Dissertations / Theses: 'Na2CO3'

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Petit, Luc. "Etude de la corrosion d'alliages de fer et de nickel par les mélanges Na2SO4, Na2CO3, NaCl et Na2CO3, Na2S, Na2SO4, NaCl entre 300oC et 900oC : application aux chaudières de récupération (procédé KRAFT)." Grenoble INPG, 1986. http://www.theses.fr/1986INPG0119.

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Etude de la corrosion en milieu de sels fondus (melanges na::(2)so::(4), na::(2)co::(3), nacl et na::(2)co::(3), na::(2)s, na::(2)so::(4), nacl) pour des temperatures comprises entre 300**(o)c et 900**(o)c d'alliages de nickel (in800, in600. . . ) et d'aciers inoxydables (z6cn1810, z12cn25-20. . . ). Mesure des variations de masse et examen des produits formes. Influence d'un traitement de surface. Influence de la composition de l'alliage. Mecanisme de corrosion

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Grynberg, Julien. "Mécanismes physiques et chimiques mis en jeu lors de la fusion du mélange SiO2-Na2CO3." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00829455.

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Entre l'enfournement des matières premières sur le bain liquide et le verre la sortie du four, on peut s'interroger sur les étapes par lesquelles le mélange vitrifiable passe avant d'être transformé en un liquide homogène. D'un point de vue chronologique, l'élaboration du verre peut être considérée en trois étapes : l'état initial du mélange granulaire avant réaction ; l'étape de réaction chimique entre les différents constituants ; un liquide avec ses inclusions gazeuses et solides (bulles et quartz résiduel). Chacune de ces étapes concerne un domaine spécifique, avec un fort couplage entre physique et chimie. Aborder la façon dont réagissent ces matières premières ensemble et comment la microstructure peut influencer le chemin réactionnel suivi globalement par le mélange est indispensable pour savoir a chaque moment de la transformation quels mécanismes sont mis en jeu. Cela permettrait de corriger certains problèmes liés à l'élaboration d'un verre industriel (bulles piégé es dans le liquide, grains de quartz non incorporés au liquide, hétérogénéité chimique du liquide). La variété de phénomènes possibles lors de la fusion d'un mélange vitrifiable industriel nous poussera à simplifier le système un maximum, afin d'être capable de relier l'évolution de la microstructure à celle de la chimie du matériau. C'est la raison pour laquelle nous avons décidé d'étudier le système SiO2-Na2CO3. Nous avons de plus utilisé des grains tamisés dans des tranches précises, afin de pouvoir relier la transformation chimique du mélange à la répartition spatiale initiale du mélange granulaire.

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Ben, Ali Amor. "Les systèmes Na2CO3-(YbF3 ou YF3)-H2O : synthèse hydrothermale, études structurales et spectroscopiques." Le Mans, 2003. http://cyberdoc.univ-lemans.fr/theses/2003/2003LEMA1008.pdf.

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Deux systèmes hydrothermaux, Na2CO3-W3-H20 (M=Yb, Y),. Sont explorés par chauffage micro-onde à 190'C dans une large gamme de compositions. Trois phases nouvelles (Yb(CO3)(OH,F)-XH20, Na2M(CO3)2F, Na3M(CO3)2F2 (M=Yb, Y) Na4Y(CO3)2F3-H2O) sont mises en évidence dans chaque système. A T>190°C, Na3Y(CO3)3-6H20, Na5y(CO3)4 et Nay2(CO3)3F apparaissent. En présence de Li2CO3, une seule phase cubique Na2LiLn(CO3)3 subsiste pour les deux systèmes, ainsi que pour la série des lanthanides Eu-Lu. Un désordre Na-'/Ln 3+ affecte trois des phases mentionnées, Na3M(CO3)2F2 (Yb, Y) et Na2LiLn(CO3)3. Dans Na2LiY(CO3)3, la RMN montre que Li+ est animé d'une agitation rapide dans son polyèdre de coordination. La comparaison des spectres RNIN 3Q-NUS de Na5Y(CO3)4 et Na2LiY(CO3)3 suggère une coordinence proche de 6 pour Na-' dans Na2LiY(CO3)3. La microscopie électronique indique, par ailleurs, que les structures de Na3M(CO3)2F2 (Yb, Y) présentent une modulation liée à l'empilement de feuillets [NaM(CO3)2F2]
Two hydrothermal systems, Na2CO3-MF3-H20 (M = Yb, Y), are investigated by mierowave assisted synthesis in large concentration domains at 190'C. Three unknown phases are evidenced in each system: Yb(CO3)(OH,F). H20, Na2Yb(CO3)2F, Na3Yb(CO3)2F2; Na2Y(CO3)2F, Na3y(CO3)2F2. Na4Y(CO3)2F3. H20. At higher température, Na3y(CO3)3-6H20, Na5Y(CO3)4 and Nay2(CO3)3F appear. With Li2CO3, one cubic phase Na2LiLn(CO3)3 exists for both systems and for Ln = Eu- Lu. Na -1 /Ln 3+ disorder affects three of the mentioned phases: Na3M(CO3)2F2, (M = Yb, Y) and the famdy Na2LiLn(CO3)3- hi Na2LiY(CO3)3, NMR spectroscopy indicates that Li+ is only submitted to fast thennal motion in its coordination polyhedron. The comparison of 3Q-NIAS NMR results for Na+ in Na5Y(CO3)4 and Na2LiY(CO3)3 suggests a coordination number close to six for Na+ in Na2LiY(CO3)3- Electron microscopy indicates that the structures of Na3M(CO3)2F2 (M = Yb, Y) present a modulation related to the stacking of the [NaM(CO3)9F2],,,, (M = Yb or Y) layers

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NASCIMENTO, Neyber Fádio Cavalcanti. "Reologia de argilas bentoníticas do Estado da Paraíba aditivadas com MgO para uso em tintas base água." Universidade Federal de Campina Grande, 2016. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1122.

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Devido a suas propriedades reológicas, uma grande quantidade de bentonitas são empregadas como aditivos para tintas como agentes espessantes, estabilizadores e antisedimentantes. Este trabalho teve por objetivo avaliar os efeitos da ativação individual e conjunta por Na2CO3 e MgO nas propriedades reológicas de argilas bentoníticas policatiônicas do estado da Paraíba visando o uso das mesmas como agentes espessantes de tintas de base água.Foram utilizadas argilas bentoníticas policatiônicas do estado da Paraíba das ocorrências de Boa Vista e Cubati, denominadas de Chocolate Boa Vista (CH BV) e Chocolate Campos Novos (CH CN), respectivamente. A caracterização física, química e mineralógica das amostras foi realizada pelos seguintes métodos: análise granulométrica (AG), fluorescência de raios X (EDX), difração de raios X (DRX), capacidade de troca de cátions (CTC), área específica (AE), análise térmica diferencial (ATD) e análise termogravimétrica (ATG). Os percentuais dos aditivos Na2CO3 e MgO foram de 0,0%, 0,5%, 1,0%, 1,5%, 2,0%, 3,0% e 4,0% quando utilizados de forma individual e de 0,5%, 1,0%, 1,5% de MgOe 0,5%, 1,0%, 1,5% de Na2CO3 associados de modo que todas as combinações fossem analisadas.Os resultados obtidos foram comparados com as especificações API e ISO de bentonitas para uso em tintas base água. A ativação apenas com MgO não proporcionou maiores valores de viscosidade às suspensões bentoníticas estudadas. A ativação apenas com Na2CO3, na forma sólida, e com ambos aditivos aumentou a viscosidade das dispersões bentoníticas com argila CH BV e foram observados comportamentos reológicos do tipo pseudoplástico com tensão de escoamentoe tixotrópico. Verificou-se também que as argilasCH BV e CH CN, com ambos aditivos, apresentaram comportamentos pseudoplástico com tensão de escoamentoe tixotrópico. Conclui-se que as bentonitas CH BV e CH CN podem ser utilizadas como espessantes de tintas de base água.
Due to its rheological properties, a large amount of bentonites are used as additives for paints as thickeners, stabilizers and anti-settling. This study aimed to evaluate the effects of individual and joint activation Na2CO3 and MgO in the rheological properties of polycationic bentonite clays of the Paraíba state aimed at using them as thickeners for water-based paints. Polycationic clays were used bentonite state of Paraiba occurrences of Boa Vista and Cubati, called Chocolate Boa Vista (CH BV) and Chocolate Campos Novos (CH CN), respectively. The physical, chemical and mineralogical samples was performed by the following methods: Particle size analysis (GA), X-ray fluorescence XDE), X-ray diffraction (XRD), capacity of cation exchange (CEC), specific area (SA), differential thermal analysis (DTA) and thermal gravimetric analysis (TGA). The percentages of MgO and additives Na2CO3 were 0.0%, 0.5%, 1.0%, 1.5%, 2.0%, 3.0% and 4.0% when used individually, and 0.5%, 1.0%, 1.5% MgO and 0.5%, 1.0%, 1.5% Na2CO3 associated so that all combinations were analyzed. The results obtained were compared with API bentonite and ISO specifications for use in water based paints. Activation only with MgO did not provide higher viscosity values for bentonite suspensions studied. Activation only with Na2CO3, in solid form, and with both additives increased the viscosity of bentonite clay dispersions with CH BV and were observed rheological behavior of the pseudoplastic type with yield stress and thixotropic. It was also found that the clays CH BV and CH CN with both additives, presented pseudoplastic behavior with yield stress and thixotropic. It follows that the bentonite and CH CN CH BV can be used as thickeners in water based paints.

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Aissa, Rabha. "Coprécipitation d'ions FeII et FeIII par Na2CO3 en milieu sulfaté et synthèse de la rouille verte substituée aluminium." Nancy 1, 2004. http://www.theses.fr/2004NAN10154.

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L'étude de la substitution des cations FeIII par les cations AlIII dans la structure de RV2(SO42-) montre qu'il est nécessaire d'introduire en solution un excès d'ions FeII par rapport à la formule chimique FeII4FeIII2(OH)12(SO4). 8H2O pour obtenir une seule phase de rouille verte sulfatée substituée aluminium. Ce nouveau composé se caractérise par une taille de cristaux de l'ordre de 50 nm et un spectre Mössbauer constitué par un doublet ferreux supplémentaire. La coprécipitation des ions FeII et FeIII en milieu sulfaté par la base faible Na2CO3 a été étudiée. Le taux d'alcalinisation et le temps de vieillissement des précipités sont les facteurs essentiels qui conditionnent la formation des rouilles vertes. Pour des taux d'alcalinisation croissant, la rouille verte sulfatée précède la formation de la rouille verte carbonatée {RV1(CO32-)}. Les rouilles vertes alors obtenues sont instables vis-à-vis d'un mélange de magnétite et de sidérite et nécessitent une analyse immédiate après synthèse. Cette transformation est inhibée par la présence d'anions silicate dans le milieu réactionnel qui réagissent avec la surface des rouilles vertes empêchant ainsi leur dissolution
Formation of sulphated green rust {RV2(SO42-)} is preceded by precipitation of a sulphated ferric basic salt and a badly crystallized ferric oxyhydroxyde. The study of the substitution of the FeIII cations by the AlIII cations in the structure of RV2(SO42-) shows that it is necessary to introduce an excess of FeII ions in solution as required for the stoichiometry of the green rust to obtain a single phase aluminium substituted sulphated green rust. This new compound is characterized by a crystal size of about 50 nm and the Mössbauer spectrum is characterised additional ferrous doublet. The coprecipitation of the FeII ions and FeIII in sulphated medium by the weak Na2CO3 was studied. Green rusts then obtained are unstable and require immediate analysis after synthesis. This transformation is inhibited by the presence of silicate anions in the reaction medium which react with the surface of green rusts thus preventing their dissolution. The transformation of the RV2(SO42-) in RV1(CO32-) is carried out by exchange of anions

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Szczesiul, Beata. "Mise en pâte d'explosion du panic érigé : effet du Li2CO3 et ZnCO3 en comparaison avec Na2CO3, NaHCO3, et MgCO3 /." Thèse, Trois-Rivières : Université du Québec à Trois-Rivières, 2001. http://www.uqtr.ca/biblio/notice/resume/03-2235606R.html.

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CORRÊA, Onésimo Amorim. "Produção de biocombustíveis em diferentes escalas via craqueamento térmico catalítico de resíduos de caixa de gordura com catalisador Na2CO3." Universidade Federal do Pará, 2015. http://repositorio.ufpa.br/jspui/handle/2011/7691.

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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
O presente trabalho apresenta a gordura residual retirada de caixas retentoras de gordura como uma matéria-prima potencial e alternativa para produção de combustíveis renováveis. A gordura residual foi utilizada como carga em experimentos de craqueamento térmico catalítico em Unidades de Bancada, Semi-Piloto e Piloto. Diferentes teores de carbonato de sódio (5%, 10% e 15%) foram utilizados como catalisador nos experimentos de craqueamneto térmico catalítico. Os produtos líquidos orgânicos (PLO’s) obtidos nos experimentos de craqueamento foram destilados em unidades de destilação em escala de bancada e piloto. Os processos de destilação resultaram na obtenção de frações de hidrocarbonetos nas faixas do querosene, diesel leve e pesado. Os PLO’s juntamente com as frações de diesel verde leve e pesado foram caracterizados de acordo com as especificações estabelecidas pela norma da ANP Nº 65 para óleo diesel S10. As frações de querosene verde foram caracterizadas de acordo com as especificações estabelecidas pela norma da ANP Nº 37 para querosene derivado do petróleo. Os resultados mostraram que os PLO’s apresentaram baixos valores para o índice de acidez, além disso, foi confirmado que a utilização de diferentes percentuais do catalisador carbonato de sódio nas três escalas de produção contribuiu para a obtenção de resultados promissores quanto ao rendimento e as características físico-químicas e composicionais, indicando a eficiência deste catalisador básico. Os resultados também mostraram que as frações de querosene verde, diesel verde leve e pesado apresentaram baixos teores de ácidos graxos livres, rendimentos significativos e características físico-químicas consonantes com as suas respectivas normas. Os experimentos que utilizaram o percentual de 10% de carbonato de sódio como catalisador apresentaram os maiores rendimentos, os menores índices de acidez e os melhores resultados das caracterizações físico-químicas e composicionais entre todos os testes feitos neste estudo. O PLO produzido utilizando o teor de 10% de carbonato de sódio apresentou um total de 78,98% de hidrocarbonetos em sua composição, enquanto o querosene verde obtido após a destilação deste mesmo PLO apresentou um total de 92,64% de hidrocarbonetos em sua composição, estes resultados foram ratificados através de análises como: FT-IR, RMN e GC-MS.
This paper presents the residual fat taken from retaining grease traps as a potential feedstock for the production of alternative and renewable fuels. The residual oil was used as filler in experiments catalytic thermal cracking countertop units, Semi-pilot and pilot. Different levels of sodium carbonate (5%, 10% and 15%) were used as a catalyst in the catalytic thermal craqueamneto experiments. Organic liquids (PLO's) obtained in the cracking experiments were distilled in distillation units in bench and pilot scale. Distillation processes resulted in the development of hydrocarbon fractions in kerosene bands, light and heavy diesel. The PLO's with the green light and heavy diesel fractions were characterized according to the specifications established by the standard of ANP 65 for diesel S10. The green kerosene fractions were characterized according to the specifications established by the standard of ANP 37 for petroleum-based kerosene. The results showed that the PLO's had low values for the acid value, moreover, it was confirmed that the use of different percentages of catalyst ash in the three scales of production contributed to obtaining promising results in terms of yield and physico -chemical and compositional, indicating the efficiency of this basic catalyst. The results also showed that the fractions of green kerosene, heavy and light green diesel had low levels of free fatty acids, significant income and physical and chemical characteristics in line with their respective standards. The experiments using the percentage of 10% sodium carbonate as catalyst showed the highest incomes, lower levels of acidity and the best results of physicochemical and compositional characterization of all the tests in this study. The PLO produced using the level of 10% of sodium carbonate showed a total of 78.98% of hydrocarbons in the composition, while the green kerosene obtained after distillation of the same PLO showed 92.64% total hydrocarbons in its composition, these results were confirmed by analysis as FT-IR, RMN and GC-MS.

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Szczesiul, Beata. "Mise en pâte d'explosion du panic érigé : effet du Li2CO3 et ZnCO3 en comparaison avec Na2CO3, NaHCO3, et MgCO3." Thèse, Université du Québec à Trois-Rivières, 2001. http://depot-e.uqtr.ca/2755/1/000685472.pdf.

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Silva, Carlos Eduardo. "Estudo do Sistema Vítreo SNABP (SiO2 Na2CO3 Al2O3 B2O3 PbO2) Nanoestruturado com Pontos Quânticos de PbS e Dopado com Íons Er3+." Universidade Federal de Uberlândia, 2011. https://repositorio.ufu.br/handle/123456789/15643.

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Fundação de Amparo a Pesquisa do Estado de Minas Gerais
The SNABP [40SiO2.30Na2CO3.1Al2O3.25B2O3.PbO2 (mol%)] glass system, nanostructured with PbS Quantum Dots (QDs) and/or doped with Er3+ ions, was successfully synthesized by the Fusion Method, when it was subjected to appropriate thermal annealing. The glass transition temperatures (Tg) were obtained by Differential Thermal Analyze (DTA), in which it was possible to define a suitable temperature to be used in the thermal annealing of the synthesized samples. As results of these thermal annealing, the formation and growth of PbS QDs have occurred in the glass environment. The optical properties of samples were investigated by Optical Absorption (OA), Photoluminescence (PL), and Photoluminescence with Temporal Resolution (PLTR). Moreover, the Atomic Force Microscopy (AFM) and X-Ray Diffractometry were employed in study of morphological and structural properties of samples, respectively. The size dispersions of PbS QDs were determined from OA spectra. Once using both the Method and OA data, it was also possible to estimate the average diameters of these nanoparticles, which grow with the increase in annealing time. The characteristic transitions of Er3+ ions were clearly identified in OA spectra. In addition, it was observed that the increase in annealing time of samples had provoked amplification in the overlapping between PL bands of both the PbS QDs and Er3+ ions, as well as with the absorption 4I15/2 -> 4I13/2 of these ions. Thus, the PLTR measurements have confirmed the decrease in lifetime of the 4I13/2 level (of Er3+ ions), with the amplification in the overlapping of PL emissions. Finally, as a main result of this work, it was proved that the SNABP glass system, nanostructured with PbS QDs and doped with Er3+ ions, displays to be quite favorable to the radiative energy transfer process (from PbS QDs to Er3+ ions), as well as the occurrence of stimulated emission of 4I13/2 level.
O sistema vítreo SNABP [40SiO2.30Na2CO3.1Al2O3.25B2O3.PbO2 (mol%)] nanoestruturado com pontos quânticos (PQs) de PbS e/ou dopados com íons Er3+ foi sintetizado com sucesso pelo Método de Fusão, quando submetido a tratamentos térmicos apropriados. As temperaturas de transição vítrea (Tg) foram obtidas por Análise Térmica Diferencial (DTA), em que foi possível definir uma temperatura adequada para ser utilizada nos tratamentos térmicos das amostras sintetizadas. Como resultados desses tratamentos térmicos, a formação e crescimento dos PQs de PbS ocorreram no ambiente vítreo. As propriedades ópticas das amostras foram investigadas por Absorção Óptica (AO), Fotoluminescência (PL) e Fotoluminescência com Resolução Temporal (PLRT). Além disso, a Microscopia de Força Atômica (AFM) e Difratometria de Raios-X (DRX) foram empregadas no estudo das propriedades morfológicas e estruturais das amostras, respectivamente. As dispersões de tamanho dos PQs de PbS foram determinadas a partir dos espectros de AO. Com a utilização do Método e os dados de AO, foi também possível estimar os diâmetros médios dessas nanopartículas, que aumentaram com o aumento no tempo de tratamento térmico. As transições características dos íons Er3+ foram claramente identificadas nos espectros de AO. Em adição, foi observado que o aumento no tempo de tratamento das amostras provocou um aumento na sobreposição entre as bandas de PL dos PQs de PbS e dos íons Er3+, bem como com a absorção 4I15/2 -> 4I13/2 desses íons. Assim, as medidas de PLRT confirmaram o decréscimo no tempo de vida do nível 4I13/2 (dos íons Er3+) com o aumento dessa sobreposição das emissões de PL. Finalmente, como principal resultado deste trabalho, foi comprovado que o sistema vítreo SNABP nanoestruturado com PQs de PbS dopados com íons Er3+ mostrou-se bastante favorável ao processo de transferência de energia radiativa (dos PQs de PbS para os íons Er3+), bem como a ocorrência da emissão estimulada do nível 4I13/2.
Mestre em Física

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Lam, Raymond Kam-Fai. "Reactions of Na2SO4(l) and CoSo4-Na2SO4(l) with SO3(g) and Al2O3(s), 900 - 1250 K." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/105286.

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Jenderka, Marcus. "Growth and Properties of Na2IrO3 Thin Films." Master's thesis, Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-201974.

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The layered honeycomb lattice iridate Na2IrO3 is a novel candidate material for either a topological insulator or spin liquid. These states of matter are one possible starting point for the future realization of scalable quantum computation, but may also find application in magnetic memory or low-power electronic devices. This thesis reports on the pulsed laser deposition of high-quality heteroepitaxial (001)-oriented Na2IrO3 thin films with well-defined in-plane epitaxial relationship on 5-by-5 and 10-by-10 square millimeter single-crystalline sapphire, YAlO3 and zinc oxide substrates. Three-dimensional Mott variable range hopping is the dominant conduction mechanism between 40 and 300 K. Moreover, a signature of the proposed topological insulator phase is found in magnetoresistance by observation of the weak antilocalization effect that is associated with topological surafce states. Compared to single crystals, a smaller, 200-meV optical gap in Na2IrO3 thin films is found by Fourier-transform infrared transmission spectroscopy.

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Freyer, Daniela. "Zur Phasenbildung und -stabilität im System Na2SO4-CaSO4-H2O." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola&quot, 2009. http://nbn-resolving.de/urn:nbn:de:swb:105-7606881.

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In den Untersuchungen zur Phasenbildung und -stabilität im System Na2SO4 - CaSO4 - H2O wurden die bisher existierenden Phasendiagramme für das wasserfreie System Na2SO4 - CaSO4 korrigiert. Metastabile Mischkristalle wurden bezüglich ihrer Existenzgebiete und Zusammensetzungen charakterisiert. Für den im wässrigen System stabil auftretenden Glauberit, Na2SO4 . CaSO4, wurde die Löslichkeitskonstante bis 250°C bestimmt und ist ab 100°C kleiner als bisher angenommen wurde. Zur Bestimmung der Löslichkeitskonstante wurde die Temperaturabhängigkeit der Freien Standardreaktionsenthalpie für die Zersetzung des Glauberits ermittelt. Dazu wurden die Cp-Funktionen für die an der Reaktion beteiligten Phasen Glauberit und Anhydrit, CaSO4, über Wärmekapazitätsmessungen bis 510°C bestimmt. Eine weitere Möglichkeit zur Bestimmung der Freien Standardreaktionsenthalpie durch die Ermittlung der thermodynamischen Aktivität von Na2SO4 in der Hochtemperaturmischkristallphase mit EMK-Messungen an Festkörperelektroden wurde aufgezeigt. Für das im System Na2SO4 - CaSO4 - H2O metastabile auftretende Natriumpentasalz, Na2SO4 . 5 CaSO4 . 3 H2O, wurde eine Einkristallstrukturanalyse durchgeführt und die strukturelle Verwandtschaft zum Calciumsulfat-Halbhydrtat, CaSO4 . 0,5 H2O, aufgeklärt, sowie die Bildungsbedingungen charakterisiert.

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Freyer, Daniela. "Zur Phasenbildung und -stabilität im System Na2SO4-CaSO4-H2O." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965898660.

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Berthaud, Maxime. "Étude du comportement de l'alliage de titane Ti6242S à haute température sous atmosphères complexes : applications aéronautiques." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCK035/document.

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L’utilisation des alliages de titane dans de nombreuses applications (transport, énergie, chimie,...) permet des gains de masse importants en tirant profit du rapport propriétés mécaniques/masse volumique qui est avantageux pour ce type de matériaux. L’utilisation de ces alliages dans des environnements à hautes températures (T>500°C) nécessite de se préoccuper de leur comportement et de comprendre les mécanismes de dégradation dans ces conditions sévères. Certains facteurs peuvent influencer le comportement des alliages de titane en oxydation, comme l’application de cycles de chauffage/refroidissement, la présence de vapeur d’eau ou la présence de sels, selon les conditions d’utilisation.Ce travail de thèse s’est attaché à comprendre les mécanismes d’oxydation d’un alliage de titane utilisé dans l’aéronautique : l’alliage Ti6242S. Il a été étudié à 560°C sous air, sous air humide et en présence de dépôts solides de sel(s) de type NaCl et/ou Na2SO4. Pour cela, des oxydations de longues durées avec et sans dépôts solides de sels ont été réalisées. Les résultats obtenus montrent que la présence de NaCl provoque une dégradation importante du comportement en oxydation des échantillons. La dissolution d’oxygène dans le métal observée sous air ne se produit plus en présence de dépôts de sels. En revanche, une oxydation interne de l’alliage a lieu et des fissures apparaissent dans la profondeur du substrat métallique. La dégradation du matériau est attribuée à la présence de dichlore et à la formation de chlorures métalliques volatiles. Un mécanisme réactionnel a été proposé afin d’expliquer l’effet néfaste des dépôts de NaCl. L’effet d’un dépôt de sels mixte NaCl/Na2SO4 sur l’oxydation de l’alliage Ti6242S est cependant moins marqué.L’évolution des propriétés mécaniques de l’alliage Ti6242S a également été étudiée après oxydation. Une simple oxydation de 100 h sous air provoque une diminution importante de la ductilité du matériau à cause de la zone de dissolution d’oxygène formée pendant l’oxydation. En présence d’un dépôt de NaCl et après 100h d’oxydation à 560°C, la perte de ductilité est encore plus importante et la rupture de l’éprouvette intervient dès la fin du domaine élastique. Dans ces conditions, la pièce perd une partie de sa section porteuse et la limite élastique et le module élastique du matériau restant sont fortement impactés. La présence d’un dépôt mixte NaCl/Na2SO4 pendant l’oxydation a un effet moins marqué sur les propriétés mécaniques du matériau, en accord avec la plus faible réactivité de l’alliage Ti6242S avec ce type de dépôt. Les mécanismes inhérents au changement de propriétés mécaniques sont expliqués dans le travail de thèse
The use of titanium alloys in many applications (transport, energy, chemistry,...) allows significant weight savings in relation to the good mechanical properties/density ratio of these materials. Since titanium alloys are employed at high temperatures (T>500°C), their behavior in such conditions has to be studied in severe conditions in order to understand degradation mechanisms. Moreover, some specific conditions can be met during application, like thermal cycling, water vapour or presence of salts. These parameters are known to influence oxidation behavior of titanium alloys.In this thesis work, oxidation behavior of an aeronautics titanium alloy (Ti6242S) has been studied in air and moist air at 560°C. The effect of solid salt deposits (NaCl and/or Na2SO4) on the oxidation behavior of Ti6242S alloy has also been taken into account. Ti6242S samples were oxidized at 560°C for oxidation times up to 19 000 hours with or without solid salt deposits. NaCl deposit resulted in an important deterioration of Ti6242S alloy behavior at this temperature. Oxygen dissolution in the metal was no longer observed compared to ageing in air, but internal oxidation of the alloy could be evidenced, and cracks were observed deeply into the metallic substrate after oxidation. The corrosion resistance decrease in such conditions was attributed to the presence of chlorine and formation of volatile metallic chlorides due to the presence of NaCl. A degradation mechanism based on active oxidation of Ti6242S alloy exposed to NaCl salt was proposed. The second salt deposit tested consisted in a mixed NaCl/Na2SO4 salt deposit. The harmful effect of this salt deposit on the oxidation behavior of Ti6242S alloy was lower than that of a simple NaCl deposit.Mechanical properties of Ti6242S alloy exposed to solid salt deposits at 560°C were then studied. A simple oxidation in air for 100 hours without salt deposit resulted in an important loss of ductility of the tested samples due to the presence of oxygen solid solution into the metal. The same oxidation time caused an even more important loss of ductility for the samples covered by NaCl deposits. In this case, sample failure occurred at the end of the elastic deformation domain. Elastic modulus and yield strength were also strongly decreased. Mixed NaCl/Na2SO4 deposit exhibited a lower impact on the mechanical properties of the oxidized Ti6242S sample, in accordance with the lower reactivity of Ti6242S alloy with this type of salt deposit. Mechanisms explaining Ti6242S alloy mechanical behavior in such conditions were explained in this thesis work

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Mobasher, Neda. "Ba(OH)2-Na2SO4-BFS cement composites for the encapsulation of sulphate bearing nuclear waste." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/11890/.

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Soluble sulphate ions in nuclear wastes can have detrimental effects on cementitious wasteforms and disposal facilities based on Portland cement. For safe immobilisation of sulphate-bearing nuclear wastes, Ba(OH)2-Na2SO4-Blast Furnace Slag composites were synthesised via a newly developed single-step method and studied. These composites promote precipitation of insoluble BaSO4 and the consequent activation of the BFS. Six month aged Ba(OH)2-Na2SO4-BFS composite samples, successfully produced via the single-step method, revealed that phases formed are low solubility salts of BaSO4 and BaCO3, calcium aluminosilicate hydrate (C-A-S-H) with some barium substitution as the main binder phase, with barium also present in Ba-substituted AFt, and a hydrotalcite-type layered double hydroxide. Long term stability investigation, up to 18 months, showed that the BaCO3 initially formed reacts with the sulphate contained in different phases to form less soluble BaSO4 without disturbing the physical stability of the bulk materials. Gamma irradiation resistance of the proposed composite cement system is the focus of the second half of this thesis. An early age BFS-PC system is studied as a reference to provide information regarding the expected behaviour of slag-rich cements under irradiation, and then early age Ba(OH)2-Na2SO4-BFS composites are studied to evaluate their performance under exposure to gamma rays by comparison. Irradiated samples were compared with control and also heat-treated samples to identify potential effects of the temperature rise during irradiation exposure. The gamma irradiation resulted in the formation of cracks in the BFS-PC system as a result of the radiolysis of the free water, whereas Ba(OH)2-Na2SO4-BFS composites could withstand gamma irradiation without any obvious reduction in the integrity of the products.

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Silva, Fernando dos Santos. "Estudo de síntese de silicato de lantânio tipo apatita pelo método sol-gel seguido de precipitação de Na2SiO3." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-29012019-143023/.

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Cerâmicas de silicato de lantânio tipo apatita têm sido estudadas devido ao grande interesse tecnológico para aplicação como eletrólito em células a combustível de óxido sólido de temperatura intermediária (IT-SOFC: Intermediate Temperature Solid Oxide Fuel Cell). A condutividade iônica dessas cerâmicas em temperaturas intermediárias (600-800°C) é maior do que a da YSZ (Ytria Stabilized Zirconia) utilizada como eletrólito em SOFCs de alta temperatura (800-1000°C). Neste trabalho, silicato de lantânio tipo apatita foi sintetizado pelo método sol-gel seguido de precipitação, a partir de Na2SiO3 como fonte de sílica. No método proposto, estudou-se rotas de síntese em meio ácido e básico para a formação do gel de sílica, seguida de precipitação. A fase cristalina de silicato de lantânio tipo apatita foi obtida pela calcinação de pós sintetizados a 900°C. Esta temperatura é muito inferior às praticadas em outros métodos convencionais de síntese. As análises por difração de raios X (DRX) mostraram silicato de lantânio tipo apatita como fase principal do material sintetizado na rota de síntese em pH ácido. No entanto, uma fase secundária indesejável, La2Si2O7, foi identificada quando o pó cerâmico foi calcinado a 1200°C. Por outro lado, pela rota básica, fase única de silicato de lantânio tipo apatita foi obtida após tratamento térmico dos precursores a 900 e 1200°C. Pastilha cerâmica obtida a partir dos pós obtidos e sinterizados a 1400°C por 4h, apresentaram fase cristalina pura de silicato de lantânio tipo apatita. Microscopia eletrônica de varredura (MEV) foi utilizada para observar a morfologia dos pós e microestrutura das pastilhas sinterizadas. Pós cerâmicos finos com tamanho de partículas submicrométricas e microestrutura típica de apatita foram alcançadas pelo método proposto.
Lanthanum silicate apatite-type ceramics have been studied because of the great technological interest for IT-SOFC applications as electrolyte (Intermediate Temperature Solid Oxide Fuel Cell). Ionic conductivity of those ceramics at intermediate temperatures (600-800°C) is higher than that of YSZ (Ytria Stabilized Zirconia) electrolyte used at high-temperatures (800-1000 °C) SOFCs. In this work, lanthanum silicate apatite-type was synthesized by sol-gel method followed by precipitation from Na2SiO3 as a source of silica. In the proposed method, synthesis routes in acid and basic medium to the formation of silica gel, followed by precipitation were studied. Apatite crystalline phase of lanthanum silicate ceramic was obtained by calcining the powders at 900°C. This temperature is much lower than those other conventional methods of synthesis. Analysis by x-ray diffraction (XRD) showed the lanthanum silicate apatite-type phase as the main phase of the synthesized material at the pH acid synthesis route. However, undesirable secondary phase, La2Si2O7, was recognized when the powder was calcined at 1200°C. On the other hand, by the basic route, single apatite-type phase powder was obtained after thermal treatment of the precursors at 900 and 1200°C. Ceramic pellet obtained from those powders sintered at 1400°C for 4h, presented pure apatite crystalline phase of lanthanum silicate. Scanning electron microscopy (SEM) was used to observe morphology of powders and microstructure of sintered pellets. Sub micrometric size powders and apatite typical microstructure ceramic were reached by the suggested method.

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Souza, Josiane Carneiro. "REUTILIZAÇÃO DE AREIA A VERDE DESCARTADA DE FUNDIÇÃO LIGADA COM Na2SiO3.XH2O/CO2 NA PREPARAÇÃO DE MOLDES NÃO PERMANENTES." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2012. http://tede2.uepg.br/jspui/handle/prefix/1425.

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Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná
The manufacture of metal parts by molding and molded by the process in the green sand (sand base crowded with clay) is widespread in industries for its low cost and operational flexibility. A major advantage is that the materials can be reused in new molding cycles. However, when the liquid metal comes in contact with the mold, causes disabling clay locally, generating inert materials that focus on the sand and limit long cycles of reuse. Thus, there are surplus sands by adding new primary materials and the consequent need for disposal to maintain the constant flow of materials. This excess is a liability that is usually discarded in landfills. This study sought a solution to this environmental waste, by reuse in the actual molding process using the sodium silicate (Na2SiO3.XH2O)/CO2, as binder. The properties obtained from samples with waste foundry sands (WFS) and with the new green sands were compared to verify the real potential for reuse WFS and the effect of its inert components and additives. For this purpose it was evaluated the mechanisms involved in the interaction with the green sand silicate before and after reaction with CO2 in the range of 0 to 20% (by weight) mixed. Mechanical properties were evaluated before and after gassing with CO2, both with WFS and with its primary components. In this study, for microstructural characterization techniques were used for X-ray diffraction, optical microscopy and MEV/ EDS. The results showed mutually dependent mechanical properties, the morphology of the silica gel coating on the sand grains, and the composition of the mixture used.
A fabricação de peças metálicas por fundição e moldadas pelo processo em areias a verde (areia base aglomerada com argila) é bastante difundida nas indústrias pelo seu baixo custo e flexibilidade operacional. Uma das grandes vantagens é que os materiais utilizados podem ser reutilizados em novos ciclos de moldagem. Porém, quando o metal líquido entra em contato com o molde, provoca a desativação da argila localmente, gerando materiais inertes que se concentram na areia e limitam ciclos longos de reuso. Com isto, surgem excedentes de areias pela adição de materiais primários novos e a consequente necessidade de descarte para manter o fluxo constante de materiais. Este excedente é um passivo que normalmente é descartado em aterros. Este trabalho buscou uma solução ambiental para este resíduo, por meio da reutilização no próprio processo de moldagem, utilizando silicato de sódio (Na2SiO3.XH2O)/CO2, como ligante. As propriedades obtidas de amostras com areias descartadas e com as areias a verde novas foram comparadas entre si para verificar o real potencial de reutilização da ADF e o efeito de seus componentes inertes e aditivos. Para esta finalidade avaliou-se os mecanismos envolvidos na interação da areia a verde com o silicato, antes a após reação com CO2, na faixa entre 0 a 20% (em peso) nas misturas. Propriedades mecânicas foram avaliadas antes e após a gasagem com o CO2, tanto com areia descartada de fundição (ADF) quanto com os seus componentes primários. Neste estudo, para caracterização microestrutural foram utilizadas técnicas de Difração de raios X, Microscopia Ótica e Microscopia Eletrônica de Varredura/EDS. Os resultados demonstraram dependência mútua entre as propriedades mecânicas; a morfologia do recobrimento da sílica gel sobre os grãos de areia; e a composição da mistura utilizada.

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Beletse, Yacob Ghebretinsae. "The environmental impact and sustainability of irrigation with coal-mine water." Thesis, University of Pretoria, 2009. http://hdl.handle.net/2263/24935.

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The environmental impact and sustainability of irrigation with coal-mine water was investigated from an agricultural point of view on different coal-mines in the Republic of South Africa. Field trials were carried out on a commercial and plot scale, on sites that could offer a range of soil, crop, weather conditions and water qualities such as gypsiferous, sodium sulphate and sodium bicarbonate waters. Crop production under irrigation with gypsiferous mine water is feasible on a field scale and sustainable if properly managed. No symptoms of foliar injury due to centre pivot sprinkler irrigation with gypsiferous water were observed. The presence of high Ca and Mg in the water suppressed plant uptake of K. This could be corrected by regular application of K containing fertilizers. The bigger problem experienced was waterlogging due to poor site selection, especially during the summer months. The problem is not related to the chemistry of the gypsiferous water used for irrigation. Pasture production with Na2SO4 rich mine effluent was also feasible, at least in the short term, but would need a well-drained profile and large leaching fraction to prevent salt build up. Forage quality was not affected by the Na2SO4 water used. NaHCO3 water was of very poor quality for irrigation and is not recommended for irrigation. Salt tolerant crops that are not susceptible to leaf scorching can be produced with this water, but only with very high leaching fractions and careful crop management. Regular gypsum application will be required to prevent structural collapse of the soil. Most of the salts applied will leach from the soil profile, and will probably need to be intercepted for treatment or reuse. The Soil Water Balance (SWB) model was validated successfully. The model predicted crop growth, soil water deficit to field capacity and soil chemistry reasonably well, with simulated results quite close to measured values. Soluble salts have to be leached from the soil profile, so that crop production can be sustainable, but will externalize the problem to the receiving water environment. To assess the environmental impact of irrigation with coal-mine water, it is valuable to develop a tool that can assist with prediction of offsite effects. SWB was validated for runoff quantity and quality estimations, and was found to give reasonable estimates of runoff quantity and quality. SWB also predicted the soil water and salt balance reasonably well. This gives one confidence in the ability of the model to simulate the soil water and salt balance for long-term scenarios and link the output of SWB to ground and surface water models to predict the wider impact of large scale irrigation. This will also link the findings of this work to other research oriented towards the management of mine water and salt balances on a catchment scale. It will also help authorities make informed decisions about the desirability and consequences of permitting mine water irrigation on a large scale. Irrigation with gypsiferous mine water can be part of finding the solution to surplus mine water problems. Appropriate irrigation management of mine water is essential for the long-term sustainability of irrigation.
Thesis (PhD)--University of Pretoria, 2009.
Plant Production and Soil Science
unrestricted

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Leite, Magda Lauri Gomes. "Cristalização e sinterização de bio vidros do sistema Na2O-CaO-SiO2-P2O5." Universidade Federal de São Carlos, 2001. https://repositorio.ufscar.br/handle/ufscar/676.

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Universidade Federal de Sao Carlos
The objective of this work was to study crystallisation and sintering of Bio-glasses of Na2O CaO SiO2 P2O5 aiming at the improvement of the mechanical properties. In order to study the development of glass-ceramics in this system, the effects of the addition of different percentages of NaF, Fe2O3, Li2O, ZrO2, TiO2 and WO3 on the behaviour of crystallisation of the glasses were studied using DSC. The results show that amongst the additions that were tested only Li2O caused increased volumetric nucleation rate. Different melting techniques were tested to obtain glasses with different concentrations of OH-. Although glasses with different contents were obtained successfully, there were problems to homogenise them. The direct extrusion technique was used to produce glass-ceramics with texture. Albeit the technique was efficient with several other systems, the results obtained in the present word showed that the glass-ceramic produced from the extruded glasses did not have the same symmetry that was showed by the glasses that were not extruded. The difficulties in sintering, related to the process of crystallisation, were analysed for two compositions of bio-glasses. Two new crystalline phases, which had not yet been observed in this system, were identified in the studies of sintering. Experimental data showed that superficial crystallisation has strong influence during the process of sintering for both glasses tested. It was not possible to obtain sintered bodies with relative density superior to 0.94 for the experimental conditions that were used. The use of the model that simulates the sintering of the glass proved to be useful to simulate the real effect of each parameter in the process, although it overestimated the ability of sintering of the compositions that were used. The use of this model can facilitate the process of searching solutions for a more efficient sintering process. Using the technique of FTIR, the studies of bioactivity of both glass and glass-ceramic powders revelled higher level of bioactivity for finer powders, and which contained phosphorus in their compositions. It was also verified that whilst total crystallisation hinders the formation of the layer of HCA, partial crystallisation seems to have beneficial effect in the process.
O objetivo deste trabalho foi estudar a nucleação, a cristalização e a sinterização de bio vidros do sistema Na2O CaO SiO2 P2O5 visando a melhoria de suas propriedades mecânicas, sem alterar significativamente a bioatividade. Para auxiliar no desenvolvimento de vitro-cerâmicas (VC) de fina microestrutura (e possivelmente boas propriedades mecânicas) estudamos os efeitos da adição de NaF, Fe2O3, Li2O, ZrO2,TiO2 e WO3, em diferentes porcentagens, no comportamento de cristalização dos vidros, através da técnica de DSC. Dentre os aditivos testados, somente o Li2O provocou aumento da taxa de nucleação volumétrica. Sabendo que OH- aumenta a taxa de nucleação, foram testadas diferentes técnicas de fusão para se obter vidros com diferentes concentrações desse dopante. Apesar do sucesso na obtenção de vidros com diferentes teores, a exemplo do que reporta a literatura, a homogeneização dos mesmos não foi satisfatória. Dessa forma, desenvolvemos e testamos um modelo original para avaliar a homogeneidade de vidros através de medidas de cristalização. A técnica de extrusão direta foi utilizada com a finalidade de produzir vitro-cerâmicas com textura (microestruturas alinhadas). Apesar da técnica ter sido eficiente em vários outros sistemas, os resultados encontrados neste trabalho demonstraram que a vitro-cerâmica obtida a partir do vidro extrudado apresentava a mesma isotropia das vitro-cerâmicas obtidas a partir do vidro não extrudado. Esse resultado é devido à morfologia quase esférica dos cristais que nucleiam neste sistema. Também tentamos sinterizar alguns desses vidros em pó, com o intuito de aproveitar a fina nucleação que geralmente ocorre nas superfícies das partículas, que após sinterizadas, poderiam levar VC com fina microestrutura. A competição entre a cinéticas de sinterização e cristalização foram analisadas experimental e teoricamente para duas composições de biovidros. Nesses estudos foram identificadas duas novas fases cristalinas, que até o momento não tinham sido observadas neste sistema Os dados experimentais mostraram que a cristalização superficial tem forte influência sobre o processo de sinterização para os dois vidros testados, sendo que para as condições experimentais utilizadas não foi possível obter corpos sinterizados com densidade relativa superior a 0,94. A utilização do modelo que simula a sinterização do vidro, apesar de superestimar a capacidade de sinterização das composições utilizadas, mostrou-se bastante útil para prever o real efeito de cada parâmetro no processo de sinterização, e com isto agilizar a busca de soluções para atingir uma densificação mais eficiente. Estudos de bioatividade utilizando a técnica de FTIR, em pós de vidro e vitro-cerâmicas, revelaram maior bioatividade para os pós mais finos e para as composições contendo fósforo em sua composição. Também foi verificado que a cristalização total do vidro retarda o processo de formação da camada de HCA, entretanto a cristalização parcial parece ter efeitos benéficos no processo de formação da camada.

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Mundstock, Karoline Bastos. "Obtenção e caracterização de biovitrocerâmicas celulares do sistema Na2O-CaO-SiO2-P2O5." reponame:Repositório Institucional da UFSC, 2012. http://repositorio.ufsc.br/xmlui/handle/123456789/93993.

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Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Florianópolis, 2010
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Este trabalho teve como objetivo a obtenção e caracterização de biovitrocerâmicas celulares para ser utilizadas como material de implante, suporte para o crescimento do tecido ósseo. Foram preparados quatro tipos de vidros do sistema SiO2-P2O5-CaO-Na2O, os quais foram denominados vidros D, E, F e G. Estes vidros foram obtidos a partir da mistura e fusão de seus precursores, carbonato de cálcio (CaCO3), carbonato de sódio (Na2CO3), fosfato de amônio dibásico [(NH4)2HPO4] e sílica (SiO2). Esses vidros foram usados para preparar as biovitrocerâmicas celulares por espumação direta usando CaCO3 como agente espumante ou pelo método da réplica usando uma esponja de poliuretano como template. Tanto os vidros como as vitrocerâmicas celulares foram analisados por técnicas de Fluorescência de Raios X (FRX), Análise Térmica Simultânea (TG/DTA), Difração de Raios X (DRX), Microscopia Eletrônica de Varredura (MEV), Energia Dispersiva de Raios-X (EDX), medidas de densidade, porosidade e expansão volumétrica. Também foram feitas medidas de resistência mecânica à compressão, análise em Fluido Corpóreo Simulado (SBF) e citotoxicidade. Todas as vitrocerâmicas celulares preparadas apresentaram uma resistência mecânica à compressão entre 3 e 12 MPa, que coincide com os valores do osso trabecular. Além disso, todas as vitrocerâmicas mostraram ser bioativas quando imersas em SBF. A vitrocerâmica preparada com o vidro F, 2% de CaCO3 tratada termicamente a 900ºC foi a vitrocerâmica que apresentou as características mais promissoras de acordo com a utilização proposta. A vitrocerâmica celular obtida pelo método da réplica também se mostrou adequada para ser usada como implante, suporte para o crescimento do tecido ósseo, pois além de apresentar poros interconectados maiores que 100 µm mostrou-se bioativa quando imersa em SBF e não citotóxica quando analisada em meio de cultura de células. Este trabalho pode contribuir com todos aqueles que pretendem obter materiais porosos que possam ser utilizados não só como suporte para o crescimento do tecido ósseo, mas também como filtros, suportes catalíticos, isolantes térmicos e acústicos, membranas, sensores de gás, material estrutural leve, já que apresenta vários métodos de preparação de materiais porosos e diversas técnicas de caracterização que podem ser utilizadas para caracterizar este tipo de material.

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Dutilleul, Olivier. "Mécanisme de corrosion des verres P2O5-Na2O-CaO-M2O3 (M:Fe3+, Al3+) amorphes et dévitrifiés." Compiègne, 1992. http://www.theses.fr/1992COMPD491.

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Nous avons étudié la corrosion des verres de phosphate du système CaO-Na2O-P205 - MIII7O3 avecMIII = Fei+, AI3+. Après avoir effectué la préparation de ces verres nous nous sommes intéressés, dans une première étape, à l'étude structurale. L'étude du verre CaO-Na2O-P2O5, appelé PCN, montre que les chaînes de phosphate sont sous la forme de longues chaînes appelées métaphosphates. Si on augmente la teneur en Fe203, celui-ci devient modificateur de verre. Le fer dépolymérise alors le verre. Nous avons étudié ensuite la dévitrification des verres PCN xFe et PCNA xFe. Lorsqu'on ajoute de l'oxyde de Fer (Fe203) au verre PCN, la cristallisation passe alors par deux étapes avec la formation de phosphates doubles de sodium fer (orthophosphates) puis avec la formation des métaphosphates observés lors de la cristallisation des verres sans fer. La deuxième partie concerne la corrosion à 100°C en solution aqueuse des verres CaONa2O-P205-M203 avec M= Fe et/ou Al. Le profil de corrosion du verre PCN est identique à celui proposé par Bunker. Celui des verres dans lesquels on a ajouté du fer est différent. Le diffractogramme X du "gel" observé à la surface du verre PCN corrodé a montré que le phosphate de calcium était sous forme d'hydroxyapatite. Enfin nous avons proposé des modèles de corrosion différents pour PCN et PCN xFe. Le premier concerne PCN et fait intervenir une étape gel de métaphosphate puis une hydrolyse et une décondensation. Le deuxième mécanisme pour PCN xFe est plus complexe et varie suivant le taux de fer introduit. Pour des faibles pourcentages de fer, le mécanisme retenu est celui des chaînes formant un gel ; mais pour un taux élevé de fer, nous n'aurions pas au départ un gel de métaphosphate mais des hydrogels d'hydrogénophosphates puis ultérieurement des hydroxydes de fer colloïdaux qui en séchant ont donné de l'hématite.

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Müllauer, Wolfram [Verfasser], Detlef [Akademischer Betreuer] Heinz, Johann Peter [Akademischer Betreuer] Plank, and Albrecht [Akademischer Betreuer] Wolter. "Mechanismen des Sulfatangriffs auf Beton – Phasenneubildungen und Expansionsdrücke in Mörteln unter Na2SO4 Belastung / Wolfram Müllauer. Gutachter: Johann Peter Plank ; Detlef Heinz ; Albrecht Wolter. Betreuer: Detlef Heinz." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1044680431/34.

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Pereira, Carmen Ines Feltrin. "Elaboração e analise de diagramas de fases dos sistemas SDS+H2O, (SDS+H2O)+DeOH e (SDS+H2O+DeOH)+Na2SO4, com auxilio de microscopia petrografica e refratometria." reponame:Repositório Institucional da UFSC, 1991. http://repositorio.ufsc.br/xmlui/handle/123456789/75807.

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Dissertação (mestrado) Universidade Federal de Santa Catarina. Centro de Ciencias Fisicas e Matematicas
Made available in DSpace on 2012-10-16T04:35:54Z (GMT). No. of bitstreams: 0Bitstream added on 2016-01-08T17:10:15Z : No. of bitstreams: 1 82128.pdf: 1863688 bytes, checksum: 59152695215c6c861fa76c5071a36a9d (MD5)
No presente trabalho elaboramos diagramas de fases de sistem liotrópicos, usando como surfactante Decilsulfato de Sódio (SDS). Partindo da concentração de 50%, em peso, de SDS e água tridestilada, determinamos uma concentração particular de existência de liomesofases (42,5% de SDS e 57,5% de H2O). Mantendo a razão da concentração para a formação do sistema ternário. Com base no diagrama de fase do sistema ternário, na região de maior estabilidade do nemático exibido pelo sistema, em temperatura, a razão (SDS + H2O) / DeOH foi escolhida para ser mantida constante quando da adição de Na2SO4, para a formação do sistema quaternário.

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Duchesne, Claire. "Etude des proprietes optiques non lineaires dans les verres. Cas du systeme NA2O-TIO2-P2O5." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1993. http://tel.archives-ouvertes.fr/tel-00136123.

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L' acces aux proprietes optiques non lineaires de materiaux tels que les verres mineraux ouvre de nouvelles perspectives dans le domaine du transport de l' information par fibre optique, voire dans celui de la commutation optique fonctionnant avec des temps de reponse tres brefs (domaine de la subpicoseconde). Concretement, leur potentialite peut etre estimee par une figure de merite F, expression d' un compromis qui doit etre trouve entre la necessite d' accroitre la vitesse et l' amplitude de changement d' indice de refraction et l' obligation d' attenuer la variation thermique de l' indice due a l' echauffement du materiau que provoque l' intensite du faisceau lumineux. Une analyse des criteres de choix des materiaux nous a conduit a centrer cette premiere etude sur des verres du systeme Na2O-TiO2-P2O5. Les resultats peuvent s' analyser en terme de reconnaissance des entites structurales se formant dans les verres et de performances obtenues sur le plan des non linearites optiques: l' analyse structurale des verres effectuee essentiellement par spectroscopie d' absorption des rayons X a conduit a l' identification des entites hyperpolarisables a l' origine des proprietes non lineaires, a savoir les groupements TiO5; les valeurs des indices non lineaires se situent un peu au-dessous de celles des verres contenant des ions lourds. En revanche, l' absence de tels constituants a permis d' accroitre considerablement les facteurs de merite. De ce point de vue, ces phosphates se placent sans doute en tete par rapport a tous les resultats publies a ce jour. Enfin, la pertinence des valeurs experimentales des indices lineaires et non lineaires a pu etre mise en evidence par une tentative de modelisation. Cette approche repose sur le modele de M. E. Lines qui a decrit la reponse electronique d' un cristal sous l' effet d' une perturbation electromagnetique en terme de processus interionique par une analyse de la liaison anion-cation.

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Marr, Robert A. (Robert Allen) 1965. "The Na2O-ZrO2-SiO2 and CaO-ZrO2-SiO2 systems : theoretical petrogenetic grids and synthesis experiments." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56671.

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Fixed-slope P$ rm sb{s}$-$ mu sb{ rm H2O}$ diagrams have been generated for the pseudoternary systems $ rm SiO sb2$-$ rm Na sb2 ZrO sb3$-$ rm H sb2O$ and $ rm SiO sb2$-$ rm CaZrO sb3$-$ rm H sb2O$ as first approximations to P-T phase relations for the Na- and Ca-zirconosilicates, respectively. Two possible topologies were determined for each pseudoternary based on an interchange of stable and metastable invariant points. Although for the $ rm SiO sb2$-$ rm Na sb2 ZrO sb3$-$ rm H sb2O$ system the correct topology cannot yet be resolved, owing to a lack of constraints from experimental and field observations, chemographic analysis reveals that the critical observation would be either the coexistence or incompatibility of the divariant mineral assemblage: elpidite + parakeldyshite.
The observed replacement of armstrongite by gittinsite + quartz in the Strange Lake peralkaline complex, Canada, suggests that the preferred topology for the $ rm SiO sb2$-$ rm CaZrO sb3$-$ rm H sb2O$ system may be the one in which the calcium catapleiite-, quartz- and calciohilairite-absent invariant points are stable.
Synthesis experiments in the $ rm SiO sb2$-$ rm CaZrO sb3$-$ rm H sb2O$ system resulted in the formation of the compound $ rm{Ca sb2 ZrSi sb4 O sb{12}}$ as well as zircon, baddeleyite, xonotlite and wollastonite under various conditions, but synthesis of naturally-occurring Ca-zirconosilicates remained elusive.

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Yazhenskikh, Elena. "Development of a new database for thermodynamic modelling of the system Na2O-K2O-Al2O3-SiO2." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=977928454.

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Delaval, Rodolphe. "Corrosion des verres de phosphates décondensés du système (Na2O. P2O5. ZnO) en milieu non-agité." Compiègne, 1996. http://www.theses.fr/1996COMPD887.

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Ce travail a concerné la corrosion des verres de phosphates décondensés et mixtes du système (Na2O. P2O5)1-x. ZnOx. L'étude initiale de la formulation des verres montre que la longueur moyenne des phosphates diminue régulièrement selon l'addition de l'oxyde de zinc. La dépolymérisation du réseau conduit à un mélange d'entités de taille variable, notamment d'espèces courtes. Les ions Zn2+ occupent des positions terminales au niveau de ces différents enchaînements phosphatés, qu'ils réticulent très faiblement. Ils se trouvent principalement en sites octaédriques, et l'oxyde de zinc participe partiellement à l'ossature du réseau vitreux, qui est dit mixte. L'évolution de la vitesse de corrosion des verres en fonction de leur proportion d'oxyde de zinc se présente sous la forme d'une courbe non-linéaire qui définit trois zones. Leur existence correspond aux phénomènes antagonistes de la décondensation et de la réticulation du réseau phosphaté par l'oxyde de zinc. Dans les mécanismes de corrosion qui ont été étudiés sur plusieurs formulations, l'étape limitative correspond toujours au délitement des enchaînements phosphatés, dont hydratation est facilitée par leur décondensation. Le verre de pyrophosphate double à un comportement spécifique, car cette formulation ne contient plus assez d'entités phosphatées suffisamment complexantes. Leur absence implique alors un mode de dissolution non-congruent. Elle permet des phénomènes d'adsorption ionique, ce qui conduit à une résistance à la corrosion particulièrement bonne.

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Ficheux, Maxime. "Diffusion multicomposante et environnement structural dans le verre Na2O-CaO-Al2O3-SiO2 contenant du zirconium." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS429.

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Le zirconium est un élément largement répandu sur Terre et aujourd’hui intensivement utilisé sous forme d’oxyde (zircone) ou d’oxyde silicaté (zircon) majoritairement pour ses bonnes propriétés thermomécaniques. A ce titre, il entre notamment dans la composition de matériaux dits « réfractaires » qui sont des céramiques frittées ou électro fondues formant la structure des fours verriers. Le zirconium rencontre ainsi le verre de deux manières différentes: en se déplaçant à haute température depuis les parois du four verrier dans le verre ou en entrant directement dans la composition cible de certains verres nécessitant une forte résistance chimique. La compréhension de son intégration dans le réseau d’un verre silicaté est un premier axe de cette thèse qui est aussi d’intérêt en sciences de la Terre où l’étude de la dissolution de zircon dans les magmas pose les mêmes problématiques. Ces phénomènes de dissolution de réfractaires dans les verres industriels ou de zircon dans les verres géologique dépendent directement de la mobilité du zirconium depuis le cristal dans le verre. Cette mobilité qui peut prendre plusieurs formes (diffusion, convection) sera étudiée dans cette thèse sous l’angle de la diffusion chimique. De nombreuses études présentant déjà des coefficients de diffusions simples de zirconium dans le verre, nous avons souhaité compléter ces données en déterminant des matrices de coefficients de diffusion via la méthode de diffusion multicomposante qui prend en compte les interactions de chaque élément sur la mobilité de tous les autres. Une autre nouveauté est le couplage d’une étude structurale à cette détermination de mobilité
Zirconium is widely spread element on Earth and actually intensively used either in its oxide form (zirconia) or in its silicate oxide form (zircon). The main interest of zirconium is to improve thermomechanical properties. This element enters in the composition of refractory materials that are sintered or electro fused ceramics used for glass furnace structure. Zirconium may also enter in glass composition through two different possibilities: at high temperature, it may move from the wall of the furnace to the glass as contaminant or it can enter in the initial glass composition, for which it can increase chemical corrosion by strengthening glass chemical durability. The understanding of its incorporation to the silicate glass structure is the first research axis of this thesis. This axis is also interesting for geosciences where zircon dissolution in geological glasses like magmas have similar issues. This dissolution phenomenon of zircon or refractory directly depends on zirconium mobility from the crystal towards the glass. This mobility may be led by several mechanisms like convection or diffusion. We focused our researches on chemical diffusion determination. Several studies have already determined diffusion coefficient of zirconium in glasses. The innovation of this thesis is the determination of mobility trough multicomponent approach, considering that each element impacts the mobility of all others. Additionally, a structural study of zirconium environment is coupled with the mobility determination

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Catteaux, Rémy. "Étude de bioverres sol-gel à base de SiO2, CaO, Na2O, P2O5 et dopés à l'argent." Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0011/document.

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Les bioverres du système quaternaire SiO2-CaO-Na2O-P2O5 obtenus par fusion doivent être coulés à 1400°C, ce qui ne permet pas la mise en forme de matériaux complexes comme par exemple des composites macroporeux en biocéramiques (HA et TCP) recouverts d’une couche uniforme de bioverre. Pour contourner cette limitation, la voie sol-gel a été utilisée dans cette étude. Le but principal a été de synthétiser par le procédé sol-gel, deux compositions quaternaires du système SiO2-CaO-Na2O-P2O5 habituellement obtenues par fusion. Il s’agit des compositions 45S5® de L.L. Hench et 47Q de C. Duée. Ces verres sont inversés, c’est à dire qu’ils contiennent plus d’éléments modificateurs (calcium et sodium) que d’éléments formateurs (silicium et phosphore). Pour la synthèse sol-gel, du TEOS (TétraEthylOrthoSilicate) et du TEP (TriEthylPhosphate) ont été utilisés pour introduire les formateurs. En utilisant des précurseurs minéraux pour le calcium et le sodium, il existe des difficultés à maintenir le gel amorphe lors de son séchage. En effet, les précurseurs minéraux sont le siège de mécanismes de dissolution-précipitation liés entre autres aux solvants choisis, à la nature et à la concentration des anions dans le milieu. L’étude s’est donc orientée vers l’utilisation d’autres précurseurs des modificateurs afin de limiter la part des anions qui contribuent au phénomène de précipitation non souhaité. Deux procédés de synthèse originaux ont été alors mis au point avec des précurseurs alcoolates, acétates et du glycérol. Avec ces procédés, la nature amorphe des composés a été confirmée et leurs caractéristiques thermiques ont été ensuite étudiées. Tous les verres sol-gel réalisés sont bioactifs. Les compositions de base, 45S5® et 47Q, ont été ensuite dopées avec de l’argent afin de doter les bioverres d’une action antibactérienne. Des cellules L132 ont été utilisées pour évaluer la toxicité des poudres des deux procédés solgel. Le procédé le moins toxique a été conservé pour la suite de l’étude. Les bioverres dopés et non dopés ont été alors déposés à la surface d’échantillons plats et macroporeux en HA et TCP par une technique de trempage-retrait. Des tests de prolifération et de formation de biofilms par Pseudomonas aeruginosa ont été réalisés sur des pastilles de TCP recouvertes et ont mis en évidence un effet toxique des dépôts contenant de l’argent. Des mesures de prolifération et de vitalité sur des cellules humaines MG63 ont été également réalisées et ont permis d’observer également un effet toxique. Cet effet n’est pas souhaitable dans ce cas car il affecte la biocompatibilité de l’implant. Il devrait cependant être confirmé par d’autres tests réalisés avec d’autres lignées cellulaires
Bioglasses of quaternary system SiO2-Na2O-CaO-P2O5 obtained by melting are cast at 1400 ° C, which does not allow the shape of complex materials, for example macroporous bioceramics composites (HA and TCP) coated with an uniform layer of bioglass. To overcome this limitation, the sol-gel process has been used in this study. The aim has been to synthesize by sol-gel process, two quaternary compositions usually obtained by melting in the SiO2- CaO-Na2O-P2O5 system. These are two compositions: 45S5® of L.L. Hench and 47Q made by C. Duée. These glasses are reversed, ie they contain more modifiers elements (calcium and sodium) as formers elements (silicon and phosphorus). For the sol-gel synthesis, TEOS (TetraEthylOrthoSilicate) and TEP (TriEthylPhosphate) have been used to introduce the formers. When minerals precursors are used for calcium and sodium, there are difficulties to maintain amorphous the gel during its drying. Indeed, minerals precursors have some dissolution-precipitation mechanisms linked to the selected solvents and the nature and concentration of anions in the medium. The use of other modifiers precursors has been made in the study to limit the proportion of anions contributing to the undesired precipitation phenomenon. Two original synthesis methods have been developed with alkoxide precursors, acetates and glycerol. With these processes, the amorphous nature of the compounds has been confirmed and their thermal characteristics have been studied. All sol-gel glasses are bioactives. The compositions, 45S5® and 47Q, have been doped with silver to add an antibacterial action to the bioglasses. L132 cells have been used to test the toxicity on the powders of the two sol-gel processes. The least toxic process is has been retained for the other tests. Doped and undoped bioglasses have been coated on the surface of flat and macroporous samples of HA and TCP by a dip-coating technique. Proliferation tests and biofilms formation by Pseudomonas aeruginosa have been made on coated TCP and show toxic effects of silver. Proliferation and vitality tests have been also made on MG63 human cells and have allowed to observe a toxic effect. This effect is not suitable in this case because it affects the biocompatibility of the implant. It would, however, be confirmed by other tests with other cell lines

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Lebecq, Isabelle. "Etude de bioverres à base de SiO2, CaO, Na2O non dopés et dopés par le phosphore." Valenciennes, 2002. https://ged.uphf.fr/nuxeo/site/esupversions/628f0255-e6b4-4af0-a060-ac6b163d2fa1.

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Le but est de trouver les verres les plus bioactifs de SiO2-CaO-Na2O non dopés et dopés avec du phosphore (P). L'immersion dans du fluide physiologique simulé permet d'étudier la formation d'hydroxyapatite cristallisée (HAC). Cette couche permet un accrochage chimique implant-os naturel. Les verres les plus bioactifs sont riches en Na2O et pauvres en SiO2. Ils forment une couche d'HAC dès 12 heures. Pour ces mêmes verres dopés avec P, l'ajout n'améliore pas la bioactivité. Pour les verres inversés au P moins riches en Na2O, correspondants aux verres du ternaire les moins bioactifs, plus le taux de P est grand plus l'HAC se forme vite (6 heures à 6 % molaire de P2O5). Dans les verres traditionnels au P, la bioactivité reste moyenne (2-3 jours) comme pour les verres conventionnels du ternaire. Des études de cytoxicité et cytocompatibilité sur le verre le plus riche en Na2O sans et avec P montrent que ces verres forment l'HAC rapidement mais rendent le milieu trop agressif pour les cellules
The aim is to determine the most bioactive glasses of SiO2-CaO-Na2O ternary, and of this system doped with phosphorus. Soaking glasses in the simulated body fluid allowed to study the formation of crystalline hydroxycarbonate apatite (HCA). This layer allows a chemical anchoring implant-natural bone. The most bioactive glasses are Na2O-rich and SiO2-poor glasses. They forms an HCA layer within 12 hours. For this same glasses doped with phosphorus, adding phosphorus don't improve bioactivity. For less Na2O-rich invert glasses with phosphorus, corresponding to the less bioactive glasses of the ternary, the higher rate of P the faster HCA forms (6 hours with 6 mol % of P2O5). In conventional glasses, bioactivity stays middle (2-3 days). Some studies of cytotoxicity and cytocompatibility on the most Na-rich glass without and with phosphorus showed that these glasses form rapidly the HCA but make the environment too aggressive for the cells

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Baril, Geneviève. "Étude par spectroscopie d'impédance électrochimique des mécanismes de corrosion des alliages de magnésium AM50, AZ91 et du magnésium pur en milieu Na2SO4 (Na exponant 2, SO exponant 4)." Toulouse, INPT, 2001. http://www.theses.fr/2001INPT023G.

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La spectroscopie d'impédance électrochimique a été utilisée pour caractériser au cours du temps d'immersion la corrosion d'alliages de magnésium en relation avec leurs microstructures. Le comportement électronique des alliages AM50, AZ91 et AZ91Si a été étudié au potentiel de corrosion dans une solution de sulfate de sodium 0,1M. A cause de sa microstructure, l'alliage AM50 présente une corrosion homogène alors que la corrosion des alliages AZ91 commence dans le grain et se développe progressivement au niveau des zones eutectiques. Pour ces alliages, la dissolution de la phase eutectique α conduit à un fort enrichissement en aluminium de la couche de produits de corrosion. Quand une concentration critique en oxyde d'aluminium dans la couche d'oxyde ou d'hydroxyde de magnésium est atteinte, un changement de l'allure des diagrammes d'impédance a été observé. Une étude plus fondamentale a été ensuite réalisée sur le magnésium pur. Il a été montré que les ions sulfates accélèrent la dissolution du film formé sur l'électrode mais que le dioxygène dissous n'influence pas la corrosion du magnésium pur. Par contre, la vitesse de corrosion est dépendante de la concentration en hydrogénocarbonate et donc de la présence de dioxyde de carbone dissous dans l'électrolyte. A partir des mesures d'impédances électrochimique et électrohydrodynamique, nous avons proposé un mécanisme réactionnel, dans lequel l'ion Mg+ (Mg exposant +) est l'espèce diffusante qui réagit chimiquement avec l'eau pour former une couche d'oxyde primaire et les ions Mg2+ (Mg exposant 2 +). Ceux-ci diffusent ensuite à travers une couche poreuse obtenue par précipitation rapide d'espèces insolubles. La boucle inductive observée sur les diagrammes d'impédance a été attribuée à l'adsorption de l'espèce Mg(OH)2 (Mg(OH) exponant 2). Le modèle proposé permet de rendre compte des résultats obtenus en impédance électrochimique.

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Delahaye-Carrière, Florence. "Influence de la solution altérante sur la dissolution des verres du système (50-x)Na2O-xCaO-50P2O5." Compiègne, 1997. http://www.theses.fr/1997COMP1057.

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Les travaux de cette thèse portent sur des verres de polyphosphate ayant une utilisation potentielle en tant que biomatériaux, ou verre-engrais. Leur dissolution et l'influence de la solution altérante sur leur dissolution est donc appréhendée. Des verres de métaphosphate de composition (50-x)Na2O-xCaO-50P2O5 sont concernés par cette étude. En premier lieu, différentes techniques, xps, rmn-mas du phosphore, ainsi que des propriétés physiques (température de transition vitreuse, densité) permettent de vérifier la structure polymérique des verres. Le caractère réticulant du calcium est également établi. La structure du matériau permet d'appréhender les intéractions verre-solution. Ensuite, le système verre-eau est étudié et sert de référence pour des milieux plus complexes. L'altération dans l'eau se caractérise par une cinétique de dissolution linéaire et un mode congruent. Les échantillons corrodés présentent une couche de verre hydraté mise en évidence par meb et analyses xps et edx. Sous cette pellicule, la surface est piquée qui progresse dans le verre massif en conservant ces irrégularités. En milieu acide, les courbes cinétiques se distinguent par un fléchissement apres une période linéaire, malgré le mode congruent. Une pellicule de verre hydraté est également observée. Il est établi que le ralentissement de la dissolution est dû à une couche qui se forme uniquement en milieu acide et à force ionique relativement élevée. Par une approche colloidale, nous avons établi que les chaines de la couche hydratée renforcent leur cohésion sous l'influence de la force ionique du milieu. La première conséquence est le changement de la charge de surface mis en évidence par des expériences de mobilité électrophorétique. La deuxième conséquence est la diminution de la vitesse de délitement ; ce qui conduit au ralentissement global de la corrosion.

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Winkler, Anke. "Molekulardynamik-Untersuchungen zur atomistischen Struktur & Dynamik von binären Mischgläsern (Na2O) (x · SiO-1tn2) und (Al2O3) (2 · SiO2) /." [S.l. : s.n.], 2002. http://ArchiMeD.uni-mainz.de/pub/2002/0125/diss.pdf.

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Kirsten, Armin [Verfasser]. "Oberflächenfunktionalisierung dentaler Zirkonoxid-Implantate mittels bioaktiver Glasbeschichtungen aus dem System SiO2-Na2O-K2O-CaO-MgO-P2O5 / Armin Kirsten." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2015. http://d-nb.info/1076065813/34.

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Welch, Mark David. "Experimental studies of selected amphiboles in the system Na2O-CaO-MgO-Al2O3-SiO2-H2O-F2 and its subsystems." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/11947.

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Iriarte, Lecumberri Pedro Ignacio. "Synthèse de minéraux argileux dans le système SiO2-Al2O3-Fe2O3-MgO-Na2O-H2O entre 150 et 225°C." Poitiers, 2003. http://www.theses.fr/2003POIT2252.

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Dans le présent mémoire on a étudié la synthèse de minéraux argileux (kaolinites et smectites) sous diverses conditions hydrothermales de pH (5-10) et de températures (150-225 o̱C), dans le système SiO2-Al2O3-Fe2O3-MgO-Na2O-H2O. Les matériaux de départ utilisés étaient des gels amorphes avec des stoechiométries de smectite et différentes proportions de cations octaédriques (aluminium, fer et magnésium). Préalablement à la synthèse, on a réalisé une optimisation de la méthode de préparation des gels dans des conditions hydrothermales (pH). La kaolinite se forme dans des conditions de pH légèrement acide. En présence de fer, celui ci s'incorpore à la structure, et la teneur en FeVI peut atteindre 30 %. Dans la gamme de composition étudiée, le système se comporte comme une solution solide octaédrique Al-Fe3+ dans les kaolinites. A partir de gels riches en Al, avec du Fe3+ et avec ou sans Mg et sous des conditions de pH légèrement plus basiques (7-10), des smectites dioctaédriques ont été synthétisées. Dans toutes les séries, notamment dans les échantillons synthétisés pour les plus basses températures, la smectite est accompagnée d'une phase à 7 Å de type kaolinite. Toutes les phases smectitiques néoformées sont de type beidellite. A partir de gels riches en Mg et dans des conditions de pH légèrement alcalin (8-10), des argiles trioctaédriques de type saponite, stévensite et kérolite ont été synthétisées. Dans tous les cas, de la kérolite a été formée. Le gel purement magnésien, aboutissent á la formation d'interstratifiés stevensite/kerolite. Les gels riches en magnésium et contenant du Fe3+, aboutissent à la formation de stevensite et kerolite. Les gels riches en magnésium et contenant de l'aluminium aboutissent à la formation de saponite et de kérolite interstratifiés ou pas interstratifiés. . .

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Mandal, Avik. "Topological Phases of (Na2O)x(P2O5)100-x glasses, their Molecular structure and Topological Defects elucidated by Raman Scattering." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563294897953075.

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Borgwardt, Nick [Verfasser], Markus [Gutachter] Grüninger, and Paul H. M. van [Gutachter] Loosdrecht. "Optics on materials with strong spin-orbit coupling: topological insulators Bi2-xSbxTe3-ySey and the j=1/2 compounds Na2IrO3 and alpha-RuCl3 / Nick Borgwardt ; Gutachter: Markus Grüninger, Paul H.M. van Loosdrecht." Köln : Universitäts- und Stadtbibliothek Köln, 2018. http://d-nb.info/1176701339/34.

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Yildiz, Mahmut [Verfasser], Reinhard [Akademischer Betreuer] Schomäcker, Arne [Akademischer Betreuer] Thomas, and Malte [Akademischer Betreuer] Behrens. "Influences of support material variation on structure and catalytic performance of MnxOy-Na2WO4/SiO2 catalyst for the oxidative coupling of methane / Mahmut Yildiz. Gutachter: Reinhard Schomäcker ; Arne Thomas ; Malte Behrens. Betreuer: Reinhard Schomäcker." Berlin : Technische Universität Berlin, 2014. http://d-nb.info/1066550301/34.

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Chi, Rifang. "Traitement en vue de leur protection contre l'oxydation d'électrodes de sidérurgie par des polyphosphates du système AI2O3-P2O5-Na2O-H2O." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376127318.

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Chi, Rifang. "Traitement en vue de leur protection contre l'oxydation d'électrodes de sidérurgie par les polyphosphates du système Al2O3-P2O5-Na2O-H2O." Lille 1, 1989. http://www.theses.fr/1989LIL10146.

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Nous avons etudié une nouvelle formulation du système Na2O-Al2O3-P2O5-H2O: le coacervat de metaphosphates d'aluminium. Nous avons confirmé que la coacervation permet de garder une meilleure structure de longues chaînes. Ce coacervat possède une stabilité plus grande vis-a-vis de l'hydrolyse que le gel correspondant. Il existe une compétition entre la complexation aluminium-phosphates et l'hydrolyse des chaînes phosphatées. La coacervation réalisée en milieu hydroalcoolique permet de stabiliser les longues chaînes. En effet, l'acidité du milieu diminue, l'effet catalytique du proton est donc moins important. L'application du procédé sol/gel (coacervat)céramiques/verres à la protection contre l'oxydation des carbones industriels a été réalisée. Nous avons montré que la protection par les revêtements réalisés avec ces coacervats de metaphosphates d'aluminium donnait des meilleurs résultats que ceux obtenus avec l'acide phosphorique. L'ajout de charges métalliques dans les coacervats améliore en plus la conductibilité électrique du revêtement par le phénomène de percolation

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Liu, Xiang Feng. "Signification pétrogénétique des micas trioctaédriques sodiques : modélisation expérimentale dans le système Na2O, K2O, MgO, Al2O3, SiO2, H2O, (TiO2, HF, D2O)." Orléans, 1989. http://www.theses.fr/1989ORLE2016.

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Soulard, Henri. "Evolution des laves basiques alcalines : étude expérimentale à 1 atmosphère du système analogue synthétique CaO-MgO-Al2O3-SiO2-Na2O (CMASN)." Clermont-Ferrand 2, 1992. http://www.theses.fr/1992CLF21424.

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Cette etude apporte des donnees experimentales sur les assemblages 4, 5 ou 6 phases de l'ensemble liquide-forsterite-diopside-plagioclase-spinelle-melilite-nepheline-orthoenstatite (liq-fo-di-pl-sp-mel-ne-oen). Apres avoir detaille les techniques experimentales et analytiques utilisees, la stchiometrie des phases minerales a ete verifiee: forsterite fo-mo-sp, diopside di-cats-en-jd, plagioclase an-ab-cms3#+s4, spinelle sp-os-ca, melilite ak-geh-sm-(ms3), nepheline nane-an-s4#+-(cms3)-(#+mas2) et orthoenstatite en-mgts-di#+jd. Nous proposons avec a. Provost, une methode descriptive numerique qui permet de quantifier les evolutions des compositions des phases dans les surfaces divariantes, et tient compte des incertitudes analytiques. Les relations de phases (donc les trajets de cristallisation) ont ete determines dans tout le systeme en utilisant (comme pour la verification de la stchiometrie) un programme de calcul de melange (inversion generalisee avec propagation des erreurs analytiques). L'assemblage cardinal des roches basaltiques (liq-fo-di-pl) possede un tres vaste domaine de stabilite reliant les compositions sursaturees a un modale et sous-saturees ou le sp, la mel, la ne et la wollastonite sont stables. Le domaine de compositions est subdivise sur la base de la norme cipw et d'un critere d'alcalinite (ne==2 na/na+al). Les limites ainsi definies correspondent a des changements drastiques dans la solution solide du di, du pl et de la mel. Des analogues synthetiques de la plupart des roches volcaniques naturelles ont pu etre definis, des basaltes aux rhyolites, phonolites et nephelinites. La relecture genetique de la classification internationale nous permet d'inclure les melilitites dans un modele d'evolution des magmas a b. P. : *les basaltes (s. L. ) produisent l'ensemble des magmas differencies par cristallisation de fodi-pl; *4 magmas parents suffisent a engendrer l'ensemble des roches volcaniques (les basaltes, nephelinites a ol, melanephelinites, melilitits a ol). Les melilitites evoluent totalement independamment de tous les autres magmas

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Hubert, Nathalie. "Contribution à la détermination des propriétés thermodynamiques des solutions aqueuses d'électrolytes forts : étude des systèmes H2O-NaCl et H2O-Na2SO4 entre 25°C et 100°C par mesures d'équilibre liquide-vapeur et par calorimétrie." Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL005N.

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L’objectif du présent travail est de définir une procédure expérimentale optimale pour déterminer les propriétés thermodynamiques de solutions aqueuses binaires d'électrolytes forts. Deux expérimentations complémentaires ont été mises en œuvre. D’une part, des mesures de la pression de vapeur de l'eau ont été effectuées afin de déterminer les variations du coefficient osmotique en fonction de la température et de la composition. Pour cela, un dispositif manométrique statique non isotherme a été construit et validé par l'étude du système H2O-NaCl entre 25°C et 100°C. D’autre part, des mesures isothermes de l'enthalpie de dissolution de NaCl solide dans l'eau ont été effectuées à plusieurs températures (24. 4°C, 44. 3°C, 59. 2°C) par calorimétrie de mélange. L’ensemble des résultats a permis de déterminer les lois de variation en fonction de la température des paramètres du modèle de Pitzer. Le système H2O-Na2SO4 a été étudié entre 25°C et 90°C selon le même plan d'expérience et la méthode de traitement des résultats mis au point sur le système H2O-NaCl a été appliquée avec succès

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Lima, Gilberto de. "Estudo de um novo eletr?lito polim?rico s?lido em forma de filme autossustent?vel: Poli(?xido de etileno)-tungstato de s?dio." PROGRAMA DE P?S-GRADUA??O EM QU?MICA, 2016. https://repositorio.ufrn.br/jspui/handle/123456789/21476.

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Filmes polim?ricos autossustent?veis baseados em um novo eletr?lito polim?rico s?lido (EPS), tendo como matriz hospedeira o poli(?xido de etileno) (POE) e como agente dopante o tungstato de s?dio (Na2WO4), foram obtidos para diferentes composi??es do sal (m = 0,20; 0,26; 0,30; 0,40; 0,50 e 1,31 mg). Os filmes foram caracterizados por DRX, FTIR, MEV/EDS, TG/DTG, DSC e EI. Os difratogramas de raios X confirmaram a natureza semicristalina do pol?mero e sugeriram que a adi??o do sal provoca uma redu??o na cristalinidade dos filmes. Os dados de FTIR permitiram a an?lise da intera??o entre os ?ons do sal e as cadeias polim?ricas. As micrografias obtidas por MEV demonstraram morfologia esferul?tica intercaladas por liga??es interlamelares para todas as composi??es estudadas. O estudo de TG/DTG mostrou que a decomposi??o t?rmica do eletr?lito ocorre em uma ?nica etapa com a adi??o do sal aumentando a estabilidade t?rmica dos filmes. Os dados de TG/DTG permitiram, ainda, o estudo cin?tico da decomposi??o t?rmica do eletr?lito por meio dos m?todos de Briodo (BR), Coats-Redfern (CR) e Horowitz-Metzger (HM) sugerindo uma cin?tica de 1? ordem para a rea??o de decomposi??o t?rmica dos filmes, assim como, a determina??o dos par?metros termodin?micos de ativa??o: E*, ?H*, ?S* e ?G*. O grau de cristalinidade foi determinado atrav?s dos dados de DSC e mostrou uma redu??o ap?s a adi??o do sal ao pol?mero. O eletr?lito POE/Na2WO4 exibiu um m?ximo de condutividade i?nica de 3,24x10-4 S.cm-1, a temperatura ambiente, para o filme com 1,31 mg do sal. Atrav?s dos dados de imped?ncia foi poss?vel o estudo de relaxa??o das cadeias do POE, assim como, a difus?o do sal entre estas cadeias. Os diagramas de imped?ncia, nos formatos Bode e Nyquist, permitiram o ajuste dos dados experimentais ? circuitos el?tricos equivalentes o que facilitou a associa??o dos componentes dos circuitos aos fen?menos f?sicos e qu?micos observados para os filmes e revelaram que, ap?s a adi??o do sal ao pol?mero, os filmes t?m suas propriedades el?tricas melhoradas.
Self-sustainable polymeric films based on new solid polymer electrolyte, having the poly(ethylene oxide) (PEO) as host matrix and sodium tungstate as doping agent (Na2WO4), were obtained from different salt compositions (m = 0.20; 0.26; 0.30; 0.40; 0.50 and 1.31 mg). The films were characterized through XRD, FTIR, SEM/EDS, TG/DTG, DSC and IS. X-ray diffraction showed the semi crystalline nature of the polymer and confirmed that the addition of salt induces reduction in the crystalinity of the films. FTIR data allowed the identification of the interaction between salt ions and polymer chains and confirmed that these interactions are of a physical nature. The micrographs obtained through SEM showed spherulitic morphology interleaved by interlayered bonds for all of the compositions studied. The TG/DTG study revealed that the thermal decomposition of the electrolyte almost happens at a single stage with the addition of salt, increasing the thermal stability of the films. TG/DTG data also allowed the kinetic study of the thermal decomposition of the electrolyte through Broido (BR), Coats-Redfern (CR) and Horowitz-Metzger (HM) methods, suggesting a first-order kinetic for the reaction of the thermal decomposition of the films, as well as the setting of pre-exponential factor, A, and the thermodynamic activation parameters: E*, ?H*, ?S* and ?G*. The crystallinity degree was determined through DSC data and showed a reduction after the addition of salt to the polymer. The polymer has its conductivity increased after addition of the salt with the PEO-Na2WO4 electrolyte exhibiting maximum of ionic conductivity of 3.24x10-4 S cm-1, to room temperature, for the film with 1.31 mg of salt (F6 film). The impedance data allowed the study on relaxation on PEO chains, even as the diffusion of salt between these chains. The impedance diagrams, on Bode and Nyquist formats, enabled the adjustment of the experimental data to equivalent electric circuits, which facilitated the association of the circuit components to the physical and chemical phenomena observed for the films and revealed that, after the addition of salt to the polymer, the films have their electrical properties enhanced.

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Stoica, Martina [Verfasser], Christian [Gutachter] Rüssel, and Dörte [Gutachter] Stachel. "Photoinduced crystallisation of CaF2 from a Na2O/K2O/CaO/CaF2/Al2O3/ZnO/SiO2 glass / Martina Stoica ; Gutachter: Christian Rüssel, Dörte Stachel." Jena : Friedrich-Schiller-Universität Jena, 2018. http://d-nb.info/1170396410/34.

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Link, Marcelo. "Influência da razão SiO2/Na2O do silicato de sódio na defloculação de suspensões aquosas empregadas na conformação por colagem de barbotinas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/87344.

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O silicato de sódio é um aditivo largamente utilizado na indústria cerâmica, sendo empregado como defloculante em barbotinas no processo de conformação por colagem. A razão SiO2/Na2O é uma das características mais importantes do silicato de sódio. Este trabalho apresenta um estudo comparativo entre quatro silicatos de sódio distintos quanto à razão SiO2/Na2O, empregado como defloculante em uma suspensão de argila, outra de caulim e uma terceira suspensão da argila, do caulim, com o acréscimo de um feldspato,constituindo essa última mistura uma massa de cerâmica triaxial. As suspensões foram caracterizadas quanto à variação da viscosidade e do pH em função do teor de defloculante empregado, na formação de espessura de parede pelo Teste Baroid e pela colagem em molde de gesso. Os resultados mostraram uma forte influência da relação SiO2/Na2O na defloculação de argilas, mas pouca influência na defloculação do caulim e uma forte influência na defloculação da massa cerâmica. Também, foi possível constatar uma relação entre o aumento de pH e a redução da viscosidade mínima aparente. Com o aumento da razão SiO2/Na2O, foi obtido um acréscimo na espessura de parede, o que favoreceria o processo de fabricação, com possíveis ganhos de produtividade. O silicato de sódio com razão SiO2/Na2O 2,43 apresentou a melhor relação de desempenho entre defloculação e formação de espessura de parede.
Sodium silicate is an additive widely used in the ceramics industry, being employed as a deflocculant in the slip casting process. The ratio SiO2/Na2O is one of the most important characteristics of sodium silicate. This paper presents a comparative study between four different sodium silicates with different SiO2/Na2O, used as deflocculant in a suspension of clay, kaolin and a third of the clay, kaolin, with de addition of feldspar, forming a triaxial ceramic slip. The suspensions were characterized in terms of viscosity and variation of the pH in function of the amount of deflocculant employed, in the formation of wall thickness by Baroid testing and the plaster mold slip casting. The results showed a strong influence on the ratio SiO2/Na2O in the deflocculation of clays, but little influence on the deflocculation of kaolin and a strong influence on the deflocculation of the ceramic slip. Also, there has been a relationship between the increase of the pH and a reduction in the minimum apparent viscosity. Whit increasing SiO2/Na2O was obtained an increase in wall thickness, which would favor the manufacturing process, with possible productivity gains. Sodium silicate with ratio SiO2/Na2O2,43 showed the best performance between deflocculation and wall thickness.

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Boukili, Boubker. "Cristallochimie des biotites ferro-alumineuses dans le système Na2O-K2O-FeO-Fe2O3-Al2O3-SiO3-SiO2-H2O-HF. Analyse par spectrométries vibrationnelles et Mössbauer." Phd thesis, Université d'Orléans, 1995. http://tel.archives-ouvertes.fr/tel-00788712.

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CE TRAVAIL CONCERNE L'ETUDE CRISTALLOCHIMIQUE DES BIOTITES FERRO-ALUMINEUSES DE SYNTHESE DANS LE SYSTEME NA20-K20-FE0-FE203-AL203-SI02-H20-HF, EN FONCTION DE LA TEMPERATURE ET DE LA FUGACITE D'OXYGENE. LES METHODES DE CARACTERISATION EMPLOYEES SONT LA DIFFRACTION X ET LES SPECTROMETRIES INFRAROUGE, RAMAN ET MOSSBAUER. EN L'ABSENCE DE FLUOR, LE FER FERRIQUE SE REPARTIT ENTRE SITES TETRA- ET OCTAEDRIQUES, SA TENEUR GLOBALE AUGMENTE AVEC LA FUGACITE D'OXYGENE. EN CONDITIONS HYDROTHERMALES, L'OXYDATION DU FER FAIT INTERVENIR AU MOINS TROIS MECANISMES, ET N'EST PAS ASSOCIEE A LA SEULE DEPROTONATION. LE POLE ANNITE THEORIQUE N'EST PAS STABLE ; L'ANNITE NE PEUT ETRE DECRITE QUE COMME UNE SOLUTION SOLIDE A CINQ CONSTITUANTS. LA SOLUBILITE DE F EST BEAUCOUP PLUS ELEVEE DANS L'ANNITE (XF = 0,5), OU ELLE PROVOQUE UNE DIMINUTION DE LA TENEUR EN FER FERRIQUE, QUE DANS LES BIOTITES ALUMINEUSES (XF = 0,2) DANS LESQUELLES LA PROPORTION DE FER FERRIQUE DIMINUE. CET ENSEMBLE DE DONNEES MONTRE UNE ADAPTATION DE LA STRUCTURE DE CES MICAS A LA FOIS AUX CONDITIONS DE GENESE ET A LA COMPOSITION GLOBALE DES SYSTEMES. EN PARTICULIER, LES MODIFICATIONS DES DISTRIBUTIONS CATIONIQUES INTERSITES ET INTERCOUCHES PERMETTENT LE MAINTIEN DE L'ELECTRONEUTRALITE LOCALE, ET L'ADAPTATION DIMENSIONNELLE DES COUCHES. LE DOMAINE DE STABILITE DES BIOTITES SODIQUES EST LIMITE AUX COMPOSITIONS LES PLUS ALUMINEUSES. D'UN POINT DE VUE METHODOLOGIQUE, L'AVANCEE LA PLUS SIGNIFICATIVE CONCERNE LA SPECTROMETRIE MOSSBAUER AVEC LA MISE EN EVIDENCE DE TROIS DOUBLETS FERREUX DANS CERTAINS CAS, ET D'ORDRES: FER FERREUX EN M1, FER FERRIQUE ET ALUMINIUM EN M2.

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Silva, Ana Paula Bispo da. "Fabricação caracterização dos sistemas vítreos TeO2-ZnO-Na2O e TeO2-Nb2O5-Bi2O3 para dispositivos ópticos nas janelas de 1.3 [micrômetro] e 1.5 [micrômetro]." [s.n.], 1998. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278247.

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Orientador: Luiz Carlos Barbosa
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Nesta dissertação apresentamos a síntese dos sistemas vítreos TeO2-ZnO-Na2O e TeO2-Nb2O5-Bi2O3 , visando obter dispositivos ópticos nas janelas de 1.3 e 1.5 mm.As amostras foram dopadas com Érbio, Praseodímio e Itérbio, que emitem nos comprimentos de onda de interesse. Os sistemas foram caracterizados estruturalmente utilizando-se técnicas de difração de raios-x' densimetria e Espectroscopía Raman. A caracterização óptica das amostras foi feita por índice de refração linear, fotoluminescência, tempo de vida de decaimento e Espectroscopía UV-Vis-IV. As propriedades térmicas foram caracterizadas por dilatometria, análise térmica diferencial e viscosidade. Estes sistemas apresentaram alta estabilidade térmica, com a diferença entre as temperaturas de transição vítrea e cristalização em tomo de 100 oC. Na viscosidade de puxamento de fibra, em 105.5 e 106 poise, os sistemas não apresentaram picos de cristalização, o que nos permitiu fazer o puxamento das fibras dopadas com terras raras com sucesso. O alto valor de índice de refração apresentado, 2.2, indica um material óptico não linear importante para aplicações em dispositivos ópticos de chaveamento. Os espectros de fotoluminescência mostraram uma largura de banda de 100 nm, muito mais larga que as de sílica dopada com Er, que têm 30 nm. A alta solubilidade das terras raras nos sistemas vítreos permitiu-nos dopá-los com até 70000 ppm, duas ordens maior do que a suportada pelas fibras comerciais existentes, que têm sua luminescência prejudicada pelo efeito de relaxação cruzada. O tempo de vida de decaimento ficou entre 2 e 4 ms, mostrando que nos sistemas estudados o efeito de relaxação cruzada é bem menor que na sílica. Os resultados mostraram a possibilidade de se fabricar amplificadores ópticos integrados de pequenas dimensões com altas concentrações de terras raras e 3 vezes mais canais que os amplificadores existentes
Abstract: In this thesis we presented the synthesis of the vitreous systems, TeO2-ZnO-Na20 and TeO2-Nb2O5-Bi2O3 , in our search for materials to be used in optical devices in the communication windows of 1.3 and 1.5 mm. The samples were doped with Erbium, Praseodymium and Ytterbiurn, which show light emission in the wanted wavelength windows. These systems were structurally and physically characterized by X-ray diffraction techniques, Raman and density measurements. The optical characterizations of the bulk samples were made by linear refraction index, photoluminescence and photoluminescence decay lifetime measurements and UV-VIS-IR absorption Spectroscopy. The thermal properties were characterized by dilatometry and viscosity measurements. These systems presented a high thermal stability, with a 100° C temperature difference between the crystallization and the softening point temperatures. The viscosity was in the range 105.5 to 106 poise between these temperatures indicating the possibility to draw optical fibers, therefore we developed a capillar suction method to make the nucleous of a core-cladding optical fibers, which allowed us to successfully draw rare earth doped optical fibers. The very high linear refraction index, 2.2, indicates a highly non linear optical material, important for ultrafast optical devices applications. The photoluminescence spectra show light emission in a 100 nm wavelength bandwidth, much larger than the 30 nm usually obtained with Er doped silica fibers. Because of the high rare earth solubility in these systems we have been able to dope our glass up to 70,000 ppm, two orders of magnitude above the usual commercial doped fibers doping levels, which are limited by the luminescence quenching due to cross relaxation effects. The photoluminescence decay lifetime in the range of 2 to 4 ms show that the cross-relaxation effects in these rare earth glass hosts is much smaller than in silica. These results show the possibility to manufacture small, integrated optical amplifiers with very high rare earth concentration with 3 times more wavelength channels than the commercially used amplifiers
Mestrado
Física
Mestre em Física

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Fleischer, Vinzenz [Verfasser], Reinhard [Akademischer Betreuer] Schomäcker, Ulrich [Gutachter] Nieken, Robert [Gutachter] Schlögl, and Reinhard [Gutachter] Schomäcker. "Oxidative coupling of methane : resolution of the surface and gas phase contributions to the mechanism of the oxidative coupling of methane at Na2WO4-Mn-SiO2-catalyst / Vinzenz Fleischer ; Gutachter: Ulrich Nieken, Robert Schlögl, Reinhard Schomäcker ; Betreuer: Reinhard Schomäcker." Berlin : Technische Universität Berlin, 2017. http://d-nb.info/1156346746/34.

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Dissertations / Theses on the topic 'Na2CO3'

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