Process to densify Bi2Sr2CaCu2Ox round wire with overpressure before coil winding and final overpressure heat treatment.
Process to densify Bi2Sr2CaCu2Ox round wire with overpressure before coil winding and final overpressure heat treatment.
复制标题
在线圈绕制和最终过压热处理之前，通过过压使 Bi2Sr2CaCu2Ox 圆线致密化的过程。
DOI：
10.1088/1361-6668/ab5ad6
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发表时间：
2020
影响因子：
3.6
通讯作者：
Hellstrom,EE
中科院分区：
文献类型：
--
作者：
Matras,MR;Jiang,J;Trociewitz,UP;Larbalestier,DC;Hellstrom,EE
风-反应bi2sr2cacu2ox（2212）圆丝的超压（OP）处理将丝压缩到几乎满密度，在不改变丝长的情况下将丝直径减小了约4%，并大幅提高了其jc。然而，这种收缩会降低线圈的绕组密度和磁场均匀性。为了解决这个问题，我们在这里提出了在熔化2212之前进行的超压预致密（OP- pd）热处理工艺，该工艺大大减少了全OP热处理（OP- ht）期间的线径收缩率。我们发现，约80%的总线径收缩发生在熔解前的50atm OP-PD过程中。我们成功地将这种1.2毫米直径的预致密线缠绕在直径小至10毫米的ag - mg护套线和5毫米的ag护套线的线圈芯上，即使如此小的直径对导体施加的塑性应变高达12%。在标准的OP-HT期间，进一步发生了约20%的收缩。对于直径小于20 mm的ag - mg护套线和直径为10 mm的ag - mg护套线，没有观察到2212泄漏，并且在直样品和直径为30 mm的线圈上没有观察到J - C降解。
Overpressure (OP) processing of wind-and-react Bi 2 Sr 2 CaCu 2 O x (2212) round wire compresses the wire to almost full density, decreasing its diameter by about 4% without change in wire length and substantially raising its J C. However, such shrinkage can degrade coil winding pack density and magnetic field homogeneity. To address this issue, we here present an overpressure predensification (OP-PD) heat treatment process performed before melting the 2212, which greatly reduces wire diameter shrinkage during the full OP heat treatment (OP-HT). We found that about 80% of the total wire diameter shrinkage occurs during the 50 atm OP-PD before melting. We successfully wound such pre-densified 1.2 mm diameter wires onto coil mandrels as small as 10 mm diameter for Ag–Mg-sheathed wire and 5 mm for Ag-sheathed wire, even though such small diameters impose plastic strains up to 12% on the conductor. A further∼ 20% shrinkage occurred during a standard OP-HT. No 2212 leakage was observed for coil diameters as small as 20 mm for Ag–Mg-sheathed wire and 10 mm for Ag-sheathed wire, and no J C degradation was observed on straight samples and 30 mm diameter coils.