Hoechst Aktiengesellschaft

Andreas Roosen

Friedrich Hessel

Christine Kostler

Katharina Seitz

Gerhard Wegner

Wolfgang Meyer

Hans-Michael Guther

Fritz Aldinger

Christian May

Wolfgang Bocker

Hermann Moser

Rainer Buckpesch

Frank Schroder

Katherina Seitz

Jurgen Rudolph

Wolfgang Sigmund

Harro Bestgen

Christine Koestler

Frank Schroeder

Hans-Michael Guether

A process is proposed for producing non-oxidic ceramic having a thermal conductivity in a predetermined range. A shaped body of non-oxidic ceramic material is heated to remove organic constituents, and is subsequently thermally treated in an oxygen-containing atmosphere to incorporate oxygen atoms into the crystal lattice of the non-oxidic ceramic, with the temperature and/or the hold time at this temperature being selected as a function of the predetermined thermal conductivity range, and the shaped body is finally sintered in a non-oxidizing atmosphere.

Process for producing non-oxidic ceramic having a defined thermal

A composition of inorganic powders comprises inorganic powder, dispersant and binder. The dispersant and/or binder used is a block copolymer of the units methacrylic acid and alkyl methacrylate in which the alkyl radical can comprise from 1 to 8 carbon atoms. The individual blocks of alkyl methacrylate possess an average molecular weight of at least 4000 and the total block copolymer has an average molecular weight of up to 150,000, in each case expressed as number average (M.sub.n).

Inorganic powder composition containing polymeric auxiliaries and use

A water sensitive ceramic powder, in particular aluminum nitride, is provided with a hydrophobic coating. The coated powder is dispersed in water with addition of a binder and a nonionic surfactant from the group comprising ethylene oxide adducts with an HLB value of from 10 to 14. Subsequently the aqueous slip is converted into a free flowing granulated powder. The nonionic surfactant, which is added in an amount sufficient to give a monomolecular layer, makes possible a good dispersion of the hydrophobically coated powder in water.

Process for converting water sensitive ceramic powders into a free

The invention relates to a casting composition comprising a ceramic powder, an organic solvent, binder, plasticizer and a dispersant, which composition is suitable for producing green ceramic sheets by the tape casting process. The dispersant present in the casting composition of the invention is a polyvinyl alcohol/fatty acid ester having a degree of conversion in the range from 50 to 100%. The invention also relates to the use of such a casting composition for producing ceramic green sheets and a process for producing ceramic substrates using a green sheet thus produced.

Casting composition for producing green ceramic sheets containing

A planar sensor made of ceramic material, for measuring and detecting combustible gases and/or the oxygen content in furnaces or in the exhaust gases of internal combustion engines, is described. The sensor has an at least five-layered structure on the basis of a combination of three zirconium dioxide layers with two aluminum oxide layers, a metallic heating resistor being embedded between two aluminum oxide layers, and three zirconium dioxide layers being combined with two platinum electrodes and one further electrode made of a binary or ternary alloy of platinum with gold, nickel, copper, rhodium, ruthenium, palladium or titanium. A process for fabricating the sensor is also described. It is also possible for the sensor to be combined, according to the invention, with a suitable housing which on its outside is provided with connecting wires and plugs for transmitting the measured signals.

Planar sensor made of ceramic material, for detecting combustible gases

A method of processing water-sensitive ceramic powders, particularly carbothermically produced aluminum nitride, whereby the ceramic powder is deagglomerated in a dry milling step with addition of an alkylamine which is liquid at room temperature is disclosed. The alkylamine is added in an amount sufficient to produce a monomolecular layer on the surface of the ceramic powder. The deagglomerated powder subsequently is vigorously stirred with a concentrated aqueous solution or dispersion of binder and rapidly and gently dried, preferably by freeze drying. Aluminum nitride powder prepared by this process can be further processed into shaped parts with a high thermal conductivity.

Process for converting water-sensitive ceramic powders into a

A planar oxygen sensor based on zirconium dioxide is described which is suitable for measuring the oxygen content in combustion furnaces or in the exhaust gases of internal combustion engines. Disposed on an external surface of the sensor is a noble-metal measuring electrode and located in its interior is a reference electrode which is connected to an external contact and is enclosed by two zirconium dioxide layers. One of these layers has, in its region near the edge, a hole whose outwardly pointing part is sealed by a solder glass. The internal part of the hole is partially filled with sintered platinum which makes a conductive connection between a platinum wire, passing outwards through the hole, as external contact and a platinum conductor track which is disposed on the internal interface of the zirconium dioxide layer and which leads to the reference electrode. A method of producing the oxygen sensor is also described.

Oxygen sensor and method of producing it

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Hofheim, Germany

Andreas Roosen