Le ciment est la principale source des impacts sur l’environnement de l’utilisation du matériau béton. Afin d’optimiser ce dernier d’un point de vue environnemental, il est nécessaire de réduire son dosage en ciment. Cela peut être entrepris en remplaçant une partie du ciment par des additions minérales lors de sa fabrication.Ces travaux de thèse visent à étudier les phénomènes physico-chimiques ayant lieu lors du processus de carbonatation de bétons à forts taux de remplacement du ciment par des additions minérales ainsi que leur résistance à ce type d’attaque.Une campagne expérimentale a été menée sur des bétons de référence préparés à base de ciments courants et sur des Écobétons préparés en substituant une partie du ciment par des cendres volantes ou du laitier de haut-fourneau. Les différentes études menées portent sur la durabilité des Écobétons vis-à-vis de la carbonatation, sur l’équivalence de performances des Écobétons avec celles des bétons de référence, et sur les paramètres de composition et de microstructure contrôlant la cinétique de carbonatation. La carbonatation a été étudiée en conditions accélérées et naturelles. Les résultats montrent que les Écobétons à forts taux de substitution du ciment par des cendres (50 %) ou du laitier (75 %) pourraient remplacer, dans certains cas, les bétons conformes à la norme en vigueur.En complément à l’étude expérimentale, des simulations numériques du couplage hydratation/séchage ont été menées en vue de déterminer l’effet du séchage sur les propriétés contrôlant la cinétique de carbonatation accélérée des bétons étudiés (la porosité, la quantité de Portlandite et le degré de saturation en eau liquide). Les résultats montrent que la cinétique de séchage augmente avec le taux de substitution du ciment par des additions. Ils remettent aussi en cause la pertinence du préconditionnement des échantillons lors de l’essai de carbonatation accélérée mené selon la norme française XP P 18-458 actuellement en vigueur. / Cement is the main source of environmental impacts of concrete use. It is thus recognized that the most pragmatic solution for minimizing environmental impacts of concrete is the reduction of the cement content. This could be achieved by replacing a part of cement by mineral additions such as fly ash or blast-furnace slag during concrete mixing.The present work aims at studying the physico-chemical phenomena occurring during the process of carbonation of concrete mixtures with high substitution rates of cement by mineral additions and their resistance against this type of attack.An experimental campaign was conducted on reference concrete mixtures prepared with common cements and on other concrete mixtures, called “Écobétons” (Green concretes), prepared by replacing a part of cement by fly ash or blast-furnace slag. The study focused on the Écobétons durability, especially their resistance against carbonation, on the equivalence of Écobétons performances with the reference mixtures performances and on the composition and microstructure parameters controlling the kinetics of carbonation. Carbonation has been studied in natural and accelerated conditions. The results show that Écobétons mixtures with high substitution rates of cement by fly ash (50 %) and blast-furnace slag (75 %) could replace, in some cases, concretes that are in accordance with the current standard.In addition to the experimental study, numerical simulations of the coupling between hydration and drying were conducted in order to determine the effect of drying on the properties controlling the accelerated carbonation kinetics of the studied concrete mixtures (porosity, Portlandite content and water saturation degree). The results show that the kinetics of drying increases with the degree of substitution of cement by mineral additions. They also question the relevance of the preconditioning of the samples during accelerated carbonation test conducted according to the French standard XP P 18-458.

Made available in DSpace on 2016-12-23T14:07:27Z (GMT). No. of bitstreams: 1 Dissertacao de Dirceu Soares Junior Parte 1.pdf: 2325132 bytes, checksum: 944653981d05fdcc1c69ff97b342de4f (MD5) Previous issue date: 2011-09-22 / Uma planta siderúrgica caracteriza-se pela existência em seu processo produtivo de cargas não lineares de elevada potência. Dentre estas cargas, as siderúrgicas do tipo mini-mill possuem normalmente Forno Elétrico a Arco (FEA) na sua fase inicial de produção do aço, que ocorre a partir da fusão de sucatas metálicas como principal matéria-prima utilizada. Os fornos elétricos absorvem uma corrente distorcida da rede elétrica, causando assim uma distorção de tensão no ponto de acoplamento comum (PAC) e inúmeros problemas de qualidade de energia elétrica. Uma solução muito utilizada para a mitigação harmônica neste tipo de carga elétrica é obtida através do uso de filtros passivos, com vários estágios de filtragem. Porém esta é uma solução que pode levar ao efeito da ressonância harmônica, elevando com isto a distorção harmônica no sistema elétrico e causando sobrecarga no sistema de filtragem. Neste trabalho é apresentado um estudo de caso em uma siderúrgica não integrada (siderúrgica que possui sucata metálica e ferro gusa como matérias-primas principais na fabricação do aço), localizada na região da Grande Vitória. Por meio de medições na subestação principal da usina, são apresentadas as principais formas de onda das correntes e tensões, em conjunto com seus espectros harmônicos, que comprovam a existência de distorções harmônicas, sobretudo provenientes da corrente do forno elétrico a arco. As medições consideradas no trabalho, para simulação dos modelos contendo os filtros híbridos, foram aquelas originadas da condição operacional mais crítica do processo, sob o ponto de vista de momento onde o comportamento da carga acarreta o maior desvio quanto à qualidade de energia nas variáveis elétricas medidas. O modelo utilizado para o sistema em questão apresenta forte grau de correlação com o sistema real, retratado através das medições elétricas efetuadas. De posse do modelo é realizada uma análise comparativa por meio de simulação entre duas topologias de filtragem híbrida, o filtro híbrido série e o filtro híbrido paralelo, para a compensação harmônica e amortecimento da ressonância. Os resultados das simulações e das análises das ressonâncias mostraram que o filtro híbrido paralelo é a topologia que permite a maior redução das distorções harmônicas de corrente e de tensão no PAC, utilizando-se um filtro ativo com a menor potência nominal. Contudo, a filtragem híbrida paralela não provê a eliminação por completo da ressonância paralela. E, quanto à ressonância série, o filtro utilizado não possui a capacidade de interferir na condição de amplificação harmônica existente no sistema elétrico. Finalmente, o estudo propõe que a definição da melhor alternativa de filtragem leve em consideração a escolha do ganho do filtro ativo e, consequentemente, a sua potência, de forma bem alinhada aos objetivos de melhoria na qualidade de energia elétrica que são esperados para o sistema em questão / A steelmaking plant is characterized for having in its productive process non linear loads of high power. For these loads, the steelmaking industries called mini-mill normally have Electric Arc Furnace (EAF) in its initial steel production phase that happen with metallic scrap melting being the principal raw material used. The EAF absorb a distorted current from the electric main, causing voltage distortion in its point of common coupling (PCC) and many problems with respects the electric power quality. A standard solution used for the harmonic mitigation in this application is obtained through the use of composite passive filter. However this is a solution that can cause harmonic resonance, increasing the harmonic distortion in the electrical system and causing overload in the filtering system. In this work, a case in a non integrated steel industry, located at Grande Vitoria region, is presented. Through measurements in the main substation of the plant, the main current and voltage waveforms are presented, along with its harmonic spectrum, that confirm the existence of harmonic resonance phenomenon, mainly from Electric Arc Furnace current. The measurement considered in this work to simulate the hybrid filters models, was that originated from operational condition with higher process criticism, under viewpoint of the moment where the behavior of the load brings to a major deviation regarding the power quality at the measured variables. The model used for the system under study shows strong correlation with the real system portrayed through the electrical measurements done. Using the model, a comparative simulation analysis is done, between two hybrid topologies, the series hybrid filter and the parallel hybrid filter, with the objective of harmonic compensation and resonance damping. The results of simulations and resonance analysis showed that the parallel hybrid filter is the topology that allows the greatest reduction in harmonic distortion of current and voltage in the PCC (Point of Common Coupling), using an active filter with the lowest nominal power rating. However, the parallel hybrid filtering does not provide the complete elimination of parallel resonance, and for the series resonance, the filter used does not have the ability to interfere in the harmonic amplification condition existing in the electrical system. Finally, the study proposes that the best filtering alternative takes into account the choice of the active filter gain and consequently its power, so well aligned with the objectives of improving the power quality that are expected for the system under analysis

The aim of this study was to assess the strength, durability properties and corrosion resistance of concrete samples using supplementary cementitious blended materials. In this investigation, three supplementary concrete materials (SCMs) were used together with ordinary Portland Cement (OPC) to form cementitious blends at different proportions. The supplementary materials are silica fume (SF), ground granulated blast furnace slag (GGBS) and fly ash (FA). Sixteen (16) different proportions of the cementitious blends were produced. Tests carried out on concrete samples include slump test, compressive strength, oxygen permeability, sorptivity, porosity, chloride conductivity test, resistance to chloride and sulphate attack. The electrode potentials of tested samples were also observed using electrochemical measurements. Concrete specimens prepared with 10%, 20%, 30%, 40%, up to 60% of blended cements replacement levels were evaluated for their compressive strength at, 7, 14, 28, 90 and 120 days while the specimens were evaluated for durability tests at 28, and 90 days respectively. The results were compared with ordinary Portland cement concrete without blended cement. Voltage, and temperature measurements were also carried out to understand the quality of concrete. The corrosion performance of steel in reinforced concrete was studied and evaluated by electrochemical half-cell potential technique in both sodium chloride, and magnesium sulphate solutions respectively. The reinforced concrete specimens with centrally embedded 12mm steel bar were exposed to chloride and sulphate solutions with the 0.5 M NaCl and MgSO4 concentrations respectively. An impressed voltage technique was carried out to evaluate the corrosion resistance of the combination of quaternary cementitious blended cement, so as to get the combination with optimum performance. Improvement of strength, durability, and corrosion resistance properties of blended concrete samples are observed at different optimum percentages for binary, ternary and quaternary samples. The effect of cementitious blends is recognized in limiting the corrosion potential of the tested SCM concrete samples. Generally, the cementitious blends with limited quantity of SF to 10% have the potential to produce satisfactory concrete. These should however be used for low cost construction, where high quality concrete is not required. / Civil and Chemical Engineering / M. Tech. (Chemical Engineering)

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-12-22T12:03:13Z No. of bitstreams: 1 Josué Claudio Metz_.pdf: 3580473 bytes, checksum: 4bb7f81d4d0a95ef4e39a7d4dffb0599 (MD5) / Made available in DSpace on 2016-12-22T12:03:13Z (GMT). No. of bitstreams: 1 Josué Claudio Metz_.pdf: 3580473 bytes, checksum: 4bb7f81d4d0a95ef4e39a7d4dffb0599 (MD5) Previous issue date: 2016-09-19 / Nenhuma / A concepção de desenvolvimento sustentável tem resultado no aumento de pressões ambientais para a melhoria da eficiência na utilização de recursos, e para a redução das emissões e da geração de resíduos. No processo de fabricação de aço, nas siderúrgicas com fornos elétricos a arco (FEA), ocorre a geração do resíduo sólido denominado pó de aciaria elétrica (PAE). O PAE é constituído por diferentes óxidos metálicos. Contém os elementos químicos cromo (Cr), chumbo (Pb) e cádmio (Cd) e, por isso, é classificado como resíduo classe I – Perigoso pela NBR 10004. Gerado em grandes quantidades diariamente em todo o país, o PAE ainda tem como principal destinação final o aterro industrial. A indústria de papel e celulose, outra atividade de destaque na indústria nacional, gera uma grande quantidade de resíduos em diferentes etapas do processo, entre os quais está o resíduo do forno de cal (RFC), cuja geração está associada a interrupções no funcionamento do forno de cal. A indústria da construção civil, devido a quantidade de matérias-primas consumida e variedade de materiais empregados – cimento, concreto, agregados, cerâmica, entre outros – apresenta-se como alternativa para a reciclagem de resíduos gerados em outros setores da economia. A incorporação do PAE no cimento e concreto produz retardo no tempo de pega em razão da presença de zinco (Zn) no resíduo. Estudos sugerem que em quantidades próximas a 1%, a incorporação de PAE não afeta de forma significativa as propriedades do cimento. O objetivo deste trabalho foi avaliar a influência do uso combinado de PAE e RFC no processo de endurecimento e evolução da hidratação de pastas de cimento. Para tanto, foi realizada a caracterização dos resíduos através dos ensaios de distribuição granulométrica, perda ao fogo, massa específica, área superficial específica, análise química elementar, difração de raios X com refinamento por Rietveld e microscopia eletrônica de varredura. A influência dos resíduos nas pastas de cimento foi avaliada através do ensaio de tempo de pega de acordo com a NBR NM 65 (ABNT, 2003b) e evolução da temperatura semi-adiabática das pastas em estado fresco, além de DRX, com refinamento por Rietveld, e microscopia eletrônica de varredura nas pastas de cimento com diferentes teores de substituição de resíduos (REF, 1%, 2%, 3%, 5% e 10%) em diferentes idades (1, 4 e 7 dias). Os resultados de tempo de pega e evolução da temperatura semi-adiabática indicaram a influência do PAE na hidratação das pastas de cimento. Nas pastas de cimento com substituição de 1% de PAE combinado ou não com RFC, não foram verificados retardos significativos no tempo de pega, demonstrando o potencial do uso de PAE e do RFC na produção de artefatos de cimento. / The sustainable development conception has resulted in increased environmental pressures to improve the efficient use of resources and reduction of emissions and waste generation. In the steelmaking process through electric arc furnaces (EAF), dust generation occurs which is called electric arc furnace dust (EAFD). EAFD is composed by different metal oxides. Some common elements those constitute this dust is chromium, lead and cadmium, and therefore, waste is classified as class I – hazardous by NBR 10004. EAFD has been generated in large quantities every day across the country and it still has mainly landfilled. The pulp and paper industry, another important activity in the domestic industry, generates a lot of waste in different stages of the process, among which is the lime kiln waste (LKW), whose generation is associated with disruptions in the lime oven. Due to expressive amount of raw materials consumed in civil construction industry and also the variety of products available - cement, concrete, aggregates, ceramics, among others - this seems to be an alternative for waste recycling generated in other sectors. The incorporation of EAFD in the cement and concrete produces delayed setting time due to the presence of zinc (Zn) in the waste. Studies suggest that in amounts up to 1%, EAFD incorporation does not affect significantly cement properties. The aim of this work was to evaluate the influence of the combined use of EAFD and LKW in the process of hardening and evolution of the cement pastes hydration. Therefore, were evaluated the characterization of the waste performed through the grain size distribution, loss on ignition, specific gravity, specific surface area, elemental chemical analysis, pH, X ray powder diffraction with refinement by Rietveld and scanning electron microscopy.. The influence of the waste on the cement pastes was evaluated through the setting time tests in accordance with the NBR NM 65 (ABNT, 2003b) and evolution of semi-adiabatic temperature in fresh conditions, XRD with refinement by Rietveld, and SEM in cement pastes with different levels of waste substitution (REF, 1%, 2%, 3%, 5% e 10%) at different ages (1, 4 and 7 days). The setting time results and evolution of semi-adiabatic temperature indicated an increase in the setting time with the increase of the EAFD in cement pastes. In cement pastes with replacement of 1% EAFD combined or not with LKW, significant delays were not verified in the setting time, demonstrating the potential use of EAFD in the production of cement artifacts.

Gas, liquid and powder flow in the lower part of a blast furnace is complex phenomena. In order to understand the aerodynamics of the blast furnace properly, these phenomena must be included in their advanced form. Previous studies have shown that the conditions of blast furnace resemble the cold model experiments which have been done in decreasing gas velocities. Also, the recent studies have shown that liquid flow in a blast furnace can be represented more realistically considering it discrete in nature. In the current study, both the phenomena have been considered along with the injection of powder through a nozzle while studying the fluid flow behaviour in a packed bed. The situation resembles the lower part of an ironmaking blast furnace. In this study, gas flow has been modelled using k-ε turbulent model and has been coupled with previously developed stress model to calculate the raceway size. Coal powder is treated as continuum and has been modelled in the similar way as gas flow. After this gas and powder flow model were coupled with previously developed discrete liquid flow model. Liquid flow model has been considered for structured bed only. The governing equations for gas phase were discretized. Finite Volume method was used for the solution. Co-located grid is used for the simulation. Blending of upwind difference scheme and central difference scheme (deferred correction approach) is used to achieve the stability of upwind scheme and accuracy of central difference scheme. Similar treatment was employed for powder phase. For the solution of volume fraction of powder, powder phase continuity equation was used along with pseudo time step scheme. Results obtained from gas and powder models have been validated against published experimental data. Similarly, gas-liquid flow results have been validated against published experimental data on gas-powder flow. Results obtained by gas-powder-liquid model could not be validated against any experimental or theoretical data as they are not available in the literature. The effect of various parameters on the fluid flow (gas/liquid/powder) behaviour have been studied like the effect of increasing and decreasing gas velocities, flow rates of liquid, gas and powder, size of powder and packing etc. It is found that the above mentioned phenomena have significant effect on the fluid flow behaviour in a packed bed.

No description available.

Η επεξεργασία των νικελιούχων λατεριτικών μεταλλευμάτων της χώρας μας για την παραγωγή σιδηρονικέλιου στη Λάρυμνα συνοδεύεται με την εκπομπή 200000t/y λεπτομερούς σκόνης που συλλέγεται στα συστήματα αντιρρύπανσης των περιστροφικών κάμινων (Π/Κ), μέσης περιεκτικότητας 1.2-1.5% σε Ni και 4-5% σε C. Η διατριβή αυτή συνέβαλε στην ανάπτυξη μεθόδου ανακύκλωσης της σκόνης αυτής με απευθείας αναγωγική της τήξη σε ηλεκτρική κάμινο συννεχούς ρεύματος (DC-HEP) με εμφυσησή της μέσω του κεντρικού διάτρητου γραφιτικού ηλκετρόδιου. Την προκαταρκτική θεωρητική διερεύνηση και τις εργαστηριακές προδοκιμές ακολούθησαν βιομηχανικές δοκιμές στην κάμινο 125t DC-HEP στη χαλυβουργία Georgsmarienhutte της Γερμανίας, όπου έλαβε χώρα τήξη 70t σκόνης και 2.5t φιλομερούς μεταλλεύματος.Η ανάκτηση Ni ήταν πολύ υψηλή 93-99%. Παρήχθησαν χάλυβες χαμηλής κραμάτωσης σε σε Ni καθώς και ποικίλοι τύποι σκωρίας προς διερεύνηση της χρήσης τους στην παραγωγή σύνθετων τσιμέντων Portland και σκωριωτσιμέντων. Πραγματοποιήθηκε μεταλλουργική αξιολόγηση των δοκιμών και αναπτύχθηκε μοντέλο προσομοίωσης της αναγωγικής τήξης της σκόνης. / The tratment of the laterite nickel ferrous ores in Hellas for the production of ferronickel at Larymna is associated with the emission of 200000t/y of fine dust collected in the gas cleaning systems of the rotary kilns (R/Ks), with 1.2-1.5% and 4-5% . Average Ni and C contents respectively . This thesis contributed to the development of a method for the recycling of this dust by means of its direct reduction smelting in a DC-HEP furnace (Direct Current-Hollow Electrode Powder) by its injection through the central hollow graphite electrode. The preliminary theoretical study and the laboratory trials were followed by industrial heat campaigns in the 12st DC-HEP furnace at georgsmarienhutte steelwork in Germany, where around 70t of dust and 2.5t of ore fines were smelted. The Ni-recovery was very high 93-99.9%. Low Nickel alloyed steel grades were produced and various slag types for the investigation of their utilization for the production of composite-portland cements and slag cements. The metallurgical evaluation of the trials was performed and model for the dust reduction smelting process was developed.

名古屋大学年代測定総合研究センターシンポジウム報告

Submitted by Maike Costa (maiksebas@gmail.com) on 2016-05-16T13:29:45Z No. of bitstreams: 1 arquivo total.pdf: 3062751 bytes, checksum: 5355db4f5e8fd0c5ecd86a23e5d0ad77 (MD5) / Made available in DSpace on 2016-05-16T13:29:45Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 3062751 bytes, checksum: 5355db4f5e8fd0c5ecd86a23e5d0ad77 (MD5) Previous issue date: 2016-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The single-phase extraction is based on the formation of a homogeneous mixture formed ideally between two immiscible phases (aqueous and organic) and a third component in the two immiscible phases, is added to achieve opalescence. In this mixture the complexation reactions occur and the subsequent extraction is performed by breaking the phase equilibrium by addition of an excess of the components of the mixture. However, the automation of this method by analyzing flow injection requires a device with a significant degree of complexity and difficult to control operating parameters. The objective of this study was to develop an automatic method of extracting single phase using flow-batch in question applied to the quantification of chromium in water and in commercial samples of vinegar by atomic absorption spectrometry graphite furnace. To this end, modifications have been made both in the mixing chamber (two outputs) as the extraction method, in which more suited to this proposal chemical systems were studied. The performance of the method was attested by statistical tests, in terms of precision (RSD <12%), accuracy (recovery between 82 and 108%), (m0 = 0.32 pg L-1 and LOQ = 0.86 μgL -1) and analytical frequency (26h-1). In this new strategy, the whole process of extraction was performed in mixing chamber quickly, simply and with adequate sensitivity to GF AAS technique. Moreover, it was possible to analyze samples of different matrices using the same method / A extração em fase única baseia-se na formação de uma mistura homogênea entre duas fases idealmente imiscíveis (uma aquosa e uma orgânica) e um terceiro componente miscível em ambas as fases, que é adicionado até atingir a opalescência. Nesta mistura ocorrem as reações de complexação e, a subsequente extração é realizada pela quebra do equilíbrio de fases através da adição de excesso de um dos componentes da mistura. Entretanto, a automação deste método através da análise por injeção em fluxo exige um aparato com significativo grau de complexidade e de difícil controle dos parâmetros operacionais. Assim, o objetivo deste trabalho foi desenvolver uma metodologia automática de extração em fase única utilizando análise em fluxo-batelada aplicada à quantificação de cromo em águas e amostras comerciais de vinagre por espectrometria de absorção atômica em forno de grafite. Para isto, foram feitas modificações tanto na câmara de mistura (duas saídas) como na técnica de extração, na qual foram estudados sistemas químicos mais adequados a esta proposta. O desempenho do método foi atestado através de testes estatísticos, em termos de precisão (RSD < 12%), exatidão (recuperação entre 82 e 108%), (m0 = 0,32 pg L-1 e LOQ = 0,86 μgL-1), e frequência analítica (26 h-1). Nesta nova estratégia, todo o processo de extração foi realizado na câmara de mistura de forma rápida, simples e com sensibilidade adequada para a técnica GF AAS. Além disso, foi possível analisar amostras de diferentes matrizes usando o mesmo método.

Pour améliorer la durée de vie des matériaux à haute température et sous atmosphère oxydante, une solution est l’utilisation d’une protection de surface constituée de matériaux ultra réfractaires non oxydes. Un des objectifs principaux de cette thèse est la sélection et la validation expérimentale de nouvelles compositions chimiques de revêtements utilisés en condition oxydante et corrosive à ultra haute température. Les recherches s’appuient sur une démarche expérimentale physico-chimique se basant sur une approche thermodynamique et thermochimique menée au préalable pour choisir les composés. Les revêtements doivent être stables chimiquement, compatibles thermomécaniquement avec le substrat et adhérent de la température ambiante à celle d’utilisation. De plus, Ils doivent jouer le rôle de barrière environnementale et/ou de barrière thermique.Des tests d’oxydation sont réalisés au four solaire sur les systèmes de matériaux non oxydes massifs élaborés par frittage flash. En parallèle, des composites modèles constitués d’une fibre de carbone revêtue par PVD d’un revêtement métallique ultra réfractaire ont été élaborés puis chauffés par effet Joule afin de réaliser des tests d’oxydation. La compréhension des mécanismes entrant en jeu lors de l’oxydation de ces « nouveaux » revêtements est aussi un des challenges de ce manuscrit. Par ailleurs, elle aide à la classification de ces matériaux selon leur résistance à l’oxydation. / In order to improve material’s lifetime used at a temperature above 2500°C and under oxidizing atmosphere, a solution is to use a surfacing protection constituted of non oxide refractory materials. One of the main objectives of this thesis is to select and experimentally validate new chemical coating compositions which will be used under corrosive and oxidizing atmosphere at ultra high temperature (more than 2000°C). A preliminary thermodynamic and thermo-chemical study aims to select compounds. These compounds are then analyzed with physic-chemical tests. Coatings have to be chemically stable, thermo-mechanically compatible with the substrate and have to stick to the substrate from ambient temperature to more than 2000°C. Moreover, coatings have to act as an environmental barrier and/or as a thermal barrier.Two kinds of oxidation tests are made. On one hand, non oxide massive material’s systems are fabricated by spark plasma sintering in order to be tested at the solar furnace. On the other hand, composite models are fabricated by PVD. A carbon fiber is covered with ultra refractory metallic coating by PVD. Then, these composite models are heated by Joule effect in order to realize oxidation tests. Understanding mechanisms at work during the oxidation of these new coatings is another main objective of this thesis. This understanding will be also useful to classify these materials regarding their resistance to oxidation.