Made available in DSpace on 2014-12-17T14:06:54Z (GMT). No. of bitstreams: 1 ClaudiaAMS_DISSERT.pdf: 2577371 bytes, checksum: 741bbb91aaccd5dd4b233f1b8017a831 (MD5) Previous issue date: 2010-03-29 / The continuous advances in ceramic systems for crowns and bridges infrastructure getting researchers and manufacturers looking for a material that has good mechanical properties and aesthetic. The purpose of this study was to verify in which composition and sintering temperature the ceramic system for infrastructure composed of alumina and zirconia would have the best mechanical properties. With this objective we made in UFRN laboratories 45 test bodies in the form of rectangular bars with the following dimensions: 30mm x 8mm x 3mm, where we separated by the sintering temperature: 1200?C, 1300?C and 1400?C, and by comp osition: 33% Zirconia + 67% Alumina; 50% Zirconia + 50% Alumina and 25% Zirconia + 75% Alumina, these test bodies were not infiltrated with glass. Also, were made nine test bodies by a technical from a laboratory with a commercial ceramic system: in the Ceram Zirc?nia (Vita - Zahnfabrik) with the following dimensions: 20mm x 10mm x 0.5mm, these test bodies following all recommendations of the manufacturer and were infiltrated with glass. Were realized optical and electronic microscopy analyses, hardness testing, resistance to bending in three points, porosity and bulk density. After analysis of the results we verified that with the increasing of sintering temperature, increased the value of resistance to bending, but with the same temperature there was no significant difference between the different compositions, samples made with the commercial ceramic that were infiltrated, presented a resistance to bending six times greater than the samples sintered to 1400?C and which have not been infiltra ted. There was no significant difference between the values of apparent porosity for the samples made in UFRN laboratories, but the samples of commercial ceramic obtained 0% in porosity apparent value. In tests of Rockwell Hardness there is an increase in the value of Hardness, with the increase of sintering temperature for the samples not infiltrated. Samples infiltrated showed similar values as the samples sintered in 1400?C. There was no significant difference between the values of apparent density among samples manufactured in UFRN laboratories and samples made with a commercial ceramic / Os avan?os constantes dos sistemas cer?micos para infra-estruturas de coroas e pontes fazem com que os pesquisadores e fabricantes busquem um material que tenha boas propriedades mec?nicas e est?ticas. O intuito deste trabalho foi verificar em qual composi??o e temperatura de sinteriza??o o sistema cer?mico a base de alumina e zirc?nia para infra-estrutura teria as melhores propriedades mec?nicas. Com este objetivo confeccionamos nos laborat?rios da UFRN 45 corpos-e-prova em forma de barras retangulares com as seguintes dimens?es: 30mm x 8mm x 3mm, onde os separamos por temperatura de sinteriza??o: 1200?C, 1300?C e 1400?C; e por composi??o: 33% Zirc?nia + 67% Alumina; 50% Zirc?nia + 50% Alumina e 25% Zirc?nia + 75% Alumina, estes corpos-de-prova n?o foram infiltrados com vidro. Foram confeccionados ainda nove corpos- e-prova por um t?cnico de laborat?rio com um sistema cer?mico comercial o In Ceram Zirc?nia (Vita Zahnfabrik) com as seguintes dimens?es: 20mm x 10mm x 0,5mm, estes corpos-de-prova seguiram todas as recomenda??es do fabricante e foram infiltrados com vidro. Foram realizadas an?lises por microscopia ?tica e eletr?nica, ensaios de dureza, de resist?ncia ? flex?o em tr?s pontos, porosidade e densidade aparente. Ap?s a an?lise dos resultados verificamos que com o aumento da temperatura de sinteriza??o, aumentamos o valor da resist?ncia ? flex?o, sendo que dentro da mesma temperatura n?o houve diferen?a significante entre as diferentes composi??es, as amostras confeccionadas com a cer?mica comercial e que foram infiltradas apresentaram uma resist?ncia ? flex?o seis vezes maior que as amostras sinterizadas ? 1400?C e que n?o foram infiltradas. N?o houve diferen?a significante entre os valores da porosidade aparente para as amostras confeccionadas nos laborat?rios da UFRN, j? as amostras da cer?mica comercial obtiveram um valor de 0% de porosidade aparente. Nos ensaios de Dureza Rockwell verifica-se um aumento no valor da Dureza, com o aumento da temperatura de sinteriza??o das amostras n?o infiltradas. As amostras infiltradas apresentaram valores similares aos das amostras sinterizadas ? 1400?C. N?o houve diferen?a significante entre os valores de densidade aparente entre as amostras confeccionadas nos laborat?rios da UFRN e as amostras confeccionadas com a cer?mica comercial

Made available in DSpace on 2014-12-17T14:07:17Z (GMT). No. of bitstreams: 1 LauraXL_DISSERT.pdf: 3047950 bytes, checksum: 570af1df35d3161d6677ac6ec832e390 (MD5) Previous issue date: 2013-12-16 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Recent studies are investigating a new class of inorganic materials which arise as a promising option for high performance applications in the field of photoluminescence. Highlight for rare earth (TR +3 ) doped, which have a high luminous efficiency, long decay time and being able to emit radiation in the visible range, specific to each element. In this study, we synthesized ZrO2: Tb +3 , Eu +3 , Tm +3 nanoparticles complex polymerization method (CPM). We investigated the influences caused by the heat treatment temperature and the content of dopants in zirconia photoluminescent behavior. The particles were calcined at temperature of 400, 500 and 600 ? C for two hours and ranged in concentration of dopants 1, 2, 4 and 8 mol% TR +3 . The samples were characterized by thermal analysis, X-ray diffraction, photoluminescence of measurements and uv-visible of spectroscopies. The results of X-ray diffraction confirmed the formation of the tetragonal and cubic phases in accordance with the content of dopants. The photoluminescence spectra show emission in the region corresponding simultaneous to blue (450 nm), green (550 nm) and red (615 nm). According to the results, ZrO2 particles co-doped with rare earth ions is a promising material white emission with a potential application in the field of photoluminescence / Estudos recentes investigam uma nova classe de materiais inorg?nicos que surgem como uma op??o promissora em aplica??es de alto desempenho no campo da fotoluminesc?ncia. Destaque para f?sforos dopados com ?ons de terras raras (TR +3 ), que possuem uma alta efici?ncia luminosa, um longo tempo de decaimento e por serem capazes de emitir radia??es na faixa do vis?vel, espec?ficas de cada elemento. Neste trabalho, foram sintetizadas nanopart?culas de ZrO2:Tb +3 , Eu +3 , Tm +3 pelo m?todo de polimeriza??o dos complexos (MPC). Foram investigadas as influ?ncias causadas pela temperatura de tratamento t?rmico e pelo teor dos dopantes no comportamento fotoluminescente da zirc?nia. As part?culas foram calcinadas nas temperaturas de 400, 500 e 600?C durante duas horas e a concentra??o dos dopantes variou em 1, 2, 4 e 8% mol TR +3 . As amostras foram caracterizadas por an?lises t?rmicas (TG/ DSC), difra??o de raios X (DRX), medidas de fotoluminesc?ncia (FL) e espectroscopia na regi?o do UV-Vis?vel (UV-vis). Os resultados de difra??o de raios X confirmaram a forma??o das fases tetragonal e c?bica de acordo com o teor de dopantes. Os espectros de fotoluminesc?ncia apresentam emiss?es simult?neas correspondentes na regi?o do azul (450 nm), do verde (550 nm) e do vermelho (615 nm). De acordo com os resultados obtidos, as part?culas de ZrO2 codopadas com ?ons de terras raras apresentam-se como um material promissor para emiss?o no branco com um potencial de aplica??o no campo da fotoluminesc?ncia

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-10-11T20:39:41Z No. of bitstreams: 1 MichelineDosReisAraujo_TESE.pdf: 2152789 bytes, checksum: 46d89fee61e001b69b0444ee74632831 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-10-14T00:04:59Z (GMT) No. of bitstreams: 1 MichelineDosReisAraujo_TESE.pdf: 2152789 bytes, checksum: 46d89fee61e001b69b0444ee74632831 (MD5) / Made available in DSpace on 2016-10-14T00:04:59Z (GMT). No. of bitstreams: 1 MichelineDosReisAraujo_TESE.pdf: 2152789 bytes, checksum: 46d89fee61e001b69b0444ee74632831 (MD5) Previous issue date: 2016-04-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Neste trabalho foram conformados substratos cer?micos de zirc?nia nanoparticulada estabilizada com 3 mol% de ?tria pelo processo de colagem de fitas (?tape casting?) em meio aquoso em uma faixa de espessura de 100 e 150 ?m, os quais apresentam grande interesse tecnol?gico para aplica??es eletroeletr?nicas. Suspens?es para a colagem de fitas foram preparadas em duas diferentes composi??es: 20% ligante - 22% solvente e 25% ligante - 17% solvente (em peso). Uma emuls?o acr?lica comercial serviu como ligante. A estabilidade da suspens?o de zirc?nia estabilizada com ?tria foi analisada por medida de reologia, atrav?s de curvas de viscosidade. Ambas as suspens?es apresentaram comportamento pseudopl?stico, o que ? desej?vel para a t?cnica de colagem de fitas. Ap?s o processo de colagem realizou-se prensagem uniaxial em diferentes temperaturas (40?C e 60?C) e tempos (5 e 10 minutos) nas fitas cer?micas, para a conforma??o dos laminados. An?lise T?rmica Diferencial (ATD) e Termogravim?trica (ATG) foram realizadas para se definir os par?metros para a sinteriza??o dos laminados. Ap?s a sinteriza??o ? 1500?C foram realizados ensaios de Difra??o de Raios X, densidade e porosidade, resist?ncia mec?nica ? flex?o, microdureza Vickers e Microscopia Eletr?nica de Varredura (MEV) para se avaliar as propriedades dos laminados obtidos al?m de analisar o tamanho e crescimento do gr?o. As amostras laminadas em menores temperaturas de prensagem apresentaram delamina??o entre as interfaces das fitas cer?micas, por?m sem influ?ncia significativa no comportamento mec?nico destes materiais. A composi??o com maior teor de ligante apresentou maiores valores de resist?ncia mec?nica devido ? maior quantidade deste componente propiciar melhorias no processo de conforma??o dos laminados. / Various processing techniques are based on the suspension of ceramics particles in an aqueous or non-aqueous media. One of these techniques is called tape casting, which need of a stabilized suspension with high concentration of solids and adequate rheological behavior, which can define if a process route is viable or not. Typical tape cast slurries are prepared by dispersion of a powder in an organic or nonorganic solvent, with a dispersant, followed by the addition of binders, plasticizers, and other additives. These slurries are cast through a so-called doctor blade over a flat carrier. In this study were shaped ceramic substrates of nanoparticulate zirconia stabilized with 3 mol% yttria by tape casting process in aqueous medium at thickness range of 100 to 150 micrometers which have great technological interest for applications electro-electronic. Tape casting slurries were prepared with two different compositions: 20% binder ? 22% solvent e 25 % binder - 17% solvent (wt.%). A commercial acrylic emulsion served as binder. The stability of the yttria-stabilized zirconia slurries was analyzed by means of rheological characterization through viscosity curves. Both slurries showed a pseudoplastic behavior, which is desired for tape casting. After the tape casting process was made uniaxial pressing at different temperatures (40?C and 60?C) and time (5 and 10 minutes) in ceramic tapes for forming the laminates. Differential Thermal Analysis (DTA) and thermogravimetry (TGA) were performed to define the parameters for the sintering of the laminate. After sintering at 1500?C were performed X Ray Diffraction (XRD), density and porosity, flexural strength, microhardness and Scanning Electron Microscopy (SEM) to evaluate the properties of the obtained laminates. Laminated samples at lower press temperatures showed delamination between the interfaces of the ceramic tapes, however no significant influence on the mechanical behavior of these materials. The composition with higher binder content shows higher values of mechanical resistance due the greater amount of this component provide improvements in the laminate forming process

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-03-14T20:59:53Z No. of bitstreams: 1 RobertaAraujoCavalcanteDeMenezes_DISSERT.pdf: 6114869 bytes, checksum: 5634897f00326b7f5e283a724bdffbb4 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-03-15T20:15:24Z (GMT) No. of bitstreams: 1 RobertaAraujoCavalcanteDeMenezes_DISSERT.pdf: 6114869 bytes, checksum: 5634897f00326b7f5e283a724bdffbb4 (MD5) / Made available in DSpace on 2017-03-15T20:15:24Z (GMT). No. of bitstreams: 1 RobertaAraujoCavalcanteDeMenezes_DISSERT.pdf: 6114869 bytes, checksum: 5634897f00326b7f5e283a724bdffbb4 (MD5) Previous issue date: 2016-08-05 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / O a?o EUROFER ? uma liga que foi desenvolvida para aplica??o em reator nuclear, apresentando propriedades mec?nicas compat?veis com essa utiliza??o, desde que, a temperatura de servi?o n?o ultrapasse 550?C, devido a sua baixa resist?ncia a flu?ncia. Visando melhorar as propriedades mec?nicas do EUROFER, estudos est?o sendo desenvolvidos adicionando ?tria, e o com isso tem-se um comp?sito com uma maior temperatura de trabalho, de aproximadamente 650?C. Dentro desse contexto, neste trabalho, estudou-se o efeito da adi??o de zirc?nia e da atmosfera de sinteriza??o na microestrutura e propriedades mec?nicas do a?o EUROFER processado atrav?s das etapas da metalurgia do p?. Inicialmente, foram adicionados 5%, em peso, de zirc?nia ao a?o, e realizada a moagem de alta energia em um moinho planet?rio por 5 horas com velocidade de 400rpm. Em seguida, os p?s particulados foram recozidos em forno resistivo a v?cuo a temperatura de 950?C por 30 minutos para uma melhor compacta??o. Os p?s de EUROFER puro e de EUROFER com 5% de zirc?nia mo?dos forma compactados a frio sob uma press?o uniaxial de a??o dupla com carga de 700 MPa, em uma matriz met?lica de cavidade cil?ndrica de 5 mm de di?metro. Os compactados a verde foram sinterizados em forno resistivo a v?cuo e em forno resistivo com fluxo de arg?nio a uma temperatura de 1300?C por 60 minutos com taxa de aquecimento de 10?C/min. Os p?s de partidas e os p?s mo?ods foram caracterizados por: distribui??o do tamanho de part?culas, fluoresc?ncia de raio-X (FRX), difra??o de raio-X (DRX) com refinamento, microscopia eletr?nica de varredura (MEV) e espectroscopia de energia dispersiva (EDS). E, as amostras sinterizadas foram caracterizadas por difra??o de raio-X (DRX), microscopia ?ptica (MO), microscopia eletr?nica de varredura (MEV) e espectroscopia de energia dispersiva (EDS); e, tamb?m, analisadas por ensaios de densidade, dilatometria e microdureza. Foi observado que a microestrutura inicial do EUROFER n?o se manteve durante o processamento do material, e, com isso, as suas propriedades mec?nicas apresentaram varia??es. Dessa forma, os resultados de microdureza obtidos para as amostras com adi??o de zirc?nia (fluxo de arg?nio 253,4HV e v?cuo 119,35HV), foram maiores que os de a?o puro sinterizados (fluxo de arg?nio 119,25HV e v?cuo 84,65HV). E, al?m disso, as amostras sinterizadas no forno resistivo com fluxo de arg?nio apresentaram valores de microdureza superiores as das amostras sinterizadas em forno resistivo a v?cuo. / The EUROFER is an alloy steel developed for application in nuclear reactor, with mechanical properties compatible with such a use, since the operating temperature does not exceed 550?C due to its low creep resistance. In order to improve the mechanical properties of EUROFER, studies have been developed by adding yttria, producing a composite with higher working temperature of approximately 650?C. In this work, we studied the effect of adding zirconia and sintering atmosphere on microstructure and mechanical properties of EUROFER steel processed through the steps of powder metallurgy. Initially, wt % zirconia was added to steel and high energy ball milling was performed in a planetary milling for 5 hours at 400rpm. Then the particles were annealed in a resistance vacuum furnace at 950?C for 30 minutes for better compression. The pure EUROFER powder and EUROFER with 5 wt% zirconia cold compacted under a uniaxial double-acting pressure of 700 MPa in a cylindrical metal matrix with a cavity of 5 mm in diameter. The green samples were sintered in resistance vacuum furnace and resistance furnace with argon flow at 1300 ?C for 60 minutes with a heating rate of 10 ?C / min. Primary and milled powders were characterized by particle size distribution analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD) with refinement, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). And the sintered samples were characterized by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS); and also analyzed by density measurement, dilatometry behavior and microhardness. It was observed that the initial microstructure of EUROFER did not maintain during processing of the material, and, therefore, its mechanical properties presented variations. Thus, the results of microhardness obtained for samples with zirconia (argon flow 253,4 HV and vacuum 119,35 HV) were higher than those of sintered pure steel (argon flow and vacuum 119,25HV 84,65HV) . Thus, the results of microhardness obtained for samples with added zirconia (argon flow and vacuum 253,4HV 119,35HV) were higher than those of sintered pure steel (argon flow 119,25 HV and vacuum 84,65 HV). Besides, the samples sintered in the resistance furnace under argon flow had higher hardness than samples sintered in vacuum resistance furnace.

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 %

Made available in DSpace on 2014-12-17T14:06:53Z (GMT). No. of bitstreams: 1 YankelBFC.pdf: 3745387 bytes, checksum: 0a72ac9538c533fa074f31beeeb3660d (MD5) Previous issue date: 2008-12-29 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Ceramics materials have good properties including chemical stability, high hardness and wear resistance. Moreover, due to its fragility, can suffer failure under relatively low levels of tension. Actually zirconia is the material of choice in metal free dental prostheses used in dentistry due its inertia in physiological environment, good bending strength, hardness and fracture toughness. The alumina and mixed tungsten and titanium carbides additions, acting as reinforcement elements in the zirconia matrix, have as their main objective the improvement of mechanical properties of this material. In this work, samples of zirconia, zirconia with 30% wt of alumina and zirconia with 30% wt mixed carbides were analyzed. The samples were sintered by uniaxial hot pressing on 30 MPa pressure, for 1 hour in an argon atmosphere. They were physically characterized by porosity and density measurements, and mechanically by 3-points bending strength and Vickers microhardness. The X-ray diffraction was used for the phase identifications and microstructure was examined by scanning electron microscopy (SEM). The addition of mixed carbides as reinforcement elements in zirconia matrix provides improvements in all properties analyzed in this work. The alumina addition has dropped the zirconia strength, although it caused improvement in other properties / Materiais cer?micos apresentam boas propriedades incluindo estabilidade qu?mica, elevada dureza e resist?ncia ao desgaste. Por outro lado, devido a sua fragilidade, podem sofrer falha sob n?veis de tens?es relativamente baixos. A zirc?nia ? hoje o material de escolha em odontologia para o uso em pr?teses dentais do tipo metal free por ser inerte em meio fisiol?gico, apresentar boa resist?ncia ? flex?o, dureza e tenacidade ? fratura. A adi??o da alumina e dos carbetos mistos de tungst?nio e tit?nio ,atuando como elementos de refor?o na matriz de zirc?nia, t?m como principal objetivo o aperfei?oamento das propriedades mec?nicas deste material. No presente trabalho, foram analisadas amostras de: zirc?nia, zirc?nia com 30% em peso de alumina e zirc?nia com 30% em peso de carbetos mistos. Os corpos de prova foram sinterizados por prensagem a quente uniaxial, sobre press?o de 30 MPa, durante 1 hora em atmosfera de arg?nio. Os mesmos foram caracterizados fisicamente por meio de medidas de porosidade e de densidade, e mecanicamente por resist?ncia a flex?o em 3 pontos e microdureza Vickers. A difra??o de raios X foi utilizada para a identifica??o das fases presentes e a microestrutura foi analisada por microscopia eletr?nica de varredura (MEV). A adi??o dos carbetos mistos como elemento de refor?o da matriz de zirc?nia ocasionou uma melhoria em todas as propriedades analisadas neste trabalho. A adi??o da alumina proporcionou uma queda na resist?ncia mec?nica da zirc?nia, apesar de ter ocasionado melhora nas demais propriedades

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-10T20:12:53Z No. of bitstreams: 1 LarissaBezerraDaSilva_DISSERT.pdf: 3671939 bytes, checksum: 0ded2fa22f6e277a6bf0acd3e16b0455 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-05-12T00:26:21Z (GMT) No. of bitstreams: 1 LarissaBezerraDaSilva_DISSERT.pdf: 3671939 bytes, checksum: 0ded2fa22f6e277a6bf0acd3e16b0455 (MD5) / Made available in DSpace on 2016-05-12T00:26:21Z (GMT). No. of bitstreams: 1 LarissaBezerraDaSilva_DISSERT.pdf: 3671939 bytes, checksum: 0ded2fa22f6e277a6bf0acd3e16b0455 (MD5) Previous issue date: 2014-08-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A efetiva utiliza??o dos recursos naturais diante o acelerado crescimento econ?mico resulta no aumento cont?nuo de res?duos industriais, e para suprimir estes res?duos, um processo de reciclagem ? de prefer?ncia uma solu??o atraente. Durante a usinagem dos blocos de zirc?nia para diversos tipos de implantes odontol?gicos, grande parte do material ? desprendida na forma de p?, que posteriormente ? descartado. A zirc?nia tetragonal estabilizada com 3% em mol de ?tria (Y-TZP) possui uma variedade de aplica??es na ?rea de engenharia e biom?dica devido ? sua ?tima combina??o de resist?ncia, tenacidade ? fratura, condutividade i?nica e baixa condutividade t?rmica. Al?m do dano para o meio ambiente, o desperd?cio deste material resulta em preju?zo financeiro, refletindo em elevado custo final no tratamento para os pacientes. Os materiais de partida utilizados neste trabalho foram dois diferentes p?s do sistema cer?mico ZrO3-Y2O3: zirc?nia comercial nanoparticulada e res?duo de zirc?nia microparticulado. Os p?s foram conformados por prensagem uniaxial e isost?tica e em seguida sinterizadas a 1500, 1550 e 1600 ?C, durante 1 hora. As t?cnicas de granulometria a laser, difra??o de raios X (DRX), e dilatometria foram utilizadas para caracteriza??o do p?. Ap?s sinterizados, foram realizados ensaios de densidade e porosidade, difra??o de raios X (DRX), resist?ncia mec?nica ? flex?o, microdureza Vickers e an?lise de tenacidade ? fratura, e microscopia eletr?nica de varredura (MEV). As amostras compactadas via prensagem isost?tica apresentaram valores de porosidade inferiores a 0,78% e demostraram maior efetividade de compacta??o comparada ? via uniaxial. Foi observado nos difratogramas de raios X, com o aumento da temperatura, a intensidade dos picos da fase monocl?nica diminuiu. A temperatura de sinteriza??o influenciou de forma moderada a microdureza das amostras, demostrando pequenos acr?scimos da dureza at? a temperatura de 1600?C. A resist?ncia ? flex?o do res?duo de zirc?nia aumenta com o aumento da temperatura de sinteriza??o, para ambas as vias de compacta??o, apresentando melhores valores por via isost?tica. / The actual use of natural resources on accelerated economic growth, resulting in continuous increase of industrial waste, and to remove these residues, a recycling process is preferably na attractive solution. During the machining of blocks of zirconia to several types of dental implants, most of the material is loosened as a powder, which is subsequently discarded. The stabilized tetragonal zirconia with 3% yttria (Y-TZP) mol boasts a variety of applications in engineering, and biomedical, because of its great combination of strength, fracture toughness, ionic conductivity and low thermal conductivity. Besides the damage to the environment wasting of the material resulting in financial loss, reflecting the high final cost of medical treatment for patients. The starting materials used in this work were two different powders ZrO3-Y2O3ceramic system: commercial zirconia nanoparticulate and microparticulate zirc?nia residue. The powder was uniaxially and isostatically pressed and then sintered at 1500, 1550 and 1600 ? C for 1 hour. The techniques of laser granulometry, X-ray diffraction (XRD) and dilatometry were used for powder characterization. After sintering were performed density and porosity tests, X-ray diffraction (XRD), Flexural strength, microhardness and fracture toughness analysis, and scanning electron microscopy (SEM). Samples compacted via isostatic pressing showed values less than 0.78% porosity and demonstrated greater effectiveness compared to uniaxial compression. Was observed in X-ray diffra ction, that with increasing temperature, the intensity of the peaks of monoclinic phase is decreased. The sintering temperature moderately has influenced on the microhardness of samples, showing small increases in hardness to temperature of 1600 ? C. The flexural strength of zirconia residue increases with increasing sintering temperature for both routes of compression, showing the best values for isostatic compression.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-07-20T21:46:40Z No. of bitstreams: 1 RafaelaLuizPereiraSantos_TESE.pdf: 5717758 bytes, checksum: 765e67dde7c80007f582df680380b1c9 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-07-21T19:39:57Z (GMT) No. of bitstreams: 1 RafaelaLuizPereiraSantos_TESE.pdf: 5717758 bytes, checksum: 765e67dde7c80007f582df680380b1c9 (MD5) / Made available in DSpace on 2016-07-21T19:39:57Z (GMT). No. of bitstreams: 1 RafaelaLuizPereiraSantos_TESE.pdf: 5717758 bytes, checksum: 765e67dde7c80007f582df680380b1c9 (MD5) Previous issue date: 2016-01-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / All-ceramic restorations have been widely used as aesthetic standard in nowadays dentistry, to replace the tooth structure (appearance and function). However, failures associated with chipping and delamination of the veneering porcelain from zirconia substructure still high when compared to metal-ceramic systems. This study aimed address these problems by improving the mechanical strength of veneering porcelain and by improving its adhesion to zirconia substrate. First, the addition of a stronger ceramic second phase (zirconia particles) to feldspathic porcelain was studied. This study began with the preliminary characterization of zirconia synthesized by Complex Polymerization Method (CPM) and commercial zirconia. It was found that the synthesized zirconia did not show improved properties when compared to commercial zirconia. Commercial zirconia powders were thus used thereafter. The influence of the type of powder (pre-sintered or agglomerated) in the mechanical properties and wear of porcelain composites (20vol.%) was evaluated. The pre-sintered powders increased the mechanical strength and wear of the composites compared to agglomerated powders. Then, it was determined the amount of second phase (0-50vol.%) that maximizes the mechanical properties of the porcelain-zirconia composites. It was concluded that the composites with 30vol.% of zirconia showed the best results for wear and flexural strength (198.5MPa). Finally, it was evaluated the influence of the type of surface treatment (sandblasting or holes) and the deposition of a composite interlayer (porcelain reinforced with 30vol.% of zirconia), on the zirconia surface, on the bond strength between the veneering porcelain and the zirconia substructure. The highest bond strength values were found for specimens having simultaneously holes on the surface of zirconia and the composite interlayer between the zirconia substructure and the veneering porcelain (138 ? 19MPa). It was demonstrated that the correct configuration of the interface between the zirconia substructure and the veneering porcelain can lead to all-ceramic restorations with enhanced mechanical strength and improved clinical performance. / Materiais comp?sitos restauradores representam um dos mais bem sucedidos biomateriais na pesquisa moderna, na substitui??o do tecido biol?gico em apar?ncia e fun??o. Nesta linha, a porcelana feldsp?tica tem sido largamente usada em odontologia devido suas interessantes qualidades como estabilidade de cor, propriedades est?ticas, elevada durabilidade mec?nica, biocompatibilidade, baixa condutividade t?rmica e elevada resist?ncia ao desgaste. Entretanto, este material ? fr?gil e pode falhar em ambiente oral devido ao micro-vazamento, baixa resist?ncia ? tra??o, descolagem ou fratura. Assim, para melhorar as propriedades mec?nicas da porcelana, a zirc?nia parcialmente estabilizada com ?tria (Y-TZP) pode ser uma boa alternativa para fortalecer e produzir infraestruturas totalmente cer?micas (coroas e pr?teses parciais fixas). Portanto, este estudo tem por objetivo avaliar as propriedades mec?nicas e caracter?sticas microestruturais da porcelana refor?ada com zirc?nia (3Y-TZP) em diferentes conte?dos e as vari?veis que afetam as propriedades mec?nicas destes materiais. O estudo de caracteriza??o revelou que a zirc?nia comercial apresenta melhores resultados quando comparada com a zirc?nia sintetizada pelo CPM. Assim, os estudos seguintes utilizaram a zirc?nia comercial para todos os testes requeridos. As part?culas de zirc?nia apresentam elevadas propriedades mec?nicas quando comparadas a zirc?nia aglomerada. Os diferentes conte?dos revelam que as propriedades mec?nicas dos comp?sitos aumentam com o aumento do conte?do volum?trico at? 30% vol.% (198,5Mpa), ou seja, maior resist?ncia ? flex?o quando comparada com os outros comp?sitos. Do mesmo modo, a resist?ncia ao desgaste para os comp?sitos com (30%, vol.% de zirc?nia) apresenta valores superiores quando comparado aos demais comp?sitos. Na ades?o cer?mico-cer?mico a porcelana exibe elevada ades?o para a superf?cie de zirc?nia porosa quando comparada a superf?cie rugosa. Os furos superficiais (PZ) e aplica??o de comp?sitos com camada intermedi?ria (RZI) na zirc?nia causam separadamente uma melhoria da resist?ncia ao cisalhamento da zirc?nia-porcelana quando comparados as amostras convencionais de zirc?nia-porcelana (RZ), embora n?o sejam estatisticamente significativas (p>0.05). A presen?a de uma camada intermediaria produz um aumento significativo na for?a de liga??o (~55%) em rela??o as amostras convencionais (RZ). Portanto, a correta a correta configura??o e tratamento superficial podem produzir subestruturas com qualidade e for?a de liga??o adequadas aos requisitos odontol?gicos.

Submitted by PPG Odontologia (odontologia-pg@pucrs.br) on 2018-05-28T13:41:25Z No. of bitstreams: 1 RAQUEL_DE_OLIVEIRA_LOPES_TES.pdf: 2230148 bytes, checksum: a749d045cae0f8098669b38fe6b648b6 (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2018-06-11T18:19:23Z (GMT) No. of bitstreams: 1 RAQUEL_DE_OLIVEIRA_LOPES_TES.pdf: 2230148 bytes, checksum: a749d045cae0f8098669b38fe6b648b6 (MD5) / Made available in DSpace on 2018-06-11T18:25:33Z (GMT). No. of bitstreams: 1 RAQUEL_DE_OLIVEIRA_LOPES_TES.pdf: 2230148 bytes, checksum: a749d045cae0f8098669b38fe6b648b6 (MD5) Previous issue date: 2018-01-17 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / (Artigo Os adesivos universais s?o t?o eficientes quanto um primer para a ades?o ? zirc?nia?) O objetivo do trabalho foi comparar a resist?ncia de uni?o ? cer?mica de zirc?nia de quatro adesivos universais e um primer para zirc?nia. Setenta e cinco amostras de zirc?nia foram confeccionadas e inclu?das em resina acr?lica. A superf?cie das amostras foi polida com lixas de carbeto de sil?cio nas granula??es 600, 800 e 1.200 e jateadas com ?xido de alum?nio 50 ?m por 5 s. As amostras foram divididas aleatoriamente em cinco grupos (n=15): G1 ? Single Bond Universal (SBU); G2 ? All Bond Universal (ABU); G3 ? Peak Universal Bond (PUB); G4 ? Ambar Universal (AU) e G5 ? Z-Prime Plus (ZP). Um cone de resina composta foi constru?do, atrav?s de uma matriz, sobre o material adesivo aplicado na superf?cie das amostras. Os corpos de prova foram armazenados em ?gua destilada a 37?C por 24 h, sendo submetidos ao teste de resist?ncia de uni?o ? tra??o em m?quina de ensaio universal EMIC com velocidade de 0,5 mm/min. Os tipos de falhas foram classificados em adesiva, coesiva ou mista. Os valores de resist?ncia de uni?o foram submetidos ? an?lise de vari?ncia (ANOVA), seguido do teste de Tukey (?=0,05). M?dias de resist?ncia de uni?o (MPa) seguidas de letras distintas diferem estatisticamente entre si: G5=21,12a, G1=20,55a, G4=19,12ab, G2=14,22b, G3=8,45c. As falhas foram predominantemente mistas no G1, G4 e G5, e predominantemente adesivas no G2 e G3. Os adesivos SBU e AU obtiveram resist?ncia de uni?o compar?vel ao ZP. / (Artigo Bond to zirconia ceramic: evaluation of different primers and a universal adhesive) The aim of the study was to evaluate the effect of a universal adhesive and different primers on the bond strength to zirconia ceramic. Seventy-five zirconia ceramic samples were obtained and divided into five groups (n=15): G1 ? Scothbond Universal (SBU); G2 ? silane + SBU; G3 - Signum Zirconia Bond; G4 - Z-Prime Plus; G5 - MZ Primer. A cone of composite resin was built. The specimens were stored in 100% relative humidity with distilled water at 37?C for 48 h, and then submitted to a tensile bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The type of failure that occurred during the debonding procedure was analyzed. The mean results of the bond strength test (MPa) followed by the same letter represent no statistical difference by ANOVA and Tukey?s post-hoc test (p<0.05): G2=27.55a (?6.99), G4=23.71a (?5.65), G1=22.64a (?5.67), G5=13.64b (?5.49), G3=7.54c (?4.75). G2 and G4 exhibited predominantly cohesive failure in the resin composite cone. G1 and G5 had predominantly mixed failures, and G3 exhibited only adhesive failures. The SBU and Z-Prime Plus provided higher bond strength to zirconia ceramic. / (Artigo Os adesivos universais s?o t?o eficientes quanto um primer para a ades?o ? zirc?nia?) The aim of the study was to compare four universal adhesives and a primer on the bond strength to zirconia ceramic. Seventy-five zirconia ceramic samples were obtained and embedded in acrylic resin. The surface of the samples was polished with 600-, 800- and 1200-grit silicon carbide abrasive papers, and sandblasted with 50 ?m aluminum oxide particles for 5 s. The samples were divided into five groups (n=15): Single Bond Universal (SBU); G2 ? All Bond Universal (ABU); G3 ? Peak Universal Bond (PUB); G4 ? Ambar Universal (AU) e G5 ? Z-Prime Plus (ZP). A cone of composite resin was built on the adhesives and primer applied. The specimens were stored in distilled water at 37oC for 24 h, and then submitted to a tensile bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The type of failure that occurred during the debonding procedure was classified as adhesive, cohesive or mixed. The values of bond strength were analyzed by analysis of variance (ANOVA) followed by Tukey?s test (?=0.05). Means of bond strength (MPa) followed by the distinct letters represent statistical difference: G5=21,12a, G1=20,55a, G4=19,12ab, G2=14,22b, G3=8,45c. The failures were predominantly mixed in G1, G4 and G5, and predominantly adhesive in G2 and G3. SBU and AU adhesives obtained bond strength comparable to ZP.

Submitted by PPG Odontologia (odontologia-pg@pucrs.br) on 2018-06-27T13:42:26Z No. of bitstreams: 1 DEBORAH_STONA_TES.pdf: 479572 bytes, checksum: 09946538cb3d70a32dd07508ec13bcce (MD5) / Rejected by Sheila Dias (sheila.dias@pucrs.br), reason: Trabalho devolvido devido constar no sum?rio o t?pico "Hip?teses", mas no corpo do trabalho n?o aparece, do t?pico "Objetivos" passa para "Materiais e m?todos" no arquivo PDF. on 2018-07-04T12:49:48Z (GMT) / Submitted by PPG Odontologia (odontologia-pg@pucrs.br) on 2018-07-19T10:52:46Z No. of bitstreams: 1 DEBORAH_STONA_TES.pdf: 842939 bytes, checksum: 8b8eda0f9181f560f275f85833a4faec (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-07-24T12:53:45Z (GMT) No. of bitstreams: 1 DEBORAH_STONA_TES.pdf: 842939 bytes, checksum: 8b8eda0f9181f560f275f85833a4faec (MD5) / Made available in DSpace on 2018-07-24T13:02:33Z (GMT). No. of bitstreams: 1 DEBORAH_STONA_TES.pdf: 842939 bytes, checksum: 8b8eda0f9181f560f275f85833a4faec (MD5) Previous issue date: 2018-03-26 / Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Aims: 1) to evaluate the fracture resistance of posterior full-contour crowns of lithium dissilicate, lithium silicate reinforced by zirconia or translucent zirconia cemented on solid abutments; 2) to evaluate if the presence of a zirconia coping can increase the fracture resistance of lithium dissilicate crowns compared to monolithic ceramics made in lithium dissilicate, lithium silicate reinforced by zirconia or translucent zirconia. Materials and methods: Forty RN (regular-neck, Straumann) implant analogs and 4.0 mm solid abutments (Straumann) were embedded in acrylic resin and divided into 5 groups (n = 8): 1) e.max CAD; 2) Celtra Duo; 3) Incoris zirconia TZI; 4) 0.6 mm zirconia coping + e.max CAD; 5) 0.3 mm zirconia coping + e.max CAD. After preparation of the specimens, they were subjected to mechanical fatigue testing with 200N and 500,000 cycles. Following, the samples were submitted to the fracture resistance testing. Results: the means in Newtons (N) were as follows: e.max CAD 210.6Na ? 1447; Celtra Duo 2026Nb ? 355.8; zirconia TZI 2850Nc ? 287.6; 0.6 mm coping + e.max CAD 851Nd ? 108.1; 0.3 mm coping + e.max CAD 980Nd ? 133. Conclusion: monolithic translucent zirconia crowns cemented on solid abutments showed the higher fracture resistance in comparison to lithium dissilicate (e.max CAD) and lithium silicate reinforced by zirconia (Celtra Duo). The use of a zirconia coping associated with lithium dissilicate does not promote superior fracture resistance than monolithic crowns regardless of the thickness of coping and veneering ceramics. / Objetivos: 1) Avaliar a resist?ncia ? fratura de coroas cer?micas de dissilicato de l?tio, silicato de l?tio refor?ada por zirc?nia e zirc?nia transl?cida cimentadas sobre pilares s?lidos; 2) Avaliar se a presen?a de um coping em zirc?nia pode aumentar a resist?ncia ? fratura de coroas de dissilicato de l?tio quando comparadas ?s cer?micas monol?ticas confeccionadas em dissilicato de l?tio, zirc?nia transl?cida ou silicato de l?tio refor?ada por zirc?nia cimentadas sobre pilares s?lidos. Materiais e m?todos: Quarenta an?logos de implantes RN (regular neck, Straumann) e pilares s?lidos 4.0mm (Straumann) foram inclu?dos em resina acr?lica e divididos em 5 grupos (n=8) os quais receberam as seguintes coroas prot?ticas cimentadas: 1) e.max CAD; 2) Celtra Duo; 3) zirc?nia Incoris TZI; 4) coping zirc?nia 0,6mm + e.max CAD; 5) coping zirc?nia 0,3mm + e.max CAD. Ap?s confec??o dos corpos de prova os mesmos foram submetidos ? fadiga mec?nica com carga de 200N e 500.000 ciclos. Na sequ?ncia foram submetidos ao ensaio de carga m?xima de carregamento. Resultados: as m?dias de resist?ncia ? fratura obtidas foram: e.max CAD 1447Na ? 210,6; Celtra Duo 2026Nb ? 355,8; zirc?nia TZI 2850Nc ? 287,6; coping 0,6mm + e.max CAD 851Nd ? 108,1; coping 0,3mm + e.max CAD 980Nd ? 133. Conclus?o: Coroas monol?ticas realizadas em zirc?nia transl?cida cimentadas sobre pilares s?lidos apresentaram a maior resist?ncia ? fratura quando comparadas ao dissilicato de l?tio (e.max CAD) e silicato de l?tio refor?ado por zirc?nia (Celtra Duo). O uso de um coping de zirc?nia associado ao dissilicato de l?tio n?o promove resist?ncia ? fratura superior as coroas monol?ticas independentemente das espessuras do coping e da cer?mica de cobertura.