CASTING COMPOUNDS, COMPOSITE MATERIAL AND CHANNEL SYSTEMS WITH STABILIZING CASTING COMPOUND

Abstract

A formulation for a casting compound is provided that includes a base slip with a proportion between 18% and 36% by weight, quartz glass particles with a proportion between 40% and 70% by weight, and particles of an admixture having at least one multicomponent glass with a proportion between 10% and 40% by weight. The base slip contains water as dispersion medium with a content between 30% and 50% by weight and ultrafine Si0 2 particles colloidally distributed therein with a content between 50% and 70% by weight, and wherein the total water content in the formulation is 10% to 20% by weight. A composite material is also provided that has a largely crystalline Si0 2 matrix and particles of a multicomponent glass embedded therein.

Claims

1. A formulation for a casting compound, comprising: a base slip with a proportion between 18% and 36% by weight; quartz glass particles with a proportion between 40% and 70% by weight; and additional particles of an admixture comprising at least one multicomponent glass with a proportion between 10% and 40% by weight, wherein the base slip comprises water as dispersion medium and ultrafine SiO.sub.2 particles, the water having a content between 30% and 50% by weight, the ultrafine SiO.sub.2 particles being colloidally distributed in the dispersion medium and having a content between 50% and 70% by weight.

2. The formulation of claim 1, wherein the quartz glass particles have a particle size distribution D.sub.50 in a range from 150 ?m to 1000 ?m and/or a particle size distribution D.sub.99 of less than 3000 ?m.

3. The formulation of claim 2, wherein the particle size distribution D.sub.50 is in a range from 200 ?m to 700 ?m and/or the particle size distribution D.sub.99 is less than 800 ?m.

4. The formulation of claim 1, wherein the quartz glass particles and/or the additional particles have a particle size distribution selected from a group consisting of multimodal, bimodal, and trimodal.

5. The formulation of claim 1, wherein the additional particles have a particle size distribution D.sub.50 in a range from 40 to 150 ?m and/or a particle size distribution D.sub.99 of less than 100 ?m.

6. The formulation of claim 5, wherein the particle size distribution D.sub.50 in a range from 60 to 105 ?m and/or a particle size distribution D.sub.99 of less than 70 ?m.

7. The formulation of claim 1, wherein the at least one multicomponent glass comprises a glass selected from a group consisting of borosilicate glass, an aluminosilicate glass, and soda-lime glass.

8. The formulation of claim 1, wherein the glass particles have a size distribution that satisfies an Andreassen equation: $Q_3\left(d\right)={\left(\frac{d}{D}\right)}^q$ $d...\mathrm{particle}\mathrm{size}$ $D...\mathrm{maximum}\mathrm{particle}\mathrm{size}$ $q...\mathrm{distribution}\mathrm{coefficient}$ with a distribution coefficient q<0.3.

9. The formulation of claim 1, wherein the at least one multicomponent glass has a transition temperature Tg<800? C. and/or a processing temperature TVA >700? C.

10. The formulation of claim 1, wherein the at least one multicomponent glass has a transition temperature Tg<600? C. and/or a processing temperature TVA >1150? C.

11. The formulation of claim 1, wherein the formulation is rheopectic at room temperature.

12. A composite material, comprising a sintered SiO.sub.2 matrix and a glassy phase of a multicomponent glass dispersed therein, wherein the glassy phase has a proportion of 18% to 42% by volume, a processing temperature T.sub.VA at which glass of the glassy phase has a viscosity of 10.sup.4 dPas is >700? C.; and a transition temperature of the glass T.sub.G is <800? C.

13. The composite material of claim 12, wherein the processing temperature T.sub.VA of the glass at which the glass has a viscosity of 10.sup.4 dPas is 22 1150? C. and the transition temperature of the glass T.sub.G is <600? C.

14. The composite material of claim 12, wherein the SiO.sub.2 matrix is largely crystalline and the proportion of glassy phases in the SiO.sub.2 matrix is formed essentially by the multicomponent glass, wherein the proportion is 10% to 40% by volume.

15. The composite material of claim 14, wherein the proportion is 18% to 25% by volume.

16. The composite material of claim 12, wherein the sintered SiO.sub.2 matrix comprises cristobalite of at least 60% by volume.

17. The composite material of claim 12, wherein the sintered SiO.sub.2 matrix comprises cristobalite of at least 75% by volume.

18. The composite material of claim 12, wherein the multicomponent glass, prior to sintering, comprises glass particles with a particle size distribution D.sub.50 in a range from 40 to 150 ?m and/or a particle size distribution D.sub.99 of less than 100 ?m.

19. The composite material of claim 12, further comprising an outer region and an inner region, wherein the proportion of the glass phase in the outer region is higher than in the inner region.

20. The composite material of claim 12, further comprising viscoelastic properties at temperatures above a softening temperature of the multicomponent glass.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0063] FIG. 1 is a schematic diagram of the casting compound;

[0064] FIG. 2 is a schematic diagram of a detail from the composite material;

[0065] FIG. 3 is a schematic diagram of an apparatus for transporting glass; and

[0066] FIG. 4 is an enlarged detail of the apparatus shown in FIG. 3.

DETAILED DESCRIPTION

[0067] FIG. 1 shows the schematic diagram of a casting compound 1 in a first working example. The formulation contains the base slip with a proportion between 18% and 36% by weight, quartz glass particles with a proportion between 40% and 70% by weight, and particles of the admixture comprising at least one multicomponent glass with a proportion between 10% and 40% by weight.

[0068] The base slip comprises water as dispersion medium between 30% and 50% by weight, and ultrafine SiO.sub.2 particles or ultrafine SiO.sub.2 grains colloidally distributed therein with a proportion between 50% and 70% by weight, preferably 55 and 65% by weight, most preferably 58% and 62% by weight.

[0069] The total proportion of water in the formulation is 10% to 20% by weight. In the embodiment shown in FIG. 1 multicomponent glass 2 used is a borosilicate glass. The median particle size D.sub.50 of the multicomponent glass 2 in the working example shown in FIG. 1 is in the range from 60 to 105 ?m. The quartz glass particles have a median particle size D.sub.50 in the range from 200 ?m to 700 ?m. The particle size distributions of multicomponent glass 2 and quartz glass 3 are preferably chosen such that the mixture can be described by an Andreassen equation with a q value of less than 0.3. The multicomponent glass 2 has a glass transition temperature T.sub.G <800? C., preferably <750? C., more preferably <600? C., and/or a processing temperature TVA >700? C., preferably >900? C. and more preferably >1150? C. In one embodiment, the multicomponent glass 2 has a glass transition temperature T.sub.G in the range from 630 to 800? C.

[0070] FIG. 2 shows a schematic of the composite material 5 produced by sintering the formulation shown in FIG. 1. The composite material 5 here may have pores (not shown in FIG. 2). The sintering transformed the quartz glass particles 3 and the colloidally distributed SiO.sub.2 4 to a quartz matrix 6. The quartz matrix 6 is at least partly crystalline and has a cristobalite structure as crystal structure. The proportion of cristobalite in the quartz matrix 6 in the working example shown in FIG. 2 is 75% to 82% by volume. Glass phases 2 are dispersed in the quartz matrix 6. The glass phases 2 are accommodated by the quartz matrix 6 and fill the pores of the quartz matrix 6 here. The softening point of the multicomponent glass 2 here is preferably below the temperature at which the composite material 5 is used, for example when the composite material 5 is used in an apparatus for glass melting. By virtue of the glass phases 2 that are thus viscous in a corresponding use, the composite material 5 has viscoelastic properties at operating temperature. When the composite material 5 is used in apparatuses comprising metallic components, these viscoelastic properties allow effective dissipation of mechanical stresses that arise from the different coefficients of thermal expansion of the materials used.

[0071] If the composite material 5 is produced by sintering the casting compound 1 on contact with a component having high thermal conductivity, for example a metallic component, the composite material 5 may have an inhomogeneous distribution of the glass phases 2. This is shown schematically in FIG. 3. FIG. 3 here shows a cross section through a composite material 5 in which a metallic component 7 is embedded. The metallic component 7 in the working example shown in FIG. 3 is a stainless steel tube having the outer shell surfaces 70. The outer shell surfaces 70 are fully surrounded by the composite material 5. The composite material 5 here has regions having different contents of glass phases. The different content of glass phases is represented by the individual regions 51, 50 and 30. The composite material here, in the regions that are in contact with the shell surfaces 70 of the metal tube 7, has a higher content of glass phases than the outer regions 51. Thus, the working example shown in FIG. 3 has a gradient with regard to the content of glass phases. This is symbolized in FIG. 3 by the arrows 13, where the arrows 13 point in the direction of the higher glass phase content. At the interface of the composite material 5 with the outer shell surfaces 70 of the metal tube 7, a closed glass film 30 is formed. This is adjoined by regions 50 of the composite material 5 having an elevated glass phase concentration compared to the regions 51. The regions 50 and 51 may have a common interface. It is likewise possible that the two regions 50, 51 merge continuously into one another.

[0072] FIG. 4 shows a schematic diagram of an apparatus 12 in the form of a channel or feeder system for transportation of glass melts using a working example. The apparatus 12 comprises the composite material 5, and a metal tube 7 embedded in the composite material 5. The flow of glass through the metal tube 7 is represented by the arrow 8. The composite material 5 forms the supporting structure of the apparatus 12. By virtue of its high mechanical stability of the composite material 5, it is also possible to achieve constructions with vertical sections. It is additionally possible for further elements such as measuring or heating elements to be accommodated in the composite material 5. In the working example shown in FIG. 4, the composite material 5 also accommodates the temperature sensors 10 and a stirred crucible 11. The apparatus 12, for improvement of thermal insulation, additionally has the insulation layers 9 that surround the outsides of the composite material.