JPH05319907A - Carbon-containing basic refractory - Google Patents

Abstract

PURPOSE:To improve durability of a carbon-containing basic refractory by improving spalling resistance, strength and oxidation resistance thereof. CONSTITUTION:To a refractory containing 5 to 30wt.% carbon material and 70 to 95wt.% magnesia as the raw material of the refractory, powdery titanum silicide is added in an amount of 0.1 to 10wt.% on outer percentage base. Titania and silica are formed by a high affinity of titanum silicide to oxygen at a high temperature so as to reinforce a carbon-containing basic refractory from the outside and the inside.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a carbon-containing basic refractory in the refractory field.

[0002]

2. Description of the Related Art Carbon-containing refractories have an excellent scope of application and are rapidly expanding in recent years because they have excellent sponging property and corrosion resistance against slag and molten metal. Among them, unfired refractories using tar pitch or phenolic resin as a binder meet the demand for energy saving. Therefore, carbon-containing refractories combined with various refractory raw materials have various properties. Used for molten metal containers and peripheral equipment.

Of these carbon-containing refractories, for example, a carbonaceous raw material such as scaly graphite is added to magnesia (Mg) such as a sintered magnesia clinker or an electromelting magnesia clinker.
MgO-C refractory compounded with O.sub.3) is widely used for furnace walls such as converters and electric furnaces, and the life of the furnace is dramatically extended.

However, such MgO-C refractory has a low hot strength because the bond in the structure essentially depends on the carbon bond which has no bond with the oxide. It is also well known that it has a drawback that it is rapidly oxidized in a strong oxidizing atmosphere to significantly increase the dissolution rate.

[0005]

In order to improve the oxidation resistance and hot strength characteristics, which are the drawbacks of this MgO-C type refractory, an easily oxidizable metal such as Al, Si or Mg is added,
By adding a carbide such as B ₄ C or SiC, or adding silicon hexaboride SiB ₆ , a B ₂ O ₃ -SiO ₂ glass phase as well as B ₂ O ₃ and a fireproof bone during the operation of the refractory There has been proposed a method of coating a carbonaceous raw material with a coating made of a high-viscosity melt that is generated by a reaction with a material at a high temperature during operation.

However, the effect of preventing the oxidation of the carbonaceous raw material by the method of adding the above-mentioned oxidizable metal or carbide is
Although there is some improvement, it is not completely satisfactory. Further, in the method of adding silicon hexaboride, it takes time to form a stable coating film of the high-viscosity melt, and depending on operating conditions, the surface of the refractory material may be damaged by melting or abrasion. Many.

[0007]

The present invention has been made in view of the above points, and in order to solve the above problems, a carbonaceous raw material of 5 to 30% by weight and a magnesia refractory raw material of 70 to 9 are used.
It is another object of the present invention to provide a carbon-containing basic refractory, which is obtained by adding 0.1 to 10% by weight of titanium silicide powder to a refractory material containing 5% by weight.

[0008]

According to the present invention, the carbonaceous raw material is 5 to 30% by weight,
By adding 0.1-10% by weight of titanium silicide powder to the refractory material containing 70-95% by weight of magnesia refractory raw material, titanium oxide shows a greater oxygen affinity to carbon at high temperature, and titania , Silica can be generated to reinforce the inner and outer surfaces of the refractory, and the sparkling resistance, strength, and oxidation resistance can be improved.

[0009]

EXAMPLE A carbon-containing basic refractory material of the present invention is obtained by applying titanium silicide powder to a refractory material containing 5 to 30% by weight of a carbonaceous raw material and 70 to 95% by weight of a magnesia refractory material. The feature is that 0.1 to 10% by weight is added.

Examples of the above carbonaceous raw materials include scaly graphite, earthy graphite, petroleum coke, coal pitch, coke,
Known materials such as foundry coke and carbon black can be used. Of these, scaly graphite is the most preferable. The particle size of the carbonaceous raw material is not particularly limited and can be appropriately selected, but it is usually preferable to use a particle size of about 1 mm or less.

Sintered magnesia clinker, electrofused magnesia, natural magnesia clinker and the like can be used as the magnesia refractory raw material, and the blending amount is 70 to 90% by weight.

The blending amount of the carbonaceous raw material varies depending on the object to which the refractory is applied, but is 5 to 3 with respect to the total amount of the refractory material.
0% by weight is preferred. For example, when scaly graphite is added as a carbonaceous raw material and the scaly graphite is less than 5% by weight,
The advantages of carbon-containing refractory, such as deterioration in sponging resistance, cannot be fully exerted. Further, if the blending amount exceeds 30% by weight, the corrosion resistance decreases, which is not preferable.

Titanium silicide (T) added to the above refractory materials
The powder of iSi ₂ ) exhibits an oxygen affinity higher than that of carbon at high temperature, and is oxidized near the refractory surface to form Ti
O ₂ (titania) and SiO ₂ (silica),
The spoiling resistance, strength, and oxidation resistance can be improved.

That is, the expansion of the volume associated with the formation of TiO ₂ and SiO ₂ almost completely closes the particle gaps formed in the surface of the refractory near the surface to increase the mechanical strength of the refractory. At the same time, the oxidation resistance can be improved. Further, SiO ₂ and TiO ₂ react with MgO, and SiO ₂ produces 2MgO.TiO ₂ (forsterite), while TiO ₂ forms 2MgO.TiO ₂ and contributes to the improvement of strength.

Further, the TiSi ₂ reacts with CO inside the refractory material, and TiSi ₂ + 6CO → Ti
Like O ₂ + 2SiO ₂ + 6C, it forms TiO ₂ , SiO ₂ and carbon, and supplements carbon that has disappeared due to oxidation. In addition, a part of it reacts with carbon, and TiSi ₂ + 3C → TiC
Titanium carbide and silicon carbide are formed like + 2SiC to strengthen the structure.

The particle size of the TiSi ₂ powder is preferably 250 μm or less, more preferably 44 μm or less in view of reactivity, uniformity, dispersibility, reaction activity and the like.

The TiSi ₂ powder is added in an amount of 0.1 to 10% by weight based on the refractory material containing the carbonaceous raw material. If the addition amount is less than 0.1% by weight, the desired effect cannot be obtained, while if it exceeds 10% by weight, there is no problem in terms of oxidation resistance, but corrosion resistance decreases, which is not preferable.

The carbon-containing refractory material contains a binder such as tar pitch or phenol resin, which has a large amount of residual carbon, that is, has a high carbon yield and is excellent in workability during molding. However, the use of phenolic resin is preferable in terms of workability and cost.

[0019]

[Test Example] Next, the features of the present invention will be further clarified by comparing Examples of the present invention with Comparative Examples.

The samples shown in Examples 1 to 5 and Comparative Examples 1 to 6 in Table 1 on the next page are 60% by weight of sintered magnesia,
A refractory material containing 20% by weight of electro-melted magnesia, 20% by weight of scaly graphite, 3% by weight of phenol resin outer shell and 2% by weight of outer shell of pitch, as shown in the upper column of Table 1, TiSi ₂ powder, metallic aluminum, Predetermined amounts of metallic silicon and boron carbide were added. Then, after kneading at room temperature for about 50 minutes, 10
It is obtained by press-molding into a shape of 40 × 40 × 160 mm at a pressure of 00 Kgf / cm ² and heat-treating at 180 ° C. for 18 hours. The lower column of Table 1 shows the characteristics of each of the above test pieces.

Comparison table

[Table 1]

In Table 1, the numerical values such as the weight loss rate after the oxidation firing at 1500 ° C. for 2 hours and the thickness of the decarburized layer are relatively high in Examples 1 to 6 of the present invention, and the oxidation resistance is high. It shows that the property has improved.

Next, the obtained refractory material was treated with a basicity, that is, a slag having a CaO / SiO ₂ weight ratio of 2.0 to obtain 16
It was subjected to a rotary slag test at 50 ° C. for 2 hours, the erosion amount of each sample was measured with the erosion amount of Comparative Example 1 being 100, and the erosion index shown in the bottom column of Table 1 was calculated. As a result, all of the examples of the present invention show a low melt loss index, and the examples of the present invention have extremely excellent corrosion resistance against slag as compared with the comparative examples.

The present invention is not limited to the above-mentioned embodiments, and various modifications such as addition of an alloy of titanium silicide and addition of other additives are possible without departing from the spirit of the present invention. It is possible.

[0025]

As described above, according to the present invention, in addition to the excellent sponging resistance which is the characteristic of the conventional products, it has good strength and excellent oxidation resistance, so that it is durable. A carbon-containing basic refractory having improved properties can be obtained, which can contribute to further extension of the furnace life.

Claims (1)

[Claims] 1. Titanium silicide powder is added 0.1 to 10% by weight to a refractory material containing 5 to 30% by weight of carbonaceous raw material and 70 to 95% by weight of magnesia refractory raw material. Characteristic basic refractory material containing carbon.