Дисертації з теми "Electric properties tomography"

chemical partitioning of Cobalt-containing soft magnetic amorphous and nanocomposite materials has been investigated with particular focus on its consequences on these materials’ nanostructure and electrical resistivity. Theory, models, experiment, and discussion in this regard are presented on this class of materials generally, and are detailed in particular on alloys of composition, (Fe65Co35)79.5+xB13Si2Nb4-xCu1.5, for X={0- 4at%}, and Co-based, Co76+YFe4Mn4-YB14Si2Nb4, for Y={0-4at%}. The context of this work is within the ongoing efforts to integrate soft magnetic metal amorphous and nanocomposite materials into electric motor applications by leveraging material properties with motor topology in order to increase the electrical efficiency and decrease the size, the usage of rare-earth permanent magnets, and the power losses of electric motors. A mass balance model derived from consideration of the partitioning of glass forming elements relates local composition to crystal state in these alloys. The ‘polymorphic burst’ onset mechanism and a Time-Temperature- Transformation diagram for secondary crystallization are also presented in relation to the partitioning of glass forming elements. Further, the intrinsic electrical resistivity of the material is related to the formation of virtual bound states due to dilute amounts of the glass forming elements. And lastly, a multiphase resistivity model for the effective composite resistivity that accounts for the amorphous, crystalline, and glass former-rich amorphous regions, each with distinct intrinsic resistivity, is also presented. The presented models are validated experimentally on the Co-containing alloys by Atom Probe Tomography performed through collaboration with Pacific Northwestern National Laboratory.

Cette étude porte sur la compréhension du lien existant entre l’architecture microstructurelle et les propriétés effectives de conductivité dans les électrodes des batteries Li-ion. Les batteries Li-ion sont très intéressantes pour des domaines tels que le transport électrique. En effet, elles présentent une grande densité d’énergie et de puissance ce qui en fait de bons substituts pour les moteurs thermiques. Cependant, même si elles sont maintenant assez largement utilisées dans beaucoup de domaines, il y a toujours besoin d’en optimiser les performances. Ceci passe par une meilleure compréhension de l’impact de la microstructure sur les propriétés effectives pour réduire l’écart entre théorie et pratique. L’attention est portée ici sur les électrodes positives des batteries lithium-ion. Les caractéristiques tridimensionnelles telles que la percolation des phases, leur tortuosité ou encore leurs dimensions caractéristiques ont un fort impact sur les propriétés à l'échelle macroscopique. Leur étude nécessite l’utilisation de techniques d’imagerie 3D comme la tomographie aux rayons X et la tomographie sériée par faisceau d’ions focalisés et MEB (FIB/SEM) pour obtenir des données quantitatives et en interpréter les propriétés de transport de charge. Ces volumes sont alors traités (segmentation et analyses morphologiques) et utilisés comme base pour des simulations numériques. La méthode FFT (Fast Fourrier Transform) avec opérateur de Green « discret » est choisie. Ces simulations permettent, soit de remonter aux propriétés de conduction électrique des phases, à partir de la mesure de la conductivité de l’électrode, par méthode inverse, soit de prédire la conductivité effective de l’électrode, en utilisant des propriétés mesurées expérimentalement sur les phases prises séparément. Les microstructures 3D numériques peuvent également être altérées afin de prédire l’impact, sur ses propriétés effectives, de changements de composition dans la formulation de l’électrode. De nouveaux outils consacrés à la meilleure compréhension de la relation entre microstructure, propriétés effectives et performance des batteries lithium-ion sont développés
Li-ion batteries are interesting for applications such as electric vehicles. They have indeed a high energy and power density, which makes them good substitutes for internal combustion engines. However, even if they are now quite widely used in many fields, there is still a need to optimize their performance. This requires a better understanding of the impact of the electrodes microstructure on their effective properties to narrow the gap between ideal and practical performance. Three-dimensional characteristics such as the carbon additive percolation or the tortuosity of the porosity have a strong impact on the electrode charge transport properties and power performance. The use of 3D imaging techniques such as X-ray tomography and serial focused ion beam and SEM tomography (FIB/SEM) is very powerful to quantify the electrode microstructures and interpret their charge transport properties. Furthermore, by processing the reconstructed volumes, one can use them as a basis for numerical simulations. We have chosen the FFT (Fast Fourrier Transform) method with "discrete" Green operator for numerical computations. These simulations can either be used to back calculate the phase (active material or conducting additive/binder) conduction properties from macroscopic electrical measurements by inverse method, or to predict the electrode effective conductivity from the phase conductivities. The 3D numerical microstructures obtained can also be modified in order to predict the influence of compositional changes in the electrode formulation on its properties. This study sets new tools to understand better the relationships between microstructure, effective electrical properties and the performance of Li-ion battery composite electrodes

Among the commercial aluminum alloys, aluminum 319 (Al-7wt%Si-4wt%Cu) type alloys are popularly used in automobile engine parts. These alloys have good casting characteristics and excellent mechanical properties resulting from a suitable heat treatment. To get a high strength in the 319 type alloys, grain refining, reducing the porosity, solid solution hardening, and precipitation hardening are preferred. All experimental variables such as solidification condition, composition, and heat treatment are influence on the precipitation behavior; however, precipitation hardening is the most significant because excess alloying elements from supersaturated solid solution form fine particles which act as obstacles to dislocation movement. The challenges of the 319 type alloys arise due to small size of precipitate and complex aging response caused by multi components. It is important to determine the chemical composition, crystal structure, and orientation relationship as well as precipitate morphology in order to understand the precipitation behavior and strengthening mechanism. In this study, the mechanical properties and microstructure were investigated using transmission electron microscopy and three dimensional atom probe tomography. The Mn and Mg effects on the microstructure and mechanical properties are discussed with crystallographic study on the iron intermetallic phases. The microstructural evolution and nucleation study on the precipitates in the low-Si 319 type aluminum alloys are also presented with sample preparation and analysis condition of TEM and 3DAP tomography.

Selective electron beam melting (SEBM) is a promising powder bed Additive Manufacturing technique for near-net-shape manufacture of high-value titanium components. An extensive research program has been carried out to characterise in 3D the size, volume fraction, and spatial distribution of the pores in model samples, using X-ray computed tomography (XCT), and correlate them to the SEBM process variables. The average volume fraction of the pores (97.5 %) where fatigue cracks would initiate based on the relative stress intensity factor of all the pores. In contrast, crack growth was found to be insensitive to porosity, which was attributed to the much higher stress concentration generated by the crack in comparison to the pores. Some crack diversion was associated with the local microstructure, with prior β grain boundaries often coincident with crack diversion.

La réduction du poids des avions est l'un des grands défis de l'industrie aérospatiale. Afin d'atteindre les objectifs ambitieux en matière de consommation de carburant et de réduction des émissions, des composites renforcés de fibres de carbone, ont été introduits sur le marché. Ces matériaux suscitent un intérêt croissant, néanmoins, ils possèdent une faible conductivité électrique, ne permettant pas de garantir une protection contre la foudre. Pour cette raison, les composites chargés de particules conductrices font l'objet d'activités de recherche en cours. L'objectif est le développement de composites multifonctionnels avec des propriétés électriques accrues. Pour l'heure, la matrice thermoplastique de référence est le PEEK mais ce polymère reste toutefois cher, et sa température d'élaboration élevée. Dans ce but, des matrices thermoplastiques, telles que le PEKK, sont à nouveau étudiées. Entre la matière première et la pièce finale, la matrice thermoplastique subit plusieurs cycles de traitement à haute température (imprégnation, consolidation, procédés d'assemblage) au cours desquelles sa capacité à cristalliser évolue sans cesse. Afin d'évaluer l'impact du procédé et des constituants du composite sur les propriétés du composite, la cristallisation a fait l'objet d'une attention particulière. Deux dispositifs expérimentaux complémentaires ont été utilisés afin de caractériser la cristallisation : une platine chauffante, permettant d'appliquer un cycle thermique et d'observer la cristallisation en microscopie optique ainsi que la calorimétrie différentielle à balayage. L'influence des fibres de carbone et des particules conductrices sur la cinétique de cristallisation a été évaluée. Une diminution des temps de cristallisation a été observée à travers l'augmentation du taux de germination. Les données recueillies ont servi à développer un modèle de cinétique de cristallisation identifié à travers une approche originale en se basant sur des données microscopiques et enthalpiques. Ce modèle permet de prédire les cinétiques de cristallisation des composites à matrice PEKK mais il ne permet pas de rendre compte de la microstructure finale engendrée. Or, cette dernière a un impact non négligeable sur les propriétés mécaniques comme cela a été prouvé à travers des essais de nano-indentation. Pour prévoir la microstructure finale, un modèle basé sur l'approche pixel coloring a été développé. L'influence des fibres de carbone a été introduite à travers la formation d'une phase transcristalline. Une bonne corrélation est constatée entre l'approche analytique, la simulation et les données expérimentales en termes de cinétique de cristallisation. Des caractérisations mécaniques et électriques ont été effectuées afin d'évaluer les performances de ces nouveaux matériaux. Sur les matériaux étudiés, la réponse mécanique n'est pas homogène comme observé sur des essais de traction suivis en stéréo-corrélation. L'étude de la santé matière montre l'existence de défauts, en particulier, à l'échelle de la microstructure. Afin de prendre en compte ces particularités, il est ainsi nécessaire de décrire plus finement la microstructure. Pour cela, la tomographie à rayons X a été utilisée afin de caractériser le composite. Les récents développements de cette technique permettent, en combinaison avec des outils de segmentation, de reconstruire une géométrie représentative du matériau. Cette géométrie est utilisée pour simuler le comportement mécanique ainsi que la cristallisation. Les simulations numériques d'un VER sont capables de prédire les propriétés d'un pli, puis celles du stratifié. Cette modélisation multi-échelle pourrait réduire le nombre et le coût des campagnes expérimentales. Ainsi, déterminer les propriétés de la structure finale en se basant sur des caractérisations et simulations à l'échelle de la microstructure est un enjeu scientifique et industriel stratégique. Ce travail constitue une contribution vers cette approche
Reducing aircraft weight is one of the major challenges facing the aerospace industry. In order to achieve the ambitious goals of fuel consumption and emission reduction, carbon-fiber reinforced composites have been introduced to the market. These materials are attracting increasing interest, however, they have low electrical conductivity to ensure protection against lightning strike. For this reason, composites filled with conductive particles are the subject of ongoing research activities. The objective is the development of multifunctional composites with enhanced electrical properties. Actually, the most used thermoplastic matrix is PEEK, but this polymer remains expensive, and its processing temperature is high. For this purpose, thermoplastic matrices, such as PEKK, are again studied. Between the raw material and the final part, the thermoplastic matrix undergoes several thermal steps with high temperature exposure (impregnation, consolidation, forming and assembly processes) during which its ability to crystallize evolves continuously. In order to evaluate the impact of the process and the composite constituents on its properties, crystallization has been the subject of particular attention. Two complementary experimental devices were used to characterize the crystallization. The heating stage, allows to apply a thermal cycle and observe the crystallization in optical microscopy and differential scanning calorimetry. The influence of carbon fibers and conductive fillers on the crystallization kinetics was evaluated. A decrease in crystallization times was observed through the increase of the nucleation rate. The collected data were used to develop a kinetic model identified through an original approach based on microscopic data. This model makes it possible to predict the crystallization kinetics of PEKK composites. Nevertheless, it does not make it possible to predict the final microstructure. However, the microstructure has a significant impact on mechanical properties as it has been proven through nano-indentation tests. To predict the final microstructure, a model based on the pixel coloring approach has been developed. The influence of carbon fibers has been introduced through the formation of a transcrystalline phase. A good correlation is found between the analytical approach, the simulation and the experimental data in terms of crystallization kinetics. Mechanical and electrical characterizations were performed to evaluate the performance of these new materials. On the studied materials, the mechanical response is not homogeneous as observed on tensile tests followed in stereo-correlation. The study of matter health shows the existence of defects, in particular, at the microstructure level. In order to take this particularity into account, it is thus necessary to describe the microstructure more finely. For this, X-ray tomography was used to characterize the composite. Recent developments in this technique allow, in combination with segmentation tools, to reconstruct a representative geometry of the material. This geometry is used to simulate the mechanical behaviour as well as the crystallization. The numerical simulations of an RVE are able to calculate the properties of a ply, then those of a laminate. This multi-scale modelling could reduce the number and cost of experimental campaigns. Thus, determining the properties of the final structure based on characterizations and simulation at the microstructure scale is a strategic scientific and industrial issue. This work is a contribution towards this approach

Depuis 30 ans, les exigences règlementaires en matière d’isolation thermique des bâtiments augmentent sans cesse. Pour mieux isoler, et conserver la surface habitable et la valeur patrimoniale, il est nécessaire d’augmenter les performances des isolants thermiques. Si les meilleurs systèmes classiques d’isolant atteignent désormais des conductivités thermiques proches de 30 mW/(m.K), les matériaux supers isolants à pression atmosphérique affichent moins de 18 mW/(m.K) et sont à base d’aérogels de silice. Cette matière première doit ses excellentes performances thermiques, à d’une part la taille de ces nanopores inférieure à 70nm, et d’autre part leur très forte quantité. Ceci induit par contre de très faibles propriétés mécaniques, les systèmes super isolants formulés avec des aérogels sont donc toujours des composites : empilement granulaire faiblement lianté. Pour développer l’optimisation de ces formulations, il est nécessaire de disposer d’outils de caractérisation microstructurales multiéchelles dédiés aux aérogels et au suivi pas à pas des étapes d’élaboration post synthèse. Ce travail de thèse a pour objectif de les mettre en place et de les valider. Les matériaux supports de cette thèse, sont des aérogels de silice hydrophobes granulaires et deux formulations liantées en phase aqueuse. Ces formulations architecturées, par une faible fraction volumique de liant organique de taille nanométrique, se distinguent par la taille et le type de surfactant employé, et les performances tant thermiques que mécaniques obtenues. Tout d’abord, le réseau poreux de silice à l’échelle nanométrique a été imagé et caractérisé par tomographie électronique. Cette partie vise à fournir une distribution en taille de pores, particules et agrégats, destinée à alimenter des modèles thermo-mécaniques. Dans un second temps, l’empilement granulaire des aérogels non liantés a été étudié par tomographie aux rayons X. Les résultats de compacité, les morphologies des réseaux de pores, et de grains ont été couplés aux mesures de masse volumique et de porosité inter-granulaire afin de dégager un lien entre microstructure de l’empilement granulaire et conductivité thermique mesurée. Enfin, les interactions aérogels de silice/liant sont imagées en utilisant l’ESEM wet-stem. Une méthodologie quantitative permet ensuite de s’assurer que le surfactant employé induit bien d’une part une dispersion homogène des aérogels, et d’autre part un réseau texturé de liant. Pour conclure, les propriétés thermiques et mécaniques sont mesurées sur les composites référence et des composites innovants avec une étude détaillée des microstructures formées en synergie. Des pistes d’optimisation matériau par opacification intra-granulaire des aérogels sont proposées, un nouveau surfactant est infirmé. Les outils développés valident ainsi leur pertinence pour assurer la qualification des futures formulations de matériaux super isolants
The national objectives on the reduction of the rejections of greenhouse gases bring to the necessity of a thermal renovation for 75 % of the French buildings. As the requirements for old and new buildings increase their standards, design thinner and more efficient insulation materials is of great and increasing interest. New insulating materials with thermal conductivities lower than the still dry air (25 mW / (m. K)), such as based silica xerogel products (15 mW / ( m.K )), recently developed, are an interesting choice to answer those new fonctionnalities. In our study, silica xerogels (porosity > 80 %, specific surface > 600 m ²/g) are available as granular materials and binded stiff composite boards (xerogels / latex). The optimization of these materials requires to understand the link between their microstructure, their thermal conductivity and their mechanical behaviour

The effect of individual and combined zirconium and manganese additions have been compared for an AA2198 6 mm thick sheet in T351 temper regarding their influence primarily on recrystallisation resistance and secondly on fracture toughness and overageing resistance. A complete characterisation of the dispersoid distributions was carried out for a deeper understanding of the effects of the Al3Zr and Al20Cu2Mn3 particles, involving studying their formation from the as-cast and homogenised stage.The most important finding in this work was the lower recrystallisation resistance in the alloy containing 0.1 wt%Zr + 0.3 wt%Mn compared to that containing only 0.1 wt%Zr. This result was rather unexpected, if one considers the opposite microsegregation patterns of Zr and Mn during casting, which leads to dispersoids occupying the majority of the grains’ volume and minimising dispersoid-free zones that could be potential sites for nucleation of recrystallisation. The other two alloys with dispersoid additions 0.05 wt%Zr + 0.3 wt%Mn and 0.4 wt%Mn, were partially and fully recrystallised respectively in the rolled T351 condition.Equally important in this work, was the observation that the opposite microsegregation trend of Zr and Mn sufficed to restrict grain growth in unrecrystallised areas. The 0.1Zr-0.3Mn alloy exhibited the lowest grain size of all alloys, both in the T351 temper and after annealing at 535oC for up to 144 hours. The reason for this was the combined action of Al20Cu2Mn3 dispersoids and Mn solute in the regions where the Zr concentration was low (i.e. near the grain boundaries), which offered additional pinning pressure to those areas compared to the 0.1Zr alloy.The lower recrystallisation resistance of the 0.1Zr-0.3Mn alloy was explained on the grounds of two main factors. The first was the lower subgrain size and hence stored energy within bands of Al20Cu2Mn3 dispersoids, which increased the driving force for recrystallisation in these regions. The second was the interaction between Zr and Mn that led to a decrease in the Al3Zr number density and pinning pressure. Since Zr was the dominant dispersoid family in terms of inhibiting recrystallisation, inevitably this alloy became more prone to recrystallisation. The Al3Zr pinning pressure was found to be much lower especially within bands of Al20Cu2Mn3 dispersoids. The detrimental effect of the Mn addition on the Al3Zr distribution was proven not to result from the dissolution of Zr within Mn-containing phases, and several other phases, at the grain interior and also in grain boundaries. The observed effect could not be precisely explained at this stage.Concerning mechanical properties, the 0.1Zr alloy exhibited the best combination of properties in the Kahn tear tests for fracture toughness. Further, it had a higher overageing resistance compared to the 0.1Zr-0.3Mn alloy.As an overall conclusion from this work, considering all the studied properties here that are essential for damage tolerant applications, the addition of 0.1 wt%Zr to the AA2198 6 mm thick sheet was found to be superior to that of the combined addition of 0.1 wt%Zr + 0.3 wt%Mn.

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O objetivo deste estudo foi a Y-TZP odontológica submetida ao envelhecimento hidrotérmico acelerado (EH). Especificamente: a) determinar a curva cinética de transformação de fase tetragonal para monoclínica; b) calcular a velocidade de crescimento da frente da camada transformada durante o EH; c) avaliar a relação entre a porcentagem de fase monoclínica e profundidade da transformação de fase com a resistência à flexão biaxial (FB); d) avaliar o efeito da associação do EH e fadiga na resistência à FB. Discos sinterizados (YZ- Vita YZ, LP-Lava Plus) foram submetidos ao EH a 120°C, 130°C e 150°C e analisados por difração de raios X (DRX). Uma amostra por grupo foi analisada por microscopia eletrônica de varredura (MEV) e tomografia de coerência óptica (OCT) para calcular a profundidade de transformação de fase e a velocidade da frente de transformação. Grupos de (YZ, LP e LA-Lava) foram submetidos ao EH (150°C) por (n=10): 0, 5, 25, 70 e 140 horas. Após o EH os grupos de YZ foram novamente divididos (n=10): com e sem ciclagem mecânica, todas as cerâmicas foram submetidas ao teste de flexão biaxial (ISO 6872) e análise de variância 1 fator (ANOVA) (α=0,05) para comparar os resultados. Os resultados de DRX indicam que a Y-TZP apresenta um comportamento sigmoidal de transformação de fase devido à limitação da profundidade de penetração dos raios X (~6,3 μm). As análises de MEV e OCT confirmaram o crescimento linear da frente de envelhecimento em função do tempo para todas as temperaturas. O ANOVA 1-fator demonstrou redução de 10-19% da resistência à FB após 140 horas de envelhecimento (150°C) para todas as cerâmicas, havendo correlação negativa entre profundidade da camada transformada e resistência à FB. Extrapolando os resultados de profundidade para 37°C foi calculado que a frente de transformação de fase levaria 1053 e 2104 anos para atingir a profundidade de 62,67μm e 85,55μm responsáveis pela diminuição da resistência mecânica da YZ e LP, respectivamente. A associação do EH com a ciclagem mecânica não apresentou efeitos deletérios para a YZ. O OCT foi validado como método preciso, fácil e rápido para avaliação da camada transformada e estudos de cinética.
Tese (Doutorado em Tecnologia Nuclear )
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

The combination of X-ray imaging and diffraction techniques provides a unique tool for structural and mechanical analysis of engineering components. A variety of modes can be employed in terms of the spatial resolution (length-scale), time resolution (frequency), and the nature of the physical quantity being interrogated. This thesis describes my contributions towards the development of novel X-ray “rich” imaging experimental techniques and data interpretation. The experimental findings have been validated via comparison with other experimental methods and numerical modelling. The combination of fast acquisition rate and high penetration properties of X-ray beams allows the collection of high-resolution 3-D tomographic data sets at submicron resolution during in situ deformation experiments. Digital Volume Correlation analysis tools developed in this study help understand crack propagation mechanisms in quasi-brittle materials and elasto-plastic deformation in co-sprayed composites. For the cases of crystalline specimens where the knowledge of “live” or residual elastic strain distributions is required, diffraction techniques have been advanced. Diffraction Strain Tomography (DST) allows non-destructive reconstruction of the 2-D (in-plane) variation of the out-of-plane strain component. Another diffraction modality dubbed Laue Orientation Tomography (LOT), a grain mapping approach has been proposed and developed based on the translate-rotate tomographic acquisition strategy. It allows the reconstruction of grain shape and orientation within polycrystalline samples, and provides information about intragranular lattice strain and distortion. The implications of this method have been thoroughly investigated. State-of-the-art engineering characterisation techniques evolve towards scrutinising submicron scale structural features and strain variation using the complementarity of X-ray imaging and diffraction. The first successful feasibility study is reported of in operando stress analysis in an internal combustion engine. Finally, further advancement of ‘rich’ imaging techniques is illustrated via the first successful application of Time-of-Flight Neutron Diffraction Strain (TOF-NDST) tomography for non-destructive reconstruction of the complete strain tensor using an inverse eigenstrain formulation.

La méthode géophysique électromagnétique inductive dans le domaine temporel (TDEM) est employée dans des domaines tels que l’hydrologie ou l’exploration minière et permet l’établissement de modèles de résistivité électrique du sous-sol. L’application de cette méthode avec des dispositifs d’acquisition réduits, avec des boucles de quelques mètres de côté, rend la mesure plus sensible aux autres paramètres électromagnétiques : la permittivité diélectrique et la viscosité magnétique. L’objet du travail de recherche présenté ici est de réaliser des sondages TDEM avec des dispositifs d’acquisition réduits et d’en extraire non seulement un modèle de résistivité électrique du sous-sol, mais aussi de permittivité diélectrique et de viscosité magnétique. L’acquisition d’un sondage TDEM avec des dispositifs à petites boucles implique également une sensibilité à la réponse du système sur lui-même, plus importante. Des simulations de cette réponse ont été menées afin de pouvoir l’estimer le plus précisément possible et la prendre en compte lors du traitement des données. Une géométrie d’acquisition des mesures est ensuite proposée pour rendre l’interprétation multi-paramètres de la mesure plus accessible. Les effets des propriétés électromagnétiques se superposent sur la mesure en configuration centrale. L’utilisation de géométries avec une sensibilité plus faible à la permittivité diélectrique et la viscosité magnétique permettra de séparer les contributions des différents paramètres. Ces développements méthodologiques ont enfin été testés lors d’acquisitions sur le site test de Garchy (Nièvre)
The geophysical electromagnetic inductive method in the time domain (TDEM) is used in fields such as hydrology or in mining exploration. It allows the establishment of electrical resistivity models of the subsurface. Using this methods with reduced acquisition loops with a width of only a few meters, makes the measurement more sensitive to additional parameters : the dielectric permittivity and the magnetic permeability. The present research work aims to acquire a small-loop TDEM sounding and to extract not only an electical resistivity model but also an estimation of the dielctric permittivity and of the magnetic viscosity. The acquisition of a small-loop TDEM sounding implies a increased sensitivity to the response from the acquisition system itself, in part because of the reduced distance between the transmission and reception loops. Simulations aiming to reproduce this system response have been carried out to be able to take it into account during the data processing step. A specific acquisition geometry is then proposed to ease the multi-parameter interpretation of the TDEM data. The effects from the electric, dielectric and magnetic properties of the ground are overlapping on the measurements in the central configuration. Using different geometry with lower sensivities to dielectric permittivity and magnetic viscosity should make the contribution of each parameter easier to isolate. These methological developments were then tested with field measurement on the test site of Garchy (Nièvre, France)

[ES] Las zeolitas son materiales cristalinos microporosos con canales y tamaños de poro de dimensiones moleculares. La estructura y composición de las zeolitas les confiere interesantes propiedades que permiten su aplicación en una amplia gama de aplicaciones industriales como adsorción, separación o catálisis. La síntesis de zeolitas es la etapa más importante para el control de la estructura y composición de las zeolitas y, por tanto, crítica para la optimización de sus propiedades. Esta tesis se ha centrado en la síntesis de zeolitas utilizando compuestos que contienen fósforo (cationes fosfonio y aminofosfonio) como Agentes Directores de Estructura (P-ADE). El uso de compuestos fosforados influye en la cristalización y propiedades de las zeolitas obtenidas en comparación con las zeolitas obtenidas con cationes de amonio clásicos. Los compuestos fosforados se eligieron debido a su diferente química y estabilidad con respecto a los cationes de amonio clásicos comúnmente usados en la síntesis de zeolitas. Estos aspectos se estudiaron con un estudio comparativo de diferentes cationes de amonio y fosforados. Los compuestos de fósforo utilizados en este trabajo han dado lugar a nuevas estructuras cristalinas (ITQ-58 e ITQ-66) y han abierto nuevas vías de síntesis de zeolitas ya conocidas (RTH, IWV y DON), ampliando su gama de composiciones químicas. La descomposición térmica de los P-ADE confinados dentro de las zeolitas da lugar a la formación de especies de fósforo extra-red que permanecen dentro de los canales y cavidades de las zeolitas. Estas especies modulan las propiedades ácidas y de adsorción de los materiales finales dependiendo de los tratamientos post-síntesis. En este trabajo se ha estudiado una ruta para la incorporación de cantidades controladas de fósforo durante la etapa de síntesis. Esto ha permitido controlar la adsorción y las propiedades ácidas en las zeolitas de poro pequeño, lo que no se puede lograr mediante metodologías de post-síntesis.
[CA] Les zeolites són materials cristal·lins microporosos amb canals i mides de porus de dimensions moleculars. L'estructura i composició de les zeolites els confereix interessants propietats que permeten la seua aplicació en una àmplia gamma d'aplicacions industrials com adsorció, separació o catàlisi. La síntesi de zeolites és l'etapa més important per al control de l'estructura i composició de les zeolites i, per tant, crítica per a l'optimització de les seues propietats. Aquesta tesi s'ha centrat en la síntesi de zeolites utilitzant compostos que contenen fòsfor (cations fosfoni i aminofosfoni) com a agents directors d'estructura (P-ADE). L'ús de compostos fosforats influeix en la cristal·lització i propietats de les zeolites obtingudes en comparació amb les zeolites obtingudes amb cations d'amoni clàssics. Els compostos fosforats es van triar a causa de la seua diferent química i estabilitat pel que fa als cations d'amoni clàssics utilitzats en la síntesi de zeolites. Aquests aspectes s¿estudiaren amb un estudi comparatiu de diferents cations d'amoni i fosforats. Els compostos de fòsfor utilitzats en aquest treball han donat lloc a noves estructures cristal·lines (ITQ-58 i ITQ-66) i han obert noves vies de síntesi de zeolites ja conegudes (RTH, IWV i DO), ampliant la seua gamma de composicions químiques. La descomposició tèrmica dels P-ADE atrapats dins de les zeolites dona lloc a la for-mació d'espècies de fòsfor extra-xarxa que romanen dins dels canals i cavitats de les zeolites. Aquestes espècies modulen les propietats àcides i d'adsorció dels materials finals depenent dels tractaments post-síntesi. En aquest treball s'ha estudiat una ruta per la incorporació de quantitats controlades de fòsfor durant l'etapa de síntesi. Això ha permés controlar l'adsorció i les propietats àcides en les zeolites de porus petit, el que no es pot aconseguir mitjançant metodologies de post-síntesi.
[EN] Zeolites are microporous crystalline materials with channels and pore openings of molecular dimensions. The structure and composition of zeolites confers them interesting properties that allow their application in a wide range of industrial applications as adsorption, separation or catalysis. The synthesis of zeolites is the most important stage to control the structure and composition of zeolites, and thus, critical to optimize their properties. This thesis has been focused on the synthesis of zeolites using phosphorous containing compounds (phosphonium and aminophosphonium cations) as Organic Structure Directing Agents (P-OSDA). The use of these phosphorous compounds influence the crystallization and properties of the obtained zeolites compared to zeolites obtained with classical ammo-nium cations. Phosphorous compounds were chosen because of their different chemistry and stabil-ity properties respect to classical ammonium cations commonly used in the synthesis of zeo-lites. These aspects were studied in a comparative study with different ammonium and phosphorous cations. The phosphorous compounds used in this work have yielded new crystalline structures (ITQ-58 and ITQ-66) and opened new routes for the synthesis of already known zeolites (RTH, IWV and DON), widening their chemical composition range. The thermal decomposition of the P-OSDAs entrapped inside the zeolites yields to the formation of extra-framework phosphorus species that remain inside the channels and voids of the zeolites. These species modulate the adsorption and acid properties of the final materials depending on the post-synthesis treatments. In this work, a route for the incorporation of controlled amounts of phosphorus during the synthesis stage has been studied. This has allowed to control the adsorption and acid properties in small pores zeolites, which cannot be achieved by post-synthesis methodologies.
I wish to firstly acknowledge the Spanish Government for the necessary funding for the FPI pre-doctoral fellowship (BES-2013-062999). Also, this thesis would not have been possible without the infrastructures provided by the UPV and the CSIC staff, fused into the ITQ. Furthermore, I want to acknowledge the Microscopy Service of the UPV for their support in sample microscopy characterization
Simancas Coloma, J. (2021). Synthesis and Characterization of Zeolitic Materials Using Phosphorous Organic Structure Directing Agents [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/171267
TESIS

Indiana University-Purdue University Indianapolis (IUPUI)
This paper presents a novel approach of particulate material (soot) measurement in a Diesel particulate filter using Electrical Capacitance Tomography. Modern Diesel Engines are equipped with Diesel Particulate Filters (DPF), as well as on-board technologies to evaluate the status of DPF because complete knowledge of DPF soot loading is very critical for robust efficient operation of the engine exhaust after treatment system. Emission regulations imposed upon all internal combustion engines including Diesel engines on gaseous as well as particulates (soot) emissions by Environment Regulatory Agencies. In course of time, soot will be deposited inside the DPFs which tend to clog the filter and hence generate a back pressure in the exhaust system, negatively impacting the fuel efficiency. To remove the soot build-up, regeneration of the DPF must be done as an engine exhaust after treatment process at pre-determined time intervals. Passive regeneration use exhaust heat and catalyst to burn the deposited soot but active regeneration use external energy in such as injection of diesel into an upstream DOC to burn the soot. Since the regeneration process consume fuel, a robust and efficient operation based on accurate knowledge of the particulate matter deposit (or soot load)becomes essential in order to keep the fuel consumption at a minimum. In this paper, we propose a sensing method for a DPF that can accurately measure in-situ soot load using Electrical Capacitance Tomography (ECT). Simulation results show that the proposed method offers an effective way to accurately estimate the soot load in DPF. The proposed method is expected to have a profound impact in improving overall PM filtering efficiency (and thereby fuel efficiency), and durability of a Diesel Particulate Filter (DPF) through appropriate closed loop regeneration operation.

Efficient and optimal use of composites in structures requires tools to monitor and capture the complex degradation that can occur within the laminates over time. Structural health monitoring (SHM) techniques uses sensors/actuators on the structure to progressively monitor the health of the structure with minimal manual intervention. Electrical tomography (ET) is a SHM technique that uses voltage measurements from the surface of the laminate to reconstruct a conductivity map of the structure. Since damage has been shown to modify the conductivity of the laminate, the conductivity map can provide an indirect measure of the damage within the material. Studies have shown the capability of ET to identify macroscale damage due to impact. But, little has been done to quantitatively assess damage using ET. In this work, we present a theoretical framework to link degradation mechanisms occuring at the microscale to the conductivity at the mesoscale through damage indicators. The mesoscale damage indicators are then shown to be intrinsic to the ply. Next, we use the knowledge obtained through mesoscale homogenization to study the detectability of transverse cracks. Last, we show how the mesoscale homogenization participates in regularization of the inverse problem and in the quantitative assessment of the reconstructed conductivity map. This is as such the first step towards turning ET into a viable quantitative health monitoring technique.