| 摘要 |
1170645 Super-conductors IMPERIAL METAL INDUSTRIES (KYNOCH) Ltd 6 Sept 1968 [28 Sept 1967] 44142/67 Headings H1A A5 and A4D An electrical conductor is produced by locating a ductile super-conductor member in a sheath consisting of at least one metal selected from the group Al, Ag, Cd, In, Pb, Sn, providing the sheath with an external can of a ductile metal which will support the sheath, and working the assembly to reduce its cross-sectional dimensions. Since the sheath metals specified are generally softer than the super-conductor direct drawing results in the thickness of the sheath decreasing faster than that of the super-conductor member and the use of an external supporting can of, for example, copper or mild steel reduces this effect. The can may be removed after the conductor has been drawn to the required size or may be retained if it is of copper. The super-conductor may be Nb 44 wt. per cent Ti. An initial direct extrusion of the superconductor and sheath may be performed by heating a super-conductor bar, inserting it into a cold sheath, and immediately extruding the assembly. Heating the super-conductor increases its ductility to allow direct drawing. This initial step may be omitted and the sheath may be provided with an inner layer of Cu to improve the metallurgical bond. A plurality of drawn filaments may be inserted into a can and further drawn down. |
