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单芯和多芯拉拔工艺是铋系高温超导带材(Bi-2223/Ag)制备过程中必不可少的重要环节。为研究超导粉体在拉拔过程中的变形行为,对单芯超导线材的拉拔工艺进行理论分析,建立了工艺参数与粉体密度之间的关系,并通过试验验证其合理性。同时,采用大截面减缩率单芯拉拔工艺来实现铋系超导线材的节能高效成形。对1.86mm61芯Bi-2223/Ag线材进行显微硬度测试,并结合数值模拟进行三道次拉拔加工,分析认为:在加工过程中,各超导芯之间及芯内部均存在密度分布不均匀性,且各层粉体密度随拔制过程不断波动,将不利于后续轧制工艺。为此,提出渐进跑道形三道次拉拔工艺,并应用于铋系超导带材的后期拉拔加工,可提高最终带材的临界电流密度10.1%。
Single-core and multi-core drawing process is the bismuth-based high temperature superconducting tape (Bi-2223 / Ag) is an essential part of the preparation process. In order to study the deformation behavior of superconducting powders during drawing process, theoretical analysis was made on the drawing process of single-core superconducting wires. The relationship between process parameters and powder density was established and the rationality of the process was verified. At the same time, the use of large-area reduction rate of single-core drawing process to achieve bismuth-based superconducting wire energy-saving high-performance forming. The microhardness test of 1.86mm61 core Bi-2223 / Ag wire was carried out and the three-pass drawing process was carried out in combination with numerical simulation. The analysis showed that the density distribution existed between the superconducting cores and inside the core during processing Uniformity, and the powder density of each layer fluctuates with the drawing process, which will not be conducive to the subsequent rolling process. For this reason, we propose a progressive runway three-pass drawing process and apply it to the post-drawing processing of bismuth-based superconducting tapes to increase the critical current density of the final tape by 10.1%.