Refractory ceramic batch and method for producing a refractory ceramic product

Abstract

This invention relates to a refractory ceramic batch and to a method for producing a refractory ceramic product.

Claims

1. A refractory ceramic batch comprising the following features: 1.1 the batch comprises the following components 1.1.1 a refractory basic component; 1.1.2 a binder in the form of silica sol; 1.1.3 an alcoholic component in the form of one or more polyvalent alcohols; 1.2 the silica sol is present in the form of a colloidal suspension of polysilicic acid in water; 1.3 the mass ratio of the refractory basic component to polysilicic acid is at least 10 and at most 55; 1.4 the polyvalent alcohols are present in the form of one or more of the following polyvalent alcohols: one or more divalent alcohols or one or more trivalent alcohols.

2. The batch according to claim 1, wherein the mass ratio of the refractory basic component to polysilicic acid is at least 16 and at most 48.

3. The batch according to claim 1, wherein the mass ratio of the refractory basic component to polysilicic acid is at least 19 and at most 40.

4. The batch according to claim 1, wherein the mass ratio of the refractory basic component to polysilicic acid is at least 24 and at most 34.

5. The batch according to claim 1, wherein the mass ratio of the refractory basic component to silica sol is at least 5 and at most 25.

6. The batch according to claim 1, with polyvalent alcohols in the form of one or more divalent alcohols.

7. The batch according to claim 1 with divalent alcohols in the form of at least one of the following divalent alcohols: monoethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol or dipropylene glycol.

8. The batch according to claim 1, with divalent alcohols in the form of at least one of the following divalent alcohols: monoethylene glycol or diethylene glycol.

9. The batch according to claim 1, wherein the mass ratio of the polysilicic acid to alcoholic component is at least 3 and at most 16.

10. The batch according to claim 1, wherein the refractory basic component consists of one or more raw materials on the basis of at least one of the following substances: SiO.sub.2, Al.sub.2O.sub.3, ZrO.sub.2, Cr.sub.2O.sub.3 or SiC.

11. The batch according to claim 1, wherein the refractory basic component consists to an extent of at least 90 mass % of one or more of the following substances: SiO.sub.2, Al.sub.2O.sub.3, ZrO.sub.2, Cr.sub.2O.sub.3 or SiC.

12. A method for producing a refractory ceramic product, said method comprising the following features: 12.1 providing a batch, the batch comprises: a refractory basic component; a binder in the form of silica sol; an alcoholic component in the form of one or more polyvalent alcohols; wherein the silica sol is present in the form of a colloidal suspension of polysilicic acid in water; and wherein the mass ratio of the refractory basic component to polysilicic acid is at least 10 and at most 55; wherein the polyvalent alcohols are present in the form of one or more of the following polyvalent alcohols: one or more divalent alcohols or one or more trivalent alcohols; and 12.2 heating the batch to form a refractory ceramic product.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows drying curves for batches according to the invention in accordance with practical examples 1 to 4 and the drying curve for a batch not according to the invention.

DETAILED DESCRIPTION

(2) The batches according to practical examples 1 to 4 consisted in each case of the following components: a refractory basic component, a binder in the form of silica sol, an alcoholic component in the form of monoethylene glycol or diethylene glycol, and fibres.

(3) The refractory basic component consisted in each case of the following refractory ceramic raw materials in the following mass proportions, in each case in relation to the total mass of the refractory basic component:

(4) fireclay (up to 6.30 mm): 82 mass %;

(5) calcined alumina: 16 mass %;

(6) microsilica: 2 mass %.

(7) The fibres were provided in the form of polypropylene fibres in a mass proportion of 0.05 mass % in relation to the total mass of the refractory basic component (without the polypropylene fibres).

(8) Furthermore, silica sol was present in the batches according to practical examples 1 to 4 in a mass proportion of 9.5 mass % in relation to the total mass of the refractory basic component (without the silica sol). The silica sol was present in the form of a colloidal suspension of polysilicic acid in water. The mass proportion of polysilicic acid in the silica sol, in relation to the total mass of the silica sol, was 40 mass %. The mass ratio of the refractory basic component to polysilicic acid was therefore 26.32.

(9) Based on the mass of the refractory basic component, the polysilicic acid was therefore present in the batch in a proportion of 3.8 mass %.

(10) Furthermore, the mass ratio of the refractory basic component to silica sol was therefore 10.53.

(11) The batches according to practical examples 1 to 4 differed in respect of the type and proportion of alcoholic component present therein.

(12) In the batches according to practical examples 1 and 2, an alcoholic component in the form of monoethylene glycol was present, whereas in practical examples 3 and 4 an alcoholic component in the form of diethylene glycol was provided.

(13) In order to achieve the most uniform distribution possible of the alcoholic component over each separate batch, the alcoholic component was mixed with the silica sol before the silica sol was then mixed with the further components to form the batches according to the practical examples.

(14) In accordance with practical example 1 the monoethylene glycol was present dissolved in the silica sol in a proportion of 5 mass % in relation to the mass of the silica sol without the monoethylene glycol. This resulted in a mass ratio of polysilicic acid to monoethylene glycol in the batch of 8.

(15) In accordance with practical example 2 the monoethylene glycol was present dissolved in the silica sol in a proportion of 10 mass % in relation to the mass of the silica sol without the monoethylene glycol. This resulted in a mass ratio of polysilicic acid to monoethylene glycol of 4.

(16) In accordance with practical example 3 the diethylene glycol was present dissolved in the silica sol in a proportion of 5 mass % in relation to the mass of the silica sol without the diethylene glycol. This resulted in a mass ratio of polysilicic acid to diethylene glycol in the batch of 8.

(17) Lastly, in accordance with practical example 4 the diethylene glycol was present dissolved in the silica sol in a proportion of 10 mass % in relation to the mass of the silica sol without the diethylene glycol. This resulted in a mass ratio of polysilicic acid to diethylene glycol of 4.

(18) The accordingly formulated batches were mixed thoroughly and then heated with a uniform heating rate of approximately 1° C. per minute to approximately 400° C.

(19) The corresponding drying curves for the batches according to the above-described practical examples 1 to 4 are shown in FIG. 1. Here, the temperature reached is plotted on the abscissa and the weight loss of the batch upon reaching the temperature specified on the abscissa, in relation to the total mass of the volatile constituents of the batch, is plotted on the ordinate. The total weight loss was standardised to 100%.

(20) It can be clearly seen that all four batches according to practical examples 1 to 4 registered approximately 90% of their weight loss up to a temperature of approximately 230° C. This is attributed to the fact that the majority of the volatile components of the silica sol volatilised in vapour form up to this temperature.

(21) For comparison of the drying properties of the batches according to practical examples 1 to 4 with a batch according to the prior art, a further batch was produced which corresponded largely to the batch according to practical examples 1 to 4, but with the sole difference that the batch according to the comparative example did not comprise an alcoholic component.

(22) As can be seen from the drying curve for this batch in FIG. 1 (denoted by “prior art”), this batch registered approximately 90% of its weight loss already up to a temperature of approximately 160° C.

(23) In the event of heating, the batches according to the invention according to practical examples 1 to 4 thus release the majority of their volatilisable constituents of the binder more slowly than the batch according to the comparative example, whereby, in the batches according to the invention according to practical examples 1 to 4, the risk of damage to the batches or the refractory ceramic products to be produced therefrom is significantly reduced.