DD263750A1 - FIRE-RESISTANT PRODUCT WITH NITRIDER CERAMIC TIE - Google Patents

Abstract

The invention relates to a porous refractory product with nitride ceramic bond. The invention goal is the provision of the product, made of cheap raw materials. Accordingly, the object was to provide the product without the need for very finely divided metals, nitrides and / or oxides are required and the cheap filamentous mineral raw materials can be used. The object was achieved by a porosite refractory product with sialonhaltiger bond, which according to the invention from a mass, in addition grobkoernigen refractory material a binder offset from intercalation compounds of clay minerals, pyrolyzable aluminum compounds and a) silicon carbide and / or its preform; b) carbon or c) polyacrylonitrile contains, is made by thermal nitridation. In the clay minerals components should be stored, which creep below 600C residue-free and / or decompose. In binder formulations, certain ratios of oxides to silicon carbide or carbon must be adhered to. Preferred agents are named; the origin and type of bond performed.

Description

Field of application of the invention

The invention relates to a porous refractory product with nitride ceramic bond based on the refractory materials. Porous ceramic products of the type mentioned are particularly suitable

- As a thermal and electrical insulating material for the melting and firing units in metallurgy and the glass and ceramic industry;

- as a filter for cleaning molten metal: and last but not least

- as a grinding wheel for all heavy grinding work.

| j characteristic of the known technical solutions

Porous ceramic products based on refractory oxides, for example the molten compounds MgO, CaO, Al ₂ O ₃ , ZrO ₂ , dolomite or spinels, and / or carbides, preferably SiC, have long been known and technically introduced. The generalized process of making them consists of the steps

a) preparation of a green mass of the refractory material and a suitable binder;

b) shaping the mass, for example by pressing or casting;

c) solidification of the green compacts by curing and / or cooking.

The properties of the finished porous ceramic body are generally determined by the physical and chemical properties of the refractory material, the binder, the mature bond and the refractory grain / mature bond contact. There is basically a causal relationship between the nature of the binder and the bond formed from it. When the refractory material is predetermined, the chemical composition of the binder and its enveloping properties substantially affect the property pattern of the ceramic product.

Refractory oxides and / or carbides have been proposed and technically introduced: synthetic resin binders, chemical binders and ceramic binders.

Porous ceramic products with resin bond are suitable only for applications in the low temperature range.

In contrast, the chemical bond, for example, the carbon bond, refractory. However, the resistance values of chemically bonded products generally do not meet the requirements imposed on products of the type mentioned in the introduction. Gi. te mechanical nr.i sufficient thermal characteristics of the porous body can be produced in principle with a ceramic bond known are binder offsets, from which a glassy phase is formed in situ; the use of prefabricated glasses has been described. However, this type of binding is limited in use to a few of the refractory materials, for example, Al ₂ Oa or SiC; So it lacks universal application.

Furthermore, glass-bound porous bodies have limited thermal and mechanical characteristics. Also, it is difficult to accomplish the complete wetting of the refractory material by the bond.

Ceramic bonds have been proposed for non-glassy, refractory oxides and / or carbides based on silicon nitride (see, inter alia: US Patent 2,636,828, US Patent 2,752,258, AT-PS 186,180, CH-PS 316.401; No. 3,343,577) or silicon oxynitride (cf., for example, DE-AS 1,282,535, DE-AS 1,671,652, DE-OS 3,113,425, US Pat. No. 3,193,399, US Pat. No. 4,069,058) or both nitrides (US Pat. see, inter alia: DE-AS 1,571,354; DE-OS 3,119,425).

It is known (see, inter alia: GB-PS 1,436,311; AT-PS 343,776; US-PS 4,184,884) that sialons show various advantages over silicon nitride or silicon oxynitride or aluminum nitride resulting from their generally improved physical and chemical properties ,

Considerable efforts have been directed to the development of single-phase ceramic materials containing 80% by mass and more sialon. For this purpose, from very finely divided Si ₃ N ₄ , AIN, Al ₂ O ₃ , SiO ₂ and / or Sinderhilfsmitteln, for example, Y ₂ O ₃ , prepared ceramic masses, these compacted directly or after molding above 1600 ⁰ C. In addition to the high temperature of sintering, this method has the disadvantage of using very fine powders of diamondoid nitrides, the production of which is energy-consuming and time-consuming, as well as being instrument-intensive. Furthermore, the production of sialons by ca-bothermal nitridation of clay mineral-containing raw materials has been proposed (see, inter alia: US Pat. No. 3,960,581, US Pat. No. 4,360,506). As the US-PS 4.360.506 and van DIJEN et. al. (Science of ceramics 12 [1983]; Sprechsaal 117 [1984], p. 627 ff.), The process of carbothermic nitration of clay minerals has several general difficulties; these relate to the gas exchange in the heated mass, the conversion of the mass, the dispersion of the mass constituents and the chemical reaction rate. For the elimination of these difficulties, no satisfactory technical solutions have yet been submitted.

By contrast, little information is available on the use of sialons as a binder in refractory products.

For example, DE-OS 3,119,425 describes refractory bodies with nitride bonding of Si ₃ N ₄ and / or Si ₂ ON ₂ and / or β'-sialon. It is obtained by thermal nitriding a mass offset of refractory, silicon powder and low clay. According to the teaching of US Pat. No. 4,460,528 or DE-OS 3,119,067, it is possible to synthesize a sialon bond from a binder which, in addition to aluminum powder and a silica, contains either little clay or a refractory additive. The main disadvantage of the above proposals is the necessary use of the finest powders of silicon or aluminum.

Object of the invention

The object of the invention is to provide a porous ceramic body of the type mentioned above, largely avoiding the disadvantages and made of fine materials.

Explanation of the essence of the invention

The invention has for its object to provide a porous refractory article having nitridkeramischer binding on the basis of fireproof oxides and / or silicates and / or carbides, without the mass offset of metal powder, such as silicon or aluminum powder, and / or nitride, in particular Si ₃ N ₄ - or AIN powder, and / or pure oxide powder, preferably Al ₂ O ₃ powder must contain. Furthermore, the object was to largely overcome the described, occurring in the carothermic nitridation of clay minerals to sialones difficulties, by Improunp the gas exchange

in the mass and the dispersion of the mass components as well as the reproducible conversion of the mass to a sialonhaltigen body.

The object was achieved by a refractory porous product with nitride ceramic bond on the basis of the refractory materials, which is characterized in that it consists of a ceramic mass, the 50 to 95Ma .-% refractory material with a particle size of 0.1 mm to 10mm , preferably from 0.25 mm to 2.5 mm, and 5 to 50% by weight of binder, the binder having the following composition:

a) - 50 to 60% by weight of one or more of the intercalation compounds of the two-layer and / or three-layer clay minerals,

this number being calculated as the sum of aluminum oxides and silicon oxides of the clay minerals, which can be produced from the siliceous raw materials kaolin and / or clay, whereby the degree of incorporation does not need to be 100%,

20 to 50% by weight of silicon carbide powder having a particle size of more than 99% by mass smaller than 0.005 mm, preferably less than 0.001 mm, and / or the corresponding amount of one or more preforms of silicon carbide,

and additionally

0 to 50% by mass of aluminum compounds calculated as Al ₂ O ₃ , pyrohydrolysable or pyrolyzable, preferably aluminum salts,

with the proviso that the ratio of the sum of the moles of aluminum oxide and silica to the moles of silicon carbide derived from the clay minerals of the siliceous raw material and the pyrohydrolysable or pyrolyzable aluminum compounds is 0.5 to 2.6, or

b) 75 to 90% by weight of one or more of the intercalation compounds of the two-layer and / or three-layer clay minerals,

this number being calculated as the sum of aluminum oxides and silicon oxides of clay minerals, a siliceous raw material whose storage level does not need to be 100%,

From 10 to 25% by mass of carbon in an amorphous and / or crystalline form having a primary particle size of more than 90% by mass, less than 0.001 mm, which may be generated partially or completely in situ,

and additionally

0 to 50 (VIa .-% calculated as Al ₂ O ₃ , pyrohydrolysable or pyrolyzable aluminum compounds, preferably aluminum salts,

with the proviso that the ratio of the sum of the moles of alumina and silica from the clay minerals of the siliceous raw material and the pyrohydrolysable or pyrolyzable aluminum compounds to the carbon given and / or formed in situ is from 0.4 to 1.5, or

c) - 75 to 95% by weight of the silicate raw material contained in the two-layer and / or three-layer clay minerals, this number

is calculated as the sum of aluminum oxides and silicon dioxide of the clay minerals, or preferably one or more of the intercalation compounds of the clay minerals with inorganic and / or organic compounds which decompose below 500 ° C substantially involute or practically free of backwash, or a mixture of clay minerals and intercalation compounds of the clay minerals .

- 50-25% by mass of carbon produced by pyrolysis of an acrylonitrile-based homo- and / or copolymer containing more than 85% acrylonitrile radicals in the chain below 1000 ° C,

and additionally

0 to 50% by weight, calculated as Al ₂ O ₃ , pyrohydrolyzable and pyrolyzable aluminum compounds, preferably Alur .iniumsdlze,

b) provided that the ratio of the sum of the moles of alumina and silica to the moles of polymeric component formed from the clay minerals and the pyrohydrolysable or pyrolyzable aluminum compounds is from 0.4 to 1.5, prepared by thermal nitriding is.

It has surprisingly been found that from the ceramic composition according to the invention after shaping and nitriding at a temperature of 1100 ⁰ C to about 1500 ⁰ C in virtually oxygen-free atmosphere, a porous refractory product einar nitride bond of sialons and / or silicon nitride and / or silicon oxynitride and / or other crystalline phases can be made as a minor component. The produced bodies basically have good strength values with an open porosity of more than 5% and show an excellent chemical resistance. They can be used in general to 1200 ⁰ C.

As silicate raw material for the inventive binder offset all natural and / or processed clays and / or kaolins can be used. Preferably, the silicon raw material should contain at least 70% by mass storable two-layer and / or three-layer clay minerals. A low content of quartz and glass network converters is advantageous. As a result, the glass phase content in the product can generally be kept below 5 to 10% by mass. The intercalation compounds of the clay minerals which are absolutely necessary in the binder offset a) or b) and which are preferably used in the offset c) and their preparation are known per se (see, inter alia: US Pat. Nos. 3,309,211; / 1 / and III ). Preferably, such inorganic and / or organic compounds should be incorporated into the Tonminnrale, which largely volatilize in the subsequent thermal treatment of the mass or decompose virtually residue-free, such as urea, Dimetnylsulfoxid (DMSO), hydrazine, ammonium acetate. A treatment of the intercalation compounds for influencing the wetting behavior iU provided according to the invention (see, for example: US-PS 3,309,211). In a preferred embodiment of the invention, the solvents of the homopolymers and copolymers of acrylonitrile with more than 85% of acrylonitrile radicals in the chain, hereinafter referred to as polyacrylonitrile (PAN), serve as compounds to be incorporated into the clay mineral. Advantageous is the use of DMSO, favorably that of dimethylformamide (DMFA), but also a melt of thiocyanates and thiourea.

The required silicon carbide powder must have a particle size of more than 99Ma .-% less than 0.005mm, preferably less than 0.002mm üufweisen. With regard to the particle size distribution of this offset component, there are otherwise no restrictions.

In an advantageous embodiment of the invention, a preform is used in place of the silicon carbide. Among these font refers to a orqanische silicon compound can be formed from the pyrolysis of between 500 ° C and 1100 ⁰ C in the heated mass virtually homogeneously distributed silicon carbide. Such organic compounds are the known polysilanes or polycarbosilanes. These compounds and their preparation are described inter alia in the following documents: DF-OS 2,236,078; DE-AS 2,618,150; DE-OS 2,628,342; DE-OS 2,651,140; DE-AS 2,660,016; DE-OS 2,716,073; DE-OS 2,803,658; DE-AS 2,848,452; DE-AS 2,921,570; U.S. Patent 4,335,217; U.S. Patent 4,482,669. Another suitable preform of silicon carbide are the silazanes known per se (cf., inter alia: DE-OS 2,218,960; DE-OS 2,243,527). The silicon nitride, which likewise forms in the pyrolysis of the silazanes and is homogeneously distributed in the mass, does not interfere in principle; it may at least partially react with the oxidic component to form silaones. It has proven convenient to produce the preforms of silicon carbide listed above in the presence of the intercalation compounds of the clay minerals.

In principle, all known amorphous or crystalline carbon species having a primary particle size of more than 99 Ma are suitable as component of the binder offset b) of the composition. % less than 0.001 mm, preferably activated carbon species. With regard to the particle size distribution of this component, there are otherwise no restrictions. Preferably activated carbons resp. Carbon blacks with a specific surface area greater than 500 mVg can be used. In an advantageous embodiment of the invention, the binder offset contains partially or completely instead of the Kchlenstoffpulvors organic compounds, which can be curbonned between 400 ⁰ C and 1100 ° Cn. Solcne species are the per se known thermoplastic polymers and / or copolymers based on PE; PP; PVC; polyvinyl chloride; Polyester or polyamides and / or based on the UF, PF or EP resins (see, inter alia: DE-AS 1,935,277, DE-AS 1,935,500, DE-AS 1,471,364, DE-OS 2,204,749 DE-AS 2,104,657; Dt-OS 3,210,818).

In order to form sialones rich in aluminum oxide and / or to reduce the levels of secondary constituents (for example to Si ₃ N ₄ or Si ₂ ON ₂ ), it is advisable to mix proportions of pyrohydrolysable and / or pyrolyzable aluminum compounds, preferably aluminum salts of the mineral acids. From these be <the heating of the mass displacement at 500 ⁰ C to 900 ° C arises in the mass homogeneously distributed largely X-ray amorphous aluminum oxide. In order to maintain stoichiometric ratios in the formation of the nitride bond is in

- Binder offset a) the ratio of the sum of the originating from the clay minerals and the pyrohydrolysable and / or pyrolysidrbaren aluminum compounds moles Al ₂ O ₃ and SiO ₂ to the moler, introduced and / or formed in situ silicon carbide 0.5 to 2.6 ;

- Binder Offset b) and c) the ratio of the sum of the originating from the clay minerals and the pyrohydrolysable and / or pyrolyzable aluminum compounds moles Al ₂ O ₃ and SiO ₂ to the moles and / or carbon formed below 1000 ⁰ C with 0.4 to 1.5 to comply.

The refractory material in the mass offset is selected from the group of sintered and / or preferably molten refractory oxides, preferably BeO, MgO, CaO, SrO, BaO, Al ₂ O ₃ , ZrO], HfOz, spinels, especially MgAl ₂ O ₄ . and / or the silicates, preferably zirconium silicate (ZrSiO ₄ ) or the sphene, for example CaSnSiOs, and / or the refractory carbides, preferably SiC, and / or the mullite melt and fired fire clay. The refractory material should have a grain size of more than 99 mass% from 0.1 mm to 10 mm, preferably from 0.25 to 2.5 mm. Within these limits there are no restrictions regarding the particle size distribution. To improve the wetting behavior of the refractory material relative to the binder offset, the grain can be cleaned and / or rendered hydrophobic in a manner known per se. The coarse grain generally acts as a porosifying agent during firing. The preparation of the mass can be done in any way. The addition of excipients has proven to be favorable, * for example, temporary binders and / or temporary porosity. Preferably, the binder offset or the mass of a mechanical stress is subjected, optionally after addition of suitable) dispersants. From the mass Fotmkörper are now produced by means of pressing or pouring.

The nitridation is carried out according to the invention in flowing, virtually oxygen-free nitrogen or nitrogen-containing gases at normal or elevated pressure at 1100 C to about 1500 ⁰ C. During nitridation, the bond forms from sialons and other crystalline nitride phases. Glass occurs, if at all, only in low Antoilen. The predominantly crystalline bond is firmly connected to the refractory material. This close contact will

- By a sufficient wetting of the refractory material grain by the binder offset in the phase of mass preparation and shaping and

- by the participation of refractory grains in the chemical reaction during nitride formation

generated. The chemical reaction which mediates the adhesion of the nitride bond to the refractory material leads to a transition layer in which new crystalline phases can also be formed; if necessary, the transition layer is glassy. The surprising occurrence of sialons in the nitride ceramic bond in substantial proportions when using the binder offset a) is compared to the teaching of DE-AS 1,571,354 by

The uniform distribution of the silicon carbide and / or in particular its preform in the matrix of intercalation compounds of the clay minerals with microscopic and / or preferably colloidal region and

- The intimate contact of the solids occurring as a reaction partner of the binder offset due to better mutual wetting with simultaneous secured contact with nitrogen

to explain.

Porous refractory bodies made from a refractory grain, siliceous raw material and carbon based mass, optionally formed in situ, have a nitride bond with, if any, less than 40 mass percent sialons and often substantial levels of silicon carbide. The reason for this is probably in the known problem of carbothermic nitridation of clay minerals. However, if the ceramic compositions according to the invention are processed into porous refractory products with the binder offsets b) or c), the bond generally contains more than 50% by mass of sialones or other silicon-metal oxynitrides. Their surprising appearance is through

The uniform distribution of the carbon or its preform in a matrix of intercalation compounds of the clay minerals in the microscopic and / or preferably colloideal B (

- The intimate contact of the solids occurring as a reaction partner of the mass and in particular the binder offset due to better mutual wetting with simultaneous secured contact with nitrogen

to explain. Generally speaking, the prior art means that the composition according to the invention and preferably the binder offsets a) to c) according to the invention preform the formation of said nitride bond.

embodiments

Notes: The outlined in the following examples, reaction processes represent conscious simplifications Thus, the DMSO-intercalation of kaolinite is shown in dehydrated form as Al ₂ O ₃ · 2SiO _2, the mixture of their AlCl 3 6H ₂ O as Al2O3 · SiO _2.. The sialons appear as daltonide compounds.

Raw materials: kaolin of the chemical composition (in% by mass): SiO ₂ = 52.6; Al ₂ O ₃ = 34; Fe ₂ O ₃ + TiO; = 0.6 with the mineral constituents (in% by mass): kaolinite = 86; Quartz = 14.

1st example:

The invention is based on a mass offset of 85Με .-% Edelko EK25 and 15Ma .-% of a binder offset from Einlagerungsverbindungen a Zwoischichttonminarales (DMSO-kaolinite) with Siliziumcarbidpulver a grain size greater than 99 Ma .-% less than 0.001 mm closer.

In the nitridation dos mass displacement arise from the binder offset, as shown in (1) and (2), directly sialones, preferably x-sialon.

Al ₂ O ₃ .2SiO ₂ + 2SiC + 2N ₂ -> SiAIO ₂ N + Si ₃ AIO ₃ N ₃ + 2CO (1)

Al ₂ O ₃ · SiO ₂ + SiC + N ₂ -> 2SiAIO ₂ N (2) They can react with further silicon carbide to form β'-sialones (3) and (4).

2SiAIO ₂ N + 2SiC + 2N ₂ - ^ Si ₄ Al ₂ O ₂ N ₆ + 2CO '(3)

Si ₃ AIO ₃ N ₃ + 2SiC + 2N ₂ - »Si ₅ AION ₇ + 2CO (4)

As can be seen from (1) to (4), in these examples, the ratio of the sum of the moles of the oxides Al ₂ U ₃ and SiO ₂ to moles of SiC is preferably 0.6 to 1.5. An excess of silicon carbide, for example, on the surface of coarse grain size of SiC, or Reaktior.emperaturen above about 1500 ° C lead to (5) from the ß'-sialones easily to the nitrides.

Si ₄ Al ₂ O ₂ N ₆ + 2SiC + 2N ₂ -> 2Si ₃ N ₄ + 2AIN + 2CO (5)

The sequence of reactions in the formation of the nitride bond outlined in the examples proceeds stepwise. In the first stage x- and o-sialon are formed, in a second step these then ß'-sialon and finally from it 3. the nitrides Si ₃ N ₄ and AIN. It is generally to be expected that the Reaktionsschi itte run side by side, so that usually creates a bond with several crystalline phases.

2.Example:

The invention will be further illustrated by a mass offset of 85Ma .-% Edelkorund EK25 and 15Ma .-% of a binder offset of DMSO-kaolinite with X-ray amorphous carbon powder of a specific surface area of 870m ² / g.

In the nitridation of the mass offset in the temperature range from 1100 ° C to about 1500 ° C arise from the binder displacement immediately sialones, preferably x-sialon (6) to (8).

Al ₂ O ₃ .2SiO ₂ + 3C + N ₂ -> 2SiAIO ₂ N + 3CO (6)

5 (Al ₂ O ₃ .2SiO ₂ ) + 21C + 7N ₂ - * 2Si ₃ AlO ₃ N ₃ + 2Si ₂ Al ₄ O ₄ N ₄ + 21CO (7)

18 (Al ₂ O ₃ .SiO ₂ ) + 52C -i- 14N ₂ -> 52CO + 12SiAIO ₂ N + 5 (SiL ₂ Al ₄₈ O ₄₈ N ₃₂ ) (8)

The dominant at low reaction temperatures x-sialon and the O-sialon can react with additional carbon to ß'-sialon (9) and (10).

3SiAIO ₃ N + 3C + N ₂ -> Si ₃ Al ₃ O ₃ N ₆ + 3CO _ (9)

3Si ₃ AIO ₃ N ₃ + 6C + 4N ₂ -> 2 (Si4.5AI, ₅ O, .sNe.s) + 6CO (10)

As is apparent from Examples (6) to (10), the ratio of the sum of the moles of Al ₂ O ₃ and SiO ₂ to moles of carbon is preferably 0.6 to 1.0. An excess of carbon and / or reaction temperatures above about 145O ⁰ C lead after (11) au 3 the ß'-sialon easily to the) nitrides. The formed silicon nitride can be further reacted to silicon carbide (12).

Si ₃ Al ₃ O ₃ N ₅ + 3C + N ₂ -> Si ₃ N ₄ + 3AIN + 3CO - (11)

Si ₃ N ₄ + 3C -> 3SiC + 2N ₂ (12)

The sequence of reactions in the formation of the nitride bond outlined in the examples is carried out stepwise. In the first stage, ν is formed in preference to x-sialon. O-sialon and ß'-sialon may already occur. In a second step, further β'-sialon then forms from the x- and O-sialon, and finally, the nitrides Si ₃ N ₄ and AIN. It is generally assumed that the reaction steps take place side by side, so that normally a bond with several crystalline constituents is formed.

3rd example:

The invention is now based on a mass offset of 85% by mass of noble corundum EK25 and 15% by mass of a binder / replacement of DMSO-kaolinite with a semicrystalline homopolymer of acrylonitride (d - 5.3 A strong, d = 4.65 A weak). be explained in more detail.

In the nitridation of the mass offset in the temperature range from 110O ⁰ C to about 1400 ⁰ C arise from the binder, similarly as shown in (6) to (8), directly sialones, preferably x-Sialcri. That at low

Reaction temperatures dominant x-sialon and the O-sialon can react with additional carbon to ß'-sialon. It can be seen that the ratio of the sum of the moles AI ₂ O ₃ and SiO ₂ to moles below 1000 ⁰ C formed from PAN

Carbon is preferably 0.5 to 1.0. Also in this example, nitridation is stepwise (see Example 2). j

The quartz content of the mass offsets, originating from the siliceous raw material kaolin, generally yields j in the nitration

Silicon nitride and / or silicon oxynitride. Both components can contribute to the formation of Sielon (13) and (14). !

Si ₃ N ₄ + Al ₂ O ₃ .2SiO ₂ -> 3Si ₂ ON ₂ + 2SiAIO ₂ N (13)!

Si ₂ ON ₂ + AI ₂ O ₃ -> 2SiAIO ₂ N (14) \

In the examples, the refractory grain was considered an inert material. This is because of the formation of the contact zone

Grain / binding not entirely justified. As a rule, it may be assumed that sales of refractory

Compared to those in the binding are low. Melt grits or coarse grain prove to be particularly

"Inert." J

Literature:

1 white, Α .; Thielepape, W. and Orth, H .: Proceedings International Clay Conference 1, (1966), p.277ff .;

2 Grimm, R.E. and Güven, N .: Bentonites. Geology, Mineralogy, Properties and Uses.

Amsterdam and others: Elsevier 1978 ^!

Claims (13)

Porous refractory product with nitride ceramic bond on the basis of the refractory materials, characterized in that it consists of a ceramic mass, the 50 to 95 wt .-% refractory material with a grain size to more than 99 wt .-% refractory material with a Grain size to more than 99% by mass of 0.1 mm to 10 mm, preferably of 0.25 mm to 2.5 mm, and 5 to 50 wt .-% binder, wherein the binder has the following composition: a) 50 to 80% by mass of one or more of the intercalation compounds of the bilayer and / or or three-layer clay minerals, this number being calculated as the sum of aluminum oxides and silicon oxides of the clay minerals, which can be produced from the siliceous raw materials kaolin and / or clay, wherein the degree of incorporation need not be 100%, 20 to 50% by mass of a silicon carbide powder having a particle size of more than 99% by mass smaller than 0.005 mm, preferably smaller than 0.001 mm, and / or the corresponding amount of one or more of the silicon carbide deformations, and additionally 0 to 50% by mass, calculated as Al ₂ O ₃ , pyrohydrolysable and / or pyrolyzable aluminum compounds, preferably aluminum salts of mineral acids, with the proviso that the ratio of the sum of the moles of aluminum oxide and silica to the moles of silicon carbide derived from the clay minerals of the siliceous raw material and the pyrohydrolysable and / or pyrolyzable aluminum compounds is 0.5 to 2.6, preferably 0.6 to 1.6, or b) 75 to 90% by mass of one or more of the intercalation compounds of the bilayer and / or or three-layer clay minerals, this number being calculated as the sum of aluminum oxides and silicon oxides of the clay minerals, a siliceous raw material whose storage level need not be 100%, 10 to 25% by weight of amorphous and / or crystalline cohesive material having a primary particle size of more than 99% by mass smaller than 0.001 mm, which can be generated partially or completely in situ, and additionally - 0 to 50Ma .-% as AI _? O ₃ calculated, pyrohydrolysable and / or pyrolyzable aluminum compounds, preferably aluminum salts of mineral acids, with the proviso that the ratio of the sum of the moles of alumina and silica derived from the clay minerals of the siliceous raw material and the pyrohydrolysable and / or pyrolyzable aluminum compounds to the moles of predetermined and / or in situ formed carbon is from 0.4 to 1.5, preferably 0 , 5 to 1.0, or c) - 75 to 95 Ma .-%, the two-layer and / or three-layer clay minerals contained silicatic raw material, this number being calculated as the sum of aluminum oxides and silicon oxides of the clay minerals, or preferably one or more of the incorporation compounds of the clay minerals with inorganic or organic compounds which largely volatilize below 500 ⁰ C or decompose virtually residue-free, or a mixture of clay minerals and intercalation compounds of clay minerals, 5 to 25% by mass of carbon, generated in situ by pyrolysis of an acrylonitrile-based homo- and / or copolymer with more than 85% of acrylonitrile radicals in the chain below 1000 ° C., and additionally 0 to 50% by mass, calculated as Al ₂ O ₃ , pyrohydrolysable and / or pyrolyzable aluminum compounds, preferably aluminum salts of mineral acids, with the proviso that the ratio of the sum of the clay minerals and the pyrolyzable and / or pyrolyzable aluminum compounds moles of alumina and silica to the moles of carbon formed from the polymeric component is from 0.4 to 1.5, preferably from 0.5 to 1, 0, is made by thermal nitridation. 2. Refractory product according to item 1, characterized in that the content of Al ₂ O ₃ calculated aluminum compounds in the binder offset in the range of 0.1 to 49 wt .-%, preferably 10 to 40Ma .-%, particularly preferably 20 to 30Ma .-%. 3. Refractory product according to item 1 or 2, characterized in that the content of the Siliziumiurncarbidpulvers in the binder offset in the range of 20 to 40 wt .-%, preferably 20 to 30 wt .-% is. 4. Refractory product according to item 1 or 2, characterized in that the content of the amorphous and / or crystalline carbon in the binder offset in the range of 10 to 20Ma .-%, preferably 10 to 15Ma .-% is. 5. Refractory product according to item 1 or 2, characterized in that the content of carbon dioxide from the polymeric acrylonitrile in the binder offset in the range of 10 to 20Ma .-%, in particular 10 to 15Ma .-%. 6. Refractory product according to one of the items 1 to 5, characterized in that the content of the Einlagerungsverbindungsn the clay minerals in the binder calculated as AI ₂ C ₃ and SiO ₂ in the binder a) 55 to 75 Ma .-%, preferably 60 to 75 Ma.- %, in the binder b) 75 to 90% by mass, preferably 80 to 90% by mass and in the binder c) 75 to 90 Ma. %, Preferably 80 to 90% by mass. 7. Refractory product according to any one of items 1 to 6, characterized in that the refractory material is selected from a group consisting of BeO, MgO, CaO, SrO, BaO, Al ₂ O ₃ , ZrO ₂ HfO ₂ , spinels, preferably MgAl ₂ O ₄ , ZrSiO ₄ , Sphene, in particular CaSnSiO ₅ , fired fire clay and / or SiC belong or a mixture of these substances. 8. Refractory product according to any one of items 1 to 7, characterized in that the refractory material is a fused grain, for example, continue Mullichelt. 9. Refractory product according to one of the items 1 to 8, characterized in that the siliceous raw material is a natural or processed clay or kaolin or a mixture of these with the mineral composition (in Ma. ~%) storable clay minerals greater than 70 Quartz smaller than 25 other ingredients less than 5 and the chemical contents (in% by mass) Glass network converter not larger than 6, and a particle size of more than 99% by mass is less than 0.002 mm. 10. Refractory product according to any one of the items 1 a, 2,3,6 to 9, characterized in that the preform of the silicon carbide is an organic silicon compound, the pyrolysis between 500 ⁰ C and 1100 ⁰ C to finely divided amorphous and / or crystalline Silicon carbide leads, for example, the known polysilanes, polycarbosilanes and / or silazanes. Refractory product according to any one of items 11-2.5 to 9, characterized in that the carbon dioxide source used is the thermoplastic polymers and / or copolymers based on polyethylene, polypropylene, polyesters, polyamides, polyvinyl chloride, polyvinylene dichloride and / or of the base the urea or phenol-formaldehyde or epoxy resins are used. 12. Refractory product according to item 11, characterized in that the carbon results from an in situ carbonization at 400 ° C to 1100 ⁰ C. 13. Refractory product according to any one of items 1 to 12, characterized in that the refractory material is present as a core material and is surrounded by the nitrided binder. 14. Refractory product according to item 13, characterized in that the core material is silicon carbide, ceramic bonded silicon carbide, silicon carbide heating rods or carbon.