A fabrication technique for producing flexible superconductor wire by extrusion of a composite of Ag2O-YBa2 Cu3 O7−x is reported. During the course of processing, the superconductive transition of the starting powder is maintained, thus obviating the need for subsequent heat treatment. This nonpoisoning behavior of Ag2 O is of significant technical importance. Scanning electron fractography reveals a mixed mode fracture behavior of the material and the evidence of ductility. Magnetic measurements on the extruded wires show an onset temperature of 91 K. Resistivity measurements indicate that the electrical resistance of the as-extruded wire essentially vanishes at liquid-nitrogen temperature.
Fractographic investigation has been carried out on glass fabric-epoxy composite laminates using scanning electron microscopy. Focusing on the flexural failure of lap shear specimens, some unique fracture features have been identified, and their likely origin suggested and explained. The influence of voids, present in the matrix, on the appearance of the fracture surface has been illustrated.
Silver is known to act as a compatible metal host for designing a microcomposite system with the high temperature superconducting ceramic YBCO[l,3]. The unique role played by nascent silver generated from the silver monoxide precursor during sintering as well as warm compaction of the powder mix is illustrated with the help of light optical micrography. It is seen that electrical as well as mechanical properties of the bulk composite is significantly governed by its microstructure. The microstructure, in turn, could be controlled by suitable heal treatment and proper selection of the fabrication process parameters at every step. Attempting a structure‐propcrty‐processing correlation, a microstructure controlled scheme for fabricating superconducting composite product of useful shapes is discussed. Successful fabrication of thin (0.75 mm dia.) and long (450 mm) flexible wire following this route is also reported here.
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