Ceria-based ceramic composites for high temperature thermochemical applications
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2018
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BRAZILIAN MRS MEETING, 17th
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Among thermochemical conversion processes, the production of fuels such as H2
via solar thermochemical cycles is potentially more efficient and more economical
than the use of electric energy to electrolyze water. The principle of solar
thermochemical cycles is based on the remarkable properties of some oxides,
which can be reduced and oxidized cyclically (redox cycles), i.e., releasing and
absorbing oxygen under certain temperature (or pressure) regimes. These redox
cycles can be efficiently used to convert H2O (or CO2) to H2 (CO). Thermochemical
redox cycles avoid the problematic step of fuel / O2 separation and allow operation
at more moderate temperatures (~ 1500 K) [1]. In this work, a new material
concept for the separation of high temperature H2O based on porous ceramic
composites composed of an ultra-high temperature ceramic phase (UHTC) and
doped cerium oxide is proposed. UHTC usually exhibit extremely low mass
diffusion rates and excellent thermomechanical properties for high temperature
applications [2]. Gadolinium-doped ceria (CGO) presents unique processes at low
oxygen partial pressure (pO2 < 10-12 atm) and high temperatures (T > 800 °C)
such as faster mass diffusion, which are not observed in conventional sintering
under ambient air conditions. In CGO/Al2O3 composites the resulting effects
driven by such mass diffusion are low viscosity flows and high reactivity between
phases, indicated by the formation of CeAlO3[3]. In this work, a comparison is
made between sintering CGO/Al2O3 under ambient air and reducing condition,
focusing on densification, viscosity and the evolution of the microstructure. The
redox process of CGO/Al2O3 is investigated using dilatometry, microscopy, and
electrochemical impedance spectroscopy. The preliminary results evidenced that
new phases with remarkable microstructure can be obtained at reducing
atmosphere depending on the temperature of reoxidation during cooling
Como referenciar
SILVA, PAULO M.; ESPOSITO, VINCENZO; MARANI, DEBORA; FLORIO, DANIEL Z. de; FONSECA, FABIO C. Ceria-based ceramic composites for high temperature thermochemical applications. In: BRAZILIAN MRS MEETING, 17th, September 16-20, 2018, Natal, RN. Abstract... São Carlos: Aptor Software, 2018. p. 989-989. Disponível em: http://repositorio.ipen.br/handle/123456789/30333. Acesso em: 20 Apr 2024.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.