Claims
- 1. A method of forming a combustible polymer film containing a thin layer of doped LaCrO.sub.3 particles, comprising the steps:
- (1) providing LaCrO.sub.3 particles doped with an element selected from the group consisting of Ca, Sr, Co, Ba, Mg, and mixtures thereof;
- (2) uniformly dispersing the particles in a solvent to provide a homogeneous dispersion;
- (3) wet screening the dispersion to provide particles in the range of from 30 micrometers to 80 micrometers;
- (4) admixing a fugitive polymer with the particles in an amount to provide homogeneous dispersion with a volume ratio of polymer plus particles:solvent of between 50:50 and 30:70 and a volume ratio of polymer:particles between 65:35 and 50:50;
- (5) casting the dispersion onto a substrate, to provide a film having a wet thickness of from 80 micrometers to 150 micrometers;
- (6) drying the film; and
- (7) stripping the film from the substrate, to provide a particle-fugitive polymer film.
- 2. The method of claim 1, where the fugitive polymer is in all cases a thermoplastic polymer which will vaporize at less than 1,100.degree. C.
- 3. The method of claim 1, where the fugitive polymer is selected from the group consisting of acrylic polymers, polyvinyl chloride polymers, and polystyrene-polymers.
- 4. The method of claim 1, where the solvent in step (2) contains an effective amount of a dispersing aid, where, between steps (3) and (4), the particles are rinsed with solvent and dried, and where the particles screened in step (3) are within a narrow size range within the 30 micrometer to 80 micrometer range.
- 5. The method of claim 1, where the stripped film is flexible and has a thickness of from 30 micrometers to 80 micrometers, and the particles are essentially in a monolayer.
- 6. The method of claim 1, where the particles are LaCrO.sub.3 doped with dopants selected from the group consisting of Co plus Sr, and Co plus Ba.
- 7. The method of claim 1, where the particles are selected from the group having the approximate chemical formulas of La.sub.0.89 Sr.sub.0.1 Co.sub.0.1 Cr.sub.0.9 O.sub.3 and La.sub.0.94 Ba.sub.0.05 Co.sub.0.1 Cr.sub.0.9 O.sub.3.
- 8. The method of claim 1, where the combustible polymer film is applied on a porous portion of a first surface of an electrode structure which is preheated to from 30.degree. C. to 80.degree. C. above the glass transition temperature of the fugitive polymer, while applying a vacuum on the opposite surface of the electrode structure, and then electrochemical vapor depositing a dense skeletal structure comprising LaCrO.sub.3, between and around the doped LaCrO.sub.3 particles, where, during initial heating the fugitive binder volatilizes.
- 9. The method of claim 8, wherein the electrode structure is a porous, tubular cathode of doped LaMnO.sub.3, and where a protective fugitive polymer film is applied on top of the particle-fugitive polymer film before electrochemical vapor deposition, which top fugitive polymer film is also volatilized during initial heating.
- 10. The method of claim 8, where solid oxide electrolyte is applied over the remaining portion of the air electrode surface and a cermet fuel electrode is applied over the electrolyte, to provide an electrochemical cell.
- 11. A method of bonding a dense, high temperature electronically conductive layer on an electrode structure comprising the steps:
- (A) applying a thin particle-fugitive polymer film, having essentially a monolayer of LaCrO.sub.3 particles doped with an element selected from the group consisting of Ca, Sr, Co, Ba, Mg, and mixtures thereof, on a porous portion of a first surface of an electrode structure which is preheated to from 30.degree. C. to 80.degree. C. above the glass transition temperature of the fugitive polymer, while applying a vacuum on the opposite surface of the electrode structure, and then
- (B) electrochemical vapor depositing a dense skeletal structure comprising LaCrO.sub.3, between and around the doped LaCrO.sub.3 particles, where, during initial heating to vapor deposit, the fugitive polymer volatilizes, and where the particles get incorporated into the lanthanum chromium oxide structure as it grows thicker with time, to provide a dense, high temperature electronically conductive interconnection layer on the porous electrode structure.
- 12. The method of claim 11, where the electrode structure is a porous, tubular cathode of doped LaMnO.sub.3, and where a protective fugitive polymer film is applied on top of the particle-fugitive polymer film before electrochemical vapor deposition, which top fugitive polymer film is also volatilized during initial heating.
- 13. The method of claim 11, where the fugitive polymer is in all cases a thermoplastic polymer which will vaporize at less than 1,100.degree. C., the particle-fugitive binder film has a thickness of from 30 micrometers to 80 micrometers with the particles essentially in a monolayer, and the particles are LaCrO.sub.3 doped with an element selected from the group consisting of Ca, Sr, Co, Ba, Mg, and mixtures thereof.
- 14. The method of claim 11, where solid oxide electrolyte is applied over the remaining portion of the air electrode surface and a cermet fuel electrode is applied over the electrolyte, to provide an electrochemical cell.
- 15. The method of claim 11, where, by appropriately choosing the dopant concentration in the particles and the amount of particles to be incorporated in the interconnection, the thermal expansion of the final interconnection can be tailored to match all other components of the electrochemical cell.
GOVERNMENT CONTRACT
The Government of the United States of America has rights in this invention pursuant to Contract No. DE-AC-0280-ET-17089, awarded by the U.S. Department of Energy.
US Referenced Citations (9)