Expedited Award for Novel Research: Investigation of the Novel Processing Technique for Fabrication of Flexible High Tc Superconducting Wire

本项目采用一种新的加工技术，采用Y-BaO-铜-氧体系+银氧化物的复合材料来制造柔性超导体线材。在加工过程中，陶瓷超导材料的氧化学计量比将保持在所需的水平，从而消除了通过热处理来再生超导电性的需要。先前使用光学和扫描电子显微镜的工作显示出致密的微结构且没有裂纹。断口显示了复合材料的复合型断裂行为和延性的证据。挤压后的线材在较高的磁场下表现出迈斯纳效应，磁化率测量的起始温度为91K。该项目旨在优化工艺参数，以改善质地，从而提高挤压丝的电流密度。也有可能以较低的挤压比对烧结坯进行冷挤压，并在工艺退火后将挤压出的线材拉伸到更精细的尺寸。该项目还将探索另一种新的超声拉丝工艺，以制备这些超导陶瓷复合材料的精细柔性丝。

This project deals with a fabrication technique for producing flexible superconductor wire by employing a novel processing technique and a composite of yttrium-barium-copper-oxygen system plus silver oxide. During the course of processing, the oxygen stoichiometry of the ceramic superconducting material will be maintained at the desired level, thus obviating the need to regenerate superconductivity by heat treatment. Prior work using an optical and a scanning electron microscope revealed a dense microstructure and absence of cracks. Fractured surface showed the mixed mode fracture behavior of the composite material and the evidence of ductility. The as-extruded wires showed Meissner effect at a significantly high field and the magnetic susceptibility measurements showed the onset temperature of 91K. This project is addressed to optimize the process parameters, to improve texture and hence the current density of the extruded wire. It is also possible that the sintered billet can be cold extruded for lower extrusion ratios and after process annealing the extruded wire can be drawn to finer dimensions. Another novel processing technique of ultrasonic wire drawing for fabricating fine flexible wires of these superconducting ceramic composites will also be explored in this project.