Base tube for fuel cell

Details Base tube for fuel cell Base tube for fuel cell

1999-02-26

2001-11-06

Brouillette, Gabrielle (Department: 1745)

Chemistry: electrical current producing apparatus, product, and

With pressure equalizing means for liquid immersion operation

C429S006000

Reexamination Certificate

active

06312847

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a base tube for a fuel cell, whose porosity and pore diameter are increased to improve the power generation characteristics of the resulting fuel cell.
2. Description of the Related Art
FIG. 1
shows the outline of a base tube of a thermal spray type solid electrolyte fuel cell.
A thermal spray type solid electrolyte fuel cell (SOFC), as shown in
FIG. 1
, is produced in the following manner: A thermit of Ni and yttria-stabilized zirconia (YSZ) is provided in a film form by plasma spraying on a porous cylindrical base tube
1
of calcia-stabilized zirconia (CSZ) to serve as a fuel electrode
2
. On this fuel electrode
2
, oxygen ion-conductive YSZ is provided in a film form by plasma spraying to serve as an electrolyte
3
. On this electrolyte
3
, LaCoO
3
is provided in a film form by acetylene flame spraying to serve as an air electrode
4
. In this manner, a fuel cell is constructed. Finally, the fuel electrode
2
and the air electrode
4
are connected together in series by an electrically conductive connecting material (interconnector)
5
in a film form composed of a thermit of NiAl and alumina.
The production of a fuel cell by thermal spraying as earlier technology is laborious and costly, and should be decreased in cost. Thus, a co-sinter type fuel cell, which is composed of a base tube, a fuel electrode and an electrolyte sintered integrally, and requires a reduced number of sintering operations, has been developed. However, this type of fuel cell poses the problem of insufficient gas permeability of the base tube for achieving desired power generation characteristics. Under these circumstances, the present invention proposes a base tube for an integral sinter type fuel cell, the base tube having increased porosity and pore diameter to improve the power generation characteristics of the fuel cell.
SUMMARY OF THE INVENTION
The present invention provides a base tube for a fuel cell produced by forming a film of a fuel electrode and a film of an air electrode on a surface of the base tube, the base tube comprising a mixture of a raw material for the base tube, and either coarse particles of the same material as the raw material for the base tube, or a metal oxide, whereby the mixture shrinks nonuniformly when sintered to increase the porosity of the base tube.
The mean particle diameter of the raw material for the base tube maybe 1 &mgr;m, and the mixture may consist of the raw material for the base tube, and the coarse particles having a particle diameter of 5 &mgr;m or more.
The mixture may contain 10 to 40% by weight of the coarse particles.
The raw material for the base tube may be calcia-stabilized zirconia (CSZ).
The raw material for the base tube may be fine particles of calcia-stabilized zirconia (CSZ), and the mixture may consist of the raw material for the base tube, and fine particles of the metal oxide selected from the group consisting of NiO, CoO and FeO, the fine particles of the metal oxide having the same particle diameter as the particle diameter of the raw material for the base tube, whereby the mixture shrinks nonuniformly when sintered to increase the porosity of the base tube.
The mixture may contain 10 to 40% by weight of the fine particles of the metal oxide.
The raw material for the base tube may be calcia-stabilized zirconia (CSZ) having a particle diameter of 1 &mgr;m, and the mixture may consist of the raw material for the base tube, and coarse particles of the metal oxide selected from the group consisting of NiO, CoO and FeO, the coarse particles of the metal oxide having a particle diameter of 5 &mgr;m or more, whereby the mixture shrinks nonuniformly when sintered to increase the porosity of the base tube.
The mixture may contain 10 to 40% by weight of the coarse particles of the metal oxide.


REFERENCES:
patent: 4598028 (1986-07-01), Rossing
patent: 5073405 (1991-12-01), Vasilow
patent: 5108850 (1992-04-01), Carlson
patent: 5244742 (1993-09-01), Zymboly
patent: 5426003 (1995-06-01), Spengler
patent: 5543239 (1996-08-01), Virkar
patent: 5591537 (1997-01-01), Bagger
patent: 5686198 (1997-11-01), Kuo

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