Synopsis of the thesis entitled “Titanium Nitride-Based Electrode Materials for Oxidation of Small Molecules: Applications in Electrochemical Energy Systems” submitted by Muhammed Musthafa O. T under the supervision of Prof. S. Sampath at the Department of Inorganic and Physical Chemistry of the Indian Institute of Science for the Ph.D degree in the faculty of science. Fuel cells have been the focus of interest for many decades because of the ever increasing demands in energy. Towards this direction, there have been considerable efforts to find efficient electrocatalysts to oxidize small organic molecules (SOMs) such as methanol, ethanol, glycerol, hydrazine and borohydride that are of potential interest in direct fuel cells. Most studies revolve around platinum which is the best electrocatalyst known for the oxidation of many SOMs. However, platinum is extremely susceptible to carbon monoxide (CO) poisoning which is an intermediate in the electrooxidation of aliphatic alcohols. The best known catalyst, platinum-ruthenium alloy (PtRu), suffers from leaching of Ru during cycling resulting in decrease in efficiency in addition to loss of precious metal. Another important aspect of fuel cell catalyst degradation is corrosion of widely-used carbon support, under fuel cell conditions. Corrosion of carbon support weakens the adherence of catalyst particles on the support and in turn results in loss of catalyst and also in its easy oxidation. Carbon corrosion is also reported to decrease the electronic continuity of the catalyst layer. Hence, replacement of carbon support with durable material is required. The present research explores the use of non-carbonaceous, transition metal nitride for anchoring catalytic particles. The favorable physicochemical properties of titanium nitride (TiN) such as extreme hardness, excellent corrosion resistance in aggressive electrolytes, resistance to nearly all chemicals, salt and humidity, very good support for the adherence of fuel cell catalysts and excellent electronic conductivity motivated us to use this material for anchoring fuel cell catalysts such as Pt, PtRu and Pd. In the present studies, TiN coated on stainless steel (SS 304) surface is used as an electrode material. Catalysts such as Pt, Pd and PtRu are anchored on to TiN and used for the oxidation of methanol and ethanol in acidic as well as in alkaline media. Use of bare TiN is explored for the oxidation of sodium borohydride. The efficiency of TiN supported catalysts are compared with carbon supported ones. Preliminary studies on the use of TiN supported catalysts in fuel cells have been conducted as well. Figure 1 shows the topographic atomic force microscopic (AFM) image in combination with scanning Kelvin probe (SKP) image of platinized TiN (Pt-TiN) surface. Since Pt particles are metallic, they are expected to show lower work function values than that of TiN domains which is indeed observed in figure 1B where the location of Pt particles is shown as dip in the work function. Very interestingly, the interface of Pt-TiN possesses very different work function values confirming the existence of metal-support interaction and this is expected to have positive implications in fuel cell catalysis. Figure 1. Contact mode AFM (A) and the corresponding scanning Kelvin probe image (B) of Pt-TiN surface. Figure 2. Cyclic voltammograms of Pt-TiN and Pt-C electrodes in 0.5 M H2SO4 containing 0.5 M methanol at a scan rate of 10 mV/s. Loading of the catalyst used is 1 mg of Pt/cm2. The performance of Pt-TiN and PtRu-TiN are compared with the corresponding carbon supported catalysts (Pt-C, PtRu-C) for the electrooxidation of methanol. Figure 2 shows the voltammograms obtained on Pt-TiN and Pt-C in presence of acidified methanol. TiN supported catalyst performs better than carbon supported catalyst in terms of high currents at low over voltages (based on I-t measurements), long term stability and high exchange current densities (based on Tafel studies). The electrochemical characteristics of methanol oxidation on Pt-TiN and Pt-C catalysts are given in table 1. The current densities observed on TiN supported catalyst are almost three times higher than that of carbon supported catalyst confirming the promoting effect of TiN support towards methanol oxidation reaction. The performance of Pt-TiN electrocatalyst under fuel cell conditions reveals peak power densities close to 396 mW/cm2 at a current density of 375 mA/cm2, at 90C. Table 1. Characteristics of methanol oxidation on TiN and carbon supported catalysts in acidic medium. Material Onset Ep (mV) Ip EAA Ip Ip/Ib E=Ep-Eb potential (mA/mg (cm2/mg)b (mA/cm2 (mV) of Pt)a of Pt)c (mV) Pt-TiN 170 720 56 78.4 0.714 1.24 82 Pt-C 250 700 18 68.6 0.262 0.98 106 a Mass activity; Ip is the forward peak current and Ib is the reverse peak current; Ep and Eb are forward and reverse peak potentials. b Electrochemically active area (EAA) c Current density normalized for EAA Figure 3. In-situ FTIR spectra on bare TiN surface as a function of applied DC bias vs.SCE. The spectra are shown in regions of 1000 to 2000 cm-1 (A) and 2500 to 4000 cm-1 (B). Electrolyte used is 0.5 M methanol in 0.5 M H2SO4. Reference spectrum is obtained at 0 V. In-situ FTIR spectroelectrochemical measurements have been carried out to understand the intermediates and products formed during methanol oxidation. TiN surface is highly reflective and is quite amenable for reflectance IR studies. Figure 3 shows the potential dependant spectral characteristics of TiN in methanolic sulphuric acid. The bands observed at 1600 and 3600 cm-1 correspond to –OH bending and stretching vibrations of adsorbed water molecules. Interestingly, bands corresponding to adsorbed water are observed even at remarkably low over potentials of around 0.1 V vs. SCE where CO poisoning of Pt can be very severe. This experiment confirms the ability of inexpensive TiN to function like expensive Ru in fuel cell catalysis. Similar studies have been carried out for ethanol electrooxidation on TiN supported catalysts such as Pd, Pt and PtRu in acidic as well as alkaline conditions. Adherence of fuel cell catalyst on to TiN and carbon support is followed by cycling the electrode potential continuously as shown in figure 4. The adherence of Pd on TiN surface is very good and the stability tests reveal that Pd adheres and remains on TiN for a long time as compared to carbon support. Figure 4. Cyclic voltammograms of Pd-C (A) and Pd-TiN (B) in 1 M KOH at 100 mV/s. Pd loading used is 83 µg/cm2. In the chapter on borohydride oxidation, bare TiN electrode is used for the electrochemical oxidation of sodium borohydride. In direct borohydride fuel cells (DBFC), H2 evolution that occurs at low over voltages decreases the apparent number of electrons transferred and consequently the fuel cell efficiency. TiN has been shown to be a relatively H2 evolution-free electrocatalyst for borohydride oxidation (figure 5A). As shown in figure 5A, no H2 oxidation is observed (below -0.5 V) on TiN surface with increase in concentration of borohydride. This point to the fact that direct oxidation of borohydride is very favourable on TiN electrode and is confirmed by fuel cell measurements as shown in figure 5B. Non-platinum DBFCs using TiN as the anode (borohydride oxidation) and prussian blue supported carbon (PB-C) as the cathode (oxygen or hydrogen peroxide) electrocatalysts (figure 5B) reveal peak power density of 107 mW/cm2 for a current density 130 mA/cm2, at 80C. Figure 5. Cyclic voltammograms of TiN in 1 M NaOH containing varying concentrations of borohydride at a scan rate of 20 mV/s (A). Polarization studies of DBFC with TiN anode catalyst and PB-C (prussian blue supported on carbon) cathode catalyst (B). Anolyte is 0.79 M borohydride in 5 M NaOH and catholyte is 2.2 M acidified H2O2. The second aspect of the thesis is related to the use of TiN to prepare visible light active, nitrogen doped TiO2 (N-TiO2). This is carried out by electrochemical anodization of TiN in 0.5 M HNO3 at 1.4 V. The X-ray photoelectron spectroscopy (XPS) suggests the formation of oxide phase on anodized TiN surface (figure 6A) and is confirmed by reflectance UV-Visible spectroscopy. The visible light activity is used for the sunlight induced reduction of graphene oxide to reduced graphene oxide. As shown in the Raman spectra (figure 6B), a negative shift of the D and G band positions by about 20 cm-1 and the intensity ratio reversal after reduction confirms the formation of reduced graphene oxide on N-TiO2. Figure 6. (A) Ti (2p) region of XPS of fresh TiN and anodized TiN. Anodization has been carried out at 1.4 V vs. SCE in 0.5 M HNO3. (B) Raman spectra of exfoliated graphene oxide on anodized TiN before and after sunlight induced reduction. In summary, TiN has been shown to be an active support material for fuel cell catalysts in the present studies. The appendix details the basic electrochemical studies on TiN using various redox couples, electroploymerization of aniline and the formation of nanostructures on TiN surface. (For figures pl refer the abstract pdf file)

Non-metallic inclusions in steels are generally considered to be detrimental for mechanical properties. However, it has been recognized that certain inclusions, such as Ti-oxide and TiN, can serve as potent nucleation sites for the formation of intragranular ferrite (IGF) in low-alloy steels. The formation of IGF could improve the toughness of the coarse grained heat affected zone (CGHAZ) of weld metals. Thus, the present thesis mainly focuses on the effect of size of nucleation sites on the IGF formation. Quantitative studies on the composition, size distribution and nucleation probability for each size of the inclusions as well as the area fraction, starting temperature and morphology of an IGF have been carried out. In the present work, the Ti-oxide and TiN powders were mixed with metallic powders. The mixed powders were heated up to the liquid state and cooled with a slow cooling rate of 3.6 ºC/min. These as-cast steels with Ti-oxide and TiN additions were used to simulate the IGF formation in the CGHAZ of weld metals. Specifically, the inclusion and microstructure characteristics in as-cast steels have been investigated. The results show that the nucleant inclusion was identified as a TiOx+MnS phase in steels with Ti2O3 additions and as a TiN+Mn-Al-Si-Ti-O+MnS phase in steels with TiN additions. In addition, the TiOx and TiN phases are detected to be the effective nucleation sites for IGF formation. It is clearly shown that an increased inclusion size leads to an increased probability of IGF nucleation. This probability of IGF nucleation for each inclusion size of the TiOx+MnS inclusions is clearly higher than that of the complex TiN+Mn-Al-Si-Ti-O+MnS inclusions. In addition, the area fraction of IGF in the steels with Ti2O3 additions is larger than that of the steels with TiN additions. This result agrees with the predicted tendency of the probability of IGF nucleation for each inclusion size in the steels with Ti2O3 and TiN additions. In order to predict the effective inclusion size for IGF formation, the critical diameters of the TiO, TiN and VN inclusions, which acted as the nucleation sites of IGF formation, were also calculated based on the classical nucleation theory. The critical diameters of TiO, TiN and VN inclusions for IGF formation were found to be 0.192, 0.355 and 0.810 μm in the present steels. The calculation results were found to be in agreement with the experiment data of an effective inclusion size. Moreover, the effects of the S, Mn and C contents on the critical diameters of inclusions were also calculated. It was found that the critical diameter of the TiO, TiN and VN inclusions increases with an increased content of Mn or C. However, the S content doesn’t have a direct effect on the critical diameter of the inclusions for IGF formation. The probability of IGF nucleation for each inclusion size slightly decreases in the steel containing a higher S content. This fact is due to that an increased amount of MnS precipitation covers the nucleant inclusion surface. In the as-cast experiment, it was noted that an IGF can be formed in steels with Ti2O3 and TiN additions with a cooling rate of 3.6 ºC/min. In order to control the microstructure characteristics, such as the area fraction and the morphology of an IGF, and to investigate the starting temperature of IGF and grain boundary ferrite (GBF) formation, the dynamic transformation behavior of IGF and GBF was studied in-situ by a high temperature confocal laser scanning microscope (CLSM). Furthermore, the chemical compositions of the inclusions and the morphology of IGF after the in-situ observations were investigated by using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and electron probe microanalysis (EPMA) which equipped wavelength dispersive spectrometer (WDS). The results show that the area fraction of IGF is larger in the steels with Ti2O3 additions compared to the steels with TiN additions, after the same thermal cycle has been imposed. This is due to that the TiOx phase provides more potent nucleation sites for IGF than the TiN phase does. Also, the area fraction of IGF in the steels is highest after at an intermediate cooling rate of 70 ºC/min, since the competing phase transformations are avoided. This fact has been detected by using a hybrid methodology in combination with CLSM and differential scanning calorimetry (DSC). In addition, it is noted that the morphology of an IGF is refined with an increased cooling rate. / <p>QC 20150325</p>

Made available in DSpace on 2016-12-08T15:56:18Z (GMT). No. of bitstreams: 1 Luiz Antonio Alves.pdf: 4887074 bytes, checksum: 2921556dad24ae9311fe651e5a0ccdcf (MD5) Previous issue date: 2014-07-14 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Titanium nitride (TiN) films with niobium (Nb) addition (TiN[Nb], 0,01 < Nb/Ti < 0,15) were obtained by sputter deposition in a triode magnetron sputtering system from a mosaic target of titanium with niobium inserts at the erosion zone. The effects of Nb/Ti in surface morphology were analyzed by atomic force and confocal microscopy measurements. The reflectivities of the films with niobium incorporation are in agreement with the Drude-Lorentz model. The constants obtained by the fitting show an increase in plasma frequency and relaxation time with increased Nb/Ti ratio, indicating an increase in the number of charge carriers. The color parameters according CIELab system show an increase in L*, a* and b* coordinates. The visual analysis indicates an increased red tone when compared with pure TiN film in agreement with the increased absolute values of a* coordinates. / Filmes de nitreto de titânio com adição de nióbio ((TiN[Nb], 0,01 < Nb/Ti < 0,15) foram depositados pelo processo de pulverização catódica utilizando um sistema Triodo Magnetron Sputtering. A pulverização catódica de Titânio e Nióbio foi feita a partir de um alvo de titânio com insertos de nióbio dispostos na região de erosão. Foram analisados os efeitos da razão Nb/Ti na morfologia superficial do filme através de microscopia de força atômica e confocal. As medidas de refletividade dos filmes de TiN[Nb] obedecem perfeitamente o modelo de Drude-Lorentz. As constantes obtidas pelo modelo de Drude-Lorentz mostram um aumento nos valores da frequência de plasma e tempo de relaxação com o aumento na razão Nb/Ti, indicando que a presença de nióbio aumenta o número de portadores de carga. Os parâmetros de cor segundo o sistema CIELab mostram um aumento nas coordenadas L*, a* e b*. A análise visual das amostras mostra uma tonalidade avermelhada, quando comparadas com o filme contendo somente TiN, em concordância com o aumento absoluto nas coordenadas a*.

O presente trabalho apresenta um estudo do tratamento duplex para o biomaterial Nitinol (NiTi). Este tratamento consiste em nitretação a plasma para a formação do nitreto de titânio (TiN), seguido de deposição de um filme fino de nitreto de zircônio (ZrN) sobre a superfície nitretada. O estudo das fases cristalinas presentes no sistema foi realizado pela técnica de difração de raios X (DRX). A morfologia e espessura da camada nitretada e do filme fino depositado foram avaliadas por microscopia eletrônica de varredura (MEV). As propriedades mecânicas foram estudadas mediante ensaios de nanoindentação. Para avaliar a resistência à corrosão foram realizados testes de polarização potenciodinâmica em solução de saliva artificial. Os resultados mostram que a temperatura de nitretação tem forte influência na formação do TiN na superfície do substrato. O filme de ZrN depositado sobre as amostras nitretadas apresenta propriedades de dureza e resistência à corrosão que dependem da temperatura de nitretação, mesmo tendo sido depositados sem variação de temperatura. Esse comportamento sugere que os filmes são influenciados pela condição inicial da superfície antes da deposição. Os melhores resultados em termos de dureza e resistência à corrosão foram obtidos nas amostras tratadas em temperaturas mais elevadas. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-06-05T18:07:33Z No. of bitstreams: 1 Dissertacao Juliane Carla Bernardi.pdf: 2940702 bytes, checksum: 376b73745f740260fc19e7a6e8b5d900 (MD5) / Made available in DSpace on 2014-06-05T18:07:33Z (GMT). No. of bitstreams: 1 Dissertacao Juliane Carla Bernardi.pdf: 2940702 bytes, checksum: 376b73745f740260fc19e7a6e8b5d900 (MD5) / The present work aims to study about duplex treatment on the biomaterial Nitinol (NiTi). This treatment consists in titanium nitride (TiN) formed by plasma nitration, followed by zirconium nitride (ZrN) thin film deposition upon the nitrated surface. The study of crystalline phases present in the system was performed by X-ray diffraction technique (XRD). The morphology and thickness of the nitrated layer and thin film were evaluated by scanning electron microscopy (SEM). The mechanical properties were studied by nanoindentation analysis. In order to evaluate corrosive resistance tests of potenciodynamic polarization were performed in solution of saliva artificial. Results demonstrate that nitration temperature has a strong influence in the formation TiN on the substrate surface. The ZrN film depositated upon nitrated samples present hardness and corrosive resistance properties that depend on nitration temperature, even though ZrN films were depositated without temperature variation. This behaviour suggests that films are influenced by the initial surface condition before depositon. The best results in terms of hardness and corrosive resistance were obtained in samples treated at higher temperatures.

The functional and mechanical properties of a material are often determined by the defects in them. A thorough understanding of the relationship between the defects and the properties allows for tailoring a material’s properties into the desired combinations. Amongst the different classes of defects, experimental identification of point defects is typically difficult and indirect, usually requiring an ingenious combination of different techniques. In this context, first-principles calculations, complemented with experiments, offer insights into the formation of defects and their role in properties. This was demonstrated in this thesis through investigations on the effect of calcium vacancies on structure, vibrational and elastic properties hydroxyapatite (HAp), and oxygen vacancies on elastic properties of zinc oxide (ZnO) using first-principles calculations based on density functional theory (DFT). Our results confirm a considerable reduction in the elastic constants of HAp—the inorganic constituent of bone—due to Ca-deficiency, which was experimentally reported earlier. Elastic anisotropic behavior of stoichiometric and Ca-deficient HAp is analyzed, which will be useful in understanding the effects of crystal orientation in designing synthetic bone. Local structural stability of HAp and Ca-deficient HAp structures is assessed with full phonon dispersion studies and the specific signatures in the computed vibrational spectra for Ca deficiency in HAp can be utilized in experimental characterization of different types of defected HAp. In ZnO, formation energies of oxygen vacancies in different types of oxygen deficient structures are analyzed to ascertain their stability. Our results show considerable degradation of some of the elastic moduli due to the presence of such vacancies. Further, the charge state of the defect structure is found to influence the shear elastic constants. Evaluation of elastic anisotropy of stoichiometric and oxygen deficient ZnO indicates the significant anisotropy in elastic properties and stiff c-axis orientation. The second part of the thesis deals with developing some understanding of the pressure-induced phase transformations (PIPT) in an inorganic material, titanium nitride (TiN), and in a metal-organic framework (MOF), erbium formate crystal. PIPT, which is a common phenomenon in many materials, is of great interest in materials science as the properties of the transformation product can diverge significantly from those of the parent phase. Hence, it is important to understand the pressure induced changes so to improve the component reliability and to enhance service life of materials used in high pressure applications. TiN undergoes PIPT from NaCl to CsCl structure. On the basis of our DFT calculations, we propose a new transformation path, which shows that the stress required for this transformation is substantially lower when it is deviatoric in nature than that under hydrostatic pressure. Local stability of the structure is assessed with phonon dispersion determined at different pressures, and we find that CsCl structure of TiN is expected to distort after the transformation. Further, we provide a quantitative comparison of electronic structure of TiN in NaCl structure with that of high pressure phase with implication to electrical conduction properties. Next, we investigate the PIPT associated with bond rearrangement in erbium formate framework. Phase transition pressure is estimated and the corresponding changes in bonding characteristics are analyzed. Estimated lattice constants for both the phases agree well with the earlier experimental results. While the transformation pressure of the framework is overestimated with respect to experiment, our calculations confirm PIPT, and thus provide a theoretical evidence for the experimental finding.

Ce travail se place dans le cadre des réacteurs nucléaires de 4ème génération tels que les réacteurs à neutrons rapides et caloporteur gaz (RNR-G), pour lesquels des matériaux réfractaires comme le nitrure de titane (TiN) enroberont le combustible afin de permettre la rétention des produits de fission. Cette étude a porté sur le comportement thermique intragranulaire du xénon dans des échantillons de TiN obtenus par frittage à chaud sous charge. Le rôle de la microstructure sur le comportement thermique du xénon a été étudié. Plusieurs lots ont ainsi été synthétisés sous différentes conditions de température et de composition de la poudre initiale. Le xénon a été introduit par implantation ionique. Les échantillons ont ensuite subi des traitements thermiques entre 1300°C et 1600°C, soient les températures accidentelles envisagées. Un transport majoritaire du xénon vers la surface a été mis en évidence. Ce dernier est ralenti lorsque la température de frittage augmente. Des différences de comportement ont été observées selon les poudres mises en oeuvre dans la synthèse et selon l'orientation cristalline du grain considéré. Le relâchement du xénon a également été corrélé à l’oxydation de TiN. Des bulles de Xe dès 0,38 % atomique ont été observées. Leur taille est proportionnelle à la concentration en Xe et augmente avec la température de recuit, d’où une certaine mobilité du Xe au sein de TiN. Plusieurs mécanismes pouvant expliquer cette mobilité sont proposés. En complément, des calculs ab initio ont confirmé le caractère fortement insoluble du Xe dans TiN et révélé que les bilacunes sont les plus favorables à l'incorporation du xénon au sein de ce matériau. / This work concerns the generation IV future nuclear reactors such as gas-cooled fast reactor (GFR) for which refractory materials as titanium nitride (TiN) are needed to surround fuel and act as a fission product diffusion barrier. This study is about Xe thermal behavior in sintered titanium nitride. Microstructure effects on Xe behavior have been studied. In this purpose, several syntheses have been performed using differents sintering temperatures and initial powder compositions. Xenon species have been introduced into samples by ionic implantation. Then, samples were annealed in temperature range from 1300°C to 1600°C, these temperatures being the accidental awaited temperature. A transport of xenon towards sample surface has been observed. Transport rate seems to be slow down when increasing sintering temperature. The composition of initial powder and the crystallographic orientation of each considered grain also influence xenon thermal behavior. Xenon release has been correlated with material oxidation during annealing. Xenon bubbles were observed. Their size is proportional with xenon concentration and increases with annealing temperature. Several mechanisms which could explain Xe intragranular mobility in TiN are proposed. In addition with experiments, very low Xe solubility in TiN has been confirmed by ab initio calculations. So, bivacancies were found to be the most favoured Xe incorporation sites in this material.

Les travaux dans cette thèse ont pour objectif la synthèse de catalyseurs (nanoparticules de cuivre) de taille contrôlée pour la synthèse de nanofils de silicium dans des conditions compatibles CMOS, c'est-à-dire en évitant l'utilisation de l'or comme catalyseur et pour des croissances basse température (<450°C). Les résultats obtenus ont permis de montrer que les techniques de chimie de surface classiquement utilisées pour la préparation de catalyseurs sur des supports 3D (silice, nitrure de titane…) sont directement applicables et transférables sur des supports 2D (wafer de silicium recouvert de films fins de SiO2, SiOx et TiN). Nous avons par exemple pu préparer des nanoparticules de cuivre de taille contrôlée (de 3 nm à 40 nm de diamètre moyen suivant les conditions expérimentales et supports). De plus, les mécanismes de formation des nanoparticules en fonction des propriétés de surface des matériaux étudiés ont été démontrés en combinant diverses techniques d'analyses de surface. La croissance de nanofils de silicium à partir de ces catalyseurs sur substrats 2D a également été réalisée avec succès dans des procédés à basse température. Il a notamment été montré l'existence d'un diamètre minimum critique à partir de laquelle la croissance basse température était possible / The work presented in this PhD thesis aimed at the preparation of copper nanoparticles of controllable size and their utilization as catalysts for the growth of silicon nanowires in a process compatible with standard CMOS technology and at low temperature (< 450°C). The growth of silicon nanowires by Chemical Vapor Deposition (CVD) via the catalytic decomposition of a silicon precursor on metallic nanoparticles at low temperature (Vapor Solid-Solid process) was demonstrated to be possible from an oxidized Cu thin film. However, this process does not allow the control over nanowires diameter, which is controlled by the diameter of the nanoparticle of catalyst. In this PhD is presented a fully bottom-up approach to prepare copper nanoparticles of controllable size directly on a surface without the help of external stabilizer by mean of surface organometallic chemistry. First, the preparation of copper nanoparticles is demonstrated on 3D substrates (silica and titanium nitride nanoparticles), along with the fine comprehension of the formation mechanism of the nanoparticles as a function of the surface properties. Then, this methodology is transferred to planar (2D) substrates typically used in microelectronics (silicon wafers). Surface structure is demonstrated to direct the Cu nanoparticles diameter between 3 to 40 nm. The similarities between the 2D and 3D substrates are discussed. Finally, the activity of the Copper nanoparticles in the growth of Silicon nanowire is presented and it is demonstrated that in our conditions a critical diameter may exist above which the growth occurs

O presente trabalho apresenta um estudo do tratamento duplex para o biomaterial Nitinol (NiTi). Este tratamento consiste em nitretação a plasma para a formação do nitreto de titânio (TiN), seguido de deposição de um filme fino de nitreto de zircônio (ZrN) sobre a superfície nitretada. O estudo das fases cristalinas presentes no sistema foi realizado pela técnica de difração de raios X (DRX). A morfologia e espessura da camada nitretada e do filme fino depositado foram avaliadas por microscopia eletrônica de varredura (MEV). As propriedades mecânicas foram estudadas mediante ensaios de nanoindentação. Para avaliar a resistência à corrosão foram realizados testes de polarização potenciodinâmica em solução de saliva artificial. Os resultados mostram que a temperatura de nitretação tem forte influência na formação do TiN na superfície do substrato. O filme de ZrN depositado sobre as amostras nitretadas apresenta propriedades de dureza e resistência à corrosão que dependem da temperatura de nitretação, mesmo tendo sido depositados sem variação de temperatura. Esse comportamento sugere que os filmes são influenciados pela condição inicial da superfície antes da deposição. Os melhores resultados em termos de dureza e resistência à corrosão foram obtidos nas amostras tratadas em temperaturas mais elevadas. / The present work aims to study about duplex treatment on the biomaterial Nitinol (NiTi). This treatment consists in titanium nitride (TiN) formed by plasma nitration, followed by zirconium nitride (ZrN) thin film deposition upon the nitrated surface. The study of crystalline phases present in the system was performed by X-ray diffraction technique (XRD). The morphology and thickness of the nitrated layer and thin film were evaluated by scanning electron microscopy (SEM). The mechanical properties were studied by nanoindentation analysis. In order to evaluate corrosive resistance tests of potenciodynamic polarization were performed in solution of saliva artificial. Results demonstrate that nitration temperature has a strong influence in the formation TiN on the substrate surface. The ZrN film depositated upon nitrated samples present hardness and corrosive resistance properties that depend on nitration temperature, even though ZrN films were depositated without temperature variation. This behaviour suggests that films are influenced by the initial surface condition before depositon. The best results in terms of hardness and corrosive resistance were obtained in samples treated at higher temperatures.

This diploma thesis deals with measuring touches problems in industrial metrology. Thesis describes adhesive wear and tear which is caused by measuring probes when dynamical measuring is being concluded. Measuring of damaged component made of silumin and its different changes of texture by different measuring probes are evaluated. Measuring touches are made of titanium nitride, silicon nitride, zirconium, bearing chrome steel, ruby, experimental composite material and nanocrystalline diamond.

Объект изучения – модуль плазмохимического травления и осаждения на базе нанотехнологического комплекса Нанофаб-100. Цель работы — плазмохимический синтез тонких покрытий на основе нитридов алюминия и титана. Методы исследования: плазмостимулированное химическое осаждение из газовой фазы, электрохимическое окисление, плазменное азотирование, сканирующая электронная и атомно-силовая микроскопия, оптическая спектроскопия, наноиндентирование. В результате исследования разработана методика синтеза нитрида алюминия на установке плазмохимического синтеза. Синтезированы тонкие пленки нитрида алюминия толщиной 50-200 нм. Продемонстрирована возможность получения наноточек нитрида алюминия. С помощью плазмохимического азотирования модифицирована поверхность металлического титана с увеличением твердости в 4 раза. Показана возможность получения нанотубулярных структур нитрида титана, являющихся перспективными в целях создания электронных устройств, фотокаталитических ячеек и др. Результаты работы отражены в тезисах докладов III Международной молодежной научной конференции «Физика. Технологии. Инновации. ФТИ-2016». / The object of this study is the module of plasma chemical etching and deposition based on nanotechnology complex Nanofab-100. The goal of the current paper is the plasma-chemical synthesis of thin coatings based on aluminum and titanium nitrides. As a result of the research, a technological map for the routine of the plasma-chemical synthesis and a technique for obtaining nanomaterials on the example of aluminum nitride have been developed. There were synthesized thin films of aluminum nitride with 50-200 nm thickness. The possibility of synthesis nano-dots of AlN is demonstrated. The surface of metallic titanium has been modified with an increase in hardness by 4 times using plasma-assisted nitriding process. The possibility of obtaining nanotubular structures of titanium nitride, which are promising for microelectronic and photocatalysis, is shown. The results of the work are reported in abstracts of the III International Youth Scientific Conference «Physics. Technologies. Innovation. FTI-2016».