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Paramétrages

Paramétrages

1. WO1995033700 - PROCEDE DE PRODUCTION DE CERAMIQUE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

CLAIMS

1. A process for the produαion of O'-SiAlON from silicon metal, nitrogen, and clay, the process comprising heating the silicon metal and the clay in a flowing nitrogen atmosphere to a temperature sufficient to reaα the components to form O'-SiAlON and wherein the clay participates in the reaαion as a source of aluminium and silicon.

. 1.. The process according to claim 1 wherein the clay is the sole source of aluminium.

3. The process according to claim 1 or claim 2 comprising dehydroxylating the clay and mixing the dehydroxylated clay with the silicon metal and heating the combination under a flowing nitrogen atmosphere to a temperature sufficient to reaα the mixture to form O'-SiAlON.

4. The process according to any one of the preceding claims further comprising the addition of silica.

5. The process according to any one of the preceding claims wherein the clay is a hydrated layer aluminosilicate mineral.

6. The process according to claim 5 wherein the clay is a kaolin, montmorillonite, pyrophyllite, bentonite or halloysite clay.

7. The process according to claim 3 wherein the clay is dehydroxylated by precalcining.

8. The process according to claim 3 wherein the clay is dehydroxylated by heating the clay to a temperature between about 500°C and about 800°C.

9. The process according to any one of the preceding claims wherein the components of the mixture are present as fine powders.

10. The process according to any one of the preceding claims wherein the clay is present in an amount of between about 5% and about 60% by weight.

11. The process according to claim 10 wherein the clay is present in an amount of between about 20% and about 60% by weight.

12. The process according to any one of the preceding claims including by weight, about 20% to about 50% clay, 0% to about 25% silica and about 40% to about 60% silicon metal.

13. The process according to any one of claims 4 to 12 including about 30% to about 40% clay, about 10% to about 20% silica, and about 40% to about 55% silicon metal.

14. The process according to any one of the preceding claims wherein the flowing N2 atmosphere comprises < 0.5% oxygen and 0.5% water vapour.

15. The process according to any one of claims 1 to 13 wherein the flowing N2 atmosphere comprises < 10 ppm 02 and < 25 ppm water vapour.

16. The process according to any one of the preceding claims wherein the mixture is heated to between about 1100°C and about 1900°C.

17. The process according to any one of the preceding claims wherein the heating rate is between about 0.2°C and about 10°C per minute.

18. The process according to claim 17 wherein the heating rate is between about 2°C and about 5°C per minute.

19. The process according to any one of the preceding claims wherein the components are held at the required temperature for between about 4 and about 60 hours.

20. The process according to any one of the preceding claims wherein additive compounds are included to enhance the reaαion and/or to promote sintering.

21. The process according to claim 20 wherein the additive compounds are seleαed from Y203, Fe304, Zr02, ZrSi04, MgO and /3-SiAlON.

22. The process according to any one of the preceding claims further comprising the addition of a ceramic material to produce a composite ceramic including O'-SiAlON.

23. The process according to claim 22 wherein the added ceramic material is seleαed from silicon carbide (SiC), alumina (Al203), silicon nitride (Si3N4), SiAlON, zirconia (Zr02), zircon (ZrSi04) and silica (Si02).

24. The process according to claim 22 or claim 23 wherein the ceramic material is coarser than the other mixture components which reaα to form the O'- SiAlON.

25. The process according to any one of claims 22 to 24 wherein the ceramic material is present in an amount of up to about 75% by weight of the mixture.

26. The process according to claim 25 wherein the ceramic material is present in an amount of between about 40% and about 70% by weight of the mixture.

27. A process for the produαion of O'-SiAlON from a component mixture comprising, by weight, 40%-60% silicon metal, 20%-45% clay, and 10%-25% silica, the process comprising the steps of:

(a) dehydroxylating the clay prior to inclusion in the component mixture;

(b) heating the component mixture at a rate of 1°C to 6°C per minute, to a temperature of between substantially 1300°C to 1900°C under a flowing N2 atmosphere having < 0.5% oxygen and < 0.5% water vapour;

(c) holding the temperature between 1300°C and 1900°C for up to 12 hours; and

(d) recovering the produα.

28. A process for the produαion of a composite ceramic material including O'- SiAlON from a mixture of components comprising a ceramic material, and an O'-SiAlON forming combination of silicon metal, clay and nitrogen wherein the process comprises heating the ceramic material, silicon metal and clay in a flowing nitrogen atmosphere to a temperature sufficient to form the O'-SiAlON composite ceramic and wherein the clay participates in the reaαion as a source of aluminium and silicon.

29. The process according to claim 28 wherein the O'-SiAlON forming combination further comprises silica.

30. The process according to claim 18 or claim 29 wherein the clay is the sole source of aluminium for the produαion of O'-SiAlON.

31. The process according to claim 18 or 19 wherein the ceramic material is selected from silicon carbide (SiC), alumina (Al203), silicon nitride (Si3N4), SiAlON, zirconia (Zr02), zircon (ZrSi04) and silica (Si02).

32. A process for the produαion of a composite ceramic including O'-SiAlON from a mixture of components comprising, by weight, up to 75% of a ceramic material and 25% or more of an O'-SiAlON forming mixture, wherein the O'- SiAlON forming mixture comprises, by weight, 40%-60% silicon metal, 20%- 45% clay, and 10%-25% silica, the process comprising the steps of:

(a) heating the component mixture at a rate of between substantially 1°C to 6°C per minute, to a temperature of between substantially 1300°C to 1900°C under a flowing N2 atmosphere having < 0.5% oxygen and < 0.5% water vapour;

(b) holding the temperature between 1300°C and 1900°C for up to 12 hours; and (c) recovering the produα.

33. An O'-SiAlON containing produα when produced by the process of any one of the preceding claims.