Transport critical currents of Bi(2223) tapes at 77 K under mechanical stress
Transport critical currents of Bi(2223) tapes at 77 K under mechanical stress
复制标题
机械应力下 77 K 下 Bi(2223) 带的传输临界电流
DOI：
10.1109/77.620992
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发表时间：
1997
影响因子：
1.8
通讯作者：
W. Goldacker
中科院分区：
文献类型：
--
作者：
B. Ullmann;A. Gabler;M. Quilitz;W. Goldacker
输运临界电流j/sub c/取决于在j/sub c/-测定期间或之前施加的机械应力。进行了两个不同目的的实验：a)弯曲胶带测试绕组（线圈，电力电缆）的阻力；B)轴向应变试验提供在运行过程中作用在导体上的力的影响的信息。Bi(2223)/Ag带从半径r=/spl infin/弯曲到r=1 cm，轴向应变约为0.2%，可使j/sub c/降低约80%。对于弯曲带和细长带，我们发现j/sub c/的场依赖性几乎不受影响，由于裂纹的形成，这只是在较低的j/sub c/水平上，即渗透路径的减少。采用2% Mg弥散硬化强化护套材料，可避免强j/sub / c/还原。这些改进带弯曲后的j/sub / c/减小幅度仅为20%左右，最大轴向应变容差约为0.8%。增强带的屈服强度为300 ~ 350 MPa，是银包覆带的5倍以上。
The transport critical current, j/sub c/, depends on the mechanical stress applied during or before the j/sub c/-determination. Two experiments with different aims were performed : a) bending of the tape tests the resistance against winding (coils, power cables); b) axial strain tests give information on the effect of forces acting on the conductor during operation. Bending of Bi(2223)/Ag tapes from a radius r=/spl infin/ to r=1 cm as well as an axial strain of about 0.2% decreases j/sub c/ by some 80%. For bent as well as for elongated tapes, we find an almost unaffected field dependence of j/sub c/, which is only on a lower j/sub c/ level due to crack formation, i.e. a reduction of the percolation path. The strong j/sub c/ reduction can be avoided by reinforcement of the sheath material by dispersion hardening with 2% Mg. The j/sub c/ decrease after bending in these improved tapes is only some 20%, the maximum axial strain tolerance about 0.8%. The yield of the reinforced tapes is 300-350 MPa, which is more than 5 times the value for Ag sheathed tapes.