Prakt. Met. Sonderband 46 (2014) 157
PRODUCTION AND ANALYSIS OF POROUS METAL
SUPPORTS FOR A SOLID OXIDE FUEL CELL
H. Gschiel, C. Gierl-Mayer, H. Danninger
Technische Universität Wien, Getreidemarkt 9/164, 1060 Wien;
harald.gschiel@tuwien.ac.at
ABSTRACT
The Solid Oxide Fuel Cell is characterized by a very high electrical efficiency and the
highest efficiency in combined heat and power units. One of the major drawbacks of an
SOFC is the longtime stability. In order to have mechanical stability, the cell can be
supported by a so-called porous metal support, and these supports are usually
manufactured by tape casting. In contrast, this work is focused on processing these
porous metal supports by different powder metallurgical techniques such as the press- and
sinter route, gravity sintering or metal injection molding. The characterization of these
highly porous materials needs special metallographic techniques which allows to compare
the porosity (as well as the distribution of the pores) of the different samples. For the
gravity sintered sample (42% porosity) and the sample produced by MIM (26.5% porosity)
the pores are homogeneously distributed and only slight agglomeration of pores can be
seen. Also porosity quantification by image analysis has been carried out for the samples.
1. INTRODUCTION
The operating temperature of Solid Oxide Fuel Cells (SOFC) is typically between 800 and
1000°C, and fuel (e.g. pure Hy) and air (or pure O,) are fed as gases. The oxygen
molecules in the air take up electrons and, as negatively charged ions, move through the
electrolyte to the anode where they react with hydrogen to form water (vapor). The mode
of operation of an SOFC can be seen in Fig.1, and the electrolyte is a solid. non-porous
metal-oxide, usually Y>O3-stabilized ZrO. [1,2].
In order to get mechanical stability, the cell can be supported either by the electrolyte, the
electrodes or by a porous metal support. In case of a metal-supported fuel cell (MS-SOFC)
a thin film cell is deposited on top of this metal support. The load bearing part of the MS-
SOFC, is e.g. a highly porous Fe26Cr alloy and has a thickness of about 1 mm [3].
Significant cost reduction is thus possible since the bulk of the material can be composed
of inexpensive material, and the metal-supported design allows conventional metal joining
techniques such as brazing and welding [4].