Manufacturing method for ceramics and products thereof
AssigneeW. R. Grace & Co.-Conn.
InventorsNicholas D. Spencer, Wie-Hin Pan, John A. Rudesill
Life of this patent
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Abstract
An extremely pure oxide containing two or more metals, homogeneous at the atomic level, is prepared by (1) reacting in water, soluble salts of two or more metals with quaternary ammonium carbonate; the metals being those that form water-insoluble carbonates, thereby to precipitate mixed carbonates of the metals; (2) recovering and drying the precipitate; (3) calcining the precipitate to provide an oxide of mixed metals homogeneous at the atomic level and substantially free from extraneous contaminants. The calcined oxide can be shaped and compressed as greenware and sintered to form useful ceramic products.
Claims26
Aqueous slurry consisting essentially of a homogeneous dispersion of a co-precipitate of at least two metal carbonates and quaternary ammonium salts.
Aqueous slurry consisting essentially of homogeneous dispersion of L.M.A carbonates and quaternary ammonium salts, where L is at least one trivalent metal, M is at least one bivalent metal, and A is at least one metal of multiple valency.
Process comprising reacting in aqueous medium at a pH of about 7.7-10.0, carbonate ions from quaternary ammonium carbonate with ions of at least two metals that form water-insoluble carbonates, thereby to form a slurry comprising co-precipitates of the respective metal carbonates, homogeneous at the atomic level, and substantially free of extraneous materials.
Process comprising reacting in aqueous medium, carbonate ions from quaternary ammonium carbonate, with L.M.A metal ions and anions thereby to form a slurry comprising precipitates of the respective metal carbonates, and recovering and drying the precipitates;
- the precipitate is heated to a temperature sufficient to decompose or otherwise volatilize any remaining quaternary ammonium and anions and to achieve partial conversion of carbonates in the co-precipitate to oxides;
- L being at least one trivalent metal, M being at least one bivalent metal, and A being at least one metal of multiple valency;
- and L, M, and A being present in a predetermined atomic ratio for a superconductor.
Process, calcining in oxygen a mixture of co-precipitated metal carbonates which has been heated to convert the carbonates at least partially to oxide, said calcining proceeding in accordance with the following schedule:
- (1) Heat to about 975.degree. C. in about 6 hours;
- (2) Hold at about 975.degree. C. for about 10 hours;
- (3) Cool to about 650.degree. C. in about 3 hours;
- (4) Cool from about 650.degree. C. to about 250.degree. C. in about 8 hours;
- and then
- (5) Discontinue heating.
Dependencies are inferred from the claim text.