174 resultados para Ceramica vitrificada
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Mode of access: Internet.
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Abstract: The Mittanian zoomorphic vessels from Nuzi, Tell Brak, Tell al-Rimah and other sites allow the creation of a significant database for analysis based on typological criteria as well as spatial distribution. This class of materials is attested in several areas of the ancient Near East from the Late Calcholitic and still produced until the Mittanian age and thereafter. Most of the finds come from temples or domestic contexts and they can be now securely dated, while their spatial distribution can be properly investigated. Lion representations seem to predominate, but pigs and other animals appear as well. The exact function and meaning of these vessels are difficult to ascertain, nevertheless, in most cases, they are probably related to cultic practices performed throughout the Mittanian Empire.
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A análise acadêmica ora apresentada reflete a pesquisa vivencial que, como investigador do Programa de Pós-Graduação em Artes da Universidade do Estado do Rio de Janeiro (em sua linha de estudos em Arte, Cultura e Cognição), aferi em aldeias Mbyá-Guarani nas cidades de Niterói e Maricá desde o ano de 2012 a respeito de sua arte em barro. Com aportes etnohistóricos da sua cerâmica ancestral, esta ação foi assim realizada por levantamento de dados tanto pré-históricos quanto históricos focados sobre si. Porém, reconhecendo a escassez de seu fabrico entre aqueles Mbyá e, paradoxalmente, que ainda existam em seu meio mostras de que os artefatos de barro permanecem memorialmente sendo importantes para esse povo, tal exame não se restringiu a conhecer apenas a morfologia desses objetos, mas procurou vislumbrar um tanto de sua simbologia e recuperar essa ocorrência prática por meio de atividades artístico-pedagógicas junto às crianças dali. Portanto, através da pesquisa-ação e do método educativo de Célestin Freinet se buscou apontar oportunidades de revitalização dentro da sociedade Mbyá dessa memória do exercício de construção oleiro e de seu devido valor às suas crianças
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60 hojas : ilustraciones.
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A partir del conocimiento que se posee referente al desarrollo de las ladrilleras del sector de Nemocón y las herramientas y disciplinas aplicables al estudio de un plan de internacionalización, se determina desarrollar el siguiente proceso. En primer lugar, a partir de la necesidad de diagnosticar un análisis del sector ladrillero en Nemocón Cundinamarca, se hace indispensable utilizar herramientas de la línea de estrategia. Se requiere de un estudio matricial del comportamiento del sector con su respectivo análisis y para generar un mayor soporte técnico al análisis del sector, se requiere de un estudio de planeación estratégica por escenarios el cual proveerá a la investigación de diversas alternativas en la selección de variables fundamentales del sistema. Acerca del estudio de los mercados tanto nacional como internacional, se dispondrá de las habilidades básicas de la línea de mercadeo. Es importante que a partir del análisis del sector y de la obtención de algunas variables importantes, se indague a profundidad acerca de las variables más importantes para el desarrollo de una matriz de mercados. La idea de la aplicación de esta matriz, es generar unos filtros de países seleccionados a partir de variables anteriormente especificadas con el fin de determinar un único mercado que será el objetivo para el plan de internacionalización. Sobre el país seleccionado se aplica un estudio de mercado y un estudio de viabilidad financiera bajo los cuales se obtienen las conclusiones del plan de internacionalización, su viabilidad y sus recomendaciones.
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This paper reports the production of bismuth germanate ceramic scintillator (Bi4Ge3O12) by combustion synthesis (SHS) method, focusing on the influence of the synthesis parameters on the crystalline phases and agglomeration of the nanoparticles. The synthesis and sintering conditions were investigated through thermal analysis, X-ray diffraction as function of temperature, dilatometry and scanning electron microscopy. Well-dispersed Bi4Ge3O12 powder was accomplished by the combustion of the initial solution at pH 9, followed by low temperature calcination and milling. Sintered ceramics presented relative density of 98% and single crystalline Bi4Ge3O12 phase. The luminescent properties of the ceramics were investigated by photo- and radio- luminescence measurements and reproduced the typical Bi4Ge3O12 single-crystal spectra when excited with UV, beta and X-rays. The sintered ceramics presented light output of 4.4 x 10(3) photons/McV. (c) 2008 Published by Elsevier Ltd.
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Dutra, R. P. S.; Varela,M. L.; Nascimento, R. M. ; Gomes, U. U. ; Martinelli1, A. E. ; Paskocimas, C. A. Estudo comparativo da queima rápida com a queima tradicional nas propriedades de materiais cerâmicos de base argilosa. Cerâmica [online]. 2009, vol.55, n.333, pp. 100-105. ISSN 0366-6913. doi:Disponivem em:
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Lightweight concrete has been the subject of several studies towards the development of new building materials. Emphasis has been given on the particle size effect and nature of aggregates used as raw materials. The present study includes an analysis of the materials that make this kind of concrete, analyzes of mechanical properties such as compressive and tensile strength, in addition to assessments of the interface concrete aggregate/matrix interface, porosity and absorption profile of chloride ions in lightweight concrete based on expanded clay. The experiments were carried out by molding cylindrical samples 100 mm in diameter and 200 mm in height. The dosage experiments were performed without additives or with the addition of minerals: (T1) 1: 2.01: 1.10: 0.78 (T2) 1: 2.00: 1.32 : 0.62 - (T3) 1 :1.93 :1.54: 0.47 (cement : sand : expanded clay 0500 : expanded clay 1506).The water to cement ratio was set to 0.43. Expanded clay minerals with different average particle sizes were used, i.e., 9.5 mm/0500 and 19 mm/1506. The larger aggregate was coated by a glassy layer, yielding lower water absorption characteristics to the concrete. The results showed that the use of light expanded clay aggregates is a technically interesting solution to the production of lightweight concrete for construction applications
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Tin oxide has wakened up great scientific and technological interest for its potential use in varistors production and as gas sensor. In order to improve the microstructural and electrical properties in SnO2 varistor ceramics, the influence of differents dopants used, like TiO2 and Al2O3, is under research. The effect of TiO2 and Al2O3 on the properties of Sn-Co-Nb varistor systems obtained by the Pechini method has been investigated in this work. Characterization of synthesized raw material was performed by X-Ray Diffraction (XRD) and Scanning Electronic Microscopy (SEM). The microstructural and electrical characterization of sintered samples show that the TiO2 favors the grain growth and the Al2O3 contributes to the decrease it, effect that is manifested in the Sn-Co-Nb varistor systems. Breakdown field increase up to 6300V/cm with increasing Al2O3 content and non-linear coefficients with alpha=22 were obtained.
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Lithium niobate (LiNbO3) thin films with 1/1 stoichiometry were prepared by a spin-coating from polymeric precursor method. The films deposited on silicon (100) substrates, were thermally treated from 400° to 600°C for 3 hours in order to study the influence of thermal treatment on the crystallinity, microstructure, grain size and roughness. X-ray diffraction (XRD) results showed that LiNbO3 phase crystallizes at low temperature (400°C). It was observed by scanning electron microscopy (SEM) that it is possible to obtain dense thin films at temperatures around 500°C. The atomic force microscopy (AFM) results showed that the grain size and roughness are strongly influenced by the annealing temperature.
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Barium titanate is used extensively as a dielectric in ceramic capacitors, particularly due to its high dielectric constant and low dielectric loss characteristics. It can be made semiconducting by addition of certain dopants and by proper modification of grains and grain boundary properties obtaining very interesting characteristics for various applications. The synthesis method and sintering regime have a strong influence on properties of obtained barium titanate ceramics. Doped barium titanate was prepared with Nb+5 and Y+3 ions as donor dopants, and with Mn+2 ions as acceptor dopant by polymeric precursors method. By this procedure nanosized powders were obtained after calcination. Sintering was performed in the temperature range of 1290°C to 1380°C The microstructure of doped BaTiO3 was performed using scanning electron microscopy. The influence of dopants and sintering temperature on grain size was analysed.