Decorative, polychrome ceramics from Corinth, Greece, produced during the 8th-6th centuries B.C.E. are luxury goods that were widely traded throughout Greece and the Mediterranean. The decorated ceramics were produced in a variety of shapes, including aryballos, alabastron, and olpe. They were decorated with slip-glazes in distinctive white, black, red, yellow, and purple colors, and in a variety of surface finishes, matte, semi-matte and glossy. Artisans in Corinthian workshops experimented to change the colors of the slips by varying the type and amount of iron-rich raw materials. They also varied the composition of the clay used as a binder and the amount of flux used as a sintering aid to promote glass formation. This research reconstructs the technology used by the Corinthian craftsmen to produce the Archaic polychrome ceramics, and shows how these technologies differed from the production of better known, more prestigious Athenian black-figure and red-figure ceramics. Through microstructural examination of archaeological samples and replication experiments, this thesis proposes that the purple iron oxide pigment is the result of acid treatment and oxidation of iron metal. The firing temperature range of the Corinthian polychrome ceramics was determined experimentally to be 925-1025° C, which is higher than previously reported and similar to that reported for Corinthian transport amphoras. The firing range is higher by 50-150° C than the Athenian black-figure and red-figure ceramics. Samples of Corinthian polychrome and Athenian black-figure ceramics from the Marie Farnsworth collection at the University of Arizona were tested and compared to Corinthian clay collections. Analytical techniques included Fourier-transform infrared spectroscopy (FTIR), scanning-electron microscopy with energy-dispersive spectroscopy (SEM-EDS), micro-Raman spectroscopy, and wavelength-dispersive electron microprobe (EPMA with BSE-SEM).

This research explores the relationship between social identity, artifact style, and communities of practice in the late prehispanic U.S. Southwest, focusing on how domestic, utilitarian objects and contexts both shape and reflect social identities. During the A.D. 1200s and 1300s, large-scale migration and aggregation occurred over much of the U.S. Southwest, bringing diverse individual and community identities into contact and, potentially, conflict. Within this social context, this research focused on clarifying the relationship between social identities and utilitarian objects and domestic contexts, and how this relationship can elucidate the social history of a community. These issues were explored through analysis of corrugated utilitarian pottery from the sites of the Homol’ovi Settlement Cluster (HSC), a community of seven villages in northeastern Arizona occupied from around 1260 through 1400. The social organization of corrugated pottery production in the HSC was approached from several angles. To identify the number and nature of the ceramic manufacturing communities present during the Pueblo IV occupation of the Homol’ovi area, sherds were submitted for instrumental neutron activation analysis and petrographic analysis. The results of the compositional analyses indicate that ceramic production groups in the Homol’ovi area were not primarily distinguished by access to specific raw material resources. What differentiation there is within the raw materials used by Homol’ovi potters appears to have been determined primarily by village, with the residents of a few villages preferring to use specific clay or temper sources. Both locally produced pottery and ceramics imported into the Homol’ovi area were incorporated into a typological and stylistic analysis. This analysis found evidence of two different production styles in the corrugated pottery assemblage. One appears stylistically similar to pottery produced in areas to the north around the Hopi Mesas; the other appears to be more akin to stylistic traditions practiced in the Puerco area and in the Chevelon drainage. This diversity suggests the presence of multiple immigrant communities co-residing within the HSC. This social diversity is not reflected in the decorated ceramic tradition of the HSC, which largely conforms to the ceramic traditions of the Hopi Mesas. Interrogating the disjuncture in the identities embodied through different categories of material culture, used in different social contexts, provides a framework through which to explore the complex social relationships that characterized Pueblo IV villages formed as individuals and communities negotiated the competing forces of integration and differentiation. This study demonstrates the value of approaching identity from multiple scales. If identity is understood as fundamentally multi-faceted and multi-scalar, even seemingly homogeneous cultural units are characterized by social diversity and the tension that accompanies such diversity. The patterns of production visible in utilitarian corrugated pottery provide a nuanced method of clarifying the complex identities of Ancestral Puebloan communities and assessing social connections and differences between groups.

Cette thèse vise à mettre en lumière les déplacements des frontières artistiques à travers le cas de la céramique contemporaine, un monde périphérique parmi la nébuleuse des mondes de l’art. Au-delà de la rupture classique entre les modèles de l’art et de l’artisanat, cette recherche analyse comment s’édifie un monde avec une identité artistique et culturelle forte et dans lequel, les amateurs jouent un rôle significatif. De la cohabitation de deux versants au cœur de la céramique contemporaine — le régime patrimonial et le paradigme de l’art contemporain — résulte une situation de relative marginalité : d’un côté se trouve la faible reconnaissance de la céramique au sein de la scène artistique contemporaine (et de ses marchés) et de l’autre, l’attachement artistique des acteurs sociaux (céramistes, amateurs, collectionneurs, professionnels) ainsi qu’une double appartenance affirmée comme une valeur. Partant d’une enquête réalisée auprès des amateurs de céramique, nous analysons la céramophilie et les enjeux de la dimension affective de l’engagement et l’attachement artistiques sur les orientations de la céramique et son système de significations. C’est également à partir d’un état des lieux organisationnel, professionnel et symbolique, que nous étudions les basculements axiologiques opérés par le processus d’artification. Les espaces où se structurent les valeurs esthétiques et marchandes des objets (marchés potiers, galeries, musées, salons, etc.) mettent en évidence une économie artistique instable, mais constante. L’étude de la médiation — comme le territoire où se préfigurent les représentations — rend compte d’un monde régi par une forte proximité humaine plutôt que par les relations institutionnelles. Cette thèse aspire à montrer ainsi comment, malgré les multiples tensions présentes au sein de ce monde de l’art, celui-ci existe grâce aux valeurs différentielles entre l’art contemporain et l’artisanat d’art. Et que sa difficulté à (se) définir en art contemporain est traversée par l’existence même de ces paradoxes, lesquels s’inscrivent dans la pluralité des pratiques et dans l’instabilité des ambitions des acteurs. C’est alors que ces contradictions cohabitent au cœur de l’identité collective de cette communauté artistique, et s’affirment par l’attachement des amateurs et « céramophiles ». / This thesis aims to highlight the displacements of artistic borders through the case of contemporary ceramics, a peripheral world among the nebula of the worlds of art. Beyond the classic break between art and craft models, this research analyzes how a world with a strong artistic and cultural identity is built and in which amateurs plays a significant role. From the coexistence of two sides within the heart of contemporary ceramics - the patrimonial regime and the paradigm of contemporary art – gives birth to a situation of relative marginality: on the one hand there is the low recognition of ceramics within the artistic scene, on the other hand, the artistic attachment of social actors (ceramists, amateurs, collectors, professionals) who consider their double sense of belonging as a value. Based on a survey of ceramic amateurs, we analyze ceramophilia and the stakes of the emotional dimension of artistic commitment and attachment to the orientations of ceramics and the renewal of its system of meanings. It is also from an organizational, professional and symbolic inventory that we study the axiological changes affected by the process of artification. The spaces where the aesthetic and market values of objects (pottery markets, galleries, museums, exhibitions, etc.) are structured show an unstable but constant artistic economy. The study of mediation - as the territory where representations are prefigured - reflects a world governed by a close human proximity rather than by institutional relations. This thesis aspires to show how, despite the many tensions present within this art world, this one exists because of the differential values between contemporary art and arts and crafts and its difficulty to define itself in contemporary art, which is intersected by the paradoxical ambitions of its developers, who coexist and reaffirm themselves at the heart of the collective identity of an artistic community, thanks to the commitment of the same aforementioned amateurs and ceramophiles.

Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Zhijian Pei / Grinding is one of the important operations employed in modern manufacturing industry to remove materials and achieve desired geometry and surface finish. Simultaneous double side grinding (SDSG) and ultrasonic vibration assisted grinding (UVAG) are two typical cost-effective grinding processes which are utilized to grind semiconductor materials and high performance ceramic materials, respectively. The objectives of this research are to investigate several technical issues in modern grinding processes by using theoretical, numerical, and experimental research approaches. Those technical issues are related to SDSG and UVAG, which have been chosen as two typical grinding processes for this research. This thesis reviews the literature on SDSG (covering process applications, modeling of grinding marks, and modeling of wafer shapes) and UVAG (covering process applications, edge chipping, and coolant effects, etc). The theoretical research work of this thesis is conducted by developing mathematical models for grinding marks and wafers shapes in SDSG of silicon wafers. These developed models are then used to study the effects of SDSG parameters on the curvature of the grinding marks, the distance between adjacent grinding marks, and the wafer shapes. The numerical research work of this thesis is done by conducting a three dimensional (3-D) finite element analysis (FEA) of UVAG process. A 3-D FEA model is developed to study the edge chipping commonly observed in UVAG of ceramics. Edge chippings not only compromises geometric accuracy but also possibly causes an increase in machining cost. A solution to reduce the edge chipping is proposed based upon the FEA simulations and validated by pilot experiments. Several experimental studies are conducted to provide new knowledge for the UVAG process. Firstly, a novel coolant delivery system is explored for UVAG machine system. Secondly, UVAG is introduced into machining of fiber-reinforced ceramic matrix composites (CMC). Results of a feasibility study and a designed experimental investigation show that UVAG is a promising process for CMC machining. Finally, an experimental study on cutting forces during UVAG of zirconia/alumina composites is conducted. The feasibility to machine different zirconia/alumina composites using UVAG is also investigated and discussed. The findings in this thesis will provide theoretical and practical guidance for modern grinding processes especially for SDSG and UVAG.

Master of Science / Department of Mechanical and Nuclear Engineering / Gurpreet Singh / Polymer-derived ceramics (PDCs) such as silicon oxycarbide (SiOC) have shown promise as an electrode material for rechargeable Li-ion batteries (LIBs) owing to the synergy between its disordered carbon phase and hybrid bonds of silicon with oxygen and carbon. In addition to their unique structure, PDCs are known for their high surface area (~822.7 m² g⁻¹), which makes them potential candidates for supercapacitor applications. However, low electrical conductivity, voltage hysteresis, and first cycle lithium irreversibility have hindered their introduction into commercial devices. One approach to improving charge storage capacity is by interfacing the preceramic polymer with boron or aluminium prior pyrolysis. Recent research has shown that chemical interfacing with elemental boron, bulk boron powders and even exfoliated sheets of boron nitride leads to enhancements in thermal and electronic properties of the ceramic. This thesis reports the synthesis of a new type of PDC composite comprising of SiOC embedded with boron nitride nanotubes (BNNTs). This was achieved through the introduction of BNNT in SiOC pre-ceramic polymer at varying wt.% loading (0.25, 0.5 and 2.0 wt.%) followed by thermolysis at high temperature. Electron microscopy and a range of spectroscopy techniques were employed to confirm the polymer-to-ceramic transformation and presence of disordered carbon phase. Transmission electron microscopy confirmed the tubular morphology of BNNT in the composite. To test the material for electrochemical applications, the powders were then made into free-standing paper-like electrodes with reduced graphene oxide (rGO) acting as support material. The synthesized free-standing electrodes were characterized and tested as electrochemical energy storage materials for LIBs and symmetric supercapacitor applications. Among the SiOC-BNNT composite paper tested as anode materials for LIBs, the 0.25 wt.% BNNT composite paper demonstrated the highest first cycle lithiation capacity corresponding to 812 mAh g⁻¹ (at a current density of 100 mA g⁻¹) with a stable charge capacity of 238 mAh g⁻¹ when asymmetrically cycled after 25 cycles. On the contrary, the 0.5 wt.% BNNT composite paper demonstrated the highest specific capacitance corresponding to 78.93 F g⁻¹ at a current density of 1 A g⁻¹ and a cyclic retention of 86% after 185 cycles. This study shows that the free carbon content of SiOC-BNNT ceramic composite can be rationally modified by varying the wt.% of BNNT. As such, the paper composite can be used as an electrode material for electrochemical energy storage.

The thesis named Analysis of Czech export development in chosen field - glass industry, jewellery glass describes a development of glass and ceramics industry in Czech lands and in the Czech Republic. The aim of the thesis is to analyze export development of glass and ceramics products, mainly in the 21st century. Conclusions are based on data of Harmonized System from the Czech Statistical Office. It is clear that the importance of export of glass, jewellery and ceramics is not as high as it used to be before WWII, however, the value of export increased in 2010. The future of the Czech glass-work is represented by orientation to technologically sophisticated products which cannot be easily produced on the cheap Asian markets.

Orientador: Lourenço Correr Sobrinho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-04T01:52:04Z (GMT). No. of bitstreams: 1 Muzilli_Marcelo_M.pdf: 7588731 bytes, checksum: 3a8603c74230e5a6adcf083d96084d55 (MD5) Previous issue date: 2005 / Resumo: O objetivo deste estudo foi avaliar a influência do tratamento de superfície na rugosidade de superfície e na dureza Vickers de oito materiais cerâmicos utilizados para cobertura incisal, após serem submetidos a desgaste abrasivo e a 4 tratamentos de superfície envolvendo polimento mecânico e/ou glaze. Foram confeccionados quarenta discos com 8 mm de diâmetro por 2 mm de espessura da cerâmica para cobertura incisal da dentina cor A3. O pó cerâmico de cada marca comercial (CERAMCO, CERCON, DSIGN, FINESSE, VINTAGE HALO, VISION, VISION ESTHETIC e WILL CERAM) foi aglutinado com o líquido modelador indicado e aplicado em uma matriz metálica bipartida. Após a sinterização e o esfriamento, os discos foram desgastados com ponta diamantada 3098 F e 3098 FF (KG Sorensen), simulando ajuste oclusal clínico, e subdivididos em 4 grupos com 10 discos cada: Grupo P ¿ Polimento com abrasivos do sistema Shofu; Grupo PP ¿ Polimento + Pasta Diamantada; Grupo PG ¿ Polimento + Glaze e Grupo G ¿ Glaze (Controle). Após os tratamentos de superfície, os corpos-de-prova foram levados ao rugosímetro Surf-Corder para mensuração da rugosidade de superfície, utilizando o parâmetro Ra. Foram feitas três leituras em cada corpo-de-prova, totalizando 960 leituras. A dureza Vickers foi efetuada no aparelho HMV-2 (Shimadzu), calibrado com carga de 1 kgf atuando por 15 segundos. Cinco penetrações foram feitas em cada corpo-de-prova, para cada tipo de cerâmica e tratamento de superfície, totalizando 1600 medidas. Os dados foram submetidos à Análise de Variância e ao teste de Tukey (5%) e mostraram que de maneira geral a rugosidade superficial sofreu influência do tratamento de superfície em todas as cerâmicas utilizadas. O polimento com o sistema Shofu e polimento com pasta diamantada não mostraram diferença estatística entre todas as cerâmicas. Para o tratamento de superfície com glaze e polimento com sistema Shofu + glaze, a cerâmica Vintage Halo apresentou os maiores valores de rugosidade, enquanto a Will Ceram os menores. O polimento com o sistema Shofu resultou nos menores valores de dureza para a cerâmica Vintage Halo. Na superfície tratada com glaze, os maiores valores foram obtidos com as cerâmicas Dsign, Finesse, Vision e Vision Esthetic e a menor com a cerâmica Cercon. No polimento + glaze, os maiores valores de dureza foram obtidos com as cerâmicas Finesse, Will Ceram, Vision Esthetic e Ceramco e os menores com o Cercon. Para o polimento + pasta diamantada, os maiores valores de dureza foram obtidos com as cerâmicas Finesse, Vision, Will Ceram, Dsign, Vision Esthetic e Ceramco e os menores com a cerâmica Cercon / Abstract: The objective of this study was to evaluate the influence of surface treatment on surface roughness and Vickers hardness number of the eight dental enamel ceramics, after abrasive grinding and 4 surface treatments with polishing and/or glaze. Forty enamel ceramic disks with 8 mm in diameter and 2.0 mm thickness were made in bipartite metallic matrix for each material incisal dentin A3. The ceramic powder for each brand (CERAMCO, CERCON, DSIGN, FINESSE, VINTAGE HALO, VISION, VISION ESTHETIC e WILL CERAM), was agglutinated with the appropriate modeling liquid and applied on a bipartite metallic matrix. After the sinterization and cooling, the disks were submitted to a simulation of oclusal adjustment with 3098 F and 3098 FF diamonds burs (KG SORENSEN), on high speed hand-piece with refrigeration and divided into four groups with 10 disks each: Group P (10 disks) ¿ Shofu polishing system; Group PP ¿ Shofu polishing system + diamond paste (6µm ¿ KG SORENSEN); Group PG ¿ Shofu polishing system + glaze; and, Group G ¿ glaze (control). After surface treatments, the roughness was measured on a Surf-Corder machine using Ra parameter. Three measurements were made for each specimen, totalizing 960 measurements. The Vickers hardness number was measured with HMV 2 microhardness tester (Shimadzu), with a load of 1 Kgf applied for 15 seconds. Five measurements were made for each specimen, totalizing 1600 measurements. The date were submitted to ANOVA and Tukey¿s test (5%) and showed that in general the surface roughness suffered the influence of the surface treatment in all the ceramics that were used. The Shofu polishing system and polishing system diamond paste, didn¿t show any difference statistic among all the ceramics. For the surface roughness with glaze and polishing with Shofu system + glaze, the Vintage halo ceramic showed the highest values of roughness, while a Will Ceram the lowest. The Shofu polishing showed the lowest values of hardness when used the Vintage halo. In the surface treated with glaze, the highest values were obtained with the design ceramic and the lowest with the Cercon ceramic. In the surface treated with glaze, the highest value was obtained with Dsign, Finesse, Vision and Vision Esthetic ceramic and the and the lowest with Cercon ceramic. In the polishing + glaze, the highest values of hardness were obtained with the Finesse, Will Ceram, Vision Esthetic and Ceramco ceramic and the lowest with Cercon ceramic. For the polishing + diamond paste, the highest hardness values were obtained with the Finesse, Vision, Will Ceram, Dsign, Vision Esthetic and Ceramco ceramic and the lowest with the Cercon ceramic / Mestrado / Materiais Dentarios / Mestre em Materiais Dentários

Orientador: Lourenço Correr Sobrinho / Dissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-04T02:14:36Z (GMT). No. of bitstreams: 1 Carvalhal_CintiaIaraOda_M.pdf: 1211123 bytes, checksum: ff29710bc6159cfbddcef9b103d75504 (MD5) Previous issue date: 2005 / Resumo: O objetivo deste estudo foi avaliar a resistência à fratura (sem fadiga) e o efeito do tempo de armazenagem em água (24 horas e 1 ano) na resistência à fadiga + fratura da coroa cerâmica IPS Empress 2 (Ivoclar), fixadas com cimento resinoso Variolink II (Ivoclar-Vivadent) e cimento de ionômero de vidro modificado por resina Rely X Luting (3M ESPE). Noventa incisivos bovinos foram incluídos em resina acrílica. Os dentes foram preparados para receber coroas totais completas, usando pontas diamantadas no 4103 sob refrigeração com água, com paredes convergentes de 8o e término cervical em ombro com 90o. Noventa coroas em cerâmica com 8 mm de diâmetro por 8,5 mm de altura foram confeccionadas com a cerâmica IPS Empress 2. Em seguida, quarenta e cinco coroas foram fixadas com cimento Variolink II e quarenta e cinco com o Rely X Luting, com auxílio de prensa pneumática, com carga estática de 9 kgf, por 1 minuto e divididas em seis grupos de acordo com o tratamento e material de fixação. Em seguida, 60 corpos-de-prova foram armazenados em água destilada a 37o C por 24 horas e 30 por 1 ano. Nos grupos 1 e 2, fratura (sem fadiga) fixadas com os cimentos Variolink II e Rely X Luting, 15 corpos-de-prova para cada grupo foram submetidos ao teste de fratura a uma velocidade de 1,0 mm/minutos. Os grupos 3 e 4 foram submetidos ao teste de fadiga por 60.000 ciclos, com carga de 75 N, aplicada com força em forma sinosoidal com 2 HZ, em água destilada seguido pelo teste de fratura para o tempo de armazenagem de 24 horas (15 corpos-de-prova para cada tipo de cimento). Os grupos 5 e 6 semelhantes aos grupos 3 e 4, para um tempo de armazenagem de 1 ano. Os resultados foram submetidos à Análise de Variância e ao teste de Tukey (p<0,05) e mostraram que o cimento resinoso Variolink II apresentou valores de resistência estatisticamente superiores ao Rely X Luting, nas condições fratura (sem fadiga) e fadiga + fratura, nos períodos de armazenagem 24 horas e 1 ano (p<0,05). Os períodos de armazenagem 24 horas e 1 ano não diminuíram significativamente os valores de resistência à fadiga + fratura para as coroas cerâmicas IPS Empress 2, fixadas com os cimentos Variolink II ou Rely X Luting (p>0,05) / Abstract: The aim of this study was to evaluate the fracture strength (without fatigue) and the influence of storage time (24 hours and 1 year) in fatigue + fracture strength of IPS Empress 2 crowns (Ivoclar), luted with resin cement Variolink II (Ivoclar-Vivadent) and resin-modified glass ionomer cement Rely X Luting (3M ESPE). Ninety bovine incisors were embedded in acrylic resin. The coronal portions of the teeth were prepared to receive complete crowns using a 4103 diamond bur under water refrigeration with 8o of tapering and 90° shoulder. Ninety crowns with 8mm diameter and 8.5mm height were fabricated with the ceramics IPS Empress 2. After glazing, forty-five crowns were luted onto the bovine tooth with Variolink II and forty-five with Rely X Luting. The crowns were luted onto the tooth with static load of 9kgf for 1min and divided in six groups according to the treatment and cement. Afterwards, sixty specimens were stored in distilled water at 37o C for 24 hours and thirty for 1 year. Groups 1 and 2, fracture strength (without fatigue) luted with Variolink II and Rely X Luting, 15 specimens for each group were submitted to the fracture strength at a crosshead speed of 1.0mm/min. Groups 3 and 4 were submitted to 60,000 fatigue cycles, with load of 75N applied perpendicularly to the oclusal surface at 2HZ in wet environment, and to the fracture test for the storage time 24 hours (15 specimens for each of the cement). The groups 5 and 6 were submitted to the same treatment of the groups 3 and 4, for the 1 year of storage time. The data were analysed by ANOVA and Tukey¿s test (p<0.05) and showed that the resin cement Variolink II showed values of the strength significantly stronger than Rely X Luting, in the condition of fracture strength (without fatigue) and fatigue + fracture, in the storage time 24 hours and 1 year (p<0.05). The storage time 24 hours and 1 year didn¿t decrease significantly the fatigue + fracture strength for the IPS Empress 2 ceramics crowns luted with Variolink II or Rely X Luting (p>0.05) / Mestrado / Materiais Dentarios / Mestre em Materiais Dentários

Orientador: Lourenço Correr Sobrinho / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-28T02:03:49Z (GMT). No. of bitstreams: 1 LyraeSilva_JoaoPaulo_D.pdf: 5649364 bytes, checksum: 4a23d0622075770d464eab54068e0f3f (MD5) Previous issue date: 2015 / Resumo: Os objetivos neste estudo foram (1) investigar a influência de diferentes métodos de ensaio de resistência à flexão de cerâmicas odontológicas de acordo com a norma ISO 6872; (2) avaliar o efeito do proporcionamento do teste de resistência à flexão biaxial para cerâmicas odontológicas por Análise de Elementos Finitos. Estudo 1 - dez discos em cera (Ø 12 mm x espessura de 1.2 mm) e barras em resina acrílica (25 mm de comprimento x 5 mm de espessura e 2 mm de altura) foram usinadas usando o sistema CAD/CAM. Em seguida, os padrões em cera e resina usinados foram incluídos em revestimento para técnica de cera perdida e pastilhas de cerâmica à base de disilicato de lítio foram injetadas. Para a análise de elementos finitos, três modelos tridimensionais foram gerados usando elementos hexaédricos e a análise foi realizada de acordo com os testes. Estudo 2 - três modelos tridimensionais de elementos finitos para teste de resistência à flexão biaxial foram gerados usando elementos hexaédricos simulando as condições da ISO 6872 e em proporções dimensionais de 75% e 50%. Todas as pontas aplicadoras foram consideradas superfícies de contato e uma carga de 120 N foi aplicada. Os materiais foram considerados como homogêneos, lineares, elásticos e isotrópicos. Os discos cerâmicos assumiram as propriedades mecânicas do dissilicato de lítio (96 GPa e 0,23 coeficiente de Poisson). Fricção entre os sistemas de carga e os cilindros foi desconsiderada. Restrições foram aplicadas nas extremidades do disco cerâmico, para evitar o deslocamento do espécime. Análise estática estrutural de contato foi considerada linear (MSC Marc 2010, MSC Software Corporation) e os resultados foram analisados usando von Mises (VM) e Máximo Principal (MPS). No estudo 1, diferenças significantes foram observadas para os valores de resistência à flexão obtidos com diferentes métodos, com maiores valores para resistência à flexão biaxial que para a flexão de três pontos. Maiores concentrações de tensão foram encontradas nas amostras nas áreas correspondentes ao contato da ponta aplicadora e suportes para ambos os métodos. Os resultados no estudo 2 mostram que maior concentração de tensão foi observado no ponto de carregamento e nas áreas de apoio, para todos os modelos do teste. O mesmo padrão de distribuição de tensão foi produzido para as diferentes proporções de piston on three ball. Já no estudo 1, pode-se concluir que: (I) para os valores de resistência à flexão, diferenças estatísticas foram verificadas para o mesmo material, quando foram utilizados diferentes métodos de ensaio (resistência à flexão uniaxial e biaxial). Para o estudo 2, de acordo com as análises de Von Mises e Resistência Máxima Principal, reduzindo a proporção da ISO 6872 houve aumento de concentração de tensão, no entanto, a distribuição de tensões nos discos de teste foi influenciada pelos diferentes design do teste / Abstract: The aims of these studies were: (1) to assess the influence of different test methods for assessing the flexural strength of dental ceramics according to the ISO 6872 standard; (2) to evaluate effect of proportioning biaxial flexural strength test on ceramic dental by Finite Element Analysis. Study 1 - ten waxed discs (12 mm in diameter and 1.2 mm thickness) and acrylic resin beams (25 mm length x 5 mm thickness and 2 mm height) were milled using CAD/CAM system. Then, the patterns were invested and lithium disilicate-based ceramic ingots were pressed. For FEA, three-dimensional (3D) models were generated and meshed using eight-node hexahedral elements and analysis was performed according to the tests. Study 2 - three models of 3D finite element of the biaxial flexure tests were generated and meshed using eight-node hexahedral elements simulating conditions of ISO 6872 parameters and its proportion of 75% and 50%. All loading systems were considered contacting surfaces and a 10 N load was applied. The materials were assumed as homogeneous, linear-elastic and isotropic. Ceramic disc assumed the mechanical property of lithium disilicate (96 GPa and 0.23 Poisson¿s ratio). Friction between the loading systems and the cylinder was considered negligible. Constraints were applied at the edges of the ceramic disc, to avoid the dislodgement of the specimen. Static structural analysis considering non-linear contact was performed (MSC Marc 2010, MSC Software Corporation) and the results were analyzed using von Mises (VM), and Maximum Principal (MPS). In study 1, significant differences were observed for the flexural strength values obtained with the different testing methods, with higher values for the biaxial flexural test than for the three point bending. Higher stress concentration was found in the specimens at the contact areas corresponding to the loading point and supports for the both test methods. The results of study 2 showed that more stress concentration was revealed at load point and support areas for all test designs. The same pattern of stress concentration was produced for the different proportions of piston on three ball test. For study 1 it was possible to conclude that: (I) for flexural strength values, statistical differences were verified for the same material when different testing methods (uniaxial and biaxial flexural strength) were performed. For study 2, according to the von Misses and Maximum principal stress analysis reducing the proportion of ISO 6872 the stress concentration increases, however, the stress concentration at the testing discs was influenced by the different test design / Doutorado / Materiais Dentarios / Doutor em Materiais Dentários

Orientador: José Roberto Cury Saad / Resumo: A crescente demanda por tratamentos estéticos tem impulsionado o desenvolvimento de novos materiais e técnicas para tratamentos restauradores. Este estudo teve como objetivo avaliar o efeito de diferentes materiais restauradores e términos de preparo sobre a integridade marginal de coroas unitárias confeccionadas pelo sistema CAD/CAM (Computer Aided Desing/Computer Aided Manufacturing). Quarenta coroas unitárias foram confeccionadas utilizando quatro materiais: cerâmica vítrea a base de dissilicato de lítio (IPS e.max CAD, Ivoclar Vivadent), composto híbrido a base de cerâmica feldspática reforçada com polímeros (Vita Enamic, Vita Zahnfabrik), cerâmica de silicato de lítio reforçada com zircônia (Vita Suprinity, Vita Zahnfabrik) e compósito vítreo nanohíbrido (Brava Blocks, FGM) a partir de um preparo com quatro términos diferentes: chanfro (espessura de borda 0.8 mm), chanfro raso (0.4 mm), chanfro profundo (1.2 mm) e ombro (1.2 mm). O dente preparado foi escaneado com um scanner intraoral (CEREC Omnicam, Dentsply Sirona) e um projeto de restauração foi confeccionado com o uso de um software (CEREC SW 4.4, Dentsply Sirona). As coroas foram obtidas a partir da fresagem (Dental Milling Machine MC XL, Dentsply Sirona) de blocos para CAD/CAM dos materiais incluídos no estudo. Em seguida, as coroas obtidas a partir de dois materiais (IPS e.max CAD e Vita Suprinity) foram levadas a forno (Programat CS2The, Ivoclar Vivadent) para queima de cristalização. A integridade de borda das ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The crescent demand for aesthetic treatments has driven the development of new materials and techniques for restorative treatments. The aim of this study was to evaluate the effect of different restorative materials and finish line designs on the marginal integrity of single crowns obtained by CAD/CAM (Computer Aided Desing/Computer Aided Manufacturing). Forty crowns were made using four materials: Lithium disilicate-based vitreous ceramics (IPS e.max CAD, Ivoclar Vivadent), hybrid composite based on polymere-reinforced feldspathic ceramics (Vita Enamic, Vita Zahnfabrik), silicate ceramics lithium reinforced with zirconia (Vita Suprinity, Vita Zahnfabrik) and composite vitreous nanohybrid (Brava Blocks, FGM) from a preparation with four different finish line designs: chamfer (0.8 mm edge thickness), shallow chamfer (0.4 mm), deep chamfer (1.2 mm) and shoulder (1.2 mm). The prepared tooth was scanned with an intraoral scanner (CEREC Omnicam, Dentsply Sirona) and a restoration project was made using a software (CEREC SW 4.4, Dentsply Sirona). Crowns were obtained from milling (Dental Milling Machine MC XL, Dentsply Sirona) from CAD/CAM blocks of materials included in the study. Then, the crowns obtained from two materials (IPS e.max CAD and Vita Suprinity) were submitted (Programat CS2The, Ivoclar Vivadent) for burning of crystallization. The marginal integrity of the crowns was measured using the Laser Confocal Scanning Microscope (Lext OLS 4100, 3D measuring laser microscope,... (Complete abstract click electronic access below) / Mestre