Nanostructured materials have potential technological applications due to their characteristic dimensions. The material performance will depend on the atomic structure, and composition of these materials. This thesis focuses on proposing a reliable method for fabricating nanoporous alumina and palladium nanoparticles inside the templates.Palladium nanoparticles were synthesized in commercial porous alumina templates using electrodeposition. Pores within these nanoporous membranes act as templates for the synthesis of nanostructures of the desired material. Electrodeposition is achieved using a three-terminal set-up and a potentiostat. Different types of deposition techniques were investigated to improve the distribution of the deposit. The nanoparticles were characterized by SEM/EDX for composition. The commercial templates have high aspect ratio, but are not hexagonally ordered. Hence porous alumina was fabricated in the laboratory by anodization of aluminum.

No description available.

In this research work, porous films on aluminum foil, with vertical through and through pores, were fabricated. The films were anodized at different applied voltages and the conditions were reported. In some cases, aluminum foil films were anodized under constant current conditions. Thicker aluminum films, referred to as aluminum tape in this thesis, were also anodized to get good porous films. While the porous alumina films using aluminum tape produced pores with good uniformity, the films did not produce through and through pores. Porous alumina films were also prepared on aluminum evaporated ITO substrate. The films on ITO substrate were different from the porous alumina films using aluminum foil/tape. In case of ITO substrate based films, an additional condition, temperature was also varied. The anodization process on ITO substrate based films was done at lower temperatures in order to reduce the effect of high currents on the process. The SEM images for different anodization conditions were compared and the porosity of films was calculated. CdS was electrodeposited inside porous alumina. D.C as well as a.c. voltages were applied and duration of the process was varied to study their effect on film morphology and the thickness of the deposited CdS. The current-voltage characteristics of the CdS-deposited alumina films were plotted and the phase of the electrodeposited CdS was found to be hexagonal using XRD.

With an increasingly aging population, a significant challenge in implantology is the creation of biomaterials that actively promote and accelerate tissue integration while offering excellent mechanical properties. Engineered surfaces with superimposed micro and nanoscale topographies showed great potential to control and direct biomaterial-host tissue interactions. However, these modified surfaces require a careful assessment to prevent potential adverse effects on the fatigue resistance, a factor which may ultimately cause premature failure of biomedical implants. In this context, the surfaces of two widely used biocompatible metals, namely CP Ti and Ti-6Al-4V, were engineered through simple yet efficient chemical treatments which demonstrated the ability to confer exciting new bioactive capacities. The qualitative and quantitative assessments of the fatigue resistance of polished and treated metals were carried out. Results from this study highlight the importance of mechanical considerations in the development and evaluation of nanoscale surface treatments for metallic biomedical implants.

Les pièces en aluminium sont largement utilisées dans le domaine aéronautique en raison de leurs bonnes propriétés mécaniques. Mais elles nécessitent un traitement de surface pour améliorer leur tenue en corrosion. Soumises à de nouvelles normes sur l'utilisation de produits chimiques et à la prise de conscience de la protection environnementale et humaine, les industries aéronautiques doivent à présent impérativement remplacer les procédés de traitements de surface actuels, devenus obsolètes car incluant des composés CMR. L'objectif de ces travaux de recherche est de développer un traitement de surface par voie liquide, à la fois innovant et conforme à la législation REACH, pour améliorer les propriétés d'anticorrosion des alliages d'aluminium ; le procédé d'élaboration présentement étudié, est composé d'une anodisation poreuse puis d'un colmatage par imprégnation de particules au sein des pores. Un film anodique poreux " modèle " a tout d'abord été élaboré et caractérisé : son épaisseur est de 10 µm, tandis que les pores sont rectilignes et ont un diamètre moyen de 120 nm. Puis, nous avons étudié la synthèse par voie aqueuse, de nanoparticules de boehmite, l'optimisation des différents paramètres de synthèse ayant permis finalement d'obtenir des particules d'une taille inférieure à celle des pores du film anodique. Deux techniques d'incorporation ont ensuite été expérimentées : le trempage-retrait et l'électrophorèse. La compréhension des mécanismes mis en jeu et de l'influence de différents paramètres opératoires, a permis une maitrise des procédés et l'insertion effective de particules. Des caractérisations microstructurales ont en particulier montré que l'insertion de particules est plus aisée dans le cas d'une électrophorèse avec une tension pulsée. Enfin, la mise en œuvre d'un post-traitement hydrothermal après l'imprégnation, a permis d'obtenir un colmatage complet des pores du film anodique, et d'augmenter significativement les propriétés anticorrosion. / Aluminum parts are widely used in the aeronautical field because of their good mechanical properties. But they require a surface treatment to improve their resistance to corrosion. Subject to new standards on the use of chemicals and awareness of environmental and human protection, the aeronautical industry must now replace current surface treatment processes, which have become obsolete because they include CMR compounds. The aim of this research is to develop a surface treatment, both innovative and REACH compliant, to improve the anticorrosion properties of aluminum alloys; the process here studied, is composed of a porous anodization and a sealing by impregnation of particles within the pores. A "model" porous anodic film was first prepared and characterized: its thickness is 10 µm, while the pores are straight and have a mean diameter of 120 nm. Then, we studied the aqueous synthesis of boehmite nanoparticles; the optimization of the synthesis parameters finally allowed to obtain a particle size smaller than the pore diameter. Two incorporation techniques were then tested: dip-coating and electrophoresis. The understanding of the involved mechanisms and of the influence of different operating parameters, allowed a control of the processes and the effective insertion of particles. In particular, microstructural characterizations showed that the particle insertion is easier using pulsed voltage electrophoresis. Finally, a hydrothermal post-treatment after the impregnation, allowed to obtain a complete sealing of the anodic film pores, and to significantly increase the anticorrosion properties.

Ces travaux de thèse ont pour but l’évaluation et le développement de briques technologiques en silicium poreux répondant à la problématique de l’intégration monolithique 3D rattachée au concept du “more than Moore” : d’une part l’intégration sur silicium de composants passifs RF, d’autre part, la réalisation de chemins traversants d’interconnexion à fort facteur d’aspect par voie électrochimique. Dans un premier temps, différents substrats mixtes silicium / silicium poreux sont réalisés. Des inductances en cuivre, réalisées sur un substrat mésoporeux de 200 µm de profondeur et de porosité proche de 60%, atteignent des facteurs de qualité à 20 GHz jusqu’à 55% supérieurs à ceux mesurés sur silicium massif. Une perspective d’industrialisation de ce type d’application est à l’étude dans le cadre d’une thèse CIFRE. La gravure de matrices de pores à fort facteur d’aspect, bien qu’encore difficilement localisable en termes de qualité de périphérie, fait d’autre part l’objet de développements, notamment pour la fabrication de condensateurs à haute densité capacitive et de contacts d’interconnexions en cuivre. / Those thesis works deal with the evaluation and the development of porous silicon technological step in order to answer some of the monolithic integration challenges bring by the “more than Moore” problematic in microelectronics industry: on one hand, the integration on silicon of passive RF devices, on the other hand, realization by electrochemical etching of through silicon via. In a first time, several mixed porous silicon / silicon substrat are realized. Copper inductors, realized on 200 µm thick and 60% porosity mesoporous layer, show a quality factor superior to 55% to the one obtained on massive silicon. Industrialization perspectives are on the line via a CIFRE PhD convention. In a second time, several electrochemical etching process are evaluated. Among them, high aspect ratio macropore array etching, although poorly localizable, allows many perspectives: copper via and high density capacitor.

Orientador: Prof. Dr. Renato Altobelli Antunes / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, 2017. / Nesse trabalho, o efeito do tempo de imersão em solução NaCl 3,5%p de amostras de zircaloy-4 anodizadas foi avaliado. O efeito do tempo de anodização no comportamento de corrosão da zircaloy-4 também foi avaliado em solução NaCl 3,5%p a temperatura ambiente. O banho de anodização consistiu de uma solução de HF 0,5%p e o processo foi realizado aplicando um potencial fixo de 20V a amostras de zircaloy-4. O comportamento de corrosão foi avaliado por espectroscopia de impedância eletroquímica e polarização potenciodinâmica. Os testes foram conduzidos após 2 condições de imersão diferentes, em 1 hora e em 7 dias de imersão. A morfologia da camada anodizada foi examinada por microscopia eletrônica de varredura, a espessura do filme foi avaliada por microscopia confocal de varredura a laser e a composição química foi determinada por espectroscopia de fotoelétrons excitados por raios X (XPS). O perfil de concentração atômica em função da profundidade foi analisado por XPS para cada condição de anodização, bem como a concentração atômica superficial dos elementos Zr, F e O. Aumentando o tempo de anodização, não foi possível observar uma relação direta com a resistência à corrosão. A condição sem filme e de 1 minuto de anodização apresentaram comportamento mais resistente para a condição de imersão de 1 hora, enquanto que para 7 dias a condição de 3 minutos foi a mais resistente. / In this study, the effect of immersion time in NaCl 3.5%w. of anodized zircaloy-4 samples were analyzed. The effect of anodizing time on the corrosion behavior of zircaloy-4 alloy was studied in 3.5 wt.% NaCl solution at room temperature. The anodizing bath consisted of a HF solution and the process was achieved by applying a fixed potential of 20 V to zircaloy-4 specimens. The corrosion behavior was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization. The tests were conducted over two different immersion conditions, after 1 hour of immersion and after seven days of immersion. The anodized layer morphology was examined by scanning electron microscopy, thickness of film was analyzed by confocal microscopy and the chemical composition was evaluated by X-ray photoelectron spectroscopy (XPS). The depth profile was analyzed through an XPS spectrum in each anodization condition, as well as atomic concentration of elements Zr, Fr and O. By increasing the anodizing time, was not possible to observe any relation between corrosion resistance. The condition without film and one minute of anodization presented more resistant behavior through 1 h immersion condition, while for 7 days the best condition was 3 minutes.

With an increasingly aging population, a significant challenge in implantology is the creation of biomaterials that actively promote and accelerate tissue integration while offering excellent mechanical properties. Engineered surfaces with superimposed micro and nanoscale topographies showed great potential to control and direct biomaterial-host tissue interactions. However, these modified surfaces require a careful assessment to prevent potential adverse effects on the fatigue resistance, a factor which may ultimately cause premature failure of biomedical implants. In this context, the surfaces of two widely used biocompatible metals, namely CP Ti and Ti-6Al-4V, were engineered through simple yet efficient chemical treatments which demonstrated the ability to confer exciting new bioactive capacities. The qualitative and quantitative assessments of the fatigue resistance of polished and treated metals were carried out. Results from this study highlight the importance of mechanical considerations in the development and evaluation of nanoscale surface treatments for metallic biomedical implants.

Předkládaná práce se zabývá nalezením vhodných podmínek pro výrobu nanaporézní struktury na tenké hliníkové vrstvě. V této práci jsou popsány postupy výroby nanoporézních struktur a jejich přípravou. Vznikly póry o rozměrech 5–20 nm. Byla zkoumána závislosti proudové hustoty v zavislosti na přiloženém pulzu. Všechny výsledky byly zkoumány pomocí SEM analýzy. Byla použita cyklická volatmetrie pro stanovení redukčního napětí při depozici niklu a zlata.

This work deals with the preparation of gold nanostructures for future usage in electrochemical sensors and biosensors, methods for their characterization and production. The emphasis is focused on the template-based electrodeposition method of gold and on study of the effect of manufacturing conditions on physical properties, mainly electrical and topological of nanostructures. Thesis is focused also on overall function and sensitivity of the gold nanostructured electrode.