Made available in DSpace on 2017-07-21T20:42:42Z (GMT). No. of bitstreams: 1 Christiane Lago Ojaimi.pdf: 6052819 bytes, checksum: 5dbeb59c4d5610d059c81f63f68e3c11 (MD5) Previous issue date: 2014-01-29 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / The search for a beautiful and harmonious smile has motivated research on ceramic materials for dentistry aiming at the elimination of the metal substructure. Among many dental devices, abutments for implants are one component that has been replaced by ceramic material. The ceramics that exhibit good biocompatibility and mechanical properties are alumina and zirconia, the latter being the material the most widely used ceramic abutments. Both alumina and zirconia as present some restrictions when used only, but the ceramic base of alumina and zirconia compounds can present improved property compared with the isolated materials. Studies exhibit that alumina-zirconia nanocomposites present agreat improvement in some mechanical properties. Since the national production of ceramic abutments is still low compared to international production, and ceramic abutment with alumina and zirconia is not widespread. This work aims studying the sintering in two and three steps process of ceramic alumina nanocomposites with nanometric inclusion of 15% by volume of zirconia, aiming the application as dental abutment. For this purpose, samples were produced by pressing and sintered using different sintering conditions. The characterization of the sintered nanocomposites was made by X-ray diffraction, scanning electron microscopy and measurements of grain size, and mechanical properties were evaluated from Vickers microhardness and fracture toughness. To evaluate the hydrothermal stability of these nanocomposites, accelerated aging tests were done in an autoclave and the samples were characterized by atomic force microscopy and X-ray diffraction. The results showed that sintering in steps allowed in the refinement of the microstructure of nanocomposites and that were resistant to hydrothermal degradation. / A busca por um sorriso bonito e harmônico tem motivado pesquisas na área de materiais cerâmicos para odontologia visando à eliminação da subestrutura metálica. Dentre muitos dispositivos odontológicos, os pilares intermediários para implantes são um dos componentes que vem sendo substituído por material cerâmico. As cerâmicas que apresentam boa biocompatibilidade e propriedades mecânicas são a alumina e a zircônia, sendo esta última a mais utilizada em pilares cerâmicos. Tanto a alumina quanto a zircônia apresentam algumas restrições quando utilizadas sozinhas, porém os compostos cerâmicos a base de alumina e zircônia podem apresentar ganhos de propriedade se comparada com os materiais isolados. Estudos mostram ainda que os nanocompósitos de alumina-zircônia apresentam uma grande melhoria em algumas propriedades mecânicas. Porém na produção de materiais cerâmicos geralmente utiliza-se sinterização sem pressão, o que ocasiona grande crescimento de grão, um dos métodos para se refinar a microestrutura de maneira simples é a sinterização em etapas. Uma vez que a produção nacional de pilares cerâmicos ainda é baixa se comparada com a produção estrangeira, e o pilar de cerâmica com alumina e zircônia é pouco difundido. Este trabalho teve como objetivo estudar o processo de sinterização em duas e três etapas de nanocompósitos cerâmicos de alumina com 15% em volume de inclusão nanométrica de zircônia, visando a aplicação como pilar odontológico. Para isso, amostras produzidas por prensagem foram sinterizadas utilizando diferentes condições de sinterização. A caracterização dos nanocompósitos sinterizados foi feita por difração de raios X, microscopia eletrônica de varredura e medidas de tamanho de grão, e as propriedades mecânicas foram avaliadas por medidas de dureza Vickers e tenacidade à fratura. Para avaliar a estabilidade desses nanocompósitos foram feitos ensaios de envelhecimento acelerado em autoclave e as amostras foram caracterizadas por microscopia de força atômica e difração de raios X. Os resultados mostraram que a sinterização em etapas permitiu o refinamento da microestrutura dos nanocompósitos e que este apresentou resistência a degradação hidrotermal.

Este trabalho traz a aplicação de alta pressão e alta pressão/temperatura (4.0 GPa e 400º C), em amostras de nanotubos de carbono de paredes múltiplas (NTCPM) comerciais para a obtenção de amostras compactas. Os NTCPM foram funcionalizados com ácido nítrico e ácido nítrico/ácido sulfúrico e, também foram usados nanotubos de carbono dopados com nitrogênio. Foram também processadas amostras contendo nanotubos de carbono de paredes múltiplas incorporados em matriz de zircônia obtida pelo método sol-gel. Para aplicação da alta pressão foi usado um sistema com câmaras do tipo toroidal, utilizando grafite como meio transmissor de pressão. Foram obtidas amostras macroscópicas autossuportadas e com resistência ao manuseio principalmente nas amostras de nanotubos de carbono funcionalizados com ácido nítrico/ácido sulfúrico incorporados em zircônia. Para a caracterização das amostras foram utilizadas as técnicas de Microscopia Eletrônica de Transmissão, Espectroscopia Raman, Difração de Raios X e isotermas de adsorção/dessorção de nitrogênio com as quais foi possível determinar que mesmo após a aplicação de alta pressão/temperatura os nanotubos de carbono não sofrem significativas modificações na sua estrutura e nas suas propriedades morfológicas e texturais, confirmando então que os NTCPM mantém suas características originais, apresentando condições para aplicações em dispositivos. As amostras macroscópicas contendo nanotubos de carbono de paredes múltiplas incorporados em zircônia apresentaram ainda resistência à carga de milhares de vezes o seu peso e comportamento de materiais semi-condutores. / This work presents the application of high pressure and/or high pressure/temperature (4.0 GPa and 400 ° C), on different samples of commercial multi-walled carbon nanotube (MWCNT) to obtain compacted samples. MWCNT were functionalized with nitric acid and nitric acid/sulfuric acid, and also carbon nanotubes doped with nitrogen. MWCNT incorporated in a zirconia matrix obtained by sol-gel method were also processed. For high pressure application it was used a system with the toroidal-type chamber, using graphite as a pressure transmitting medium. Self-supported macroscopic samples were obtained, easy to handle, especially in samples of functionalized carbon nanotubes with nitric and sulfuric acid and also incorporated in zirconia. To characterize the samples it was used Transmission Electron Microscopy, Raman Spectroscopy, X-ray diffraction and nitrogen adsoption/desorption isotherms and it was determined that even after application of high pressure/temperature carbon nanotubes do not suffer significant changes in their structure and in their morphological and textural properties, confirming that the CNT keeps its original characteristics and providing conditions for device applications. The macroscopic samples containing MWCNT incorporated in zirconia also exhibited resistance to load of thousands times its own weight and behavior like semiconductor materials.

Made available in DSpace on 2014-12-17T15:42:16Z (GMT). No. of bitstreams: 1 IzangelaMA_TESE.pdf: 6002351 bytes, checksum: 61a1b03824f174ac0458b386d74608e7 (MD5) Previous issue date: 2012-03-21 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this study five compositions were synthesized zirconia doped with cerium and neodymium ions in the system Ce10-xNdx Zr90O2 with 0,5 ≤ x ≤ 4,0 using the Pechini method. The powders were characterized by thermogravimetric analysis, differential thermal analysis, infrared spectroscopy and X-ray diffraction, with application of Rietveld refinement of the calcination temperatures of 350?C/3h and 30 minutes at 900?C/3h. All compositions stabilized with a mixture of cubic and tetragonal phase zirconia. The samples were pressed into bars and sintered at 1500?C/3h and 1500?C/6h, being characterized by Xray diffraction, with application of the Rietveld refinement, density and porosity using Archimedes method, scanning electron microscopy and resistance the three point bending. It has been observed the increase in strength with increasing sintering temperature for the compositions x = 2,0 and x = 4,0. For x = 2,0 the main phase was the cubic with 92,56% with crystallite size of 0,56 μm, density and porosity of 96,82% from 1,36%. For x = 4,0 was a mixture of cubic and tetragonal phase with 21% and 37,98%, respectively. The crystallite size was 54,21 nm and 49,64 nm with a density porosity of 97,45% and 1,32% respectively. In the analysis of the fracture surface was observed a greater amount of grain fracture intragranular type, which contribute to increase the mechanical strength of the ceramic. Increased addition of the neodymium ion in the crystal lattice of the zirconium showed a nearly linear behavior with increasing mechanical strength of the zirconia ceramic. Was obtained a bending resistance of 537 ? 38 MPa for the composition x = 2,0 predominantly attributed to cubic phase with 92,56% / No presente trabalho foram sintetizadas cinco composi??es de zirc?nia dopada com ?ons c?rio e neod?mio no sistema Ce10-x.Ndx Zr90O2 com 0,5 ≤ x ≤ 4,0 com o uso do m?todo Pechini. Os p?s foram caracterizados por an?lise termogravim?trica, an?lise t?rmica diferencial, espectroscopia na regi?o do infravermelho e difra??o de raios X, com a aplica??o do refinamento de Rietveld nas temperaturas de calcina??o de 350?C/3h e 30 minutos a 900?C/3h. Todas as composi??es estabilizaram com mistura de fase tetragonal e c?bica da zirc?nia. As amostras foram prensadas em forma de barras e sinterizadas a 1500?C/3h e 1500?C/6h, sendo caracterizadas por difra??o de raios X, com a aplica??o do refinamento de Rietveld, densidade e porosidade usando o m?todo de Arquimedes, microscopia eletr?nica de varredura e resist?ncia a flex?o em tr?s pontos. Foi observado o aumento da resist?ncia mec?nica com o aumento da temperatura de sinteriza??o para as composi??es x=2,0 e x=4,0. Para x=2,0 a fase principal foi ? c?bica com 92,56 % com tamanho de cristalito de 0,56 μm, densidade de 96,82 % e porosidade de 1,36 %. Para x=4,0 ocorreu uma mistura da fase tetragonal e c?bica com 21 % e 37,98 %, repectivamente. O tamanho de cristalitos foi de 54,21 nm e 49,64 nm, com densidade de 97,45 % e porosidade de 1,32 %, respectivamente. Nas an?lises da superf?cie de fratura foi observado uma maior quantidade de gr?os com fratura do tipo intragranular, na qual contribuiu para o aumento da resist?ncia mec?nica da cer?mica. O aumento da adi??o do ?on neod?mio na rede cristalina da zirc?nia apresentou um comportamento quase linear com o aumento da resist?ncia mec?nica da cer?mica de zirc?nia. Foi obtida uma resist?ncia a flex?o de 537 ? 38 MPa para a composi??o x=2,0 atribu?da a predomin?ncia da fase c?bica com 92,56 %

Le système barrière thermique (BT) est utilisé pour protéger les aubes de turbines à gaz aéronautiques. Aux températures de fonctionnement, une des causes de l'endommagement du système barrière thermique est la dégradation de la couche céramique isolante en zircone yttriée (8YPSZ : ZrO2 - 4% mol. Y2O3) par corrosion. Celle-ci est due à des dépôts d'oxydes à base de Ca, Mg, Al, Si, appelés CMAS provenant de diverses particules ingérées par le moteur. A haute température (~1200°C), le CMAS fond et s'infiltre dans la microstructure poreuse de la BT, se rigidifie au refroidissement provoquant, à terme, la délamination de la BT. A haute température, la BT subit une corrosion chimique induisant sa dissolution dans le CMAS liquide. L'ensemble de ces deux phénomènes conduit à la perte d'intégrité de la barrière thermique. Le présent travail s'est focalisé sur la compréhension des mécanismes de dégradation chimique en vue de proposer une solution de protection contre l'infiltration par les CMAS. Après expertise d'aubes de turbines de retour de vol, une reproduction de la corrosion de la barrière thermique par un CMAS modèle de type CAS et une étude thermodynamique et cinétique de la dissolution de différents oxydes des systèmes ZrO2 - Y2O3 et ZrO2 - Nd2O3 ont été menées dans le verre silicaté CAS pour comprendre le processus de dissolution de Zr et Y et définir une nouvelle composition de barrière thermique anti-CMAS. Le comportement en corrosion par le CAS de matériaux céramiques denses de compositions ZrO2 - 12% mol Nd2O3 et Zr2Nd2O7 ainsi qu'un revêtement déposé par EB-PVD ((La, Nd)2Zr2O7) a été testée. Les résultats obtenus font apparaître que : i) le CAS réplique le mécanisme de corrosion en service, soit la dissolution-re-précipitation. ii) l'oxyde ZrO2 se dissout progressivement et forme le zircon (ZrSiO4) dans le verre CAS, dès 30 min iii) les dopants (Nd2O3 et Y2O3) conduisent à la formation très rapide, de la phase apatite X8Ca2(SiO4)6O2 (X = Nd ou Y) après réaction avec le verre silicaté. En plus de la phase apatite, Y2O3 forme la phase Ca3Y2Si6O18, qui est instable entre 1300°C et 1400°C. iv) les composés dopés au néodyme (ZrO2 - 12% mol Nd2O3 et Zr2Nd2O7) se dissolvent et conduisent, quasi-spontanément, à la phase apatite Nd8Ca2(SiO4)6O2 ainsi qu'à la re-précipitation de grains de ZrO2 appauvris en néodyme. v) malgré la présence de Y2O3, les composés ZrO2 - 4% mol Y2O3, ZrO2 - 10% mol Y2O3 ne conduisent qu'à la re-précipitation de la zircone appauvrie en Y2O3. L'absence de phases secondaires notamment, la phase apatite, pourrait expliquer l'infiltration facile du CMAS dans la microstructure de la barrière thermique en zircone yttriée. vi) l'inhibition avérée de l'infiltration du CAS dans la microstructure poreuse de couches céramiques de nouvelles compositions semble être due à la formation rapide d'une couche superficielle fine et dense, constituée de zircone appauvrie en dopant et de phase apatite / Thermal barrier coating (TBC) system is used to protect aeronautical gas turbine blades. At operating temperatures, one of the damaging causes of thermal barrier system is the degradation of the insulating ceramic layer in zirconia (8YPSZ: ZrO2 - 4 mol %. Y2O3) by corrosion. The corrosion is due to calcium - magnesium alumino-silicates (CMAS) deposits from various particles ingested by the engine. At high temperature (~ 1200°C), the molten CMAS infiltrates the porous microstructure of the thermal barrier leads to i) the chemical dissolution of the thermal barrier zirconia and ii) the delamination of the TBC after cracking at low temperature due to the mismatch of CTE of the solid oxides constituting the CMAS and TBC. This study has contributed to understanding the mechanisms of chemical degradation in order to propose a solution to protect against infiltration by CMAS. After expertise of ex-service turbine blades, a reproduction of the thermal barrier corrosion by model CMAS (CAS) and thermodynamic and kinetic study of the solubility of different oxides of both ZrO2-Y2O3 and ZrO2-Nd2O3 systems were performed in the silicate glass (CAS) in order to understand the mechanism of Zr and Y dissolution and to define a new composition of TBC. The corrosion by the CAS of dense ceramic (ZrO2 - 12 mol% Nd2O3 and Zr2Nd2O7) and of a EB-PVD coating (La, Nd)2Zr2O7)was studied. The results obtained show that: i) CAS replicates the corrosion mechanism, i.e. dissolution-re-precipitation reaction ii) ZrO2 oxide dissolves gradually and forms zircon (ZrSiO4) in the glass after 30 min iii) (Nd2O3 and Y2O3) oxides lead very rapidly to the apatite X8Ca2(SiO4)6O2 (X = Nd, Y) phase formation, after reaction with silicate glass. In addition to the apatite phase, Y2O3 forms Ca3Y2Si6O18 phase, which is unstable at 1300°C and 1400°C iv) the compounds doped with Nd2O3 (ZrO2 - 12 mol% Nd2O3 and Zr2Nd2O7) dissolve and form almost spontaneously, the apatite Nd8Ca2(SiO4)6O2 phase and the ZrO2 depleted in Nd2O3 grains v) Although Y2O3 is a constitutent of the compounds ZrO2 - 4 mol% Y2O3, ZrO2 - 10 mol% Y2O3, the chemical corrosion of these compounds leads only to the re-precipitation of zirconia depleted Y2O3. The absence of secondary phases, particularly the apatite phase may explain the easy CMAS infiltration in the microstructure of the 8YPSZ thermal barrier vi) inhibition of CAS infiltration into the porous microstructure of ceramic layers of new compositions seems to be due to the rapid formation of a thin and dense layer, consisting in Nd-depleted zirconia and apatite phase

Os materiais à base de céria (CeO2) e zircônia (ZrO2) estão presentes em diversas aplicações tecnológicas, destacando-se como anodo de células de combustível de óxido sólido (SOFC) e em catálise, tanto para a produção de hidrogênio, como na automotiva (Three-Way Catalysis). A solução sólida ZrxCe1-xO2- é de especial interesse, pois apresenta melhor estabilidade térmica e maior capacidade de armazenamento de oxigênio (OSC), quando comparada com os óxidos não dopados. Os materiais mesoporosos (poros de 2 a 50 nm) possuem elevada área superficial e permeabilidade a gases, características estas importantes para o desempenho das SOFCs e dos processos de catálise. Neste trabalho, zircônia-céria (Zr0,1Ce0,9O2-) mesoporosa foi sintetizada pelo processo sol-gel, utilizando, como precursores, os cloretos inorgânicos (ZrCl4 e CeCl3.7H2O), o copolímero em bloco P123 (PEO20PPO70PEO20) como direcionador de estrutura e o TIPB (tri-isopropil-benzeno) como agente dilatador. A solução passou por tratamento hidrotérmico durante 48h a 80°C, com posterior calcinação a 400°C para a remoção do polímero, resultando no óxido cristalizado. Na análise foram utilizadas as técnicas: difração de raios X em alto ângulo (XRD), espalhamento de raios X a baixo ângulo (SAXS), isotermas de adsorção de nitrogênio (NAI) e microscopia eletrônica de varredura e transmissão (SEM e TEM). Os resultados mostraram que o material possui elevada área superficial (110m2/g), mesoporos de várias dimensões, atingindo valores médios em torno de 30 nm, fase majoritariamente cúbica Fm3m e, em menor proporção, tetragonal P42/nmc. As micrografias revelaram que o óxido está totalmente nano-cristalizado, com os poros tipo fendas e uma mesoporosidade secundária com distribuição de tamanhos menor e mais estreita. Quatro amostras foram sintetizadas com diferentes razões em massa TIPB/P123 (0, 1, 2 e 4), de forma que foi possível verificar um aumento na dimensão dos poros devido à inclusão do dilatador. As demais propriedades estruturais e morfológicas mantiveram-se inalteradas entre todas as amostras, mesmo com diferentes quantidades de TIPB. / The ceria (CeO2) and zirconia (ZrO2) based materials are present in several technological applications, mainly as Solid Oxide Fuel Cells (SOFC) anodes and catalysts, for hydrogen production and automotive converter (Three-Way Catalysis). The solid solution ZrxCe1-xO2- has attracted special attention, since it shows better thermal stability and higher oxygen storage capacity (OSC), if compared to the non-doped oxides. The mesoporous materials (pores of 2 to 50 nm) show high surface area and gas permeability, important properties for SOFCs and catalysts efficiency. In this work, mesoporous ceria-zirconia (Zr0,1Ce0,9O2-) was synthesized by a sol-gel route using inorganic chlorides (ZrCl4 e CeCl3.7H2O) as precursors, block copolymer P123 (PEO20PPO70PEO20) as template and TIPB (tri-isopropyl-benzene) as swelling agent. The solution was submitted to hydrothermal treatment for 48h at 80°C and calcined at 400°C to remove the template, resulting in the crystallized oxide. The characterization was performed by X-ray diffraction at high angles (XRD), small angle X-ray scattering (SAXS), nitrogen adsorption isotherms (NAI) and transmission and scanning electron microscopy (TEM and SEM). The results showed that the material has high surface area (110m2/g), a wide pore size distribution with mean values around 30 nm, predominant cubic phase Fm3m and, in less quantity, tetragonal P42/nmc. The micrographs revealed that the oxide is totally nano-crystallized, having pores with slit shape and a secondary smaller mesoporosity with a narrow size distribution. Four samples were produced with different TIPB/P123 mass rate (0, 1, 2, 4), therefore was possible to verify the pore size expansion due to the swelling addition. The structural and morphological properties remained unchanged, even with different quantities of TIPB.

Nanocompósitos de Al2O3/ZrO2 apresentam-se promissores para serem utilizados como biomateriais, por promoverem melhorias significativas quanto à homogeneidade microestrutural, propriedades mecânicas e serem biologicamente inerte. Dentre as técnicas capazes de tornar seu desempenho biológico mais adequado, o recobrimento biomimético tem se destacado, sendo que sua eficiência pode ser melhorada a partir de prévios tratamentos superficiais. Nesse sentido, o objetivo desse trabalho foi estudar a adesão e a uniformidade do revestimento de fosfato de cálcio em nanocompósitos de Al2O3 contendo 5% em volume de inclusões nanométricas de ZrO2. Para isso, nanocompósitos foram conformados, sinterizados, tratados quimicamente com soluções de H3PO4, HNO3 e NaOH e por plasma em diferentes condições de processo: 20%N2-80%H2, 40%N2-60%H2, 40%N2-40%H2-20%O2, 30%N2-50%H2-20%O2, 100%N2 e 100%O2 e recobertos biomimeticamente com soluções que simulam o plasma sanguíneo (SBF 1,5x e 5,0x) nos tempos de 7, 14, 21 e 28 dias de incubação. A partir dos resultados obtidos pode-se observar que os prévios tratamentos superficiais promoveram variações na rugosidade média superficial (Ra) entre 0,045 e 0,079 µm. Além disso, independentemente do tratamento superficial, observou-se a formação de apenas três fases de fosfatos de cálcio: hidroxiapatita (HA), α-fosfato tricálcico (α-TCP) e β-fosfato tricálcico (β-TCP). Observou-se ainda, que o percentual das fases formadas variou de acordo com o tratamento, sugerindo a possibilidade de controlar a razão TCP:HA. Nos resultados obtidos pelo teste de riscamento observou-se que tratamentos realizados com plasma, H3PO4 e HNO3 aumentaram a carga crítica (Lc) entre 2,0 e 2,9N, melhorando assim a aderência da camada de fosfato de cálcio formada. Os testes de proliferação celular utilizando linhagem de células de hamster chinês (CHO) demonstraram que os nanocompósitos tratados com H3PO4, HNO3 e NaOH e recobertos biomimeticamente com SBF 5,0x são biocompatíveis. / Nanocomposite Al2O3/ZrO2 have to be promising to be used as biomaterials for promoting significant improvements in the microstructural homogeneity, mechanical properties and be biologically inert. Among the techniques to make it more useful biological performance, the biomimetic coating has been highlighted, and its efficiency can be improved from previous surface treatments. In this sense, the objective of this work was to study the adhesion and uniformity of calcium phosphate nanocomposite coating of Al2O3 containing 5% by volume of nanometric inclusions of ZrO2. For this nanocomposites were shaped, sintered, chemically treated with solutions of H3PO4, HNO3 and NaOH, and plasma in different process conditions: 20%N2-80%H2, 40%N2-60%H2, 40%N2-40%H2-20%O2, 30%N2-50%H2-20% O2, 100% N2 and 100%O2 and covered with solutions biomimetic that simulate the blood plasma (SBF 1.5x and 5.0x) in the times of 7, 14, 21 and 28 days of incubation. From the results obtained it can be seen that prior surface treatments promoted variations in average surface roughness (Ra) from 0.045 to 0.079 micrometers. Furthermore, regardless of surface treatment, formation of the observed only three-phase calcium phosphate: hydroxyapatite (HA), tricalcium α-phosphate (α-TCP) and β-tricalcium phosphate (β-TCP). It was also observed that the percentage of phases formed varied according to the treatment, suggesting the possibility of controlling the ratio TCP:HA. In the results obtained by scratching test was observed that plasma treatments performed, HNO3 and H3PO4 increased the critical load (Lc) between 2.0 and 2,9N, thereby improving the adhesion of the calcium phosphate layer is formed. Cell proliferation assays The strain using chinese hamster cells (CHO) have demonstrated that nanocomposites treated with H3PO4, HNO3 and NaOH, and coated with solution biomimetic SBF 5.0x are biocompatible.

O principal objetivo deste trabalho foi estudar a influência do tratamento superficial com laser de femtossegundo em amostras de alumina e compósito de alumina-zircônia estabilizada com ítria para depósito e aderência de apatita. Os resultados obtidos mostraram que houve a formação de apatita sobre as superfícies das amostras que foram texturizadas com laser de femtossegundo e em seguida imersa em 1,5 SBF. Este método biomimético pôde, por conseguinte, tornar estas cerâmicas bioativas. Também houve a formação de apatita na superfície das amostras sem o tratamento a laser. Os efeitos da texturização na superfície para as diferentes cerâmicas e a influência do tempo de imersão em 1,5 SBF são discutidos, a fim de determinar a condição ótima para estimular a deposição e a adesão da apatita na superfície dos materiais. Finalmente, os resultados obtidos das diferentes análises são comparados. A adesão da hidroxiapatita é essencial para interação com o substrato e depende das propriedades das superfícies dos materiais. A qualidade desta adesão influenciará sua morfologia e a capacidade futura de osseointegração. As características de superfície dependem da química de superfície, energia de superfície e topografia de superfície. Geralmente, a reatividade de superfície e energia de superfície pode ser influenciada pelas características de molhabilidade, influenciando o desempenho de biomateriais. A adesão e crescimento da apatita depositada também é função da rugosidade superficial. O tratamento superficial com laser de femtossegundo melhora consideravelmente a adesão da apatita obtida pelo recobrimento biomimético nas superfícies dos materiais. / The main objective of this work was to study the influence of femtosecond laser surface treatment on samples of alumina and composite of zirconia-alumina yttria stabilized for deposit and adhesion of apatite. The results showed that there was apatite formation on the surfaces of the samples that have been textured with femtosecond laser and then immersed in SBF 1.5. This biomimetic method can therefore make these bioactive ceramics. There was also the formation of apatite in the samples without laser treatment. The effects of texturing surface for the different ceramics and the influence of immersion time in SBF 1.5 are discussed in order to determine the optimal conditions to promote the deposition and the adhesion of the apatite in the material`s surface. Finally, the results of the different analyzes are compared. The adhesion of hydroxyapatite is essential for interaction with the substrate and depends on the properties of material´s surface. The quality of this adhesion will influence their morphology and the future ability of osseointegration. The surface characteristics depend on the surface chemical, surface energy and surface topography. Generally, the reactivity of surface and the energy of surface can be affected by wetting characteristics influencing the performance of biomaterials. The adhesion and growth of apatite deposited is also a function of surface roughness. The femtosecond laser surface treatment greatly improves the adhesion of apatite obtained by biomimetic coating on the surfaces of materials.

Metal implants are a type of hard tissue replacement currently used. Metals used for implants include: stainless steel, titanium, chrome, and cobalt alloys. Such implants often fail at the interface with bone. Metal implants fail when the surface of the implant is coated with an osteoconductive material. An osteoconductive material provides scaffolding for cellular migration, cellular attachment, and cellular distribution. A reason for metal implant failure could be the vastly different material properties than bone. Motivation for the research was to find a suitable bone substitute other than metal. Materials considered were: zirconia toughened alumina, carbon fiber reinforced epoxy, and glass fiber reinforced epoxy. Those materials have been used in previous biological applications and can be cast into complex configurations. Objectives of the study were to compare material properties of the composites to bone. A method to create porosity was then tested in the material that was similar to bone in critical material property. Some of the materials were statistically similar to bone in yield strength. Method to create interconnected porosity in those materials resulted in 49% void space.

La fusion sélective par laser est un procédé de la technologie de fabrication rapide de plus en plus utilisé dans l’industrie automobile, aéronautique, médicale, etc. Selon le principe de la fabrication rapide, la pièce est fabriquée couche par couche en fusionnant et soudant les particules fines par laser. Actuellement, les principaux matériaux utilisés sont les métaux métalliques ou les polymères. Le faible ou modeste point de fusion de ces matériaux conduit à une mise en œuvre par laser relativement facile. Cependant, en raison de leur point de fusion élevé, de la forte résistance à haute température et de la faible conductivité thermique, l’utilisation de matériaux céramiques est limitée dans la technologie de fusion laser sélective. Cette étude explore la fusion laser sélective de zircone stabilisée par yttrine avec un laser à fibre de longueur d’onde d’environ 1 µm. L’influence de différentes puissances de laser et de différentes vitesses de balayage sur la microstructure et la déformation de l’échantillon a été étudiée, et la densité relative et la microdureté ont été mesurées. Notamment, l’effet de différentes températures de préchauffage sur la microstructure sera étudié. En même temps, la structure cristalline céramique et la transformation des phases pendant le procédé de prototypage rapide ont été analysées. Les résultats expérimentaux montrent qu’il est possible de fondre complètement de la poudre YSZ avec un laser à fibre NIR, et avec l’optimisation des paramètres de fabrication, la densité relative de l’échantillon peut atteindre 91 %. Il est inévitable de voir se former des fissures et des pores dans les pièces fabriquées du fait de l’hétérogénéité de la distribution de l’énergie du laser. Cette distribution de l’énergie peut être améliorée grâce à l’optimisation des paramètres ; les longueurs de fissure peuvent être contrôlées et maîtrisées par un préchauffage du lit de poudre. Notamment, à haute température (1500°C, 2000°C et 2500°C) de préchauffage, la fissure verticale continue devient désordonnée et courte. Une transformation de la structure monoclinique et cubique en structure tétragonale s’est produite pendant le processus de fabrication. / Selective laser melting is a rapid manufacturing process coming from the rapid prototyping technology, which is widely used in the automotive, aeronautical, medical industry etc. According to the principle of rapid manufacturing, the piece is manufactured layer by layer through the laser sintering or melting the fine powder. Currently, the main powder materials used are metal or polymer materials. The low melting point of these materials facilitates the melting process. However, duo to the high melting point, strong strength at high temperature and low thermal conductivity the application of ceramic materials is limited in the technology of selective laser melting. In this study, selective laser melting of the ceramic yttria stabilized zirconia by a 1μm wavelength fiber laser was explored. The influence of different laser powers and different scanning velocities on the microstructure and the deformation were analyzed, then the micro-hardness and relative density were measured. In particular, the effect of different preheat temperatures on microstructure was investigated. At the same time, the crystal structure and phase transformation during the fabrication were analyzed. Experimental results show that YSZ powder can be completely melted by the near IR fiber laser. With the optimization of the manufacturing parameters, the relative density of sample could reach 91 %. The forming of cracks and pores in the manufactured parts is rarely avoid due to the heterogeneity of distribution of energy. The energy distribution could be improved by optimizing the parameters and the crack lengths can be controlled by preheating the powder bed. In particular, the high temperature (1500 ℃, 2000 ℃ and 2500 ℃) lead the continuous vertical crack becomes messy and short. The transformation of monoclinic and cubic crystal to tetragonal crystal can be observed during the fabrication.

Thermal mismatch between different components of a system could be sources of problems like residual stress induced cracking, thermal fatigue or even optical misalignment in certain high technology applications. Use of materials with tailored thermal expansion coefficient is a counter-measure to overcome such problems. With its negative thermal expansion coefficient zirconium tungstate (ZrW2O8) is a candidate component to be used in synthesis of composites with controlled thermal expansion coefficient (CTE). ZrW2O8 is typically produced by solid-state reaction between zirconium oxide and tungsten oxide at 1200oC. However, it has been demonstrated that ZrW2O8 can also be synthesized using wet chemical techniques, which provide a superior chemical homogeneity that often extents down to the atomic scale, and the convenient means of controlling nucleation and growth of the primary crystallites. With the commonly adopted wet chemical approaches, it is possible to crystallize particles with sizes in the submicrometer range at temperatures as low as 600 oC or even lower. In these studies, precursors are aged either below 100 oC (7 days &ndash / 3 weeks), or at 160-180 oC under hydrothermal conditions (1&ndash / 2 days). Besides the obvious disadvantage in the ageing steps, use of tungsten sources with high cost in all approaches, constitutes the other disadvantage. Production of composites with tunable controlled thermal expansion (CTE) has been achieved by blending negatively and positively expanding materials in different proportions. In majority of these studies composites have been produced by conventional sintering methods. Spark Plasma Sintering (SPS) is a recent technique / in which sintering can be achieved at relatively low temperatures in short durations. There is only one study made by Kanamori and coworkers on the use of SPS in sintering of a composite, in which ZrW2O8 is one of the constituents [1]. This study aims the synthesis of ZrW2O8 particles and composites that possess tunable or zero CTE. A novel precursor recipe for ZrW2O8 synthesis was developed. In preparation of the precursor a total of 2 days of ageing and a temperature less than 100 oC was used. It was developed using a cost-effective tungsten source, namely tungstic acid and its final pH was lower than 1. The particles obtained from &lsquo / unwashed&rsquo / procedure had sizes in micrometer range, while those obtained from &lsquo / washed&rsquo / case had sizes in the range of 400-600 nm. These precursors could readily be crystallized at 600 oC, which in turn provided the desired particle sizes for composite applications. Experimental details on the precursor development are hereby presented with a discussion on the effects of solution parameters (i.e. solubility of tungstic acid, adjustment of the stoichiometry, ageing time) on the phase purity of the fired product. Zirconium oxide (ZrO2) has positive vi thermal expansion, therefore ZrW2O8/ZrO2 was selected as the composite system, and for their synthesis both conventional and spark plasma sintering methods were experimented. Composition ranges that provide composites with almost zero CTE&rsquo / s were determined. The composite having a composition of containing 35% ZrW2O8, 65% ZrO2, and 35 w/o Al2O3 and sintered at 1200 oC for 24 hours had an expansion coefficient of 0.20 x 10-6/K for conventional method, while the one having a composition of 55% ZrW2O8, 45% ZrO2 and sintered at 1000 oC for 5 minutes had an expansion coefficient of 0.94 x 10-6/K for spark plasma sintering method. For characterization of the products X-ray diffraction (XRD), scanning electron microscopy (SEM), photon correlation spectroscopy (PCS), and thermal and dilatometer analyses (DTA/TGA/DMA) were used.