Liquid phase sintered superconducting cermet
AssigneeAluminum Company of America
InventorSiba P. Ray
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Abstract
Disclosed is a cermet exhibiting superconducting properties with improved mechanical properties comprising a mixture of a superconducting ceramic and one or more metals, the cermet resulting from liquid phase sintering at a temperature at which one of the metals is molten and below the melting temperature of the superconducting ceramic.
Claims10
A method of making a super-conducting cermet having superconducting properties with improved bulk density, low porosity and in situ stabilization comprising the steps of:
- (a) forming a structure of
- (i) a superconducting ceramic material having the formula RM.sub.2 Cu.sub.3 O.sub.(6.5+x) wherein R is one or more rare earth elements capable of reacting to form a superconducting ceramic, M is one or more alkaline earth metal elements selected from barium and strontium capable of reacting to form a superconducting ceramic, x is greater than 0 and less than 0.5;
- and
- (ii) a precious metal compound in solid form selected from the class consisting of oxides, sulfides and halides of silver;
- and
- (b) liquid phase sintering the mixture at a temperature wherein the precious metal of the precious metal compound is molten and below the melting point of said ceramic material, the liquid phase sintering carried out for a time less than 36 hours but sufficient to improve the bulk density of the cermet.
The method in accordance with claim 2 including annealing said sintered mixture at a temperature of from about 650.degree. to 750.degree. C. in an oxygen-containing atmosphere for from about 12 to 36 hours.
The method in accordance with claim 7 wherein said sintered ceramic material is comminuted into -100 mesh (Tyler) particles and the process steps of claim 8 are repeated at least one more time.
A method of making a superconducting cermet having superconducting properties with improved bulk density and low porosity comprising the steps of:
- (a) forming a powder mixture of:
- (i) a -100 mesh (Tyler) superconducting ceramic powder material having the formula YBa.sub.2 Cu.sub.3 O.sub.(6.5+x) wherein x is greater than 0 and less than 0.5;
- and
- (ii) a -100 mesh (Tyler) silver-bearing powder material selected from the group consisting of the oxide, sulfide, or halide of silver;
- (b) liquid phase sintering the mixture at a temperature in the range of about 960.degree. to 990.degree. C. to provide a molten silver phase and at a temperature below the melting of the superconducting ceramic, the liquid phase sintering carried out for a time less than 36 hours but sufficient to improve the bulk density of the cermet;
- and
- (c) annealing said sintered mixture at a temperature of from about 650.degree. to 750.degree. C. in an oxygen-containing atmosphere for from about 12 to 36 hours.
Dependencies are inferred from the claim text.