A process with aim to prepare an oxidically and thermal resistant layer was performed on the samples from clear aluminium (99,99+ %, VÚK čisté kovy, s. r. o.) and on the samples from clear titanium (99,95 % Goodfellow) with a layer from sputtered aluminium (99,99 %, VÚK čisté kovy, s. r. o.), An oxidic layer was prepared on the samples by anodization in the oxalic acid. The layer had fine, hexagonally organized pores with the diameter of 30 nm. During the following processing was the structure prepared for the electrochemical deposition of copper to the pores. The aim of the electrodeposition was preparation of copper nanowires deposited into the pores of the oxidic layer. The process was performed in the solution of copper sulfate and sulfuric acid in water. The controlling parameter of the deposition was voltage which had a very asymmetric period. The period had to be optimized for a successful preparation of the wires. The result of the whole process was structure with oxidic matrix whose most of the pores were filled with copper.

Eisen-Gallium-Legierungen sind aufgrund ihrer hohen Magnetostriktion und ihrer hervorragenden mechanischen Eigenschaften sehr interessant für Anwendungen sowohl in Form von Sensoren als auch Aktoren. Die fortschreitende Miniaturisierung erfordert die Herstellung von Bauteilen in eindimensionaler Struktur und komplexen Geometrien. Beide Herausforderungen sind mit templatbasierter elektrochemischer Abscheidung zugänglich. Es konnte gezeigt werden, dass dünne Fe-Ga-Schichten schon aus einfachen wässrigen Elektrolyten abgeschieden werden können. Gallium kann nur in Anwesenheit von Fe induziert reduziert werden. Gleichzeitig konnte nachgewiesen werden, dass durch die Hydrolyseneigung der Ga-Ionen immer Hydroxide gebildet und in das Deposit eingebunden werden. Durch die Einführung einer alternierenden potentiostatischen Abscheidung mit einem Reduktions- und einem Relaxationsschritt können dennoch dichte und homogene Fe80Ga20-Schichten mit wenigen Defekten und einem vernachlässigbar kleinen Sauerstoffgehalt hergestellt werden. Die Übertragung der so gefundenen Abscheideparameter zur templatbasierten Nanodrahtherstellung ist nur bis zu einem Porendurchmesser von 100nm möglich. Wird der Durchmesser der Porenkanäle weiter verringert, führt aufgrund eingeschränkter Diffusionsvorgänge die Abscheidung zu segmentierten und sauerstoffreichen Depositen. Die Modifizierung des Elektrolyten durch Komplexierung der Metallionen verhindert die Bildung und Einbindung der Hydroxide. Damit können auch für Porendurchmesser kleiner 100nm Drähte in AAO-Template abgeschieden werden. Diese sind dicht, defektfrei und weisen keinen Zusammensetzungsgradienten entlang der Wachstumsrichtung auf. Detaillierte TEM-Untersuchungen konnten zeigen, dass die Herstellung durch ein einfacheres potentiostatisches Abscheideregime zu weniger verspannten und dennoch homogenen und defektfreien Drähten führt. Für die Herstellung von magnetisch aktiven Drähten sollte daher die potentiostatische der gepulsten Abscheidung vorgezogen werden.

The objective of this work is to enhance the understanding of the delay observed in the early stages of E-coat deposition. E-coat deposition has been widely used by industries such as the automotive industry to form the primary protective coating against corrosion. Currently, models that are used to find the best conditions under which the desired coating coverage for the entire auto body can be achieved do not accurately predict the coating coverage in recessed areas. The accuracy of large-scale models can be improved by enhancing our understanding of the mechanisms responsible for the observed delay. To accomplish this, experiments are performed to define the processes that control deposition initiation and then a model is developed to describe those processes. Simulation results are compared with experimental measurements for a range of conditions to assess the validity of the results. The delay before the onset of deposition is influenced by the type of substrate and properties of the E-coat solution. The impact of the substrate type on the onset of deposition was experimentally investigated. The results of experiments indicated that surface characteristics such as adhesion of bubbles to the surface and the formation of an initial coating increase the local current density on the surface. Investigations of the morphology of the initial coating on different types of substrates indicated that deposition began at areas where the local current density was higher. Increasing the local current density due to the adhesion of bubbles to the surface resulted in a 40% reduction in the time required for the onset of deposition on galvanized steel compared to bare steel. The processes in the solution adjacent to the surface were also investigated to understand the mechanisms responsible for the onset of deposition. Convection was used as a tool to determine the impact of the accumulation of hydroxide ions on the onset of deposition. The results of rotating disk electrode (RDE) experiments showed that the observed delay before deposition was not due to the time required for accumulation of hydroxide ions at the surface. The results of additional experiments showed that the accumulation of micelles was critical to the deposit initiation. The impact of micelle accumulation on the deposit initiation was further explored by developing a mathematical model of the physical processes in the solution adjacent to the surface. The model was evaluated at different conditions and was found to agree with experimental results at different current densities and bulk micelle concentrations. The model and the experimental results from this study help to explain the observed delay in the early stages of E-coat deposition and provide a basis for improving large-scale simulation of E-coat deposition.

Le dépôt de ZnO sur diamant est actuellement assuré par des méthodes physiques (ALD, sputtering, CVD) coûteuses et complexes à mettre en oeuvre. La réalisation de ces dépôts de ZnO peut également être effectuée via des procédés plus doux tels que le procédé électrochimique qui représente une alternative intéressante car peu coûteux, et facile à mettre en oeuvre. L’électrodépôt de ZnO a été très largement étudié sur divers substrats, notamment pour des applications dans le domaine du photovoltaïque. Toutefois, seule une étude a été réalisée concernant l’électrodépôt de ZnO sur diamant alors que de nombreuses applications découlent de telles structures : dispositifs à ondes acoustiques de surface (SAW), photo-détecteurs UV ou bien biocapteurs. L’objectif de la thèse réside ainsi dans l’étude de l’électrodépôt de ZnO sur substrat diamant dopé bore en se basant sur le procédé mis en évidence par le groupe de Lincot dans les années 1990. Cette technique consiste à réduire, en présence d’ions Zn2+, l’oxygène dissous pour former des hydroxydes et a fortiori ZnO par réaction des hydroxydes et des ions Zn2+.Le diamant étant un substrat complexe en raison notamment de son grand gap (5,4 eV), un important dopage est nécessaire pour pouvoir l’étudier dans le domaine de l’électrochimie. Dans un premier temps, les conditions d’électrodépôt de ZnO sur diamant (température, potentiel électrique) ont été déterminées avant d’envisager l’étude de l’influence de divers paramètres expérimentaux. Par la suite, l’influence de la composition du bain a été étudiée puisque les concentrations et la nature des précurseurs de zinc et de l’électrolyte support ont été étudiées, permettant de former toute une variété de structures de ZnO sur diamant. Enfin, la dernière partie de la thèse s’est focalisé sur l’influence de la chimie de surface du diamant sur la morphologie, la structure et l’adhérence des dépôts de ZnO formés. L’état de surface initialement hydrogéné du diamant a été modifié en utilisant des traitements électrochimiques conduisant à la formation de groupements oxydés. / Currently, ZnO deposition on diamond is obtained by physicals methods (ALD, sputtering, CVD) which are expensive and difficult to implement. The realization of these ZnO deposits can also be made by softer methods such as electrodeposition which represents an interesting alternative because of its low cost. ZnO electrodeposition has been already studied on several substrates especially for photovoltaic devices. However, only one study has been realized concerning ZnO electrodeposition on diamond while many applications derived from these structures: surface acoustic wave sensors, UV photodetectors, and biosensors. The aim of this work is the study of ZnO electrodeposition on boron doped diamond by following the process highlighted by Lincot et al in 1990s. This process is based on the oxygen reduction reaction leading to the formation of hydroxides which react with Zn2+ cations to form ZnO. Diamond is a complex substrate which presents a large gap of 5.4 eV requiring an important doping to allow its use in electrochemistry. At first, ZnO electrodeposition conditions (temperature, electrical potential) have been determined. The influence of deposition bath has then been studied by varying nature and concentrations on zinc precursor and electrolyte support. Results indicate the possibility to obtain different ZnO/diamond structures by varying theses parameters. Finally, the influence of the surface termination of diamond on ZnO structures, shape and adherence has been investigated by modifying the H-terminated surface on O-terminated surface by using electrochemical treatments.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19732号 / 工博第4187号 / 新制||工||1646(附属図書館) / 32768 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 作花 哲夫, 教授 安部 武志, 教授 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20364号 / 工博第4301号 / 新制||工||1666(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 邑瀬 邦明, 教授 杉村 博之, 教授 作花 哲夫 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

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Layered double hydroxides (LDH) are a class of anionic clay with alternating layers of positive and negative charge. A metal hydroxide layer with divalent and trivalent metals with a positive charge is complemented by an interlayer region containing anions and water with a negative charge. The anions can be exchanged under favorable conditions. Hydrotalcite (Mg6Al2(OH)16[CO3]·4H2O) and other variations are naturally occurring minerals. Synthetic LDH can be prepared as a powder or film by numerous methods. Synthetic LDH is used in electrode materials, adsorbents, nuclear waste treatment, drug delivery systems, water treatment, corrosion protection coatings, and catalysis. In this dissertation Zn-Al-NO3 derivatives of zaccagnaite (Zn4Al2(OH)12[CO3]·3H2O) are electrochemically synthesized as films and applied to sensing and corrosion resistance applications. First, Zn-Al-NO3 LDH was potentiostatically electrosynthesized on glassy carbon substrates and applied to the electrochemical detection of gallic acid and caffeic acid in aqueous solutions. The modified electrode was then applied to the detection of gallic acid in green tea samples. The focus of the work shifts to corrosion protection of stainless steel. Modified zaccagnaite films were electrodeposited onto stainless steel in multiples layers to reduce defects caused by drying of the films. The films were deposited using a step potential method. The corrosion resistance of the films in a marine environment was investigated while immersed in 3.5 wt.% NaCl environments. Next modified zaccagnaite films were potentiostatically electrodeposited onto stainless steel followed by a hydrophobization reaction with palmitic acid in order to prepare superhydrophobic (>150° contact angle) surfaces. Each parameter of the film synthesis was optimized to produce a surface with the highest possible contact angle. The fifth chapter examines the corrosion resistance of the optimized superhydrophobic film and a hydrophobic film. The hydrophobic film is prepared using the same procedure as the superhydrophobic film except for a difference in electrodeposition potential. The corrosion resistance of these films is investigated in a simulated marine environment (3.5 wt.% NaCl) for short and extended durations. The last chapter summarizes the previous chapters and suggests future directions for this work.