Estudo da sinterização de eletrólito sólido de céria dopada com gadolínia
Fuel cells are electrochemical devices that convert chemical energy in electrical energy by a reaction directly. The solid oxide fuel cell (SOFC) works in temperature between 900ºC up to 1000ºC, Nowadays the most material for ceramic electrolytes is yttria stabilized zirconium. However, the high...
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| Formato: | doctoralThesis |
| Idioma: | por |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/12806 |
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| Resumo: | Fuel cells are electrochemical devices that convert chemical energy in
electrical energy by a reaction directly. The solid oxide fuel cell (SOFC) works in
temperature between 900ºC up to 1000ºC, Nowadays the most material for ceramic
electrolytes is yttria stabilized zirconium. However, the high operation temperature
can produce problems as instability and incompatibility of materials, thermal
degradation and high cost of the surround materials. These problems can be reduced
with the development of intermediate temperature solid oxide fuel cell (IT-SOFC) that
works at temperature range of 600ºC to 800ºC. Ceria doped gadolinium is one of the
most promising materials for electrolytes IT-SOFC due high ionic conductivity and
good compatibility with electrodes. The inhibition of grain growth has been
investigated during the sintering to improve properties of electrolytes. Two-step
sintering (TSS) is an interesting technical to inhibit this grain growth and consist at
submit the sample at two stages of temperature. The first one stage aims to achieve
the critical density in the initiating the sintering process, then the sample is submitted
at the second stage where the temperature sufficient to continue the sintering without
accelerate grain growth until to reach total densification. The goal of this work is to
produce electrolytes of ceria doped gadolinium by two-step sintering. In this context
were produced samples from micrometric and nanometric powders by two routes of
two-step sintering. The samples were obtained with elevate relative density, higher
than 90% using low energy that some works at the same area. The average grain
size are at the range 0,37 μm up to 0,51 μm. The overall ionic conductivity is 1,8x10-2
S.cm and the activation energy is 0,76 eV. Results shown that is possible to obtain
ceria-doped gadolinium samples by two-step sintering technique using modified
routes with characteristics and properties necessary to apply as electrolytes of solid
oxide fuel cell |
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