Fabrication And Propertites Of Oxide Nanotube Array

Due to their novel properties, composite titanium oxide nanostructures have been widely used in photocatalitic, sensor and biomaterial fields. In this work, the process of NiTi, TiNbZr, TiAlV and TiNbTaZr alloys anodized in organic solutions have been investigated, and the uniform doped titania nanotubes have been prepared. Based on the optimal anodization parameters, the tests on their hydrogen sensing properties and wetting behavior have been experimented.The results show that anodization media, temperature, voltage and time have a sound impact on Ni-Ti-O nanotubes. Only anodized in 0.15M (NH4)2SO4+0.2M NH4F glycol (5vol%) and glycerol mixed solution and under 30oC, 30V, 1.5h,can the even and top-open Ni-Ti-O nanotubes fabricated. Ni/Ti atomic ratio along the growth direction of the Ni-Ti-O nanotubes could keep at a certain level during the whole anodization process, which could demonstrate a good biocompatibility and corrosion resistance in many biomedical applications. In addition, Ni-Ti-O nanotube arrays grown on the shape memory alloy could only withstand a temperature lower than 400°C. Thus, the handling of Ni-Ti-O nanotube arrays for medical applications or other occasions should be limited to the above temperature.Anodization in the nonaqueous glycerol-based electrolytes is beneficial to avoid the uneven anodization at two-phase regions in Ti35Nb5Zr and TiNbTaZr alloys, but not in Ti6Al4V alloy. The anodic Ti-Nb-Zr-O, Ti-Nb-Ta-Zr-O andTi-Al-V-O nanotubes are underneath a layer of nanoporous structrure. The anodization temperature and voltage cannot dissolve this nanoporous layer. Ti-Nb-Zr-O nanotubes show certain hydrogen sensing properties in the room temperature. Although Ti-Nb-Zr-O namotubes have larger response to the hydrogen atmosphere under low hydrogen concentrations, they present the lower stability and repeatability. As a result, the doping of Zr element has reduced the sensing properties of Ti-O nanotubes. Among all the Nb, Zr- doped titanium alloys, Ti-Nb-O nanotubes, fabricated on Ti35Nb base, anodized at 30oC and heattreated at 450 oC, can achieve the best wetting behavior. Similarly, Ni-Ti-O nanotubes anodized at 30oC, 30V, 1.5h and heattreated at 400 oC can have the best wetting behavior.