Submitted by Cássio da Cruz Nogueira (cassionogueirakk@gmail.com) on 2017-02-13T14:39:48Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_DesacidificacaoFracoesDestiladas.pdf: 2889911 bytes, checksum: 46a68fb9f2542c626bdd08f273e474fc (MD5) / Approved for entry into archive by Edisangela Bastos (edisangela@ufpa.br) on 2017-02-14T17:11:55Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_DesacidificacaoFracoesDestiladas.pdf: 2889911 bytes, checksum: 46a68fb9f2542c626bdd08f273e474fc (MD5) / Made available in DSpace on 2017-02-14T17:11:55Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_DesacidificacaoFracoesDestiladas.pdf: 2889911 bytes, checksum: 46a68fb9f2542c626bdd08f273e474fc (MD5) Previous issue date: 2015-04-16 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho foi estudado o processo de adsorção de ácidos graxos livres residuais (ácidos carboxílicos) presentes em frações destiladas provenientes do Produto Líquido Orgânico (PLO) obtido por craqueamento termo-catalítico de óleo vegetal. O objetivo foi a desacidificação das frações destiladas obtidas a partir da destilação do PLO. Os experimentos foram realizados empregando diferentes frações destiladas empregando três diferentes adsorventes, y-Alumina, Lama Vermelha Ativada Termicamente (400ºC) e Lama Vermelha Ativada Quimicamente com soluções de HCl em diferentes concentrações (0.25, 1 e 2M). A capacidade do adsorvente em relação à adsorção de ácidos graxos livres foi avaliada por meio de estudos cinéticos, medindo-se a variação da concentração de ácidos graxos livres presentes antes e após a adsorção, através da determinação do Índice de Acidez. Os resultados indicaram que o aumento da concentração de ácidos iniciais diminui a capacidade de adsorção do adsorvente, mostrando que o processo é menos eficiente para concentrações mais elevadas. Para os experimentos com diferentes porcentagens de adsorventes vimos que ao se utilizar 0,5% de adsorvente obtemos a maior eficiência na remoção dos ácidos graxos, a qual vai diminuindo com o aumento da porcentagem de adsorvente. O adsorvente mais eficiente foi a Lama Vermelha ativada com 1M de HCl, onde foi obtida uma redução de 98% dos ácidos graxos para uma amostra com índice de acidez inicial 4 mg KOH/g. A modelagem matemática indicou que o modelo cinético que melhor representa o processo foi o modelo Cinético de Pseudo-2ª Ordem. Portanto, os resultados mostraram que os adsorventes utilizados são, na sua maioria, eficientes na remoção dos ácidos graxos livres e que a concentração inicial de ácidos na amostra tem efeito direto sobre o desempenho da adsorção dos mesmos. / This paper studied the adsorption of residual free fatty acids (carboxylic acids) present in distilled fractions from the Liquid Organic Product (PLO) obtained by thermal catalytic cracking of vegetable oil. The objective was to deacidification of distilled fractions obtained from the distillation of the PLO. The experiments were performed using different distilled fractions using three different adsorbents, y-Alumina, Red Mud Thermally activated (400 °C) and Red mud chemically activated with solutions of HCl in different concentrations (0.25, 1 and 2M). The adsorbent capacity relative to adsorption of free fatty acids was evaluated by means of kinetic studies, measuring the change in concentration of free fatty acids present before and after adsorption by determining the Acid Number. The results indicated that increasing the initial concentration of acids decreases the adsorption capacity of the adsorbent, showing that the process is less effective at higher concentrations. For experiments with different percentages of adsorbents seen that when using 0.5% adsorbent to obtain greater efficiency in the removal of fatty acids, which decreases with increasing percentage of adsorbent. The most efficient adsorbent was red mud activated with 1M HCl, which was obtained a reduction of 98% of the fatty acids to a sample with an initial acid number of 4 mg KOH/g. Mathematical modeling indicated that the kinetic model that best represents the process was the Pseudo Second- Order. Therefore, the results show that the adsorbents used are mostly effective in the removal of free fatty acids and the initial concentration of acids in the sample has a direct effect on the performance of adsorption thereof.

Submitted by Cássio da Cruz Nogueira (cassionogueirakk@gmail.com) on 2017-02-13T14:59:34Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_EstudoCineticoIsotermas.pdf: 3143352 bytes, checksum: 45ffca6692dbf8ebf9c8c5cdd8257ed6 (MD5) / Approved for entry into archive by Edisangela Bastos (edisangela@ufpa.br) on 2017-02-15T15:47:55Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_EstudoCineticoIsotermas.pdf: 3143352 bytes, checksum: 45ffca6692dbf8ebf9c8c5cdd8257ed6 (MD5) / Made available in DSpace on 2017-02-15T15:47:55Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_EstudoCineticoIsotermas.pdf: 3143352 bytes, checksum: 45ffca6692dbf8ebf9c8c5cdd8257ed6 (MD5) Previous issue date: 2013-11-08 / Neste trabalho, as variáveis do processo em batelada de adsorção dos óleos vegetais de palma (Elaeis guineensis, Jacq.) e andiroba (Carapa guianensis, Aubl.) adsorvidos em aluminas ativadas termicamente a 723,15 K e 923,15 K (y-alumina) foram investigadas por meio da análise da influência da temperatura, tempo, massa de óleo e massa de adsorvente sobre a capacidade de adsorção. Um modelo cinético de segunda-ordem foi utilizado para a modelagem da capacidade de adsorção de ácidos graxos livres (AGL). Resultados de capacidade de AGL dos óleos brutos de palma em y-alumina AG.450 a 328,15 K e andiroba em y-alumina AG.650 a 323,15 K, obtidos de experimentos de adsorção consecutiva, foram modelados por meio de isotermas de adsorção de Irving Langmuir e BET. O modelo de TAN & LIOU (1989) foi utilizado para a modelagem da cinética de dessorção do óleo de palma em y-alumina AG.650 e do óleo de andiroba em y-alumina AG.450, utilizando-se dióxido de carbono supercrítico como solvente, avaliando-se os rendimentos, erros, os coeficientes de correlação e os resíduos das massas dos óleos dessorvidas versus preditas pelo modelo.A influência das variáveis sobre a capacidade de adsorção, apresentaram correlação negativa (curva exponencial) para a variável massa de adsorvente. A influência da variável massa de óleo apresentou correlação positiva (comportamento linear), sendo a elevação da temperatura favorável ao processo. Os resultados totais de redução de AGL após três adsorções consecutivas do óleo de palma e quatro adsorções consecutivas do óleo de andiroba foram de 21,07 % e 40,29 %, respectivamente. A modelagem com a isoterma Langmuir para o óleo de palma apresentou alta capacidade de predição (R² = 0,9996), assim como para o óleo de andiroba, onde o modelo de BET apresentou alto ajuste (R² = 0,9146). O modelo de Tan & Liou evidenciou alta capacidade de predição dos dados experimentais, R² mínimo de 0,9230 e resíduos da ordem de 10-1 gramas. Os rendimentos das dessorções do óleo de palma a partir da -alumina AG.650 de 20 MPa a 30 MPa e 323,15 K a 328,15 K, foram de 28,88 % a 34,563%, enquanto para o óleo de andiroba em y-alumina AG.450 de 15 MPa a 25 MPa e 323,15 K a 328,15 K, foram de 14,208 % a 27,972 %. Os resultados mostram que a elevação de pressão ou temperatura favorecem o processo de dessorção supercrítica. / In this work, the variables of the batch adsorption process of palm (Elaeis guineensis, Jacq.) and andiroba (Carapa guianensis, Aubl.) vegetables oils on thermally activated alumina at 723,15 K and 923,15 K (y-alumina) has been investigated by analyzing the influence of temperature, time, mass of vegetable oil, mass of adsorbent on the adsorbent capacity. A kinetic model of second-order was proposed to modeling the adsorption capacity of free fatty acids (FFA). Capacity results of FFA of the crude palm oil on y-alumina AG.450 at 328.15 K and of the crude andiroba oil on y-alumina AG.650 at 323.15 K were obtained from the consecutive adsorption experiments and adjusted by isotherms of Langmuir e BET. The transfer mass model of TAN & LIOU (1989) was used to modeling the kinetic desorption of the palm oil from y-alumina AG.650 and of the andiroba oil on y-alumina AG.450 with supercritical carbon dioxide, evaluating the yields, errors, correlation coefficients and the residues of the desorbed oil mass versus predicted by the model.The study of the variables influence, over the adsorption capacity, presented negative correlation (with exponential behavior) to the variable mass of oil. The adsorbent mass influence, presented a positive correlation (with a linear behavior) and the temperature increase is favorable to the adsorption process. The total reduction of the FFA after three consecutive adsorptions of the crude palm oil on y-alumina AG.450 and after four consecutive adsorptions on -alumina AG.650 with andiroba oil, were 21.07 % and 40.29 %, respectively. The modeling of the FFA capacity to the palm oil with Langmuir model, presented a high experimental data prediction ability (R² = 0.9610), as well as to the andiroba oil with the BET model, which presented a high adjustment (R² = 0.9140). Tan & Liou model evidenced high prediction capacity of the desorption oil mass from γ-alumina for all experiments, minimum correlation coefficient of 0.9230 and magnitude residues of 10-1 grams. The yields, based on adsorbate initial mass, of the palm oil desorbed from y-alumina AG.650 at 20 MPa up to 30 MPa and 323.15 K up to 328.15 K were 28.880 % up to 34.563 %, while to the andiroba oil on y-alumina AG.450 at 15 MPa up to 25 MPa at 323.15 K were 14.108 % up to 27.972 %. The yields results shows that the increase of pressure and temperature are favorable to the supercritical desorption.

Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2017-04-12T13:02:02Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_AproveitamentoRejeitoCaulim.pdf: 7255550 bytes, checksum: 1cf9dd419155eff22adcbd62e6db8507 (MD5) / Approved for entry into archive by Edisangela Bastos (edisangela@ufpa.br) on 2017-04-12T16:07:48Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_AproveitamentoRejeitoCaulim.pdf: 7255550 bytes, checksum: 1cf9dd419155eff22adcbd62e6db8507 (MD5) / Made available in DSpace on 2017-04-12T16:07:48Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_AproveitamentoRejeitoCaulim.pdf: 7255550 bytes, checksum: 1cf9dd419155eff22adcbd62e6db8507 (MD5) Previous issue date: 2000-11-29 / FINEP - Financiadora de Estudos e Projetos / A região Amazônica detém 10 % das reservas mundiais de caulim. A partir dos anos setenta, duas grandes jazidas amazônicas de caulim vêm sendo exploradas, produzindo caulim para cobertura de papel. No processo de beneficiamento, é gerado um elevado volume de rejeito industrial poluente, o qual é depositado em extensas e onerosas lagoas de sedimentação. Pelo fato do rejeito ser bastante volumoso, essas lagoas tornam-se um problema ambiental de grandes proporções, devido às extensas áreas desmatadas para suas construções (Barata, 1998). Neste trabalho, são propostas alternativas de utilização econômica desse rejeito, o qual constitui-se, basicamente, de uma suspensão do argilomineral caulita, para a produção de pozolana, sulfato de alumínio, a síntese de alúmen de amônio e alumina para utilização cerâmica. A metodologia constitui-se na secagem e calcinação do rejeito, seguida da extração do Al contido via lixiviação ácida (H2SO4), seguida da cristalização de alúmen de amônio, por reação com NH4OH concentrado, mediante controle de pH, e posterior calcinação a 1200°C, obtendo-se ?-Al2O3, isenta de sódio e de baixa granulometria. Das aluminas assim obtidas, são confeccionados corpos de prova prensados e sinterizados a 1600° C, para determinação de suas propriedades cerâmicas, as quais são comparadas com as de uma alumina comercial. Após a lixiviação ácida para a extração do Al, resulta como material insolúvel, uma sílica amorfa, para a qual sugere-se, como contribuição adicional, uma aplicação econômica, empregando-se como pozolana artificial em argamassas de cimento portland, realizando-se testes mecânicos para avaliação de seu desempenho. Os materiais utilizados e sintetizados, foram caracterizados empregando-se difração de raios-X, microscopia eletrônica de varredura, espectroscopia no infravermelho, termogravimetria, análise térmica diferencial, distribuição granulométrica, área específica BET, porosidade, análises químicas por via úmida e por fluorescência de raio-X. / The Amazon region detains 10% of the world reserves of kaolim. Since the seventy's, two great amazonic beds of kaolim are explored, producing kaolim for paper cover. In the beneficiation process, it's generated an elevated volume of polluted industrial residue which is deposited in extensivas and onerous lagoons of sedimentation. Because of the residue is very voluminous, these lagoons become an environmental problem of great proportions, due the extensivas deforested areas used for their constructions ( Barata, 1998). In this work, are suggested altematives of economic utilization of this residue, which is constituted, mainly, by a suspension of the claymineral kaolinite, for the production of pozolane, aluminium sulphate, the synthesis of the ammonium alum and alumina for ceramics utilization. The methodology constitutes in the drying and the calcination of the residue, followed by the extraction of the AI retained by the acid lixiviation H2SO4 ) followed by the ammonium alum crystallisation, for the reaction with the concentrated NH4OH, by means of pH control, and later calcination at 1200°C, getting a-Al2O3, with no sodium and Iow granulometry. From the aluminas obtained, are made bodies of proof smashed and sintered at 1600°C, to the determination of the ceramics properties, which are compared to one of the commercial alumina. After the acid lixiviation for the AI extraction, results as an insoluble material, an amorphous silica, for which it is suggested, as an additional contribution, an economic application, using it as artificial pozolane in building portland cement, making mechanics tests for the evaluation of its performance. The material that were used and synthesized were characterized throught the use of the X ray diffraction, eletronic scanning microscopy, the infra-red spectroscopy, thermogravimetry, differential thermic analisys, particle size analysis, specific area BET, porosity, chemical analisys throught umid means and throught X ray fluorescence.

Submitted by Nathalya Silva (nathyjf033@gmail.com) on 2017-04-24T19:51:20Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_DesenvolvimentoUnidadeTransferencia.pdf: 5766543 bytes, checksum: fcf8315abf2ab82857983c0462d36d66 (MD5) / Approved for entry into archive by Edisangela Bastos (edisangela@ufpa.br) on 2017-04-25T22:07:01Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_DesenvolvimentoUnidadeTransferencia.pdf: 5766543 bytes, checksum: fcf8315abf2ab82857983c0462d36d66 (MD5) / Made available in DSpace on 2017-04-25T22:07:01Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_DesenvolvimentoUnidadeTransferencia.pdf: 5766543 bytes, checksum: fcf8315abf2ab82857983c0462d36d66 (MD5) Previous issue date: 2013-02 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / O refino de bauxita utilizando o processo Bayer produz de 0,7 a 2,0 t do resíduo conhecido como lama vermelha e cerca de 1,0 t de CO2 para cada tonelada de alumina produzida. O resíduo de bauxita apesar de não ser particularmente tóxico, apresenta riscos ao meio ambiente devido ao grande volume e a sua reatividade. De acordo com a tecnologia mais recente tem parte da umidade removida e é empilhado em depósitos impermeáveis especialmente construídos. Mais de 95% do resíduo de bauxita que já foi produzido no mundo (2,6 Bt até 2007) foi descartada, principalmente em depósitos em terra. Esta tese mostra o projeto, a construção e a operação de uma unidade de transferência de massa gás líquido em escala piloto com o objetivo de testar a redução da reatividade do resíduo de bauxita através da reação com gás de combustão. Como ganho adicional há a redução da emissão de dióxido de carbono e dióxido de enxofre. Esta unidade, composta por três reatores, foi projetada de modo a consumir o mínimo de energia, utilizar os efluentes da maneira mais eficiente possível e minimizar o custo de investimento. Foram realizados 25 experimentos com duração de 80 a 520 minutos cada um. Os gases foram analisados com o uso de sensores eletroquímicos e infravermelho não dispersivo na entrada e saída. O pH foi mensurado durante e após a reação de modo a avaliar os resultados curto e longo prazo bem como a estabilidade das reações. Foi demonstrada a viabilidade de reagir o resíduo de bauxita com os gases provenientes da combustão de fontes fósseis da própria refinaria sem processamento prévio com o pH de estabilização atingindo 10,5. / The bauxite refining using the Bayer process produces 0.7 to 2.0 tons of the residue known as red mud and about 1.0 ton of CO2 for each ton of alumina produced. The bauxite residue, although not particularly toxic, poses risks to the environment due to its large volume and reactivity. According to the latest technology, part of the moisture is removed and it is stacked on sealed areas specially constructed. More than 95% of the bauxite residue that has been produced (2.6 Bt until 2007) was discarded, especially in ponds on land. This thesis shows the design, construction and operation of a pilot scale gas liquid mass transfer unity with the objective of testing the reduction of the reactivity of the bauxite residue through a reaction with flue gas. As an additional gain, there is a reduction of carbon dioxide and sulfur dioxide emissions. This unity, with three reactors, was designed in order to consume minimal power, process the effluent as efficiently as possible and minimize the investment cost. Twenty-five experiments were realized with duration from 80 to 520 minutes each. The gases were analyzed at the entry and exit with electrochemical cells and non-dispersive infrared sensors. The pH was monitored during and after the reaction in order to evaluate the short and long-term results as well as the stability of the reactions. It was demonstrated the viability of reacting the bauxite residue with the flue gas from the refinery without previous processing with the stabilization pH reaching 10.5.

Materiais cerâmicos, como a alumina e a zircônia têm sido explorados ao longo dos anos na aplicação como biomateriais. Sua natureza bioinerte, tem estimulado o desenvolvimento de novas alternativas, como tratamentos químicos para tornar o desempenho biológico destas cerâmicas mais adequadas. O recobrimento biomimético de cerâmicas bioinertes a partir de soluções com concentrações iguais às do plasma sanguíneo humano, SBF, pemiite o crescimento de uma camada bioativa na superfície dos implantes. A bioatividade do material está relacionada com a formação de uma camada constituída por cristais de hidroxiapatita carbonatada de baixa cristalinidade, similar à apatita biológica. A biocompatibilidade associada às propriedades estruturais da alumina e da zircônia tem estimulado o uso clínico destes materiais, inclusive em regiões de maiores solicitações mecânicas. Neste trabalho foram produzidas amostras de alumina, zircônia dopada com ítria (3% mol) e compósitos de alumina e zircônia dopada com ítria (3% mol) preparadas pelo método de co-precipitação, calcinadas, sinterizadas, tratadas quimicamente com soluções de ácido fosfórico e hidróxido de sódio e imersas em 1,0M e 1,5M SBF. Os pós calcinados foram analisados por difração de raios x (DRX), microscopia eletrônica de varredura (MEV), análise de área de superfície específica (BET) e análise de distribuição granulométrica (CILAS). Os resuhados por DRX indicam que as amostras possuem baixa cristalinidade. Observou-se que por BET as amostras apresentam alta área de superfície específica. Os resultados de CILAS e MEV mostraram que os pós encontram-se na forma de aglomerados. As amostras sinterizadas, foram analisadas por difração de raios x (DRX), microscopia eletrônica de varredura (MEV) e fluorescência de raios x (FRX), apresentando 96% da densidade teórica e as fases analisadas pelo método de Rietveld foram identificadas e quantificadas como: cúbica, tetragonal e monoclínica da zircônia, além da fase alfa da alumina. O tratamento químico com ácido fosfórico não apresentou uma tendência de maior formação de apatita em relação às amostras não tratada quimicamente. O tratamento com hidróxido de sódio provocou transformação acentuada da fase cúbica para tetragonal e da fase tetragonal para a fase monoclínica da zircônia. Os ensaios biomiméticos proporcionaram a formação de apatita sobre as superfícies das amostras, identificadas por DRX, e sua espessura foi medida por FRX. / Ceramic materials, as akimina and zirconia have been explored along the years as biomateriais application. The bioinert nature has been stimulating the development of new alternatives, as chemical treatments to improve the biological application of these ceramics. The biomimetic process of bioinerts ceramics for coating apatite is based on soaking the implant in a simulated body fluid, SBF, with ion concentrations nearly equal to those of human blood plasma. The bioactivity of the material is related with the formation of a layer constituted of hidroxiapatite low crystalline, similar to the biological apatite. The biocompatibility associated to the structural properties of the alumina and zirconia has been stimulating the clinical use of these materials, mainly in areas of larger mechanical requests, places not recommended for bioactive hidroxiapatite, for instance. In this work samples of alumina, zirconia doped with yttria (3% mol) and composites of alumina and zirconia doped with yttria (3% mol) were prepared by co-precipitation method, calcinated, sintered, chemically treated with solutions of acid phosphoric and sodium hydroxide and them immersed in l.OM and 1.5M SBF. The calcinated powders were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), gas adsorption (BET) and laser diffraction. The XRD resuhs indicate that the samples are low crystalline. It was observed for BET that the samples present high specific surface area. The resuhs of laser diffraction and SEM showed that the powders are agglomerates. The sintered samples were analyzed by XRD, SEM and X-ray fluorescence (XRF). The phases quantified by Rietveld method were: cubic, tetragonal and monoclinic of the zirconia, besides the phase alpha of the alumina. The chemical treatment with phosphoric acid didn\'t present a tendency of larger apatite formation in relation to the samples no chemically treated. The treatment with sodium hydroxide provoked accentuated transformation of the cubic phase for tetragonal phase and of tetragonal phase for the monoclinic phase of the zirconia. The immersion of samples in SBF provided apatite coating formation on the surfaces of the samples, identified by XRD, and the coating thiclmess was measured by XRF.

Un procédé de synthèse de dépôts nanostructurés de céramiques à bases d’aluminium au sein de composites carbone/carbone (C/C) est développé. Il consiste à synthétiser à partir de précurseurs dissout en solution aqueuse des nano-particules de morphologies variées. La maîtrise du procédé se déroule en deux étapes. Dans un premier temps une étude sur substrat plan permet de saisir les points clés du procédé, puis l’adaptation de la synthèse au sein d’un échantillon massif permet le changement d’échelle à des échantillons fibreux. Quatre gammes d’éprouvettes de matériaux densifiés sont ainsi élaborées. La caractérisation des matériaux permet de prouver la bonne cohésion de ceux-ci et de mesurer plusieurs propriétés mécaniques et structurales.En complément plusieurs interfaces carbone|alumine ou nitrure d’aluminium sont simulées par une approche de dynamique moléculaire ab initio. La méthode choisie pour générer les modèles consiste à simuler la trempe d’un carbone amorphe à haute température sur une surface céramique immobile, puis de relaxer les contraintes.Des disparités sur l’organisation structurale des nano-structures et en particulier sur l’orientation des plans de graphène générés vis-à-vis de la surface sont observées en fonction des modèles. Lorsque les plans sont plutôt perpendiculaires à la surface, l’interface est constituée de nombreuses liaisons fortes et le comportement en simulation de traction est bon, tandis que des plans parallèles entrainent une interface et un comportement faible.Enfin, la caractérisation HRTEM de certains matériaux élaborés permet d’identifier expérimentalement des interfaces semblables à celles obtenus par les modèles. / A hydrothermal-like process to introduce nano-structured alumina and aluminum nitride in carbon/carbon (C/C) composites is developped. Starting from dissolved reactants in an aqueous media,nanoparticules with various morphology are synthesised. The understanding and control of the processis completed in two steps. In the former the study on simplewafer type substrat allows to identifythe key parameters of the process. During the latter a scaling up of the process is done to allow thesynthesis in situ of C/C composites. The microstructural and some mechanical characterization ofthe four ranges of material produced is achieved.In addition several carbon|alumina and carbon|aluminumnitride are simulated using an ab initiomolecular dynamic approach. The methdology to generate the models consists in sumulating theliquid quench of a high temperature amorphous carbon inbetween fixed ceramic surface, then torelease the constrains. Depending on the system, different organisations of the nano-carbons withinthe surfaces are identified : when the graphene sheets are pependicular to the surface, the modelshows an important number of strong bonds and the simulation traction behavior is good, whereaswhen they are parallel to the surface it leads to weak interface and mechanical behavior.Finally HRMET charasterization of some of the materials produced allows to identify experimentalinterfaces alike to those obtained during themolecular dynamic simulations.

A l'heure actuelle les recherches de nouvelles apatites thermiquement plus stables se développent. Ainsi desdépôts à base de fluoroapatite (Ca10(PO4)6F2) ou de fluorhydroxyapatite fournissent des dépôts plus stables etplus adhérents que l'hydroxyaptite tout en étant biocompatibles. La fluoroapatite (Fap) présente non seulement despropriétés physicochimiques semblables à celles de l'os naturel mais également une bonne résistance à lacorrosion dans le milieu physiologique. La Fap et l'hydroxyapatite (Hap) sont utilisées soit sous forme de dépôt surles parties métalliques de prothèses soit toutefois comme matériaux de comblement osseux. L'utilisation de cesbiocéramiques pose quelques problèmes en raison de leur faible tenue mécanique. L'alumine a été proposée ainsipour ses bonnes propriétés mécaniques et pour sa forte affinité pour le fluor avec lequel elle donne des composéstrès stables. Des dépôts composites Al2O3-Fap et Hap-Fap ont été réalisés par projection thermique. Nous avonsfait varier dans ces composites le pourcentage de fluor. Les résultats obtenus montrent que l'ajout de Fap améliorela résistance mécanique et les propriétés tribologiques de l'Hap et contribue à l'adhésion et à la prolifération descellules osseuses pour les dépôts d'alumine. / A considerable amount of research already focused on ceramic biomaterials given their chemical stabilityand high mechanical strength. On the one hand, Fluorapatite (Fa) has recently attracted some attention as analternative to pure hydroxyapatite (Hap) as coating on metallic implants, given its chemical composition which issimilar to the bone mineral and therefore its excellent biocompatibility. On the other hand, alumina is known for itsexcellent bioinertia and is also one of the most widely investigated bioceramics. In this frame, the aim of our workwas to investigate Al2O3-Fap and Hap-Fap composite coatings deposited on stainless steel substrates usingSpraying processes (APS and SHVOF). The mechanical, micro-structural, tribological and biological (in Vitro and inVivo tests) properties of these composite coatings are determined and analysed in order to determine their possibleuse as surigical implant materials.

Dans cette étude de doctorat, de la poudre de Y3Al5O12 (YAG) a été synthétisé avec plusieurs méthodes: atomisation, synthèse de réaction et co-précipitation. Le procédé de synthèse le plus prometteur, la co-précipitation, a été optimisé pour obtenir une poudre hautement frittable, présentant une phase pure. Le traitement approprié avant frittage, comprenant calcination, efficace dispersion et séchage homogène, a été réalisé. La poudre de YAG a été dispersée avec plusieurs méthodes, avant frittage. Grâce à la technique Spark Plasma Sintering (SPS) une évaluation très rapide de l'influence des différents traitements a été réalisée. Il a été constaté que, pour une poudre obtenue avec une telle synthèse, la méthode de dispersion est cruciale afin de obtenir une transparence élevée du materiaux fritté. En raison de l'aptitude au frittage de la poudre, du traitement approprié avant frittage et de la basse température du cycle effectué par SPS, un matériau à grains fins a été obtenu. Des mesures de spectroscopie de photoélectrons (XPS) ont été effectuées sur la poudre de YAG et sur le matériaux fritté, et plusieurs differences ont été mises en évidence. Quelques hypothèses ont été faites pour expliquer les differences observées, et certains preuves supplémentaires pour les vérifier ont été mises en avant. Une poudre composite alumine-zircone-YAG a été synthétisé à partir d'une poudre d'alumine commerciale, qui a été fonctionnalisé avec chlorures de yttrium et de zirconium. Les traitements de pré-frittage appropriées ont été effectués, comprenant une calcination à basse température et une calcination "rapide", pour favoriser la germination des petits cristallites. Deux méthodes de mise en forme, coulage et pressage, ont été réalisées. Il a été constaté que le coulage permet la production de matériaux céramiques beaucoup plus homogènes. Une caractérisation mécanique préliminaire a été effectuée. Une caractérisation spectroscopique des poudres d'alumine-YAG, traités à basse et haute température, a été réalisée. Il a été mis en évidence que l'état d'hydratation des poudres varie avec la fonctionnalisation par les chlorures. La présence de sites Y sur la surface des poudres composites a été mise en évidence par XPS et à partir des spectres infrarouges (spectroscopie infrarouge par transformée de Fourier, FTIR) des échantillons soumis à des différentes pressions de monoxide de carbone (CO). / In this PhD study, Yttrium aluminum garnet (Y3Al5O12, YAG) powder was synthesised with several methods, i.e. spray drying, reaction synthesis and co-precipitation. The most promising synthesis method, i.e. co-precipitation, was optimized to obtain a pure phase, highly sinterable powder. The appropriate pre-sintering processing, i.e. calcination treatment, e fficient dispersion, homogeneous drying, were performed. YAG powder was dispersed with several methods, prior to sintering. Through Spark Plasma Sintering (SPS) a very fast assessment of the influence of the various treatments was performed. It was found that, for the synthesised powder, the dispersion method is crucial to obtain a high transparency. Due to the high sinterability of the powder and to the appropriate pre-sintering treatment, a low temperature SPS cycle was performed, and a fine-grained material was obtained. X-ray Photoelectron Spectroscopy (XPS) measurements were performed on YAG powder and on the sintered material, and several di fferences were evidenced. Some hypothesis were made to explain the observed di fferences, and some additional proofs to verify them were put forward. A composite Alumina-YAG-Zirconia powder was synthesized, starting from a commercial alumina powder, which was functionalised with Yttrium and Zirconium chlorides. The appropriate pre-sintering treatments were performed, comprising a low temperature calcination and a "fast" calcination, to favour the germination of small crystallites. Two shaping methods, i.e. slip casting and pressing, were performed. It was found that slip casting allows the production of much more homogeneous ceramic materials. A preliminary mechanical characterization was performed. A spectroscopic characterization of Alumina-YAG powders, heat-treated at low and high temperatures, was performed. It was evidenced that the hydration state of the powders changes with chlorides functionalization. The presence of Y sites on the surface of the composite powders was evidenced by X-ray Photoelectron Spectroscopy and from the di fference spectra of powdered samples subjected to various CO pressures.

La connaissance du comportement et des propriétés des matériaux est d’une grande importance pour optimiser leur mise en forme et adapter leur utilisation. Pour étudier ces propriétés de nombreuses techniques sont couramment utilisées : les essais de traction, la microindentation, la nanoindentation instrumentée… Aujourd’hui, un intérêt particulier est porté sur les nanomatériaux et matériaux nanostructurés car ils présentent souvent des propriétés différentes et plus intéressantes. La nanoindentation instrumentée, notamment, permet de déterminer des paramètres matériaux de manière locale. Cependant, le comportement en temps réel ne peut être observé et l’échantillon ne doit pas être de dimension trop faible (typiquement, l’étude de nanoparticules n’est pas envisageable). Le principal atout de la nanoindentation in situ en Microscopie Electronique en Transmission vis-à-vis des autres techniques existantes est la possibilité d’étudier le comportement de nano-objets ou des comportements très locaux et en temps réel, tout en observant les transformations subies par le matériau. Dans cette étude, nous avons évalué les potentialités de cette nouvelle technique via l’analyse de céramiques très étudiées au laboratoire notamment en tant que biomatériaux : la zircone stabilisée et l’alumine. Dans le cas de la zircone (stabilisée à l’yttrium ou au cérium), le but était de localiser à l’échelle nanométrique les contraintes responsables ou inhérentes à la transformation de phase quadratique-monoclinique, phénomène ayant une très grande influence sur les propriétés du matériau massif. Pour ce faire, après avoir déterminé une technique de préparation adaptée, nous proposons une voie d’étude pour la localisation des contraintes liées à la transformation de phase : le CBED (Convergent Beam Electron Diffraction) couplé à la nanoindentation in situ. Dans le cas de l’alumine, l’objectif était d’étudier le matériau (commercial et non un matériau modèle) dans sa forme originelle à savoir sous forme de nanoparticules d’alumine de transition. L’idée était d’étudier le comportement de ces nanoparticules sous compression. Nous avons notamment constaté que ces particules pouvaient subir une grande déformation plastique à température ambiante. Nous avons pu également, sur quelques particules, obtenir une série d’images en cours de compression ainsi que la courbe de charge-déplacement correspondante. Ces résultats ont ensuite été soumis à une analyse des images couplée à une simulation de type Eléments Finis (réalisées par le LAMCOS). / Knowledge of the behavior and properties of materials is of great importance to optimize their processing and adapt their use. To study these properties, many techniques are commonly used: tensile tests, microindentation, instrumented nanoindentation ... Today, particular interest is focused on nanomaterials and nanostructured materials because they often have different and more interesting properties. Instrumented nanoindentation allow to determine material parameters. However, the real-time behavior can not be observed and the study of nano-objects is difficult (nanoparticles for example). The main advantage of in situ TEM (Transmission Electron Microscopy) nanoindentation is the ability to study the behavior of nano-objects in real time. In this study, we evaluated the potential of this new technique by analyzing ceramics extensively studied in the laboratory such as biomaterials: stabilized zirconia and alumina. In the case of zirconia (stabilized with yttrium or cerium), the goal was to locate at the nanoscale, the constraints responsible for the tetragonal to monoclinic phase transformation. This phenomenon having a great influence on the bulk material properties. To do this, after having determined a suitable preparation method, we suggest a way to study the localization of constraints: the CBED (Convergent Beam Electron Diffraction) coupled with in situ TEM nanoindentation. In the case of alumina, the goal was to study the material in its original form (nano powder of transition alumina). The idea was to study the behavior of these nanoparticles under compression. We particularly observed that these particles could undergo large plastic deformation at room temperature. We have also obtained during compression on few particles, series of images and the corresponding load-displacement curve. These results were then analyzed by image analysis coupled with Finite Element simulations (performed in LAMCOS lab).

L’objectif de cette thèse est le développement de composites dans le système alumine-zircone par une approche d’ingénierie des poudres permettant de façonner les caractéristiques microstructurales et compositionnelles, et, par conséquent, les propriétés des matériaux finaux. Les poudres composites ont été elaborée à travers la modification de la surface des poudres commerciales par un précurseur inorganique de les phases secondaires . Cette approche innovante assure un degré élevé du contrôle de la taille et de la distribution des grains de seconde phase sur la surface du matériau parent. Les poudres composites à base d’alumine contenant 10 vol% de zircone non-stabilisée et des poudres composites à base de zircone triphasique contenant 8 vol% d’alumine et 8 vol% de phase aluminate, ont été développées. Leur propriétés physiques, chimiques et mécaniques a été caractérisé. Dans le cas premier, les materials porous ont été développés à travers le technique gel-casting avec sphères de PE. Les mécanismes de ténacité de la zircone ont été étudiés, révélant aucun influence sur les propriété mécaniques. Les composites poreux présentent des valeurs de résistance à la rupture plus élevées, en comparant à des alumines pures, mais cet amélioration peut être raisonnablement dû à leur microstructure plus fine, celle-ci étant caractérisée par des grains et des pores plus petits. Dans le deuxième cas, a partir de la Ce-TZP, connue pour sa ténacité et sa stabilité importantes, un travail d’optimisation de la microstructure a été réalisé afin d’obtenir une résistance à la rupture maximale. Les matériaux présentés dans cette étude ont été développés afin de répondre au triple objectif de ténacité, résistance et stabilité. Deux composites très prometteurs, avec des résistances à la rupture élevées (environ 900 MPa) et ténacités élevées (environ 10Mpa√m), ont été réalisés. De plus, les composites étudiés ont montré de hautes capacités de transformation et pas de faible température de dégradation en atmosphère humide, dans les temps des applications médicales. Il a été démontré que les propriétés mécanique sont vivement affectées par le degré de stabilisation de la zircone. L’étude de la relation entre les propriétés finales et l’architecture de la composition/microstructure, au but d’obtenir les propriétés désirées, se révèle nécessaire. / The aim of this PhD study is the development of composites in the alumina-zirconia system through a powder engineering approach which allows tailoring the compositional and microstructural features, and, as a consequence, the properties of the final materials. The experimental activities refer to two different projects. The first, named MITOR project, was devoted to the elaboration and mechanical characterization of macro-porous Alumina-Zirconia composites. It dealt with the development of a new method for the elaboration of composite cellular ceramics and with the investigation of the role of zirconia and its toughening mechanisms in porous materials, thus filling a gap in the scientific literature. The latter, a European Project named Longlife, was dedicated to the preparation and characterization of zirconia (stabilized with ceria)-based composites for dental and spine implants. The major aim was to overcome the drawbacks proper of yttria-zirconia-based materials, concerning their stability in moisture atmosphere as well as their low toughness. Ceria-zirconia-based composites should benefit from phase transformation toughening still keeping high strength. In addition, they should not suffering of surface degradation in presence of water. So, materials characterized by high strength, high toughness with a perfect reliability and a lifetime longer than 60 years were investigated. Alumina-based composite powders containing 10 vol% of un-stabilized zirconia as well as tri-phasic zirconia-based composite powders containing 8 vol% of alumina and 8 vol% of an aluminate phase(Srontiuma nd Magnesium hexaxaluminate), were developed and characterized in terms of phase evolution and thermal behaviour. In addition, the adopted elaboration route allowed tailoring the ceria amount inside the zirconia grains: four different zirconia stabilization degree were thus investigated. Two very promising composites with high fracture strength, of about 900 MPa, and high crack resistance were found. Furthermore, the investigated composites showed high transformability and no low temperature degradation in moisture atmosphere in the time-scale of medical applications. It was shown that the deep knowledge of all the involved mechanisms (such as raw powders dispersion, pH suspension, powder thermal treatments) is crucial for achieving a full control of the powders features and, consequelntly, of the final microstructures.