US5055436A
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Method for preparation of superconductor powders
Assignee: CPS Superconductor Corp
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Filing: 1988-08-19
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Granted: 1991-10-08
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Expires: 2008-08-19
Abstract
Abstract An improved process for preparing superconducting ceramic powder includes calcining superconducting precursor compounds in an atmosphere having a controlled amount of oxygen, generally not more than that found in air, the remainder of the atmosphere composed of a gas or mixture of gases inert with respect to the ceramic. A preferred process includes forming the precursor compounds into a slurry, granulating the slurry, drying the granules (a binder can be added to the slurry to promote green strength), and calcining in the controlled atmosphere to provide the desired HTSC (high temperature superconductor) composition.
Inventors
- 👤 Lori J. Klemptner
- 👤 James D. Hodge
- 👤 John W. Halloran
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 10:21
CPC Classifications
H; H10; H10N; H10N60/00; H10N60/01; H10N60/0268; C; C01; C01G; C01G15/00; C01G15/006; C01G29/00; C01G29/006; C01G3/00; C01G3/006; C04; C04B; C04B35/00; C04B35/01; C04B35/45; C04B35/4504; C04B35/4512; C04B35/4521; C01P; C01P2002/00; C01P2002/50; C01P2002/52; C01P2002/54; C01P2002/70; C01P2002/72; C01P2004/00; C01P2004/01; C01P2004/03; Y; Y10; Y10S; Y10S505/00; Y10S505/725; Y10S505/733; Y10S505/737; Y10S505/739
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
91 words
A method for preparing ceramic superconducting powder, comprising the steps of: (a) providing a pourable slurry having 15% to 50% by volume of solids and composed of (i) superconducting precursors, (ii) a binder, (iii) a dispersant, and (iv) a solvent; (b) granulating the slurry by freezing; (c) drying the granules; (d) providing a bed of the granules; (e) calcining the granules while percolating through the bed an atmosphere composed of not more than 20% oxygen and the remainder being an inert gas; and (f) grinding the calcined granules into a powder.
Claim 2
Independent Claim
91 words
A method for preparing ceramic superconducting powder, comprising the steps of: (a) providing a pourable slurry having 15% to 50% by volume of solids and composed of (i) superconducting precursors, (ii) a binder, (iii) a dispersant, and (iv) a solvent; (b) granulating the slurry by freezing; (c) drying the granules; (d) providing a bed of the granules; (e) calcining the granules while percolating through the bed an atmosphere composed of not more than 20% oxygen and the remainder being an inert gas; and (f) grinding the calcined granules into a powder.
Claim 3
Dependent Claim
117 words
The method as defined by claim 1, wherein the superconducting powder is a composition selected from the group consisting of LnM 2 Cu 3 O 7 , (Ln 1-x M x ) 2 CuO 4 , MPb 1-x Bi x O 3 , La 2 CuO 4 , Bi 2 CaSr 2 Cu 2 O 8 , Tl 2 Ba 2 Ca 2 Cu 3 O x , Tl 2 Ba 2 Ca 1 Cu 2 O x , Tl 2 Ba 2 CuO x , and mixtures thereof, wherein 0<x≦0.1, Ln is Y or an element having an atomic number of 57 to 71 or mixtures thereof, and M is Ba, Sr, Ca, or mixtures thereof.
Claim 4
Dependent Claim
31 words
The method as defined by claim 1, wherein the precursor is an oxide, carbide, carbonate, hydroxide, hydride, nitrate, acetate, citrate, peroxide, or mixture thereof, of an element in the superconducting powder.
Claim 5
Dependent Claim
27 words
The method as defined by claim 1, wherein the binder is a polyethylene glycol having a molecular weight within the range of about 200 to about 4600.
Claim 6
Dependent Claim
18 words
The method as defined by claim 1, wherein the dispersant is a polyelectrolytic polyacrylate or a modified alkanolamine.
Claim 7
Dependent Claim
17 words
The method as defined by claim 1, wherein the atmosphere is composed of at least 80% nitrogen.
Claim 8
Dependent Claim
17 words
The method as defined by claim 1, wherein the atmosphere is composed of 1% to 20% oxygen.
Claim 9
Dependent Claim
15 words
The method as defined by claim 1, wherein the calcination temperature is 900° C.±50° C.
Claim 10
Dependent Claim
15 words
The method as defined by claim 8, wherein the calcination temperature is 900° C.±5° C.
Claim 11
Dependent Claim
38 words
The method as defined by claim 8, wherein the ceramic superconducting powder is LnBa 2 Cu 3 O 7-x , wherein 0<x<0.15, and Ln represents an element having an atomic number of 57 to 71 or mixtures thereof.
Claim 12
Dependent Claim
13 words
The method as defined by claim 1, wherein drying is essentially by sublimation.
Claim 13
Dependent Claim
15 words
The method as defined by claim 1, further comprising the step of milling the slurry.
Claim 14
Dependent Claim
21 words
The method as defined by claim 1, wherein the precursors have an average particle size of less than about 2 microns.
Claim 15
Dependent Claim
22 words
The method as defined by claim 1, wherein the granules have an average size of between about 1/2 mm and 5 mm.
Claim 16
Dependent Claim
21 words
The method as defined by claim 1, wherein the inert gas is nitrogen, helium, neon, argon, krypton, xenon, or mixtures thereof.
Claim 17
Dependent Claim
21 words
The method as defined by claim 1, further comprising the step of cooling the calcined granules in air prior to grinding.
References Cited (Backward Citations)
US2893102A
Cited
US4049789A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1994-10-07 | 1995-04-08 | 1995-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-10-07 | 1999-04-08 | 1999-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-10-07 | 2003-04-08 | 2003-10-08 | $7700.00 | Window Closed / Lapsed |