Critical current of laminated and non-laminated BSCCO superconducting composite tape under bending strain

Abstract

a b s t r a c tIt has been reported that, when the (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O x (hereafter noted as BSCCO)/Ag/Ag-alloy tape is laminated with stainless steel, the tensile strain tolerance of critical current is much improved. In this study, using the non-laminated and laminated BSCCO composite tapes fabricated at American Superconductor Corporation, the influences of lamination on the critical current and its distribution under bending strain were studied. The analysis of the measured variation of average critical current with bending strain based on the damage evolution model revealed that the laminated stainless steel acts to suppress the fracture of the BSCCO filaments. The experimentally observed high critical current retention of the laminated tape up to high bending strain was accounted for by the suppression of fracture of BSCCO filaments stated above and enhancement of the compressive residual strain in the filaments. The distributions of local critical current in non-laminated and laminated composite tape were described well by the three-parameter Weibull distribution function within the bending strain lower than 1.1%. The coefficient of variation of distribution of critical current of the laminated tape was similar to that of the non-laminated one under the same strain distribution in the core.

Effect of fatigue loading on critical current in stainless steel–laminated DI-BSCCO superconducting composite tape

“…3 compares the relationship between the stress and strain at 77 K, and that between the normalized critical current at the tively. These values correspond well with previously reported results where the fracture strain of the filament almost doubled owing to lamination [9][10][11]. In the next section, the maximum fatigue stress for SUS3ply tapes is selected according to the irreversible stress under the loading step, r l,irr95% , of 342 MPa, and that under the unloading step, r u,irr99% , of 315 MPa.…”

“…It is also reported that the lamination suppresses the fracture of Bi2223 filaments. Consequently, the fracture strain of Bi2223 filaments in the laminated composite tapes is twice as much as that of filaments in the non-laminated composite tapes [9][10][11].…”

Analysis of critical current fluctuations as a means of checking the quality of high-temperature superconductor tape slitting

“…During the search for the cause of lower local I c values, two main mechanisms were identified in the investigations carried out by various groups: a weakening of vortex pinning in the superconducting layer, and a reduction of its cross-section [21][22][23][24][25][26]. If the properties of the superconducting material vary, the power-law exponent, n, is expected to fluctuate along the tape length [27][28][29].…”