Bbc Brown, Boveri & Company, Limited

Asea Brown Boveri Ag

Asea Brown Boveri Inc.

Bbc Brown Boveri Ag

Gundolf Meyer

Imre Horvath

Clemens Verpoort

Kurt Kwasnitza

Erwin Schonfeld

Christoph Tonnes

Alfred Koch

Clemeens Verpoort

Reinhard Kurt Maix

Harald Fillunger

Process for the production of an elongate body of longitudinally aligned acicular crystals (3) of the superconducting substance REBa.sub.2 Cu.sub.3 O.sub.6.5+y, with RE=rare earth metal, 0&lt;y&lt;1, in which fine-grained powder (1) with a particle diameter of 0.1-5 .mu.m is sintered for 1-100 h at a temperature of 600.degree.-850.degree. C. with application of a pressure of 100-5,000 bar. For the production of a filament conductor, the powder is filled into a small Ag tube (4), drawn, and pressure sintered at 800.degree. C./10 h under 2,000 bar.

Process for the production of an elongate body consisting of

The process serves for producing a carbon-containing sintered compact from steel powder. In this process, the steel powder is heated to sintering temperature in an atmosphere containing, at least for a time, carbon monoxide, is kept at sintering temperature over a predetermined period of time and the sintered compact formed thereby is subsequently cooled. In this process, the carbon content of the sintered compact to be produced is to be set to a predetermined value in a way which is simple and suitable for mass production. This is achieved by the partial pressure of the carbon monoxide in the atmosphere being changed selectively during the execution of the production process, and by this change being controlled in such a way that the carbon content of the sintered compact is set to the predetermined value after execution of the production process.

Process for producing a sintered compact from steel powder

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

Conductor in strip, sheet or wire form with an electrical conductivity of at least 0.85.times.10.sup.6 .OMEGA..sup.-1 cm.sup.-1 at 77.degree. K. composed of a composite material of a metal matrix (1) and particles (2) composed of a high-temperature superconductor of the type RE Ba.sub.2 Cu.sub.3 O.sub.6.5-7.5 embedded therein and arranged rectilinearly in the longitudinal direction, RE generally denoting a rare earth metal. Preferably RE=yttrium and specifically the substance YBa.sub.2 Cu.sub.3 O.sub.7 and the particle diameter=0.1-100 .mu.m, more narrowly 0.2-20 .mu.m. Optionally an additional metal sheath which envelops the body forming the matrix (1).

Composite superconductor

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.

Process for producing a multiple-filament oxide superconductor

Process for the hot forming of sheets (5) made of a material that is difficult to work, especially of a dispersion-hardened high-temperature alloy by hot-isostatic pressing in one operation against the contour of a mold (1) serving as negative form in a container (2) that is under vacuum (6) and closed by a cover (3) with welding seam (4). In addition, joining of several sheets (5) to form one body (9) of complicated shape by the diffusion bonding process at the end of the hot-isostatic pressing in one heat in the same single operation.

Process for the hot-forming of at least one sheet made of a material

A superconductor structure is disclosed in which a plurality of superconductive assemblies are provided with at least one cooling arrangement. The superconductive assemblies consist of superconductor components and a stabilizing conductor, with at least a portion of the stabilizing conductors in the structure being provided with cooling passages. A cooling arrangement is enclosed between adjacent superconductive assemblies. The assemblies are preferably insulated from each other to prevent eddy current flow and may be joined by resistors or diodes connected across the ends of the superconductor components.

Electrical superconductor

An electrical superconductor comprises in a stepwise manner single conductors and at least two stages of stranding of component cables and interstitial layers having a high resistance relative to the conductivity of the matrix material arranged between the single conductors and/or the component cables. The electrical resistance of the interstitial layers from inner twisted single conductors to the interstitial layers of the outer component cables are made progressively higher in at least two consecutive interstitial layers in order to effect a reduction in electrical losses in an economical manner.

A method of producing a stabilized electrical superconductor wherein a longitudinally extending slug is provided, the slug including a matrix of copper within which are embedded, in a central region thereof, a multiplicity of wires or rods made from a superconductor-forming material such as niobium or vanadium. Surrounding the superconductor-forming material, within the outer region of the copper matrix, is a circular array of a material such as copper wires or rods having a high electrical conductivity characteristic, forming an electrically parallel connection with the superconductors which provides a bridge of good electrical conductivity in the event the superconductivity of the superconductor is lost for any reason. The slug is then worked and drawn to convert the various wire or rod components within it into filamentary form, after which a tin layer is applied to its surface. By a heating and annealing process, the tin in the surface layer diffuses radially inward through the copper matrix and into the niobium or vanadium superconductor-forming wires or rods thus to convert the latter into superconductors. The circular array of the wires or rods having the high electrical conductivity characteristic that form a bridge paralleling the superconductors are each enclosed within a sheath of a diffusion-inhibiting material such as tantalum to prevent diffusion thereinto of the tin which would otherwise undesirably reduce their electrical conductivity.

Method for producing a stabilized electrical superconductor

A plurality of superconductive wires form a cable. In each wire a number of filaments of superconductive material are embedded in a matrix of normal electrically conductive material. The individual wires are connected by a thermally conductive joining medium whose melting point lies below that of the matrix and whose tensile and/or shear strength at the operating temperature of the superconductor is substantially equal to or greater than that of the matrix.

Superconductor

A method of producing a stabilized electrical superconductor wherein a longitudinally extending slug is provided, the slug including a matrix such as bronze within which are embedded a multiplicity of wires or rods of a material such as niobium into which the tin in the bronze is diffused to convert the niobium into a superconductor. The matrix is surrounded by a ring of wires or rods of a material such as copper having a high electrical conductivity characteristic, forming an electrically parallel connection with the superconductors which provides a bridge of good electrical conductivity in the event the superconductivity of the superconductor is lost for any reason and each of these latter wires or rods is surrounded by a high resistance layer such as a copper-nickel alloy, which, in turn, is surrounded by a diffusion inhibiting layer such as tantalum to prevent diffusion of the tin from the bronze matrix into the copper wires or rods which would otherwise reduce their electrical conductivity. The slug is then drawn to convert the various wire or rod components within it into filamentary form, and diffusion of the tin into the niobium to convert the latter into a superconductor is effected by annealing.

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Birmenstorf, Switzerland

Gundolf Meyer