This research provides a comprehensive investigation in understanding the effect of the addition of graphene nano-platelets (GNP) on the mechanical, tribological and biological properties of glass/ceramic composites. We investigated two kinds of materials namely amorphous matrices like glasses (silica, bioglass) and polycrystalline matrices like ceramics (alumina). The idea was to understand the effect of GNP on these matrices as GNP was expected to behave differently in these composites. Bioglass (BG) was also chosen as a matrix material to prepare BG-GNP composites. GNP can improve the electrical conductivity of BG which can be used further for bone tissue engineering applications. The effect of GNP on both electrical conductivity and bio-activity of BG-GNP composites was investigated in detail. There were three main problems for fabricating these novel nano-composites: 1) Production of good quality graphene; 2) Homogeneous dispersion of graphene in a glass/ceramic matrix and; 3) Retention of the graphitic structure during high temperature processing. The first problem was solved by synthesising GNP using liquid phase exfoliation method instead of using a commercially available GNP. The prepared GNP were ~1 μm in length with a thickness of 3-4 layers confirmed using transmission electron microscopy. In order to solve the second problem various processing techniques were used including powder and colloidal processing routes along with different solvents. Processing parameters were optimised to fabricate glass/ceramic-GNP composite powders. Finally in order to avoid thermal degradation of the GNP during high temperature processing composites were sintered using spark plasma sintering (SPS) technique. Fully dense composites were obtained without damaging GNP during the sintering process also confirmed via Raman spectroscopy. Finally the prepared composites were characterised for mechanical, tribological and biological applications. Interestingly fracture toughness and wear resistance of the silica nano-composites increased with increasing concentration of GNP in the glass matrix. There was an improvement of ~45% in the fracture toughness and ~550% in the wear resistance of silica-GNP composites with the addition of 5 vol% GNP. GNP was found to be aligned in a direction perpendicular to the applied force in SPS. In contrast to amorphous materials fracture toughness and scratch resistance of alumina-GNP composites increased only for small loading of GNP and properties of the composites decreased after a critical concentration. There was an improvement of ~40% in the fracture toughness with the addition of only 0.5 vol% GNP in the alumina matrix while the scratch resistance of the composite increased by ~10% in the micro-ductile region. Electrical conductivity of the BG-GNP composite was increased by ~9 orders of magnitude compared to pure BG. In vitro bioactivity tests performed on BG-GNP composites confirmed that the addition of GNP to BG matrix also improved the bioactivity of the nano-composites confirmed using XRD analysis. Future work should focus on understanding electrical and thermal properties of these novel nano-composites.

The research carried out in this thesis describes the processing of liquids and ceramic suspensions, having a viscosity >100mPa s, using electrostatic atomization, mainly in the stable cone-jet mode. Electrostatic atomization, also called electrospraying, refers to a process where a liquid or a suspension is made to flow through a needle. The liquid or suspension is subjected to a high voltage maintained between the needle and a ground electrode. Two major physical properties, namely electrical conductivity and viscosity, affect electrostatic atornization in the stable cone-jet mode and the investigations described in this thesis focussed on the latter. Firstly, a set of liquid mixtures were prepared using distilled water and glycerol. The dc electrical conductivity of these mixtures were kept constant and the viscosity was varied. The mixtures were subjected to electrostatic atornization and in each case the mode of atornization, the cone/jet characteristics and relic sizes were studied as a function of viscosity. The effect of applied voltage on the conejet mode electrostatic atornization of glycerol having a viscosity of 1338mPa s was also investigated. Secondly, the possibilities of electrostatically atomizing ceramic suspensions were studied in detail. Several alumina suspensions were used including one containing a high volume fraction of solids (20 vol. % - the highest filler loading attempted to date using any jet-based processing route). Applied voltage - flow rate - atornization mode maps were constructed for this suspension incorporating even pico-flow rate regimes. This is a new input into the aerosol science and engineering literature. This section also highlights the importance of controlling the applied voltage and flow rate as these parameters affect the jet diameter and relic/droplet size generated. The effect of the geometry of the ground electrode used for electrostatic atornization was also investigated. In particular, the use of a point-like ground electrode was studied for the very first time. The third and most innovative facet of this research was the discovery of ceramic electrostatic atornization printing (CEAP) and the use of electrostatic atornization to produce ceramic foams. In CEAP a point-like ground electrode is used to focus the spray which was printed as characters, collection of characters and single tracks. This investigation was extended to explore the printing of multiple tracks produced with the aid of several needles and ground electrodes which worked simultaneously. A ring shaped ground electrode was used to electrospray ceramic droplets onto a polyurethane template and this paved the way for the development of a new method to prepare open-cell ceramic foams with a very high porosity. This method was extended to prepare ceramic structures and complex components.

by Tang Wing Chi = 碳-碳化鈦生物陶器之合成與表徵 / 鄧詠芝. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / by Tang Wing Chi = Tan-tan hua tai sheng wu tao qi zhi he cheng yu biao zheng / Deng Yongzhi. / Acknowledgement --- p.i / Abstract --- p.ii / 摘要 --- p.iv / Table of contents --- p.vi / List of figures --- p.xi / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Biomorphic materials --- p.1-1 / Chapter 1.2 --- Synthesis of biomorphic ceramics --- p.1-1 / Chapter 1.2.1 --- Pyrolysis --- p.1-2 / Chapter 1.2.1.1 --- Pyrolysis conditions --- p.1-3 / Chapter 1.2.2 --- Infiltration --- p.1-4 / Chapter 1.2.2.1 --- Vapor or gas infiltration --- p.1-4 / Chapter 1.2.2.2 --- Liquid infiltration --- p.1-4 / Chapter 1.2.2.3 --- Chemical vapor infiltration (CVI) --- p.1-5 / Chapter 1.2.2.4 --- Sol-gel processing --- p.1-5 / Chapter 1.2.3 --- Sintering --- p.1-6 / Chapter 1.3 --- Potential applications of biomorphic ceramics --- p.1-7 / Chapter 1.3.1 --- Homogenous porosity structures --- p.1-7 / Chapter 1.3.2 --- Heterogeneous porosity structures --- p.1-7 / Chapter 1.4 --- Methods and raw materials --- p.1-8 / Chapter 1.4.1 --- Infiltration --- p.1-8 / Chapter 1.4.2 --- Starting materials --- p.1-8 / Chapter 1.4.2.1 --- Ti source --- p.1-8 / Chapter 1.4.2.2 --- Biotemplates --- p.1-9 / Chapter 1.5 --- Objectives and approaches --- p.1-9 / Chapter 1.6 --- Thesis layout --- p.1-10 / References --- p.1-11 / Figures --- p.1-13 / Chapter Chapter 2 --- Methodology and Instrumentation / Chapter 2.1 --- Introduction --- p.2-1 / Chapter 2.2 --- Synthesis --- p.2-1 / Chapter 2.2.1 --- Biomorphic C-TiC ceramics from dragon tree --- p.2-1 / Chapter 2.2.2 --- Biomorphic C-TiC ceramics from wool sponge --- p.2-2 / Chapter 2.3 --- Characterization methods --- p.2-3 / Chapter 2.3.1 --- Differential thermal analyzer (DTA) --- p.2-3 / Chapter 2.3.2 --- Scanning electron microscopy (SEM) --- p.2-4 / Chapter 2.3.3 --- X-Ray powder diffractometry (XRD) --- p.2-4 / Chapter 2.3.4 --- Transmission electron microscopy (TEM) --- p.2-4 / Chapter 2.3.5 --- X-ray photoelectron spectroscopy (XPS) --- p.2-6 / Chapter 2.3.6 --- Compression tests --- p.2-6 / References --- p.2-9 / Figures --- p.2-8 / Chapter Chapter 3 --- The starting materials / Chapter 3.1 --- Introduction --- p.3-1 / Chapter 3.2 --- Fresh dragon tree --- p.3-1 / Chapter 3.2.1 --- SEM results --- p.3-1 / Chapter 3.2.2 --- Discussions --- p.3-2 / Chapter 3.3 --- Fresh sea wool sponge --- p.3-2 / Chapter 3.3.1 --- SEM results --- p.3-3 / Chapter 3.3.2 --- Discussions --- p.3-3 / Chapter 3.4 --- Tyzor-LA solution --- p.3-3 / Chapter 3.4.1 --- Physical properties --- p.3-4 / Chapter 3.4.2 --- DTA results --- p.3-4 / Chapter 3.4.3 --- XRD results --- p.3-5 / Chapter 3.4.4 --- Discussions --- p.3-5 / Chapter 3.5 --- Conclusions --- p.3-6 / References --- p.3-7 / Figures --- p.3-8 / Chapter Chapter 4 --- Results and discussions of biomorphic products fabricated from dragon tree / Chapter 4.1 --- Introduction --- p.4-1 / Chapter 4.2 --- Fabrication of biomorphic C-TiC ceramics --- p.4-1 / Chapter 4.2.1 --- Biotemplates from dragon tree --- p.4-1 / Chapter 4.2.1.1 --- XRD results --- p.4-1 / Chapter 4.2.1.2 --- SEM results --- p.4-2 / Chapter 4.2.1.3 --- Discussions --- p.4-2 / Chapter 4.2.2 --- Biomorphic C-TiC ceramics --- p.4-3 / Chapter 4.2.2.1 --- XRD results --- p.4-3 / Chapter 4.2.2.1.1 --- Effects of sintering temperature --- p.4-3 / Chapter 4.2.2.1.2 --- Effects of time duration --- p.4-3 / Chapter 4.2.2.2 --- SEM results --- p.4-4 / Chapter 4.2.2.3 --- TEM results --- p.4-4 / Chapter 4.2.2.3.1 --- Sample sintered at 1400。C for 6 hours --- p.4-4 / Chapter 4.2.2.3.2 --- Sample sintered at 1200°C for 6 hours --- p.4-5 / Chapter 4.2.2.3.3 --- Sample sintered at 1100。C for 6 hours --- p.4-5 / Chapter 4.2.2.3.4 --- Sample sintered at 900°C for 32 hours --- p.4-6 / Chapter 4.2.2.4 --- XPS results --- p.4-6 / Chapter 4.2.2.5 --- Results of compression tests --- p.4-7 / Chapter 4.2.2.6 --- Discussions --- p.4-7 / Chapter 4.3 --- Biomorphic C-TiC ceramics by repeated infiltration --- p.4-10 / Chapter 4.3.1 --- XRD results --- p.4-10 / Chapter 4.3.2 --- Discussions --- p.4-10 / Chapter 4.4 --- Conclusions --- p.4-11 / References --- p.4-12 / Figures --- p.4-13 / Chapter Chapter 5 --- Results and discussions of biomorphic products fabricated from sea wool sponges / Chapter 5.1 --- Introduction --- p.5-1 / Chapter 5.2 --- Fabrication of C-TiC biomorphic ceramics with sea wool sponges --- p.5-1 / Chapter 5.2.1 --- XRD results --- p.5-1 / Chapter 5.2.2 --- SEM results --- p.5-2 / Chapter 5.2.3 --- TEM results --- p.5-3 / Chapter 5.2.4 --- Discussions --- p.5-3 / Chapter 5.3 --- Dilution of Tyzor-LA solution --- p.5-5 / Chapter 5.3.1 --- XRD results --- p.5-5 / Chapter 5.3.2 --- SEM results --- p.4-5 / Chapter 5.3.3 --- Discussions --- p.5-6 / Chapter 5.4 --- Further annealing of biomorphic C-TiC ceramics in air --- p.5-6 / Chapter 5.4.1 --- XRD results --- p.5-7 / Chapter 5.4.2 --- SEM results --- p.5-7 / Chapter 5.4.3 --- TEM results --- p.5-8 / Chapter 5.4.4 --- Discussions --- p.5-9 / Chapter 5.5 --- Conclusions --- p.5-11 / References --- p.5-12 / Figures --- p.5-13 / Chapter Chapter 6 --- Conclusions and future works / Chapter 6.1 --- Conclusions --- p.6-1 / Chapter 6.2 --- Future works --- p.6-2 / References --- p.6-4

Orientador: Estevão Tomomitsu Kimpara / Banca: Alvaro Della Bona / Banca: José Henrique Rubo / Banca: Mário Alexandre Coelho Sinhoreti / Banca: Guilherme de Siqueira Ferreira Anzaloni Saavedra / Resumo: Testou-se o efeito de diferentes formas de tratamento da superfície cerâmica após condicionamento com ácido hidrofluorídrico (HF) na resistência à fratura de coroas cerâmicas à base de dissilicato de lítio. Quarenta terceiros molares humanos receberam um preparo convencional para coroa total. Após escaneamento digital dos preparos, blocos cerâmicos foram usinados pelo sistema CAD/CAM para obtenção das coroas. A espessura da película de cimento das coroas ao preparo foi verificada com silicone de adição. As coroas foram distribuídas nos 4 grupos conforme o tratamento da superfície cerâmica (n=10): (HF)- HF à 4.9% por 20s + spray ar-água por 30s; (HFN)- HF + agente neutralizador por 5 min (N); (HFU) - HF + banho sônico por 5 min (U); e (HFNU)- HF + N + U. Após aplicação de uma camada de silano (60s), as coroas foram cimentadas com cimento resinoso dual. Uma carga compressiva de 1000Kg foi aplicada no centro da face oclusal da coroa com velocidade de 1 mm/min até a fratura. Os dados foram analisados por ANOVA e Tukey (α=0,05). A carga média de fratura (Kgf) foi: HF = 169,92 ± 21,37; HFN = 187,34 ± 34,79; HFU = 166,63 ± 40,22 e HFNU = 175,26 ± 40,22. O tratamento da superfície cerâmica após condicionamento ácido não influenciou significativamente (p>0.05) na resistência à fratura das coroas cerâmicas testadas, sugerindo que é desnecessário qualquer tratamento adicional para remoção de resíduos após o uso de HF e lavagem com jato de água-ar / Abstract: The effect of different ceramic surface post hydrofluoric acid (HF) etching cleaning protocols in the fracture strength of lithium dissilicate glass ceramic crowns were evaluated. Forty maxillary third human molars received a conventional full preparation. Crowns were obtained from the digital scanning of the preparations and CAD/CAM blocks machining. Crown cement film thickness was evaluated with vinyl polysiloxane. The crowns were allocated in 4 groups according to the ceramic surface treatment (n=10): (HF)- 4.9% HF for 20s + water spray for 30s; (HFN)- HF + neutralizing agent for 5 min (N); (HFU) -: HF+ sonic bath for 5 min (U) and (HFNU): HF + N + U. After a silane coat (60s), crowns were cemented with dual cure cement. A compressive load of 1000Kg was applied in the occlusal surface center at crosshead speed of 1mm/min until the fracture. Data were analyzed by one-way ANOVA and Tukey tests (α = 0.05). Fracture strength mean for each group was (Kgf): HF = 169.92 ± 21.37; HFN = 187.34 ± 34.79; HFU = 166.63 ± 40.22 e HFNU = 175.26 ± 40.22. There was no statistical difference as the surface treatment (p>0.05) suggesting that it is not necessary any additional ceramic surface treatment in order to remove debris after using of HF and air-water spray rinsing / Doutor

Resumo: O objetivo deste trabalho foi avaliar a translucidez de diferentes cores da cerâmica, o grau de conversão de diferentes cores do agente de fixação resinoso e a resistência de união entre a cerâmica e a dentina, variando as cores da cerâmica e do agente de fixação e o tempo de fotoativação. A hipótese é que quanto mais escuros o agente de fixação resinoso e a cerâmica, menor translucidez, menor conversão dos monômeros, mais baixa será a resistência adesiva, portanto maior tempo necessário para fotoativação. Três discos da cerâmica Vita VM7 com dimensão de 20 x 2 mm nas cores Base Dentine 0M1, Base Dentine 2M2 e Base Dentine 5M3 e dois discos com 20 x 2,5 mm da mesma cerâmica nas cores Base Dentine 0M1 e Base Dentine 5M3 foram usados para determinar a percentagem de translucidez através do espectrofotômetro MiniScan. Para se obter o grau de conversão (GC), os cp do agente de fixação (Variolink II; A3 Amarelo e transparente; espessura: 100 μm) foram fotoativados sob um bloco cerâmico (espessura: 2 mm; Base Dentine 0M1, Base Dentine 2M2 e Base Dentine 5M3) por 20 ou 40 s. Cp fotoativados sem o bloco cerâmico foram usados como controle. Dezesseis grupos (n=3) foram avaliados. Espectrometria de Micro- ATR/FTIR foi utilizada para avaliar a extensão da polimerização de todos os cp depois de 24 h. A %GC foi calculada e os dados foram analisados através de ANOVA 1-fator e teste de Tukey ( =0,05). Para avaliar adesão, a dentina da superfície oclusal de 80 molares humanos hígidos foi exposta e condicionada com ácido fosfórico 37% e adesivo (Excite DSC). Oitenta blocos (7,2 x 7,2 x 2,5 mm) da mesma cerâmica, nas cores Base Dentine 0M1 e Base Dentine 5M3, foram confeccionados de acordo com as instruções do fabricante. A superfície cerâmica foi tratada com ácido fluorídrico 10% por 60 s e silanizada. Os blocos cerâmicos de cada cor foram cimentados... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to evaluate the translucency of different ceramic shades, degree of conversion of different resin cement and the bond strength between a feldspathic ceramic and dentin using different resin cement and ceramic shades, and the activation time. The hypothesis is the darker the resin cement and ceramic, lower the translucency; the lower the degree of monomers conversion, lower the bond strength, then the activation time should be higher. Three discs of Vita VM7 ceramic with 20 x 2 mm and shades: Base Dentine 0M1, Base Dentine 2M2 and Base Dentine 5M3, and two discs with 20 x 2.5 mm of the same ceramic and shades: Base Dentine 0M1 and Base Dentine 5M3 were used to determine the translucency percentage of each sp using the MiniScan espectrophotometer. For measure the degree of conversion (DC), the resin cement (Variolink II; A3 Yellow and transparent) specimens (thickness: 100 μm) were photocured under a ceramic block (2mm-thick; Base Dentine 0M1, Base Dentine 2M2 and Base Dentine 5M3) for 20 or 40 s. Specimen photocured without the ceramic block were used as control. Sixteen groups (n=3) were evaluated. Micro-ATR/FTIR spectrometry was used to evaluate the extent of polymerization of all sp after 24 h. The %DC was calculated and the data were analyzed using ANOVA 1-way and Tukey test ( =0,05). For the microtensile bond strength test, the occlusal dentin surface of eighty molars were exposed and etched with 37% phosphoric acid and an adhesive (Excite DSC) was applied. Eighty blocks (7.2 x 7.2 x 2.5 mm) of Base Dentine 0M1 and Base Dentine 5M3 of Vita VM7 ceramic were produced according to the manufacturers. The ceramic surface was etched with 10% hydrofluoric acid for 60 s, followed by the application of a silane agent and a dualcured resin cement (Variolink II; base and catalyst: A3 Yellow; base and catalyst: transparent), according to the manufacturers' ...(Complete abstract click electronic access below) / Orientador: Estevão Tomomitsu Kimpara / Coorientador: Amin Sami Rizkalla / Banca: Anderson Pinheiro de Freitas / Banca: Marco Antonio Bottino / Banca: Mario Alexandre Coelho Sinhoreti / Banca: Paula Komori / Doutor

This work was on the effect of electric current on the processing of ceramics. The focus was on electromigration/electrochemistry and plasma effects. While there is no solid evidence that there is plasma in Spark Plasma Sintering, (SPS), newer techniques e.g. flash, use different conditions so there is an interest in understanding the conditions under which a plasma forms. The minimum arcing voltage was found from literature to be from 10-15V for materials of interest. This is above that found in SPS (10V). However, due to the many contact points in a powder compact much higher voltages (50V) were required in practical experiments. Optical spectroscopy was used to verify the formation of a plasma, and emission peaks from the powder compact material were visible implying they were vaporised and formed the plasma. Electromigration was exploited to alter the oxidation of zirconium diboride, by passing current through the oxide layer (120μm zirconia base grown at 1200°C) oxygen could be pumped either away or toward the diboride bulk. Small cubes (3mm) of diboride had platinum foil electrodes applied on both sides and oxidation was performed at 1400°C for 5hr. Without a field the oxide grew to 360μm, by applying 10V and 100mA the oxide grew to 150μm under the +ve electrode but 1400μm under the -ve electrode. Electrochemical reduction was believed to have occurred due to the electrical properties of the material changing during oxidation and visible blackening of the oxide. Combining the techniques from both earlier works, a contactless flash sintering setup was developed. This used two plasma arcs as electrodes to heat and pass current through the sample. Various materials, currents and times were used, but the best result was with SiC:B4C which was sintered in 3s with 6A, the microstructure showed sharp grains, no segregation and limited grain growth ( initially 0.7μm SiC and 0.5μm B4C, this grew to 1.1μm and 1.4μm). This was the first recorded case of contactless flash sintering and the technique has the potential to sinter ceramics in a continuous manner.

Essa tese versa sobre um procedimento inovador para o controle e garantia da qualidade em processos de manufatura onde existem vários atributos e variáveis a serem monitorados, como acontece, por exemplo, na indústria cerâmica. O procedimento proposto, chamado de controle integrado da qualidade, começa com a definição de alguns postos de controle na linha de produção, onde o monitoramento será feito usando uma única carta de controle que agrega vários atributos e variáveis. Esse procedimento é complementado usando gráficos de Pareto, que hierarquizam as características de qualidade que contribuem mais fortemente para o percentual de defeituosos do posto, e as cartas de controle tradicionais, que são utilizadas seletivamente, apenas conforme a indicação dos gráficos de Pareto. A utilização conjunta dessas ferramentas auxilia no diagnóstico e solução dos problemas de qualidade, permitindo que as ações de melhoria aconteçam no tempo e local certo. Entre as vantagens do procedimento proposto, cita-se: (a) a simplicidade do controle integrado, que foca prioritariamente umas poucas cartas de controle; (b) a abordagem estatística, que fornece uma base sólida para a tomada de decisões; e (c) o forte apelo gerencial fornecido pelo controle integrado, que disponibiliza a cada amostra uma visão geral da condição de qualidade nos postos de controle e na linha de produção como um todo. A tese apresenta também uma abordagem sistemática para auxiliar na implantação do controle integrado da qualidade. Essa abordagem contempla 5 etapas principais: definição do projeto, planejamento da implantação, treinamento, implantação efetiva e acompanhamento e consolidação. Por fim, é apresentado e discutido um estudo de caso em uma indústria cerâmica, que contribui para a validação do método proposto. Com base nesse estudo de caso e no referencial teórico, conclui-se sobre o assunto. / This dissertation presents a new procedure, Integrated Quality Control, for quality control and assurance in situations where severa! variables and attributes are to be monitored. That is the case in the ceramics manufacturing industry, for example. The procedure is implemented by defining control (or work) stations in the production line; variables and attributes in each station are monitored simultaneously using an aggregated control chart for the percentages of non-conformities. When a signal occurs, a Pareto graph sorts out variables and attributes identifying those contributing the most to its occurrence: such variables and attributes are then examined using traditional control charts. The joint use of aggregate charts, Pareto graphs and univariate control charts turns monitoring and improvement of processes into a non-complex task. A systematic approach for the implementation of Integrated Quality Control is also presented. The approach comprises five main steps: project definition, implementation planning, training of personnel, effective implementation, and follow up. Key advantages of the procedure suggested here are: (i) ability to handle variables and attributes in a single integrated chart, (ii) the statistical approach which provides a solid basis for the decision-making, and (iii) strong managerial appeal provided by the integrated charts. The procedure is illustrated with a case study conducted in a ceramic plant. Some conclusions are drawn based on the results of this case study and in the theoretical references.

The dissertation follows the trajectory of one of the commodities of the transpacific trade, Chinese porcelain, from the city of Jingdezhen where it was produced, to Manila where it was sold to Spanish merchants, on to Mexico, where it was adopted by the colonial society. The study ends in the city of Puebla where potters drew inspiration from Chinese porcelain for the invention of a new ceramic style known as loza poblana. The methodology of following the trajectory of Chinese porcelains through various sites reveals a new kind of history, one where the tactile aspects of the circulation of goods become salient. The places, contexts, and transactions that the commodities passed through are more prominent--the trade is no longer an abstract exchange between different parties or an endeavor driven purely by imperial greed. Instead it emerges as a process that developed from an interaction between global material forces and local histories and contingencies. Such a tactile history also provides details about the movement and transfer of aesthetics in the early modern period, as seen in the case of the design of the Chinese guan, a jar form, that was adapted to make the Mexican chocolatero.

Este estudo tem por objetivo formular um composto cerâmico para revestimento de paredes visando contribuir para a otimização da blindagem de salas de diagnóstico. O trabalho foi baseado em medidas experimentais de atenuação da radiação X (80 e 100 kV) empregando materiais cerâmicos de revestimento contendo diferentes suportes cerâmicos (vermelho, branco, grês, porcelanatos, etc). Dentre os suportes cerâmicos avaliados, o grês branco apresentou melhores propriedades atenuadoras, e foi considerado o mais adequado para a proposta deste trabalho. Diferentes formulações de grês branco foram estudadas e alteradas a fim de obter melhores propriedades atenuadoras. Foram efetuadas simulações de composições cerâmicas de revestimento grês dentro das porcentagens de matérias-primas necessárias na composição que são 12-20% argila; 6-18% caulim; 12-25% filito; 8-14% quartzo; 10-18% feldspato; 32- 40% pegmatito; 6-8% talco. As composições químicas quantitativas e qualitativas destes materiais foram também avaliadas, e os elementos constituintes mais comuns são SiO2, Fe2O3, Al2O3, CaO e Ti2O3. Considerando que o CaO pode ser substituído pelo PbO ou BaO, foram estudadas formulações com maiores teores de óxidos de Pb e Ba. O comportamento destes materiais como atenuadores para a radiação X foi investigado por meio de simulações computacionais que levaram em consideração os espectros de raios X incidentes e transmitidos através das diferentes composições estudadas e comparado com os materiais de referência Pb, Ba e BaSO4 (barita). Os resultados obtidos nas simulações indicaram as formulações do composto de suporte cerâmico grês que demonstram melhores propriedades de atenuação levando-se em conta as energias usadas em raios X diagnóstico (80, 100 e 150 kV). Placas cerâmicas baseadas na composição formulada que apresentou menor diferença percentual em relação ao Pb foram produzidas em laboratório e testadas fisicamente como revestimento de parede e barreira protetora. Propriedades como módulo de resistência à flexão, densidade, carga de ruptura, absorção de água e atenuação da radiação X foram avaliadas para todas as placas produzidas. / This study aims to formulate a ceramic composition for wall coating seeking to contribute to the optimization of diagnosis rooms’ shielding. The work was based on experimental measures of X-radiation attenuation (80 and 100 kV) using ceramic coating materials containing different ceramic bases (red, white, grês, stoneware porcelain tiles, etc). Among the appraised ceramic bases, the white grês presented better attenuation properties and it was considered the most suitable material for the targets of this work. Different formulations of white grês were studied and altered in order to obtain better attenuation properties. Simulations of ceramic compositions using grês coating were made maintaining the percentages of 12-20% clay; 6-18% kaolin; 12-25% phyllite; 8-14% quartz; 10- 18% feldspar; 32-40% pegmatite and 6-8% talc in the composition of the necessary raw-material. The quantitative and qualitative chemical compositions of these materials were also evaluated and the most common representative elements are SiO2, Fe2O3, Al2O3, CaO and Ti2O3. Formulations containing Pb and Ba oxides were studied, considering that CaO can be replaced by PbO or BaO. The attenuation properties for X-radiation were investigated by computer simulations considering the incident and transmitted X-ray spectra for the different studied compositions and they were compared to the properties of the reference materials Pb, Ba and BaSO4 (barite). The results obtained with the simulations indicated the formulated composition of grês ceramic base that presented better attenuation properties considering the X-ray energies used in diagnosis (80, 100 and 150 kV). Ceramic plates based on the formulated compositions that presented lower percentage differences related to Pb were experimentally produced and physically tested as wall coating and protecting barrier. Properties as flexion resistance module, density, load rupture, water absorption and Xradiation attenuation were evaluated for all produced plates.

A utilização da lama residual de marmoraria em cerâmica vermelha foi colocada em prática visando à diminuição do impacto ambiental, causado tanto pelo descarte da lama como também pela quantidade de argila extraída no setor cerâmico. Foram coletadas amostras em 12 marmorarias localizadas na Grande São Paulo. No entanto, apenas as amostras de quatro foram selecionadas para serem incorporadas, levando em consideração suas características distintas. O argilito foi a matéria-prima escolhida para confecção da massa padrão de cerâmica vermelha, devido à sua grande utilização no setor. Tanto as amostras a serem incorporadas, quanto o argilito, foram caracterizados por meio de análise granulométrica, análise química por fluorescência de raios X e análise mineralógica por difração de raios X; além de análises segundo à norma NBR 10004 nas lamas. Após a caracterização das matérias-primas, foi aplicado às misturas o ensaio de plasticidade; em seguida, confeccionados corpos-de-prova com diversos teores de lama incorporada, os quais foram queimados e submetidos a ensaios tecnológicos, como resistência mecânica, absorção de água, porosidade, massa específica aparente e retração, dilatação do material seco e microscopia eletrônica de varredura. Os resultados demonstraram a viabilidade de aproveitamento destas lamas, apontando vantagens de sua utilização, porém levando em consideração algumas condições adotadas. / In order to decrease environmental impact, caused by mud discarding and clay extraction in the ceramic industry, it was used residual mud from marble and granite companies for structural ceramic. Samples were collected in twelve different marble companies located at the metropolitan region of São Paulo. However, only four samples were selected, based on its different characteristics. Claystone was the raw material chosen to prepare the structural ceramic, considering its high use in this segment. Samples and claystone were both analysed by the following procedures: granulometric analysis, x-rays fluorescent chemical analysis and x-rays diffraction mineralogical analysis, besides, tests in the samples were conducted following NBR 10004 standards. Once raw materials were characterized, the plasticity test was conducted. Test specimen were molded with different levels of mud, then burned and submitted to technological tests, such as: mechanical resistance, water absorption, porosity, specific gravity and retraction, material dilation before burning process and scanning electron microscopy. The final results have shown the viability of using this kind of mud, and pointed some advantages on its usage, but taking in consideration some previous conditions to be adopted.