Asea Brown Boveri Ag

Erwin Schonfeld

Gundolf Meyer

Clemens Verpoort

A powder-in-tube method is disclosed for making a composite superconducting oxide wire which comprises loading a copper tube with a mixture composed of rare earth metal oxide, BaO.sub.2 and copper oxide or the finished superconductor powder and subjecting the loaded tube to drawing and a heat treatment at a temperature of up to 950.degree. C., wherein prior to loading the copper tube, the tube is oxidized at least on its inside to form a copper oxide layer having a thickness of 1 to 100 .mu.m and then a silver intermediate layer is inserted to the oxidized copper tube.

Process for producing a sheathed wire composed of a ceramic

Production of a sheathed wire or multiple-filament conductor composed of ceramic high-temperature superconductor by mixing Y.sub.2 O.sub.3, CuO and BaO.sub.2 or BaO.sub.2 +BaO, loading the powder mixture (3) into the interior of a metal sheath (1) lined with Ag intermediate layer (2), slowly heating to a maximum permissible reaction/sintering temperature of 950.degree. C. in a period of at least 0.1 h, holding the sintering temperature for at least 1 h, cooling down to 200.degree. C. at at most 10.degree. to 100.degree. C./h to form a conducting core (4) composed of YBa.sub.2 Cu.sub.3 O.sub.6.5-7.5. Variants having a layer composed of CuO, diffusion barrier composed of Ni, Ta, Nb, V or having Ag intermediate layer doped with AgO or BaO.sub.2. Preferably reactive sintering under a pressure of 10 to 10.000 bar as hot isostatic pressing. Variant: reactive annealing of the powder mixture under oxygen pressure of 10 to 3000 bar at 600.degree. to 950.degree. C. Pulverizing of the body formed, loading into the metal sheath (1), fabrication, sintering to form a compact superconductor under an external pressure of 10 to 3000 bar at 500.degree. to 900.degree. C. Multiple-filament conductor with centrally arranged tracks of oxygen-releasing substances surrounded by peripheral superconductor tracks.

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Baden-Dattwil, Switzerland

Erwin Schonfeld