Monolithic refractory composition for metal casting, method for producing monolithic refractory composition for metal casting, and cured product of monolithic refractory composition for metal casting

Abstract

To provide a monolithic refractory composition for metal casting that is capable of filling a joint part or a crack of a refractory molded body while reducing the content of inorganic fibers, freely shapes itself by itself to dry and solidify, is unlikely to crack when cured by drying or baking, and is capable of forming a cured product having practically adequate bending strength.　The monolithic refractory composition for metal casting is characterized by containing 1.00-15.00 mass% of inorganic fibers, 1.00-13.00 mass% of organic fibers, colloidal silica, an ion-binding substance, and an inorganic filler in the solids fraction.

Description

Unformable refractory composition for metal casting, method for producing unformable refractory composition for metal casting, and cured product of unformable refractory composition for metal casting

[0001] The present invention relates to a castable refractory composition for metal casting that can be suitably used in parts that come into direct contact with molten metal in casting equipment for aluminum, magnesium, etc., and to a cured product of the castable refractory composition for metal casting.

[0002] In casting equipment for non-ferrous metals such as aluminum, insulating walls that are applied with a castable refractory composition and then dried or fired are used as lining materials for constructing molten metal holding components that come into contact with molten metal, such as gutters, molten metal holding furnaces, ladles, etc. In addition to the castable refractory composition, a refractory molded body is also used for the lining material, and in some cases the castable refractory composition is used to fill the joints of the refractory molded body, which is then dried or fired to form an insulating wall.

[0003] As amorphous refractory compositions for metal casting and hardened products obtained by drying or firing amorphous refractory compositions for metal casting, which are used as materials for forming refractory molded bodies for metal casting such as the above-mentioned lining materials and joint materials, there are known, for example, those containing aluminosilicate fibers as inorganic fibers, as disclosed in Patent Document 1.

[0004] JP 2011-093726 A

[0005] The aluminosilicate fiber is an amorphous ceramic fiber also known as refractory ceramic fiber (RCF). It is an artificial mineral fiber made by mixing and blending approximately equal amounts of alumina and silica, melting them in an electric furnace, extracting the mixture as a thin stream, and then blowing it into fibers. Because it has excellent heat resistance and is low cost, it is suitable for use in various components that require fire resistance.

[0006] On the other hand, the above-mentioned aluminosilicate fibers have recently been designated as "controlled class 2 substances" of "specified chemical substances (class 2 substances)" under the Industrial Safety and Health Act, and are now designated as fibers that require appropriate handling.

[0007] For this reason, there is a trend toward demand for monolithic refractory compositions for metal casting and cured products thereof that use a reduced amount of aluminosilicate fibers or that do not use aluminosilicate fibers at all.

[0008] Alumina fibers, known as crystalline ceramic fibers, are considered as inorganic fibers that can replace aluminosilicate fibers. However, alumina fibers are known to be expensive among inorganic fibers, and in order to use them as constituent fibers of monolithic refractory compositions for metal casting and their cured products, it is practically necessary to reduce the amount of alumina fibers used.

[0009] Thus, it has become desirable for unshaped refractory compositions for metal casting and cured products thereof to have a reduced content of inorganic fibers.

[0010] On the other hand, when the amount of inorganic fibers in the amorphous refractory composition for metal casting was reduced, cracks were more likely to occur, especially in curved surfaces, when the amorphous refractory composition for metal casting was applied and dried or fired to form a hardened product.

[0011] Furthermore, it is desirable that the cured product of the monolithic refractory composition for metal casting has sufficient bending strength for use as a refractory molded article for metal casting.

[0012] Therefore, the present invention aims to provide an amorphous refractory composition for metal casting that can be filled into joints and cracks in refractory molded bodies, or can be freely shaped by itself and dried and solidified, while reducing the content of inorganic fibers, and that is less likely to crack when dried or fired and hardened to form a hardened product having sufficient bending strength for practical use, as well as to provide a method for producing the amorphous refractory composition for metal casting and a hardened product of the amorphous refractory composition for metal casting.

[0013] In order to achieve the above-mentioned object, the inventors conducted extensive research and came up with the idea of ​​reducing the amount of inorganic fibers in an amorphous refractory composition for metal casting while increasing the amount of organic fibers in the composition.

[0014] As described above, the monolithic refractory composition for metal casting is applied and dried or fired to form a hardened product (refractory molded body for metal casting). However, when organic fibers are used as the constituent fibers of the monolithic refractory composition for metal casting, these organic fibers are burned away during the firing treatment or when the molten metal is cast, and therefore it has been thought that they are difficult to use as aggregates (reinforcing fibers) for refractory molded bodies for metal casting. For this reason, even when organic fibers are used as the constituent fibers of the monolithic refractory composition for metal casting, they have traditionally been used in the presence of a sufficient amount of inorganic fibers, and it has not been possible to reduce the amount of inorganic fibers used and then use organic fibers in place of inorganic fibers.

[0015] On the other hand, after extensive research, the inventors have discovered that if the amount of inorganic fibers in an amorphous refractory composition for metal casting is reduced while the amount of organic fibers in place of the inorganic fibers is increased, a hardened product (refractory molded body for metal casting) can be formed that is not only less likely to crack when dried or baked and hardened, but also has sufficient bending strength for practical use, and have completed the present invention based on this finding.

[0016] That is, the present invention provides: (1) an amorphous refractory composition for metal casting, characterized in that the solid content contains 1.00 to 15.00 mass% of inorganic fibers, 1.00 to 13.00 mass% of organic fibers, colloidal silica, an ionically bondable substance, and an inorganic filler; (2) the amorphous refractory composition for metal casting according to (1) above, which contains 2.00 to 20.00 mass% of the colloidal silica, calculated as silica, 4.00 to 40.00 mass% of the ionically bondable substance, and 30.0 to 92.00 mass% of the inorganic filler in the solid content; (3) the amorphous refractory composition for metal casting according to (1) above, which contains 2.00 to 28.00 mass% of the inorganic fibers and the organic fibers in total in the solid content; (4) The amorphous refractory composition for metal casting according to (1) above, wherein the ratio of the content of the organic fibers to the content of the inorganic fibers in the solid content is 0.18 to 3.08 by mass; (5) The refractory composition for metal casting according to (1) above, wherein the inorganic fibers are alumina fibers; (6) A method for producing the amorphous refractory composition for metal casting according to (1) above, comprising mixing inorganic fibers, organic fibers, colloidal silica, an ionically bonded substance, and an inorganic filler so that the solid content contains 1.00 to 15.00 mass% of the inorganic fibers and 1.00 to 13.00 mass% of the organic fibers; (7) A cured product of the amorphous refractory composition for metal casting according to any one of (1) to (5) above.

[0017] According to the present invention, an amorphous refractory composition for metal casting is provided which can be filled into joints and cracks in refractory molded bodies, or can be freely shaped by itself and dried and solidified, while reducing the content of inorganic fibers, and which is less likely to crack when dried or fired and hardened to form a hardened product having sufficient bending strength for practical use, and a hardened product of such an amorphous refractory composition for metal casting is also provided.

[0018] First, the monolithic refractory composition for metal casting according to the present invention will be described. The monolithic refractory composition for metal casting according to the present invention is characterized by comprising, based on the solid content, 1.00 to 15.00 mass % of inorganic fibers, 1.00 to 13.00 mass % of organic fibers, colloidal silica, an ionically bondable substance, and an inorganic filler.

[0019] In the amorphous refractory composition for metal casting according to the present invention, the inorganic fibers function as aggregates for the amorphous refractory composition, and examples thereof include one or more fibers selected from glass fibers, glass wool, ceramic wool, rock wool, alumina fibers, zirconia fibers, aluminosilicate fibers, biosoluble inorganic fibers, etc., with alumina fibers being particularly preferred.

[0020] In the monolithic refractory composition for metal casting according to the present invention, the alumina fiber means a metal oxide fiber whose main component is alumina, which is also generally called alumina fiber, and as long as it is mainly composed of alumina, it may contain components such as silica, zirconia, etc. In the monolithic refractory composition for metal casting according to the present invention, the alumina fiber means one having an alumina content of 65% by mass or more, preferably one having an alumina content of 80% by mass or more, and more preferably one having an alumina content of 90% by mass or more.

[0021] When the amorphous refractory composition for metal casting according to the present invention contains alumina fibers as inorganic fibers, the proportion of alumina fibers in the total amount of inorganic fibers in the amorphous refractory composition for metal casting is preferably 10 to 100 mass%, more preferably 50 to 100 mass%, and even more preferably 100 mass% (the inorganic fibers consist only of alumina fibers).

[0022] In the amorphous refractory composition for metal casting of the present invention, the proportion of alumina fibers in the total amount of inorganic fibers satisfies the above-mentioned specification, so that even if the content of inorganic fibers is reduced, cracks are less likely to occur when dried or fired and hardened, and a hardened product (refractory molding for metal casting) with sufficient bending strength can be easily formed.

[0023] The monolithic refractory composition for metal casting according to the present invention may contain aluminosilicate fibers as inorganic fibers, but it is preferable to minimize the content thereof, and it is desirable to not contain aluminosilicate fibers at all.

[0024] In the monolithic refractory composition for metal casting according to the present invention, the biosoluble inorganic fiber refers to an inorganic fiber having a solubility in physiological saline of 1% or more at 40°C. Examples of the biosoluble inorganic fiber include AES fiber (alkaline earth silicate wool fiber), which is an artificial mineral fiber made from high-purity silica, calcia, and magnesia as raw materials, as an inorganic fiber that can replace aluminosilicate fiber. More specific examples of the biosoluble inorganic fiber include inorganic fibers described in JP-A Nos. 2000-220037, 2002-68777, 2003-73926, and 2003-212596, namely, SiO ２ and CaO total content is 85 mass % or more, 0.5 to 3.0 mass % MgO and 2.0 to 8.0 mass % P ２ O ５ and inorganic fibers with a carcinogenicity index (KI value) of 40 or more according to the German Regulation on Hazardous Substances, and SiO ２ , MgO and TiO ２ Inorganic fibers containing SiO ２ , inorganic fibers containing MgO and manganese oxide as essential components, and SiO ２ 52-72% by mass, Al ２ O ３ Less than 3% by mass, MgO 0-7% by mass, CaO 7.5-9.5% by mass, B ２ O ３ 0-12% by mass, BaO 0-4% by mass, SrO 0-3.5% by mass, Na ２ O 10-20.5% by mass, K ２ O 0.5 to 4.0 mass % and P ２ O ５ Inorganic fibers containing 0 to 5% by mass, SiO ２ 75-80% by mass, CaO + MgO 19-25% by mass, Al ２ O ３ The inorganic fibers may be one or more selected from inorganic fibers containing 1 to 3% by mass.

[0025] On the other hand, biosoluble inorganic fibers such as the AES fibers dissolve in the water that constitutes the monolithic refractory composition for metal casting, and tend to harden by reacting with the inorganic binder, which tends to reduce the shelf life of the monolithic refractory composition for metal casting. Therefore, although the monolithic refractory composition for metal casting according to the present invention may contain biosoluble inorganic fibers as inorganic fibers, it is preferable to reduce the content as much as possible, and it is desirable to not contain biosoluble inorganic fibers.

[0026] In the amorphous refractory composition for metal casting according to the present invention, the average fiber diameter of the inorganic fibers is preferably 1.0 to 50.0 μm, more preferably 1.5 to 10.0 μm, and even more preferably 2.0 to 6.0 μm. If the average fiber diameter of the inorganic fibers is less than 1.0 μm, the fibers are prone to breakage, which tends to reduce the strength of the cured product (refractory molded body for metal casting) obtained by drying or firing the amorphous refractory composition for metal casting according to the present invention. If the average fiber diameter exceeds 50.0 μm, the density of the cured product (refractory molded body for metal casting) obtained by drying or firing the amorphous refractory composition for metal casting according to the present invention is reduced, which tends to reduce the strength of the resulting refractory molded body. Furthermore, the average fiber length of the inorganic fibers is preferably 1 to 200 mm, more preferably 2 to 50 mm, and even more preferably 10 to 50 mm. Having the average fiber length of the inorganic fibers within the above range makes it easier to obtain a refractory molded body for metal casting with an appropriate density. In this application, the average fiber diameter of inorganic fibers means the average value when the diameters of 200 fibers are measured in an image observed by an electron microscope, and the average fiber length of inorganic fibers means the average value when the fiber lengths of 200 fibers are measured with a vernier caliper.

[0027] The amorphous refractory composition for metal casting according to the present invention contains inorganic fibers in an amount of 1.00 to 15.00% by mass, preferably 1.00 to 12.00% by mass, and more preferably 1.00 to 10.00% by mass, based on the solid content. By having the inorganic fiber content within the above range, the amorphous refractory composition for metal casting according to the present invention can easily fill the joints and cracks of a refractory molding while reducing the inorganic fiber content, and can be freely shaped and dried and solidified by itself, allowing for the easy formation of a refractory molding for metal casting that has sufficient strength and erosion resistance for practical use, and that is excellent in heat retention (thermal insulation) and light weight.

[0028] Because inorganic fibers are lightweight and have low density, when used as a constituent material for a refractory molded body, the mechanical strength is relatively low and the body is easily corroded by molten metal such as aluminum. However, by using a predetermined amount of inorganic fibers together with an ionic bonding substance and colloidal silica, which will be described later, as a constituent material for a refractory molded body, it is possible to produce a refractory molded body for metal casting that has sufficient strength and erosion resistance for practical use, excellent heat retention (thermal insulation), and reduced weight.

[0029] In the amorphous refractory composition for metal casting according to the present invention, the organic fiber functions as an aggregate for the amorphous refractory composition, and examples thereof include one or more types selected from natural fibers such as pulp, cotton, and hemp, and hydrophobically treated synthetic fibers such as vinylon, rayon, polypropylene (PP), and polyethylene (PE).

[0030] In the amorphous refractory composition for metal casting according to the present invention, the average fiber diameter of the organic fibers is preferably 1.0 to 50.0 μm, more preferably 5.0 to 30.0 μm, and even more preferably 10.0 to 20.0 μm. If the average fiber diameter of the organic fibers is less than 1.0 μm, the fibers are prone to breakage, and cracks are likely to occur in the cured product (refractory molded body for metal casting) obtained by drying or firing the amorphous refractory composition for metal casting according to the present invention. If the average fiber diameter of the organic fibers exceeds 50.0 μm, the density of the cured product (refractory molded body for metal casting) obtained by drying or firing the amorphous refractory composition for metal casting according to the present invention is low, and the strength is likely to be low.

[0031] Furthermore, in the monolithic refractory composition for metal casting according to the present invention, the average fiber length of the organic fibers is preferably 1 to 30 mm, more preferably 1 to 20 mm, and even more preferably 2 to 13 mm. If the average fiber length of the organic fibers is less than 1 mm, the monolithic refractory composition for metal casting according to the present invention will be less likely to exhibit pullout resistance between the organic fibers and the base material during drying or at the beginning of the firing treatment, making it more likely to crack. On the other hand, if the average fiber length of the organic fibers exceeds 30 mm, the density of the cured product (refractory molded product for metal casting) obtained by drying or firing will be low, making it more likely to have a reduced bending strength.

[0032] In this application, the average fiber diameter of the organic fibers means the average value when the diameters of 200 fibers are measured in an image observed by an electron microscope, and the average fiber length of the organic fibers means the average value when the fiber lengths of 200 fibers are measured with a vernier caliper.

[0033] The amorphous refractory composition for metal casting according to the present invention contains organic fibers in an amount of 1.00 to 13.00% by mass, preferably 1.00 to 12.00% by mass, and more preferably 1.00 to 10.00% by mass, based on the solid content. By having the organic fiber content within the above range, the amorphous refractory composition for metal casting according to the present invention can be used to fill joints and cracks in refractory molded bodies, or to freely shape the composition itself and dry and solidify, while reducing the inorganic fiber content. This makes it easier to form cracks in the cured product (refractory molded body for metal casting) obtained by drying or firing. Depending on the heating temperature during firing, the organic fibers may completely disappear after the firing treatment, and not remain in the resulting cured product. However, if cracks do not occur during drying or in the early stages of firing, cracks can be easily suppressed even after firing is complete.

[0034] The amorphous refractory composition for metal casting according to the present invention contains the inorganic fibers and organic fibers in a total amount of 2.00 to 28.00 mass%, preferably 2.00 to 25.00 mass%, and more preferably 8.00 to 11.00 mass%, in the solid content.

[0035] Since the amorphous refractory composition for metal casting according to the present invention contains the above-mentioned inorganic fibers and organic fibers in total in the above-mentioned proportions in the solid content, the content of inorganic fibers can be reduced while the cured product obtained by drying or firing is more likely to have a dense structure, making it easy to produce a cured product (refractory molded body for metal casting) with sufficient bending strength.

[0036] In the amorphous refractory composition for metal casting according to the present invention, the ratio of the content of organic fibers in the solid content to the content of inorganic fibers in the solid content (content of organic fibers in the solid content / content of inorganic fibers in the solid content) is preferably 0.18 to 3.08, more preferably 0.20 to 2.99, even more preferably 0.25 to 2.50, and particularly preferably 0.30 to 2.00, by mass.

[0037] The amorphous refractory composition for metal casting of the present invention contains the above-mentioned inorganic fibers and organic fibers in the solid content in a ratio that satisfies the above-mentioned ratio, so that it is possible to easily produce a hardened product (refractory molded body for metal casting) that is less likely to crack and has sufficient bending strength when dried or fired and hardened, while reducing the inorganic fiber content.

[0038] In the amorphous refractory composition for metal casting according to the present invention, the colloidal silica is preferably silica particles or their hydrates dispersed in a colloidal state in water, with a median diameter (D50) of less than 0.10 μm and a 90% cumulative diameter (D90) of less than 0.20 μm, and more preferably a median diameter (D50) of 0.01 μm or more but less than 0.1 μm and a 90% cumulative diameter (D90) of 0.02 μm or more but less than 0.20 μm.

[0039] In the monolithic refractory composition for metal casting according to the present invention, the colloidal silica imparts sufficient shape retention and strength to the cured product obtained by drying or firing the monolithic refractory composition for metal casting according to the present invention, and after curing, it functions to bind inorganic fibers together and, as an oxygen source for the molten metal, to form an oxide film of the molten metal (when the metal is aluminum, an aluminum oxide film) at the interface where the cured product comes into contact with the molten metal. If the median diameter (D50) of the colloidal silica is less than 0.10 μm and the 90% cumulative diameter (D90) is less than 0.2 μm, the surface area of ​​the silica increases after curing, facilitating the rapid oxidation-reduction reaction between the highly reducing molten metal and the silica, and facilitating the rapid formation of an oxide film on the surface of the refractory. On the other hand, if the median diameter (D50) of the colloidal silica is 0.10 μm or more or the 90% cumulative diameter (D90) is 0.20 μm or more, it becomes difficult to form an oxide film quickly, and metals tend to stick to the surface of the resulting cured product.

[0040] The monolithic refractory composition for metal casting according to the present invention can be formed into any shape and then dried or fired to form a cured product (refractory molded body for metal casting). Since the cured product is made of a material containing silica and a predetermined amount of a highly ionic-bonding substance described below, the oxidation-reduction reaction between the molten metal, which has a high reducing power, and silica, which serves as an oxygen source for the molten metal, can proceed quickly, allowing a metal oxide film to be rapidly formed on the surface of the cured product. As a result, the metal oxide is formed on the surface of the cured product before the molten metal penetrates, which prevents the metal from adhering to the cured product and also prevents the molten metal from penetrating the cured product. Furthermore, since the metal oxide itself is easily peeled off, damage to the cured product can be prevented.

[0041] In the monolithic refractory composition for metal casting according to the present invention, the median diameter (D50) refers to the diameter of particles that account for 50% of the particle size distribution when calculated from the finest particles, and the 90% cumulative diameter (D90) refers to the diameter of particles that account for 90% of the particle size distribution when calculated from the finest particles. The particle size distribution of the colloidal silica can be determined by a laser diffraction / scattering method using a nanoparticle size distribution measuring device SALD-7100 (measurement range: 0.01 to 300 μm) (manufactured by Shimadzu Corporation) to calculate the particle size distribution (particle size) from the intensity distribution of light scattered from the particles.

[0042] The amorphous refractory composition for metal casting according to the present invention preferably contains 2.00 to 20.00 mass % of colloidal silica, calculated as silica, in the solid content, more preferably 2.00 to 15.00 mass %, and even more preferably 2.00 to 10.00 mass %.

[0043] Colloidal silica is a colloidal substance in which silica particles or their hydrates are dispersed in water. In the amorphous refractory composition for metal casting according to the present invention, the content of the colloidal silica means the mass proportion, converted into silica, of the total solid content of the amorphous refractory composition for metal casting according to the present invention.

[0044] If the content of colloidal silica in the solids is less than 2.00 mass % in terms of silica, the bending strength after curing tends to be insufficient, whereas if the content of colloidal silica in the solids is more than 20.00 mass % in terms of silica, the consistency becomes high, causing the paste-like composition to drip during application and causing significant shrinkage of the applied product, such as joints, due to drying.

[0045] In the monolithic refractory composition for metal casting according to the present invention, the ionic bonding substance may be one or more selected from calcium fluoride, magnesium fluoride, calcium oxide or its precursor, magnesium oxide or its precursor, barium oxide or its precursor, and barium sulfate. Of the above ionic bonding substances, calcium fluoride is preferred because it has the strongest ionic bonding property.

[0046] An example of a calcium oxide precursor is calcium carbonate. An example of a magnesium oxide precursor is magnesium carbonate. An example of a barium oxide precursor is barium carbonate. These precursors are easily decomposed by heating, and therefore, after firing, they are present as calcium oxide, magnesium oxide, and barium oxide, respectively, in the refractory molded body for metal casting.

[0047] The ionic bonding substance has ionic bonding strength equal to or greater than that of an oxide of the molten metal with which it comes into contact, such as aluminum oxide, and is used for the purpose of forming an oxide film of the molten metal at the interface where the molten metal comes into contact with the cured or fired product of the monolithic refractory composition for metal casting according to the present invention. The stronger the ionic bonding strength of the ionic bonding substance, the greater the oxide film-forming effect, so even if the content of the ionic bonding substance in the mixture is small, a sufficient oxide film-forming effect can be achieved.

[0048] In the amorphous refractory composition for metal casting according to the present invention, the ionic bonding substance preferably has a small particle size. Specifically, the average particle size (median diameter (D50)) is preferably 0.15 mm or less, more preferably 0.10 mm or less, and even more preferably 0.050 mm or less. The average particle size (median diameter (D50)) is preferably 0.001 mm or more. When an ionic bonding substance with a small particle size is used, the specific surface area of ​​the ionic bonding substance as a whole can be increased, and therefore an oxide film with suitable release properties can be rapidly formed on the surface of a cured product of the amorphous refractory composition for metal casting according to the present invention.

[0049] In the present invention, the average particle size (median diameter (D50)) of the ionically bonded substance means a value measured by a laser diffraction / scattering method using a nanoparticle size distribution measuring device SALD-7100 (measurement range: 0.01 to 300 μm) (manufactured by Shimadzu Corporation).

[0050] The ion-binding substance to be used preferably has a purity of 90% or more, and more preferably has a purity of 99% or more.

[0051] The amorphous refractory composition for metal casting according to the present invention preferably contains 4.00 to 40.00 mass % of an ionic bonding substance in the solid content, more preferably 5.00 to 25.00 mass %, and even more preferably 5.00 to 20.00 mass %.

[0052] In the monolithic refractory composition for metal casting according to the present invention, if the content of the ionic bonding substance in the solid content is less than 4.00% by mass, it becomes difficult to rapidly form an oxide film of the molten metal at the interface where the cured product of the monolithic refractory composition for metal casting contacts the molten metal. Furthermore, if the content of the ionic bonding substance in the solid content exceeds 40.00% by mass, materials with strong ionic bonding properties generally exhibit large volume expansion upon heating, resulting in reduced thermal shock resistance and making the cured product more susceptible to cracking due to thermal shock. By including a specific ratio of the ionic bonding substance and colloidal silica in the monolithic refractory composition for metal casting according to the present invention, it is possible to rapidly form an oxide film of the molten metal at the interface where the resulting cured product contacts the molten metal. Since this oxide is formed on the surface of the cured product before penetration of the molten metal occurs, it is possible to suppress adhesion of the metal to the cured product and suppress penetration of the molten metal into the cured product. Furthermore, since the metal oxide itself is easily peeled off, damage to the cured product can be easily suppressed.

[0053] The amorphous refractory composition for metal casting according to the present invention preferably contains inorganic fibers, organic fibers, colloidal silica and ion-bonding substances in a total amount of 20.00 mass% or more of the total solids, more preferably 25.00 mass% or more of the total solids, and even more preferably 30.00 mass% or more of the total solids.

[0054] In the monolithic refractory composition for metal casting according to the present invention, the inorganic filler is added as an aggregate and may be in the form of particles or needle-like crystals. Note that in this application, the inorganic filler does not include the inorganic fibers or ionic bonding substances mentioned above.

[0055] The inorganic filler may be one or more selected from particulate inorganic fillers (particulate materials) or acicular inorganic fillers (acicular materials). Examples of the particulate inorganic fillers (particulate materials) include one or more selected from silica particles, alumina particles, chamotte particles, titania particles, zirconia particles, silicon nitride particles, silicon carbide particles, cordierite particles, etc. Examples of the acicular inorganic fillers (acicular materials) include one or more selected from wollastonite, sepiolite, attapulgite, potassium titanate fibers, calcium carbonate fibers, calcium silicate fibers, microfiber cellulose, fibrillated aramid, gypsum, hydromagnesite, etc. As the inorganic filler, acicular inorganic fillers (acicular materials) are preferred, as described below, with wollastonite being more preferred.

[0056] The amorphous refractory composition for metal casting according to the present invention preferably contains 30.00 to 92.00 mass % of inorganic filler in the solid content, more preferably 40.00 to 90.00 mass %, and even more preferably 50.00 to 80.00 mass %.

[0057] The amorphous refractory composition for metal casting according to the present invention contains an inorganic filler in the solid content in the above-mentioned range, which results in a dense structure when dried or fired and hardened, thereby preventing sticking due to penetration of molten metal on the surface of the resulting hardened product (refractory molding for metal casting).

[0058] The monolithic refractory composition for metal casting according to the present invention preferably contains a needle-shaped inorganic filler (needle-shaped materials) such as wollastonite as an inorganic filler. When the monolithic refractory composition for metal casting according to the present invention contains needle-shaped materials as an inorganic filler, the solid content of the monolithic refractory composition for metal casting according to the present invention is preferably 5.00 to 60.00 mass%, more preferably 5.00 to 50.00 mass%, and even more preferably 10.00 to 45.00 mass% of the needle-shaped materials.

[0059] The monolithic refractory composition for metal casting according to the present invention is usually in the form of a paste containing a desired amount of a liquid medium such as water, and further has a reduced content of inorganic fibers, so that it adheres to the hands of workers or construction tools during application and is difficult to peel off, which tends to reduce workability and handleability. On the other hand, since the monolithic refractory composition for metal casting according to the present invention contains acicular materials such as wollastonite as at least a part of the inorganic filler in the above proportions, it is difficult to adhere to the hands of workers or construction tools during application, and once adhered, the monolithic refractory composition for metal casting is easily peeled off, which easily improves workability and handleability.

[0060] The amorphous refractory composition for metal casting according to the present invention preferably contains inorganic fibers, organic fibers, colloidal silica, ion-bonding substances and inorganic fillers in a total amount of 96.0 mass% or more of the total solids, more preferably 97.0 mass% or more of the total solids, and even more preferably 98.0 mass% or more of the total solids.

[0061] The unshaped refractory composition for metal casting according to the present invention preferably contains a thickener. The thickener in the unshaped refractory composition for metal casting according to the present invention is not particularly limited and can be appropriately selected from those commonly used in this technical field, for example, one or more selected from hydroxyethyl cellulose, sodium acrylate polymer, etc.

[0062] The amorphous refractory composition for metal casting according to the present invention preferably contains 0.01 to 3.00 mass % of a thickener in the solid content, more preferably 0.01 to 2.00 mass %, and even more preferably 0.01 to 1.00 mass %.

[0063] Since the amorphous refractory composition for metal casting of the present invention contains the thickener in the above-mentioned proportion in the solid content, the consistency of the amorphous refractory composition for metal casting of the present invention can be easily controlled within the desired range.

[0064] The amorphous refractory composition for metal casting according to the present invention preferably contains inorganic fibers, organic fibers, colloidal silica, ion-bonding substances, inorganic fillers and thickeners in a total amount of 97.0 mass% or more of the total solids, more preferably 98.0 mass% or more of the total solids, and even more preferably 99.0 mass% or more of the total solids.

[0065] The monolithic refractory composition for metal casting according to the present invention may contain, in addition to the above-mentioned components, optional components such as a coating layer forming agent, a dispersant, and a preservative.

[0066] The amorphous refractory composition for metal casting according to the present invention may have any shape, and may be, for example, a paste-like composition obtained by mixing a solid component with a liquid medium.

[0067] The liquid medium for forming the paste-like substance is not particularly limited, but may be one or more selected from water and polar organic solvents. Examples of polar organic solvents include monohydric alcohols such as ethanol and propanol, and dihydric alcohols such as ethylene glycol. Among these liquid media, water is preferred in consideration of the working environment and environmental load. The water is also not particularly limited, and may be one or more selected from distilled water, ion-exchanged water, tap water, groundwater, industrial water, etc.

[0068] When the amorphous refractory composition for metal casting according to the present invention is in a paste form, the viscosity of the paste, i.e., the solids concentration in the liquid medium, is appropriately determined taking into account the intended use and workability. For example, the content of the liquid medium is preferably 20 to 800% by mass, more preferably 25 to 500% by mass, and even more preferably 30 to 250% by mass, relative to 100% by mass of the solids of the amorphous refractory composition for metal casting according to the present invention. If the content of the liquid medium is less than 20% by mass relative to 100% by mass of the solids of the amorphous refractory composition for metal casting according to the present invention, the fluidity of the amorphous refractory composition will be reduced, resulting in poor application properties and a decrease in the mechanical strength, particularly bending strength, of the applied product. Furthermore, if the content of the liquid medium exceeds 800% by mass relative to 100% by mass of the solids of the amorphous refractory composition for metal casting according to the present invention, the consistency of the amorphous refractory composition will be high, resulting in sagging of the paste-like composition during application and significant shrinkage of the applied product, such as joints, due to drying. In addition, when calculating the solid content and liquid medium content of the above-mentioned amorphous refractory composition for metal casting, for the colloidal silica used as a constituent component of the amorphous refractory composition for metal casting, the silicon content in the colloidal silica is converted into silica and added to the above-mentioned solid content, and the liquid content (moisture) in the colloidal silica is added to the above-mentioned liquid medium content, and then the respective amounts are calculated.

[0069] The consistency of the monolithic refractory composition for metal casting according to the present invention is preferably 100 to 400 (1 / 10 mm), more preferably 100 to 350 (1 / 10 mm).

[0070] If the consistency is less than 100 (1 / 10 mm), the flexibility of the monolithic refractory composition for metal casting will decrease, resulting in poor workability, while if the consistency is more than 400 (1 / 10 mm), the paste-like composition will tend to drip during application, and shrinkage of the applied product, such as joints, due to drying will be large.

[0071] In this application, the term "penetration" refers to the worked penetration measured in accordance with JIS K 2220. Specifically, the penetration refers to the depth (mm) to which the tip of a standard cone attached to a penetration meter sinks into a test sample (a monolithic refractory composition for metal casting) at 25°C, measured by a specified method, for 5 seconds. This is the depth (mm) to which the tip of the standard cone sinks into the test sample, i.e., the penetration, measured by measuring the depth (mm) of the standard cone. However, in measuring the penetration, a 150 g weight is placed on the standard cone, taking into consideration the difficulty of the standard cone penetrating into the test sample.

[0072] The consistency of the monolithic refractory composition for metal casting according to the present invention can be adjusted and controlled by the amount of liquid excluding solids contained in the monolithic refractory composition for metal casting according to the present invention (for example, the amount of water contained in colloidal silica or other liquid medium) and the amount of inorganic fiber. Specifically, increasing the amount of the solvent or decreasing the amount of inorganic fiber increases the consistency, while decreasing the amount of the solvent or increasing the amount of inorganic fiber decreases the consistency.

[0073] The amorphous refractory composition for metal casting according to the present invention can be used, for example, as a lining material and joint material for components that come into contact with molten metal, such as gutters, molten metal holding furnaces, and ladles, and can be dried or fired to form a hardened product having any shape.

[0074] The method for producing the monolithic refractory composition for metal casting according to the present invention will now be described. The monolithic refractory composition for metal casting according to the present invention can be produced by mixing the inorganic fibers, organic fibers, colloidal silica, ion-bonding substance, and inorganic filler, and, if necessary, further constituent materials such as a thickener, in desired amounts, calculated as solids.

[0075] A preferred method for producing the monolithic refractory composition for metal casting according to the present invention is to mix inorganic fibers, organic fibers, an ion-bonding substance, an inorganic filler, and other aggregates as needed, then add colloidal silica, and then add and mix other ingredients such as a thickener and, if desired, a preservative. When a liquid medium is used, a preferred method is to add inorganic fibers and organic fibers to the liquid medium, then add and mix colloidal silica and an ion-bonding substance, and then add and mix other ingredients such as an inorganic filler, a thickener, and, if desired, a preservative.

[0076] The amorphous refractory composition for metal casting of the present invention reduces the content of inorganic fibers while increasing the content of organic fibers, and further contains colloidal silica, an ionically bonding substance, an inorganic filler, and a thickener, so that when dried or fired and hardened, it forms a hardened product that is less likely to crack and has sufficient bending strength, and can be suitably used as a refractory molding for metal casting.

[0077] Next, the cured product of the monolithic refractory composition for metal casting according to the present invention will be described. The cured product of the monolithic refractory composition for metal casting according to the present invention is characterized by comprising a cured product of the refractory composition for metal casting according to the present invention.

[0078] The details of the monolithic refractory composition for metal casting, which is a constituent material of the cured product according to the present invention, are as described above.

[0079] The cured product of the present invention can be easily formed by drying or firing the monolithic refractory composition for metal casting of the present invention.

[0080] The method for producing the cured product of the present invention includes applying or molding the monolithic refractory composition for metal casting of the present invention by the method described above, followed by drying or firing. The method for producing the cured product of the present invention is preferably applying or molding the monolithic refractory composition for metal casting of the present invention by the method described above, followed by drying and then firing.

[0081] When producing the cured product according to the present invention, the drying temperature is preferably room temperature to 180°C, more preferably 40 to 180°C, even more preferably 60 to 150°C, and particularly preferably 80 to 120°C. The drying time is preferably 6 to 48 hours, more preferably 8 to 40 hours, and even more preferably 10 to 36 hours. The drying atmosphere can be an air atmosphere, an oxygen atmosphere, a nitrogen atmosphere, or the like.

[0082] When producing the cured product according to the present invention, the baking temperature (baking temperature) is preferably 600 to 1300°C, and more preferably 700 to 900°C. The atmosphere during the baking is not particularly limited, but is preferably an air atmosphere, an oxygen atmosphere, or a nitrogen atmosphere. The baking time is preferably 0.5 to 4 hours. By carrying out the baking treatment, the resulting cured product can be degreased and shrinkage during actual use can be easily prevented.

[0083] A method for producing the cured product of the present invention may involve applying or molding the amorphous refractory composition for metal casting of the present invention using the method described above, drying it, and then using the resulting dried product for metal casting purposes (such as by contacting it with molten metal) and hardening it by subjecting it to a substantial firing treatment.

[0084] The amorphous refractory composition for metal casting and its hardened product according to the present invention can be used in areas that come into direct contact with molten metal in casting equipment for aluminum, zinc, magnesium, etc., and although there are no particular limitations on the metal, examples include aluminum casting and zinc casting.

[0085] According to the present invention, it is possible to provide a cured product of a monolithic refractory composition for metal casting that is resistant to cracking and has sufficient bending strength while reducing the content of inorganic fibers.

[0086] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following examples and comparative examples, the following physical properties were measured by the following methods. <Average particle size (median diameter (D50)) and 90% cumulative diameter (D90) of colloidal silica, and average particle size (median diameter (D50)) of calcium fluoride> Each was measured by a laser diffraction / scattering method using a nanoparticle size distribution measurement device SALD-7100 (measurement range: 0.01 to 300 μm) (manufactured by Shimadzu Corporation). <Consistency> Measured in accordance with the provisions of JIS K 2220. However, considering that a standard cone would be difficult to penetrate into the measurement sample, a 150 g weight was placed on the standard cone for measurement. In the following examples and comparative examples, the paste-like amorphous refractory composition was prepared by kneading a mixture of the respective components with water using a kneading device such as a kneader or pressure kneader.

[0087] (Example 1) As shown in Table 1, the components were mixed to contain 4.34 mass% of alumina fiber (Arsen B97 manufactured by Denka Co., Ltd.), 2.17 mass% of polypropylene fiber, 6.50 mass% of colloidal silica having an average particle size (median diameter (D50)) of 0.02 μm and a 90% cumulative diameter (D90) of 0.04 μm, calculated as silica, 18.9 mass% of calcium fluoride (average particle size (median diameter (D50)) 45 μm), 42.7 mass% of alumina powder, 24.31 mass% of wollastonite, 0.64 mass% of a thickener, and 0.43 mass% of a preservative. 29.34 mass parts of water were added to 100 mass parts of the solid content of the resulting mixture of the components, and the mixture was kneaded in a kneading device to prepare a paste-like amorphous refractory composition. Since the mixture of components before the kneading contained 15.17 parts by mass of water constituting colloidal silica per 100 parts by mass of the solid content of the mixture of components, the kneading treatment was equivalent to kneading 44.51 parts by mass of water (15.17 parts by mass + 29.34 parts by mass) per 100 parts by mass of the solid content of the mixture of components. The consistency of the monolithic refractory composition obtained immediately after the kneading was 310 (1 / 10 mm).

[0088] The obtained paste-like amorphous refractory composition was filled into a mold, dried at 100°C for 24 hours, and then demolded to obtain a dried body (cured product). The dried body was fired in a heating furnace under an air atmosphere at 700°C for 3 hours to obtain a fired body (cured product). This fired body had a bulk density of 1.28 g / cm. ３ The bending strength measured in accordance with the standard of JIS R 2553 was 4.82 MPa.

[0089] The obtained paste-like unshaped refractory compositions were evaluated by the following test methods. The results are shown in Table 1.

[0090] <Drying Cracking Test> The presence or absence of cracks in the obtained paste-like amorphous refractory composition when it dried at the bent portion and cured was evaluated. First, an L-shaped iron plate having a horizontal portion 200 mm wide and 200 mm long and a vertical portion 200 mm wide and 200 mm long was coated with the paste-like amorphous refractory composition to a thickness of 10 mm on the inner surface of the horizontal portion and the vertical portion, and then air-dried and cured for 5 days. The surface of the obtained cured product was visually inspected and evaluated as follows: ∘: No cracks were observed on the surface of the obtained cured product. Δ: Cracks were observed on the surface of the obtained cured product, and the arithmetic mean value of the crack widths measured at 10 random locations with a vernier caliper was 0.1 mm or more and less than 2.0 mm. ×: Cracks were observed on the surface of the obtained cured product, and the arithmetic mean value of the crack widths measured at 10 random locations with a vernier caliper was 2.0 mm or more.

[0091] <Moldability Test> The moldability of the obtained paste-like amorphous refractory composition was evaluated by the following methods (1) to (5). (1) The obtained paste-like amorphous refractory composition was measured out to the level in a 90 ml container. (2) The paste-like amorphous refractory composition measured out in (1) was molded into a sphere and placed in the center of a stainless steel plate measuring 300 mm in length, 300 mm in width, and 3 mm in thickness. (3) A stainless steel plate of the same size as the above stainless steel plate was placed on top of the paste-like amorphous refractory composition placed in (2) above, with the upper and lower stainless steel plates overlapping each other, thereby sandwiching the paste-like amorphous refractory composition. (4) The stack of two stainless steel plates sandwiching the paste-like amorphous refractory composition obtained in (3) above is roll-pressed once using a roll press under the conditions of a roll diameter of 180 mm, a roll pressure of 0.01 MPa, a roll rotation speed of 30 rpm, and a gap between the upper and lower rolls of 13 mm. (5) After the roll pressing in (4), the upper stainless steel plate constituting the stack of two stainless steel plates is removed, and the area of ​​the main surface of the amorphous refractory composition formed into a flat plate on the lower stainless steel plate is calculated by image analysis. At this time, the formability is evaluated as follows based on the calculated area value of the main surface. ◯: Area is 120 cm ２ Super △: Area is 80cm ２ 120cm or more ２ Below: ×: Area is 80 cm ２ less than

[0092] <Storage test> The obtained paste-like amorphous refractory composition was evaluated for a decrease in consistency when stored for a long period of time. First, the obtained paste-like amorphous refractory composition was stored in a cool, dark place for 6 months after production, and the consistency after 6 months was confirmed and evaluated as follows. ◯: The consistency of the paste-like amorphous refractory composition after 6 months is 50% or more of the consistency of the paste-like amorphous refractory composition immediately after production. ×: The consistency of the paste-like amorphous refractory composition after 6 months is less than 50% of the consistency of the paste-like amorphous refractory composition immediately after production.

[0093] <Applicability Test (Hand-Releasability (Hand-Adhesion) of Monolithic Fireproof Moldings)> The applicability (hand-releasability (Hand-Adhesion) of the obtained paste-like amorphous fireproof composition when used for application) was evaluated. First, one hand, wearing a glove made of natural rubber latex, was placed vertically into a container containing the obtained paste-like amorphous fireproof composition, with the hand open, and the hand was left in that position for 3 seconds. Next, the hand placed in the container was pulled vertically upward, and the state of the glove after pulling up was visually confirmed and rated as follows: ∘: The paste-like amorphous fireproof composition adhered to the entire glove as a powdery substance and was easily removed by shaking the hand. Δ: The paste-like amorphous fireproof composition adhered to the entire glove as a powdery substance and to parts between the fingers of the glove as a sticky substance, and the powdery substance was easily removed by shaking the hand, but the sticky substance was hardly removed. ×: The paste-like amorphous fireproof composition adhered to the entire glove as a sticky substance and was hardly removed by shaking the hand.

[0094] <Molten Aluminum Immersion Test (Molten Aluminum Properties)> A rectangular columnar test specimen was formed from the obtained paste-like castable refractory composition, immersed in molten aluminum, and then removed. Whether or not the aluminum adhered to the test specimen was evaluated. First, the obtained paste-like castable refractory composition was molded into a rectangular columnar shape measuring 200 mm in length, 40 mm in width, and 40 mm in height. The dried specimen was then processed to a rectangular columnar shape measuring 160 mm in length, 40 mm in width, and 40 mm in height. Next, aluminum was placed in a crucible-shaped electric furnace and heated to 700°C to melt the aluminum. The rectangular columnar test specimen was immersed in the molten aluminum. The electric furnace was maintained at 700°C while the rectangular columnar test specimen was immersed in the molten aluminum. The electric furnace was maintained at 700°C. The test specimen was removed 24 hours after the start of immersion. The removed specimen was cooled at room temperature and visually inspected for the following evaluation. ◯: No aluminum adhesion was observed on the test piece. ×: Aluminum adhesion was observed on the test piece.

[0095] (Examples 2 to 32, Comparative Examples 1 to 3) Paste-like amorphous refractory compositions and their dried (cured) and fired (cured) products were produced in the same manner as in Example 1, except that the blending ratios of the components were changed as shown in Tables 1 to 4, and evaluated in the same manner as in Example 1. The results are shown in Tables 1 to 4.

[0096] Reference Example 1 As shown in Table 5, aluminosilicate fibers (refractory ceramic fibers (RCF)) were used instead of alumina fibers, and the blending ratios of the components were changed as shown in Tables 1 to 4. Except for this, paste-like amorphous refractory compositions and their dried (cured) and fired (cured) products were produced in the same manner as in Example 1, and evaluated in the same manner as in Example 1. The results are shown in Table 5.

[0097]

[0098]

[0099]

[0100]

[0101]

[0102] Tables 1 to 4 show that the amorphous refractory compositions obtained in Examples 1 to 32 contain, in the solids, 1.00 to 15.00% by mass of inorganic fibers, 1.00 to 13.00% by mass of organic fibers, colloidal silica, an ionically bonded substance, and an inorganic filler. Therefore, when dried and cured, they are less likely to crack, and the dried product obtained by firing has sufficient bending strength for practical use. Furthermore, Tables 1 to 4 show that the amorphous refractory compositions obtained in Examples 1 to 32 have excellent moldability, and can be used to fill the joints and cracks of refractory molded bodies, or can be freely shaped and dried to solidify. Therefore, the amorphous refractory compositions obtained in Examples 1 to 32 can be suitably used as amorphous refractory compositions for metal casting, similar to the amorphous refractory molded body containing aluminosilicate fibers (refractory ceramic fiber (RCF)) obtained in Reference Example 1.

[0103] On the other hand, Tables 1 and 2 show that the amorphous refractory compositions obtained in Comparative Examples 1 to 3 have inorganic or organic fiber content ratios outside the specified range in the solid content, and therefore produce large cracks when dried and hardened (Comparative Example 1, Comparative Example 3), and the moldability and bending strength of the dried product obtained by firing are poor (Comparative Example 2).

[0104] According to the present invention, an amorphous refractory composition for metal casting is provided which can be filled into joints and cracks in refractory molded bodies, or can be freely shaped by itself and dried and solidified, while reducing the content of inorganic fibers, and which is less likely to crack when dried or fired and hardened to form a hardened product having sufficient bending strength for practical use, and a hardened product of such an amorphous refractory composition for metal casting is also provided.

Claims

1. An amorphous refractory composition for metal casting, comprising, in its solid content, 1.00 to 15.00 mass% inorganic fibers, 1.00 to 13.00 mass% organic fibers, colloidal silica, an ion-bonding substance, and an inorganic filler.

2. An amorphous refractory composition for metal casting as described in claim 1, containing, in solid content, 2.00 to 20.00 mass% of the colloidal silica, 4.00 to 40.00 mass% of the ion-bonding substance, and 30.00 to 92.00 mass% of the inorganic filler, calculated as silica.

3. An amorphous refractory composition for metal casting as described in claim 1, comprising a total of 2.00 to 28.00 mass% of said inorganic fibers and said organic fibers in the solid content.

4. An amorphous refractory composition for metal casting as described in claim 1, wherein the ratio of the content of the organic fibers to the content of the inorganic fibers in the solid content is 0.18 to 3.08 by mass.

5. The refractory composition for metal casting according to claim 1, wherein said inorganic fibers are alumina fibers.

6. A method for producing the amorphous refractory composition for metal casting described in claim 1, characterized in that inorganic fibers, organic fibers, colloidal silica, an ionically binding substance and an inorganic filler are mixed so that the solid content contains 1.00 to 15.00 mass% of the inorganic fibers and 1.00 to 13.00 mass% of the organic fibers.

7. A cured product of a moldable refractory composition for metal casting, comprising a cured product of the refractory composition for metal casting according to any one of claims 1 to 5.

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