Les matériaux réfractaires non façonnés dense (MRNF) prennent une part de plus en plus importante aussi bien en cimenterie, fonderie, sidérurgie, ... Principalement constitués d’agrégats à base d’alumine, de magnésie, de spinelle, … ils constituent des matériaux de faible perméabilité contenant une teneur résiduelle en eau de 4 à 6 %. Leur séchage avant leur première utilisation est une opération critique qui conditionne leur durée de vie. D’une part, mal conduit, il peut du fait des endommagements occasionnés, réduire considérablement la durée de vie des installations. D’autre part, certaines conditions de séchage conduisent à une véritable destruction de nature explosive du matériau correspondant à une élévation brutale de la pression interne (accompagnant l’élévation de la pression de vapeur saturante de l’eau avec la température). Le travail a permis de se familiariser avec les matériaux réfractaires non-façonnés à l’aide d’une caractérisation thermomécanique complète menée entre la température ambiante et 500 °C, de comprendre les mécanismes mis en jeu lors de leur séchage, d’une part, par une expérimentation et, d’autre part, en les reproduisant en s’appuyant sur un transfert simultané de chaleur et de masse en milieu poreux. Et enfin, il a permis d’étudier l’impact d’un ajout de fibres polymère sur une caractéristique qui gère l’évacuation de l’eau, la perméabilité, et plus généralement sur le séchage / Castable refractories take a more and more important place in various industries: cement factory, casting, iron and steel making. They consist mainly of aggregates of high-alumina and ultra-low cement. Their permeability is very low and they contain before the first heat-up a residual water content of 4 to 6 % (dry basis). Drying during the first heat-up is a crucial step which sharply influence the refractory in-service performances. On one hand, damaging can occur, and as a consequence will reduce drastically the life time of the plants. On the other hand, particular drying conditions can lead to an explosive spalling of the refractory corresponding to an internal gas pressure steep raise linked to the water saturated vapour pressure raise with temperature. First, a complete thermomechanical characterization between ambient temperature and 500 °C of the unshaped refractory materials has been conducted. Then the mechanisms involved during their drying, on one hand, by an experiment and, on the other hand, by using a simultaneous heat and mass transfer model in porous media have been studied. And last, the impact of adding polymer fibers has been analysed both on the concrete permeability as well as their influence on drying

A ceramic vortex finder (CVF) is the central pipe (gas outlet) of a gas cyclone, which is an important structural component within gas cyclone separation. Its main application is within high temperature processes, within the energy and cement industry where the atmosphere is highly abrasive and corrosive. The CVF has the purpose of inducing well-defined flow field resulting in optimal performance of the cyclone.  Ceramics and refractories are superior when it comes to high temperature stability, resistance against chemical attacks along with abrasion resistance. The aim for a longer lifetime of the CVF creates an importance of further investigation into factors influencing the strength of the material. Fracture toughness is an important parameter to focus on in the CVF application. This is because it’s known that fracture is the major cause of failure for brittle materials. This creates an interest into further investigation of the parameters influencing the casting process including water addition and porosity.  This project work aimed to investigate the impact of water addition on the CVF material. The focus was on identifying how much the casting process influenced the fracture toughness. The results showed that 4.5% water addition is the best amount to use for the CVF application. This water amount gave the minimum porosity with the highest fracture toughness. The water amount ensured a good flowability of the castable along with a curing time above 50 minutes, making it possible to cast in the production.

Made available in DSpace on 2014-12-17T14:58:22Z (GMT). No. of bitstreams: 1 JoaoAAB_DISSERT.pdf: 2621016 bytes, checksum: 39aa654f0df748b1db86062c61ed8f35 (MD5) Previous issue date: 2013-05-16 / Emerald mining is an important area of the economy in Brazil, country which is in second place among the exporting nations of this gem. Due to the process of extraction, a great amount of reject is generated. Since there is no appropriate destination, the reject is abandoned around the mining industries, contributing to environment degradation. Nowadays, some of the most relevant things to an industry in general are: energy conservation, cost reduction, quality and productivity enhancement. The production of isolating, transformed refractory materials achieves the sustainability dimension when protection of the environment is incorporated to such process. This work investigates the use of emerald mining rejects in the ceramic body of refractory materials, aiming at obtaining a product whose characteristics are compatible with commercial products and, at the same time, allow the use of such rejects to solve the environmental issue caused by its disposal in nature. X-ray fluorescence analysis show that the emerald reject obtained after the flotation to extract molybdenum and mica has 70% of silica and alumina (SiO2+Al2O3) and 21% of a basic oxides and alkaline metals and earthy alkaline mixture (Na2O, K2O, CaO e MgO). Because of the significant amount of silica and alumina present in the reject, four refractory ceramic bodies were prepared. Samples with a rectangular shape and dimensions 100x50x10 mm were pressed in a steel mold at 27,5 MPa and sintered at 1200?C for 40 min. under environment atmosphere in a resistive oven. The sintered samples were characterized in relation to the chemical composition (FRX), mineralogical composition (DRX), microstructure (MEV) and physical and mechanical properties. The results indicate that the mixture with 45% of reject, 45% of alumina and 10% of kaolin presents a refractory quality of 1420?C, dimensional linear variation below 2.00%, apparent specific mass of 1,56 g/cm3 and porosity of 46,68%, which demonstrates the potential use of the reject as raw material for the industry of isolating transformed refractory materials / A minera??o de esmeraldas ? uma importante ?rea da atividade econ?mica do Brasil, pa?s que ocupa o segundo lugar entre as na??es exportadoras dessa gema. Em virtude do processo de extra??o, uma grande quantidade de rejeito ? gerada. Como n?o h? uma destina??o apropriada, o rejeito ? abandonado ao redor das mineradoras, contribuindo, assim, para a degrada??o do meio ambiente. Atualmente, alguns dos pontos de maior relev?ncia para a ind?stria em geral s?o: conserva??o de energia, redu??o de custos, melhoria de qualidade e produtividade. A produ??o de refrat?rios conformados isolantes ganha a dimens?o de sustentabilidade quando a prote??o ao meio ambiente ? incorporada a tal processo. Este trabalho investiga o uso de rejeitos da minera??o de esmeraldas na massa cer?mica de materiais refrat?rios, com intuito de obter um produto com caracter?sticas compat?veis aos produtos comerciais e, ao mesmo tempo, viabilizar a utiliza??o de tais rejeitos para solucionar o problema ambiental gerado por seu descarte na natureza. An?lises de fluoresc?ncia de raios x mostram que o rejeito de esmeraldas obtido ap?s a flota??o para retirada de molibd?nio e mica possui 70% de s?lica e alumina (SiO2+Al2O3) e 21% de uma mistura de ?xidos b?sicos de metais alcalinos e alcalinos terrosos (Na2O, K2O, CaO e MgO). Em fun??o dos significativos teores de s?lica e de alumina presentes no rejeito, quatro massas cer?micas refrat?rias foram preparadas. Corpos de prova com forma retangular e dimens?es 100x50x10 mm foram prensados em uma matriz de a?o a 27,5 MPa e sinterizados a 1200?C por 40 min. sob atmosfera ambiente em forno resistivo. Os corpos de prova sinterizados foram caracterizados com rela??o ? composi??o qu?mica (FRX), composi??o mineral?gica (DRX), microestrutura (MEV) e propriedades f?sicas e mec?nicas. Os resultados obtidos indicam que a mistura com 45% de rejeito, 45% de alumina e 10% de caulim apresenta uma refratariedade de 1420?C, varia??o linear dimensional inferior a 2,00%, densidade de massa aparente de 1,56 g/cm3 e porosidade total de 46,68%. Isto demonstra que o rejeito possui um potencial como mat?ria-prima para aplica??o na ind?stria de materiais refrat?rios conformados isolante

In this diploma thesis was analysed layer of corroded material created on refractory lining of reactors for mazut gasification. Samples of corroded material were analysed for SiO2, Al2O3, ZrO2, Fe2O3 a TiO2. Corroded material was further analysed by x-ray and IR spectroscopy to acquire more precise data about chemical composition. This thesis studies the exact effect of microstructure on static corrosion kinetics in system SiO2-Al2O3.

Thermal insulating refractories are an integral part of each thermal unit since they reduce its energy consumption. The current phenomenon of saving in both environmental and financial aspects reflects in searching for such possibilities to produce at lower manufacturing and material costs. One of the possible ways is to valorise waste materials. The theoretical part then deals with the division of refractory materials, classification of thermal insulation refractory materials and manufacturing technologies. The experiment is focused on the production of insulating refractory materials made from plastic dough with a possibility of using sawdust and materials made by pressing mixture moist, with a focus on coal bottom ash. Both of these technologies will be tested for the possibility of modification by using mixed clays and of increasing the strength by using clays with lower sintering temperature.

Die Arbeit führt Methoden zur Durchführung von Zugversuchen und bruchmechanischen Versu-chen ein und liefert mechanische Kennwerte für zwei kohlenstoffgebundene FFW im Bereich von RT bis 1500°C. Dafür standen ein grobkörniges MgO-C und ein feinkörniges Al2O3-C zur Ver-fügung. Die Werkstoffe zeigten bis 1200°C keine Duktilität und sprachen spröde. Die Schädigung erfolgte ausschließlich durch Risswachstum. Dieses fand beim MgO-C temperaturunabhängig auf Grund der rissbehafteten Mikrostruktur durch stabiles Risswachstum bereits vorhandener Risse statt. Es kam dabei zur Bildung von Rissnetzwerken sowie zu zahlreichen energiedissipierenden Prozessen. Beim Al2O3-C trat be RT instabiles Risswachstum auf. Bei hohen Temperaturen kam es durch thermisch aktivierte Prozesse zu duktilem Verhalten und stabilem Risswachstum. Beim grobkörnigen MgO-C wurden große Verformungen durch das starre Oxidgerüst verhindert. Zu-sätzlich zeigten die Werkstoffe auf Grund ihrer Mikrostruktur eine Zunahme der Festigkeit mit steigender Temperatur. Aus den Versuchen wurde ein Heißpressverfahren zur Herstellung von gradierten Werkstoffen abgeleitet.:1 Einleitung 2 Grundlagen 2.1 Feuerfestwerkstoffe 2.1.1 Einsatz und Beanspruchung von FFW 2.1.2 Einteilung von FFW 2.2 Kohlenstoffgebundene FFW 2.2.1 Kohlenstoff und seine Terminologie 2.2.2 Grundlegende Eigenschaften kohlenstoffgebundener FFW 2.2.3 Anwendungen kohlenstoffgebundener FFW 2.2.4 Aufbau und Mikrostruktur kohlenstoffgebundener FFW 2.2.5 Herstellungsparameter kohlenstoffgebundener FFW 2.2.6 Chemische Eigenschaften kohlenstoffgebundener FFW 2.3 Mechanische Eigenschaften kohlenstoffgebundener FFW 2.3.1 Mechanische Eigenschaften kohlenstoffgebundener FFW bei RT 2.3.2 Mechanische Eigenschaften kohlenstoffgebundener FFW bei HT 2.4 Grundlagen zur Werkstoffprüfung bei RT und hohen Temperaturen 2.4.1 Streuung und Einfluss der Probengröße 2.4.2 Belastungsrate 2.4.3 Zugversuche 2.4.4 Druckversuche 2.4.5 Biegeversuche 2.4.6 Bruchmechanische Untersuchungen 2.4.7 Temperaturwechselbeständigkeit 2.4.8 Kriechen 2.4.9 Spannungsrelaxation 2.4.10 Härtemessung 2.4.11 Hochtemperaturprüfung in Kaltkammerofen mit induktiver Heizung 2.4.12 Temperaturmessung mit Thermoelement, Pyrometrie, Thermographie 2.4.13 Bestimmung elastischer Konstanten mittels akustischer Methoden 2.4.14 Optische in situ Schadensbeschreibung mittels Mikroskopie und DIC 2.5 Heißpressverfahren 3 Experimentelles 3.1 Werkstoffe 3.1.1 Kohlenstoffgebundenes Magnesiumoxid (MgO-C) 3.1.2 Kohlenstoffgebundenes Aluminiumoxid (Al2O3-C) 3.1.3 Graphit (ISEM 8) 3.2 Mechanische Tests 3.2.1 Prüfmaschine für Druck- und Biegeversuche 3.2.2 Prüfmaschine für Zug-Druck-Versuche 3.2.3 Probengeometrien 3.2.4 Druckversuche 3.2.5 Biegeversuche 3.2.6 Bruchmechanische Versuche 3.2.7 Versuche mit Zugbeanspruchung 3.2.8 Versuchsabläufe der Hochtemperaturversuche 3.2.9 Temperaturmessung mittels Thermographie 3.3 Weitere Versuchsmethoden 3.3.1 Mikrostrukturuntersuchung mittels Mikroskopie und Röntgenbeugung 3.3.2 Porositäts- und Dichtemessung 3.3.3 Härtemessung 3.3.4 Dynamischer E-Modul 4 Methodische Erkenntnisse und Voruntersuchungen 4.1 Temperaturmessung und -verteilung 4.1.1 Temperaturmessung mittels Thermoelement und Pyrometer 4.1.2 Emissionskoeffizient und Probenbeschichtung 4.1.3 Temperaturverteilung 4.2 Dehnungsmessung 4.3 Zugversuche an Keramiken 4.3.1 Übertragung von Zugkräften 4.3.2 Axialität in Zugversuchen 4.4 Bruchmechanische Versuche 4.4.1 Kerbeinbringung 4.4.2 Überprüfung des optischen Messsystems 4.4.3 Bestimmung der Risslänge während des Versuchs 4.5 Überprüfung der Messmethodik mit dem Referenzwerkstoff Graphit ISEM-8 5 Ergebnisse 5.1 Mikrostrukturbeschreibung der untersuchten FFW 5.1.1 Mikrostruktur des MgO-C’s 5.1.2 Mikrostruktur des Al2O3-C’s 5.2 Mechanisches Verhalten bei RT 5.2.1 Mechanisches Verhalten von MgO-C bei RT 5.2.2 Mechanisches Verhalten von Al2O3-C bei RT 5.3 Mechanische Eigenschaften bei HT 5.3.1 Mechanisches Verhalten von MgO-C bei HT 5.3.2 Mechanisches Verhalten von Al2O3-C bei HT 5.4 Heißpressverfahren für kohlenstoffgebundene FFW 5.4.1 Beschreibung des Heißpressverfahrens 5.4.2 Physikalische Eigenschaften und Mikrostruktur des Presslings 5.4.3 Mechanische Eigenschaften des Presslings 6 Diskussion 7 Zusammenfassung und Ausblick Literatur Anhang

The master´s thesis focuses on high-alumina refractory materials used mainly in aluminia metallurgy. Teoretical part of this thesis is aimed at distribution of refractory materials, possibilities of its production and raw material basis. Characteristic properties are described as well as application possibilities in aluminium technology. In final part of this thesis experimental data are evaluated to obtain physical, mechanical, chemical properties of high-alumina refractory materials. Those are used for economical optimalization of raw materials.