JP2000290080A - Sliding nozzle plate refractories - Google Patents

Abstract

(57) [Problem] To produce unfired brick excellent in strength and corrosion resistance at 1000 ° C or less. SOLUTION: After adding one or both of aluminum nitride and aluminum oxynitride to a refractory material including alumina or carbon powder, metal silicon powder, and the like, which are the main components of unfired brick, a thermosetting resin and A boron compound is added. By this method, 1000 ° C
An inexpensive unfired brick having excellent strength and corrosion resistance in the following intermediate temperature ranges can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate brick of a sliding nozzle plate (hereinafter, referred to as an SN plate) mounted on a ladle or a tundish in a steelmaking plant, and particularly to an unfired brick having excellent corrosion resistance. is there.

[0002]

2. Description of the Related Art An SN plate brick is one in which one of two plate refractories provided with holes is fixed and the other is slid to open and close the plate brick to flow and stop molten steel flow. Alumina-carbon is mainly used as the plate brick material.

[0003] The form of damage to the SN plate brick is as follows.
These include abrasion due to molten steel flow, cracking due to rapid thermal shock, abrasion loss on sliding surfaces, surface roughness due to deterioration of brick structure due to carbon oxidation, and chemical erosion due to molten steel or slag. Therefore, the SN plate brick should have excellent properties such as abrasion resistance, heat spalling and corrosion resistance as a characteristic to be provided. However, the conventional SN plate brick can be obtained by adjusting the distribution of each characteristic according to the use conditions. And high durability such as extended life.

[0004] In addition, among the various properties, the fired SN which has been conventionally used for the purpose of further improving the heat-resistant spalling property, streamlining the manufacturing process of the brick, and reducing the manufacturing cost.
In addition to plates, unfired SN plates that do not perform firing are also used.

[0005]

Since the unsintered SN plate is not fired at a high temperature, its strength at a temperature of 1000 ° C. or less is low. There is a problem that the carbon in the brick is oxidized by the air flowing from between the surfaces, and the surface is remarkably roughened due to the weakening of the structure, and the durability is inferior to that of the baked SN plate. Therefore, in order to increase the service life of the unfired SN plate, it is considered that prevention of strength deterioration and improvement of oxidation resistance in an intermediate temperature range of 1000 ° C. or less are effective means.

To solve this problem, see, for example,
An improved technique disclosed in 3-57380 has also been proposed. According to this technique, the strength is improved and an antioxidant effect is achieved by adding a metal powder having a melting point of 1000 ° C. or lower.

However, since the above-mentioned prior art uses a low melting point metal, the linear expansion coefficient of the material itself increases as the amount of the metal added increases. As a result, SN
When used in a form constrained by a 3 to 4 mm thick hoop (iron headband for preventing cracking during use) such as a plate, warpage is likely to occur.
When using an N plate, a gap is formed between the plates, which causes steel leakage. In addition, in the case of this technology, metallic aluminum is used as the low melting point metal. However, in this case, when the SN plate is used, 4Al +
Since a reaction such as 3C → Al ₄ C ₃ occurs, Al with a large expansion coefficient
There was also a problem that ₄ C ₃ promoted cracks in the structure during repeated heating and cooling.

[0008]

The present invention employs the following means to achieve the above object.

[0009] One or both of aluminum nitride and aluminum oxynitride are added to a refractory material containing alumina or carbon powder and metal silicon powder, which are the main components of the SN plate, and then a thermosetting material such as silicon resin is added. By adding a resin and a boron compound such as boron carbide, an unsintered SN plate brick having excellent corrosion resistance, an improved strength of 1000 ° C. or less, and excellent oxidation and abrasion resistance is obtained.

First, a refractory aggregate 85 mainly containing alumina, a refractory material 85 containing carbon powder and metallic silicon powder.
One or both of aluminum nitride powder and aluminum oxynitride powder or 0.5 to 15 parts by weight are added to 99.5 parts by weight. The reason for using aluminum nitride powder or aluminum oxynitride powder is that these materials have very good corrosion resistance to molten metal,
This is because the corrosion resistance of the brick is improved. If the amount is less than 0.5 part by weight, the effect of the addition is not sufficient. If the amount exceeds 15 parts by weight, the corrosion resistance is further improved, but the oxidation resistance is improved. It is not preferable because it leads to deterioration of raw materials and soaring of raw material costs. The particle size of the powder to be added is preferably 500 μm or less in terms of uniform dispersion in the brick structure.

When the alumina-carbon brick composed of the above components is fired at a high temperature of 800 ° C. or more, silicon carbide is generated by a reaction between carbon and silicon, and thereby oxidation of carbon can be suppressed. At the same time, a carbon bond is formed, and a strength of 1000 ° C. or less can be developed.

However, in the case of unfired bricks, the above reaction does not proceed sufficiently in the course of temperature rise during use, so that it is inferior in oxidation resistance, does not increase in strength at 1000 ° C. or lower, and has resistance to heat spoil resistance. It is known to be vulnerable.

Next, in the present invention, 1 to 10 parts by weight of a thermosetting resin such as a liquid phenol resin, a silicon resin, a furan resin and an epoxy resin is added to 100 parts by weight of the refractory material as a binder. 1000 ℃
Suppresses the strength and high temperature oxidation below. If the amount of the thermosetting resin to be added as a binder is less than 1 part by weight, sufficient strength is not exhibited. On the other hand, if the amount exceeds 10 parts by weight, a resin material component volatilized in a brick drying step increases. In addition to causing cracks and cracks in the molded body, the resin is decomposed and volatilized by heat during use to increase the number of pores, resulting in a decrease in strength and a decrease in corrosion resistance.

However, improvement of oxidation resistance and abrasion resistance is not observed only by adding the above-mentioned thermosetting resin. Therefore, in the present invention, further with respect to 100 parts by weight of the refractory material,
0.3 to 5 parts by weight of boron compound such as boron carbide (B ₄ C), zirconium boride (ZrB ₂ ), titanium boride (TiB ₂ ), aluminum boride (AlB ₂ , AlB ₁₂ ) is externally added By doing so, a brick exhibiting excellent properties with respect to oxidation / abrasion resistance and corrosion resistance is generated.

Here, the action of the boron compound is as follows. When the boron compound reacts with oxygen at 400 ° C. or higher, a vitreous film is formed, and the effect of suppressing the oxidation of carbon is obtained by this film. Deterioration of strength in an intermediate temperature range of not more than ℃ can be eliminated. If the amount of the boron compound is less than 0.3 parts by weight based on 100 parts by weight of the refractory material, a sufficient oxidation resistance cannot be obtained. On the other hand, if it exceeds 5 parts by weight, the formation of a vitreous film increases, and the hot strength and corrosion resistance deteriorate.

The boron compound powder used in the present invention preferably has a particle size of 200 μm or less. This is 2
If the thickness exceeds 00 μm, the kneading property is deteriorated, the uniformity in the brick is lost, and the oxidation resistance is reduced.

[0017] The brick according to the present invention is obtained by kneading, forming and drying raw materials mixed in a predetermined ratio to obtain an SN plate brick having a shape suitable for the intended use. Drying is performed for the purpose of volatilizing and curing the solvent component in the thermosetting resin added as a binder. The drying temperature is 200-800
C., but more preferably in the range of 300 to 600C.

In the above-described steps, conventionally, unsintered SN
Deterioration of strength at 1000 ° C. or less, which has been regarded as a weak point of the plate, can be avoided without adding a low melting point metal. Further, ZrO ₂ , TiO ₂ , Al ₂ O ₃ newly generated in the process
Is a high melting point compound that fills voids in the tissue,
Contribute to the elaboration of the organization.

[0019]

[Example] Alumina and alumina as refractory aggregates
By mixing zirconia, carbon black powder, metal silicon powder, aluminum nitride powder, and aluminum oxynitride powder in the proportions shown in Table 1, adding a predetermined binder and boron compound thereto, kneading, molding and drying,
An SN plate was manufactured. Further, the quality characteristic values were measured, and the results are shown in Table 1. As a result, in the examples of the present invention to which aluminum nitride powder and aluminum oxynitride powder were added, improvement in corrosion resistance was recognized as compared with the comparative example.

In the following, the strength is measured by a three-point bending method.

[0021]

[Table 1]

As a refractory aggregate, a binder and an additive are added to a mixture of 74 parts by weight of alumina, 15 parts by weight of alumina-zirconia, 3 parts by weight of carbon black, 5 parts by weight of metal silicon powder, and 3 parts by weight of aluminum nitride. By kneading, molding and drying the added material, SN
Plates were manufactured and quality characteristics were investigated. Table 2 shows the measurement results of the amounts of the binder and the additives (indicated by the outer amount relative to 100 parts by weight of the composition) and the quality.

[0023]

[Table 2]

As a refractory aggregate, a binder and an additive are added to a mixture of 73 parts by weight of alumina, 15 parts by weight of alumina-zirconia, 3 parts by weight of carbon black, 3 parts by weight of metal silicon powder, and 6 parts by weight of aluminum oxynitride. The SN plate was manufactured in the same manner as in the example, with the addition. Table 3 shows the quality measurement results.

[0025]

[Table 3]

In producing the SN plate, a predetermined refractory aggregate and a premixed carbon powder, metal silicon powder, aluminum nitride and / or aluminum oxynitride are mixed, and a binder and an additive are added thereto. After mixing, they were kneaded. This was molded by a friction press and dried at 300 ° C. As quality characteristics, strength, oxidation / abrasion, and erosion of molten steel were investigated.

As is apparent from these results, those of the examples according to the present invention are superior in all of strength, oxidation / abrasion resistance and corrosion resistance as compared with those of the comparative examples manufactured by the conventional method at the same time. I understand.

[0028]

As described above, according to the present invention, 100
An unfired alumina-carbon SN plate brick excellent in strength at 0 ° C. or lower, oxidation / abrasion resistance and corrosion resistance can be produced. Therefore, the manufacturing cost of the sliding nozzle plate is reduced compared to conventional products.
The service life can be improved and the operation can be stabilized.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) B22D 41/32 B22D 41/32 (72) Inventor Seijiro Tanaka 1576 Nakahiro, Higashi-oki, Ako-shi 2 Kawasaki Furnace material Co., Ltd. F term (reference) 4E014 MA12 4G033 AA02 AA14 AA18 AB08 AB10 AB23

Claims (1)

[Claims] 1. A refractory material comprising a refractory aggregate mainly composed of alumina, carbon powder and metallic silicon powder.
One or both of aluminum nitride powder and aluminum oxynitride powder are added in an amount of 0.5 to 15 parts by weight with respect to 9.5 parts by weight, and at least one or more thermosetting resin is added in an amount of 1 to 10 parts by weight , The boron compound in 0.1.
An unfired brick for a sliding nozzle obtained by externally adding 3 to 5 parts by weight.