JPH0699182B2 - Carbon-containing refractory - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon-containing refractory having high strength properties in a wide temperature range of 200 to 1000 ° C. and having excellent thermal shock resistance and hot abrasion resistance.

[0002]

2. Description of the Related Art Refractory compositions containing carbonaceous substances such as graphite have other properties such as high thermal conductivity of carbon, resistance to wet metal and slag, and prevention of excessive sintering of refractory materials. In the coexistence with the refractory aggregate of No. 1, it is widely used as a refractory for metallurgy, such as a refractory for pig making and a refractory for steel making, complementing the advantages of the refractory aggregate. In recent years, due to severer operating conditions such as strong agitation operation, the demand for hot wear resistance, high strength, and improvement of thermal shock resistance of carbon-containing refractories has become stronger and stronger. Is desired.

Natural carbonaceous graphite is generally used as a carbon source for carbon-containing refractories.
Since it does not melt up to, it is difficult to expect an improvement in strength due to the sintering of scaly graphite particles or the sintering of scaly graphite particles and other aggregate particles. Therefore, the quality of carbon bond formation derived from the binder is an important factor that determines the strength of the carbon-containing refractory.

Conventionally, carbon-containing refractory binders have been
Combined use with a liquid phenolic resin or powdered resin having a carbonization yield of 40% or more, a tar-compatible resin and a carbonization yield of 50 to 6
Pitch binders having a softening point of 80 to 90 ° C. at 0% are used, but none are satisfactory.

[0005]

The strength of carbon-containing refractories using phenol resin as a binder is 200 to
The resin strength is high up to 300 ° C due to the development of the resin strength.
It becomes about ¼ of the strength at 200 ° C. between 00 and 1000 ° C. Further, at 1000 ° C. or higher, the strength is gradually increased due to the graphitization of carbon derived from the resin, but the degree is small. Moreover, the carbon structure derived from the resin exhibits a glassy structure, and is lower in thermal shock resistance, oxidation resistance and thermal conductivity than graphite. Intermediate temperature range (400-1000 ℃)
The decrease in strength and the glassy carbon bond structure promote the weakening (loosening) of the carbon-containing refractory structure used under repeated heating conditions, and promote the oxidation damage of graphite and the wear damage of hot metal and molten steel.

[0006] A tar-compatible resin is used to improve the drawbacks of the phenolic resin binder, but it strongly retains the properties of the resin and has a small strength improving effect in the intermediate temperature range.

Further, since the conventional pitch binder has a large amount of volatile components, it expands in the heat treatment process at 200 to 500 ° C., so that it is difficult to obtain a dense brick structure.

Therefore, an object of the present invention is to provide a carbon-containing refractory material which can maintain high strength in a wide temperature range and a method for producing the same.

[0009]

That is, the present invention is 50 to 97% by weight of a mixture of one or more of refractory oxides, nitrides, borides and carbides, 3 to 50% by weight of carbon raw material,
And a bulk mesophase having optical anisotropy 60
% Of the mesophase pitch powder having a carbonization yield of 70% or more is added and blended, and if necessary, a thermosetting resin such as phenol resin is added to the carbon-containing refractory. Pertain.

Such a carbon-containing refractory can be produced by the following method: 50 to 97% by weight of a mixture of one or more of refractory oxides, nitrides, borides and carbides and 3 to 3 carbon raw materials.
85% to 99.5% by weight of refractory aggregate composed of 50% by weight,
0.5 to 15% by weight of mesophase pitch powder having a carbonization yield of 70% or more containing 60% or more of bulk mesophase having optical anisotropy is kneaded at room temperature, molded, and dried,
Further bake appropriately;

A refractory aggregate 85-99. Consisting of 50-97% by weight of a mixture of one or more refractory oxides, nitrides, borides and carbides and 3-50% by weight of a carbon raw material.
5% by weight and 0.5 to 15% by weight of mesophase pitch powder having a carbonization yield of 70% or more containing 60% or more of bulk mesophase having optical anisotropy are kneaded in a temperature range in which the mesophase pitch powder is softened. , Mold and fire appropriately;

Refractory aggregates 85-99. Consisting of 50-97% by weight of a mixture of one or more refractory oxides, nitrides, borides and carbides and 3-50% by weight of carbon raw materials.
5% by weight and 0.5 to 15% by weight of mesophase pitch powder containing 60% or more of bulk mesophase having optical anisotropy and having a carbonization yield of 70% or more were kneaded at room temperature, and then the pitch powder was prepared. 1-30% by weight of melted dissolved oil is externally added, kneaded, molded, and further heat-treated or baked;

A refractory aggregate 85-99. Consisting of 50-97% by weight of a mixture of one or more refractory oxides, nitrides, borides and carbides and 3-50% by weight of a carbon raw material.
5% by weight and 0.5 to 15% by weight of mesophase pitch powder containing 60% or more of bulk mesophase having optical anisotropy and having a carbonization yield of 70% or more were kneaded and molded at room temperature to obtain The molded body is air-oxidized in a temperature range of 200 to 300 ° C. to polymerize the mesophase pitch, and then heat-treated or baked.

A refractory aggregate 85-99. Consisting of 50-97% by weight of a mixture of one or more refractory oxides, nitrides, borides and carbides and 3-50% by weight of a carbon raw material.
0.5% to 10% by weight of mesophase pitch powder containing 5% by weight and 60% or more of bulk mesophase having optical anisotropy and a carbonization yield of 70% or more, and 5% by weight of thermosetting resin such as phenol resin The following are kneaded at room temperature, molded, dried, and heat-treated at a temperature in the range of 100 to 300 ° C.

[0015]

The mesophase pitch powder used in the present invention has an extremely high carbonization yield without raising the softening point too much, and has a good fluidity at 200 to 300 ° C. Disperse evenly. Moreover, since the carbonization yield is high and the amount of volatile gas is small, the formed carbon bond is dense and has almost no bubbles,
It can form a very strong brick tissue.

Further, this carbon bond increases in strength with heating, and in the conventional resin bond, the strength is significantly decreased.
High strength can be achieved even at a temperature of 00 to 1000 ° C. The carbon derived from the resin binder generally has a low graphitization degree and has a drawback of being easily oxidatively worn, but the bond derived from the mesophase pitch powder exhibits an optically anisotropic structure and has a high density. Also, since it is of high purity, it is strong against oxidative wear. On the other hand, since it does not undergo the heat treatment required for graphitization,
Although it is in the state of calcined carbon, since it is an extremely high graphitizable substance, it has a thermal conductivity and a thermal expansion coefficient similar to that of graphite.

In order to make these characteristics more effective, it is preferable that the mesophase pitch has a bulk shape. Conventionally, the mesophase in the bulk state is formed by coalescing mesophase spherulites, and it usually requires a temperature around 400 ° C. or higher at which mesophase spherules can be formed. Since the mesophase has a high viscosity, when it is used as a binder, the spreadability of the refractory aggregate between particles becomes poor. The softening point of mesophase pitch used in the present invention is 1
80-400 degreeC is preferable.

The mesophase pitch is bulky and spreads between the refractory aggregate particles to form a strong connective structure. The method for producing the bulk mesophase pitch is not limited, but a bulk mesophase pitch having an extremely low softening point can be easily prepared by a non-dehydration condensation reaction of naphthalene or anthracene with HF / BF ₃ under pressure. Obtained (Susumu Mochida et al .: The 15th Annual Meeting of the Carbon Society of Japan)
(1988) pp. 32-33).

The carbonization yield of the mesophase pitch powder is preferably one having a carbonization yield of 70% or more in view of the orientation, compactness and purity of the formed bond. The higher the carbonization yield, the better, but it is also necessary to obtain proper fluidity at 200 to 300 ° C.

Further, according to the method of the present invention, the refractory aggregate and the mesophase pitch powder can be mixed and molded at room temperature, and then fired to obtain a better refractory material. Since the mesophase pitch powder maintains the shape of the formed body, it is thinly and uniformly distributed in the formed structure due to the fluidity at 200 to 400 ° C., so that the subsequent carbonization forms a uniform carbon bond between the aggregates. Upon carbonization, the mesophase pitch shows a high yield, and since the carbon produced is a graphitizable compound having a fine mosaic composition and is dense, the carbon bond between the aggregates is extremely strong.

The carbon bond has a higher degree of graphitization by firing at a high temperature and becomes finer due to shrinkage, so that the carbon bond is further strengthened. This firing is performed in a reducing atmosphere at 500
It is preferably carried out at a temperature of ˜1500 ° C. The mesophase pitch begins to carbonize and solidify at 400 to 550 ° C, and its strength improves as it is subjected to high temperature treatment. Therefore, the higher the calcination temperature is, the better it is. However, when the calcination temperature is higher, the oxidation-reduction reaction with the oxide occurs. Therefore, it is necessary to select a temperature suitable for the refractory aggregate.

Further, as a method for maximizing the characteristics of the mesophase pitch powder, according to the second method of the present invention, the mesophase pitch powder can be kneaded in a temperature range where it softens and molded in a heated state. In this method, there is almost no volatile component and the mesophase pitch powder is uniformly dispersed on the surface of the refractory aggregate, so that a dense and high-strength brick structure can be obtained.

Further, according to the third method of the present invention, in order to uniformly disperse the mesophase pitch powder by kneading at room temperature or a temperature of 100 ° C. or less, a dissolved oil capable of dissolving the mesophase pitch powder is used as a refractory bone. The material is added to a mixture of pitch powder utilizing the high solubility of the mesophase pitch and the mixture is kneaded and then molded. The mesophase pitch is melted and uniformly dispersed on the surface of the refractory aggregate. As the dissolved oil, xylene, toluene, methylnaphthalene, tetrahydrofuran (THF) or the like can be used. When quinoline is used as the solvent, the solubility of mesophase pitch in the solvent is 20
-80% is preferable. The added amount of the dissolved oil is in the range of 1 to 30% by weight on the outside. Further, after kneading, the dissolved oil may be partially or wholly removed and molded.

When the carbon-containing refractory material of the present invention is obtained as an unfired brick, strength at room temperature is required. As a method of imparting this room temperature strength, according to the fourth method of the present invention, the mesophase pitch is polymerized by infusibilizing treatment of air oxidation in the temperature range of 200 to 300 ° C. after molding, and the strength at 300 ° C. or lower Can be expressed.

Further, according to the fifth method of the present invention, a thermosetting resin such as a phenol resin and a mesophase pitch powder are used together as a binder, kneaded, and molded 100 to 3 after molding.
A heat treatment at 00 ° C. is performed. In this method, mesophase pitch powder is added in order to complement the drawbacks of phenolic resin, and it is possible to improve the strength at 400 to 1000 ° C. in which the strength is lowered due to the decomposition of phenolic resin. Further, since the phenol resin is used, the conventional room temperature kneading can be performed.

It is necessary to consider the particle size and dispersion of the mesophase pitch used in the present invention, and the particle size of the mesophase pitch powder is preferably adjusted to 0.149 mm or less.

From the viewpoint of corrosion resistance, it is not desirable that the amount of the mesophase pitch powder added exceeds 15% by weight. On the other hand, if it is less than 0.5% by weight, the effect of strength development becomes small. When the mesophase pitch powder and the thermosetting resin are used in combination, the addition amount of the mesophase pitch powder is about 0.5 to 10% by weight, and the addition amount of the thermosetting resin is 5% by weight or less. preferable.

As the refractory material usable in the present invention, oxides such as magnesia, spinel, calcia, dolomite, alumina, silica, zirconia and zircon, and silicon carbide, silicon nitride, boron nitride, boron carbide and zirconium boride ( Non-oxides such as ZrB ₂ ) can be mentioned.

The above mesophase pitch is easy to graphitize, and when the boron compound is used in combination with the refractory aggregate, it is 1000 to 1
From the relatively low temperature range of 500 ° C., the substitutional solid solution of boron strengthens the carbon skeleton and provides high strength. Also, the oxidation resistance is improved.

Further, by adding a small amount of a metal such as Mo, Cr, Ti or Mn, the degree of graphitization can be improved at low temperature treatment temperature, and the same effect as high temperature treatment can be obtained. Strength is obtained.

Further, as the carbonaceous material usable in the present invention, natural graphite such as earth-like graphite and scaly graphite or artificial graphite,
Examples include electrode scrap, carbon fiber, and pyrolytic graphite.

The above-mentioned refractory material and carbonaceous material are not particularly limited, and it is preferable to use natural graphite mainly containing magnesia, calcia, dolomite, spinel and alumina, although it depends on the purpose of use.

[0033]

EXAMPLES The carbon-containing refractory material of the present invention will be further described with reference to the following examples. Example 1 A mixture having a blending ratio shown in Table 2 below was heated and kneaded at room temperature or 200 ° C., and the obtained dough was 1500 kgf.
It was pressure molded into a size of 230 mm × 114 mm × 65 mm with a pressure of / cm ² . The molded articles thus obtained were treated by the treatment methods shown in Table 2 to obtain carbon-containing refractories.

The characteristics of the mesophase pitch powder used in the examples and comparative examples and the comparative pitch are shown in Table 1 below.

[0035]

[Table 1] Softening point Anisotropy content Yield Note (℃) (%) (%) Mesophase pitch 1 218 100 85.5 Synthetic pitch Mesophase pitch 2 252 90 91.7 Coal pitch Mesophase pitch 3 258 100 92.0 Petroleum pitch Comparative pitch 1 215 0 60 Comparative pitch 2> 400 60 85 ~ 90

[0036]

[Table 2]

In Table 2, xylene was used as the dissolved oil. The phenol resin used was a resole type liquid resin residual carbon rate of 40%.

Manufacturing conditions of sample Molding: hydraulic press 1.5 ton / cm ² shape: 230 × 114 × 65 mm reduction firing: firing in a breeze-filled sheath 200-300 heating: air oxidizing atmosphere for 12 hours

Example 2 As a gas injection nozzle for a molten metal container, 3% by weight of synthetic pitch type mesophase pitch and 3% by weight of phenolic resin were added to the compound containing magnesia of A in Table 2 above and graphite as an aggregate.
A non-fired gas injection nozzle was manufactured by loading a stainless steel tube having an inner diameter of 1.5 mm and an outer diameter of 3.5 mm in a refractory to which was added.

180 ton converter placed at the bottom of the converter, 7 kgf / cm ²
Argon gas was blown at a rate of 8 Nm ³ / min for refining. Phenolic resin 3.0% by weight, comparative pitch 3.
The wear rate is about 20% compared to the comparative product H added with 0% by weight.
Also, no abnormal damage such as peeling due to heat spalling and gas leakage was observed.

Example 3 As a plate brick for a sliding nozzle, F of Table 2 was used.
After adding 3.0% by weight of synthetic mesophase pitch and 2.0% by weight of petroleum-based mesophase pitch to the mixture of alumina, mullite, and graphite as aggregate, after adding 3.0% by weight of toluene as a dissolved oil to the outside, Oxidation infusibilizing treatment was carried out at 200 to 300 ° C. to produce a non-fired plate.

A two-strand 60 ton tundish was compared to a non-fired plate with 4.0% by weight phenolic resin. Both of them completed 6-charge continuous casting, but the product of the present invention to which mesophase pitch was added had a slight decarburization around the nozzle hole as compared with the product to which the phenol resin was added, and the corner defect of the nozzle hole and the sliding surface The roughness was small and the effect was confirmed.

[0043]

INDUSTRIAL APPLICABILITY The carbon-containing refractory material of the present invention has a high carbonization yield without significantly increasing the softening point.
Since mesophase pitch powder with good fluidity at 300 ° C is used, it is quickly and uniformly dispersed around the refractory aggregate, and the mesophase pitch powder has a high carbonization yield and a small amount of volatile gas. Since the carbon bond to be formed is dense and has almost no bubbles, a very strong brick structure can be formed.

Further, the carbon bond made of the mesophase pitch powder increases in strength with heating, and the conventional resin bond alone can enhance the strength of the carbon-containing refractory even at a temperature of 500 to 1000 ° C. at which the strength is remarkably lowered.

Claims (7)

[Claims] 1. A refractory aggregate 85-99 comprising 50-97% by weight of a mixture of one or more refractory oxides, nitrides, borides and carbides and 3-50% by weight of a carbon raw material.
5% by weight and 0.5-15% by weight of mesophase pitch powder containing 60% or more of bulk mesophase having optical anisotropy and having a carbonization yield of 70% or more Containing refractories. 2. A refractory aggregate 85-99 comprising 50 to 97% by weight of a mixture of one or more of refractory oxides, nitrides, borides and carbides and 3 to 50% by weight of a carbon raw material.
5% by weight and 0.5 to 15% by weight of mesophase pitch powder having a carbonization yield of 70% or more containing 60% or more of bulk mesophase having optical anisotropy are kneaded at room temperature, molded, dried, and further A method for producing a carbon-containing refractory material, which comprises firing appropriately. 3. A refractory aggregate 85-99 comprising 50-97% by weight of a mixture of one or more refractory oxides, nitrides, borides and carbides and 3-50% by weight of a carbon raw material.
After kneading 5% by weight and 0.5 to 15% by weight of mesophase pitch powder having a carbonization yield of 70% or more containing 60% or more of bulk mesophase having optical anisotropy in a temperature range where the mesophase pitch powder is softened. A method for producing a carbon-containing refractory material, which comprises molding, and appropriately firing. 4. A refractory aggregate 85-99 comprising 50 to 97% by weight of a mixture of one or more of refractory oxides, nitrides, borides and carbides and 3 to 50% by weight of a carbon raw material.
5% by weight and 0.5 to 15% by weight of mesophase pitch powder containing 60% or more of bulk mesophase having optical anisotropy and having a carbonization yield of 70% or more were kneaded at room temperature, and then the pitch powder was prepared. A method for producing a carbon-containing refractory material, which comprises adding 1 to 30% by weight of dissolved oil to the outside, kneading, molding, and heat-treating or firing. 5. A refractory aggregate 85 to 99 comprising 50 to 97% by weight of a mixture of one or more of refractory oxides, nitrides, borides and carbides and 3 to 50% by weight of a carbon raw material.
5% by weight and 0.5 to 15% by weight of mesophase pitch powder containing 60% or more of bulk mesophase having optical anisotropy and having a carbonization yield of 70% or more were kneaded and molded at room temperature to obtain A method for producing a carbon-containing refractory material, which comprises subjecting a formed body to air oxidation in a temperature range of 200 to 300 ° C. to polymerize the mesophase pitch. 6. A refractory aggregate 85 to 99 comprising 50 to 97% by weight of a mixture of one or more of refractory oxides, nitrides, borides and carbides and 3 to 50% by weight of a carbon raw material.
5% by weight, 0.5-10% by weight of mesophase pitch powder having a carbonization yield of 70% or more containing 60% or more of bulk mesophase having optical anisotropy, and 5% by weight or less of a thermosetting resin were added and blended. A refractory material containing carbon, which is characterized by: 7. A refractory aggregate 85-99 comprising 50-97% by weight of a mixture of one or more refractory oxides, nitrides, borides and carbides and 3-50% by weight of a carbon raw material.
0.5 to 10% by weight of mesophase pitch powder containing 5% by weight and 60% or more of bulk mesophase having optical anisotropy and a carbonization yield of 70% or more, and thermosetting resin 5
100% to 300 ° C by kneading and molding less than wt% at room temperature
A method for producing a carbon-containing refractory material, which comprises performing heat treatment at a temperature within the range.