JPH0723254B2 - Refractory material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory material, and more particularly to a steelmaking nozzle having high functionality with four essential components ZrO ₂ , CaO, SiO ₂ and B ₂ O _3. The present invention relates to an electrofused refractory material used in.

[0002]

2. Description of the Related Art A refractory material used as a nozzle material used in the continuous casting of conventional steelmaking is one of fused silica material, alumina and / or alumina-silica high alumina material, zirconia material, zirconia-calcia material, or the like. Mainly composed of oxide refractory materials such as magnesia and / or magnesia-alumina spinel material under two or more or special use conditions. Graphite material, carbonaceous material (carbon material) carbide material and silicon nitride material Nozzles that are kneaded, molded, and fired using a refractory material composed of one or two or more of them are used.

The long nozzles and dipping nozzles used for these continuous casting ladle, tundish, etc. were initially made of fused silica, but the quality was stable and the casting efficiency was high. In addition, casting cost and yield of slabs have been improved, and continuous casting is also aimed at multiple casting, and fused silica material has large melting loss and problems such as nozzle hole expansion and nozzle damage. Therefore, in order to cope with this, multi-continuous casting operation cannot be performed, and in order to cope with this, various oxide fire-resistant materials such as fused silica material, alumina material, alumina-silica high alumina material, zirconia material, zirconia-calcia material, etc. Under one or more of the materials or under special usage conditions, the magnesia material and / or the alumina-magnesia spinel material are mainly used, and the graphite material and the carbon material One or two of them are transferred to a nozzle manufactured by mixing one or more of carbide materials and nitride materials as needed, and it has been effective in dealing with multi-continuous casting operation, but on the other hand The oxide (non-metallic inclusions) mainly composed of aluminum adheres and accumulates on the inner wall of the nozzle hole, and smooth casting operation cannot be performed, and the non-metal inclusions adhered and accumulated on the inner wall of the nozzle hole are peeled off and mixed. As a result, a big problem in terms of operation and quality, which causes a large sand scratch, is occurring.

In order to solve this problem, the above-mentioned various refractory materials are combined or the structure of the nozzle is made into a multi-layered structure, and an inert gas is blown from the inner wall of the nozzle to protect the inner surface by a gas sealing effect. Although various measures have been taken to prevent such problems, the improvement has been urgently required under the present circumstances because it has not yet been able to achieve sufficient effects.

[0005]

PROBLEM TO BE SOLVED BY THE INVENTION Provided is a refractory material which has a special function of maintaining heat resistance and corrosion resistance and capable of preventing adhesion and deposition of non-metallic inclusions mainly composed of aluminum oxide existing in molten metal. This is a technical issue.

[0006]

The present invention is intended to prevent the adhesion and deposition of aluminum oxide, which is the main component of the non-metallic inclusions in the molten metal, on the inner wall of the nozzle and to improve the operation and quality.

The present invention has various activities with a focus on the fact that it has a high activity with alumina, which is the main component adhered and deposited on the inner wall of the nozzle, and causes a chemical reaction to form a low-melting substance, which causes it to flow out. As a result of stacking, it was found that the refractory material containing CaO as the main component is the most effective. Furthermore, Ca
Among the refractory materials containing O as a main component, in order to obtain a material having higher reactivity and a high anti-adhesion effect, ZrO 2 is a main component of the adhered substance, has high reactivity with alumina, and has high heat resistance.
₂ ． CaO and 3CaO. SiO ₂ , 2CaO. Si
O ₂ , 3CaO. It has a composite polycrystalline composition such as 2SiO ₂ .
Moreover, in order to make it a stable material, ZrO ₂ is added in an amount of 7% to 50%,
_{CaO40% ~62%, SiO 2 6} % ~20%, B 2 O 3
We have developed an electromelting refractory material in which 1% to 5% does not contain these 4 components as essential components and the total content of the 4 components is 95% or more.

[0008] The refractory material γ2CaO heat resistance and heat, CaO even for stability is high thermal changes in the crystal against thermal changes due to cooling or the like, the crystal changes in SiO ₂ system material.
SiO ₂ is a material that is stable and does not cause a pulverization phenomenon due to generation, and has high reactivity with non-metallic inclusions containing alumina as a main component.

Next, the reason for limitation will be described.

Content of ZrO ₂ 7% to 50% ZrO ₂ in the present material forms a compound in an equimolar amount with CaO to form ZrO ₂ . 2270, which is CaO
It is a material with a high melting point of ℃. This is because in order to maintain the heat resistance and corrosion resistance of this material, if ZrO ₂ is 7% or less, this characteristic cannot be utilized, and if it exceeds 50%, the reactivity with alumina is slightly lowered.

CaO content 40% -62% CaO content is equimolar compound Zr with ZrO _2.
O ₂ . The amount and heat resistance constituting CaO, for maintaining corrosion resistance, between the SiO ₂ 3CaO. SiO ₂ (melting point 2065 ° C.) and 2CaO. SiO ₂ (melting point 2130
(° C) is the content necessary for forming. If it exceeds 62% within the constitutional range of this material, the formation of free lime is observed, a hydration reaction occurs, the stability of the material is impaired, and if it is less than 40%, the heat resistance is impaired.

SiO ₂ content 6% to 20% The content of SiO ₂ is 3CaO with CaO in order to maintain heat resistance, corrosion resistance and functionality with CaO.
SiO ₂ , and 2CaO. Since it is necessary to use up to SiO ₂ as the main product, within the composition range of this material, 20
%, The heat resistance will be impaired, and if it is less than 6%, free lime will be formed, causing a hydration reaction and impairing the stability of the material.

If the content of B ₂ O ₃ is 1% to 5% (a) 1% or less, the crystal stability of the material cannot be sufficiently maintained. (2CaO.SiO ₂ → γ2CaO.Si
Since the effect of preventing crystal transition of O ₂ is incomplete, a pulverization phenomenon occurs. (B) If it is 5% or more, heat resistance becomes a problem.

[0014]

EXAMPLES Using the raw materials shown in Table 1, Table 2 shows Examples, Comparative Examples within the scope of the present invention and outside the scope of the present invention.

[0015]

[Table 1]

Each of the raw materials listed in Table 1 is 74 μm alone.
Grind into the following and mix (lime is converted by the amount of CaO. The lime material may be lime hydroxide, lime carbonate, etc.), mix and knead with a mixer, and 6 × 6 × 8 mm with a briquette machine. After granulation and drying, it is melted using a three-phase electric furnace, tilted in the furnace, transferred to a ladle, and cooled in the ladle for production. Heat resistance test from this melt is 30 ×
A 30 × 90 mm test piece is cut out, and the hydration resistance test material is crushed to prepare a sample of 3 to 2 mm, and the stability of crystals and the change of mineral composition by heating and cooling are also performed using the same sample. . The functional test is crushing the melted material to 3-1 mm 45%
5% of resin is added to 1.0-0.1mm 15%, 0.1mm or less 40%, and mixed and kneaded in a wet pan to obtain 100
A sample for evaluation test is manufactured by molding at a pressure of 0 kg / cm ² and firing in a tunnel kiln with a maximum temperature of 1450 ° C. The evaluation test results are shown in Table 2.

[0017]

[Table 2]

[0018]

EFFECTS OF THE INVENTION The refractory material of the present invention is a material ZrO having a high reactivity with alumina which is a main component of non-metallic inclusions in molten steel.
₂ ． CaO, 3CaO. SiO ₂ , 2CaO. The SiO ₂ as a main composition material, and ZrO _2, CaO because it is contained B ₂ O ₃ as a crystal stabilizer, a ZrO ₂ that is to SiO _2, B ₂ O _3, the essential components of 7% to 50 %, CaO
Is 40% to 62%, SiO ₂ is 6% to 20%, and B ₂ O ₃ is 1% to 5%, heat resistance, corrosion resistance, digestion resistance, and crystal form stability are excellent. Even after repeated cooling, 2CaO. Γ2CaO without any transition of the crystalline forms of SiO ₂ or the like. It has sufficient characteristics as various refractory materials such as no formation of SiO ₂ and has sufficient functionality such as very high contact reactivity with alumina. Since this material is manufactured by melting in an electric furnace, it has a uniform and high crystallinity, and is a material that maintains stable quality. Nozzle materials manufactured using this material have extremely high reactivity with non-metallic inclusions mainly composed of alumina that are present in molten steel, so the inner wall of the nozzle hole of long nozzles for continuous casting and immersion nozzles It is very effective in preventing the deposition of non-metallic inclusions such as alumina that deposit and deposit on the surface. The results of the examples shown in Table 2 are based on the following judgment criterion test method. <Heat resistance> (Indicates the state after cooling in the holding furnace at a predetermined temperature for 3 hours.) A No change B Each shows a softened state C Semi-molten state D State that is melted and permeated on the pedestal sample 30 from the melt It is cut out and made into a size of x30x30mm. <Hydration resistance> The electric melt is crushed and adjusted to 3 to 2 mm to prepare a sample. Put this sample in water, and after boiling for 30 minutes, 10
Dry for 10 hours in a constant temperature bath at 5 ° C. a. Weight increase (digestion amount) b. Pulverization rate (amount (less than 2 mm) (weight percentage)) <Mineral composition> a. By X-ray diffraction test of the original material b. Hydration test-by X-ray diffraction test of the material after drying 1. CaO 2.3 CaO. SiO ₂ 3.2 CaO. SiO ₂ 4.3 CaO. 2SiO ₂ 5. γ2CaO. SiO ₂ 6. ZrO ₂ . CaO 7. Ca (OH) ₂ <Functional test> The molten material is crushed to 3-1 mm 45%, 1
Resin 5 containing ~ 0.1mm 15% and 0.1mm or less 40%
%, After kneading, pressure molding at a pressure of 1000 kg / cm ² , and baking at 1450 ° C. to obtain a sample. Sample size 5
The state after applying 44 μm of alumina to 2 mm thickness to 0 × 50 × 20 mm and keeping it at 1550 ° C. for 30 minutes and cooling in the furnace is shown. A No change B 1/3 change is present C 2/3 change is present D Mostly react

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Claims (1)

[Claims] In a refractory material containing four components ZrO ₂ , CaO, SiO ₂ and B ₂ O ₃ as essential components, ZrO ₂ 7% to 50%, Ca
_{O40% ~62%, SiO 2 6} % ~26%, B 2 O 3 1%
~ 5%, the total amount of these four is 95% or more and 3Ca
O. SiO ₂ , 2CaO. SiO ₂ , CaO, SiO ₂ and ZrO ₂ . ZrO ₂ , CaO, SiO _2. , Characterized in that it is mainly composed of the mineral composition of CaO. B ₂
O ₃ type fused fused refractory material.