Fire-resistant ceramic mix and fire resistant ceramic product

Abstract

The invention concerns a refractory ceramic batch as well as a refractory ceramic product.

Claims

1. A refractory ceramic batch based on magnesia, having the following characteristics: 1 the batch comprising: 1.1.1 at least 70% by weight of magnesia, 1.1.2 at least one plasticizer wherein the at least one plasticizer comprises at least one of magnesia spinel, hercynite, galaxite or jacobsite, as well as 1.1.3 at least one phosphorus-comprising component; 1.2 wherein the batch comprises proportions of CaO and SiO.sub.2 wherein the mole fraction of CaO in the batch is more than twice the mole fraction of SiO.sub.2 in the batch.

2. The batch as claimed in claim 1, in which the proportion by weight of phosphorus in the batch, calculated as P.sub.2O.sub.5, is at most 50% above or below the value for the fraction by weight of P.sub.2O.sub.5, calculated in accordance with the following formula (I): $\begin{array}{cc}{P}_2{O}_{5\mathrm{ideal}}\left[\mathrm{weight}\%\right]=\left({\mathrm{CaO}}_{\mathrm{free}}\right).Math.\frac{b}{a}& \left(I\right)\end{array}$ wherein said percentage of at most 50% is with respect to said value and wherein CaO.sub.free is the quantity of free CaO in the batch as a weight %, which is determined using the following formula: $\begin{array}{cc}{\mathrm{CaO}}_{\mathrm{free}}=x-\frac{2.Math.y.Math.c}{s}& \left(\mathrm{II}\right)\end{array}$ with x=proportion of CaO in batch [weight %] y=SiO.sub.2 content in batch [weight %] c=molecular weight of CaO [g/mol]=56 g/mol s=molecular weight of SiO.sub.2 [g/mol]=60.1 g/mol a=fraction of CaO in tricalcium phosphate [weight %]=54.2%, and b=fraction of P.sub.2O.sub.5 in tricalcium phosphate [weight %]=45.8%.

3. The batch as claimed in claim 1, in which the phosphorus comprising component is present in such fractions by weight in the batch that phosphorus, calculated as P.sub.2O.sub.5, is present in the batch in the range from 0.1% to 5%, with respect to the total weight of the batch.

4. The batch as claimed in claim 2, in which the fraction by weight of CaO is in the range 0.2% to 8% by weight with respect to the total weight of the batch.

5. The batch as claimed in claim 2, in which the fraction by weight of SiO.sub.2 is in the range 0.05% to 3% by weight with respect to the total weight of the batch.

6. The batch as claimed in claim 1, in which the fraction by weight of Fe.sub.2O.sub.3 which is not present in the batch in the form of a plasticizer is more than 3% by weight with respect to the total weight of the batch.

7. The batch as claimed in claim 1, in which the fraction by weight of magnesia is in the range 70% to 97% by weight with respect to the total weight of the batch.

8. The batch as claimed in claim 1, in which the fraction by weight of plasticizer is in the range 2% to 30% by weight with respect to the total weight of the batch.

9. A shaped refractory ceramic product which is produced from a batch as claimed in claim 1 by ceramic firing and which comprises the following phases: magnesia, at least one mineral phase which has been formed from at least one plasticizer, as well as at least one of the following phases: tricalcium phosphate or a calcium-silicate-phosphate solid solution.

10. The product as claimed in claim 9, in which the fraction by weight of tricalcium phosphate is in the range 0.5% to 6% by weight with respect to the total weight of the product.

11. The product as claimed in claim 9, in which the fraction by weight of calcium-silicate-phosphate solid solution is in the range 0.5% to 8% by weight with respect to the total weight of the product.

12. The product as claimed in claim 9, having a T.sub.0 value of more than 1,325 C.

13. The product as claimed in claim 9, having at least one of the following properties: modulus of elasticity: <70 GPa, <60 GPa, <50 GPa or <40 GPa, nominal notched-bar tensile strength: <10 MPa, <9 MPa, <8 MPa or <7 MPa.

14. The batch as claimed in claim 2, in which the phosphorus comprising component is present in such fractions by weight in the batch that phosphorus, calculated as P.sub.2O.sub.5, is present in the batch in the range from 0.1% to 5%, with respect to the total weight of the batch.

15. The batch as claimed in claim 1, in which the fraction by weight of CaO is in the range 0.2% to 8% by weight with respect to the total weight of the batch.

16. The batch as claimed in claim 1, in which the fraction by weight of SiO.sub.2 is in the range 0.05% to 3% by weight with respect to the total weight of the batch.

17. The batch as claimed in claim 2, in which the fraction by weight of Fe.sub.2O.sub.3 which is not present in the batch in the form of a plasticizer is more than 3% by weight with respect to the total weight of the batch.

18. The batch as claimed in claim 2, in which the fraction by weight of magnesia is in the range 70% to 97% by weight with respect to the total weight of the batch.

19. The batch as claimed in claim 2, in which the fraction by weight of plasticizer is in the range 2% to 30% by weight with respect to the total weight of the batch.

20. A shaped refractory ceramic product which is produced from a batch as claimed in claim 2 by ceramic firing and which comprises the following phases: magnesia, at least one mineral phase which has been formed from at least one plasticizer, as well as at least one of the following phases: tricalcium phosphate or a calcium-silicate-phosphate solid solution.

Description

(1) In the accompanying drawings,

(2) FIG. 1 shows a scanning electron microscope image of a section of a refractory brick from the prior art, and

(3) FIGS. 2 to 5 show scanning electron microscope images of sections of products in accordance with the invention.

(4) In FIGS. 1 to 5, the white bars in the lower centre of the image each correspond to a length of 10 m.

(5) The section of the refractory brick of FIG. 1 is formed from a batch which comprises the components magnesia, spinel and hercynite. In FIG. 1, the dicalcium silicate phase 2 and ferrite phase 3 can be seen.

(6) The products of FIGS. 2 to 5, based on a batch which additionally comprises a phosphorus-comprising component, are in contrast to the refractory brick of FIG. 1. In this regard, in addition to the magnesia, spinel, hercynite, dicalcium silicate 2 and ferrite 3 phases, the bricks of FIGS. 2 to 5 exhibit a further phase with reference numeral 1, of a calcium-silicate-phosphate solid solution.