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Patent US4892861A successfully refreshed from Google Patents.
US4892861A
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Liquid phase sintered superconducting cermet
Assignee: Alcoa Corp
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Filing: 1987-08-14
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Granted: 1990-01-09
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Expires: 2007-08-14
Abstract
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.
Inventors
- 👤 Siba P. Ray
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 00:15
CPC Classifications
C; C22; C22C; C22C29/00; C22C29/12; B; B22; B22F; B22F3/00; B22F3/001; H; H10; H10N; H10N60/00; H10N60/80; H10N60/85; H10N60/855; H10N60/857; Y; Y10; Y10S; Y10S505/00; Y10S505/775; Y10S505/785
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
164 words
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 2 Cu 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.
Claim 2
Independent Claim
164 words
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 2 Cu 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.
Claim 3
Dependent Claim
33 words
The method in accordance with claim 2 including annealing said sintered mixture at a temperature of from about 650° to 750° C. in an oxygen-containing atmosphere for from about 12 to 36 hours.
Claim 4
Dependent Claim
15 words
The method in accordance with claim 1 wherein the precious metal compound contains silver oxide.
Claim 5
Dependent Claim
23 words
The method in accordance with claim 1 wherein the superconducting ceramic material is in powder form having a mesh size of -100 (Tyler).
Claim 6
Dependent Claim
23 words
The method in accordance with claim 1 wherein the precious metal compound is in powder form having a mesh size of -100 (Tyler).
Claim 7
Dependent Claim
24 words
The method in accordance with claim 1 wherein said sintering step is carried out at a temperature of from about 960 to 1000° C.
Claim 8
Dependent Claim
89 words
The method in accordance with claim 6 wherein said superconducting ceramic is formed by sintering a mixture of one or more rare earth-bearing materials, one or more alkaline earth metal-bearing materials, and a copper-bearing material in the presence of oxygen at a temperature of from about 900° to 1000° C. for a period of from about 12 to about 36 hours followed by an annealing step conducted for from about 12 to 36 hours at a temperature of from about 650° to about 750° C. in an oxygen-bearing atmosphere.
Claim 9
Dependent Claim
33 words
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.
Claim 10
Independent Claim
161 words
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 2 Cu 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° to 990° 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° to 750° C. in an oxygen-containing atmosphere for from about 12 to 36 hours.
Claim 11
Independent Claim
161 words
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 2 Cu 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° to 990° 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° to 750° C. in an oxygen-containing atmosphere for from about 12 to 36 hours.
Claim 12
Dependent Claim
32 words
The method in accordance with claim 1 including hot working said cermet, said hot working and liquid phase sintering capable of producing a bulk density of greater than 97% of theoretical density.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-01-08 | 1993-07-10 | 1994-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-08 | 1997-07-10 | 1998-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-08 | 2001-07-10 | 2002-01-09 | $7700.00 | Window Closed / Lapsed |