JP2003040672A - Refractory used for fireproof member for continuous steel casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refractory used for fireproof member for continuous steel casting capable of preventing Al2 O3 oxide perfectly from adhering regardless of cleanness of the molten steel, useful for fireproof material contactable with the molten steel. SOLUTION: The refractory used for fireproof member for continuous steel casting is composed of fire proof member for mainbody and the refractory used for fireproof material contactable with the molten steel of the continuous casting. The refractory contains CaO of 5-40 mass%, SiO2 of 2-30 mass%, ZrO2 of 35-80 mass% and carbon of <5 mass% (including zero).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory for a continuous cast refractory member of steel, and more specifically, a continuous casting nozzle such as a long nozzle, an upper nozzle, a lower nozzle and a dipping nozzle used for continuous casting of steel. As a refractory for the continuous cast refractory member of steel, such as stopper heads and slide plates, which is in contact with molten steel, oxides such as alumina and new metal refractory for continuous cast refractory member that can suppress the adhesion of metal It is about things.

[0002]

2. Description of the Related Art Contact with a molten steel of a continuous casting refractory member such as a long nozzle, an upper nozzle, a lower nozzle, a dipping nozzle or the like for continuous casting of steel, a stopper head, a slide plate, etc. As the refractory for the part, conventionally, alumina-graphite, alumina-silica-
Graphite-containing refractories such as graphite, spinel-graphite and zirconia-graphite are widely used.

When these materials are applied to refractory members for continuous casting such as dipping nozzles, since they contain graphite, they are excellent in spalling resistance, but due to reaction with [Al] in the molten steel, or due to reaction with molten steel. The presence of Al ₂ O ₃ inclusions causes Al ₂ O ₃ based oxide to adhere and deposit on the refractory working surface. If the amount of the Al ₂ O ₃ based oxide attached becomes remarkable,
The nozzle inner tube is clogged to reduce the amount of molten steel passing, which is not preferable in terms of slab quality and stable operation.

In order to suppress the adhesion of this Al ₂ O ₃ -based oxide, in recent years, a non-carbon or carbon-less material having a thickness of several mm has been arranged on the inner tube-side working surface of a refractory such as a dipping nozzle. The method of setting is implemented.

For example, JP-A-3-243258 discloses that an inner surface of one or both of an immersion nozzle for continuously injecting molten steel in a tundish into a mold and an intermediate nozzle connected to the upper portion of the immersion nozzle is (a). ) 5% by weight
Al ₂ O ₃ is 9 without containing SiO ₂ in excess of (mass%).
Carbonless high-alumina refractory of 0% by weight (mass%) or more, (b) Carbonless high magnesia of 90% by weight (mass%) or more without containing SiO ₂ exceeding 5% (mass%). Quality refractory, (c) one or two or more of carbonless high zirconia refractory containing not more than 5% by weight (mass%) of SiO ₂ and 90% by weight (mass%) or more of ZrO _2. Nozzles for continuous casting composed of combined refractory materials are disclosed.

Further, JP-A-5-154628 discloses that an alumina clinker having an alumina content of 99 wt% (mass%) or more as a main component, an alumina content of 70 wt% (mass%) or more, and a carbon content of Has a refractory composition of less than 1 wt% (mass%) and a silica content of less than 1 wt% (mass%), and a particle size of 0.21 mm or less is 20 to 20%.
Nozzle bores for continuous casting are disclosed having a grain size composition which accounts for 70%.

Further, Japanese Patent No. 3114004 discloses that
Calcium zirconate having a carbon content of less than 1 wt% (mass%) and a free silica content of less than 1 wt% (mass%), zirconia containing calcium oxide as a solid solution, zircon refractory, or magnesia- Disclosed is a nozzle characterized in that the wall surface of the inner hole is formed of any material of zircon refractory materials.

[0008]

Non-carbon or carbon-less materials such as alumina, alumina-silica, and spinel do not contain graphite or contain only a small amount of carbon, so that carbon is dissolved or lost in molten steel. It is more effective for adhesion of Al ₂ O ₃ -based oxide than the conventional graphite-containing system due to the characteristics such that unevenness of the operating surface due to scattering can be suppressed and the thermal conductivity is low. However, once the Al ₂ O
_{When the 3-} based oxide starts to adhere to the operating surface, the operating surface becomes uneven, and therefore the adhesion progresses over time, leading to blockage of the inner pipe portion.

In addition to the effect that the non-carbon or carbon-less material of calcia-zirconia type is non-carbon or carbon-less material, the adhered Al ₂ O ₃ -based oxide reacts with calcium in the refractory. Then, by producing a CaO-Al ₂ O ₃ -based low-melting-point substance, it is expected to be cleaned by the molten steel flow. However, also in this case, when the cleanliness of the molten steel is very poor, CaO.6Al ₂ O ₃ having a high melting point is simultaneously produced, and therefore a sufficient adhesion preventing effect cannot be obtained.

Therefore, an object of the present invention is to continuously provide a steel useful as a refractory material at least at a portion in contact with molten steel capable of completely preventing adhesion of Al ₂ O ₃ -based oxide regardless of cleanliness of molten steel. It is to provide a refractory for a cast refractory member.

[0011]

According to the research conducted by the present inventors, a non-carbon or carbon-less material of CaO--SiO ₂ --ZrO ₂ quality is provided in at least a portion of a continuously cast refractory steel member which comes into contact with molten steel. When installed, it reacts with molten steel and inclusions in the steel to produce a highly viscous molten glassy smooth surface,
It has been found that the adhesion of Al ₂ O ₃ based oxide can be prevented.

That is, according to the present invention, a refractory used as a refractory material at least in a portion in contact with molten steel of a continuously cast refractory member made of steel composed of a main body refractory material and a refractory material in a portion in contact with molten steel is CaO: 5. -40 mass%, SiO2: _2-
30% by mass, ZrO ₂ : 35 to 80% by mass, and carbon: less than 5% by mass (including zero).

Further, the refractory for continuous cast refractory steel of the present invention contains 0.1 to 20% by mass of at least one low melting point raw material having a melting point of 1400 ° C. or less. Is characterized by.

Further, the refractory for continuous casting refractory steel of the present invention is characterized in that the refractory member for continuous casting of steel is a long nozzle, an upper nozzle, a lower nozzle, a dipping nozzle, a stopper head or a slide plate. And

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Steel for continuous casting refractory member of the present invention
Is the refractory a refractory that is in contact with the body refractory or molten steel?
Continuous casting refractory member of steel composed of at least molten steel
It is useful as a refractory material in contact with. At least
The continuous casting of the steel of the present invention to the refractory of the member which also contacts the molten steel
Non-carbon by arranging refractory for refractory member
Alternatively, the smoothness and low heat transfer characteristic of carbonless materials
In addition to providing conductivity, in the unlikely event that Al_TwoO_ThreeSystem oxide cast
Even if it adheres once in the beginning, Al_TwoO_ThreeFor reaction with oxides
Immediately CaO-SiO_Two-ZrO_Two-Al_TwoO_Three
The molten glassy smooth surface of the system is formed, and the subsequent Al_TwoO_Three
It has a feature that it is difficult for the system oxide to adhere. Melting moth
Al on smooth lath surface_TwoO_ThreeMechanism that does not adhere to oxides
Although there are some uncertainties regarding the structure, the wettability with molten steel is significantly improved.
It is thought that playing the game plays a major role.
In addition, a molten glassy smooth surface formed by this reaction
ZrO _TwoDue to the presence of high viscosity, molten steel temperature
Even if the temperature is high, it will be washed away by the molten steel flow, and the operating surface will
It is not melted down.

In the refractory for continuous cast refractory steel of the present invention, the CaO component is in the range of 5 to 40 mass%.
If the CaO component is less than 5% by mass, the generation of the molten glassy smooth surface (layer) in the reaction with Al ₂ O ₃ is unstable,
On the other hand, if it exceeds 40% by mass, the viscosity of the smooth surface of the molten glass decreases, and melting may be lost, which is not preferable. From the viewpoint of preventing the Al ₂ O ₃ -based oxide from adhering and preventing melting damage, the CaO component is more preferably 10 to 30 mass%.

In the refractory for continuous casting refractory steel of the present invention, the SiO ₂ component is in the range of 2 to 30 mass%. If the SiO ₂ component is less than 1% by mass, there is no effect of forming a molten glassy smooth surface, and if it exceeds 30% by mass, the reaction with the adhered Al ₂ O ₃ -based oxide becomes excessive, so that the refractory melts. Lose. The SiO ₂ component is more preferably 3 to 20 mass%.

In the refractory for continuous cast refractory steel of the present invention, the ZrO ₂ component is within the range of 35 to 80 mass%. If the content of ZrO ₂ component is less than 35% by mass, the viscosity of the molten glassy smooth surface produced is reduced. On the other hand, if it exceeds 80% by mass, the formation of a molten glassy smooth surface is insufficient, and A
The effect of preventing adhesion of the l ₂ O ₃ -based oxide is small. Zr
The O ₂ component is more preferably 40 to 70 mass%.

In the refractory for a continuous cast refractory member of steel of the present invention, a non-carbon material in which carbon is the only carbon due to residual carbon due to the binder is preferable.
In this case, the carbon content of the residual coal is usually 1% by mass or more. In some cases, it is possible to use a binder that does not substantially generate residual carbon. In this case, carbon is substantially absent. When spall resistance is required depending on continuous casting conditions such as insufficient preheating, carbon-less material containing carbon raw material such as graphite or carbon black in an amount of less than 5% by mass is used. It may be. When carbon is 5% by mass or more, decarburization impairs the smoothness of the operating surface, and sufficient smoothness cannot be secured.

In producing the refractory for continuous cast refractory steel of the present invention, it is possible to use synthetic raw materials synthesized by melting CaO-based raw materials, SiO ₂ -based raw materials and ZrO ₂ -based raw materials. It is also possible to combine two or more kinds of general refractory raw materials containing each component. For example, ZerO ₂ -based raw materials include baddelite, zircon,
Stabilized or partially stabilized zirconia by calcia, etc.,
Sintered or electrofused calcium zirconate or the like can be used. Further, as the CaO-based raw material and / or the SiO ₂ -based raw material, electrofused calcia, calcium carbonate, fluorite,
Wollastonite, calcium silicate, fused quartz, silica flour, silica stone, natural raw materials containing 60% by mass or more of SiO ₂ can be used, and both amorphous and crystalline can be used.

[0021] Incidentally, the CaO-based material, a combination of SiO ₂ based material and the ZrO ₂ raw material, wherein at the respective raw materials may be blended in combination in any manner, inter alia, CaO · SiO _2, etc. calcia - Combination of silica-based material + calcium zirconate, CaO ・ SiO ₂
Such as a combination of calcia-silica-based raw material + stabilized zirconia, a combination of calcium zirconate + silica-based raw material, and a combination of calcia-stabilized or partially-stabilized zirconia + silica-based raw material with thermal expansion behavior and adhered Al _{It is} preferable from the viewpoint of melting behavior during the reaction with the ₂ O ₃ based oxide.

The refractory for continuous cast refractory steel of the present invention is a non-carbon or carbonless material,
Continuous casting of steel The main body of refractory members is a material with a much smaller amount of graphite than the conventional material that constitutes the refractory material, so at least the refractory material in contact with molten steel is used as the refractory material in contact with molten steel. The coefficient of thermal expansion of is likely to be higher than the coefficient of thermal expansion of the material forming the refractory body. Therefore, due to the difference in the coefficient of thermal expansion, peeling of the refractory at least in a portion in contact with the molten steel or cracking of the main body refractory is likely to occur.

In order to prevent this peeling and cracking,
It is effective to add a low-melting-point raw material that melts from a low temperature range of 1400 ° C. or lower to reduce the coefficient of thermal expansion of the refractory at least in the portion in contact with the molten steel. Also, the addition of the low melting point raw material is
There is also an effect of accelerating the formation of a molten glass-like smooth surface by the reaction with the Al ₂ O ₃ -based oxide adhering to the operating surface of the refractory inner tube or the like at least in contact with the molten steel.

The low melting point raw material in the present invention refers to a raw material having a melting point of 1400 ° C. or less as a simple substance, and examples thereof include feldspar, frit, glass powder, and fluorite used for glazes of ceramics. it can. The low melting point raw material may be a natural product or a synthetic product. The addition amount of the low melting point raw material is within the range of 0.1 to 20 mass%. If the addition amount of the low melting point raw material is less than 0.1% by mass, the effect of the addition will not be exhibited, which is not preferable, and if it exceeds 20% by mass, the melting loss resistance is unfavorably reduced. The addition amount of the low melting point raw material is more preferably 10% by mass or less.

When the refractory material of the present invention is used as, for example, the inner tube material of a nozzle, not only the integral molding method with the main body refractory material, but the inner tube material is preliminarily formed into a sleeve shape and inserted into the main body refractory material. A method is also possible. In addition, a considerable effect can be obtained by kneading the refractory material of the present invention together with a binder and applying it to the main body refractory material.

As a prior art having a chemical composition similar to that of the present invention, there is JP-A-9-57406, which erodes refractory materials such as steel species having a high oxygen content and steel species treated with calcium. The purpose of the invention is to improve the corrosion resistance by making the addition of graphite essential and preventing the dissolution of graphite into molten steel in steel types with strong properties.
Therefore, after adding as little graphite as possible,
The purpose and idea are different from those of the present invention in which the adhesion of Al ₂ O ₃ -based oxide is prevented and the cracking due to abnormal expansion is prevented.

Further, in Japanese Patent No. 3114004, calcium zirconate having a carbon content of less than 1% by mass and a free silica content of less than 1% by mass, zirconia containing calcium oxide as a solid solution, and zircon refractory material. , Or a magnesia-zircon refractory, a nozzle characterized in that the inner wall surface is formed of any material, that is, CaO—ZrO ₂ ,
Points to a made of any of the composition of _{ZrO 2 -SiO 2, MgO-ZrO} 2 -SiO 2, Ca of the present invention
It is clearly different from the composition composed of the O—SiO ₂ —ZrO ₂ system.

The refractory for continuous cast refractory member of the present invention is C
a non-carbon or carbon-free material of aO-SiO ₂ -ZrO ₂ compositions, parts once adhered to react with Al ₂ O ₃ based oxide, to produce a molten glass-like smooth surface of a high viscosity, in contact with at least the molten steel By using it as a refractory, it is possible to prevent the Al ₂ O ₃ -based oxide from adhering to the refractory.

Next, an application example of the refractory material for continuous cast refractory steel of the present invention will be described. FIG. 1 is an example in which the refractory material (2) of the present invention is used as an inner tube material of a dipping nozzle.
In the figure, (1) is a refractory body. Here, as the main body refractory (1), a conventional alumina-carbon refractory, zirconia-carbon refractory, or the like can be used. Next, FIG. 2 is an example in which the refractory material (2) of the present invention is used as an inner pipe material of a long nozzle. Here, as the main body refractory (1), a conventional alumina-carbon refractory or the like can be used. Next, FIG. 3 shows an example in which the refractory material (2) of the present invention is used as an inner hole material of a slide plate. Here, as the main body refractory (1), a conventional alumina-carbon refractory or the like can be used. next,
FIG. 4 shows an example in which the refractory material (2) of the present invention is used as the inner tube material of the upper nozzle and the lower nozzle. Here, as the main body refractory (1), a conventional alumina-carbon refractory or the like can be used. Next, FIG. 5 shows an example in which the refractory material (2) of the present invention is used on the surface of the stopper head.
Here, as the main body refractory (1), a conventional alumina-carbon refractory, zirconia-carbon refractory, or the like can be used. 1 to 5 show preferred examples of application of the refractory steel of the present invention to a continuously cast refractory member, and the application of the refractory product of the present invention is not limited to these. I want you to understand.

[0030]

EXAMPLES The fire resistant member for continuous casting of steel according to the present invention will be described below with reference to examples. Examples Using the raw materials shown in Table 1, 5 to 10% by mass of a binder was added to the refractory raw material mixture having the mixing ratios shown in Table 2 by external coating, and the mixture was molded into the shape of a dipping nozzle, then at 10 ° C at 200 ° C.
After being dried for an hour, the product of the present invention and a comparative product were obtained by baking at 1100 ° C. for 3 hours in a reducing atmosphere. In addition,
In Products 15 and 16 of the present invention in Table 2 described later, ligulin sulfonic acid which is a low residual carbon binder was used as a binder, and phenol resin which is a high residual carbon binder was used as the others. Further, the composition values in Table 2 are the values obtained by analyzing the fired product, and because of volatilization and the like, the values are slightly different from the calculated values in terms of formulation.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

In Table 2, the coefficient of thermal expansion is measured by a non-contact type hot linear expansion coefficient measuring device. In addition, the adhesion amount and melting loss are in the molten steel in the high frequency induction furnace (low carbon aluminum killed steel)
It was measured by the immersion test. In addition, the comprehensive evaluation is that all three items of coefficient of thermal expansion, adhesion amount, and melting loss sufficiently satisfy the practical level. ◎ Any of the three items do not satisfy the practical level, and therefore cannot be applied to the actual machine. It is evaluated as x, and when either the amount of adhesion or the melting loss is slightly recognized, but the effect is considerably recognized as compared with the conventional product, it is evaluated as ◯.

In the example containing 2 mass% or more of the SiO ₂ component and adding the low-melting-point raw material, the thermal expansion was minimal, and the adhesion of Al ₂ O ₃ -based oxide and the melting loss of the refractory were not recognized. , Very good results were obtained.

[0036]

The refractory for continuous cast refractory steel of the present invention is disposed on at least a member of the continuous cast refractory cast steel which is in contact with molten steel, for example, an inner pipe of a dipping nozzle, so that Al on the working surface _{It is possible} to prevent clogging due to adhesion and deposition of ₂ O ₃ based oxide. Further, by adding a low-melting point raw material having a melting point of 1400 ° C. or less as a simple substance, thermal expansion is reduced. For example, when the raw material is arranged in the inner tube of the immersion nozzle, etc., the main material is pushed and split by the expansion of the inner tube. Can be prevented.

[Brief description of drawings]

FIG. 1 is an example in which the refractory material of the present invention is used as an inner tube material of a dipping nozzle.

FIG. 2 is an example in which the refractory material of the present invention is used as an inner pipe material of a long nozzle.

FIG. 3 is an example of using the refractory material of the present invention as an inner hole material of a slide plate.

FIG. 4 shows the case where the refractory material of the present invention is used as the inner pipe material of the upper nozzle and the lower nozzle.

FIG. 5 is an example of using the refractory material of the present invention on the surface of a stopper head.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B22D 41/32 B22D 41/32 41/54 41/54 (72) Inventor Shinsuke Inoue Kudankita, Chiyoda-ku, Tokyo 4-7 No. 7 Shin Kawashiro Brick Co., Ltd. (72) Inventor Toshio Horiuchi No. 4-7 Kudankita 4-Chome, Chiyoda-ku, Tokyo F Term of Shin Kawashiro Brick Co., Ltd. (reference) 4E004 FA10 FB10 NC01 4E014 DA03 FA01 GA01 MA12 4G031 AA04 AA12 AA30 BA25 GA02 GA11

Claims (3)

[Claims] 1. A refractory used as a refractory material for at least a portion of a continuous cast refractory member made of steel composed of a main body refractory material and a refractory material in contact with molten steel is C
aO: 5 to 40 mass%, SiO ₂ : 2 to 30 mass%, Z
and rO _2: with 35 to 80 wt%, carbon: less than 5 mass% (including zero) continuous casting refractory member refractories steel, which is a. 2. The refractory for a continuous cast refractory member of steel according to claim 1, wherein the refractory contains 0.1 to 20 mass% of one or more low melting point raw materials each having a melting point of 1400 ° C. or less. . 3. The refractory material for continuous casting refractory steel of claim 1 or 2, wherein the refractory material for continuous casting steel is a long nozzle, an upper nozzle, a lower nozzle, a dipping nozzle, a stopper head or a slide plate. .