Influence of the wire diameter, filament size and interval Ag space on the processing window of Bi-2212 wires
Influence of the wire diameter, filament size and interval Ag space on the processing window of Bi-2212 wires
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DOI：
10.1007/s10854-023-10193-4
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发表时间：
2023-03
期刊：
影响因子：
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通讯作者：
Zhenbao Li;Guoqing Liu;K. Yao;G. Jiao;Xiaoyan Xu;Q. Hao;L. Jin;Chengshan Li
中科院分区：
文献类型：
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作者：
Zhenbao Li;Guoqing Liu;K. Yao;G. Jiao;Xiaoyan Xu;Q. Hao;L. Jin;Chengshan Li
将负载有四个质量百分比的Bi-2212粉末（MBi-2212= 25.6%、28.1%、30.5%和32.3%）的Bi-2212线分别加工成1.18 mm、1.00 mm和0.81 mm的直径。首次提出了计算Bi-2212导线中平均银间距（IDa）的理论模型。然后比较这些线材的加工窗口（Tp），发现其受线材的平均直径（d）、长丝的平均直径（Da）和IDa的影响。最后揭示了Bi-2212丝材结构对其Tp的影响机理。主要结论如下：（1）884 °C低温下，最大MBi-2212（直径1.18 mm、1.00 mm和0.81 mm）的8 -2线全部失温。Bi-2212晶体的最大Da和最小ID导致的最低传热导致晶体生长最不充分，最终导致其Tpat损失884 °C。(2)直径为0.81mm的四根Bi-2212丝在890 °C高温下全部失温。丝极间严重的耦合和丝极中大量出现的1：2AEC相是导致丝极890 °C失温的主要原因。0.81mm丝的d和ID较小是导致丝耦合加剧的主要原因。(3)0.81mm Bi-2212丝材中较高的温度和较低的氧分压可能导致其较高的1：2 AEC含量。总之，本文为进一步拓宽Bi-2212线材的Tp提供了明确的方向，这将进一步推动Bi-2212线材的工程应用。
Bi-2212 wires loaded with four mass percent of Bi-2212 powder (MBi-2212= 25.6%, 28.1%, 30.5% and 32.3%) were machined to diameters of 1.18 mm, 1.00 mm and 0.81 mm, respectively. The theoretical model evaluating the average interval Ag space (IDa) in Bi-2212 wires was firstly presented. Then the processing window (Tp) for these wires was compared and discovered to be influenced by the average diameter of the wire (d), the average diameter of the filaments (Da) andIDa. Mechanisms on how Bi-2212 wire’s structure influenced itsTpwere finally disclosed. The main conclusions were summarized as follows: (1) Line8-2 holding the largestMBi-2212with diameters of 1.18 mm, 1.00 mm and 0.81 mm all lost theirTpat the low temperature of 884 °C. The lowest heat transfer caused by its largestDaand lowestIDaled to the most insufficient growth of Bi-2212 crystals, which eventually resulted in its loss ofTpat 884 °C. (2) The four Bi-2212 wires with the diameter of 0.81 mm all lost theirTpat the high temperature of 890 °C. Both the severe coupling of the filaments and the abundant 1:2 AEC phase appeared in these wires were found to be the main reasons of losing theirTpat 890 °C. The aggravating coupling of the filaments was mainly caused by both the smaller d andIDain 0.81 mm wires. (3) The higher temperature and the lower oxygen pressure in 0.81 mm Bi-2212 wires might result in its higher content of 1:2 AEC. In conclusion, the article provided a clear direction to broadenTpof Bi-2212 wires by adjusting its structure, which will further propel the engineering application of Bi-2212 wires.