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

本项目采用一种新颖的加工工艺和钇-钡-铜-氧体系与氧化银的复合材料，研究了柔性超导体线的制造技术。在加工过程中，陶瓷超导材料的氧化学计量量将保持在所需的水平，从而避免了通过热处理再生超导性的需要。先前使用光学和扫描电子显微镜的工作揭示了致密的微观结构和没有裂纹。断口表面表现出复合材料的混合模式断裂行为和延性证据。在高磁场下，挤压态金属丝表现出明显的迈斯纳效应，磁化率测量显示起始温度为91K。该项目旨在优化工艺参数，改善纹理，从而提高挤压线材的电流密度。也有可能烧结后的坯料可以冷挤压以获得较低的挤压比，并且经过工艺退火后，挤压后的线材可以拉到更细的尺寸。本项目还将探索另一种新型的超声拉丝加工技术，用于制作这些超导陶瓷复合材料的细软线。

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.