Papers by Keyword: Anodization

Abstract: In this work, titanium dioxide nanotubes (TNTs) were prepared by anodization method with carbon cathode rather than the conventional platinum electrode. The composition of electrolyte and the anodizing voltage was fixed as constant for this research. Carbon plate was used as the counter electrode and the anodizing times were varied for 5 h and 10 h. After anodization, the samples were further annealed at 450 °C to crystallize the as-produced TNTs. Phase composition and morphology were identified by XRD and FESEM, respectively. Wettability of the samples were examined using a contact angle instrument. The results showed that the annealed TNTs were anatase phase with average pore diameter and tube-length of 28.7 nm and 284.6 nm for 5 h, and 30.0 nm and 376.5 nm for 10 h, respectively. The differences in pore diameter and length of the nanotube samples were due to the effect of anodizing time. Wettability of both annealed TNTs was also affected by anodizing time. The surface modifications and wettability results suggested potential applications in biomedical fields.

Abstract: This paper aims to comparison of corrosion properties of two titanium alloys with different grain size. These alloys are commonly used in implantology for manufacturing long term body hard tissues replacements. Surfaces of tested samples were also electrochemically anodized using fluorine ions rich environment: the main reason for anodization was to create surfaces with highly bioactive properties which can intensify healing process and result into better bonding between body tissues when they are used in implantology. It was found by direct electrochemical methods that difference of corrosion rate between anodized and non-anodized samples was not significant. Anodization results positively influenced decreasing of corrosion rate when samples were tested in aerated physiological solution (0,9 wt. % NaCl/water). Type of bonding between implant and surrounding tissue may be also predetermined by value of contact angle of tested sample and water droplet on its surface. This paper confirmed that anodization increases wettability of tested samples and lower the contact angle to ~60°. According to these results anodization process may be recommended as a profitable treatment for surfaces of tissue replacements made from titanium.

Abstract: The present work investigates the effects of microwave-assisted annealing on the granulation and photocatalytic performance of anodic TiO₂ nanotubes. The results indicate that although microwave-assisted heating can transform the amorphous TiO₂ nanotubes into completely anatase one within 5min, it brings the collapse and granulation of TiO₂ nanotubes, which weaken their photocatalytic activity. Meanwhile, the detachment and evolution of F^- rich layer to a layer of TiO₂ membrane with rounding-off surface, and the stripping of TiO₂ nanotube bottom from its body are also observed.

Abstract: Highly-organized one-dimensional arrays of copper-doped titanium dioxide nanotubes (Cu-TiNTs) were synthesized in a one-pot approach by double anodization of titanium sheets. Field-emission scanning electron microscopy showed that Cu-TiNTs have an average inner diameter of 52.13 nm, a wall thickness of 14.28 nm, and a tube length of 0.6401 μm. Fourier-transform infrared spectroscopy confirmed the presence of characteristic O-Ti-O bond of TiO₂. X-ray fluorescence spectroscopy confirmed copper-doping with an average dopant loading of 0.0248%. Even at this low dopant loading, Cu-TiNTs were shown to be photo-active in degrading Acid Orange 52 (AO 52) under UV light illumination. The kinetic profiles of AO 52 photoelectrochemical degradation were best described by the pseudo-first-order kinetic model (R² ≥ 0.991) with kinetic constants 9.42 x 10^-3 min^-1 for Cu-TiNTs as compared to 6.04 x 10^-3 min^-1 for pristine TiNTs. Overall, doping pristine TiNTs with Cu was shown to enhance its photoelectrocatalytic properties in degrading textile dyes such as AO 52.

Abstract: TiO₂ nanotube arrays (TiO₂ NTAs) were prepared by anodization method. The as-prepared TiO₂ NTAs were annealed at 450 °C for 3 h transforming amorphous TiO₂ to anatase TiO₂. The inner diameter and tube length of synthesized TiO₂ NTAs are approximately 100 nm and 1.0 mm, respectively. Electric double-layer capacitor (EDLC) was fabricated using TiO₂ NTAs as electrodes with 6 M KOH electrolyte. The internal resistance of the EDLC is relatively low (3.8 – 6.5 Ω) depending on the operating temperature. This work confirmed experimentally the use of TiO₂ NTAs as EDLC electrodes.

Abstract: Silver-doped TiO₂ nanotubes (Ag-TiNTs) were synthesized in a top-down approach by single-step anodization of titanium sheets. The highly-ordered array of Ag-TiNTs was confirmed by scanning electron microscopy with an average inner diameter of 41.28 nm and a wall thickness of 35.38 nm. Infrared spectroscopy confirmed the presence of O-Ti-O bonds. Analysis of the X-ray powder diffraction profiles showed the characteristic peaks for anatase and titanium for both pristine TiNTs and Ag-TiNTs. Ag-doping caused no observed changes in the crystalline structure of pristine TiNTs. High-definition X-ray fluorescence spectroscopy revealed that the synthesized Ag-TiNTs have 0.05 wt% Ag-loading. Even at low Ag-loading, the Ag-TiNTs were shown to be photo-active, achieving 10.13% degradation of Acid Orange 52 under UV illumination after 120 min.

Abstract: The present study is focused on analysing the change of colours of anodized titanium and effects of applied electrolytic voltages on chromatics. The titanium specimens were anodized in 20 g/L citric acid and 20 g/L baking soda electrolyte by use of different voltages. The colours of anodized titanium were measured with a spectrophotometer and then evaluated in the CIELAB colour space. It is found that different volt produces different colours. Anodizing in the range of 15 V to 150 V produces respectively a wide spectrum of colour ranging from brown to fuchsia. It can be concluded that the colours of the anodized titanium are dependent upon the applied voltages.

Abstract: Titanium dioxide (TiO₂) nanotubes with a highly ordered structure were grown by a self-organized anodization process. The photodeposition process was used to improve the visible light response of titanium dioxide (TiO₂) nanotubes. The irradiation was carried out with 500 W halogen lamp for 1, 5, 15, 30 and 60 min in the mixed ethanol solution of antimony trisulfide (Sb₂S₃). The obtained samples were annealed at 250 °C for 30 min. The morphology of the fabricated sample was characterized by a field emission scanning electron microscope (FE-SEM). The phase of samples was determined by X- ray diffractometer (XRD). The weight percentages of a component in the sample were measured by X-ray fluorescence spectrometry (XRF). UV-Vis diffuse reflectance spectra (DRS) of the samples were recorded. All titanium dioxide (TiO₂) nanotube samples prepared by anodization process were anatase phase. All composite titanium dioxide (TiO₂) nanotube /Sb₂S₃ samples were a crystalline phase. The percentage of Sb and S increase with increasing of photodeposition’s time. The increasing photodeposition of antimony trisulfide (Sb₂S₃) on titanium (TiO₂) nanotubes from 1 to 60 min lead to increasing of photoabsorption property of the material in the visible region.

Abstract: The energy materials such as titania (TiO₂) and alumina (Al₂O₃) are the environmental friendly materials. In this paper the nanostructure of high surface area titania and alumina are fabricated by anodization process and assistance in electrochemical mold. In general, academic or research institutes can simply control the required experimental conditions in a small sample; however, it’s difficult to control the stable parameters in a large surface and a large number of nanostructural products in the industry production. In order to solve the problems of unstable current density and temperature we have designed a cooling functional electrochemical mold which can improve the nanostructural quality of energy materials during a large number production. The electrochemical mold is used for a local surface treatment at an isothermal temperature controlling. The mold limits sample for a specific treated area and current density in the electrolyte. The mold can be used for the assistance of electrolysis, electro-polishing, electro-deposition, anodization, etching, chemical deposition, pickling, and caustic processes. The mold structure includes fixture group, water-cooling electrode group, and electrode conductive group.

Abstract: Zirconia (ZrO2) nanotubes were prepared by anodization of zirconium (Zr) foil in a glycerol-formamide electrolyte containing ammonium fluoride. The effects of anodizing voltage and temperature on the pore diameter and thickness of the resulting nanotube array were studied. ZrO2 nanotubes with larger pore diameter were formed at higher anodizing voltage and temperature. Additinally, the thickness of the oxide layer was also increased. The applicability of the ZrO2 nanotubes for adsorption of heavy metals in aqueous solution was evaluated using Pb (II) as the model ions. Generally, the uptake of Pb (II) was increased at longer adsorption time and higher initial concentration of the adsorbate.