JP2002274959A - Refractory material for aluminum and aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refractory material for aluminum and aluminum alloys preventing permeation of molten aluminum and deposition of oxides of molten aluminum. SOLUTION: The refractory material for aluminum and aluminum alloys is prepared by incorporating fluorine compounds by 0.01 to 30 wt.% in terms of fluorine into a refractory material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a refractory for aluminum and aluminum alloys, and more particularly to a refractory used as a lining in melting furnaces, holding furnaces, ladles, gutters, etc., which come into contact with molten aluminum and aluminum alloys. About.

[0002]

2. Description of the Related Art Molten aluminum and aluminum alloy (hereinafter abbreviated as "aluminum molten metal") have the property of easily penetrating into the refractory structure for aluminum and aluminum alloy, and have an extremely strong reducing power. The refractory which comes into contact with the molten aluminum gradually penetrates into the structure of the refractory, and the components such as silicic acid (SiO ₂ ) constituting the refractory are reduced and deteriorated, and are damaged. Further, when the above-mentioned reduction of silicic acid or the like occurs, oxidation of aluminum or the like also occurs, and a molten oxide such as Al ₂ O ₃ is generated. The molten oxide adheres to the surface of the refractory, grows gradually and closes the furnace space, which may hinder the melting operation. Further, at the time of removing the molten metal oxide, a mechanical impact is applied to the refractory, which often damages the refractory itself.

In order to prevent or suppress such damage to the refractory and the generation of deposits on the surface of the refractory, first,
It is important to prevent or suppress the penetration of the molten aluminum into the refractory.

[0004] The present applicant has previously completed the invention of a dense alumina brick as a refractory for aluminum and aluminum alloys in which such molten aluminum is prevented from penetrating (Japanese Patent No. 1679359). This brick is made of low-pressure compacted clay containing a mixture of refractory clay and aluminum phosphate mixed with alumina raw material and fired at a low temperature of several hundred degrees Celsius, and has a compressive strength of 170 MPa, a porosity of 16.5%, and an average porosity of 0.48 μm. It is characterized by high strength and low porosity. However, this brick is used as a fixed refractory, and it is difficult to apply the brick as a fixed refractory such as a casting material or a plastic material.

As means for preventing or suppressing the permeation of the molten aluminum, use of various permeation suppressing additives has been proposed. For example, US Pat. No. 4,126,474 describes BaSO ₄ as an additive that imparts resistance to the action of molten aluminum to various refractories. Also, JP-A-59-16997
The 1 discloses the use of _{9Al 2 O 3 · 2B 2 O} 3 has been proposed.

[0006] However, none of these permeation suppressive additives has a sufficient effect, and furthermore, there is a drawback that the adhesion of the molten oxide to the surface of the refractory cannot be sufficiently prevented. Further, each of them also has the following problems.
That is, since many barium salts are generally toxic, Ba
Refractories containing SO ₄ have the disadvantage that they must avoid operating under conditions where such toxic barium salts are decomposed and formed. _{Further, 9Al 2 O 3 · 2B 2} O 3 is itself expensive synthetic products, refractories blended with this there is a disadvantage that the cost.

As described above, in the art, the permeation of molten aluminum can be prevented, and the adhesion of molten metal oxides to the surface of refractory can be sufficiently prevented. There is a need for the development of improved refractories for aluminum and aluminum alloys, especially refractories that can be used not only as fixed refractories such as brick blocks, but also as cast refractories and as irregular refractories such as plastic materials. I have.

[0008]

Accordingly, it is an object of the present invention to provide an improved refractory for aluminum and aluminum alloys as desired in the art.

More specifically, the present invention prevents permeation of molten aluminum, sufficiently prevents adhesion of molten metal oxides and the like to the surface of a refractory material, and is safe and has no disadvantages in terms of cost. To provide refractories for aluminum, aluminum and aluminum alloys.

Another object of the present invention is to provide the above-mentioned refractory which can be used not only as a fixed refractory such as a brick block but also as an irregular refractory such as a casting material and a plastic material.

[0011]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that when a predetermined amount of a fluorine compound is contained in a refractory, a refractory meeting the above object is obtained. It was found that it could be obtained. The present invention has been completed based on this new finding.

The present invention relates to a refractory for aluminum and aluminum alloys, wherein the refractory has a fluorine content of 0.1.
Disclosed is a refractory for aluminum and an aluminum alloy, which contains a fluorine compound in an amount of from 01 to 30% by weight.

[0013] Further, the present invention provides a method wherein the fluorine compound is CaF ₂ ,
The refractory is provided, which is at least one selected from the group consisting of AlF ₃ , MgF ₂ , LiF, Na ₃ AlF ₆ and K ₃ AlF ₆ .

Further, the present invention relates to chamotte, mullite,
Using a refractory raw material containing a refractory powder material selected from calcined bauxite and fused alumina and a binder selected from finely divided alumina, finely divided clay mineral, ultrafinely divided silica, aluminum phosphate and sodium silicate The refractory described above is provided.

In particular, the refractories provided by the present invention include:
The fluorine content is preferably selected from the range of 0.1 to 5% by weight, and the refractory includes both amorphous refractories and fixed refractories.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The refractory of the present invention can prevent the penetration of molten aluminum into a refractory for a long time based on the use of a predetermined amount of a fluorine compound as described above. It is also possible to sufficiently prevent oxides and the like from adhering to the surface of the refractory.

The refractory of the present invention is safe and can be manufactured at a low cost, and can be used not only as a fixed refractory such as a brick block but also as an irregular refractory such as a casting material and a plastic material. There are advantages that can be done.

Hereinafter, the refractory of the present invention will be described in detail. The refractory of the present invention is characterized by containing the above-mentioned predetermined amount of the fluorine compound. Except for containing such a fluorine compound, it can be manufactured basically in the same manner as a conventional refractory for aluminum and aluminum alloys of this kind.

As the refractory raw material, any of various types known to be used as refractories for aluminum and aluminum alloys of this kind can be used. Examples thereof include those obtained by combining the following refractory powder materials, binders, and other additives as necessary. [Refractory powder material] (1) High alumina raw materials such as fused alumina, sintered alumina, and calcined alumina (2) Alumina-silica raw materials such as calcined bauxite, mullite, sillimanite, kyanite, andalusite (3) Raw Silica-alumina raw materials such as stone, chamotte and clay minerals (4) Silicic raw materials such as silica sand, silica stone, fused quartz, etc. (5) Spinel raw materials such as chromite, sintered spinel, and electrofused spinel (6) Magnesia clinker, Basic raw materials such as forsterite, dolomite clinker, and calcia (7) Zircon raw materials (8) Zirconia raw materials (9) Silicon carbide, zirconium carbide, aluminum carbide,
Raw materials of carbonized materials such as boron carbide (10) Raw materials of nitrided materials such as silicon nitride, zirconium nitride, boron nitride and aluminum nitride (11) Coke, natural graphite, artificial graphite, anthracite, carbon black, carbon brick waste, electrode waste, etc. Carbonaceous raw materials (12) Refractory aggregates such as sodium silicate lump, silicon, chromium oxide, etc.These refractory powder materials can be used by selecting one or two or more from each group. One or more kinds may be selected and used in combination.

The particle size of these refractory powder materials can be the same as that of ordinary materials of this kind.

Specific examples of the binder include alumina sol, silica sol, ethyl silicate, phosphoric acid, alumina cement, silicate, phosphate, fine clay mineral, ultrafine silica, fine alumina, hydraulic alumina, dextrin and carboxy. Examples include methylcellulose (CMC), hydroxyethylcellulose (HEC), and ligninsulfonate. In addition, a polymer compound such as a pitch and a phenol resin can also be used as the binder. The salts constituting the above silicates, phosphates and ligninsulfonates include aluminum salts and sodium salts.

One of these can be used alone, or two or more can be used in combination. The blending amount of the binder with respect to the refractory powder material is not particularly limited and can be appropriately selected from a wide range. Usually, the binder can be used in the range of about 0.1 to 50% by weight of the refractory powder.

Examples of additives that can be further compounded as required include, for example, fibrous materials such as ceramic fibers in the case of fixed refractories.

In the case of an amorphous refractory, a conventionally known dispersant for improving fluidity (for example, tripolyphosphate) and an explosion-proofing agent for preventing dry explosion (for example, metal aluminum powder, organic fiber and the like) And the like, and a thickener (for example, methylcellulose) for improving the ironing property. The compounding amount thereof can be the same as the compounding amount in known amorphous refractories. For example, a dispersant for improving the flowability can be generally added in a range of about 0.01 to 1% by weight of the refractory powder, and an anti-explosion agent for preventing dry explosion is generally used in an amount of the refractory powder by weight. Thickeners can be added in the range of about 0.01 to 1% by weight, and the thickener for improving the ironing property is generally added in the range of about 0.01 to 5% by weight of the refractory powder. it can.

It is important that the refractory of the present invention be obtained by adding a predetermined amount of a fluorine compound to the above-mentioned refractory raw materials (refractory powder material, binder and additive). Here, as the fluorine compound, CaF ₂ , AlF ₃ , MgF ₂ ,
LiF, Na ₃ AlF ₆ , K ₃ AlF _{6 and the} like are used alone or in combination of two or more. The form and size of these fluorine compounds are not particularly limited, and can be used in the present invention in the form of powders which are generally available. In order to easily and uniformly disperse and mix in the refractory raw material, a fine powder having a particle diameter of 0.1 mm or less is preferably used. Among these fluorine compounds, CaF ₂ and AlF ₃ are particularly preferred.

The compounding amount of the fluorine compound can be selected from the range in which the fluorine content (in terms of F) is 0.01 to 30% by weight based on the total amount of the refractory raw materials. By adding the fluorine compound in the above range, the desired effects of the present invention, that is, a sufficient effect of suppressing the permeation of the molten aluminum and an effect of preventing the adhesion of the oxide of the molten aluminum can be imparted to the obtained refractory. The reason is probably as follows. That is, when the molten aluminum is brought into contact with the refractory of the present invention at a high temperature such that the refractory of the present invention is used, a fluorine compound present in the refractory is suspended and suspended in the molten aluminum. Reacts with the oxides to form oxide films and particles on the surface of the refractory,
It is thought that this results in an increase in the surface tension of the molten aluminum, thus weakening the wettability of the molten aluminum.

When the compounding amount of the fluorine compound is less than 0.01% by weight, the intended effect of the present invention, particularly the effect of weakening the wettability of the molten aluminum and preventing or suppressing penetration into the refractory, is sufficiently exhibited. Will not be. Conversely, if it exceeds 30% by weight,
Although the effect of preventing or suppressing permeation is sufficient, the obtained refractory itself may have a low melting point and spoil resistance may be impaired. In order to exhibit the intended effect of the present invention, the particularly preferable compounding amount of the fluorine compound can be selected from the range of about 0.1 to 5% by weight.

The time of addition and compounding of the fluorine compound is arbitrary as long as it is before firing the refractory. Generally, it is mixed when the powder of the refractory raw material is mixed.

The production of the refractory of the present invention can be basically carried out in a conventional manner, except for the addition and blending of the fluorine compound. For example, the refractory powder material, a fluorine compound, a binder and, if necessary, additives are mixed, and after adding water and kneading,
The desired refractory of the present invention can be obtained by molding and firing.

In particular, in the case of amorphous refractories, generally, for example, the above-mentioned refractory powder material, fluorine compound, binder and various additives are mixed, and if necessary, water is added and kneaded. Thereafter, a manufacturing process of packing as a product is adopted. Also, in the case of a shaped refractory, generally, for example, after mixing the above-mentioned refractory powder material, a fluorine compound, a binder and various additives as necessary, and adding water and kneading,
A manufacturing process is employed in which the product is molded, dried and fired, and then subjected to processing such as cutting as required, and packed as a product.

The operation, conditions, etc. of the water addition / kneading, molding and firing can be the same as those employed in the production of this type of refractory.

The refractory of the present invention obtained in this way has an excellent effect of suppressing the penetration of molten aluminum and an effect of preventing adhesion of oxides of molten aluminum, and has the advantage of being safe, inexpensive and easy to manufacture. Yes, it is extremely useful as a refractory material for lining, such as a melting furnace, a holding furnace, a ladle, and a gutter for aluminum and aluminum alloys.

[0033]

The present invention will be described in more detail with reference to the following examples.

The chemical analysis values (based on atomic absorption spectrometry) of each refractory raw material used in the examples are as shown in Table 1 below.

[0035]

[Table 1]

Examples 1-5 and Comparative Examples 1-4 Production of Amorphous Refractories A predetermined amount of each refractory raw material and fluorine compound shown in Table 2 below was mixed using a 10-liter V-type mixer. Water was added and kneaded using a 10-liter winged mixer.

[0037]

[Table 2]

Next, in Example 1-4 and Comparative Example 1-3,
Each 5 kg of the kneaded material was poured into a mold capable of being formed into a cylindrical molded body (outer diameter 80 mm, height 65 mm, wall thickness 25 mm, inner hole inner diameter 30 mm, height 40 mm), and left at room temperature for 24 hours. Thereafter, the molded body was removed from the mold, and was heated at 110 ° C. for 12 hours in an electric hot air dryer.
After drying for an hour, the temperature was further raised to 800 ° C. using a resistance type electric heating furnace with a silicon carbide element, and held for 3 hours, followed by firing, to obtain each crucible sample.

In Example 5 and Comparative Example 4, the kneaded material was used as a cylindrical molded body (outer diameter 80 mm, height 65 mm, wall thickness 25 mm, inner hole inner diameter
Using a mold capable of molding (30 mm, height 40 mm), molding was performed with a hydraulic pressure machine at a molding pressure of 10 MPa. Next, the molded body was taken out of the mold, and then dried in an electric hot-air dryer.
After drying at 12 ° C. for 12 hours, the temperature was further raised to 800 ° C. using a resistance type electric heating furnace with a silicon carbide element, held for 3 hours and fired to obtain each crucible sample.

The formulas of Examples 1 and 2 and Comparative Example 1 were as follows:
This is a typical example of the formulation of a typical casting material for irregular shaped refractories commonly used in aluminum melting furnaces and the like.

In Examples 3 and 4 and Comparative Examples 2 and 3,
This is a formulation example of a high-strength cast material of an amorphous refractory used in an aluminum melting furnace or the like, mainly in a part where strength characteristics are required.

In addition, Example 5 and Comparative Example 4 are examples of formulating a clay-like plastic agent of an amorphous refractory widely used in an aluminum melting furnace or the like for repair or the like.

Test Example 1 Using each of the crucible samples obtained in Example 1-5 and Comparative Example 1-4, a molten aluminum was used under conditions using an aluminum alloy considered to be the most severe for refractories. The erosion test was performed as follows.

That is, it was previously melted in a graphite crucible,
A melt of an aluminum alloy (a hydrosodium alloy containing 5.5% magnesium) was poured into each crucible sample, and the temperature was raised to 1000 ° C. in an electric heating furnace and maintained for 100 hours. Thereafter, each crucible was cooled, taken out of the furnace, and cut with a diamond cutter.

The cut surface was visually observed, and the state of each crucible sample (contact depth of the molten aluminum into each sample (mm), penetration state, and adhesion of aluminum oxide and the like to the surface of each sample) Corrosion resistance using the situation as an index and its comprehensive evaluation) were evaluated.

In addition, the flow value (in the case of a cast material) and workability (in the case of a plastic material, a workability index according to JIS R2574, indicated as “WI” in the table) of the amorphous refractory in the erosion test were determined. .

Table 3 shows the results.

[0048]

[Table 3]

From the results shown in Table 3, it is clear that all of the refractories of the present invention can exhibit an excellent effect of suppressing permeation of molten aluminum and an effect of preventing adhesion of oxides of molten aluminum.

Example 6-7 and Comparative Example 5 Production of Fixed Refractories A given amount of each raw material and fluorine compound shown in Table 2 below was
After mixing using a V-type mixer having a capacity of 0 l, water was kneaded using a wheel-type kneader.

[0051]

[Table 4]

Next, each 5 kg of the kneaded material was formed into a parallel brick shape (65 × 114 × 230 mm) specified in JIS R2101 at a forming pressure of 20 MPa using a hydraulic press, and this was heated with an electric hot air type. It was dried in a drier at 110 ° C. for 24 hours, and further heated to 1300 ° C. at which the bonding force of clay was developed using a resistance type electric heating furnace with a silicon carbide element, and sintered for 3 hours.

The crucible samples obtained above were subjected to the erosion test according to Test Example 1 above, and the results are shown in Table 5 below.

[0054]

[Table 5]

From the results shown in Table 5, it is clear that the refractory material of the present invention can exhibit an excellent effect of suppressing the permeation of molten aluminum and an effect of preventing adhesion of oxides of molten aluminum.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F27D 1/00 C04B 35/00 W (72) Inventor Hiroyuki Suzuki 56 God of Mifunemachiyama, Toyota City, Aichi Prefecture, Japan F-term (reference) in Bottom Co., Ltd. 4G030 AA36 AA58 BA28 HA05 4G033 AA02 AA10 AB02 AB03 AB04 AB07 AB10 BA01 4K051 AA06 AB03 AB05 BE03

Claims (6)

[Claims] 1. A refractory for aluminum and an aluminum alloy, characterized in that the refractory contains a fluorine compound in an amount such that the fluorine content is 0.01 to 30% by weight. 2. The method according to claim 1, wherein the fluorine compound is CaF ₂ , AlF ₃ , MgF ₂ , Li
2. The refractory according to claim 1, wherein the refractory is at least one selected from the group consisting of F, Na ₃ AlF ₆ and K ₃ AlF ₆ . 3. A refractory powder material selected from chamotte, mullite, calcined bauxite and fused alumina,
2. The refractory according to claim 1, which is obtained by using a refractory raw material containing fine alumina, fine clay mineral, ultrafine silica, a binder selected from aluminum phosphate and sodium silicate. 4. The refractory according to claim 1, wherein the fluorine content is selected from the range of 0.1 to 5% by weight. 5. The refractory according to claim 1, which is an amorphous refractory. 6. The refractory according to claim 1, which is a fixed refractory.