Th. Goldschmidt Ag

Elektro-thermit Gmbh

Horst Eggert

Michael Steinhorst

Hans-Gunter Domazer

Martin Edeling

Gunter Buttner

The invention relates to an automatically opening tapping thimble made from a refractory material for casting crucibles which are used in aluminothermic reactions. This thimble consists entirely or partially of air-permeable graphite or metal whose melting point lies between 2100 and 3727.degree. C.

Automatic tapping thimble

Disclosed is a method for the aluminothermal production of molten steel for the aluminothermal welding of workpieces, wherein the aluminothermal reaction is carried out in a crucible made of porous or hollow spherical .alpha.-Al.sub.2 O.sub.3 with a density of 0.8-3.0 g/cm.sup.3 and a bulk density of 0.3-1.8 g/cm.sup.3.

Method for the aluminothermal production of molten steel

A method for the preparation of alloys of the SE.sub.2 Fe.sub.17-x TM.sub.xN.sub.y type where SE stands for a rare earth metal, including Y or a mixture of these metals, while TM stands for Co, Ni, Cu, Zr, Ga, Hf, Ta, Nb, Ti, Si, A1, V, Mo, Cr, Zn or Sn or a mixture of these metals, x=0 to 10, y=&gt;0 to 5 is described. The preparation involves calciothermal reduction of a finely divided, homogeneous mixture of the alloying components, subsequent diffusion of the components, followed by nitriding and separating the calcium oxide and excess calcium formed. The method is characterized by:

Method for the preparation of alloys of the rare earth metals of the

A method for producing single-phase intermetallic phases, which melt incongruently within a temperature range of 900.degree. to 2,000.degree. K., with a homogeneity range of .ltoreq.10 atom % at room temperature by co-reduction is described. The exothermic reaction of the calciothermal reduction is adjusted by altering the oxide content of the reaction mixture, the composition of which corresponds to the desired single-phase alloy, in such a way that the temperature condition T.sub.m &gt;T.sub.R .gtoreq.0.9 T.sub.m (in .degree. K.) is fulfilled, T.sub.m being the melting temperature of the intermetallic phase and T.sub.R the reaction temperature. The components of the reaction mixture, with the exception of calcium, have an average particle size of .ltoreq.75 .mu.m. The reaction product at the end of the exothermic reaction is tempered at a temperature which is at least 0.7 times the melting temperature T.sub.m of the desired, single-phase alloy, measured in .degree. K., but is less than the melting temperature T.sub.m, during a period sufficient for the diffusion of the components.

Method for producing single-phase, incongruently melting intermetallic

For preparing a chromium metal powder lacking in oxygen and having an average particle size not greater than 20 .mu.m, a mixture of chromium oxide and calcium oxide, in a molar ratio of 1:0.5 to 1:2, is calcined initially at temperatures of 650.degree. to 1,200.degree. C. with access of oxygen up to a weight increase of 1 to 6 g per mole of chromium oxide, the calcined product is comminuted to a particle size not greater than 100 .mu.m and the product so obtained is reduced calciothermally. The calcium oxide can be replaced wholly or partially by calcium carbonate.

Process for the preparation of finely particulate chromium metal powder

A process is disclosed for the preparation of alloy powders, which can be sintered and which are based on titanium, by the calciothermal reduction of the oxides of the metals forming the alloys in the presence of neutral additives. This can be accomplished by mixing TiO.sub.2 with oxides of the other components of the alloy, admixing an alkaline earth oxide or carbonate with the metal oxides, calcining the mixture. After cooling, the mixture is crushed and calcium is added. Thereafter, green compacts are formed which are heated and leached to remove the calcium oxide. The powder obtained is of uniform structure composition, is free of segrations of oxides nitrides carbides and/or hydrides and has high bulk and tap densities and can be molded by isostatic hot molding.

Process for the preparation of alloy powders which can be sintered and

This invention relates to a vacuum rotatable tubular furnace for metallothermal reactions comprising an outer housing adapted to be evacuated and having one end thereof a closable filler cap, and a vacuum-tight passage for a shaft on the other end, rotatable tube means in said outer housing, said tube means being open on an end thereof facing said filler cap, and having a shaft connected to the other end of said tube and extending through said housing, a cylindrical reaction chamber mounted in said rotatable tube means symmetrically to the longitudinal axis of the latter, and being detachably connected thereto, said reaction chamber being narrowed on a filling end thereof to a tube having a small lumen and being closed at the other end thereof, a cylindrical evaporation chamber mounted in the area of the filling end of the reaction chamber and being adapted to contain metal effecting a metallothermal reaction, said evaporation chamber having an opening on an end thereof facing said filler cap, heating means on said rotatable tube means at least within the area of the cylindrical reaction chamber, means for evacuating the rotatable furnace, and drive means for rotating said rotatable tube means.

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Dorsten, Germany

Horst Eggert