Max-planck-gesellschaft Zur F&#xf6;rderung Der Wissenschaften E. V.

Hoechst Aktiengesellschaft

Max-planck-institut Zur Foerderung Der Wissenschaften E.v.

Firma Schott Glaswerke

502 Robert Bosch Gmbh

Gunter Petzow

Nils Claussen

Manfred Ruhle

Jurgen Jahn

Heinrich Hofmann

Kurt Weiss

Hans-Jerg Kleiner

Martin Bruck

Marcellus Peuckert

Tilo Vaahs

Friedrich J Esper

Gerhard Schneider

Waldemar Draxler

Helmut Schubert

Bernhard Hettich

Richard J Brook

Peter Majewski

Michael Hoffmann

Klaus Nickel

Klaus Schulze, Deceased

Andreas Buchel

Klaus-Dieter Durst

Ernst-Theo Henig

Helmut Kronmuller

Ralf Riedel

Karl-Ludwig Weisskopf

Wolfgang Panhorst

Martin Sehr

Houssmann

Peter Greil

The invention relates to an oxide-ceramic superconducting material which contains bismuth, strontium, calcium and copper, having an overall composition of Bi.sub.y Ca.sub.2 Sr.sub.2 Cu.sub.3 O.sub.x, where y is an integer from 2.35 to 2.6 and x is about 10 to 12. The material has a critical temperature T above 105 K and has a proportion of the phase Bi.sub.2 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.x of at least 85% by volume. The invention also relates to a process for producing a bismuth-containing superconducting material which comprises holding the oxides or oxide precursors of bismuth, strontium, calcium and copper at a temperature in the range from 850.degree. to 890.degree. C. over a time span of a plurality of hours and adhering to the following atomic ratios:

Bismuth-containing superconducting material and process for producing it

Sinter magnet based on Fe-Nd-B

The invention relates to a novel sinterable ceramic powder, to its preparation and to its further processing to give a silicon nitride ceramic, and to this material itself and its use. The sinterable ceramic powder is produced by melting a polysilazane or dissolving it in an organic solvent, suspending a powdered sinter aid in this melt or solution, then pyrolyzing the melt, or the residue obtained after evaporation of the solvent, at 500.degree. to 1600.degree. C. in a protective gas atmosphere, the polysilazane either

Sinterable ceramic powder, process for its production, silicon nitride

Process for the hot isostatic compression of silicon nitride bodies

A novel method of sintering Si.sub.3 N.sub.4 shaped bodies which method comprises grinding Si.sub.3 N.sub.4 with the use of a grinding material down to a surface area magnitude of 10.5 to 35 m.sup.2 /g and an average particle size from 0.2 to 0.005 .mu.m, shaping the powder obtained, and sintering the compact under inert gas or nitrogen at a temperature from 1700.degree. to 1900.degree. C.

Method of sintering articles of silicon nitride

Boron carbide/transition metal boride molded articles produced by hot preng a mixture of from 25 to 75% by weight of boron carbide, from 14 to 40% by weight or boron, from 10 to 50% by weight of tungsten and/or titanium carbide, from 0 to 6% by weight of cobalt and from 0 to 8% by weight of silicon to convert the carbide into the corresponding boride.

Molded metal carbide-boride refractory products

The present invention provides a fine-grained ceramic formed body of 0.5 to mole % rare earth oxide and 0.5 to 7 mole % MgO-containing ZrO.sub.2, wherein the cubic granules thereof are coated with Mg-Al spinel particles. The present invention also provides a process for the production of such formed bodies, wherein a ZrO.sub.2 powder alloyed with rare earth oxide, which contains small amounts of Al.sub.2 O.sub.3, is pressed and sintered in the presence of MgO at a temperature of from 1400.degree. to 1600.degree. C. and optionally subsequently tempered at a temperature of from 1200.degree. to 1350.degree. C.

High-strength and temperature-stable formed bodies of zirconium dioxide

Ceramic moldings containing finely crystalline cordierite are described, which are obtainable by the intensive grinding of precrystallized cordierite powder, mixing the powder with second additive phases of higher modulus of elasticity, shaping the mixture, and sintering the greenware thus obtained in a siliceous atmosphere at temperatures between 900.degree. and 1400.degree. C. The moldings according to the invention have not only good mechanical strengths but also outstanding dielectric and thermal properties; they are therefore especially suitable for use as dielectrics and as thermal insulating components.

Process of making ceramic moldings containing cordierite

The present invention provides a fibre-strengthened ceramic formed body with improved mechanical strength, wherein it contains at least 15% by volume of zirconium dioxide, hafnium dioxide or zirconium dioxide/hafnium dioxide composition in the form of monoclinic crystals and an amount of inorganic fibres sufficient for increasing the strength, which is obtainable by hot pressing a mixture of ceramic matrix materials, at least 15% by volume of tetragonal zirconium dioxide, hafnium dioxide or zirconium dioxide/hafnium dioxide composition particles and the fibres at a temperature above the tetragonal.fwdarw.monoclinic transition temperature. The present invention also provides a process for the production of such a ceramic formed body.

Fibre-strengthened ceramic formed bodies

A process for the preparation of boron carbide/transition metal boride mod articles comprising hot pressing a mixture of from 25 to 75% by weight of boron carbide, from 15 to 40% by weight of boron, from 0 to 8% by weight of silicon, from 10 to 50% by weight of tungsten and/or titanium carbide, and from 0 to 6% by weight of cobalt.

Process for the preparation of carbide-boride products

A ceramic body of zirconium dioxide containing, if desired, aluminum oxide, and partially stabilized with yttrium oxide and/or one or more rare earth oxides (e.g., cerium dioxide) and/or magnesium oxide and/or calcium oxide is partially stabilized with 0.5 to 5 mole-% of yttrium oxide and/or 5 to 12 mole-% of magnesium oxide and/or calcium oxide and/or cerium dioxide or one or more rare earth oxides, is 30 to 100% in the tetragonal lattice modification and has in the surface region a content of yttrium oxide, cerium dioxide, magnesium oxide, calcium oxide or rare earth oxide that is 1 to 20 mole-% higher than the average content, such that the body is coated with a thin, PSZ-like layer in a more highly stabilized tetragonal or with a layer that is predominantly in the cubic lattice form. For preparation, the surface of an already sintered or only presolidified compact of partially stabilized zirconium oxide is brought into intimate contact with yttrium oxide, cerium dioxide, magnesium oxide, calcium oxide and/or another rare earth powder or a zirconium dioxide powder containing at least 12 mole-% of yttrium oxide and/or other stabilizer oxides, and then annealed at 1000.degree. to 1600.degree. C. until a more highly stabilized tetragonal or predominantly cubic surface layer of 0.1 to 200 micrometers thickness and 2 to 20 mole-% higher content of yttrium oxide, cerium dioxide, magnesium oxide, calcium oxide or rare earth oxide has formed.

Ceramic body of zirconium dioxide (ZrO.sub.2) and method for its

The present invention is concerned with a ceramic formed body comprising a ceramic matrix and at least one phase of ceramic incorporation material dispersed therein, characterized by a dense, microcrack-free ceramic base matrix and compressive zones incorporated therein which consist of a mixture of the base matrix material with unstabilized zirconium dioxide particles which are predominantly monoclinic at ambient temperature. The present invention is also concerned with a process for the production of such ceramic formed bodies and with the use thereof as constructional elements in the hot region of heat engines.

Ceramic formed body with a high crack arrestability

A ceramic formed body having high temperature change resistance and stren and being composed of a ceramic matrix with dispersed particles of ZrO.sub.2, HfO.sub.2, or mixture thereof, is formed of a powdered ceramic material which is a precursor to the matrix material of the ceramic matrix, mixed with a compound which can form ZrO.sub.2, HfO.sub.2 or mixture thereof upon reaction with the ceramic material, and thereafter densely sintered below the reaction temperature. The sintered body is then heat treated above the reaction temperature to convert the precursor ceramic material into the matrix material and form the ceramic body with in situ formation of the dispersed particles.

High-strength and temperature-change resistant ceramic formed body,

In a process for the production of dispersion ceramics by sintering or hot pressing of a mixture of a matrix-forming ceramic material and of at least one ceramic embedment material dispersible therein which at the sintering temperature of the ceramic and at room temperature is present in different enantiotropic solid modifications of different densities, a ceramic embedment material is employed which is divided into at least two groups of different, substantially uniform particle sizes, each group having different lower phase-transition temperatures.

Process for the preparation of dispersion ceramics

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Leinfelden-Echterdingen, Germany

Gunter Petzow