JPH0723253B2 - Refractory material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to refractory materials, more particularly CaO, 3 of SiO _2, B ₂ O ₃
TECHNICAL FIELD The present invention relates to an electromelting refractory material having high functionality with essential components used for a steelmaking nozzle.

[0002]

2. Description of the Related Art Refractory materials used as materials for nozzles used in continuous casting of conventional steelmaking are one of fused silica materials, alumina and / or alumina-silica high alumina materials, zirconia materials, and zirconia-calcia materials. Alternatively, under two or more or special use conditions, oxide refractory materials such as magnesia and / or magnesia-alumina spinel materials are mainly used, and graphite material, carbonaceous material (carbon material) carbide material, silicon nitride A nozzle is used in which a refractory material composed of one or two or more raw materials is kneaded, molded, and fired.

The long nozzles and dipping nozzles used for these continuous casting ladle, tundish, etc. were initially made of a fused silica material, but the stability of quality and casting High efficiency, casting cost, and improved yield of slabs have been promoted, and continuous casting is also aimed at multi-casting, and fused silica material has large melting loss and nozzle hole expansion and nozzle damage. However, in order to deal with this problem, fused silica materials, alumina materials, alumina-silica-based high alumina materials, zirconia materials, zirconia-calcia materials, etc. One or more refractory materials, and under special use conditions, magnesia materials and / or alumina-magnesia spinel materials are mainly used. One or two of the carbonaceous materials and, if necessary, one or more of the carbide material and the nitride material are mixed to produce a nozzle, which is effective in dealing with the multi-continuous casting operation. On the other hand, on the other hand, the oxide mainly composed of aluminum and (non-metallic inclusions) adhere and deposit on the inner wall of the nozzle hole, which prevents smooth casting work, and the non-metallic inclusion that adheres and deposits on the inner wall of the nozzle hole. Things have fallen off,
A major problem in terms of operation and quality has arisen, such as being a cause of large sand scratches when mixed.

In order to solve this problem, the above-mentioned various refractory materials are combined and the nozzle has a multi-layer structure in terms of the structure of the nozzle, and an inert gas is blown from the inner wall of the nozzle to protect the inner surface by the gas sealing effect. Although various measures have been taken to prevent this, there is a strong demand for this improvement under the present circumstances because it has not yet been able to achieve sufficient effects.

[0005]

In view of the above, heat resistance,
It is a technical object to provide a refractory material which has a special function of keeping corrosion resistance and preventing adhesion and deposition of non-metallic inclusions mainly composed of aluminum oxide present in the molten metal.

[0006]

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

The present invention focuses on the fact that it has a high activity with alumina, which is the main component that adheres to and deposits on the inner wall of the nozzle, and that a low-melting substance is generated and flows out by causing a chemical reaction, and various studies have been repeated. As a result, they found that the refractory material containing CaO as the main component was the most effective. Further, in order to make the material having higher reactivity and higher anti-adhesion effect among the refractory materials containing CaO as the main component, the molar ratio of CaO to SiO ₂ is 2: 1 to 1 because of the main component of the deposit and alumina. 3:
2 and 1% to 5% of B ₂ O ₃ as a crystal stabilizer.
Add these three components as essential ingredients and the total amount of the three components is 95
We have developed an electro-melting refractory material composed of more than 100%. This refractory material has high heat resistance and high crystal stability even with changes in heat due to heat reception, cooling, etc. and is stable against changes in heat and does not cause phenomena such as pulverization. It is a material having a high reactivity with non-metallic inclusions containing alumina as a main component (no generation of γ2CaOSiO ₂ ), and provides this.

Next, the reason for limitation will be described. The ratio of CaO and SiO ₂ (molar ratio 2: 1 to 3: 2) <a> When the ratio is 3: 2 or less, the heat resistance is greatly impaired and the melting loss becomes very large. <B> When the ratio is 2: 1 or more, the heat resistance becomes high, and the reactivity with non-metallic inclusions containing alumina as a main component becomes small although CaO is contained in a large amount. If the content of B ₂ O ₃ (1% to 5%) <a> 1% or less, the crystal stability of the material cannot be sufficiently maintained. (Powdering phenomenon occurs due to the incomplete crystal transition preventing effect of 2CaOSiO ₂ → γ2CaOSiO _2. ) <B> If it is 5% or more, heat resistance becomes a problem.

[0009]

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.

[0010]

[Table 1]

Each of the raw materials shown in Table 1 is 74 μm alone.
Grind into the following (compound lime in terms of CaO content, the lime material may be lime hydroxide, lime carbonate, etc.), mix and knead with a mixer, and 6 × 6 × with a briquette machine. After granulating to 8 mm, it is dried, then melted using a three-phase electric furnace, tilted and transferred to a ladle, and cooled in the ladle for production. A heat resistance test cuts out a test piece of 30 × 30 × 30 mm from this melt, and a hydration resistance test material is crushed to prepare a sample of 3 to 2 mm, and the stability of crystals by heating and cooling, a ridge The composition is also changed using the same sample. The functional test is to pulverize the molten material to 3-1mm 45%, 1.0-0.1mm 15%, 0.1mm
Then, 5% of resin is added to 40%, mixed and kneaded in a wet pan, molded at a pressure of 1000 kg / cm ² , and fired in a tunnel kiln having a maximum temperature of 1450 ° C. to produce a sample for evaluation test. The evaluation test results are shown in Table 2.

[0012]

[Table 2]

[0013]

INDUSTRIAL APPLICABILITY The refractory material of the present invention is CaO, S which has high reactivity with alumina which is a main component of non-metallic inclusions in molten steel.
Consists of iO ₂ and B ₂ O ₃ as essential components, and CaO
And SiO _{2 in} a molar ratio of 2: 1 to 3: 2 and B ₂ O ₃ 1
% To 5%, it has excellent heat resistance and digestion resistance and stability of crystal form. Γ2CaOS has no transition of crystal form such as 2CaOSiO ₂ even after repeated heating and cooling.
It has sufficient characteristics as various refractory materials, such as no generation of iO 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 adhesion and accumulation of alumina-based non-metallic inclusions that adhere and accumulate on the surface. In Table 2, <Heat resistance> (indicates the state after cooling in the holding furnace at a predetermined temperature for 3 hours) A: No change B: Softened state C: Semi-melted state It is cut out from the melt and cut into a size of 30 × 30 × 30 mm. <Hydration resistance> The electric melt is crushed and adjusted to 3 to 2 mm to prepare a sample. Put this sample in water and boil 30 minutes later 1
Dry for 10 hours in a constant temperature bath at 05 ° C. a. Weight increase (digestion amount) b. Pulverization rate (amount (less than 2 mm) (weight percent)) <Mind 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 2.3CaOSiO ₂ 3.2CaOSiO ₂ 4.3CaO 2SiO ₂ 5. CaOSiO ₂ <Functional test> The molten material is crushed and crushed by 3 to 1 mm 45%, 1
Resin 5 containing ~ 0.1mm 15% and 0.1mm or less 40%
%, Added and kneaded, pressure-molded at a pressure of 1000 kg / cm ² , and fired at 1450 ° C. to obtain a sample. Sample size 50
It shows the state after applying 44 μm of alumina and 2 mm thickness to 50 × 20 mm and keeping it at 1550 ° C. for 30 minutes and cooling in the furnace. A No change B 1/3 change is present C 2/3 change is present D Mostly react

Claims (1)

[Claims] In a refractory material containing three components, CaO, SiO ₂ and B ₂ O ₃ , as essential components, the molar ratio of CaO to SiO ₂ is 2: 1.
To 3: 95% to 99% refractory material 2 in the range and B ₂ O ₃ is 1
% To 5%, and the total amount of CaO, SiO ₂ , B ₂ O ₃ is 95% or more, CaO, SiO ₂ ,
B ₂ O ₃ based fused refractory material.