JP6678871B2 - Refractory fiber powder, refractory forming composition and refractory - Google Patents

Description

  The present invention relates to a refractory fiber powder, a composition for forming a refractory, and a refractory.

  Conventionally, refractories such as castable refractories have been used, for example, to protect the furnace shell from high temperatures and to shut off heat inside the furnace. This type of refractory is generally produced by molding and firing a refractory-forming composition comprising water, refractory powder such as alumina powder, and additives such as alumina cement and ceramic fiber.

  Prior Patent Literature 1 discloses a castable refractory obtained by molding and firing a refractory-forming composition comprising water, alumina-lime clinker, alumina fine powder, and alumina cement. . In addition, the document describes that ceramic fibers can be further compounded in the composition for forming a refractory.

JP 2012-72014 A

However, the prior art has problems in the following points. That is, the composition for forming a refractory using alumina powder as an aggregate tends to increase in viscosity. In addition, a refractory obtained by molding and firing a composition for forming a refractory using alumina powder as an aggregate has a large linear shrinkage during firing and lacks volume stability. Further, the refractory, although it is possible to ensure a required strength by shrink come clamping, since the hollow space is reduced, the bulk density tends to increase.

  As a method of reducing the bulk density of the refractory, it is conceivable to add a predetermined additive to the composition for forming a refractory. For example, the above-mentioned ceramic fiber usually has a cotton-like form in which long fibers of about several hundred μm are entangled with each other. Therefore, in the refractory obtained by molding and firing the refractory-forming composition to which the ceramic fibers are added, the voids formed between the cotton-like ceramic fibers are maintained, and the bulk density can be reduced.

  However, when the amount of the ceramic fiber added is large, the viscosity of the composition for forming a refractory increases, and casting cannot be performed. Therefore, the amount of ceramic fibers that can be added to the composition for forming a refractory is usually limited to about 10 to 25 parts by mass with respect to 100 parts by mass of water. Therefore, it is difficult to use a large amount of ceramic fiber as an aggregate to obtain a refractory having a low bulk density and sufficient strength.

  The present invention has been made in view of the above background, and uses a ceramic fiber, has a small linear shrinkage rate at the time of firing, has a low bulk density, and has a refractory capable of securing strength, and has a fluidity that can be cast and molded. An object of the present invention is to provide a refractory forming composition and a refractory fiber powder suitable for obtaining the composition.

One embodiment of the present invention is a refractory fiber powder for castable refractories, refractory mortar, sprayed refractories, or troweled refractories,
It is composed of ceramic fiber powder containing Al ₂ O ₃ and SiO ₂ in chemical composition,
The refractory fiber powder has an average fiber diameter of 4 μm or more and 7 μm or less and an average fiber length of 10 μm or more and 35 μm or less.

Another embodiment of the present invention is a castable refractory, a refractory mortar, a sprayed refractory, or a refractory forming composition used for forming a refractory comprising a troweled refractory,
A refractory-forming composition comprising water, the refractory fiber powder, alumina cement and / or hydraulic alumina.

  Still another embodiment of the present invention resides in a refractory formed using the composition for forming a refractory.

The refractory fiber powder is composed of ceramic fiber powder containing Al ₂ O ₃ and SiO ₂ in a chemical composition, and has an average fiber diameter and an average fiber length within a specific range. Therefore, the refractory fiber powder uses a cotton-like ceramic fiber having a fiber length of about several hundred μm, even when a large amount is added to water as an aggregate when preparing the composition for forming a refractory. As compared with the case, the increase in the viscosity of the composition for forming a refractory can be suppressed. Therefore, the composition for forming a refractory containing the refractory fiber powder has a fluidity that allows casting. Further, according to the composition for forming a refractory, it is possible to obtain the refractory which has a small linear shrinkage ratio during firing, a low bulk density and a sufficient strength. This is because the sintering reaction hardly occurs and the average fiber diameter and the average fiber length of the refractory fiber powder are reduced to a specific range by making the hard-sintering flocculent ceramic fiber into powder. It is presumed that the gap between the ceramic fiber particles formed at the time of drying is maintained even after firing, so that the bulk density is reduced, and the strength of the refractory is improved due to crosslinking by the ceramic fiber particles. Is done.

  Therefore, according to the present invention, using a ceramic fiber, a small linear shrinkage rate during firing, a refractory capable of ensuring strength at a low bulk density, a refractory forming composition having a fluidity that can be cast, A refractory fiber powder suitable for obtaining these can be provided.

3 is a scanning electron microscope image of a refractory fiber powder composed of alumina fiber powder and having an average fiber diameter of 5 μm and an average fiber length of 35 μm. 3 is a scanning electron microscope image of a refractory fiber powder composed of alumina fiber powder and having an average fiber diameter of 5 μm and an average fiber length of 25 μm. 3 is a scanning electron microscope image of a refractory fiber powder composed of alumina fiber powder and having an average fiber diameter of 5 μm and an average fiber length of 10 μm. 3 is a scanning electron microscope image of a refractory fiber powder composed of alumina fiber powder and having an average fiber diameter of 5 μm and an average fiber length of 100 μm. It is a scanning electron microscope image of a flocculent alumina fiber (before grinding). 5 is a scanning electron microscope image of a molded product obtained by casting and drying a composition for forming a refractory of Sample 5 (a product fired at 1300 ° C.). 5 is a scanning electron microscope image of a fired body obtained by casting, drying, and firing the composition for forming a refractory of Sample 5 (a product fired at 1300 ° C.).

The refractory fiber powder is composed of ceramic fiber powder containing Al ₂ O ₃ and SiO ₂ in the chemical composition. The ceramic fiber is an inorganic refractory fiber having a basic composition of Al ₂ O ₃ and SiO ₂ as defined by the Ceramic Fiber Industry Association. The ceramic fiber powder is, specifically, a powder obtained by pulverizing ceramic fibers or the like, and more specifically, an aggregate of ceramic fiber particles. In the chemical composition, the ceramic fiber powder may contain more Al ₂ O ₃ than SiO ₂ , may contain more SiO ₂ than Al ₂ O ₃ , or may contain SiO ₂ and Al ₂ O _3. May be included in equal amounts. In addition, components other than Al ₂ O ₃ and SiO ₂ may be included in the chemical composition. Specific examples of the ceramic fiber powder include a crystalline alumina fiber powder, an amorphous refractory ceramic fiber powder, and a fired refractory ceramic fiber powder. In the present specification, the term “alumina fiber powder” is used in a broad sense, and includes not only alumina fibers but also mullite fibers.

  The average fiber diameter of the refractory fiber powder was determined by randomly selecting 10 ceramic fiber particles whose end faces could be confirmed from the outermost surface of the ceramic fiber particles in the SEM image of the refractory fiber powder observed by a scanning electron microscope (SEM). And the average of the diameters of the end faces of the selected ceramic fiber particles. In addition, the average fiber length of the refractory fiber powder, among the ceramic fiber particles that appear on the outermost surface in the SEM image of the refractory fiber powder observed by a scanning electron microscope, randomly select 100 of which both ends can be confirmed, This is a value obtained by averaging the lengths of the selected ceramic fiber particles.

  The average fiber diameter of the refractory fiber powder is preferably 6.5 μm or less, from the viewpoints of availability of ceramic fibers as a raw material, improvement of fluidity of the composition for forming a refractory, reduction of bulk density of a molded article, and the like. It is preferably 6 μm or less, more preferably 5.5 μm or less, and even more preferably 5 μm or less. The average fiber diameter of the refractory fiber powder is preferably 0.5 μm or more, more preferably 1 μm or more, and still more preferably 1 μm or more, from the viewpoint of the availability of ceramic fibers as a raw material and the improvement of the specific strength of the refractory. 0.5 μm or more, and even more preferably 2 μm or more.

  The average fiber length of the refractory fiber powder is preferably 33 μm or less, more preferably 30 μm or less, from the viewpoint of improving the fluidity of the composition for forming a refractory, improving the curing reactivity, and reducing the bulk density of the refractory. More preferably, it can be 28 μm or less, even more preferably 25 μm or less. The average fiber length of the refractory fiber powder is preferably 10 μm or more, more preferably 15 μm or more, and still more preferably 20 μm or more, from the viewpoint of the crushability of the ceramic fiber and the productivity of the refractory fiber powder. .

  Specifically, the refractory fiber powder can be composed of an aggregate of ceramic fiber particles having a rod-like (column-like) shape. In this case, the above-described operation and effect can be ensured.

  The refractory fiber powder can be used for castable refractories. In this case, a castable refractory having a low linear shrinkage ratio at the time of firing, a low bulk density and sufficient strength, and a castable refractory forming composition excellent in fluidity can be obtained.

  In the refractory fiber powder, the ceramic fiber powder is preferably an alumina fiber powder. In this case, even if the average fiber length of the refractory fiber powder is a relatively large value close to 35 μm, it is easy to suppress an increase in viscosity of the composition for forming a refractory. In this case, the linear shrinkage of the refractory can be easily reduced, and the specific strength of the refractory can be easily increased.

  Specifically, the refractory fiber powder can be produced, for example, by dry or wet pulverizing a cotton-like ceramic fiber having a fiber length of about several hundred μm using a ball mill or the like.

  In the refractory fiber powder, the ceramic fiber powder may be any of a dry pulverized product and a wet pulverized product of flocculent ceramic fiber. The ceramic fiber powder is preferably a dry pulverized product of flocculent ceramic fibers. In this case, the increase in the viscosity of the composition for forming a refractory can be easily suppressed as compared with the case where the ceramic fiber powder is a wet pulverized product of a cotton-like ceramic fiber. This is considered to be because OH groups on the surface of the ceramic fiber particles hardly increase by dry pulverization.

  In the composition for forming a refractory, the refractory fiber powder is a material that functions as an aggregate and gives basic characteristics as a refractory. The composition for forming a refractory is, specifically, for example, from the viewpoint of improving fluidity, curing reactivity, and reducing the bulk density of the refractory, with respect to 100 parts by mass of water, the refractory fiber powder , Preferably 225 to 450 parts by mass, more preferably 250 to 430 parts by mass, further preferably 275 to 420 parts by mass, and still more preferably 300 to 410 parts by mass.

  In the composition for forming a refractory, the alumina cement and / or hydraulic alumina have a role as a curing agent for curing the composition for forming a refractory. The composition for forming a refractory is, for example, an alumina cement and / or water with respect to 100 parts by mass of water, from the viewpoint of, for example, accelerating the curing reaction at room temperature and reducing the linear shrinkage during firing. Hard alumina can be contained preferably in an amount of 2 to 30 parts by mass, more preferably 2.5 to 25 parts by mass, still more preferably 3 to 20 parts by mass, and still more preferably 4 to 15 parts by mass.

  The refractory-forming composition may further include a swellable clay mineral. The clay mineral having a swelling property makes it easy to mix the refractory fiber powder as an aggregate and can contribute to improving the fluidity of the composition for forming a refractory. Specific examples of the swellable clay mineral include, for example, smectite, kaolinite, halloysite, mica, vermiculite, chlorite, imogolite, allophane, sepiolite, bargilgilskite, gibbsite, and the like. One or more of these may be included.

  Specifically, the composition for forming a refractory has a swelling property with respect to 100 parts by mass of water, for example, from the viewpoint of fluidity, acceleration of a curing reaction at room temperature, reduction of a linear shrinkage rate during firing, and the like. The clay mineral may be contained preferably at most 4 parts by mass, more preferably at most 3.5 parts by mass, further preferably at most 3 parts by mass, even more preferably at most 2.5 parts by mass. In addition, the said composition for refractory formation WHEREIN: From a viewpoint of obtaining the said effect, the clay mineral which has swellability with respect to 100 mass parts of water, Preferably 0.1 mass parts or more, More preferably, 0.2 mass parts. Parts, more preferably 0.3 parts by mass or more, even more preferably 0.4 parts by mass or more.

  The refractory-forming composition may further contain an inorganic colloid. The inorganic colloid makes it easy to mix the refractory fiber powder as an aggregate and can function as an auxiliary for a curing reaction in the refractory forming composition. In particular, when the inorganic colloid is used in combination with a swelling clay mineral, the inorganic colloid tends to improve the fluidity of the composition for forming a refractory, and also to improve the strength of the refractory. Specific examples of the inorganic colloid include colloidal silica, colloidal alumina, and colloidal zirconia. One or more of these may be included.

  The refractory-forming composition is, for example, from the viewpoint of fluidity, acceleration of a curing reaction at ordinary temperature, reduction of linear shrinkage during firing, cost, etc. The colloid can preferably contain 60 parts by mass or less, more preferably 35 parts by mass or less, still more preferably 30 parts by mass or less, and still more preferably 25 parts by mass or less. In addition, the said composition for refractory formation WHEREIN: From a viewpoint of obtaining the said effect, 100 mass parts of water WHEREIN: An inorganic colloid is preferably 3 mass parts or more, more preferably 5 mass parts or more, further more preferably 8 mass parts. Parts, more preferably 10 parts by mass or more.

  The composition for forming a refractory may further contain one or more kinds of various additives. Specific examples of the additive include hollow alumina, refractory aggregate, chamotte, ceramic fiber, silicon carbide, glass powder, activated carbon, carbide, and a foaming agent.

  More specifically, hollow alumina of about 3 to 5 mm is effective in reducing the weight of refractory, improving volume stability, improving thermal shock resistance, and the like. In order to obtain these effects, the composition for forming a refractory can contain 300 parts by mass or less of hollow alumina of about 3 to 5 mm based on 100 parts by mass of water. Hollow alumina of about 1 to 3 mm is effective for improving the volume stability of the refractory, improving the thermal shock resistance, reducing the thermal conductivity, and the like. In order to obtain these effects, the composition for forming a refractory can contain 300 parts by mass or less of hollow alumina of about 1 to 3 mm based on 100 parts by mass of water. Coarse-grained refractory aggregate having a size of about 3 to 5 mm is effective for improving the volume stability of the refractory, the thermal shock resistance, and the like. In order to obtain these effects, the composition for forming a refractory can contain a coarse refractory aggregate of about 3 to 5 mm in an amount of 300 parts by mass or less based on 100 parts by mass of water. Coarse-grained refractory aggregates of about 1 to 3 mm are effective in improving the volume stability of the refractory, improving the thermal shock resistance, and the like. In order to obtain these effects, the composition for forming a refractory material can contain a coarse-grained refractory aggregate of about 1 to 3 mm in an amount of 300 parts by mass or less based on 100 parts by mass of water. The medium-sized refractory aggregate of about 0.1 to 1 mm is effective for improving the volume stability of the refractory, the thermal shock resistance, and the like, like the coarse-grained refractory aggregate of about 1 to 3 mm. In order to obtain these effects, the refractory-forming composition can contain 350 parts by mass or less of medium-grained refractory aggregate with respect to 100 parts by mass of water. The chamotte is effective in improving the volume stability of the refractory, the thermal shock resistance, and the like, as in the case of the coarse-grained refractory aggregate of about 1 to 3 mm. In order to obtain these effects, the composition for forming a refractory material can contain 300 parts by mass or less of chamotte based on 100 parts by mass of water. Ceramic fibers having a fiber length of about 200 to 1000 μm are effective for improving the volume stability and the strength of the refractory. In order to obtain these effects, the composition for forming a refractory can contain ceramic fibers in an amount of 25 parts by mass or less based on 100 parts by mass of water. Silicon carbide having an average particle size d50 of about 3 to 40 μm is effective in improving the strength of the refractory, improving the wear resistance, and the like. In order to obtain these effects, the composition for forming a refractory can contain silicon carbide in an amount of 350 parts by mass or less based on 100 parts by mass of water. Glass powder having an average particle size d50 of about 1 to 40 μm is effective in improving the strength of refractories and the like. In order to obtain these effects, the composition for forming a refractory can contain 250 parts by mass or less of glass powder with respect to 100 parts by mass of water. Activated carbon having a size of about 0.5 to 3 mm has effects such as weight reduction of refractories, improvement of volume stability, and improvement of thermal shock resistance. In order to obtain these effects, the composition for forming a refractory material can contain about 0.5 to 3 mm of activated carbon in an amount of 70 parts by mass or less based on 100 parts by mass of water. Activated carbon having an average particle diameter d50 of about 1 to 50 μm is effective in reducing the weight of the refractory and reducing the thermal conductivity. In addition, as activated carbon having a smaller average particle size is used, the pores become smaller, and the thermal conductivity is easily reduced. In order to obtain these effects, the composition for forming a refractory material can contain 120 parts by mass or less of activated carbon having an average particle size d50 of about 1 to 50 μm with respect to 100 parts by mass of water. The foaming agent is effective in reducing the weight of the refractory and reducing the thermal conductivity. In order to obtain these effects, the composition for forming a refractory can contain a foaming agent in an amount of 5 parts by mass or less based on 100 parts by mass of water. The “average particle size d50” referred to in the present specification is a volume-based cumulative frequency distribution measured by a laser diffraction / scattering type particle size distribution analyzer (“LA-500” manufactured by Horiba, Ltd.). It is the particle diameter (diameter) when indicating 50%. The particle diameters of the above-mentioned hollow alumina, coarse-grained refractory aggregate, medium-grained refractory aggregate, chamotte, and activated carbon (0.5 to 3 mm) are values obtained by sieving.

  The composition for forming a refractory is, for example, specifically, after dispersing a clay mineral having a swelling property and an inorganic colloid as necessary in water, the refractory fiber powder, and various additives as necessary. And then dispersing alumina cement and / or hydraulic alumina, for example.

The refractory is formed using the composition for forming a refractory. The above refractory can be a key Yasutaburu refractories, refractory mortar, castable refractory, such as spray can with refractory. Easy to adjust viscosity, can be cured over time, has strong adhesion to substrates, etc., does not easily change over time due to its own weight before curing, has high workability, and has a smooth surface after curing This is because there are advantages such as The refractory is more specifically, for example, a fired body of a molded article formed using the composition for forming a refractory, a trowel-coated refractory formed using the composition for forming a refractory, (sintered body of troweling body) can also be, and the like.

The refractory preferably has a bulk density in the range of 1.4 to 2.2 g / cm ³ and a flexural strength of 5 to 5 from the viewpoint of easily securing strength at a low bulk density. It is good to be in the range of 22 MPa. The bulk density is more preferably be in the range of 1.5~2g / cm ^3.

  The above-described configurations can be arbitrarily combined as necessary to obtain the above-described respective effects.

  The refractory fiber powder, the composition for forming a refractory, and the refractory will be described with reference to examples.

<Preparation of refractory fiber powder>
The following cotton-like ceramic fibers (commercially available) were prepared as raw materials.
Alumina fiber containing chemical composition of Al ₂ O ₃ : 68 mass% and SiO ₂ : 32 mass% (average fiber diameter 5 μm, average fiber length 500 μm) (manufactured by ITM Co., Ltd., “FMX bulk fiber”) (scanning electron Microscope image: Fig. 5)
A refractory ceramic fiber (average fiber diameter: 4 μm, average fiber length: 500 μm) containing Al ₂ O ₃ : 48% by mass and SiO ₂ : 52% by mass in the chemical composition (ITM Co., Ltd., “FXL bulk fiber”)
In addition, the said chemical composition was measured using the X-ray fluorescence analyzer (the product made by Rigaku Corporation, "Rigaku 3270").

  A raw material alumina fiber or refractory ceramic fiber was placed in a ball mill containing alumina balls as a grinding medium, and ground by a dry grinding method. At this time, the refractory fiber powder composed of the following six types of alumina fiber powders and the four types of refractory ceramic fiber powders were produced by adjusting the pulverization time.

Refractory fiber powder composed of alumina fiber powder and having an average fiber diameter of 5 μm and an average fiber length of 100 μm (scanning electron microscope image: FIG. 4)
Refractory fiber powder composed of alumina fiber powder and having an average fiber diameter of 5 μm and an average fiber length of 35 μm (scanning electron microscope image: FIG. 1)
A refractory fiber powder composed of alumina fiber powder and having an average fiber diameter of 5 μm and an average fiber length of 30 μm. A refractory fiber powder composed of alumina fiber powder and having an average fiber diameter of 5 μm and an average fiber length of 25 μm. Type electron microscope image: Fig. 2)
A refractory fiber powder composed of alumina fiber powder and having an average fiber diameter of 5 μm and an average fiber length of 20 μm. A refractory fiber powder composed of alumina fiber powder and having an average fiber diameter of 5 μm and an average fiber length of 10 μm. Type electron microscope image: Fig. 3)
Refractory fiber powder composed of refractory ceramic fiber powder and having an average fiber diameter of 4 μm and average fiber length of 30 μm It is composed of fiber powder and refractory ceramic fiber powder, and is composed of refractory fiber powder and refractory ceramic fiber powder having an average fiber diameter of 4 μm and an average fiber length of 20 μm, and has an average fiber diameter of 4 μm and an average fiber length of 10 μm. Some refractory fiber powder

A refractory fiber powder composed of one type of alumina fiber powder was prepared in the same manner except that the powder was pulverized by a wet pulverization method using water.
Refractory fiber powder composed of alumina fiber powder and having an average fiber diameter of 5 μm and an average fiber length of 25 μm

<Preparation of composition for forming refractory>
The following were prepared as raw materials of the composition for forming a refractory.
−Refractory fiber powder−
・ Refractory fiber powder-fire powder-
Alumina powder (average particle size d50 = 90 μm) (“A-210” manufactured by Sumitomo Chemical Co., Ltd.)
Alumina powder (average particle size d50 = 40 μm) (“A-21” manufactured by Sumitomo Chemical Co., Ltd.)
・ Alumina powder (average particle size d50 = 15 μm) (“AM-28B” manufactured by Sumitomo Chemical Co., Ltd.)
・ High alumina powder (average particle size d50 = 15 μm) (“Yaki Great Wall 85 # 325M” manufactured by Calderis Corporation)
・ Low alumina powder (average particle size d50 = 15 μm) (“Mullite Flower” manufactured by Inagaki Mining Co., Ltd.)
・ Alumina powder (average particle size d50 = 5 μm) (“AM-21” manufactured by Sumitomo Chemical Co., Ltd.)
-Curing material-
・ Alumina cement (Denka Alumina Cement No.1 manufactured by Denki Kagaku Kogyo Co., Ltd.)
-Additive-
・ Clay mineral (smectite) (Hojun Co., Ltd., “Purified bentonite (aqueous)”)
・ Inorganic colloid (colloidal silica) (manufactured by JGC Catalysts, Inc., “Cataloid SI-40”)
-Hollow alumina (3-5 mm) (Hollow sphere fused alumina BL 3-5 mmF, manufactured by Taiheiyo Random Corporation)
・ Hollow alumina (1-3 mm) (manufactured by Taiheiyo Random Co., Ltd., “Hollow sphere fused alumina BL 1-3 mm”)
・ Coarse-grained refractory aggregate (3 to 5 mm) ("Yard Great Wall 85 (3-5 mm)" manufactured by Calderis Corporation)
・ Coarse-grained refractory aggregate (1 to 3 mm) (manufactured by Calderis Corporation, “Yaki Great Wall 85 (1 to 3 mm)”)
・ Medium grain refractory aggregate (0.1-1mm) ("Karderis Co., Ltd.," Yaki Great Wall 85 (0.1-1mm) ")
・ Chamotte (3-4mm)
・ Chamotte (1-3mm)
・ Chamotte (0.1-1mm)
・ Alumina fiber (cotton) (average fiber diameter 5 μm, average fiber length 500 μm) (“FMX bulk fiber” manufactured by ITM Co., Ltd.)
・ Silicon carbide (average particle size d50 = 40 μm) (Shinano Electric Refining Co., Ltd., “polishing fine powder Shinano random GP # 320”)
・ Silicon carbide (average particle size d50 = 3 μm) (Shinano Electric Refining Co., Ltd., “polishing fine powder Shinano random GP # 4000”)
・ Glass powder (average particle size d50 = 10 μm) (a bottle glass crushed by a ball mill)
・ Activated carbon (0.5-3mm) ("KD-GA-X", manufactured by UES Corporation)
・ Activated carbon (average particle size d50 = 40 μm) (“KD-PWSG” manufactured by UES Corporation)

  Clay minerals and inorganic colloids were dispersed in predetermined amounts in 100 parts by mass of water with the formulations shown in Tables 1 to 18 described below. In some cases, the clay mineral and / or the inorganic colloid may not be dispersed. Next, a predetermined amount of the refractory fiber powder or refractory powder and, if necessary, a predetermined additive were dispersed therein. Next, a predetermined amount of alumina cement was dispersed therein. Note that a stirrer was used for dispersion. In this way, each refractory-forming composition obtained by blending each component shown in Tables 1 to 18 was obtained.

<Viscosity of composition for forming refractory>
The viscosity of the composition for forming a refractory at 20 ° C. was measured using a viscometer (manufactured by Rion, “Visco Tester VT-04E”). The viscosity was measured immediately after the preparation of the composition for forming a refractory. The composition for forming a refractory having a viscosity of 150 Pa · s or less can be cast without requiring external stimulus such as vibration, and can be said to be excellent in fluidity during casting. A composition for forming a refractory having a viscosity of more than 150 Pa · s to 300 Pa · s or less requires external stimulation such as vibration, but can be said to have good fluidity for casting. The composition for forming a refractory having a viscosity of more than 300 Pa · s to 400 Pa · s or less is mainly suitable for use in trowel coating, but may be used for cast molding, and has a fluidity capable of being cast. It can be said that it has. A composition for forming a refractory having a viscosity of more than 400 Pa · s has no fluidity and is difficult to use for casting.

<Curing reactivity of composition for forming refractory>
Each refractory forming composition was poured into a stainless steel mold (space: 160 mm long × 40 mm wide × 40 mm high) having a rectangular parallelepiped space, and cured at room temperature. The state of curing at this time was visually observed, and after confirming the curing, it was released from the mold to obtain each molded body. Further, the molded article after demolding was visually observed for cracks and the like. In addition, the confirmation of the said curing state was performed after 6 hours, 12 hours, and 18 hours. When the curing progressed and it was determined that demolding was possible, the mold was released from the mold at that point, but curing was continued at room temperature. The curing was basically carried out for 12 hours or more, and the maximum was 18 hours. The curing reactivity of each refractory-forming composition was evaluated on a four-point scale. Specifically, "(4)" indicates that the curing reactivity is excellent when cured in less than 12 hours, and "(3)" indicates that the curing reactivity is excellent when cured in 12 hours or more and 18 hours or less. Cracking was confirmed at the time of demolding, but the case where the resin was cured was regarded as "(2)" as a curing reactivity within an allowable range, and the case where curing was not performed at room temperature was regarded as "(1)" as being inferior in curing reactivity. did.

<Preparation of refractories>
Each of the molded bodies after the demolding was dried at 110 ° C. for 6 hours or more (up to 12 hours). Next, each of the dried compacts was heated to a maximum temperature at a heating rate of 100 ° C./h, and was fired under firing conditions of maintaining at the maximum temperature for 3 hours. Note that the maximum temperature was 1300 ° C or 1500 ° C.

<Amount of construction of refractory forming composition used>
The working amount of the composition for forming a refractory was calculated from the weight of the molded article after drying and the volume of the mold.

<Linear shrinkage of refractories>
For the fired rectangular parallelepiped refractory, the longest part was measured at five points with calipers and averaged, and the linear shrinkage of the refractory was calculated from the size of the mold.

<Bulk density of refractory>
While measuring the weight of the refractory, the length, width, and height of the refractory were measured at five points with a vernier caliper and averaged to obtain the volume of the refractory, and the bulk density of the refractory was calculated. did.

<Bending strength of refractories>
The bending strength of the refractory was measured by a three-point bending test (average value of N = 3) using a universal bending tester (“RTF-2325” manufactured by A & D).

<Specific strength of refractories>
The specific strength of the refractory was calculated by dividing the value of the bending strength by the value of the bulk density.

  Tables 1 to 18 collectively show the composition and each property of the produced refractory forming composition, each property of the refractory, and the like.

  Tables 1 to 7 show the following. Sample 52 containing 230 parts by mass of alumina powder having an average particle size d50 of 90 μm has no fluidity. Sample 54 (d50 = 40 μm), in which the average particle size of the alumina powder was smaller than that of Sample 52, already showed a high value of 350 Pa · s when the compounding amount of the alumina powder was 300 parts by mass. As shown in Sample 55, when the amount of the alumina powder is further increased, the viscosity sharply increases. In Samples 57 and 58, although the increase in viscosity can be suppressed by further reducing the average particle size of the alumina powder as compared with Sample 54 and the like, the linear shrinkage ratio during firing becomes extremely large, and the volume stability is reduced. Chip. The samples 60 and 61 also show the same tendency as the samples 57 and 58. Further, as shown in the sample 57, the strength can be secured by baking. However, the refractory of the sample 57 has a high bulk density because the internal voids are reduced by baking.

  On the other hand, the sample 21 uses refractory fiber powder composed of alumina fiber powder. However, the average fiber length of the refractory fiber powder is 100 μm, which is far beyond the range specified in the present invention. Therefore, sample 21 had no fluidity at a compounding amount of about 230 parts by mass, and could not be cast. From this result, it can be said that it is difficult to obtain a refractory material having a low bulk density and sufficient strength by using a large amount of ceramic fibers as an aggregate in Sample 21.

On the other hand, the refractory fiber powders in the other samples shown in Tables 1 to 7 are composed of ceramic fiber powders containing Al ₂ O ₃ and SiO ₂ in the chemical composition, and have an average fiber diameter and an average fiber length. Within the specific range defined in the present invention. Therefore, the refractory fiber powder can suppress an increase in viscosity of the refractory-forming composition, even when a large amount is added to water as an aggregate when preparing the refractory-forming composition. ing. Therefore, the composition for forming a refractory containing the refractory fiber powder has a fluidity that can be cast and molded, including those having excellent fluidity during casting and those having good fluidity. I understand. In addition, according to the composition for forming a refractory material containing the refractory fiber powder, a refractory material having a small linear shrinkage ratio at the time of firing, a low bulk density and a sufficient strength can be obtained.

  6 and 7 that the gaps between the ceramic fiber particles formed during drying after molding are maintained even after firing. In addition, even after firing, the rod-shaped ceramic fiber particles maintain their shape, and it can be seen that the sintering reaction has not progressed so much.

  Next, according to Tables 8 to 10, the following can be understood. When the composition for forming a refractory containing the refractory fiber powder contains a clay mineral having a swelling property, the refractory fiber powder as an aggregate is easily mixed, which is advantageous for improving the fluidity of the composition for forming a refractory. It is. Further, the composition for forming a refractory, while obtaining the effect of addition, from the viewpoint of fluidity, acceleration of the curing reaction at room temperature, reduction of the linear shrinkage rate during firing, etc., the swelling property with respect to 100 parts by mass of water. It can be seen that it is preferable that the clay mineral is contained in the range of 0.1 to 4 mass% or less.

  When the composition for forming a refractory containing the refractory fiber powder contains an inorganic colloid, the refractory fiber powder as an aggregate is easily mixed and contributes to assisting a curing reaction in the composition for forming a refractory. can do. In addition, the composition for forming a refractory, while obtaining the effect of addition, from the viewpoint of fluidity, acceleration of the curing reaction at room temperature, reduction of the linear shrinkage at the time of firing, etc., the inorganic colloid with respect to 100 parts by mass of water It can be seen that it is preferable that the content be contained in the range of 3 to 60 mass or less.

  Next, according to Table 11, the following can be understood. As shown in Samples 57, 58, and 63 to 66, even if the alumina content in the refractory powder composed of alumina powder was changed, the linear shrinkage of the refractory using such refractory powder as an aggregate was significantly increased. It turns out that it is difficult to reduce the size. Further, as shown in Samples 48 and 62, even when refractory ceramic fiber powder was used as the refractory fiber powder instead of alumina fiber powder, the same effect as when alumina fiber powder was used was obtained. It can be seen that it can be obtained. However, when alumina fiber powder was used as the refractory fiber powder, although the viscosity of the composition for forming a refractory slightly increased within the allowable range, the linear shrinkage decreased, and the specific strength also increased. There was a tendency to be easy.

  Next, according to Table 12, the following can be understood. Table 12 confirms the effect of the bulk density on the bending strength. That is, as shown in Table 12, here, activated carbon, which is an organic substance, was added to the composition for forming a refractory material, and this was eliminated during firing, thereby making the refractory material porous. When compared at the same bulk density, the refractories of Samples 5 and 48 using the refractory fiber powder have the same or higher specific strength as the refractories of other samples using the conventional refractory powder. You can see that there is.

  Next, Table 13 shows the following. As shown in Table 13, when the ceramic fiber powder constituting the refractory fiber powder is a dry pulverized product of flocculent ceramic fiber, the ceramic fiber powder is a wet pulverized product of the flocculent ceramic fiber. It can be seen that the increase in viscosity of the composition for forming a refractory is more easily suppressed than in the case.

  Next, according to Tables 14 to 18, the following can be understood. As shown in Tables 14 to 18, even if the additives described in each table were blended in the composition for forming a refractory using a refractory fiber powder composed of ceramic fiber powder as an aggregate, the refractory formation did not occur. It can be seen that the viscosity and curing reactivity of the composition for use are not significantly impaired. Therefore, it can be seen that by adding an appropriate amount of these additives to the composition for forming a refractory, a refractory capable of enjoying the effects of the above-described additives can be obtained.

  As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention.

Claims (11)

Refractory fiber powder for castable refractories, refractory mortars, sprayed refractories, or troweled refractories,
It is composed of ceramic fiber powder containing Al ₂ O ₃ and SiO ₂ in chemical composition,
A refractory fiber powder having an average fiber diameter of 4 μm to 7 μm and an average fiber length of 10 μm to 35 μm. The refractory fiber powder according to claim 1, wherein the ceramic fiber powder is an alumina fiber powder. Castable refractory, refractory mortar, sprayed refractory, or refractory forming composition used for forming a refractory consisting of troweled refractory,
And water, according to claim 1 or a 2 and refractory fiber powder according to, alumina cement and / or hydraulic alumina, a refractory forming composition. The composition for forming a refractory according to claim 3 , comprising 225 to 450 parts by mass of the refractory fiber powder based on 100 parts by mass of the water. The composition for forming a refractory according to claim 3 or 4 , comprising a clay mineral having a swelling property. The composition for forming a refractory according to claim 5 , wherein the composition contains 4 parts by mass or less of the clay mineral with respect to 100 parts by mass of the water. The composition for forming a refractory according to claim 6, wherein the composition contains at least 0.1 part by mass of the clay mineral with respect to 100 parts by mass of the water. The composition for forming a refractory according to any one of claims 3 to 7, comprising an inorganic colloid.   9. The composition for forming a refractory according to claim 8, wherein the composition contains 60 parts by mass or less of the inorganic colloid with respect to 100 parts by mass of the water. The composition for forming a refractory according to claim 9, comprising 3 parts by mass or more of the inorganic colloid with respect to 100 parts by mass of the water. A refractory formed using the composition for forming a refractory according to any one of claims 3 to 10 .