KR100701198B1 - Composition of carbonaceous refractory with fine flake graphite powder - Google Patents

Abstract

Provided is a composition of a carbonaceous refractory containing fine flake graphite powder to improve strength and anti-oxidation and to lower modulus of the conventional refractories. The composition of a carbonaceous refractory comprises: 85-95 wt% of oxide aggregates and 5-15 wt% of fine flake graphite powder which is used as a replacement of normal flake graphite powder having an average particle size of 100 micrometers. Preferably, the fine flake graphite powder has an average particle size of 20 micrometers, a filling density of 0.5g/cm^3 or greater, and a globular shape(diameter/height is less than 1/3). As for the oxide aggregates, MgO powder is preferably used.

Description

Composition based carbonaceous refractory with fine flake graphite powder

1 is a photograph showing the microstructure of the impression graphite powder having an average particle diameter of 5㎛.

Figure 2 is a photograph showing the microstructure of the impression graphite powder having an average particle diameter of 15㎛.

Figure 3 is a photograph showing the microstructure of the impression graphite powder having an average particle diameter of 100㎛.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon-based refractory material composition containing finely grained graphite, and in particular, in the refractory material composition, low-elasticity is exhibited by substituting finely-graphed graphite with a constant packing density and an average particle size. It relates to a carbon-based refractory material composition containing fine grained graphite which can improve the pollutability and can exhibit high strength.

In general, carbon-containing refractory materials are used in refractory bricks required in steelmaking and refining processes in steel mills. Since these refractory materials are used in high-density molten steel near 1600 ° C, not only mechanical properties such as room temperature strength and high temperature strength, but also molten steel Properties such as erosion by slag and spalling resistance are required.

For such characteristics, conventionally, carbon aggregates have been produced using natural impression graphite having an average particle diameter of about 100 μm.

On the other hand, recently, in the case of carbon-based refractory containing impression graphite, since the heat dissipation is high due to the high thermal conductivity due to the carbon content in the range of 15-20% by weight, the temperature of molten steel decreases and solidifies from the contact area with the refractory. There is a problem such as lowering the playing efficiency, deterioration of the properties of the refractory by the oxidation of carbon.

In order to solve such a problem, development of a refractory having a reduced carbon content in the refractory is being developed. As a representative example, carbon black is used to reduce the particle size of the carbon aggregate to nano size, thereby reducing the contact area with the carbon aggregate. There has been a study (Japanese Patent 2002-316865, 2002-265210) to increase the same effect with a small amount of content.

However, when only the size of the carbon particles is applied in this way, the mixing efficiency is lowered due to excessive use of the binder resin due to the increase of the specific surface area of the carbon aggregate and aggregation between the small particles, and the oxidation resistance is insufficient. This is being pointed out.

The present invention has been proposed in order to solve the above problems, and the strength and oxidation resistance compared to conventional refractory using the impression graphite particles through the control of the shape and packing density of the particles, as well as miniaturization of the particle size An object of the present invention is to provide a carbon-based refractory material containing fine grained graphite which is excellent and can exhibit low elastic modulus.

The present invention for achieving the above object in the carbon-containing refractory composition, consisting of 85 to 95% by weight of oxide aggregate and 5 to 15% by weight of fine grained graphite having an average particle diameter of 20㎛ or less, the filling of the fine grained graphite The density is characterized in that 0.5g / cm ³ or more.

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Preferably, the fine grained graphite is spherical, and the ratio of the diameter to the height may be 3 or less.

Hereinafter, the present invention will be described in detail.

The present invention provides a carbon-containing refractory material composition comprising 80 to 85% by weight of an oxide aggregate and 15 to 20% by weight of graphite, wherein the graphite having an average particle diameter of about 100 μm is obtained by (1) particle size of 20 μm or less, (2) The filling density of 0.5 g / cm 3 or more and (3) shape are replaced by the finely grained graphite of 15 weight% or less, which is spherical (diameter / height <3/1 or less). It provides a carbon-based refractory material composition containing.

Here, the reason why the grain size of the fine grained graphite is limited as described above is that the grained graphite currently used for the carbon-containing refractory is particles having an average particle diameter of about 100 μm, in order to reduce the amount of the carbon-containing refractory used, This is because graphite having a fine particle diameter must be used.

In the present invention, the particle size of the finely grained graphite is preferably 20 µm or less, more preferably 1-15 µm. When the particle size is 20 μm or more, the effect expression by the addition of fine particles is insufficient, and the graphite of 1 μm or less is not easily obtained through grinding.

In addition, although the graphite having a packing density of 0.6 g / cm 3 is used for the impression graphite currently used for the carbon-containing refractory, the packing density of the natural graphite is closely related to the porosity of the produced refractory.

In the case of the finely grained graphite according to the present invention, a packing density of at least 0.5 g / cm 3 or more is required, and when it is less than or less, the porosity of the refractory material is greatly increased, and thus the strength and oxidation resistance are greatly deteriorated.

In addition, although the impression graphite currently used for carbon-containing refractory shows a typical plate-like appearance, in order to satisfy the particle size and packing density as described above, the shape of the particles is preferably spherical, in which the ratio of the diameter to the height 3 or less is preferable.

Hereinafter, the present invention will be described in more detail with reference to Examples.

EXAMPLE

MgO powder is used as the oxide aggregate, and predetermined binders and antioxidants are used so that the content of finely divided graphite having an average particle diameter of 5 µm and a packing density of 0.31 g / cm 3 as shown in FIG. 1 is 5, 10, or 15 wt%. Together to prepare a refractory composition (Invention Examples 1 to 3).

In addition, a predetermined binder is used so that an MgO powder is used as the oxide aggregate, and the content of the finely divided graphite having an average particle diameter of 15 µm and a packing density of 0.97 g / cm 3 as shown in FIG. 2 is 5, 10, or 15 wt%. A refractory composition was prepared with an antioxidant (Invention Example 4 to Inventive Example 6).

For comparison, MgO powder is used as the oxide aggregate, and is currently used for carbon-containing refractory, and the content of natural graphite having an average particle diameter of 100 μm and a packing density of 0.65 g / cm 3 as shown in FIG. A refractory composition was prepared together with a predetermined binder and an antioxidant so as to be (Comparative Examples 1 to 3).

Average particle diameter 100 μm 5 μm 15 μm Comparative Example 1 Comparative Example 2 Comparative Example 3 Inventive Example 1 Inventive Example 2 Inventive Example 3 Inventive Example 4 Inventive Example 5 Inventive Example 6 MgO (% by weight) 95 90 85 95 90 85 95 90 85 Graphite (wt%) 5 10 15 5 10 15 5 10 15 Binder ○ ○ ○ ○ ○ ○ ○ ○ ○ Antioxidant ○ ○ ○ ○ ○ ○ ○ ○ ○ Porosity (%) 3.4 1.5 1.4 2.5 1.9 1.7 1.2 1.2 1.3 Compressive strength (kg / ㎠) 690 572 519 800 678 481 900 890 800 Bending strength (kg / ㎠) 272 223 196 308 190 120 310 313 223 Erosion Index (Slag) 100 73 87 101 56 63 90 60 62 Weight loss rate (%) 1.8 5.6 8.8 2.3 5.7 8.8 2.2 5.8 9.5 Modulus of elasticity (GPa) 32 25 20 21 14 13 23 18 16

As shown in Table 1, in the case of using fine grained graphite having a packing density of 0.31 g / cm 3 and an average particle diameter of 5 µm (Invention Examples 1 to 3), the graphite having an average particle diameter of 100 µm having the same content was the same. Compared with (Comparative Examples 1 to 3), due to the low packing density, the porosity showed a high porosity compared to the same content.

Inventive Examples 1 to 3 showed a tendency superior to the comparative example in strength, erosion resistance, elastic modulus, and even in the case of oxidation resistance, it was possible to express the same level of characteristics as the existing refractory.

Further, when using spherical impression graphite having a packing density of 0.97 g / cm 3 and having an average particle diameter of 15 µm (Invention Examples 4 to 6), when using graphite having an average particle diameter of 100 µm having the same content ( Compared with Comparative Examples 1 to 3, it can be seen that low porosity, high strength, high corrosion resistance, low elasticity can be implemented.

Moreover, when only the elastic modulus was considered, even when only 5% of fine grained graphite was added as in Inventive Example 4, the effect of adding more than 10% of the graphite as in Comparative Example 2 and Comparative Example 3 was expressed.

In addition, in the case of oxidation resistance, Inventive Examples 1 to 6 were able to implement the oxidation resistance equivalent to the comparative example, without increasing the amount of oxidation due to miniaturization of the particle size.

As described above, the carbon-based refractory material composition containing particulate impression smoking according to the present invention is produced by replacing the impression graphite of the existing refractory material composition with graphite having a constant packing density and average particle size, showing a low elastic modulus The polling property is improved and there is an effect capable of high intensity expression.

Claims (3)

In the carbon-containing refractory composition, 85 to 95 wt% of oxide aggregate and 5 to 15 wt% of fine grained graphite having an average particle diameter of 20 μm or less, and the packed density of the fine grained graphite is 0.5 g / cm ³ or more. Carbon-based refractory material composition. delete The method of claim 1, Said fine grained graphite is spherical, and carbon-type refractory material composition containing fine grained graphite characterized by the ratio of diameter to height being three or less.

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