Papers by Keyword: Titanium (Ti)

Abstract: It is well known that titanium (Ti) has excellent properties of anticorrosion, biocompatibility and low modulus that would be applied in many clinical applications. The aim of this study wants to increase the hydrophilicity of titanium surface through silanization and then grafted with hydroxyapatite (HA) by hydrothermal synthesis method. Physiochemical analysis of grafting plate substrate was observed by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and contact angle analysis. The surfaces with silanization were strongly interaction between SiO₂ and TiO₂, and thus Ti-O-Si-bonds formed having larger surface areas but only showed a little improved hydrophilicity. The hydrophilicity of Ti substrate was largely increased after the hydrothermal process. Compared with Ti surface without any surface treatment, the surface which modified with hydrothermal synthesis can improve the wettability of Ti surfaces. Furthermore, the Ti surface through silanized modification before hydrothermal synthesis held good calcium phosphate precipitates existing due to the better calcium ion combined ability with polar bond of aldehyde group (Ti-O-Si-CO^-).

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: The use of titanium for medical and dental applications is on the rise because of their excellent biocompatibility. However, some properties of pure titanium are not sufficient. Alloying with copper can improve mechanical properties needed for dental use. A recent research on Ti-Cu cast alloy indicated that ductility decreased with increasing copper concentration, but addition of copper improved grindability and wear resistance, with lower corrosion resistance. The objective of this research is to study sintering of Ti-Cu alloys; their microstructure and hardness, and the effect of copper content to their sintered density. Ti-Cu alloys were produced via powder metallurgy. Titanium powder was mixed with copper powder with chemical composition of 2, 4, 7 and 10 wt%. Lubricant was added in alloy powder with 0.5% of total weight, followed by cold compaction under 254 MPa pressure. Debinding and sintering was carried out at 400oC for 0.5 hr and 1000oC for 1 hr respectively in argon atmosphere. Condition with highest density was found in 10wt%Cu composition; having highest hardness of 317 Hv. Differential thermal analysis of Ti-15Cu under N2 atmosphere showed exothermic reaction at 1078oC. Phase formation of the sintered alloys followed the Ti-Cu equilibrium phase diagram.

Abstract: The present paper focus on preliminary work carried out at INETI concerning the use of microwave radiation applied to sintering of both ceramic and metal powders. Due to the characteristics of materials-radiation interaction, microwaves can become an interesting power source in powder technology and other processing routes, since it is possible to lower the sintering temperature and shorten the sintering cycles, leading to time and energy savings. Alumina, hydroxyapatite, titanium and stainless steel powder compacts were sintered in a modified commercial oven of 2.45GHz and 1000W nominal power. Microwave susceptors were used to enable temperature rise during the initial stage of the sintering cycles. Results on densification and microstructural evaluation of microwave sintered samples are reported and compared to conventionally sintered ones, when available. For similar porosity levels upon sintering, microwave radiation generally reduces sintering times from several hours to minutes. The results obtained so far are quite encouraging since in the case of alumina and stainless steel compacts, a decrease of about 200°C in the sintering temperature was achieved. It was also found that the green density plays a key role in the densification of both metallic and ceramic powders.

Abstract: In the present work, Al-B4C composites were produced by casting route at 850°C and titanium-containing flux was used to overcome the wetting problem between B4C and liquid aluminium metal. The microstructure of matrix/reinforcement interface was investigated using SEM studies with or without Ti added composites. The reaction layer was also characterized with EDS analysis and X-ray mapping. It was found from the microstructural observations by high resolution field emission gun SEM (FEG-SEM) that the wetting issue was effectively solved by the formation of very thin (80-180 nm in thickness) Ti-C and Ti-B reaction layers.

Abstract: Titanium and its conventional alloys reveal a high affinity for hydrogen, being capable to absorb up to 60 at.% hydrogen at 600°C, and even higher contents can be alloyed with titanium at lower temperatures. Hydrogen exhibits a low solubility in the low-temperature hexagonal closed-packed (hcp) α phase and a very high solubility (up to 50 at.%) in the high temperature body-centered cubic (bcc) β phase. The presence of hydrogen in the amount exceeding 200 ppm leads to formation of hydrides in α and α + β titanium alloys. While the aforementioned hydrogen behavior within bulk titanium has been well-established and reviewed, this is not the case with titanium thin films. The interpretation of results in these nanosized systems is complicated because the exact determination of the hydrogen concentration is difficult. However, using electrochemical hydrogen loading technique under the proper conditions, the hydrogen concentration can be accurately determined via Faraday’s law. In this study the thermodynamics of the titanium films during hydrogen absorption were investigated by electromotive force (EMF) measurements. Titanium films of different thicknesses were prepared on sapphire substrates in an UHV chamber with a base pressure of 10-8 mbar, using ion beam sputter deposition under Ar-atmosphere at the pressure of 1,5ּ10-4 mbar. The crystal structure was investigated by means of X-Ray diffraction using a Co-Kα radiation. For electrochemical hydrogen loading, the films were covered by a 30 nm thick layer of Pd in order to prevent oxidation and facilitate hydrogen absorption. The samples were step-by-step loaded with hydrogen by electrochemical charging, which was carried out in a mixed electrolyte of phosphoric acid and glycerin (1:2 in volume). An Ag/AgCl (sat.) and Pt wires were used as the reference and the counter electrode, respectively. XRD measurements were performed before and after hydrogenation in order to investigate the effect of hydrogen loading on the films microstructure. The role of varying thicknesses on the main characteristics of hydrogen's absorption behavior, as well as hydrogen-induced microstructural changes in titanium thin films, are discussed in detail.

Abstract: Two kinds of pure titanium specimens, i.e., the first one is prepared by the ingot metallurgy (I/M) process and the second one is prepared by the metal injection molding (MIM) process were used in this experiment, and their corrosion behavior under stress has been investigated in several aqueous solutions by Slow Strain Rate Tensile (SSRT) test. Ti MIM specimen showed the larger maximum stress and the lower maximum stain than I/M Ti specimen in the deionized water. Both Ti I/M and MIM specimens indicated good corrosion resistance in the aqueous solution of 2.5 kmol/m3 H2SO4 + 0.2 kmol/m3 NaCl in which SUS304 stainless steel showed SCC, and showed the decrease of the maximum stress and the maximum strain in the aqueous solutions of CH3OH + 0.1 kmol/m3 HCl, where the brittle fracture appearance was more remarkable with an decrease of H2O in the solution.

Abstract: A new ECAP process method called rotary-die ECAP (RD-ECAP) was developed to form fine-grained bulk materials such as aluminium alloys, magnesium alloys, aluminium composites, and titanium, all of which can be processed under conditions of 573-773K, at an approximately 0.9-2.4 mm/s punch speed of 300MPa or lower. By the RD-ECAP method, ECAP processing of up to 2 passes can be done without sample removal and samples processed over 30 cycles were obtained.

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.

Abstract: Over the past years significant efforts were dedicated to developing production processes for aerospace and automotive parts from light weight titanium aluminides. Considerable progress was achieved worldwide in the field of near net shape casting. Access has developed an own production route, based on centrifugal investment casting. Various components from TiAl-based alloys, including turbocharger wheels and stator vanes were successfully cast and supplied for engine tests. A newly developed automated centrifugal casting line was recently taken into operation. This presentation will describe our activities that aimed to qualify the casting line for series production of turbocharger wheels: apart from basic issues of casting cluster design, process control and quality inspection we will discuss the casting process from the perspective of its techno-economic characteristics