JPH0777979B2 - Carbon-containing refractory - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a carbon-containing refractory having excellent oxidation resistance.

[0002]

2. Description of the Related Art Conventionally, carbon-containing refractories such as magnesia-carbonaceous material, alumina-carbonaceous material, alumina-silicon carbide-carbonaceous material have been widely used as lining materials for hot metal and molten steel. Carbon has a property that it is hard to get wet with slag and has excellent thermal shock resistance. By combining this with a refractory material having a high melting point such as magnesia or alumina, a refractory material having high durability can be obtained.

[0003]

However, the carbon-containing refractory has a drawback that carbon disappears by oxidation. When the decarburized layer is formed by the oxidation of carbon, the strength of the refractory structure is deteriorated or the slag is infiltrated, and the durability is significantly reduced. As a means for preventing the oxidation of carbon, Al, Al-
Addition of metal powder such as Mg alloy (JP-B-60-2269, JP-A-57-166362), addition of B ₂ O ₃ (JP-A-57-5811), addition of glass powder (JP Methods such as Kaihei 1-141872) are known, but sufficient effects have not been obtained.

[0004]

The inventors of the present invention have conducted extensive research to improve the oxidation resistance of carbon-containing refractory materials. As a result, magnesium boride or magnesium boride and boron are used as antioxidants. The inventors have completed the present invention by knowing that good results can be obtained by adding a mixture. The present invention relates to a carbon-containing refractory material obtained by adding 0.1 to 10% of magnesium boride to 100% by weight of a compound containing 3 to 40% by weight of carbon and the balance being a refractory oxide material. Is. Further, it is a carbon-containing refractory material obtained by adding a mixture of magnesium boride and boron in a total amount of 0.1 to 10% in place of the above magnesium boride.

Boron or boron carbide, calcium boride,
It is already known to add borides such as zirconium boride as antioxidants of carbon-containing refractories. However, the magnesium boride used in the present invention exhibits markedly superior oxidation resistance as compared with these boron or boride. Further, magnesium boride does not lower the corrosion resistance unlike the conventionally used boron or boride. It also has an excellent effect on corrosion resistance. The reason is presumed to be due to the following action. That is, magnesium boride decomposes into a B component and a Mg component at high temperatures during use of the refractory. Of these, the B component becomes B ₂ O ₃ by oxidation. B
₂ O ₃ melts in the matrix, forms a glassy film in the pores of the refractory structure, and blocks the carbon component from the outside air, thereby suppressing the oxidation. On the other hand, the Mg component moves as vapor inside the refractory structure, is oxidized in the vicinity of the operating surface and in the pores to become MgO, forms a dense layer, and has no deterioration in corrosion resistance.

The present invention will be described in more detail below. The percentages shown in the proportions of the respective blends are all weight proportions. Specific types of carbon used in the present invention include phosphorous graphite, earthy graphite, artificial graphite, pitch coke, anthracite,
One or more selected from carbon black and pitch. If the ratio is less than 3%, the effect of carbon on corrosion resistance and spall resistance becomes insufficient. 40%
If it exceeds, the strength and wear resistance will decrease. The particle size is not particularly limited, but is preferably 0.5 mm or less.

As the refractory oxide material, one or more of magnesia, alumina, silica, calcia, zirconia, chrome, spinel, alumina-silica, dolomite, zircon and the like can be used. Use as main material. The particle size is adjusted to coarse particles, medium particles, and fine particles so that close packing can be obtained.

The specific chemical composition of magnesium boride is M
g ₂ B ₃ , MgB ₂ , and MgB ₄ are known. The same effect can be obtained by using any of them, but Mg ₂ B _{3 which} is easily available in terms of productivity is preferable. The particle size is not particularly limited, but fine powder is desirable in order to efficiently exhibit oxidation resistance and corrosion resistance, and for example, it is 0.5 mm or less. If the addition ratio is less than 0.1%, the above effect of magnesium boride cannot be obtained, and if it exceeds 10%, the amount of B ₂ O ₃ component produced becomes too large, and the corrosion resistance deteriorates. When a mixture of magnesium boride and boron is used, the proportion of magnesium boride in this mixture is preferably 3% or more. If it is less than 3%, the above-mentioned MgO dense layer is insufficiently formed, resulting in a decrease in corrosion resistance.

The present invention requires the use of the above-mentioned compounds and additives, but in addition to the above, the additions known in conventional carbon-containing refractories within a range not impairing the effects of the present invention. You may use a thing together. For example, Al,
Metal powder such as Si, Mg, Ca or alloy powder thereof, B ₄
C, SiC, Si ₃ N ₄ , B ₂ O ₃ and other carbides, nitrides or oxides, metal fibers, ceramic fibers,
Addition of fibers such as carbon fiber and glass.

The carbon-containing refractory material of the present invention is an unfired refractory material,
Manufactured as fired refractory or amorphous refractory. In the case of an unfired refractory, a binder such as a phenol resin or pitch is added, and after pressure molding, if necessary, heat treatment is performed in a temperature range where carbon is not oxidized, preferably 100 to 600 ° C. The fired product is pressure-molded and then reduction-fired at about 900 to 1500 ° C. For amorphous refractories, phenolic resin, organic binders such as pitch, sodium silicate, sodium phosphate,
A kneaded product to which an inorganic binder such as aluminum phosphate is added.

[0011]

EXAMPLES Examples of the present invention and comparative examples are shown below.
Tables 1 and 3 are examples and comparative examples of unfired refractories. The production was carried out by kneading the compounds shown in the table, molding them into a normal shape with a friction press, and further 230 ° C. × 48.
It was heat treated for a certain period of time. Table 2 shows examples and comparative examples of fired refractories, which were kneaded and molded in the same manner as the above-mentioned unfired refractories, and then embedded in a coke breeze,
It was reduced and baked at 00 ° C. for 10 hours.

The test results are shown in each table at the same time, and the test method is as follows. Oxidation resistance: A test piece cut into a size of 50 × 50 × 50 mm was heated in an electric furnace at 1400 ° C. for 6 hours and then cut, and the thickness of the decarburized layer generated by the oxidation was measured. Corrosion resistance: Melting loss dimension was measured by a rotary erosion method. In the rotary erosion, the magnesia-carbonaceous unburned refractory in Table 1 and the magnesia-carbonaceous fired refractory in Table 2 were eroded at 1700 ° C. for 4 hours using a converter slag as an erosion agent. In the alumina-carbonaceous unfired refractories shown in Table 3, blast furnace slag was used as an erosion agent and eroded at 1400 ° C. for 4 hours.

Actual machine test: Unfired refractories shown in Tables 1 and 3 were tested. The magnesia-carbonaceous unfired refractories shown in Table 1 were lined on the barrel of a 350 ton converter and the damage rate after using 3000 charges was measured. Alumina in Table 3
The carbonaceous non-fired refractory was lined on the slag line of a 600 ton mixed pig car, and the damage rate after using 1200 charges was measured. As the test results of each table show, the refractory materials obtained by the examples of the present invention are all excellent in oxidation resistance,
Moreover, no reduction in corrosion resistance is observed. As a result, good results were obtained in the actual machine test.

[0014]

[Table 1A]

[0015]

[Table 1B]

[0016]

[Table 2]

[0017]

[Table 3A]

[0018]

[Table 3B]

[0019]

INDUSTRIAL APPLICABILITY As described above, the carbon-containing refractory material of the present invention exhibits an excellent effect of oxidation resistance. The biggest drawback of the carbon-containing refractory is oxidative deterioration, and the present invention eliminates this drawback, so that the carbon-containing refractory originally has the corrosion resistance and spalling resistance effect. it can. Various kilns in the steel industry often use carbon-containing refractory materials as furnace materials due to severer operating conditions. For example, most of blast furnaces, blast furnace gutters, converters, ladles, mixed pig wheels, continuous casting equipment and the like use carbon-containing refractories. Under such circumstances, the value of the present invention for improving the performance of carbon-containing refractories is extremely high.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location C04B 35/10 G (72) Inventor Tsuneo Kitai 1-3-1 Niihama, Arai-cho, Takasago-shi, Hyogo Harima Ceramics Co., Ltd. (72) Inventor Masato Tanaka 1-3-1 Arai-cho Niihama, Takasago, Hyogo Prefecture Harima Ceramic Co., Ltd. (72) Inventor Akiyoshi Maekawa 1-3-1 Niihama, Arai-cho Takasago, Hyogo Prefecture Harima Ceramic Co., Ltd.

Claims (2)

[Claims] 1. A carbon content obtained by adding 0.1 to 10% of magnesium boride to 100% by weight of a compound containing 3 to 40% of carbon and the balance being a refractory oxide material as a main component. Refractory. 2. A mixture of magnesium boride and boron in a total amount of 0.1 to 100% by weight of a mixture containing 3 to 40% of carbon and the balance of a refractory oxide material as a main component. 1
Carbon-containing refractory made by adding 0%.