JPH07172907A - Carbon-containing refractory - Google Patents

Abstract

PURPOSE:To obtain a carbon-contg. refractory retaining its spalling resistance and hot strength and improved in resistance to oxidation and corrosion. CONSTITUTION:A refractory material comprising a carbonaceous material and alumina refractory material is incorporated with 0.1-8 outer wt.% of titanium carbide powder. Incorporation of the titanium carbide preferentially oxidizes it at elevated temperatures to suppress carbon burn-off, also causing reaction of the produced TiO2 with Al2O3 to produce high-toughness Al2O3.TiO2- based compounds to effect densification of the texture, thus obtaining them objective carbon-contg. refractory improved in resistance to oxidation and corrosion.

Description

Detailed Description of the Invention

[0001]

This invention relates to carbon containing refractories.

[0002]

2. Description of the Related Art Conventionally, refractory materials containing carbonaceous raw materials such as graphite have high thermal conductivity and low thermal expansion coefficient as compared with refractory materials such as alumina and shale shale.
It has excellent ringability and is hard to get wet with molten metal, slag, etc.,
It also has excellent corrosion resistance.

Further, since these refractory materials also have a function of preventing oversintering of the refractory material, their field of use has been rapidly expanding in recent years. Alumina-carbon refractories using sintered alumina, fused alumina, calcined shale and scaly graphite are often used in electric furnaces, mixed pig cars, etc., and contribute to the extension of the life of these furnaces. There is.

[0004]

However, such a carbon-containing refractory has a drawback that it has a low hot strength because the bond between the brick structures is mainly due to the carbon bond and the oxidation resistance at a high temperature is poor. .

Therefore, a method is known in which a metal such as Al, Si, or Mg which is easily oxidized is added alone or an alloy thereof to the refractory material, or a method in which a carbide such as B ₄ C or SiC is added. In addition, the addition of silicon hexaboride (SiB ₆ ) or a nitrate causes the formation of a glass phase and B ₂
A method of coating a carbonaceous raw material with a highly viscous melt produced by reacting O ₃ with a refractory aggregate at a high temperature during operation has been proposed.

[0006] However, the effect of preventing the oxidation of the carbonaceous raw material by the method of adding the easily oxidizable metal or carbide is not sufficiently satisfactory. Further, in the method of adding hexaboride or the like, the surface of the refractory material may be damaged by melting loss or abrasion before forming a stable coating film, resulting in unstable quality.

[0007]

The present invention has been made in view of the above points, and in order to solve the above-mentioned problems, a refractory material containing a carbonaceous raw material and an alumina refractory raw material contains titanium carbide. It is another object of the present invention to provide a carbon-containing refractory material, which is characterized in that 0.1 to 8% by weight of powder is added to the exterior.

[0008]

According to the present invention, the refractory material containing the carbonaceous raw material and the alumina refractory raw material is coated with titanium carbide powder in an external amount of 0.
By adding 1 to 8% by weight, while maintaining the sparking resistance and hot strength, titanium carbide is preferentially oxidized at high temperature to suppress carbon burnout, and the generated TiO ₂ is Al. It reacts with ₂ O ₃ to form a highly viscous Al ₂ O ₃ .TiO ₂ type compound, and densifies the structure to improve oxidation resistance and corrosion resistance.

The present invention will be described below. The carbon-containing refractory material of the present invention is a carbonaceous raw material, a refractory material containing an alumina-based refractory raw material, titanium carbide powder 0.1
It is characterized by adding 8% by weight.

As the carbonaceous raw material having the above-mentioned constitution, scaly graphite is preferable, but known materials such as earthy graphite, petroleum coke, coal pitch coke, foundry coke, carbon slag and the like should also be used. You can The particle size of the carbonaceous raw material is not particularly limited and may be appropriately selected, but it is usually preferably about 1 mm or less.

Sintered alumina, fused alumina, calcined alumina, calcined bauxite, calcined alum shale, etc. can be used as the alumina refractory raw material.

The blending amount of the carbonaceous raw material varies depending on the purpose of use of the refractory material, but is preferably 5 to 90% by weight based on the total amount of the refractory material. For example, if the scaly graphite is less than 5% by weight, the advantages of the carbon-containing refractory cannot be fully exhibited, such as the deterioration of sponging resistance, and if it exceeds 90% by weight, the hot strength is reduced, which is not preferable. .

The blending amount of the alumina refractory raw material also varies depending on the purpose of use of the refractory, but is preferably 10 to 95% by weight based on the total amount of the refractory material. Outside of these ranges, the spooling resistance and hot strength are reduced, which is not preferable.

The titanium carbide powder added to the refractory material as described above exhibits an excellent oxygen affinity at high temperatures and is oxidized near the refractory surface to precipitate TiO ₂ and C. Then, due to the expansion of the volume accompanying the formation of TiO ₂ and C, the gaps between the particles near the surface formed during the molding of the oxide are almost completely densified and the mechanical strength is increased, and the oxidation resistance is further improved. Improve.

The particle size of the titanium carbide powder is preferably 250 μm or less, more preferably 44 μm or less from the viewpoints of reactivity, uniformity, dispersibility, reaction activity and the like. Further, the addition amount of the titanium carbide powder is preferably 0.1 to 8% by weight in terms of external weight with respect to the refractory material. If the amount of titanium carbide powder added is less than 0.1% by weight, the desired effect cannot be obtained, and if it exceeds 8% by weight, there is no problem in terms of oxidation resistance, but corrosion resistance decreases, which is not preferable.

The carbon-containing refractory contains a binder such as tar pitch or phenol resin, which has a large amount of residual carbon, that is, a high carbon yield and is excellent in workability during molding, either alone or in combination. be able to.

[0017]

EXAMPLES Table 1 shows a comparative table for the products of the present invention and the conventional products in which 3.5% by weight of an outer shell type phenol resin was added. In the lower column of Table 1, each compound was kneaded at room temperature for 50 minutes, and then pressure-molded at a pressure of 1000 Kgf / cm ² into a shape of 40 × 40 × 160 mm.
The quality characteristics of unfired refractories obtained by heat treatment at 15 ° C. for 15 hours are displayed.

Comparison table

[Table 1]

As can be seen from Table 1, the values of the weight raw material ratio and the decarburized layer thickness, etc. after oxidation and calcination at 1500 ° C. for 2 hours are smaller in the product of the present invention, and the oxidation resistance is higher than that of the conventional product. Is shown to be excellent.

Further, the obtained refractory material was treated with a slag having a basicity, that is, a CaO / SiO ₂ weight ratio of 2 to 16
It was subjected to a rotary slag test at 50 ° C. for 2 hours, and the erosion amount of each product was measured by setting the erosion amount of the conventional product 1 to 100, and the erosion index was calculated. As shown in the bottom column of the table The products of the present invention all show a low melt loss index, and it is understood that the products of the present invention have extremely excellent corrosion resistance against slag as compared with the conventional products.

It is needless to say that the present invention is not limited to the above-mentioned embodiments, and various applications can be made without departing from the spirit of the present invention.

[0022]

As described above, according to the present invention, carbon is burned down by preferential oxidation of titanium carbide at high temperature while maintaining the conventional features of anti-spooling property and hot strength. And the generated TiO ₂ is
Al ₂ O ₃ · TiO ₂ which has a large viscosity by reacting with l ₂ O _3.
It is possible to improve the oxidation resistance and the corrosion resistance to slag and molten metal by forming a system compound and densifying the structure, and prolonging the life of a furnace or the like using refractory.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Yamaguchi 2 at 1576, Higashioki, Nakahiro, Ako City, Hyogo Prefecture Kawasaki Furnace Co., Ltd.

Claims (1)

[Claims] 1. A carbon-containing refractory material, which comprises 0.1 to 8% by weight of titanium carbide powder added to a refractory material containing a carbonaceous raw material and an alumina-based refractory raw material.