LaCrO.sub.3 electrodes and method of manufacture
AssigneeGeneral Refractories Company
InventorsRonald Staut, Peter E. D. Morgan
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Abstract
A technique of forming electrodes for magneto-hydrodynamic generators having the composition (La.sub.1.sub.-x Y.sbsb.x ) CrO.sub.3 where Y is strontium, calcium or magnesium and having densities of as high as 97% of theoretical or even higher is provided. Electrodes of such densities offer superior mechanical and electrical properties when employed in magneto-hydrodynamic generators.
Claims4
A method for producing an electrode body having the composition (La.sub.1.sub.-x Sr.sub.x) CrO.sub.3, (La.sub.1.sub.-x Ca.sub.x) CrO.sub.3, (La.sub.1.sub.-x Mg.sub.x) CrO.sub.3, or La.sub.1 Mg.sub.x Cr.sub.1.sub.-x O.sub.3, where x = 0 to 0.3, and a density in excess of 90% of theoretical, comprising the steps of:
- a. forming an aqueous solution of chromic acid, and reacting lanthanum oxide and strontium, calcium or magnesium carbonate or hydroxides or oxides in proportions to provide the aforesaid composition;
- drying said thick slurry to a dry cake;
- c. calcining said dry cake to a temperature of about 1000.degree. to 1600.degree.C.;
- d. grinding the calcined cake to a powder of particle size of less than about 100 mesh;
- e. forming said powder to an electrode-shape;
- and
- f. firing said electrode shape in an oxidizing atmosphere to a temperature of about 1500.degree. to 2300.degree.C.
Dependencies are inferred from the claim text.