JPH02129078A - Carbon-containing refractory - Google Patents

Abstract

PURPOSE:To obtain a carbon-containing refractory exhibiting excellent thermal shock resistance and high mechanical strength even after the carbonization of an organic binder by dispersing a phenolic resin fiber as an organic binder. CONSTITUTION:A refractory aggregate composed mainly of carbon and containing MgO, Al2O3, SiC, etc., as other main components is prepared beforehand. The weight ratio of the refractory aggregate to the carbon is preferably about (50-100):(50-0). The objective carbon-containing refractory can be produced by dispersing phenolic resin fibers in the above refractory aggregate. Various commercially available phenolic resin fibers can be used in the above process, however, fibers having an outer diameter of 2-100mum and a length of about 0.1-50mm are preferable. Since the obtained carbon-containing refractory has the above-mentioned characteristics, it is especially suitable as a lining material for charging wall of converter, hot spot of electric furnace, etc., or as a casting nozzle.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to carbon-containing refractories, particularly for use in blast furnaces, tap runners, mixer cars, ladles, converters, electric furnaces, and secondary refining in ironmaking and steelmaking. The present invention relates to carbon-containing refractories used for refractory furnace materials such as furnaces and tundishes, or nozzles.

[Prior art]

Carbon-containing refractories have been conventionally used as refractories for steelmaking furnaces because they have excellent corrosion resistance and thermal shock resistance. However, if it is used in areas that are subject to mechanical shock and wear due to the charging of scrap and hot metal, such as the charging wall of a converter, or in areas that are subject to severe thermal shock, such as continuous casting nozzles, it will cause significant damage. This is one of the causes of shortening the lifespan of refractories.

[Problem to be solved by the invention]

In order to improve the drawbacks of carbon-containing refractories, attempts have been made to add carbon fiber (Japanese Patent Publication No. 62-9553,
JP-A-58-88167, JP-A-59-207871.
JP-A-60-65771, etc.). However, although carbon fiber itself has high strength, the bonds are broken due to large shrinkage during carbonization of the organic binder (phenol resin, pitch, etc.) commonly used for carbon-containing refractories, and the carbon The fibers no longer participate in the bonding of the carbon-containing refractories, and it cannot be said that the above-mentioned conventional drawbacks have been sufficiently solved.

This invention was proposed in view of the above-mentioned conventional circumstances, and aims to provide a carbon-containing refractory that has excellent thermal shock resistance and mechanical strength even after carbonization of an organic binder. purpose.

[Means to solve the problem]

In order to achieve the above object, the present invention adds phenol resin fibers of the same quality as the phenol resin used as a binder, so that the fibers and the binder phase are firmly bonded even after carbonization.

[Effect]

With the above configuration, carbon is used as the main component of the fireproof aggregate, but other main components include magnesia,
Use refractory aggregates such as alumina, spinel, and silicon carbide. The blending ratio of fireproof aggregate and carbon is 50 to 10 by weight.
Approximately 0:50 to 0 is preferable. Natural or artificial carbon raw materials can be used, and scaly graphite, globular graphite, electrode scrap, quiche graphite, pitch coke, and carbon blank can be used. Further, since carbon is generated by carbonization of the binder, there are cases where it is not necessary to use a carbon material. In addition to the above carbon and refractory aggregate, metals such as aluminum, silicon, magnesium, and their alloys, or B4 C, BN, S
Carbides, nitrides, etc. such as is N4 can be blended for the purpose of improving oxidation resistance.

Various commercially available phenol resin fibers can be used as the phenol resin fibers to be blended in the present invention, but preferably have an outer diameter of 2 to 100 μm and a length of 0.1 to 50 mm. If the outer diameter is less than 2 μm, the strength of the fiber after carbonization will not be sufficient, and if it exceeds 100 μm, the fiber will have poor flexibility, making it impossible to obtain a good molded product. If the length is less than 0.1 mm, the reinforcing effect of the fiber is insufficient and it is difficult to achieve the effect of improving thermal shock resistance and mechanical strength. If the length exceeds 50 mm, the dispersibility in the refractory will be poor. It makes things worse and is not desirable.

In addition, the aspect ratio (fiber length/fiber diameter) is 20 to 500.
It is desirable that the The blending amount of phenol resin fibers can be set in various ways depending on the need, but it is 0.1 to 30% by weight based on the total amount of carbon and refractory aggregate of 100% by weight.
Weight percent is preferred. If it is less than 0.1% by weight, the reinforcing effect of the fibers will be insufficient, and if it exceeds 30% by weight, uniform dispersion will be difficult.

A refractory molding material is prepared by adding an organic binder to the above mixture. The organic binder preferably has a high residual carbon content, and phenol resin, furan resin, pitch, etc. can be used, but in the present invention, it is preferable to use phenol resin because of its bondability with phenol resin fibers.

〔Example〕

Examples of the present invention will be described below.

Sintered magnesia with MgO purity of 98% and carbon purity of 9
Using 8% scaly graphite, etc., it was mixed in the ratio shown in Table 1, kneaded in a roll pan using phenol resin as a binder, and then molded into the shape of a regular brick (JIS R2101) using a 500-ton hydraulic press. , 2 at 200℃
It was dried and hardened for 4 hours to obtain an unfired refractory. The results of the quality tests for each Example and each Comparative Example are also listed in Table 1.

In Examples ■ to ■, the hot bending strength, thermal shock resistance, and bending strength after binder carbonization (after reduction firing at 1500'C x 3 hours) were significantly improved compared to Comparative Examples ■, ■, ■, and ■ due to the use of phenol resin fibers. It was confirmed that there was an improvement. Furthermore, it was confirmed that, compared to Comparative Example (3) using carbon fibers, Example 2 using phenol resin fibers had significantly improved hot bending strength, thermal shock resistance, and bending strength after binder carbonization.

The brick of Example 1 in Table 1 was used on the charging side wall of a 901-n converter, and a practical test was conducted to compare it with the conventional product of Comparative Example 2. As a result, the wear rate of the conventional product was 1.8 mm/ In contrast, the bricks of Example 1 had a rate of only 1°5 mm/ch, confirming that their durability was improved.

(The following is a blank space) [Effects of the Invention] As explained above, the carbon-containing refractory of the present invention has significantly improved mechanical strength and resistance to thermal shock, and is suitable for lining of converter charging walls, electric furnace hot spots, etc. It is particularly suitable as a material or a nozzle for casting.

Claims (1)

[Scope of Claims] [1] A carbon-containing refractory characterized by dispersing and mixing phenol resin fibers. [2] The carbon-containing refractory according to claim 1, wherein the phenol resin fiber has an outer diameter of 2 to 100 μm and a length of 0.1 to 50 mm. [3] The carbon-containing refractory according to claim 1 or 2, wherein the amount of the phenol resin fiber used is 0.1 to 30% by weight based on the total weight of the refractory raw material.