Swiss Aluminium Ltd.

Alusuisse-lonza Services Ltd.

Swiss Aluminum Ltd.

Albert Maurer

Jean-Pierre Gabathuler

Tiberiu Mizrah

Ludwig Gauckler

Peter Kaser

Anton Fischer

Karl-Ludwig Eckert

Wolfhart Rieger

Konrad Kampfer

The process for manufacturing an open pore foam body with three dimensional ceramic network, in particular as a filter for the treatment of hot gases or as a catalyst substrate, has as its starting material a block of open pore plastic foam. This is impregnated at least once with a ceramic suspension, freed of excess ceramic suspension and heated to a temperature below the melting point of the plastic, then finally burnt off at a temperature at which the ceramic sinters together. The plastic foam block of the prescribed outer dimensions is cooled down and machined to produce a Z-flow filter with high precision longitudinal channels.

Process for manufacturing a ceramic foam body

The process for manufacturing an open pore foam body with three dimensional ceramic network, in particular as a filter for the treatment of hot gases or as a catalyst substrate, has as its starting material a block of open pore plastic foam. This is impregnated at least once with a ceramic suspension, freed of excess ceramic suspension and heated to a temperature below the melting point of the plastic, then finally burnt off at a temperature at which the ceramic sinters together. At least one plastic foam layer is impregnated, assembled into a plastic foam block with flow channels between two layers and sintered to form a Z-flow filter.

In a filter consisting of holoow cylindrical open-pore ceramic foam cylinder elements and an end plate made of gas-impermeable material, as an insert in a filter cup for cleaning exhaust gases of diesel engines, in which the exhaust gases flow through the active filter section essentially perpendicularly to the cylinder axis, bending moments which lead to breakage of the ceramic foam cylinder elements occur during fitting of the elements due to lack of surface evenness and plane-parallelism of the end faces. A filter of the aforementioned kind, in which the end faces of the ceramic foam cylinder elements are provided with temperature-resistant and thermal shock-resistant layers of material which are plastic at room temperature, avoids the bending moments.

Filter for cleaning exhaust gases of diesel engines

In a filter consisting of hollow cylindrical open-pore ceramic foam cylinder elements and an end plate made of gas-impermeable material, as an insert in a filter cup for cleaning exhaust gases of diesel engines, in which the exhaust gases flow through the active filter section essentially perpendicularly to the cylinder axis, bending moments which lead to breakage of the ceramic foam cylinder elements occur during fitting of the elements due to lack of surface evenness and plane-parallelism of the end faces. A filter of the aforementioned kind, in which the end faces of the ceramic foam cylinder elements are provided with temperature-resistant and thermal shock-resistant layers of material which are plastic at room temperature, avoids the bending moments.

In filters for cleaning the exhaust gases from diesel engines having openpored foam ceramic bodies, the deposited soot particles are burned up at temperatures of between 550.degree. and 700.degree. C. at periodic intervals. In order to lower the inflammation temperature of the soot in the regeneration phase of the filter, the ceramic bodies are catalytically coated. The region of the openpored foam ceramic body first subjected to the flow of the exhaust gases of the diesel engines has at least partly a denser pore structure than the remaining foam body so that the inflammation temperature can be lowered since temperature peaks occur in these regions on account of increased soot deposits, which temperature peaks lead to inflammation of the soot located there and consequently burn up all the soot deposited in the filter.

Filter for cleaning the exhaust gases from diesel engines

Filter medium in the form of a stable porous body of granules of spherical form bonded together by a different phase or by sintering. Preferably hollow spherical granules of corundum are manufactured into filter media in plate form. The filter media are employed for filtration of molten metal preferably aluminum.

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Thayngen, Switzerland

Albert Maurer