistance of TiO2 nanotubes before and after iron doping. The results were as follows:1. TiO2 nanotube arrays were prepared by anodic oxidation in acidic, neutral and organic solutions. The effect of different experimental conditions on the surface morphology of the nanotube arrays was analyzed in order to find out the optimum growth conditions of nanotubes. As a result, the type and concentration of the electrolyte and the oxidation voltage have more significant effect on the surface morphology of the TiO2 nanotube arrays than the oxidation time. The nanotubes can’t grow if the voltage and concentration is too low or too high. The size of nanotubes would no longer change when they achieve a balance of growth after a certain period of time.2. The nanotubes were doped by iron with different concentrations by anodic oxidation and chemical immersion methods, respectively. At the same time, surface morphologies of the iron-doped nanotube were investigated to obtain the optimal doping process.,The results showed that the nanotube morphology is more ordered and integrated by chemical immersion method than by anodic oxidation method. Doping in a ferric salt solution of low concentration could acquire titanium dioxide nanotube arrays with high concentration of iron ions.3. Electrochemical property was carried out on the samples before and after doping in order to evaluate the corrosion resistance of various samples. The results showed that the corrosion potential of the nanotubes decreases after low concentration of iron doping. However, the self-etching current density corresponding to the samples with low concentration of iron doping is small and passivation coating forms, which indicates the low corrosion rate.