A study of the heat treatment time, temperature and ramp rate on the transport current properties and Bi-2223 grain growth in (Bi,Pb)2223/Ag superconducting tapes
A study of the heat treatment time, temperature and ramp rate on the transport current properties and Bi-2223 grain growth in (Bi,Pb)2223/Ag superconducting tapes
The Bi-2223 phase formation in (Bi, Pb)2223/Ag tapes is known to be via a Pb rich liquid phase, the control of the wetting properties and the phase volume of liquid phase in the early hours of sintering can substantially improve the transport current of the final sintered tape. The phase volume of liquid phase, characterised by the formation of the Bi2(Sr1.6Ca0.4)CuO6, (Bi-2201), phase, was observed to depend on the heat treatment temperature and atmosphere. The volume of secondary phases, (Cu2O, Cu-free phase, and Bi2(Sr1.6Ca0.4)CuO6), in the sintered Bi-2223 microstructure is shown to be sensitive to the sintering heating rate, and this is thought to be related to the wetting properties of the liquid phase. For an optimum transport critical current, (77K, self-field), the heat treatment temperature and the heating rate are inter-dependent parameters, the heating rate only increasing the transport current of tapes heat treated between 822oC and 852oC, (in 7.5% partial pressure O2/balance Ar. A model is proposed to explain the influence of the temperature and ramp rate on the grain growth and secondary phase formation by a liquid phase sintering mechanism.
The influence of the heat treatment time on the Transport Current of the tapes was seen to give a broad maximum Ic that saturated with long heat treatment time. XRD analysis of the tape found that the conversion to (Bi, Pb)2223 occurs slower in some filaments than others. The cause of the difference was put down to the rolling process which causes the aspect ratio and the density of the filaments to vary.
University of Southampton
Young, Edward A
f488c39c-a3b1-4791-9d96-ded4e714ba8d
2002
Young, Edward A
f488c39c-a3b1-4791-9d96-ded4e714ba8d
Young, Edward A
(2002)
A study of the heat treatment time, temperature and ramp rate on the transport current properties and Bi-2223 grain growth in (Bi,Pb)2223/Ag superconducting tapes.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The Bi-2223 phase formation in (Bi, Pb)2223/Ag tapes is known to be via a Pb rich liquid phase, the control of the wetting properties and the phase volume of liquid phase in the early hours of sintering can substantially improve the transport current of the final sintered tape. The phase volume of liquid phase, characterised by the formation of the Bi2(Sr1.6Ca0.4)CuO6, (Bi-2201), phase, was observed to depend on the heat treatment temperature and atmosphere. The volume of secondary phases, (Cu2O, Cu-free phase, and Bi2(Sr1.6Ca0.4)CuO6), in the sintered Bi-2223 microstructure is shown to be sensitive to the sintering heating rate, and this is thought to be related to the wetting properties of the liquid phase. For an optimum transport critical current, (77K, self-field), the heat treatment temperature and the heating rate are inter-dependent parameters, the heating rate only increasing the transport current of tapes heat treated between 822oC and 852oC, (in 7.5% partial pressure O2/balance Ar. A model is proposed to explain the influence of the temperature and ramp rate on the grain growth and secondary phase formation by a liquid phase sintering mechanism.
The influence of the heat treatment time on the Transport Current of the tapes was seen to give a broad maximum Ic that saturated with long heat treatment time. XRD analysis of the tape found that the conversion to (Bi, Pb)2223 occurs slower in some filaments than others. The cause of the difference was put down to the rolling process which causes the aspect ratio and the density of the filaments to vary.
This record has no associated files available for download.
More information
Published date: 2002
Identifiers
Local EPrints ID: 464704
URI: http://eprints.soton.ac.uk/id/eprint/464704
PURE UUID: 5ced1e25-03a3-4d75-8eeb-0f9c344eae6b
Catalogue record
Date deposited: 04 Jul 2022 23:57
Last modified: 04 Jul 2022 23:57
Export record
Contributors
Author:
Edward A Young
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics