INVESTIGADORES
MALACHEVSKY Maria Teresa
artículos
Título:
SEM investigation of the critical current degradation onset in BSCCO-2223 multifilamentary tapes submitted to bending
Autor/es:
M. T. MALACHEVSKY; C.D'OVIDIO
Revista:
SUPERCONDUCTOR SCIENCE AND TECHNOLOGY
Referencias:
Año: 2005 vol. 18 p. 289 - 293
ISSN:
0953-2048
Resumen:
The applicability of superconducting tapes is evaluated employing the
definition of an irreversibility strain irr, attained at a critical current densityirr, attained at a critical current density
Jc of 98% of its initial value. Before reaching this limit, the Jc decreases
slowly. In order to determine the microstructural changes responsible for
this behaviour, we investigated the mechanical response of 19-filament
BSSCCO-Ag tapes with different ceramic microstructures, when bent
without exceeding irr. After chemically removing a rectangular-shaped area
of the silver sheath to expose the ceramic filaments, the samples were
subjected to three-point bending inside an SEM chamber. Thus, we were
able to follow the microstructural changes produced by the formation and
propagation of cracks at the same time that we recorded on a PC the force
versus deflection curves. We identified three different regions representing
the response of the tapes to increasing bending. After the elastic region, the
pre-existing microstructural faults determined the plastic behaviour. At
higher deflections, we measured several stress drops coincident with the
observation of micro-cracks that grew slowly across the filaments. Twin
samples were employed to control the critical current density decay as a
function of the bending deflection introduced at ambient temperature. We
investigated the correlation between the bending induced defects and the
critical current degradation.c of 98% of its initial value. Before reaching this limit, the Jc decreases
slowly. In order to determine the microstructural changes responsible for
this behaviour, we investigated the mechanical response of 19-filament
BSSCCO-Ag tapes with different ceramic microstructures, when bent
without exceeding irr. After chemically removing a rectangular-shaped area
of the silver sheath to expose the ceramic filaments, the samples were
subjected to three-point bending inside an SEM chamber. Thus, we were
able to follow the microstructural changes produced by the formation and
propagation of cracks at the same time that we recorded on a PC the force
versus deflection curves. We identified three different regions representing
the response of the tapes to increasing bending. After the elastic region, the
pre-existing microstructural faults determined the plastic behaviour. At
higher deflections, we measured several stress drops coincident with the
observation of micro-cracks that grew slowly across the filaments. Twin
samples were employed to control the critical current density decay as a
function of the bending deflection introduced at ambient temperature. We
investigated the correlation between the bending induced defects and the
critical current degradation.irr. After chemically removing a rectangular-shaped area
of the silver sheath to expose the ceramic filaments, the samples were
subjected to three-point bending inside an SEM chamber. Thus, we were
able to follow the microstructural changes produced by the formation and
propagation of cracks at the same time that we recorded on a PC the force
versus deflection curves. We identified three different regions representing
the response of the tapes to increasing bending. After the elastic region, the
pre-existing microstructural faults determined the plastic behaviour. At
higher deflections, we measured several stress drops coincident with the
observation of micro-cracks that grew slowly across the filaments. Twin
samples were employed to control the critical current density decay as a
function of the bending deflection introduced at ambient temperature. We
investigated the correlation between the bending induced defects and the
critical current degradation.