Für den Prozeß des Fügens von Keramik bzw. Keramik mit Metall ergeben sich zahlreiche Probleme, die aus den Eigenschaften der Keramik und den Eigenschaftsdifferenzen zwischen Keramik und Metall resultieren. Unterschiedliche physikalische und mechanische Werkstoffkennwerte bewirken ein zumeist hohes Eigenspannungsniveau des Verbundes, welches in Verbindung mit dem spröden Bruchverhalten keramischer Materialien deren Fügbarkeit verhindert oder einschränkt. Als aussichtsreicher Ansatz bietet sich die Eigenschaftsanpassung des Aktivlotes durch dessen Modifikation mit verstärkenden Materialien an. Es wird ein Konzept für die Herstellung und den Einsatz verstärkter Aktivlote vorgestellt. Theoretische Grundlagen werden durch die Berechnung der Eigenschaften derartiger Lote auf der Basis bewährter Methoden der Verbundwerkstofftheorien geschaffen. Die Simulation mechanisch-thermischer Eigenschaften von Lötverbindungen mit verstärkten Aktivloten unter Einsatz der Methode der finiten Elemente dient dem Erfassen des Spannungsverhaltens. Richtlinien für die Wahl geeigneter Verstärkungskomponenten werden festgelegt. Es wird ein Überblick über geeignete Herstellungsmethoden, deren praktische Realisierung und die Wechselwirkung mit dem Prozeß des Aktivlötens gegeben. Die Bewertung von Aktivlötverbindungen mit verstärkten Loten im Vergleich zu herkömmlichen Verfahren wird auf Grundlage der Ergebnisse von Festigkeitsuntersuchungen vorgenommen.

Measurements of process variations and particle morphology are widely employed in the pulp and paper industry. Two techniques with high potential, infrared thermography and microparticle characterisation, are mainly used qualitatively. Quantitative thermography requires knowledge of the emittance, a material property which has not been measured under many process-relevant conditions. Quantitative characterisation of microparticles, e.g. pulp fines and mineral fillers, requires the analysis of a large number of particles, which can be accomplished using flow microscopes. Flow microscopes for pulp analysis have had insufficient spatial resolution to resolve fines and fillers. Additionally, there has been a lack of methods which can differentiate between fines and fillers in a mixed suspension. State-of-the-art instruments for particle image analysis were evaluated and compared to laser diffractometry, a measurement method based on scattering by diffraction. Laser diffractometry was found to be highly sensitive to the complex refractive index of the particles, and especially to its change due to moisture absorption. A high-resolution imaging flow cytometer and a high-resolution fibre analyser were found to be complementary for characterisation of pure fines and fines/filler mixtures, and superior to laser diffractometry. A method for differentiating between fines and fillers in a suspension based on their autofluorescence and side-scattering was proposed and qualitatively evaluated. Furthermore, a method for measuring the directional and integrated emittance of paper was developed and its accuracy was determined. Measurements on a wide range of samples showed that the emittance of fibre-based materials vary significantly with wavelength, pulp type, observation angle, and moisture content. By applying measured quantitative values of the emittance, the thermal energy emitted by sack paper samples during mechanical deformation could be quantitatively calculated. The increase in thermal energy at the time of rupture was found to correlate well with the elastic share of the mechanical energy that was stored in the sample during its elongation. In summary, the results of this work have facilitated the use of quantitative microparticle analysis and infrared thermography for pulp and paper applications. / Mätningar av processvariationer och partiklars form och storlek utförs i stor skala inom massa- och pappersindustrin. Två mättekniker med stor potential, infraröd termografi och mikropartikel-karaktärisering, används mest kvalitativt idag. Kvantitativ termografi kräver att provets emittans är känd. Emittansen är en materialegenskap som inte har mätts för många förhållanden som är relevanta inom papperstillverkning. Kvantitativ karaktärisering av partiklar kräver att ett tillräckligt stort antal partiklar analyseras, något som kan göras med flödesmikroskop. Flödesmikroskop för mäldanalys har haft otillräcklig upplösning för att karaktärisera mikrometerstora partiklar, t.ex. fines och fyllmedel. Det har heller inte funnits någon metod som kan särskilja mellan fines och fyllmedel i en blandning. Högupplösta mätinstrument för bildbaserad mikropartikelkaraktärisering utvärderades och jämfördes med en laserdiffraktometer, en mätmetod baserad på ljusspridning genom diffraktion. Laserdiffraktometerns mätresultat påverkades starkt av det brytningsindex som antogs för provet, och hur brytningsindexet ändrades med fukthalt. En högupplöst bildbaserad flödescytometer och en högupplöst fibermätare konstaterades komplettera varandra vid mätningar av mäldens finmaterial. De var även pålitligare än laserdiffraktometern vid mätningar av organiskt finmaterial. En metod för att skilja mellan organiskt och oorganiskt finmaterial i en mäld baserat på deras autofluorescens och ljusspridning presenterades och utvärderades kvalitativt. En metod för att mäta den vinkelberoende och våglängdsintegrerade emittansen hos fiberbaserade material utvecklades och dess mätnoggrannhet utvärderades. Mätningar på ett stort antal prover visade att emittansen varierade betydligt med våglängd, mäldtyp, observationsvinkel, och fukthalt. Genom att använda den uppmätta emittansen kunde den termiska energin som frigjordes av ett säckpappersprov vid brottögonblicket beräknas. Denna energi korrelerade väl med den elastiska energi som lagrades i provet medan det töjdes, fram till tidpunkten för brottet. Sammanfattningsvis har resultaten av detta arbete möjliggjort kvantitativ användning av mikropartikel-karaktärisering och infraröd termografi i massa- och papperstillämpningar. / <p>QC 20160122</p>

Par rapport aux ressources énergétiques fossiles combustibles, l’énergie solaire présente des caractéristiques inhérentes à la nature même de la ressource. Ce constat met en évidence la nécessité de système de stockage d’énergie. Ce travail de thèse consiste à étudier un stockage thermique pour une centrale solaire à concentration, ainsi que ses deux composants essentiels : le fluide de transfert et les matériaux de garnissage solides. La compréhension du système de stockage thermocline sur lit de roche est réalisée grâce à une approche expérimentale et numérique. Une alternative innovante sur le choix du fluide de transfert consiste à utiliser des huiles végétales. Concernant le garnissage, un matériau à géométrie contrôlée est développé à partir d’un coproduit issu de la sidérurgie. L’originalité de cette association pour le stockage thermique permet d’allier performance, disponibilité des matériaux en quantité industrielle tout en réduisant l’impact environnemental et financier. / Compare to fossil fuel energy resources, solar energy presents the inherent characteristic given by the very nature of the resource (intermittent availability). This observation highlights the need for thermal energy storage system. This doctoral thesis studies thermal energy storage for concentrating solar power plant, as well as its two essential components: the heat transfer fluid and the thermal energy storage materials. The analysis of the thermocline storage system with filler materials is achieved through experimental and numerical approaches. An innovative alternative for the heat transfer fluid consists to use vegetable oils, which offers comparable thermal properties and operating behavior to conventional thermal fluid. Regarding thermal energy storage materials, many natural and recycled materials can be used. A storage material with controlled geometry is developed from steel industry co-product. The originality of this combination for thermal energy storage combines performance, materials availability at industrial scale while reducing environmental and financial impact.

L’odontologie conservatrice a connu une véritable révolution avec l’avènement de la dentisterie adhésive et le développement des résines composites associé au collage aux tissus dentaires. L’apparition il y a 20 ans des résines composites fluides a élargi encore les possibilités thérapeutiques des praticiens. La mise sur le marché d’un grand nombre de résines composites qui diffèrent par leur nature matricielle et par le type, la taille et la proportion des charges incorporées associée au manque d’informations des fabricants sur les compositions exactes de leurs produits empêchent les praticiens de réellement connaitre les caractéristiques des matériaux qu’ils utilisent. L’hyper-caractérisation in vitro desdits matériaux est une voie importante pour avancer dans la compréhension de leur comportement. Afin de juger de l’impact de la variation du taux de charges dans le comportement mécanique et physico-chimique des résines composites fluides, nous avons étudié deux groupes de matériaux : un premier groupe constitué de résines composites fluides expérimentales à matrice commune et à taux de charges variable et un deuxième groupe composé de résines composites fluides disponibles dans le commerce. Pour chacun de ces matériaux après la détermination du taux de charges par la méthode de la calcination, l’évaluation des caractéristiques rhéologiques (viscosité complexe et module de conservation), la mesure de la micro-dureté (micro-dureté Vickers), la contraction volumétrique de prise selon la méthode de la déflexion d’une lame de verre, l’analyse thermo-mécanique dynamique en flexion (module de conservation, module de perte, facteur d’amortissement) ainsi que les capacités d’absorption d’eau et de solubilisation (détermination par différentiel de gravimétrie après immersion dans différents milieux) sont autant de facteurs potentiellement influencés par ledit taux de charges qui ont été étudiés. Si le taux de charges devrait clairement faire partie des critères de choix du praticien tant il apparait influant sur les plans mécaniques et physico-chimiques, il apparait qu’un taux de charges élevé ne représente pas une garantie suffisante pour répondre de façon optimale au cahier des charges du matériau d’obturation idéal. L’emploi de résines composites fluides déformulées à taux de charges variable permet d’évaluer le rôle de la phase dispersée, pour autant, l’étude en parallèle de matériaux commerciaux met en lumière l’influence de la nature matricielle et des différentes entités monomériques entrant dans la structure polymère. / Conservative dentistry has undergone a genuine revolution, with the advent of adhesive dentistry and the development of resin composites combined with dental bonding. The emergence of flowable resin composites 20 years ago further expanded the treatment options open to dental practitioners. The appearance on the market of a large number of resin composites that differ in terms of their matrix type, along with the size and the proportion of the fillers incorporated, combined with a lack of information from manufacturers concerning the exact compositions of their products, means that practitioners do not really know all the characteristics of the materials they are using. In vitro hypercharacterization of these materials is an important approach to help us gain a better understanding of their properties. In order to assess the impact of variation of filler contents on the mechanical and physicochemical properties of flowable resin composites, we studied two groups of materials: a first group, composed of experimental flowable resin composites with the same matrix and a variable filler content, and a second group, composed of commercially available flowable resin composites. For each of these materials, after determination of the filler content using the calcination method, assessment of their rheological properties (complex viscosity and storage modulus), measurement of microhardness (Vickers microhardness), volumetric setting shrinkage using the glass slide deflection technique, dynamic thermo-mechanical analysis in flexure (storage modulus, loss modulus, damping factor), along with the water absorption and dissolution capacities (determination by thermal gravimetry differential following immersion in different media) are all factors potentially influenced by the said filler contents studied. While the filler content should clearly be one of the decision-making criteria used by practitioners given the influence it seems to have on both mechanical and physicochemical properties, it nonetheless appears that a high filler content is not, in itself, a sufficient guarantee that the material meets the optimum specifications for an ideal filling material. The use of deformulated flowable composite resins with a variable filler content makes it possible to assess the role of the dispersed phase. However, a parallel study of commercially available materials highlights the influence of the matrix type and the various monomeric entities included in the polymer structure.

Un nouveau procédé d’élaboration de CMC par voie liquide a été développé ; il met en œuvre l’utilisation de charges réactives afin d’obtenir un composite à bas coût. Afin de préserver le renfort en fibres Nicalon, ces charges doivent réagir sous azote à une température inférieure à 1100°C. Deux charges réactives répondant ces critères et présentant une prise de volume intéressante ont été identifiées : AlB2 et TiSi2.Le broyage planétaire de ces charges a été étudié afin d’évaluer l’influence de l’affinement de la microstructure sur les propriétés. Des poudres de surface spécifique élevée et de granulométrie proche l’échelle nanométrique ont été obtenues. La nitruration des charges a été analysée et un effet de taille a pu être mis en évidence sur la réactivité du TiSi2.Les poudres broyées ont été mises en suspension pour être imprégnées au sein de préformes. Les échantillons ont ensuite subi une étape de nitruration à 1100°C, cruciale pour la cohésion de la matrice. Un cycle PIP a ensuite été réalisé pour diminuer la porosité résiduelle.L’oxydation des matériaux obtenus a été étudiée dans des conditions correspondant à l’application aéronautique visée. Les propriétés mécaniques des composites élaborés ont été évaluées par des essais de flexion 3 points. La combinaison de l’utilisation de la charge réactive TiSi2 et d’un polysiloxane a permis d’obtenir un composite dont la contrainte à rupture est remarquable compte tenu du faible nombre d’étapes nécessaires à son élaboration par voie liquide. / A new CMC manufacturing process has been developped ; the active filler technique is used in order to obtain a low cost composite. Active fillers must react under nitrogen atmosphere at a temperature below 1100°C so that the Nicalon fiber reinforcement is not damaged. Two active fillers meeting these criteria and offering an interesting volume expansion have been identified : AlB2 et TiSi2.The planetary milling of these fillers has been explored in order to assess the influence of microstructure refinement on properties. Powders with high specific surface areas and of granulometry close to the nanometric scale were obtained. The nitridation of the active fillers was examined and a size effect on TiSi2 reactivity was displayed.Milled powders were used in colloidal suspensions in order to be impregnated in preforms. Samples were subsequently nitrided at 1100°C ; this step was crucial for matrix cohesion. A PIP cycle was eventually performed in order to reduce residual porosity.The oxydation behaviour of materials was studied in conditions corresponding to the considered aeronautics application. Mechanical properties of composites were estimated by 3 point bending tests. Combining the use of TiSi2 and of a polysiloxane enabled to obtain a composite whose maximum bending stress was remarkable considering the limited number of steps required for its processing.

Cement bonded particleboards contain organic base and as they are set outside, extreme weather condition, such as frost, chemical defrosting substances or sulphates, cause their degradation. The presence of the organic base in the matrix of the material could be the reason why there is higher probability of degrading when compared with materials containing an inorganic base. It could be partially eliminated by an appropriate surface modification of the slab, which main goal is to weaken the impact of an aggressive environment and to extend the lifespan of the board. On the other hand, the surface modifications based on a polymer base are prone to degrade because of other unfavourable conditions such as UV radiation when compared with the cement bonded particleboard. The classification of the surface modifications and the way of their degradation caused by the aggressive environment in real applications are presented in the theoretical part of the thesis. In the experimental part, appropriate methodical ways of testing the resistance of cement bonded particleboard’s coating system were chosen. Then, the testing and comparing of the physical, mechanical and aesthetic properties of different types of coatings were done. Moreover, a spectrophotometric analysis of the colour shade changes for the different aggressive environment were carried out. Furthermore, microstructures of chosen surface modifications were assessed by using an optical and an electron microscope.

The diploma thesis deals with the development of polymeric repair mortars in two qualitative levels ECONOMY and PREMIUM, designed especially for heavy engineering plants and the energy industry. In order to effectively withstand difficult industrial conditions, the developed materials should meet the highest requirements such as increased chemical and heat resistance, excellent adhesion to the concrete substrate, minimal shrinkage and other physical and mechanical properties. The PREMIUM level is aimed to achieve maximum physical and mechanical properties. Within the economy version, the emphasis is placed not only on very good properties, but also the possibility capability of reducing price of the resulting material. The partial aim of this work is the efficient use of secondary raw materials, mainly based on industrial waste in the form of fillers to the developed polymeric repair mortars.

This diploma thesis deals with welding of two dissimilar materials by laser. The samples were welded by direct beam guidance and wobbling, with and without using high alloy filler material and with the use of a diffusion barrier in the form of nickel. Welding was done with different shielding atmospheres. Nondestructive (VT, PT, UT-PA, RT) and destructive tests were performer (tensile test at room and elevated temperatures, microhrardness). Metalography was suplemented by EDX analysis of selected elements.

The identification of the hydrolysis and photodegradation products of flexible polyurethane foams (PUFs) with addition of biooriginated and biodegradable additive was the first topic of this dissertation work. Separation of polyurethane foam hydrolysis degradation products, designed for ecotoxicological tests, was managed by high-performance liquid chromatography coupled with mass spectrometry (HPLC/MS). The degradations product structure was elucidated by tandem mass spectrometry (MSn). PUF photodegradation products were obtained by exposure of materials by irradiation at 254 nm. Semi-volatile degradation products were isolated from the exposed polyurethane by n-hexane extraction; volatile compounds were collected by solid phase microextraction (SPME). Gas chromatography with mass spectrometry (GC/MS) and complete orthogonal tandem gas chromatography with mass spectrometry (GCxGC/TOF MS) was used for separation and identification of photodegradation products. The influence of the bio-filler on the character of degradation products and the possible effect of PUF degradation products on the environment was discussed at the end of this section. The determination of isoprostanes – markers of oxidative stress in tissues of beadlet anemone (Actinia equina) was the subject of the second topic. F2-isoprostanes were synthesized from the arachidonic acid. With thereby prepared isoprostanes the method of determination by liquid chromatography with tandem mass spectrometry (HPLC/MS/MS) was developed and optimized. The isoprostane isolation process from the Actinia equina tissues was optimized with solid phase extraction (SPE). The resulting methodology was used to quantify isoprostanes in tissues of anemones, which were exposed to both moderate and high temperature changes. The temperature changes were used to initiate the oxidative stress in organisms. In addition, concentration levels of unknown compounds were also monitored. These unknown compounds were extracted from tissues together with F2-isoprostanes and their identity is discussed in this dissertation work too. The possibility of using isoprostane levels in the Anthozoa tissues for the oxidative stress monitoring is discussed in the conclusion of this work.

The diploma thesis is focused on the behaviour of natural and synthetic aggregates and their behaviour in polymer – cement composites, while being exposed to high temperature. The processes, happening in aggregates and mortar under the thermal load, were described in the theoretical part of the thesis same as the testing of heat effects on the aggregates and mortar. Further, the influence of high temperature on each component of concrete was described, followed by the suggestion of the appropriate components for concrete exposed to high temperature. Various aggregates were tested in the experimental part of the thesis. The basic physical and mechanical properties of aggregates were examined same as their mineralogical composition with using XRD, DTA and SEM methods. At the mortar, the influence of high temperature on the concrete density, compressive strength and tensile strength was defined. The gained knowledge was evaluated in the final part of the thesis