JPH0780709B2 - Refractory material - Google Patents

Description

Detailed Description of the Invention

[0001]

This invention relates to refractory materials. More specifically, the present invention relates to an electromelting refractory material for steelmaking nozzles containing CaO, SiO ₂ and B ₂ O ₃ as essential components.

[0002]

2. Description of the Related Art Conventionally, refractory materials used for steelmaking nozzles are S
io ₂ and / or Al ₂ O ₃ based materials, ZrO ₂ based materials and oxide refractory materials such as magnesia and spinel materials are mainly used for some special use conditions. Graphite material, carbon material,
It is manufactured and provided for use with a material constituted by adding one or more of a carbide material and a nitride material.
Among the steelmaking nozzles, the ones that are currently regarded as the most problematic and important in operation are the long nozzles from the ladle to the tundish and the immersion nozzles from the tundish to the mold when performing continuous casting.

Initially, long nozzles and submerged nozzles were mainly made of fused silica material, but the high efficiency ratio was promoted, and multi-continuous casting was aimed at. From the viewpoint of melting resistance. At present, alumina-graphite materials have been used, but non-metallic inclusions mainly composed of alumina adhere to the inner wall of the nozzle hole, which prevents smooth casting work. There are serious problems in terms of operation and quality, such as large sand scratches caused by the inclusions coming off and mixing.

In order to deal with this, an inert gas is blown from the nozzle material or the inner wall of the nozzle, which has a multilayer structure made of a graphite material in which zirconia or calcium zirconate is arranged on a part or the whole of the inner layer surface of the nozzle, and the gas sealing effect is obtained. Although we are trying to prevent the adhesion and deposition by protecting the inner surface by means of etc., we have not yet achieved a sufficient effect, and there is a strong demand for improvement of these. .

[0005]

[Problems to be Solved by the Invention] It is rich in chemical erosion resistance, maintains heat resistance, and prevents deposition of alumina, which is the main component of non-metallic inclusions adhering to the inner wall of the nozzle hole, from the molten metal. The technical problem is to provide a special functional material to be obtained.

[0006]

The present invention is intended to prevent the aluminum oxide, which is the main component of the non-metallic inclusions in the molten metal, from adhering to and depositing on the inner wall of the nozzle hole, thereby improving the operation and quality. Is.

According to the present invention, in order to prevent the adhesion and deposition of alumina, which is the main component of the adhered deposit on the inner wall of the nozzle hole, it has a high activity with the adhering alumina and causes a chemical reaction to cause low melting. As a result of further research focusing on the generation and outflow of substances, the most effective material is Ca.
We found that it is a refractory material containing O as a main component, but C
aO has a very high reactivity with water and requires great care during the storage of raw materials and the manufacturing of nozzles, and also because it does not cause a hydration reaction. There is a problem that quality and manufacturing are greatly affected by moisture in the atmosphere such as moisture during firing, which makes it difficult to manufacture.
The cost will be very high. For this reason, various studies have been conducted from the viewpoints of material stabilization, high heat resistance, high functionality, etc., and the CaO / SiO ₂ based material has a CaO / SiO ₂ molar ratio of 2: 1 to 3: 1. B ₂ O ₃ as 1
This refractory material, which was developed to be an electro-melting refractory material with the total content of the three components being 95% or more at ~ 5%, has high stability against heat change, heat reception, and thermal change due to cooling, and It is an excellent material having a high reactivity with a non-metallic inclusion containing alumina as a main component, and provides this material.

Next, the reasons for limitation will be described. Ratio of CaO and SiO ₂ (molar ratio 2: 1 to 3: 1) a) When the molar ratio is 2: 1 or less, the heat resistance tends to be greatly impaired, and the reaction with other components proceeds, and the heat resistance increases. Get scarce. b) When the molar ratio is 3: 1 or more, free lime is produced, so that a phenomenon of hydration occurs during storage, production, etc.
Both manufacturing and storage are difficult, and the cost is very high. If the content of B ₂ O ₃ is 1% to 5% a) 1% or less, the stable value of the material cannot be maintained sufficiently (prevention of crystal transition, r2CaOSiO due to heat reception).
_{When 2} (dicalcium silicate) is formed, no pulverization phenomenon occurs. ) B) When it is 5% or more, heat resistance is significantly impaired.

[0009]

EXAMPLES The characteristics of the raw materials used in the examples are shown in Table 1. Using the raw materials shown in Table 1, Table 2 shows 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 2 is 74 μm alone.
Grind into the following and mix (lime is mixed in the amount of CaO.
(The lime material may be either lime hydroxide or limestone), add 5% of non-hydrogen resin in a wet pan and knead, then granulate to 6 × 6 × 8 mm with a briquette machine,
Dry, melt this using a three-phase electric furnace, tilt the furnace, transfer to a ladle, and cool in the ladle to obtain the test material. A heat resistance test cuts out a sample of 30 × 30 × 30 mm from the melt, and a hydration resistance test is crushed to prepare a sample of 3 to 2 mm. In the functional test, the molten material is crushed to 3-1 mm 45.
%, 1-0.1 mm 15%, 0.1% or less 40%, 5% of resin is added, and after kneading in a wet pan, 1000 kg
After pressure molding at a pressure of / cm ^2, a maximum temperature of 1450 ° C. is produced in a tunnel kiln to produce a fired sample. The evaluation test results are shown in Table 2.

[0012]

[Table 2]

[0013]

INDUSTRIAL APPLICABILITY Refractory materials within the scope of the present invention are shown in Example 2
As shown in ( ₃₎ , CaO, SiO ₂ , and B ₂ O ₃ having high reactivity with alumina, which is the main component of the nonmetallic inclusions in the molten steel, are included as essential components. Moreover, CaO and SiO ₂
The molar ratio of 2: 1 to 3: 1 and B ₂ O _{3 to} 1% to 5% are excellent, so that heat resistance, digestion resistance, and crystal form stability are excellent, and heating and cooling are repeated. 2C
aO, SiO ₂ etc. have no crystal form transition, and r2CaO, S
No heterogeneous crystals such as iO ₂ are found to be formed. For example, it has sufficient characteristics as a refractory material and has a very high reactivity at the contact surface with alumina. In addition, since it is manufactured by cooling after being electrically fused, it is possible to obtain a homogeneous material and has a high degree of crystallinity, and the stability of the material is high and the quality of the refractory material and the stability of the quality are high. As shown in Table 2 and Table 2, it has a very high reactivity with alumina and is very effective as an alumina adhesion preventing material as a nozzle material.

In Table 2, heat resistance (showing a state after cooling in a holding furnace at a predetermined temperature for 3 hours) A ... No change B ... showing a softened state C ... semi-molten state D ………… The state that the sample is melted and permeated on the base. The sample is cut out from the melt into a size of 30 × 30 × 30.
make. Hydration resistance The electric melt is crushed and adjusted to 3 to 2 mm for use as a sample.
It This sample was placed in water and boiled for 30 minutes, then kept at 105 ° C.
Dry for 10 hours in a warm bath. a Weight increase amount (digestion amount) b Pulverization rate (Amount less than 2 mm (weight percentage
G)) Mineral composition a According to the X-ray diffraction test of the original material. b Hydration test According to the X-ray diffraction test of the dried material. 1 CaO 2 3 CaOSiO₂  32 CaOSio₂  45 CaO3SiO₂  5 CaOSiO₂  6 CaOZrO₂  7 ZrO₂  8 Ca (OH)²  Functionality test Melt material is crushed and 3-1mm 45%, 1-0.1mm
15% and 0.1% or less 40% are mixed and resin 5% is added.
After kneading and kneading, 1000 kg / cm²Pressure molding
After that, the sample is baked at 1450 ° C. and the size of the sample is 50 ×
Apply 50mm x 20mm alumina 44mm under 2mm to 30
The state after keeping at 1550 ° C. for 1 minute 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

Claims (1)

[Claims] In a refractory material containing three components, CaO, SiO ₂ and B ₂ O ₃ , as essential components, the ratio of CaO and SiO ₂ is 2: 1 in molar ratio.
95% to 99% of refractory material composed of 3: 1, B ₂
CaO, Si characterized in that O ₃ is 1% to 5% by weight and the total amount of CaO, SiO ₂ , B ₂ O ₃ is 95% or more.
An electrofused refractory material used as a material for an O ₂ and B ₂ O ₃ based steelmaking nozzle.