Patents

Patent No. US 6117807 A

Alkali-metal-β- and β"-alumina and gallate polycrystalline ceramics and fabrication by a vapor phase method.

ABSTRACT: A ceramic composite containing alkali-metal-β"- or β"-alumina and an oxygen-ion conductor is fabricated by converting α"-alumina to alkali-metal-β- or β"-alumina. A ceramic composite with continuous phases of α-alumina and the oxygen-ion conducting ceramic, such as zirconia, is exposed to a vapor containing an alkali-metal oxide, such as an oxide of sodium or potassium. Alkali metal ions diffuse through alkali-metal-β- or β"-alumina converted from α-alumina and oxygen ions diffuse through the oxygen-ion conducting ceramic to a reaction front where α-alumina is converted to alkali-metal-β- or β"-alumina. A stabilizer for alkali-metal-β"-alumina is preferably introduced into the α-alumina/oxygen-ion conductor composite or introduced into the vapor used to convert the α-alumina to an alkali-metal-β"-alumina.

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Patent No. US 6168745 B1

Method for forming t'-phase zirconia for high temperature applications

ABSTRACT: A t′-phase zirconia shapes with superior properties are made by forming a zirconia powder containing a rare-earth-oxide dopant into sintered bodies. The sintered bodies are heat treated in an oxygen atmosphere at a temperature high enough to form a cubic phase. The heated body is then cooled rapidly to form a t′-phase. The t′-phase is characterized with a large grain size, is resistant to transformation, low temperature degradation, and has excellent toughness, and creep resistance. Rare earth-oxide dopants include yttria, scandia, erbia, and ceria. For yttria doped materials, the sintered body is doped with between 2.5 and 5 mole percent yttria.

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Patent No. US 6284692 B1

Ceramic of zirconia and rare earth oxide

ABSTRACT: A t′-phase zirconia shapes with superior properties are made by forming a zirconia powder containing a rare-earth-oxide dopant into sintered bodies. The sintered bodies are heat treated in an oxygen atmosphere at a temperature high enough to form a cubic phase. The heated body is then cooled rapidly to form a t′-phase. The t′-phase is characterized with a large grain size, is resistant to transformation, low temperature degradation, and has excellent toughness, and creep resistance. Rare earth-oxide dopants include yttria, scandia, erbia, and ceria. For yttria doped materials, the sintered body is doped with between 2.5 and 5 mole percent yttria.

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Patent No. US 6537940 B1

Alkali-metal-β"- and β″-alumina and gallate polycrystalline ceramics and fabrication by a vapor phase method

ABSTRACT: A ceramic composite containing alkali-metal-β"- or β″-alumina and an oxygen-ion conductor is fabricated by converting α-alumina to alkali-metal-β- or β″-alumina. A ceramic composite with continuous phases of α-alumina and the oxygen-ion conducting ceramic, such as zirconia, is exposed to a vapor containing an alkali-metal oxide, such as an oxide of sodium or potassium. Alkali metal ions diffuse through alkali-metal-β- or β″-alumina converted from α-alumina and oxygen ions diffuse through the oxygen-ion conducting ceramic to a reaction front where α-alumina is converted to alkali-metal-β- or β″-alumina. A stabilizer for alkali-metal-β″-alumina is preferably introduced into the α-alumina/oxygen-ion conductor composite or introduced into the vapor used to convert the α-alumina to an alkali-metal-β″-alumina.

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Patent No. US 6632763 B2

Alkali-metal-beta-and beta″-alumina and gallate polycrystalline ceramics and fabrication by a vapor phase method

ABSTRACT: A ceramic composite containing alkali-metal-beta"- or beta″-alumina and an oxygen-ion conductor is fabricated by converting alpha-alumina to alkali-metal-beta- or beta″-alumina. A ceramic composite with continuous phases of alpha-alumina and the oxygen-ion conducting ceramic, such as zirconia, is exposed to a vapor containing an alkali-metal oxide, such as an oxide of sodium or potassium. Alkali metal ions diffuse through alkali-metal-beta- or beta″-alumina converted from α-alumina and oxygen ions diffuse through the oxygen-ion conducting ceramic to a reaction front where alpha-alumina is converted to alkali-metal-beta- or beta″-alumina. A stabilizer for alkali-metal-beta″-alumina is preferably introduced into the α-alumina/oxygen-ion conductor composite or introduced into the vapor used to convert the alpha-alumina to an alkali-metal-beta″-alumina.

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Patent No. US 6770395 B2

Comprising a tri-layer structure of anode, electrolyte and cathode, are series-connected to a bipolar plate, also referred as interconnect, which is impervious to ensure that fuel and air do not mix, excellent electroconductor

ABSTRACT: A metallic interconnect for use in planar solid oxide fuel cell (SOFC) stacks with metal gauzes disposed in border pieces at the cathodes and anodes providing the electrical conduction between the cell and an interconnect foil and also providing structure for directing gas across the cell surface.

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