Annual Conference on Functional Materials and Nanotechnologies – FM&NT 2011 IOP Publishing IOP Conf. Series: Materials Science and Engineering 23 (2011) 012023 doi:10.1088/1757-899X/23/1/012023
Gradient composite metal-ceramic foam as supportive component for planar SOFCs and MIEC membranes Oleg Smorygo*1, Vitali Mikutski1, Alexander Marukovich1, Vladislav Sadykov2, Vladimir Usoltsev2, Natalia Mezentseva2, Anatolijs Borodinecs3, Oleg Bobrenok4 1
Powder Metallurgy Institute, National Academy of Sciences, Minsk, Belarus
2
Boreskov Institute of Catalysis, Russian Academy of Sciences, Novosibirsk, Russia
3
Institute of Heat, Gas and Water Technology, Riga Technical University, Latvia
4
Institute of Thermal Physics, Russian Academy of Sciences, Novosibirsk, Russia
E-mail:
[email protected] Abstract. A novel approach to the design of planar gradient porous supports for the thin-film SOFCs and MIEC membranes is described. The support’s thermal expansion is controlled by the creation of a two-component composite metal-ceramic foam structure. Thin MIEC membranes and SOFCs were prepared on the composite supports by the layerwise deposition of composite functional layers including complex fluorites and perovskites. Lab-scale studies demonstrated promising performance of both MIEC membrane and SOFC.
1. Introduction Dense MIEC ceramic membranes comprising both electronic and ionic conductors have a great potential for high-temperature catalytic processes including methane reforming into syngas [1]. If the membrane is thick, the bulk diffusion limits the oxygen permeability [2]. Thin membranes on porous supports are known to ensure the increased oxygen flux [3, 4]. As for SOFCs, the current trend is to decrease their operating temperatures to 600-800oC, which creates a potential for the reasonable manufacturing cost [5]. Due to dramatic decrease of the solid electrolyte (YSZ) electric conductivity SOFCs must be manufactured as a thin-layer laminated composite. [6]. The SOFC design concepts with a thin electrolyte layer and supporting functional layers (anode or cathode) [7] cannot resolve the problem because of the impeded mass transfer within the cells. The concepts with a special porous metallic supports bring many benefits in this respect [6, 8]. Thus, both thin layer MIEC membranes and intermediate temperature SOFCs require a porous support for the deposition of functional layers with a special combination of chemical, mechanical and physical properties. Porous FeCr steels made by powder metallurgy methods are considered to be promising supports due to the low cost, corrosive resistance and the thermal expansion coefficient (TEC) close to the solid electrolyte material [9]. FeCr support fundamental drawbacks are as follows: migration of poisoning Fe and Cr cations to the catalytic layer, limitations of heat treatments in oxidizing atmospheres during the functional layers deposition, and the necessity to deposit electric conductive barrier coatings [10]. A novel approach to the support design and composition is described in the paper.
Published under licence by IOP Publishing Ltd
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Annual Conference on Functional Materials and Nanotechnologies – FM&NT 2011 IOP Publishing IOP Conf. Series: Materials Science and Engineering 23 (2011) 012023 doi:10.1088/1757-899X/23/1/012023
2. Design of the composite supports According to the proposed approach, the support comprises two layers (figure 1 (a)): (1) a load bearing layer with the thickness of 2-2.5 mm has a highly-porous open-cell structure and ensures the support’s stiffness and robustness; (2) a layer with the thickness of about 500 μm that that has remarkably finer pores (
