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Sample records for ceramics avaliacao da

  1. Powder addition assessment of manganese residue ceramic matrix coating; Avaliacao da adicao do po de residuo de manganes em matriz ceramica para revestimento

    Conceicao, A.C.R. da; Santos, O.C.; Leao, M.A., E-mail: arangel-ma@hotmail.com [Instituto Federal de Educacao, Ciencia e Tecnologia da Bahia (IFBA), BA (Brazil)

    2016-07-01

    The use of recycled materials in the composition of new products follows the production's worldwide trending, meeting new technological requirements and environmental concerns. This work aims to utilize the residue of manganese dust on ceramic mass for the production of ceramic coating. The raw materials were characterized by both x-ray fluorescence and diffraction. The powder residue added to clay in the percentage of 0%, 5%, 10% and 15% (measured in weight) was compressed by a uniaxial pressing of 30MPa and the sintering temperatures were 900°, 1000° and 1100°. The samples were analysed in relation to flexural strength, bulk density, water absorption and linear shrinkage. The microstructural variation was also analysed by x-ray diffraction and electron microscopy. The results showed that there is a viability for the production of porcelain ceramic coating (A3 and A4 formulations) and stoneware (A2 formulation) according to the specification of technical standards. author)

  2. Assessment pozzolanicity waste red ceramics produced in Valley Assu / RN; Avaliacao da atividade pozolanica dos residuos de ceramica vermelha produzidos no Vale do Assu / RN

    Palhares, Rodolfo de Azevedo; Pereira, Arthur Ruan da Silva; Cabral, Kleber Cavalcanti; Nobrega, Andreza Kelly Costa, E-mail: rodolfo.palhares@hotmail.com, E-mail: arthurruan_rn@hotmail.com, E-mail: kleber.cabral@ufersa.edu.br, E-mail: akcn123@hotmail.com [Universidade Federal Rural do Semi-Arido (UFERSA), Mossoro, RN (Brazil). Departamento de Ciencias Exatas

    2016-07-01

    It is known that both the cement industry as a ceramist contribute much to the generation of environmental impacts. Be the Co2 in the atmosphere, as well as the generation of excessive waste, reaching 20%. The objective of this study is to analyze the potential pozollanic of waste from the red ceramic industries Valley Assu / RN, in order that this material can be incorporated as alternative raw material in the manufacture of ecological and similar brick, replacing partially in its composition Portland cement. Thus contributing to reducing the environmental impact produced by both the ceramics industry, such as cement. To evaluate the efficiency of pozollanic material, it was made sample preparation and then the physico-chemical characterization. After performing tests, it was noticed that the material has the minimum requirements established in standard to be considered as pozollanic material. (author)

  3. Evaluation of clayey masses compositions starting from the residue incorporation of the red ceramic industry to obtain tubular ceramic membranes; Avaliacao das composicoes de massas argilosas a partir da incorporacao de residuo da industria de ceramica vermelha na obtencao de membranas ceramicas tubulares

    Silva, Adriano Lima da; Chaves, Alexsandra Cristina; Luna, Carlos Bruno Barreto; Neves, Gelmires de Araujo; Lira, Helio de Lucena, E-mail: adrianolimadasilva@hotmail.com, E-mail: alexsandra.chaves@ifap.edu.br, E-mail: brunobarretodemaufcg@hotmail.com, E-mail: gelmires@ufcg.edu.br, E-mail: helio@ufcg.edu.br [Universidade Federal de Campina Grande (UAEMa/CCT/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais

    2017-01-15

    The inappropriate residue disposal of red ceramic industry is very high. Nowadays, one of the major challenges is the investigation of processes to obtain alternative materials, enabling the use of these residues to manufacture new materials. This work's objective is to study clayey masses' compositions starting from the residue incorporation of the red ceramic industry to be used in tubular ceramic membranes. Two compositions of ceramic masses were established, composition A (50% of residue) and composition B (70% of residue). Granulometric analysis of the ceramic masses presented an average size of particles, what indicates membranes in the microfiltration scale. Another observed factor is related to the increase of residue amount, what favored a decrease in the ceramic mass' plasticity. A rise in the apparent porosity was also observed, probably because of a possible growing in the bigger pores numbers, due to the sintering high temperature and the elevation of residue quantity itself. (author)

  4. Evaluation of fracture toughness in dental ceramics using indentation and SEVNB (Single Edge V-Notched Beam)-method; Avaliacao da tenacidade a fratura de ceramicas dentarias atraves do metodo de entalhe - SEVNB (Single Edge V-Notched Beam)

    Santos, L.A.; Santos, C.; Souza, R.C.; Ribeiro, S. [Universidade de Sao Paulo (DEMAR/EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de Lorena. Dept. de Engenharia de Materiais. Polo Urbo-Industrial; Strecker, K. [Universidade Federal de Sao Joao del-Rei (DME/UFSJ), MG (Brazil). Dept. de Materiais Eletricos; Oberacker, R. [Karlsruhe Univ. (Germany)

    2009-07-01

    In this work, the fracture toughness of different ceramics based on Al{sub 2}O{sub 3} and ZrO{sub 2} were evaluated using, comparatively two methods, Vickers indentation and SEVNB (Single Edge V-Notched Beam) method. Al{sub 2}O{sub 3}, ZrO{sub 2}(3%Y{sub 2}O{sub 3}) micro-particled and ZrO{sub 2}(3%Y{sub 2}O{sub 3}) nanometric, ZrO{sub 2}-Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-ZrO{sub 2} composites were sintered at different temperatures. Samples were characterized by relative density, X-ray diffraction, SEM, and mechanical evaluation by hardness, bending strength and fracture toughness obtained by ickers indentation and SEVNB-method. The results were presented comparing the densification and microstructural results. Furthermore, the advantages and limitations of each method were discussed. (author)

  5. Avaliacao de projeto de promocao da saude para adolescentes

    Jovino Oliveira Ferreira

    2013-06-01

    Full Text Available OBJETIVO: Avaliar programa de promoção de atividade física e de escolhas alimentares entre adolescentes. MÉTODOS: Estudo transversal realizado com 911 adolescentes de 13 a 18 anos de idade, de escolas públicas de Goiânia, GO, em 2010. Os participantes foram divididos em dois grupos: intervenção (escolas participantes do Projeto Viver Saudável e controle. Foram considerados como atividade física: deslocamento, aulas de educação física na escola, atividade física fora da escola e no lazer. Foram definidos como ativos aqueles que acumularam 300 ou mais minutos por semana. Quanto às escolhas alimentares, foi classificado como adequado o consumo de alimentos protetores em cinco ou mais dias da semana. Foram realizadas análises estatísticas com teste de Qui-quadrado de Pearson. RESULTADOS: A maioria dos adolescentes foi identificada como inativos ou insuficientemente ativos, com 65,7% no grupo intervenção e 65,2% no grupo controle, sem diferenças significativas entre os grupos e com prevalência maior entre o sexo feminino. Pouco mais da metade dos adolescentes consumiam alimentos protetores da saúde em cinco ou mais dias da semana, sendo 56,6% e 50,4%, respectivamente, nos grupos intervenção e controle (p = 0,373. CONCLUSÕES: A ausência de diferenças quanto a escolhas alimentares e prática de atividade física entre os grupos intervenção e controle indica que o projeto Viver Saudável precisa ser reavaliado visando melhorar a efetividade no cumprimento dos seus objetivos.

  6. Avaliacao de interacoes medicamentosas potenciais em prescricoes da atencao primaria de Vitoria da Conquista (BA), Brasil

    Danyllo Fabio Lessa Leao; Cristiano Soares de Moura; Danielle Souto de Medeiros

    2014-01-01

    As interações medicamentosas são fatores de risco para a ocorrência de reações adversas a medicamentos. Este estudo teve o objetivo de avaliar as interações medicamentosas potenciais em prescrições da atenção primária de Vitória da Conquista (BA), visando preencher a lacuna de conhecimento sobre essa temática no Brasil. Foram coletadas informações sobre diversas variáveis de prescrições oriundas da atenção primária e as interações medicamentosas avaliadas a partir dos bancos de dados do Medsc...

  7. Instrumentos em Lingua Brasileira de Sinais para avaliacao da qualidade de vida da populacao surda

    Neuma Chaveiro

    2013-06-01

    Full Text Available OBJETIVO: Construir a versão em Língua Brasileira de Sinais dos instrumentos WHOQOL-BREF e WHOQOL-DIS para avaliar a qualidade de vida da população surda brasileira. MÉTODOS: Utilizou-se metodologia proposta pela Organização Mundial da Saúde (WHOQOL-BREF e WHOQOL-DIS para a construção dos instrumentos adaptados para população surda em Língua Brasileira de Sinais (Libras. A pesquisa para execução do instrumento consistiu de 13 etapas: 1 criação do sinal qualidade de vida; 2 desenvolvimento das escalas de respostas em Libras; 3 tradução por um grupo bilíngue; 4 versão reconciliadora; 5 primeira retrotradução; 6 produção da versão em Libras a ser disponibilizada aos grupos focais; 7 realização dos grupos focais; 8 revisão por um grupo monolíngue; 9 revisão pelo grupo bilíngue; 10 análise sintática/semântica e segunda retrotradução; 11 reavaliação da retrotradução pelo grupo bilíngue; 12 filmagem da versão para o software; 13 desenvolvimento do software WHOQOL-BREF e WHOQOL-DIS em Libras. RESULTADOS: Características peculiares da cultura da população surda apontaram a necessidade de adaptações na metodologia de aplicação de grupos focais quando compostos por pessoas surdas. As convenções ortográficas da escrita das línguas sinalizadas não estão consolidadas, o que trouxe dificuldades em registrar graficamente as etapas de tradução. As estruturas linguísticas que causaram maiores problemas de tradução foram as que incluíram expressões idiomáticas do português, muitas sem conceitos equivalentes entre o português e a Libras. Foi possível construir um software do WHOQOL-BREF e WHOQOL-DIS em Libras. CONCLUSÕES: O WHOQOL-BREF e o WHOQOL-DIS em Libras possibilitarão que os surdos se expressem autonomamente quanto a sua qualidade de vida, o que permitirá investigar com maior precisão essas questões.

  8. Avaliacao de interacoes medicamentosas potenciais em prescricoes da atencao primaria de Vitoria da Conquista (BA, Brasil

    Danyllo Fabio Lessa Leao

    2014-01-01

    Full Text Available As interações medicamentosas são fatores de risco para a ocorrência de reações adversas a medicamentos. Este estudo teve o objetivo de avaliar as interações medicamentosas potenciais em prescrições da atenção primária de Vitória da Conquista (BA, visando preencher a lacuna de conhecimento sobre essa temática no Brasil. Foram coletadas informações sobre diversas variáveis de prescrições oriundas da atenção primária e as interações medicamentosas avaliadas a partir dos bancos de dados do Medscape e Micromedex(r. Verificou-se ainda a frequência de polifarmácia e associação desta com a ocorrência de interações medicamentosas. Os resultados mostraram frequência de 48,9% de interações medicamentosas, 74,9% delas de gravidade moderada ou maior, e 8,6% de prescrições em polifarmácia que, em teste qui-quadrado, mostrou associação positiva com ocorrência de interações medicamentosas potenciais (p < 0,001. As prescrições oriundas da atenção primária de Vitória da Conquista (BA apresentaram uma alta frequência de interações medicamentosas, porém faz-se necessária a análise de outros fatores de risco para ocorrência destas nesse nível de atenção à saúde.

  9. Assessment of stability of ceramics type perovskite, Ba{sub 2}MgWO{sub 6}, submerged in crude oil taken from oil wells of Sergipe - Brazil; Avaliacao da estabilidade de ceramicas tipo perovskita, Ba{sub 2}MgWO{sub 6}, submersas em petroleo cru retirado de pocos do estado de Sergipe - Brasil

    Yadava, Y.P.; Sales, D.G.; Lima, M.M.; Ferreira, R.A.S. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)], e-mail: daniella_guedes@yahoo.com.br

    2008-07-01

    Oil wells are harsh environments, thus, it is necessary to find materials that are able to resist the weather imposed by these sites. Many of the new technology incorporating ceramic components because their chemical properties, electrical, mechanical, thermal and structural. The ceramics exhibit high hardness and therefore resistant to high pressure, have high melting point, resisting the high temperatures, and make inert nature in hostile environments. The ceramics, type Perovskite Ba{sub 2}MgWO{sub 6}, were submerged in crude oil for thirty days and then examined by X-ray diffraction, optical microscopy and Vickers microhardness to see if there were changes in structural characteristics, microstructural and mechanical properties. This work was evaluated and discussed by these results, the stability of these ceramics when subject to attack by crude oil taken from oil wells of land and sea state of Sergipe, Brazil. (author)

  10. Avaliacao da Relacao entre a Doenca Hepatica Nao Gordurosa e CAD utilizando TCMF

    Duran Efe

    2014-01-01

    Full Text Available Fundamento: Alguns fatores de risco para a aterosclerose são acompanhados pela doença hepática gordurosa não alcoólica (DHGNA. Desejamos usar a tomografia computadorizada multi-fatias (TCMF como a técnica para encontrar relação entre a DHGNA e a doença arterial coronariana (DAC. Objetivo: A relação entre a DHGNA e a DAC foi investigada através de TCMF. Métodos: Um total de 372 indivíduos com ou sem sintomas cardíacos, que foram submetidos à angiografia por TCMF, foram incluídos no estudo. Os pacientes foram divididos em dois grupos, de acordo com a presença da DHGNA. Os segmentos arteriais coronarianos foram avaliados visualmente via angiografia por TCMF. Com base no grau de estenose arterial coronariana, aqueles com placas ausentes ou mínimas foram considerados como normais, enquanto aqueles que apresentavam estenose de menos do que 50% e no mínimo uma placa foram considerados como portadores da doença arterial coronariana não obstrutiva (não-obsDAC. Os pacientes que apresentaram no mínimo uma placa e estenose arterial coronariana de 50% ou mais foram considerados como portadores de doença arterial coronariana obstrutiva (obsDAC. A DHGNA foi determinada de acordo com o protocolo de TCMF, utilizando a densidade hepática. Resultados: De acordo com a densidade hepática, o número de pacientes com doença hepática gordurosa não alcoólica (grupo 1 foi de 204 (149 homens, 54,8% e com fígado normal (grupos 2 foi de 168 (95 homens, 45.2%. Houve 50 (24,5% não-obsDAC e 57 (27,9% casos de obsDAC no Grupo 1, e 39 (23,2% não-obsDAC e 23 (13,7% casos de obsDAC no Grupo 2. Conclusões: O presente estudo utilizando TCMF demonstrou que a frequência da doença arterial coronariana em pacientes com NAFDL foi significativamente superior do que nos pacientes em NAFDL.

  11. Avaliacao da seguranca de diferentes doses de suplementos de acido folico em mulheres do Brasil

    Quenia dos Santos

    2013-10-01

    Full Text Available OBJETIVO Avaliar a distribuição da ingestão de ácido fólico e a segurança de diferentes doses de suplementos em mulheres em idade reprodutiva. MÉTODOS Foram utilizados dados de consumo a partir de dois dias não consecutivos de registro alimentar de 6.837 mulheres em idade reprodutiva (19 a 40 anos participantes do Inquérito Nacional de Alimentação, módulo da Pesquisa de Orçamentos Familiares 2008-2009. Médias e percentis de consumo habitual de folato natural e ácido fólico foram estimados utilizando o método do National Cancer Institute . Cinco cenários foram simulados somando-se diferentes doses diárias de fortificação (400 mcg, 500 mcg, 600 mcg, 700 mcg e 800 mcg ao ácido fólico oriundo dos alimentos consumidos pelas mulheres. Comparou-se o total de ácido fólico (dieta + suplemento com o nível máximo de ingestão tolerável (UL = 1.000 mcg para definir a dose segura de suplementação. RESULTADOS Mulheres com ingestão habitual de ácido fólico acima do nível máximo de ingestão tolerável foram observadas para doses de suplemento de 800 mcg (7,0% das mulheres. Abaixo desse valor, qualquer dose de suplementação mostrou-se segura. CONCLUSÕES O uso de suplementos de até 700 mcg de ácido fólico mostrou-se seguro.

  12. Leitura rapida do KDIGO 2012: Diretrizes para avaliacao e manuseio da doenca renal cronica na pratica clinica

    Gianna Mastroianni Kirsztajn

    2014-03-01

    Full Text Available Os autores desta "leitura rápida" apresentam os dados que consideraram mais relevantes na versão 2012 do KDIGO referente à avaliação e manuseio da doença renal crônica. Não se trata da opinião dos autores, mas sim de uma apresentação mais concisa das diretrizes, que podem ser úteis na prática clínica.

  13. Avaliacao da espessura medio-intimal em pacientes com doenca renal cronica nao dialitica: estudo prospectivo de 24 meses

    Andrea Gaspar Marcos

    2014-03-01

    Full Text Available Introdução: O aumento da espessura média-intimal (EMI avaliada por ultrassom é um preditor de risco cardiovascular na população geral. Porém, em pacientes com doença renal crônica nos estágios iniciais, essa associação ainda não está bem estabelecida. Objetivo: Avaliar a associação EMI com a ocorrência de eventos cardiovasculares e mortalidade em pacientes nos estágios iniciais da doença renal crônica. Métodos: A análise post hoc de uma coorte de pacientes nos estágios 2-4 da DRC. Foram avaliados dados laboratoriais, ultrassom da artéria carótida e tomografia coronariana no início do estudo e a ocorrência de óbito, em seguimento por 24 meses. Resultados: Um total de 117 pacientes (57 ± 11 anos, 61% sexo masculino foram avaliados. A taxa de filtração glomerular foi 36 ± 17 mL/min, 96% dos pacientes eram hipertensos, 23% diabéticos e 27% obesos. Calcificação arterial coronariana esteve presente em 48% dos pacientes, sendo mais prevalente em pacientes nos estágios mais avançados da DRC (p = 0,02. EMI foi 0,6 mm (0,4-0,7 mm. Comparado aos pacientes com EMI < 0,6mm, aqueles com EMI ≥ 0,6 mm eram mais velhos (p = 0,001, apresentavam maior prevalência do sexo masculino (p = 0,001, menor taxa de filtração glomerular (p = 0,01 e maior proporção de pacientes com calcificação (p = 0,001. Não foi observada relação entre a espessura média-intimal e a ocorrência de evento cardiovascular e óbito. Conclusão: A espessura médio-intimal em pacientes DRC se associou à calcificação coronariana, mas não à ocorrência de eventos cardiovasculares e óbito, em um seguimento de 24 meses.

  14. Evaluation of elemental composition of clays from Campos Gerais (MG); Avaliacao da composicao elementar de argilas de Campos Gerais (MG)

    Martins, Joao P.M.; Maduar, Marcelo F.; Silva, Paulo S.C da, E-mail: jpmm0697@hotmail.com [Instituto de Pesquisas Energeticas e nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    There are numerous applications given to clays including oil and water adsorbent, ceramic, whitening of beverages, porcelain, waste treatment, organic carrier molecules in cosmetics and pharmaceuticals, support for catalysts. In the pharmaceutical industry, the clays are used as excipients, diluents, desiccants, emulsifiers, to mask undesirable flavors, isotonic agent such as charger and delivery of active substances. These characteristics have contributed to the expansion of the search for applications of clay minerals in the cosmetic industry. The aim of this study was to determine the elemental composition of clays from Campos Gerais, Minas Gerais, with a view to their applicability in the production of cosmetics. The elements As, Ba, Br, Ce, Cl, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th,U, Yb and Zn were determined by neutron activation analysis and radionuclide activity concentration of {sup 226}Ra, {sup 228} Ra, {sup 210}Pb and {sup 40}K were determined by gamma spectrometry. It was verified that the activity concentration of radionuclides was in the same concentration as the global average, indicating that these samples do not present a risk of increased radiation exposure. The concentration of most elements determined is less than or equal to the overall mean concentrations, indicated by the values of Continental Upper Crust. (author)

  15. AIDS related thoracic lymphoma: evaluation by computed tomography; Linfoma toracico na sindrome da imunodeficiencia adquirida: avaliacao por tomografia computadorizada

    Siciliano, Antonio Alexandre de Oliveira [Hospital Universitario Clementino Fraga Filho, Rio de Janeiro, RJ (Brazil). Servico de Radiodiagnostico; Marchiori, Edson [Universidade Federal, Rio de Janeiro, RJ (Brazil). Curso de Pos-graduacao em Radiologia

    2000-02-01

    The authors reviewed five cases of patients with acquired immunodeficiency syndrome (AIDS) related lymphoma to describe the thoracic findings on computed tomography. The patients were followed at Hospital Universitario Clementino Fraga Filho, Hospital Universitario Antonio Pedro and Hospital da Lagoa, from November, 1989 to March 1998. Epidemiological, clinical and pathological data from these patients were quiet variable and pulmonary nodules and masses, hilar and mediastinal lymphadenopathy, and thoracic wall masses were observed. AIDS related lymphomas involving the chest are pleomorphic and most commonly extranodal. (author)

  16. Evaluation of solid waste and plastic clay mixtures for structural ceramic use; Avaliacao de misturas de residuo solido com argila plastica para aplicacao em ceramica vermelha

    Silva, Neli Iloni Warpechowski da [Fundacao de Ciencia e Tecnologia (CIENTEC), Porto Alegre, RS (Brazil); Belo, Pedro [Ceramics Representacoes Comerciais Ltda, Porto Alegre, RS (Brazil)

    1996-07-01

    This work aims to verify the behaviour of the organic solid waste added by 10%, 15% and 20% in mixture in a plastic clay. It intends to emphasize the influence of the waste in the mixture. Technology tests have been carried out in the clay and mixtures to obtain possible uses in the structural ceramics. (author) 1 ref., 4 figs., 2 tabs.

  17. Evaluation of the reuse of glass and ceramic blocks in the development of a ceramic products; Avaliacao do reaproveitamento de blocos ceramicos e de vidro no desenvolvimento de um produto ceramico

    Rodrigues, R.A.; Silva, L.A.; Martins, B.E.D.B.S.; Felippe, C.E.C.; Almeida, V.C., E-mail: valeria@eq.ufrj.b [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Escola de Quimica

    2010-07-01

    The ceramic industry has enormous potential to absorb wastes. The main objective of this study was to evaluate the feasibility of reusing leftovers ceramic blocks, from construction and, with shards of glass in the development of a ceramic product. The ceramic pieces were prepared with different compositions of glass by the method of pressing conformation and heating at 1000 and 1100 deg C. The conformed pieces were tested for linear shrinkage, water absorption, porosity, and tensile strength. The techniques for characterization were X-ray fluorescence, X-ray diffraction and scanning electron microscopy, the results show that the ceramic material produced has a high flexural strength and low values of water absorption. (author)

  18. Evaluation of the potential of waste fondant glass in formulations of ceramic pasta; Avaliacao do potencial fundente do residuo de vidro em formulacoes de massas ceramicas

    Soares Filho, J.E.; Santos, L.L. dos; Nascimento, R.M. do, E-mail: elsinhofilho@gmail.com [Universidade Federal do Rio Grande do Norte (PPGCEM/UFRN), RN (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais; Feitosa, A.O.; Dutra, R.P.S. [Universidade Federal da Paraiba (PPCEM/UFPB), PB (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2014-07-01

    An increasing amount of waste generated and deposited on the environment, many unspecified decomposition with time, as is the case of the glass. Thinking about it, the purpose of this study is to evaluate the power of the flux residue on glass formulations porcelains, as a flux to feldspar replacement. This study was performed in comparison with a standard formulation. The raw materials were characterized in the diffraction X-ray fluorescence and X-ray thermal differential analysis, and determination of the technological properties of water absorption, linear contraction, ignition loss, apparent porosity and apparent specific gravity in the formulation standard and replacement of feldspar in different percentages of waste and processing conditions. Specimens of the formulations were subjected to assay of three points. Results indicate that the residue glass has the potential of being used as a flux material in the composition of the ceramic body reduces the apparent porosity and according to the technology of water absorption property. The ceramic mass standard was classified as semi-stoneware, the BIIa group, and after the addition of the residue in any of the three percentages evaluated was classified as sandstone, belonging to the group BIb.(author)

  19. Chemical treatment and biomimetic coating evaluating in zirconia-alumina ceramics; Avaliacao de tratamentos quimicos e recobrimento biomimetico em ceramicas de alumina-zirconia

    Aguiar, Amanda Abati

    2007-07-01

    Ceramic materials, as alumina and zirconia have been explored along the years as biomaterials application. The bio inert nature has been stimulating the development of new alternatives, as chemical treatments to improve the biological application of these ceramics. The biomimetic process of bio inert ceramics for coating apatite is based on soaking the implant in a simulated body fluid, SBF, with ion concentrations nearly equal to those of human blood plasma. The bioactivity of the material is related with the formation of a layer constituted of hydroxyapatite low crystalline, similar to the biological apatite. The biocompatibility associated to the structural properties of the alumina and zirconia has been stimulating the clinical use of these materials, mainly in areas of larger mechanical requests, places not recommended for bioactive hydroxyapatite, for instance. In this work samples of alumina, zirconia doped with Yttria (3% mol) and composites of alumina and zirconia doped with Yttria (3% mol) were prepared by co-precipitation method, calcinate, sintered, chemically treated with solutions of acid phosphoric and sodium hydroxide and them immersed in 1.0 M and 1.5 M SBF. The calcinate powders were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), gas adsorption (BET) and laser diffraction. The XRD results indicate that the samples are low crystalline. It was observed for BET that the samples present high specific surface area. The results of laser diffraction and SEM showed that the powders are agglomerates. The sintered samples were analyzed by XRD, SEM and X-ray fluorescence (XRF). The phases quantified by Rietveld method were: cubic, tetragonal and monoclinic of the zirconia, besides the phase alpha of the alumina. The chemical treatment with phosphoric acid didn't present a tendency of larger apatite formation in relation to the samples no chemically treated. The treatment with sodium hydroxide provoked accentuated transformation

  20. Assessment of natural radioactivity of sands in beaches from Great Vitoria, ES, Brazil; Avaliacao da radioatividade natural em areias das praias da Grande Vitoria, ES

    Aquino, Reginaldo Ribeiro de

    2010-07-01

    In this work the concentrations of natural radionuclides {sup 226}Ra, {sup 232}Th and {sup 40}K were determined in superficial sand samples for 16 locations throughout the coast of the Great Victory, metropolitan region of the state of Espirito Santo, Southeast of Brazil. The assessed beaches were Manguinhos and Jacaraipe in Serra county, Camburi, Praia do Canto and Curva da Jurema in Vitoria county, Praia da Costa and Itapua in Vila Velha county, Setibao, Setibinha, Praia do Morro, Praia das Castanheiras and Areia Preta in Guarapari county and sand of the Paulo Cesar Vinha Reserve also located in Guarapari county. Three sand samples of each beach were sealed in 100 mL high density polyethylene flasks. After approximately 4 weeks in order to reach secular equilibrium in the {sup 238}U and {sup 2}'3{sup 2}Th series, the samples were measured by high resolution gamma spectrometry and the spectra analyzed with the WinnerGamma software. The self absorption correction was performed for all samples. The {sup 226}Ra concentration was determined from the weighted average concentrations of {sup 214}Pb and {sup 21}'4Bi, the {sup 232}Th concentration was determined from the weighted average concentrations of {sup 228}Ac, {sup 2}'1{sup 2}Pb and {sup 212}Bi and the concentration of {sup 40}K is determined by its single gamma transition of 1460 keV. The radium equivalent concentration and the external hazard index where obtained from the concentrations of {sup 226}Ra, {sup 232}Th and {sup 4}'0K. {sup 226}Ra concentrations show values varying from 3 +- 1 Bq.kg-1 to 738 +- 38 Bq.kg{sup -1}, with the highest values for the central locality of the Camburi beach. {sup 232}Th concentrations show values varying from 7 +- 3 Bq.kg{sup -1} to 7422 +- 526 Bq.kg{sup -1}, with the highest values for Areia Preta beach. {sup 40}K concentrations show values varying from 14 +- 6 Bq.kg{sup -1} to 638 +- 232 Bq.kg{sup -1}, with the highest values for Areia Preta beach

  1. Evaluation of the natural radioactivity at sands of anomalous regions of Espirito Santo state, Brazil; Avaliacao da radioatividade natural em areias de regioes anomalas do Espirito Santo, Brasil

    Aquino, Reginaldo Ribeiro de; Pecequilo, Brigitte Roxana Soreanu, E-mail: raquino@ipen.b, E-mail: brigitte@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-10-26

    The natural radioactivity in sands of anomalous regions of the state of Espirito Santo, Brazil, were calculated from the concentration of activity of {sup 40}K, {sup 225}Ra and {sup 232}Th for the places of south and central of Camburi, Curva da Jurema, Ilha do Boi, Setibinha, south and central area of Praia da Areia Preta, denominated Black Spot. The samples were sealed and measured by high resolution gamma spectrometry and after a expectation time pf 30 days, until to reach a radioactive equilibrium

  2. Evolution of reuse of sludge from water treatment plant in the red ceramic industry; Avaliacao do reaproveitamento do lodo de estacao de tratamento de agua (ETA) na industria ceramica vermelha

    Rodrigues, R.A.; Martins, B.E.D.B.S.; Couto, V.M.P.; Campos, J.C.; Almeida, V.C., E-mail: valeria@eq.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Centro de Tecnologia. Escola de Quimica

    2011-07-01

    The ceramic industry has enormous potential to absorb wastes. The main objective of this study was to investigate whether the use of a sludge (WTP) in the physical and mechanical properties of the burning of a red ceramic body. Compositions were prepared with different percentages of mud by the method of forming the pressed and sintered at 900 deg C, 1000 deg C and 1100 ° C. The specimens were tested for linear shrinkage, water absorption, porosity and stress rupture flexion. Were characterized by X-ray fluorescence, X-ray diffraction and Scanning Electron Microscopy. The results show that the incorporation of sludge WTP changes the quality of ceramics. (author)

  3. Evaluation of the repeatability of dosimetric parameters of a linear accelerator beam; Avaliacao da repetibilidade de parametros dosimetricos do feixe de um acelerador linear

    Morelli, Humberto A.S.; Oliveira, Harley F. de; Silva, Maelson do N.; Pavoni, Juliana F., E-mail: h.morelli@hotmail.com [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Medicina. Servico de Radioterapia

    2016-07-01

    This study aims to evaluate the repeatability of symmetry and flatness of the photon beam of 6 MV linear accelerator Oncor Impression, Siemens, from the Radiotherapy Department of the Hospital das Clinicas da Faculdade de Medicina de Ribeirao Preto - USP. In total they were collected 102 measures, weekly, through two-dimensional detector of ionization chambers, Matrixx Evolution, IBA Dosimetry, connected to a computer with software OmniProI'mrt. The isocenter of the linear accelerator was placed in the center of the sensitive volume of the detector with solid water plates above and below these. Data were collected with 100 UM, with field size 10 x 10 cm². The flatness and symmetry values were calculated by the software used. The first measurement of this work was used as reference, the others were compared with it, taking into account the values of permissible variation for these parameters. The minimum, maximum and average value were analyzed. The literature indicates that the flatness and symmetry values should not vary by more than 2 and 3%, respectively. The results of this work show that the values of these parameters for the linear accelerator study are within the permissible variations in protocols and are therefore able to appropriate clinical use. (author)

  4. Evaluation of physical and mechanical and gaseous emissions in reuse waste in the development of a ceramic products; Avaliacao das propriedades fisica e mecanica e de emissoes gasosas no reaproveitamento de residuos no desenvolvimento de um produto ceramico

    Rodrigues, R.A.; Martins, B.E.D.B.S.; Couto, V.M.P.; Campos, J.C.; Guimaraes, C.S.; Almeida, V.C., E-mail: valeria@eq.ufrj.br [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Centro de Tecnologia. Escola de Quimica

    2011-07-01

    The search for alternative environmentally less aggressive disposal of solid waste has been the path taken to reverse the negative scenario established by the improper disposal of these materials. The aim of this study was to evaluate the recycling of the waste: sludge from water treatment and WTP, glass beads, obtained from the blasting chamber, aiming to develop a ceramic material. Compositions were prepared with different percentages of waste. The ceramic bodies were sintered at 900 deg C, 1000 deg C and 1100 deg C being tested for water absorption and bending failure stress, and characterized by X-ray diffraction We performed the analysis of greenhouse gases released during the burning process. Preliminary results indicate that the ceramic material produced did not show a gain of resistance expected by the introduction of micro glass beads, and that we must observe the legal limits for air emissions coming from burning.(author)

  5. Evaluation of home-made teas efficiency from medicinal plants used on childish diarrhea treatment; Avaliacao da eficacia de chas caseiros de plantas medicinais utilizados no tratamento da diarreia infantil

    Pinto, Magda Moreira; Silva, Maria Jose de Sousa Ferreira da [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Quimica; Vilhena Schayer Sabino, Claudia de; Amaral, Angela Maria [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)

    1996-03-01

    The objective of this work is to verify whether the home-made teas form Brazilian plants, used for control of childish diarrhea have been efficient reaching the composition recommended by World Health Organizations (WHO). This work has been carried out using the neutron activation analysis and the TRIGA MARK I reactor, the IPR-R1, in the Centro de Desenvolvimento da Tecnologia Nuclear - CDTN. (author). 4 refs., 2 tabs.

  6. Physicochemical characterization of ceramics from Sao Paulo II archaeological site; Caracterizacao fisico-quimica da ceramica do sitio arqueologico Sao Paulo II

    Ribeiro, Rogerio Baria

    2013-08-01

    Archaeometry is a consolidated field with a wide application of nuclear analytical techniques for the characterization, protection, and restoration of archaeological pieces. This project aimed at studying the elementary chemical composition of 70 ceramic fragments samples from Sao Paulo II archaeological site, located along the Solimoes River channel, next to Coari city, in Brazilian Amazon. The characterization of samples was performed by neutron activation analysis (NAA). By the determination of 24 elements in the ceramic fragments ( Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Sb, Sm. Rb, Se, Ta, Tb, Th, U, Yb and Zn), it was possible to define groups of samples regarding the similarity/dissimilarity in elementary chemical composition. For such a task, the multivariate statistical methods employed were cluster analysis (C A), principal component analysis (PCA) and discriminant analysis (DA). Afterwards, seven ceramic fragments were selected based on the groups previously established, for the characterization of the site temporal horizon. Those ceramic fragments were analyzed by thermoluminescence (TL) and EPR for dating purposes. The firing temperatures were determined by electron paramagnetic resonance (EPR) technique, in order to infer about some aspects of the ceramic manufacture employed by the ancient peoples that lived in Sao Paulo 11. By the results obtained in this study, it was possible to identify the quantity of clay sources employed by the ceramists and the age of the ceramic pieces. Therefore, the results of this research may contribute to the study on the occupation dynamics in the pre-colonial Brazilian Amazon. (author)

  7. System precision assessment ExacTrac 6D® BrainLab of the Hospital das Clinicas da Faculdade de Medicina da USP; Avaliacao da precisao do sistema Exactrac 6D® BrainLab do Hospital das Clinicas da Faculdade de Medicina da USP

    Maistro, Carlos E.B., E-mail: carloseduardo.bravinmaistro@gmail.com [Programa de Residencia Multiprofissional em Fisica Medica, Faculdade de Medicina de Sao Paulo, SP (Brazil); Nakandakari, Marcos V.N.; Ribeiro, Victor A.B.; Sales, Camila P. de; Rodrigues, Laura N. [Universidade de Sao Paulo (USP), SP (Brazil). Instituto de Radiologia. Servico de Radioterapia. Hospital das Clinicas

    2015-08-15

    The goal of this study was to evaluate the precision of ExacTrac 6D® Brainlab system, installed at Hospital das Clinicas da Faculdade de Medicina da USP, in frameless radiosurgery treatments. Four sets of tests were performed for different purposes in order to assess the following parameters: the accuracy of location through infrared system; evaluation of the reproducibility of fusion algorithm; evaluation of the X-ray system; and the end-to-end test with the goal of assess the overall accuracy of the system. It was found that the infrared system showed a maximum deviation of 0.5 mm in terms of positioning and the X-ray system showed a precision of 0.15 mm and 0.6°. The reproducibility of fusion algorithms provided a maximum deviation in position which was less than 0.5 mm and 0.5° and the quantitative analysis of the results for end-to-end test showed an overall accuracy of the system better than 0.8 mm. (author)

  8. Avaliação da tenacidade à fratura de diferentes sistemas cerâmicos Relative fracture toughness of differents dental ceramics

    Clovis Pagani

    2003-03-01

    Full Text Available Embora as cerâmicas possuam alta resistência à compressão, apresentam friabilidade devido à sua baixa resistência à tração e, desta forma, possuem menor capacidade de absorver impactos. Este trabalho avaliou a tenacidade à fratura de diferentes sistemas cerâmicos, que refere-se à medida da habilidade de absorção da energia de deformação de um material friável. Foram confeccionados 30 corpos-de-prova em forma de discos (5mmx3mm utilizando-se três diferentes materiais cerâmicos, os quais foram divididos em 3 grupos: G1-10 amostras confeccionadas com a cerâmica Vitadur Alpha (Vita-Zahnfabrik; G2-10 amostras confeccionadas com a cerâmica IPS Empress 2 (Ivoclar-Vivadent e G3-10 amostras confeccionadas com a cerâmica In-Ceram Alumina (Vita-Zahnfabrik. Para a obtenção dos valores de tenacidade foi utilizada a técnica da indentação que se baseia na série de fissuras que se formam sob uma carga pesada. Foram realizadas 4 impressões por amostra, utilizado um microdurômetro (Digital Microhardness Tester FM com uma carga de 500gf, durante 10 segundos. A análise estatística dos dados (Testes ANOVA de Kruskal-Wallis e Dunn, indica que a cerâmica In-Ceram Alumina apresentou valor mediano (2,96N/m3/2, estatisticamente diferente do apresentado pela IPS Empress 2 (1,05N/m3/2, enquanto que a cerâmica Vitadur Alpha apresentou valores intermediários (2,08N/m3/2, sem diferenças estatísticas dos outros dois materiais. Conclui-se que as cerâmicas apresentam diferentes desempenhos de tenacidade à fratura, sendo a In-Ceram capaz de absorver maior energia comparada a Vitadur Alpha e ao IPS Empress2.Although ceramics present high compressive strength, they are brittle materials due to their low tensile strength so they have lower capacity to absorb shocks. This study evaluated the fracture toughness of different ceramic systems, which refers to the ability of a friable material to absorb defformation energy. Three ceramic systems were

  9. Advanced ceramics: evaluation of the ground surface Cerâmicas avançadas: avaliação da superfície polida

    E. C. Bianchi

    2003-09-01

    Full Text Available The aim of this research is to evaluate the influence of grinding and cutting conditions on surfaces of advanced ceramics ground with diamond grinding wheels containing a binding resin bond. The quality surface was analyzed by Scanning Electron Microscopy (SEM.O objetivo desta pesquisa é a avaliação da influência das condições de usinagem na superfície gerada de cerâmicas avançadas retificadas com rebolo diamantado com ligante resinóide. A qualidade superficial foi analisada utilizando-se a Microscopia Eletrônica de Varredura (MEV

  10. Cinza da lenha para aplicação em cerâmica vermelha. parte I: características da cinza Firewood ash for application in red ceramic. part I: characteristics of the ash

    M. C. Borlini

    2005-09-01

    Full Text Available A lenha de eucalipto constitui-se no principal combustível utilizado pelas indústrias de cerâmica vermelha do município de Campos dos Goytacazes, Estado do Rio de Janeiro. Em princípio, esta lenha tem características promissoras para adição em cerâmica. Assim, esse trabalho tem por objetivo caracterizar a cinza proveniente da combustão de lenha predominantemente de eucalipto visando a incorporação na massa de cerâmica vermelha processada em indústrias de Campos dos Goytacazes. Foram realizados ensaios de fluorescência de raios X, difração de raios X, distribuição de tamanho de partícula, análise térmica (ATD/TG, porosimetria de mercúrio e microscopia eletrônica de varredura. Os resultados mostraram que a cinza da lenha se apresenta como aglomerados de partículas, sendo constituída principalmente por Ca, Si, Mg, K e S.The eucalyptus firewood is one of the main fuels used by the industries of red ceramic in the municipal area of Campos of Goytacazes, State of Rio de Janeiro. In principle this firewood has promising characteristics for addition into ceramics. Thus, the present work has for objective to characterize the ash generated from burning firewood aiming at its incorporation into red ceramic products. The ash was submitted to X-ray diffraction, chemical composition, particle size distribution, thermal analysis (ATD/TG, mercury porosimetry and scanning electron microscopy tests. The results showed that the ash of the firewood comes as agglomerates of particles, being constituted mainly by Ca, Si, Mg, K and S.

  11. Niobium (V) doped bioceramics: evaluation of the hydrothermal route modified with citric acid and urea to obtain modified hydroxyapatite; Bioceramicas aditivadas com niobio (V): avaliacao da rota hidrotermica modificada com acido citrico e ureia para obtencao de hidroxiapatitas modificadas

    Simomukay, E.; Souza, E.C.F. de; Antunes, S.R.M.; Borges, C.P.F.; Michel, M.D.; Antunes, A.C. [Universidade Estadual de Ponta Grossa (UEPG), Ponta Grossa, PR (Brazil)

    2016-01-15

    Synthetic hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}; HA) has become a widely used ceramic material for bone reconstruction due to its biocompatibility with the bone tissue. This biocompatibility as well as other physical and chemical properties of the hydroxyapatite can be modified by the addition of different ions to its structure. Niobium (V) ion has not been commonly used in the hydroxyapatite synthesis. The objective of this study was to evaluate the use of hydrothermal route in the niobium (V) doped hydroxyapatite synthesis. The route used the niobium ammonium oxalate (NH{sub 4}H{sub 2}[NbO(C{sub 2}O{sub 4}){sub 3}].3H{sub 2}O) complex as a niobium (V) ion precursor. The addition of citric acid and urea in the hydrothermal route is used for the control of synthesis pH and precipitation rate. Pure sample and sample added with 5.3 ppm of niobium (V) ion were prepared. The coexistence of other phases besides the hydroxyapatite was not observed in any of the samples through the use of X-ray diffraction and infrared spectroscopy (FTIR) techniques. The FTIR technique revealed the presence of hydroxyapatite characteristic functional groups. The scanning electron microscopy analysis showed the formation of agglomerates composed of round particles, confirmed by the transmission electron microscopy technique. The X-ray fluorescence spectroscopic analysis detected the presence of niobium in the doped sample. The results showed that niobium (V) doped hydroxyapatite can be synthesized by means of hydrothermal route, which may be considered as huge potential for future application in bioceramics. (author)

  12. Thermal hydraulic evaluation for an experimental facility to investigate pressurized thermal shock (PTS) in CDTN/CNEN; Avaliacao termo-hidraulica da montagem experimental de choque termico pressurizado do CDTN/CNEN

    Palmieri, Elcio T.; Navarro, Moyses A.; Aronne, Ivam D.; Terra, Jose L. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)

    2002-07-01

    The goal of the work presented in this paper is to provide necessary thermal hydraulics information to the design of an experimental installation to investigate the Pressurized Thermal Shock (PTS) to be implemented at Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN). The envisaged installation has a test section that represents, in a small scale, a pressure vessel of a nuclear reactor. This test section will be heated and then exposed to a PTS in order to evaluate the appearance and development of cracks. To verify the behavior of the temperatures of the pressure vessel after a sudden flood through the annulus, calculations were made using the RELAP5/MOD 3.2.2 gamma code. Different outer radiuses were studied for the annular region. The results showed that the smaller annulus spacing (20 mm) anticipates the wetting of the surface and produces a higher cooling of the external surface, which stays completely wet for a longer time. (author)

  13. Evaluation of solubility in simulated lung fluid of metals present in the sludge from a metallurgical industry to produce metallic zinc; Avaliacao da solubilidade em liquido pulmonar simulado dos metais presentes no rejeito gerado por uma industria metalurgica de zinco

    Lima, Rosilda Maria Gomes de

    2012-07-01

    The objective of this study was to determine the solubility parameters (rapid and slow dissolution rates, rapid and slow dissolution fractions) metal particles present in a pile of sludge accumulated under exposure to weathering from the Cia Mercantil Inga, located at the Ilha da Madeira, Sepetiba Bay, Rio de Janeiro. Plant samples collected in the neighboring of the pile and bioindicators placed in the region and collected after some months indicated that the inhabitants of Ilha da Madeira have been exposed to trace elements such zinc, cadmium, mercury and lead, produced during the processing of zinc minerals (hemimorphite - Zn{sub 4}(OH){sub 2}Si{sub 2}O{sub 7}.H{sub 2}O, and willemite - Zn{sub 2}SiO{sub 4}). A static dissolution test in vitro was used to determine the solubility parameters using a simulated lung fluid (SLF), on a time basis ranging from 10 min to 1 year. The metal concentrations in the sludge samples and in the SLF were determined using Particle Induced X-rays Emission (PIXE). In conclusion, this study confirms the harmful effects on the neighboring population of the airborne particles containing these metals that came from the sludge. The solubility parameters obtained for Zn, Cd, Cr, Ni and Mn present in the rapid dissolution fraction in SLF were 0.945; 0.473; 0.226; 0.300 and 0.497, respectively, and the corresponding times for half life of dissolution of the rapid fraction were f{sub r} = 2.082 days; f{sub r} = 0.09 days; f{sub r} = 0.37 days; f{sub r} = 0.332 days ad f{sub r} = 0.99 days; for the slow dissolution fraction times were f{sub r} = 146.95 days; f{sub r} = 63 days; f{sub r} = 86.64 days; f{sub r} = 79.66 days and f{sub r} = 59.84 days. These values indicate that these metals present a moderate absorption level in SLF, and may be classified as M type, according to the International Commission on Radiological Protection (ICRP). The use of solubility parameters allowed a better description of the kinetic behaviour of the sludge in

  14. Influence of gypsum on efflorescence in ceramic tiles; Influence da gipsita no surgimento de eflorescencia em telhas ceramicas

    Monteiro, C.M.O.L. [Servico Nacional de Aprendizagem Industrial (SENAI), Teresina, PI (Brazil); Nascimento, R.M.; Martinelli, A.E. [Universidade Federal do Rio Grande do Norte (PPgCEM/UFRN), Natal, RN (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2009-07-01

    The red ceramic industry is recognized as of major importance in Piaui State. The State capital, Teresina, is the greatest producer of this material, which is used mainly for masonry sealing blocks. One of the most frequent problems in this kind of products is the efflorescence.This paper has the main objective of studying the influence of gypsum on tiles, using the local industry production standards. The raw materials were characterized by FRX, DRX, thermal analysis and sulfates. Extruded test specimens were made with the addition of 1%, 3% and 5% of gypsum in the ceramic paste, burned at 850 deg C, 950 deg C and 1050 deg C and submitted to further technological and analysis for MEV. The reference ceramic paste did not show tendency to efflorescence formation after burning for samples with 1% gypsum added to the paste. The reference ceramic paste showed tendency to efflorescence formation after drying and consolidated efflorescence after burning for samples with 5% gypsum added to the paste. (author)

  15. Caracterização da matéria-prima cerâmica da Mina Tabajara (Limeira, SP Characterization of Tabajara Mine ceramic raw materials (Limeira, SP

    L. H. Godoy

    2011-12-01

    Full Text Available O presente trabalho consiste no estudo das matérias-primas provenientes da Mina Tabajara (Limeira, SP, através da determinação das características químicas, físicas e mineralógicas, ensaios cerâmicos, métodos de controle, petrografia e influência do intemperismo, e em especial da mistura que vem sendo fornecida pela Mina para as indústrias da região. Esta foi elaborada a partir de tentativas e erros baseados na experiência dos ceramistas, o que despertou interesse no sentido de se averiguar os fatores que influenciam e/ou controlam seu comportamento. Individualmente as amostras representativas dos três níveis comercializados não apresentam resultados satisfatórios, ao contrário da mistura. Na mistura, os grãos mais grosseiros da amostra da porção do meio do perfil (L2; 20% são acomodados na matriz formada pelo material da base (L1; 70%, e parte dos interstícios remanescentes são preenchidos por partículas da porção superior (L3; 10%, que é ligeiramente mais fina que a anterior, gerando peças cuja absorção de água é compatível com revestimentos do tipo BIII, a nível de laboratório. A partir da análise dos dados tem-se que a rocha fonte de sedimento juntamente com o ambiente deposicional possuem um papel importante na composição da mineralogia, granulometria e quimismo, que por sua vez relacionam-se diretamente com a capacidade de troca de cátions/ superfície específica e pH, e que todos esses fatores somados influenciam o grau de empacotamento dos grãos na conformação de peças cerâmicas, ocasionando mudanças tanto no grau de absorção de água como na resistência dos corpos de prova.This work is based on the study of materials from Mina Tabajara (Limeira, S. Paulo, by determining the chemical, physical and mineralogical features, ceramic tests, control methods, petrography and weathering influence, and especially the mixture that has been provided by the Mine for the industries of the region. The

  16. Characterization of application of acu sandstone in ceramic mass; Caracterizacao da aplicacao do arenito acu na massa ceramica

    Nobrega, L.F.P.M.; Souza, M.M.; Gomes, Y.S.; Fernandes, D.L., E-mail: junior.luiz09@hotmail.com [Universidade Federal do Rio Grande do Norte (DIAREN/UFRN), Natal, RN (Brazil). Laboratorio de Processamento Mineral e Residuo

    2016-07-01

    The sandstone is a sedimentary rock formed mainly by quartz grains. In Rio Grande do Norte, there is the Potiguar Basin with the Jandaira and Acu Formations. The latter consists of thick layers of whitish-colored sandstones. It stands out as a water storage facility in the state, but it is also used for building aggregates. This article aimed at the use of the sandstone of this formation in the ceramic mass for coating. Initially, the material was sampled. It went through the comminution process to achieve the required granulometry. After this, three formulations were made to incorporate this new material into the traditional ones. The methods were performed according to ISO 13816. After sintering at 1200 °C, the specimens were subjected to the physical tests. A positive result was obtained for the use of the Acu sandstone in low concentrations. It is clear, therefore, its use in ceramics for coating.

  17. Portfolio: Ceramics.

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  18. Utilization of marble from Bejui mine - Currais Novos/RN in ceramic mass; Analise da incorporacao de marmore da mina Brejui - Currais Novos/RN na massa ceramica

    Farias, D.S.U. de; Souza, M.M. de; Almeida, A.B.D. de; Lima, T.C. de; Nobrega, L.F.P. de M. [Instituto Federal de Ciencia e Tecnologia do Rio Grande do Norte (IFRN), Natal, RN (Brazil); Mendes, L.B., E-mail: debora_suf_00@hotmail.com [Fundacao de Apoio a Pesquisa do Rio Grande do Norte (FAPERN), Natal RN (Brazil)

    2016-07-01

    Mining in Mine Brejui, in Currais Novos - RN, is related to the extraction of scheelite, however the marble of the region is not fully tapped. Aiming to provide a utility to this carbonate rock very abundant in the Serido region, this work is to evaluate, from its chemical and other tests, the addition of marble in the ceramic mass. For the analysis, the samples were collected, then comminuted and sieved to #200 and, right after, characterized by fluorescence X-ray method (FRX). The results indicate a high concentration of CaO (95%), a flux element, and very low content of Fe{sub 2}O{sub 3} and SO{sub 3} (less than 0.6%). After produced the samples, there were performed the water absorption tests and linear shrinkage, which has indicate satisfactory results and classifying them as porcelain. Therefore, with the significant potential of the marble, other laboratory tests may be performed to analyze its incorporation in the formulation of ceramic bodies, being economically viable and adding proper use and commercial value to the rock. (author)

  19. An assessment of ninth round; Nona: uma avaliacao da rodada

    Assumpcao, Eduardo; Andrade, Leila; Fontana, Raphaela [Agencia Nacional do Petroleo, Gas Natural e Biocombustiveis (ANP), Rio de Janeiro, RJ (Brazil)

    2008-07-01

    Accomplished on November, 27{sup th}, 2007, 271 exploratory blocks were offered in Round 9, distributed within 14 sectors, totalling an area of 73 thousand km{sup 2}. The following basins were included: Campos, Espirito Santo, Para- Maranhao, Parnaiba, Pernambuco-Paraiba, Potiguar, Santos, Reconcavo and Rio do Peixe. From the original lot of 67 companies qualified (31 Brazilian and 36 of foreign origin), 42 offered bids individually or in partnerships. 117 blocks were allocated to 24 winning operator companies. Other 12 enterprises won acreage as non-operator participants of joint bids. A record of R$ 2,1 billion were offered as signature bonuses along with 169.436 units of the so called minimum exploratory programs. These units may be converted to an estimated R$ 1,4 billion. The objective of this paper is to evaluate the results obtained in Round 9, analyzing collected data through three different perspectives of aggregate results: bidding companies, offered areas and exploratory models. (author)

  20. Advanced Ceramics

    1989-01-01

    The First Florida-Brazil Seminar on Materials and the Second State Meeting about new materials in Rio de Janeiro State show the specific technical contribution in advanced ceramic sector. The others main topics discussed for the development of the country are the advanced ceramic programs the market, the national technic-scientific capacitation, the advanced ceramic patents, etc. (C.G.C.) [pt

  1. Comparison of the microstructure and composition of aboriginal ceramics, from indigenous site Caninhas, with the obtained ones in the region; Comparacao da microestrutura e da composicao de ceramicas indigenas provenientes do sitio arqueologico Caninhas, com as obtidas atualmente na regiao

    Matos, C.C.; Nakano, F.P.; Taguchi, S.P.; Camargo-Vernilli, D., E-mail: cristhian@alunos.eel.usp.b [Universidade de Sao Paulo (DEMAR/EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de Lorena. Dept. de Engenharia de Materiais; Ribeiro, R.B.; Rosa, S.J. L. [Faculdades Integradas Teresa D' Avila (FATEA), Lorena, SP (Brazil). Rede Salesianas. Dept. de Desenho Industrial

    2009-07-01

    The archaeological site of Caninhas is made of funeral and combustion structures and various objects of aboriginal daily use. These parts and fragments were safe and inventoried, constituting approximately 4000 units. The objective of this project was to analyze the microstructure and composition of archaeological ceramics, and ceramics made of argil current of the zone. The crystalline phases were identified by X-Rays Diffraction (XRD), elementary composition was obtained by X-Rays Fluorescence (XRF) and Energy Dispersive Spectrometry (EDS), and the microstructure was evaluated by Scanning Electron Microscope (SEM). Composition and microstructure of archaeological ceramics are different of current ceramics, indicating the effect of lixiviation in function of the time and the microstructural evolution due different ceramic processing. These results are valuable for the archaeological area studies, mainly for the cultural denoting which represents. The relation between some studies is basic to add knowledge: use of the ceramic materials engineering for archaeology application. (author)

  2. Ceramic joining

    Loehman, R.E. [Sandia National Lab., Albuquerque, NM (United States)

    1996-04-01

    This paper describes the relation between reactions at ceramic-metal interfaces and the development of strong interfacial bonds in ceramic joining. Studies on a number of systems are described, including silicon nitrides, aluminium nitrides, mullite, and aluminium oxides. Joints can be weakened by stresses such as thermal expansion mismatch. Ceramic joining is used in a variety of applications such as solid oxide fuel cells.

  3. Sensitive Ceramics

    2014-01-01

    Sensitive Ceramics is showing an interactive digital design tool for designing wall like composition with 3d ceramics. The experiment is working on two levels. One which has to do with designing compositions and patterns in a virtual 3d universe based on a digital dynamic system that responds on ...... with realizing the modules in ceramics by 3d printing directly in porcelain with a RapMan printer that coils up the 3d shape in layers. Finally the ceramic modules are mounted in a laser cut board that reflects the captured composition of the movement of the hands....

  4. [Ceramic posts].

    Mainjot, Amélie; Legros, Caroline; Vanheusden, Alain

    2006-01-01

    As a result of ceramics and all-ceram technologies development esthetic inlay core and abutments flooded the market. Their tooth-colored appearance enhances restoration biomimetism principally on the marginal gingiva area. This article reviews indications and types of cores designed for natural teeth and implants.

  5. Incorporation of sludge of the sewage treatment station (STS) into red ceramic; Incorporacao de lodo da estacao de tratamento de esgoto (ETE) em ceramica vermelha

    Areias, I.O.R.; Vieira, C.M.F.; Manhaes, R. da S.T.; Intorne, A.C., E-mail: oraisabela@gmail.com, E-mail: vieira@uenf.br, E-mail: rosane.toledo@gmail.com, E-mail: aline_intorne@yahoo.com.br [Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Campos dos Goytacazes, RJ (Brazil)

    2017-07-15

    This study aimed to evaluate the waste incorporation of sewage treatment station (STS) on the production of red ceramic. The used raw materials were clayey ceramic body and STS waste from Campos dos Goytacazes - RJ. The raw materials were characterized through techniques of X-ray fluorescence and X-ray diffraction; moreover, the specific surface area was determined by means of the BET and blue methylene techniques. The thermal behavior of STS waste was evaluated by thermal gravimetric analysis. Formulations were prepared with 0, 2.5, 10 and 15 wt% STS waste in the clayey ceramic. Specimens were prepared by uniaxial pressing at 20 MPa with 8% moisture content and calcination at 950 °C. The evaluated physical and mechanical properties of the calcined ceramics were water absorption and compression strength. The microstructure of calcined pieces was investigated by scanning electron microscopy. The results showed that this type of waste must be incorporated in low amounts (up to 2.5 wt%) to avoid deleterious effects on the ceramic physical and mechanical properties. (author)

  6. Study of the gem residue (sludge) addition in bulk red ceramics; Estudo da adicao de residuo (lodo) de gemas na massa ceramica vermelha

    Bruxel, F. R.; Oliveira, E. C.; Stulp, S.; Muller, C. S.; Etchepare, H.D., E-mail: eniz@univates.br [Univates - Centro Universitario, Lajeado, RS (Brazil)

    2012-04-15

    This work aims to incorporate gems waste (sludge saw cutting of gems), produced in an amethyst and agate firm cut, in the red ceramic body used for the production of solid bricks. The raw materials were tested by X-ray fluorescence, X-ray diffraction and granulometric distribution analysis, for characterize the mineralogy and physical chemistry of materials. Samples were prepared with 0%, 5%, 9%, 13% and 17% waste added to the ceramic body by mass. The physical properties studied were compressive strength, linear shrinkage, water absorption and density in accordance with current technical standard. The results showed that it is possible to incorporate up to 5% of waste in bulk ceramics. (author)

  7. Analysis of thermal stability of ceramic engobes developed with marble reject; Analise da estabilidade termica de engobes ceramicos desenvolvidos com rejeito de marmore

    Carlos, E.M.; Assis, R.B.; Sousa, R.F.; Galvao, A.C.P.; Mendes, J.U.L., E-mail: elionemoura@hotmail.com [Universidade Federal do Rio Grande do Norte (UFRN), RN (Brazil)

    2014-07-01

    Considering the technological growth and technical production in the ceramic industry, ceramic mass formulations were evaluated with addition of marble residue to substitute the quartz for obtaining of engobes. Five formulations were prepared varying the proportions of raw material, sieved at 200 mesh, ball mill homogenised, characterized by fluorescence (FRX) and X-ray diffraction (XRD). Samples were separated from the formulations for thermal analysis (TG / DSC) and dilatometry. The specimens were prepared in uniaxial press (25 Mpa). The FIII and FIV formulations presented satisfactory results, evidencing the potential of replacing quartz by the marble residue in ceramic formulation for engobes, minimizing the environmental impact by the undue discard of waste, reducing costs and increasing the range of raw materials for the coatings industry.

  8. Using of sawing quartzite fine residual for obtaining ceramic coating; Utilizacao do residuo fino da serragem de quartzito para obtencao de revestimento ceramico

    Nobrega, L.F.P.M.; Souza, M.M., E-mail: junior.luiz09@hotmail.com [Universidade Federal do Rio Grande do Norte (DIAREN/UFRN), Natal, RN (Brazil). Laboratorio de Processamento Mineral e Residuo

    2016-07-01

    Quartzite is a metamorphic rock that is consisting mainly of quartz. In Paraiba there is a mining activity of this rock, in the region of Varzea and Junco do Serido especially where many wastes are created, including the sawing residue. The objective is to use the waste cited as the ceramic component coating mass, thereby replacing the quartz. Initially, the raw materials samples were taken and the chemical analysis was done of them. This passed the comminution process to achieve the required minimum particle size. After this, a formulation which added the residue in ceramic mass was made. The specimens were subjected to sintering and it was later made physical tests according to NBR 13818. The results show that the residue can replace the quartz ceramic mass successfully, but not as good as the original raw material. (author)

  9. Influence of sintering temperature in red ceramic with addition of mill scale; Influencia da temperatura de sinterizacao em ceramica vermelha com adicao de carepa/residuo de laminacao

    Arnt, A.B.C.; Rocha, M.R.; Bernardin, A.M.; Meller, J.G., E-mail: anb@unesc.ne [Universidade do Extremo Sul Catarinense (UNESC), Criciuma, SC (Brazil). Engenharia de Materiais. Lab. de Fenomenos de Superficies e Tratamentos Termicos

    2010-07-01

    This study aimed to evaluate the influence of sintering temperature in a red ceramic body with the addition of mill scale. This residue consists of oxides of iron had to replace the function of pigments used in ceramic materials. After chemical characterization, by X-ray diffraction, X-ray fluorescence and scanning electron microscopy, this residue was added at a rate of 5% in commercial ceramic past. The formulations were subjected to different burn temperatures of around 950 deg C, 1000 deg C and 1200 deg C. The formulations were evaluated for physical loss to fire, linear firing shrinkage, water absorption and flexural strength by 3 and intensity of tone. The results indicate that the different firing temperatures influence the strength and stability of tone in the formulations tested. (author)

  10. Recycling of the reduction sludge of manganese in the production of ceramics; Reciclagem da lama de reducao de manganes na producao de ceramicas vermelhas

    Castro, C.G.; Araujo, F.G.S., E-mail: camilac46@gmail.com [Universidade Federal de Ouro Preto (REDEMAT/UFOP), MG (Brazil); Kruger, F.L. [Fundacao Gorceix (DEPEC), Ouro Preto, MG (Brazil). Departamento de Pesquisa e de Educacao Continuada; Jannotti Junior, N. [Vale Manganes, Ouro Preto, MG (Brazil)

    2011-07-01

    To study the use of manganese reduction residues, from the electric arc furnaces for the production of manganese ferro-alloys, as raw materials for construction bricks, different ceramic compositions were formulated with contents of 0, 2.5, 5 and 10wt% of waste addition to the clay used commercially, and sintered at different temperatures, 850, 950 and 1050°C. After firing, the ceramic samples were studied by optical microscopy, scanning electron microscopy (SEM), x-ray diffraction and by spectrophotometry. Their mechanical properties were evaluated by flexural strength, apparent porosity and specific mass, water absorption, linear shrinkage and loss on ignition. With the help of technics and experiment planning programs, the effects of the variables: temperature, composition and interaction between them over the results were discussed. This work proved that the addition of manganese reduction sludge to the clay, for the production of ceramic construction bricks, is highly feasible, from a technical standpoint. (author)

  11. Incorporation of ladle furnace slag in ceramic formulations: study of extrusion zones; Incorporacao da escoria do forno panela em formulacao ceramica: estudo das zonas de extrusao

    Feitosa, E.F.; Santana, C.M.; Luna, D.S.; Santos, D.M.S.; Silva, G.S.; Noleto, L.T.; Almeida, N.C.; Rabelo, A.A.; Fagury Neto, E., E-mail: edna.fernandes48@gmail.com, E-mail: fagury@unifesspa.edu.br [Universidade Federal do Sul e Sudeste do Para (UNIFESSPA), Maraba, PA (Brazil). Instituto de Geociencias e Engenharias

    2016-07-01

    This study aimed to investigate the effect of incorporation of ladle furnace slag (LFS) in two clays with higher and lower plasticity, used for the manufacture of structural ceramics. The LFS from a local steel making plant was added to ceramic compositions in proportions of 8 %, 14 % and 16 %. The formulations were tested in appropriate equipment that measures the liquid limit and plastic limit. The property examined was the plasticity index, in order to make a study of the extrusion zones. Results showed that the addition of slag into clay mixtures alters the plasticity; however, the extrusion process was not hampered. (author)

  12. Estudo da potencialidade da aplicação de uma argila contaminada com calcário na produção de placas cerâmicas Study of the potentiality of the application of a contaminated clay with limestone in the production of ceramic plates

    R. A. L. Soares

    2012-12-01

    Full Text Available Na região da cidade de Teresina, PI, encontra-se uma grande quantidade de jazidas de argilas de queima vermelha usadas na produção de cerâmica estrutural, sendo o principal motivo da instalação de um pólo cerâmico nesta região. Porém muitas destas jazidas não estão sendo exploradas de forma adequada ou simplesmente abandonadas por causa da contaminação com calcário, sendo este o principal contaminante indesejável pelos ceramistas do pólo teresinense. Assim, esta pesquisa tem como objetivo avaliar a potencialidade de aplicação de uma argila com calcário na produção de placas de revestimento cerâmico de queima vermelha. Para isso foram caracterizadas uma massa cerâmica usada na produção de revestimento semiporoso e uma argila contaminada com calcário. As matérias-primas foram queimadas em forno industrial separadamente e em combinação nas proporções de 25%, 50% e 75% em peso da argila adicionada a massa industrial. Foram realizados nos corpos de prova queimados ensaios tecnológicos de retração linear, absorção de água e resistência mecânica. A microestrutura foi avaliada através de análise por difração de raios X. Os resultados mostraram potencialidade da utilização da argila contaminada com calcário em massa de revestimento cerâmico.In the city of Teresina area, capital of Piauí, Brazil, there is a lot of clay deposits red burning used in the production of structural ceramics, being the main reason for installing a ceramic center in the region. But many of these deposits are not being adequately exploited or simply abandoned because of contamination with limestone, which is the main undesirable contaminant for the ceramic producers pole of Teresina. Thus, this research aims to evaluate the capability of applying some clay with limestone in the production of these plates of red ceramic burning. A ceramic body used in the production of coating semiporous and a contaminated clay with limestone were

  13. Oxide ceramics

    Ryshkewitch, E.; Richerson, D.W.

    1985-01-01

    The book explores single-phase ceramic oxide systems from the standpoint of physical chemistry and technology. This second edition also focuses on advances in technology since publication of the original edition. These include improvements in raw materials and forming and sintering techniques, and the major role that oxide ceramics have had in development of advanced products and processes. The text is divided into five major sections: general fundamentals of oxide ceramics, advances in aluminum oxide technology, advances in zirconia technology, and advances in beryllium oxide technology

  14. Characterization, analysis and dating of archaeological ceramics from the Amazon basin through nuclear techniques; Caracterizacao, analise e datacao de ceramicas arqueologicas da Bacia Amazonica atraves de tecnicas nucleares

    Latini, Rose Mary

    1998-07-01

    The aim of this work is to contribute to the research in the reconstruction of part of the pre-history of the Amazon Basin by means of an analytical methods combined with multivariate analysis, given a analytic basis that can be continued by the archaeological work, through the identification, classification, provenance and dating the ceramics found in different archaeological sites of the Hydro graphic Basin of the Purus river. Neutron activation analysis in conjunction multivariate statistical methods were used for the identification and classification and thermoluminescence was used for the dating. Chemical composition results were in better agreement with archaeological classification for the archaeologically define Iquiri, Quinan and Xapuri phases and less characteristics the Iaco and Jacuru archaeological phase were not well characterized. An homogeneous group was established by most of the samples collected from the Los Angeles Archaeological Site (LA) and was distinct from all the other groups analysed. The provenance studies made with ceramics collected at this site shows that they were made with clay from nearby river (Rio Ina). From the LA ceramics dating the average date of site occupation was 1660 years. The ceramic dating results from the external wall of a circular earth wall construction confirm the relation with the local pre-history. Beyond the Acre material two urns were dated from the Archaeological Site Morro Grande and Sao Jose at Araruama, Rio de Janeiro. (author)

  15. Influência da distribuição granulométrica na estabilidade dimensional de placas cerâmicas de base vermelha Influence of particle size distribution on the dimensional stability of red ceramic tiles

    A. C. A. Prado

    2008-12-01

    Full Text Available As propriedades do revestimento cerâmico queimado estão intrinsecamente ligadas às características da massa, dentre estas se encontram o tamanho, a distribuição, o formato e o arranjo das partículas. O efeito da distribuição granulométrica de partículas sobre a estabilidade dimensional de placas cerâmicas para revestimentos de base vermelha foi estudado em três massas, todas continham no mínimo 57% de material advindo da Formação Corumbataí. Foram estudadas duas distribuições granulométricas - uma parecida com aquelas usadas no Pólo Cerâmico de Santa Gertrudes e, outra, com uma massa de grés. De uma maneira geral, granulações mais grossas, semelhantes à massa de Santa Gertrudes, variaram menos dimensionalmente quando as placas apresentaram médias e altas porosidades (absorção de água entre 3,0 e 10,0%. Já, granulações mais finas, similares a massas de grés, foram necessárias para a produção de placas de baixa absorção (menor que 3,0%.The properties of final ceramic tiles are related with the mass characteristics, among them the size, shape, distribution and arrange of particles. The effect of particle size distribution on dimensional stability of red ceramic tiles was studied in three masses; all of them composed with, at minimum, 57% of Corumbataí Formation's materials. Two particle size distributions were investigated: the first was similar to the masses that are used in the Santa Gertrudes Ceramic Pole's factories and the other was similar to the stoneware mass. In general, masses with larger particle sizes, similar to that of Santa Gertrudes, had greater dimensional stability in the products with 3 to 10% of water absorption. On the other hand, in the manufacture of low porosity tiles (water absorption capacity < 3% it is recommended the use of smaller grain size.

  16. Study of the microstructure and the hardness of PZT piezoelectric ceramics types I and III used in electro acoustic transducers; Estudo da microestrutura e da microdureza das ceramicas piezoeletricas tipos PZT I e III utilizadas em transdutores eletroacusticos

    Cabral, Ricardo de Freitas; Itaboray, Lucas Mendes; Santos, Anna Paula de Oliveira [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil)

    2015-12-15

    The field of electronic processing of the ceramic piezoelectric type imported powdered led to the production of ceramics with 97% of theoretical density, homogeneous microstructure with great potential for applications in piezoelectric devices such as electro acoustic transducers. However, the production of electronic ceramics National piezoelectric type is not yet able to have as raw material zirconate titanate Lead (PZT) 100% made in Brazil. Thus, this is used for supply of domestic production, the zirconium oxide. In this work, both post PZT types I and III, imported, were uniaxially pressed at 70 MPa and sintered at 1200 and 1250 deg C for 3 hours. Hardness measurements were performed by micro indentation, X-ray diffraction analysis and Scanning Electron Microscopy. The hardness of PZT I was 393 HV. (author)

  17. Evaluation of the shear bond strength of the union between two CoCr-alloys and a dental ceramic Avaliação da resistência ao cisalhamento da união entre duas ligas a base de CoCr e uma cerâmica

    Mariana Pretti

    2004-12-01

    Full Text Available INTRODUCTION: Based on the importance of the integrity of the metal/ceramic interface, the purpose of this work was to evaluate the shear bond strength of the metal-ceramic union of two Co-Cr alloys (Wirobond C, Bego; Remanium 2000, Dentaurum combined with Omega 900 ceramic (Vita Zahnfabrik. MATERIAL AND METHOD: Eleven cylindrical matrixes were made for each alloy, and the metallic portion was obtained with the lost wax casting technique with standardized waxing of 4mm of height and of 4mm of diameter. The ceramic was applied according to the manufacturer's recommendations with the aid of a teflon matrix that allowed its dimension to be standardized in the same size as the metallic portion. The specimens were submitted to the shear bond test in an universal testing machine (EMIC, with the aid of a device developed for such intention, and constant speed of 0.5mm/min. RESULTS AND CONCLUSIONS: The mean resistance was 48.387MPa for Wirobond C alloy, with standard deviation of 17.718, and 55.956MPa for Remanium 2000, with standard deviation of 17.198. No statistically significant difference was observed between the shear strength of the two metal-ceramic alloys.INTRODUÇÃO: Baseados na importância da integridade da interface metal-cerâmica, este trabalho tem como objetivo avaliar a resistência ao cisalhamento da união metal-cerâmica de duas ligas de Co-Cr (Wirobond C, Bego; Remanium 2000, Dentaurum combinadas com a cerâmica Omega 900 (Vita Zahnfabrik. MATERIAIS E MÉTODOS: Foram confeccionados 11 corpos-de-prova cilíndricos para cada liga utilizada, sendo que a porção metálica foi obtida por fundição pela técnica da cera perdida, através de enceramentos padronizados com 4mm de altura por 4mm de diâmetro. A aplicação da cerâmica foi realizada segundo recomendações do fabricante, com auxílio de uma matriz de teflon que permitia sua padronização com as mesmas dimensões da porção metálica. Os corpos-de-prova foram submetidos

  18. Effect of porcelain polishing addition of waste in properties blocks ceramic; Efeito da adicao do residuo de polimento de porcelanato nas propriedades de blocos ceramicos

    Santana, G.L.; Barbosa Neto, M.C.; Campos, L.F.; Macedo, D.A; Dutra, R.P.S., E-mail: geovanalira1@gmail.com [Universidade Federal da Paraiba (UFPB), PB (Brazil)

    2016-07-01

    This work has as objective the study of the technological properties of ceramic blocks with addition of residue porcelain polishing. The test samples are produced with clay base, where the waste is introduced in concentrations of 10% and 20% by mass, to evaluate its influence on the properties of the ceramic block. All these materials were characterized by determining their chemical composition (XRF) and X-ray diffraction Sintering was performed at temperatures of 850 ° C, 950 ° C and 1100 ° C with a heating rate of 2 ° C / me and 60 minutes of landing. After this, there was obtained the technological properties of the samples such as: Loss on fire, the burning linear shrinkage, water absorption, porosity and density, as well as, mechanical strength properties through the flexural strength test. The results show that the addition of waste influenced both the technological properties, the mechanical properties evaluated in this study. (author)

  19. Ceramic filters analysis for aluminium melting through microtomography technique; Analise de filtros ceramicos para fundicao de aluminio atraves da tecnica de microtomografia

    Rocha, Henrique de Souza; Lopes, Ricardo Tadeu; Jesus, Edgar Francisco Oliveira de; Oliveira, Luis Fernando de [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Lab. de Instrumentacao Nuclear; Duhm, Rainer; Feiste, Karsten L.; Reichert, Christian; Reimche, Wilfried; Stegemann, Dieter [Universidade de Hannover (Germany). IKPH

    2000-07-01

    In this work a ceramic filters analysis is done through the microtomography for improvement of the aluminium melting process through the filter porosity control. Microtomography were obtained of ceramic filters with pore dimensions of 10, 20 and 30 ppi. The data were calculated by using an reconstruction algorithm for divergent beam implemented in the Nuclear Instrumentation Laboratory of COPPE/UFRJ and analysed through cells and windows separation according to the defined by Ray. For the analyses the Image Pro program were used where the cells have been detached by sphere inserted, adjusting by nine points, in the filter cavities. So, the size of the answer sphere were considered as the cell size. The windows were measured by straight lines secant to the window intersections.

  20. Variação da cor e propriedades cerâmicas com o aumento da temperatura de queima de uma argila proveniente da formação Corumbataí, região de Piracicaba, SP Variation of color and ceramic properties with the increase of temperature of clay's firing from the Corumbataí formation, region of Piracicaba, SP

    C. D. Roveri

    2007-12-01

    Full Text Available Objetivando compreender a influência do ferro contido na illita, presente na formação Corumbataí, na cor de queima de produtos cerâmicos selecionou-se uma amostra de cor cinza esverdeado claro, dominantemente illítica e com porcentagem de óxidos e hidróxidos de ferro relativamente baixo, com base em estudos petrográficos, mineralógicos e químicos. Para os testes cerâmicos, os corpos de prova foram queimados em forno de queima rápida de laboratório nas temperaturas de 900 ºC, 950 ºC, 1000 ºC, 1050 ºC, 1075 ºC e 1100 ºC, com taxa de aquecimento de 40 ºC/min, sendo um conjunto de corpos de prova queimado a 950 ºC, porém com taxa de aquecimento de 20 ºC/min, com o intuito de verificar a influência do tempo de queima na coloração das peças cerâmicas. O tempo de queima mostrou não interferir significativamente na alteração da cor e os corpos de prova apenas apresentaram alterações significativas a partir da temperatura de 1000 ºC, adquirindo, respectivamente os matizes: laranja, vermelho e marrom escuro. A mudança de cor foi acompanhada em intensidade equivalente pela retração linear de queima, pela absorção de água e módulo de ruptura por flexão.The objective of this paper is to understand the influence of the iron contained in the illite, present in the Corumbataí formation, in the color of firing of ceramic products. A sample was selected, with a gray color clearly, with illite domination, hydroxide and oxide percentage and relatively low iron, with basis of petrographics, mineralogical and chemical studies. For the ceramic essays, the test bodies were fired in a fast firing kiln of laboratory in the temperatures of 900 ºC, 950 ºC, 1000 ºC, 1050 ºC, 1075 ºC and 1100 ºC, with heating rate of 40 ºC/min, a set of bodies test was fired at 950 ºC, however with heating rate of 20 ºC/min, for the checking of the influence of the time of firing range in the coloration of the ceramic plates. The time of

  1. Study of potentiality of raw material of Crato/CE for use in structural ceramics - part I - technological characterization; Estudo da potencialidade da materia-prima do Crato/CE para utilizacao em ceramica estrutural - parte I - caracterizacao tecnologica

    Andrade, J.C.S.; Santos, G.M.; Saldanha, K.M.; Sales Junior, J.C.C.; Nascimento, R.M.; Paskocimas, C.A., E-mail: jean@ufrnet.br [Universidade Federal do Rio Grande do Norte (UFRN), Natal RN (Brazil)

    2011-07-01

    The limitation of information on chemical, mineralogical and thermal characteristics of raw material used in process of manufacture of ceramic products in the region of Cariri, specifically the city of Crato, state of Ceara, motivated the development of this work, since this region ceramics exist that in a general context they appear as important productive chains in the state. The characteristics were evaluated by tests of limit of liquidity, limit of plasticity, index of plasticity, but also by chemical analysis for fluorescence of rays X, analysis of phases for diffraction of rays X, and thermal analysis (thermogratimetric analysis). The results showed that the raw material has excellent size distribution and characteristics acceptable to the processing of structural components of dark color the red, requiring a mixture of clay with coarse less plastic which granulation, that functions as reducer of plasticity. (author)

  2. Aspectos da Reologia e da Estabilidade de Suspensões Cerâmicas. Parte III: Mecanismo de Estabilização Eletroestérica de Suspensões com Alumina Aspects of Rheology and Stability of Ceramic Suspensions. Part III: Electrosteric Stabilization Mechanism of Alumina Suspensions

    F. S. Ortega

    1997-08-01

    Full Text Available Esta terceira e última parte da revisão sobre os aspectos reológicos e de estabilização de suspensões com pós cerâmicos vem reunir a aplicação dos conhecimentos adquiridos nas primeiras duas partes publicadas anteriormente. Aqui, os fenômenos eletrostático devido à dupla camada elétrica, e estérico, relacionado à adsorção de moléculas poliméricas, são combinados para explicar o mecanismo eletroestérico de estabilização de suspensões cerâmicas. Os defloculantes que atuam através desse mecanismo abrangem uma classe específica de polímero denominada polieletrólitos, a qual é constituída por macromoléculas ionizáveis quando em solução. O estudo da forma com que os polieletrólitos atuam justifica-se devido à larga utilização desta classe de polímeros na indústria cerâmica. Os ácidos poliacrílico (PAA e polimetacrílico (PMAA são exemplos de polieletrólitos amplamente utilizados no processo de materiais à base de alumina. Dá-se destaque à influência do pH do meio e da presença de íons, sendo novamente aqui importante o conceito de força iônica da suspensão. Como aplicação prática, apresenta-se a estabilidade do sistema alumina-PMAA, reportando-se sobre o comportamento da viscosidade e da efetiva defloculação da suspensão. Este estudo é concluído apresentando resultados do efeito do peso molecular sobre a viscosidade, chamando atenção para o fato de que não basta definir apenas a classe de polímero a ser usada, sendo também fundamental especificar o peso molecular médio do polímero selecionado.The third and last part of this review about stabilization and rheological aspects of ceramic suspension gathers the knowledge in the two parts previously published. Here, the electrostatic and steric phenomena, related to the electrical double layer and polymeric molecules adsorption, respectively, are combined to explain the electrosteric stabilization mechanism of ceramic suspensions. The

  3. Ceramic Seal.

    Smartt, Heidi A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Romero, Juan A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Custer, Joyce Olsen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hymel, Ross W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Krementz, Dan [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Gobin, Derek [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Harpring, Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Martinez-Rodriguez, Michael [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Varble, Don [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); DiMaio, Jeff [Tetramer Technologies, Pendleton, SC (United States); Hudson, Stephen [Tetramer Technologies, Pendleton, SC (United States)

    2016-11-01

    Containment/Surveillance (C/S) measures are critical to any verification regime in order to maintain Continuity of Knowledge (CoK). The Ceramic Seal project is research into the next generation technologies to advance C/S, in particular improving security and efficiency. The Ceramic Seal is a small form factor loop seal with improved tamper-indication including a frangible seal body, tamper planes, external coatings, and electronic monitoring of the seal body integrity. It improves efficiency through a self-securing wire and in-situ verification with a handheld reader. Sandia National Laboratories (SNL) and Savannah River National Laboratory (SRNL), under sponsorship from the U.S. National Nuclear Security Administration (NNSA) Office of Defense Nuclear Nonproliferation Research and Development (DNN R&D), have previously designed and have now fabricated and tested Ceramic Seals. Tests have occurred at both SNL and SRNL, with different types of tests occurring at each facility. This interim report will describe the Ceramic Seal prototype, the design and development of a handheld standalone reader and an interface to a data acquisition system, fabrication of the seals, and results of initial testing.

  4. Ceramic Seal

    Smartt, Heidi A.; Romero, Juan A.; Custer, Joyce Olsen; Hymel, Ross W.; Krementz, Dan; Gobin, Derek; Harpring, Larry; Martinez-Rodriguez, Michael; Varble, Don; DiMaio, Jeff; Hudson, Stephen

    2016-01-01

    Containment/Surveillance (C/S) measures are critical to any verification regime in order to maintain Continuity of Knowledge (CoK). The Ceramic Seal project is research into the next generation technologies to advance C/S, in particular improving security and efficiency. The Ceramic Seal is a small form factor loop seal with improved tamper-indication including a frangible seal body, tamper planes, external coatings, and electronic monitoring of the seal body integrity. It improves efficiency through a self-securing wire and in-situ verification with a handheld reader. Sandia National Laboratories (SNL) and Savannah River National Laboratory (SRNL), under sponsorship from the U.S. National Nuclear Security Administration (NNSA) Office of Defense Nuclear Nonproliferation Research and Development (DNN R&D), have previously designed and have now fabricated and tested Ceramic Seals. Tests have occurred at both SNL and SRNL, with different types of tests occurring at each facility. This interim report will describe the Ceramic Seal prototype, the design and development of a handheld standalone reader and an interface to a data acquisition system, fabrication of the seals, and results of initial testing.

  5. Glazed ceramic roof tiles: influence of surface features in the solar reflectance index; Influencia das caracteristicas da superficie no indice de refletancia solar de telhas ceramicas esmaltadas

    Bortoli, Leitcia Silva de; Stapait, Camila Cristina; Marinoski, Deivis Luis; Fredel, Marcio Celso; Schabbach, Luciana M., E-mail: luciana.maccarini@ufsc.br [Universidade Federal de Santa Catarina (UFSC), Blumenau, SC (Brazil)

    2016-07-01

    In this study the influence of surface features of ceramic roof tiles in the solar reflectance index were evaluated. Two glazed ceramic roof tiles (type stoneware) with the same color (ivory) but with different appearance (matte and brilliant) were the focus of the analysis. The Solar Reflectance Index (SRI) of the roofs tiles were determined by the solar reflectance values (UV-VIS-NIR) and emittance, measured in laboratory. The samples showed SRI> 39 in accordance with LEED certification criteria (Leadership in Energy and Environmental Design), contributing to minimizing the Heat Island Effects. Although the matte roof tile shows a slightly higher SRI value (82) than the brilliant one (78), the results for the variables that composes the SRI value (reflectance and emittance) were very similar. Analysis of XRD, SEM and EDS performed on the surfaces of the two roofs indicated for the matte glaze the presence of microcrystals (with barium and zinc) that can contribute to the slightly highest value of SRI. The roughness (optical interferometer white light) and the brightness (brightness meter) of the samples were also measured. (author)

  6. Evaluation of shear bond strength of different treatments of ceramic bracket surfaces Avaliação da resistência ao cisalhamento de diferentes tratamentos na superfície de braquetes cerâmicos

    Patrícia Helou Ramos Andrade

    2012-08-01

    Full Text Available OBJECTIVE: To evaluate the bonding strength of the ceramic bracket and composite resin restoration interface, using four types of treatment on the base of the bracket. METHODOLOGY: 48 photoactivated composite resin discs were used (FiltekTM Z250 contained in specimens and divided into 4 groups of 12 specimens for each group according to the type of treatment performed on the base of the brackets. Once the brackets were bonded, the specimens were subjected to shear stress carried out in a universal testing machine (MTS: 810 Material Test System calibrated with a fixed speed of 0.5 mm / minute. The values obtained were recorded and compared by means of appropriate statistical tests - analysis of variance and then Tukey's test. RESULTS AND CONCLUSIONS: The surfaces of ceramic brackets conditioned with 10% hydrofluoric acid for 1 minute, followed by aluminum oxide blasting, 50µ, after silane application and primer application, was considered the best method to prepare surfaces of ceramic brackets prior to orthodontic esthetic bonding.OBJETIVO: avaliar a resistência à união da interface entre braquete cerâmico e restauração de resina composta, empregando quatro tipos de tratamento na base do braquete. MÉTODOS: foram utilizados 48 discos de resina fotoativada (Filtek® Z250 incluídos em corpos de prova, divididos em quatro grupos, com 12 espécimes em cada grupo, de acordo com o tipo de tratamento realizado na base do braquete. Uma vez colados os braquetes, os corpos de prova foram submetidos à tensão de cisalhamento, realizado numa máquina universal de ensaios (MTS: 810 Material Test System calibrada com velocidade fixa de 0,5mm/min. Os valores obtidos foram registrados e comparados por meio de médias, utilizando-se testes estatísticos adequados (análise de Variância e, posteriormente, teste de Tukey. RESULTADOS E CONCLUSÕES: o condicionamento das superfícies dos braquetes cerâmicos com ácido hidrofluorídrico a 10% por 1 minuto

  7. Influence of morphology of ceramic fibers in catalytic combustion of methane; Influencia da morfologia de fibras ceramicas na combustao catalitica do metano

    Tabarelli, A.C.; Alves, A.K.; Bergmann, C.P., E-mail: andretabarelli@gmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Departamento de Materiais

    2012-07-01

    Methane, considered as the main constituent of natural gas has been widely used as an energy source. During its combustion are produced pollutants that cause concern and necessity to eliminate or reduce the emission of these agents in the atmosphere. One of the main means of controlling emissions is the use of catalysts. In order to contribute to the development of new catalysts, this study analyzed the morphology of ceramic fibers of cerium oxide (ceria) doped with copper fabricated by electrospinning, in order to verify their effects on catalytic activity. Parameters were varied in distance from the electrodes, the diameter of the capillary and applied voltage between electrodes. The characterizations were performed: scanning electron microscopy, thermogravimetric analysis, BET and Xray diffraction (DXR). The results indicate that after the thermal treatment there was a reduction of approximately 40% fiber diameter and specific surface area ranging between 28.929 and 34.501 m{sup 2}/g. (author)

  8. Effect of the Sr and Fe incorporation on the Pzt electric and ceramic properties; Efeito da incorporacao de Sr e Fe nas propriedades ceramicas e eletricas de PZT

    Santos, Marcia C. Cavaco dos [Instituto de Pesquisas da Marinha, Rio de Janeiro, RJ (Brazil); Villegas, Marina; Moure, Carlos [Instituto de Ceramica e Vidro, Madrid (Spain)

    1997-12-31

    The Piezoelectric Pzt properties with compositions near of morphotropic boundary phase can be usefully modified by adding small quantities of various oxides, such as, Fe{sub 2} O{sub 3} and Sr O, which Fe{sub 2} O{sub 3} has been studied due his property of decrease the Dielectric Loss factor and increase the Mechanical Quality Factor of PZT Ceramics. With this purpose a powder was synthesized through an organic precursors route, where a finely divided powder, with a good PZT phase formation at low temperatures. The electrical properties of temperatures. The electrical properties of the [Pb{sub 0.9.8} Sr 0{sub .53} Ti{sub o.4676} Fe{sub 0.00024} {sub 03}] compositions with 1% of Pb O excess confirmed the Fe{sub 2} (O{sub 3}) additive performance, counterbalancing with Sr O effects. (author) 7 refs., 5 figs., 3 tabs.

  9. Industrial ceramics

    Mengelle, Ch.

    1999-04-01

    After having given the definition of the term 'ceramics', the author describes the different manufacturing processes of these compounds. These materials are particularly used in the fields of 1)petroleum industry (in primary and secondary reforming units, in carbon black reactors and ethylene furnaces). 2)nuclear industry (for instance UO 2 and PuO 2 as fuels; SiC for encapsulation; boron carbides for control systems..)

  10. Investigação sobre a eficiência da fibra de vidro e da fibra cerâmica como suporte de solda na soldagem unilateral Investigation over the eficiency of fiber glass and ceramic fiber as weld support in one-sided welding

    Luiz Cláudio Tatagiba

    2011-12-01

    Full Text Available O objetivo deste trabalho foi avaliar uma nova categoria de suporte de solda para a soldagem unilateral do aço carbono, usando tecidos de fibra de vidro e fibra cerâmica. Trata-se de uma proposta de inovação tecnológica, uma evolução do suporte cerâmico convencional. A soldagem unilateral com este tipo de suporte de solda foi executada em chapas de aço carbono com arame tubular (FCAW e MIG-MAG (GMAW. A eficiência da fibra de vidro e da fibra cerâmica em suportar o metal de solda líquido foi verificada durante a soldagem do passe de raiz. Várias espessuras e combinações de tecidos de fibra de vidro e fibra cerâmica foram testadas, bem como foram identificados pontos de trabalho. As seguintes variáveis do processo foram estudadas: a abertura de raiz, a corrente e a velocidade de soldagem. Os resultados mostram que os materiais à base de fibra de vidro e fibra cerâmica são eficientes para suportar a poça de solda líquida. O modo de fixação do suporte de solda na junta soldada também mostrou ser efetivo. Foi possível estimar uma faixa de operação do processo, com abertura de raiz de 2,0 a 4,0 mm, a energia de soldagem menor que 1,8 kJ/mm, a técnica de soldagem ligeiramente puxando e com pequena oscilação da tocha, espessura do suporte de solda de tecido de fibra de vidro maior que 1,6 mm. Macrogafias da juntas soldadas mostraram que houve penetração nas laterais do chanfro, reforço de solda adequado na raiz e não foram notados defeitos.The objective of this work was to evaluate a new chategory of weld support for the one-sided welding of carbon steel, using fiber glass and ceramic fiber tissues. This is a proposal of techonological innovation proposed, an evolution of the conventional ceramic support. The one-sided welding with this type of weld support was made in carbon steel with FCAW and GMAW. The efficiency of fiber glass and ceramic fiber was verified during the root weld bead. Several thicknesses and

  11. Técnicas para avaliação da consolidação de suspensões cerâmicas com o uso de diferentes ligantes Techniques for setting evaluation of ceramic suspensions with different binders

    I. R. Oliveira

    2007-06-01

    Full Text Available O desenvolvimento de concretos refratários avançados exige uma otimização simultânea das propriedades reológicas (fluidez e trabalhabilidade e do tempo de desmoldagem desses materiais. Geralmente, tais propriedades, bem como as variáveis que as influenciam, são avaliadas diretamente no concreto refratário por meio de medidas de fluidez e da resistência mecânica. Tal procedimento demanda tempo e limita a investigação sobre todas as possíveis combinações de variáveis que podem influenciar o mecanismo de consolidação a partir de diferentes agentes ligantes. Neste contexto, esse trabalho tem como objetivo apresentar técnicas alternativas que podem facilitar a avaliação da consolidação de suspensões cerâmicas com o uso de diferentes ligantes, correlacionando propriedades macroscópicas como trabalhabilidade e o tempo de desmoldagem de concretos refratários. Tais técnicas consistem em medidas de condutividade elétrica, da temperatura, dos módulos de armazenamento (G' e de perda (G" dos materiais (ensaios reológicos oscilatórios, e da resistência do material a uma deformação axial imposta (ensaios reológicos de força normal.The development of advanced refractory castables demands a simultaneous optimization of rheological properties (fluidity and workability and the time for demolding. Generally, such properties and the variables that influence them, (temperature and additives are directly evaluated in the refractory castable. Nevertheless, such procedure demands time and limits the investigation related to the variables that can influence the suspensions consolidation mechanism. In this context, the objective of this work is to present alternative techniques that could better evaluate the setting of ceramic suspensions containing different binders. The results obtained can be correlated with castable macroscopic properties such as workability and demolding time. These techniques comprise the measurements of

  12. Avaliação da permeabilidade de filtros de aerossóis para altas temperaturas, preparados a partir da técnica de adição de espuma aquosa em suspensão cerâmica Permeability characterization of hot aerosol filters prepared with foaming of ceramic suspensions

    M. D. M. Innocentini

    2009-12-01

    Full Text Available Este trabalho é parte de um projeto de desenvolvimento de filtros cerâmicos para a remoção de material particulado disperso em correntes gasosas em temperaturas elevadas. Os filtros cerâmicos utilizados para esta finalidade devem apresentar elevada porosidade aliada a uma distribuição homogênea de poros interconectados, resultando em estrutura permeável e com boa resistência mecânica e eficiência de coleta. Uma rota de processamento recentemente desenvolvida é utilizada para o processamento das peças, já que permite a obtenção de todas as características requeridas para uma filtração eficiente. Nesta técnica, os materiais porosos são processados a partir da incorporação de espumas aquosas em uma suspensão cerâmica de alumina e consolidados a partir da adição de cimento aluminoso. Comparado com outras rotas de processamento, este processo é mais atrativo, pois permite a fabricação de peças com geometrias complexas, economicamente viáveis e sem utilização de aditivos tóxicos. O objetivo deste trabalho foi otimizar a composição cerâmica de modo a atender aos requisitos de permeabilidade do filtro, tendo como base sua operação econômica em temperaturas elevadas em processos como incineração de resíduos, produção de cimento ou queima de biomassa em caldeiras em plantas químicas.This work is part of a project to develop ceramic filters to treat flue gases from cement plants, biomass boilers and waste incinerators. Ceramic filters used for these purposes must present high porosity, homogeneous porous distribution (interconnected to result in bodies with high mechanical strength, permeability and collection efficiency for fine particles. A method recently developed has been used for the filters processing. In this new processing route, the porous samples were prepared through the incorporation of aqueous foams into alumina-based suspensions. Compared to other techniques, this process seems to be an

  13. Otimização da permeabilidade de filtros de aerossóis para altas temperaturas preparados a partir da técnica de adição de espuma aquosa em suspensão cerâmica Permeability optimization of hot aerosol filters prepared from foaming of ceramic suspensions

    M. D. M. Innocentini

    2009-03-01

    Full Text Available Este trabalho é parte de um projeto de desenvolvimento de filtros cerâmicos para a remoção de material particulado disperso em correntes gasosas em temperaturas elevadas. Os filtros cerâmicos utilizados para esta finalidade devem apresentar elevada porosidade aliada a uma distribuição homogênea de poros interconectados, resultando em estrutura permeável e com boa resistência mecânica e eficiência de coleta. Uma rota de processamento recentemente desenvolvida é utilizada para o processamento das peças, já que permite a obtenção de todas as características requeridas para uma filtração eficiente. Nesta técnica, os materiais porosos são processados a partir da incorporação de espumas aquosas em uma suspensão cerâmica de alumina e consolidados a partir da adição de cimento aluminoso. Comparado com outras rotas de processamento, este processo é mais atrativo, pois permite a fabricação de peças com geometrias complexas, economicamente viáveis e sem utilização de aditivos tóxicos. O objetivo deste trabalho foi otimizar a composição cerâmica de modo a atender aos requisitos de permeabilidade do filtro, tendo como base sua operação econômica em temperaturas elevadas em processos como incineração de resíduos, produção de cimento ou queima de biomassa em caldeiras em plantas químicas.This work is part of a Brazilian project to develop ceramic filters to treat flue gases from cement plants, biomass boilers and waste incinerators. Ceramic filters used for these purposes must present high porosity, homogeneous porous distribution (interconnected to result in bodies with high mechanical strength, permeability and collection efficiency for fine particles. A method recently developed has been used for the filters processing. In this new processing route, the porous samples were prepared through the incorporation of aqueous foams into alumina-based suspensions. Compared to other techniques, this process seems to be

  14. Chemical, mineralogical and ceramic properties of clays from Northern Santa Catarina, Brazil; Caracterizaco fisico-quimica de argilas da regiao norte de Santa Catarina

    Correia, S L; Bloot, E L; Folgueras, M.V., E-mail: sivaldo@joinville.udesc.b [Universidade do Estado de Santa Catarina (UDESC/CCT), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas; Hotza, D [Universidade Federal de Santa Catarina (UFSC/EQA), Florianopolis, SC (Brazil). Dept. de Engenharia Quimica

    2009-07-01

    Clay materials crop out in the northern Santa Catarina mining district were investigated in order to assess their potential in the ceramic industry. Four different clays (A, B, C and D) were selected. Their chemical composition was obtained by Xray fluorescence and their mineralogy by X-ray diffraction, coupled with numerical rational analysis. Their thermal behaviour was studied by differential thermal analysis. Technological testing consisted in a simulation of the industrial processing performed at a laboratory scale. The test pieces were obtained by pressing and fired in the range of 850-1200 deg C. In each case their technological properties were studied. The main mineralogical phases detected were kaolinite, quartz and mica. Hematite and feldspars may be present in the clays. The clays show two groups of particle sizes almost equally frequent in the range of 1 to 60 {mu}m. The northern Santa Catarina clays are suitable for the production of bricks and earthenware in the 900- 1100 deg C range. (author)

  15. The feasibility analysis for the merger of powder from steel making dedusting system in red ceramic; Analise da viabilidade da incorporacao do po de despoeiramento siderurgico em ceramica vermelha

    Santos, D.M.S.; Goncalves, S.S.; Mocbel, E.B.B.; Barbosa, A.C.C.; Leal, A.P.S.; Lopes, S.A.; Feitosa, E.F.; Silva, G.S.; Rabelo, A.A.; Fagury Neto, E., E-mail: danilo.marciano@gmail.com, E-mail: fagury@unifesspa.edu.br [Universidade Federal do Sul e Sudeste do Para (UNIFESSPA), Maraba, PA (Brazil). Instituto de Geociencias e Engenharias

    2016-07-01

    The aim of this work was to study the variation of physical and mechanical properties of ceramics made from two clays with the addition of dedusting system powder from a local steel making plant (SDP), which was added in proportions of 3%, 5 %, 7 % and 10 %. The test-bodies were shaped by uniaxial two-stage pressing, calcined for 2 hours at 300 °C and sintered at temperatures of 900 °C, 1000 °C and 1100 °C. The analyzed properties were apparent density, water absorption, apparent porosity, linear firing shrinkage, flexural strength and plasticity index. The starting materials were characterized by XRF as well, in order to evaluate the chemical composition. This methodology showed good results in the development of future work related to the area. (author)

  16. Effect of airborne particle abrasion protocols on surface topography of Y-TZP ceramic Efeito do protocolo de jateamento com partículas na topografia da superfície de uma cerâmica Y-TZP

    J. R. C. Queiroz

    2012-06-01

    Full Text Available This study aimed to evaluate Y-TZP surface after different airborne particle abrasion protocols. Seventy-six Y-TZP ceramic blocks (5×4×4 mm³ were sintered and polished. Specimens were randomly divided into 19 groups (n=4 according to control group and 3 factors: a protocol duration (2 and 4 s; b particle size (30 µm, alumina coated silica particle; 45 µm, alumina particle; and 145 µm, alumina particle and; c pressure (1.5, 2.5 and 4.5 bar. Airborne particle abrasion was performed following a strict protocol. For qualitative and quantitative results, topography surfaces were analyzed in a digital optical profilometer (Interference Microscopic, using different roughness parameters (Ra, Rq, Rz, X-crossing, Mr1, Mr2 and Sdr and 3D images. Surface roughness also was analyzed following the primer and silane applications on Y-TZP surfaces. One-way ANOVA revealed that treatments (application period, particle size and pressure of particle blasting provided significant difference for all roughness parameters. The Tukey test determined that the significant differences between groups were different among roughness parameters. In qualitative analysis, the bonding agent application reduced roughness, filing the valleys in the surface. The protocols performed in this study verified that application period, particle size and pressure influenced the topographic pattern and amplitude of roughness.O objetivo deste estudo foi avaliar a superfície de uma cerâmica à base de zircônia tetragonal estabilizada por ítria (Y-TZP após diferentes protocolos de jateamento com partículas. Setenta e seis blocos cerâmicos de Y-TZP (5 x 4 x 4 mm³ foram sinterizados e polidos. As amostras foram randomicamente divididas em 19 grupos (n=4 sendo um controle e 18 grupos utilizando 3 fatores: a tempo (2 e 4 s; b tamanho de partícula (30 µm - partículas de alumina revestida por sílica; 45 µm - partículas de alumina; 145 µm - partículas de alumina e; c pressão (1

  17. Decision theory on the quality evaluation of medical images; A teoria da decisao na avaliacao da qualidade da imagem medica

    Lessa, Patricia Silva

    2001-10-01

    The problem of quality has been a constant issue in every organization.One is always seeking to produce more, to do it at a lower cost, and to do it with better quality. However, in this country, there is no radiographic film quality control system for radiographic services. The tittle that actually gets done is essentially ad hoc and superficial. The implications of this gap, along with some other shortcomings that exist in process as a whole (the state of the x-ray equipment, the adequate to use in order to obtain a radiography, the quality of the film, the processing of the film, the brightness and homogeneity of the viewing boxes, the ability of the radiologist), have a very negative impact on the quality of the medical image, and, as result, to the quality of the medical diagnosis and therapy. It frequently happens that many radiographs have to be repeated, which leads to an increase of the patient's exposure to radiation, as well as of the cost of the procedure for the patient. Low quality radiographs that are not repeated greatly increase the probability of a wrong diagnosis, and consequently, of inadequate therapeutical procedures, thus producing increased incidence of bad outcomes and higher costs. The paradigm proposed in order to establish a system for the measurement of the image's quality is Decision Theory. The problem of the assessment of the image is studied by proposing a Decision Theory approach. The review of the literature reveals a great concern with the quality of the image, along with an absence of an adequate paradigm and several essentially empirical procedures. Image parameters are developed in order to formalize the problem in terms of Decision Theory, and various aspects of image digitalisation are exposed. Finally, a solution is presented, including a protocol for quality control. (author)

  18. Síntese e caracterização da cerâmica PZT dopada com íons bário Synthesis and characterization of barium-doped PZT ceramics

    G. Gasparotto

    2003-04-01

    Full Text Available Pós de titanato zirconato de chumbo (PZT puros e dopados com bário foram obtidos pelo método de precursores poliméricos, conformados uniaxialmente, na forma de cilindros, utilizando 15 MPa, e prensados isostaticamente à 210MPa. Com o objetivo de estudar o comportamento de sinterização os compactos foram divididos em dois lotes. Sendo um sinterizado em um forno acoplado a um dilatômetro até a temperatura de 1300 °C e o outro sinterizado em forno tipo mufla, em sistema fechado, na temperatura de 1100 °C por 4 horas. Verificou-se que a adição do íon bário influencia na cinética de sinterização, na densificação final, na microestrutura e nas propriedades elétricas da cerâmica. A adição de bário aumenta a concentração da fase tetragonal no PZT, em função da substituição do chumbo por bário na rede perovskita. As amostras dopadas com concentrações maiores que 5,0 mol % em bário apresentaram segregação de PbO no contorno de grão, inibindo seu crescimento.Pure and barium doped lead zirconate titanate powders were obtained by the polymeric precursor method, uniaxially conformed in cylinders form using 15 MPa and pressing isostatically at 210 MPa. In order to study the sintering behaviour, the compacts were divided in two parts. One part was sintered in a dilatometer furnace till 1300 °C and the other one sintered in muffle furnace in the temperature of 1100 °C for 4 hours. It was verified that the addition of barium influences on the sintering kinetics, on the final density, microstructure and electric properties of the ceramics. The addition of barium increases the concentration of the tetragonal phase of PZT due to the substitution of lead by barium in the perovskite lattice. The samples doped with barium concentrations higher than 5.0 mol % leads to the segregation of PbO in the grain boundary, inhibiting grain growth.

  19. Activity evaluation from different native or irradiated with {sup 60} Co gamma rays snake venoms and their inhibitory effect on Leishmania (Leishmania) amazonensis; Avaliacao da atividade de diferentes venenos de serpentes, nativos ou irradiados, com radiacao gama de {sup 60} Co, quanto ao poder inibitorio do crescimento de Leishmania (Leishmania) amazonensis

    Lourenco, Cecilia de Oliveira

    2000-07-01

    Cutaneous leishmaniasis is a disease, caused by Leishmania parasites, that occurs frequently in tropical and sub-tropical regions of the world. Skin lesions that could results in disfiguring aspect characterize it. The treatment is based on few drugs as antimony salts or pentamidine that are toxic with increasing resistance by the parasite. Alternative forms of disease treatment are in constant search, including natural components as snake venoms. Previous studies demonstrate that some components of snake venoms have an inhibitory effect against those parasites, including Leishmania species. Although snake venoms presented high toxicity, several methods have been described to detoxify most or some of their toxic components, with favorable results by the use of gamma irradiation. In this report we tested several native and irradiated snake venoms for inhibitory effect against Leishmania (Leishmania) amazonensis parasite and LLCMK{sub 2} mammalian cells, with enzymatic tests and electrophoresis. There are significant activity in Acanthophis antarcticus, Agkistrodon bilineatus, Bothrops moojeni, Bothrops jararaca, Hoplocephalus stephensi, Naja melanoleuca, Naja mossambica, Pseudechis australis, Pseudechis colletti, Pseudechis guttatus and Pseudechis porphyriacus, venom being inactive Pseudonaja textilis, Notechis ater niger, Notechis scutatus. Oxyuranus microlepidotus and Oxyuranus scutellatus venoms. After 2 KGy of {sup 60}Co irradiation most venom loses significantly their activity. Venoms with antileishmanial activity presented L-amino acid oxidase (L-AO) activity and showed common protein with a molecular weight about 60kDa in SDS-PAGE. These results indicate that L-AO activity in those venoms are probably related with antileishmanial effect. (author)

  20. Ceramic Laser Materials

    Guillermo Villalobos

    2012-02-01

    Full Text Available Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements.

  1. Ceramic Laser Materials

    Sanghera, Jasbinder; Kim, Woohong; Villalobos, Guillermo; Shaw, Brandon; Baker, Colin; Frantz, Jesse; Sadowski, Bryan; Aggarwal, Ishwar

    2012-01-01

    Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements. PMID:28817044

  2. Influência da cinética de oxidação no controle da atmosfera de fornos de revestimentos cerâmicos Influence of the oxidation kinetics for control of the atmosphere of kilns for production of ceramic tiles

    S. Cava

    2000-06-01

    Full Text Available No processo de monoqueima para produção de revestimentos cerâmicos, o aparecimento do "coração negro" ocorre sob determinadas condições de matérias-primas utilizadas e parâmetros do processo industrial. Neste sentido, decidimos pesquisar os efeitos de uma atmosfera enriquecida com oxigênio para minimizar defeitos como o "coração negro", com o objetivo de reduzir o ciclo de queima. Foram realizadas uma completa caracterização física e química das matérias-primas utilizadas. Os corpos de prova foram queimados em um forno de laboratório tipo câmara, eletricamente aquecido, com controle de atmosfera, e simulação do processo de queima rápida. Fluxos de uma mistura de oxigênio e/ou misturas de oxigênio foram continuamente adicionados no forno por dois diferentes métodos. A tendência da eliminação do coração negro em função da atmosfera do forno foi avaliada pela medida da relação de volumes de coração negro e volume total da amostra. Os resultados, conforme o modelo proposto, mostram que o efeito da atmosfera enriquecida com oxigênio segue as equações determinadas pelos modelos cinéticos de reação de oxi-redução, que neste caso, determina a evolução da eliminação do defeito "coração negro" em função da atmosfera modificada com oxigênio introduzida no forno. Isto indica que além de melhorar a qualidade do produto final, pode-se aumentar a produtividade, reduzindo o ciclo de queima.In the single firing process for the production of ceramic tiles, the appearance of the "black core" defect occurs under determined conditions of raw materials and parameters of the industrial process. It was then decided to investigate the effects of an oxygen enriched atmosphere for minimizing the occurrence of defects such as "black core", with the goal of reducing the firing cycle. A complete physical and chemical characterization of the used raw materials was carried out. Raw material samples were fired in an

  3. Study of thermocycling effect on the bond strength between an aluminous ceramic and a resin cement Estudo do efeito da ciclagem térmica na resistência da união adesiva entre uma cerâmica aluminizada e um cimento resinoso

    Osvaldo Daniel Andreatta Filho

    2005-03-01

    Full Text Available This study evaluated the effect of thermocycling on the bond strength between Procera AllCeram (Nobel-Biocare and a resin cement (Panavia F, Kuraray CO. Nine ceramic blocks with dimensions of 5x6x6mm were conditioned at one face with Rocatec System (Espe. After, they were luted with Panavia F to composite resin blocks (Clearfil AP-X, Kuraray CO. The nine groups formed by ceramic, cement and composite resin were split up obtaining 75 samples with dimensions of 12x1x1mm and adhesive surface presenting 1mm²±0.1mm² of area. The samples were divided into 3 groups (n=25: G1 - 14 days in distilled water at 37ºC; G2 - 6,000 cycles in water (5ºC - 55ºC - 30s; G3 - 12,000 cycles in water (5ºC - 55ºC - 30s. The samples were tested in a universal testing machine (EMIC at a crosshead speed of 1mm/min. Data were analyzed by ANOVA and Tukey tests. The results indicated that mean values of rupture tension (MPa of G1 (10.71 ± 3.54 did not differ statistically (p Este trabalho avaliou o efeito da ciclagem térmica sobre a resistência adesiva entre a cerâmica aluminizada (Procera AllCeram, Nobel-Biocare e um cimento resinoso (Panavia F, Kuraray CO. Nove blocos de cerâmica, com dimensões de 5x6x6mm, foram condicionados em uma de suas faces com o Sistema Rocatec (ESPE. A seguir foram cimentados a blocos de resina composta (Clearfil AP-X, Kuraray CO. Os conjuntos cerâmica-cimento-resina foram cortados em 75 corpos-de-prova com formato retangular com dimensões de 12x1x1mm e superfície adesiva apresentando 1mm² ± 0,1mm². Os corpos-de-prova foram divididos em três grupos (n=25: G1 - 14 dias em água destilada a 37ºC, G2 - 6000 ciclos em água (5ºC e 55ºC e G3 - 12000 ciclos em água (5ºC e 55ºC. Os corpos-de-prova foram ensaiados sob velocidade de 1mm/min em máquina de ensaio universal (EMIC. Os dados foram tratados estatisticamente com os testes de Anova e Tukey e indicaram que os valores médios de tensão de rupturas (MPa de G1 (10,71 ± 3

  4. Partial replacement of Portland cement by red ceramic waste in mortars: study of pozzolanic activity; Substituicao parcial do cimento Portland por residuo de ceramica vermelha em argamassas: estudo da atividade pozolonica

    Silva, A.R. da; Cabral, K.C.; Pinto, E.N. de M.G.l., E-mail: kleber.cabral@ufersa.edu.br [Universidade Federal Rural do Semi-Arido (UFERSA), Mossoro, RN (Brazil)

    2016-07-01

    The objective of this study is to analyze the pozzolanic activity of red ceramic residue on the partial replacement of Portland cement in mortars. The mortars were prepared by substituting 25% of the Portland cement for ground of ceramic residue with water cement’s factor of 0.48. The concrete used to construct the reference mortars and those with addiction was CPII-Z-32 (compound of Portland pozzolana cement). The chemical analysis and physical ceramic waste showed that this meets the requirements of NBR12653 (2014) for use as pozzolanic material. The pozzolanic activity index (IAP) obtained for the ceramic waste to twenty-eight days cure rate was 80.28%. (author)

  5. Creep in ceramics

    Pelleg, Joshua

    2017-01-01

    This textbook is one of its kind, since there are no other books on Creep in Ceramics. The book consist of two parts: A and B. In part A general knowledge of creep in ceramics is considered, while part B specifies creep in technologically important ceramics. Part B covers creep in oxide ceramics, carnides and nitrides. While covering all relevant information regarding raw materials and characterization of creep in ceramics, the book also summarizes most recent innovations and developments in this field as a result of extensive literature search.

  6. Ceramic Parts for Turbines

    Jones, R. D.; Carpenter, Harry W.; Tellier, Jim; Rollins, Clark; Stormo, Jerry

    1987-01-01

    Abilities of ceramics to serve as turbine blades, stator vanes, and other elements in hot-gas flow of rocket engines discussed in report. Ceramics prime candidates, because of resistance to heat, low density, and tolerance of hostile environments. Ceramics considered in report are silicon nitride, silicon carbide, and new generation of such ceramic composites as transformation-toughened zirconia and alumina and particulate- or whisker-reinforced matrices. Report predicts properly designed ceramic components viable in advanced high-temperature rocket engines and recommends future work.

  7. Forming of superplastic ceramics

    Lesuer, D.R.; Wadsworth, J.; Nieh, T.G.

    1994-05-01

    Superplasticity in ceramics has now advanced to the stage that technologically viable superplastic deformation processing can be performed. In this paper, examples of superplastic forming and diffusion bonding of ceramic components are given. Recent work in biaxial gas-pressure forming of several ceramics is provided. These include yttria-stabilized, tetragonal zirconia (YTZP), a 20% alumina/YTZP composite, and silicon. In addition, the concurrent superplastic forming and diffusion bonding of a hybrid ceramic-metal structure are presented. These forming processes offer technological advantages of greater dimensional control and increased variety and complexity of shapes than is possible with conventional ceramic shaping technology.

  8. Ceramic gas turbine shroud

    Shi, Jun; Green, Kevin E.

    2014-07-22

    An example gas turbine engine shroud includes a first annular ceramic wall having an inner side for resisting high temperature turbine engine gasses and an outer side with a plurality of radial slots. A second annular metallic wall is positioned radially outwardly of and enclosing the first annular ceramic wall and has a plurality of tabs in communication with the slot of the first annular ceramic wall. The tabs of the second annular metallic wall and slots of the first annular ceramic wall are in communication such that the first annular ceramic wall and second annular metallic wall are affixed.

  9. Thin film ceramic thermocouples

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  10. Use of the extraction residue of emeralds in a formulation mass of ceramic tiles; Utilizacao do residuo da extracao de esmeraldas em uma formulacao de massa de revestimento ceramico

    Cavalcante, R. F., E-mail: ronaldofcavalcante@gmail.com [Programa de Pos-Graduacao em Engenharia Mecanica - PPgEM - UFRN, Universidade Federal do Rio Grande do Norte, Lagoa Nova, RN (Brazil); Nascimento, R.M.; Paskocimas, C.A., E-mail: rmaribondo@ufrnet.br, E-mail: paskocimas_ca@hotmail.com [Departamento de Engenharia Materiais - DEMAT - Universidade Federal do Rio Grande do Norte, Lagoa Nova, RN (Brazil); Dutra, R.P.S., E-mail: ricardodutra@ct.ufpb.br [Departamento de Engenharia Materiais - DEMAT - UFPB - Universidade Federal de Pernambuco, Recife (Brazil)

    2012-04-15

    Companies involved in mining and beneficiation of emerald represent an important area of industrial development in Brazil, with a significant contribution to world production of this ore. As a result, large volumes of waste generated and emerald are constantly abandoned in the environment, contributing negatively to their preservation. On the other hand the interest in the use of mining waste as an additive in production of ceramic materials has grown among researchers in recent years. The ceramic industry is constantly seeking to expand the market for the sector and trying to improve product quality and increase the variety of applications. The technology of obtaining ceramic coating that uses waste from mining is still a largely unexplored market. Thus, the purpose of this study was to characterize the waste generated from mining emerald as well as to evaluate its potential use as raw material for production melting of ceramic tiles. Ceramic mixtures were prepared from raw materials characterized by X-ray fluorescence and X-ray diffraction. Five compositions were prepared using the waste codes of emeralds from 0%, 10%, 20%, 30% and 40%. Samples were prepared by pressing, sintered at 1000, 1100 and 1200 deg C and characterized to establish their mineralogical composition, water absorption, linear shrinkage and modulus of rupture. The results showed that the residue of emeralds studied can be embedded in the mass of ceramic tiles up to 20% in replacement of feldspar without compromising the end product properties. (author)

  11. SPECT for smokers brain perfusion evaluation; SPECT para avaliacao da perfusao cerebral em fumantes

    Maliska, C.M.; Martins, E.F.; Barros, D.S.; Lopes, M.M.S.; Lourenco, C.; Goncalves, S.; Goncalves, M.B.; Miranda, M.M.B.G.; Neto, L.M.; Penque, E.; Antonucci, J.B. [Instituto Nacional do Cancer, Rio de Janeiro, RJ (Brazil)

    2002-07-01

    Cigarette smoking increases brain stroke risk, however,five to fifteen years after ceasing this habit, brain perfusion recovers normal pattern. We propose to compare brain perfusion patterns performing brain SPECT scans of smokers and non-smokers. Thirteen volunteers age range 20-30 years old) composed of six non-smokers and seven smokers were studied by brain scans (SPECT).We used ECD- {sup 99m} Tc radiolabelled as recommended by the manufacturer. All patients received 740 MBq of the radiopharmaceutical through intravenous injection, with their eyes opened and their ears unplugged, in a quiet room. We used a one head SPECT camera ( General Electric/ StarCam 4000 and Siemens/ E.Cam) with low-energy ultrahigh resolution collimator. Imaging begin 40 minutes after tracer injection. For reconstruction we used a Butterworth filter.The preliminary results showed brain perfusion deficit areas on five of the smokers while all non- smokers had normal brain perfusion scans. We believe that smoking increases the possibility of brain perfusion deficits. (author)

  12. Integrity assessment of pipelines - additional remarks; Avaliacao da integridade de dutos - observacoes adicionais

    Alves, Luis F.C. [PETROBRAS S.A., Salvador, BA (Brazil). Unidade de Negocios. Exploracao e Producao

    2005-07-01

    Integrity assessment of pipelines is part of a process that aims to enhance the operating safety of pipelines. During this task, questions related to the interpretation of inspection reports and the way of regarding the impact of several parameters on the pipeline integrity normally come up. In order to satisfactorily answer such questions, the integrity assessment team must be able to suitably approach different subjects such as corrosion control and monitoring, assessment of metal loss and geometric anomalies, and third party activities. This paper presents additional remarks on some of these questions based on the integrity assessment of almost fifty pipelines that has been done at PETROBRAS/E and P Bahia over the past eight years. (author)

  13. Avaliacao da gestao ambiental dos hoteis de selva na Amazonia, Brasil

    Gomes de Moraes, Adriana

    2008-10-01

    Full Text Available In the challenge of desvelar of that it forms the hoteleiros enterprises they manage its ambient action without causing great impacts in one of biggest ecosystems of the world, the Amazonian forest, was tried to know in this research the forms of ambient management of the located hotels of forest in the legal Amazônia. The norteadora question of the research was to know that type of ambient management is made by the hotels of selva?Foi used as instrument of collection of data the questionnaire, that if subdividiui in four great subjects to be searched. The first one was relative questions to the planning of the place, according to to the profile of the customer, third to the room and the relative questions architecture the building subject relative questions to the energy resources and infrastructure of the public services. As result of this analysis was concluded that two of three hotels searched are practising management ambient of form less impactante, since type of construction adopted until services offered to guests, or either shows objective that its hotel is coadjuvante for customer that visits this type of place, that stops it does not import luxury, comfort and amenities, more yes contact with the fauna and flora and way of life of the natives.

  14. Quality evaluation of blood irradiation process;Avaliacao da qualidade do processo de irradiacao de hemocomponentes

    Goto, R.E.; Medeiros, R.B. [Universidade Federal de Sao Paulo (DDI/UNIFESP), SP (Brazil). Dept. de Diagnostico por Imagem. Coordenadoria de Fisica e Higiene das Radiacoes

    2009-07-01

    An adverse reaction in blood transfusion is the graft versus host disease (GVHD). This disease affects immunodeficient or immunosuppressed patients where transfused T cells proliferate and initiate a host's immune system reaction. Blood gamma irradiation is the most efficient way to inhibit lymphocyte T blastic transformation and mitotic activity and it is the most effective method to combat this disorder. However, there is no fast and effective system to analyze the dose distribution in the irradiation process and guarantee that the absorbed doses are in agreement with FDA recommendations. This study aims to establish a periodic quality control of the gammacell irradiators using radiochromic films properly calibrated. The quality control is simply and effective to combat GVHD as well as is useful to detect mechanical fails at rotation set system through the dose uniformity analysis. It was possible to verify the uniformity ranged from -72.38% to 106.33% and some blood bag received doses not compatible with recommended international threshold. (author)

  15. Radiological evaluation of the cranio vertebral junction; Avaliacao radiologica da transicao cranio-vertebral

    Mello, Silvia Marcal Benicio de; Haetinger, Rainer Guilherme [Med Imagem - Beneficiencia Portuguesa de Sao Paulo, SP (Brazil). Setor de Cabeca e Pescoco]. E-mail: sbm@uol.com.br; Schettini, Marianna Cunha; Lima, Sergio Santos [Med Imagem - Beneficiencia Portuguesa de Sao Paulo, SP (Brazil); Mourao, Maria Lucia; Mendonca, Renato Adam [Med Imagem - Beneficiencia Portuguesa de Sao Paulo, SP (Brazil). Setor de Neuroradiologia

    2005-04-15

    The cranio vertebral junction (CVJ) comprises the occiput, atlas, their joints and ligaments. Besides conventional x-rays other imaging methods are need for the assessment of CVJ including high resolution computerized tomography (CT) and magnetic resonance imaging (MRI) which provide specific parameters such as field of view, slice thickness and incremental movement of the patient. A dynamic study is also important to assess the stability of the cranio vertebral junction and the effect upon the bulbomedullary junction. The aim of this study is to review the techniques used in the evaluation of the CVJ, the semiological parameters, and the most frequent disorders affecting this region. We review the literature and present conventional x-ray, CT and MRI images from the didactic file of the Radiology service 'Med Imagem - Beneficiencia Portuguesa de Sao Paulo, SP, Brazil, of cases with normal anatomy and the main congenital and acquired disorders of the CVJ. In daily practice, CVJ disorders are diagnoses using CT and MRI scans of the head and cervical spine. It is essential to be familiar with these conditions in order to preform specific tests which will allow a detailed study of the CVJ, thus providing the basis for the treatment, whenever indicated. (author)

  16. Crystallinity evaluation of polyhydroxybutyrate and polycaprolactone blends; Avaliacao da cristalinidade de blendas de polihidroxibutirato e policaprolactona

    Cavalcante, Maxwell P.; Rodrigues, Elton Jorge R.; Tavares, Maria Ines B., E-mail: maxdpc@gmail.com [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Instituto de Macromoleculas

    2015-07-01

    Polyhydroxybutyrate, PHB, is a polymer obtained through bacterial or synthetic pathways. It has been used in the biomedical field as a matrix for drug delivery, medical implants and as scaffold material for tissue engineering. PHB has high structural organization, which makes it highly crystalline and brittle, making biodegradation difficult, reducing its employability. In order to enhance the mechanical and biological properties of PHB, blends with other polymers, biocompatible or not, are researched and produced. In this regard, blends of PHB and polycaprolactone, PCL, another biopolymer widely used in the biomedical industry, were obtained via solution casting and were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and low field nuclear magnetic resonance (LF-NMR). Results have shown a dependence between PHB's crystallinity index and PCL quantity employed to obtain the blends.(author)

  17. Evaluation of occupational exposure in intraoral radiography; Avaliacao da dose ocupacional em radiografia intraoral

    Miguel, Cristiano; Barros, Frieda S.; Rocha, Anna S.P.S.; Godoi, Walmor C., E-mail: miguel_cristianoch@yahoo.com.br, E-mail: saicla@utfpr.edu.br, E-mail: annarocha@yahoo.com, E-mail: walmor.godoi@gmail.com [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Tilly Junior, Joao G., E-mail: joao.tilly@derax.com.br [Universidade Federal do Parana (HC/UFPR), Curitiba, PR (Brazil). Hospital das Clinicas

    2014-07-01

    The intraoral radiography is widely performed in the dental office due to low cost and agility. The doses in intraoral radiology are considered low, however it is known that doses below the threshold for deterministic radiation has the potential to induce stochastic effects. An intraoral radiography has a risk of inducing fatal cancer or serious in order of 1:10,000,000. Besides the patient, the dentist may also be being exposed to radiation during the work with the radiographics practices. The bibliographies demonstrates the lack of information on radiation protection of dentists, however, the occupational dose reduction was observed in radiology over the past 14 years. This work aims to evaluate the effective dose of radiation to which workers can be exposed dentists in dental offices to perform intraoral radiographs. In this context, a study was be conducted between June 2013 and May 2014 with 44 professionals in Curitiba city. For each dentist was given a personal dosimeter to be used for 30 days. During this period, the number of radiographies and the length of the cable triggers of the X-ray equipment was registered and, the dosimeter´s dose was read. It was observed that the cables triggers meet regulatory standards and allow dentists to get the mean minimum distance of two meters from the radiation source in 93% of cases. Through analysis of the doses, it was concluded that occupational exposures of these workers are within the recommended threshold by regulatory 453/1998 of the Ministry of Health from Brazil. (author)

  18. Imaging assessment of osteitis pubis; Avaliacao por imagem da osteite pubica

    Lopes, Alexia Abuhid; Ferreira, Ana Paula Alves; Leite, Ana Rachel Albuquerque de Moura; Guido, Daniela Araujo; Rodrigues, Rogeria Nobre [Axial Centro de Imagem, Belo Horizonte, MG (Brazil)]. E-mail: ce@cidbh.com.br; Araujo, Rodrigo Otavio Dias [Minas Tenis Clube, Belo Horizonte, MG (Brazil); Lasmar, Rodrigo Campos Pace [Faculdade de Ciencias Medicas de Minas Gerais, Belo Horizonte, MG (Brazil). Curso de Fisioterapia

    2005-10-15

    Objective: to assess the physiopathological aspects of osteitis pubis and the findings seen on imaging methods, emphasizing the usefulness of Flamingo view radiographs and the diagnostic aspects of Magnetic resonance images. Material and Method: magnetic resonance images of ten patients (eight of them professional athletes) referring symptoms in the inguinal regional were retrospectively evaluated. For some of these patients Flaming view radiographs were performed. Results: in all studied patients magnetic resonance imaging was the only diagnostic method capable of showing the different phases os osteitis pubis, from acute cases with pubic bone marrow edematous changes to chronic cases with involvement of other pelvic joints. Flamingo view radiographs were performed in six patients and three of them were diagnosed with vertical pubis symphyseal instability greater than 2 mm of vertical displacement. This diagnosis was confirmed by instability tests using orthopedic manoeuvres. Conclusion: magnetic resonance imaging was the most helpful method for the diagnosis of different phases of osteitis pubis whereas conventional X-ray was inconclusive in the initial phases. Flamingo view radiographs were extremely important to show vertical instability of the pubic symphysis, which in combination with osteitis pubis can be the cause of failure of nonoperative treatment. (author)

  19. Magnetomotive colon elastography: preliminary assessment; Elastografia magnetomotriz da regiao do colon: avaliacao preliminar em phantoms

    Bruno, A. Colello, E-mail: alexandrecolellobruno@usp.br [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Medicina; Grillo, F.W.; Sampaio, D.R.T.; Carneiro, A.A.O. [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia Ciencias e Letras

    2015-08-15

    Colorectal cancer (CRC) is the third most common malignant neoplasm worldwide and early diagnosis reduces morbidity. The standard preventive exams methods are uncomfortable for the patient, invasive, and /or are ionizing. Here, we evaluate the potential of magneto-motive ultrasound (MMUS) as a new, minimally invasive CRC screening technique. We developed a hybrid transducer (comprised of an ultrasound probe and a magnetic coil system) to construct relative elastography maps in a paraffin phantom with isoechoic inclusions. The electromagnetic component of our system manipulated ferromagnetic fluid located inside of our synthetic colon, and the captured ultrasound images were used to produce relative elastography maps. The MMUS images reveal by otherwise invisible structures based on differences in stiffness. Ultrasound elastography (relative) images by MMUs technique complements usual preventive CRC exams, is minimally invasive, has relative low cost when compared with others image methods. Also is fast diagnose and more comfortable for patient which prevents withdrawal of the screening. (author)

  20. Influência da expansão por umidade no comportamento mecânico de argilas para uso em blocos de cerâmica vermelha - revisão Influence of moisture expansion on the mechanical behavior of structural clay materials for use in ceramic bricks - review

    R. A. Andrade

    2011-09-01

    Full Text Available O fenômeno da expansão por umidade (EPU resulta da ação da água e seus vapores causando a expansão dos materiais cerâmicos, podendo provocar danos no material e prejudicar sua vida útil. Na literatura existe muita ênfase nos problemas gerados pela EPU e nas tensões resultantes dessa expansão, porém até o presente não há dados relativos ao comportamento mecânico dos materiais cerâmicos após ação da EPU. Trabalhos recentemente desenvolvidos na UFCG tratam especificamente desse problema em blocos cerâmicos de vedação. Inicialmente verificou-se que, no caso de massas cerâmicas para uso em cerâmica vermelha queimadas em diversas temperaturas na faixa de 700 a 1100 ºC, e com a EPU induzida por imersão, fervura e autoclavagem, a EPU tem correlação com o comportamento mecânico dos corpos queimados, observando-se redução no módulo de ruptura à flexão à medida que a EPU aumenta. Trabalhos desenvolvidos com massas para uso em cerâmica vermelha aditivadas com carbonato de cálcio e carbonato de magnésio e queimadas entre 850 e 1000 ºC, evidenciaram o efeito benéfico do carbonato de cálcio na redução da EPU e aumento da resistência à flexão, sendo observada correlação entre EPU e módulo de ruptura à flexão, mas, no entanto, não foi observada correlação entre a EPU e o módulo quando da utilização do carbonato de magnésio. Pesquisas efetuadas com massas para cerâmica vermelha aditivadas com quartzo fino, visando o desenvolvimento de fases vítreas, não mostraram correlações bem definidas entre EPU e módulo de ruptura, sendo observado que adições de 10 e 20% de quartzo melhoram a resistência mecânica dos corpos cerâmicos após autoclavagem e que a adição de 30% de quartzo reduz seu módulo de ruptura.Moisture expansion (ME phenomenon results from the action of water and water vapors causing the expansion of ceramic materials, which may damage the material damage and jeopardize its useful life

  1. Technological characterization of new clay deposits in the south region of Amapa, Brazil aiming applications in the ceramic industry; Caracterizacao tecnologica de novos depositos de argilas da regiao sul do Amapa visando aplicacoes na industriav ceramica

    Silva, Adriano Lima da; Luna, Carlos Bruno Barreto; Chaves, Alexsandra Cristina; Neves, Gelmires de Araujo, E-mail: adrianolimadasilva@hotmail.com, E-mail: brunobarretodemaufcg@hotmail.com [Universidade Federal de Campina Grande (UAEMa/CCT/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais

    2017-01-15

    The objective of the present work was to characterize two new Clay deposits (A and B) from the south region of Amapa state, aiming to establish their adequate uses as ceramic raw materials and to promote the potential of the ceramic industry in the region. Were prepared specimens by uniaxial pressing, being applied a two phase pressing of 13,4 MPa and 20 MPa, respectively. The samples were dried in an oven at 110 deg C, and submitted to burning at 850, 1000 and 1200 deg C. Were determined linear firing shrinkage, water absorption, apparent porosity and modulus of flexural modulus of rupture, as well as mineralogical evolution after burning. Finishing, the microstructure of the sintered clay at 1200 deg C was evaluated in a scanning electron microscope. The results showed that the clay A presented a better mechanical development, having a red coloration and, therefore, potential to the red ceramic industry. On the other hand, the clay B presented a light color, due to a low content of iron oxide and, therefore, having potential as refractory raw material. In general, one clay is suitable to be used in white ceramic and the other in red ceramic. (author)

  2. Analyses of fine paste ceramics

    Sabloff, J.A.

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics

  3. Science and Technology of Ceramics

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 2. Science and Technology of Ceramics - Advanced Ceramics: Structural Ceramics and Glasses. Sheela K Ramasesha. Series Article Volume 5 Issue 2 February 2000 pp 4-11 ...

  4. Analyses of fine paste ceramics

    Sabloff, J A [ed.

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics. (DLC)

  5. Hydrothermal degradation of tetragonal ZrO{sub 2} ceramic components used in dental applications; Efeito da degradacao em meio aquoso de componentes ceramicos a base de ZrO{sub 2} tetragonal para uso odontologico

    Mukaeda, L.E.; Robin, A.; Taguchi, S.P. [Universidade de Sao Paulo (DEMAR/EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de Lorena. Dept. de Engenharia de Materiais; Santos, C. [ProtMat Materiais Avancados, Guaratingueta, SP (Brazil)

    2009-07-01

    With the evolution of the dental restoration techniques, a considerable growth in the demand of ceramic products occurred. These materials present good strength associated to reliability. In this work, micrometric and nanometric scale tetragonal ZrO{sub 2} blocks were sintered at 1500 deg C-2h and 1350 deg C-2h, respectively, ground and polished. Ceramics with relative density higher than 98% were obtained. The specimens were immersed in hot water (150 deg C), for times ranging from 10h to 30h. The mass variation of the samples was measured and the crystalline phases present before and after the degradation tests were identified by X-ray diffractometry, in order to evaluate the capacity of these ceramics in resisting to aqueous medium exposure. Materials with nanometric structure present higher resistance to degradation than those with micrometric scale, and this interferes in structural stability after the test, and reduces the martensitic transformation. (author)

  6. [Ceramic inlays and onlays].

    van Pelt, A W; de Kloet, H J; van der Kuy, P

    1996-11-01

    Large direct composite restorations can induce shrinkage related postoperative sensitivity. Indirect resin-bonded (tooth colored) restorations may perhaps prevent these complaints. Indirect bonded ceramics are especially attractive because of their biocompatibility and esthetic performance. Several procedures and techniques are currently available for the fabrication of ceramic restorations: firing, casting, heat-pressing and milling. In this article the different systems are described. Advantages, disadvantages and clinical performance of ceramic inlays are compared and discussed.

  7. Ceramic Electron Multiplier

    Comby, G.

    1996-01-01

    The Ceramic Electron Multipliers (CEM) is a compact, robust, linear and fast multi-channel electron multiplier. The Multi Layer Ceramic Technique (MLCT) allows to build metallic dynodes inside a compact ceramic block. The activation of the metallic dynodes enhances their secondary electron emission (SEE). The CEM can be used in multi-channel photomultipliers, multi-channel light intensifiers, ion detection, spectroscopy, analysis of time of flight events, particle detection or Cherenkov imaging detectors. (auth)

  8. Displacive Transformation in Ceramics

    1994-02-28

    PZT ), ceramics have attracted natural abundance. much attention for use in nonvolatile semiconductor mem- We attribute the observed spectra in Fig. I to...near a crack tip in piezoelectric ceramics of lead zirconate titanate ( PZT ) and barium titanate. They reasoned that the poling of ferroelectric... Texture in Ferroelastic Tetragonal Zirconia," J. Am. Ceram . Soc., 73 (1990) no. 6: 1777-1779. 27. J. F. Jue and A. Virkar, "Fabrication, Microstructural

  9. Continuous Fiber Ceramic Composites

    Fareed, Ali [Honeywell Advanced Composites Inc. (HACI), Newark, DE (United States); Craig, Phillip A. [Honeywell Advanced Composites Inc. (HACI), Newark, DE (United States)

    2002-09-01

    Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.

  10. Piezo-electrostrictive ceramics

    Kim, Ho Gi; Shin, Byeong Cheol

    1991-09-01

    This book deals with principle and the case of application of piezo-electrostrictive ceramics, which includes definition of piezoelectric materials and production and development of piezoelectric materials, coexistence of Pb(zr, Ti)O 3 ceramics on cause of coexistence in MPB PZT ceramics, electrostrictive effect of oxide type perovskite, practical piezo-electrostrictive materials, and breaking strength, evaluation technique of piezoelectric characteristic, and piezoelectric accelerometer sensor like printer head, ink jet and piezoelectric relay.

  11. Method of sintering ceramic materials

    Holcombe, Cressie E.; Dykes, Norman L.

    1992-01-01

    A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density.

  12. Defect production in ceramics

    Zinkle, S.J. [Oak Ridge National Lab., TN (United States); Kinoshita, C. [Kyushu Univ. (Japan)

    1997-08-01

    A review is given of several important defect production and accumulation parameters for irradiated ceramics. Materials covered in this review include alumina, magnesia, spinel silicon carbide, silicon nitride, aluminum nitride and diamond. Whereas threshold displacement energies for many ceramics are known within a reasonable level of uncertainty (with notable exceptions being AIN and Si{sub 3}N{sub 4}), relatively little information exists on the equally important parameters of surviving defect fraction (defect production efficiency) and point defect migration energies for most ceramics. Very little fundamental displacement damage information is available for nitride ceramics. The role of subthreshold irradiation on defect migration and microstructural evolution is also briefly discussed.

  13. Ceramic piezoelectric materials

    Kaszuwara, W.

    2004-01-01

    Ceramic piezoelectric materials conert reversibility electric energy into mechanical energy. In the presence of electric field piezoelectric materials exhibit deformations up to 0.15% (for single crystals up to 1.7%). The deformation energy is in the range of 10 2 - 10 3 J/m 3 and working frequency can reach 10 5 Hz. Ceramic piezoelectric materials find applications in many modern disciplines such as: automatics, micromanipulation, measuring techniques, medical diagnostics and many others. Among the variety of ceramic piezoelectric materials the most important appear to be ferroelectric materials such as lead zirconate titanate so called PZT ceramics. Ceramic piezoelectric materials can be processed by methods widely applied for standard ceramics, i.e. starting from simple precursors e.g. oxides. Application of sol-gel method has also been reported. Substantial drawback for many applications of piezoelectric ceramics is their brittleness, thus much effort is currently being put in the development of piezoelectric composite materials. Other important research directions in the field of ceramic piezoelectric materials composite development of lead free materials, which can exhibit properties similar to the PZT ceramics. Among other directions one has to state processing of single crystals and materials having texture or gradient structure. (author)

  14. Corrosion of Ceramic Materials

    Opila, Elizabeth J.; Jacobson, Nathan S.

    1999-01-01

    Non-oxide ceramics are promising materials for a range of high temperature applications. Selected current and future applications are listed. In all such applications, the ceramics are exposed to high temperature gases. Therefore it is critical to understand the response of these materials to their environment. The variables to be considered here include both the type of ceramic and the environment to which it is exposed. Non-oxide ceramics include borides, nitrides, and carbides. Most high temperature corrosion environments contain oxygen and hence the emphasis of this chapter will be on oxidation processes.

  15. Synthesis and evaluation of antimalarial activity of curcumin derivatives; Sintese e avaliacao da atividade antimalarica de compostos derivados da curcumina

    Gomes, Patricia Ramos; Miguel, Fabio Balbino; Almeida, Mauro Vieira de; Couri, Mara Rubia Costa [Universidade Federal de Juiz de Fora (UFSJ), MG (Brazil). Instituto de Ciencias Exatas. Departamento de Quimica; Oliveira, Michael Eder de; Ferreira, Vanessa Viana; Guimaraes, Daniel Silqueira Martins; Lima, Aline Brito de; Barbosa, Camila de Souza; Oliveira, Mariana Amorim de; Almeida, Mauro Vieira de; Viana, Gustavo Henrique Ribeiro; Varotti, Fernando de Pilla, E-mail: varotti@ufsj.edu.br [Universidade Federal de Sao Joao Del Rei (UFSJ), MG (Brazil). Centro de Ciencias da Saude; others, and

    2014-05-15

    ne of the main challenges in the development of new antimalarial drugs is to achieve a viable lead candidate with good pharmacokinetic properties. Curcumin has a broad range of biological activities, including antimalarial activity. Herein, we report the antimalarial activity of six curcumin derivatives (6-12) and an initial analysis of their pharmacokinetic properties. Five compounds have demonstrated potent activity against the P. falciparum in vitro (IC{sub 50} values ranging from 1.7 to 15.2 μg mL{sup -1}), with moderate or low cytotoxicity against the HeLa cell line. The substitution of the carbonyl group in 6 by a 2,4-dinitrophenylhydrazone group (to afford 11) increases the Selective Index. These preliminary results indicate curcumin derivatives as potential antimalarial compounds. (author)

  16. Evaluation of the numerical solution of polymer flooding; Avaliacao da solucao numerica da injecao de polimeros em reservatorios de petroleo

    Teixeira, Vinicius Ligiero; Pires, Adolfo Puime; Bedrikovetsky, Pavel G. [Universidade Estadual do Norte Fluminense (UENF), Macae, RJ (Brazil). Lab. de Engenharia e Exploracao do Petroleo (LENEP)

    2004-07-01

    Enhanced Oil Recovery (EOR) methods include injection of different fluids into reservoirs to improve oil displacement. The EOR methods may be classified into the following kinds: injection of chemical solutions, injection of solvents and thermal methods. The chemical fluids most commonly injected are polymers, surfactants, micellar solutions, etc. Displacement of oil by any of these fluids involves complex physico-chemical processes of interphase mass transfer, phase transitions and transport properties changes. These processes can be divided into two main categories: thermodynamical and hydrodynamical ones. They occur simultaneously during the displacement, and are coupled in the modern mathematical models of EOR. The model for one-dimensional displacement of oil by polymer solutions is analyzed in this paper. The Courant number is fixed, and we compare the results of different runs of a numerical simulator with the analytical solution of this problem. Each run corresponds to a different spatial discretization. (author)

  17. Tratabilidade de solos tropicais contaminados por resíduos da indústria de revestimentos cerâmicos Treatability of tropical soils contaminated by solid wastes from ceramic tile industry

    Luciana Pena de Oliveira

    2008-03-01

    Full Text Available Este trabalho de pesquisa buscou investigar a eficácia da remoção de chumbo (Pb e zinco (Zn de uma área contaminada pelo depósito inadequado de resíduos de indústrias de revestimentos cerâmicos do pólo de Santa Gertrudes (São Paulo, Brasil, ocorrido há cerca de trinta anos atrás. Foram avaliados três processos de lixiviação: lavagem com ácido sulfúrico concentrado e por soluções de peróxido de hidrogênio a 30% e de ácido clorídrico 0,1 M. Os resultados obtidos mostraram que o tratamento com peróxido de hidrogênio não removeu Pb e Zn; que a lavagem com ácido sulfúrico concentrado promoveu a redução de 50% dos teores de Zn e a solução de ácido clorídrico 0,1 M reduziu os teores de Pb e Zn em 15% e 10%, respectivamente. O teor remanescente de Zn no solo tratado com ácido sulfúrico concentrado foi de 117 mg/kg e os de Pb e Zn no solo lavado com a solução de ácido clorídrico 0,1 M, de 806 mg/kg e 213 mg/kg, respectivamente, valores estes inferiores aos de intervenção estabelecidos pelo órgão de controle ambiental paulista.The aim of this research was to evaluate different leaching processes to the removal of lead (Pb and zinc (Zn from tropical soil contaminated by inappropriate past deposition of wastes from ceramic tile industries of Santa Gertrudes (São Paulo, Brazil. Three soil washing processes were investigated: with concentrated sulphuric acid, with a 30% solution of hydrogen peroxide and with 0.1M solution of hydrochloric acid. The results indicated that the treatment with hydrogen peroxide did not remove Pb and Zn significantly; the washing with concentrated sulphuric acid caused a 50% reduction of Zn contents and the 0.1M solution of hydrochloric acid reduced Pb and Zn contents in 15% and 10%, respectively. The Zn content remaining in the soil processed with concentrated sulphuric acid was 117 mg/kg and the Pb and Zn contents remaining in the soil processed with 0.1M solution of hydrochloric acid

  18. Ceramic Technology Project

    1992-03-01

    The Ceramic Technology Project was developed by the USDOE Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the USDOE and NASA advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. These programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. A five-year project plan was developed with extensive input from private industry. In July 1990 the original plan was updated through the estimated completion of development in 1993. The objective is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. To facilitate the rapid transfer of this technology to US industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities.

  19. New ceramic materials

    Moreno, R.; Dominguez-Rodriguez, A.

    2010-01-01

    This article is to provide a new ceramic materials in which, with a control of their processing and thus their microstructural properties, you can get ceramic approaching ever closer to a metal, both in its structural behavior at low as at high temperatures. (Author) 30 refs.

  20. Mounting for ceramic scroll

    Petty, Jack D.

    1993-01-01

    A mounting for a ceramic scroll on a metal engine block of a gas turbine engine includes a first ceramic ring and a pair of cross key connections between the first ceramic ring, the ceramic scroll, and the engine block. The cross key connections support the scroll on the engine block independent of relative radial thermal growth and for bodily movement toward an annular mounting shoulder on the engine. The scroll has an uninterrupted annular shoulder facing the mounting shoulder on the engine block. A second ceramic ring is captured between mounting shoulder and the uninterrupted shoulder on the scroll when the latter is bodily shifted toward the mouting shoulder to define a gas seal between the scroll and the engine block.

  1. Ceramic heat exchanger

    LaHaye, Paul G.; Rahman, Faress H.; Lebeau, Thomas P. E.; Severin, Barbara K.

    1998-01-01

    A tube containment system. The tube containment system does not significantly reduce heat transfer through the tube wall. The contained tube is internally pressurized, and is formed from a ceramic material having high strength, high thermal conductivity, and good thermal shock resistance. The tube containment system includes at least one ceramic fiber braid material disposed about the internally pressurized tube. The material is disposed about the tube in a predetermined axial spacing arrangement. The ceramic fiber braid is present in an amount sufficient to contain the tube if the tube becomes fractured. The tube containment system can also include a plurality of ceramic ring-shaped structures, in contact with the outer surface of the tube, and positioned between the tube and the ceramic fiber braid material, and/or at least one transducer positioned within tube for reducing the internal volume and, therefore, the energy of any shrapnel resulting from a tube fracture.

  2. Utilização do subproduto da recuperação metálica de escórias de aços inoxidáveis na síntese de pigmentos cerâmicos; caracterização da matéria-prima By-product utilization of metallic recovering of stainless steel slags in the ceramic pigments synthesis; raw material characterization

    V. P. Della

    2005-06-01

    Full Text Available O processo de recuperação metálica em escórias de aciaria - resíduo gerado em grande quantidade no processo de refino do ferro-gusa para obtenção do aço - que visa a recuperação de metais nobres, gera uma massa de óxidos que pode ser utilizada como fonte precursora na síntese do pigmento cerâmico verde vitória. Verde vitória é o nome dado ao pigmento cerâmico à base de cálcio, cromo e silício (Ca3Cr2Si3O12 que a elevadas temperaturas desenvolve a estrutura cristalina uvarovita responsável pela estabilização da cor verde característica. Este subproduto apresenta características constitucionais favoráveis à obtenção deste pigmento mediante o ajuste da composição química através da adição de óxidos puros. A combinação de técnicas de análise microestrutural, térmica e química foi utilizada nesta caracterização inicial.The metallic recovering process of steel industry slags - waste produced in a big amount by the process of pig iron refining for steel obtainment, which aims the recovering of noble metals, produces a oxide mass that can be used as a precursor source for the synthesis of the Victory Green ceramic pigment. Victory Green is the name of the ceramic pigment based on calcium, chromium and silicon (Ca3Cr2Si3O12 , and that develops the uvarovite crystalline structure in high temperatures, responsible for the stabilization of characteristic green color. This by-product presents favorable constitutional characteristics to the obtainment of this pigment by adjusting the chemical composition through additions of pure oxides. The combination of techniques of microstructural, thermal and chemical analysis was used in this initial characterization.

  3. Characterization of solid wastes from kraft pulp industry for ceramic materials development purposes; Caracterizacao de residuos solidos da industria de celulose tipo kraft visando sua aplicacao no desenvolvimento de materiais ceramicos

    Rodrigues, L.R.; Francisco, M.A.C.O.; Sagrillo, V.P.D.; Louzada, D.M.; Entringer, J.M.S. [Instituto Federal do Espirito Santo (IFES), Vitoria, ES (Brazil)

    2016-07-01

    The Kraft pulp industry generates a large amount of solid wastes. Due this large quantity, the target of this study is characterize inorganic solid wastes, dregs, grits and lime mud, from the step of reagents recovery of Kraft process, aiming evaluate the potentiality of their use as alternative raw material on development of ceramic materials. Initially, the wastes were dried and ground, then they were subjected to the following characterization techniques: pH analysis, particle size analysis, X ray fluorescence, X ray diffraction, differential thermal analysis and thermogravimetric analysis and scanning electron microscopy. According to the results, it may be concluded that these wastes could be used as raw material in production of red ceramic and luting materials. (author)

  4. Study on the potential of water/oil of tubular alumina ceramics through flux and turbidity analysis; Estudo do potencial de separacao agua/oleo de membranas ceramicas tubulares de alumina atraves da analise das medidas de fluxo e turbidez

    Silva, A.A; Melo, K.S. [Universidade Federal, Campina Grande, PB (Brazil)]. E-mail: adrianasilva_cg@yahoo.com.br; Maia, J.B.N.; Franca, R.V.; Silva, R.A.V.; Lira, H.L.; Carvalho, L.H. [Universidade Federal, Campina Grande, PB (Brazil). Dept. de Engenharia de Materiais]. E-mail: helio@dema.ufpb.br; Franca, K.B.; Rodrigues, M.G.F [Universidade Federal, Campina Grande, PB (Brazil). Dept. de Engenharia Quimica]. E-mail: kepler@labdes.ufpb.br

    2003-07-01

    In the last years, a considerable attention was given to the effluents composed by contaminated water with oil and the impact on the environment . The water pollution by oleaginous hydrocarbon is specially harmful to the aquatic life, decreasing the transmission of light and disturb the normal mechanism of oxygen transfer. So, to remove oil from water is an important aspect to control the pollution from several industries. The ceramic membranes act as a barrier for the emulsified oil. It has been studied enough as a medium to separate oil/ water from stable emulsions. The objective of this work is to present an evaluation of the separation potential of a tubular alumina ceramic membrane made in laboratory from Materials Engineering Department, Federal University of Campina Grande (UFCG). It was done test of flux and concentration of oil the permeate. The results showed that the membranes can be satisfactorily used in the oil/water separation. (author)

  5. Effect of the addition of expanded vermiculite in the technological properties of ceramic materials of clay base; Efeito da adicao de vermiculita expandida nas propriedades tecnologicas de materiais Ceramicos de base argilosa

    Lins, R.R.F.; Peixoto, R.S. Dutra; Macedo, D.A.; Nascimento, R.M.; Oliveira, G.V.M., E-mail: rivaldoeng.m@gmail.com [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais; Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2016-07-01

    This paper discusses the effects of adding expanded vermiculite ceramic block made from two different types of clay and analysis of the properties for three compositions at different sintering temperatures. Samples pressed at 40 MPa were sintered between 800 and 1100 ° C. The technological properties were determined according to the sintering temperature. The evaluation of the crystalline phases and microstructure was carried out by X-ray diffraction results indicated that with the addition of expanded vermiculite in the specimens there was an increase in porosity of the blocks together with the water absorption, therefore a reduction in apparent density, as well as the breakdown voltage of the three-point bending. This study demonstrates the possibility of formulating ceramic blocs order to improve the insulating properties of these materials. (author)

  6. Comparison among the mineralogic characteristics of Corumbatai formation and a mass for via humidity ceramic coating; Comparacao das caracteristicas mineralogicas da formacao Corumbatai com uma massa para revestimentos ceramicos via umida

    Rocha, R R; Zanardo, A; Moreno, M M.T., [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), SP (Brazil). Dept. de Petrologia e Metalogenia; Souza, E M [Colorminas Colorificio e Mineracao S.A., Icara, SC (Brazil)

    2009-07-01

    The mineralogy of the raw materials used in the production of ceramic tiles is a matter of great importance considering the constant necessity of finding alternatives to reduce costs and to improve the product quality. The ceramic industry of Santa Gertrudes could see a dramatic growth due to reasons that include the natural characteristics of the raw materials found in the region which are suitable for the production of ceramic tiles through the dry grinding process. In order to understand the ease of use of such clays which are sedimentary rocks of Corumbatai Formation, their plastic components made up primarily of clay minerals such as illite and smectite, and non-plastic components, including quartz (inert), feldspars (fluxe) and some contaminants, were identified with the use of X-ray diffraction. When comparing the properties of the formulation made with clays from Corumbatai Formation with that made with raw materials for the wet process, it was possible to note the ease of use and the relative characteristics of both processes. (author)

  7. Study of ceramics from circular archaeological sites of Amazonic Basin by geochemical methods: dating and characterization; Estudo de ceramicas de sitios arqueologicos circulares da Bacia Amazonica por meio de metodos geoquimicos: datacao e caracterizacao

    Nicoli, Ieda Gomes

    2000-09-01

    The aim of this work is to examine by means of characterization and dating pottery recently discovery inside archaeological sites recognized with circular earth structure in Acre State - Brazil which may contribute to the research in the reconstruction of part of the pre-history of the Amazonic Basin. These sites are located mainly in the Hydrographic Basin of High Purus River. Three of them were strategic chosen which provide the ceramics: Lobao, in Sena Madureira County at north; Alto Alegre, in Rio Branco County at east and Xipamanu I, in Xapuri County at south. The X-ray diffraction mineral analysis made possible to identify two types of crystal structures of ceramic minerals: quartz and M-Kaolinite. Neutron activation analysis in conjunction with multivariate statistical methods were applied for the ceramic characterization and classification. An homogeneous group was established by all sherds collected from Alto Alegre and was distinct from all the other two groups analyzed. Some of the sherds collected from Xipamanu I appeared in Lobao's urns, probably because they had the same fabrication process. The Lobao's urns presented a homogeneous group. Geochronology of these materials was carried out by Thermoluminescence. The Xipamanu I was the oldest site and Lobao the youngest. The average age of Xipamanu I and Alto Alegre were 2600 and 2070 years respectively. The average age of of occupation was 400 years to Alto Alegre and 970 years to Xipamanu I. The most probably date for Lobao was 1880 years. (author)

  8. Study of ceramics from circular archaeological sites of Amazonic Basin by geochemical methods: dating and characterization; Estudo de ceramicas de sitios arqueologicos circulares da Bacia Amazonica por meio de metodos geoquimicos: datacao e caracterizacao

    Nicoli, Ieda Gomes

    2000-09-01

    The aim of this work is to examine by means of characterization and dating pottery recently discovery inside archaeological sites recognized with circular earth structure in Acre State - Brazil which may contribute to the research in the reconstruction of part of the pre-history of the Amazonic Basin. These sites are located mainly in the Hydrographic Basin of High Purus River. Three of them were strategic chosen which provide the ceramics: Lobao, in Sena Madureira County at north; Alto Alegre, in Rio Branco County at east and Xipamanu I, in Xapuri County at south. The X-ray diffraction mineral analysis made possible to identify two types of crystal structures of ceramic minerals: quartz and M-Kaolinite. Neutron activation analysis in conjunction with multivariate statistical methods were applied for the ceramic characterization and classification. An homogeneous group was established by all sherds collected from Alto Alegre and was distinct from all the other two groups analyzed. Some of the sherds collected from Xipamanu I appeared in Lobao's urns, probably because they had the same fabrication process. The Lobao's urns presented a homogeneous group. Geochronology of these materials was carried out by Thermoluminescence. The Xipamanu I was the oldest site and Lobao the youngest. The average age of Xipamanu I and Alto Alegre were 2600 and 2070 years respectively. The average age of of occupation was 400 years to Alto Alegre and 970 years to Xipamanu I. The most probably date for Lobao was 1880 years. (author)

  9. Industrial ceramics - Properties, forming and applications

    Fantozzi, Gilbert; Niepce, Jean-Claude; Bonnefont, Guillaume; Alary, J.A.; Allard, B.; Ayral, A.; Bassat, J.M.; Elissalde, C.; Maglione, M.; Beauvy, M.; Bertrand, G.; Bignon, A.; Billieres, D.; Blanc, J.J.; Blumenfeld, P.; Bonnet, J.P.; Bougoin, M.; Bourgeon, M.; Boussuge, M.; Thorel, A.; Bruzek, C.E.; Cambier, F.; Carrerot, H.; Casabonne, J.M.; Chaix, J.M.; Chevalier, J.; Chopinet, M.H.; Couque, H.; Courtois, C.; Leriche, A.; Dhaler, D.; Denape, J.; Euzen, P.; Ganne, J.P.; Gauffinet, S.; Girard, A.; Gonon, M.; Guizard, C.; Hampshire, S.; Joulin, J.P.; Julbe, A.; Ferrato, M.; Fontaine, M.L.; Lebourgeois, R.; Lopez, J.; Maquet, M.; Marinel, S.; Marrony, M.; Martin, J.F.; Mougin, J.; Pailler, R.; Pate, M.; Petitpas, E.; Pijolat, C.; Pires-Franco, P.; Poirier, C.; Poirier, J.; Pourcel, F.; Potier, A.; Tulliani, J.M.; Viricelle, J.P.; Beauger, A.

    2013-01-01

    After a general introduction to ceramics (definition, general properties, elaboration, applications, market data), this book address conventional ceramics (elaboration, material types), thermo-structural ceramics (oxide based ceramics, non-oxide ceramics, fields of application, functional coatings), refractory ceramics, long fibre and ceramic matrix composites, carbonaceous materials, ceramics used for filtration, catalysis and the environment, ceramics for biomedical applications, ceramics for electronics and electrical engineering (for capacitors, magnetic, piezoelectric, dielectric ceramics, ceramics for hyper-frequency resonators), electrochemical ceramics, transparent ceramics (forming and sintering), glasses, mineral binders. The last chapter addresses ceramics used in the nuclear energy sector: in nuclear fuels and fissile material, absorbing ceramics and shields, in the management of nuclear wastes, new ceramics for reactors under construction or for future nuclear energy

  10. A indústria cerâmica vermelha de Campos dos Goitacazes e a inclusão social das artesãs da baixada campista através do projeto Caminhos de Barro The red ceramic industry in Campos dos Goitacazes and the social inclusion of artisans from Baixada Campista through the Caminhos de Barro project

    I. S. Ramos

    2008-09-01

    Full Text Available O Parque industrial de Campos dos Goytacazes é formado por mais de cem cerâmicas, absorvendo, segundo informações do próprio segmento, cerca de 5000 funcionários. Este tipo de trabalho, de um modo geral, emprega pessoas capazes de suportar serviços pesados, excluindo desta forma mulheres, idosos e portadores de deficiência. O Projeto Caminhos de Barro, implantado pela Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF, no ano de 2000, tem como finalidade capacitar, na arte cerâmica artesanal, essas comunidades excluídas do processo industrial de produção de tijolos e telhas. O presente trabalho tem como primícia contribuir para uma melhora na tecnologia adotada, pela primeira geração de artesãs formada na Oficina Caminhos de Barro, adequando a matéria prima utilizada à nova atividade através de mapeamento, classificação e caracterização dos materiais da região na forma in natura, ocupando-se, igualmente do seu comportamento após a queima. A mesma análise técnica utilizada para caracterização e adequação dos produtos industrializados pelas industrias cerâmicas mostrou-se também adequada para o artesanato. A matéria prima estudada, em principio, apresentou as qualidades necessárias ao trabalho artesanal como pode ser observado pelos produtos obtidos levando a um menor grau de perda. Porém a criação de um padrão mais adequado de matéria prima a ser utilizado na arte cerâmica da baixada campista demandará, portanto, mais tempo, recursos e estudo, pois as propriedades desejadas de cada artefato tais como: cor, permeabilidade e acabamento podem estar associados a pequenas variações físicas e mineralógicas.The industrial park of the Campos dos Goytacazes is formed for more than one hundred ceramics, absorbing, by mean information of the proper segment, about 5000 employees. This type of work in a general way uses capable person to support heavy services excluding: women, deficient and old person

  11. Efeito da adição de lodo de estação de tratamento de água (ETA nas propriedades de material cerâmico estrutural Effect of the addition of sludge from water treatment plants on the properties of structural ceramic material

    S. R. Teixeira

    2006-09-01

    Full Text Available O resíduo (lodo gerado nos decantadores das Estações de Tratamento de Água (ETA possui composição variada, de acordo com a região onde ela está localizada, com o mês de coleta e com o coagulante usado. Neste trabalho foram feitas caracterizações, física, química e mineralógica, deste lodo e ensaios tecnológicos em corpos de prova, com a finalidade de avaliar a possibilidade de incorporação deste resíduo em massa cerâmica para produção de tijolos. Retração linear, absorção de água, porosidade e massa específica aparente e ensaios de resistência à flexão em corpos-de-prova, com diferentes concentrações de lodo, foram avaliadas. Também, foi avaliado o efeito do tipo de floculante usado na ETA, sobre as propriedades dos corpos-de-prova. A análise mineralógica mostrou que estes lodos apresentaram composição parecida com as das argilas usadas pelas cerâmicas. Em geral, a adição destes materiais à massa cerâmica piorou suas propriedades, entretanto, os valores obtidos para as propriedades tecnológicas ainda permaneceram dentro dos valores limites aceitáveis para a produção de tijolos, dependendo da temperatura de queima e da concentração na mistura. O lodo obtido com floculante à base de alumínio, em geral, prejudicou mais as propriedades cerâmicas do que aqueles à base de ferro. Os resultados indicaram que o lodo de ETA pode ser incorporado à massa cerâmica para produzir material cerâmico.The residue (sludge produced in the decantation ponds of Water Treatment Plants (WTP has variable composition according to the regional WTP localization, the month of collection and the chemical used to flocculation. In this work the sludge was submitted to physical, chemical and mineralogical characterization. Also, technological trials were realized on ceramic probes to evaluate the possibility of sludge incorporation in ceramic mass used to produce bricks. Linear shrinkage, water absorption, mechanical

  12. Effect of thermocycling on the bond strength of a glass-infiltrated ceramic and a resin luting cement Efeito da ciclagem térmica sobre a resistência de união entre uma cerâmica infiltrada com vidro e um cimento resinoso

    Osvaldo Daniel Andreatta Filho

    2003-03-01

    Full Text Available The aim of the present study was to evaluate the effect of thermocycling on the bond strength between the surface of the glass-infiltrated alumina ceramic In-Ceram (VITA and the Panavia F resin cement (Kuraray CO.. Four 5x6x6mm In-Ceram blocks were obtained. One of the 6x6mm faces of each block was conditioned with Cojet - System (tribochemical silica coating, ESPE-3M and then luted under a constant 750g pressure with Panavia F cement to another identical face of a resin composit block (Clearfil AP-X, Kuraray obtained by reproduction of the ceramic one from Express (3M addition curing silicone impressions. The four sets so formed by ceramic, luting cement and resin have been each one serially sectioned in 20 sticks so that the adhesive surface in each presented 1mm² of area. The samples were divided in 2 groups (n=10: G1- stored for 7 days in deionized water at 36 ± 2ºC; G2 - thermocycled 1500 times between 5 and 55ºC dwell times. The microtensile tests were accomplished in an universal testing machine (EMIC at a crosshead speed of 0,5 mm/min. The results showed that the mean tensile bond strength values (MPa for the group G2: (22,815 ± 5,254 had not statistically differ of the values of group G1: (25,628 ± 3,353 (t = 1,427; gl = 18; p-value = 0,171, at the level of a= 5%. It can be concluded that the thermocycling technique used in the present experiment had not produced statistically significant differences between the bond strength results of the specimens obtained by the two used techniques.O objetivo deste estudo foi avaliar o efeito da ciclagem térmica sobre a resistência de adesão entre a superfície da cerâmica In-Ceram Alumina (VITA e o cimento resinoso Panavia F (Kuraray. Foram confeccionados quatro blocos de cerâmica In-Ceram com dimensões de 5x6x6mm. Uma das faces com 6x6mm de cada bloco cerâmico, após condicionamento com o sistema Cojet (ESPE-3M (jateamento com óxido de alumínio/jateamento com óxido de s

  13. Ceramic breeder materials

    Johnson, C.E.

    1990-01-01

    The breeding blanket is a key component of the fusion reactor because it directly involves tritium breeding and energy extraction, both of which are critical to development of fusion power. The lithium ceramics continue to show promise as candidate breeder materials. This promise was recognized by the International Thermonuclear Reactor (ITER) design team in its selection of ceramics as the first option for the ITER breeder material. Blanket design studies have indicated properties in the candidate materials data base that need further investigation. Current studies are focusing on tritium release behavior at high burnup, changes in thermophysical properties with burnup, compatibility between the ceramic breeder and beryllium multiplier, and phase changes with burnup. Laboratory and in-reactor tests, some as part of an international collaboration for development of ceramic breeder materials, are underway. 32 refs., 1 fig., 1 tab

  14. Corrosion resistant ceramic materials

    Kaun, T.D.

    1996-07-23

    Ceramic materials are disclosed which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200--550 C or organic salt (including SO{sub 2} and SO{sub 2}Cl{sub 2}) at temperatures of 25--200 C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components. 1 fig.

  15. Ceramic injection molding

    Agueda, Horacio; Russo, Diego

    1988-01-01

    Interest in making complex net-shape ceramic parts with good surface finishing and sharp tolerances without machining is a driving force for studying the injection molding technique. This method consists of softhening the ceramic material by means of adding some plastic and heating in order to inject the mixture under pressure into a relatively cold mold where solidification takes place. Essentially, it is the same process used in thermoplastic industry but, in the present case, the ceramic powder load ranges between 80 to 90 wt.%. This work shows results obtained from the fabrication of pieces of different ceramic materials (alumina, barium titanate ferrites, etc.) in a small scale, using equipments developed and constructed in the laboratory. (Author) [es

  16. Applications of Piezoelectric Ceramics

    Applications of Piezoelectric Ceramics. Piezoelectric Actuators. Nano and Micropositioners. Vibration Control Systems. Computer Printers. Piezoelectric Transformers,Voltage Generators, Spark Plugs, Ultrasonic Motors,. Ultrasonic Generators and Sensors. Sonars, Medical Diagnostic. Computer Memories. NVFRAM ...

  17. Corrosion resistant ceramic materials

    Kaun, Thomas D.

    1996-01-01

    Ceramic materials which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  18. Making Ceramic Cameras

    Squibb, Matt

    2009-01-01

    This article describes how to make a clay camera. This idea of creating functional cameras from clay allows students to experience ceramics, photography, and painting all in one unit. (Contains 1 resource and 3 online resources.)

  19. Selecting Ceramics - Introduction

    Cassidy, M.

    2002-01-01

    AIM OF PRESENTATION: To compare a number of materials for extracoronal restoration of teeth with particular reference to CAD-CAM ceramics. CASE DESCRIPTION AND TREATMENT CARRIED OUT: This paper will be illustrated using clinical examples of patients treated using different ceramic restorations to present the advantages and disadvantages and each technique. The different requirements of tooth preparation, impression taking and technical procedures of each system will be presented and compar...

  20. Cavitation damage of ceramics

    Kovalenko, V.I.; Marinin, V.G.

    1988-01-01

    Consideration is given to results of investigation of ceramic material damage under the effect of cavitation field on their surface, formed in water under the face of exponential concentrator, connected with ultrasonic generator UZY-3-0.4. Amplitude of vibrations of concentrator face (30+-2)x10 -6 m, frequency-21 kHz. It was established that ceramics resistance to cavitation effect correlated with the product of critical of stress intensity factor and material hardness

  1. Utilização do planejamento experimental na incorporação do resíduo da indústria cerâmica em argamassas para obtenção da capacidade de retenção de água Use of the experimental design in the incorporation of the ceramic waste in mortars for obtaining water retention capacity

    A. V. Bahiense

    2008-12-01

    Full Text Available O município de Campos dos Goytacazes, RJ, possui um pólo cerâmico com mais de 100 indústrias cerâmicas e uma produção mensal estimada de 90 milhões de peças compreendidas entre lajotas, blocos e telhas. Muitos desses artefatos acabam gerando resíduos e impactos ambientais na região devido às falhas no processo produtivo e logístico das indústrias. Este trabalho propõe a incorporação do resíduo cerâmico em argamassas, avaliando as diversas proporções dos constituintes por meio do planejamento de experimentos em rede simplex buscando soluções técnicas, sem o tradicional empirismo existente na indústria, com o objetivo de alcançar um desempenho satisfatório da propriedade analisada, capacidade de retenção de água e, sem dúvida, favorecendo o desenvolvimento sustentável. O procedimento experimental foi baseado nas normas ABNT 13276, 13277 e 13281. A partir destes ensaios foram tomados dez pontos experimentais cujos teores máximos de cimento, areia e resíduo cerâmico são 20, 80 e 20% em massa, respectivamente, que delimitou a superfície de resposta para as argamassas de índice de consistência 265±30 mm. Este índice mostrou-se mais próximo da aplicação real para o modelo estatístico, porém, pouco acima do valor normalizado. O modelo em rede simplex cúbico especial mostrou melhor ajuste aos resultados experimentais, estimando respostas estatisticamente mais adequadas para as misturas. A superfície de resposta gerada apresentou capacidade de retenção de água da argamassa de 88 a 94,5%, classificando-a como normal e alta, segundo a norma ABNT 13281. Mesmo com valor superior ao índice de consistência padrão (valor acima do estabelecido por norma conseguiu-se uma capacidade de retenção padronizada com adição de resíduo na argamassa.The district of the Campos dos Goytacazes, RJ, Brazil, has a ceramic pole with more than 100 ceramic industries, with a 90 million monthly production (brick masonry

  2. Large ceramics for fusion applications

    Hauth, W.E.; Stoddard, S.D.

    1979-01-01

    Prominent ceramic raw materials and products manufacturers were surveyed to determine the state of the art for alumina ceramic fabrication. This survey emphasized current capabilities and limitations for fabrication of large, high-density, high-purity, complex shapes. Some directions are suggested for future needs and development. Ceramic-to-ceramic sealing has applications for several technologies that require large and/or complex vacuum-tight ceramic shapes. Information is provided concerning the assembly of complex monolithic ceramic shapes by bonding of subassemblies at temperatures ranging from 450 to 1500 0 C. Future applications and fabrication techniques for various materials are presented

  3. Clinical application of bio ceramics

    Anu, Sharma, E-mail: issaranu@gmail.com; Gayatri, Sharma, E-mail: sharmagayatri@gmail.com [Department of Chemistry, Govt. College of Engineering & Technology, Bikaner, Rajasthan (India)

    2016-05-06

    Ceramics are the inorganic crystalline material. These are used in various field such as biomedical, electrical, electronics, aerospace, automotive and optical etc. Bio ceramics are the one of the most active areas of research. Bio ceramics are the ceramics which are biocompatible. The unique properties of bio ceramics make them an attractive option for medical applications and offer some potential advantages over other materials. During the past three decades, a number of major advances have been made in the field of bio ceramics. This review focuses on the use of these materials in variety of clinical scenarios.

  4. The history of ceramic filters.

    Fujishima, S

    2000-01-01

    The history of ceramic filters is surveyed. Included is the history of piezoelectric ceramics. Ceramic filters were developed using technology similar to that of quartz crystal and electro-mechanical filters. However, the key to this development involved the theoretical analysis of vibration modes and material improvements of piezoelectric ceramics. The primary application of ceramic filters has been for consumer-market use. Accordingly, a major emphasis has involved mass production technology, leading to low-priced devices. A typical ceramic filter includes monolithic resonators and capacitors packaged in unique configurations.

  5. Clinical application of bio ceramics

    Anu, Sharma; Gayatri, Sharma

    2016-01-01

    Ceramics are the inorganic crystalline material. These are used in various field such as biomedical, electrical, electronics, aerospace, automotive and optical etc. Bio ceramics are the one of the most active areas of research. Bio ceramics are the ceramics which are biocompatible. The unique properties of bio ceramics make them an attractive option for medical applications and offer some potential advantages over other materials. During the past three decades, a number of major advances have been made in the field of bio ceramics. This review focuses on the use of these materials in variety of clinical scenarios.

  6. Evaluation of the thermoluminescent detector answers of CaSO{sub 4}:Dy, LiF:Mg,Ti and micro LiF:Mg,Ti in photon clinical beams dosimetry using water simulator; Avaliacao da resposta de detectores termoluminescentes de CaSO4:Dy, LiF:Mg,Ti e microLiF:Mg,Ti na dosimetria de feixes clinicos de fotons utilizando simulador de agua

    Matsushima, Luciana C.; Veneziani, Glauco R.; Campos, Leticia L., E-mail: lmatsushima@usp.b, E-mail: veneziani@ipen.b, E-mail: lcrodri@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (GMR/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Gerencia de Metrologia das Radiacoes; Sakuraba, Roberto K.; Cruz, Jose C. da, E-mail: rsakuraba@einstein.b, E-mail: jccruz@einstein.b [Sociedade Beneficente Israelita Brasileira, Sao Paulo, SP (Brazil). Hospital Albert Einstein (HAE)

    2011-10-26

    This paper perform the comparative study of thermoluminescent answer of calcium sulfate dosemeter doped with dysprosium (DaSO{sub 4}:Dy) produced by the IPEN, Sao Paulo, with answer of lithium fluoride dosemeters doped with magnesium and titanium (LiF:Mg, Ti) in the dosimetry of clinical beams of photons (6 and 15 MV) by using water simulator object. Dose-answer curves were obtained for gamma radiation of cobalt-60 in the air and in conditions of electronic equilibrium (plate of PMMA), and clinical photons of CLINAC model 2100C accelerators of the two evaluated hospitals: Hospital das Clinicas of the Faculty of Medicine of Sao Paulo university and Hospital Albert Einstein. It was also evaluated the sensitivity and reproduction of the three dosemeters

  7. Surface modification of ceramics. Ceramics no hyomen kaishitsu

    Hioki, T. (Toyota Central Research and Development Labs., Inc., Nagoya (Japan))

    1993-07-05

    Surface modification of ceramics and some study results using in implantation in surface modification are introduced. The mechanical properties (strength, fracture toughness, flaw resistance) of ceramics was improved and crack was repaired using surface modification by ion implantation. It is predicted that friction and wear properties are considerably affected because the hardness of ceramics is changed by ion implantation. Cementing and metalization are effective as methods for interface modification and the improvement of the adhesion power of the interface between metal and ceramic is their example. It was revealed that the improvement of mechanical properties of ceramics was achieved if appropriate surface modification was carried out. The market of ceramics mechanical parts is still small, therefore, the present situation is that the field of activities for surface modification of ceramics is also narrow. However, it is thought that in future, ceramics use may be promoted surely in the field like medicine and mechatronics. 8 refs., 4 figs.

  8. Physicochemical characterization of ceramics from Sao Paulo II archaeological site

    Ribeiro, Rogerio Baria

    2013-01-01

    Archaeometry is a consolidated field with a wide application of nuclear analytical techniques for the characterization, protection, and restoration of archaeological pieces. This project aimed at studying the elementary chemical composition of 70 ceramic fragments samples from Sao Paulo II archaeological site, located along the Solimoes River channel, next to Coari city, in Brazilian Amazon. The characterization of samples was performed by neutron activation analysis (NAA). By the determination of 24 elements in the ceramic fragments ( Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Sb, Sm. Rb, Se, Ta, Tb, Th, U, Yb and Zn), it was possible to define groups of samples regarding the similarity/dissimilarity in elementary chemical composition. For such a task, the multivariate statistical methods employed were cluster analysis (C A), principal component analysis (PCA) and discriminant analysis (DA). Afterwards, seven ceramic fragments were selected based on the groups previously established, for the characterization of the site temporal horizon. Those ceramic fragments were analyzed by thermoluminescence (TL) and EPR for dating purposes. The firing temperatures were determined by electron paramagnetic resonance (EPR) technique, in order to infer about some aspects of the ceramic manufacture employed by the ancient peoples that lived in Sao Paulo 11. By the results obtained in this study, it was possible to identify the quantity of clay sources employed by the ceramists and the age of the ceramic pieces. Therefore, the results of this research may contribute to the study on the occupation dynamics in the pre-colonial Brazilian Amazon. (author)

  9. [Ceramic-on-ceramic bearings in total hip arthroplasty (THA)].

    Sentürk, U; Perka, C

    2015-04-01

    The main reason for total hip arthroplasty (THA) revision is the wear-related aseptic loosening. Younger and active patients after total joint replacement create high demands, in particular, on the bearings. The progress, especially for alumina ceramic-on-ceramic bearings and mixed ceramics have solved many problems of the past and lead to good in vitro results. Modern ceramics (alumina or mixed ceramics containing alumina) are extremely hard, scratch-resistant, biocompatible, offer a low coefficient of friction, superior lubrication and have the lowest wear rates in comparison to all other bearings in THA. The disadvantage of ceramic is the risk of material failure, i.e., of ceramic fracture. The new generation of mixed ceramics (delta ceramic), has reduced the risk of head fractures to 0.03-0.05 %, but the risk for liner fractures remains unchanged at about 0.02 %. Assuming a non-impinging component implantation, ceramic-on-ceramic bearings have substantial advantages over all other bearings in THA. Due to the superior hardness, ceramic bearings produce less third body wear and are virtually impervious to damage from instruments during the implantation process. A specific complication for ceramic-on-ceramic bearings is "squeaking". The high rate of reported squeaking (0.45 to 10.7 %) highlights the importance of precise implant positioning and the stem and patient selection. With precise implant positioning this problem is rare with many implant designs and without clinical relevance. The improved tribology and the presumable resulting implant longevity make ceramic-on-ceramic the bearing of choice for young and active patients. Georg Thieme Verlag KG Stuttgart · New York.

  10. Effects of the presence of heavy rare earths on the stabilization of the zirconia ceramics - Yttria; Efeito da presenca de terras raras pesadas na estabilizacao das fases de ceramicas de zirconia - itria

    Lazar, D.R.R.; Fancio, E.; Menezes, C.A.B.; Ussui, V.; Bressiani, A.H.A.; Lima, N.B.; Paschoal, J.O.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: drlazar@net.ipen.br

    2000-07-01

    The use of Yttria concentrates has been proposed to substitute the high purity Yttria in the zirconia stabilization. The elements terbium, dysprosium, holmium, erbium and ytterbium, classified as heavy rare earths, are the main impurities in these concentrates, due to their presence in yttrium ores. Besides that, the chemical similarities of these elements need the utilization of complex purification techniques. Considering the importance of the employed dopant on zirconia crystallization, this work shows the quantitative phases analysis of powders and ceramics of stabilized zirconia doped with 3 and 9 mol % of high purity Yttria and with a 85 wt % Yttria concentrate. This determination was performed using the Rietveld refinement of the X-ray diffraction data. The powders were synthesized by the hydroxides coprecipitation route, which includes treatments with ethanol and butanol, drying, calcination at 800 deg C for 1 hour and milling in a ball mill and in an attrition mill. The ceramics pellets were pressed uniaxially and sintered at 1550 deg C for 1 hour. The powders and sintered pellets were also characterized by X-ray fluorescence analysis, laser diffraction, gas adsorption (B.E.T.), scanning electron microscopy and determination of apparent density by the Archimedes method. The results showed the same stabilization behavior when it was employed high purity Yttria and a concentrate of this oxide. It was also observed the predominating formation of tetragonal and cubic phases when the dopant concentration is 3 and 9 mol %, respectively. (author)

  11. Testing method for ceramic armour and bare ceramic tiles

    Carton, E.P.; Roebroeks, G.H.J.J.

    2016-01-01

    TNO developed an alternative, more configuration independent ceramic test method than the Depth-of-Penetration test method. In this alternative test ceramic tiles and ceramic based armour are evaluated as target without a semi-infinite backing layer. An energy approach is chosen to evaluate and rank

  12. Testing method for ceramic armor and bare ceramic tiles

    Carton, E.P.; Roebroeks, G.H.J.J.

    2014-01-01

    TNO has developed an alternative, more configuration independent ceramic test method than the standard Depth-of-Penetration test method. In this test ceramic tiles and ceramic based armor are evaluated as target without a semi-infinite backing layer. An energy approach is chosen to evaluate and rank

  13. Mechanical properties of ceramics

    Pelleg, Joshua

    2014-01-01

    This book discusses the mechanical properties of ceramics and aims to provide both a solid background for undergraduate students, as well as serving as a text to bring practicing engineers up to date with the latest developments in this topic so they can use and apply these to their actual engineering work.  Generally, ceramics are made by moistening a mixture of clays, casting it into desired shapes and then firing it to a high temperature, a process known as 'vitrification'. The relatively late development of metallurgy was contingent on the availability of ceramics and the know-how to mold them into the appropriate forms. Because of the characteristics of ceramics, they offer great advantages over metals in specific applications in which hardness, wear resistance and chemical stability at high temperatures are essential. Clearly, modern ceramics manufacturing has come a long way from the early clay-processing fabrication method, and the last two decades have seen the development of sophisticated technique...

  14. Fatigue of dental ceramics.

    Zhang, Yu; Sailer, Irena; Lawn, Brian R

    2013-12-01

    Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Ceramic combustor mounting

    Hoffman, Melvin G.; Janneck, Frank W.

    1982-01-01

    A combustor for a gas turbine engine includes a metal engine block including a wall portion defining a housing for a combustor having ceramic liner components. A ceramic outlet duct is supported by a compliant seal on the metal block and a reaction chamber liner is stacked thereon and partly closed at one end by a ceramic bypass swirl plate which is spring loaded by a plurality of circumferentially spaced, spring loaded guide rods and wherein each of the guide rods has one end thereof directed exteriorly of a metal cover plate on the engine block to react against externally located biasing springs cooled by ambient air and wherein the rod spring support arrangement maintains the stacked ceramic components together so that a normal force is maintained on the seal between the outlet duct and the engine block under all operating conditions. The support arrangement also is operative to accommodate a substantial difference in thermal expansion between the ceramic liner components of the combustor and the metal material of the engine block.

  16. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-10-01

    This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  17. Ceramic impregnated superabrasives

    Radtke, Robert P.; Sherman, Andrew

    2009-02-10

    A superabrasive fracture resistant compact is formed by depositing successive layers of ceramic throughout the network of open pores in a thermally stable self-bonded polycrystalline diamond or cubic boron nitride preform. The void volume in the preform is from approximately 2 to 10 percent of the volume of the preform, and the average pore size is below approximately 3000 nanometers. The preform is evacuated and infiltrated under at least about 1500 pounds per square inch pressure with a liquid pre-ceramic polymerizable precursor. The precursor is infiltrated into the preform at or below the boiling point of the precursor. The precursor is polymerized into a solid phase material. The excess is removed from the outside of the preform, and the polymer is pyrolized to form a ceramic. The process is repeated at least once more so as to achieve upwards of 90 percent filling of the original void volume. When the remaining void volume drops below about 1 percent the physical properties of the compact, such as fracture resistance, improve substantially. Multiple infiltration cycles result in the deposition of sufficient ceramic to reduce the void volume to below 0.5 percent. The fracture resistance of the compacts in which the pores are lined with formed in situ ceramic is generally at least one and one-half times that of the starting preforms.

  18. Diffusion in ceramics

    Pelleg, Joshua

    2016-01-01

    This textbook provides an introduction to changes that occur in solids such as ceramics, mainly at high temperatures, which are diffusion controlled, as well as presenting research data. Such changes are related to the kinetics of various reactions such as precipitation, oxidation and phase transformations, but are also related to some mechanical changes, such as creep. The book is composed of two parts, beginning with a look at the basics of diffusion according to Fick's Laws. Solutions of Fick’s second law for constant D, diffusion in grain boundaries and dislocations are presented along with a look at the atomistic approach for the random motion of atoms. In the second part, the author discusses diffusion in several technologically important ceramics. The ceramics selected are monolithic single phase ones, including: A12O3, SiC, MgO, ZrO2 and Si3N4. Of these, three refer to oxide ceramics (alumina, magnesia and zirconia). Carbide based ceramics are represented by the technologically very important Si-ca...

  19. Fabrication and study of stability of Ca{sub 2}AlWO{sub 5,5} ceramic in crude petroleum for applications in petroleum industry; Fabricacao e estudo da estabilidade em petroleo cru da ceramica Ca{sub 2}AlWO{sub 5,5} para aplicacao em industria petrolifera

    Yadava, Y.P.; Silva, N.D.G.; Sousa, A.G. de; Sanguinetti Ferreira, R.A., E-mail: dea.a@hotmail.co [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Engenharia Mecanica

    2010-07-01

    Perovskite-type ceramic oxides or their derivatives are used for applications in high technology because of their enormous range of physic-chemical properties with little change in structural characteristics. In this paper we report manufacture ceramic components of a new ceramic Ca{sub 2}AlWO{sub 5,5} by thermo-mechanical process. Stoichiometric amounts of chemical constituents with high degree of purity, were homogenized using a ball mill and high purity alumina balls, compacted by uniaxial pressing and annealed at 1200 deg C for 48 hours. The structural characterization studied by x-ray diffraction that this material has a typical complex ordered cubic perovskite structure. For the study the stability of these ceramics in crude petroleum circular discs of 20 mm diameter and 2 mm thickness were produced and sintering. These discs were submerged in crude petroleum for 15, 30 and 45 days and were examined at each stage by X-ray diffraction, optical microscopy and hardness testing and these results show that Ca{sub 2}AlWO{sub 5,5} are stable in crude petroleum environment. (author)

  20. High flow ceramic pot filters

    van Halem, D.; van der Laan, H.; Soppe, A. I.A.; Heijman, S.G.J.

    2017-01-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more

  1. Ceramic composites: Enabling aerospace materials

    Levine, S. R.

    1992-01-01

    Ceramics and ceramic matrix composites (CMC) have the potential for significant impact on the performance of aerospace propulsion and power systems. In this paper, the potential benefits are discussed in broad qualitative terms and are illustrated by some specific application case studies. The key issues in need of resolution for the potential of ceramics to be realized are discussed.

  2. Verification of Ceramic Structures

    Behar-Lafenetre, Stephanie; Cornillon, Laurence; Rancurel, Michael; De Graaf, Dennis; Hartmann, Peter; Coe, Graham; Laine, Benoit

    2012-07-01

    In the framework of the “Mechanical Design and Verification Methodologies for Ceramic Structures” contract [1] awarded by ESA, Thales Alenia Space has investigated literature and practices in affiliated industries to propose a methodological guideline for verification of ceramic spacecraft and instrument structures. It has been written in order to be applicable to most types of ceramic or glass-ceramic materials - typically Cesic®, HBCesic®, Silicon Nitride, Silicon Carbide and ZERODUR®. The proposed guideline describes the activities to be performed at material level in order to cover all the specific aspects of ceramics (Weibull distribution, brittle behaviour, sub-critical crack growth). Elementary tests and their post-processing methods are described, and recommendations for optimization of the test plan are given in order to have a consistent database. The application of this method is shown on an example in a dedicated article [7]. Then the verification activities to be performed at system level are described. This includes classical verification activities based on relevant standard (ECSS Verification [4]), plus specific analytical, testing and inspection features. The analysis methodology takes into account the specific behaviour of ceramic materials, especially the statistical distribution of failures (Weibull) and the method to transfer it from elementary data to a full-scale structure. The demonstration of the efficiency of this method is described in a dedicated article [8]. The verification is completed by classical full-scale testing activities. Indications about proof testing, case of use and implementation are given and specific inspection and protection measures are described. These additional activities are necessary to ensure the required reliability. The aim of the guideline is to describe how to reach the same reliability level as for structures made of more classical materials (metals, composites).

  3. Characterization of residual soils of the region of Campos dos Goytacazes, RJ, Brazil, slip for use in artistic ceramics; Caracterizacao de solos residuais da regiao de Campos dos Goytacazes, RJ, Brazil, para uso de engobes em ceramica artistica

    Chrispim, Z.M.P.; Alves, M.G.; Ramos, I.S.; Silva, A.L., E-mail: zeliachrispim@terra.com.b [Universidade Estadual do Norte Fluminense Darcy Ribeiro (LECIV/CCT/UENF), Campos dos Goytacazes, RJ (Brazil). Engenharia Civil; Almeida, L.L.P. de [Universidade Estadual do Norte Fluminense Darcy Ribeiro (LAMAV/CCT/UENF), Campos dos Goytacazes, RJ (Brazil). Lab. de Materiais Avancados

    2010-07-01

    This work was conducted in the city of Campos dos Goytacazes/RJ, in which four residual soils collected in the region were technologically characterized. We sought to determine their properties, such as analysis of the colors after firing, aiming at its use in ceramic art. To this end the tests were conducted in the laboratories of the Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF) and that are granulometry (by sieving and sedimentation), specific mass of grains, chemical analysis by X-ray fluorescence, diffraction mineralogical identification X-ray, differential thermal analysis and thermogravimetry. The soils were analyzed before drying at 110 deg C and after burning the different temperatures (500 deg C 750 deg C and 950 deg C). The analyzed results showed the physical composition, chemical and mineralogical of raw material. After burning was possible to observe several color variations. (author)

  4. Cyclic mechanical fatigue in ceramic-ceramic composites: an update

    Lewis, D. III

    1983-01-01

    Attention is given to cyclic mechanical fatigue effects in a number of ceramics and ceramic composites, including several monolithic ceramics in which significant residual stresses should be present as a result of thermal expansion mismatches and anisotropy. Fatigue is also noted in several BN-containing ceramic matrix-particulate composites and in SiC fiber-ceramic matrix composites. These results suggest that fatigue testing is imperative for ceramics and ceramic composites that are to be used in applications subject to cyclic loading. Fatigue process models are proposed which provide a rationale for fatigue effect observations, but do not as yet provide quantitative results. Fiber composite fatigue damage models indicate that design stresses in these materials may have to be maintained below the level at which fiber pullout occurs

  5. Distorting the ceramic familiar: materiality and non-ceramic intervention, Conference, Keramik Museum, Germany

    Livingstone, Andrew

    2009-01-01

    Invited conference speaker, Westerwald Keramik Museum, August 2009. Paper title: Distorting the ceramic familiar: materiality and non-ceramic intervention.\\ud \\ud This paper will examine the integration of non-ceramic media into the discourse of ceramics.

  6. Piezoelectric displacement in ceramics

    Stewart, M.; Cain, M.; Gee, M.

    1999-01-01

    This Good Practice Guide is intended to aid a user to perform displacement measurements on piezoelectric ceramic materials such as PZT (lead zirconium titanate) in either monolithic or multilayer form. The various measurement issues that the user must consider are addressed, and good measurement practise is described for the four most suitable methods. (author)

  7. Dense ceramic articles

    Cockbain, A.G.

    1976-01-01

    A method is described for the manufacture of articles of substantially pure dense ceramic materials, for use in severe environments. Si N is very suitable for use in such environments, but suffers from the disadvantage that it is not amenable to sintering. Some disadvantages of the methods normally used for making articles of Si N are mentioned. The method described comprises mixing a powder of the substantially pure ceramic material with an additive that promotes densification, and which is capable of nuclear transmutation into a gas when exposed to radiation, and hot pressing the mixture to form a billet. The billet is then irradiated to convert the additive into a gas which is held captive in the billet, and it is then subjected to a hot forging operation, during which the captive gas escapes and an article of substantially pure dense ceramic material is forged. The method is intended primarily for use for Si N, but may be applied to other ceramic materials. The additive may be Li or Be or their compounds, to the extent of at least 5 ppm and not more than 5% by weight. Irradiation is effected by proton or neutron bombardment. (UK)

  8. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Dr. Sukumar Bandopadhyay; Dr. Nagendfra Nagabhushana

    2001-07-01

    The mechanical properties of model systems were analyzed. A reasonably accurate finite element model was implemented and a rational metric to predict the strength of ceramic/metal concentrical joints was developed. The mode of failure of the ceramic/metal joints was determined and the importance of the mechanical properties of the braze material was assessed. Thermal cycling experiments were performed on the model systems and the results were discussed. Additionally, experiments using the concept of placing diffusion barriers on the ceramic surface to limit the extent of the reaction with the braze were performed. It was also observed that the nature and morphology of the reaction zone depends greatly on the nature of the perovskite structure being used. From the experiments, it is observed that the presence of Cr in the Fe-occupied sites decreases the tendency of Fe to segregate and to precipitate out of the lattice. In these new experiments, Ni was observed to play a major role in the decomposition of the ceramic substrate.

  9. Dissolution of crystalline ceramics

    White, W.B.

    1982-01-01

    The present program objectives are to lay out the fundamentals of crystalline waste form dissolution. Nuclear waste ceramics are polycrystalline. An assumption of the work is that to the first order, the release rate of a particular radionuclide is the surface-weighted sum of the release rates of the radionuclide from each crystalline form that contains it. In the second order, of course, there will be synergistic effects. There will be also grain boundary and other microstructural influences. As a first approximation, we have selected crystalline phases one at a time. The sequence of investigations and measurements is: (i) Identification of the actual chemical reactions of dissolution including identification of the solid reaction products if such occur. (ii) The rates of these reactions are then determined empirically to give what may be called macroscopic kinetics. (iii) Determination of the rate-controlling mechanisms. (iv) If the rate is controlled by surface reactions, the final step would be to determine the atomic kinetics, that is the specific atomic reactions that occur at the dissolving interface. Our concern with the crystalline forms are in two areas: The crystalline components of the reference ceramic waste form and related ceramics and the alumino-silicate phases that appear in some experimental waste forms and as waste-rock interaction products. Specific compounds are: (1) Reference Ceramic Phases (zirconolite, magnetoplumbite, spinel, Tc-bearing spinel and perovskite); (2) Aluminosilicate phases (nepheline, pollucite, CsAlSi 5 O 12 , Sr-feldspar). 5 figures, 1 table

  10. Ceramic analysis in Greece

    Hilditch, J.

    2016-01-01

    Scientific, analytical or ‘archaeometric’ techniques for investigating ceramic material have been used within archaeology for over 50 years and now constitute an indispensable tool for archaeologists in the Aegean world (see Jones 1986 for a detailed summary of early work in Greece and Italy) and

  11. Ceramic solid electrolytes

    Goodenough, John B. [Center for Materials Science and Engineering, University of Texas at Austin, Austin, TX (United States)

    1997-02-15

    Strategies for the design of ceramic solid electrolytes are reviewed. Problems associated with stoichiometric and doped compounds are compared. In the illustration of design principles, emphasis is given to oxide-ion electrolytes for use in solid-oxide fuel cells, oxygen pumps, and oxygen sensors

  12. Coated ceramic breeder materials

    Tam, Shiu-Wing; Johnson, Carl E.

    1987-01-01

    A breeder material for use in a breeder blanket of a nuclear reactor is disclosed. The breeder material comprises a core material of lithium containing ceramic particles which has been coated with a neutron multiplier such as Be or BeO, which coating has a higher thermal conductivity than the core material.

  13. Evaluation of the crude oil viscosity variation in function of the demulsifiers addition; Avaliacao da variacao da viscosidade de oleo cru em funcao da adicao de desemulsificante

    Lopes, Jansen M.; Lucas, Elisabete F. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Macromoleculas]. E-mail: elucas@ima.ufrj.br; Neves, Guilherme B.M. [COMAB Especialidades Quimicas Ltda., Rio de Janeiro, RJ (Brazil)]. E-mail: tecnico@comabrio.com

    2003-07-01

    One way of improving well production is the addition of demulsifier already in the gas lift. This is due to the apparent viscosity of water-in-oil emulsions being higher than apparent viscosity of crude oil, which in turn is higher than the apparent viscosity of an water-in-oil dual phase admixture and is also higher than the apparent viscosity of an oil-in-water emulsion. However, there are some situations where, in order to obtain separate flows of oil and water phases, demulsifier should be added in specific amounts in order to promote the desired phase separation. In heavy oils water and oil phase separation may be hard to obtain, however, the right demulsifier amount may imply in a considerable decrease in petroleum viscosity even without the appearance of two phases, making the flow easier. This work has evaluated the viscosity of a heavy crude having API degree 14 and BSW 52%, as a function of the addition of different amounts of DEMTROL BR 67, manufactured by Dow Quimica/Comab, Brazil, as demulsifier. (author)

  14. Effects of using kaolin waste and granite waste as raw materials for the production of low-water absorption ceramic tiles; Efeitos da co-utilizacao dos residuos do beneficiamento do caulim e da extracao do granito rain forest para a producao de revestimentos ceramicos com baixa absorcao de agua

    Freires, H.P.; Argonz, R.; Nogueira, R.E.F.Q.; Sasaki, J.M., E-mail: argonz@ufc.br [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil); Sales, J.C. [Universidade do Vale do Aracau (UVA), Crateus, CE (Brazil)

    2012-07-01

    This study aims to evaluate the potential of co-use of granite waste (Rain Forest) and kaolin waste as raw material for the manufacture of ceramic coating of low water absorption. Raw materials were characterized by X-ray diffraction. Kaolin residue was added to the residue of granite in the following proportions (in wt%): 0, 10, 20, 30, 40 and 50%. Specimens were fabricated by uniaxial pressing and fired at 1175,1200 and 1225 deg C. Studies of firing linear shrinkage, water absorption, apparent porosity, apparent density and tensile bending test (or rupture modulus) were conducted. The temperature of 1225 deg C allowed the use of a mixture of 50% granite residue and 50% kaolin residue. Ceramic parts made from that mixture exhibited the maximum values required by the Brazilian Standard NBR 13818 for water absorption, shrinkage and density. (author)

  15. Efeito da adição de resíduo de rocha ornamental nas propriedades tecnológicas e microestrutura de piso cerâmico vitrificado Effect of the addition of ornamental rock waste on the technological properties and microstructure of vitrified ceramic floor tiles

    A. J. Souza

    2011-06-01

    Full Text Available A indústria de rochas ornamentais gera grandes quantidades de resíduos sólidos na forma de pós finos. Estes resíduos, quando descartados no ambiente, provocam impacto ambiental negativo. Foi feito um estudo sobre a influência de um resíduo de rocha ornamental nas propriedades e microestrutura de piso cerâmico vitrificado. Foi preparada uma série de massas cerâmicas contendo até 30% em peso de resíduo de rocha ornamental. Peças cerâmicas foram preparadas por prensagem uniaxial e sinterizadas entre 1190 e 1250 ºC em um ciclo de queima rápida. As seguintes propriedades tecnológicas foram determinadas: retração linear, absorção de água, massa específica aparente, e tensão de ruptura a flexão. A evolução da microestrutura e a análise de fases foram acompanhadas por microscopia eletrônica de varredura e difração de raios X. Os resultados mostraram que adições de até 30% em peso de resíduo de rocha ornamental causaram variações significativas na generalidade das propriedades tecnológicas da massa cerâmica de referência. A microestrutura das peças cerâmicas também foi influenciada com a incorporação do resíduo estudado. Os resultados também mostram que a substituição de feldspato sódico por resíduo de rocha ornamental nas massas cerâmicas tende a melhorar a qualidade do piso cerâmico.The ornamental rock industries generate huge amounts of solid wastes (fine powders. These wastes as disposed in the environment generate negative environmental impacts. In this work a study was done on the influence of an ornamental rock waste in the technological properties and microstructure of vitrified floor tile. A series of ceramic pastes were prepared with additions of up to 30 wt% of waste. Ceramic pieces were prepared by uniaxial pressing and sintered between 1190 and 1250 ºC using a fast-firing cycle. The following technological properties were determined: linear shrinkage, water absorption, apparent density

  16. Influência das características ácido-básicas da superfície dos óxidos na estabilidade de suspensões cerâmicas de Al2O3 ou SnO2 com dispersantes comerciais Influence of acid-basic characteristic of Al2O3 or SnO2 surfaces on the stability of ceramic suspensions with commercial dispersants

    D. Gouvêa

    2001-03-01

    Full Text Available Uma suspensão cerâmica estável pode ser obtida através da combinação de um pó cerâmico, um solvente e um dispersante. Polímeros adsorvidos às partículas de óxidos podem estabilizar uma suspensão através da formação de um potencial de repulsão entre as partículas que pode ser de origem eletrostática, estérica ou da combinação das duas. A adsorção depende das características da superfície dos óxidos cerâmicos utilizados. O SnO2 apresenta um ponto isoelétrico igual a 4 e a alumina igual a 8. A característica ácida da superfície do SnO2 faz com que ocorra uma competição entre a adsorção dos polímeros derivados de ácidos poliacrílicos e das hidroxilas. O aumento do potencial zeta ocorre devido à mudança do pH e não devido à adsorção dos polímeros. No caso da alumina, a superfície básica permite a adsorção dos polímeros e o aumento do potencial zeta sem que haja competição com os grupos OH-. Este estudo foi realizado através da medida simultânea de potencial zeta e pH das suspensões através da técnica ESA (Electrokinetic Sonic Amplitude.A stable ceramic dispersion can be obtained by mixing a ceramic powder, a solvent and a dispersant. Polymers adsorbed to ceramic particles may stabilize the dispersions by creating a repulsion charge among then.The stabilization has an electrostatic or steric origin, or even the sum of both processes. The adsorption depends on the characteristics of the powder surface. Isoelectric points (IEP of the SnO2 and alumina are 4 and 8, respectively. The basic/acid characteristic of the surface originates a competition between the adsorption of polymers derivated from polyacrilic acids and hidroxiles due to acidic characteristics of the SnO2 surface. In the other hand, alumina's basic surface allows polymers to adsorb and to increase the zeta potential without any competition between the dispersants and OH- ions. This study has been carried out by simultaneously

  17. Wonderland of ceramics superplasticity; Ceramics chososei no sekai

    Wakai, F. [National Industrial Research Inst. of Nagoya, Nagoya (Japan)

    1995-07-01

    It has been ten years since it was found that ceramics, which is strong and hard at room temperatures and does not deform at all, may exhibit a superplasticity phenomenon at high temperatures that it endlessly elongates when pulled as if it were chewing gum. This phenomenon is one of peculiar behaviours which nano-crystal ceramics, pulverized to an extent that the crystalline particle size is on the order of nanometers, show. The application of superplasticity made the material engineers`s old dream come true that hard ceramics are arbitrarily deformed and machined like metal. Using as models materials such as silicone nitride, alumina and zirconia, this paper describes the history and deformation mechanism of ceramics superplasticity, material design aiming at superplasticization and application of ceramics superplasticity to the machining technology. Furthermore, it describes the trend and future development of international joint researches on the basic surveys on ceramics superplasticity. 25 refs., 11 figs.

  18. Addition of schelita residue from the mine in Cerro Cora Bodo / RN in the composition of ceramic materials; Adicao de residuo de scheelita da mina Bodo em Cerro Cora/RN na composicao de materiais ceramicos

    Almeida, A.B.D. de; Souza, M. M. de; Farias, D.S.U. de; Lima, T.C. de; Nobrega, L.F.P. de M. [Instituto Federal de Ciencia e Tecnologia do Rio Grande do Norte (IFRN), RN (Brazil); Mendes, L.B., E-mail: anabeatriz.d.a@outlook.com [Fundacao de Apoio a Pesquisa do Rio Grande do Norte (FAPERN), Natal RN (Brazil)

    2016-07-01

    Mining activities produce mineral waste that can degrade the environment. The waste generated by companies is not reused due to the fact they fail to present an application for it that proves to be economically viable. Seeking the reuse of mineral waste and reduce the environmental impacts, this work addresses the chemical characterization by x-ray fluorescence (FRX), of the processing of scheelite reject at Bodo mine in Cerro Cora-RN. For the procedure, the sample was collected, grounded and sieved to #200, and then characterized to evaluate its chemical composition and its potential to be incorporated into materials. Besides the characterization, a water absorption test and also a bending test were performed to analyze the power and tension of the material. The result of the analysis indicated that the sample researched presents a greater concentration of SiO{sub 2} to be used as a structuring element in ceramic mass, but in the traditional formulation, it will only be added 10% of the reject in its formulation, because besides the SiO{sub 2} in the sample analyzed other elements that act with fluxes were found. It was also observed the material has low water absorption, but the reject reached low strength and breakdown voltage. We concluded that the reject of scheelite presents great potential, and therefore, further tests can be conducted to analyze the possibility of being added as raw material for the formulation of other materials like cement. (author)

  19. FIBROUS CERAMIC-CERAMIC COMPOSITE MATERIALS PROCESSING AND PROPERTIES

    Naslain , R.

    1986-01-01

    The introduction of continuous fibers in a ceramic matrix can improve its toughness, if the fiber-matrix bonding is weak enough, due to matrix microcracking and fiber pull-out. Ceramic-ceramic composite materials are processed according to liquid or gas phase techniques. The most important are made of glass, carbide, nitride or oxide matrices reinforced with carbon, SiC or Al2O3 fibers.

  20. Positron annihilation in transparent ceramics

    Husband, P.; Bartošová, I.; Slugeň, V.; Selim, F. A.

    2016-01-01

    Transparent ceramics are emerging as excellent candidates for many photonic applications including laser, scintillation and illumination. However achieving perfect transparency is essential in these applications and requires high technology processing and complete understanding for the ceramic microstructure and its effect on the optical properties. Positron annihilation spectroscopy (PAS) is the perfect tool to study porosity and defects. It has been applied to investigate many ceramic structures; and transparent ceramics field may be greatly advanced by applying PAS. In this work positron lifetime (PLT) measurements were carried out in parallel with optical studies on yttrium aluminum garnet transparent ceramics in order to gain an understanding for their structure at the atomic level and its effect on the transparency and light scattering. The study confirmed that PAS can provide useful information on their microstructure and guide the technology of manufacturing and advancing transparent ceramics.

  1. Positron annihilation in transparent ceramics

    Husband, P; Selim, F A; Bartošová, I; Slugeň, V

    2016-01-01

    Transparent ceramics are emerging as excellent candidates for many photonic applications including laser, scintillation and illumination. However achieving perfect transparency is essential in these applications and requires high technology processing and complete understanding for the ceramic microstructure and its effect on the optical properties. Positron annihilation spectroscopy (PAS) is the perfect tool to study porosity and defects. It has been applied to investigate many ceramic structures; and transparent ceramics field may be greatly advanced by applying PAS. In this work positron lifetime (PLT) measurements were carried out in parallel with optical studies on yttrium aluminum garnet transparent ceramics in order to gain an understanding for their structure at the atomic level and its effect on the transparency and light scattering. The study confirmed that PAS can provide useful information on their microstructure and guide the technology of manufacturing and advancing transparent ceramics. (paper)

  2. Ceramic hot-gas filter

    Connolly, E.S.; Forsythe, G.D.; Domanski, D.M.; Chambers, J.A.; Rajendran, G.P.

    1999-05-11

    A ceramic hot-gas candle filter is described having a porous support of filament-wound oxide ceramic yarn at least partially surrounded by a porous refractory oxide ceramic matrix, and a membrane layer on at least one surface thereof. The membrane layer may be on the outer surface, the inner surface, or both the outer and inner surface of the porous support. The membrane layer may be formed of an ordered arrangement of circularly wound, continuous filament oxide ceramic yarn, a ceramic filler material which is less permeable than the filament-wound support structure, or some combination of continuous filament and filler material. A particularly effective membrane layer features circularly wound filament with gaps intentionally placed between adjacent windings, and a filler material of ceramic particulates uniformly distributed throughout the gap region. The filter can withstand thermal cycling during back pulse cleaning and is resistant to chemical degradation at high temperatures.

  3. Ceramic hot-gas filter

    Connolly, Elizabeth Sokolinski; Forsythe, George Daniel; Domanski, Daniel Matthew; Chambers, Jeffrey Allen; Rajendran, Govindasamy Paramasivam

    1999-01-01

    A ceramic hot-gas candle filter having a porous support of filament-wound oxide ceramic yarn at least partially surrounded by a porous refractory oxide ceramic matrix, and a membrane layer on at least one surface thereof. The membrane layer may be on the outer surface, the inner surface, or both the outer and inner surface of the porous support. The membrane layer may be formed of an ordered arrangement of circularly wound, continuous filament oxide ceramic yarn, a ceramic filler material which is less permeable than the filament-wound support structure, or some combination of continuous filament and filler material. A particularly effective membrane layer features circularly wound filament with gaps intentionally placed between adjacent windings, and a filler material of ceramic particulates uniformly distributed throughout the gap region. The filter can withstand thermal cycling during backpulse cleaning and is resistant to chemical degradation at high temperatures.

  4. Avaliação da técnica de solidificação/estabilização no tratamento de resíduo têxtil: produção de bloco cerâmico de vedação Evaluation of solidification/stabilization process in the treatment of textile wastes: production of ceramic blocks

    F. M. S. Ramos

    2009-12-01

    Full Text Available A incorporação do resíduo têxtil em matrizes de argila para a produção de blocos cerâmicos de vedação foi avaliada por meio do processo de solidificação/estabilização (s/e. Inicialmente foi feita a caracterização do resíduo têxtil e da argila, utilizada como matriz para produção de blocos cerâmicos de vedação. A composição química deste resíduo têxtil é variada, contendo Al, Fe, Mn, Na, Pb, Cu, Cr e Zn, oriundos do processo têxtil e do tratamento do efluente gerado no processo. Sua classificação se enquadra como um resíduo não perigoso e não inerte. Posteriormente, foram preparados blocos com composição 0, 5, 10, 15, 20 e 25% de resíduo têxtil. A mistura foi feita proporcionalmente em porcentagem de massa seca. Para análise comparativa das características químicas desses blocos cerâmicos, foram produzidos blocos somente com argila. As concentrações dos metais analisados, nos extratos lixiviados e solubilizados dos blocos cerâmicos, em todas as proporções de incorporação do resíduo têxtil, ficaram abaixo dos limites definidos pela NBR 10004/2004 da ABNT, classificando-os como não perigosos e inertes, ou seja, não oferecendo riscos de futura contaminação do solo durante a sua vida útil, bem como quando o mesmo for disposto em aterros depois de utilizados. Resultados relacionados à resistência mecânica dos blocos cerâmicos mostraram que todas as proporções de incorporação atenderam ao requisito mínimo exigido por norma. Além disso, foi possível observar que, com até 20% de resíduo têxtil incorporado à massa cerâmica, os requisitos exigidos por norma ABNT relacionados ao índice de absorção de água foram obedecidos. Assim, o processo de s/e foi capaz de imobilizar de forma eficaz os metais presentes no resíduo têxtil nos blocos cerâmicos.This paper evaluates the incorporation of textile waste in clay matrices for the production of ceramic blocks with no structural function

  5. Ceramics for fusion applications

    Clinard, F.W. Jr.

    1987-01-01

    Ceramics are required for a variety of uses in both near-term fusion devices and in commercial powerplants. These materials must retain adequate structural and electrical properties under conditions of neutron, particle and ionizing irradiation; thermal and applied stresses; and physical and chemical sputtering. Ceramics such as Al 2 O 3 , MgAl 2 O 4 , BeO, Si 3 N 4 and SiC are currently under study for fusion applications, and results to date show widely-varying responses to the fusion environment. Materials can be identified today that will meet initial operating requirements, but improvements in physical properties are needed to achieve satisfactory lifetimes for critical applications. (author)

  6. Ceramics for fusion applications

    Clinard, F.W. Jr.

    1986-01-01

    Ceramics are required for a variety of uses in both near-term fusion devices and in commercial powerplants. These materials must retain adequate structural and electrical properties under conditions of neutron, particle, and ionizing irradiation; thermal and applied stresses; and physical and chemical sputtering. Ceramics such as Al 2 O 3 , MgAl 2 O 4 , BeO, Si 3 N 4 and SiC are currently under study for fusion applications, and results to date show widely-varying response to the fusion environment. Materials can be identified today which will meet initial operating requirements, but improvements in physical properties are needed to achieve satisfactory lifetimes for critical applications

  7. Ceramic Composite Thin Films

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  8. Advanced ceramic in structural engineering

    Alonso Rodea, Jorge

    2012-01-01

    The work deals with "Advanced Ceramics in Structural Engineering”. Throughout this work we present the different types of ceramic that are currently in wider use, and the main research lines that are being followed. Ceramics have very interesting properties, both mechanical and electrical and refractory where we can find some of the most interesting points of inquiry. Through this work we try tounderstand this complex world, analyzing both general and specific properties of ...

  9. The technical ceramics (second part)

    Auclerc, S.; Poulain, E.

    2004-01-01

    This work deals with ceramics used in the nuclear and the automotive industries. Concerning the nuclear sector, ceramics are particularly used in reactors, in the treatment of radioactive wastes and for the storage of the ultimate wastes. Details are given about the different ceramics used. In the automobile sector, aluminium is principally used for its lightness and cordierite, basic material of catalyst supports is especially used in the automobile devices of cleansing. (O.M.)

  10. Neutrons, radiation and archaeology: a multi analytical case study of incised rim tradition ceramics in Central Amazon; Neutrons, radiacao e arqueologia: estudo de caso multianalitico de ceramicas da tradicao borda incisa na Amazonia Central

    Hazenfratz-Marks, Roberto

    2014-07-01

    This thesis is an interdisciplinary archaeometric study involving archaeological ceramic material from two large archaeological sites in Central Amazon, namely Lago Grande and Osvaldo, on the confluence region of Negro and Solimoes rivers. It was tested a hypothesis about the existence of an exchange network between the former inhabitants of those sites, focusing on material and/or technological exchange. That hypothesis has implications for archaeological theories of human occupation of the pre-colonial Central Amazon, which try to relativise the role of ecological difficulties of the tropical forest as a limiting factor for the emergence of social complexity in the region. The physical-chemical characterization of potsherds and clay samples near the sites was carried out by: instrumental neutron activation analysis (INAA) to determine the elemental chemical composition; electron paramagnetic resonance (EPR) to determine the firing temperature; X-ray diffraction (XRD) to determine the mineralogical composition; and dating by optically stimulated luminescence (OSL). Previous studies showed that Osvaldo and Lago Grande were occupied by people which produced pottery classified in the Manacapuru and Paredao phases, subclasses of the Incised Rim Tradition, around the 5-10th and 7-12th centuries BC, respectively. INAA results were analyzed by multivariate statistical methods, whereby two chemical groups of pottery were defined for each archaeological site. Significant variation in firing temperatures and mineralogical composition were not identified for such groups. By integration of the results with archaeological data, the superposition between pairs of chemical groups was interpreted as a correlate of an ancient exchange network, although it was not possible to define if it existed exclusively between Lago Grande and Osvaldo. On the contrary, it was suggested that Lago Grande participated in a more extensive exchange network by comparison of two chemical groups

  11. Ceramic superconductors II

    Yan, M.F.

    1988-01-01

    This volume compiles papers on ceramic superconductors. Topics include: structural patterns in High-Tc superconductors, phase equilibria of barium oxide superconductors, localized electrons in tetragonal YBa/sub 2/Cu/sub 3/O/sub 7-δ/, lattice and defect structure and properties of rare earth/alkaline earth-copper-oxide superconductors, alternate candidates for High-Tc superconductors, perovskite-structure superconductors; superconductive thin film fabrication, and superconductor/polymer composites

  12. Piezoelectric Ceramics Characterization

    Jordan, T

    2001-01-01

    ... the behavior of a piezoelectric material. We have attempted to cover the most common measurement methods as well as introduce parameters of interest. Excellent sources for more in-depth coverage of specific topics can be found in the bibliography. In most cases, we refer to lead zirconate titanate (PZT) to illustrate some of the concepts since it is the most widely used and studied piezoelectric ceramic to date.

  13. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-01-01

    Conversion of natural gas to liquid fuels and chemicals is a major goal for the Nation as it enters the 21st Century. Technically robust and economically viable processes are needed to capture the value of the vast reserves of natural gas on Alaska's North Slope, and wean the Nation from dependence on foreign petroleum sources. Technologies that are emerging to fulfill this need are all based syngas as an intermediate. Syngas (a mixture of hydrogen and carbon monoxide) is a fundamental building block from which chemicals and fuels can be derived. Lower cost syngas translates directly into more cost-competitive fuels and chemicals. The currently practiced commercial technology for making syngas is either steam methane reforming (SMR) or a two-step process involving cryogenic oxygen separation followed by natural gas partial oxidation (POX). These high-energy, capital-intensive processes do not always produce syngas at a cost that makes its derivatives competitive with current petroleum-based fuels and chemicals. This project has the following 6 main tasks: Task 1--Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. Task 2--Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. Task 3--Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. Task 4--Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. Task 5--Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. Task 6--Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques

  14. Ion conductivity of nasicon ceramics

    Hoj, J.W.; Engell, J.

    1989-01-01

    The Nasicon ss ,Na 1 + X Zr 2 Si X P 3 - X O 12 o , X , 3, includes some of the best solid state sodium conductors known today. Compositions in the interval 1.6 , X , 2.6 show conductivities comparable to the best β double-prime-alumina ceramics. It is well known that the ion conductivity of β-alumina is strongly dependent on the texture of the ceramic. Here a similar behavior is reported for Nasicon ceramics. Ceramics of the bulk composition Na 2.94 Zr 1.49 Si 2.20 P 0.80 O 10.85 were prepared by a gel method. The final ceramics consist of Nasicon crystals with x = 2.14 and a glass phase. The grain size and texture of the ceramics were controlled by varying the thermal history of the gel based raw materials and the sintering conditions. The room temperature resistivity of the resulting ceramics varies from 3.65*10 3 ohm cm to 1.23*10 3 ohm cm. Using the temperature comparison method and estimates of the area of grain boundaries in the ceramics, the resistivity of the Nasicon phase is estimated to be 225 ohm cm at 25 degrees C. B 2 O 3 - or Al 2 O 3 -doping of the glass bearing Nasicon ceramic lower the room temperature resistivity by a factor 2 to 5. The dopants do not substitute into the Nasicon phase in substantial amounts

  15. Fracture strength of three all-ceramic systems: Top-Ceram compared with IPS-Empress and In-Ceram.

    Quran, Firas Al; Haj-Ali, Reem

    2012-03-01

    The purpose of this study was to investigate the fracture loads and mode of failure of all-ceramic crowns fabricated using Top-Ceram and compare it with all-ceramic crowns fabricated from well-established systems: IPS-Empress II, In-Ceram. Thirty all-ceramic crowns were fabricated; 10 IPS-Empress II, 10 In-Ceram alumina and 10 Top-Ceram. Instron testing machine was used to measure the loads required to introduce fracture of each crown. Mean fracture load for In-Ceram alumina [941.8 (± 221.66) N] was significantly (p > 0.05) higher than those of Top-Ceram and IPS-Empress II. There was no statistically significant difference between Top-Ceram and IPS-Empress II mean fracture loads; 696.20 (+222.20) and 534 (+110.84) N respectively. Core fracture pattern was highest seen in Top- Ceram specimens.

  16. Estudo do comportamento reológico de barbotinas preparadas com argilas da Formação Corumbataí utilizadas no pólo cerâmico de Santa Gertrudes (SP Study of rheological behavior of slips prepared with clays from Corumbataí Formation used in ceramic pole of Santa Gertrudes (SP

    R. R. Rocha

    2008-09-01

    Full Text Available Este estudo surgiu da necessidade das indústrias cerâmicas do pólo de Santa Gertrudes (SP se adaptarem às mudanças do comportamento do mercado e às exigências dos órgãos ambientais em relação aos riscos causados pela geração de poeira na fase de preparação da massa. Assim, o processo de preparação de massa via úmida pode ser uma alternativa para esta substituição, sendo necessária a obtenção de uma barbotina que apresente um comportamento reológico adequado ao processo e ao consumo de energia. Foram feitas medidas de viscosidade, tensão de cisalhamento e taxa de cisalhamento com viscosímetro rotacional, tendo como parâmetros de controle, o teor de sólidos da barbotina e a granulometria. Desta forma, foram verificadas variações das suspensões, como o comportamento pseudoplástico e a tixotropia. Também foi analisada a dependência do comportamento reológico com a mineralogia das argilas, obtida por difração de raios X. Os resultados das curvas reológicas mostraram-se muito coerentes com a mineralogia determinada, indicando uma piora do comportamento reológico no sentido da base para o topo da Formação Corumbataí, devido à alteração supérgena e presença de esmectitas.The study of rheological behavior of clay slips at Corumbataí Formation arose from the need for the ceramic industries of Santa Gertrudes pole (SP to adapt to the changes of the market behavior and to the demands of the environmental organs regarding the risks caused by the generation of dust in the mass preparation process. The wet grinding process can be an alternative for this substitution, and it]s important to have proper rheological features of the slips for the process and energy consumption. Viscosity measurements, shear stress and shear rate have been made with rotational viscometer, by having the solid content of the slip and particle size as control parameters. Therefore variations of the suspensions have been verified, like the

  17. Evaluation of the energetic equivalence of goat manure biogas; Avaliacao da equivalencia energetica do biogas de esterco de caprinos

    Canafistula, Francisco Jose Firmino; Carvalho, Paulo Cesar Marques de [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Dept. de Engenharia Eletrica], e-mails: firmino@ufc.br, carvalho@dee.ufc.br

    2008-07-01

    The present paper shows the results of a research about a new production system model based on goats; part of the animals manure is used for biogas production. The biogas is used as fuel for water pumping for the irrigation of the animals pasture. For the viability of the project, a photovoltaic powered electrified fence was used. Additional to the positive results of sustainability, innovative solutions were developed for sizing, optimization and costs reduction by the use of digesters in small rural communities of the semi-arid of the Brazilian Northeast Region. (author)

  18. Evaluation of the absorbed dose in odontological computerized tomography; Avaliacao da dose absorvida em tomografia computadorizada odontologica

    Legnani, Adriano; Schelin, Hugo R.; Rocha, Anna Silvia P.S. da, E-mail: schelin@utfpr.edu.b, E-mail: anna@utfpr.edu.b [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Khoury, Helen J., E-mail: khoury@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

    2011-10-26

    This paper evaluated the absorbed dose at the surface entry known as 'cone beam computed tomography' (CBCT) in odontological computerized tomography. Examination were simulated with CBCT for measurements of dose. A phantom were filled with water, becoming scatter object of radiation. Thermoluminescent dosemeters were positioned on points correspondent to eyes and salivary glands

  19. Evaluation of the absorbed dose in odontological computerized tomography; Avaliacao da dose absorvida em tomografia computadorizada odontologica

    Legnani, Adriano; Schelin, Hugo R; Rocha, Anna Silvia P.S. da, E-mail: schelin@utfpr.edu.b, E-mail: anna@utfpr.edu.b [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Khoury, Helen J., E-mail: khoury@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

    2011-10-26

    This paper evaluated the absorbed dose at the surface entry known as 'cone beam computed tomography' (CBCT) in odontological computerized tomography. Examination were simulated with CBCT for measurements of dose. A phantom were filled with water, becoming scatter object of radiation. Thermoluminescent dosemeters were positioned on points correspondent to eyes and salivary glands

  20. Evaluation of welding by MIG in martensitic stainless steel; Avaliacao da soldagem pelo processo MIG em aco inoxidavel martensitico

    Fernandes, M.A. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Mariano, N.A.; Marinho, D.H.C. Marinho, E-mail: neideaparecidamariano@gmail.co [Universidade Federal de Alfenas (UNIFAL), Pocos de Caldas, MG (Brazil)

    2010-07-01

    This work evaluated structure's characterization and mechanical properties after the welding process of the stainless steel CA6NM. The employed welding process was the metal active gas with tubular wire. The control of the thermal cycle in the welding process has fundamental importance regarding the properties of the welded joint, particularly in the thermally affected zone. The mechanical properties were appraised through impact resistance tests and the hardness and microstructure through metallographic characterization and Ray-X diffraction. The parameters and the process of welding used promoted the hardness and toughness appropriate to the applications of the steel. Welding energy's control becomes an essential factor that can affect the temperature of carbide precipitation and the nucleation of the retained austenite in the in the region of the in the thermally affected zone. (author)

  1. Evaluation of kerma rate in radioactive waste disposal; Avaliacao da taxa de kerma em deposito de rejeitos radioativos

    Rosa, Rodolfo O.; Silva, Joao C.P.; Santos, Joao R. dos, E-mail: oliveira@ien.gov.br, E-mail: jcarlos@ien.gov.br, E-mail: regis@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2014-07-01

    This study aims to assess the progression of kerma rate levels in the air due to the increase of collection, storing and storage of radioactive waste in the new building (after expansion) of the radioactive waste disposal (RWD) of the Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Brazil. This review is carried out every six months at IEN with thermoluminescent dosimeter lithium fluoride LiF: Mg, Cu, P (TLD-100H). Here are the average values of kerma rate for the period 2008- 2012. In this context, the methodology used for selection and choices of detectors used in dosimeters is presented. The detectors were chosen through homogeneity criteria of the pack, standardization factor and coefficient of variation (CV%). The monitoring points and the exposure time of the detectors are chosen considering various factors, including the rate of occupation and indoor and outdoor positions to RWD. These evaluations showed that the contribution of the new waste disposal in increasing kerma rate of IEN, has proved to be insignificant, that is, the presence of RWD does not contribute to increased environmental kerma rate in the region around this installation.

  2. Evaluation of radioiodinetherapy protocol for patients with Plummer disease; Avaliacao do protocolo da radioiodoterapia para pacientes com doenca de Plummer

    Mendonca, Keyla Mary Cavalheiro; Antonio Filho, Joao; Brandao, Simone Cristina Soares, E-mail: keylamcm@yahoo.com.br, E-mail: jaf@ufpe.br, E-mail: simonecordis@yahoo.com.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Santos, Marcus Aurelio P. dos, E-mail: masantos@cnen.gov.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2014-07-01

    The disease Plummer (DP) is generated by the thyroid cells that function autonomously, independent the rest of the organ parenchyma. The DP presents a prevalence of 1% to 9%, higher in regions with iodine deficiency, affecting six women for every man. The study was conducted at the Department of Nuclear Medicine of Universidade Federal de Pernambuco (UFPE) from {sup 99m}Tc data capture and mass existing in the thyroid records of 54 patients with PD who underwent radioiodine therapy with fixed activities 1110 megabecquerels (MBq) from 2004 to 2008. For capitation of {sup 99m}Tc from a group of 22 patients were used 5 ml syringes, measured by a Capintec CRC-7 model activimeter, having scintigraphy after 20 minutes and results in a region of interest. Mass evaluation was based on method of palpation of the thyroid, considering the mass standard. It is observed that 68.2% of patients received more activity than needed, 31.8% were less active, and none received activity in accordance with your needs. There was a statistically significant difference (p <0.05) between the fixed activities and activities computed for all patients, according to Chi-square test for independence with 21 degrees of freedom. The cure rate of a group of 32 patients was 75% after one year of follow-up. It is suggested that the RIT is preceded by an assessment of the maximum percentage of uptake and thyroid mass.

  3. Evaluation of the dispersion of oil refinery liquid effluent; Avaliacao da dispersao de efluente liquido de refinaria de petroleo

    Mariano, Adriano Pinto; Silva, Ariovaldo Jose da; Oliveira, Valdenilson Jose Alves de; Angelis, Dejanira de Franceschi de [Universidade Estadual Paulista (UNESP), Rio Claro, SP (Brazil). Dept. de Bioquimica e Microbiologia. Inst. de Biociencias], e-mail: adrianomariano@yahoo.com.br

    2010-07-15

    In this paper, two techniques to evaluate the dispersion of the effluent of an oil refinery are presented. Thus, the dispersion plume was characterized by field measurements of electrical conductivity and by computational simulation (Cormix simulator). An oil refinery whose effluent is discharged on the Atibaia river (Paulinia/SP) is taken as study case. The behavior of the effluent was evaluated until 1000 m after the discharge. The results show that the measurement of electrical conductivity is a suitable technique to evaluate the dispersion of oil refinery wastewaters, since they have high conductivity and for this reason there is a strong contrast between the values of the wastewater and the ambient background. Furthermore, other water quality parameters had a dispersion behavior similar to that shown by the conductivity. The dispersion plume generated by the computational simulator showed high concordance with the field data. In this manner, computational simulation can be a useful tool to evaluate the dispersion of discharges considering hypothetical scenarios, as well as to design the discharge channel. (author)

  4. Cementing quality evaluation with ultrasonic logs in fiberglass casings; Avaliacao da qualidade do cimento em revestimentos de fibra de vidro

    Campos, Wellington; Lazaro, Andre F. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The sonic and ultrasonic profiles are used as the main tools in assessing the cementing quality between formation and casing in oil wells. This assessment is important, because, if there is a failure in the primary cementing, both the structural integrity and zone isolation will be compromised. The sonic profiles are based on the acoustic energy attenuation in casing, cement and formation, while the ultrasonic profiles are based on the resonance of the wave pulse within the media where they travel (casings, cement and formation). The attenuation and resonance are due to the difference in the way the wave travel within these media. The acoustic impedance is the quantification of this difference, determining the refraction and reflection between the environments, and wave attenuation as well. In steel casings, this difference is meaningful, allowing the captured signals (reflected pulses) to be interpreted as good adhesion between cement and casing, or a lack of adhesion at some interval. In fiber glass casings, the impedance contrast between glass and cement is small and not detectable with the CBL/VDL sensors. The CBL/VDL tools provide an inefficient assessment of the quality of the cementing. The ultrasonic profile does not have this problem, theoretically. The goal of this work is to demonstrate and recommend the ultrasonic tool as the main instrument to assess the cementation quality in fiber glass casings. (author)

  5. Evaluation of the ocular protection for low intensity therapeutic lasers; Avaliacao da protecao ocular para lasers terapeuticos em baixa intensidade

    Cordon, Rosely

    2003-07-01

    The low intensity laser therapy (LILT) has been extensively used in medicine and dentistry presenting positive effects. However, the laser radiation can also cause adverse effects. Due to the ocular focalization property, in the wavelength from 400 to 1400 nm, the retina is more susceptible to damage by radiation than any other part of the human body. Then, the ocular protection is frequently emphasized. This protection must attenuate the radiation to a safe level. The International Electrotechnical Commission (IEC) standard IEC 60825-1 suggests safety requirements for medical laser equipment, including the ocular protection, based on maximum permissible exposure levels. The Brazilian legislation adopts a corresponding IEC standard, the NBR IEC 601.2.22, for safety requirements. The aim of this study was to analyze the adequacy of the ocular protectors furnished by four laser equipment manufacturers, commercially available in Brazil, commonly used for LILT. For this purpose, the laser equipment and the respective ocular protectors were characterized. The adequacy was verified according to the IEC standards. It was found, among other results, ocular protectors attenuating to safe levels the radiation emitted by the respective laser equipment, however, presenting inadequate visual transmission. Inefficient protection and protection indicated in cases where they were not necessary were also observed. (author)

  6. Evaluation of external exposure in a radioactive waste deposit; Avaliacao da exposicao externa em um deposito de rejeitos radioativos

    Oliveira, Sergio Quinet de; Pereira, Wagner de Souza; Py Junior, Delcy de Azevedo; Dores, Luis Augusto de Carvalho Bresser; Dantas, Marcelino Vicente de Almeida; Silva, Ana Claudia Antunes; Garcia Filho, Oswaldo, E-mail: wspereira@inb.gov.b, E-mail: sergioquinet@inb.gov.b, E-mail: delcy@inb.gov.b, E-mail: luisdores@inb.gov.b, E-mail: marcelino@inb.go.b, E-mail: anasilva@inb.gov.b, E-mail: ogarcia@inb.gov.b [Industrias Nucleares do Brasil (UTM/INB), Pocos de Caldas, MG (Brazil). Unidade de Tratamento de Minerio

    2011-10-26

    The ore treatment unit (OTU) of Industrias Nucleares do Brasil (INB), located at Caldas municipality - Minas Gerais, Brazil, posses a radioactive deposit, coming mainly from the chemical processing of monazite sands for obtention of 'rare earths'. The main components of these waste are the 'torta II (thorium rich residues) and the 'mesothorium' ({sup 228}Ra rich residues) - conditioned in steel drums (200 liters), plastic pumps (100 liters) or underground silos. These loaders are deposited in waste loading warehouses existent at the OTU and periodic evaluations of the external exposure rates (mR/h) are part of the 'Programa de Monitoracao Radiologica Ocupacional' of the unit. This paper presents a brief history of origins of this waste deposit and the material found there, and also the result of a routine monitoring of the external exposure rates

  7. Evaluation of integrity of radiation sources of nuclear gauges; Avaliacao da integridade de fontes radioativas de medidores nucleares

    Torohate, Wiclif Francisco

    2016-11-01

    Nuclear equipment meters are mainly used in the industry in quality control and process control. The principle of operation consists in a shielded radioactive source together with a radiation detector such that the radiation interacts with the material to be analyzed before reaching the detector, providing real time data. Can be as their fixed and mobile mobility, the unique properties of ionizing radiation are used in three basic modes, transmission, backscatter or dispersion or induced (reactive). With the advancement and technological modernization in the world, the demand for nuclear gauges becomes increasingly larger. Currently in Brazil there are about 465 process control plants and 21 portable systems and Mozambique about 45 facilities using nuclear gauges. This font registration is done through a process called source inventory that allows also to know the category of the source, the danger or risk to human health that the source offers. The handling of this equipment requires personnel, certified, skilled and well trained in radiation protection area in accordance with the requirements of the various CNEN Rules. Due to the presence of radioactive source and because these devices are used by workers risk because there external radiation. In this context, we made the smear test in two fixed meters from the IRD industry laboratory, which determines the integrity of the source package, mandatory item in periodic integrity testing of the radiation source of this type of device. A set of procedures is made for its implementation as an evaluation of the radiological risk by radiological survey. It was intended to contribute to the learning handling and safe use of these meters. (author)

  8. External exposure assessment in dwelling built with phosphogypsum; Avaliacao da exposicao externa em residencia construida com fosfogesso

    Villaverde, Freddy Lazo

    2008-07-01

    In this study it was evaluated the viability of the use of phosphogypsum plates as a building material in the dwelling construction. Thus, the effective dose due to external gamma exposure was assessed through the {sup 226}Ra, {sup 232}Th, {sup 210}Pb e {sup 40}K activity concentration in phosphogypsum plates. Samples of this material were analyzed by high resolution gamma spectrometry for their natural radionuclide activity concentration. The radium equivalent activity and extern ai and inter nai hazard indices were also calculated. The plates were made with phosphogypsum from fertilizer industries located in Cajati, Cubatao and Uberaba. The samples were identified according to phosphogypsum origin, Cajati (CA), Cubatao (CT) and Uberaba (UB). The activity concentrations results varied from 15.9 to 392 Bq kg{sup -1} for {sup 226}Ra, 26.1 to 253 Bq kg{sup -1} for {sup 232}Th, and 27.4 to 852 Bq kg{sup -1} for {sup 210}Pb. The results of {sup 40}K were lower than 81 Bq kg{sup -1}. The annual effective dose was obtained through the dosimetric model with reference standard room concept, the results were 0.02 mSv y{sup -1} for a house built with phosphogypsum from origin CA, 0.2 mSvy{sup -1} for CT phosphogypsum and 0.14 mSvy{sup -1} for UB phosphogypsum, everything the effective doses were below 1 mSvy{sup -1}, an annual effective dose limit for public exposure by International Commission on Radiological Protection. (author)

  9. Deodorant ceramic catalyst. Dasshu ceramics shokubai

    Arai, K. (Kobe Steel Ltd., Kobe (Japan)); Naka, R. (Hitachi Ltd., Tokyo (Japan))

    1993-07-01

    Concerning debromination to be used for the filter of deodorizing device, those of long life and high deodorizing performance are demanded a great deal. As one of this kind of debromination, a deodorant ceramic catalyst (mangantid) has been developed and put for practical use as deodorant for refrigerator. In this article, the information and knowledge obtained by the development of mangantid, the features as well as several properties of the product are stated. The deodorizing methods currently used practically are roughly divided into 6 kinds such as the adsorption method, the direct combustion method, the catalytic method and the oxidation method, but each of them has its own merit and demerit, hence it is necessary to select the method in accordance with the kind of odor and its generating condition. Mangantid is a compound body of high deodorant material in a honeycomb configuration, and has the features that in comparison with the existing deordorants, its pressure loss is smaller, its deodorizing rate is bigger, and acidic, neutral and basic gaseous components can be removed in a well-balanced manner. Deodorization with mangantid has the mechanism to let the odorous component contact and react with the catalyst and change the component to the non-odorous component in the temperature range from room temperature to the low temperature region. 5 refs., 11 figs., 1 tab.

  10. Micromolding for ceramic microneedle arrays

    van Nieuwkasteele-Bystrova, Svetlana Nikolajevna; Lüttge, Regina

    2011-01-01

    The fabrication process of ceramic microneedle arrays (MNAs) is presented. This includes the manufacturing of an SU-8/Si-master, its double replication resulting in a PDMS mold for production by micromolding and ceramic sintering. The robustness of the replicated structures was tested by means of

  11. Ceramics in nuclear waste management

    Chikalla, T D; Mendel, J E [eds.

    1979-05-01

    Seventy-three papers are included, arranged under the following section headings: national programs for the disposal of radioactive wastes, waste from stability and characterization, glass processing, ceramic processing, ceramic and glass processing, leaching of waste materials, properties of nuclear waste forms, and immobilization of special radioactive wastes. Separate abstracts were prepared for all the papers. (DLC)

  12. Science and Technology of Ceramics

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 12. Science and Technology of Ceramics - Functional Ceramics. Sheela K Ramasesha. Series Article Volume 4 Issue 12 December 1999 pp 21-30. Fulltext. Click here to view fulltext PDF. Permanent link:

  13. Science and Technology of Ceramics

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 8. Science and Technology of Ceramics - Traditional Ceramics. Sheela K Ramasesha. Series Article Volume 4 Issue 8 August 1999 pp 16-24. Fulltext. Click here to view fulltext PDF. Permanent link:

  14. Low thermal expansion glass ceramics

    1995-01-01

    This book is one of a series reporting on international research and development activities conducted by the Schott group of companies With the series, Schott aims to provide an overview of its activities for scientists, engineers, and managers from all branches of industry worldwide where glasses and glass ceramics are of interest Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated This volume describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics The composition, structure, and stability of polycrystalline materials having a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization Thus glass ceramics with thermal c...

  15. Ceramic membrane development in NGK

    Araki, Kiyoshi; Sakai, Hitoshi, E-mail: kinsakai@ngk.co.jp [Corporate R and D, NGK Insulators, Ltd., Nagoya 467-8530 (Japan)

    2011-05-15

    NGK Insulators, Ltd. was established in 1919 to manufacture the electric porcelain insulators for power transmission lines. Since then, our business has grown as one of the world-leading ceramics manufacturing companies and currently supply with the various environmentally-benign ceramic products to worldwide. In this paper, ceramic membrane development in NGK is described in detail. We have been selling ceramic microfiltration (MF) membranes and ultra-filtration (UF) membranes for many years to be used for solid/liquid separation in various fields such as pharmaceutical, chemical, food and semiconductor industries. In Corporate R and D, new ceramic membranes with sub-nanometer sized pores, which are fabricated on top of the membrane filters as support, are under development for gas and liquid/liquid separation processes.

  16. Ceramic membrane development in NGK

    Araki, Kiyoshi; Sakai, Hitoshi

    2011-05-01

    NGK Insulators, Ltd. was established in 1919 to manufacture the electric porcelain insulators for power transmission lines. Since then, our business has grown as one of the world-leading ceramics manufacturing companies and currently supply with the various environmentally-benign ceramic products to worldwide. In this paper, ceramic membrane development in NGK is described in detail. We have been selling ceramic microfiltration (MF) membranes and ultra-filtration (UF) membranes for many years to be used for solid/liquid separation in various fields such as pharmaceutical, chemical, food and semiconductor industries. In Corporate R&D, new ceramic membranes with sub-nanometer sized pores, which are fabricated on top of the membrane filters as support, are under development for gas and liquid/liquid separation processes.

  17. Method of forming a ceramic matrix composite and a ceramic matrix component

    de Diego, Peter; Zhang, James

    2017-05-30

    A method of forming a ceramic matrix composite component includes providing a formed ceramic member having a cavity, filling at least a portion of the cavity with a ceramic foam. The ceramic foam is deposited on a barrier layer covering at least one internal passage of the cavity. The method includes processing the formed ceramic member and ceramic foam to obtain a ceramic matrix composite component. Also provided is a method of forming a ceramic matrix composite blade and a ceramic matrix composite component.

  18. Zirconia based ceramics

    Bressiani, J.C.; Bressiani, A.H.A.

    1989-05-01

    Within the new generation of ceramic materials, zirconia continues to attract ever increasing attention of scients, technologists and users by virtue of its singular combination of properties and being able to perform thermo-mechanical, electroeletronic, chemico-biological functions. Nevertheless, in order to obtain these properties, a through understanding of the phase transformation mechanisms and microstructural changes is necessary. This paper discusses the main parameters that require control during fabrication of these materials to obtain desired properties for a specific application. (author) [pt

  19. Directionally Solidified Multifunctional Ceramics

    2006-12-01

    Vidrio , Vol. 44 [5] (2005) pp 347 - 352. 9. F. W. Dynys and A. Sayir, "Self Assemble Silicide Architectures by Directional Solidification," Journal...Sociedad Espanola de Ceramica y Vidrio , Vol. 43 [4] (2004) pp 753 - 758. 21. A. Sayir and F. S. Lowery, "Combustion-Resistance of Silicon-Based Ceramics...Espafiola de Cerdmica y Vidrio , Vol. 43 [3], 2004. ISSN-0366-3175-BSCVB9. 14 37. P. Berger, A. Sayir and M. H. Berger, "Nuclear Microprobe using Elastic

  20. Avaliação da resistência de união metalocerâmica em função de diferentes tempos de oxidação prévia Evaluation of the bond resistance between metal and ceramics, resulting from different previous oxidation times

    Stefan Fiuza de Carvalho DEKON

    1999-01-01

    Full Text Available Avaliou-se a resistência de união metal/porcelana utilizando-se uma liga de Ni-Cr, submetida a diferentes tempos de oxidação prévia com o sistema cerâmico Vita-VMK, através do teste preconizado por CHIODI NETTO3. A análise dos resultados permitiu as seguintes conclusões: a ausência da oxidação prévia possibilitou os melhores resultados, sendo que a diferença foi estatisticamente significante; diferentes tempos de oxidação prévia provocaram redução acentuada nos valores obtidos e foram semelhantes entre si; o grupo submetido ao processo de jateamento após a oxidação prévia por cinco minutos mostrou resultados similares aos grupos que também passaram pelo processo de oxidação e não sofreram jateamento posterior.The objective of this research was to evaluate the porcelain-alloy bonding strength using a local-made alloy under different times of pre-oxidation with a ceramic system. The test used was preconized by CHIODI NETTO. The results lead to the following conclusions: the control group (no pre-oxidation showed the best values, statistically significant, when compared with others groups. The different times of pre-oxidation procedures reduced the values significantly, and the groups were similar to each other. The group submitted to the sandblasting process after a pre-oxidation of 5 minutes, showed similar values when compared with the other groups treated with pre-oxidation without sandblasting.

  1. Formulation and synthesis by melting process of titanate enriched glass-ceramics and ceramics

    Advocat, T.; Fillet, C.; Lacombe, J.; Bonnetier, A.; McGlinn, P.

    1999-01-01

    The main objective of this work is to provide containment for the separated radionuclides in stable oxide phases with proven resistance to leaching and irradiation damage and in consequence to obtain a glass ceramic or a ceramic material using a vitrification process. Sphene glass ceramic, zirconolite glass ceramic and zirconolite enriched ceramic have been fabricated and characterized by XRD, SEM/EDX and DTA

  2. Caracterização dos argilominerais usados em matéria-prima cerâmica, da formação Rio do Rasto, Bacia do Paraná, no município de Turvo, SC Characterization of clay minerals used in the ceramic industry, from Rio do Rasto formation, Paraná basin, exploitation in Turvo, SC, Brazil

    J. A. Costa

    2010-12-01

    Full Text Available No sudeste de Santa Catarina existem inúmeras minas de exploração de argilas destinadas à indústria cerâmica da região. Para o conhecimento desta matéria prima foi realizada a caracterização em detalhe de uma frente de lavra em atividade. A exploração é realizada em terrenos sedimentares da Formação Rio do Rasto (Permiano Superior na Bacia do Paraná que afloram como morros testemunho. Foram coletadas quatorze amostras representativas dos níveis desta mina composta de argilitos com intercalação de siltitos de pequena espessura. As amostras foram analisadas por difratometria de raios X pelo método do pó na rocha total e na fração In the southeastern part of Santa Catarina state, Brazil, many mines of clays used as raw material for the ceramic industry are found. A detail study of this material was developed in a mine in activity. The exploitation of clays is held in sedimentary rocks of Rio do Rasto Formation (Upper Permian in the Paraná Basin. The outcrops are in hills testimonies. Fourteen samples were collected and represent the levels of this mine which consisted of argillites with intercalation of slim siltite layer. These samples were analyzed by X-ray diffraction using the powder method and in the fraction < 4 µm. The chemical composition was determined by X-ray fluorescence spectrometer. Petrographic observations in thin section were also performed. Scanning electron microscope images was obtained in samples fragments by secondary electron method. Electron microprobe microanalysis was performed in one thin section. The results showed large vertical variation in the mineralogy and it has been identified three different levels. Up to 2.00 m there is a predominance of smectite. Between 5.50 m 2.00 m the smectite is the main clay mineral, but with significant amounts of illite/mica and above 5.50 m occurs large increase in K-feldspar and detrital mica. Studies in detail by X-ray diffraction (determination of the b

  3. Nano-ceramics and its molding technologies

    Liu Jian; Xu Yunshu

    2007-01-01

    Nano-ceramics and its related knowledge were introduced. Fabrication of nano-ceramic powder, as well as the molding and sintering technologies of nano-ceramics were reviewed. Features of the present molding technologies were analyzed. The applications of nano-ceramics were prospected. (authors)

  4. Preparation of 147Pm ceramic source core

    Mielcarski, M.

    1989-01-01

    Preparation of ceramic pellets containing fixed promethium-147 is described. Incorporation rate of 147 Pm into the ceramic material was determined. The leachability and vaporization of promethium from the obtained ceramics was investigated. The ceramic pellets prepared by the described procedure, mounted in special holders, can be applied as point sources in beta backscatter thickness gauges. (author)

  5. Development of optical phase shifter based on piezoelectric ceramic

    Yu, Fusheng; Shen, Xiaoqin; Yao, Chunjuan; Leng, Changlin

    2005-02-01

    The phase shifter is necessary in the optical phase-shifting measurement. At present the phase shifter commonly used is approximately divided into the penetrance-type and the reflection-type. In this paper, a reflection-type phase shifter made of piezoelectric ceramic stackup assemble is developed. The assemble are constituted of the flat piezoelectric ceramic with parallel connection circuit and inline structure. The communication between the computer and MCU is by RS232. The D/A converter controlled by the MCU outputs 0~10V voltage. Then the voltage is amplified to 0~400V DC voltage by the designed linear DC amplifier. When this voltage loads on the piezoelectric ceramic stackup assemble, the assemble will axially extend 0~5mm. In this paper, the connecting types for the mechanical construction and circuit of the piezoelectric ceramic stackup assemble, the driving power and the DC amplifier with high linearity are all introduced. The whole system developed is standardized by using phase-interfering Michelson. The standardization and the practical application indicates that this system has excellent linearity and precision repeatability.

  6. Fibrous monolithic ceramics

    Kovar, D.; King, B.H.; Trice, R.W.; Halloran, J.W.

    1997-01-01

    Fibrous monolithic ceramics are an example of a laminate in which a controlled, three-dimensional structure has been introduced on a submillimeter scale. This unique structure allows this all-ceramic material to fail in a nonbrittle manner. Materials have been fabricated and tested with a variety of architectures. The influence on mechanical properties at room temperature and at high temperature of the structure of the constituent phases and the architecture in which they are arranged are discussed. The elastic properties of these materials can be effectively predicted using existing models. These models also can be extended to predict the strength of fibrous monoliths with an arbitrary orientation and architecture. However, the mechanisms that govern the energy absorption capacity of fibrous monoliths are unique, and experimental results do not follow existing models. Energy dissipation occurs through two dominant mechanisms--delamination of the weak interphases and then frictional sliding after cracking occurs. The properties of the constituent phases that maximize energy absorption are discussed. In this article, the authors examine the structure of Si 3 N 4 -BN fibrous monoliths from the submillimeter scale of the crack-deflecting cell-cell boundary features to the nanometer scale of the BN cell boundaries

  7. Ceramic fiber reinforced filter

    Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

    1991-01-01

    A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

  8. Ceramic drug-delivery devices.

    Lasserre, A; Bajpai, P K

    1998-01-01

    A variety of ceramics and delivery systems have been used to deliver chemicals, biologicals, and drugs at various rates for desired periods of time from different sites of implantation. In vitro and in vivo studies have shown that ceramics can successfully be used as drug-delivery devices. Matrices, inserts, reservoirs, cements, and particles have been used to deliver a large variety of therapeutic agents such as antibiotics, anticancer drugs, anticoagulants, analgesics, growth factors, hormones, steroids, and vaccines. In this article, the advantages and disadvantages of conventional drug-delivery systems and the different approaches used to deliver chemical and biological agents by means of ceramic systems will be reviewed.

  9. High flow ceramic pot filters

    van Halem, D.; van der Laan, H.; Soppe, A. I.A.; Heijman, S.G.J.

    2017-01-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6–19 L h−1), but initial LRVs for E. coli o...

  10. Hardness of ion implanted ceramics

    Oliver, W.C.; McHargue, C.J.; Farlow, G.C.; White, C.W.

    1985-01-01

    It has been established that the wear behavior of ceramic materials can be modified through ion implantation. Studies have been done to characterize the effect of implantation on the structure and composition of ceramic surfaces. To understand how these changes affect the wear properties of the ceramic, other mechanical properties must be measured. To accomplish this, a commercially available ultra low load hardness tester has been used to characterize Al 2 O 3 with different implanted species and doses. The hardness of the base material is compared with the highly damaged crystalline state as well as the amorphous material

  11. Porous ceramics out of oxides

    Bakunov, V.S.; Balkevich, V.L.; Vlasov, A.S.; Guzman, I.Ya.; Lukin, E.S.; Poluboyarinov, D.N.; Poliskij, R.Ya.

    1977-01-01

    A review is made of manufacturing procedures and properties of oxide ceramics intended for high-temperature thermal insulation and thermal protection applications. Presented are structural characteristics of porous oxide refractories and their properties. Strength and thermal conductivity was shown to depend upon porosity. Described is a procedure for manufacturing porous ceramic materials from aluminium oxide, zirconium dioxide, magnesium oxide, beryllium oxide. The thermal resistance of porous ceramics from BeO is considerably greater than that of other high-refractoriness oxides. Listed are areas of application for porous materials based on oxides

  12. Agglomeration of ceramic powders

    Cawley, James D.; Larosa, Judith; Dirkse, Fredrick

    1989-01-01

    A research program directed at a critical comparison of numerical models for power agglomeration with experimental observations is currently underway. Central to this program is the quantitative characterization of the distribution of mass within an agglomerate as a function of time. Current experiments are designed to restrict agglomeration to a surface, which is oriented perpendicular to the force of gravity. These experiments are discussed with reference to: their significance to ceramic processing; artifacts which may be avoided in microgravity experiments; and the comparison of information available in real space (from optical microscopy) to that in reciprocal space (from light scattering). The principle machine requirement appears to be a need to obtain information at small scattering angles.

  13. Creep in electronic ceramics

    Routbort, J. L.; Goretta, K. C.; Arellano-Lopez, A. R.

    2000-04-27

    High-temperature creep measurements combined with microstructural investigations can be used to elucidate deformation mechanisms that can be related to the diffusion kinetics and defect chemistry of the minority species. This paper will review the theoretical basis for this correlation and illustrate it with examples from some important electronic ceramics having a perovskite structure. Recent results on BaTiO{sub 3}, (La{sub 1{minus}x}Sr){sub 1{minus}y}MnO{sub 3+{delta}}, YBa{sub 2}Cu{sub 3}O{sub x}, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x}, (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} and Sr(Fe,Co){sub 1.5}O{sub x} will be presented.

  14. Ceramics for fusion devices

    Clinard, F.W. Jr.

    1984-01-01

    Ceramics are required for a number of applications in fusion devices, among the most critical of which are magnetic coil insulators, windows for RF heating systems, and structural uses. Radiation effects dominate consideration of candidate materials, although good pre-irradiation properties are a requisite. Materials and components can be optimized by careful control of chemical and microstructural content, and application of brittle material design and testing techniques. Future directions for research and development should include further extension of the data base in the areas of electrical, structural, and thermal properties; establishment of a fission neutron/fusion neutron correlation including transmutation gas effects; and development of new materials tailored to meet the specific needs of fusion reactors

  15. Moessbauer studies of Inca ceramics

    Wagner, U.; Wagner, F.E.; Marticorena, B.; Salazar, R.; Schwabe, R.; Riederer, J.

    1986-01-01

    To obtain information on the firing of Inca ceramics, 7 samples from different locations were studied by Moessbauer spectroscopy including a detailed laboratory refiring procedure. The glaze typical for the surface of this ware was studied by Moessbauer scattering. (Auth.)

  16. Non destructive evaluation of ceramics

    Green, R.E. Jr

    1992-01-01

    While monolithic and composite ceramics have been successfully manufactured, inconsistencies in processing and the unpredictable nature of their failure have limited their use as engineering materials. The optimization of the processing and properties of ceramics and the structures, devices and systems made from them demand the innovative application of modern nondestructive materials characterization techniques to monitor and control as many stages of the production process as possible. This paper will describe the state-of-the-art of nondestructive evaluation techniques for characterization of monolithic ceramics and ceramic composites. Among the techniques to be discussed are laser ultrasonics, acoustic microscopy, thermography, microfocus and x-ray tomography, and micro-photoelasticity. Application of these and other nondestructive evaluation techniques for more effective and efficient real-time process control will result in improved product quality and reliability. 27 refs

  17. Low Thermal Expansion Glass Ceramics

    Bach, Hans

    2005-01-01

    This book appears in the authoritative series reporting the international research and development activities conducted by the Schott group of companies. This series provides an overview of Schott's activities for scientists, engineers, and managers from all branches of industry worldwide in which glasses and glass ceramics are of interest. Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated. This new extended edition describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics. The composition, structure, and stability of polycrystalline materials having a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions. Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization. Thus g...

  18. Inorganic glass ceramic slip rings

    Glossbrenner, E. W.; Cole, S. R.

    1972-01-01

    Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours.

  19. Metal-ceramic joint assembly

    Li, Jian

    2002-01-01

    A metal-ceramic joint assembly in which a brazing alloy is situated between metallic and ceramic members. The metallic member is either an aluminum-containing stainless steel, a high chromium-content ferritic stainless steel or an iron nickel alloy with a corrosion protection coating. The brazing alloy, in turn, is either an Au-based or Ni-based alloy with a brazing temperature in the range of 9500 to 1200.degree. C.

  20. Multiphase-Multifunctional Ceramic Coatings

    2013-06-30

    systems for high temperatura applications” “ Estudios de Ferroelasticidad en Sistemas Cerámicos Multifásicos para Aplicaciones en Alta Temperatura ...Ceramic Coatings Performing Organization names: Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional – Unidad Queretaro...materials, Cinvestav. Thesis: “Ferroelasticity studies in multiphase ceramic systems for high temperatura applications”. Her work mainly focused in the

  1. Nano-Ceramic Coated Plastics

    Cho, Junghyun

    2013-01-01

    Plastic products, due to their durability, safety, and low manufacturing cost, are now rapidly replacing cookware items traditionally made of glass and ceramics. Despite this trend, some still prefer relatively expensive and more fragile ceramic/glassware because plastics can deteriorate over time after exposure to foods, which can generate odors, bad appearance, and/or color change. Nano-ceramic coatings can eliminate these drawbacks while still retaining the advantages of the plastic, since the coating only alters the surface of the plastic. The surface coating adds functionality to the plastics such as self-cleaning and disinfectant capabilities that result from a photocatalytic effect of certain ceramic systems. These ceramic coatings can also provide non-stick surfaces and higher temperature capabilities for the base plastics without resorting to ceramic or glass materials. Titanium dioxide (TiO2) and zinc oxide (ZnO) are the candidates for a nano-ceramic coating to deposit on the plastics or plastic films used in cookware and kitchenware. Both are wide-bandgap semiconductors (3.0 to 3.2 eV for TiO2 and 3.2 to 3.3 eV for ZnO), so they exhibit a photocatalytic property under ultraviolet (UV) light. This will lead to decomposition of organic compounds. Decomposed products can be easily washed off by water, so the use of detergents will be minimal. High-crystalline film with large surface area for the reaction is essential to guarantee good photocatalytic performance of these oxides. Low-temperature processing (nano-ceramic coatings (TiO2, ZnO) on plastic materials (silicone, Teflon, PET, etc.) that can possess both photocatalytic oxide properties and flexible plastic properties. Processing cost is low and it does not require any expensive equipment investment. Processing can be scalable to current manufacturing infrastructure.

  2. Method for preparing ceramic composite

    Alexander, K.B.; Tiegs, T.N.; Becher, P.F.; Waters, S.B.

    1996-01-09

    A process is disclosed for preparing ceramic composite comprising blending TiC particulates, Al{sub 2}O{sub 3} particulates and nickel aluminide and consolidating the mixture at a temperature and pressure sufficient to produce a densified ceramic composite having fracture toughness equal to or greater than 7 MPa m{sup 1/2}, a hardness equal to or greater than 18 GPa. 5 figs.

  3. Fracture-dissociation of ceramic liner.

    Hwang, Sung Kwan; Oh, Jin-Rok; Her, Man Seung; Shim, Young Jun; Cho, Tae Yeun; Kwon, Sung Min

    2008-08-01

    The use of BIOLOX delta ceramic (CeramTec AG, Plochingen, Germany) has been increasing. This ceramic prevents cracking by restraining the phase transformation due to the insertion of nano-sized, yttria-stabilized tetragonal zirconia into the alumina matrix. This restrains the progress of cracking through the formation of platelet-like crystal or whiskers due to the addition of an oxide additive. We observed a case of BIOLOX delta ceramic liner (CeramTec AG) rim fracture 4 months postoperatively. Radiographs showed that the ceramic liner was subluxated from the acetabular cup. Scratches on the acetabular cup and femoral neck were seen, and the fracture was visible on the rim of the liner. Under electron microscope, metal particle coatings from the ceramic liner were identified. The ceramic liner, fracture fragments, and adjacent tissues were removed and replaced with a ceramic liner and femoral head of the same size and design. We believe the mechanism of the fracture-dissociation of the ceramic liner in this case is similar to a case of separation of the ceramic liner from the polyethylene shell in a sandwich-type ceramic-ceramic joint. To prevent ceramic liner fracture-dissociation, the diameter of the femoral neck needs to be decreased in a new design, while the diameter of the femoral head needs to be increased to ensure an increase in range of motion.

  4. Análise da co-utilização do resíduo do beneficiamento do caulim e serragem de granito para produção de blocos e telhas cerâmicos Analysis of the use of kaolin processing waste and granite sawing waste together for the production of ceramic bricks and roof tiles

    R. R. Menezes

    2007-06-01

    Full Text Available O volume de resíduos gerado pela mineração e o beneficiamento mineral vêm se intensificando a cada dia, em virtude do aumento da demanda causado pelo crescimento da economia mundial. As indústrias do beneficiamento do caulim e da serragem do granito são importantes segmentos econômicos do Estado da Paraíba, entretanto produzem enormes quantidades de resíduos. Assim, este trabalho tem por objetivo caracterizar os resíduos do beneficiamento do caulim e da serragem do granito e avaliar a viabilidade de sua co-utilização para produção de blocos e telhas cerâmicos. Os resíduos foram caracterizados através da determinação de sua composição química e mineralógica, pelo uso de difração de raios X e análise térmica diferencial e gravimétrica, distribuição e tamanho de partículas e análise morfológica por microscopia eletrônica de varredura. Foram formuladas composições contendo os resíduos e confeccionados corpos de prova por extrusão. Os corpos de prova foram queimados e em seguida determinou-se sua absorção de água e módulo de ruptura à flexão. Pode-se observar que o resíduo do caulim é constituído por caulinita, mica e quartzo, que o resíduo de granito é constituído por quartzo, mica, albita e calcita e, que os resíduos apresentam distribuições granulométricas significativamente diferentes. Concluiu-se também que é possível a incorporação de até 50% de resíduo em formulações para produção de blocos e telhas cerâmicas e que a co-utilização do resíduo de granito e de caulim possibilita obter propriedades físicas superiores às observadas nos corpos de prova com incorporação de apenas resíduo de caulim.The amount of wastes generated by the miner and mineral processing industries has increasing day by day due to the high demand cause by the global economy grow up. The processing kaolin ad sawing granite industries are important economic segments in the state of Paraíba, but generate

  5. Ceramics as nuclear reactor fuels

    Reeve, K.D.

    1975-01-01

    Ceramics are widely accepted as nuclear reactor fuel materials, for both metal clad ceramic and all-ceramic fuel designs. Metal clad UO 2 is used commercially in large tonnages in five different power reactor designs. UO 2 pellets are made by familiar ceramic techniques but in a reactor they undergo complex thermal and chemical changes which must be thoroughly understood. Metal clad uranium-plutonium dioxide is used in present day fast breeder reactors, but may eventually be replaced by uranium-plutonium carbide or nitride. All-ceramic fuels, which are necessary for reactors operating above about 750 0 C, must incorporate one or more fission product retentive ceramic coatings. BeO-coated BeO matrix dispersion fuels and silicate glaze coated UO 2 -SiO 2 have been studied for specialised applications, but the only commercial high temperature fuel is based on graphite in which small fuel particles, each coated with vapour deposited carbon and silicon carbide, are dispersed. Ceramists have much to contribute to many aspects of fuel science and technology. (author)

  6. Microwave sintering of ceramic materials

    Karayannis, V. G.

    2016-11-01

    In the present study, the potential of microwave irradiation as an innovative energy- efficient alternative to conventional heating technologies in ceramic manufacturing is reviewed, addressing the advantages/disadvantages, while also commenting on future applications of possible commercial interest. Ceramic materials have been extensively studied and used due to several advantages they exhibit. Sintering ceramics using microwave radiation, a novel technology widely employed in various fields, can be an efficient, economic and environmentally-friendlier approach, to improve the consolidation efficiency and reduce the processing cycle-time, in order to attain substantial energy and cost savings. Microwave sintering provides efficient internal heating, as energy is supplied directly and penetrates the material. Since energy transfer occurs at a molecular level, heat is generated throughout the material, thus avoiding significant temperature gradients between the surface and the interior, which are frequently encountered at high heating rates upon conventional sintering. Thus, rapid, volumetric and uniform heating of various raw materials and secondary resources for ceramic production is possible, with limited grain coarsening, leading to accelerated densification, and uniform and fine-grained microstructures, with enhanced mechanical performance. This is particularly important for manufacturing large-size ceramic products of quality, and also for specialty ceramic materials such as bioceramics and electroceramics. Critical parameters for the process optimization, including the electromagnetic field distribution, microwave-material interaction, heat transfer mechanisms and material transformations, should be taken into consideration.

  7. Method for Waterproofing Ceramic Materials

    Cagliostro, Domenick E. (Inventor); Hsu, Ming-Ta S. (Inventor)

    1998-01-01

    Hygroscopic ceramic materials which are difficult to waterproof with a silane, substituted silane or silazane waterproofing agent, such as an alumina containing fibrous, flexible and porous, fibrous ceramic insulation used on a reentry space vehicle, are rendered easy to waterproof if the interior porous surface of the ceramic is first coated with a thin coating of silica. The silica coating is achieved by coating the interior surface of the ceramic with a silica precursor converting the precursor to silica either in-situ or by oxidative pyrolysis and then applying the waterproofing agent to the silica coated ceramic. The silica precursor comprises almost any suitable silicon containing material such as a silane, silicone, siloxane, silazane and the like applied by solution, vapor deposition and the like. If the waterproofing is removed by e.g., burning, the silica remains and the ceramic is easily rewaterproofed. An alumina containing TABI insulation which absorbs more that five times its weight of water, absorbs less than 10 wt. % water after being waterproofed according to the method of the invention.

  8. Índices bióticos para avaliação da qualidade ambiental em trechos do rio Correntoso, Pantanal do Negro, Estado do Mato Grosso do Sul, Brasil = Biotic indexes for the evaluation of environmental quality in stretches of the Correntoso river, Pantanal do Negro, Mato Grosso do Sul State, Brazil

    Fábio Henrique da Silva

    2011-07-01

    Full Text Available Este trabalho teve como objetivo pesquisar a estrutura da comunidade de insetos aquaticos, utilizando esta comunidade como indicadora da qualidade ambiental de um trecho do rio Correntoso, Pantanal do Negro, Mato Grosso do Sul, Brasil. Foram realizadas seis campanhas de coleta em diferentes periodos sazonais: vazante, seca e cheia. Os organismos foram coletados utilizando rede D com malha de 300 ƒÝm eesforco amostral de cinco lances de rede nas raizes dos bancos de macrofitas. Foram comparados tres ambientes (aberto, intermediario e fechado, por juncao dos dados obtidos de seis sitios de coleta. Foi analisada a riqueza, abundancia absoluta e relativa das familias de insetos amostrados e a avaliacao da qualidade da agua usando o indiceBMWP, indice BMWP-ASPT, indice IBF e indice de diversidade de Shannon-Wienner, com log2. Foram registradas 60 familias pertencentes a 12 ordens da Classe Insecta, totalizando 19.773 individuos coletados. Entre os indices aplicados, o indice BMWP foi o que melhor representou as condicoes do ambiente estudado.This work aimed to research the aquatic insect community structure using this community as a bioindicator of the environmental quality in a stretch of the Correntoso river, in Pantanal do Negro, Mato Grosso do Sul, Brazil. Six collections were taken in different seasonal periods; ebb, dry and wet. The organisms were collected using a 300 ƒÝm mesh D net sweeping five times through the roots of macrophyte banks at each sample. Three environments were compared (open, intermediary, closed by adding the information from six collection sites. Family richness, absolute and relative abundance ofinsect samples and an evaluation of water quality were analyzed by using the BMWP index, BMWP-ASPT index, IBF index and Shannon diversity index, with log2. A total of 60 families from 12 orders of Insecta Class were recorded, totaling 19,773 individuals. Among the indexes applied, the BMWP index was the one that best

  9. Design and In-Situ Processing of Metal-Ceramic and Ceramic-Ceramic Microstructures

    Sass, Stephen

    1997-01-01

    .... Metal-ceramic microstructures have been synthesized in situ by a variety of novel processing techniques, including the partial reduction of oxide compounds and displacement reactions and sol-gel...

  10. FOREWORD: Focus on Advanced Ceramics Focus on Advanced Ceramics

    Ohashi, Naoki

    2011-06-01

    Much research has been devoted recently to developing technologies for renewable energy and improving the efficiency of the processes and devices used in industry and everyday life. Efficient solutions have been found using novel materials such as platinum and palladium-based catalysts for car exhaust systems, samarium-cobalt and neodymium-iron-boron permanent magnets for electrical motors, and so on. However, their realization has resulted in an increasing demand for rare elements and in their deficit, the development of new materials based on more abundant elements and new functionalities of traditional materials. Moreover, increasing environmental and health concerns demand substitution of toxic or hazardous substances with nature-friendly alternatives. In this context, this focus issue on advanced ceramics aims to review current trends in ceramics science and technology. It is related to the International Conference on Science and Technology of Advanced Ceramics (STAC) held annually to discuss the emerging issues in the field of ceramics. An important direction of ceramic science is the collaboration between experimental and theoretical sciences. Recent developments in density functional theory and computer technology have enabled the prediction of physical and chemical properties of ceramics, thereby assisting the design of new materials. Therefore, this focus issue includes articles devoted to theory and advanced characterization techniques. As mentioned above, the potential shortage of rare elements is becoming critical to the industry and has resulted in a Japanese government initiative called the 'Ubiquitous Element Strategy'. This focus issue also includes articles related to this strategy and to the associated topics of energy conversion, such as phosphors for high-efficiency lighting and photocatalysts for solar-energy harvesting. We hope that this focus issue will provide a timely overview of current trends and problems in ceramics science and

  11. All-ceramic crowns: bonding or cementing?

    Pospiech, Peter

    2002-12-01

    Despite the wide variety of all-ceramic systems available today, the majority of dental practitioners hesitate to recommend and insert all-ceramic crowns. This article regards the nature of the ceramic materials, the principles of bonding and adhesion, and the clinical problems of the acid-etch technique for crowns. Advantages and disadvantages are discussed, and the influences of different factors on the strength of all-ceramic crowns are presented. Finally, the conclusion is drawn that conventional cementing of all-ceramic crowns is possible when the specific properties of the ceramics are taken into consideration.

  12. Exoelectron emission from magnesium borate glass ceramics

    Kawamoto, Takamichi; Yanagisawa, Hideo; Nakamichi, Hiroshi; Kikuchi, Riichi; Kawanishi, Masaharu.

    1986-01-01

    Thermally stimulated exoelectron emission (TSEE) of a magnesium borate glass ceramics was investigated for its application to dosemetric use. It has been found that the TSEE glow patterns of the magnesium borate glass ceramics as well as a Li 2 B 4 O 7 glass ceramics depend on the kind of the radiation used and that the heat resistance of the magnesium borate glass ceramics is higher than that of the Li 2 B 4 O 7 glass ceramics. Therefore, the TSEE glow patterns of the magnesium borate glass ceramics indicate a possibility to be used as the dose measurement for each kind of radiation in the mixed radiation field. (author)

  13. Producing ceramic laminate composites by EPD

    Nicholson, P.S.; Sarkar, P.; Datta, S.

    1996-01-01

    The search for tough structural ceramics to operate at high temperatures in hostile environments has led to the development of ceramic composites. This class of material includes laminar ceramic-ceramic composites, continuous-fiber-reinforced ceramic composites and functionally graded materials. The present authors developed electrophoretic deposition (EPD) to synthesize lamellar, fiber-reinforced and functionally graded composites. This paper briefly describes the synthesis and characterization of these EPD composites and introduces a novel class of lamellar composites with nonplanar layers. The synthesis of the latter demonstrates the facility of the EPD process for the synthesis of ceramic composites. The process is totally controllable via suspension concentration, deposition current, voltage and time

  14. Production by thermo-mechanical process and stability in crude petroleum studies of Ba{sub 2}AlZrO{sub 5,5} ceramics; Producao por processo termo-mecanico e estudos de estabilidade em petroleo cru da ceramica Ba{sub 2}AlZrO{sub 5,5}

    Yadava, Y.P.; Bezerra, L.P.; Ferreira, R.A.S., E-mail: yadava@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Engenharia Mecanica

    2010-07-01

    The necessity of developing technologies that makes possible the petroleum wells exploration is very important. Knowing that those are hostile environments is necessary ta find materials that are able to resist to those environment conditions. In this way we worked on the fabrication of ceramic embedding temperature sensors for petroleum industry. The present work looks for the fabrication of Ba{sub 2}AlZrO{sub 5,5} ceramic by thermo-mechanical process and the study of it's stability in crude petroleum. The Ba{sub 2}AlZrO{sub 5,5} was fabricated by thermo-mechanical process. The ceramic powder was calcined and then the granulometry was analyzed by laser. The samples were compacted, sintered and the microstructure and mechanical properties were characterized. The ceramic stability study in crude petroleum was done and the ceramic was analyzed by X-Ray diffraction and Vickers micro hardness The results shows that the ceramic is stable in crude petroleum. (author)

  15. Quality evaluation of Argentina onion irradiated, transported and stored; Avaliacao da qualidade da cebola argentina irradiada, transportada e armazenada no Brasil

    Walder, J M.M.; Domarco, R E; Spoto, M H.F.; Blumer, L [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil); Curzio, O A; Croci, C A [Universidad Nacional del Sur, Bahia Blanca (Argentina). Lab. de Radioisotopos

    1996-12-31

    Onion bulbs of the Valenciana Sintetica 14 variety from Argentina were irradiated with a dose of 60 Gy gamma rays at 30-40 days after harvest. Treated and control lots (40 bags of 20 Kg each) were send by road to Piracicaba, SP, Brazil, and stored up to 180 days in a warehouse at 20-28{sup 0} C and relative humidity ranging from 50 to 100%. Monthly quality control was done by physical and sensorial analysis. Radiation treatment reduced the weight loss of the bulbs and increased the percentage of marketable bulbs without affecting its sensorial properties. (author). 4 refs, 8 tabs.

  16. Ribeira do Iguape basin water quality assessment for drinking water supply; Avaliacao da qualidade da agua na bacia hidrografica do Ribeira de Iguape com vistas ao abastecimento publico

    Cotrim, Marycel Elena Barboza

    2006-07-01

    Ribeira do Iguape Basin, located in the Southeast region of Sao Paulo state, is the largest remaining area of Mata Atlantica which biodiversity as rich as Amazon forest , where the readiness of water versus demand is extremely positive. With sparse population density and economy almost dependent on banana agriculture, the region is still well preserved. To water supply SABESP (Sao Paulo State Basic Sanitation Company). Ribeira do Iguape Businesses Unit - RR, uses different types of water supplies. In the present work, in order to ascertain water quality for human consumption, major and minor elements were evaluated in various types of water supply (surface and groundwater's as well as the drinking water supplied). Forty three producing systems were monitored: 18 points of surface waters and treated distributed water, 10 points of groundwater and 15 points of surface water in preserved areas, analyzing 30 elements. Bottom sediments (fraction < 63 {mu}m) were also evaluated. The sampling period covered dry and wet seasons from March 2002 to February 2003. The descriptive analysis showed that Al, Fe and Mn, exceeding CONAMA 357 quality guideline. A comparison of the elemental concentrations with the Brazilian Drinking Water Legislation (Portaria 518/04) showed that with the exception of some violations, the levels of all the elements investigated were below the Brazilian Legislation maximum allowed concentrations. This study examined the relationship between the type of water supply and the quality of water used, showed different characteristics on Ca, Fe, Mn concentration. In bottom sediments (fraction <63 {mu}m), Al, Fe and Mg largest concentrations were found. Pb and Zn presents concentrations up to 142,0 {mu}g.g{sup -1} and 172 {mu}g.g{sup -1}, respectively. Data revealed that trace elements concentration in the sediment were below PEL (Probable Effect Level - probable level of adverse effect to the biological community), exception for Pb in Sete Barras and Eldorado. (author)

  17. Density evaluation by computerized tomography in plain soils over different manipulation systems; Avaliacao da densidade pelo metodo da tomografia computadorizada de um planossolo sob diferentes sistemas de manejo

    Pedrotti, Alceu [Lavras Univ., MG (Brazil). Dept. de Ciencia do Solo; Pauletto, Eloy Antonio [Pelotas Univ., RS (Brazil). Dept. de Solos; Crestana, Silvio [Empresa Brasileira de Pesquisa Agropecuaria (EMBRAPA), Sao Carlos, SP (Brazil). Centro Nacional de Pesquisa e Desenvolvimento de Instrumentacao Agropecuaria (CNPDIA)

    1996-08-01

    The objective of this paper is the evaluation of a plain soil density in different culture systems determined by X ray computerized tomography.It was observed a larger variation in densities in soils profiles analysed. The identification of layers is better utilising computerized tomography than others technic 1 fig.

  18. Assessing the quality of energy supplied by small renewable energy systems; Avaliacao da qualidade da energia fornecida por sistemas renovaveis isolados de pequeno porte

    Galhardo, Marcos Andre Barros; Pinho, Joao Tavares [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Grupo de Estudos e Desenvolvimento de Alternativas Energeticas], e-mail: galhardo@ufpa.br, E-mail: jtpinho@ufpa.br

    2004-07-01

    This paper makes an analysis of the power quality supplied by small renewable energy systems with energy storage in a battery bank and its DC/AC conversion by an inverter. It is shown that the power quality supplied by stand-alone renewable systems depends on the used inverter, specially of its voltage waveform, the load supplied and the voltage level in the battery bank, which has a direct influence on the value of the rms output voltage of the inverter. For these analysis, measurements are presented for typical loads used in these systems as illumination, TV, refrigerator, etc., and combinations of these loads, supplied by different waveforms. (author)

  19. Study and evaluation of radiometry in photo therapeutic treatment of the neonatal hyperbilirubinaemia; Estudo e avaliacao da radiometria no tratamento fototerapico da hiperbilirrubinemia neonatal

    Caly, Jose Pucci

    2009-07-01

    Phototherapy is a procedure established more than 50 years ago in the treatment of the newborn jaundice. However there is no a standard method to quantify the photo therapeutic dose in published clinical studies, hindering the comparison of previous studies on photo therapeutic effectiveness, as well as the establishment of safe and predictable doses. The photo therapeutic dose depends, among other factors, on the effective mean irradiance produced by the photo therapeutic unit. There are no standard procedures, however, neither to quantify the effective irradiance, nor to estimate the mean effective irradiance. As a consequence, large measurement variations in a same photo therapeutic unit are observed using different commercially available radiometers, as a consequence of the vast diversity of spectral responsivities of the instruments. An objective of this work was to adapt and to apply the bases of the wideband ultraviolet radiometry to quantify the available irradiance from photo therapeutic units, establishing procedures that allow us to compare measured irradiances from different sources, using radiometers presenting different spectral responsivities. Another objective was to characterize samples of photo therapeutic units commonly used, focusing the problem of the estimation of the effective mean irradiance from photo therapeutic units, proposing a method to estimate of the effective irradiance from focused sources. The experimental results allow us to conclude that it is not only necessary to standardize the photo therapeutic radiometry, but also the method of estimation of the effective mean irradiance. (author)

  20. Evaluation of X ray attenuation by means of radiographic images; Avaliacao da atenuacao da radiacao X por meio de imagens radiograficas

    Barros, Frieda Saicla, E-mail: saicla@utfpr.edu.b [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Paredes, Ramon S.C., E-mail: ramon@ufpr.b [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil); Godoi, Walmor C., E-mail: walmor.godoi@gmail.co [Faculdade de Tecnologia Camoes (FATEC), Curitiba, PR (Brazil); Souza, Gabriel Pinto de [Universidade Estadual Paulista (UNESP), SP (Brazil)

    2011-07-01

    This paper's main goal is to adopt a qualitative methodology to evaluate the attenuation of x-radiation through X-ray images in polymeric materials plus residual lead. To determinate the images it was initially used an experimental setup at the Laboratory for Materials Diagnostics LACTEC. These results correspond to a more qualitative analysis, even with quantitative answers. Through analysis of radiographic images we can measure the intensity of radiation that goes through the plate, making possible to establish a relationship between the attenuation coefficient and the thickness of the material. (author)

  1. Evaluation of the morphological alteration of the root surface radiated with a diode laser; Avaliacao da alteracao morfologica da superficie cimentaria irradiada com laser de diodo

    Gulin, Mauricio

    2003-07-01

    The diode laser has been studied for periodontal therapy, as much for removal of calculus as for microbial reduction of periodontal pockets, as well as the visible analgesic effects and biomodulation capacity. For this reason the purpose of this study was to evaluate the morphological alteration of the root surface after radiation with the diode laser, 808 nm through analysis by scanning electron microscopy (SEM). Besides this, to verify the temperature variations caused during the radiation, a thermometer put into the dentinal wall of the root canal was used. In all, 18 teeth were used, 15 of which for the SEM study, and the other 3 were used to temperature variation analysis. The 25 samples were scraped on the root surface and planed with manual instruments. The other 5 were not subjected to any type of treatment. This, 6 groups of 5 samples each were formed. Control Group C whose samples had not received any treatment; Control Group C 1 was only scraped and polished conventionally with Hu-Friedy Gracey curettes 5 and 6; the other samples groups L1, L2, L3, L4 were radiated by diode laser using parameters of power 1,0 W; 1,2 W; 1,4 W; and 1,6 W respectively, 2 times for 10 seconds with 20 seconds intervals between each radiation in continuous mode. The results with relation to the increase of temperature in the interior of the root canal demonstrated that there was an increase of more than 5 degree Celsius. The results of the scanning electron microscope analysis of Control Group C demonstrated great irregularity and ridges on the root surface, with the presence of a dentine layer. Control Group C1 presented a similar aspect to Group L 1's, smoother and more homogeneous surface. Groups L2, L3, and L4 presented scratches alternating with smoother areas showing that fiber contacted the surface of the sample. The results reconfirmed the necessity of further studies using diode laser, with a beam of light emitted in an interrupted mode to improve the control of the increase of temperature during radiation, and probably followed by a new scraping and root polishing with conventional instruments in an attempt to obtain a smoother and more homogeneous root surface. (author)

  2. Technique applied in the evaluation of the UFCC reactor at Refinaria Alberto Pasqualini (REFAP), PETROBRAS; Tecnicas utilizadas na avaliacao do reator da UFCC da REFAP

    Cascaes, Ronesio da Silva [PETROBRAS (Brazil) Refinaria Alberto Pasqualini

    1994-01-01

    Main problems found in the maintenance of the Fluidized Catalytic Cracking (FCC) unity, searches of metal alteration properties, metallographic evaluations, failures and micro-structures alterations are presented. Micrographic analysis of the structural samples, the methodology to detect the failures and physical and chemical essays utilized in the inspection are also reported 13 refs., 64 figs., 1 tab.

  3. Evaluation of testosterone serum levels in testicular interstitial fluid under thyroxine influence; Avaliacao da testosterona no fluido intersticial testicular sob influencia da tiroxina

    Silva, Isvania Maria S. da; Pereira, Simey de L.S.; Souza, Grace Mary L.; Carvalho, Elaine F.M.B.; Catanho, Maria Teresa J. de A. [Pernambuco Univ., Recife, PE (Brazil). Dept. de Biofisica e Radiobiologia; Silveira, Maria de Fatima G. da [Pernambuco Univ., Recife, PE (Brazil). Dept. de Anatomia; Lima Filho, Guilherme L. [Universidade de Pernambuco (UPE), Nazare da Mata, PE (Brazil). Faculdade de Formacao de Professores

    2000-07-01

    The thyroid hormones possibly exert a reciprocal action between testicular steroids and Sertoli's cells during the premature period. This work aims to evaluate thyroxine effect on testosterone serum levels and in the testicular interstitial fluid (TIF) in rats. Wistar males rats, 22 days old, 80g of body weight, were induced to hyperthyroidism with thyroxine (20{mu}g/kg) in periods of 5, 10, 15 and 20 consecutive days. After the treatment the animals were weighed and sacrificed for blood and testis collection. From the blood serum and from the TIF drained from the testis were performed testes in order to obtain testosterone attached to {sup 125} I with a specific activity of 36,86 MBq/ig. The results have shown a testosterone significant lineal increase in both - serum and TIF - in the group treated with thyroxine as a time function. In the control group, testosterone levels remained low in both serum and TIF dosages. As a result, we were able to verify that the testosterone levels could be modified by thyroxine in serum and TIF. And so, it could affect luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels in hypophysis. (author)

  4. Quality assessment of radiopharmaceuticals in nuclear medicine services at Northeast states, Brazil; Avaliacao da qualidade de radiofarmacos em servicos de medicina nuclear de estados da regiao nordeste

    Andrade, Wellington Gomes de

    2012-07-01

    The radiopharmaceuticals are used in the field nuclear medicine services (NMS) as tracer in the diagnoses and treatment of many diseases. Radiopharmaceuticals used in nuclear medicine and usually have a minimum of pharmacological effect. The procedures for labelling Radiopharmaceuticals should be observed in order to minimize risks to patients, employees and individuals from the public, and to be administered in humans, must be sterile and free of pyrogens and possess elements all measures of quality controls required a conventional drug. The 'Agencia Nacional de Vigilancia Sanitaria (ANVISA)' in its 'Resolucao de Diretoria Colegiada' (RDC) No. 38 of June 4{sup th} 2008, decided that the NMS must perform quality control in the generators eluate and radiopharmaceuticals according to recommendations of manufacturers and scientific evidence accepted by ANVISA. Thus, this study proposes to evaluate the quality of the generator {sup 99M}o-{sup 99m}Tc eluate and radiopharmaceuticals labeled with {sup 99m}Tc used in most NMS of some states in the Northeast, in relation to radionuclide, chemical, radiochemical purity and pH and promote the inclusion of procedure for quality control of radiopharmaceuticals in routine NMS. The results show that 90% radionuclidic purity, 98.2% purity chemical and radiochemical purity of 46% and 100% of the eluates are in agreement with international pharmacopoeias; already radiopharmaceuticals showed 82.6% purity and all radiochemical pH values are also in accordance with international pharmacopoeias. Even with so many positive results, staff the majority of MNS was not able to perform the quality control of the eluates and radiopharmaceuticals. Showing the importance of implementing of quality control programs of the eluates and radiopharmaceuticals in nuclear medicine. (author)

  5. Synthesis and evaluation of phytotoxic activity of {alpha}-Santonin derivatives; Sintese e avaliacao da atividade fitotoxica de derivados da {alpha}-Santonina

    Alvarenga, Elson S.; Barbosa, Luiz C.A.; Saliba, William A.; Arantes, Francisco F.P.; Demuner, Antonio J. [Universidade Federal de Vicosa (UFV), MG (Brazil). Dept. de Quimica]. E-mail: elson@ufv.br; Silva, Antonio A. [Universidade Federal de Vicosa (UFV), MG (Brazil). Dept. de Fitotecnia

    2009-07-01

    Mixtures of {alpha}-Santonin and various solvents were irradiated by either high or low pressure mercury lamps. The photochemical reactions afforded lumisantonin (11) (76% in acetonitrile), (3 S,3a S,9{beta}S)-3,6,6-trimethyl-3,3a,4,5-tetrahydronafto[1,2-b]furan-2,7({eta}6,9{beta}{eta}) dione (12) (100% in acetonitrile), 10{alpha}-acetoxy-3-oxo-1,7{alpha}H{eta},6,11{alpha}a{eta}-guaia-4-en-6,12-oli= de (8) (26% in acetic acid), 10{alpha}-hydroxy-3-oxo-1,7{alpha}a{eta},6,11{alpha}{eta}-guaia-4-en-6,12-olid= e (10) (32%) and (E)-3-((3 S,3a S,7{alpha}S)-3-methyl-2-oxo-6-(propan-2-ylidene)hexahydrobenzofuran- 7 - (7{alpha}{eta})-ylidene)propanoic acid (9) (44%) (in water/ acetic acid 1:1, v/v). Lactone 12 was also prepared by irradiation of lumisantonin in diethyl ether. Lactones 8 and 10 were converted, respectively, into the 10 {alpha}-acetoxy-3{alpha}-hydroxy-1,7{alpha}H,6,11{alpha}H-guaia-4-en-6,12-olid= e (13) (87%) and 3a,10a-dihydroxy-1,7{alpha}H,6,11{alpha}H-guaia-4-en-6,12-olide (14) (75%) by sodium borohydride reduction. The effects of the compounds on the development of radicle of Sorghum bicolor and Cucumis sativus were evaluated. (author)

  6. Development of test objects for image quality evaluation of digital mammography; Desenvolvimento de objetos de teste para avaliacao da qualidade da imagem em mamografia digital

    Pinto, Vitor Nascimento de Carvalho

    2013-07-01

    Mammography is the image exam called 'gold standard' for early detection of breast cancer. 111 Brazil, more than eight million mammograms are carried out per year. With the advancement of technology, the digital systems CR and DR for this diagnostic modality have been increasingly implemented, replacing the conventional screen-film system, which brought environmental problems, like the disposal of chemical waste, and is also responsible for the rejection of radiographic films with processing artifacts. Digital systems, besides not experiencing the problem of environmental pollution, are still capable of image processing, allowing a much lower rejection rate when compared to the conventional system. Moreover, the determination of an accurate diagnosis is highly dependent on the image quality of the examination. To ensure the reliability of the images produced by these systems, it is necessary to evaluate them on a regular basis. Unfortunately, there is no regulation in Brazil about the Quality Assurance of these systems. The aim of this study was to develop a set of test objects that allow the evaluation of some parameters of image quality of these systems, such as field image uniformity, the linearity between the air Kerma incident on detector and the mean pixel value (MPV) of the image, the spatial resolution of the system through the modulation transfer function (MTF) and also to suggest an object to be applied in the evaluation of contrast-to-noise ratio (CNR) and signal-difference-to-noise ratio (SDNR). In order to test the objects. 10 mammography centers were evaluated, seven with CR systems and three with the DR systems. To evaluate the linearity, besides the test objects high sensitivity dosimeters were necessary to be used, namely LiF:Mg,Cu,P TL dosimeters. The use of these dosimeters was recommended in order to minimize the time required to perform the tests and to decrease the number of exposures needed. For evaluation of digital images in DICOM format, the software {sup O}BJ{sub I}QJeduced{sup ,} version 3.0, was used. It was developed by the team of Prof.. Dr. Nicholas Marshall at the Catholic University of Leuven, Belgium. The results were very promising, leaving opened the possibility of future work as the optimization of the correction factors and uncertainties for the dosimeters as well as the applicability of the test objects in evaluating the image quality of digital systems across the country. (author)

  7. Use of different simulators to quality evaluation of image quality in digital mammography; Utilizacao de diferentes simuladores na avaliacao da qualidade da imagem em mamografia digital

    Pereira, Leslie S.; Coutinho, Celia M.C., E-mail: leslie@ird.gov.br, E-mail: celia@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Magalhaes, Luis A.G.; Almeida, Carlos Eduardo de, E-mail: luisalexandregm@hotmail.com, E-mail: cea71@yahoo.com.br [Universidade do Estado do Rio de Janeiro (LCR/UERJ), Rio de Janeiro, RJ (Brazil). Laboratorio de Ciencias Radiologicas

    2013-11-01

    In this study, the digital images were acquired with different exposure simulators to evaluate the quality of the image, noting the tumor mass detection, microcalcification fiber and representing regions of interest during mammography. The technical parameters of exposure depends on the thickness and composition of the breast, thus affecting the dose and image quality. The simulators were used: ACR, SBP 1054, BREAST PHANTOM CIRS and for evaluation of image quality, as well as measures kerma incident on the entrance surface (Ki) and calculating the mean glandular dose (MGD)

  8. Evaluation of the morphological alteration of the root surface radiated with a diode laser; Avaliacao da alteracao morfologica da superficie cimentaria irradiada com laser de diodo

    Gulin, Mauricio

    2003-07-01

    The diode laser has been studied for periodontal therapy, as much for removal of calculus as for microbial reduction of periodontal pockets, as well as the visible analgesic effects and biomodulation capacity. For this reason the purpose of this study was to evaluate the morphological alteration of the root surface after radiation with the diode laser, 808 nm through analysis by scanning electron microscopy (SEM). Besides this, to verify the temperature variations caused during the radiation, a thermometer put into the dentinal wall of the root canal was used. In all, 18 teeth were used, 15 of which for the SEM study, and the other 3 were used to temperature variation analysis. The 25 samples were scraped on the root surface and planed with manual instruments. The other 5 were not subjected to any type of treatment. This, 6 groups of 5 samples each were formed. Control Group C whose samples had not received any treatment; Control Group C 1 was only scraped and polished conventionally with Hu-Friedy Gracey curettes 5 and 6; the other samples groups L1, L2, L3, L4 were radiated by diode laser using parameters of power 1,0 W; 1,2 W; 1,4 W; and 1,6 W respectively, 2 times for 10 seconds with 20 seconds intervals between each radiation in continuous mode. The results with relation to the increase of temperature in the interior of the root canal demonstrated that there was an increase of more than 5 degree Celsius. The results of the scanning electron microscope analysis of Control Group C demonstrated great irregularity and ridges on the root surface, with the presence of a dentine layer. Control Group C1 presented a similar aspect to Group L 1's, smoother and more homogeneous surface. Groups L2, L3, and L4 presented scratches alternating with smoother areas showing that fiber contacted the surface of the sample. The results reconfirmed the necessity of further studies using diode laser, with a beam of light emitted in an interrupted mode to improve the control of the increase of temperature during radiation, and probably followed by a new scraping and root polishing with conventional instruments in an attempt to obtain a smoother and more homogeneous root surface. (author)

  9. Evaluation of the introduction of cogeneration for refrigeration in the fisheries sector of the Amazon; Avaliacao da introducao da cogeracao para refrigeracao no setor pesqueiro do Amazonas

    Cruz, Ricardo Wilson Aguiar da [Universidade Estadual do Amazonas (UEA), Manaus (Brazil)], e-mail: rcruz@uea.edu.br; Nebra, Silvia Azucena [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica], e-mail: sanebra@fem.unicamp.br; Cartaxo, Elizabeth Ferreira [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil)], e-mail: ecartaxo@ufam.edu.br

    2004-07-01

    This work analyses the opportunity to introduce cogeneration for the production of aquammonia absorption refrigeration in the autonomous Amazons State power system, by one hand as a means to improve its efficiency and by another, solve the deficiency the State has to store its fish-ing production. (author)

  10. Evaluation of gels obtained from acetylation of chitosan in heterogeneous medium; Avaliacao de geis obtidos a partir da acetilacao da quitosana em meio heterogeneo

    Garcia, Rosangela Balaban; Silva, Dayse Luzia Pinheiro da; Costa, Marta [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Dept. de Quimica]. E-mail: balaban@digi.com.br; Raffin, Fernanda Nervo [Universidade Federal do Rio Grande do Norte (UFRGN), Natal, RN (Brazil). Centro de Ciencias da Saude. Dept. de Quimica, Tecnologia Farmaceutica e de Alimentos; Ruiz, Naira Machado da Silva [Centro de Pesquisa Leopoldo A. Miguez de Mello (CENPES), Rio de Janeiro, RJ (Brazil)

    2008-07-01

    Chitosan was acetylated during 2, 5 and 10 h and physical gels were obtained at different polymer concentrations in N,N-dimethylacetamide containing 5% of LiCl. Acetylation was confirmed by infrared spectroscopy and {sup 13}C NMR, and degrees of acetylation in the range of 0.82-0.91 were determined by NMR. The O-acetylation degree (0.12-0.15) was exclusively determined by a volumetric method. Rheological studies showed that the storage modulus values were smaller for the more acetylated samples and increased with the temperature and the polymer concentration. All the gels presented storage modulus superior to loss modulus, evidencing more elastic than viscous characteristics. The results obtained in this work suggest a gelation process based on a balance between O and N-acetylation and intermolecular bonds. (author)

  11. Quality assessment of radiopharmaceuticals in nuclear medicine services at Northeast states, Brazil; Avaliacao da qualidade de radiofarmacos em servicos de medicina nuclear de estados da regiao nordeste

    Andrade, Wellington Gomes de

    2012-07-01

    The radiopharmaceuticals are used in the field nuclear medicine services (NMS) as tracer in the diagnoses and treatment of many diseases. Radiopharmaceuticals used in nuclear medicine and usually have a minimum of pharmacological effect. The procedures for labelling Radiopharmaceuticals should be observed in order to minimize risks to patients, employees and individuals from the public, and to be administered in humans, must be sterile and free of pyrogens and possess elements all measures of quality controls required a conventional drug. The 'Agencia Nacional de Vigilancia Sanitaria (ANVISA)' in its 'Resolucao de Diretoria Colegiada' (RDC) No. 38 of June 4{sup th} 2008, decided that the NMS must perform quality control in the generators eluate and radiopharmaceuticals according to recommendations of manufacturers and scientific evidence accepted by ANVISA. Thus, this study proposes to evaluate the quality of the generator {sup 99M}o-{sup 99m}Tc eluate and radiopharmaceuticals labeled with {sup 99m}Tc used in most NMS of some states in the Northeast, in relation to radionuclide, chemical, radiochemical purity and pH and promote the inclusion of procedure for quality control of radiopharmaceuticals in routine NMS. The results show that 90% radionuclidic purity, 98.2% purity chemical and radiochemical purity of 46% and 100% of the eluates are in agreement with international pharmacopoeias; already radiopharmaceuticals showed 82.6% purity and all radiochemical pH values are also in accordance with international pharmacopoeias. Even with so many positive results, staff the majority of MNS was not able to perform the quality control of the eluates and radiopharmaceuticals. Showing the importance of implementing of quality control programs of the eluates and radiopharmaceuticals in nuclear medicine. (author)

  12. Ribeira do Iguape basin water quality assessment for drinking water supply; Avaliacao da qualidade da agua na bacia hidrografica do Ribeira de Iguape com vistas ao abastecimento publico

    Cotrim, Marycel Elena Barboza

    2006-07-01

    Ribeira do Iguape Basin, located in the Southeast region of Sao Paulo state, is the largest remaining area of Mata Atlantica which biodiversity as rich as Amazon forest , where the readiness of water versus demand is extremely positive. With sparse population density and economy almost dependent on banana agriculture, the region is still well preserved. To water supply SABESP (Sao Paulo State Basic Sanitation Company). Ribeira do Iguape Businesses Unit - RR, uses different types of water supplies. In the present work, in order to ascertain water quality for human consumption, major and minor elements were evaluated in various types of water supply (surface and groundwater's as well as the drinking water supplied). Forty three producing systems were monitored: 18 points of surface waters and treated distributed water, 10 points of groundwater and 15 points of surface water in preserved areas, analyzing 30 elements. Bottom sediments (fraction < 63 {mu}m) were also evaluated. The sampling period covered dry and wet seasons from March 2002 to February 2003. The descriptive analysis showed that Al, Fe and Mn, exceeding CONAMA 357 quality guideline. A comparison of the elemental concentrations with the Brazilian Drinking Water Legislation (Portaria 518/04) showed that with the exception of some violations, the levels of all the elements investigated were below the Brazilian Legislation maximum allowed concentrations. This study examined the relationship between the type of water supply and the quality of water used, showed different characteristics on Ca, Fe, Mn concentration. In bottom sediments (fraction <63 {mu}m), Al, Fe and Mg largest concentrations were found. Pb and Zn presents concentrations up to 142,0 {mu}g.g{sup -1} and 172 {mu}g.g{sup -1}, respectively. Data revealed that trace elements concentration in the sediment were below PEL (Probable Effect Level - probable level of adverse effect to the biological community), exception for Pb in Sete Barras and Eldorado. (author)

  13. Incorporação de cinza de lenha, lodo de estação de tratamento de água e cinza de casca de arroz em massa cerâmica: utilização da técnica de planejamento Grog incorporation in ceramic mass to manufacture of bricks: a study of the physical-mechanical properties

    E. N. M de Medeiros

    2010-12-01

    Full Text Available Este trabalho apresenta um estudo das propriedades físico-mecânicas de massas cerâmicas com a incorporação de resíduos de cinza de lenha, lodo de estação de tratamento de água e cinza de casca de arroz, visando a sua futura utilização na produção de blocos. Os procedimentos metodológicos consistiram na caracterização química e mineralógica, na análise granulométrica e no delineamento de misturas com argila e resíduos por meio da técnica de planejamento. Foram produzidos corpos de prova por prensagem, com variações de composições no intervalo de 0 a 50% de resíduo e 50 a 100% de argila. A queima foi realizada em forno tipo mufla. As propriedades físico-mecânicas avaliadas foram absorção de água e módulo de ruptura à flexão. Como resultados principais, concluiu-se sobre a viabilidade em se utilizar composições com até 25% de resíduo nas temperaturas de 800, 900 e 1000 ºC.This paper presents a study of the physical and mechanical properties of ceramic mass with the incorporation of waste ash wood, sludge from water treatment and rice husk ash to determine whether its future use manufacture of bricks. The procedures consisted in the chemical and mineralogical characterization, particle size analysis and design of mixtures with clay and waste through planning technique. Bodies were produced by uniaxial pressing, with variations of compositions in the range of 0 to 50% waste and 50 to 100% clay. The burning was carried out in muffle furnace. The physical and mechanical properties evaluated were water absorption and modulus of rupture strength. The main result, it was concluded on the feasibility of using compositions with up to 25% of waste at temperatures of 800, 900 and 1000ºC.

  14. Glass Ceramic Formulation Data Package

    Crum, Jarrod V.; Rodriguez, Carmen P.; McCloy, John S.; Vienna, John D.; Chung, Chul-Woo

    2012-01-01

    A glass ceramic waste form is being developed for treatment of secondary waste streams generated by aqueous reprocessing of commercial used nuclear fuel (Crum et al. 2012b). The waste stream contains a mixture of transition metals, alkali, alkaline earths, and lanthanides, several of which exceed the solubility limits of a single phase borosilicate glass (Crum et al. 2009; Caurant et al. 2007). A multi-phase glass ceramic waste form allows incorporation of insoluble components of the waste by designed crystallization into durable heat tolerant phases. The glass ceramic formulation and processing targets the formation of the following three stable crystalline phases: (1) powellite (XMoO4) where X can be (Ca, Sr, Ba, and/or Ln), (2) oxyapatite Yx,Z(10-x)Si6O26 where Y is alkaline earth, Z is Ln, and (3) lanthanide borosilicate (Ln5BSi2O13). These three phases incorporate the waste components that are above the solubility limit of a single-phase borosilicate glass. The glass ceramic is designed to be a single phase melt, just like a borosilicate glass, and then crystallize upon slow cooling to form the targeted phases. The slow cooling schedule is based on the centerline cooling profile of a 2 foot diameter canister such as the Hanford High-Level Waste canister. Up to this point, crucible testing has been used for glass ceramic development, with cold crucible induction melter (CCIM) targeted as the ultimate processing technology for the waste form. Idaho National Laboratory (INL) will conduct a scaled CCIM test in FY2012 with a glass ceramic to demonstrate the processing behavior. This Data Package documents the laboratory studies of the glass ceramic composition to support the CCIM test. Pacific Northwest National Laboratory (PNNL) measured melt viscosity, electrical conductivity, and crystallization behavior upon cooling to identify a processing window (temperature range) for melter operation and cooling profiles necessary to crystallize the targeted phases in the

  15. Disc piezoelectric ceramic transformers.

    Erhart, Jirií; Půlpán, Petr; Doleček, Roman; Psota, Pavel; Lédl, Vít

    2013-08-01

    In this contribution, we present our study on disc-shaped and homogeneously poled piezoelectric ceramic transformers working in planar-extensional vibration modes. Transformers are designed with electrodes divided into wedge, axisymmetrical ring-dot, moonie, smile, or yin-yang segments. Transformation ratio, efficiency, and input and output impedances were measured for low-power signals. Transformer efficiency and transformation ratio were measured as a function of frequency and impedance load in the secondary circuit. Optimum impedance for the maximum efficiency has been found. Maximum efficiency and no-load transformation ratio can reach almost 100% and 52 for the fundamental resonance of ring-dot transformers and 98% and 67 for the second resonance of 2-segment wedge transformers. Maximum efficiency was reached at optimum impedance, which is in the range from 500 Ω to 10 kΩ, depending on the electrode pattern and size. Fundamental vibration mode and its overtones were further studied using frequency-modulated digital holographic interferometry and by the finite element method. Complementary information has been obtained by the infrared camera visualization of surface temperature profiles at higher driving power.

  16. Bar piezoelectric ceramic transformers.

    Erhart, Jiří; Pulpan, Půlpán; Rusin, Luboš

    2013-07-01

    Bar-shaped piezoelectric ceramic transformers (PTs) working in the longitudinal vibration mode (k31 mode) were studied. Two types of the transformer were designed--one with the electrode divided into two segments of different length, and one with the electrodes divided into three symmetrical segments. Parameters of studied transformers such as efficiency, transformation ratio, and input and output impedances were measured. An analytical model was developed for PT parameter calculation for both two- and three-segment PTs. Neither type of bar PT exhibited very high efficiency (maximum 72% for three-segment PT design) at a relatively high transformation ratio (it is 4 for two-segment PT and 2 for three-segment PT at the fundamental resonance mode). The optimum resistive loads were 20 and 10 kΩ for two- and three-segment PT designs for the fundamental resonance, respectively, and about one order of magnitude smaller for the higher overtone (i.e., 2 kΩ and 500 Ω, respectively). The no-load transformation ratio was less than 27 (maximum for two-segment electrode PT design). The optimum input electrode aspect ratios (0.48 for three-segment PT and 0.63 for two-segment PT) were calculated numerically under no-load conditions.

  17. Reliability of ceramics for heat engine applications

    1980-01-01

    The advantages and disadvantages associated with the use of monolithic ceramics in heat engines are discussed. The principle gaps in the state of understanding of ceramic material, failure origins, nondestructive tests as well as life prediction are included.

  18. III Advanced Ceramics and Applications Conference

    Gadow, Rainer; Mitic, Vojislav; Obradovic, Nina

    2016-01-01

    This is the Proceedings of III Advanced Ceramics and Applications conference, held in Belgrade, Serbia in 2014. It contains 25 papers on various subjects regarding preparation, characterization and application of advanced ceramic materials.

  19. Panel report on high temperature ceramics

    Nolet, T C [ed.

    1979-01-01

    Fundamental research is reported concerning high temperature ceramics for application in turbines, engines, batteries, gasifiers, MHD, fuel cells, heat exchangers, and hot wall combustors. Ceramics microstructure and behavior are included. (FS)

  20. Ceramics: past, present, and future.

    Lemons, J E

    1996-07-01

    The selection and application of synthetic materials for surgical implants has been directly dependent upon the biocompatibility profiles of specific prosthetic devices. The early rationale for ceramic biomaterials was based upon the chemical and biochemical inertness (minimal bioreactivity) of elemental compounds constituted into structural forms (materials). Subsequently, mildly reactive (bioactive), and partially and fully degradable ceramics were identified for clinical uses. Structural forms have included bulk solids or particulates with and without porosities for tissue ingrowth, and more recently, coatings onto other types of biomaterial substrates. The physical shapes selected were application dependent, with advantages and disadvantages determined by: (1) the basic material and design properties of the device construct; and (2) the patient-based functional considerations. Most of the ceramics (bioceramics) selected in the 1960s and 1970s have continued over the long-term, and the science and technology for thick and thin coatings have evolved significantly over the past decade. Applications of ceramic biomaterials range from bulk (100%) ceramic structures as joint and bone replacements to fully or partially biodegradable substrates for the controlled delivery of pharmaceutical drugs, growth factors, and morphogenetically inductive substances. Because of the relatively unique properties of bioceramics, expanded uses as structural composites with other biomaterials and macromolecular biologically-derived substances are anticipated in the future.

  1. Shock compression profiles in ceramics

    Grady, D.E.; Moody, R.L.

    1996-03-01

    An investigation of the shock compression properties of high-strength ceramics has been performed using controlled planar impact techniques. In a typical experimental configuration, a ceramic target disc is held stationary, and it is struck by plates of either a similar ceramic or by plates of a well-characterized metal. All tests were performed using either a single-stage propellant gun or a two-stage light-gas gun. Particle velocity histories were measured with laser velocity interferometry (VISAR) at the interface between the back of the target ceramic and a calibrated VISAR window material. Peak impact stresses achieved in these experiments range from about 3 to 70 GPa. Ceramics tested under shock impact loading include: Al{sub 2}O{sub 3}, AlN, B{sub 4}C, SiC, Si{sub 3}N{sub 4}, TiB{sub 2}, WC and ZrO{sub 2}. This report compiles the VISAR wave profiles and experimental impact parameters within a database-useful for response model development, computational model validation studies, and independent assessment of the physics of dynamic deformation on high-strength, brittle solids.

  2. Transparent ceramic lamp envelope materials

    Wei, G C [OSRAM SYLVANIA, 71 Cherry Hill Drive, Beverly, MA 01915 (United States)

    2005-09-07

    Transparent ceramic materials with optical qualities comparable to single crystals of similar compositions have been developed in recent years, as a result of the improved understanding of powder-processing-fabrication- sintering-property inter-relationships. These high-temperature materials with a range of thermal and mechanical properties are candidate envelopes for focused-beam, short-arc lamps containing various fills operating at temperatures higher than quartz. This paper reviews the composition, structure and properties of transparent ceramic lamp envelope materials including sapphire, small-grained polycrystalline alumina, aluminium oxynitride, yttrium aluminate garnet, magnesium aluminate spinel and yttria-lanthana. A satisfactory thermal shock resistance is required for the ceramic tube to withstand the rapid heating and cooling cycles encountered in lamps. Thermophysical properties, along with the geometry, size and thickness of a transparent ceramic tube, are important parameters in the assessment of its resistance to fracture arising from thermal stresses in lamps during service. The corrosive nature of lamp-fill liquid and vapour at high temperatures requires that all lamp components be carefully chosen to meet the target life. The wide range of new transparent ceramics represents flexibility in pushing the limit of envelope materials for improved beamer lamps.

  3. High flow ceramic pot filters.

    van Halem, D; van der Laan, H; Soppe, A I A; Heijman, S G J

    2017-11-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6-19 L h -1 ), but initial LRVs for E. coli of high flow filters was slightly lower than for regular ceramic pot filters. This disadvantage was, however, only temporarily as the clogging in high flow filters had a positive effect on the LRV for E. coli (from below 1 to 2-3 after clogging). Therefore, it can be carefully concluded that regular ceramic pot filters perform better initially, but after clogging, the high flow filters have a higher flow rate as well as a higher LRV for E. coli. To improve the initial performance of new high flow filters, it is recommended to further utilize residence time of the water in the receptacle, since additional E. coli inactivation was observed during overnight storage. Although a relationship was observed between flow rate and LRV of MS2 bacteriophages, both regular and high flow filters were unable to reach over 2 LRV. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Emerging Ceramic-based Materials for Dentistry

    Denry, I.; Kelly, J.R.

    2014-01-01

    Our goal is to give an overview of a selection of emerging ceramics and issues for dental or biomedical applications, with emphasis on specific challenges associated with full-contour zirconia ceramics, and a brief synopsis on new machinable glass-ceramics and ceramic-based interpenetrating phase composites. Selected fabrication techniques relevant to dental or biomedical applications such as microwave sintering, spark plasma sintering, and additive manufacturing are also reviewed. Where appropriate, the authors have added their opinions and guidance. PMID:25274751

  5. Ion implantation and fracture toughness of ceramics

    Clark, J.; Pollock, J.T.A.

    1985-01-01

    Ceramics generally lack toughness which is largely determined by the ceramic surface where stresses likely to cause failure are usually highest. Ion implantation has the capacity to improve the surface fracture toughness of ceramics. Significantly reduced ion size and reactivity restrictions exist compared with traditional methods of surface toughening. We are studying the effect of ion implantation on ceramic fracture toughness using indentation testing as the principal tool of analysis

  6. Ceramic cutting tools materials, development and performance

    Whitney, E Dow

    1994-01-01

    Interest in ceramics as a high speed cutting tool material is based primarily on favorable material properties. As a class of materials, ceramics possess high melting points, excellent hardness and good wear resistance. Unlike most metals, hardness levels in ceramics generally remain high at elevated temperatures which means that cutting tip integrity is relatively unaffected at high cutting speeds. Ceramics are also chemically inert against most workmetals.

  7. Ferroelastic ceramic-reinforced metal matrix composites

    2006-01-01

    Composite materials comprising ferroelastic ceramic particulates dispersed in a metal matrix are capable of vibration damping. When the ferroelastic ceramic particulates are subjected to stress, such as the cyclic stress experienced during vibration of the material, internal stresses in the ceramic cause the material to deform via twinning, domain rotation or domain motion thereby dissipating the vibrational energy. The ferroelastic ceramic particulates may also act as reinforcements to impro...

  8. Development of advanced ceramics at AECL

    Palmer, B.J.F.; MacEwen, S.R.; Sawicka, B.D.; Hayward, P.J.; Sridhar, S.

    1986-12-01

    Atomic Energy of Canada Limited (AECL) has a long history of developing ceramics for nuclear fission and fusion applications. AECL is now applying its multidisciplinary materials R and D capabilities, including unique capabilities in ceramic processing and nondestructive evaluation, to develop advanced ceramic materials for commercial and industrial applications. This report provides an overview of the facilities and programs associated with the development of advanced ceramics at AECL

  9. What every surgeon should know about Ceramic-on-Ceramic bearings in young patients

    Hernigou, Philippe; Roubineau, Fran?ois; Bouthors, Charlie; Flouzat-Lachaniette, Charles-Henri

    2016-01-01

    Based on the exceptional tribological behaviour and on the relatively low biological activity of ceramic particles, Ceramic-on-Ceramic (CoC) total hip arthroplasty (THA) presents significant advantages CoC bearings decrease wear and osteolysis, the cumulative long-term risk of dislocation, muscle atrophy, and head-neck taper corrosion. However, there are still concerns regarding the best technique for implantation of ceramic hips to avoid fracture, squeaking, and revision of ceramic hips with...

  10. Durability of feldspathic veneering ceramic on glass-infiltrated alumina ceramics after long-term thermocycling.

    Mesquita, A M M; Ozcan, M; Souza, R O A; Kojima, A N; Nishioka, R S; Kimpara, E T; Bottino, M A

    2010-01-01

    This study compared the bond strength durability of a feldspathic veneering ceramic to glass-infiltrated reinforced ceramics in dry and aged conditions. Disc shaped (thickness: 4 mm, diameter: 4 mm) of glass-infiltrated alumina (In-Ceram Alumina) and glass-infiltrated alumina reinforced by zirconia (In-Ceram Zirconia) core ceramic specimens (N=48, N=12 per groups) were constructed according to the manufacturers' recommendations. Veneering ceramic (VITA VM7) was fired onto the core ceramics using a mold. The core-veneering ceramic assemblies were randomly divided into two conditions and tested either immediately after specimen preparation (Dry) or following 30000 thermocycling (5-55 ºC±1; dwell time: 30 seconds). Shear bond strength test was performed in a universal testing machine (cross-head speed: 1 mm/min). Failure modes were analyzed using optical microscope (x20). The bond strength data (MPa) were analyzed using ANOVA (α=0.05). Thermocycling did not decrease the bond strength results for both In-Ceram Alumina (30.6±8.2 MPa; P=0.2053) and In-Ceram zirconia (32.6±9 MPa; P=0.3987) core ceramic-feldspathic veneering ceramic combinations when compared to non-aged conditions (28.1±6.4 MPa, 29.7±7.3 MPa, respectively). There were also no significant differences between adhesion of the veneering ceramic to either In-Ceram Alumina or In-Ceram Zirconia ceramics (P=0.3289). Failure types were predominantly a mixture of adhesive failure between the veneering and the core ceramic together with cohesive fracture of the veneering ceramic. Long-term thermocycling aging conditions did not impair the adhesion of the veneering ceramic to the glass-infiltrated alumina core ceramics tested.

  11. Dense high temperature ceramic oxide superconductors

    Landingham, Richard L.

    1993-01-01

    Dense superconducting ceramic oxide articles of manufacture and methods for producing these articles are described. Generally these articles are produced by first processing these superconducting oxides by ceramic processing techniques to optimize materials properties, followed by reestablishing the superconducting state in a desired portion of the ceramic oxide composite.

  12. Ceramic component with reinforced protection against radiations

    Dubuisson, J.; Laville, H.; Le Gal, P.

    1986-01-01

    Ceramic components hardened against radiations are claimed (for example capacitors or ceramic substrates for semiconductors). They are prepared with a sintered ceramic containing a high proportion of heavy atoms (for instance barium titanate and a bismuth salt) provided with a glass layer containing a high proportion of light atoms. The two materials are joined by vitrification producing a diffusion zone at the interface [fr

  13. Study of brazilian market of advanvced ceramics

    Veiga, M.M.; Soares, P.S.M.; SIlva, A.P. da; Alvarinho, S.B.

    1989-01-01

    The brazilian actual market survey of advanced ceramics, divided in sectors according to their function is described. The electroelectronics, magnetics, optics, mechanics and nuclears ceramics are presented. A forecasting of the brazilian market in advanced ceramics are also mentioned. (C.G.C.) [pt

  14. Polymer-ceramic piezoelectric composites (PZT)

    Bassora, L.A.; Eiras, J.A.

    1992-01-01

    Polymer-ceramic piezoelectric transducers, with 1-3 of connectivity were prepared with different concentration of ceramic material. Piezoelectric composites, with equal electromechanical coupling factor and acoustic impedance of one third from that ceramic transducer, were obtained when the fractionary volume of PZT reach 30%. (C.G.C.)

  15. Effect of operating conditions on the performances of multichannel ceramic UF membranes for textile mercerization wastewater treatment.

    Zebić Avdičević, Maja; Košutić, Krešimir; Dobrović, Slaven

    2017-01-01

    Textile wastewaters are rated as one of the most polluting in all industrial sectors, and membrane separation is the most promising technology for their treatment and reuse of auxiliary chemicals. This study evaluates the performance of three types of tubular ceramic ultrafiltration membranes differing by mean pore size (1, 2 and 500 kDa) treating textile mercerization wastewater from a textile mill at different operating conditions: cross-flow velocity (CFV) and temperature. Acceptable results were obtained with 1 kDa ceramic membrane, with rejection efficiencies 92% for suspended solids, 98% for turbidity, 98% for color and 53% for total organic carbon at 20°C and 3 m s -1 CFV. Highest fouling effect was observed for 500 kDa membrane and lowest CFV. According to the observed results, 1 kDa membrane could be used for the treatment of wastewater from the textile mercerization process in terms of permeate quality.

  16. Study of stability of the ceramic Ba{sub 2}NiWO{sub 6} in crude petroleum drew back from state - Brazil oil wells; Microestrutura e propriedades mecanicas da ceramica Ba{sub 2}NiWO{sub 6} apos imersao em petroleo cru retirado de pocos de prtroleo do estado de Sergipe - Brasil

    Yadava, Y.P.; Bezerra, L.P.; Diniz, M.J.L.; Ferreira, R.A.S. [Universidade Federal de Pernambuco (DEM/UFPE), Recife, PE (Brazil). Dept. de Engenharia Mecanica], e-mail: yadava@ufpe.br

    2008-07-01

    The necessity of developing technologies which make practical the oil-well exploration is notorious. Knowing that those are hostile places is necessary to find materials which are capable to resist to the inclemency caused by those environments. Pondering that the ceramics show the required characteristics to this purpose the present assignment views the elaboration of complex perovskite ceramic Ba{sub 2}NiWO{sub 6} to produce ceramics components parts of temperature sensors to oil-well. To this purpose we studied the ceramic stability when they are vulnerable to the attack of the crude petroleum drew back from ocean and earth's oil-wells of Sergipe state-Brazil. The ceramics were submersed in the mentioned petroleum during thirty days and then they were analyzed by X-ray diffraction, optics microscopy and microhardness Vickers to verify if changes happened in the structure, microstructure and mechanics proprieties characteristics. These results are showed and discussed in this assignment. (author)

  17. Surface treatment of ceramic articles

    Komvopoulos, K.; Brown, I.G.; Wei, B.; Anders, S.; Anders, A.; Bhatia, C.S.

    1998-01-01

    A process is disclosed for producing an article with improved ceramic surface properties including providing an article having a ceramic surface, and placing the article onto a conductive substrate holder in a hermetic enclosure. Thereafter a low pressure ambient is provided in the hermetic enclosure. A plasma including ions of solid materials is produced the ceramic surface of the article being at least partially immersed in a macroparticle free region of the plasma. While the article is immersed in the macroparticle free region, a bias of the substrate holder is biased between a low voltage at which material from the plasma condenses on the surface of the article and a high negative voltage at which ions from the plasma are implanted into the article. 15 figs

  18. Dynamic properties of ceramic materials

    Grady, D.E.

    1995-02-01

    The present study offers new data and analysis on the transient shock strength and equation-of-state properties of ceramics. Various dynamic data on nine high strength ceramics are provided with wave profile measurements, through velocity interferometry techniques, the principal observable. Compressive failure in the shock wave front, with emphasis on brittle versus ductile mechanisms of deformation, is examined in some detail. Extensive spall strength data are provided and related to the theoretical spall strength, and to energy-based theories of the spall process. Failure waves, as a mechanism of deformation in the transient shock process, are examined. Strength and equation-of-state analysis of shock data on silicon carbide, boron carbide, tungsten carbide, silicon dioxide and aluminum nitride is presented with particular emphasis on phase transition properties for the latter two. Wave profile measurements on selected ceramics are investigated for evidence of rate sensitive elastic precursor decay in the shock front failure process

  19. Superplastic forging nitride ceramics

    Panda, P.C.; Seydel, E.R.; Raj, R.

    1988-03-22

    A process is disclosed for preparing silicon nitride ceramic parts which are relatively flaw free and which need little or no machining, said process comprising the steps of: (a) preparing a starting powder by wet or dry mixing ingredients comprising by weight from about 70% to about 99% silicon nitride, from about 1% to about 30% of liquid phase forming additive and from 1% to about 7% free silicon; (b) cold pressing to obtain a preform of green density ranging from about 30% to about 75% of theoretical density; (c) sintering at atmospheric pressure in a nitrogen atmosphere at a temperature ranging from about 1,400 C to about 2,200 C to obtain a density which ranges from about 50% to about 100% of theoretical density and which is higher than said preform green density, and (d) press forging workpiece resulting from step (c) by isothermally uniaxially pressing said workpiece in an open die without initial contact between said workpiece and die wall perpendicular to the direction of pressing and so that pressed workpiece does not contact die wall perpendicular to the direction of pressing, to substantially final shape in a nitrogen atmosphere utilizing a temperature within the range of from about 1,400 C to essentially 1,750 C and strain rate within the range of about 10[sup [minus]7] to about 10[sup [minus]1] seconds[sup [minus]1], the temperature and strain rate being such that surface cracks do not occur, said pressing being carried out to obtain a shear deformation greater than 30% whereby superplastic forging is effected.

  20. Chemical characterization of marajoara ceramics

    Toyota, Rosimeiri Galbiati

    2009-01-01

    In this study the elemental concentration of Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sc, Sm, Ta, Tb, Th, U, Yb and Zn were determined by instrumental neutron activation analysis (INAA) in 204 fragments of Marajoara archaeological ceramics, of which 156 were provided by the Archaeology and Ethnology Museum of Sao Paulo University (MAE) and 48 were provided by Dr. Denise Pahl Schaan, Marajo Museum curator. Also, 9 contemporary ceramics produced and marketed at Marajo Island were analyzed. Electron paramagnetic resonance (EPR) analyses were performed in 8 archaeological samples and 1 contemporary sample in order to identify the burning temperature of the samples. X-ray diffraction (XRD) analyses were performed in 13 archaeological samples and 2 contemporary samples for the investigation of their mineralogical composition. Mahalanobis distance was used for the study of outlier while modified filter was used for the study of the temper added to the ceramic paste. Result interpretation was performed using cluster analysis, principal components analysis and discriminant analysis. Procrustes analysis was used for variable selection and it showed that the Ce, Fe, Eu, Hf, K and Th variables are adequate for the characterization of the analyzed samples. The comparative study among the archaeological and contemporary ceramics showed the arrangement of two well-defined and close groups for the archaeological samples and a third, distant group for the contemporary ones. This result indicates that the archaeological and contemporary ceramics differ in their composition. EPR and XRD analysis were inconclusive for the differentiation of archaeological and contemporary ceramics. (author)

  1. Uranium determination in dental ceramics

    Jacobson, I.; Gamboa, I.; Espinosa, G.; Moreno, A.

    1984-01-01

    There are many reports of high uranium concentration in dental ceramics, so they require to be controlled. The SSNTD is an optional method to determine the uranium concentration. In this work the analysis of several commercial dental ceramics used regularly in Mexico by dentists is presented. The chemical and electrochemical processes are used and the optimal conditions for high sensitivity are determined. CR-39 (allyl diglycol polycarbonate) was used as detector. The preliminary results show some materials with high uranium concentrations. Next step will be the analysis of equivalent dose and the effects in the public health. (author)

  2. Análise da expansão por umidade e absorção de água de pisos cerâmicos comerciais em relação à composição química e à quantidade estimada de fase vítrea Analysis of moisture expansion and water absorption of commercial ceramic tiles in relation with chemical composition and estimated glassy phase content

    R. R. Menezes

    2003-04-01

    Full Text Available Expansão por umidade (EPU é o aumento das dimensões do corpo cerâmico devido à adsorção de água, podendo ter grande influência na vida útil dos materiais cerâmicos. Este trabalho tem por objetivo relacionar a EPU e a absorção de água de pisos cerâmicos comerciais, com a sua composição química e a quantidade estimada de fase vítrea, calculada utilizando-se o diagrama de equilíbrio de fases do sistema SiO2.Al2O3.K2 O e a regra da alavanca. Foram estudadas amostras de vinte e três tipos de pisos cerâmicos comerciais. Foi realizada a análise química das amostras (via úmida e determinada a sua EPU e absorção de água (ensaios realizados de acordo com a norma Brasileira NBR 13818. Foi também determinada a área superficial específica de algumas amostras por adsorção de nitrogênio (BET. Os resultados obtidos mostram genericamente uma proporcionalidade inversa entre a EPU e a absorção de água, para a maioria das amostras, e a análise utilizando o diagrama de fases sugere uma relação decrescente entre a absorção de água e a quantidade estimada de fase vítrea, e uma relação crescente entre a EPU e a quantidade estimada de fase vítrea.Moisture expansion is the size increase of the ceramic body due to water adsorption and can have a great influence in the ceramic material service life. This work aims to relate the moisture expansion and water absorption of commercial ceramic tiles with their chemical composition and estimated glassy phase content, calculated from the phase equilibrium diagram of the system SiO2.Al2O3.K2 O using the lever rule. Samples of twenty three commercial ceramic tiles were studied. The chemical composition of the samples was obtained (wet route and their moisture expansion and water absorption were determined (according to the Brazilian standard NBR 13818. The specific surface area of some samples was also determined, using the nitrogen adsorption methodology (BET. The results obtained

  3. Reuse of the red brick waste and dust waste of blasting chamber (glass micro spheres) in the red ceramic industry; Reaproveitamento dos residuos de tijolos vermelhos e do residuo de poeira da camara de jateamento (micro esferas de vidro) na industria de ceramica vermelha

    Rodrigues, R.A.; Felippe, C.E.C.; Guimaraes, C.S.; Almeida, V.C., E-mail: valeria@eq.ufrj.b [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Centro de Tecnologia. Escola de Quimica

    2010-07-01

    The search for alternative environmentally less aggressive disposal of solid waste has been adopted to reverse the negative scenario established by the improper disposal of these materials. The aim of this study was to evaluate the reuse of waste: leftover red brick from the civil construction and glass micro spheres, obtained from the blasting chamber, aiming to develop a ceramic product. Mixtures containing various amounts of waste were prepared. The ceramic pieces were burned at 1000 and 1200 deg C being tested for water absorption and tensile strength and characterized by X-ray diffraction. The analysis of volatile organic compounds released during the burning process was performed. The results indicate that the ceramic material produced has a high resistance although the analysis of gases from the burning point to a negative environmental impact. (author)

  4. Fracture mechanics of ceramics. Vol. 7

    Bradt, R.C.; Evans, A.G.; Hasselman, D.P.; Lange, F.F.

    1986-01-01

    This volume, together with volume 8, constitutes the proceedings of an international symposium on the fracture mechanics of ceramics. The topics discussed in this volume include the toughening of ceramics by whisker reinforcement; the mechanical properties of SiCwhisker-reinforced TZP; the fracture of brittle rock and oil shale under dynamic explosive loading; impact damage models of ceramic coatings used in gas turbine and diesel engines; the use of exploratory data analysis for the safety evaluation of structural ceramics; and proof testing methods for the reliability of structural ceramics used in gas turbines

  5. MHD oxidant intermediate temperature ceramic heater study

    Carlson, A. W.; Chait, I. L.; Saari, D. P.; Marksberry, C. L.

    1981-09-01

    The use of three types of directly fired ceramic heaters for preheating oxygen enriched air to an intermediate temperature of 1144K was investigated. The three types of ceramic heaters are: (1) a fixed bed, periodic flow ceramic brick regenerative heater; (2) a ceramic pebble regenerative heater. The heater design, performance and operating characteristics under conditions in which the particulate matter is not solidified are evaluated. A comparison and overall evaluation of the three types of ceramic heaters and temperature range determination at which the particulate matter in the MHD exhaust gas is estimated to be a dry powder are presented.

  6. Ceramic nanostructures and methods of fabrication

    Ripley, Edward B [Knoxville, TN; Seals, Roland D [Oak Ridge, TN; Morrell, Jonathan S [Knoxville, TN

    2009-11-24

    Structures and methods for the fabrication of ceramic nanostructures. Structures include metal particles, preferably comprising copper, disposed on a ceramic substrate. The structures are heated, preferably in the presence of microwaves, to a temperature that softens the metal particles and preferably forms a pool of molten ceramic under the softened metal particle. A nano-generator is created wherein ceramic material diffuses through the molten particle and forms ceramic nanostructures on a polar site of the metal particle. The nanostructures may comprise silica, alumina, titania, or compounds or mixtures thereof.

  7. Ceramic Ultrafiltration of Marine Algal Solutions: A Comprehensive Study

    Dramas, Laure

    2014-09-01

    Algal bloom can significantly impact reverse osmosis desalination process and reduce the drinking water production. In 2008, a major bloom event forced several UAE reverse osmosis plants to stop their production, and in this context, a better understanding of UF membrane fouling caused by algal organic matter (AOM) is needed, in order to adjust the filtration conditions during algal bloom events. Polymeric MF/UF membranes are already widely used for RO pretreatment, but ceramic UF membranes can also be an alternative for the filtration of marine algal solutions. The fouling potential of the Red Sea and the Arabian Sea, sampled at different seasons, along with four algal monocultures grown in laboratory, and one mesocosm experiment in the Red Sea was investigated. Algal solutions induce a stronger and more irreversible fouling than terrestrial humic solution, toward ceramic membrane. During algal bloom events, this fouling is enhanced and becomes even more problematic at the decline phase of the bloom, for a similar initial DOC. Three main mechanisms are involved: the formation of a cake layer at the membrane surface; the penetration of the algal organic matter (AOM) in the pore network of the membrane; the strong adhesion of AOM with the membrane surface. The last mechanism is species-specific and metal-oxide specific. In order to understand the stronger ceramic UF fouling at the decline phase, AOM quality was analyzed every two days. During growth, AOM is getting enriched in High Molecular Weight (HMW) structures (> 200 kDa), which are mainly composed by proteins and polysaccharides, and these compounds seem to be responsible for the stronger fouling at decline phase. In order to prevent the fouling of ceramic membrane, coagulation-flocculation (CF) using ferric chloride was implemented prior to filtration. It permits a high removal of HMW compounds and greatly reduces the fouling potential of the algal solution. During brief algal bloom events, CF should be

  8. A new classification system for all-ceramic and ceramic-like restorative materials.

    Gracis, Stefano; Thompson, Van P; Ferencz, Jonathan L; Silva, Nelson R F A; Bonfante, Estevam A

    2015-01-01

    Classification systems for all-ceramic materials are useful for communication and educational purposes and warrant continuous revisions and updates to incorporate new materials. This article proposes a classification system for ceramic and ceramic-like restorative materials in an attempt to systematize and include a new class of materials. This new classification system categorizes ceramic restorative materials into three families: (1) glass-matrix ceramics, (2) polycrystalline ceramics, and (3) resin-matrix ceramics. Subfamilies are described in each group along with their composition, allowing for newly developed materials to be placed into the already existing main families. The criteria used to differentiate ceramic materials are based on the phase or phases present in their chemical composition. Thus, an all-ceramic material is classified according to whether a glass-matrix phase is present (glass-matrix ceramics) or absent (polycrystalline ceramics) or whether the material contains an organic matrix highly filled with ceramic particles (resin-matrix ceramics). Also presented are the manufacturers' clinical indications for the different materials and an overview of the different fabrication methods and whether they are used as framework materials or monolithic solutions. Current developments in ceramic materials not yet available to the dental market are discussed.

  9. Industrial ceramics in Spain

    Regueiro, M.

    2000-02-01

    Full Text Available The Spanish ceramic industry has experienced a amazing growth in the last four years. Such expansion has affected all sector, but has been particularly noteworthy in those directly related to construction: tiles. glazes, bricks and roof tiles. A combination of an extraordinary exporting effort, together with a record figure in new housing projects (415 000 houses in 1999, are responsible for such outburst. Other sectors, such as refractories have undergone significant growths due to the high rate of steel production increase, also in historical record figures (15m t in 1999. All this sectors doubled altogether the growing rate of their main European competitors. Raw material production has had an even more effervescent trend, almost doubling 1995 production. Such dynamic growth has been associated to a remarkable quality increase and to an unparalleled technological innovation process.

    La industria española de la cerámica ha experimentado un notable crecimiento en los últimos cuatro años; expansión que ha alcanzado a todos los sectores, pero que ha sido especialmente notable en los mas directamente asociados a la construcción: revestimientos, esmaltes, tejas y ladrillos. La combinación de un extraordinario esfuerzo exportador unido a las cifras récord en la viviendas iniciadas, 415 000 en 1999, justifican este auge. Otros sectores como refractarios han experimentado crecimientos significativos ante el ritmo elevado en la producción de acero, que alcanzó asimismo un récord histórico, 15 Mt en 1999. Para el conjunto de estos sectores el ritmo de crecimiento ha duplicado el de los principales competidores europeos. La producción de materias primas han experimentado un dinamismo aún mas elevado duplicándose prácticamente las cifras respecto a 1995. Este crecimiento ha estado asociado a un notable incremento en la calidad y en los procesos de innovación tecnológica.

  10. Dispersion toughened silicon carbon ceramics

    Wei, G.C.

    1984-01-01

    Fracture resistant silicon carbide ceramics are provided by incorporating therein a particulate dispersoid selected from the group consisting of (a) a mixture of boron, carbon and tungsten, (b) a mixture of boron, carbon and molybdenum, (c) a mixture of boron, carbon and titanium carbide, (d) a mixture of aluminum oxide and zirconium oxide, and (e) boron nitride. 4 figures.

  11. Microstructural Design for Tough Ceramics

    1994-10-01

    or Rockwell cones) where the contact pressure (i.e. the ’hardness’) is effectively independent of load (Sperisen, Carry and Mocellin 1986, Makino...148. RrrcHM, R. 0., 1988, Mater. Sci. Engng, A, 103, 15. SPERmEN, T., CARRY, C., and MOCELLIN , A, 1986, Fracture Mechanics of Ceramics, Vol. 8, edited

  12. Electrical Degradation in Ceramic Dielectrics

    1988-09-09

    and D. M. Smyth, " Positron Annihilation in Calcium-Doped Barium Titanate", in Electro- Ceramics and Solid State Ionsi, H. L. Tuller and D. M. Smyth...2 with the formation of ompensating oxygen vacancies, and this causes an increase in the ioni conductivity: 2CaO CaC + Call + 20 + (5) TiO2 --- V

  13. Natural Radioactivity in Ceramic Materials

    Abu Khadra, S.A.; Kamel, N.H.

    2005-01-01

    Ceramics are one of the most important types of the industrial building materials. The raw materials of the ceramic are made of a mixture of clay, feldspar, silica, talc kaolin minerals together with zirconium silicates (ZrSiO4).The ceramic raw materials and the final products contain naturally occurring radionuclide mainly U-238 and, Th-232 series, and the radioactive isotope of potassium K-40. Six raw ceramic samples were obtained from the Aracemco Company at Egypt together with a floor tile sample (final product) for measuring radioactive concentration levels., The activity of the naturally U-238, Th-232, and K-40 were determined as (Bq/kg) using gamma spectroscopy (Hyperactive pure germanium detector). Concentration of U and Th were determined in (ppm) using spectrophotometer technique by Arsenazo 111 and Piridy l-Azo -Resorcinol (PAR) indicators. Sequential extraction tests were carried out in order to determine the quantity of the radionuclide associated with various fractions as exchangeable, carbonate, acid soluble and in the residue. The results evaluated were compared to the associated activity indices (AI) that were defined by former USSR and West Germany

  14. Radiation Effects in Nuclear Ceramics

    L. Thomé

    2012-01-01

    Full Text Available Due to outstanding physicochemical properties, ceramics are key engineering materials in many industrial domains. The evaluation of the damage created in ceramics employed in radiative media is a challenging problem for electronic, space, and nuclear industries. In this latter field, ceramics can be used as immobilization forms for radioactive wastes, inert fuel matrices for actinide transmutation, cladding materials for gas-cooled fission reactors, and structural components for fusion reactors. Information on the radiation stability of nuclear materials may be obtained by simulating the different types of interactions involved during the slowing down of energetic particles with ion beams delivered by various types of accelerators. This paper presents a review of the radiation effects occurring in nuclear ceramics, with an emphasis on recent results concerning the damage accumulation processes. Energetic ions in the KeV-GeV range are used to explore the nuclear collision (at low energy and electronic excitation (at high energy regimes. The recovery by electronic excitation of the damage created by ballistic collisions (SHIBIEC process is also addressed.

  15. Ceramic microspheres for cementing applications

    2011-01-01

    A method and apparatus for manufacturing ceramic microspheres from industrial slag. The microspheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about 11 lbs/g. The resultant cement slurry may then be

  16. Ceramic microspheres for cementing applications

    2010-01-01

    A method and apparatus for manufacturing ceramic microspheres from industrial slag. The microspheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about 11 lbs/g. The resultant cement slurry may then be

  17. Ceramic microspheres for cementing applications

    2012-01-01

    A method and apparatus for manufacturing ceramic microspheres from industrial slag. The microspheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about 11 lbs/g. The resultant cement slurry may then be

  18. [Posterior ceramic bonded partial restorations].

    Mainjot, Amélie; Vanheusden, Alain

    2006-01-01

    Posterior ceramic bonded partial restorations are conservative and esthetic approaches for compromised teeth. Overlays constitute a less invasive alternative for tooth tissues than crown preparations. With inlays and onlays they are also indicated in case of full arch or quadrant rehabilitations including several teeth. This article screens indications and realization of this type of restorations.

  19. GEORGIAN PRODUCTION PREFABRICATED CERAMIC FIREPLACE

    Gaprindashvili, G.; Chemia, M.; Kartozia, L.

    2006-01-01

    General description and basic working principles of new construction prefabricated ceramic fireplace are given. The presented fireplace represents a unique synthesis of various fireplaces distributed in Georgian and some European countries; however, it is distinguished for its higher efficiency and other advantages. (author)

  20. Monolithic Integrated Ceramic Waveguide Filters

    Hunter, IC; Sandhu, MY

    2014-01-01

    Design techniques for a new class of integrated monolithic high permittivity ceramic waveguide filters are presented. These filters enable a size reduction of 50% compared to air-filled TEM filters with the same unloaded Q-Factor. Designs for both chebyshev and asymmetric generalized chebyshev filter are presented, with experimental results for an 1800 MHz chebyshev filter showing excellent agreement with theory.

  1. Compositionally Graded Multilayer Ceramic Capacitors.

    Song, Hyun-Cheol; Zhou, Jie E; Maurya, Deepam; Yan, Yongke; Wang, Yu U; Priya, Shashank

    2017-09-27

    Multilayer ceramic capacitors (MLCC) are widely used in consumer electronics. Here, we provide a transformative method for achieving high dielectric response and tunability over a wide temperature range through design of compositionally graded multilayer (CGML) architecture. Compositionally graded MLCCs were found to exhibit enhanced dielectric tunability (70%) along with small dielectric losses (filters and power converters.

  2. Soft lithography of ceramic patterns

    Göbel, Ole; Nedelcu, M.; Steiner, U.

    2007-01-01

    Polymer-based precursor solutions are patterned using a soft-lithographic patterning technique to yield sub-micrometer-sized ceramic patterns. By using a polymer-metal-nitrate solution as a lithographic resist, we demonstrate a micromolding procedure using a simple rubber stamp that yields a

  3. Science and Technology of Ceramics

    These ceramics are developed by chemical synthesis, in other words, they ... Science in 1980 and was a post doctoral ... complex crystal structures that have anisotropic characteristics. (Box 1) .... is a rare-earth or transition metal ion) and hexagonal ferrites. .... dielectric loss factor and dielectric strength normally determine.

  4. Photovoltaic effect in ferroelectric ceramics

    Epstein, D. J.; Linz, A.; Jenssen, H. P.

    1982-01-01

    The ceramic structure was simulated in a form that is more tractable to correlation between experiment and theory. Single crystals (of barium titanate) were fabricated in a simple corrugated structure in which the pedestals of the corrugation simulated the grain while the intervening cuts could be filled with materials simulating the grain boundaries. The observed photovoltages were extremely small (100 mv).

  5. Doubled-ended ceramic thyratron

    1974-01-01

    The double-ended ceramic thyratron CX 1171 B, with its coaxial voltage divider for the SPS. Such a switch, paralleled by three ignitrons in series forms the "thyragnitron" arrangement, and can switch 10 kA, 25 ms pulses, with very fast rise times.

  6. Ceramic matrix composite article and process of fabricating a ceramic matrix composite article

    Cairo, Ronald Robert; DiMascio, Paul Stephen; Parolini, Jason Robert

    2016-01-12

    A ceramic matrix composite article and a process of fabricating a ceramic matrix composite are disclosed. The ceramic matrix composite article includes a matrix distribution pattern formed by a manifold and ceramic matrix composite plies laid up on the matrix distribution pattern, includes the manifold, or a combination thereof. The manifold includes one or more matrix distribution channels operably connected to a delivery interface, the delivery interface configured for providing matrix material to one or more of the ceramic matrix composite plies. The process includes providing the manifold, forming the matrix distribution pattern by transporting the matrix material through the manifold, and contacting the ceramic matrix composite plies with the matrix material.

  7. Raw materials from the region of Rio Claro - SP for the manufacture of ceramic coatings: technological characteristics and geological-technological modeling; Materias-primas da regiao de Rio Claro - SP para fabricacao de revestimentos ceramicos: caracteristicas tecnologicas e modelamento geologico-tecnologico

    Cunha, R.A.; Roveri, C.D.; Maestrelli, S.C., E-mail: rafael.azevedodacunha@gmail.com [Universidade Federal de Alfenas (UNIFAL), Pocos de Caldas, MG (Brazil)

    2016-07-01

    The Santa Gertrudes Ceramic Polo (PCSG) is the largest national producer of ceramic tiles, located in east-central region of Sao Paulo, encompassing different cities. PCSG uses various clays as the main raw material from the Corumbatai Formation, which is inserted in the Sedimentary Basin of Parana, with more than 1.5 square kilometers. In this context, X-ray diffractograms of samples from different areas of PCSG were used for application of the cluster analysis. Aiming to group the samples in families and subsequently to seek the most representative for the complete analysis. Also, ceramic tests were made by the following methods: the green bulk density after pressing, flexural strength modulus for green. , tests were conducted after firing at 1070 °C and 1120 °C: apparent density after drying, flexural modulus; after firing: apparent density after firing, water absorption linear shrinkage sintering, apparent porosity, modulus of resistance to bending after burning. Further, from the georeferenced sample were created tables for industry in the area, to facilitate the identification of new sample by XRD. Furthermore, the 3D model of the region was developed from the interesting characteristics for ceramic use, using Micromine Mining Software, Enterprise Micromine. (author)

  8. Application of neutron activation analysis in study of ancient ceramics

    Li Guoxia; Zhao Weijuan; Gao Zhengyao; Xie Jianzhong; Huang Zhongxiang; Jia Xiuqin; Han Song

    2000-01-01

    Trace-elements in ancient ceramics and imitative ancient ceramics were determined by neutron activation analysis (NAA). The NAA data are then analyzed by fuzzy cluster method and the trend cluster diagram is obtained. The raw material sources of ancient ceramics and imitative ancient ceramics are determined. The path for improving quality of imitative ancient ceramics is found

  9. Translucency of dental ceramics with different thicknesses.

    Wang, Fu; Takahashi, Hidekazu; Iwasaki, Naohiko

    2013-07-01

    The increased use of esthetic restorations requires an improved understanding of the translucent characteristics of ceramic materials. Ceramic translucency has been considered to be dependent on composition and thickness, but less information is available about the translucent characteristics of these materials, especially at different thicknesses. The purpose of this study was to investigate the relationship between translucency and the thickness of different dental ceramics. Six disk-shaped specimens of 8 glass ceramics (IPS e.max Press HO, MO, LT, HT, IPS e.max CAD LT, MO, AvanteZ Dentin, and Trans) and 5 specimens of 5 zirconia ceramics (Cercon Base, Zenotec Zr Bridge, Lava Standard, Lava Standard FS3, and Lava Plus High Translucency) were prepared following the manufacturers' instructions and ground to a predetermined thickness with a grinding machine. A spectrophotometer was used to measure the translucency parameters (TP) of the glass ceramics, which ranged from 2.0 to 0.6 mm, and of the zirconia ceramics, which ranged from 1.0 to 0.4 mm. The relationship between the thickness and TP of each material was evaluated using a regression analysis (α=.05). The TP values of the glass ceramics ranged from 2.2 to 25.3 and the zirconia ceramics from 5.5 to 15.1. There was an increase in the TP with a decrease in thickness, but the amount of change was material dependent. An exponential relationship with statistical significance (Pceramics and zirconia ceramics. The translucency of dental ceramics was significantly influenced by both material and thickness. The translucency of all materials increased exponentially as the thickness decreased. All of the zirconia ceramics evaluated in the present study showed some degree of translucency, which was less sensitive to thickness compared to that of the glass ceramics. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  10. Method of forming a ceramic to ceramic joint

    Cutler, Raymond Ashton; Hutchings, Kent Neal; Kleinlein, Brian Paul; Carolan, Michael Francis

    2010-04-13

    A method of joining at least two sintered bodies to form a composite structure, includes: providing a joint material between joining surfaces of first and second sintered bodies; applying pressure from 1 kP to less than 5 MPa to provide an assembly; heating the assembly to a conforming temperature sufficient to allow the joint material to conform to the joining surfaces; and further heating the assembly to a joining temperature below a minimum sintering temperature of the first and second sintered bodies. The joint material includes organic component(s) and ceramic particles. The ceramic particles constitute 40-75 vol. % of the joint material, and include at least one element of the first and/or second sintered bodies. Composite structures produced by the method are also disclosed.

  11. Ceramic fiber reinforced glass-ceramic matrix composite

    Bansal, Narottam P. (Inventor)

    1993-01-01

    A slurry of BSAS glass powders is cast into tapes which are cut to predetermined sizes. Mats of continuous chemical vapor deposition (CVD)-SiC fibers are alternately stacked with these matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite which is heated to burn out organic constituents. The remaining interim material is then hot-pressed to form a BSAS glass-ceramic fiber-reinforced composite.

  12. Evaluation of Monolithic Ceramics and Ceramic Thermal Barrier Coatings for Diesel Engine Applications

    Swab, Jeffrey J

    2001-01-01

    The Metals and Ceramics Research Branch (MCRB) of the Weapons and Materials Research Directorate is providing ceramic material characterization and evaluation to the Tank Automotive Research, Development, and Engineering Center (TARDEC...

  13. A fractographic study of clinically retrieved zirconia–ceramic and metal–ceramic fixed dental prostheses

    Pang, Zhen; Chughtai, Asima; Sailer, Irena; Zhang, Yu

    2015-01-01

    A recent 3-year randomized controlled trial (RCT) of tooth supported three- to five-unit zirconia-ceramic and metal-ceramic posterior fixed dental prostheses (FDPs) revealed that veneer chipping and fracture in zirconia-ceramic systems occurred more frequently than those in metal-ceramic systems [1]. This study seeks to elucidate the underlying mechanisms responsible for the fracture phenomena observed in this RCT using a descriptive fractographic analysis

  14. Werkstoffwoche 98. Vol. 7. Symposium 9: Ceramics. Symposium 14: Simulation of ceramics

    Heinrich, J.; Ziegler, G.; Hermel, W.; Riedel, H.

    1999-01-01

    The leading subject of this proceedings volume is ceramic materials, with papers on the following subject clusters: Processing (infiltration, sintering, forming) - Physics and chemistry of ceramics (functional ceramics, SiC, ceramic precursors, microstructural properties) - Novel concepts (composites, damage induced by oxidation and mechanical stress, performance until damage under mechanical and thermal stress, layers, nanocomposites). 28 of the conference papers have been prepared for individual retrieval from the ENERGY database. (orig./CB) [de

  15. Y-TZP ceramic processing from coprecipitated powders: a comparative study with three commercial dental ceramics.

    Lazar, Dolores R R; Bottino, Marco C; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H A

    2008-12-01

    (1) To synthesize 3mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. A coprecipitation route was used to synthesize a 3mol% yttria-stabilized zirconia ceramic processed by uniaxial compaction and pressureless sintering. Commercially available alumina or alumina/zirconia ceramics, namely Procera AllCeram (PA), In-Ceram Zirconia Block (CAZ) and In-Ceram Zirconia (IZ) were chosen for comparison. All specimens (6mmx5mmx5mm) were polished and ultrasonically cleaned. Qualitative phase analysis was performed by XRD and apparent densities were measured on the basis of Archimedes principle. Ceramics were also characterized using SEM, TEM and EDS. The hardness measurements were made employing Vickers hardness test. Fracture toughness (K(IC)) was calculated. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's test (alpha=0.05). ANOVA revealed that the Vickers hardness (pceramic materials composition. It was confirmed that the PA ceramic was constituted of a rhombohedral alumina matrix, so-called alpha-alumina. Both CAZ and IZ ceramics presented tetragonal zirconia and alpha-alumina mixture of phases. The SEM/EDS analysis confirmed the presence of aluminum in PA ceramic. In the IZ and CAZ ceramics aluminum, zirconium and cerium in grains involved by a second phase containing aluminum, silicon and lanthanum were identified. PA showed significantly higher mean Vickers hardness values (H(V)) (18.4+/-0.5GPa) compared to vitreous CAZ (10.3+/-0.2GPa) and IZ (10.6+/-0.4GPa) ceramics. Experimental Y-TZP showed significantly lower results than that of the other monophased ceramic (PA) (pceramics (pceramic processing conditions led to ceramics with mechanical properties comparable to commercially available reinforced ceramic materials.

  16. Application of nuclear magnetic resonance in osteoporosis evaluation; Aplicacoes de ressonancia magnetica nuclear na avaliacao de osteoporose

    Giannoni, Ricardo A., E-mail: giannoni@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Montrazi, Elton T.; Bonagamba, Tito J., E-mail: elton.montrazi@gmail.com, E-mail: tito@ifsc.usp.br [Universidade de Sao Paulo (IFSC/USP), Sao Carlos, SP (Brazil). Inst. de Fisica; Cesar, Reinaldo, E-mail: reinaldofisica@gmail.com [Universidade de Sao Paulo (EESC/USP), Sao Carlos, SP (Brazil). Escola de Engenharia

    2013-07-01

    In this work, initially ceramic samples of known porosity were used. These ceramic samples were saturated with water. The nuclear magnetic resonance signal due to relaxation processes that the hydrogen nucleus water contained in the pores of this ceramic material was measured. Then these samples were subjected to a process of drying and measures successively. As the water contained in pores greater evaporates the intensity of signal decreases and shows the sign because of the smaller pores. The analysis of this drying process gives a qualitative assessment of the pore size of the material. In a second step, bones of animals of unknown porosity underwent the same methodology for evaluating osteoporosis. Also a sample of human vertebra in a unique manner, with the same purpose was measured. Combined with other techniques is a quantitative evaluation of the possible porosity.

  17. Salt splitting with ceramic membranes

    Kurath, D.

    1996-01-01

    The purpose of this task is to develop ceramic membrane technologies for salt splitting of radioactively contaminated sodium salt solutions. This technology has the potential to reduce the low-level waste (LLW) disposal volume, the pH and sodium hydroxide content for subsequent processing steps, the sodium content of interstitial liquid in high-level waste (HLW) sludges, and provide sodium hydroxide free of aluminum for recycle within processing plants at the DOE complex. Potential deployment sites include Hanford, Savannah River, and Idaho National Engineering Laboratory (INEL). The technical approach consists of electrochemical separation of sodium ions from the salt solution using sodium (Na) Super Ion Conductors (NaSICON). As the name implies, sodium ions are transported rapidly through these ceramic crystals even at room temperatures

  18. Ceramics: Durability and radiation effects

    Ewing, R.C.; Lutze, W. [Univ. of New Mexico, Albuquerque, NM (United States); Weber, W.J. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-05-01

    At present, there are three seriously considered options for the disposition of excess weapons plutonium: (1) incorporation, partial burn-up and direct disposal of MOX-fuel; (2) vitrification with defense waste and disposal as glass {open_quotes}logs{close_quotes}; (3) deep borehole disposal. The first two options provide a safeguard due to the high activity of fission products in the irradiated fuel and the defense waste. The latter option has only been examined in a preliminary manner, and the exact form of the plutonium has not been identified. In this paper, we review the potential for the immobilization of plutonium in highly durable crystalline ceramics apatite, pyrochlore, zirconolite, monazite and zircon. Based on available data, we propose zircon as the preferred crystalline ceramic for the permanent disposition of excess weapons plutonium.

  19. Interfaces in ceramic nuclear fuels

    Reeve, K.D.

    Internal interfaces in all-ceramic dispersion fuels (such as these for HTGRs) are discussed for two classes: BeO-based dispersions, and coated particles for graphite-based fuels. The following points are made: (1) The strength of a two-phase dispersion is controlled by the weaker dispersed phase bonded to the matrix. (2) Differential expansion between two phases can be controlled by an intermediate buffer zone of low density. (3) A thin ceramic coating should be in compression. (4) Chemical reaction between coating and substrate and mass transfer in service should be minimized. The problems of the nuclear fuel designer are to develop coatings for fission product retention, and to produce radiation-resistant interfaces. 44 references, 18 figures

  20. Silsesquioxane-derived ceramic fibres

    Hurwitz, F. I.; Farmer, S. C.; Terepka, F. M.; Leonhardt, T. A.

    1991-01-01

    Fibers formed from blends of silsesquioxane polymers were characterized to study the pyrolytic conversion of these precursors to ceramics. The morphology of fibers pyrolyzed to 1400 C revealed primarily amorphous glasses whose conversion to beta-SiC is a function of both blend composition and pyrolysis conditions. Formation of beta-SiC crystallites within the glassy phase is favored by higher than stoichiometric C/Si ratios, while carbothermal reduction of Si-O bonds to form SiC with loss of SiO and CO occurs at higher methyl/phenylpropyl silsesquioxane (lower C/Si) ratios. As the carbothermal reduction is assumed to be diffusion controlled, the fibers can serve as model systems to gain understanding of the silsesquioxane pyrolysis behavior, and therefore are useful in the development of polysilsesquioxane-derived ceramic matrices and coatings as well.

  1. Microimpurity composition of superconducting ceramics

    Zhiglov, Yu.S.; Poltoratskij, Yu.B.; Protsenko, A.N.; Tuchin, O.V.

    1989-01-01

    Using laser mass spectrometry, the microimpurity composition of YBa 2 Cu 3 O 7-y superconducting ceramics, prepared by routine solid-phase synthesis from extremely pure yttrium and copper oxides and BaCO 3 , is determined. The presence of F, Na, Al, P, Cl, S, K, Ca impurities, which concentration in specimens varies within 10 -3 +5x10 -3 at.% and also Si, Sr, Fe of about 1x10 -1 at.% is established. It is difficult to determine concentrations of C, N, H 2 O impurities because of the presence of background signals of residual gases in the chamber. Using the method of Auger electron spectroscopy, a surface layer of HTSC ceramics grain is studied. The availability of chlorine impurity, which amount considerably exceeds its volume concentration, is determined in near the surface layer. 2 refs.; 2 figs

  2. Surface treatment of zirconia ceramics

    1980-01-01

    A method of chemically micropitting and/or microcratering at least a portion of a smooth surface of an impervious zirconia-base ceramic is described, comprising (a) contacting the smooth surface with a liquid leachant selected from concentrated sulphuric acid, ammonium bisulphate, alkali metal bisulphates and mixtures thereof at a temperature of at least 250 0 C for a period of time sufficient to effect micropitting and/or microcratering generally uniformly distributed throughout the microstructure of the resultant leached surface; (b) removing the leached surface from contact with the leachant; (c) contacting the leached surface with hydrochloric acid to effect removal from the leached surface of a residue thereon comprising sulphate of metal elements including zirconium in the ceramic; (d) removing the leached surface from contact with the hydrochloric acid; and (e) rinsing the leached surface with water to effect removal of acid residue from that surface. (author)

  3. LUCRO, VALOR CONTABIL E DIVIDENDOS NA AVALIAcAO DO PATRIMÔNIO LIQUIDO

    James A. Ohlson

    2009-09-01

    Full Text Available A contabilidade atribui uma importante função integrativa a demonstração das mutações do patrimônio liquido. A demonstração inclui os itens mais importantes do balanço o e da demonstração de resultado do exercício - o valor do patrimônio liquido e o lucro - e sua forma de apresentação exige que a alteração no valor do patrimônio liquido seja igual ao lucro menos os dividendos (líquidos das contribuições para aumento de capital. Referimo-nos a essa relação corno sendo a “relação de lucro limpo", pois, da forma como foi articulada, todas as alterações nos ativos e passivos que não estejam relacionadas com os dividendos devem passar pela demonstração de resultado do exercício. A teoria da contabilidade adota geralmente esse esquema sem relacioná-lo a perspectiva do usuário dos dados contábeis. Contudo, a idéia fundamental de que estoques (líquidos de valor são compatíveis com a criação c distribuição de valor levanta uma questão básica no contexto de avalia4ao do patrimônio liquido: e possível delinear urna teoria coesiva do valor de uma firma sustentada pela relação de lucro limpo, no intuito de se identificar um papel claro para cada uma das três variáveis, quais sejam: o lucro, o valor contábil do patrimônio liquido e os dividendos?

  4. Tensile Properties of Open Cell Ceramic Foams

    Dlouhý, Ivo; Řehořek, Lukáš; Chlup, Zdeněk

    2009-01-01

    Roč. 409, - (2009), s. 168-175 ISSN 1013-9826. [Fractography of Advanced Ceramics /3./. Stará Lesná, 07.09.2008-10.09.2008] R&D Projects: GA ČR(CZ) GA106/06/0724; GA ČR GD106/05/H008 Institutional research plan: CEZ:AV0Z20410507 Keywords : tensile test * ceramics foam * open porosity * tensile strength Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  5. Acid-base properties of ceramic powders

    Bleier, A.

    1983-01-01

    This chapter addresses the fundamental aspects of potentiometric titration, electrokinetics, and conductometric titration in evaluating surface and interfacial thermodynamic behavior. Emphasizes the characterization of aqueous systems which are pertinent to the processing of ceramic powders. Attempts to clarify the role of novel analytical techniques that will increasingly contribute to the advanced characterization of ceramic powders. Evaluates recently developed acid-base and complexation concepts and their applications to the processing of oxide ceramics

  6. Structure and conductivity of nanostructured YBCO ceramics

    Palchayev, D. K.; Gadzhimagomedov, S. Kh; Murlieva, Zh Kh; Rabadanov, M. Kh; Emirov, R. M.

    2017-12-01

    Superconducting nanostructured ceramics based on YBa2Cu3O7-δ were made of nanopowder obtained by burning nitrate-organic precursors. The structure, morphology, electrical resistivity, and density of ceramics were studied. Various porosity values of the ceramics were achieved by preliminary heat treatment of the nanopowder. The features of conductivity and the reason for increase of the of the superconducting transition temperature in these materials are discussed.

  7. Advanced ceramics: the present and the perspectives

    Freitas, C.T. de.

    1990-04-01

    Development in the Brazilian and international areas of advanced ceramics is described, emphasizing its economic perspectivas and industrial applications. Results obtained by national institutions are reviewed, mainly in the context of those that pioneered the required high technology in this ceramic field. The rapid growth of the interest for those special materials, made more evident by ample information related to the superconducting ceramics great pontential for important practical applications, is one of the most significant characteristics of the area. (author) [pt

  8. Piezoelectric ceramic-reinforced metal matrix composites

    2004-01-01

    Composite materials comprising piezoelectric ceramic particulates dispersed in a metal matrix are capable of vibration damping. When the piezoelectric ceramic particulates are subjected to strain, such as the strain experienced during vibration of the material, they generate an electrical voltage that is converted into Joule heat in the surrounding metal matrix, thereby dissipating the vibrational energy. The piezoelectric ceramic particulates may also act as reinforcements to improve the mec...

  9. High temperature fracture of ceramic materials

    Wiederhorn, S.M.

    1979-01-01

    A review is presented of fracture mechanisms and methods of lifetime prediction in ceramic materials. Techniques of lifetime prediction are based on the science of fracture mechanics. Application of these techniques to structural ceramics is limited by our incomplete understanding of fracture mechanisms in these materials, and by the occurrence of flaw generation in these materials at elevated temperatures. Research on flaw generation and fracture mechanisms is recommended as a way of improving the reliability of structural ceramics

  10. Performance characteristics of porous alumina ceramic structures

    Latella, B.A.; Liu, T.

    2000-01-01

    Porous ceramics have found a wide range of applications as filters for liquids and gases. The suitability of materials for use in these types of applications depends on the microstructure (grain size, pore size and pore volume fraction) and hence the mechanical and thermal properties. In this study alumina ceramics with different levels of porosity and controlled pore sizes were fabricated and the surface damage and fracture properties were examined. Copyright (2000) The Australian Ceramic Society

  11. Strength and Microstructure of Ceramics

    1989-11-01

    Forex - one particular alumina ceramic, I our own detailed crack ample, the relatively large values of r, and c* for the VI observations, and those of...particularly toughness indices, 1i71", indicating that there is sonic the c° , T parameters. However, the indentation mcth- kind of trade -o1Tbetwecn...macroscopic and microsnpic odology takes us closer to the strengths of specimens toughness levels, and that this trade -off is cont’olled by with natural

  12. Flash sintering of ceramic materials

    Dancer, C. E. J.

    2016-10-01

    During flash sintering, ceramic materials can sinter to high density in a matter of seconds while subjected to electric field and elevated temperature. This process, which occurs at lower furnace temperatures and in shorter times than both conventional ceramic sintering and field-assisted methods such as spark plasma sintering, has the potential to radically reduce the power consumption required for the densification of ceramic materials. This paper reviews the experimental work on flash sintering methods carried out to date, and compares the properties of the materials obtained to those produced by conventional sintering. The flash sintering process is described for oxides of zirconium, yttrium, aluminium, tin, zinc, and titanium; silicon and boron carbide, zirconium diboride, materials for solid oxide fuel applications, ferroelectric materials, and composite materials. While experimental observations have been made on a wide range of materials, understanding of the underlying mechanisms responsible for the onset and latter stages of flash sintering is still elusive. Elements of the proposed theories to explain the observed behaviour include extensive Joule heating throughout the material causing thermal runaway, arrested by the current limitation in the power supply, and the formation of defect avalanches which rapidly and dramatically increase the sample conductivity. Undoubtedly, the flash sintering process is affected by the electric field strength, furnace temperature and current density limit, but also by microstructural features such as the presence of second phase particles or dopants and the particle size in the starting material. While further experimental work and modelling is still required to attain a full understanding capable of predicting the success of the flash sintering process in different materials, the technique non-etheless holds great potential for exceptional control of the ceramic sintering process.

  13. Metallizing of machinable glass ceramic

    Seigal, P.K.

    1976-02-01

    A satisfactory technique has been developed for metallizing Corning (Code 9658) machinable glass ceramic for brazing. Analyses of several bonding materials suitable for metallizing were made using microprobe analysis, optical metallography, and tensile strength tests. The effect of different cleaning techniques on the microstructure and the effect of various firing temperatures on the bonding interface were also investigated. A nickel paste, used for thick-film application, has been applied to obtain braze joints with strength in excess of 2000 psi

  14. Wear of human enamel opposing monolithic zirconia, glass ceramic, and composite resin: an in vitro study.

    Sripetchdanond, Jeerapa; Leevailoj, Chalermpol

    2014-11-01

    Demand is increasing for ceramic and composite resin posterior restorations. However, ceramics are recognized for their high abrasiveness to opposing dental structure. The purpose of this study was to investigate the wear of enamel as opposed to dental ceramics and composite resin. Twenty-four test specimens (antagonists), 6 each of monolithic zirconia, glass ceramic, composite resin, and enamel, were prepared into cylindrical rods. Enamel specimens were prepared from 24 extracted human permanent molar teeth. Enamel specimens were abraded against each type of antagonist with a pin-on-disk wear tester under a constant load of 25 N at 20 rpm for 4800 cycles. The maximum depth of wear (Dmax), mean depth of wear (Da), and mean surface roughness (Ra) of the enamel specimens were measured with a profilometer. All data were statistically analyzed by 1-way ANOVA, followed by the Tukey test (α=.05). A paired t test was used to compare the Ra of enamel at baseline and after testing. The wear of both the enamel and antagonists was evaluated qualitatively with scanning electron microscopic images. No significant differences were found in enamel wear depth (Dmax, Da) between monolithic zirconia (2.17 ±0.80, 1.83 ±0.75 μm) and composite resin (1.70 ±0.92, 1.37 ±0.81 μm) or between glass ceramic (8.54 ±2.31, 7.32 ±2.06 μm) and enamel (10.72 ±6.31, 8.81 ±5.16 μm). Significant differences were found when the enamel wear depth caused by monolithic zirconia and composite resin was compared with that of glass ceramic and enamel (Pglass ceramic, and enamel (Pglass ceramic and enamel. All test materials except composite resin similarly increased the enamel surface roughness after wear testing. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  15. Energy storage in ceramic dielectrics

    Love, G.R.

    1990-01-01

    Historically, multilayer ceramic capacitors (MLC's) have not been considered for energy storage applications for two primary reasons. First, physically large ceramic capacitors were very expensive and, second, total energy density obtainable was not nearly so high as in electrolytic capacitor types. More recently, the fabrication technology for MLC's has improved significantly, permitting both significantly higher energy density and significantly lower costs. Simultaneously, in many applications, total energy storage has become smaller, and the secondary requirements of very low effective series resistance and effective series inductance (which, together, determine how efficiently the energy may be stored and recovered) have become more important. It is therefore desirable to reexamine energy storage in ceramics for contemporary commercial and near-commercial dielectrics. Stored energy is proportional to voltage squared only in the case of paraelectric insulators, because only they have capacitance that is independent of bias voltage. High dielectric constant materials, however, are ferroics (that is ferroelectric and/or antiferroelectric) and display significant variation of effective dielectric constant with bias voltage

  16. The Electrospun Ceramic Hollow Nanofibers

    Shahin Homaeigohar

    2017-11-01

    Full Text Available Hollow nanofibers are largely gaining interest from the scientific community for diverse applications in the fields of sensing, energy, health, and environment. The main reasons are: their extensive surface area that increases the possibilities of engineering, their larger accessible active area, their porosity, and their sensitivity. In particular, semiconductor ceramic hollow nanofibers show greater space charge modulation depth, higher electronic transport properties, and shorter ion or electron diffusion length (e.g., for an enhanced charging–discharging rate. In this review, we discuss and introduce the latest developments of ceramic hollow nanofiber materials in terms of synthesis approaches. Particularly, electrospinning derivatives will be highlighted. The electrospun ceramic hollow nanofibers will be reviewed with respect to their most widely studied components, i.e., metal oxides. These nanostructures have been mainly suggested for energy and environmental remediation. Despite the various advantages of such one dimensional (1D nanostructures, their fabrication strategies need to be improved to increase their practical use. The domain of nanofabrication is still advancing, and its predictable shortcomings and bottlenecks must be identified and addressed. Inconsistency of the hollow nanostructure with regard to their composition and dimensions could be one of such challenges. Moreover, their poor scalability hinders their wide applicability for commercialization and industrial use.

  17. Silicate bonded ceramics of laterites

    Wagh, A.S.; Douse, V.

    1989-05-01

    Sodium silicate is vacuum impregnated in bauxite waste (red mud) at room temperature to develop ceramics of mechanical properties comparable to the sintered ceramics. For a concentration up to 10% the fracture toughness increases from 0.12 MNm -3/2 to 0.9 MNm -3/2 , and the compressive strength from 7 MNm -2 to 30 MNm -2 . The mechanical properties do not deteriorate, when soaked in water for an entire week. The viscosity and the concentration of the silicate solution are crucial, both for the success of the fabrication and the economics of the process. Similar successful results have been obtained for bauxite and lime stone, even though the latter has poor weathering properties. With scanning electron microscopy and energy dispersive analysis, an attempt is made to identify the crystals formed in the composite, which are responsible for the strength. The process is an economic alternative to the sintered ceramics in the construction industry in the tropical countries, rich in lateritic soils and poor in energy. Also the process has all the potential for further development in arid regions abundant in limestone. (author). 6 refs, 20 figs, 3 tabs

  18. All-ceramic restorations: an overview.

    Bassi, F; Carossa, S; Pera, P; Preti, G

    1998-09-01

    Advantages and disadvantages of metal-ceramic and all-ceramic restorations are reviewed particularly from the aesthetic point of view. All-ceramic restorations offer the best results because they let the light through optimally. In constructing all-ceramic crowns on teeth which have been endodontically treated, the material used to rebuild the pin-abutments must be taken into consideration if the best aesthetic results are to be achieved. Materials which, because of their translucent characteristics, are the most aesthetic alternatives to metal alloy pin-abutments in rebuilding teeth which have been endodontically treated, are then described.

  19. Performances of multi-channel ceramic photomultipliers

    Comby, G.; Karolak, M.; Piret, Y.; Mouly, J.P.

    1995-09-01

    Ceramic electron multipliers with real metal dynodes and independent channels ware constructed using multilayer ceramic technology. Tests of these prototypes show their capability to form sensitive detectors such as photomultipliers or light intensifiers. Here, we present results for the photocathode sensitivity, dynode activation, gain, linearity range and dynamic characteristics as well as the effect of 3-year aging of the main operational functions. The advantages provided by the ceramic components are discussed. These results motivate the development of a compact 256 pixel ceramic photomultiplier. (author)

  20. Ceramic technology for Advanced Heat Engines Project

    Johnson, D.R.

    1991-07-01

    Significant accomplishments in fabricating ceramic components for advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and database and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. An assessment of needs was completed, and a five year project plan was developed with extensive input from private industry. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. To facilitate the rapid transfer of this technology to US industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities. This project is managed by ORNL for the Office of Transportation Technologies, Office of Transportation Materials, and is closely coordinated with complementary ceramics tasks funded by other DOE offices, NASA, DOD, and industry.

  1. Portland blended cements: demolition ceramic waste management

    Trezza, M.A.; Zito, S.; Tironi, A.; Irassar, E.F.; Rahhal, V.F.

    2017-01-01

    Demolition ceramic wastes (DCWs) were investigated in order to determine their potential use as supplementary cementitious materials in Portland Blended Cements (PBCs). For this purpose, three ceramic wastes were investigated. After characterization of the materials used, the effect of ceramic waste replacement (8, 24 and 40% by mass) was analyzed. Pozzolanic activity, hydration progress, workability and compressive strength were determined at 2, 7 and 28 days. The results showed that the ground wastes behave as filler at an early age, but as hydration progresses, the pozzolanic activity of ceramic waste contributes to the strength requirement. [es

  2. Manufacturing of superconductive silver/ceramic composites

    Seifi, Behrouz; Bech, Jakob Ilsted; Eriksen, Morten

    2000-01-01

    Manufacturing of superconducting metal/ceramic composites is a rather new discipline within materials forming processes. High Temperature SuperConductors, HTSC, are manufactured applying the Oxide-Powder-In-Tube process, OPIT. A ceramic powder containing lead, calcium, bismuth, strontium, and cop......Manufacturing of superconducting metal/ceramic composites is a rather new discipline within materials forming processes. High Temperature SuperConductors, HTSC, are manufactured applying the Oxide-Powder-In-Tube process, OPIT. A ceramic powder containing lead, calcium, bismuth, strontium...

  3. Review of glass ceramic waste forms

    Rusin, J.M.

    1981-01-01

    Glass ceramics are being considered for the immobilization of nuclear wastes to obtain a waste form with improved properties relative to glasses. Improved impact resistance, decreased thermal expansion, and increased leach resistance are possible. In addition to improved properties, the spontaneous devitrification exhibited in some waste-containing glasses can be avoided by the controlled crystallization after melting in the glass-ceramic process. The majority of the glass-ceramic development for nuclear wastes has been conducted at the Hahn-Meitner Institute (HMI) in Germany. Two of their products, a celsian-based (BaAl 3 Si 2 O 8 ) and a fresnoite-based (Ba 2 TiSi 2 O 8 ) glass ceramic, have been studied at Pacific Northwest Laboratory (PNL). A basalt-based glass ceramic primarily containing diopsidic augite (CaMgSi 2 O 6 ) has been developed at PNL. This glass ceramic is of interest since it would be in near equilibrium with a basalt repository. Studies at the Power Reactor and Nuclear Fuel Development Corporation (PNC) in Japan have favored a glass-ceramic product based upon diopside (CaMgSi 2 O 6 ). Compositions, processing conditions, and product characterization of typical commercial and nuclear waste glass ceramics are discussed. In general, glass-ceramic waste forms can offer improved strength and decreased thermal expansion. Due to typcially large residual glass phases of up to 50%, there may be little improvement in leach resistance

  4. Ceramic Technology For Advanced Heat Engines Project

    1990-12-01

    Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DoD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. The objective of the project is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. This advanced materials technology is being developed in parallel and close coordination with the ongoing DOE and industry proof of concept engine development programs. To facilitate the rapid transfer of this technology to U.S. industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities. Abstracts prepared for appropriate papers.

  5. Tritium behaviour in ceramic breeder blankets

    Miller, J.M.

    1989-01-01

    Tritium release from the candidate ceramic materials, Li 2 O, LiA10 2 , Li 2 SiO 3 , Li 4 SiO 4 and Li 2 ZrO 3 , is being investigated in many blanket programs. Factors that affect tritium release from the ceramic into the helium sweep gas stream include operating temperature, ceramic microstructure, tritium transport and solubility in the solid. A review is presented of the material properties studied and of the irradiation programs and the results are summarized. The ceramic breeder blanket concept is briefly reviewed

  6. Emerging ceramic-based materials for dentistry.

    Denry, I; Kelly, J R

    2014-12-01

    Our goal is to give an overview of a selection of emerging ceramics and issues for dental or biomedical applications, with emphasis on specific challenges associated with full-contour zirconia ceramics, and a brief synopsis on new machinable glass-ceramics and ceramic-based interpenetrating phase composites. Selected fabrication techniques relevant to dental or biomedical applications such as microwave sintering, spark plasma sintering, and additive manufacturing are also reviewed. Where appropriate, the authors have added their opinions and guidance. © International & American Associations for Dental Research.

  7. Measurement of Emissivity of Porous Ceramic Materials

    BÜYÜKALACA, Orhan

    1998-01-01

    In this study, measurements of spectral and total emissivities of seven different porous ceramic materials and one ceramic fibre material are reported. Measurements were made for wavelength range from 1.2 µm to 20 µm and temperature range from 200 °C to 700 °C. It was found that total emissivity increases with increase of pore size but decreases with increase of temperature. The results showed all the porous ceramic materials tested to be much better than ceramic fibre in terms of total em...

  8. A review of the strength properties of dental ceramics.

    Hondrum, S O

    1992-06-01

    New ceramic materials for restorative dentistry have been developed and introduced in recent years. This article reviews advantages and disadvantages of dental ceramics, concentrating on strength properties. Included are factors affecting the strength of dental ceramic materials and the most common mechanisms for increasing the strength of dental ceramics. The properties of presently available materials such as dispersion-strengthened ceramics, cast ceramics, and foil-reinforced materials are discussed. Current research efforts to improve the fracture resistance of ceramic restorative materials are reviewed. A description of methods to evaluate the strength of ceramics is included, as a caution concerning the interpretation of strength data reported in the literature.

  9. Development and characterization of ceramic composites based on alumina-titania reinforced with rare earth oxide (holmium oxide) for the production of inert coatings in metal tanks of petroleum industry; Desenvolvimento e caracterizacao de compositos ceramicos baseados em alumina-titania reforcados com oxido de terra rara (oxido de holmio) para fabricacao de revestimentos inertes em tanques metalicos da industria petrolifera

    Silva, N.D.G.; Pontual, J.O.; Ferreira, R.A.S.; Yadava, Y.P., E-mail: nokaa_demery@hotmail.com, E-mail: yadava@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Departamento de Engenharia Mecanica

    2014-07-01

    Due to the importance of petroleum and its derivatives for modern society, it is necessary to develop technologies that improve processes and transports of petroleum. The crude oil creates hostile environments and in the process of transport and storage of petroleum are used metallic materials, which corrode becoming a critical problem in this industry. One way of solving this problem is the use of ceramics based on alumina as inert coating on hostile environments. In this work was studied a structure, microstructure and mechanical properties of ceramic composite based on Al2O3 - TiO2 reinforced Ho2O3. The composites were produced by a thermomechanical process, sintered at 1350°C, were analyzed by x-ray diffraction, optical microscopy, scanning electron microscopy, and microhardness. Analyses were performed before and after immersion in earth and offshore crude petroleum to study stability of the developed composites and concluded that the ceramic composites immersed in petroleum show stable in hostile environments. (author)

  10. Development of Advanced Ceramic Manufacturing Technology; FINAL

    Pujari, V.K.

    2001-01-01

    Advanced structural ceramics are enabling materials for new transportation engine systems that have the potential for significantly reducing energy consumption and pollution in automobiles and heavy vehicles. Ceramic component reliability and performance have been demonstrated in previous U.S. DOE initiatives, but high manufacturing cost was recognized as a major barrier to commercialization. Norton Advanced Ceramics (NAC), a division of Saint-Gobain Industrial Ceramics, Inc. (SGIC), was selected to perform a major Advanced Ceramics Manufacturing Technology (ACMT) Program. The overall objectives of NAC's program were to design, develop, and demonstrate advanced manufacturing technology for the production of ceramic exhaust valves for diesel engines. The specific objectives were (1) to reduce the manufacturing cost by an order of magnitude, (2) to develop and demonstrate process capability and reproducibility, and (3) to validate ceramic valve performance, durability, and reliability. I n order to achieve these objectives, NAC, a leading U.S. advanced ceramics component manufacturer, assembled a multidisciplinary, vertically integrated team. This team included: a major diesel engine builder, Detroit Diesel Corporation (DDC); a corporate ceramics research division, SGIC's Northboro R and D Center; intelligent processing system developers, BDM Federal/MATSYS; a furnace equipment company, Centorr/Vacuum Industries; a sintering expert, Wittmer Consultants; a production OEM, Deco-Grand; a wheel manufacturer and grinding operation developer, Norton Company's Higgins Grinding Technology Center (HGTC); a ceramic machine shop, Chand Kare Technical Ceramics; and a manufacturing cost consultant, IBIS Associates. The program was divided into four major tasks: Component Design and Specification, Component Manufacturing Technology Development, Inspection and Testing, and Process Demonstration

  11. Prestresses in bilayered all-ceramic restorations.

    Aboushelib, Moustafa N; Feilzer, Albert J; de Jager, Niek; Kleverlaan, Cornelis J

    2008-10-01

    A general trend in all ceramic systems is to use veneering ceramics of slightly lower thermal expansion coefficients compared with that of the framework resulting in a positive mismatch in thermal expansion coefficient (+DeltaTEC). The concept behind this TEC mismatch is to generate compressive stresses in the weaker veneering ceramic and thus enhance the overall strength of the restoration. This technique had excellent results with porcelain fused to metal restorations (PFM). However, there are concerns to apply this concept to all-ceramic restorations. The aim of this research was to determine the stresses in bilayered all-ceramic restorations due to the mismatch in TEC. Two commercial veneering ceramics with a TEC lower than that of zirconia (+DeltaTEC); NobelRondo zirconiatrade mark and Lava Ceramtrade mark, plus one experimental veneering ceramic with an identical TEC that matches that of zirconia (DeltaTEC = 0) were used to veneer zirconia discs. The specimens were loaded in biaxial flexure test setup with the veneer ceramic in tension. The stresses due to load application and TEC mismatch were calculated using fractography, engineering mathematics, and finite element analysis (FEA). In this study, the highest load at failure (64 N) was obtained with the experimental veneer where the thermal mismatch between zirconia and veneering ceramic was minimal. For the two commercial veneer ceramics the magnitude of the thermal mismatch localized at the zirconia veneer interface (42 MPa) exceeded the bond strength between the two materials and resulted in delamination failure during testing (ca. 50 MPa). For all-ceramic zirconia veneered restorations it is recommended to minimize the thermal mismatch as much as possible. (c) 2008 Wiley Periodicals, Inc.

  12. Characterization techniques to predict mechanical behaviour of green ceramic bodies fabricated by ceramic microstereolithography

    Adake, Chandrashekhar V.; Bhargava, Parag; Gandhi, Prasanna

    2018-02-01

    Ceramic microstereolithography (CMSL) has emerged as solid free form (SFF) fabrication technology in which complex ceramic parts are fabricated from ceramic suspensions which are formulated by dispersing ceramic particles in UV curable resins. Ceramic parts are fabricated by exposing ceramic suspension to computer controlled UV light which polymerizes resin to polymer and this polymer forms rigid network around ceramic particles. A 3-dimensional part is created by piling cured layers one over the other. These ceramic parts are used to build microelectromechanical (MEMS) devices after thermal treatment. In many cases green ceramic parts can be directly utilized to build MEMS devices. Hence characterization of these parts is essential in terms of their mechanical behaviour prior to their use in MEMS devices. Mechanical behaviour of these green ceramic parts depends on cross link density which in turn depends on chemical structure of monomer, concentrations of photoinitiator and UV energy dose. Mechanical behaviour can be determined with the aid of nanoindentation. And extent of crosslinking can be verified with the aid of DSC. FTIR characterization is used to analyse (-C=C-) double bond conversion. This paper explains characterization tools to predict the mechanical behaviour of green ceramic bodies fabricated in CMSL

  13. Desolventizing of soybean oil/azeotrope mixtures using ceramic membranes.

    de Melo, Jonas R M; Tiggeman, Lidia; Rezzadori, Katia; Steffens, Juliana; Palliga, Marshall; Oliveira, J Vladimir; Di Luccio, Marco; Tres, Marcus V

    2017-08-01

    This work investigates the use of ceramic membranes with different molecular weight cut-offs (MWCOs: 5, 10 and 20 kDa) to desolventize azeotropic solvent mixtures (ethanol/n-hexane and isopropyl alcohol/n-hexane) from soybean oil/azeotrope micelles. Results show that a decrease in the MWCO of a membrane and an increase in the solvent mass ratio in the mixture resulted in a significant reduction in the permeate flux. The 20 kDa membrane presented the highest permeate flux, 80 and 60 kg/m 2 h for the soybean oil/n-hexane/isopropyl alcohol and soybean oil/n-hexane/ethanol azeotropes, respectively, for an oil to solvent ratio of 1:3 (w/w). The highest oil retention was found using the n-hexane/isopropyl alcohol azeotrope, around 25% in the membrane with the lowest MWCO, that is, 5 kDa. It is shown that the azeotropic mixtures provided intermediate characteristics compared to the original pure solvent behavior.

  14. What every surgeon should know about Ceramic-on-Ceramic bearings in young patients.

    Hernigou, Philippe; Roubineau, François; Bouthors, Charlie; Flouzat-Lachaniette, Charles-Henri

    2016-04-01

    Based on the exceptional tribological behaviour and on the relatively low biological activity of ceramic particles, Ceramic-on-Ceramic (CoC) total hip arthroplasty (THA) presents significant advantagesCoC bearings decrease wear and osteolysis, the cumulative long-term risk of dislocation, muscle atrophy, and head-neck taper corrosion.However, there are still concerns regarding the best technique for implantation of ceramic hips to avoid fracture, squeaking, and revision of ceramic hips with fracture of a component.We recommend that surgeons weigh the potential advantages and disadvantages of current CoC THA in comparison with other bearing surfaces when considering young very active patients who are candidates for THA. Cite this article: Hernigou P, Roubineau F, Bouthors C, Flouzat-Lachaniette C-H. What every surgeon should know about Ceramic-on-Ceramic bearings in young patients. EFORT Open Rev 2016;1:107-111. DOI: 10.1302/2058-5241.1.000027.

  15. Influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage restorations.

    Bakeman, E M; Rego, N; Chaiyabutr, Y; Kois, J C

    2015-01-01

    This study evaluated the influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage ceramic restorations. Forty extracted molars were allocated into four groups (n=10) to test for two variables: 1) the thickness of ceramic (1 mm or 2 mm) and 2) the ceramic materials (a lithium disilicate glass-ceramic [IPS e.max] or leucite-reinforced glass ceramic [IPS Empress]). All ceramic restorations were luted with resin cement (Variolink II) on the prepared teeth. These luted specimens were loaded to failure in a universal testing machine, in the compression mode, with a crosshead speed of 1.0 mm/min. The data were analyzed using two-way analysis of variance and the Tukey Honestly Significantly Different multiple comparison test (α =0.05). The fracture resistance revealed a significant effect for materials (pceramic was not significant (p=0.074), and the interaction between the thickness of ceramic and the materials was not significant (p=0.406). Mean (standard deviation) fracture resistance values were as follows: a 2-mm thickness of a lithium disilicate bonded to tooth structure (2505 [401] N) revealed a significantly higher fracture resistance than did a 1-mm thickness of leucite-reinforced (1569 [452] N) and a 2-mm thickness of leucite-reinforced ceramic bonded to tooth structure (1716 [436] N) (pceramic at 1-mm thickness (2105 [567] N) and at 2-mm thickness. Using a lithium disilicate glass ceramic for partial coverage restoration significantly improved fracture resistance compared to using a leucite-reinforced glass ceramic. The thickness of ceramic had no significant effect on fracture resistance when the ceramics were bonded to the underlying tooth structure.

  16. Superplasticity in Fine-Grained Ceramics

    1994-01-31

    Stabilized, Tetragonal Zirconia," Acta Metall. Mater., 39(12), (1991), pp. 3227-3236. 10. B. Kellett, P. Carry, and A. Mocellin , "Extrusion of Tet-ZrO2...F. Wakai, S. Sakaguchi, and H. Kato, J. Ceram. Soc. Jap., 94, 72 (1986). 8. B. Kellett, P. Carry, and A. Mocellin , J. Amer. Ceram. Soc., 74, 1922

  17. Shock wave fabricated ceramic-metal nozzles

    Carton, E.P.; Stuivinga, M.E.C.; Keizers, H.L.J.; Verbeek, H.J.; Put, P.J. van der

    1999-01-01

    Shock compaction was used in the fabrication of high temperature ceramic-based materials. The materials' development was geared towards the fabrication of nozzles for rocket engines using solid propellants, for which the following metal-ceramic (cermet) materials were fabricated and tested: B4C-Ti

  18. New ceramic materials; Nuevos materiales ceramicos

    Moreno, R.; Dominguez-Rodriguez, A.

    2010-07-01

    This article is to provide a new ceramic materials in which, with a control of their processing and thus their microstructural properties, you can get ceramic approaching ever closer to a metal, both in its structural behavior at low as at high temperatures. (Author) 30 refs.

  19. Crack growth in thermally sprayed ceramic coatings

    Kroupa, František; Náhlík, Luboš; Knésl, Zdeněk

    2004-01-01

    Roč. 49, č. 2 (2004), s. 149-168 ISSN 0001-7043 R&D Projects: GA ČR GP106/04/P084; GA ČR GA101/03/0331 Institutional research plan: CEZ:AV0Z2043910 Keywords : ceramic coatings, fracture mechanics, crack extension Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  20. Prestresses in bilayered all-ceramic restorations

    Aboushelib, M.N.; Feilzer, A.J.; de Jager, N.; Kleverlaan, C.J.

    2008-01-01

    Introduction: A general trend in all ceramic systems is to use veneering ceramics of slightly lower thermal expansion coefficients compared with that of the framework resulting in a positive mismatch in thermal expansion coefficient (+ΔTEC). The concept behind this TEC mismatch is to generate

  1. Yellow cake to ceramic uranium dioxide

    Zawidzki, T.W.; Itzkovitch, I.J.

    1983-01-01

    This overview article first reviews the processes for converting uranium ore concentrates to ceramic uranium dioxide at the Port Hope Refinery of Eldorado Resources Limited. In addition, some of the problems, solutions, thoughts and research direction with respect to the production and properties of ceramic UO 2 are described

  2. Ceramics for applications in fusion systems

    Clinard, F.W. Jr.

    1979-01-01

    Six critical applications for ceramics in fusion systems are reviewed, and structural and electrical problem areas discussed. Fusion neutron radiation effects in ceramics are considered in relation to fission neutron studies. A number of candidate materials are proposed for further evaluation

  3. Synthesis of crystalline ceramics for actinide immobilisation

    Burakov, B.; Gribova, V.; Kitsay, A.; Ojovan, M.; Hyatt, N.C.; Stennett, M.C.

    2007-01-01

    Methods for the synthesis of ceramic wasteforms for the immobilization of actinides are common to those for non-radioactive ceramics: hot uniaxial pressing (HUP); hot isostatic pressing (HIP); cold pressing followed by sintering; melting (for some specific ceramics, such as garnet/perovskite composites). Synthesis of ceramics doped with radionuclides is characterized with some important considerations: all the radionuclides should be incorporated into crystalline structure of durable host-phases in the form of solid solutions and no separate phases of radionuclides should be present in the matrix of final ceramic wasteform; all procedures of starting precursor preparation and ceramic synthesis should follow safety requirements of nuclear industry. Synthesis methods that avoid the use of very high temperatures and pressures and are easily accomplished within the environment of a glove-box or hot cell are preferable. Knowledge transfer between the V. G. Khlopin Radium Institute (KRI, Russia) and Immobilisation Science Laboratory (ISL, UK) was facilitated in the framework of a joint project supported by UK Royal Society. In order to introduce methods of precursor preparation and ceramic synthesis we selected well-known procedures readily deployable in radiochemical processing plants. We accounted that training should include main types of ceramic wasteforms which are currently discussed for industrial applications. (authors)

  4. Atomic imaging and microanalysis of ceramics

    Thomas, G.; Ramesh, R.

    1988-10-01

    This paper is a short review of electron microscopy techniques, as applied to modern ceramics. Examples: representative of the significance of modern electron microscopy, methods of atomic resolution imaging, diffraction and spectroscopy in the task of characterising, and understanding typical ceramic materials are given. (JL)

  5. Oxygen diffusion in glasses and ceramic materials

    Kolitsch, A.; Richter, E.; Wolf, M.

    1978-10-01

    A survey is given on the published works to study oxygen diffusion in glasses and ceramic materials in the last years. In the first part methods are described for the measurement of oxygen diffusion coefficients and in the second part the published reports on oxygen diffusion in glasses, ceramic and other oxides are discussed. The most important results are summarized in different tables. (author)

  6. Nature of radiation damage in ceramics

    Bunch, J.M.

    1976-01-01

    Efforts to determine the equivalence between different sources of radiation damage in ceramics are reviewed. The ways in which ceramics differ from metals are examined and proposed mechanisms for creation and stabilization of defects in insulators are outlined. Work on radiation damage in crystalline oxides is summarized and suggestions for further research are offered

  7. High performance structural ceramics for nuclear industry

    Pujari, Vimal K.; Faker, Paul

    2006-01-01

    A family of Saint-Gobain structural ceramic materials and products produced by its High performance Refractory Division is described. Over the last fifty years or so, Saint-Gobain has been a leader in developing non oxide ceramic based novel materials, processes and products for application in Nuclear, Chemical, Automotive, Defense and Mining industries

  8. Synthesis and characterization of biomorphic ceramics

    Rambo, Carlos Renato

    2001-01-01

    Biotemplating represents a recently developed technology for manufacturing of biomorphous ceramics from naturally grown plant structures. This approach allows the production of ceramic materials with cellular structure, where the microstructural features of the ceramic product are similar to the native plant. After processing, the biomorphic ceramic exhibits directed pore morphology in the micrometer range. Biomorphic SiC fibers were produced from bamboo by carbothermal reduction of SiO 2 originally present in the bamboo structure. Bamboo pieces were heated up to 1500 deg C in argon to promote the reaction between carbon and silica. Biomorphic alumina, mullite and zirconia ceramics were manufactured via the sol-gel route by repeated infiltration of low viscous oxide precursors (sols) into rattan, pine and bamboo structures. The raw samples were pyrolyzed at 800 deg C in nitrogen for 1h and subsequently annealed at 1550 deg C in air. The microstructure and physical properties of the biomorphic ceramics were characterized by X-ray diffraction (XRD) and high temperature-XRD, scanning electron microscopy (SEM), porosimetry and picnometry. Thermal analysis (TGA/DTA) was performed on the infiltrated samples in order to evaluate the reactions and the total weight loss during the thermal process. The mechanical properties were evaluated by compressive strength tests. In contrast to conventional processed ceramic foam of similar porosity, the microstructure highly porous biomorphic ceramics shows uniaxial pore morphology with anisotropic properties. These properties are favorable for applications in catalyst support, filters or low-density heat insulation structures, or as biomaterials. (author)

  9. FY2015 ceramic fuels development annual highlights

    Mcclellan, Kenneth James [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

    2015-09-22

    Key challenges for the Advanced Fuels Campaign are the development of fuel technologies to enable major increases in fuel performance (safety, reliability, power and burnup) beyond current technologies, and development of characterization methods and predictive fuel performance models to enable more efficient development and licensing of advanced fuels. Ceramic fuel development activities for fiscal year 2015 fell within the areas of 1) National and International Technical Integration, 2) Advanced Accident Tolerant Ceramic Fuel Development, 3) Advanced Techniques and Reference Materials Development, and 4) Fabrication of Enriched Ceramic Fuels. High uranium density fuels were the focus of the ceramic fuels efforts. Accomplishments for FY15 primarily reflect the prioritization of identification and assessment of new ceramic fuels for light water reactors which have enhanced accident tolerance while also maintaining or improving normal operation performance, and exploration of advanced post irradiation examination techniques which will support more efficient testing and qualification of new fuel systems.

  10. Light scattering in glass-ceramics

    Hendy, S.C.

    2002-01-01

    Full text: Glass-ceramic materials with microstructures comprised of dispersed nanocrystallites in a residual glass matrix show promise for many new technological applications. In particular, transparent glass-ceramics offer low thermal expansion and stability, in addition to the prospect of novel non-linear optical properties that can arise from the nanocrystallites. Good transparency requires low optical scattering and low atomic absorption. Light scattering in the glass-ceramic arises primarily from the glass-crystallite interface. The attenuation due to scattering (turbidity) will depend upon the difference in refractive index of the two phases and the size and distribution of nanocrystallites in the glass. Here we consider models of glass-ceramic structure formation and look at scattering in these model structures to increase our understanding of the transparency of glass-ceramics

  11. Polymer and ceramic nanocomposites for aerospace applications

    Rathod, Vivek T.; Kumar, Jayanth S.; Jain, Anjana

    2017-11-01

    This paper reviews the potential of polymer and ceramic matrix composites for aerospace/space vehicle applications. Special, unique and multifunctional properties arising due to the dispersion of nanoparticles in ceramic and metal matrix are briefly discussed followed by a classification of resulting aerospace applications. The paper presents polymer matrix composites comprising majority of aerospace applications in structures, coating, tribology, structural health monitoring, electromagnetic shielding and shape memory applications. The capabilities of the ceramic matrix nanocomposites to providing the electromagnetic shielding for aircrafts and better tribological properties to suit space environments are discussed. Structural health monitoring capability of ceramic matrix nanocomposite is also discussed. The properties of resulting nanocomposite material with its disadvantages like cost and processing difficulties are discussed. The paper concludes after the discussion of the possible future perspectives and challenges in implementation and further development of polymer and ceramic nanocomposite materials.

  12. Ceramic Technology for Advanced Heat Engines Project

    1989-08-01

    The Ceramic Technology for Advanced Heat Engines Project was developed by the Department of Energy's Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Advanced Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DoD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially.

  13. FY2016 Ceramic Fuels Development Annual Highlights

    Mcclellan, Kenneth James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-24

    Key challenges for the Advanced Fuels Campaign are the development of fuel technologies to enable major increases in fuel performance (safety, reliability, power and burnup) beyond current technologies, and development of characterization methods and predictive fuel performance models to enable more efficient development and licensing of advanced fuels. Ceramic fuel development activities for fiscal year 2016 fell within the areas of 1) National and International Technical Integration, 2) Advanced Accident Tolerant Ceramic Fuel Development, 3) Advanced Techniques and Reference Materials Development, and 4) Fabrication of Enriched Ceramic Fuels. High uranium density fuels were the focus of the ceramic fuels efforts. Accomplishments for FY16 primarily reflect the prioritization of identification and assessment of new ceramic fuels for light water reactors which have enhanced accident tolerance while also maintaining or improving normal operation performance, and exploration of advanced post irradiation examination techniques which will support more efficient testing and qualification of new fuel systems.

  14. Fluorescence of ceramic color standards

    Koo, Annette; Clare, John F.; Nield, Kathryn M.; Deadman, Andrew; Usadi, Eric

    2010-01-01

    Fluorescence has been found in color standards available for use in calibration and verification of color measuring instruments. The fluorescence is excited at wavelengths below about 600 nm and emitted above 700 nm, within the response range of silicon photodiodes, but at the edge of the response of most photomultipliers and outside the range commonly scanned in commercial colorimeters. The degree of fluorescence on two of a set of 12 glossy ceramic tiles is enough to introduce significant error when those tiles have been calibrated in one mode of measurement and are used in another. We report the nature of the fluorescence and the implications for color measurement.

  15. Ceramics for Turbine Engine Applications.

    1980-03-01

    permet de travailler en compression. 2 - LES TURBINES CONTRAROTATIVES Connues depuis plus de 50 ans dsns lea turbines A vapeur (A grilles radiales) lea...AD-AO87 594 ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT--ETC F/6 11/2 CERAMICS FOR TURBINE ENGINE APPICATIONS.(U) MAR 8G H M GURTE, J...for Turbine Engine Applications ( X.,, ~LAJ DISTRIBUTION AND AVAILABILITY Ths ai’-t~ ~ru O ACK COVER forp"~ ~So’ 8 6 0 40 NORTH ATLANTIC TREATY

  16. Building ceramic based on sludge

    Szöke, A-M; Muntean, M; Dumitrescu, O; Bartalis, I

    2013-01-01

    Because of the rapid evolution in the last decade of science and engineering materials, development of new advanced materials, particularly in construction, we must find solutions, namely, new performed materials, with functional and aesthetic qualities. In recent years, there have been made alternative attempts to reuse various types of wastes, including the incorporation of products in ceramic clay. This theme concerning the achievement of some durable, economic and ecological materials represents a high-level preoccupation in this domain, the problems related to the ecosystem being permanent issues of the century

  17. Fibrous-Ceramic/Aerogel Composite Insulating Tiles

    White, Susan M.; Rasky, Daniel J.

    2004-01-01

    Fibrous-ceramic/aerogel composite tiles have been invented to afford combinations of thermal-insulation and mechanical properties superior to those attainable by making tiles of fibrous ceramics alone or aerogels alone. These lightweight tiles can be tailored to a variety of applications that range from insulating cryogenic tanks to protecting spacecraft against re-entry heating. The advantages and disadvantages of fibrous ceramics and aerogels can be summarized as follows: Tiles made of ceramic fibers are known for mechanical strength, toughness, and machinability. Fibrous ceramic tiles are highly effective as thermal insulators in a vacuum. However, undesirably, the porosity of these materials makes them permeable by gases, so that in the presence of air or other gases, convection and gas-phase conduction contribute to the effective thermal conductivity of the tiles. Other disadvantages of the porosity and permeability of fibrous ceramic tiles arise because gases (e.g., water vapor or cryogenic gases) can condense in pores. This condensation contributes to weight, and in the case of cryogenic systems, the heat of condensation undesirably adds to the heat flowing to the objects that one seeks to keep cold. Moreover, there is a risk of explosion associated with vaporization of previously condensed gas upon reheating. Aerogels offer low permeability, low density, and low thermal conductivity, but are mechanically fragile. The basic idea of the present invention is to exploit the best features of fibrous ceramic tiles and aerogels. In a composite tile according to the invention, the fibrous ceramic serves as a matrix that mechanically supports the aerogel, while the aerogel serves as a low-conductivity, low-permeability filling that closes what would otherwise be the open pores of the fibrous ceramic. Because the aerogel eliminates or at least suppresses permeation by gas, gas-phase conduction, and convection, the thermal conductivity of such a composite even at

  18. Ceramic Technology for Advanced Heat Engines Project

    1990-08-01

    The Ceramic Technology For Advanced Heat Engines Project was developed by the Department of Energy's Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Advanced Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DOD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. An assessment of needs was completed, and a five year project plan was developed with extensive input from private industry. The objective of the project is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on structural ceramics for advanced gas turbine and diesel engines, ceramic hearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines.

  19. Utilização do resíduo da extração de esmeraldas em uma formulação de massa de revestimento cerâmico Use of the extraction residue of emeralds in a formulation mass of ceramic tiles

    R. F. Cavalcante

    2012-06-01

    volumes of waste generated and emerald are constantly abandoned in the environment, contributing negatively to their preservation. On the other hand the interest in the use of mining waste as an additive in production of ceramic materials has grown among researchers in recent years. The ceramic industry is constantly seeking to expand the market for the sector and trying to improve product quality and increase the variety of applications. The technology of obtaining ceramic coating that uses waste from mining is still a largely unexplored market. Thus, the purpose of this study was to characterize the waste generated from mining emerald as well as to evaluate its potential use as raw material for production melting of ceramic tiles. Ceramic mixtures were prepared from raw materials characterized by X-ray fluorescence and X-ray diffraction. Five compositions were prepared using the waste codes of emeralds from 0%, 10%, 20%, 30% and 40%. Samples were prepared by pressing, sintered at 1000, 1100 and 1200 ºC and characterized to establish their mineralogical composition, water absorption, linear shrinkage and modulus of rupture. The results showed that the residue of emeralds studied can be embedded in the mass of ceramic tiles up to 20% in replacement of feldspar without compromising the end product properties.

  20. Basaltic scorias from Romania - complex building material us for concrete, glazing tiles, ceramic glazes, glass ceramics, mineral wool

    Marica, S.; Cetean, V. [PROCEMA S.A., Bucharest (Romania)

    2002-07-01

    The most spectacular deposit of basaltic scoria from Romania is the Heghes Hill from Racos, locality situated in the central part of country. This deposit emerged as grains of various dimensions, as volcanic ash with specific porosity up to 30% and vacuolar basaltic rocks. All types of basaltic scorias have specific vacuolar appearance, red- brick or blackish - grey coloured, scoria textures and similar chemical composition with others basalts of the world. The physical and mechanical characteristics determined included the scorias in the Heghes Hill in the following categories : light rocks (2,98 g/ dmc), porous(11,04%), similar to expanded slag, slightly absorbing rocks (3,86%), with low compression strengths (1700 daN/cmp). Basaltic scoria from Heghes is a very good row material for the manufacture of concrete, for obtain decorative cutting tiles glazing with ceramic and basaltic glazes (up to 40%) varied the range of colours and for obtaining glass ceramic, mineral wool, crushing sand for road maintenance, heat -insulating bricks and shid -proof material. (orig.)

  1. Development and characterization of ceramic composites alumina-titania based reinforced with lanthanum oxide for fabrication of inert coatings for metallic tanks of the oil industry; Desenvolvimento e caracterizacao de compositos ceramicos baseados em alumina-titania reforcados com oxido de lantanio para fabricacao de revestimentos inertes em tanques metalicos da industria petrolifera

    Bandeira, J.M.; Yadava, Y.P.; Silva, N.D.G.; Ferreira, R.A.S., E-mail: julianamb91@gmail.com, E-mail: yadava@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Centro de Tecnologia e Geociencias. Departamento de Engenharia Mecanica

    2016-07-01

    Crude petroleum is highly corrosive causing superficial degradation in metallic tanks used for storage and transportation of this material, which causes a serious problem in the oil industry. An alternative to solve this problem is to use some kind of coating that is inert to this kind of corrosion. Alumina and titania are interesting materials for several engineering applications because, when compared with other ceramic materials, they present superior mechanical properties, e.g. high mechanical strength, good chemical stability and high fracture toughness combined with good wear resistance and a coefficient of thermal expansion close to the iron's, which makes them fit to use in ceramic hardening process and coating. In this paper, alumina-titania ceramic composites with 5%, 10%, 15% and 20% of titania (TiO2) and reinforced with 2% of lanthanum oxide of were produced by thermo-mechanical processing and sintering techniques at 1350 deg C. In these composites, microstructure and mechanical properties were analyzed using X-ray spectroscopy, optical microscopy, scanning electron microscopy and Vickers hardness in order to evaluate their applicability. X-ray spectroscopy showed the formation of composite without the presence of other phases. Optical microscopy and scanning electron microscopy showed a homogeneous microstructure in terms of particle size and distribution. Vickers hardness test showed a gradual decrease in hardness with the addition of titania. The composite with 5% of titania and 2% of lanthanum oxide is the best choice for structural applications. The composites were submerged in crude petroleum for 30 days to study their stability in such environment. Through the analysis of X-ray spectroscopy, optical microscopy and Vickers hardness before and after the submersion in crude petroleum, it was not observed structural or microstructural degradation nether alterations in mechanical properties. This way, it was concluded that these composites have

  2. A fractographic study of clinically retrieved zirconia–ceramic and metal–ceramic fixed dental prostheses

    Pang, Zhen; Chughtai, Asima; Sailer, Irena; Zhang, Yu

    2015-01-01

    Objectives A recent 3-year randomized controlled trial (RCT) of tooth supported three- to five-unit zirconia–ceramic and metal–ceramic posterior fixed dental prostheses (FDPs) revealed that veneer chipping and fracture in zirconia–ceramic systems occurred more frequently than those in metal–ceramic systems [1]. This study seeks to elucidate the underlying mechanisms responsible for the fracture phenomena observed in this RCT using a descriptive fractographic analysis. Methods Vinyl-polysiloxane impressions of 12 zirconia–ceramic and 6 metal–ceramic FDPs with veneer fractures were taken from the patients at the end of a mean observation of 40.3 ± 2.8 months. Epoxy replicas were produced from these impressions [1]. All replicas were gold coated, and inspected under the optical microscope and scanning electron microscope (SEM) for descriptive fractography. Results Among the 12 zirconia–ceramic FDPs, 2 had small chippings, 9 had large chippings, and 1 exhibited delamination. Out of 6 metal–ceramic FDPs, 5 had small chippings and 1 had large chipping. Descriptive fractographic analysis based on SEM observations revealed that fracture initiated from the wear facet at the occlusal surface in all cases, irrespective of the type of restoration. Significance Zirconia–ceramic and metal–ceramic FDPs all fractured from microcracks that emanated from occlusal wear facets. The relatively low fracture toughness and high residual tensile stress in porcelain veneer of zirconia restorations may contribute to the higher chipping rate and larger chip size in zirconia–ceramic FDPs relative to their metal–ceramic counterparts. The low veneer/core interfacial fracture energy of porcelain-veneered zirconia may result in the occurrence of delamination in zirconia–ceramic FDPs. PMID:26233469

  3. Factors affecting the shear bond strength of metal and ceramic brackets bonded to different ceramic surfaces.

    Abu Alhaija, Elham S J; Abu AlReesh, Issam A; AlWahadni, Ahed M S

    2010-06-01

    The aims of this study were to evaluate the shear bond strength (SBS) of metal and ceramic brackets bonded to two different all-ceramic crowns, IPS Empress 2 and In-Ceram Alumina, to compare the SBS between hydrofluoric acid (HFA), phosphoric acid etched, and sandblasted, non-etched all-ceramic surfaces. Ninety-six all-ceramic crowns were fabricated resembling a maxillary left first premolar. The crowns were divided into eight groups: (1) metal brackets bonded to sandblasted 9.6 per cent HFA-etched IPS Empress 2 crowns; (2) metal brackets bonded to sandblasted 9.6 per cent HFA-etched In-Ceram crowns; (3) ceramic brackets bonded to sandblasted 9.6 per cent HFA-etched IPS Empress 2 crowns; (4) ceramic brackets bonded to sandblasted 9.6 per cent HFA-etched In-Ceram crowns; (5) metal brackets bonded to sandblasted 37 per cent phosphoric acid-etched IPS Empress 2 crowns; (6) metal brackets bonded to sandblasted 37 per cent phosphoric acid-etched In-Ceram crowns; (7) metal brackets bonded to sandblasted, non-etched IPS Empress 2 crowns; and (8) metal brackets bonded to sandblasted, non-etched In-Ceram crowns. Metal and ceramic orthodontic brackets were bonded using a conventional light polymerizing adhesive resin. An Instron universal testing machine was used to determine the SBS at a crosshead speed of 0.1 mm/minute. Comparison between groups was performed using a univariate general linear model and chi-squared tests. The highest mean SBS was found in group 3 (120.15 +/- 45.05 N) and the lowest in group 8 (57.86 +/- 26.20 N). Of all the variables studied, surface treatment was the only factor that significantly affected SBS (P Empress 2 and In-Ceram groups.

  4. Radiopaque strontium fluoroapatite glass-ceramics

    Wolfram eHöland

    2015-10-01

    Full Text Available The controlled precipitation of strontium fluoroapatite crystals, was studied in four base glass compositions derived from the SiO2 – Al2O3 – Y2O3 – SrO – Na2O – K2O/Rb2O/Cs2O – P2O5 – F system. The crystal phase formation of these glasses and the main properties of the glass-ceramics, such as thermal and optical properties and radiopacity were compared with a fifth, a reference glass-ceramic. The reference glass-ceramic was characterized as Ca-fluoroapatite glass-ceramic. The four strontium fluoroapatite glass-ceramics showed the following crystal phases: a Sr5(PO43F – leucite, KAlSi2O6 , b Sr5(PO43F – leucite, KAlSi2O6, and nano-sized NaSrPO4 c Sr5(PO43F – pollucite, CsAlSiO4 , and nano-sized NaSrPO4, d Sr5(PO43F – Rb-leucite, RbAlSi2O6, and nano-sized NaSrPO4.The proof of crystal phase formation was possible by X-ray diffraction (XRD. The microstructures, which were studied using scanning electron microscopy (SEM demonstrated a uniform distribution of the crystals in the glass matrix. The Sr-fluoroapatites were precipitated based on an internal crystallization process, and the crystals demonstrated a needlelike morphology. The study of the crystal growth of needlelike Sr-fluoroapatites gave a clear evidence of an Ostwald ripening mechanism.The formation of leucite, pollucite and Rb-leucite was based on a surface crystallization mechanism. Therefore, a twofold crystallization mechanism was successfully applied to develop these types of glass-ceramics. The main focus of this study was the controlled development of glass-ceramics exhibiting high radiopacity in comparison to the reference glass-ceramic. This goal could be achieved with all four glass-ceramics with the preferred development of the Sr-fluoroapatite – pollucite-type glass-ceramic. In addition to this main development, it was possible to control the thermal properties. Especially the Rb-leucite containing glass-ceramic showed the highest coefficient of thermal

  5. Limpeza da superfície de corte de rebolos por um sistema de ar comprimido na retificação cilíndrica externa de mergulho de materiais cerâmicos refrigerados com a técnica da mínima quantidade de lubrificante (MQL Grinding wheel surface cleaning using a compressed air system, in external plunge grinding of ceramics using the minimum quantity lubricant (MQL technique

    E. C. Bianchi

    2012-06-01

    Full Text Available Nos processos de retificação, a utilização de fluidos de corte é uma maneira de implementar a qualidade final do processo, pois os fluidos têm como finalidade a lubrificação na área de contato entre a peça e ferramenta e a refrigeração das superfícies, assim evitando danificações na superfície da peça. Com isso, a utilização de fluidos de corte tem sido constantemente estudada, visando diminuir a utilização deste, pois a utilização de fluidos de corte tem seus problemas. O custo do produto final aumenta consideravelmente com o uso de fluidos de corte no processo de retificação, além de que os fluidos de corte são substâncias tóxicas e nocivas tanto às pessoas quanto ao meio ambiente. Portanto, indústrias, universidades e centros de pesquisas são levados a pesquisar métodos alternativos menos prejudiciais ao meio ambiente. Dentre as alternativas surge a técnica da mínima quantidade de lubrificante (MQL, que também tem suas desvantagens, como por exemplo, a formação de um borra de óleo na superfície de corte do rebolo, o que gera uma rugosidade maior na peça. Porém, visando minimizar o problema da formação da borra de óleo podem ser usados jatos de ar comprimido incidindo na superfície de corte do rebolo, com o objetivo de limpar a mesma. Este estudo será feito através da análise da avaliação das variáveis de saída do processo de retificação externa, como o comportamento da rugosidade superficial e dos desvios de circularidade. Através dos resultados obtidos pretende-se estudar a técnica do MQL, visando melhorá-la através da limpeza da superfície de corte do rebolo com jatos de ar comprimido.In grinding, the use of cutting fluids aims to improve the final quality of the process, because their purpose is to lubricate the contact area between workpiece and tool and the surface cooling, thus avoiding damages on the machined part. Therefore, this subject has been constantly studied, in order

  6. Glass ceramic seals to inconel

    McCollister, Howard L.; Reed, Scott T.

    1983-11-08

    A glass ceramic composition prepared by subjecting a glass composition comprising, by weight, 65-80% SiO.sub.2, 8-16%, Li.sub.2 O, 2-8% , Al.sub.2 O.sub.3, 1-8% K.sub.2 O, 1-5% P.sub.2 O.sub.5 and 1.5-7% B.sub.2 O.sub.3, to the following processing steps of heating the glass composition to a temperature sufficient to crystallize lithium metasilicate therein, holding the glass composition at a temperature and for a time period sufficient to dissolve the lithium metasilicate therein thereby creating cristobalite nucleii, cooling the glass composition and maintaining the composition at a temperature and for a time period sufficient to recrystallize lithium metasilicate therein, and thermally treating the glass composition at a temperature and for a time period sufficient to cause growth of cristobalite and further crystallization of lithium metasilicate producing a glass ceramic composition having a specific thermal expansion coefficient and products containing said composition.

  7. Method for producing ceramic bodies

    Prunier, A.R. Jr.; Spangenberg, S.F.; Wijeyesekera, S.

    1992-01-01

    This patent describes a method for preparing a superconducting ceramic article. It comprises heating a powdered admixture comprising a source of yttria (Y 2 O 3 ), a source of barium monoxide and a source of cupric oxide to a temperature of from about 800 degrees Centigrade to 900 degrees Centigrade to allow the admixture to be densified under pressure to more than about 65 percent of the admixture's theoretical density but low enough to substantially preclude melting of the admixture; applying to the heated admixture isostatic pressure of between about 80,000 psi (5.5 x 10 2 MPa) and about the fracture stress of the heated admixture, for a period of time of from about 0.1 second to about ten minutes to form a densified article with a density of more than about 65 percent of the admixture's theoretical density; and annealing the densified article in the presence of gaseous oxygen under conditions sufficient to convert the densified article to a superconducting ceramic article having a composition comprising YBa 2 Cu 3 O 7 - x where O < x < 0.6

  8. Ceramics like PZT-PMN

    Droescher, R.E.; Sousa, V.C.; Bergman, C.P.

    2009-01-01

    The goal of this work was to achieve piezoelectric ceramics referring to the system PZT-PMN Pb(Mg 1 / 3 Nb 2 / 3 Zr 0 , 52 Ti 0 , 48 )O 3 . Have been analysed ceramics like 0,65PZT-0,35PMN ((Pb(Mg 0 , 1167 Nb 0 , 2300 Zr 0 , 3380 Ti 0 , 3120 )O 3 ), 0,75PZT-0,25PMN ((Pb(Mg 0 , 083 Nb 0 . 1675 Zr 0 , 3900 Ti 0 , 3600 )O3) and the 0,85PZT-0,15PMN ((Pb(Mg 0,0500 Nb 0 , 1000 Zr 0 , 4420 Ti 0 , 4080 )O 3 ). The influence of the calcination and concentration of PZT on the lattice phases, microstructure and density was evaluated. Then, the method used was the mixed-oxide method, the samples were taken under different temperatures of calcination before the final sinterizing. The DRX and SEM techniques were used to identify the phases formed and analyse the microstructure, respectively. The main result revealed that, the better way is to realize three burns before the final sinterizing at 1200 o C/4 h . Like that, on obtain for sure the average lattice phases, like: perovskite, pyrochlore and PbO and also tend to densify the samples. (author)

  9. Ceramic materials on perovskite-type structure for electronic applications

    Surowiak, Z.

    2003-01-01

    Ceramic materials exhibiting the perovskite-type structure constitute among others, resource base for many fields of widely understood electronics (i.e., piezoelectronics, accustoelectronics, optoelectronics, computer science, tele- and radioelectronics etc.). Most often they are used for fabrication of different type sensors (detectors), transducers, ferroelectric memories, limiters of the electronic current intensity, etc., and hence they are numbered among so-called intelligent materials. Prototype structure of this group of materials is the structure of the mineral called perovskite (CaTiO 3 ). By means of right choice of the chemical composition of ABO 3 and deforming the regular perovskite structure (m3m) more than 5000 different chemical compounds and solid solutions exhibiting the perovskite-type structure have been fabricated. The concept of perovskite functional ceramics among often things ferroelectric ceramics, pyroelectric ceramics, piezoelectric ceramics, electrostrictive ceramics, posistor ceramics, superconductive ceramics and ferromagnetic ceramics. New possibilities of application of the perovskite-type ceramics are opened by nanotechnology. (author)

  10. Randomized, Controlled Clinical Trial of Bilayer Ceramic and Metal-Ceramic Crown Performance

    Esquivel-Upshaw, Josephine; Rose, William; Oliveira, Erica; Yang, Mark; Clark, Arthur E.; Anusavice, Kenneth

    2013-01-01

    Purpose Analyzing the clinical performance of restorative materials is important, as there is an expectation that these materials and procedures will restore teeth and do no harm. The objective of this research study was to characterize the clinical performance of metal-ceramic crowns, core ceramic crowns, and core ceramic/veneer ceramic crowns based on 11 clinical criteria. Materials and Methods An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study. The following three types of full crowns were fabricated: (1) metal-ceramic crown (MC) made from a Pd-Au-Ag-Sn-In alloy (Argedent 62) and a glass-ceramic veneer (IPS d.SIGN veneer); (2) non-veneered (glazed) lithium disilicate glass-ceramic crown (LDC) (IPS e.max Press core and e.max Ceram Glaze); and (3) veneered lithia disilicate glass-ceramic crown (LDC/V) with glass-ceramic veneer (IPS Empress 2 core and IPS Eris). Single-unit crowns were randomly assigned. Patients were recalled for each of 3 years and were evaluated by two calibrated clinicians. Thirty-six crowns were placed in 31 patients. A total of 12 crowns of each of the three crown types were studied. Eleven criteria were evaluated: tissue health, marginal integrity, secondary caries, proximal contact, anatomic contour, occlusion, surface texture, cracks/chips (fractures), color match, tooth sensitivity, and wear (of crowns and opposing enamel). Numerical rankings ranged from 1 to 4, with 4 being excellent, and 1 indicating a need for immediate replacement. Statistical analysis of the numerical rankings was performed using a Fisher’s exact test. Results There was no statistically significant difference between performance of the core ceramic crowns and the two veneered crowns at year 1 and year 2 (p > 0.05). All crowns were rated either as excellent or good for each of the clinical criteria; however, between years 2 and 3, gradual roughening of the occlusal surface occurred in some of the ceramic-ceramic crowns

  11. Ceramic restoration repair: report of two cases

    Luís Henrique Araújo Raposo

    2009-04-01

    Full Text Available The esthetic and functional rehabilitation of patients with multiple missing teeth can be performed with several techniques and materials. Ceramic restorations provide reliable masticatory function and good esthetics. However, fracture can occur in some cases due to their brittle behavior. In some cases, the replacement of an extensive prosthesis is a problem due to the high treatment cost. In this paper, two cases are presented, in which fractures occurred in extensive metal-ceramic fixed partial dentures, and their replacement was not possible. Ceramic repair was chosen and the sequences of treatment with and without presence of the ceramic fragment are also discussed. The cases illustrate that, in some situations, fractured metal-ceramic partial dentures can be successfully repaired when prosthetic replacement is not a choice. Prosthodontists must use alternatives that allow a reliable repair to extensive metal-ceramic fixed partial dentures. Surface preparation of the ceramic with hydrofluoric acid in conjunction with a silane coupling agent is essential for a predictable bonding of composite resin. The repair performed with composite resin is an esthetic and functional alternative when extensive fixed partial dentures cannot be replaced.

  12. High-temperature materials and structural ceramics

    1990-01-01

    This report gives a survey of research work in the area of high-temperature materials and structural ceramics of the KFA (Juelich Nuclear Research Center). The following topics are treated: (1) For energy facilities: ODS materials for gas turbine blades and heat exchangers; assessment of the remaining life of main steam pipes, material characterization and material stress limits for First-Wall components; metallic and graphitic materials for high-temperature reactors. (2) For process engineering plants: composites for reformer tubes and cracking tubes; ceramic/ceramic joints and metal/ceramic and metal/metal joints; Composites and alloys for rolling bearing and sliding systems up to application temperatures of 1000deg C; high-temperature corrosion of metal and ceramic material; porous ceramic high-temperature filters and moulding coat-mix techniques; electrically conducting ceramic material (superconductors, fuel cells, solid electrolytes); high-temperature light sources (high-temperature chemistry); oil vapor engines with caramic components; ODS materials for components in diesel engines and vehicle gas turbines. (MM) [de

  13. Microcracking in ceramics and acoustic emission

    Subbarao, E.C.

    1991-01-01

    One of the limitations in the use of ceramics in critical applications is due to the presence of microcracks, which may arise from differential thermal expansion and phase changes, among others. Acoustic emission signals occur when there are abrupt microdeformations in a material and thus offer a convenient means of non-destructive detection of microcracking. Examples of a study of acoustic emission from microcracking due to anisotropic thermal expansion in low thermal expansion single phase ceramics such as niobia and sodium zirconium phosphate ceramics and due to phase changes in zirconia and superconducting YBa 2 Cu 3 Osub(7-x) ceramics are presented, together with the case of lead titanate ceramics, which exhibits both a phase change (paraelectric to ferroelectric) and an anisotropic thermal expansion. The role of grain size on the extent of microcracking is illustrated in the case of niobia ceramics. Some indirect evidence of healing of microcracks on heating niobia and lead titanate ceramics is presented from the acoustic emission results. (author). 69 refs., 9 figs

  14. Characterization and evaluation of ceramic properties of clay used in structural ceramics

    Reis, A.S.; Oliveira, J.N.; Della-Sagrillo, V.P.; Valenzuela-Diaz, F.R.

    2014-01-01

    The clay used in the manufacture of structural ceramic products must meet quality requirements that are influenced by their chemical, physical, mineralogical and microstructural characteristics, which control the ceramic properties of the final products. This paper aims to characterize the clay used in the manufacture of ceramic roof tiles and bricks. The clay was characterized through XRF, XRD, thermogravimetry and differential thermal analysis, Atterberg limits and particle size distribution. Specimens were shaped, dried at 110°C, and burned at 900 deg C in an industrial kiln. After that, they were submitted to tests of water absorption, apparent porosity, bulk density and flexural strength. The results show that the chemical composition of clay has significant amount of silica and alumina and adequate levels of kaolinite for use in structural ceramic. The ceramic properties evaluated in the specimens partially meet the requirements of the Brazilian standard-clays for structural ceramics. (author)

  15. Characterization of ceramics used in mass ceramic industry Goianinha/RN

    Sales Junior, J.C.C.; Nascimento, R.M. do; Andrade, J.C.S.; Saldanha, K.M.; Dutra, R.P.S.

    2011-01-01

    The preparation of the the ceramic mass is one of the most important steps in the manufacture of ceramic products, since the characteristics of the raw materials used, and the proportions that they are added, directly influence the final properties of ceramic products and the operational conditions of processing. The objective of this paper is to present the results of the characterization of a ceramic mass used in the manufacture of sealing blocks by a red ceramic industry of the city of Goianinha / RN. We analyzed the chemical and mineralogical composition; thermogravimetric and differential thermal analysis; granulometric analysis; evaluation of plasticity; and determining the technological properties of specimens used in test firing at 700, 900 and 1100 ° C. The results show that the ceramic body studied has characteristics that allow use in the manufacture of sealing blocks when burned at a temperature of 900 ° C. (author)

  16. Tribology of ceramics: Report of the Committee on Tribology of Ceramics

    1988-01-01

    The current state of knowledge of ceramic surface structures, composition, and reactivity is reviewed. The tribological requirements of advanced mechanical systems now being deployed (in particular, heat engines) exceed the capabilities of traditional metallic-based materials because of the high temperatures encountered. Advanced ceramic materials for such applications are receiving intense scrutiny, but there is a lack of understanding of the properties and behavior of ceramic surfaces and the influence of processing on the properties of ceramics is described. The adequacy of models, ranging form atomic to macro, to describe and to predict ceramic friction and wear are discussed, as well as what is known about lubrication at elevated temperatures. From this analysis, recommendations are made for coordination, research, and development that will lead to better performance of ceramic materials in tribological systems.

  17. Preliminary analysis of the regolithic clay covers from the region of Alfenas, Minas Gerais, Brazil, aiming to evaluate its use in the traditional ceramic industry; Analise preliminar das coberturas regoliticas argilosas da regiao de Alfenas, Minas Gerais, Brasil, visando sua utilizacao na industria de ceramica vermelha

    Gaspar, Junior, L A; Varajao, A F.D.C. [Universidade Federal de Ouro Preto (UFOP), MG (Brazil). Escola de Minas. Dept. de Geologia; Moreno, M M.T. [Universidade Estadual Paulista (UNESP), Rio Claro, SP (Brazil). Dept. de Petrologia e Metalogenia

    2009-07-01

    The region of Alfenas, in the state of Minas Gerais, Brazil, is predominantly constituted of Pre-Cambrian rocks with well developed alteration profiles in association with colluvial and alluvial sediments. No study to date has examined in detail its potential use in the ceramic industry. The scarce knowledge of its mineralogical and technological properties limits its value and consequently its industrial use. Until now, these clay materials have been used in a rudimental manner, in small scale in the fabrication of red tiles. The present study aimed at analyzing these clays mineralogically (X-ray diffraction), chemically (major and minor elements by X-ray fluorescence and organic carbon analysis) and technologically (pressing granulometric distribution; mechanical resistance; water absorption, apparent porosity; linear firing shrinkage; color of firing and others) in order to better understand the raw material and develop adequate technological applications. The best results of ceramic properties were the samples with higher organic content (more plastic clays) and higher values of Al{sub 2}O{sub 3} (kaolinite and gibbsite) and Fe{sub 2}O{sub 3} as well lower SiO{sub 2} content and finer grain size which contribute to a better sintering. (author)

  18. Flight-vehicle materials, structures, and dynamics - Assessment and future directions. Vol. 3 - Ceramics and ceramic-matrix composites

    Levine, Stanley R. (Editor)

    1992-01-01

    The present volume discusses ceramics and ceramic-matrix composites in prospective aerospace systems, monolithic ceramics, transformation-toughened and whisker-reinforced ceramic composites, glass-ceramic matrix composites, reaction-bonded Si3N4 and SiC composites, and chemical vapor-infiltrated composites. Also discussed are the sol-gel-processing of ceramic composites, the fabrication and properties of fiber-reinforced ceramic composites with directed metal oxidation, the fracture behavior of ceramic-matrix composites (CMCs), the fatigue of fiber-reinforced CMCs, creep and rupture of CMCs, structural design methodologies for ceramic-based materials systems, the joining of ceramics and CMCs, and carbon-carbon composites.

  19. High temperature alloys and ceramic heat exchanger

    Okamoto, Masaharu

    1984-04-01

    From the standpoint of energy saving, the future operating temperatures of process heat and gas turbine plants will become higher. For this purpose, ceramics is the most promissing candidate material in strength for application to high-temperature heat exchangers. This report deals with a servey of characteristics of several high-temperature metallic materials and ceramics as temperature-resistant materials; including a servey of the state-of-the-art of ceramic heat exchanger technologies developed outside of Japan, and a study of their application to the intermediate heat exchanger of VHTR (a very-high-temperature gas-cooled reactor). (author)

  20. Solidification of HLLW into sintered ceramics

    O-Oka, K.; Ohta, T.; Masuda, S.; Tsunoda, N.

    1979-01-01

    Simulated HLLW from the PNC reprocessing plant at Tokai was solidified into sintered ceramics by normal sintering or hot-pressing with addition of some oxides. Among various ceramic products obtained so far, the most preferable was nepheline-type sintered solids formed with addition of SiO 2 and Al 2 O 3 to the simulated waste calcine. The solid shows advantageous properties in leach rate and mechanical strength, which suggest that the ceramic solids were prepared with additions of ZrO 2 or MnO 2 , and some of them showed good characteristics

  1. High-performance ceramics. Fabrication, structure, properties

    Petzow, G.; Tobolski, J.; Telle, R.

    1996-01-01

    The program ''Ceramic High-performance Materials'' pursued the objective to understand the chaining of cause and effect in the development of high-performance ceramics. This chain of problems begins with the chemical reactions for the production of powders, comprises the characterization, processing, shaping and compacting of powders, structural optimization, heat treatment, production and finishing, and leads to issues of materials testing and of a design appropriate to the material. The program ''Ceramic High-performance Materials'' has resulted in contributions to the understanding of fundamental interrelationships in terms of materials science, which are summarized in the present volume - broken down into eight special aspects. (orig./RHM)

  2. Hybrid Ceramic Matrix Fibrous Composites: an Overview

    Naslain, R.

    2011-10-01

    Ceramic-Matrix Composites (CMCs) consist of a ceramic fiber architecture in a ceramic matrix, bonded together through a thin interphase. The present contribution is limited to non-oxide CMCs. Their constituents being oxidation-prone, they are protected by external coatings. We state here that CMCs display a hybrid feature, when at least one of their components is not homogeneous from a chemical or microstructural standpoint. Hybrid fiber architectures are used to tailor the mechanical or thermal CMC-properties whereas hybrid interphases, matrices and coatings to improve CMC resistance to aggressive environments.

  3. Properties of textile grade ceramic fibers

    Pudnos, E.

    1992-01-01

    The availability of textile grade ceramic fibers has sparked great interest for applications in composite reinforcement and high temperature insulation. This paper summarizes the properties of various small diameter textile grade ceramic fibers currently available. Room temperature mechanical and electrical properties of the fibers are discussed for three cases: ambient conditions, after heat aging in argon, and after heat aging in wet air. Dow Corning (R) HPZ Ceramic Fiber, a silicon nitride type fiber, is shown to have improved retention of mechanical and electrical properties above 1200 C

  4. Hybrid Ceramic Matrix Fibrous Composites: an Overview

    Naslain, R

    2011-01-01

    Ceramic-Matrix Composites (CMCs) consist of a ceramic fiber architecture in a ceramic matrix, bonded together through a thin interphase. The present contribution is limited to non-oxide CMCs. Their constituents being oxidation-prone, they are protected by external coatings. We state here that CMCs display a hybrid feature, when at least one of their components is not homogeneous from a chemical or microstructural standpoint. Hybrid fiber architectures are used to tailor the mechanical or thermal CMC-properties whereas hybrid interphases, matrices and coatings to improve CMC resistance to aggressive environments.

  5. Clay Ceramic Filter for Water Treatment

    Zereffa Enyew Amare

    2017-05-01

    Full Text Available Ceramic water filters were prepared from different proportions of kaolin and soft wood and sintered at 900 °C, 950 °C, and 1000 °C. The flow rate, conductivity, pH of filtered water and removal efficiency (microbial, water hardness agent’s, nitrite and turbidity were analysed. The ceramic filter with 15 % saw dust, 80 % clay and 5 % grog that was fired at temperature of 950 °C or 1000 °C showed the best removal efficiency. Statistical ANOVA tests showed a significant difference between ceramic filters with various compositions in their removal efficiencies.

  6. Porous ceramic scaffolds with complex architectures

    Munch, E.; Franco, J.; Deville, S.; Hunger, P.; Saiz, E.; Tomsia, A. P.

    2008-06-01

    This work compares two novel techniques for the fabrication of ceramic scaffolds for bone tissue engineering with complex porosity: robocasting and freeze casting. Both techniques are based on the preparation of concentrated ceramic suspensions with suitable properties for the process. In robocasting, the computer-guided deposition of the suspensions is used to build porous materials with designed three dimensional geometries and microstructures. Freeze casting uses ice crystals as a template to form porous lamellar ceramic materials. Preliminary results on the compressive strengths of the materials are also reported.

  7. Ceramic sealants prepared by polymer pyrolysis

    Hong, Sung Jin; Kim, Deug Joong; Yoo, Young Sung

    2011-02-01

    The formation and properties of ceramic seals for SOFC applications prepared by polymer pyrolysis are investigated. A mixture with polymethylsiloxane and fillers are pyrolyzed in a N2 atmosphere. The coefficient of thermal expansion of the ceramic composites was controlled by fillers with a high coefficient of thermal expansion such as AlCo. The morphology of the ceramic composites derived from the mixture with polymethylsiloxane and fillers is composed of fillers embedded in a Si-O-C glass matrix. The thermal expansion behavior and sealing characteristics are measured and discussed

  8. Multiscale Modeling of Ceramic Matrix Composites

    Bednarcyk, Brett A.; Mital, Subodh K.; Pineda, Evan J.; Arnold, Steven M.

    2015-01-01

    Results of multiscale modeling simulations of the nonlinear response of SiC/SiC ceramic matrix composites are reported, wherein the microstructure of the ceramic matrix is captured. This micro scale architecture, which contains free Si material as well as the SiC ceramic, is responsible for residual stresses that play an important role in the subsequent thermo-mechanical behavior of the SiC/SiC composite. Using the novel Multiscale Generalized Method of Cells recursive micromechanics theory, the microstructure of the matrix, as well as the microstructure of the composite (fiber and matrix) can be captured.

  9. Cerâmicas avançadas no processo de retificação cilíndrica externa de mergulho com rebolos diamantados com a técnica da mímima quantidade de lubrificação e refrigeração otimizada Advanced ceramics in the external cylindrical plunge grinding using the technique of minimum quantity of lubrication and the technique of optimized refrigeration with diamond wheels

    M. H. Oikawa

    2011-09-01

    Full Text Available Os materiais cerâmicos têm muitas vantagens em relação a outros materiais, entre elas, três principais: capacidade de operação em altas temperaturas, alta dureza e alta resistência ao desgaste. Por essa razão, são aptos a serem usados em situações que exigem pouco desgaste, tanto em temperatura ambiente quanto em temperaturas elevadas. Estas propriedades fizeram as cerâmicas avançadas terem uma importante parte na utilização em aplicações na indústria nas últimas décadas. Porém, o custo agregado ao acabamento da peça ainda é muito alto. Esse acabamento geralmente é feito pelo processo de retificação, único processo economicamente viável que produz superfícies de elevada qualidade e precisão geométrica. As empresas desse modo vêm buscando a otimização no processo de retificação de cerâmicas, explorando outras técnicas de lubrificação. Assim, este projeto pretendeu explorar a otimização do método de lubrificação na retificação cilíndrica externa de mergulho com o método da mínima quantidade de lubrificação (MQL e refrigeração otimizada. Foram utilizadas três métodos de refrigeração, o convencional o MQL e a refrigeração otimizada, com três avanços de corte para cada caso. Foram analisadas como variáveis de saída a relação G, rugosidade e circularidade. Dos resultados obtidos, pode-se concluir que a refrigeração otimizada é a que apresenta os melhores resultados, sendo esta uma alternativa viável de melhora do processo. O MQL apresentou resultados insatisfatórios em comparação aos outros dois métodos, porém, ainda aceitáveis em alguns processos de retificação. Considerando a dificuldade e altos custos de descarte do fluido de corte devido às rígidas leis ambientais, o MQL vem como uma forte tendência neste tipo de processo.Ceramic materials have many advantages over other materials, including three main: capability of operating at high temperatures, high hardness and

  10. Scale up issues involved with the ceramic waste form: ceramic-container interactions and ceramic cracking quantification

    Bateman, K. J.; DiSanto, T.; Goff, K. M.; Johnson, S. G.; O'Holleran, T.; Riley, W. P. Jr.

    1999-01-01

    Argonne National Laboratory is developing a process for the conditioning of spent nuclear fuel to prepare the material for final disposal. Two waste streams will result from the treatment process, a stainless steel based form and a ceramic based form. The ceramic waste form will be enclosed in a stainless steel container. In order to assess the performance of the ceramic waste form in a repository two factors must be examined, the surface area increases caused by waste form cracking and any ceramic/canister interactions that may release toxic material. The results indicate that the surface area increases are less than the High Level Waste glass and any toxic releases are below regulatory limits

  11. Alkaline resistant ceramics; Alkalimotstaandskraftiga keramer

    Westberg, Stig-Bjoern [Vattenfall Utveckling AB, Aelvkarleby (Sweden)

    2001-02-01

    Despite durability in several environments, ceramics and refractories can not endure alkaline environments at high temperature. An example of such an environment is when burning biofuel in modern heat and power plants in which the demand for increasing efficiency results in higher combustion temperatures and content of alkaline substances in the flue gas. Some experiences of these environments has been gained from such vastly different equipment as regenerator chambers in the glass industry and MHD-generators. The grains of a ceramic material are usually bonded together by a glassy phase which despite it frequently being a minor constituent render the materials properties and limits its use at elevated temperature. The damage is usually caused by alkaline containing low-melting phases and the decrease of the viscosity of the bonding glass phase which is caused by the alkaline. The surfaces which are exposed to the flue gas in a modern power plant are not only exposed to the high temperature but also a corroding and eroding, particle containing, gas flow of high velocity. The use of conventional refractory products is limited to 1300-1350 deg C. Higher strength and fracture toughness as well as durability against gases, slag and melts at temperatures exceeding 1700 deg C are expected of the materials of the future. Continuous transport of corrosive compounds to the surface and corrosion products from the surface as well as a suitable environment for the corrosion to occur in are prerequisites for extensive corrosion to come about. The highest corrosion rate is therefore found in a temperature interval between the dew point and the melting point of the alkaline-constituent containing compound. It is therefore important that the corrosion resistance is sufficient in the environment in which alkaline containing melts or slag may appear. In environments such as these, even under normal circumstances durable ceramics, such as alumina and silicon carbide, are attacked

  12. Study of the behavior of the consistency rates of a clay with the incorporation of waste of burned ceramic blocks

    Oliveira, Orley Magalhaes de; Crivelari, Rubem Mateus; Munhoz Junior, Antonio Hortencio; Silva-Valenzuela, Maria das Gracas da; Valenzuela-Diaz, Francisco Rolando

    2016-01-01

    One of the important parts in the process of manufacturing a structural ceramic product is its conformation. The clay which is the basis for these products need to have an appropriate plasticity. In Ceramics Industries that produce ceramic blocks and tiles plasticity clay and a key property for this production. This Industries are a lot of pieces that do not pass the quality control for not having a uniform visual appearance or have small cracks, these lots are usually discarded, which leads to material waste and produces a lot of waste. The objective of this work is the study of the behavior of consistency indexes, plastic limit (LP); the liquid limit (LL) and plasticity index (PI) of a clay from Vitoria da Conquista, Bahia, with the addition of several waste percentages of burnt and ground ceramic blocks. Our results demonstrate that the addition of the reject only affect the plasticity of clay from an increase of over 100%, which makes possible its incorporation in ceramic paste. (author)

  13. Archaeometric study of Amazon ceramic

    Sabino, Claudia de Vilhena Schayer; Amaral, Angela Maria; Poirior, Andre Pierre Prous

    2002-01-01

    There is no evidence of urban civilization in Brazilian prehistory; most inhabitants lived in tribal organization, probably with regional economic integration among several independent tribes. There are few evidences of seasonal migrations between the coast and the inland of southern Brazil. Some specialized horticulturists competed among themselves but other groups lived more isolatedly and probably peacefully, in the upper interfluvial regions. The chiefdom system is supposed to have existed only along the Amazon River. In this region, some pottery makers may have been specialized craftsmen and finest ceramics, that should have been exported from one village/region to another, can be found. In this study we tested some limited possibilities in three different cultural and regional contexts to see if application of analytic analysis in economically and politically 'simple' societies should give any results. (author)

  14. Mechanical behaviour of structural ceramics

    Bueno, S.

    2007-06-01

    Full Text Available The use of ceramic materials in structural applications is limited by the lack of reliability associated with brittle fracture behaviour. In order to extend the structural use of ceramics, the design of microstructures which exhibit flaw tolerance due to toughening mechanisms which produce an increase in crack growth resistance during crack propagation has been proposed. This work is a review of the mechanical behaviour of structural ceramic materials and its characterisation. Firstly, the basic brittle fracture parameters and the statistical criteria to determine the probability of exceeding the safety factors demanded for a particular application are analysed. Then, the toughening mechanisms which can be developed in the materials through microstructural design as well as the mechanical characterisation of toughened ceramics are discussed. The experimental values of linear elastic fracture toughness parameters (critical stress intensity factor, KIC, and critical energy release rate, GIC are not intrinsic properties for toughened materials and depend on crack length and the loading system. In this work, the different mechanical parameters proposed to characterise such materials are reviewed. The following fracture parameters are analysed: work of fracture (γWOF, critical J-integral value (JIC and R-curve. For the determination, stable fracture tests are proposed in order to ensure that the energy provided during the test is no more than the necessary one for crack propagation.

    El uso de los materiales cerámicos en aplicaciones estructurales está limitado por la falta de fiabilidad asociada a su comportamiento frágil durante la fractura. Para extender su aplicación se ha propuesto el diseño de microestructuras que presenten tolerancia a los defectos debido a la actuación de mecanismos de refuerzo. Este trabajo es una puesta al día sobre el estudio del comportamiento mecánico de los materiales cerámicos estructurales y su

  15. Manufacturing of planar ceramic interconnects

    Armstrong, B.L.; Coffey, G.W.; Meinhardt, K.D.; Armstrong, T.R. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-12-31

    The fabrication of ceramic interconnects for solid oxide fuel cells (SOFC) and separator plates for electrochemical separation devices has been a perennial challenge facing developers. Electrochemical vapor deposition (EVD), plasma spraying, pressing, tape casting and tape calendering are processes that are typically utilized to fabricate separator plates or interconnects for the various SOFC designs and electrochemical separation devices. For sake of brevity and the selection of a planar fuel cell or gas separation device design, pressing will be the only fabrication technique discussed here. This paper reports on the effect of the characteristics of two doped lanthanum manganite powders used in the initial studies as a planar porous separator for a fuel cell cathode and as a dense interconnect for an oxygen generator.

  16. Surface characterization of ceramic materials

    Somorjai, G.A.; Salmeron, M.

    1976-01-01

    In recent years several techniques have become available to characterize the structure and chemical composition of surfaces of ceramic materials. These techniques utilize electron scattering and scattering of ions from surfaces. Low-energy electron diffraction is used to determine the surface structure, Auger electron spectroscopy and other techniques of electron spectroscopy (ultraviolet and photoelectron spectroscopies) are employed to determine the composition of the surface. In addition the oxidation state of surface atoms may be determined using these techniques. Ion scattering mass spectrometry and secondary ion mass spectrometry are also useful in characterizing surfaces and their reactions. These techniques, their applications and the results of recent studies are discussed. 12 figures, 52 references, 2 tables

  17. Evaluation of the fuel rod integrity in PWR reactors from the spectrometric analysis of the primary coolant; Avaliacao da integridade de varetas combustiveis em reatores PWR a partir da analise espectrometrica da agua do primario

    Monteiro, Iara Arraes

    1999-02-15

    The main objective of this thesis is to provide a better comprehension of the phenomena involved in the transport of fission products, from the fuel rod to the coolant of a PWR reactor. To achieve this purpose, several steps were followed. Firstly, it was presented a description of the fuel elements and the main mechanisms of fuel rod failure, indicating the most important nuclides and their transport mechanisms. Secondly, taking both the kinetic and diffusion models for the transport of fission products as a basis, a simple analytical and semi-empirical model was developed. This model was also based on theoretical considerations and measurements of coolant's activity, according to internationally adopted methodologies. Several factors are considered in the modelling procedures: intrinsic factors to the reactor itself, factors which depend on the reactor's operational mode, isotope characteristic factors, and factors which depend on the type of rod failure. The model was applied for different reactor's operational parameters in the presence of failed rods. The main conclusions drawn from the analysis of the model's output are relative to the variation on the coolant's water activity with the fuel burnup, the linear operation power and the primary purification rate and to the different behaviour of iodine and noble gases. The model was saturated from a certain failure size and showed to be unable to distinguish between a single big fail and many small ones. (author)

  18. Evaluation of the contribution of contamination of radiotherapy room surfaces in the measure of exposure rate of radioiodine therapy patients; Avaliacao da contribuicao da contaminacao de superficies do quarto terapeutico na medida da taxa de exposicao de pacientes de radioiodoterapia

    Campos, Rafael Ferreira

    2015-07-01

    The contamination of radiotherapy room surfaces is significant and the measures of patient exposure rate are held on the fourth dependencies, relevant questions are raised: the background radiation of the room stay high due to surface contamination, may interfere with the rate of patient exposure at the time of its release? The monitoring site is important to determine whether the patient will be released? The value of the deal activity and the clinical condition of the patient may increase the contamination, influencing the monitoring results? This paper aims to conduct a quantitative analysis of surface contamination of the contribution of therapeutic room at the time is monitored exposure rate from inpatient. Measurements were made regarding the hospitalization of 32 patients with different doses administered activity, age and of both genders. The measurements were performed in the therapeutic rooms at the hospital Brotherhood Santa Casa de Misericordia de Sao Paulo. Exposure rate measurements were performed at the center of the room at 1 meter of the patient on the day of its release. After his release and prior to decontamination, measurements were performed at predetermined landmarks within the therapeutic room. The results revealed that on average background radiation, high due to surface contamination contributes only 2% of the patient dose rate. It can be considered that even with influence of contamination of surfaces, this is insignificant to determine if the patient may or may not be released. This study suggests that the site in which monitoring occurs exposure rate of the patient should not be decisive for liberation thereof. (author)

  19. CERAMIC WASTE FORM DATA PACKAGE

    Amoroso, J.; Marra, J.

    2014-06-13

    The purpose of this data package is to provide information about simulated crystalline waste forms that can be used to select an appropriate composition for a Cold Crucible Induction Melter (CCIM) proof of principle demonstration. Melt processing, viscosity, electrical conductivity, and thermal analysis information was collected to assess the ability of two potential candidate ceramic compositions to be processed in the Idaho National Laboratory (INL) CCIM and to guide processing parameters for the CCIM operation. Given uncertainties in the CCIM capabilities to reach certain temperatures throughout the system, one waste form designated 'Fe-MP' was designed towards enabling processing and another, designated 'CAF-5%TM-MP' was designed towards optimized microstructure. Melt processing studies confirmed both compositions could be poured from a crucible at 1600{degrees}C although the CAF-5%TM-MP composition froze before pouring was complete due to rapid crystallization (upon cooling). X-ray diffraction measurements confirmed the crystalline nature and phase assemblages of the compositions. The kinetics of melting and crystallization appeared to vary significantly between the compositions. Impedance spectroscopy results indicated the electrical conductivity is acceptable with respect to processing in the CCIM. The success of processing either ceramic composition will depend on the thermal profiles throughout the CCIM. In particular, the working temperature of the pour spout relative to the bulk melter which can approach 1700{degrees}C. The Fe-MP composition is recommended to demonstrate proof of principle for crystalline simulated waste forms considering the current configuration of INL's CCIM. If proposed modifications to the CCIM can maintain a nominal temperature of 1600{degrees}C throughout the melter, drain, and pour spout, then the CAF-5%TM-MP composition should be considered for a proof of principle demonstration.

  20. Salt splitting using ceramic membranes

    Kurath, D.E. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-10-01

    Many radioactive aqueous wastes in the DOE complex have high concentrations of sodium that can negatively affect waste treatment and disposal operations. Sodium can decrease the durability of waste forms such as glass and is the primary contributor to large disposal volumes. Waste treatment processes such as cesium ion exchange, sludge washing, and calcination are made less efficient and more expensive because of the high sodium concentrations. Pacific Northwest National Laboratory (PNNL) and Ceramatec Inc. (Salt Lake City UT) are developing an electrochemical salt splitting process based on inorganic ceramic sodium (Na), super-ionic conductor (NaSICON) membranes that shows promise for mitigating the impact of sodium. In this process, the waste is added to the anode compartment, and an electrical potential is applied to the cell. This drives sodium ions through the membrane, but the membrane rejects most other cations (e.g., Sr{sup +2}, Cs{sup +}). The charge balance in the anode compartment is maintained by generating H{sup +} from the electrolysis of water. The charge balance in the cathode is maintained by generating OH{sup {minus}}, either from the electrolysis of water or from oxygen and water using an oxygen cathode. The normal gaseous products of the electrolysis of water are oxygen at the anode and hydrogen at the cathode. Potentially flammable gas mixtures can be prevented by providing adequate volumes of a sweep gas, using an alternative reductant or destruction of the hydrogen as it is generated. As H{sup +} is generated in the anode compartment, the pH drops. The process may be operated with either an alkaline (pH>12) or an acidic anolyte (pH <1). The benefits of salt splitting using ceramic membranes are (1) waste volume reduction and reduced chemical procurement costs by recycling of NaOH; and (2) direct reduction of sodium in process streams, which enhances subsequent operations such as cesium ion exchange, calcination, and vitrification.

  1. Polymer-Derived Ceramic Fibers

    Ichikawa, Hiroshi

    2016-07-01

    SiC-based ceramic fibers are derived from polycarbosilane or polymetallocarbosilane precursors and are classified into three groups according to their chemical composition, oxygen content, and C/Si atomic ratio. The first-generation fibers are Si-C-O (Nicalon) fibers and Si-Ti-C-O (Tyranno Lox M) fibers. Both fibers contain more than 10-wt% oxygen owing to oxidation during curing and lead to degradation in strength at temperatures exceeding 1,300°C. The maximum use temperature is 1,100°C. The second-generation fibers are SiC (Hi-Nicalon) fibers and Si-Zr-C-O (Tyranno ZMI) fibers. The oxygen content of these fibers is reduced to less than 1 wt% by electron beam irradiation curing in He. The thermal stability of these fibers is improved (they are stable up to 1,500°C), but their creep resistance is limited to a maximum of 1,150°C because their C/Si atomic ratio results in excess carbon. The third-generation fibers are stoichiometric SiC fibers, i.e., Hi-Nicalon Type S (hereafter Type S), Tyranno SA, and Sylramic™ fibers. They exhibit improved thermal stability and creep resistance up to 1,400°C. Stoichiometric SiC fibers meet many of the requirements for the use of ceramic matrix composites for high-temperature structural application. SiBN3C fibers derived from polyborosilazane also show promise for structural applications, remain in the amorphous state up to 1,800°C, and have good high-temperature creep resistance.

  2. Compact Ceramic Microchannel Heat Exchangers

    Lewinsohn, Charles [Ceramatec, Inc., Salt Lake City, UT (United States)

    2016-10-31

    The objective of the proposed work was to demonstrate the feasibility of a step change in power plant efficiency at a commercially viable cost, by obtaining performance data for prototype, compact, ceramic microchannel heat exchangers. By performing the tasks described in the initial proposal, all of the milestones were met. The work performed will advance the technology from Technology Readiness Level 3 (TRL 3) to Technology Readiness Level 4 (TRL 4) and validate the potential of using these heat exchangers for enabling high efficiency solid oxide fuel cell (SOFC) or high-temperature turbine-based power plants. The attached report will describe how this objective was met. In collaboration with The Colorado School of Mines (CSM), specifications were developed for a high temperature heat exchanger for three commercial microturbines. Microturbines were selected because they are a more mature commercial technology than SOFC, they are a low-volume and high-value target for market entry of high-temperature heat exchangers, and they are essentially scaled-down versions of turbines used in utility-scale power plants. Using these specifications, microchannel dimensions were selected to meet the performance requirements. Ceramic plates were fabricated with microchannels of these dimensions. The plates were tested at room temperature and elevated temperature. Plates were joined together to make modular, heat exchanger stacks that were tested at a variety of temperatures and flow rates. Although gas flow rates equivalent to those in microturbines could not be achieved in the laboratory environment, the results showed expected efficiencies, robust operation under significant temperature gradients at high temperature, and the ability to cycle the stacks. Details of the methods and results are presented in this final report.

  3. Wear mechanisms in ceramic hip implants.

    Slonaker, Matthew; Goswami, Tarun

    2004-01-01

    The wear in hip implants is one of the main causes for premature hip replacements. The wear affects the potential life of the prosthesis and subsequent removals of in vivo implants. Therefore, the objective of this article is to review various joints that show lower wear rates and consequently higher life. Ceramics are used in hip implants and have been found to produce lower wear rates. This article discusses the advantages and disadvantages of ceramics compared to other implant materials. Different types of ceramics that are being used are reviewed in terms of the wear characteristics, debris released, and their size together with other biological factors. In general, the wear rates in ceramics were lower than that of metal-on-metal and metal-on-polyethylene combinations.

  4. Screening and classification of ceramic powders

    Miwa, S.

    1983-01-01

    A summary is given of the classification technology of ceramic powders. Advantages and disadvantages of the wet and dry screening and classification methods are discussed. Improvements of wind force screening devices are described.

  5. High Temperature Characterization of Ceramic Pressure Sensors

    Fonseca, Michael A; English, Jennifer M; Von Arx, Martin; Allen, Mark G

    2001-01-01

    This work reports functional wireless ceramic micromachined pressure sensors operating at 450 C, with demonstrated materials and readout capability indicating potential extension to temperatures in excess of 600 C...

  6. Mixed-mode fracture of ceramics

    Petrovic, J.J.

    1985-01-01

    The mixed-mode fracture behavior of ceramic materials is of importance for monolithic ceramics in order to predict the onset of fracture under generalized loading conditions and for ceramic composites to describe crack deflection toughening mechanisms. Experimental data on surface flaw mixed-mode fracture in various ceramics indicate that the flaw-plane normal stress at fracture decreases with increasing in-flaw-plane shear stress, although present data exhibit a fairly wide range in details of this sigma - tau relationship. Fracture from large cracks suggests that Mode II has a greater effect on Mode I fracture than Mode III. A comparison of surface flaw and large crack mixed-mode I-II fracture responses indicated that surface flaw behavior is influenced by shear resistance effects.

  7. Scaling up the microwave firing of ceramics

    Wroe, F.C.R.

    1993-01-01

    EA Technology, through a comprehensive R ampersand D program, is developing new microwave furnace technology focused on the ceramics processing industries. Using a combination of computer modelling, experimentation and feasibility studies, EA Technology has developed processes and procedures for firing large ceramic components. The aim of this work is to describe the investigation of the firing of ceramic products such as bricks, pottery, refractories, and industrial ceramics, using advanced processing techniques to produce and maintain uniformity of temperature throughout the components and kiln environment. This has achieved the goal of producing uniform microstructures and low thermal stress by careful control of the firing cycle. This paper illustrates the feasibility of microwave-assisted firing and shows it to be economically viable in terms of energy costs and process control. 6 refs., 1 fig

  8. Additively Manufactured Ceramic Rocket Engine Components

    National Aeronautics and Space Administration — HRL Laboratories, LLC, with Vector Space Systems (VSS) as subcontractor, has a 24-month effort to develop additive manufacturing technology for reinforced ceramic...

  9. Additive manufacturing of polymer-derived ceramics

    Eckel, Zak C.; Zhou, Chaoyin; Martin, John H.; Jacobsen, Alan J.; Carter, William B.; Schaedler, Tobias A.

    2016-01-01

    The extremely high melting point of many ceramics adds challenges to additive manufacturing as compared with metals and polymers. Because ceramics cannot be cast or machined easily, three-dimensional (3D) printing enables a big leap in geometrical flexibility. We report preceramic monomers that are cured with ultraviolet light in a stereolithography 3D printer or through a patterned mask, forming 3D polymer structures that can have complex shape and cellular architecture. These polymer structures can be pyrolyzed to a ceramic with uniform shrinkage and virtually no porosity. Silicon oxycarbide microlattice and honeycomb cellular materials fabricated with this approach exhibit higher strength than ceramic foams of similar density. Additive manufacturing of such materials is of interest for propulsion components, thermal protection systems, porous burners, microelectromechanical systems, and electronic device packaging.

  10. Ceramics and glasses for radioactive waste storage

    Baudin, G.

    1984-06-01

    Borosilicate glasses are mainly choosen for the confinement of fission products; industrial plants are either in operation (AVM) or in construction. Studies of ceramics as a matrix haven't received real application [fr

  11. Celsian Glass-Ceramic Matrix Composites

    Bansal, Narottam P.; Dicarlo, James A.

    1996-01-01

    Glass-ceramic matrix reinforced fiber composite materials developed for use in low dielectric applications, such as radomes. Materials strong and tough, exhibit low dielectric properties, and endure high temperatures.

  12. Radiation effects on structural ceramics in fusion

    Hopkins, G.R.; Price, R.J.; Trester, P.W.

    1986-01-01

    Ceramics are required to serve in a conventional role as electrical and thermal insulators and dielectrics in fusion power reactors. In addition, certain ceramic materials can play a unique structural role in fusion power reactors by virtue of their very low induced radioactivity from fusion neutron capture. The aspects of safety, long-term radioactive waste management, and personnel access for maintenance and repair can all be significantly improved by applying the low-activation ceramics to the structural materials of the first-wall and blanket regions of a fusion reactor. Achievement of long service life at high structural loads and thermal stresses on the materials exposed to high-radiation doses presents a critical challenge for fusion. In this paper, we discuss radiation effects on structural ceramics for fusion application

  13. Toward Modeling Limited Plasticity in Ceramic Materials

    Grinfeld, Michael; Schoenfeld, Scott E; Wright, Tim W

    2008-01-01

    The characteristic features of many armor-related ceramic materials are the anisotropy on the micro-scale level and the very limited, though non-vanishing, plasticity due to limited number of the planes for plastic slip...

  14. Photon CT scanning of advanced ceramic materials

    Sawicka, B.D.; Ellingson, W.A.

    1987-02-01

    Advanced ceramic materials are being developed for high temperature applications in advanced heat engines and high temperature heat recovery systems. Small size flaws (10 - 200 μm) and small nonuniformities in density distributions (0.1 -2%) present as long-range density gradients, are critical in most ceramics and their detection is of crucial importance. Computed tomographic (CT) imaging provides a means of obtaining a precise two-dimensional density map of a cross section through an object from which accurate information about small flaws and small density gradients can be obtained. With the use of high energy photon sources high contrast CT images can be obtained for both low and high density ceramics. In the present paper we illustrate the applicability of the photon CT technique to the examination of advanced ceramics. CT images of sintered alumina tiles are presented from which data on high-density inclusions, cracks and density gradients have been extracted

  15. Transparent Ceramic Scintillator Fabrication, Properties and Applications

    Cherepy, N.J.; Kuntz, J.D.; Roberts, J.J.; Hurst, T.A.; Drury, O.B.; Sanner, R.D.; Tillotson, T.M.; Payne, S.A.

    2008-01-01

    Transparent ceramics offer an alternative to single crystals for scintillator applications such as gamma ray spectroscopy and radiography. We have developed a versatile, scaleable fabrication method, using Flame Spray Pyrolysis (FSP) to produce feedstock which is readily converted into phase-pure transparent ceramics. We measure integral light yields in excess of 80,000 Ph/MeV with Cerium-doped Garnets, and excellent optical quality. Avalanche photodiode readout of Garnets provides resolution near 6%. For radiography applications, Lutetium Oxide offers a high performance metric and is formable by ceramics processing. Scatter in transparent ceramics due to secondary phases is the principal limitation to optical quality, and afterglow issues that affect the scintillation performance are presently being addressed

  16. Microstructure and properties of ceramic materials

    Yen Tungsheng

    1984-01-01

    Ceramics materials study is an important field in modern materials science. Each side presented 19 papers most of which were recent investigations giving rather extensive coverage of microstructure and properties of new materials. (Auth.)

  17. Composite metal foil and ceramic fabric materials

    Webb, Brent J.; Antoniak, Zen I.; Prater, John T.; DeSteese, John G.

    1992-01-01

    The invention comprises new materials useful in a wide variety of terrestrial and space applications. In one aspect, the invention comprises a flexible cloth-like material comprising a layer of flexible woven ceramic fabric bonded with a layer of metallic foil. In another aspect, the invention includes a flexible fluid impermeable barrier comprising a flexible woven ceramic fabric layer having metal wire woven therein. A metallic foil layer is incontinuously welded to the woven metal wire. In yet another aspect, the invention includes a material comprising a layer of flexible woven ceramic fabric bonded with a layer of an organic polymer. In still another aspect, the invention includes a rigid fabric structure comprising a flexible woven ceramic fabric and a resinous support material which has been hardened as the direct result of exposure to ultraviolet light. Inventive methods for producing such material are also disclosed.

  18. Testing Consent Order on Refractory Ceramic Fibers

    This notice announces that EPA has signed signed an enforceable testing consent order under the Toxic Substances Control Act (TSCA), 15 U.S.C. section 2601 at seq., with three of the primary producers of refractory ceramic fibers (RCF).

  19. Phytochemical study and evaluation of anti-inflammatory activity of Aeschynomene fluminensis Vell. (Fabaceae); Estudo fitoquimico e avaliacao da atividade anti-inflamatoria de Aeschynomene fluminensis Vell. (Fabaceae)

    Ignoato, Marlene Capelin; Fabrao, Rodrigo Monteiro; Schuquel, Ivania Teresinha Albrecht; Botelho, Marcos Felipe Pinatto; Santin, Silvana Maria de Oliveira [Universidade Estadual de Maringa (UEM) PR (Brazil). Dept. de Quimica; Arruda, Laura Licia Milani de; Bersani-Amado, Ciomar Aparecida [Universidade Estadual de Maringa (UEM) PR (Brazil). Dept. de Farmacologia e Terapeutica; Souza, Maria Conceicao de, E-mail: smoliveira@uem.br [Universidade Estadual de Maringa (UEM) PR (Brazil). Dept. de Biologia

    2012-07-01

    Phytochemical investigation of Aeschynomene fluminensis leaves and branches led to isolation of the flavonoid glycosides kaempferol 3,7-di-O-{alpha}-L-rhamnopyranoside, kaempferol 7-O-{alpha}-L-rhamnopyranoside, kaempferol 3-O-apiofuranosil-7-O- rhamnopyranoside, quercetin 3-O-{alpha}-L-rhamnopyranoside, quercetin 3-O-arabinofuranoside, 8-{beta}-D-glucopyranosyl 4',5,7-trihydroxyflavanone, the isoflavonoid 4',7-di-hydroxy-isoflavone, the dimer epicatechin-(2{beta} ->7, 4{beta} ->8)- epicatechin, the polyol 3-O-methyl-chiro-inositol and two steroids in sitosterol and stigmasterol mixture. These compounds were identified by NMR {sup 1}H and {sup 13}C and compared with literature data. Anti-inflammatory activity of the crude methanolic extract and its fractions was evaluated (author)

  20. Evaluation of pollution effects in transmission lines located in industrial areas; Avaliacao dos efeitos da poluicao em linhas de transmissao situadas em regiao industrial

    Kanashiro, Arnaldo G.; Burani, Geraldo F. [Sao Paulo Univ., SP (Brazil). Inst. de Eletrotecnica e Energia; Nascimento, Iara R. [Eletricidade de Sao Paulo SA, SP (Brazil)

    1995-12-31

    This work aims to determinate a correlation between the pollution levels and electric power transmission lines maintenance procedures in order to establish the necessary procedures for specific pollution levels. The methodology is presented. The results obtained in field tests and bench scale tests are presented and discussed. The so called pollution equivalent is determined for each site of the transmission line studied and maintenance procedures are established 6 refs., 5 figs., 4 tabs.

  1. Evaluation of morphological changes of the skin after radiation-induced injury in Wistar rats;Avaliacao de alteracoes morfologicas da pele apos lesao radioinduzida em ratos Wistar

    Andrade, Cherley Borba Vieira de

    2010-07-01

    The cancer covers a heterogeneous group of more than 100 diseases with different etiology and prognosis. Radiotherapy is one of the most commonly used treatment modalities, aiming at the destruction of cancer cells, using ionizing radiation. One of the limiting factors of radiotherapy is that radiation promotes the death of tumor cells in addition to injure healthy tissue neighboring the tumor, and may cause their death. Irradiation of the skin, accidental or for therapeutic purposes can trigger many injuries culminating in fibrosis, which implies functional alteration of the body. The evaluation of morphological effects associated with skin irradiation becomes essential to develop more effective radiation strategies and decreased morbidity; and in case of accidents, proper handling of the victim.Evaluate radio-induced dermal changes using a Wistar rats model irradiated with 10, 40 and 60Gy. Male Wistar rats, aged approximately three months, were pre-anesthetized with midazolam and xylazine and anesthetized with sodium pentobarbital, shaved in the back, immobilized on polystyrene support in the prone position and irradiated with doses of 10, 40 and 60 Gy, with 4MeV nominal energy electron beams. The skin was irradiated in a 3cm{sup 2} field, and used 0.5cm of tissue equivalent material, to obtain a homogeneous dose distribution. After irradiation, the animals remained on constant evaluation, and the lesions were recorded photographically. The animals were divided into groups and were killed on the irradiation day, 5, 10, 15, 25 and 100 days after irradiation. The skin was fixed in 10% formaldehyde; the samples were embedded in paraffin and cut. The sections were stained with hematoxylin-eosin, picrosirius red and immuno stained with antibody anti-TGF beta1. Another part of the tissue was fixed in 2.5% glutaraldehyde and processed for scanning electron microscopy. It was observed macroscopically the appearance of skin lesions similar to burns on the entire irradiated area. The optical microscope verified the early development of lesions in the 5 days group. After 10 days of irradiation it was already possible to see evidences of epidermal healing under the crust formed by the lesion. At 15 days after irradiation the tissue beneath the lesion had reconstructed epidermis. It was also observed the characteristics of tissue healing. It was also seen a significant polymorphonuclear cells infiltration. After 25 days at the higher doses the lesions remained, which did not occur at the lower dose, where the irradiated area of the animals were already completely healed. After 100 days of irradiation at 40Gy dose the wound was healed with the emergence of a well defined healed tissue. At the 60Gy dose, the lesion persisted in some animals, and in those that healing occurred the epidermis was a hypertrophied (acanthosis). It was visualized a tissue with their morphological aspect completely mis characterized, where it's possible to view a necrotic tissue. The results of the scanning electron microscopy analysis corroborate with the in optical microscopy findings, where it's possible to visualize the distortion of collagen fibers at the higher dosages. The results indicate that the used doses induced an important skin inflammatory process, activating the immune system. This fact leads to an increase in the expression of TGF beta1, one of the responsible for the increased production of extracellular matrix (ECM) by various cell types, mainly fibroblasts in injured tissues. Besides the increased expression of ECM, the TGF beta1 also promotes the inhibition of the degradation processes of the same. The intense expression of cytokines in irradiated skin can trigger the fibrosis process; consequently, affect the homeostasis of this organ due to the accumulation of ECM. (author)

  2. Evaluation of dosimetric effects caused by the table top of therapy; Avaliacao dos efeitos dosimetricos causados pelo tampo da mesa de tratamento

    Camargo, Andre Vinicius de; Alvares, Bruno; Fioravante, Gustavo Donisete; Silva, Diego da Cunha Silveira Alves da; Giglioli, Milena; Batista, Felipe Placido; Silva, Lais Bueno da; Radicchi, Lucas Augusto [Hospital de Cancer de Barretos, SP (Brazil)

    2016-07-01

    The attenuation and bolus effect for two tables top from different manufacturers were investigated for 6MV photons. The bolus effect of couch was compared with 0,5cm bolus (water equivalent). Maximum attenuation found in Exact Couch table was 6,9% and the minimum was 0,63%. The rail of Exact Couch, for beam in 180 deg, was observed attenuation of 13,61%. The same way that for attenuation, the surface dose was different for each region of couch Exact Couch and for different components of iBeam evo. The percentage of the dose in the depth of 1,8 mm was greater for table top of Exact Couch (66,2%). The extender of table iBeam evo offered increase dose of 38,3% and it table top of 51,9% in the same depth. The bolus increased surface dose in 61,1%. The results of this study showed that table tops when in contact with surface of the patient may significantly increase surface dose and beam attenuation. (author)

  3. Evaluation of quality of tomographs of Rio de Janeiro state, Brazil; Avaliacao da qualidade dos tomografos do estado do Rio de Janeiro

    Travassos, P.C.B.; Belem, V.R.; Magalhaes, L.A.; Almeida, C.E.A. de, E-mail: luisalexandregm@hotmail.com [Instituto de Radioprotecao e Dosimetria, (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Lab. de Ciencias Radiologicas

    2014-07-01

    Computerized tomographs used in 56 institutions in the state of Rio de Janeiro were evaluated. Criteria of image quality and dosimetry were submitted. The results showed that some not performed optimize their protocols examinations or perform wrongly, which results in an increase in the dose received by patients, and an image in compromised quality. (author)

  4. Assessment of effect of chemical treatment to carnauba's fibers straw; Avaliacao do efeito de tratamento quimico as fibras da palha de carnauba

    Carvalho, T.M.P. de; Carvalho, L.F.M.; Oliveira, R.R. de; Sousa, F.M.S. de; Sousa, R.C. de; Marques, J.R., E-mail: thaismarjore.pc@gmail.com [Instituto Federal de Educacao, Ciencia e Tecnologia do Piaui (IFPI), Teresina, PI (Brazil)

    2016-07-01

    The use of natural fibers in composite materials has been highlighted in the scientific field. However, its application in polymer matrices usually requires surface modifications. The objective of this work was to treat carnauba's straw fibers with NaOH 1 % and NaOH 5% solutions and measure the water absorption. We used the X-ray diffraction (XRD configuration “Bragg- Brentano) for verification of the crystalline phases and Fourier Transform Infrared Spectroscopy (FTIR) to identify functional groups. The alkali treatment allowed the solubilization of the hemicellulose and lignin without causing changes to cellulose, as indicated by FTIR spectrophotometry and by the increase in crystallinity content. The samples showed the typical peaks of constituents of the fiber. The natural fiber showed an average water absorption of 256 %; fiber treated with NaOH 1%, 315 %; and treated with NaOH 5%, 405 %. Therefore, it is evident improvement in hydrophilicity, fundamental aspect in the interaction fiber / matrix. (author)

  5. Morpho-functional study of ionizing radiation effects on the rabbits` femoral vein; Avaliacao morfofuncional do efeito da radiacao ionizante sobre a veia femoral. Estudo experimental em coelhos

    Sakiyama, Mauro Yoshimitsu

    1996-12-31

    In this study we evaluate the effects of the ionizing radiation on the rabbits femoral vein. The samples of femoral vein were obtained from 56 New Zealand rabbits, male with ageing from 90 to 120 days, that were divided into 4 groups of 14 animals: one control group non-irradiated and three animal groups sacrificed 2 days, 14 days and 90 days after irradiation. In the three irradiated rabbits groups, each animal received the total dose 4000 cGy (rads) divided in 10 sessions of 400 cGy, a dose equivalent that utilized on clinical therapeutic. A morpho functional study of vein samples was carried out with: light microscopy: stained by hematoxin - eosin, Masson`s tricromic, and Verhoeff. Immunohistochemical: reactions of immunoperoxidase with monoclonal mouse anti-human endothelial cell factor CD-31 and anti-human Von Willebrand factor (factor VIII), to study the vein endothelium. Histomorphometry of elastic fiber system stained by Weigert`s resorcin-fuchsin with and without prior oxidation with oxone; for the study of mature, elaunin or pre-mature and oxytalan or young elastic fibers. Electronic microscopy: transmission and scanning. With the methodology utilized we observe changes in the femoral vein of the animals submitted to irradiation in relation to the control group, thus described: there is formation of vacuoles between the endothelium and the basal membrane, called sub endothelial vacuoles, in focal areas. The factor VIII and CD-31 endothelial antigens are preserved with no changes in their functions. Focal alterations are present in the endothelial surface with disorder in the setting and orientation of the endothelial cells. there is degeneration of the elastic fibers with significant decrease in their quantity in the stage, 2 days and 14 days after irradiation. There is increase in the quantity of elastic fibers in the late stage, 90 days after irradiation, tending to normality. In this present study, the changes described are not accompanied by venous thrombosis. (author) 101 refs., 22 figs., 2 tabs.

  6. Magnetic resonance imaging pre- and postoperative evaluation of tetralogy of Fallot; Avaliacao pre e pos-operatoria da tetralogia de Fallot por ressonancia magnetica

    Bernardes, Renata Junqueira Moll; Simoes, Luiz Carlos [Instituto Nacional de Cardiologia (INC), Rio de Janeiro, RJ (Brazil). Servico de Cardiologia da Crianca e do Adolescente; Marchiori, Edson [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Faculdade de Medicina. Dept. de Radiologia]. E-mail: edmarchiori@bol.com.br; Bernardes, Paulo Manuel de Barros; Gonzaga, Maria Beatriz Albano Monzo [Rede Labs/D' Or, Rio de Janeiro, RJ (Brazil)

    2004-08-01

    The purpose of this study was to assess the usefulness of magnetic resonance imaging (MRI) in the pre- and postoperative evaluation of patients with tetralogy of Fallot. Twenty patients aged 1 to 29 years were prospectively evaluated with black-blood and contrast-enhanced angiographic techniques, 11 with the classic form of tetralogy of Fallot and 9 with tetralogy of Fallot and pulmonary atresia. MRI studies provided adequate visualization of the aorta that was classified as dilated or not dilated, and definition of its position in all cases. The use of contrast-enhanced MR angiographic techniques provided excellent imaging of the main right and left pulmonary arteries. The results suggest that MRI, including contrast-enhanced angiography techniques, is a useful tool in the evaluation of patients with tetralogy of Fallot before and after cardiac surgery since it provides important anatomical information that is not always obtained with echocardiography. MRI can be considered an alternative to cardiac catheterization, particularly in the evaluation of the pulmonary vascular anatomy. (author)

  7. Evaluation of radon measuring technique using passive detector activated carbon; Avaliacao da tecnica de medicao do radonio utilizando detector passivo com carvao ativado

    Ferreira, Paulo Roberto Rocha; Lessa, Edmilson de Lima; Oliveira, Evaldo Paulo de, E-mail: epoliveira@aluno.ird.gov.br [Instituto de Radioprotecao e Dosimetria, (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Div. de Radioprotecao Ambiental e Ocupacional

    2014-07-01

    This study aims to evaluate the efficiency of measuring the radioactive gas Radon ({sup 222} Rn) with passive detector activated carbon. Alpha Guard, exposure chamber, air sampler, default font Radio, calibrator flow, flow adjuster, ducts drivers: For this, various equipment to make the measurement system as were used. An assembly of such equipment, with specific sequence was used allowing for more efficient exposure of passive detectors Radon gas. Twenty samples were heated to remove moisture and then stored in desiccator until the experiment were made. The exhibition was held passive dosimeters being removed from the chamber, and one hour after, subjected to analysis by gamma spectrometry in germanium (HPGe) for an hour. Subsequently, other measurements were made at scheduled times and sequential for one hour. The results were presented in report form and spectra, measures and graphs generated by Alpha Guard were also extracted. Finally we calculated the efficiency of the passive meter activated carbon. (author)

  8. Glass forming ability of the Al-Ce-Ni system; Avaliacao da capacidade de formacao vitrea do sistema Al-Ce-Ni

    Triveno Rios, C. [Engenharia Mecanica, Universidade Federal de Mato Grosso, Rondonopolis, MT (Brazil)], e-mail: triveno@ufmt.br; Surinach, S.; Baro, M.D. [Departamento de Engenharia de Materiais - Universidade Federal de Sao Carlos, SP (Brazil); Bolfarini, C.; Botta, W.J.; Kiminami, C.S. [Departamento de Fisica da Universidade Autonoma de Barcelona, Bellaterra (Spain)

    2010-07-01

    In the present work, the glass forming ability (GFA) and its compositional dependence on Al-Ni-Ce system alloys were investigated in function of several thermal parameters. Rapidly quenched Al{sub 85}Ni{sub 15}-{sub X}Ce{sub X} (X=4,5,6,7,10), Al{sub 90}Ni{sub 5}Ce{sub 5}, Al{sub 89}Ni{sub 2}.{sub 4}Ce{sub 8}.{sub 6}, Al{sub 80}Ni{sub 15.6}Ce{sub 4}.{sub 4} and Al{sub 78}Ni{sub 18.5}Ce{sub 3.5} amorphous ribbons were produced by melt-spinning and the structural transformation during heating was studied using a combination of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results showed that the GFA and the thermal stability in the Al-rich corner of Al- Ni-Ce system alloys were enhanced by increasing the solute content and specifically the Ce content (author)

  9. Morpho-functional study of ionizing radiation effects on the rabbits` femoral vein; Avaliacao morfofuncional do efeito da radiacao ionizante sobre a veia femoral. Estudo experimental em coelhos

    Sakiyama, Mauro Yoshimitsu

    1995-12-31

    In this study we evaluate the effects of the ionizing radiation on the rabbits femoral vein. The samples of femoral vein were obtained from 56 New Zealand rabbits, male with ageing from 90 to 120 days, that were divided into 4 groups of 14 animals: one control group non-irradiated and three animal groups sacrificed 2 days, 14 days and 90 days after irradiation. In the three irradiated rabbits groups, each animal received the total dose 4000 cGy (rads) divided in 10 sessions of 400 cGy, a dose equivalent that utilized on clinical therapeutic. A morpho functional study of vein samples was carried out with: light microscopy: stained by hematoxin - eosin, Masson`s tricromic, and Verhoeff. Immunohistochemical: reactions of immunoperoxidase with monoclonal mouse anti-human endothelial cell factor CD-31 and anti-human Von Willebrand factor (factor VIII), to study the vein endothelium. Histomorphometry of elastic fiber system stained by Weigert`s resorcin-fuchsin with and without prior oxidation with oxone; for the study of mature, elaunin or pre-mature and oxytalan or young elastic fibers. Electronic microscopy: transmission and scanning. With the methodology utilized we observe changes in the femoral vein of the animals submitted to irradiation in relation to the control group, thus described: there is formation of vacuoles between the endothelium and the basal membrane, called sub endothelial vacuoles, in focal areas. The factor VIII and CD-31 endothelial antigens are preserved with no changes in their functions. Focal alterations are present in the endothelial surface with disorder in the setting and orientation of the endothelial cells. there is degeneration of the elastic fibers with significant decrease in their quantity in the stage, 2 days and 14 days after irradiation. There is increase in the quantity of elastic fibers in the late stage, 90 days after irradiation, tending to normality. In this present study, the changes described are not accompanied by venous thrombosis. (author) 101 refs., 22 figs., 2 tabs.

  10. Dynamic system for the evaluation of CIM monitoring and control techniques; Sistema dinamico para avaliacao de tecnicas de monitoracao e controle da CIM

    Penna, Monica de Oliveira [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Biotecnologia e Ecossistemas]. E-mail: mpena@cenpes.petrobras.com.br; Baptista, Walmar; Brito, Rosane Fernandes de [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES). Tecnologia de Materiais, Equipamentos e Corrosao]. E-mails: walmar@cenpes.petrobras.com.br; rosanef@cenpes.petrobras.com.br; Silva, Edilson Domingos da; Nascimento, Juliana Rangel do [Fundacao Gorceix, Ouro Preto, MG (Brazil)]. E-mails: edilson@cenpes.petrobras.com.br; julianarn@cenpes.petrobras.com.br; Coutinho, Claudia M.L.M. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Biologia. Dept. de Biologia Celular e Molecular

    2002-03-01

    In general, the two main problems associated to the water injection system for secondary petroleum recovery are the corrosion control and the decrease in solid injection in the reservoir. Corrosion problems in injection water systems may have abiotic as well as biotic causes, and the occurrence of reservoir plugs can result from the injection of particles (suspended solids as well as corrosion products), bacteria and fouling formation. Due to the need to implement a methodology for the evaluation of abiotic and biotic corrosive processes, monitoring techniques and MIC control in a dynamic system, an apparatus was built that simulates the characteristics of a water injection system. The apparatus allows monitoring and control of the parameters that, when varied, may influence the performance of the quality of the injected water. The dynamic system was designed to simulate as precisely as possible the conditions that allow the SRB and heterotrophic bacteria to create fouling in a water injection system. This article discusses the dynamic system, analytical methods and some preliminary results. (author)

  11. Evaluation of average glandular dose in digital and conventional systems of the mammography; Avaliacao da dose glandular media em sistemas digitais e convencionais de mamografia

    Xavier, Aline C.S.; Barros, Vinicius S.M.; Khoury, Hellen J., E-mail: alinecx90@gmail.com, E-mail: vsmdbarros@gmail.com, E-mail: hjkhoury@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Mello, Francisca A. de, E-mail: francissamello@yahoo.com.br [Hospital das Clinicas do Recife (HCR/UFPE), PE (Brazil)

    2014-07-01

    Mammography is currently the most effective method of diagnosis and detection of breast pathologies. The main interest in this kid of exam comes from the high incidence rate of breast cancer and necessity of high quality images for accurate diagnosis. Digital mammography systems have several advantages compared to conventional systems, however the use of digital imaging systems is not always integrated to an image acquisition protocol. Therefore, it is questionable if digital systems truly reduce the dose received by the patient, because many times is introduced in the clinics without optimization of the image acquisition protocols. The aim of this study is to estimate the value of incident air Kerma and average glandular dose (AGD) in patients undergoing conventional and digital mammography systems in Recife. This study was conducted with 650 patients in three hospitals. The value of incident air Kerma was estimated from the measurement of the yield of equipment and irradiation parameters used for each patient. From these results and using the methodology proposed by Dance et al. the value of the average glandular dose was calculated. The results obtained show that the lowest value of AGD was found with conventional screen-film system, indicating that the parameters for image acquisition with digital systems are not optimized. It was also observed that the institutions with digital systems use lower breast compression values than the conventional. (author)

  12. Falling hammer use evaluation for hot deformation hardness testing; Avaliacao do uso de um martelo de queda, para a determinacao da resistencia a deformacao a quente

    Beck, J.C.P.C.; Cauduro, Carlos R.; Schaeffer, Lirio [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil)

    1990-12-31

    This work performs a evaluation of the characteristics hot leaking of a 8620 stainless steel, deformed at 870 deg C. The tools associated with the measurements was described and a comparison between the theoretical values and the values experimentally obtained from the performed tests. 5 figs., 3 refs.

  13. Magnetic resonance imaging of sella turcica: evaluation of patients with galactorrhea, amenorrhea and hyperprolactinemia; Ressonancia magnetica da sela turca: avaliacao de pacientes com galactorreia, amenorreia e hiperprolactinemia

    Santos, Alair Augusto Sarmet M.D. dos [Hospital Universitario Antonio Pedro, Niteroi, RJ (Brazil). Dept. de Radiologia; Moreira, Denise Madeira [Universidade Federal, Rio de Janeiro, RJ (Brazil). Faculdade de Medicina. Dept. de Radiologia; Andreiuolo, Pedro Angelo [Beneficencia Portuguesa de Niteroi, RJ (Brazil). Servico de Radiologia Santa Cruz Scan

    1999-08-01

    We have selected 135 cases of patients who have done magnetic resonance imaging of sella region, carried out from September, 1991 to August, 1996, who had galactorrhea (G), amenorrhea(A), and hyperprolactinemia (H), isolated or in association. The patients were divided in seven groups, according to the presence of these symptoms and signs. All examinations were made in a private clinic in the city of Rio de Janeiro, Brazil. Correlating these patients with the results of the magnetic resonance images, we found 57 micro adenomas, 31 normal examinations, 22 macro adenomas, 11 pituitary hyperplasias, 7 empty sella and 7 cases included in other aspects. The micro adenoma predominated in groups 1 (GAH), 2 (GH), 3 (HA) and 5 (H), that is, in all groups whose patients had hyperprolactinemia. In macro adenomas, a bright signal on T 1-weighted images indicates pituitary apoplexy with intratumoral hemorrhage. All in all, the magnetic resonance imaging is excellent method to be used in the evaluation of patients with changes in the hypothalamic-pituitary axis. (author)

  14. Evaluation of occupational exposure during the exploration and physical processing of monazite; Avaliacao das exposicoes ocupacionais durante as etapas de exploracao e beneficiamento fisico da monazita

    Farias, Joao Torres de

    2006-07-01

    In Brazil the most important concentrations of monazite sands occur in the beaches and sandbanks that extend throughout the coast, from the State of Rio Grande do Norte down to the State of Rio Grande do Sul, Brazil. Nowadays, the most important Brazilian monazite concentrations - considered as being the fourth worldwide reservoir of rare-earth elements - are located at the north seacoast of the State of Rio de Janeiro, near Buena town. At this location the Brazilian Nuclear Industries - INB - manages an industrial complex for prospecting, mining and physical separation and concentration of monazite sands. Among the elements present at the monazite sands there are the radioelements thorium and uranium, which make the monazite sand a radioactive mineral. Monazite is constituted basically of 62% in TR{sub 2}0{sub 3} (rare-earth oxides), 5,5% of thorium in Th0{sub 2} (thorium oxide) and 0,25% of uranium in U{sub 3}0{sub 8} (uranium oxide). The general objective of the present work was to estimate the occupational doses at the industrial complex for prospecting, mining and physical separation and concentration of monazite sands located at Buena, at the north of the State of Rio de Janeiro. The occupational exposures occur mainly through the inhalation of airbone dust particles of mineraIs containing thorium and uranium, during the prospection and physical separation and concentration of monazite. To evaluate the impact of the occupational exposures during the physical separation and concentration of monazite, it was necessary to evaluate the effective equivalent doses due to thorium contamination of the air and the exposures due to the daughter radionuclides from the natural series of uranium and thorium. The results obtained at the present work showed that, although occupational doses are within the annual dose limits established by the Brazilian regulatory authority - CNEN - in some of the working places within the industrial complex the concentrations of radionuclides in air are above the maximum recommended levels. (author)

  15. Synthesis and preliminary evaluation of N-acylhydrazone compounds as antibacterial and antifungal agents; Sintese e avaliacao preliminar da atividade antibacteriana e antifungica de derivados N-acilidrazonicos

    Cachiba, Thomas Haruo; Carvalho, Bruno Demartini; Carvalho, Diogo Teixeira [Universidade Federal de Alfenas, MG (Brazil). Fac. de Ciencias Farmaceuticas. Dept. de Alimentos e Medicamentos; Cusinato, Marina; Prado, Clara Gaviao; Dias, Amanda Latercia Tranches, E-mail: diogo.carvalho@unifal-mg.edu.br [Universidade Federal de Alfenas, MG (Brazil). Inst. de Ciencias Biomedicas

    2012-07-01

    We describe the synthesis and evaluation of N-acylhydrazone compounds bearing different electron-donating groups in one of its aromatic rings, obtained using a four-step synthetic route. IC{sub 50} values against pathogenic fungi and bacteria were determined by serial microdilution. Compounds showed low activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. By contrast, a derivative with a meta-oriented electron-donating group showed significant activity (IC50) against Candida albicans (17 {mu}M), C. krusei (34 {mu}M) and C. tropicalis (17 {mu}M). Results suggest this is a promising lead-compound for synthesis of potent antifungal agents. (author)

  16. Assessment of activity of nitrate-reducing bacterial souring control; Avaliacao da atividade de bacterias redutoras de nitrato no controle de acidificacao de reservatorios de petroleo

    Sousa, Kally A. de; Cammarota, Magali C.; Servulo, Eliana F.C. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Escola de Quimica

    2008-07-01

    The effect of nitrate addition in relation to NRB concentration was evaluated on biogenic H{sub 2}S generation in anaerobic microcosms with produced water. A 2{sup k} factorial experimental design was performed by using as response variables nitrate (NO{sub 3}{sup -}) and sulfate (SO{sub 4}{sup =}) consumption and nitrite (NO{sub 2}{sup -}) and sulfide (H{sub 2}S) production and as independent variables the SRB and NRB (10{sup 1} - 10{sup 7} MPN/mL) and NO{sub 3}{sup -} (127.5 - 727.5 mg/L) initial concentrations. Each condition was carried out under incubation at 30 deg C during 7, 14 and 28 days. The lowest sulfide production (0.4 - 0.8 mg/L) was achieved for 10{sup 4} MPN/mL of SRB and NRB and 427.5 mg/L nitrate. Also, a reduction of sulfide generation was obtained by nitrate addition when low SRB and NRB concentrations were established. In such condition, the produced sulfide is rather dependent of nitrate concentration. The increase of the NRB concentration has not resulted in the reduction of sulfide production, even when higher nitrate concentrations were used. (author)

  17. Assessment in dogs tympanic bulla, through virtual tomographic endoscopy; Avaliacao de bulas timpanicas em caes, por meio da endoscopia tomografica virtual

    Silva, Luciana Carandina da; Sabino, Emanuelle Guidugli, E-mail: lucianacarandina@uol.com.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Botucatu, SP (Brazil). Faculdade de Medicina Veterinaria. Dept. de Reproducao Animal e Radiologia Veterinaria; Vulcano, Luiz Carlos; Machado, Vania Maria de Vasconcelos [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Botucatu, SP (Brazil). Faculdade de Medicina Veterinaria

    2012-07-01

    Dogs usually have problems related to the auditory canal. For the diagnosis of these pathologies, it is necessary a physical examination and, in some cases radiographic examination and computed tomography. The tympanic bulla is not easily visualized radiographically, since there is many structures of the brain overlaying the image obtained. The computed tomography has been the technique of choice to assess this structure faithfully. A new alternative assessment of the tympanic bulla is tomographic virtual endoscopy, which allows an improvement of the image obtained through the virtual tomographic technique. This paper provides information on the use of computed tomography, and a new technique, tomographic virtual endoscopy, in order to make the improvement of these techniques, and prove the reliability of these changes in the diagnosis of ear canals of dogs. Therefore, we performed the computed tomography of the tympanic bulla on healthy animals, and later performed image reconstruction in three-dimensional (3D) mode for virtual endoscopy. (author)

  18. Photoluminescence evaluation of TiO{sub 2} synthesized by Pechini method; Avaliacao da fotoluminescencia do TiO{sub 2} sintetizado pelo metodo Pechini

    Araujo, D.S.; Diniz, V.C.S.; Dantas, J.; Araujo, P.M.A.G.; Costa, A.C.F.M., E-mail: dagobertoufcg@gmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais; Viana, R.S.; Junior, S.A. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. Quimica Fundamental; Torquato, R.A. [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil). Dept. de Engenharia de Materiais

    2017-07-15

    Titanium dioxide (TiO{sub 2}) stands out for use in various applications mainly due to its properties of thermal and chemical stability and its excellent optical properties. However, these properties are dependent on the type and phase morphology, which is related to the TiO{sub 2} processing method. Thus, this paper proposed to synthesize TiO{sub 2} nanoparticles by polymeric precursor method with different polymorphs, and evaluate the influence of these phases in the photoluminescent properties. For this, the stoichiometric molar proportions of citric acid:metallic cations of 1:1, 2:1, 3:1, 4:1 and 5:1 were investigated. The nanoparticles were characterized by X-ray diffraction (XRD), infrared spectroscopy, textural analysis, scanning electron microscopy (SEM), excitation and emission spectroscopy and determination of the band gap by UV-Vis diffuse reflectance spectroscopy. The presence of anatase and rutile was confirmed by XRD in different proportions for each sample. The agglomerate size increased with the citric acid/metal cations ratio as observed by SEM. Concerning photoluminescence, the maximum intensity in the emission spectrum occurred at the wavelength of 533 nm for the 3:1 sample and the maximum intensity in the excitation spectrum occurred for the 2:1 sample at the wavelength of 451 nm. (author)

  19. Radiographic and tomographic study of the elbow joint in dogs; Avaliacao morfologica e morfometrica da articulacao umerorradioulnar em caes atraves de exames radiograficos e por tomografia computadorizada

    Sendyk-Grunkraut, Alessandra; Martin, Claudia M.; Souza, Alexandre N.A.; Patricio, Geni Cristina F.; Lorigados, Carla A.B.; Matera, Julia M.; Fonseca-Pinto, Ana C.B.C., E-mail: anacarol@usp.br [Universidade de Sao Paulo (FMVZ/USP), SP (Brazil). Faculdade de Medicina Veterinaria e Zootecnia

    2017-02-15

    Elbow dysplasia disease includes an united anconeal process, fragmented medial coronoid process, osteochondrosis of humeral trochlea, articular incongruity and degenerative joint disease. The aim of this study was to present detailed morphologic and morphometric aspects of the elbow joint in dog in clinical and correlate with radiographic and tomographic (CT) exam. Inter-observer variation for articular incongruity measurements by CT, comparative analysis in the radiographic exam, angle in ulnar notch and its comparative analysis between radiographic and tomographic agreement examination in 44 elbow of dogs with different ages were evaluated. The statistics analyses included the kappa coefficient and interclass correlation and Fischer's test and McNemar's test. It was evidenced that individual performance of each radiographic incidence had poor agreement with the tomographic exam, suggesting that the accomplishment of more than two radiograph views are needed. There was no agreement between the three evaluators in the ulnar notch angle at radiographic and tomographic exams. However, there was good/moderate agreement for articular incongruity measurement in the sagittal plane between evaluators. It was possible to conclude that none of the five radiographic incidences was better than the others for radiographic analysis because each incidence had a better identification of a particular elbow compartment; measurements at the tomographic exam to evaluate radioulnar incongruity had no reproductiveness in the frontal plane, but in sagittal plan had a good/moderate agreement between observers and the angle in ulnar notch presented no repeatability at radiographic exam and no reproductiveness at tomographic exam. (author)

  20. Evaluation of impact strength of polyamide 6/bentonite clay nanocomposites; Avaliacao da resistencia mecanica sob impacto de nanocompositos de poliamida 6/argila bentonitica

    Paz, Rene A.; Leite, Amanda M.D.; Medeirosa, Vanessa da N., E-mail: rene@cct.ufcg.edu.b [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Curso de Pos-Graduacao em Ciencia e Engenharia de Materiais; Araujo, Edcleide M.; Melo, Tomas J.A. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Dept. de Engenharia de Materiais; Pessan, Luiz A. [Universidade Federal de Sao Carlos (DEMa/UFSCAR), SP (Brazil). Dept. de Engenharia de Materiais

    2010-07-01

    Nanocomposites of polymer/clay have had much attention in recent years, particularly those developed with layered silicates due to the need of engineering materials more efficient than pure polymers for certain applications. The level of exfoliation of layered silicates in crystalline structure of polymer matrices has been studied and has been observed that they affect the crystalline behavior and the physical and mechanical properties. In this study, nanocomposites of polyamide 6 were obtained by the melt intercalation method, using a regional bentonite modified with a quaternary ammonium salt in an amount of 3% by weight. XRD results showed that incorporation of salt among the layers of clay, making it organophilic and obtaining exfoliated and/or partially exfoliated structures. The impact properties of the nanocomposites showed inferior in relation to pure polyamide, in other words, lost of toughness. (author)

  1. Assessment and epidemiology of Chagas' disease in patients treated in Araguaina - Tocantins; Avaliacao e epidemiologia da cardiopatia chagasica em pacientes atendidos em Araguaina - Tocantins

    Correa, Valeria Rita

    2010-07-01

    Chagas disease (AD) was described by Carlos Chagas in 1909. It is caused by a parasite T. cruzi, transmitted by bugs, by blood transfusion, vertical and orally. The DC has two phases: acute and chronic. The evolution to the cardiac form occurs in about 30% of chronic cases and is the largest cause of mortality in chronic Chagas disease. The aim of this study was to Chagas' disease in patients of Tocantins, compared with other heart patients and asymptomatic from the standpoint of non-invasive exams using radiant energies such as echocardiography and ECG and RX. The descriptive study included 80 patients, 20 chronic form of Chagas disease, 20 indeterminate, 20 with other heart diseases, and 20 controls. There was a prevalence of 9.5% of chagasic patients treated in outpatient cardiology at Araguaina Tocantins, and 7.3% in chronic and 2.21% in the indeterminate. Of the chronic patients in the study 50% had mega esophagus and megacolon 4 (20%). Most patients had no family history of AD, nor was a smoker or drinker. Major electrocardiographic abnormalities found refer to driving. The evaluation of ICT, the chronic chagasic showed that increased by 40% of patients, 40% had esophageal changes and 20% of patients had megacolon s. The echocardiogram was abnormal in 42%). 27% of patients had EF below 55% changed. Changes in segmental contractility and Asynchrony septum were found in 80% of chronic Chagas disease. In 80% of the patients was observed diastolic dysfunction. The valvular changes occurred in 75%. Electrocardiographic abnormalities occurred in 80% of patients with CCC, while the other heart had ECG changes. Arterial hypertension had an incidence of 45% in patients with CCC and 40% in FCI. The systolic and diastolic ventricular dysfunction was more prevalent in groups that had an abnormal ECG and arrhythmia. Observed that the group of chagasic decreased ejection fraction is correlated to a higher incidence of arrhythmias besides diastolic dysfunction and related increased atrio-left, ICT correlates with LV size and EF and LA. The abnormal ECG also are related to the dysfunction. (author)

  2. Assessment of natural radioactivity in wall paints of commercial use in Brazil; Avaliacao da radioatividade natural em tintas de uso comercial no Brasil

    Fonseca, Leandro Milhomens da

    2016-11-01

    Natural radioactivity in soils, rocks and construction materials, due to {sup 40}K and the natural series of {sup 232}Th and {sup 2}'3{sup 8}U, is the main contribution to external exposure in mankind. In this work, activity concentrations of {sup 226}Ra ({sup 238}U series), {sup 232}Th and {sup 4}'0K were determined for 50 white latex wall paints samples, commercialized in Brazil, namely 15 Economic quality samples, 15 Standard quality samples and 20 Premium quality samples and for a single titanium dioxide sample. The samples were tightly sealed and stored for a minimum period of 30 days, to reach the radioactive secular equilibrium from {sup 238}U and {sup 232}Th series, then measured by high resolution gamma ray spectrometry. The activity concentration was determined using the weighted average concentrations of {sup 214}Pb and {sup 214}Bi for {sup 226}Ra and {sup 228}Ac, {sup 212}Pb and {sup 212}Bi for {sup 232}Th. The {sup 4}'0K activity concentration was determined by its single transition of 1460.8 keV. Self attenuation correction factors of the samples whose densities are higher than 1.0 g.cm{sup -3}, were determined and used to make the necessary corrections. The radiological indices radium equivalent activity (Ra{sub eq}), activity concentration index (I{sub γ}), internal exposure risk index (H{sub in}) and external exposure risk index (H{sub ex}) and also the absorbed dose rate (D) and annual effective dose (D{sub ef}) were calculated from the activity concentrations of {sup 226}Ra, {sup 232}Th and {sup 40}K. The activity concentration values for {sup 226}Ra ranged from under the minimum detectable activity to 38.7 Bq.kg{sup -1}, for {sup 232}Th from under the minimum detectable activity to 101.2 Bq.kg{sup -1} and for {sup 40}K from under the minimum detectable activity to 256 Bq.kg{sup -1}. Ra{sub eq} ranged from 1.41 Bq.kg{sup -1} to 203 Bq.kg{sup -1}, I{sub γ} ranged from 0.0047 to 0.720, H{sub in} from 0.0076 to 0.653 and H{sub ex} from 0.0038 to 0.549. The absorbed dose rate ranged from 0.170 nGy.h{sup -1} and 21.3 nGy.h{sup -1} and the annual effective dose ranged from 0.83 μSv and 104.2 μSv. The results show that the activity concentrations of the wall paints studied in this work are below the recommended limits by Hassan et al. for Ra{sub eq} (370 Bq.kg{sup -1}), by European Commission for I{sub γ} (limit of 2 for superficial materials) and by the Organisation for Economic Co-operation and Development for H{sub in} and H{sub ex} (both with limit of 1), for all the 50 samples, assuring the safety of these wall paints with respect to radiological protection. (author)

  3. Renewability emergy index calculation in the evaluation of the sustainability of a national economy; Calculo do indice de renovabillidade emergetica na avaliacao da sustentabilidade de uma economia nacional

    Siche Jara, Raul Benito [Universidad Nacional de Trujillo, La Libertad (Peru). Fac. de Ciencias Agropecuarias. Escuela de Ingenieria Agroindustrial], e-mail: Siche.J.R@gmail.com; Ortega Rodriguez, Enrique [Universidade Estadual de Campinas (DEA/FEA/UNICAMP), SP (Brazil). Lab. de Engenharia Ecologica e Informatica Aplicada], e-mail: ortega@fea.unicamp.br

    2006-07-01

    In this study, the emergy methodology was used to analyze the sustainability of the Peruvian economic system. The resources (natural and not natural) and importations had been accounting in units of solar emergy using data of the Peruvian economy for the year 2004. Emergy is an energy measure based in the contribution of the resources and its influence, defined as the energy of a type required producing a flow or storage of another type. The focus of this study is the calculation of the emergy index call 'renewability' (REN), considered as a general measure of the ecological sustainability. In a long period, only systems or processes with high REN are sustainable. This index is calculated by the accounting of the resources renewed used in the economy in emergy units (2.17E+23 seJ) and divided by emergy total that enters to the economic system (6.93E+23 seJ), resulting a REN of 0.31. The renewable resources that use Peru almost represent 20% of the total of renewable resources available in the system. The great amount of renewable resources that Peru can potentially use was calculated in 11.44E+23 seJ, meaning that the system can be more sustainable if the economy is based on increasing the use of renewable resources and to diminish the use of non-renewable resources and imported resources. These data show that Peru has a relatively sustainable economy that can improve or get worse, depending of its politics in the use of resources. (author)

  4. Evaluation of effects of ionizing radiation on materials used in dental restorations;Avaliacao dos efeitos da radiacao ionizante em materiais utilizados em restauracoes dentarias

    Maio, Mireia Florencio

    2009-07-01

    This work consisted of quantitative studies of the effects caused by ionizing radiation on materials used in dental restorations (Titanium, Amalgam, Resin Composite and Glass Ionomer) aiming the deleterious effects of radiotherapy when patients with tumors in head and neck, arising when the teeth are restored within in the field of radiation. Samples were submitted to X-ray beams of 6 MV from a linear accelerator, VARIAN 2100C model. The samples were analyzed by X-ray fluorescence techniques to compare the chemical composition before and after the irradiation. The sample were submitted to Geiger-Mueller detectors and the ionization chambers in order to verify any residual radiation in the samples. The samples were also analyzed by gamma spectrometry by a Germanium detector. These tests were performed to determine small changes in the composition in the samples due to the radiation interaction. The results of this study may encourage the development of new research for alternative materials in dental restorations that can contribute to improve the quality of life of those patients with tumors of the mouth. (author)

  5. Synthesis optimization of calcium aluminate cement phases for biomedical applications; Avaliacao da sintese das fases de cimento de aluminato de calcio

    Andrade, T.L.; Santos, G.L.; Oliveira, I.R. [Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP (Brazil); Pandolfelli, V.C. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

    2011-07-01

    Calcium aluminate cement (CAC) has been studied as a potential material for applications in the areas of health such as, endodontics and bone reconstruction. These studies have been based on commercial products consisting of a mixture of phases. Improvements can be attained by investigating the synthesis routes of CAC aiming the proper balance between the phases and the control of impurities that may impair its performance for biomedical applications. Thus, the aim of this work was to study the CAC synthesis routes in the Al{sub 2}O{sub 3}-CaCO{sub 3} and Al{sub 2}O{sub 3}-CaO systems, as well as the phase characterization attained by means of X ray analysis. The Al{sub 2}O{sub 3}-CaO route enabled the production of the target phases (CA, CA{sub 2}, C{sub 3}A and C{sub 12}A{sub 7}) with a higher purity compared to the Al2O3-CaCO3 one. As a result the particular properties of these phases can be evaluated to define a more suitable composition that results in better properties for an endodontic cement and other applications. (author)

  6. Sintering evaluation of spinel MA nanostructured obtained via synthesis of combustion in solution; Avaliacao da sinterizacao de espinelio MA nanoestruturado obtido via combustao em solucao

    Vitor, P.A.M.; Braganca, S.R.; Bergmann, C.P., E-mail: pedroaugusto89@hotmail.com [Universidade Federal do Rio Grande do Sul (LACER/UFRGS), Porto Alegre, RS (Brazil). Laboratorio de Materiais Ceramicos

    2016-07-01

    Specimens were shaped from powders of spinel MA (MgAl2O4) obtained via synthesis combustion in solution (SCS) from the trio chemical precursor aluminum nitrate, magnesium nitrate and sucrose in water, and then sintered at different temperatures between 1350 and 1650 ° C. Were evaluated the physical properties (density, porosity, water absorption and linear shrinkage), mechanical (flexural 4 points), and the microstructures (SEM) as a function of sintering temperature. The densification increased with growing the value of the sintering temperature, wherein the temperature to 1650 ° C had the highest flexural strength and higher elastic modulus: 51.33 (± 6.83) and 26.16 MPa (± 5.06) GPa respectively. The study confirmed the microstructure of the densification of the particles, confirming the purity and nature of nanometric powders obtained via the SCS. (author)

  7. Preliminary results of the evaluation of biomass use as energy sources; Resultados preliminares da avaliacao do uso de biomassas como fontes de energia

    Rocha Ferreira, Leo da; Tourinho, Octavio A.F. [Instituto de Planejamento Economico e Social (IPES), Rio de Janeiro, RJ (Brazil). Inst. de Pesquisas

    1985-12-31

    This article discusses the preliminary results of the BIOMASSA model of IPEA with emphasis on three aspects: temporal and spatial crop mix patterns along the analysis horizon; evaluation of the social cost of alcohol fuel ; and the impact of alcohol production on the balance of payments. It concludes that the PROALCOOL increases domestic costs, but the impact on the balance of payments is positive and substantial. (author). 8 tabs

  8. Evaluation of the efficiency of injection of polyacrylamide in different reservoir-rock samples; Avaliacao da eficiencia de injecao de poliacrilamida em diferentes amostras de rocha-reservatorio

    Marcelino, Cleuton P.; Valentim, Adriano C.M.; Medeiros, Ana Catarina R. de; Girao, Joaquim H.S.; Barcia, Rosangela B. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2004-07-01

    Water soluble polymers have been used extensively in the petroleum recovery, due to their ability in increasing the viscosity of the injection water and to reduce water/oil mobility ratio and the water relative permeability in the reservoir. This reduction acts favorably as a secondary effect, and it reestablishes part of the pressure in the reservoir after the flow of the polymer, causing a correction of the injection profile in the wells through the restructuring of the resident fluids in the porous media. Nevertheless, some parameters influence the improve of this mechanism, such as petrophysics properties, chemical composition of the rock, adsorption, resistance factor and the residual resistance factor. Many paper in the area of polymers applied to the enhanced petroleum recovery indicate a high efficiency in the injection of different partially hydrolysed polyacrylamides, in different concentrations, or even in different injection conditions, as: temperature, flow, among others. In this work it was evaluated the behavior and efficiency of partially hydrolysed polyacrylamide flooding on outcrop cores from Botucatu, Rio Bonito, Clashach and Assu, using core flow tests and computer simulations. (author)

  9. Characterization and evaluation of residue 'grits' of the cellulose industry; Caracterizacao e avaliacao do resisduo 'grits' da industria de celulose

    Destefani, A.Z.; Santos, M.M.; Holanda, J.N.F. [Universidade Estadual do Norte Fluminense Darcy Ribeiro (LAMAV/CCT/UENF), Campos dos Goytacazes, RJ (Brazil). Lab. de Materiais Avancados

    2010-07-01

    The cellulose industry generates huge amounts of solid waste residue called 'grits'. These wastes have been willing over time in landfills near the mills. However, this type of disposal is not environmentally friendly and can cause degradation and environmental pollution. In addition, environmental legislation increasingly severe and the high costs of landfill have led the search for new alternatives for final disposition of this abundant waste. In this context, this study is to characterize waste grits, generated by the cellulose industry in the region of Aracruz-ES. The residue samples were characterized in terms of chemical composition, X-ray diffraction, particle size distribution and thermal analysis (DTA and TGA). The characterization of the residual 'grits' demonstrated its potential as a feedstock for production of soil-cement bricks. (author)

  10. Evaluation of bioactivity in vitro of endodontic calcium aluminate cement; Avaliacao da bioatividade in vitro de cimento endodontico a base de aluminato de calcio

    Oliveira, I.R.; Andrade, T.L.; Santos, G.L., E-mail: ivonero@univap.br [Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP (Brazil); Pandolfelli, V.C. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

    2011-07-01

    Bioactivity is referred to as the capacity of a material to develop a stable bond with living tissue via the deposition of hydroxyapatite. Materials which exhibit this property can be used to repair diseased or damaged bone tissue and can be designed to remain in situ indefinitely. An indication of bioactivity can be obtained by the formation of a hydroxyapatite layer on the surface of a substrate in simulated body fluids (SBF) in vitro. Therefore, set samples of calcium aluminate endodontic cement were maintained in contact with SBF solutions (Kokubo and Rigo) and their surfaces were later evaluated by means of SEM, EDX and DRX. Measurements of pH and ionic conductivity were also carried out for SBF solutions in contact with set samples of endodontic cement. The ideal conditions of precipitation were obtained in SBF Rigo been observed a surface layer with spherical morphology characteristic of stoichiometric hydroxyapatite.(author)

  11. Evaluation of the inflammatory activity in chronic osteomyelitis. Contribution of the scintigraphy with polyclonal antibodies; Avaliacao de atividade inflamatoria em osteomielite cronica. Contribuicao da cintilografia com anticorpos policlonais

    Sapienza, Marcelo Tatit

    1996-07-01

    Active chronic osteomyelitis or complicating osteomyelitis (superimposed on diseases that changes the normal bone structure fractures, post-surgery, prosthesis) can be difficult to diagnose by anatomic radiological imaging modalities, like plain radiograph and CT. These diseases frequently cause also increased bone remodeling, leading to nonspecific uptake of Tc-99m-bone scan agents and gallium-67. New radiopharmaceuticals with greater inflammation/infection avidity and specificity are being developed, including the nonspecific polyclonal immunoglobulin (IgG) labeled with technetium-99. Tc-99m-IgG may be available as a ready to use kit, with no reported side effects, low patient absorbed radiation dose and low cost. The mechanism of IgG uptake at the inflammation site has not been fully elucidated yet. Specific (receptor linking, physico-chemical immunoglobulin properties) and nonspecific mechanisms (enhanced vascular permeability and macromolecular exudate) has been suggested. IgG scintigraphy results are affected by the isotope, labeling procedure adopted and characteristics of the inflammatory focus. Nineteen patients with suspected osteomyelitis (active chronic osteomyelitis or violated bone osteomyelitis) were studied by Tc-99m-IgG scintigraphy (directly labeled polyclonal immunoglobulin, Sandoglobuilina - Sandoz). All patients also underwent standard three-phase bone scintigraphy using methylene diphosphonate (Tc-99m-MDP), gallium-67 scintigraphy and plain radiographs. Infection was found in 8 sites. Sensitivity and specificity for Tc-99m-MDP, gallium-67 and Tc 99m-IgG scintigraphy were, respectively, 88 and 36%, 75 and 73%,88 and 82%. All patients with false positive IgG scintigraphies had previous surgery. Other current scintigraphic procedures used in the diagnosis of osteomyelitis are also reviewed. (author)

  12. Evaluation of maximum absorbed dose for accompanying patients in nuclear medicine establishments; Avaliacao da dose maxima absorvida por acompanhantes de pacientes em servicos de medicina nuclear

    Cabral, Geovanna; Amaral, Ademir; Hazin, Clivis A. [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear; Lima, Ricardo A.; Nogueira, Maria S. [Centro Regional de Ciencias Nucleares (CRCN), Recife, PE (Brazil); Lopes, Ferdinand [Centro de Medicina Nuclear de Pernambuco (CEMUPE), Recife, PE (Brazil); Guimaraes, Maria Ines C.C. [Sao Paulo Univ., SP (Brazil). Centro de Medicina Nuclear

    2001-07-01

    In nuclear medicine, radioisotopes are bound to various pharmaceuticals for use in diagnostic and therapeutic applications. These unsealed sources are administered in various forms to patients, who remain radioactive for hours or days, and represent a source of potential radiation exposure for others. Thus, in nuclear medicine departments, radiation protection of workers and members of the public (especially persons accompanying patients) must consider this exposure. In this study, thermoluminescent dosimeters were given to various persons who were accompanying patients in two nuclear medicine departments in Recife, Pernambuco State, Brazil. Exposure results are given, and issues regarding exposure conditions and times for members of the public in these departments are discussed. (author)

  13. Magnetic resonance imaging textural evaluation of posterior cranial fossa tumors in childhood; Avaliacao textural por ressonancia magnetica dos tumores da fossa posterior em criancas

    Santos, Joelson Alves dos; Costa, Maria Olivia Rodrigues da; Otaduy, Maria Concepcion Garcia; Lacerda, Maria Teresa Carvalho de; Leite, Claudia da Costa [Sao Paulo Univ., SP (Brazil). Faculdade de Medicina. Dept. de Radiologia]. E-mail: joelson_alves@ig.com.br; Matsushita, Hamilton [Sao Paulo Univ., SP (Brazil). Faculdade de Medicina. Dept. de Neurologia

    2004-08-01

    Objective: To distinguish healthy from pathological tissues in pediatric patients with posterior cranial fossa tumors using calculated textural parameters from magnetic resonance images. Materials And Methods: We evaluated 14 pediatric patients with posterior cranial fossa tumors using the software MaZda to define the texture parameters in selected regions of interest representing healthy and pathological tissues based on T2-weighted magnetic resonance images. Results: There was a statistically significant difference between normal and tumoral tissues as well as between supposedly normal tissues adjacent and distant from the tumoral lesion. Conclusion: Magnetic resonance textural evaluation is an useful tool for determining differences among various tissues, including tissues that appear apparently normal on visual analysis. (author)

  14. Evaluation of poly(vinylpyrrolidone) and collagen by Low Field Nuclear Magnetic Resonance Spectroscopy; Avaliacao da polivinilpirrolidona e do colageno por ressonancia magnetica nuclear de baixo campo

    Costa, Paula de M.; Tavares, Maria I.B. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Macromoleculas Professora Eloisa Mano]. E-mail: pmcosta@ima.ufrj.br

    2005-07-01

    Blends of natural and synthetic polymers represent a new class of materials with better mechanical properties and biocompatibility than those of the single components. Collagen and poly(vinylpyrrolidone) are well known for their important biological properties. The blending of collagen with poly(vinylpyrrolidone) makes it possible to obtain new materials in which strong interactions between the synthetic and biological components occur. Do to the excellent biocompatibility of these polymers, this blend has been much studied intending biomedical applications. And a one technique that can provide important information on molecular mobility, compatibility and even evaluate the interactions that can occur with these polymers is the Low Field Nuclear Magnetic Resonance Spectroscopy. Thus, the purpose of this work is to evaluate collagen and poly(vinylpyrrolidone) by Low Field Nuclear Magnetic Resonance Spectroscopy. From the values of relaxation times obtained, we can conclude that these materials have different interactions, and different mobility domains, confirming the heterogeneity and complexity of these materials. (author)

  15. Chemical and microbiological assessments of the multi mixture treated by gamma radiation; Avaliacao quimica e microbiologica da multimistura tratada por irradiacao gama

    Goncalves, Cinthia Graciele

    2008-07-01

    In Brazil, the multi mixture have being used since the eighties as an alternative against severe infantile malnutrition of the poorest population. However, its use is still reason of controversies mainly due to: the presence of anti nutritional factors, the microbiological quality and the nutritional value. Considering the routine use of multi mixture in the region, this work aimed to evaluate samples of multi mixture were collected in the metropolitan area of the City of Belo Horizonte/MG for determining the anti nutritional factors (phytic and oxalic acids), the microbiological quality, the centesimal and mineral composition, and still the induced effect in these factors of the gamma radiation. For the analyses, the samples passed by the process of gamma irradiation at doses of: 2, 4, 6, 8 and 10 kGy and then were evaluated anti nutritional factors (phytic acid and oxalic), the microbiological quality (yeasts and molds, Salmonella, Coagulase positive Staphylococcus, Bacillus cereus, coliform to 45 deg C) to full percentage (moisture, ash, proteins, carbohydrates and lipids) and the efficiency of the method of Paramagnetic Electronic Resonance (EPR) in the detection of irradiated samples. The mineral composition of the samples was carried out by the irradiation by Neutronic Activation. The methods used were searched in literature. The obtained results suggest that the concentration of the phytic and oxalic acids can not be appropriated for the children with severe nutritional deficit and that it would be necessary additional control in their daily ingestion due to the absorption of essential minerals. In general the samples had presented acceptable microbiological quality for consumption, except by one of it. The data of the centesimal and mineral composition, in the usually recommended portions, showed lower concentration than recommended for children. Any significant alteration in phytic and oxalic acids as well as in the centesimal composition were detected after gamma irradiation. The electronic paramagnetic resonance can be detected irradiated samples. (author)

  16. Evaluation of absorbed radiation dose in mammography using Monte Carlo simulation; Avaliacao da dose absorvida em mamografia usando simulacao Monte Carlo

    Rodrigues, Bruno L.; Tomal, Alessandra [Universidade Estadual de Campinas (UNICAMP), Campinas, SP (Brazil). Instituto de Fisica Gleb Wataghin

    2016-07-01

    Mammography is the main tool for breast cancer diagnosis, and it is based on the use of X-rays to obtain images. However, the glandular tissue present within the breast is highly sensitive to ionizing radiation, and therefore requires strict quality control in order to minimize the absorbed dose. The quantification of the absorbed dose in the breast tissue can be done by using Monte Carlo simulation, which allows a detailed study of the deposition of energy in different regions of the breast. Besides, the results obtained from the simulation can be associated with experimental data and provide values of dose interest, such as the dose deposited in glandular tissue. (author)

  17. Exergy and thermoeconomic evaluation of hydrogen production from natural gas; Avaliacao exergetica e termo-economica da producao de hidrogenio a partir do gas natural

    Cruz, Flavio Eduardo da [PROMON Engenharia Ltda., Sao Paulo, SP (Brazil); Oliveira Junior, Silvio de [Universidade de Sao Paulo (USP), SP (Brazil). Escola Politecnica

    2008-07-01

    Some specific processes are required to obtain pure hydrogen and the most usual one is the natural gas reforming, where natural gas reacts with superheated steam producing H{sub 2}, CO, CO{sub 2} and H{sub 2}O. This paper presents exergy and thermoeconomic analysis of a complete hydrogen production unit of a petroleum refinery. The hydrogen production unit analysed in this paper has to supply 550,000 Nm{sup 3} of hydrogen per day to purify diesel oil. Based on a synthesis plant of the hydrogen production unit, the exergy efficiency of each component and of the overall plant are calculated. The hydrogen production cost is determined by means of a thermoeconomic analysis in which the equality cost partition method is employed, including capital and operational costs, in order to determine the production cost of hydrogen and other products of the plant.(author)

  18. Evaluation of homogeneity and dose conformity in IMRT planning in prostate radiotherapy; Avaliacao da homogeneidade e conformidade de dose em planejamentos de IMRT de prostata em radioterapia

    Lopes, Juliane S.; Leidens, Matheus; Estacio, Daniela R., E-mail: juliane.lopes@pucrs.br [Hospital Sao Lucas (PUC-RS), Porto Alegre, RS (Brazil). Servico de Radioterapia; Razera, Ricardo A.Z.; Streck, Elaine E.; Silva, Ana M.M. da [Pontificia Universidade Catolica do Rio Grande do Sul (PUC-RS), Porto Alegre, RS (Brazil). Faculdade de Fisica

    2015-12-15

    The goal of this study was to evaluate the dose distribution homogeneity and conformity of radiation therapy plans of prostate cancer using IMRT. Data from 34 treatment plans of Hospital Sao Lucas of PUCRS, where those plans were executed, were retrospectively analyzed. All of them were done with 6MV X-rays from a linear accelerator CLINAC IX, and the prescription doses varied between 60 and 74 Gy. Analyses showing the homogeneity and conformity indices for the dose distribution of those plans were made. During these analyses, some comparisons with the traditional radiation therapy planning technic, the 3D-CRT, were discussed. The results showed that there is no correlation between the prescribed dose and the homogeneity and conformity indices, indicating that IMRT works very well even for higher doses. Furthermore, a comparison between the results obtained and the recommendations of ICRU 83 was carried out. It has also been observed that the indices were really close to the ideal values. 82.4% of the cases showed a difference below 5% of the ideal value for the index of conformity, and 88.2% showed a difference below 10% for the homogeneity index. Concluding, it is possible to confirm the quality of the analyzed radiation therapy plans of prostate cancer using IMRT. (author)

  19. Importance of evaluation of uncertainties on the measurement of natural gas and petroleum volumes; Importancia da avaliacao das incertezas na medicao dos volumes de petroleo e gas natural

    Silva Filho, Jose Alberto Pinheiro da; Oliveira, Thiago Barra Vidal de; Mata, Josaphat Dias da [PETROBRAS, Rio de Janeiro, RJ (Brazil)], Emails: jose.pinheiro@petrobras.com.br, thiagovidal@petrobras.com.br, josaphat@petrobras.com.br; Val, Luiz Gustavo do [Instituto de Qualidade e Metrologia (IQM), Rio de Janeiro, RJ (Brazil)], E-mail: gdoval.iqm@petrobras.com.br

    2009-07-01

    The measurement is considered as the 'cash register' of the enterprises, increasing the accuracy and the exigence at each step when come close to the delivery points, where the 0.1 % of differences are discussed. The work presents the approach used in the evaluation of measurement uncertainties in the volumes obtained of petroleum and natural gas at the processes of production in Brazil, and in the international level as well.

  20. Residual stress evaluation and curvature behavior of aluminium 7050 peen forming processed; Avaliacao da tensao residual em aluminio 7050 conformado pelo processo peen forming

    Oliveira, R.R. de; Lima, N.B., E-mail: rolivier@ipen.b, E-mail: nblima@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Braga, A.P.V.; Goncalves, M., E-mail: anapaola@ipt.b, E-mail: mgoncalves@ipt.b [Instituto de Pesquisas Tecnologicas (IPT), Sao Paulo, SP (Brazil)

    2010-07-01

    Shot peening is a superficial cold work process used to increase the fatigue life evaluated by residual stress measurements. The peen forming process is a variant of the shot peening process, where a curvature in the plate is obtained by the compression of the grains near to the surface. In this paper, the influence of the parameters such as: pressure of shot, ball shot size and thickness of aluminum 7050 samples with respect to residual stress profile and resulting arc height was studied. The evaluation of the residual stress profile was obtained by sin{sup 2} {Psi} method. (author)