Porous fluid-permeable moldings of silicon carbide and process of production
AssigneeForschungszentrum Julich GmbH
InventorsFrancisco J. Dias, Freimut J. Koch
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Abstract
A process for producing a porous fluid permeable body which is heatable by the passage of electric current therethrough. The process involves coating silicon-containing particles with a cokable organic binder to produce coated particles with a particle size fraction of 0.2 to 10 mm, forming the particles into a molding, coking the binder and heating the molding at 1400.degree. to 2000.degree. C. in the presence of nitrogen to form a doped body containing 30% to 100% .beta.-silicon carbide.
Claims7
A process for producing a porous, fluid-permeable body heatable by passage of an electric current through the body, said process comprising the steps of:
- (a) coating silicon-containing particles with a cokable organic binder to produce coated particles with a particle size fraction of 0.2 to 10 mm;
- (b) forming said particles into a molding having a shape of the body;
- (c) heating said molding at a temperature of 600.degree. to 1000.degree. C. to coke said binder and produce in a resulting coked molding reactable silicon and carbon sufficient to form .beta.-silicon carbide in an amount of 30% to 100% of said body;
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- (d) thereafter heating said molding to a temperature of 1400.degree. to 2000.degree. C. in the presence of nitrogen derived from at least one of a nitrogen compound present in said body and a nitrogen atmosphere to react the silicon with the carbon and comprise said body of 30% to 100% of .beta. silicon carbide simultaneously doped with nitrogen, thereby forming said body with a specific electrical resistance of 10.sup.-2 to <18.OMEGA. cm.sup.-1 and a porosity of 35% to 75%.
A process for producing a diesel soot filter element which comprises the steps of:
- (a) coating silicon-containing particles with a cokable organic binder to produce coated particles with a particle size fraction of 0.2 to 10 mm;
- (b) forming said particles into a molding having a tubular shape and having thickened walls at opposite ends of said body;
- (c) heating said molding at a temperature of 600.degree. C. to 1000.degree. C. to coke said binder and produce in a resulting coked molding reactable silicon and carbon sufficient to form .beta.-silicon carbide in an amount of 30% to 100% of said body;
- (d) thereafter heating said molding to a temperature of 1400.degree. C. to 2000.degree. C. in the presence of nitrogen derived from at least one of a nitrogen compound present in said body and a nitrogen atmosphere surrounding said body to react the silicon with the carbon and comprise said body of 30% to 100% of .beta.-silicon carbide simultaneously doped with nitrogen, thereby forming said body with a specific electrical resistance of 100.sup.-2 to less than 18 ohm cm.sup.-1 and a porosity of 35% to 75% comprising the diesel soot filter element having electrical contacts at said opposite ends for passing an electric current through the diesel soot filter.
A diesel soot filter consisting of a body of silicon carbide containing 30% to 100% .beta.-silicon carbide formed in situ and doped in situ with nitrogen and having a porosity of 35 to 75% and a specific electrical resistance of 100.sup.-2 to less than 18 ohm cm.sup.-1.
Dependencies are inferred from the claim text.