The fabrication, thermomechanical processing and characterisation of high temperature superconducting Bi-2212 tapes for applications
The fabrication, thermomechanical processing and characterisation of high temperature superconducting Bi-2212 tapes for applications
The design and construction of High Temperature Superconducting (HTSC) devices requires long lengths of tape, high critical current densities (Jc), and good mechanical characteristics. This work focuses on two areas; firstly the influence of the heat treatment parameters on Jc, and secondly the bending strain tolerance of Bi-2212 and Bi-2223 tapes.
Bi-2212 tapes have been partially melt processed using a fast final cooling schedule in a purpose built water cooled furnace in oxygen atmosphere. The Jc77K of both AgMg-sheathed multifilamentary and Ag-sheathed monocore tapes is observed to increase dramatically with a final cooling rate of 800°C/hr. This increase is attributed to the lower oxygen content of fast cooled samples and the consequent effect on Tc.
The bend strain dependence of the transport critical current Ic has been studied for Bi-2212 and Bi-2223 multifilament tapes at 77K, 65K and 4.2K. Two methods are described for producing the bend strain. The first, an in-situ cold bend at the measurement temperature; and the second an ex-situ warm bend where samples are bent at room temperature and then cooled for transport measurements. The differences between the two measurements are discussed, as is the dependence of the bending strain characteristic on the measured temperature. Optical and SEM investigations of the microstructure of bent tapes are presented.
40%wt silver added Bi-2212 monocore tapes have been fabricated and the details of the manufacture and processing are presented. The addition of large (45-125μm) silver particles into the precursor powder resulted in a novel core configuration. These silver particles flattened upon rolling, producing a connected system of core filaments, yielding a high Jc in comparison to a non-silver added monocore control tape. The silver added tapes showed bend strain tolerance characteristics comparable with multifilament tapes, with the advantage of a single production step. Optical and SEM micrographs are presented of both standard monocore Bi-2212 and the silver added tapes under bending.
University of Southampton
Dudley, Richard Anthony
1f8a7baf-7d94-48d2-9140-c35286aee809
2004
Dudley, Richard Anthony
1f8a7baf-7d94-48d2-9140-c35286aee809
Dudley, Richard Anthony
(2004)
The fabrication, thermomechanical processing and characterisation of high temperature superconducting Bi-2212 tapes for applications.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The design and construction of High Temperature Superconducting (HTSC) devices requires long lengths of tape, high critical current densities (Jc), and good mechanical characteristics. This work focuses on two areas; firstly the influence of the heat treatment parameters on Jc, and secondly the bending strain tolerance of Bi-2212 and Bi-2223 tapes.
Bi-2212 tapes have been partially melt processed using a fast final cooling schedule in a purpose built water cooled furnace in oxygen atmosphere. The Jc77K of both AgMg-sheathed multifilamentary and Ag-sheathed monocore tapes is observed to increase dramatically with a final cooling rate of 800°C/hr. This increase is attributed to the lower oxygen content of fast cooled samples and the consequent effect on Tc.
The bend strain dependence of the transport critical current Ic has been studied for Bi-2212 and Bi-2223 multifilament tapes at 77K, 65K and 4.2K. Two methods are described for producing the bend strain. The first, an in-situ cold bend at the measurement temperature; and the second an ex-situ warm bend where samples are bent at room temperature and then cooled for transport measurements. The differences between the two measurements are discussed, as is the dependence of the bending strain characteristic on the measured temperature. Optical and SEM investigations of the microstructure of bent tapes are presented.
40%wt silver added Bi-2212 monocore tapes have been fabricated and the details of the manufacture and processing are presented. The addition of large (45-125μm) silver particles into the precursor powder resulted in a novel core configuration. These silver particles flattened upon rolling, producing a connected system of core filaments, yielding a high Jc in comparison to a non-silver added monocore control tape. The silver added tapes showed bend strain tolerance characteristics comparable with multifilament tapes, with the advantage of a single production step. Optical and SEM micrographs are presented of both standard monocore Bi-2212 and the silver added tapes under bending.
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Published date: 2004
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Local EPrints ID: 465433
URI: http://eprints.soton.ac.uk/id/eprint/465433
PURE UUID: 337de831-5f40-428f-acd2-85f645faa950
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Date deposited: 05 Jul 2022 00:58
Last modified: 16 Mar 2024 20:10
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Author:
Richard Anthony Dudley
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