Method of coating a substrate with a metal oxide film from an aqueous solution comprising a metal cation and a polymerizable organic solvent
AssigneeThe Curators of the University of Missouri
InventorsHarlan U. Anderson, Magdi M. Nasrallah, Chieh-Cheng Chen
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Abstract
A method for preparing a substrate coated with a polycrystalline, metal oxide film using polymeric precursors. The oxide films prepared by the method of the present invention are dense (i.e., substantially free of cracks and pinholes) and may be used, for example, as an electrolyte or electrode in intermediate temperature solid oxide fuel cells (SOFCs) or as gas separation membranes.
Claims16
A method for preparing a component for a solid oxide fuel cell comprising a substrate coated with a polycrystalline metal oxide film, the oxide film being comprised of an oxide selected from the group consisting of (CeO.sub.2).sub.1-x (SmO.sub.1.5).sub.x, (ZrO.sub.2).sub.1-x (YO.sub.1.5).sub.x, La.sub.1-x Sr.sub.x MnO.sub.3 and La.sub.1-x Sr.sub.x Co.sub.y Fe.sub.1-y O.sub.3, wherein x and y are between 0 and 1 and are selected to represent the nominal composition of the oxide film, the method comprising:
- preparing a precipitate-free starting solution by dissolving metal cation source compounds for each of the metal constituents of the oxide film in an aqueous mixture comprising a polymerizable organic solvent, the cations of each metal being present in the starting solution in a molar ratio corresponding to the nominal composition of the oxide film;
- heating the starting solution to form a polymeric precursor comprising a polymer containing the metal cations, the precursor being free of precipitates;
- depositing the polymeric precursor onto a surface of the substrate;
- spinning the substrate to thereby coat the substrate with a film of the polymeric precursor;
- and
- calcining the deposited film of polymeric precursor in the presence of oxygen and at a temperature not in excess of 600.degree. C. to convert the film of polymeric precursor into the polycrystalline metal oxide film, the oxide film having an average grain size less than about 0.5 .mu.m and being substantially free of cracks or pinholes.
A method for preparing a gas separation membrane for selectively transferring a component of a gaseous mixture across the membrane, the membrane comprising a polycrystalline metal oxide film, the method comprising:
- preparing a precipitate-free starting solution by dissolving at least one metal cation source compound in an aqueous mixture comprising a polymerizable organic solvent;
- heating the starting solution to form a polymeric precursor comprising a polymer containing the metal cations, the precursor being free of precipitates;
- depositing a film of the polymeric precursor onto a surface of a porous substrate, the porosity of the substrate being sufficient to allow transport of the selected component of the gas mixture across the membrane;
- and
- calcining the deposited film of polymeric precursor in the presence of oxygen to convert the film of polymeric precursor into the polycrystalline metal oxide film, the oxide film being substantially free of cracks or pinholes.
A method for preparing a gas separation membrane for selectively transferring oxygen from a gaseous mixture across the membrane, the membrane comprising a polycrystalline metal oxide film of (ZrO.sub.2).sub.1-x (YO.sub.1.5).sub.x or La.sub.1-x Sr.sub.x Co.sub.y Fe.sub.1-y O.sub.3, wherein x and y are between 0 and 1 and are selected to represent the nominal composition of the oxide, the method comprising:
- preparing a precipitate-free starting solution by dissolving source compounds for cations of Zr and Y or La, Sr, Co and Fe in an aqueous mixture comprising a polymerizable organic solvent;
- heating the starting solution to form a polymeric precursor comprising a polymer containing the metal cations, the precursor being free of precipitates;
- depositing a film of the polymeric precursor onto a surface of a porous substrate, the porosity of the substrate being sufficient to allow transport of oxygen across the substrate/membrane boundary;
- and
- calcining the deposited film of polymeric precursor in the presence of oxygen to convert the film of polymeric precursor into the polycrystalline metal oxide film, the oxide film being substantially free of cracks or pinholes.
Dependencies are inferred from the claim text.