JPH08333183A - Production of alumina refractory - Google Patents

Abstract

PURPOSE: To improve high-temperature strength and spalling resistance by kneading alumina raw materials and forming them to a preform having an open cell structure and a specific glass content, then reactively impregnating the preform with aluminum. CONSTITUTION: An alumina raw material such as aluminous shale with a silica content of <=5%, if necessary, a pore-forming agent, and a variety of oxides, carbides and, nitrides as components to be mixed are kneaded and formed through an arbitrary process and then fired usually at 800-1,800 deg.C for 1-several hours to prepare a preform which has a glass content of <=3% and open cells of which 15%-70% have 70μm or more cell diameters. A formed aluminum which has an almost same shape as that of the preform with a thickness of about 20mm is placed on the preform and pressed with a pressure of about 100MPa, then subjected to reactive impregnation in an oxygen atmosphere at 1,150 deg.C for 4 hours to give the objective alumina refractory. This refractory is useful in the sites which require excellent texture, strength, spalling resistance and abrasion resistance, for example, slide plates or sleeves for iron discharge outlets of a blast furnace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an alumina refractory material, and in particular, by reacting and infiltrating aluminum into a refractory base material, the alumina refractory material has excellent sponging resistance and hot strength. The present invention relates to a refractory manufacturing method.

[0002]

2. Description of the Related Art As a method for producing a refractory having a high hot strength, a method intended to densify the refractory and improve the bonding strength has been conventionally performed. Specific methods include (1) using ultrafine powder raw materials, or using high-purity raw materials that do not contain substances that form a liquid phase at high temperatures (2) increasing molding pressure and firing temperature , A method of using a rubber press (CIP) for molding (3) a method of pressure burning using HIP (4) a method of adding a sintering accelerator (5) a metal in the pores of a ceramic preform or a filler. Method for filling while oxidizing (Japanese Patent Publication No. 3-75508)
(See JP-A-63-30376 and JP-A-63-170256) (6) A method of reacting and permeating aluminum into ceramic containing mullite while oxidizing it (JP-A-6-135766) is known. There is.

Among the above-mentioned conventional methods, the methods (1) to (4) are different from the present invention, but the methods (5) and (6) correspond to the prior art of the present invention. Therefore, further explaining the methods of (5) and (6), these techniques are methods for increasing the strength by reacting and permeating a metal into a refractory base material, a ceramic preform, a filler, and the like. .

[0004]

In the methods (5) and (6), the refractory base material, the ceramic preform, the filler, etc. produced by mixing the raw material with whiskers or fibers are made of metal. The reaction permeation can be expected to improve the sponging resistance of the reaction permeate.

However, when whiskers and fibers are used for the purpose of improving the anti-spooling property, not only the raw materials are expensive, but also the whiskers and fibers are difficult to disperse, so that they are non-uniform. It has a drawback that it is easy to become a thing.

By the way, the characteristics of the refractory base material, the ceramics preform, the filler and the like have a great influence on the reaction permeability and the characteristics of the reaction permeate. There is no one that explained the relationship in detail. In the conventional technique, it is very difficult to control the reaction permeability and the characteristics of the reaction permeate.

Therefore, the inventors of the present invention have conducted extensive studies on the relationship between the characteristics of the refractory base material and the characteristics of the reaction permeation material obtained by reactively permeating aluminum.
Moreover, the characteristics of the base material for reaction infiltration for producing a refractory material (reaction infiltration material) having excellent sponging resistance have been clarified and the present invention has been completed.

That is, an object of the present invention is to solve the above-mentioned conventional drawbacks and problems, and to provide a method for producing an alumina refractory material having high hot strength and excellent sparking resistance. In addition, it is an object of the present invention to provide an alumina refractory material suitable for applications such as members requiring particularly hot strength, sponging resistance, wear resistance and the like.

[0009]

Means for Solving the Problems The present invention is, as a means for achieving the above object, particularly as a refractory base material for reaction infiltration: a base material having a glass content of 3% or less; It is characterized by using a base material having 15% or more of 70 μm or more.

That is, according to the present invention, "a base material having a glass content of 3% or less and having a pore diameter of 70 μm or more and 15% or more of open pores is kneaded and molded using an alumina-based raw material and then fired. A method for producing an alumina refractory material, which is characterized by producing and reacting and permeating aluminum into the base material. "
(Claim 1) is the gist.

The present invention will be described in detail below.
The type of raw material used in the present invention is not particularly limited, and examples thereof include shale shale, sillimanite, bauxite, synthetic mullite, fused alumina, sintered alumina, and calcined alumina. System raw materials can be used. In addition, various oxides, carbides, nitrides and the like can be used as the pore forming agent and the mixed component, and these are also included in the present invention.

The present invention is based on the above-mentioned alumina raw material.
(Or a mixture of the raw materials with the above-mentioned mixed components)
Is fired to produce a refractory base material, which is characterized in that the glass content in the base material is 3% or less. Therefore, as the raw material (including the above-mentioned mixed components) used in the present invention, it is preferable to use a silica content of 5% or less.

As described above, the present invention is characterized in that the ratio of the amount of glass in the refractory base material is 3% or less. The reason for this will be described with reference to FIG. Note that FIG. 1 is a graph showing the influence of the amount of glass in the base material on the hot bending strength of the reaction permeate. That is, 2%, 4%, 6%, 8%, and 10% of kaolin was used as the raw material for fused alumina.
Mixed (the amounts of glass in the base material in this case are 0.8%, 1.7%, 2.6%, 3.5%, 4.3%, respectively, as shown in FIG. 1), and under the same conditions as in Example 1 described later. A base material was produced. Then, the "hot bending strength in a N ₂ atmosphere at 1400 ° C." of the reaction permeation product produced by reacting and permeating aluminum into the base material under the same conditions as in Example 1 was measured. It is a graph which showed the influence of the amount of glass in a base material which acts on the hot bending strength of a reaction permeate in this case.

As is apparent from FIG. 1, when the amount of glass in the base material exceeds 3%, the hot bending strength of the reaction permeate decreases. Therefore, in the present invention, the glass amount in the base material is 3%.
Must be: When the amount of glass in the base material increases
The reason why the hot bending strength of the reaction permeate decreases when it exceeds 3% (particularly if it exceeds 3%) is that the glass phase softens and melts during the hot process, causing the "grain boundary sliding effect", which may cause cracks and voids. It may be due to progress, but details are not clear.

In the present invention, the molding method for manufacturing the base material is not particularly limited, and for example,
Molding methods such as die press molding, rubber press (isostatic isostatic press), extrusion molding, casting molding, slip casting, injection molding and the like can be arbitrarily used. Regarding the firing conditions of the base material, the firing temperature and the firing time are not particularly limited, but in the present invention, it is usually "800 to 1800".
Calcination at 1 ° C to several hours ", and the glass content in the base material is 3% or less, and as will be described later, the open pores have a pore diameter of 70 µm or more and 15% or more. Need to be adjusted.

As described above, in the present invention, the amount of glass in the base material needs to be adjusted to 3% or less by the combination of both "from the viewpoint of raw material" and "from the viewpoint of firing conditions". However, in the present invention, the open pores of the base material must be “having a pore diameter of 70 μm or more and 15% or more”, which is also a feature of the present invention. Less than,
This point will be described in detail.

As a result of repeated studies by the present inventors, the relationship between the "pore size of the open pores of the base material" and the "spooling resistance of the reaction permeate obtained by reacting and permeating aluminum into the base material" Spoiling resistance of the reaction permeate is 70 μm.
It has been found that it has the best correlation with the "content ratio of m or more". Regarding the relationship between "the ratio of the pore size of the open pores of the base material of 70 µm or more" and "the sponging resistance of the reaction permeate", A description will be given based on FIG.

FIG. 2 shows a pore diameter of 70 μm among the open pores of the base material.
The ratio of m or more and the number of cycles of the reaction permeate (the number of times until cracking, which is an index of sponging resistance)
FIG. That is, 3% of ball clay was mixed with the sintered alumina raw material to prepare 6 kinds of compounds having different particle sizes, and these compounds were mixed at a pressure of 60 MPa and a width of 100%.
mm, thickness 45mm, length 160mm, then 1760 ℃
Then, it was baked for 3 hours to obtain a base material. Aluminum is reacted and infiltrated into the base material in the same manner as in Example 1 described later, and then the infiltrated portion is processed into a cubic shape with a side of 36 mm,
C./15 minutes-water cooling / 3 minutes-air cooling / 12 minutes "was repeated to carry out a spooling test, and the number of times (cycle number) until cracking was measured. FIG. 2 is a diagram showing the relationship between the “cycle number” which is an index of the anti-spooling property in this case and the “ratio of the open pores of the base material having a pore diameter of 70 μm or more”.

As is apparent from FIG. 2, the reaction permeation product using as the base material one having 15% or more of the open pores of the base material having a pore size of 70 μm or more is excellent in the anti-spooling property. Admitted. In the present invention, “the ratio of the open pores of the base material having a pore diameter of 70 μm or more” is “15% or more”.
And the upper limit is not particularly limited,
Generally, "70% or less" is preferable. The reason is that it is not easy to increase the ratio of the pore diameter of 70 μm or more among the open pores of the base material to 70% or more, and the improvement of the effect is not particularly recognized.

[0020]

Next, examples of the present invention will be described together with comparative examples.
The present invention will be described in more detail, but the present invention is not limited only to the following examples.

Here, the following Examples 1 to 6 and Comparative Example 1
Table 1 shows the particle sizes of the base material-forming compounds used in Examples 1 to 3 together.

[0022]

[Table 1]

(Example 1) A ball clay was added to sintered alumina.
1% was mixed to prepare a particle size shown in the particle size composition in Table 1 above, and molded at a pressure of 60 MPa into a shape with a width of 85 mm, a thickness of 45 mm and a length of 110 mm, and the molded body was baked at 1760 ° C. for 3 hours. I used it as the base material. The glass amount in this base material was 0.4%, and the ratio of the open pores having a pore diameter of 70 μm or more was 22.5%.

An aluminum molded body having a width of 85 mm, a thickness of 20 mm, and a length of 110 mm was placed on the upper surface of the base material at a pressure of 100 MPa, and the mixture was reacted and permeated under an oxygen atmosphere at 1150 ° C. for 3 hours. After cooling, the reaction permeated portion was cut out, and hot bending strength was measured at 1400 ° C. in a nitrogen atmosphere. In addition, the permeation part is processed into a cube shape with a side of 36 mm,
Minute-water cooling / 3 minutes-air cooling / 12 minutes "
A ring test was conducted.

As a result, the hot bending strength of the reaction permeate is 4
It was 5.7 MPa. This value is extremely large among refractory materials. On the other hand, the number of cycles to reach the spooling, which is an index of the spooling resistance, is 17,
It was also found to have excellent anti-spooling properties.

(Example 2) 80% of sintered alumina and 20% of calcined alumina were mixed to prepare a mixture having a particle size shown in Table 1, and a pressure of 100 MPa gave a width of 85 mm, a thickness of 45 mm and a length of 45 mm. After being formed into a shape having a length of 110 mm, it was fired at 1650 ° C. for 3 hours to obtain a base material. The glass amount of this base material is 0.01%, which is a very small amount, and the ratio of open pores with a pore diameter of 70 μm or more is 18.5%.
Met.

0.5% of Pyrex glass powder with respect to the weight of the base material was applied on the upper surface of the base material, and 100 MPa was applied on the upper part
An aluminum compact molded into a shape having a width of 85 mm, a thickness of 20 mm and a length of 110 mm under the pressure was placed, and the reaction was permeated under the same conditions as in Example 1. Then, with respect to the reaction permeation portion, Example 1
The number of cycles, which is an index of hot bending strength and spooling resistance, was measured in the same manner as in (1). As a result, the hot bending strength of the reaction permeate was 46.5 MPa and the number of cycles was 15.

(Example 3) 96% of fused alumina, chromia
3% and 1% of kaolin were mixed to prepare particles having the particle sizes shown in Table 1. It is 100mm wide and 100mm wide and 45m thick.
After being molded into a shape of m and 160 mm in length, it was fired at 1760 ° C for 3 hours to form a refractory base material. The glass amount of this base material is 0.4%, and the ratio of open pores with a pore diameter of 70 μm or more is 42.3.
%Met.

On the upper surface of the base material, at a pressure of 100 MPa, a width of 100 mm,
An aluminum molded body having a thickness of 20 mm and a length of 160 mm was placed thereon, and aluminum was reactively permeated under the same conditions as in Example 1, and hot bending strength and sponging resistance were obtained in the same manner as in Example 1. The number of cycles, which is an index of, was measured. As a result, the hot bending strength of the reaction permeate is 41.2 MPa,
The number of cycles was 23.

(Example 4) Sintered alumina 60%, white boxside 36%, and ball clay-4% were mixed to prepare particles having a particle size shown in Table 1, and a width of 85 mm at a pressure of 100 MPa, Thickness
After being formed into a shape with a length of 45 mm and a length of 110 mm, it was fired at 1500 ° C. for 3 hours to obtain a refractory base material. The amount of glass in this base material is 2.6
%, And the percentage of open pores with a pore size of 70 μm or more
It was 27.2%.

On the upper surface of the base material, an aluminum molded body having a width of 85 mm, a thickness of 20 mm and a length of 110 mm was placed under a pressure of 100 MPa, and aluminum was reacted and permeated under the same conditions as in Example 1, and The number of cycles, which is an index of hot bending strength and sponging resistance, was measured in the same manner as in 1. As a result, the hot bending strength of the reaction permeate was 40.5 MPa,
The number of cycles was 18 times.

(Embodiment 5) Fused alumina 87%, silicon carbide
10% and Pyrex 3% are mixed and adjusted to the particle size shown in the particle size composition of Table 1, width 85mm, thickness 45mm at a pressure of 60MPa,
After being formed into a shape with a length of 110 mm, it was fired at 1600 ° C. for 3 hours to obtain a refractory base material. The amount of glass in this base material is 1.3%, and the ratio of open pores with a pore diameter of 70 μm or more is 24.4%.
Met.

An aluminum molded body having a width of 85 mm, a thickness of 20 mm, and a length of 110 mm was placed on the upper surface of the base material at a pressure of 100 MPa, and the aluminum was reacted and permeated under the same conditions as in Example 1, and The number of cycles, which is an index of hot bending strength and sponging resistance, was measured in the same manner as in 1. As a result, the hot bending strength of the reaction permeate was 42.6 MPa,
The number of cycles was 16. Further, the production phase of the reaction-permeated product was composed of alumina, silicon carbide, aluminum and silicon.

Example 6 Sintered alumina 90%, silicon nitride
7%, Bolecree-1%, and pore-forming agent 2% were mixed, and Table 1
Prepared to the particle size composition shown in the particle size composition and molded at a pressure of 60 MPa into a shape with a width of 85 mm, a thickness of 45 mm and a length of 110 mm, and then 176
The refractory base material was fired at 0 ° C for 3 hours. The amount of glass in this base material was 0.5%, and the pore diameter of the open pores was 70 μm.
The above rate was 65.4%.

An aluminum molded body having a width of 85 mm, a thickness of 20 mm and a length of 110 mm was placed on the upper surface of the base material under a pressure of 100 MPa, and the aluminum was reacted and permeated under the same conditions as in Example 1, and The number of cycles, which is an index of hot bending strength and sponging resistance, was measured in the same manner as in 1. As a result, the hot bending strength of the reaction permeate was 39.2 MPa,
The number of cycles was 22 times.

Comparative Example 1 Sintered alumina 92%, kaolin
8% was mixed and adjusted to the particle size shown in Table 1 for the particle size ratio.
A base material was formed by molding at a pressure of 0 MPa into a shape with a width of 100 mm, a thickness of 45 mm, and a length of 160 mm, and then firing at 1500 ° C. for 3 hours.
The glass amount in this base material was 3.5%, and the ratio of the open pores having a pore diameter of 70 μm or more was 23.8%.

On the upper surface of the base material, width 100 mm, thickness 20 mm, length 1
An aluminum molded body having a shape of 60 mm was placed, and aluminum was reactively permeated under the same conditions as in Example 1. Then, with respect to the reaction permeated portion, the number of cycles, which is an index of hot bending strength and spooling resistance, was measured in the same manner as in Example 1. As a result, the hot bending strength of the reactive permeate is
The number of cycles was 16 at 25.3 MPa.

In Comparative Example 1, the hot bending strength was small as compared with Examples 1 to 6 above. this is,
In Comparative Example 1, the glass content was "3.5%", which exceeded the range (3% or less) of the glass content in the base material specified in the present invention, and thus the glass content in the base material was large. Is believed to be the cause.

(Comparative Example 2) 59% of sintered alumina, 40% of fused alumina, and 1% of volley were mixed to prepare particles having a particle size composition shown in Table 1, and a pressure of 60 MPa gave a width of 85 mm and a thickness of 85 mm. 45m
After being molded into a shape of m and 110 mm in length, it was fired at 1760 ° C for 3 hours to form a refractory base material. The amount of glass in the base material was 0.4%, and the ratio of the open pores having a pore diameter of 70 μm or more was 12.1
%Met.

Aluminum formed into a shape of width 85 mm, thickness 20 mm, and length 110 mm under a pressure of 100 MPa was placed on the upper surface of the base material, and aluminum was reacted and permeated under the same conditions as in Example 1. Then, with respect to the reaction permeated portion, the number of cycles, which is an index of hot bending strength and spooling resistance, was measured in the same manner as in Example 1. As a result, the hot bending strength of the reaction permeate was 44.6 MPa and the number of cycles was 8.

In Comparative Example 2, the number of cycles was smaller than that in Examples 1 to 6, that is, the result was inferior in the spring resistance. In Comparative Example 2, this is “12.1%” which is outside the range of “ratio of pore diameter of open pores of 70 μm or more = 15% or more” in the base material specified in the present invention. It is considered that the ratio of 70 μm or more of the open pores of the material was small.

(Comparative Example 3) Sintered alumina raw material 65%, calcined alumina 25%, and ball clay-10% were mixed to prepare a particle size shown in the particle size composition of Table 1, and a width of 85 mm at a pressure of 60 MPa, The base material was formed into a shape with a thickness of 45 mm and a length of 110 mm, and fired at 1600 ° C for 3 hours. The glass amount of the base material is 3.9%, and the ratio of the open pores having a pore diameter of 70 μm or more is 8.0%.
Met.

Aluminum formed into a shape of width 85 mm, thickness 20 mm, and length 110 mm under a pressure of 100 MPa was placed on the upper surface of the base material, and aluminum was reactively permeated under the same conditions as in Example 1. Then, with respect to the reaction permeated portion, the number of cycles, which is an index of hot bending strength and spooling resistance, was measured in the same manner as in Example 1. As a result, the hot bending strength of the reaction permeate was 21.7 MPa and the number of cycles was 6.

In Comparative Example 3, as compared with Examples 1 to 6, the hot bending strength was small, and the number of cycles as an index of the anti-spooling property was small. This is "3.9%" in Comparative Example 3 which exceeds the "range of glass amount in the base material (3% or less)" specified in the present invention, and "in the base material specified in the present invention". The ratio of the open pores having a pore diameter of 70 μm or more = 15% or more was “8.0%”, and thus “the glass content in the base material was large” and “the open pores of the base material” The ratio of 70 μm or more was low ”.

Here, the above Examples 1 to 6 and Comparative Examples 1 to
Hot bending strength (MPa) of the base material and reactive osmosis product used in 3.
Tables 2 and 3 collectively show the number of cycles (times) as an index of the anti-spooling property.

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

As described in detail above, the present invention is carried out by kneading and molding using an alumina-based raw material, followed by firing, "glass content is 3% or less""open pores having a pore diameter of 70 μm or more of 15%. It is characterized in that a base material having "above" is produced, and aluminum is reacted and permeated into the base material, whereby an alumina refractory material having a large hot strength and an excellent spring resistance is obtained. The effect obtained is produced.

The alumina refractory material obtained by the method of the present invention is a portion requiring excellent structure, strength, spooling resistance, wear resistance and the like, for example, a slide plate and pig iron. It is a refractory material suitable for mouth sleeves and the like.

[Brief description of drawings]

Fig. 1 Glass content in base metal and hot bending strength of reaction permeate
The figure which shows the relationship with (1400 degreeC in nitrogen atmosphere).

FIG. 2 is a diagram showing the relationship between the ratio of the pore diameter of 70 μm or more of the open pores of the base material and the number of cycles of the reaction permeate (the number of cycles until cracking, an index of sponging resistance).

Claims (3)

[Claims] 1. A base material having a glass content of 3% or less and having pore diameters of 70 μm or more and 15% or more of open pores is prepared by kneading and molding using an alumina-based raw material, A method for producing an alumina refractory material, which comprises reacting and permeating aluminum into a material. 2. The alumina-based raw material is shale shale,
Various alumina-based raw materials such as sillimanite, bauxite, synthetic mullite, fused alumina, sintered alumina, calcined alumina, or other components (various oxides, carbides, nitrides, etc.) in the alumina-based raw material. The method for producing an alumina refractory material according to claim 1, further comprising: a pore-forming agent. 3. As a means for reducing the glass content in the base material to 3% or less, it is prepared by a combination of the silica content of the alumina-based raw material and the firing conditions.
The method for producing an alumina refractory material according to 1.