Vitreous Silica
Mostrando 1-12 de 13 artigos, teses e dissertações.
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1. Investigações sobre a sinterização de sílica vítrea por plasma pulsado. / Investigations of vitreous silica sintering by spark plasma.
A obtenção da sílica vítrea pelo processo de sinterização por plasma pulsado (SPS), a partir de matérias-primas de diferentes estruturas (cristalina e amorfa) e diferentes granulometrias, foi investigada. Análises de difração de raios X, transmitância óptica, microscopia óptica e eletrônica de varredura, e medições de densidade foram realizad
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 30/06/2011
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2. Um novo método para síntese de vidros fotônicos baseado na sinergia entre as técnicas VAD e ALD / A new method for synthesis of photonic glasses based on the synergy between VAD and ALD techniques
This study aimed to establish a new method for synthesis of photonic glasses through the synergy of Vapor-phase Axial Deposition (VAD) and Atomic Layer Deposition (ALD) techniques. Having the intention to obtain a completely transparent material containing a uniform distribution of dopant element both radial and axial position. In the first stage of this stu
Publicado em: 2011
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3. GLASS AND GLASS-CERAMICS WITH HIGH METAL CONCENTRATION OF FROM INDUSTRIAL WASTES / Vidros e vitrocerâmicos com alta concentração de metais obtidos a partir de resíduos industriais
The reuse of industrial waste materials is considered as an important source of raw-materials to be employed at new products. However proper criteria is needed in order to obtain vitreous materials from industrial solid wastes like solid galvanic waste (metallurgical industry) as main raw material. Ajusting the composition silica fine powder (ceramic industr
Publicado em: 2008
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4. Propriedades estruturais do material vitreo silica-titania produzido pelo metodo do aerosol em chama / Structural properties of silica-titania vitreous material produced by flame aerosol method
O sistema binário sílica titânia, SiO2-TiO2,apresenta grande interesse tecnológico devido as suas propriedades: ultra-baixo coeficiente de expansão térmico e alto índice de refração. As propriedades são dependentes da quantidade de dopante presente no material. A SiO2-TiO2 é usada na indústria de componentes fotônicos, tais como, lentes, micro-l
Publicado em: 2008
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5. High sensitivity Thermal Lens spectroscopy / Espectroscopia de lente térmica de alta sensibilidade
The efficiency of conventional transmission methods used to measure absorption of hightransparent materials is usually limited by light scattering and reflection. On the other hand, Thermal Lens spectroscopy is insensible to such phenomena and has been widely applied to determinate low optical absorptions. In this thesis, we have studied a recently developed
Publicado em: 2008
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6. Vitrocerâmicas do sistema Li2O Al2O3 SiO2 (LAS) via siterização com cristalização corrente. / Synthesis of Li2O - Al2O3 - SiO2 (LAS) glass-ceramics by sintering with concurrent crystallization.
LAS (Li2O-Al2O3-SiO2) glasses have been often used to produce glass- ceramics with near zero thermal expansion coefficient. These glass-ceramics are very important for applications that require high thermal shock resistance. However, they are still produced by traditional techniques, such as melting and forming followed by internal nucleation (induced by the
Publicado em: 2007
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7. The use of swine deep bedding ash as partial substution of Portland cement. / Aproveitamento das cinzas da queima da cama sobreposta de suínos para substituição parcial do cimento Portland.
A sustentabilidade das regiões de produção intensiva de suínos depende de destinos alternativos para os resíduos gerados. A calcinação da casca de arroz pode gerar sílica vítrea para substituição parcial de aglomerantes comerciais. A utilização de cinzas de casca de arroz como material pozolânico para argamassas e concretos tem merecido atenç�
Publicado em: 2005
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8. "Caracterização eletroquímica e imobilização de metaloporfirinas em filmes de pirrol eletropolimerizados: preparação e aplicação". / Electrochemical characterization and immobilization of metalloporphyrins on electropolymerized pyrrole films: prepartion and application
This work describes the preparation and characterization of metalloporphyrin-modified electrodes and their application in the reduction or/and oxidation of organic compounds. The studied metalloporphyrins were 5,10,15,20-tetrakis(4-methylpyridyl) porphyrinmanganese(III)hexafluorophosphate, [Mn(T4MPyP)](PF6)5, and 5,10,15,20-tetrakis(2-aminophenyl)porphyr
Publicado em: 2003
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9. Obtenção de constantes opticas no infravermelho a partir de medidas de reflectancia especular via analise de Kramers-kronig
Kramers- Krönig analysis, which correlates the real and the imaginary parts of causal complex functions, provides the reconstruction of the phase shift spectra from reflectance spectra, when appIied to the complex specular reflectivity. Fresnel s formulae, by their turn, permit the calculation of the optical constants, refractive and absorption indexes, fro
Publicado em: 1998
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10. Efeito do tratamento superficial na devitrificação e dissolução da silica vitrea / Effect of surface treatment on devitrification and dissolution of vitreous silica
The effect of surface stress and roughness, produced by polishing process with abrasive powder, was investigated on the devitrification and dissolution of silica glass. The characterization studies of the silica glass treated by grinding, polishing and etching and their effect on the devitrification were conducted by X-ray diffraction, optical and electronic
Publicado em: 1997
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11. Modificação estrutural em silica vitrea e quartzo cristalino por implantação de He+ para guiamento optico
The purpose of this work was to study the technical application of íon implantation to modify the refraction index on vitreous and crystallines substrates, allowing the optical guidance. We have implanted HE + ions with energies from 30 to 190 KeV and doses from 1.0x10 16 to 2.5x10 16 ions/cm 2 in vitreous silica and crystalline quartz substrates, with perp
Publicado em: 1996
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12. Obtenção e caracterização de materiais dopados SiO2-CdSe a partir de sonogeis de silica
The sol-gel process has proved to be extremely interesting in the production of new materiaIs. This is clearly indicated by the great number of publications in this area in the last decade. The possibility of obtaining monolithic solid materials and also powders, films and fibers from a liquid mixture of components at room temperature via aggregation and pol
Publicado em: 1994