Method of preparing sialon products
AssigneeSociete Europeenne des Produits Refractaires
InventorsRene A. Paris, Therese Grollier-Baron
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Abstract
The invention relates to a method of preparing a product containing, as a single crystalline phase, a solid solution or .beta.'-sialon type having the general formula Si.sub.6-Z Al.sub.Z O.sub.Z N.sub.8-Z where Z=1 to 4, which comprises heating in a nitrogen atmosphere, at 1400.degree.-1600.degree. C., agglomerated elements obtained by drying a paste comprising a silico-aluminous material, such as kaolinitic clay, carbon, and a pore-generating agent comprised of fine particles of a ligneous material, such as sawdust or a powder of olive stones.
Claims12
A method of preparing .beta.'-sialon products which contain as a single crystalline phase a solid solution of .beta.'-sialon having the general formula Si.sub.6-z Al.sub.z N.sub.8-z O.sub.z, where z=1 to 4, by the steps comprising
- (1) forming a paste containing a silico-aluminous material, carbon and fine particles of a ligneous pore-forming agent;
- said ligneous pore-forming agent being present in said paste in an amount of 8 to 18% by weight of the combined weights of the silico-aluminous material, the carbon and the ligneous pore-forming agent;
- said carbon, when considered together with the carbon contained in the ligneous pore-forming agent, being present in said paste in an amount at least equal to the stoichiometric amount needed for satisfying the equation:
- ##EQU2## where Z=1 to 4;
- (2) forming the paste formed in step (1) into shaped elements;
- (3) drying the shaped elements formed in step (2);
- and,
- (4) heating the shaped elements which have been dried in step (3) in a nitrogen atmosphere and at temperatures of between 1400.degree. C. and 1600.degree. C. to form the .beta.'-sialon products.
A method of forming a refractory article which comprises
- (1) forming a paste containing a silico-aluminous material, carbon and fine particles of a ligneous pore-forming agent;
- said ligneous pore-forming agent being present in said paste in an amount of 8 to 18% by weight of the combined weights of the silico-aluminous material, the carbon and the ligneous pore-forming agent;
- said carbon, when considered together with the carbon contained in the ligneous pore-forming agent, being present in said paste in an amount at least equal to the stoichiometric amount needed for satisfying the equation:
- ##EQU3## where Z=1 to 4;
- (2) forming the paste formed in step (1) into shaped elements;
- (3) drying the shaped elements formed in step (2);
- (4) heating the shaped elements which have been dried in step (3) in a nitrogen atmosphere and at temperatures of between 1400.degree. C. to 1600.degree. C. to form products which contain as a single crystalline phase a solid solution of .beta.'-sialon having the general formula Si.sub.6-Z Al.sub.Z N.sub.8-Z O.sub.Z, where Z=1 to 4;
- (5) crushing the products formed in step (4) to form a powder;
- (6) forming the powder formed in step (5) into a desired shape;
- and
- (7) sintering the shape formed in step (6) in the absence of elevated pressure to form the refractory article.
Dependencies are inferred from the claim text.