Sintered material based on doped chromium oxide

Patent metadata

Field	Value
Publication number	US-9242885-B2
Application number	US-201213985649-A
Country	US
Kind code	B2
Filing date	Feb 9, 2012
Priority date	Feb 15, 2011
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

A sintered product having an average chemical composition such that, in weight percentages on the basis of the oxides: Cr 2 O 3 =80.0-99.0%; 0.5%≦TiO 2 ≦9.0%; 0.2%≦MgO≦3.0%; and ZrO 2 ≦5.0%, provided that the ratio of TiO 2 /MgO is between 1.5 and 9.0 and the molar ratio TiO 2 /Cr 2 O 3 is less than 0.12.

First claim

The invention claimed is:

1. Sintered product having an average chemical composition such that, in percentages by weight on the basis of the oxides:
Cr 2 O 3 : 81.0-99.0%
0.5%≦TiO 2 ≦9.0%
0.15%≦MgO≦3.0%
ZrO 2 ≦5.0%

provided that the TiO 2 /MgO molar ratio is between 1.5 and 9.0 and the TiO 2 /Cr 2 O 3 molar ratio is less than 0.12, the sintered product comprising less than 2.0%, by weight on the basis of the oxides, of oxides other than Cr 2 O 3 , TiO 2 , MgO, and ZrO 2 .

2. Product according to claim 1 , the bulk density of the product being greater than 4.0 g/cm 3 .

3. Product according to claim 1 , in which the molar ratios meet at least one of the following conditions (i)-(iii):
(i) TiO 2 /MgO>2.5 and TiO 2 /MgO<9.0,
(ii) TiO 2 /MgO≧1.5 and TiO 2 /MgO<8.0,
(iii) TiO 2 /MgO>2.5, and/or TiO 2 /MgO<8.0.

4. Product according to claim 1 , comprising 0.5 to 5.0% ZrO 2 , as a percentage by weight on the basis of the oxides.

5. Product according to claim 1 , the MgO content being greater than 0.3% and less than 1.5%, or the MgO content being greater than 0.3% and less than or equal to 3.0%, or the MgO content being greater than 0.15% and less than 1.5%, as a percentage by weight on the basis of the oxides.

6. Product according to claim 1 , comprising less than 1.0% by weight on the basis of the oxides of oxides other than Cr 2 O 3 , TiO 2 , MgO and ZrO 2 .

7. Product according to claim 1 , manufactured from a feedstock in which at least the oxides Cr 2 O 3 , MgO and TiO 2 are present in the form of particles of said oxides and optionally grog particles of said oxides, said particles together forming a powder blend having a median size of less than 50 μm.

8. Product according to claim 7 , manufactured from a feedstock in which at least the oxides Cr 2 O 3 , MgO and TiO 2 are present in the form of particles of said oxides and optionally grog particles of said oxides, said particles together forming a powder blend having a median size of less than 10 μm.

9. Product according to claim 1 , manufactured from a feedstock comprising at least 10% grog as a percentage by weight on the basis of the oxides.

10. Product according to claim 1 , manufactured from a feedstock in which the oxide powders and optionally the grog each have a median size of less than 150 μm.

11. Product according to claim 1 , in which Fe 2 O 3 <0.2% and/or P 2 O 5 <1% and/or SiO 2 <0.5%.

12. Product according to claim 1 , in the form of a block having a mass of greater than 5 kg.

13. Installation comprising a product according to claim 1 , said product being placed in a region of said installation where it is likely to come into contact with an oxidizing environment at a temperature above 1000° C. or with flue gas emitted by molten glass.

14. Tank comprising a product according to claim 1 , said product being placed in a region of said tank where it is likely to come into contact with a molten glass.

15. Product according to claim 1 , wherein 0.2%<MgO≦3.0%.

16. Product according to claim 1 , wherein 1.0%<TiO 2 ≦9.0%.

17. Product according to claim 16 , wherein 1.5%<TiO 2 ≦9.0%.

18. Product according to claim 17 , wherein 2.5%<TiO 2 ≦9.0%.

19. Product according to claim 1 having an apparent porosity of less than 10%.

20. Product according to claim 1 , wherein ZrO 2 ≦4.5%.

21. Product according to claim 1 , wherein the molar ratio TiO 2 /MgO is less than 7.0.

22. Product according to claim 6 , comprising less than 0.5% by weight on the basis of the oxides of oxides other than Cr 2 O 3 , TiO 2 , MgO and ZrO 2 .

23. Product according to claim 1 , wherein a content of CaO is less than 0.6%.

24. Product according to claim 1 , obtained by sintering a green part formed from a feedstock comprising at least 10% and less than 50% of grog.

25. Product according to claim 1 , obtained by sintering a green part formed from a feedstock comprising particles comprising at least one of MgTiO 3 , Mg 2 TiO 4 , and MgTi 2 O 5 .

26. Product according to claim 25 , wherein more than 50% by weight of the MgO is supplied in the MgTiO 3 form.

27. Process for manufacturing a sintered product according to claim 1 , comprising the following steps:
a) mixing raw materials to form a feedstock;
b) forming a green part from said feedstock;
c) sintering said green part to obtain a sintered product.

28. Process according to claim 27 , wherein said feedstock comprises particles comprising at least one of MgTiO 3 , Mg 2 TiO 4 , and MgTi 2 O 5 .

29. Process according to claim 27 , wherein the oxides Cr 2 O 3 , TiO 2 and MgO and optionally ZrO 2 are present in the feedstock in the form of particles of said oxides, and optionally grog of said oxides, said particles together forming a powder blend having a median size of less than 50 μm.

Assignees

• Citti Olivier
• Fourcade Julien
• Saint Gobain Ct Recherches

Inventors

• Citti Olivier
• Fourcade Julien

Classifications

• C04B2235/727

  Phosphorus or phosphorus compound content · CPC title

• C04B2235/5427

  millimeter or submillimeter sized, i.e. larger than 0,1 mm · CPC title

• C04B2235/3206

  Magnesium oxides or oxide-forming salts thereof · CPC title

• C04B35/12 Primary

  based on chromium oxide (C04B35/047 and C04B35/105 take precedence) · CPC title

• C04B2235/3236

  Alkaline earth titanates · CPC title