Granule for producing a fire-proof product, use of such granules, fire-proof product, method for producing a fire-resistant product, and product produced by said method

Abstract

The invention relates to a grain for production of a refractory product, to the use of such grains, to a refractory product, to a process for producing a refractory product and to a refractory product produced thereby.

Claims

1. A refractory product, having a use temperature exceeding 600° C., comprising a grain, said grain comprising zirconium carbonitride and zirconium dioxide, wherein said zirconium dioxide is in the form of a room temperature metastable mineral phase in cubic modification.

2. The product as claimed in claim 1 in the form of a wearing part in continuous steel casting.

3. The product as claimed in claim 2 in the form of a slide plate, a monoblock stopper, a nozzle, an immersed tube or a submerged entry nozzle.

4. The product as claimed in claim 1, wherein zirconium carbonitride is concentrated in the edge region of the grain.

5. The product as claimed in claim 1, wherein the grain has a proportion of zirconium carbonitride in the range from 1% to 99% by mass.

6. The product as claimed in claim 1, wherein the grain has a proportion of zirconium dioxide in the range from 1% to 99% by mass.

7. The product as claimed in claim 1, wherein the grain comprises the following elements in the following proportions by mass: zirconium: 5-97%; oxygen: 1-50%; nitrogen: 1-30%; carbon: 1-30%; hafnium: 0-4%; calcium: 0-8%; yttrium: 0-8%; iron: 0-2%; aluminum: 0-2%; and silicon: 0-2%.

8. A process for producing a refractory product, having a use temperature exceeding 600° C., comprising the following steps: providing grains for production of a refractory product, wherein the grains comprise zirconium carbonitride and zirconium dioxide, wherein said zirconium dioxide is in the form of a room temperature metastable mineral phase in cubic modification; combining the grains with further refractory raw materials; pressing a shaped body from the grains and the further refractory raw materials; and firing the shaped body to give a refractory product.

9. A refractory product having a use temperature exceeding 600° C., the refractory product produced by the following process: providing grains for production of a refractory product, wherein said grains comprise zirconium carbonitride and zirconium dioxide, wherein said zirconium dioxide is in the form of a room temperature metastable mineral phase in cubic modification; combining the grains with further refractory raw materials; pressing a shaped body from the grains and the further refractory raw materials; and firing the shaped body to give a refractory product.

Description

(1) Two images of polished sections of the grains produced as above according to samples 1 and 2 are appended as figures. The figures show:

(2) FIG. 1 a reflected light microscopy image of a polished section of sample 1,

(3) FIG. 2 a detail of the polished section of FIG. 1 in a scanning electron micrograph,

(4) FIG. 3 a reflected light microscopy image of a polished section of sample 2 and

(5) FIG. 4 a detail of the polished section of FIG. 3 in a scanning electron micrograph.

(6) The black bar bottom right in FIG. 1 corresponds to a length of 200 μm. In FIG. 1, it is possible to see a grain of the invention identified by reference numeral 1, having a size of about 520×380 μm. The grain 1 is embedded into a carbon matrix 2 that has formed from the carbon black during the firing.

(7) Further grains of the invention that have formed during the firing are identified by reference numerals 3 and 4.

(8) The average elemental composition of the grain 1 is, for instance, as follows, where the proportion by mass of the respective element is reported in relation to the total mass of the grain 1:

(9) zirconium: about 65.0%

(10) oxygen: about 18.0%;

(11) nitrogen: about 6.0%

(12) carbon: about 7.0%;

(13) calcium: about 2.5%

(14) magnesium: 0%;

(15) yttrium: 0%;

(16) iron: <0.5%;

(17) aluminum: <0.5%.

(18) However, the proportions by mass of the respective elements are not distributed homogeneously over the volume of the grain 1. Instead, zirconium carbonitride is concentrated in the edge region of the grain 1. This concentration of zirconium carbonitride in the edge region of the grain 1 is reflected, inter alia, in the concentration of the element carbon, which is significantly higher in the edge region of the grain 1 than in the interior of the grain 1.

(19) This concentration of zirconium carbonitride is reflected visually in the edge region of the grain 1 in FIGS. 1 and 2 in a thin seam 5 that completely surrounds the grain 1 at the edge.

(20) The proportion of zirconium carbonitride in the grain 1 is about 5% by mass and the proportion of cubic zirconium dioxide is about 90% by mass, based in each case on the total mass of the grain 1. The residual phase component of the grain 1 is formed essentially from melt phases based on the oxides CaO, SiO.sub.2 and ZrO.sub.2.

(21) The black bar bottom right in FIG. 3 corresponds to a length of 100 μm. In FIG. 3, it is possible to see a grain of the invention identified by reference numeral 11, having a size of about 700×325 μm. The grain 11 is embedded into a carbon matrix 12 that has formed from the carbon black during the firing.

(22) The average elemental composition of the grain 11 is as follows, where the proportion by mass of the respective element is reported in relation to the total mass of the grain 11:

(23) zirconium: about 64.0%

(24) oxygen: about 17.0%;

(25) nitrogen: about 8.0%

(26) carbon: about 9.0%;

(27) calcium: about 1.0%

(28) magnesium: 0%;

(29) yttrium: 0%;

(30) iron: <0.5%;

(31) aluminum: <0.5%.

(32) However, the proportions by mass of the respective elements are not distributed homogeneously over the volume of the grain 11. Instead, zirconium carbonitride is concentrated in the edge region of the grain 11. This concentration of zirconium carbonitride in the edge region of the grain 11 is reflected, inter alia, in the concentration of the element carbon, which is significantly higher in the edge region of the grain 11 than in the interior of the grain 11.

(33) This concentration of zirconium carbonitride is reflected visually in the edge region of the grain 11 in FIGS. 3 and 4 in a thin seam 15 that completely surrounds the grain 11 at the edge.

(34) The proportion of zirconium carbonitride in the grain 11 is about 23% by mass and the proportion of cubic zirconium dioxide is about 72% by mass, based in each case on the total mass of the grain 11. The residual phase component of the grain 11 is formed essentially from melt phases based on the oxides CaO, SiO.sub.2 and ZrO.sub.2.