Asea Brown Boveri Ag

Bbc Brown Boveri Ag

Asea Brown Boveri Inc.

Clemens Verpoort

Gundolf Meyer

Erwin Schonfeld

Christoph Tonnes

Peter Jongenburger

A process for the powder-metallurgical production of a workpiece by filling a binder-free and solvent-free, dry metal powder or ceramic powder into a mold, precompacting the powder by tapping and presintering it for 1/2 hour to 1 hour at 0.65 to 0.85 times the absolute melting temperature without significant shrinkage, adjacent powder particles being joined merely at their contact points by necking to give a skeletal formed body. The formed body is taken out of the mold and finish-sintered at at least 0.9 times the absolute melting temperature for at least 1 hour without additional support by a mold. Advantageously, the sintered body is additionally hot-isostatically pressed containerless in order to reach at least 98% of the theoretical density.

Process for the powder-metallurgical production of a workpiece

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.

Process for producing a multiple-filament oxide superconductor

A composite gas turbine blade consists of an airfoil (1) in an oxide-dispersion-hardened nickel-based superalloy, in the condition of longitudinally directed coarse columnar crystals, and a shroud plate (6) or a shroud and a root (7), the latter items in a non-dispersion-hardened nickel-based superalloy (cast alloy). The gas turbine blade is manufactured by casting in and casting round, using the non-dispersion-hardened superalloy mentioned, the tip end (2) and root end (3)--provided with depressions (4) and/or protrusions (5)--of the airfoil (1), after preheating the latter to a temperature of between 50.degree. and 300.degree. C. below the solidus temperature of the lowest melting phase of the airfoil material. The casting temperature for this should be a maximum of 100.degree. C. above the liquidus temperature of the highest melting phase of this non-dispersion-hardened alloy. Any melting onto the airfoil (1) and any metallurgical connection is to be avoided. It is advantageous to provide a thermally insulating, mechanically damping intermediate layer (16) of an oxide of at least one of the elements Cr, Al, Si, Ti and Zr with a thickness of 5 to 200 .mu.m between the airfoil (1), on the one hand, and the shroud plate (6) and the root (7), on the other.

Composite gas turbine blade and method of manufacturing same

Method of manufacturing a workpiece of any given cross-sectional dimensions from an oxide-dispersion-hardened nickel-based superalloy available in the form of coarse-grained longitudinally directed columnar crystals by connecting previously very finely machined workpiece parts derived from a semi-finished product by diffusion-bonding using hot isostatic pressing, the workpiece parts being first heat-treated under a protective gas in the temperature range of 50.degree. to 100.degree. C. below the recrystallization temperature, under a pressure p.sub.k of not more than 5 MPa with the machined surfaces to be connected joined together, the workpiece then being heated at least to a critical temperature T.sub.K, above which no further cold working takes place, and the pressure then being gradually increased to the diffusion bonding pressure p.sub.max of 100 to 300 MPa with simultaneous increase in temperature are a heating rate of not more of 2.degree. C./min to the diffusion bonding temperature T.sub.D of 0 to 50.degree. C. below the recrystallization temperature, this condition being maintained for 1 to 24 hours. Safe variant: only raise the pressure when T.sub.D has been reached!Application: gas turbine blading of large dimensions.

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Fislisbach, Switzerland

Clemens Verpoort