Methods for producing silicon carbide whisker-reinforced refractory composition

1. A method of forming a monolithic refractory composition, the method comprising:

(a) providing a particulate refractory composition comprising:

(i) 2 to 90 mass-% alumina, aluminosilicate or mixtures thereof;

(ii) 2 to 70 mass-% silicon carbide;

(iii) 2 to 10 mass-% carbon;

(iv) 1 to 10 mass-% silicon powder; and

(v) 1 to 3 mass-% microsilica;

(b) adding an amount of water to the particulate refractory composition to form a uniform mixture;

(c) allowing the uniform mixture to set;

(d) heat-treating said set mixture at a temperature no higher than 1200° C. under atmospheric conditions to form the monolithic refractory composition; and

(e) heat-treating the monolithic refractory composition to form silicon carbide whiskers within the monolithic refractory composition.

2. The method according to claim 1 , wherein in step (a), the particulate refractory composition further comprises up to 5 mass-% ferrosilicon.

3. The method according to claim 1 , wherein in step (a), the particulate refractory composition further comprises up to 5 mass-% cement.

4. The method according to claim 1 , wherein said step (e) is carried out by contacting said monolithic composition obtained at the end of step (d) with a molten metal.

5. The method according to claim 1 , wherein said step (e) of heat-treating is carried out at a temperature of up to 1600° C.

6. The method according to claim 1 , wherein step (b) comprises applying the uniform mixture to a vessel by casting, ramming, gunning, or spray casting before allowing the uniform mixture to set.

7. The method according to claim 1 , wherein the particulate refractory composition of step (a) comprises from 5 to 50 mass-% silicon carbide, on the basis of the total mass of the particulate refractory composition.

8. The method according to claim 1 , wherein the particulate refractory composition of step (a) comprises from 1 to 6 mass-% microsilica, on the basis of the total mass of the particulate refractory composition.

9. The method according to claim 1 , wherein the particulate refractory composition of step (a) comprises from 2 to 5 mass-% carbon, on the basis of the total mass of the particulate refractory composition.

10. The method according to claim 1 , wherein the carbon in said particulate refractory composition of step (a) is present as carbon black, graphite, fusible carbon, or a mixture thereof.

11. The method according to claim 1 , wherein the particulate refractory composition of step (a) is substantially free of TiO 2 .

12. The method according to claim 1 , wherein said monolithic refractory composition forms a refractory lining having a thickness ranging from 7 mm to 10 mm.

13. The method according to claim 1 wherein step (e) of heat-treating is repeated at least once.

14. The method according to claim 13 , wherein step (e) of heat-treating is repeated throughout the lifetime of the monolithic refractory composition.

15. The method according to claim 1 , wherein the mass ratio of silicon powder to microsilica in the particulate refractory composition of step (a) ranges from 1:1 to 3:1.

16. A monolithic refractory composition formed by the method according claim 1 .

17. A method of forming a refractory composition, the method comprising:

adding water to a particulate composition to form a mixture, the particulate composition comprising:

(i) 2 to 90 mass-% alumina, aluminosilicate, or a mixture thereof;

(ii) 2 to 70 mass-% silicon carbide;

(iii) 2 to 10 mass-% carbon;

(iv) 1.5 to 4 mass-% silicon powder; and

(v) 1.3 to 2 mass-% microsilica;

depositing the mixture on a surface of a vessel;

applying a first heat treatment to the deposited mixture at a first temperature ranging from 800° C. to 1200° C. to form the refractory composition, the refractory composition forming a refractory lining on the surface of the vessel; and

applying a second heat treatment to the refractory composition at a second temperature higher than the first temperature, the second temperature ranging from 1200° C. to 1600° C., wherein the second heat treatment forms silicon carbide whiskers in the refractory composition.

18. The method of claim 17 , wherein applying the second heat treatment includes contacting an inner surface of the refractory composition with a molten metal.

19. A method of forming a refractory composition, the method comprising:

adding water to a particulate composition to form a mixture, the particulate composition comprising:

(i) 2 to 90 mass-% alumina, aluminosilicate, or a mixture thereof;

(ii) 2 to 70 mass -% silicon carbide;

(iii) 2 to 10 mass-% carbon;

(iv) 1 to 10 mass-% silicon powder; and

(v) 1 to 3 mass-% microsilica;

depositing the mixture on a surface of a vessel:

applying a first heat treatment to the deposited mixture at a first temperature less than 1200° C. to form the refractory composition, wherein the retractory composition has a thickness ranging from 7 mm to 10 mm; and

applying a second heat treatment to the refractory composition by contacting the refractory composition with a molten metal at a second temperature ranging from 1200° C. to 1600° C., wherein the second heat treatment forms silicon carbide whiskers in the refractory composition.

20. The method of claim 19 , wherein the particulate composition comprises 1.5 to 4 mass-% silicon powder with respect to the total mass of the particulate composition, and wherein the mixture comprises 4 to 6 mass-% water with respect to the total mass of the mixture.