The ability to integrate multiple photonic devices on a single substrate has turned out to be very advantageous in the fabrication of components for optical communication networks. For example, improved fiber coupling can be achieved by integrating a modulator with an optical mode converter. However, current technology is very limited in its ability to fabricate such photonic integrated circuits (PIC). / We report on a selective area epitaxy (SAE) process suitable for the fabrication of a PIC. The process includes a quantitative model, which for the first time, is capable of predicting the growth rate and composition of thin films selectively deposited by metalorganic chemical vapour deposition in areas close to the dielectric mask as well as areas several microns away. The accuracy of the model is demonstrated by comparing simulation results with experimental measurements of the thickness and composition profiles obtained by surface profilometry and energy dispersed X-ray respectively. / The process is applied to the fabrication of an elecroabsorption modulator and optical mode converter, monolithically integrated on an InP substrate. As part of the fabrication, quantitative modeling of the converter waveguide core deposition is employed to achieve a thickness profile previously designed by beam propagation calculations. Modeling is also used to predict the composition and strain shifts introduced by selective deposition, enabling the composition to be designed such that the maximum strain is minimized. Device measurements demonstrate that SAE is successfully used for the fabrication of a PIC with characteristics superior to those found in conventional devices.

Early empirical publications on metal foam production have shown that ceramic particles are required in the alloy in order to produce stable aluminum foams. Follow-ing a commonly accepted theory, it is believed that the wetting behaviour of the alloy on the particles is the main factor causing the stabilizing effect of the particles. The connection between wetting and metal foamability, however, has not yet been proven. The present work is a systematic study of the wetting behaviour of synthetic aluminum alloys on ceramic substrates under high vacuum conditions rounded off by foaming tests with several of these alloy / ceramic particle systems. / The wetting experiments were conducted in a horizontal tube furnace, which allows for high precision contact angle measurements; foaming tests were carried out in an expandometer. From the wetting behaviour and accompanying foam expansion and quality results, the common foam stabilization theory was evaluated. / Based on analyses of wetting experiments, it was found that certain alloying elements can reduce the contact angle of aluminum on Al2O3 and SiC, and that even wetting systems that are commonly considered non-reactive are in fact highly affected by chemical reactions occurring at the interface. / The foaming results showed that while it appears that the stabilization theory linking wetting behaviour and foam quality is generally correct, wetting experiments under idealized (almost oxygen-free) conditions are unsuitable to predict foam stability based on these models, as in-situ wetting behaviour during foaming seems to be significantly different from that observed during the wetting experiments. / Les premières publications empiriques portant sur la production de mousses métal-liques montrent que la présence de particules de céramique dans la composition d'un alliage est nécessaire afin d'assurer la production de mousses d'aluminium stables. Selon une théorie communément acceptée, il est établi que le facteur à l'origine de l'effet de stabilisation apporté par les particules provient du comporte-ment au mouillage de l'alliage sur les particules. Cependant, aucune connexion entre les caractéristiques de mouillage et de moussabilité du métal n'a encore été établie. Le présent ouvrage propose une investigation systématique sur les comportements au mouillage d'alliages synthétiques d'aluminium sur des substrats de céramique et dans des conditions de vide poussé, corroborée par des essais de moussage avec plusieurs de ces systèmes alliage/particules. / Les expériences de mouillage ont été réalisées dans un four à tube horizontal per-mettant des mesures d'angle de contact de haute précision; les tests de moussage ont été effectués dans un expandomètre. La corrélation entre le comportement au mouillage des alliages et les résultats d'expansion et de qualité des mousses corres-pondantes a permis d'évaluer la théorie de stabilisation des mousses métalliques. / A partir des analyses effectuées sur les expériences de mouillage, il a été montré d'une part que la présence de certains éléments dans la composition de l'alliage peut engendrer une réduction de l'angle de contact de l'alliage d'aluminium sur des substrats de céramiques tels que Al2O3 et SiC; d'autre part, il a été défini que les systèmes de mouillage, bien que généralement considérés inertes, se trouvaient en réalité amplement affectés par l'incidence de réactions chimiques au niveau de l'interface alliage/céramique. / Si les résultats des expériences de moussabilité ont montré de façon générale une bonne corrélation avec la théorie de stabilisation des mousses qui relie le comporte-ment au mouillage de l'alliage et la qualité de la mousse, en revanche les résultats des expériences de mouillage dans des conditions idéales (sous atmosphère très pauvre en oxygène) n'ont pas suivi les prédictions de stabilité des mousses établies par les modèles théoriques. En effet, le comportement au mouillage in-situ de l'alliage, au cours de la formation de la mousse, semble différer de façon significative du comportement observé au cours des expériences de mouillage.

Electron backscatter diffraction (EBSD) is a recognized characterization technique for the scanning electron microscope. Over the last quarter century, several major advancements improved this technique and expanded its applications to the fields of materials engineering and geological science. These improvements have been primarily related to the commercialization of EBSD systems. With their conviviality and ease of use, these systems have reached a broad audience and have contributed to the maturation of EBSD. However, from another perspective, they have also limited the development by the EBSD community: researchers facing atypical problems do not have the opportunity to modify and improve commercial systems to meet their specific needs. Innovation is left to the scientists and engineers working at EBSD companies. This work offers a solution to this problem by the development of an open source, freely available software, EBSD-Image, for processing of diffraction patterns acquired by an EBSD system.Built on top of image analysis software, EBSD-Image provides a flexible and structured interface to implement new algorithms to process and extract information from diffraction patterns. Two applications are given to demonstrate the analytical benefits of the software. In one application, the calculation of different metrics to evaluate diffraction quality led to a more accurate characterization of the microstructure of Zr-2.5Nb pressure tubes. In the other, quantitative measurements of the deformation induced during metallographic specimen preparation were made, in addition to the development of a new quality metric to assess the deformation level in a sample.Furthermore, this work presents tools to validate new algorithms via the generation of simulated diffraction patterns as well as utilities to process and analyze large data sets on a distributed computing grid. Two file formats are introduced to provide a more practical way of processing large numbers of diffraction pattern image files and to share the results of an analysis. Finally, an equation linking the two resolutions of the Hough transform for diffraction patterns of any size and a method to remove artifacts created by vertical Kikuchi bands in the Hough space are proposed. / La diffraction d'électrons rétrodiffusées (EBSD) est une technique de caractérisation reconnue en microscopie électronique en balayage. Au cours du dernier quart de siècle, plusieurs progrès ont amélioré cette technique et ont élargi le spectre de ces applications dans les domaines du génie des matériaux et des sciences géologiques. Ces améliorations ont principalement été reliées à la commercialisation des systèmes EBSD. Avec leur convivialité et leur simplicité d'utilisation, ces systèmes ont permis de rejoindre un plus grand public et ainsi de permettre la maturité de l'EBSD. Toutefois, ils ont également limité la communauté scientifique de participer au développement de cette technique. Les chercheurs qui font face à des problématiques inhabituelles n'ont pas la possibilité de modifier et de perfectionner les systèmes commerciaux pour répondre à leurs propres besoins. L'innovation est réservée aux scientifiques et aux ingénieurs travaillant pour les compagnies d'EBSD. Avec le développement d'un logiciel gratuit à code source libre pour le traitement des diagrammes de diffraction acquis par un système EBSD, EBSD-Image, ce travail propose une solution à ce problème.Conçu à partir d'un logiciel d'analyse d'images, EBSD-Image offre une interface flexible et structurée pour l'implémentation de nouveaux algorithmes afin de traiter et d'extraire un maximum d'informations des diagrammes de diffraction. Deux exemples d'application sont présentés pour démontrer les avantages analytiques du logiciel. L'évaluation de la qualité de la diffraction a permis, pour l'un des deux exemples, de caractériser avec une plus grande exactitude la microstructure des tubes de forces d'alliage Zr-2.5Nb et, pour l'autre, de mesurer quantitativement le niveau de déformation induit lors de la préparation métallographique d'échantillons ainsi que de développer une nouvelle mesure de la qualité pour évaluer la déformation.En outre, ce mémoire présente des outils pour la validation de nouveaux algorithmes par la génération de diagrammes de diffraction simulés et des fonctions utilitaires pour le traitement et l'analyse d'un large ensemble de données sur une grille de calcul. Deux formats de fichier sont introduits afin de fournir une méthode plus pratique pour la manipulation d'un grand nombre de fichiers et de permettre le partage des résultats d'une analyse. Finalement, une équation reliant les deux résolutions de la transformée de Hough pour des diagrammes de diffraction de n'importe quelle dimension et une méthode pour éliminer les artéfacts dans l'espace de Hough engendrés pour les bandes de Kikuchi verticales sont proposées.

Although the study of biominerals may be traced back many centuries, it is only recently that biological principles have been applied to synthetic systems in processes termed "biomimetic" and "bioinspired" to yield materials syntheses that are otherwise not possible and may also reduce the expenditure of energy and/or eliminate toxic byproducts. Many investigators have taken inspiration from interesting and unusual minerals formed by organisms, in a process termed biomineralisation, to tailor the nanostructure of inorganic materials not necessarily found biogenically. However, the fields of nanoparticle synthesis and biomineralisation remain largely separate, and this thesis is an attempt to apply new studies on biomineralisation to nanomaterials science.Principally among the proteins that influence biomineralisation is a group comprised largely of negatively charged aspartic acid residues present in serum. This study is an investigation determining the ability of these serum proteins and other anolagous biomolecules to stabilise biologically relevant amorphous minerals and influence the formation of a variety of materials at the nanoscale. Three different materials were chosen to demonstrate this effect; gold was templated into nanosized single crystals by the action of bioorganic molecules, and the utility of these nanoparticles as a biosensor was explored. The influence of bioorganic molecules on the phase selection and crystal size restriction of titanium dioxide, an important semiconductor with many applications, was explored. The use of bioorganically derived nanoparticles of titanium dioxide was then demonstrated as a highly efficient photocatalyst. Finally, calcium carbonate, a prevalent biomineral was shown to form highly ordered structures over a variety of length scales and different crystalline polymorphs under the influence of a templating protein. In addition, an alternative route to producing calcium phosphate nanoparticle dispersions by mechanical filtration was explored and use as a transfection vector was optimised in two cell lines.Several significant achievements are presented: (i) the assessment of the relative ability of serum, serum derived proteins and their analogues to stabilize the amorphous state, (ii) the formation of single crystalline gold templated by an antibody, (iii) the formation of highly photocatalytically active nanoparticulate anatase by a phosphorylated cyclic esther, (iv) the formation of conical structures at the air liquid interface by the templating ability of a protein and (v) the optimisation of calcium phosphate nanoparticle mediated transfection in two cell lines by mechanical filtration. / Malgré le fait que l'étude des biomatériaux remonte à plusieurs siècles, ce n'est que récemment que des principes biologiques furent appliqués à des systèmes synthétiques dans des procédés de "biomimetic" et "bioinspirés", permettant ainsi de nouveaux matériaux de synthèses tout en réduisant l'expansion d'énergie et/ou d'éliminer les résultantes toxiques. Plusieurs chercheurs se sont inspirés des formes inusuelles dès plus intéressantes créées par des organismes, formés par un procédé de biominéralisation, qui modifie la nanostructure des matériaux synthétiques. Toutefois, les champs d'études des synthèses de nanoparticules et de la biominéralisation demeurent grandement à part, et cette thèse tente d'appliquer de nouvelles études de biominéralisation par rapport à la science des nanomatériaux.Les protéines sériques qui influencent la biominéralisation sont chargées négativement de résidus d'aspartate. Cette recherche déterminera l'habileté de ces protéines et des diverses molécules bio–organiques qui stabilisent biologiquement d'important minéraux aux multiples formes qui influencent la formation de matériaux non biogènes sur une nano échelle; l'or et le dioxyde de titane ont permis de démontrer ce résultat. L'or fut transformé en nanoparticules de cristal par l'action des protéines sériques, et c'est l'utilité de ces nanoparticules en tant que biocapteurs qui fut explorée. L'influence des molécules bios-organiques sur le choix de la phase ainsi que sur la restriction de la grosseur du cristal de dioxyde de titane, un important semi-conducteur dans plusieurs applications, fut explorée. Les nanoparticules dérivant bio-organiquement du dioxyde de titane ont dès lors démontrées leur action hautement efficace comme photo catalyseur. Le carbonate de calcium, un biominéral commun, a su démontré sa capacité à auto-former des structures à multiples échelles ainsi que différents polymorphes cristallins sous l'influence d'une protéine modèle. De plus, la manipulation des structures à former divers arrangements est une variable qui fut démontrée. Finalement, la stabilité des nanoparticules du phosphate de calcium à se disperser dans le sérum de culture fut modifiée afin d'optimiser l'efficacité du transfert dans deux lignes de cellules.Plusieurs grandes recherches ont accomplis de façon significative; (i) l'évaluation de l'habileté relative du sérum, le dérivé des protéines sériques et de leur capacité à stabiliser les phases de leurs multiples formes, (ii) la formation simple cristalline de l'or former par un anticorps, (iii) la formation de nanoparticules très actives photocatalytiquement d'anatase formées par un ester cyclique phosphorylée, (iv) la formation de structures coniques à l'interface air liquide par la capacité de gabarits d'une protéine, (iv) l'optimisation de transfection médiation par des nanoparticules de phosphate de calcium dans deux lignées cellulaires par filtration méchanique.

Molecular self-assembly (MSA) was used to fabricate multilayered composites on silicon, silicon monoxide and silica substrates. 3-mercaptopropyltrimethoxysilane (MPTMS) was grafted onto the substrates, followed by chemisorbed silver colloidal nanoparticles. 1,4-benzenedimethanethiol (BDMT) was used to chemisorb gold to silver colloidal nanoparticles forming an MPTMS-silver-methyl-BDMT-gold heterostructure. A self-poling stilbazole dye---(E)-[4- N,N-(octadecylmethylamino)styryl]pyridine (ODMASP)---was integrated with a mercaptoacetic acid (MAA) spacer into an MPTMS-silver-MAA-ODMASP heterostructure by MSA of ODMASP C18 alkyl tails. ODMASP on fractal silver aggregates enhanced the 2nd-order nonlinear susceptibility implying that silver colloid intensified the electrical field to produce a c2 of 1.48 x 10-22 C3/J 2 (4.00 x 10-8 esu). We used x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), ultraviolet-visible (UV-VIS) spectroscopy and second harmonic generation (SHG) for characterization. We described the synthesis of a tolane dye---N-4-[(4 '-nitrodiphenylethynyl)phenyl]-bis-2 ″-diethanethiolamine (NDPEPD)---by palladium-catalyzed cross-coupling. Corona poled NDPEPD-doped poly(styrene) films produced a c2 of 1.5 x 10-23 C3/J 2 (0.4 x 10-8 esu).

The ability to tailor specific properties, such as stiffness, hardness and thermal expansion has led to the use of metal matrix composites (MMCs) in a wide variety of engineering applications. Squeeze casting can be used to produce MMCs and involves the infiltration of a ceramic preform by liquid metal under pressure exerted by a punch. This work deals with the fabrication and evaluation of an aluminum casting alloy (A356) reinforced with short Al$ sb2$O$ sb3$ fibre (mean fibre length $ sim$265 $ mu$m) using the squeeze casting technique. Discontinuous Al$ sb2$O$ sb3$ fibre preforms of different volume fractions (5-15%), were infiltrated with metal using various melt temperatures (775-825$ sp circ$C) and pressures (20-60 MPa). The microstructure and the mechanical properties of MMCs and unreinforced A356 were investigated. In addition, the MMC response to heat treatment operations was assessed. / The microstructure consisted of primary Al, eutectic Si particles at the fibre surface, and homogeneously dispersed, randomly oriented short fibres. Excellent fibre/matrix contact was achieved and little or no porosity was detected. There was no evidence of any bulk chemical reactions between fibre and matrix alloy at the interface. / The material exhibited a range of properties depending on the Al$ rm sb2O sb3$ content and the casting pressure. In general, the density, elastic modulus, tensile strength, and bulk hardness increased with fibre content and the elongation to failure decreased significantly. (Abstract shortened by UMI.)

Particulate Reinforced Metal Matrix Composites, or PMMCs, consist of ceramic particulates dispersed in a metal matrix. Powder metallurgy (P/M) techniques are often employed to fabricate these materials. P/M offers the simplest way to ensure good distribution of reinforcement within the matrix. In this work, TiC particles have been dispersed in a Ti matrix, yielding a composite which combines the high hardness and abrasive nature of the ceramic phase with the refractory, metallic properties of Ti. / The microstructure of this material has been investigated for composites having various TiC content (2.5wt%-20wt%). Furthermore, the effect of sintering temperature and time on the microstructural evolution was investigated. The addition of TiC was seen to enhance the sinterability of Ti, making it possible to attain theoretical densities $>$99%. Results show that the optimum density is obtained using 2.5 to 5 wt% TiC at a temperature of 1440-1480$ sp circ$C for 2 hours. This study also illustrates the decrease in the microhardness of the TiC particles due to carbon diffusion from TiC into Ti matrix at high sintering temperatures. On the other hand, the addition of TiC significantly increases the overall hardness compared to that of pure Ti.

Ceramic fibers are one of the most important categories of reinforcements for composite materials. This study deals with a novel melt extraction system which has been developed to produce fine oxide ceramic fibers. Four oxide compounds were selected for the production of fibers and characterization of the extraction system. These compounds were CaO-$ rm Al sb2O sb3$ (CA), ZrO$ sb2$-$ rm Al sb2O sb3$ (ZA), ZrO$ sb2$-$ rm Al sb2O sb3$-SiO$ sb2$ (ZAS), and ZrO$ sb2$-$ rm Al sb2O sb3$-TiO$ sb2$ (ZAT). Using a 150 W CO$ sb2$ laser, these materials were melted to obtain a small molten drop, and through shallow contact with a sharpened and bevelled molybdenum wheel, fibers were extracted at various wheel velocities. At low speeds (v 000$ sp circ$C) was measured using a novel technique. Various parameters such as laser power (temperature), wheel tip radius and feed rate have been studied and their effects on the extracted fiber dimensions were investigated. It is suggested that momentum transfer controls the extracted layer thickness and fiber dimensions. The viscosity of the liquid ceramics is a crucial factor in the system, and is estimated to be $<$0.5 poise (0.05 Pa$ cdot$s) at ${ approx}2400 sp circ$C. / Due to the fine fiber dimensions and strong conductive cooling of the molybdenum wheel, the extracted liquid layer was rapidly solidified, and fibers with amorphous, partially crystalline and/or metastable phases were formed. Uniform diameter fibers were amorphous, transparent, flexible and exhibited excellent tensile properties. Fine fibers with a diameter of ${ approx}$10 $ mu$m showed tensile strengths up to 3300 MPa, however, only moderate elastic moduli were achieved (95-143 GPa) due to the amorphous nature of the fibers. The rapidly solidified fibers were thermodynamically metastable, and as shown by differential thermal analysis (DTA), they devitrified in the temperature range of 930-980$ sp circ$C. Heating the fibers at higher temperatures resulted in the formation of various crystalline phases and the development of different grain morphologies.

The increase in efficiency of furnace and refinery components in petroleum industries has been the target of many studies. However, the repair technology for damaged pieces is still to be developed. During prolonged service, a degradation of developed coatings occurs as a result of the harsh environment. Therefore, a repair technology, which can extend the life of the coatings, is now under consideration. In this work, electrospark deposition (ESD) has been investigated to understand the solidification behavior and its possibility to repair damaged MCrAlY coatings. Ni-based alloys with different compositions were deposited on Ni substrate using ESD to understand crystal structure of the solidified deposit and the effect of the dissimilar weld composition on dilution. The electrode samples were prepared by spark plasma sintering (SPS). Firstly, different coatings with single and bi-phase microstructure were deposited on pure Ni substrate. Secondly, NiCoCrAlY and CoNiCrAlY were deposited on the damaged spot of the oxidized NiCoCrAlY and CoNiCrAlY respectively. A fine microstructure of metastable phases obtained from each deposit. Also, it was found that an epitaxial growth of NiCoCrAlY and CoNiCrAlY were obtained on the damaged spots. In addition, α-Al2O3 was obtained on the surface of the deposit after 24hr oxidation at 1000C. / L'augmentation de l'efficacité des fours et des composantes de raffinage dans l'industrie du pétrole a été le sujet de nombreuses études. Cependant, la technologie de réparation des pièces endommagées reste toujours à développer. Durant un service prolongé, une dégradation des revêtements développés se produit en raison de l'environnement hostile. Par conséquent, une technologie de réparation qui peut prolonger la vie des revêtements est actuellement à l'étude. Dans ce travail, le dépôt électro-étincelle (ESD) a été étudié pour comprendre le comportement de la solidification ainsi que son potentiel pour la réparation des revêtements MCrAlY. Différentes alliages à base de nickel ont été déposés sur des substrats de nickel via ESD afin de comprendre la structure cristalline du dépôt solidifié et l'effet du changement de composition de la soudure sur la dilution. Les échantillons d'électrodes ont été préparés par frittage flash (SPS). Tout d'abord, différents revêtements avec une microstructure monophasée et biphasée ont été déposés sur un substrat de nickel pur. Deuxièmement, du NiCoCrAlY et du CoNiCrAlY ont été déposés à l'endroit endommagé sur les oxides de NiCoCrAlY et de CoNiCrAlY respectivement. Une fine microstructure de phases métastables a été obtenue à partir de chaque dépôt. Également, il a été constaté qu'une croissance épitaxiale de NiCoCrAlY et de CoNiCrAlY a été obtenue sur les surfaces endommagées et une couche de α-Al2O3 a été obtenue sur la surface du dépôt après une oxydation de 24 heures à 1000C.

A new process was developed to fabricate particulate metal matrix composites (MMCs). The process involves three steps: (1) modifying the particulate surface by metal coating, (2) forming a particulate porous compact; and (3) introducing metal into the channel network by vacuum infiltration. MMCs with different reinforcements, volume fractions, and sizes can be produced by this technique. Powders of alumina and silicon carbide were successfully coated with nickel and copper in preparation for infiltration with molten aluminum. Electroless Ni and Cu deposition was used since it enhances the wettability of the reinforcements for composite fabrication. While Cu deposits were polycrystalline, traces of phosphorous co-deposited from the electroless bath gave an amorphous Ni-P coating. / The effect of metal coating on wetting behavior was evaluated at 800ºC on plain and metal-coated ceramic plates using a sessile drop technique. The metallic films eliminated the non-wetting behavior of the uncoated ceramics, leading to equilibrium contact angles in the order of 12º and below 58º for Ni and Cu coated ceramics, respectively. The spreading data indicated that local diffusion at the triple junction was the governing mechanism of the wetting process. Precipitation of intermetallic phases in the drop/ceramic interface delayed the formation of Al4C3. / Infiltration with molten Al showed that the coated-particulates are suitable as reinforcing materials for fabricating MMCs, giving porosity-free components with a homogeneously distributed reinforcing phase. The coating promoted easy metal flow through the preform, compared to the non-infiltration behavior of the uncoated counterparts. Liquid state diffusion kinetics due to temperature dependent viscosity forces controlled the infiltration process. Microstructural analysis indicated the formation of intermetallic phases such as CuAl 2, in the case of Cu coating, and Ni2Al3 and NiAl 3 when Ni-coated powders were infiltrated. The overall Ni and Cu content increased from bottom to top of the samples due to dissolution of the metal film by the stream of liquid Al during infiltration. The strengths of the Al/Ni-SiC composites, measured by four-point bending, were 205 and 225 MPa for samples reinforced with 78 mum and 49 mum Ni-SiC, respectively. The mode of fracture was mainly controlled by SiC particle fracture.