Preparing superconducting ceramic materials
This patent describes the process of fabricating superconducting ceramic bodies comprising {gt}99 percent YBa{sub 2}Cu{sub 3}O{sub 7}. It comprises wet milling an aqueous slurry comprising selected proportions of starting ingredients comprising yttrium oxide, barium carbonate and cupric oxide in an approximately 1:2:3 molar ratio to form a milled slurry, the aqueous slurry including a binder, a defoaming agent and a dispersant, continuously agitating the milled slurry after the wet milling step so as to avoid non-uniform sedimentation of starting ingredients in the slurry, spray drying the milled slurry into particulate material, calcining the spray dried particulate material to produce a calcined powder, the calcining step comprising ramping the temperature within a calcining furnace containing the spray dried particulate material to 900{degrees}C in 4 hours, soaking the particulate matter at 900{degrees}C for a period of 24 hours and, thereafter, ramping the temperature to about 450{degrees}C in about 4 hours, the calcined powder comprising {ge}95 percent YBa{sub 2}Cu{sub 3}O{sub 7}, forming the calcined powder into a body having a desired form, and sintering the body, the sintering including the steps comprising ramping the temperature of a sintering furnace to 900{degrees}C in 2 hours, ramping the temperature from 900{degrees} to 975{degrees}C in 6 hours, soaking the body at 975{degrees}C for 6 hours, ramping the temperature from 975{degrees}C to 450{degrees}C in 1 hour, soaking the body at 450{degrees}C for 4 hours, and ramping the temperature from 450{degrees}C to room temperature in 1 hour.
- Assignee:
- AT and T Bell Lab., Murray Hill, NJ (USA)
- Patent Number(s):
- A; US 5006504
- Application Number:
- PPN: US 7-399649
- OSTI ID:
- 5097935
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CALCINATION
CERAMICS
CHALCOGENIDES
CHEMICAL REACTIONS
COPPER COMPOUNDS
COPPER OXIDES
DECOMPOSITION
FABRICATION
MACHINING
MILLING
OXIDES
OXYGEN COMPOUNDS
PYROLYSIS
SINTERING
SUPERCONDUCTORS
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES