JPH1179854A - Carbon-containing monolithic refractory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject refractory excellent in corrosion resistance and slag resistance to moisture and capable of improving strength after heating by using a zirconia-based raw material whose particle diameter is specific and an alumina-based raw material at a specific weight ratio as main raw materials and further including a carbonaceous raw material in a specific amount. SOLUTION: This refractory uses a zirconia-based raw material (e.g. electromelting zirconia), preferably stabilized with calcia, yttria or the like, having <=1 mm particle diameter and an alumina-based raw material (e.g. electromelting alumina) at a weight ratio of >=1 and further contains the carbonaceous raw material in an amount of 3-20 wt.%, preferably 5-15 wt.%. The carbonaceous raw material has heat-melting and self hardening properties and is preferably spherical and contains carbon raw material (e.g. phenol resin) in an amount of 3-10 wt.%. Carbon black having high hydrophilic property is preferable as the carbonaceous raw material other than above carbonaceous raw material. As a result, the resultant refractory is further compacted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon-containing amorphous refractory used for an immersion nozzle, a slide gate plate, a vertical nozzle, and the like.

[0002]

2. Description of the Related Art At present, materials such as alumina-carbon and zirconia-carbon are widely used for immersion nozzles. For the slide gate plate and upper and lower nozzles,
Brick materials (regular refractories) such as high alumina, alumina-carbon, alumina-zirconia-carbon, and magnesia-spinel are widely used.

[0003] Further, high-alumina materials, alumina-spinel materials, and the like are known as amorphous refractories, and are widely used for lining materials such as ladles, tundishes, and mass blocks. In recent years, in order to improve the infiltration resistance, alumina-carbon materials, magnesia-carbon materials, and
Development of carbon-containing irregular shaped materials such as 315858) is also in progress.

Among non-carbon amorphous refractories, JP-A-63-103869 discloses a glass phase-containing zirconia raw material 85 as an amorphous refractory containing a zirconia raw material which is expected to have higher corrosion resistance than the above materials. ~ 99
A zirconia-based amorphous refractory comprising about 1% by weight and 15 to 1% by weight of alumina cement is disclosed. JP-A-2-
No. 9774 discloses a cast tub refractory for hot metal pretreatment lances containing silica as a main component and 30 to 67% by weight of a zirconia-based raw material added thereto. JP-A-3-17
No. 4369 discloses an amorphous refractory comprising 50 to 90% by weight of chromia, 5 to 20% by weight of alumina, 1 to 20% by weight of zirconia and 1 to 10% by weight of a mineralizer. Japanese Unexamined Patent Publication (Kokai) No. 4-36069 discloses a zirconia-based refractory raw material of 3 to 20 parts by weight per 100 parts by weight of basic refractory raw material.
A zirconia-based material-added basic pouring material containing parts by weight is disclosed.

[0005] By the way, for the purpose of simplifying the manufacture of the immersion nozzle, it is desired to switch from a fixed refractory to an irregular refractory. However, conventional amorphous refractories have a problem that their corrosion resistance to slag and mold powder is inferior. In addition, the present inventors have recently developed Mg0-
It is difficult to obtain sufficient corrosion resistance even under C-shaped irregular refractories (Japanese Patent Application No. 6-315858) under conditions where slag or mold powder having a basicity of 1 or less is used, such as a immersion nozzle. Met.

[0006] Zirconia raw material is known as one of the materials that can be expected to have the highest corrosion resistance for low basicity mold powder, and this raw material (aluminum cement, silica, chromia) is used as an amorphous material. , Basic raw materials). However, such amorphous refractories have not been sufficiently satisfactory in terms of infiltration resistance and spalling resistance.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a carbon-containing amorphous refractory which is excellent in corrosion resistance and slag infiltration resistance and can be expected to improve service life.

[0008]

The carbon-containing amorphous refractory according to the present invention comprises a zirconia raw material and an alumina raw material as main raw materials, and has a weight ratio of the zirconia raw material and the alumina raw material having a particle size of 1 mm or less. Is zirconia-based material / alumina-based material ≧ 1, and further 3 to 20% by weight
Characterized by containing the following carbonaceous raw material.

According to the present invention, a zirconia raw material and an alumina raw material having a specific particle size are used as main raw materials, the ratio of these raw materials is specified, and a specific amount of a carbonaceous raw material is further contained. Thereby, a carbon-containing amorphous refractory excellent in corrosion resistance and slag infiltration resistance can be obtained.

That is, when a zirconia-based raw material is used, excellent slag erosion resistance is exhibited, but the strength after heating is greatly reduced. This is considered to be because the zirconia raw material undergoes a remarkable volume change according to the phase transformation (monoclinic / tetragonal). By stabilizing zirconia with calcia, yttria, etc., the volume stability is greatly improved.
If the temperature is increased to more than 500 ° C., the effect of the stabilizer is lost, and the tissue is easily relaxed and cracked.

[0011] From the above, the present invention has a particle diameter of 1 µm.
The following zirconia raw material and alumina raw material are used in combination, the ratio thereof is set to zirconia raw material / alumina raw material ≧ 1, and 3 to 20% by weight of carbon raw material is blended to provide excellent corrosion resistance and high resistance. It is possible to obtain a carbon-containing amorphous refractory which has improved strength after being heated without impairing slag erosion.

In the carbon-containing irregular shaped refractory according to the present invention, it is preferable that the carbonaceous raw material contains 3 to 10% by weight of a carbon material having a heat melting property and a self-curing property. By using such a carbon material having heat melting and self-curing properties together, it is possible to densify the product constructed from the obtained amorphous refractory, and to improve the strength after being heated. .

It is preferable that the carbon material (for example, phenol resin) having the heat melting property and the self-curing property is spherical. By using a carbon material having such a shape and having heat-melting and self-curing properties, it is possible to further densify a product constructed from the obtained amorphous refractory.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
This carbon-containing amorphous refractory is mainly composed of a zirconia raw material and an alumina raw material, and the weight ratio of the zirconia raw material having a particle size of 1 mm or less and the alumina raw material is zirconia raw material / alumina raw material ≧ 1. And three more
Contains ~ 20% by weight of carbonaceous material.

As the zirconia raw material as the main raw material, a zirconia raw material stabilized with calcia, yttria or the like is preferable. As the alumina raw material, for example, fused alumina, sintered alumina, alumina cement, hydraulic alumina and the like can be used.

The weight ratio of the zirconia-based raw material / alumina-based raw material is such that the particle size is 1 mm, which has a large influence on the corrosion resistance.
In the following, it is important that the number is 1 or more. If the weight ratio between the raw materials is less than 1, the characteristics of the zirconia raw material cannot be sufficiently exhibited, and the slag erosion resistance of the obtained amorphous refractory may be significantly reduced.

The zirconia raw material has a particle size of 1 m.
When the zirconia raw material has a particle diameter of more than 1 mm, the weight ratio of the zirconia-based material / alumina-based material is arbitrary. The effect of expansion and contraction on the pressure increases. Further, it is possible to increase the amount of the alumina raw material which is inexpensive even in view of the raw material cost.

The carbonaceous raw material is indispensable,
Add 3-20% by weight. Add 3 carbon materials
If the content is less than 10% by weight, sufficient slag infiltration resistance cannot be obtained, and high durability cannot be expected. If the amount of the carbonaceous material exceeds 30% by weight, the corrosion resistance of the obtained refractory may be reduced. A more preferable addition amount of the carbonaceous raw material is 5 to 15% by weight.

As the carbonaceous raw material, various ones can be used, but it is desirable to use a phenolic resin, pitch or the like having heat-melting and self-curing properties in combination. In particular, heat-meltable and self-curing carbon such as phenolic resin and pitch has a residual carbon ratio of about 50%, and when 10% by weight or more is added as a carbonaceous raw material, corrosion resistance may decrease due to an increase in porosity. Further, since the phenol resin is thermosetting, it is necessary to use the phenol resin together with alumina cement or the like to remove the mold without heating to supplement the curing characteristics at room temperature.

As the phenol resin, a water-soluble phenol resin or the like can be used. However, when used alone as a carbonaceous raw material, it becomes necessary to add excess water as the viscosity increases, and as a result, the porosity increases, and high durability cannot be expected. On the other hand, a water-insoluble powdery phenol resin excellent in dispersibility in water can be poured with an appropriate amount of water even if the phenol resin is used alone. As the powdered phenolic resin, for example, resol, novolak and the like can be used. In the powdered phenolic resin, the spherical powder is more excellent in dispersibility in water than the crushed powder, and it is possible to make the product constructed from the obtained amorphous refractory more dense.

As a material other than the heat-meltable and self-curing carbonaceous material, carbon black having a high hydrophilicity is most effective. Since scale-like graphite used for MgO-CO brick has high hydrophobicity, it is preferable to perform ozone treatment or dispersant treatment in advance. Although these carbonaceous raw materials are easy to obtain a dense structure due to their high residual carbon ratio, products constructed from the obtained amorphous refractories by using in combination with the above-mentioned hot-melt / self-curing carbon Can be densified, and the strength after being heated can be improved.

The carbon-containing amorphous refractory according to the present invention permits addition of organic fibers for improving spalling resistance and addition of metal fibers for preventing falling off. . In order to prevent oxidation, a coating material may be applied to the surface of the substrate or an antioxidant may be added to the inside of the substrate.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail. (Example) Formulation No. shown in Table 1 below. The raw materials Nos. 1 to 6 were mixed and kneaded with clean water using a tabletop mixer having a capacity of 5000 ml (mL). 40mm × 4
Pour into a 0 mm x 160 mm formwork, train for 24 hours,
Six kinds of test pieces were prepared by drying at 350 ° C. for 24 hours.

Each of the obtained test pieces was subjected to various physical property measurements, oxidation tests, and erosion, infiltration tests, and spalling tests by an induction furnace dipping method described below.
The results are shown in Table 1 below. (1) Slag erosion / infiltration test
Measurement of infiltration amount) Method: Taxiway dip method Sample size: 40 mm × 40 mm × 160 mm Erosive: Synthetic slag (C / S = 1) Test temperature: 1650 ° C.-1 h (2) Spalling test (cracking on cut surface of sample) Measurement: Amount: Method: induction furnace dipping method Sample size: 40 mm x 40 mm x 160 mm Test conditions: 1650 ° C for 5 minutes without preheating, then quenching twice in water for 1 minute, repeated twice

[0025]

[Table 1]

(Comparative Example) Formulation NO. 7-1
The raw materials of No. 1 were mixed and kneaded with clean water in a 5000 mL tabletop mixer. By using these inexpensive materials in the same manner as in the above embodiment, five types of test pieces were produced.

The obtained test pieces were subjected to various physical property measurements, oxidation tests, and erosion / infiltration tests / spalling tests by an induction furnace dipping method in the same manner as in the examples. The results are shown in Table 2 below.

[0028]

[Table 2]

(Conventional example) Formulation No. shown in Table 3 below 12 ~
The 17 materials were mixed and kneaded with clean water using a 5000 mL tabletop mixer. Six kinds of test pieces were prepared by treating these inexpensive materials in the same manner as in the above-mentioned embodiment. However, NO. Reference numerals 16 and 17 denote press-formed products (forming pressure: 1 ton / cm ² ).

The obtained test pieces were subjected to various physical property measurements, oxidation tests, and erosion / infiltration tests / spalling tests by an induction furnace dipping method in the same manner as in the examples. The results are shown in Table 3 below.

[0031]

[Table 3]

As is clear from Tables 1 to 3, the amorphous refractories of Examples have excellent slag erosion / infiltration properties and corrosion resistance as compared with the amorphous refractories of Comparative Examples and the conventional examples. It can be seen that the zirconia-carbon brick of the example has characteristics equivalent to those of the brick.

[0033]

As described above in detail, according to the present invention, there is provided a carbon-containing amorphous refractory which is excellent in corrosion resistance and slag infiltration resistance and is expected to have improved service life and is useful for immersion nozzles, slide gate plates and the like. it can.

Claims (3)

[Claims] 1. A zirconia-based material and an alumina-based material are main materials, and the weight ratio of the zirconia-based material and the alumina-based material having a particle size of 1 mm or less is zirconia-based material / alumina-based material ≧ 1; A carbon-containing amorphous refractory containing 20% by weight of a carbonaceous raw material. 2. The carbon-containing amorphous refractory according to claim 1, wherein the carbonaceous raw material contains 3 to 10% by weight of a carbon material having a heat melting property and a self-hardening property. 3. The carbon-containing irregular shaped refractory according to claim 2, wherein the carbon material having heat melting and self-curing properties is spherical.