Thin Titanium Layer Research Articles

Enhanced proliferation of pre-osteoblastic cells by dynamic piezoelectric stimulation

This work reports on the influence of the polarization of electroactive poly(vinylidene fluoride), PVDF, on the biological response of cells cultivated under static and dynamic conditions. Non-poled and “poled +” β-PVDF with and without a titanium layer were thus prepared. A thin titanium layer was deposited on PVDF films in order to obtain a more homogeneous surface charge. The MC3T3-E1 osteoblast cell culture exhibited different responses in the presence of PVDF films. The positively charged β-PVDF films promote higher osteoblast adhesion and proliferation, which is higher under dynamic conditions on poled samples, showing that the surface charge under mechanical stimulation improves the osteoblast growth. Therefore, electroactive membranes and scaffolds can provide the necessary electrical stimuli for the growth and proliferation of specific cells.

Surface modification of titanium by chemical and thermal methods – electrochemical impedance spectroscopic studies

The surface modification of untreated, alkali treated and alkali heat treated titanium has been investigated by electrochemical impedance spectroscopic technique. The substrates were treated with 10M NaOH aqueous solutions and subsequently heat treated at 600°C, a thin sodium titanium layer was formed on their surfaces. Thus, the treated substrates formed a dense and uniform bone-like apatite layer on their surfaces in simulated body fluid (SBF) solution. This indicates that the alkali and heat treated titanium bond to living bone through the bonelike apatite layer formed on their surface in the body. Electrochemical impedance spectroscopic (EIS) experiments were performed in SBF solution as a function of immersion time. Data of EIS were taken for untreated and the results revealed the formation of one additional layer along with the barrier layer. In case of alkali treated sample, titania gel layer alone dissolves completely and forms apatite and barrier layers, whereas, the alkali and heat treated samples showed three layers namely apatite, gel and barrier layers. The nature of these layers has been obtained by fitting the EIS data to suitable equivalent electrical circuit models. The alkali heat treated titanium results in the faster apatite nucleation and growth on the surface. Immersion in SBF solution exhibited higher apatite film resistance compared to alkali treated and untreated titanium substrate.

Synthesis and characterization of flexible one-dimensional TiO2 nanocrystalline films

The flexible oriented one-dimensional (1-D) TiO2 nanocrystalline films with large length-diameter ratios were synthesized in 1 M NaOH solution by hydrothermal treatment of the thin titanium layer which was deposited on flexible stainless steel substrates by direct current magnetron sputtering. The films were characterized, respectively by field emission scanning electron microscopy (FESEM), X-Ray diffraction (XRD), and transmission electron microscopy (TEM). Results showed that the TiO2 films were composed of oriented single-crystalline anatase nanowires, and the morphology of the nanowire film was determined by hydrothermal conditions. The photoelectric property studies revealed that the photoelectric property of TiO2 films was improved with the increase of the hydrothermal temperature. This approach provides an alternative method to synthesize 1-D TiO2 nanocrystalline films on non-Ti substrates.

Ellipsometric investigation of the mechanism of the formation of titanium oxynitride nanolayers

The formation mechanism of insulating titanium oxynitride nanolayers was studied by means of spectroscopic ellipsometry. The parameters of the model for solving the inverse problem of ellipsometry were chosen on the basis of experimental data obtained with the help of high-resolution transmission electron microscopy, atomic force microscopy, UV and X-ray photoemission spectroscopy. The layers were obtained using the plasmachemical nitridation of thin titanium layers on silicon substrate. The features of nanolayer preparation procedure (low temperature and short process time), as well as good masking characteristics (the minimal density of pores and defects, and the perfect smoothness of the surface) allow one to use these layers for chemical and electron passivation and stabilization of the surface of semiconductor nano-objects (quantum dots, quantum wires, nanowhiskers etc.) for electron and photon nanodevices.

Direct electroreduction of oxides in molten fluoride salts

A new kind of electrolyte composed of molten fluorides has been evaluated in order to perform a feasibility study of the direct electroreduction reaction. The direct reduction of SnO 2 and Fe 3O 4 was realised in LiF–NaF at 750 °C and in LiF–CaF 2 at 850 °C for TiO 2 and TiO. The electrochemical behaviour of these oxides was studied by linear sweep voltammetry: a current corresponding to the oxide reduction was evidenced for TiO 2, SnO 2 and Fe 3O 4. After galvanostatic electrolyses, a complete conversion was obtained for all oxides, except TiO, and the structure of reduced Ti and Fe samples had a typical coral-like structure while dense drops of Sn were recovered (Sn is liquid at operating temperature). After TiO electrolysis, a thin external metallic titanium layer was detected, acting as a barrier for the oxide ion diffusion and no complete reduction can be achieved. This could be explained by a Pilling–Bedworth ratio around 1 for Ti/TiO.

Multi-scale mechanical analysis of thin titanium layer on UHMWPE substrates for biomedical applications

We present a multi-scale scratch resistance analysis of thin titanium layer with thickness varying between 0.5 and 1μm, deposited on two biomedical polymeric substrates (UHMWPE). Using different experimental set-ups with specific tip radii, we have performed scratch experiments at various testing conditions. First, nano scratch tests have been performed with a spherical indenteur (tip radius R=22μm) with increasing progressively the normal applied load between 1 and 100 mN. Then, macro-scratch tests have been realized with a spherical indenter (tip radius R=200μm) with the same experimental procedure by applying normal load in the range of 0.5 to 15N. Finally, experimental results about multi-pass scratch tests at low average contact pressure are presented. Scratch experiments have been performed using a specific built-in microvisioscratch device that allows in situ observations of the contact area and of the residual groove during tests. About 100 repeated scratch experiments have been realized in the same track with a glass spherical indenter (tip radius R=3.3mm) at a constant normal load of 5N. Friction coefficient evolutions are studied as function of the scratching conditions and some correlations have determined with damage mechanisms observed by SEM and chromatic confocal microscopy.

Temperature measurements near the contact line of an evaporating meniscus V-groove

Evaporation from a meniscus of heptane liquid in a V-groove geometry is experimentally investigated. A thin layer of titanium coated on the backside of the fused quartz groove is electrically heated to provide a constant heat flux. The temperature profile in the evaporating thin film region of the extended meniscus is measured using high-resolution infrared thermography and the temperature suppression in this region is obtained as a function of liquid feeding rate. The meniscus shape is captured using a goniometer. A temperature suppression of ∼0.2K in the 150μm region surrounding the contact line on each side indicates the efficacy of evaporation in the extended meniscus. At a given axial location, the fraction of total meniscus heat transfer which takes place in a 50μm sub-region measured from the contact line is estimated by an approximate heat balance analysis to be ∼45% for the range of liquid feeding rates explored.

Chromatographic behavior of food additives on thin layers of titanium(IV) silicate ion-exchanger

The chromatographic behavior of acetaldehyde, o -anisidine, ascorbic acid, benzoic acid, butylated hydroxyanisole, butylated hydroxytoluene, butyraldehyde, butyric acid, cinnamaldehyde, fumaric acid, furfural, lactic acid, lauric acid, maleic acid, DL -malic acid, 1- octanol, oleic acid, propionic acid, propyl gallate, salicylic acid, sodium benzoate, sodium nitrate, sodium nitrite, sodium sulfite, sodium tartrate, sodium thiocyanate, sodium thiosulfate, sorbic acid, tartaric acid, and vitamin E has been studied on thin layers of titanium(IV) silicate ion-exchanger using several aqueous, organic, and mixed mobile phases. Rapid separations of one food additive from many other food additives, and quaternary and ternary separations are reported. The term SR F has been introduced to quantify the separating power of the adsorbent. The effect of salt concentration on R F has been studied and is discussed.

Improvement in Oxide-Pattern Sizes Controllability on Scanning Probe Nanolithography

Pattern size controllability of SPM-based nano-lithography especially in vertical direction was improved using in-situ height and depth measurements at the processed point. The transient oxide growth was monitored by light transmission (depth of the oxide in sample metal surface) and topographical signals measurements obtained from a scanning near-field optical microscope. First, we investigated oxidizing rate limitation on titanium film. At the voltage rise faster than 10 V/sec, the depth growth didn’t follow the voltage change in spite of immediate upheaval growth. This result suggested the rate determining of reactive chemicals transport in the titanium oxide. Next, we discovered improvement in the process stability on intractable materials (e.g. iron group elements or noble metals; manganese in this paper) by using thin cap layer of titanium. As the result, the oxidization reaction progressed moderately due to the facts that the oxide of the cap layer is electrical insulative and restriction of the permeability of the reactive chemicals (ingredients of the oxide) that were electrochemically generated at apex of the probe tip.

Electrical Nanocontact Between Bismuth Nanowire Edges and Electrodes

Three methods for attaching electrodes to a bismuth nanowire sample were investigated. In the first and second methods, thin layers of titanium and copper were deposited by ion plating under vacuum onto the edge surface of individual bismuth nanowire samples that were encapsulated in a quartz template. Good electrical contact between the electrodes and the nanowire was achieved using silver epoxy and conventional solder on the thin-film layers in the first and second methods, respectively. In the third method, a low-melting-point solder was utilized and was also successful in achieving good electrical contact in air atmosphere. The connection methods showed no difference in terms of resistivity temperature dependence or Seebeck coefficient. The third method has an advantage in that nanocontact is easily achieved; however, diffusion of the solder into the nanowire allows contamination near the melting point of the solder. In the first and second methods, the thin-film layer enabled electrical contact to be more safely achieved than the direct contact used in the third method, because the thin-film layer prevented diffusion of binder components.

Structural characterization of highly textured AlN thin films grown on titanium

A pulsed direct current (dc) reactive ion beam sputtering system has been used to synthesize highly c-axis oriented aluminum nitride (AlN) thin films on (0002)-oriented 200-nm thin titanium layers deposited on a Si-(111) substrate. After a systematic study of the processing variables, high-quality polycrystalline films with preferred c-axis orientation have been grown successfully on the Ti (0002) layer using an Al target under a N2/(N2 + Ar) ratio of 70%, a 2 mTorr processing pressure, and keeping the temperature of the substrate holder at ambient temperature (no substrate heating). The crystalline quality of the AlN and the underlaying Ti thin films was characterized by high-resolution x-ray diffraction. Best ω- full width at half maximum values of the (0002) reflection for 1-μm thin AlN layers are 0.56°. Hence, the AlN layers show a high degree of orientation in the (0002) direction, which directly translates into a high Q value piezoelectric response. Atomic force microscopy measurements were used to study the surface morphology of the Ti layer in an attempt to understand its impact on the quality of the AlN films deposited on top of them. Transmission electron microscopy cross-section analysis has been carried out to investigate the AlN/Ti interface. Our observations reveal the presence of crack-free layers with a smooth surface and extremely low defect density. Even local epitaxy phenomena have been identified at the AlN/Ti interface. The processing conditions used to synthesize AlN layers on Ti at room temperature are efficient in reducing the dislocation density and in-plane residual strain. Such AlN/Ti bilayers can be applied to manufacture novel electroacoustic device structures (such as bulk acoustic wave filters) on silicon substrates in further investigations.

Heavily Aluminum-Doped Epitaxial Layers for Ohmic Contact Formation to p-Type 4H-SiC Produced by Low-Temperature Homoepitaxial Growth

In this work, heavily aluminum (Al)-doped layers for ohmic contact formation to p-type SiC were produced by utilizing the high efficiency of Al incorporation during the epitaxial growth at low temperature, previously demonstrated by the authors’ group. The low-temperature halo-carbon epitaxial growth technique with in situ trimethylaluminum (TMA) doping was used. Nearly featureless epilayer morphology with an Al atomic concentration exceeding 3 × 1020 cm−3 was obtained after growth at 1300°C with a growth rate of 1.5 μm/h. Nickel transfer length method (TLM) contacts with a thin adhesion layer of titanium (Ti) were formed. Even prior to contact annealing, the as-deposited metal contacts were almost completely ohmic, with a specific contact resistance of 2 × 10−2 Ω cm2. The specific contact resistance was reduced to 6 × 10−5 Ω cm2 by employing a conventional rapid thermal anneal (RTA) at 750°C. Resistivity of the epitaxial layers better than 0.01 Ω cm was measured for an Al atomic concentration of 2.7 × 1020 cm−3.

Transient Behavior of Inclusion Chemistry, Shape, and Structure in Fe-Al-Ti-O Melts: Effect of Titanium/Aluminum Ratio

During ladle processing of interstitial-free (IF) steel melts, it is possible for transient titanium-containing oxides to be formed if the local titanium/aluminum (Ti/Al) ratio is locally and temporarily increased after aluminum killing. The phase stability diagrams suggest that if the Ti/Al ratio is increased, then Al2TiO5 and/or a liquid Al-Ti-O region can become stable, and eventually at even higher Ti/Al ratios, Ti3O5 becomes stable. In this study, the Ti/Al ratio was successively altered to investigate (1) how the inclusions evolved after titanium addition to aluminum-killed iron melts and (2) whether the inclusions present after sufficient time were those predicted by thermodynamics. When the Ti/Al ratio was maintained at 1/4, such that Al2O3 is the only thermodynamically stable oxide, the results show that transient titanium-containing oxides exist temporarily after titanium addition, but with time, the predominant inclusion was Al2O3, which would generate little shape change and produce transient stage inclusions with less titanium contents. When the Ti/Al ratio was increased to 1/1 (Al2O3 still being the only thermodynamically stable oxide), the results show a more distinct increase in the titanium content of the transient inclusions. The transient reaction was, in this case, accompanied by an irreversible shape change from spherical to irregular inclusions. When the Ti/Al ratio in the melt was increased to 15/1 within the Al2TiO5 stable phase region, the inclusion population evolved from spherical-dominant ones to irregular ones. It was found that the final inclusion chemistry has more titanium but less aluminum content compared with the expected from the Al2TiO5 chemistry. Besides, the transmission electron microscopy (TEM) results showed the existence of Ti2O. When the Ti/Al ratio in the melt was increased such that Ti3O5 is the thermodynamically stable inclusion (Ti/Al ratio of 75/1 or ∞), the inclusions evolved after titanium addition toward TiOx inclusions, which is accompanied by a shape change from spherical to irregular. The TEM results revealed and confirmed the existence of metastable Ti2O besides the thermodynamically stable Ti3O5, and it was consistent with the results based on oxidation studies of thin layers of titanium with Al2O3 substrate. It was discovered that Ti2O has the tendency of transforming into the thermodynamically stable phase Ti3O5 under certain conditions.

Role of titanium in Ti/Ni ohmic contact on n-type 6H-SiC

A set of Ti/Ni metallizations with different thickness of the underlying titanium layer was prepared on 6H-SiC together with structures that contained only pure Ti and Ni. Samples were gradually annealed at 750–1150 °C. Structures Ti(2)/Ni(50) and Ti(100)/Ni(50) showed the lowest contact resistivity, 2 × 10 −4 Ω cm 2 in both cases. For the Ti(2)/Ni(50) structure, low contact resistivity was reached most likely due to reduction of surface oxides on SiC by the thin titanium layer. In the Ti(100)/Ni(50) structure, the titanium layer prevents diffusion of nickel towards SiC and there is a layer containing mainly TiC at the interface with silicon carbide.

Enhanced mass sensitivity of ZnO nanorod-grown quartz crystal microbalances

ZnO nanorods were directly grown on the surface of a quartz crystal in zinc nitrate hexahydrate solution. The nanorod dimensions were controlled by varying the growth time, from 0.6 μm for a growth time of 1 h to 2.0 μm after 3 h of growth. After sequentially coating the nanorod-grown quartz crystals with thin layers of titanium and gold by thermal evaporation, the crystals were exposed to mercaptohexanol solution and the frequency change due to mercaptohexanol adsorption was determined. The frequency change for the nanorod-grown quartz crystal was about 60 times greater than that of the corresponding plain gold-coated quartz crystal due to the increase in surface area afforded by the nanorods. A similar enhancement of mass sensitivity was observed for the immobilization and hybridization of oligonucleotides on the nanorod-grown crystals. Although for larger molecules the enhancement of mass sensitivity was degraded by steric hindrance, the results demonstrate the potential of ZnO nanorod-grown quartz crystals for use in DNA-based biosensor applications.

Detailed Experimental and Theoretical Investigation of the Electron Transport in a Dye Solar Cell by Means of a Three-Electrode Configuration

Dye solar cells have been built in a three-electrode configuration where the nanoporous TiO2 layer has been contacted additionally on the rear side by means of a thin porous layer of metal titanium. With this third electrode, it was proved that under short-circuit conditions and an illumination intensity equivalent to “1 sun”, the differences of the electrochemical potential of the electrons between the two ends of the TiO2 layer reached values of more than 600 meV. The results confirm our former work carried out using an indirect method. As the third electrode could be used as a current collector as well, deeper insight in the transient behavior was achieved. A model has been developed to describe the transient electron transport through the TiO2 matrix, taking explicitly into account the numerous trap states of nanoporous anatase. The model turned out to be in good agreement with the experimental results.

Surface Improvement Technology “Wonder Process Craft (WPC)” by Rapid Impact of Fine Particle

Based on our sandblast and shot peening technology, we have found that utilizing relatively smaller powder for sandblasting enables the modification or the organizational and mechanical features of the ingredient's surface, defying the conventional thought in this subject manner. The technology mentioned previously can be utilized on various ingredients and machinery parts, and its effect is widely recognized. By blasting titanium particles onto the surface of metals, ceramics, or combined substances utilizing the previously mentioned technology, it is possible to attain a thin film layer of titanium deposit that is effective in catalyzing light. This is PIP (Powder Impact Plating) natural catalyst. In today's world where environmental destruction has become a serious issue, we hope to contribute to the improvement of the environment with our highly efficient catalyst.

Sol−Gel Tungsten Oxide/Titanium Oxide Multilayer Nanoheterostructured Thin Films: Structural and Photoelectrochemical Properties

Multilayer structures of alternating thin titanium and tungsten oxide layers having dimensions of ∼20 nm have been fabricated from titanium alkoxide and various tungstate precursor solutions using the dip coating technique. Single, double, and triple layer titanate and tungstate thin films were deposited on silicon substrates, and these films were initially annealed at 400 °C. Structural and microstructural aspects of the films were investigated using a variety of techniques, including X-ray reflectometry, grazing incidence X-ray absorption spectroscopy (GIXAS), cross-sectional transmission electron microscopy (TEM), and secondary ion mass spectrometry. The dimensions of the films and the character of the interfaces were principally gauged by cross-sectional TEM and X-ray reflectometery. All films were continuous on a local scale and had relatively low surface roughness. At the treatment temperature of 400 °C, only the tungsten oxide component showed appreciable crystallinity. The multilayer films had rel...

CFRP/titanium hybrid material for improving composite bolted joints

Abstract The structural joining remains an essential challenge for the development of composite aerospace structures: every structural interconnection means a disturbance of an optimized structure resulting in an increase in overall structural weight. The lightweight potential of advanced, high-performance fiber composite materials is affected more strongly by mechanical fastening techniques than by conventional metallic materials due to the low shear and bearing capabilities of CFRP materials. Local embedding of thin titanium layers into the composite laminate in the coupling region results in a considerable improvement in structural efficiency of bolted and riveted joints in CFRP structures. This improvement is not only obvious in the increase in shear and bearing capabilities, but also in the resulting possibilities for a design no longer burdenend by local material thickening, excentricities and additionally excited local bending stresses. This report displays experimental results demonstrating the advantageous influence of titanium hybridization on specific characteristics of CFRP-materials, thus proving the mechanical potential of CFRP/titanium hybrid materials when used as an advanced reinforcement technique for highly loaded composite joints.

A physical vapor deposition method for controlled evaluation of biological response to biomaterial chemistry and topography

The purpose of this study was to characterize a technique to effectively mask surface chemistry without modifying surface topography. A thin layer of titanium was deposited by physical vapor deposition (PVD) onto different biomaterial surfaces. Commercially pure titanium disks were equally divided into three groups. Disks were either polished to a mirror finish, grit blasted with alumina particles, or grit blasted and subsequently plasma sprayed with a commercial grade of hydroxyapatite (HA). A subgroup of each of these treatment types was further treated by masking the entire disk surface with a thin layer of commercially pure titanium deposited by PVD. A comparison of surface topography and chemical composition was carried out between disks within each treatment group. Canine marrow cells were seeded on all disk surfaces to determine the stability of the PVD Ti mask under culture conditions. The PVD process did not significantly alter the surface topography of any samples. The thin titanium layer completely masked the underlying chemistry of the plasma sprayed HA surface and the chemistry of the plasma vapor deposited titanium layer did not differ from that of the commercially pure titanium disks. Aliquots obtained from the media during culture did not indicate any significant differences in Ti concentration amongst the Ti and Ti-masked surfaces. The PVD application of a Ti layer on HA coatings formed a stable, durable, and homogenous layer that effectively masked the underlying surface chemistry without altering the surface topography.