JPH06287052A - Carbon-containing refractory - Google Patents

Abstract

PURPOSE:To inexpensively improve thermal shock resistance by blending a mixture of a refractory raw material and graphite with a given amount of spherical carbon powder. CONSTITUTION:A main component comprising a refractory raw material such as fused magnesia having >=90wt.% purity and graphite is blended with metal powder to produce a carbide, nitride, etc., by reaction, a carbide to form an oxide by reaction and glass powder such as borosilicate glass to give a mixture. Then 100 pts.wt. of the mixture is mixed with 1-30wt.% spherical carbon powder such as coke having >=90wt.% purity to give a blend. Then the blend is kneaded, molded, dried and hardened to produce carbon-containing refractory.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon-containing refractory used in the steel industry.

[0002]

2. Description of the Related Art As a refractory material lined with molten metal, a carbon-containing refractory material having excellent slag resistance and thermal shock resistance is applied, and has achieved a considerably high performance.

However, these refractories have a weak point in oxidation resistance at high temperatures, and various metals are added or metal and carbide are added in combination in order to improve the weakness (for example, Japanese Patent Application Laid-Open No. 2000-242242). JP-A-54-163913 and JP-A-01-320262).

[0004]

However, although the corrosion resistance and the oxidation resistance are improved by the densification of the structure due to the reaction of the added metal inside the refractory, the carbon-containing refractory is a very excellent feature. It has a problem that the thermal shock resistance is relatively lowered.

An object of the present invention is to obtain a carbon-containing refractory having a thermal shock resistance equal to or higher than that of the carbon-containing refractory containing no metal or the like.

[0006]

The present invention is characterized by having the following composition in order to achieve a thermal shock resistance equal to or higher than that of a carbon-containing refractory without adding a metal.

(1) A carbon-containing refractory characterized in that spherical carbon powder is added in an amount of 1 to 30% by weight to a mixture 100 containing a refractory raw material and graphite as main components.

(2) A carbon-containing refractory material containing 1 to 30% by weight of spherical carbon powder with respect to a compound 100 containing a refractory raw material and graphite as main components and metal powders added thereto.

(3) A carbon-containing refractory material characterized in that 1 to 30% by weight of spherical carbon powder is added to a mixture 100 containing a refractory raw material and graphite as main components and metal powder and carbide added.

(4) Carbon-containing, characterized in that spherical carbon powder is added in an amount of 1 to 30% by weight with respect to a compound 100 containing a refractory raw material and graphite as main components, to which metal powder, carbide and glass powder are added. Refractory.

[0011]

The carbon source of the carbon-containing refractory material is natural, artificial graphite, mesophase carbon, coke, carbon black or the like, and preferably has a purity of 90% or more in order to prevent deterioration of corrosion resistance due to impurities.

As the refractory raw material for the carbon-containing refractory, electromelted products, sintered products, natural products such as alumina, magnesia, calcia, zirconia, and spinel can be used. In order to prevent deterioration of corrosion resistance due to impurities, 90 The purity is preferably at least%.

As the metal powder, it is possible to use one which forms a carbide, a nitride or an oxide by a reaction inside the refractory during use, and can improve strength, oxidation resistance and corrosion resistance.

As the carbide, it is possible to use one that forms an oxide by the reaction inside the refractory during use, and the oxidation resistance can be improved.

Borosilicate glass can be used as the glass, and the oxidation resistance can be improved.

The amount of the spherical carbon powder added is 1 to 30% by weight in order to improve the thermal shock resistance. If it is less than 1% by weight, the thermal shock resistance improving effect cannot be obtained, and if it exceeds 30% by weight, the structure is This is because it causes deterioration.

The spherical carbon powder refers to spherical particles made of graphite, mesophase carbon, coke, carbon black or the like, and preferably has a purity of 90% or more in order to prevent deterioration of corrosion resistance due to impurities.

The spherical carbon powder in the present invention does not necessarily have to be spherical, and is a powder having a curved surface, and preferably has a particle size of 500 microns or less.

The spherical carbon powder in the present invention improves the thermal shock resistance by the following mechanism.

The cracks generated by the thermal shock develop in the grain boundaries of the carbon and the refractory raw material particles forming the refractory structure.

When the spherical carbon powder exists at the destination of the crack, the crack stops at the surface of the spherical particle, or the crack has to bypass the spherical carbon particle and propagate.
The length of crack propagation until failure increases.

Further, the thermal expansion behavior of the added spherical carbon particles is different from that of the compounded carbon and isotropic, so that microcracks are generated inside the refractory structure.

By the generated microcracks, the progress of cracks generated by thermal shock is dispersed, and the propagation energy of the cracks is absorbed, whereby the progress of cracks is suppressed.

The thermal shock resistance can be improved by the above two effects.

[0025]

EXAMPLES The present invention will be described below based on examples.

Examples of producing and using the carbon-containing refractory material of the present invention are shown below.

3 to 5% by weight of a liquid phenolic binder is added to 100% by weight of the raw material composition shown in Table 1, kneading, vacuum friction molding and drying (90 ° C. × 24.
Time) and a curing treatment (250 ° C. × 10 hours) to produce a carbon-containing refractory material.

[0028]

[Table 1]

[0029]

[Table 2]

The carbon-containing refractory material produced was evaluated by immersing a sample of a certain shape in hot metal at 1600 ° C. for 90 seconds, water-cooling 15 seconds, and air-cooling 60 seconds five times. evaluated. When the rate of decrease in elastic modulus was 20% or less, it was evaluated as ◯, and when it was more than that, it was evaluated as x.

Table 2 shows a comparative example.

[0032]

[Table 3]

[0033]

[Table 4]

3 to 5% by weight of a liquid phenolic binder is added to 100% by weight of the raw material composition shown in Table 2, kneading, vacuum friction molding and drying (90 ° C. × 24.
Time) and a curing treatment (250 ° C. × 10 hours) to produce a carbon-containing refractory material.

The carbon-containing refractory material produced was evaluated by immersing a sample of a certain shape in hot metal at 1600 ° C. for 90 seconds, water-cooling 15 seconds, and air-cooling 60 seconds five times. evaluated. When the rate of decrease in elastic modulus was 20% or less, it was evaluated as ◯, and when it was more than that, it was evaluated as x.

As is clear from Table 1, the carbon-containing refractory material of the present invention has excellent thermal shock resistance. On the contrary,
The carbon-containing refractory material of the comparative example is inferior in thermal shock resistance.

[0037]

According to the present invention, the following effects can be obtained.

By adding the spherical carbon powder, it was possible to achieve thermal shock resistance equal to or higher than that of the carbon-containing refractory containing no metal.

As a result, it is possible to reduce the unit cost and unit cost by extending the life of the carbon-containing refractory for the steel industry, and reduce the working cost due to the reduction in the number of repairs.

Claims (4)

[Claims] 1. A blend 1 comprising a refractory raw material and graphite as main components.
1 to 30% by weight of spherical carbon powder with respect to No. 00, a carbon-containing refractory material. 2. A spherical carbon powder in an amount of 1 to 100 with respect to a mixture 100 containing a refractory raw material and graphite as main components and metal powder added.
A carbon-containing refractory characterized by being added in an amount of 30% by weight. 3. A carbon-containing refractory material containing 1 to 30% by weight of a spherical carbon powder with respect to a compound 100 containing a refractory raw material and graphite as main components and containing a metal powder and a carbide. 4. A carbon-containing fire resistant material, characterized in that 1 to 30% by weight of spherical carbon powder is added to a mixture 100 containing a refractory raw material and graphite as main components, and containing metal powder, carbide and glass powder. object.