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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Estudo da viabilidade do sistema LZAS para uso como selante de PaCOS

Valcacer, Samara Melo 22 March 2012 (has links)
Made available in DSpace on 2014-12-17T14:07:01Z (GMT). No. of bitstreams: 1 SamaraMV_DISSERT.pdf: 3021267 bytes, checksum: 443b2ba79e877562b95c18cd66a9716c (MD5) Previous issue date: 2012-03-22 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Cells the solid oxide fuel are systems capable to directly convert energy of a chemical reaction into electric energy in clean, quiet way and if its components in the solid state differentiate of excessively the techniques for having all. Its more common geometric configurations are: the tubular one and to glide. Geometry to glide beyond the usual components (anode, cathode and electrolyte) needs interconnect and sealant. E the search for materials adjusted for these components is currently the biggest challenge found for the production of the cells. The sealants need to present chemical stability in high temperatures, to provoke electric isolation, to have coefficient of compatible thermal expansion with the excessively component ones. For presenting these characteristics the glass-ceramics materials are recommended for the application. In this work the study of the partial substitution of the ZrO2 for the Al2O3 in system LZS became it aiming at the formation of system LZAS, this with the addition of natural spodumene with 10, 20 and 30% in mass. The compositions had been casting to a temperature of 1500?C and later quickly cooled with the objective to continue amorphous. Each composition was worn out for attainment of a dust with average diameter of approximately 3?m and characterized by the techniques of DRX, FRX, MEV, dilatometric analysis and particle size analysis. Later the samples had been conformed and treated thermally with temperatures in the interval between 700-1000 ?C, with platform of 10 minutes and 1 hour. The analyses for the treated samples had been: dilatometric analysis, DRX, FRX, electrical conductivity and tack. The results point with respect to the viability of the use of system LZAS for use as sealant a time that had presented good results as isolating electric, they had adhered to a material with similar ? of the components of a SOFC and had presented steady crystalline phases / Pilhas a combust?vel de ?xido s?lido (PaCOS) s?o sistemas capazes de converter energia de uma rea??o qu?mica diretamente em energia el?trica de maneira limpa, silenciosa e se diferenciam das demais t?cnicas por ter todos os seus componentes no estado s?lido. Suas configura??es geom?tricas mais comuns s?o: a tubular e a planar. A geometria planar al?m dos componentes usuais (anodo, catodo e eletr?lito) necessita de interconectores e selantes. E a busca por materiais adequados para esses componentes ? atualmente o maior desafio encontrado para a produ??o das pilhas. Os selantes precisam apresentar estabilidade qu?mica em altas temperaturas, provocar isolamento el?trico e ter coeficiente de dilata??o t?rmica compat?vel com os demais componentes. Por apresentarem essas caracter?sticas os materiais vitrocer?micos s?o os mais recomendados para a aplica??o. Neste trabalho fez-se o estudo da substitui??o parcial da Zr02 pela Al2O3 no sistema LZS visando a forma??o do sistema LZAS, isso com a adi??o 10, 20 e 30% em massa de espodum?nio natural. As composi??es foram fundidas a uma temperatura de 1500?C e depois resfriadas rapidamente com o objetivo de continuarem amorfas. Cada composi??o foi mo?da para obten??o de um p? com di?metro m?dio de aproximadamente 3?m e caracterizada pelas t?cnicas de DRX, FRX, MEV, dilatometria e granulometria. Posteriormente as amostras foram preparadas por compacta??o e tratadas termicamente com temperaturas no intervalo entre 700-1000 ?C, com patamar de 10min e 1h. As an?lises para as amostras tratadas foram: dilatometria, DRX, FRX, condutividade el?trica e ader?ncia. Os resultados apontam para a viabilidade do sistema LZAS para uso como selante uma vez que apresentaram bons resultados como isolante el?trico, aderiram a um material com coeficiente de dilata??o t?rmica (?) semelhante a dos componentes de uma PaCOS e apresentaram fases cristalinas est?veis / 2020-01-01

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