Estudio de la cinética de sinterizado de polvos nanoestructurados de CeO2 y Ce0.9Zr0.1O2

M. G. ZIMICZ; A. SOLDATI; S.A. LARRONDO.; F. PRADO

Córdoba

Congreso; Congreso Internacional de Metalurgia y Materiales, 16° SAM-CONAMET; 2016

Sociedad Argentina de Materiales

CeO2-based mixed oxides are important constituents of many catalytic systems for oxidation reactions [1?3], and they have received considerable attention in the formulation of anode materials for Solid Oxide Fuel Cells (SOFCs) operated with hydrocarbons (SOFCs) [4]. The anode material has to fulfill special requirements such as stable microstructure, high ionic and electronic conductivities and high catalytic activity at reduced temperatures [5]. One critical aspects of the use of Ce?Zr?O mixed oxides is the stability of its morphology. A processing step which has a major influence on the microstructure, is the thermal treatment used to fix the anode material to the electrolyte. For this reason, it is important to know the kinetics of sintering of the ceramic material. In this work, we analyze the sintering of CeO2 and Ce0.9Zr0.1O2 mixed oxide by means of Stepwise Isothermal Dilatometry (SID) and Constant Heating Rate (CHR) methods. The mixed oxides were characterized also by X ray diffraction and Transmission Electron Microscopy. Even though the identical composition and crystal structure of Ce0.9Zr0.1O2 samples, the sintering behavior resulted very different for each solid, indicating that sintering process is highly dependent on the morphology of the powders. The temperature at which appreciable densification occurs, increases with increasing crystallite size. Also, samples with lower crystallite size exhibits lower thermal expansion coefficients and lower activation energy for sintering. It was concluded that sintering mechanism of Ce0.9Zr0.1O2 is controlled mainly by grain boundary diffusion, like pure CeO2.REFERENCIAS1.A. Trovarelli, M. Boaro, E. Rocchini, C. de Leitenburg, G. Dolcetti, ?Some recent developments in the characterization of ceria-based catalysts? Journal of Alloys and Compounds 323?324 (2001) p. 584?591.2.P. Fornasiero, G. Balducci, R. Di Monte, J. Kaspar, V. Sergo, G. Gubitosa, A. Ferraro, M. Graziani, ?Modification of the Redox Behaviour of CeO2Induced by Structural Doping with ZrO2? Journal of Catalysis 164 (1996) p. 173?183.3.R. Di Monte, J. Kaspar, ?Heterogeneous environmental catalysis ? a gentle art: CeO2?ZrO2 mixed oxides as a case history? Catalysis Today 100 (2005) p. 27?35.4.D.G. Lamas, M.D. Cabezas, I.O. Fábregas, N.E. Walsöe de Reca, G.E. Lascalea, A. Kodjaian, M.A. Vidal, N.E. Amadeo, S.A. Larrondo, ?NiO/ZrO2-CeO2 Anodes for Single-Chamber Solid-Oxide Fuel Cells Operating on Methane/Air Mixtures? ECS Transactions 7 (1) (2007) p. 961? 970.5.A.J. Jacobson, ?Materials for solid oxide fuel cells? Chemistry of Materials 22 (2010) p. 660-674.