JP2016160143A - Refractory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refractory and a production method of the same, capable of suppressing a reaction between the refractory and Fe-based alloy raw materials, reducing generation of erosion and slag, and suppressing cracks on an inner wall of the refractory.SOLUTION: A spinel raw material excellent in corrosion resistance relative to an alumina raw material, is added to the alumina raw material by a predetermined amount, and a ratio of an AlOcomponent and a MgO component is adjusted for obtaining a raw material, then the obtained raw material is sintered for forming into a shaped article, and the shaped article has a minute tissue structure. Thereby the shaped refractory comprises improved corrosion resistance to molten metal.SELECTED DRAWING: None

Description

  The present invention relates to a regular refractory suitable for a crucible or the like for melting an Fe-based alloy raw material, such as an Fe-based amorphous alloy, an Fe-based nanocrystalline alloy, or metallic glass.

  Patent Document 1 contains 40 to 93% by weight of alumina raw material, 5 to 40% by weight of calcined spinel with a particle size of 1 mm or less, and 2 to 20% by weight of alumina cement. Alumina-spinel amorphous refractories are described.

As calcined _spinel, Al ₂ O _{3, MgO,} can be used a material containing _{Fe 2 O 3, SiO 2,} CaO is illustrated. Furthermore, since it is an irregular refractory, it is described that a predetermined amount of water is added, poured into a metal frame, molded and dried.

Japanese Unexamined Patent Publication No. 7-330449

  As exemplified in Patent Document 1, the amorphous refractory is obtained by mixing a fire-resistant raw material with water, for example, forming into a crucible shape and drying.

  Although the surface of the amorphous refractory has a relatively dense structure, it is simply formed and dried, so that, for example, an Fe-based amorphous material containing dissolved elements such as P, Si, B, and Cu. In the alloy material, these elements and raw material components on the surface of the amorphous refractory react to form a low melting point compound, and the molten metal permeates into the refractory and causes melting and slag. .

  Furthermore, there is a problem that cracks are likely to occur on the surface of the irregular refractory due to thermal expansion.

  The present invention provides a refractory that suppresses the reaction between the refractory and the Fe-based alloy raw material, reduces the occurrence of erosion and slag, and is less prone to cracks on the inner wall of the refractory, and a method for producing the same. Objective.

In order to solve the above problems, the refractory according to the present invention adds a predetermined amount of a spinel raw material, which has better corrosion resistance than the alumina raw material, to the alumina raw material, that is, adjusts the ratio of the Al ₂ O ₃ component and the MgO component. The raw material obtained in this manner is sintered into a regular shape, and a finer structure is obtained, thereby obtaining a regular refractory with increased corrosion resistance to the molten metal.

  That is, by using a regular refractory obtained by sintering, it is possible to prevent particles constituting the refractory from being separated and mixed into the molten metal.

  Furthermore, by giving the residual expansibility, the occurrence of cracks in the refractory is suppressed.

The present invention is a refractory that is a sintered body containing 90% by mass to 98% by mass of an Al ₂ O ₃ component and 2% by mass to 8% by mass of an MgO component.

The present invention is a refractory that is a sintered body containing 92% by mass to 95% by mass of an Al ₂ O ₃ component and 5% by mass to 7% by mass of an MgO component.

  The present invention is a refractory having a residual expansion coefficient of 0.3% or less (not including 0).

In the present invention, alumina raw material 70% by mass to 90% by mass and spinel raw material 10% by mass to 30% by mass are mixed, Al ₂ O ₃ component 90% by mass to 98% by mass, MgO component 2 A step of obtaining a mixture containing not less than 8% by mass and not more than 8% by mass; a step of filling the mixture into a mold to obtain a molded body; a step of removing the molded body from the mold and drying; and baking the molded body. A method for producing a refractory, characterized by comprising a step of tying.

In the present invention, alumina raw material 70% by mass to 85% by mass and spinel raw material 15% by mass to 30% by mass are mixed, Al ₂ O ₃ component 92% by mass to 95% by mass, MgO component 5 A step of obtaining a mixture containing not less than 7% by mass and not more than 7% by mass, a step of filling the mixture into a mold to obtain a molded body, a step of removing the molded body from the mold and drying it, and firing the molded body. A method for producing a refractory, characterized by comprising a step of tying.

  According to the present invention, the reaction between the refractory and the molten alloy raw material is suppressed, the occurrence of erosion and slag is reduced, and the inner wall of the refractory is less likely to crack, that is, corrosion resistance and penetration resistance. An excellent refractory material having a relatively long life and particularly suitable as a holding container or holding tool for molten Fe-based alloy and a method for producing the same can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail.

A mixture containing a predetermined amount of Al ₂ O ₃ and MgO in which an alumina raw material and a spinel raw material mixed to have a predetermined mixing ratio and composition are mixed with a binder, such as a crucible shape or a cylindrical shape suitable for use in a melting furnace, etc. A molded body obtained by uniformly and densely filling a mold having a predetermined shape and then removing the mold is dried and sintered to obtain the refractory of the present invention.

Any alumina raw material may be used as long as it mainly has an Al ₂ O ₃ composition. For example, electrofused alumina or sintered alumina is preferably used alone or in combination. The mixing ratio of the alumina raw material is preferably 70% by mass or more and 90% by mass or less in which the corrosion resistance to the molten metal does not decrease.

  In addition, the refractory preferably has a residual expansion coefficient of 0.3% or less in order to make it difficult for cracks and breakage to occur. In this case, the mixing ratio of the alumina raw material is more preferably 70% by mass or more and 85% by mass or less.

The spinel raw material may be any material as long as it mainly has a MgAl ₂ O ₃ composition. For example, it is preferable to use a fused spinel, a sintered spinel or the like alone or in combination. If the blending ratio of the spinel raw material is less than 10% by mass, the spinel area exposed on the surface of the refractory is reduced, so the corrosion resistance to the molten metal is lowered. descend. Therefore, the blending ratio is preferably 10% by mass or more and 30% by mass or less.

  The residual expansion coefficient can be adjusted by increasing a certain amount of the MgO component contained in the spinel raw material. Therefore, considering the residual expansion rate, the blending ratio of the spinel raw material is more preferably 15% by mass or more and 30% by mass or less.

Spinel reacts with the FeO and MnO components in the slag and has an effect of suppressing the penetration of the slag by solid solution, but the effect of suppressing the penetration of the slag containing the CaO and SiO ₂ components. Therefore, if added excessively, the corrosion resistance decreases. Therefore, the blending ratio is more preferably about 20% by mass.

By adjusting the mixing ratio of the alumina raw material and the spinel raw material as described above, the refractory according to the present invention has Al ₂ O ₃ of 90% by mass or more and less than 98% by mass, and MgO of 2.0% by mass or more and 8.0% by mass. A sintered body containing at most mass% is preferred.

Furthermore, considering the residual expansion coefficient, the refractory according to the present invention is a sintered body containing Al ₂ O ₃ in an amount of 92% by mass to less than 95% by mass and MgO in an amount of 5.0% by mass to 7.0% by mass. More preferably.

In addition, as a spinel material, it is preferable to use a spinel composition having a molar ratio of Al ₂ O ₃ : MgO = 90: 10 to 60:40.

Similarly, considering the residual expansion rate, it is more preferable to use a spinel material having a spinel composition of Al ₂ O ₃ : MgO = 85: 15 to 60:40 in a molar ratio.

Components such as SiO ₂ and Fe ₂ O ₃ contained as impurities in the alumina raw material and the spinel raw material cause a low melting point when the slag penetrates and increase the permeation layer. Therefore, the alumina raw material or the spinel raw material is It is more preferable to use those having a total impurity content of 3.0% or less.

  The particle size of the alumina raw material and the spinel raw material may be any, and in order to improve fluidity and fillability, the particle size blending is adjusted, that is, each raw material is coarse powder, medium powder, fine powder, and the ratio is adjusted appropriately. Is preferred.

  In order to improve the filling property to the mold, it is preferable to adopt a molding method such as applying a compressive stress or applying vibration with a press or stamp after pouring the mixture of the alumina raw material and the spinel raw material into the mold. .

  Any binder may be mixed with the alumina raw material and the spinel raw material, and an inorganic compound such as sodium silicate, and an organic compound such as phenol resin and PVA are preferable.

  The shape of the formwork may be either a unitary structure or a divided structure, but it is possible to reduce the portion that is highly reactive with the molten metal or slag, such as seams and voids caused by degranulation, so the inner wall that contacts the molten metal It is more preferable that the parts have an integral structure.

  Since the refractory of the present invention obtained as described above is a sintered body, it has high corrosion resistance against elements having high reactivity with refractories such as P, Si, and B elements, and particularly for melting and holding molten metal for Fe-based alloys. Suitable for tools, crucibles, refining containers and the like.

  In addition, slag generated due to refractory erosion can be reduced, and a highly clean molten metal can be obtained. For example, quality deterioration due to entrainment of impurities and nozzle clogging are reduced during the manufacture of amorphous alloy ribbons. can do.

  Hereafter, it demonstrates concretely using the Example of this invention.

Example 1
A binder made of sodium silicate was weighed with an alumina raw material and a spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 76:24 to a blending ratio of 90% by mass of the alumina raw material and 10% by mass of the spinel raw material. Mixed with. Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 96.4% by mass and MgO was 2.4% by mass.

  The mixture is poured into a crucible-shaped mold, molded by stamping, taken out from the mold, dried in an oven at 450 ° C., heated to 1300 ° C. and fired, outer diameter φ85 mm × inner diameter A crucible-shaped refractory having a diameter of 73 mm and a height of 160 mm was obtained.

(Example 2)
A binder made of sodium silicate, which weighs an alumina raw material and a spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 76:24 so that the mixing ratio is 80% by mass of the alumina raw material and 20% by mass of the spinel raw material. Mixed with.

Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 94.0% by mass and MgO was 4.8% by mass.

  While pouring this mixture into a crucible-shaped mold, a crucible-shaped refractory having the same size as in Example 1 was obtained in the same manner as in Example 1.

(Example 3)
A binder made of sodium silicate, which weighs an alumina raw material and a spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 76:24 to a blending ratio of 70% by mass of the alumina raw material and 30% by mass of the spinel raw material. Mixed with.

Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 91.6% by mass and MgO was 7.2% by mass.

  While pouring this mixture into a crucible-shaped mold, a crucible-shaped refractory having the same size as in Example 1 was obtained in the same manner as in Example 1.

(Comparative Example 1)
An alumina raw material and a spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 76:24 are weighed so that the mixing ratio is 80% by mass of the alumina raw material and 10% by mass of the spinel raw material, and further 10% by mass of the alumina cement. And water were added and mixed to obtain a slurry mixture.

Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 96.4% by mass and MgO was 2.4% by mass.

  The mixture is poured into a mold, dried in a mold at 100 ° C., removed from the mold and fired at 1300 ° C., and a crucible-shaped refractory having an outer diameter φ85 mm × inner diameter φ73 mm × height 160 mm is obtained. Obtained.

(Comparative Example 2)
A crucible shaped refractory having the same size as in Example 1 was obtained in the same manner as in Example 1 using only the alumina raw material.

(Comparative Example 3)
Binder made of sodium silicate, weighed alumina raw material and spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 76:24 to a blending ratio of 95% by weight of alumina raw material and 5% by weight of spinel raw material Mixed with.

Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 97.6% by mass and MgO was 1.2% by mass.

  While pouring this mixture into a crucible-shaped mold, a crucible-shaped refractory having the same size as in Example 1 was obtained in the same manner as in Example 1.

(Comparative Example 4)
A binder made of sodium silicate was weighed with an alumina raw material and a spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 76:24 to a mixing ratio of 60% by mass of the alumina raw material and 40% by mass of the spinel raw material. Mixed with.

Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 89.2% by mass and MgO was 9.6% by mass.

  While pouring this mixture into a crucible-shaped mold, a crucible-shaped refractory having the same size as in Example 1 was obtained in the same manner as in Example 1.

  In each of the refractories of Examples 1 to 3 and Comparative Examples 1 to 4, iron, ferroboron, ferrophosphorus, metal silicon, and electrolytic copper were weighed and put in total so that each had a predetermined composition. It melt | dissolved in the vacuum in the inside, and the Fe-Si-B-P-Cu alloy molten metal was obtained.

  After these raw materials were melted, the molten metal was held in each refractory at 1350 ° C. for 2 hours, and then the molten metal was taken out into a mold. After cooling, the refractory taken out from the melting furnace was cut, and the inner wall was observed and the molten metal permeation portion in the longitudinal section was measured. The results are shown in Table 1. Table 1 shows the surface reaction state and the penetration depth.

  In the refractories of Examples 1 to 3, the surface reaction with the Fe—Si—B—P—Cu alloy molten metal is suppressed, and the penetration depth of the molten metal is also suppressed to 2 mm or less. It can be seen that the reaction with the molten metal is suppressed by densification and appropriate addition of MgO.

  On the other hand, in Comparative Example 1 that is not sintered, that is, an amorphous refractory, the surface reaction with the molten metal is remarkable, and further, when the inside of the refractory is observed, it can be seen that the molten metal penetrates deeply. .

  Furthermore, although the refractories of Comparative Examples 2 to 4 are sintered bodies, a surface reaction with the molten Fe—Si—B—P—Cu alloy occurs, and in Comparative Examples 2 and 3 in particular, the molten metal The infiltration part reaches the vicinity of the outer wall of the refractory. That is, it can be seen that Comparative Example 2 and Comparative Example 3 have insufficient spinel addition and insufficient corrosion resistance.

  Industrial iron, Fe-B, Fe-P, and electrolytic copper were weighed to be Fe 83.3 at%, B 7 at%, P 9 at%, Cu 0.7 at%, and obtained in Examples 1 to 3 and Comparative Examples 1 to 4. Put in each refractory, melt in a high-frequency melting furnace, hold at 1350 ° C. for 2 hours, then pour each mother alloy obtained by casting into a mold, cut into a cube shape of 2 cm × 2 cm × 2 cm, respectively, The composition of was analyzed. The results are shown in Table 2.

  Furthermore, the amorphous alloy continuous thin ribbon having a width of 1 mm, a thickness of 25 μm, and 8.0 g obtained by the single-roll liquid quenching method using each of the mother alloys described above was cut in a length direction by 6 cm, and the infrared heating apparatus After the heat treatment, each coercive force Hc was measured using a direct current BH tracer. The results are shown in Table 3.

  According to Table 2, when the relative error from the target alloy composition is calculated for each alloy element in the Fe—B—P—Cu alloy manufactured using the refractories of Examples 1 to 3, the Fe is 0. 08% to 0.24%, B is 0.71% to 1.4%, P is 0.89% to 2.56%, and Cu is 4.2% to 7.1%.

  The detected amount of Mg or Al, which is the main component of the refractory, is below the detection limit for Mg and 0.01% to 0.02% for Al.

  In the Fe—B—P—Cu alloy manufactured using the refractories of Comparative Examples 1 to 4, when the relative error from the target alloy composition was calculated for each alloy element, Fe was 0.32% to 1. 6%, B is 2.4% to 5.7%, P is 2.7% to 9.0%, Cu is 8.6% to 17.0%, all compared with Examples 1 to 3 It can be seen that there is a large deviation from the target alloy composition for these elements.

  The detected amounts of Mg and Al, which are the main components of the refractory, are 0.02% to 0.20% for Mg and 0.06% to 0.25% for Al. As compared with Examples 1 to 3, it can be seen that both Mg and Al are large.

  From the above results, it is clear that the refractory of the present invention has a suppressed reaction with the molten alloy.

  Furthermore, according to Table 3, the coercive force Hc is less than 10 A / m in any case in the Fe—B—P—Cu alloys manufactured using the refractories of Examples 1 to 3. On the other hand, in the alloys manufactured using the refractories of Comparative Examples 1 to 4, the coercive force Hc exceeds 10 A / m.

  The deterioration of the coercive force in each comparative example is considered to be due to the inclusion of refractory components because of the large amount of Mg and Al detected, so the refractory of the present invention has a dense surface structure by sintering, It is clear that the main component elements are prevented from flowing out.

Example 4
A binder made of sodium silicate was weighed with an alumina raw material and a spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 66:34 to a blending ratio of 90% by mass of the alumina raw material and 10% by mass of the spinel raw material. Mixed with. Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 93.7% by mass and MgO was 5.1% by mass.

  The mixture is poured into a box-shaped formwork, squeezed with a stamp, molded, taken out from the formwork, dried in an oven at 450 ° C, heated to 1300 ° C, fired, 40 mm x 40 mm x long A rod-like refractory having a thickness of 250 mm was obtained.

(Example 5)
A binder made of sodium silicate, which weighs an alumina raw material and a spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 71:29 so that the mixing ratio is 80% by mass of the alumina raw material and 20% by mass of the spinel raw material. Mixed with. Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 93.0% by mass and MgO was 5.8% by mass.

  The mixture is poured into a box-shaped formwork, squeezed with a stamp, molded, taken out from the formwork, dried in an oven at 450 ° C, heated to 1300 ° C, fired, 40 mm x 40 mm x long A rod-like refractory having a thickness of 250 mm was obtained.

(Example 6)
A binder made of sodium silicate, which weighs an alumina raw material and a spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 66:34 such that the mixing ratio of the alumina raw material is 80% by mass and the spinel raw material is 20% by mass. Mixed with. Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 92.1% by mass and MgO was 6.8% by mass.

  The mixture is poured into a box-shaped formwork, squeezed with a stamp, molded, taken out from the formwork, dried in an oven at 450 ° C, heated to 1300 ° C, fired, 40 mm x 40 mm x long A rod-like refractory having a thickness of 250 mm was obtained.

(Example 7)
A binder made of sodium silicate, which weighs an alumina raw material and a spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 78:22 so that the mixing ratio is 80% by mass of the alumina raw material and 20% by mass of the spinel raw material. Mixed with. Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 92.2% by mass and MgO was 6.6% by mass.

  The mixture is poured into a box-shaped formwork, squeezed with a stamp, molded, taken out from the formwork, dried in an oven at 450 ° C, heated to 1300 ° C, fired, 40 mm x 40 mm x long A rod-like refractory having a thickness of 250 mm was obtained.

(Comparative Example 5)
An alumina raw material and a spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 76:24 are weighed so that the mixing ratio is 80% by mass of the alumina raw material and 10% by mass of the spinel raw material, and further 10% by mass of the alumina cement. And water were added and mixed to obtain a slurry mixture.

Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 96.4% by mass and MgO was 2.4% by mass.

  This mixture is poured into a box-shaped mold, dried at 100 ° C. while being placed in the mold, and then removed from the mold and baked at 1300 ° C. to obtain a rod-like refractory having a size of 40 mm × 40 mm × length 250 mm. It was.

(Comparative Example 6)
A binder made of sodium silicate, which weighs an alumina raw material and a spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 78:22 so that the mixing ratio is 80% by mass of the alumina raw material and 20% by mass of the spinel raw material. Mixed with.

Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 94.5% by mass and MgO was 4.4% by mass.

  A rod-like refractory having the same size as in Example 4 was obtained by the same method as in Example 1 while pouring this mixture into a box-shaped formwork.

(Comparative Example 7)
A binder made of sodium silicate was weighed with an alumina raw material and a spinel raw material having an Al ₂ O ₃ to MgO component ratio of 78:22 so that the mixing ratio was 90% by mass of the alumina raw material and 10% by mass of the spinel raw material. Mixed with.

Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 96.5% by mass and MgO was 2.2% by mass.

  A rod-like refractory having the same size as in Example 4 was obtained by the same method as in Example 1 while pouring this mixture into a box-shaped formwork.

(Comparative Example 8)
A binder made of sodium silicate, which weighs an alumina raw material and a spinel raw material having a component ratio of Al ₂ O ₃ to MgO of 78:22 so that the mixing ratio is 60% by mass of the alumina raw material and 40% by mass of the spinel raw material. Mixed with.

Composition analysis of the obtained mixture revealed that Al ₂ O ₃ was 90.0% by mass and MgO was 8.8% by mass.

  A rod-like refractory having the same size as in Example 4 was obtained by the same method as in Example 1 while pouring this mixture into a box-shaped formwork.

  After placing the refractories of Examples 4 to 7 and Comparative Examples 5 to 8 inside the melting crucible, weigh 10 kg in total so that pure iron, ferroboron, ferrophosphorus, metal silicon, and electrolytic copper each have a target composition. Then, these raw materials were melted in a nitrogen atmosphere by a high-frequency melting furnace to obtain a Fe—Si—B—P—Cu alloy melt, and the temperature of the melt was raised to 1400 ° C. Held for hours.

  After the above treatment was repeated three times and each refractory was cooled, the depth of the cracks that occurred, the slag line (hereinafter referred to as SL) melting and the molten metal penetration state (hereinafter referred to as ML) Evaluation was made as a corrosion resistance test.

  Table 4 shows the corrosion resistance test results together with the measurement results of the porosity, apparent specific gravity, bulk specific gravity, and thermal expansion coefficient of each refractory.

  The residual expansion coefficient was the same as in Examples 4 to 7 and Comparative Examples 5 to 8, and a refractory with dimensions of 5 mm × 5 mm × 10 mm was prepared, and a thermomechanical analyzer (TMA) was used. It is the result of using and measuring at a measurement temperature of 1400 ° C. Moreover, ○ of SL melting loss and ML melting loss indicates a case where the melting amount is 2 mm or less, and × indicates a case where the melting amount is 2 mm or more.

  From Table 4, when compared with Comparative Examples 5-8, the refractories of Examples 4-7 improved the residual expansion coefficient at 1500 ° C. to 0.05% to 0.25%, and Fe—Si—. The crack depth generated after the immersion test in the BP-Cu alloy molten metal is reduced to 15.2 mm to 18.1 mm. Furthermore, no melt damage in SL or molten metal penetration in ML occurs.

  On the other hand, in the refractories of Comparative Examples 5 to 8, the residual expansion coefficient at 1400 ° C. shows a negative value, that is, the residual expansion does not occur and the molten Fe—Si—B—P—Cu alloy is melted. In the refractory after the immersion test, cracks having a depth of 26.9 mm to 30.5 mm are generated. Furthermore, obvious SL melting and ML infiltration have occurred.

  As described above, according to the present invention, it is obvious that the corrosion resistance is remarkably improved. Therefore, by installing the refractory according to the present invention, such as a crucible shape or a cylindrical shape, in accordance with the shape of the melting furnace to be used in the furnace, the generation of slag from the refractory is reduced, and the refractory progresses due to the slag. In addition, it is possible to suppress the mixing of slag into the molten metal, and to prevent mixing of impurities into the product and deterioration of characteristics due to the impurities.

  As described in detail, the present invention can be used for a refractory for melting, holding a molten metal, and refining an iron-based alloy containing an element having high reactivity with a refractory such as P, Si, and B. It can also be used for melting alloys such as iron-based soft magnetic materials, structural materials, and machine part materials containing other elements.

  As mentioned above, although the Example of this invention was described, this invention is not limited above, The change and correction of a structure are possible in the range which does not deviate from the summary of this invention. That is, various changes and modifications that can be made by those skilled in the art are also included in the present invention.

Claims (5)

A refractory material comprising a sintered body containing 90% by mass to 98% by mass of an Al ₂ O ₃ component and 2% by mass to 8% by mass of an MgO component. A refractory material comprising a sintered body containing 92% by mass to 95% by mass of an Al ₂ O ₃ component and 5% by mass to 7% by mass of an MgO component.   The refractory according to claim 2, wherein the residual expansion coefficient is 0.3% or less (excluding 0). And alumina raw material 70% by mass to 90% by mass, by mixing the spinel material 10% by mass or more and 30% or less, _Al 2 _{O 3} component 90 mass% and 98 mass% or more, MgO component 2 wt% or more 8 A step of obtaining a mixture containing less than mass%, a step of filling the mixture into a mold to obtain a molded body, a step of removing the molded body from the mold and drying, and a step of sintering the molded body. A method for producing a refractory, comprising: And alumina raw material 70 mass% or more and 85 mass% or less, by mixing the spinel material 15% by mass or more and 30% or less, _Al 2 _{O 3} and component 92 mass% to 95 mass%, MgO component 5 wt% or more 7 A step of obtaining a mixture containing less than mass%, a step of filling the mixture into a mold to obtain a molded body, a step of removing the molded body from the mold and drying, and a step of sintering the molded body. A method for producing a refractory, comprising: