Process for producing a dense ceramic product
AssigneeCommonwealth Scientific and Industrial Research Organisation
InventorsMark Brian Trigg, Chull Hee Oh
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Abstract
A process for the production of dense polycrystalline silicon carbide shaped articles; includes (a) heating a powder compact containing silicon carbide and alumina or a precursor thereof to an intermediate temperature, and maintaining the said intermediate temperature for an extended dwell, and then (b) heating the product of step (a) to a higher temperature for sufficient time to produce a dense polycrystalline silicon carbide product.
Claims24
A process for the production of a dense polycrystalline silicon carbide shaped article, characterized in that the process includes the following steps:
- (a)(i.) forming a powder compact which contains silicon carbide and alumina or a precursor of alumina but excludes boron or boron containing compounds;
- (a)(ii.) heating the powder compact in an inert atmosphere to a temperature between 1400.degree. and 1900.degree. C.;
- (b) maintaining the powder compact in the temperature range between 1400.degree. and 1900.degree. C. in an inert atmosphere for at least 30 minutes and thereafter for a time sufficient to remove unstable inorganic species which adversely affect the densification of the compact;
- and
- (c) heating the product of step (b) to a temperature above 1900.degree. C. in an atmosphere comprising carbon monoxide for at least 10 minutes and thereafter for a time sufficient to produce a dense polycrystalline silicon carbide product.
A process for the production of a dense polycrystalline silicon carbide shaped article, characterized in that the process includes the following steps:
- (a)(i.) forming a powder compact comprising silicon carbide and alumina or a precursor of alumina but excludes boron or boron containing compounds;
- (a)(ii.) heating the powder compact to a temperature between 1400.degree. and 1900.degree. C.;
- (b) maintaining the powder compact in the temperature range of between 1600.degree. and 1900.degree. C. in an atmosphere comprising carbon monoxide, the powder compact being maintained in the temperature range for at least 30 minutes and thereafter for a time sufficient to remove unstable inorganic species which adversely affect the densification of the compact;
- and
- (c) heating the product of step (b) to a temperature above 1900.degree. C. in an atmosphere comprising carbon monoxide for at least 10 minutes to produce a dense polycrystalline silicon carbide product.
A process for the production of a dense polycrystalline silicon carbide shaped article, characterized in that the process includes the following steps:
- (a)(i.) forming a powder compact which comprises silicon carbide and alumina or an alumina precursor but excludes boron or boron containing compounds;
- (a)(ii.) heating the powder compact in an inert atmosphere, to a temperature between 1400.degree. and 1900.degree. C.;
- (b) maintaining the powder compact, in the temperature between 1400.degree. and 1900.degree. C. in a vacuum, said temperature being maintained for at least 30 minutes and thereafter to remove unstable inorganic species which adversely affect the densification of the compact;
- and
- (c) heating the product of step (b) to a temperature above 1900.degree. C. in an atmosphere comprising carbon monoxide for at least 10 minutes, and thereafter for a time sufficient to produce a dense polycrystalline silicon carbide product.
Dependencies are inferred from the claim text.