Abstract In this work, the electrochemical anodization process was carried out on titanium grade 2, using an electrolytic solution of 3 M and 0.15 M HCl with voltages of 11 V, 12 V and 15 V, as well as time variations in the experimental process and later an annealing process at 750 °C. According to the results obtained, the TiO2 coatings presented different morphologies on their surface, which consisted of nanopores, nanowires and clusters of oxide grains, as well as a combination of anatase and rutile crystalline phases. Band Gap variations were found to be non-significant despite changes in the morphology of the coatings at different anodization conditions, with an average value of 2.91 eV. It was observed that the anodized samples treated by the annealing process at 750 °C, thickness values up to 16 μm were obtained.

Abstract TiO2 nanotubes were prepared by the anodization process of a set of titanium foils in order to study the influence of time and voltage on the morphology of them under a 1.2 wt % NH4F salt concentration, taking advantage of this percent and remarking the great importance of the oxide growth-dissolution speed with this electrolyte concentration. The anodization process consists of an organic media of ethylene glycol, a voltage from 5 to 30 V for a time period from 1 to 6 hours, a constant potential of 30 V for a time lapse from 10 to 360 minutes and 5 to 480 seconds. All anodized samples are rinsed and annealed to 400 ° C for 3 hours to obtain an anatase crystalline structure. The morphological characterization was carried out by Field Emission Scanning Electron Microscopy (FESEM) to verify the presence of the main nanostructures: nanopores, nanotubes, and nanograss. Raman spectroscopy was used for optical characterization in order to identify the changes in the signal of the E g (v6) vibrational mode. It was observed the Raman E g (v6) vibrational mode suffers a redshift at the initial anodization stage with the contribution of the stress between the substrate-oxide layer and the stoichiometry defects. The diameter and tube length have a strong correlation with the oxide thickness (ascendant slope), moreover, this oxide is compared and related to the Raman intensity of the E g (v6) mode, from this fact, it is easy to define some time periods and a voltage range for each titania nanostructures observed.

Abstract Many studies, focused in TiO2 anodized, uses frequently a NH4F salt concentration from 0.3- 0.5 wt% and the whole information about how voltage, time and even pH affects to nanotubes morphology, are effective just for these concentration range. It is known that increasing salt concentration, the electrolyte increases their conductivity and anodization speed (oxidation-dissolution) suffers also an increment and for a specifically concentration 1.2wt%, there is no data about morphology repercussions. A TiO2 nanotubular matrix is synthesized, in order to identify the range of time where it is possible to obtain with no presence of nanograss. The anodization process consists of an organic electrolyte of ethylene glycol, deionized water and 1.2 wt% NH4F salts, constant potential of 30 V, and a time lapse from 10 to 60 minutes (short time). All anodized samples are rinsed and annealed to 400oC for 4 hours to obtain an anatase crystalline structure; no samples are cleaned in ultrasonic bath to preserve the nanograss structure. Optical characterization was performed by Raman Spectroscopy to identify the increases in signal intensity, associated with thickness. The morphological characterization was carried out by Scanning Electron Microscopy to verify the presence and density of the nanograss and nanotubes.

The performance characteristics of a compliant mechanical displacement amplification mechanism, as well as the geometrical gain in forced regime, the geometrical gain in resonance and the resonance frequency are obtained by using optical interferometry and compared with values obtained using the finite element analysis software ANSYS. The operation principle and the limits of the compliant mechanism are described by numerical simulations in ANSYS. The similarity between the experimental results and numerical simulations show that the used methodology is adequate to describe its design and its mechanical performance.

Las características de desempeño de un mecanismo para amplificar desplazamientos mecánicos, como la ganancia geométrica en régimen forzado, la ganancia geométrica en resonancia y la frecuencia de resonancia, son obtenidas mediante interferometría óptica y comparados con los valores obtenidos mediante elemento finito en ANSyS. Se describe el principio de operación del mecanismo y mediante simulaciones numéricas en ANSyS, se obtienen los rangos de operación del mismo. La similitud entre los resultados experimentales y las simulaciones numéricas muestran que la metodología seguida es adecuada.

Using the reactive magnetron rf co-sputtering technique and a Ti target partially covered with a small Al plate, TiAlN coatings were made on c-Si in a reactive atmosphere of nitrogen and argon. Coatings were deposited on substrates at 22°C and at 150°C. The substrate temperature notably affected the thickness, crystalline grain size, and hardness of the coatings. We analyzed the dependence of both structure and crystalline grain sizes on substrate temperature and the chemical composition of the coatings. The structural properties and the chemical composition were obtained by means of XRD and EDS techniques. High aluminum content was found in the coatings for the samples grown at the lower substrate temperature when samples were measured by electron dispersive spectroscopy technique. Atomic force microscopy measurements showed a surface morphology dependent on the nitrogen content. Scanning electron microscopy measurements showed a clear pyramidal microstructure of TiAlN coatings grown at 22°C, while the microstructure of those grown at a substrate temperature of 150°C were not well defined.