Papers by Keyword: Titania (TiO₂)

Abstract: Aluminum 7075 alloy has excellent mechanical properties and exhibits good ductility, strength, toughness, and fatigue resistance. The addition of oxide additives to cast Al7075 has also enhanced tribological properties apart from these properties. In this study, the tribological properties of cast Al7075 with the addition of 2.5% zirconium oxide (Zirconia) and titanium oxide (Titania), produced in a resistance melting furnace followed by die casting, were investigated. The wear test is conducted using a pin-on-disc wear testing machine, as specified by ASTM G99. The comparison is based on two independent process variables: a fixed sliding distance of 1000 m for all samples and applied load variations are 10, 20, 30, and 50 N with 500, 700, and 1000 revolution speeds. Using a scanning electron microscope (SEM), the wear surface morphology of the samples was analyzed, and the wear test results were compared. Further, it was found that oxides added samples showed less wear loss compared to as-cast Al7075 samples. The abrasion mechanism for as-cast Al7075 samples is identified as ploughing and deep wear tracks, while for Al7075 samples with Zirconia and Titania addition, it is characterized by delamination and shallow wear marks that show less wear.

Abstract: Nanomedicine is a relatively new field of science and technology. By interacting with biomolecules, therefore at nanoscale, nanotechnology opens up a vast field of research and application. Current and potential applications of nanotechnology in medicine range from research involving diagnostic devices, drug delivery vehicles to enhanced gene therapy and tissue engineering procedures. Its advantage over conventional medicine lies on its size. Operating at nanoscale allows to exploit physical properties different from those observed at microscale such as the volume/surface ratio. This allows drugs of nanosize be used in lower concentration and has an earlier onset of therapeutic action. It also provides materials for controlled drug delivery by directing carriers to a specific location. Inorganic nanomedicine is likely to remain one of the most prolific fields of nanomedicine, which refers to the use of inorganic or hybrid (inorganic-inorganic or inorganic-organic) nanomaterials (INMs) and nanoparticles (INPs) to achieve innovative medical advances for body parts implantation, drug and gene discovery and delivery, discovery of biomarkers, and molecular diagnostics. Among the most promising INMs being developed are metal, silica, dendrimers, organic-inorganic hybrids, ceramics (e.g. ZrO₂, TiO₂, Al₂O₃, etc.) and bioinorganic hybrids. Metal NP contrast agents enhance magnetic resonance imaging and ultrasound results in biomedical applications of in vivo imaging. Hollow and porous INMs have been exploited for drug and gene delivery, diagnostic imaging, and photothermal therapy. Biomolecular inorganic nanohybrids and nanostructured biomaterials have been exploited for targeted imaging and therapy, drug and gene delivery, and regenerative medicine. Potential uses for fluorescent quantum dots (QDs) include cell labeling, biosensing, in vivo imaging, bimodal magnetic-luminescent imaging, and diagnostics. Biocompatible QD conjugates have been used successfully for sentinel lymph node mapping, tumor targeting, tumor angiogenesis imaging, and metastasis cell tracking. This article outlines present developments and future prospects for the use of Ti-based NPs and NMs in experimental in vivo and in vitro studies and in engineering nanodevices and biosensors for clinical and investigative use in diagnosis and therapy in diverse fields of medical sciences, such as oncology, infection control, orthopedics, dentistry, dermatology, genetics, cardiology, ophthalmology, etc. Toxicological considerations of these INPs and INMs are also discussed.

Abstract: In this paper, a two-step method is adopted to add titania (TiO₂) nanoparticle and silica (SiO₂) nanoparticle in commercial water-based paint to form the nano-paint with various concentrations of the added nanoparticle. The paint is sprayed onto the steel plate to form a coated film as the test samples. The experiments are implemented in order to investigate the effects of the nanoparticle on reflection spectra, surface hydrophobic and heat transfer performance of the coated film. The experimental results show that adding the nanoparticle indeed has positive effects on the above properties. This research contributes to the development of the functional paint for various applications.

Abstract: Titanium dioxide (TiO2) films were prepared on glass substrates without external heating by DC magnetron reactive sputtering. Argon and oxygen were used as sputtering and reactive gases, respectively. Initially TiO2 films were produced under a constant discharge power of 300W, total operated pressure of 1.10 Pa, the Ar:O2 flow rate of 50:45 sccm and film thickness of 300 nm. After deposition, the films were annealed in air and in vacuum (8×10-1 Pa) at a temperature of 350 °C and an annealed time of 2 hours. Films structure, optical properties, photocatalytic activity (methylene blue degradation) and photo-induced hydrophilicity properties were mainly investigated to produce self-cleaning surface. Because of higher crystallinity of vacuum-annealed films lead to the highest MB degradation under UV irradiation. While, air-annealed films showed lower MB degradation than as-deposited films that could be affected of contamination on surface and defect from annealing. Vacuum-annealed films showed changes of water contact angle on the films surface higher than as-deposited films and air annealed- films.

Abstract: A comparative study of TiO2 films on glass substrates produced by sol- gel dip coating technique using two types of titania precursors were performed. The two types of titania solutions with and without triton x-100, poly (ethylene glycol) were used to prepare the films. The dip coated films were dried at 55°C and calcined at 400 - 600°C for 4 hrs resulting in smooth and transparent TiO2 films. Morphology and phases of the films were investigated using SEM and XRD, respectively. Anatase phase was found to be dominant in all samples with various degree of crystallinity depending on the calcination temperatures and whether the templating agents were used. The templating agent was found to effectively inhibit the crystallization and growth of the crystallites of the films. Morphology of the TiO2 particles was found to be in the nanoscale level. All films fabricated were found to effectively degrade cyanide even though no obvious relations between processing method including calcinations temperature and the use of template were found.

Abstract: This work compared properties and catalytic performance of two hybrid photocatalysts, TiO2/RH-MCM-41 and TiO2/TEOS-MCM-41 prepared by loading nanoparticles of TiO2 (10 wt.%) on MCM-41 synthesized with rice husk silica and tetraethyl orthosilicate respectively. The supports and catalysts were characterized by X-ray diffraction, N2 adsorption-desorption, transmission electron microscopy and zeta potential. The photocatalytic activities of the TiO2/RH-MCM-41 and TiO2/TEOS-MCM-41 for the degradation of tetramethylammonium (TMA) in aqueous slurry were similar with a complete conversion after irradiation time of 90 min at pH 7.

Abstract: In this work TiO2 and ZnO layers have been deposited by screen-printing in common glazed ceramic tiles. These layers were evaluated for the photocatalytic degradation of Orange II in aqueous solutions, in a batch photoreactor under visible light. The photocatalytic behaviour was assessed by taking into account experimental variables which include: (i) firing temperature of the TiO2 printed layer; (ii) layer thickness; (iii) operation time; (iv) pH; and (v) dye concentration. Optimal processed layers showed an interesting decolourisation performance (over 90% efficiency after 7-8 h). It is anticipated that these new ceramic materials might be developed as an interesting alternative to TiO2 or ZnO suspensions, for example in photocatalytic applications excusing the particles removal at the end of the process.

Abstract: Titanium dioxide (TiO2) thin films were prepared by RF magnetron sputtering technique at an argon flow rate of 4.9 sccm and room temperature during 4 h. These films were deposited on pyrex substrates with an RF power of 300 W and annealed at different temperatures (500, 600, 700 and 800 °C). The optical and structural properties were studied by spectrophotometry and X ray Diffractometry respectively. The obtained results show an amorphous structure for the unheated TiO2 films and an apparition of an anatase phase after the annealing process. The transmittance is increased with an annealing of 500°C from 45 to 80 % in the visible and near-infrared regions. The direct band gap, refractive index, extinction coefficient and grain size were investigated. The reflection in the visible range for a silicon (Si(p)) substrate covered by TiO2 thin films is decreased to be about 20%. The results of this work suggest that the variation of the annealing temperature allow the control of the physical properties of TiO2 thin films as antireflective coating for silicon solar cells.

Abstract: Hydroxyapatite (HA) coatings are widely used to improve the biocompatibility of titanium substrates. The main problem concerning these coatings is related with the bad adhesion characteristic of the ceramic/metal interface. A TiO2 interlayer can be used to improve the adhesion of the coating; however the TiO2 is a bioinert material. Then, a solution can be the use of a mixture of HA-TiO2 (60% wt HA- 40% wt TiO2) powder has been sprayed by using High Velocity Oxy-Fuel (DJH-2700) for different spraying distances. The adhesion of the coatings has been mechanically tested and the values have been compared with the values obtained for coatings that have been immersed in simulated body fluid solution (SBF) after 24 and 120 hours. The crystallinity degree of the HA plays an important role on it for the dissolution affecting the behaviour of the interface at the same time it is also important osteoclastic resorption and carbonate apatite precipitation.

Abstract: The lecture will give an overview of the manufacturing technique of ceramic target materials based on ZnO and TiO2. Sintering and plasma spraying techniques are typically used. Also special bonding procedures have to be established in order to join ceramic target materials to metallic carriers. Metallic and ceramic target materials will be compared with respect to target materials processing and sputtering experiences as well. In addition planar and cylindrical targets will be briefly discussed as sputtering of large substrates is strongly moving towards cylindrical cathode applications.