Papers by Keyword: Bi2223

Abstract: The critical current versus tensile strain characteristics of mono- and multi-filament Bi-2223 tapes with Ag and AgMn and AgMg sheath has been studied. The strain tolerance ε0.9 of naked mono- and 37-filament Bi-2223 tapes were 0.13% and 0.20%, respectively. Ag sheath increased the strain tolerance ε0.9 of critical current by 0.08% and 0.16% for mono-filament and 37-filament Bi-2223/Ag tapes. The ε0.9 of Bi-2223 with Ag and AgMn and AgMg sheath increased with filament number. AgMn and AgMg sheath, increasing ε0.9 of Bi-2223 tapes by 0.07-0.09%, are effective to improve strain tolerance of critical current for multifilamentary Bi-2223 tapes.

Abstract: The strain dependence of the critical current, Ic, of Bi2223/Ag/Ag-alloy composite superconducting tapes has been studied both experimentally and analytically under bending deformation for two types of tape used in the VAMAS bending round-robin program (classified as VAM1 and 3). Our former analysis showed that the experimentally obtained Ic values were between the calculated ones based on a damage-free initial state and a case where delamination occupied the full width of the tape mid-plane. The experimentally obtained Ic values were explained by the delamination occupying partial width of the tape mid-plane. However, the microscopic observation indicated that the delamination location in the thickness direction was not limited to the mid-plane. In the present study, the analysis was modified to incorporate the movement of the delamination location in the thickness direction. The calculated Ic values with delamination increased when the delamination location moved to compressive side of the tape, and decreased when that moved to tensile side of the tape. Finally, the experimental Ic values can be understood by the distribution of delamination in both width and thickness direction.

Abstract: Bi-2223/Ag tapes are usually used for superconducting power cables and magnets. Bi- 2223 ceramic superconducting core can be damaged under complicated stress and strain conditions such as winding tension, bending and twisting. In this study, we have presented the effect of axial stress and bending strain on the superconducting properties of Bi-2223/Ag tapes. In order to establish the value for 95% retained Ic of the Bi-2223/Ag tapes under various stress-strain conditions, the tension apparatus with bending former was used to apply the tension and bending stress-strain. Tension and bending stress-strain simultaneously applied to the tapes could reduce the critical current even though each applied stress and strain values were not higher than that of 95% retained Ic of the tapes. Complex stress-strain conditions including the thermal stress-strain have accelerated the degradation of the Bi-223/Ag tapes. The deformation temperature was important to maintain the 95% retained Ic of the Bi-2223/Ag tapes after bending or tension deformation because mechanical strength of the tapes can be changed drastically between room temperature and 77 K.

Abstract: Orientation distributions of polyphased (Bi,Pb)2Sr2Ca2Cu3O10+d superconducting textured materials are determined from neutron diffraction analysis. The quantitative texture analysis of neutron data was accomplished by using the combined Rietveld-WIMV-Popa algorithms, implemented in the program package Materials Analysis Using Diffraction (MAUD). Curved position-sensitive detector and 4-circle diffractometry allow the whole diffraction pattern treatment. Transport critical current densities, measured on different samples, are strongly dependent of the calculated texture strengths, crystallite sizes and phase ratios. The results prove the interest of the combined approach for a quantitative texture analysis of complex materials. Texture to anisotropic physical properties relationship is discussed.