Fuel cell system including porous, panel type support and process for producing the same

DETAILED DESCRIPTION OF THE INVENTION Referring now to the figures of the drawing in detail and first, particularly, to FIG.
1 thereof, there is seen a fuel cell system 1 which is formed essentially of fuel cells 1Z and a support 2.
The support 2 is of panel-type construction and is manufactured from a porous material.
The interior of the support 2 has cavities 2H passing through it which are disposed at a specified distance from one another and which have longitudinal axes that extend parallel to one another and to two surfaces 2A and 2B of the support 2.
The cavities 2H open outwardly at both ends of the support 2 so that air or oxygen can be passed through them.
The support 2 shown in FIG.
1 is 20-50 cm long and 10-30 cm wide.
Its thickness is 0.
8-1.
8 cm.
Its cavities 2H have a cross section of 0.
5.
times.
1 to 1.
2.
times.
2.
4 cm.
sup.
2.
The distance between two cavities 2H is 0.
1-0.
2 cm.
The support 2 is produced by means of an extrusion process.
The material used for manufacturing the support is composed of zirconium oxide which is stabilized with calcium oxide or magnesium oxide.
The proportion of calcium oxide or magnesium oxide is approximately 15 mol-%, based on the total molar weight of the ceramic material being used.
Instead of stabilized zirconium oxide, magnesium aluminum spinel (MgAl.
sub.
2 O.
sub.
4) may also be used.
Other temperature and corrosion-resistant ceramic materials may also be used, provided their coefficient of thermal expansion at 1000.
degree.
C.
is also in the vicinity of 10 to 11.
multidot.
10.
sup.
-6 degrees.
sup.
-1, as is the case for the above-mentioned materials.
The support 2 has a porosity which is 30 to 45%, based on the theoretical density of the ceramic material.
In order to achieve this porosity, pore formers are added to the extrusion compound.
Foaming agents in the form of polyalcohols or carbonates are suitable for this purpose.
The pore formers are thermally decomposed during the sintering of the ceramic to form the pores.
As can be seen by making reference to FIG