Sagger, manufacturing method of sagger and manufacturing method of fired product

Abstract

To provide a sagger and a method for manufacturing the sagger that is resistant to breakage, capable of suppressing the effects of impurities originating from the material forming the sagger from mixing with the material to be fired when the material to be fired is fired using the sagger, and producing high quality fired products.SOLUTION: The sagger according to the present invention has a body made of inorganic material and containing the material to be fired, and a coating layer formed on at least one of the surfaces of the body in contact with the material to be fired, wherein the coating layer has an average primary particle size of 1 nm to 100 nm and consists of one or two or more kinds of nanoparticles selected from alumina, hydrated alumina, zirconia, hydrated zirconia, silica, titania, hydrated titania, magnesia, spinel, and gahnite, and a film-forming component.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a sagger, a method for manufacturing a sagger, and a method for manufacturing a fired product.

Background Art

[0002] Conventionally, in the manufacturing process of inorganic oxides, there may be a firing step of obtaining a fired product by putting a material to be fired into a firing container (sagger) and heating it. Examples of the firing container used in the firing step include those described in Patent Documents 1 to 3.

[0003] Patent Document 1 describes a sagger for firing electronic components, the surface of which is coated with zirconia, for use in the firing of electronic components. Patent Document 1 describes a method for repairing a sagger for firing electronic components, in which a surface treatment agent obtained by slurrying zirconia powder having a particle size of 30 μm or less with a solvent such as water is applied and dried to the missing part of the sagger or the peeled part of the coated zirconia.

[0004] Patent Document 2 describes a sagger used when heat-treating a ceramic green body or the like used in the manufacture of ceramic electronic components. Patent Document 2 describes a sagger having a high emissivity material in which at least the outer wall surface and the outer bottom surface of the sagger exhibit a higher emissivity than at least one of the inner wall surface and the inner bottom surface. Further, Patent Document 2 describes that the inner wall surface and the inner bottom surface of the sagger are coated with a low emissivity material containing zirconia.

[0005] Patent Document 3 describes a sagger for manufacturing a lithium ion positive electrode active material, in which the surface of the sagger body made of an inorganic material that comes into contact with the lithium ion positive electrode active material is ceramic-coated with a material selected from one or more of zirconia, alumina, silicon nitride, spinel, or magnesia.

Prior Art Documents

Patent Documents

[0006] Patent Document 1 Japanese Patent Application Laid-Open No. 09-202666 Patent Document 2 Japanese Patent Application Laid-Open No. 2015-059698 Patent Document 3 Japanese Patent Application Laid-Open No. 2014-118339 Summary of the Invention Problems to be Solved by the Invention

[0007] As the sagger used in the manufacturing process of inorganic oxides and the like, it is preferable to use one made of a material that does not react with the material to be fired and has few impurities. The reason is to prevent impurities derived from the material forming the sagger from mixing into the material to be fired and having an adverse effect on the fired product. For example, as the sagger used in the manufacturing process of alumina, which is an inorganic oxide, it is preferable to use one made of high-purity dense alumina.

[0008] However, a sagger made of a material that does not react with the material to be fired and has few impurities generally has the disadvantages of being expensive and easily damaged. Therefore, when firing using a sagger made of a material that does not react with the material to be fired and has few impurities, it is necessary to sufficiently slow down the heating rate and the cooling rate in order to prevent the sagger from being damaged. As a result, it has been difficult to improve the degree of freedom of firing conditions and the production efficiency of the fired product.

[0009] In addition, as a method for preventing the influence of impurities derived from the material forming the sagger from mixing into the material to be fired, there is a method of forming a coating layer on the surface of the sagger to avoid contact between the surface of the sagger and the material to be fired.

[0010] However, a sagger having a coating layer on its surface is likely to have cracks in the coating layer and is easily damaged when the material to be fired is fired using it. For this reason, the effect of avoiding contact between the surface of the sagger and the material to be fired by the coating layer formed on the surface of the sagger has not been sufficiently obtained.The present invention has been made in view of the above circumstances, and is difficult to break. When a material to be fired is fired using this, the influence caused by impurities derived from the material forming the sagger being mixed into the material to be fired can be suppressed, and a sagger capable of manufacturing a high-quality fired product, a method for manufacturing a sagger, and a method for manufacturing a fired product are provided.

Means for Solving the Problems

[0011] [1] It is made of an inorganic material and has a main body for housing the material to be fired and a coating layer formed on at least the contact surface that contacts the material to be fired among the surfaces of the main body. The coating layer has an average particle diameter of primary particles of 1 nm or more and 100 nm or less, and is composed of one or more kinds of nanoparticles selected from alumina, hydrated alumina, zirconia, hydrated zirconia, silica, titania, hydrated titania, magnesia, spinel, and garnet, and a film-forming component. Sagger.

[0012] [2] The sagger according to [1], wherein the thickness of the coating layer is 500 nm or less. [3] The sagger according to [1] or [2], which is used when firing the material to be fired in the presence of a molybdenum compound to produce an inorganic oxide. [4] The sagger according to any one of [1] to [3], wherein the porosity of the main body is 25% to 35% by volume.

[0013] [5] It is made of an inorganic material and has a coating step of forming a coating layer on at least the contact surface that contacts the material to be fired among the surfaces of the main body for housing the material to be fired. The coating step includes a coating agent containing one or more kinds of nanoparticles selected from alumina, hydrated alumina, zirconia, hydrated zirconia, silica, titania, hydrated titania, magnesia, spinel, and garnet having an average particle diameter of primary particles of 1 nm or more and 100 nm or less, and a film-forming component. A method for manufacturing a sagger, which includes a coating step of forming a coating layer made of a coating film by applying it to at least the contact surface of the main body.

[0014] [6] The method for manufacturing a crucible according to [5], wherein the film-forming component is a water-soluble polymer. [7] The method for manufacturing a crucible according to [6], wherein the water-soluble polymer is hydroxypropyl cellulose. [8] The method for manufacturing a crucible according to [7], wherein the water-soluble polymer is hydroxypropyl cellulose having a mass average molecular weight of 40,000 to 200,000. [9] The method for manufacturing a crucible according to any one of [5] to [8], wherein the nanoparticles are composed of one or two selected from alumina and hydrated alumina.

[10] The method for manufacturing a crucible according to any one of [5] to [9], wherein the porosity of the main body is 25% by volume to 35% by volume.

[0015]

[11] It is made of an inorganic material and has a main body for accommodating a material to be fired and a coating sintered layer formed on at least a contact surface of the surface of the main body that contacts the material to be fired. The coating sintered layer has a thickness of 50 nm to 500 nm and includes a sintered body of particles composed of one or more selected from alumina, hydrated alumina, zirconia, hydrated zirconia, silica, titania, hydrated titania, magnesia, spinel, and garnet. A crucible.

[0016]

[12] A step of forming a coating layer on at least a contact surface of the surface of a main body made of an inorganic material and accommodating a material to be fired that contacts the material to be fired, wherein the average particle diameter of the primary particles is 1 nm or more and 100 nm or less, and alumina, hydrated alumina, zirconia, hydrated zirconia, silica, titania, hydrated titania, magnesia, spinel, A coating step of forming a coating layer made of a coating film by applying a coating agent containing one or more nanoparticles selected from garnet and a film-forming component to at least the contact surface of the surface of the main body, A method for manufacturing a crucible, comprising a sintering step of sintering the nanoparticles contained in the coating layer.

[0017]

[13] In the sintering process, a material to be fired is placed in the body with the coating layer formed thereon and heated to obtain a fired product of the material to be fired, according to the method for manufacturing a crucible described in

[12] .

[14] The method for manufacturing a crucible according to

[13] , wherein the nanoparticles and the fired product contain the same compound.

[0018]

[15] A method for manufacturing a fired product, comprising placing the material to be fired in the body of the crucible according to any one of [1] to [4], firing the material to be fired, and manufacturing a fired product. [Advantages of the Invention]

[0019] The crucible of the present invention is made of an inorganic material and has a body for accommodating a material to be fired and a coating layer formed on at least a contact surface that contacts the material to be fired among the surfaces of the body. The coating layer contains nanoparticles made of a specific material having an average particle diameter of primary particles of 1 nm or more and 100 nm or less, and a film-forming component. Therefore, the coating layer is firmly fixed to the contact surface of the body, and when the material to be fired is fired using the crucible of the present invention, the coating layer is less likely to be damaged. Therefore, when the material to be fired is fired using the crucible of the present invention, the effect of preventing contact between the material to be fired and the body by the coating layer can be sufficiently obtained. From this, when the material to be fired is fired using the crucible of the present invention, the influence caused by impurities derived from the material forming the crucible being mixed into the material to be fired can be suppressed, and a high-quality fired product can be manufactured.

[0020] The method for manufacturing a crucible of the present invention is made of an inorganic material and has a coating step of forming a coating layer on at least a contact surface that contacts the material to be fired among the surfaces of the body for accommodating the material to be fired. The coating step includes a coating step of forming a coating layer made of a coating film by applying a coating agent containing nanoparticles made of a specific material having an average particle diameter of primary particles of 1 nm or more and 100 nm or less, and a film-forming component, to at least the contact surface of the body surface. Therefore, according to the method for manufacturing a crucible of the present invention, the crucible of the present invention can be easily manufactured.

[0021] In the method for manufacturing a fired product of the present invention, a material to be fired is placed in the main body of the sagger of the present invention, and the material to be fired is fired to manufacture a fired product. For this reason, impurities derived from the material forming the main body of the sagger are less likely to be mixed into the material to be fired, the material forming the main body and the material to be fired are less likely to react, and a high-quality fired product can be manufactured.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0023] The inventors of the present invention have earnestly studied to solve the above problems and focused on the function of avoiding contact between the material to be fired and the main body of the sagger by the coating layer. As a result, it has been found that a coating agent containing nanoparticles made of a specific material having an average primary particle diameter of 1 nm or more and 100 nm or less and a film-forming component is applied to at least the contact surface of the main body that contacts the material to be fired, whereby a coating layer made of a coating film may be formed.

[0024] The coating layer formed in this way is firmly fixed to the contact surface of the main body due to the synergistic effect of the sufficiently small average primary particle diameter of the nanoparticles and the inclusion of the film-forming component. Therefore, when manufacturing the coating layer, it is difficult for the coating film that becomes the coating layer to peel off from the contact surface of the main body, and it is easy to obtain a sagger having a coating layer that sufficiently covers the contact surface of the main body and can be easily manufactured. Further, even when the material to be fired is fired using the sagger having the above coating layer, the coating layer is hardly damaged, and the effect of avoiding contact between the material to be fired and the main body of the sagger by the coating layer can be sufficiently obtained.

[0025] On the other hand, for example, when the coating layer contains coarse particles with an average particle diameter of the primary particles exceeding 100 nm instead of nanoparticles, and / or when the coating layer does not contain a film-forming component, the coating layer is likely to peel off from the contact surface of the main body, and the effect of avoiding contact between the material to be fired and the main body of the sagger by the coating layer cannot be sufficiently obtained.

[0026] Furthermore, the inventors of the present invention have found that a coating layer containing nanoparticles made of a specific material with an average particle diameter of the primary particles being 1 nm or more and 100 nm or less and a film-forming component is formed on at least the contact surface of the surface of the main body that contacts the material to be fired. When the material to be fired is fired using the sagger, it was confirmed that the influence of impurities derived from the material forming the sagger being mixed into the material to be fired can be suppressed and a high-quality fired product can be manufactured, and the present invention was conceived.

[0027] Hereinafter, the sagger of the present invention, the manufacturing method of the sagger, and the manufacturing method of the fired product will be described in detail with reference to the drawings. Note that the drawings used in the following description may show, for the sake of clarity, the characteristic parts enlarged for convenience. For this reason, the dimensional ratios of each component may be different from the actual ones. The scope of the present invention is not limited to the embodiment described here, and various modifications can be made without departing from the spirit of the present invention. Also, when a plurality of upper limit values and lower limit values are described for a specific parameter, any upper limit value and lower limit value can be combined to form a suitable numerical range.

[0028] [First Embodiment] (Sagger) FIG. 1 is a cross-sectional view for explaining an example of the sagger of the present embodiment. The sagger 1 shown in FIG. 1 has a main body 10 and a coating layer 20. The sagger 1 shown in FIG. 1 is substantially square in plan view and concave in cross-sectional view. In the present embodiment, as an example, the case where the planar shape of the sagger 1 is substantially square will be described. However, the planar shape of the sagger 1 may be, for example, substantially rectangular or substantially circular, and is not particularly limited.

[0029] (Body) The body 10 of the sagger 1 in this embodiment is made of an inorganic material. As the inorganic material that can be used for the body 10, known inorganic materials that can be used for the sagger 1 can be used. Specifically, examples of the inorganic material that can be used for the body 10 include mullite, mullite-cordierite, alumina, magnesia, silica, zirconia, and the like. Among these inorganic materials, in order to obtain a sagger 1 that is inexpensive, difficult to break, and has a high degree of freedom in firing conditions, it is preferable to use mullite and / or mullite-cordierite.

[0030] The body 10 can be manufactured by a conventionally known method, and can be appropriately determined according to the type of the inorganic material forming the body 10, the shape, size, etc. of the body 10. As the body 10, a sagger made of a commercially available inorganic material may be used. As the body 10, it is preferable to use one having a porosity of 25 to 35% by volume. When the porosity of the body 10 is 25% by volume or more, the body 10 is not too dense, so the sagger is less likely to break. Also, when the porosity of the body 10 is 35% by volume or less, sufficient strength can be ensured, and the sagger is less likely to break.

[0031] (Coating layer) As shown in FIG. 1, the coating layer 20 in the sagger 1 of this embodiment is formed with a substantially uniform thickness so as to cover the entire surface of the body 10. The coating layer 20 contains nanoparticles having an average primary particle diameter of 1 nm or more and 100 nm or less, and a film-forming component.

[0032] Since the average primary particle diameter of the primary particles of the nanoparticles contained in the coating layer 20 is 1 nm or more, the nanoparticles used as the material of the coating layer 20 can be easily obtained. The average primary particle diameter of the primary particles of the nanoparticles is preferably 5 nm or more, and more preferably 10 nm or more.

[0033] In addition, since the average particle diameter of the primary particles of the nanoparticles contained in the coating layer 20 is 100 nm or less, by firing the material to be fired using the sagger 1 of the present embodiment, a coating sintered layer with a thickness that is difficult to peel off from the inner surface 11 of the main body 10 and is less likely to crack is formed. Also, since the average particle diameter of the primary particles of the nanoparticles is 100 nm or less, when manufacturing the coating layer 20, the coating film that becomes the coating layer 20 is less likely to peel off from the surface of the main body 10. Therefore, it is easy to obtain the sagger 1 having the coating layer 20 that sufficiently covers the surface of the main body 10, and it can be easily manufactured. The average particle diameter of the primary particles of the nanoparticles is preferably 50 nm or less, and more preferably 30 nm or less.

[0034] The nanoparticles contained in the coating layer 20 are composed of one or more selected from alumina, hydrated alumina, zirconia, hydrated zirconia, silica, titania, hydrated titania, magnesia, spinel, and garnet. All of these nanoparticles have a high melting point. Therefore, for example, by firing the material to be fired using the sagger 1, the coating layer 20 containing these nanoparticles can form a coating sintered layer having heat resistance that can sufficiently withstand the use temperature of the sagger 1.

[0035] The type of nanoparticles contained in the coating layer 20 can be appropriately selected according to the use of the sagger 1, and it is preferably determined according to the type of the material to be fired fired using the sagger 1. The nanoparticles contained in the coating layer 20 preferably contain the same compound as the fired product of the material to be fired. The reason is that when firing the material to be fired using the sagger 1, the influence of impurities derived from the material forming the sagger 1 mixing into the material to be fired can be effectively suppressed, and a high-quality fired product can be manufactured.

[0036] For example, in the sagger 1 used when manufacturing alumina as a fired product, it is preferable that the nanoparticles contained in the coating layer 20 are composed of one or two types selected from alumina and hydrated alumina. In this case, the influence of impurities derived from the material forming the sagger 1 on the fired product can be effectively suppressed. Also, since the thermal conductivity of the nanoparticles is relatively high, the coating layer 20 becomes a coating layer through which heat is easily transferred to the fired product during firing. Moreover, the nanoparticles are easy to obtain and / or synthesize.

[0037] As the film-forming component contained in the coating layer 20, a water-soluble polymer or a thermoplastic polymer dissolved in an organic solvent may be used. Examples of the water-soluble polymer include hydroxyalkyl celluloses such as hydroxyethyl cellulose and hydroxypropyl cellulose, hydroxyalkylalkyl celluloses such as hydroxyethylmethyl cellulose, hydroxypropylmethyl cellulose, and hydroxyethylethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, polyacrylic acid, and the like. Examples of the thermoplastic polymer dissolved in an organic solvent include polystyrene, polyethylene terephthalate, polyacrylate, polymethacrylate, and the like. The film-forming component may be contained only in one type or two or more types in the coating layer 20.

[0038] The film-forming component contained in the coating layer 20 is preferably a water-soluble polymer, and among the above water-soluble polymers, hydroxypropyl cellulose is particularly preferred. The reason is that a coating agent containing nanoparticles, water, and a water-soluble polymer becomes one in which the nanoparticles are uniformly dispersed. By applying the coating agent in which the nanoparticles are uniformly dispersed to the surface of the main body 10 and removing the water in the coating agent, a coating layer 20 with a thin and uniform thickness can be formed without becoming island-shaped or mesh-shaped. Further, when the coating agent contains water and hydroxypropyl cellulose, it has excellent film-forming ability. Therefore, when manufacturing the coating layer 20, the coating film that becomes the coating layer is difficult to peel off from the surface of the main body 10. Therefore, by applying the coating agent and removing the water in the coating agent, the coating layer 20 that sufficiently covers the surface of the main body 10 can be easily formed. Further, since hydroxypropyl cellulose has a relatively low decomposition temperature, it has the advantage that it easily burns completely during firing and hardly leaves ash.

[0039] When the coating layer 20 contains hydroxypropyl cellulose, the hydroxypropyl cellulose preferably has a mass average molecular weight (Mw) of 40,000 to 200,000, and more preferably 100,000 to 150,000. The reason is that when manufacturing the coating layer 20 using a coating agent containing nanoparticles, water, and hydroxypropyl cellulose, it is easy to obtain a coating agent having more excellent film-forming ability and a viscosity that can be applied efficiently. Further, it is because a coating layer 20 with a thin and uniform thickness can be easily formed by the method of applying the obtained coating agent. The mass average molecular weight (Mw) of hydroxypropyl cellulose can be measured by known methods such as gel permeation chromatography under known measurement conditions.

[0040] Hydroxyalkyl cellulose can be produced by a known method. Also, a commercially available product may be used as the hydroxyalkyl cellulose. When using commercially available hydroxypropyl cellulose as the hydroxyalkyl cellulose, for example, hydroxypropyl cellulose (HPC-L, M, L, SL, H: manufactured by Nippon Soda Co., Ltd.) can be used.

[0041] In addition to the nanoparticles and the film-forming component, the coating layer 20 may contain other components as necessary within a range not deviating from the gist of its function. Examples of the other components include an acid, a base, a dispersant, an organic solvent, an antifoaming agent, and the like.

[0042] The thickness of the coating layer 20 shown in FIG. 1 is not particularly limited, but is preferably 500 nm or less. When the thickness of the coating layer 20 is 500 nm or less, the coating layer 20 heated by firing the material to be fired using the crucible 1 of the present embodiment is less likely to peel off from the inner surface 11 of the main body 10 and is less likely to crack. Further, by firing the material to be fired using the crucible 1, the coating sintered layer 30 formed by sintering the nanoparticles contained in the coating layer 20 is stably fixed on the surface of the main body 10. More preferably, the thickness of the coating layer 20 is 400 nm or less.

[0043] Also, the thickness of the coating layer 20 is preferably 100 nm or more. This is because the coating layer 20 is formed with a uniform film thickness without becoming island-shaped or mesh-shaped, and the coating layer 20 can cover the surface of the main body 10 with a high coverage rate, and can more effectively prevent contact between the main body 10 and the material to be fired. The thickness of the coating layer 20 is more preferably 200 nm or more.

[0044] (Manufacturing method) The crucible 1 of the present embodiment can be manufactured, for example, using the manufacturing method shown below. To manufacture the crucible 1 of the present embodiment, first, the main body 10 shown in FIG. 1 is prepared. The main body 10 is made of an inorganic material and may be manufactured by a conventionally known method or a commercially available crucible may be used.

[0045] Next, in the present embodiment, a coating layer 20 is formed on the entire surface of the main body 10 (coating step). The coating step in the present embodiment includes a coating step of forming a coating layer 20 made of a coating film by applying a coating agent containing nanoparticles having an average particle diameter of primary particles of 1 nm or more and 100 nm or less and a film-forming component to the entire surface of the main body 10.

[0046] The coating agent used in the coating step contains the nanoparticles contained in the above-described coating layer 20 and the film-forming component contained in the above-described coating layer 20, and preferably contains nanoparticles, a dispersion medium, and a film-forming component. As the dispersion medium, an aqueous medium such as water, a mixed solution of water and ethanol, or a mixed solution of water and propylene glycol may be used, or an organic medium such as ethanol, isopropyl alcohol, propylene glycol monomethyl ether, toluene, or xylene may be used, and it can be appropriately determined according to the type of the film-forming component. In the present embodiment, it is preferable to use water as the dispersion medium, and it is preferable to use the above-described water-soluble polymer as the film-forming component.

[0047] The coating agent used in the coating step may contain other components, if necessary, within a range not deviating from the main purpose of its function, in addition to nanoparticles, a dispersion medium, and a film-forming component. Examples of the other components include an acid, a base, a dispersant, a surface tension adjuster, and an antifoaming agent.

[0048] The coating agent used in the coating process can be manufactured by known methods. When the coating agent used in the coating process contains, for example, nanoparticles, water as a dispersion medium, and a water-soluble polymer as a film-forming component, it is preferably manufactured by the method shown below. This is because a coating agent with uniformly dispersed nanoparticles can be easily and efficiently manufactured.

[0049] First, disperse the nanoparticles in water to prepare a nanoparticle aqueous dispersion with a predetermined concentration. Also, dissolve the water-soluble polymer in water to prepare an aqueous solution of the water-soluble polymer with a predetermined concentration. The nanoparticle aqueous dispersion and / or the aqueous solution of the water-soluble polymer may contain other components as necessary. Then, mix and stir a predetermined amount of the nanoparticle aqueous dispersion and a predetermined amount of the aqueous solution of the water-soluble polymer to manufacture the coating agent.

[0050] In the coating process, as a method of applying the coating agent to the inner surface 11 and the outer surface 12 of the main body 10, known methods can be used. As a method of applying the coating agent, for example, a method using a brush, a method using a spray, a method of immersing the main body 10 in the coating agent contained in a container, etc. can be used.

[0051] In this embodiment, after applying the coating agent to the inner surface 11 and the outer surface 12 of the main body 10, it is preferable to form a coating layer 20 made of a coating film by drying. As a method of drying the inner surface 11 and the outer surface 12 of the main body 10 to which the coating agent has been applied, known methods can be used, and it can be appropriately determined according to the types of the dispersion medium and the film-forming component contained in the coating agent. For example, when the coating agent contains nanoparticles, water as a dispersion medium, and a water-soluble polymer as a film-forming component, a method of drying the inner surface 11 and the outer surface 12 of the main body 10 by heating the main body 10 to which the coating agent has been applied to remove water can be used.

[0052] In this embodiment, the thickness of the coating layer 20 can be adjusted by changing the composition of the coating agent and / or the coating amount of the coating agent.

[0053] [Second Embodiment] FIG. 2 is a cross-sectional view for explaining another example of the crucible of this embodiment. The crucible 2 shown in FIG. 2 has a main body 10 and a coating sintered layer 30 formed with a substantially uniform thickness so as to cover the entire surface of the main body 10.

[0054] (Coating Sintered Layer 30) The coating sintered layer 30 includes a sintered body of particles composed of one or more selected from alumina, hydrated alumina, zirconia, silica, titania, and spinel. The sintered body of particles included in the coating sintered layer 30 shown in FIG. 2 is a sintered body of nanoparticles in which the average particle diameter of the primary particles included in the above-described coating layer 20 is 1 nm or more and 100 nm or less.

[0055] The coating sintered layer 30 in the crucible 2 is formed by sintering the nanoparticles included in the coating layer 20 into a sintered body and removing the film-forming components, and has a thickness of 500 nm or less. When the average particle diameter of the primary particles of the nanoparticles included in the coating layer 20 exceeds 100 nm, necking between the particles hardly progresses, and a strong coating sintered layer 30 cannot be obtained.

[0056] In the crucible 2 of this embodiment, since the thickness of the coating sintered layer 30 is 500 nm or less, the coating sintered layer 30 is stably fixed on the surface of the main body 10. Therefore, even when the material to be fired is fired using the crucible 2, the coating sintered layer 30 is less likely to peel off from the inner surface 11 of the main body 10 or crack. Thus, when the material to be fired is fired using the crucible 2 of this embodiment, impurities derived from the material forming the main body 10 are less likely to mix into the material to be fired, and the material forming the main body 10 and the material to be fired are less likely to react, enabling the production of high-quality fired products. Further, in the crucible 2 of this embodiment, since the coating sintered layer 30 is less likely to crack and break, it can be used multiple times as a firing container for firing the material to be fired and has excellent durability. The thickness of the coating sintered layer 30 is preferably 300 nm or less.

[0057] The thickness of the coating sintered layer 30 is 50 nm or more. For this reason, the coating sintered layer 30 is formed with a uniform thickness without becoming island-shaped or mesh-shaped, and the surface of the main body 10 can be covered with a high coverage rate by the coating sintered layer 30. When the surface of the main body 10 is covered with the coating sintered layer 30 at a high coverage rate, impurities derived from the material forming the main body 10 are even less likely to mix into the material to be fired when the material to be fired is fired using the crucible 2, enabling the production of high-quality fired products. The thickness of the coating sintered layer 30 is preferably 100 nm or more.

[0058] (Manufacturing method) The crucible 2 shown in FIG. 2 can be manufactured by heating the crucible 1 shown in FIG. 1 and performing a firing process of sintering the nanoparticles contained in the coating layer 20 to form the coating sintered layer 30. The firing process for forming the coating sintered layer 30 is not particularly limited as long as the nanoparticles contained in the coating layer 20 can be sintered.

[0059] The firing process for forming the coating sintered layer 30 is preferably a process of putting the material to be fired into the body 10 on which the coating layer 20 is formed and heating it to obtain a fired product of the material to be fired. That is, in the present embodiment, instead of performing the firing process only for forming the coating sintered layer 30, in the process of obtaining the fired product of the material to be fired, it is preferable to manufacture the fired product and form the coating sintered layer 30 at the same time. In this case, for example, compared with the case where the firing process is performed to manufacture the sagger 2 for forming the coating sintered layer 30, the obtained material to be fired is put into the body 10 of the sagger 2 and heated to obtain the fired product of the material to be fired, the same effect can be obtained with fewer steps.

[0060] In the sintering process, when putting the material to be fired into the body 10 on which the coating layer 20 is formed, heating it to obtain a fired product of the material to be fired, and forming the coating sintered layer 30, it is preferable that the nanoparticles contained in the coating layer 20 and the fired product contain the same compound. The reason is that the influence on the fired product due to the material to be fired put into the body 10 being fired in contact with the coating layer 20 can be suppressed, and a high-quality fired product can be stably manufactured.

[0061] The firing conditions such as the atmosphere, firing temperature, and firing time in the firing process for forming the coating sintered layer 30 may be any firing conditions that can sinter the nanoparticles contained in the coating layer 20. For example, when the firing process for forming the coating sintered layer 30 is a process of putting the material to be fired into the body 10 on which the coating layer 20 is formed and heating it to obtain a fired product of the material to be fired, the firing conditions can be the optimal firing conditions for manufacturing the fired product of the material to be fired. That is, in the present embodiment, when the coating sintered layer 30 is formed, it is difficult for the coating sintered layer 30 to peel off from the surface of the body 10 or cracks to occur in the coating sintered layer 30. Therefore, it is not necessary to slow down the heating rate and cooling rate during the production of the fired product, and the coating sintered layer 30 can be formed without reducing the production efficiency of the fired product.

[0062] The thickness of the coating sintered layer 30 in the sagger 2 of the present embodiment can be adjusted by, for example, changing the content per unit area of the nanoparticles contained in the coating layer 20 shown in FIG. 1 and / or the average particle diameter of the primary particles of the nanoparticles contained in the coating layer 20.

[0063] (Use) The saggers 1 and 2 of the first and second embodiments described above can be suitably used as firing containers used when firing a material to be fired to produce a fired product. Since the saggers 1 and 2 of the first and second embodiments are less likely to be damaged when producing a fired product, there is no need to slow down the heating rate and the cooling rate when producing the fired product in order to prevent damage to the saggers 1 and 2, and the degree of freedom of the firing conditions is not reduced. Therefore, the fired product produced using the saggers 1 and 2 of the first and second embodiments is not particularly limited, and a high-quality fired product can be efficiently produced under the optimum firing conditions when producing the fired product.

[0064] Preferred fired products produced using the saggers 1 and 2 of the first and second embodiments include, for example, inorganic oxides such as alumina, zirconia, silica, titania, magnesia, and spinel. When the fired product produced using the saggers 1 and 2 is an inorganic oxide, it is particularly preferable to produce the fired product using a method of firing the material to be fired in the presence of a known molybdenum compound such as molybdenum trioxide. This is because impurities derived from the material forming the main body 10 of the saggers 1 and 2 are less likely to mix into the material to be fired, so that the reaction between the material to be fired as a flux of the molybdenum compound and the material to be fired can function effectively without being inhibited by the impurities, and a higher-quality inorganic oxide can be stably produced.

[0065] (Method for producing fired product) The method for manufacturing a fired product according to this embodiment is a method of putting a material to be fired into the main bodies 10 of the saggers 1 and 2 of the first and second embodiments described above, firing the material to be fired, and manufacturing a fired product. The method for manufacturing a fired product according to this embodiment can be suitably used when manufacturing an inorganic oxide as the fired product. In particular, it can be suitably used as a method of putting a material to be fired together with a molybdenum compound into the main bodies 10 of the saggers 1 and 2 of the first and second embodiments, firing the material to be fired in the presence of the molybdenum compound, and manufacturing a fired product made of an inorganic oxide. As the molybdenum compound, known compounds such as molybdenum trioxide can be used.

[0066] In the method for manufacturing a fired product according to this embodiment, since the material to be fired is put into the main bodies 10 of the saggers 1 and 2 of the first and second embodiments and the material to be fired is fired, impurities derived from the material forming the main body 10 are less likely to be mixed into the material to be fired, and the material forming the main body 10 and the material to be fired are less likely to react, and a high-quality fired product can be manufactured. In the method for manufacturing a fired product according to this embodiment, in order to prevent damage to the saggers 1 and 2, it is not necessary to slow down the heating rate and the cooling rate when manufacturing the fired product, so the degree of freedom of the firing conditions is high, and a high-quality fired product can be efficiently manufactured under the optimum firing conditions when manufacturing the fired product.

[0067] In the method for manufacturing a fired product according to this embodiment, the material to be fired is put into the main bodies 10 of the saggers 1 and 2 of the first and second embodiments, and the material to be fired is fired. In the saggers 1 and 2 of the first and second embodiments, the nanoparticles contained in the coating layer 20 are sintered to form a sintered body, and the film-forming components are removed to form a coating sintered layer 30. For this reason, it is presumed that the surface roughness of the surface of the sagger in contact with the material to be fired is reduced as compared with a sagger in which the coating sintered layer 30 is not formed. As a result, the fired product does not strongly adhere to the saggers 1 and 2 when taken out. Therefore, the method for manufacturing a fired product according to this embodiment is excellent in the removability of the fired product.

[0068] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, each configuration and their combinations in each embodiment are examples, and additions, omissions, substitutions, and other changes of the configuration are possible without departing from the spirit of the present invention.

[0069] (Other examples) In the above-described embodiment, as a preferred example of the present invention, the case where the coating layer 20 is formed on the entire surface of the main body 10 has been described as an example. However, the coating layer 20 in the crucible of the present invention may be formed on at least the contact surface of the surface of the main body 10 that contacts the material to be fired. Therefore, the coating layer 20 may be formed, for example, only in the region of the inner surface 11 that contacts the material to be fired, or may be formed only on the entire inner surface 11, and may not be formed on the outer surface 12 of the main body 10. When the coating layer 20 is formed only on a part of the surface of the main body 10, as a method of applying the coating agent containing nanoparticles, for example, it is preferable to use a method using a brush or a method using a spray.

[0070] Further, in the above-described embodiment, as a preferred example of the present invention, the case where the coating sintered layer 30 is formed on the entire surface of the main body 10 has been described as an example. However, the coating sintered layer 30 in the crucible of the present invention may be formed on at least the contact surface of the surface of the main body 10 that contacts the material to be fired, similarly to the coating layer 20.

Example

[0071] Hereinafter, the present invention will be described more specifically with reference to examples. Note that the present invention is not limited only to the following examples.

[0072] [Example 1] A main body (crucible; manufactured by Maruei Sangyo Co., Ltd., NA) made of mullite, having a square outer shape with a side length of 150 mm in plan view, a porosity of 27% by volume, and having a recess with a length of 130 mm, a width of 130 mm, and a depth of 40 mm was prepared.

[0073] (Preparation of Coating Agent) Next, the coating agent of Example 1 containing alumina with an average particle diameter of primary particles as nanoparticles of 40 nm, water as a dispersion medium, and hydroxypropyl cellulose (HPC-L manufactured by Nippon Soda Co., Ltd.; molecular weight 140,000) as a film-forming component was manufactured by the method shown below.

[0074] To 500 g of a colloidal alumina aqueous dispersion (manufactured by Nissan Chemical Industries, Ltd.; AS520A) containing 20% by mass (solid content concentration) of colloidal alumina, 500 g of ion-exchanged water was added to prepare 1000 g of a nanoparticle aqueous dispersion containing 10% by mass of colloidal alumina. 980 g of ion-exchanged water was stirred using a magnetic stirrer, and 20 g of hydroxypropyl cellulose was gradually added to the stirred ion-exchanged water to prepare 1000 g of an aqueous solution of a water-soluble polymer containing 2% by mass of hydroxypropyl cellulose.

[0075] Thereafter, the nanoparticle aqueous dispersion was stirred using a magnetic stirrer, and the aqueous solution of the water-soluble polymer was gradually added to the stirred nanoparticle aqueous dispersion and mixed and stirred to produce 2000 g of the coating agent of Example 1 containing 5% by mass of colloidal alumina and 1% by mass of hydroxypropyl cellulose.

[0076] The coating agent of Example 1 thus obtained was applied to the entire surface of the main body with a brush. Thereafter, the main body coated with the coating agent was placed in an oven set at 120 °C and dried. By performing the above steps, a coating layer made of a coating film was formed on the entire surface of the main body, and the crucible of Example 1 was obtained.

[0077] Next, 80 g of aluminum hydroxide (BF-013, manufactured by Nippon Light Metal Co., Ltd.), which is the material to be fired, and 0.40 g of silicon dioxide (VN3, manufactured by Tosoh Silica Corporation) were placed in a bag made of a resin film together with 8.0 g of molybdenum trioxide (manufactured by Nippon Inorganic Chemical Industry Co., Ltd.), which is a molybdenum compound as a flux, and shaken for 5 minutes to mix them, thereby obtaining a mixture. The mixture thus obtained was placed in the main body of the crucible of Example 1 and fired under the firing conditions shown below to produce the fired product of Example 1 together with a coating sintered layer made of alumina.

[0078] (Firing conditions) In an air atmosphere, the temperature was raised from room temperature to 1000 °C at a rate of 5 °C / min, held at 1000 °C for 5 hours, and then allowed to cool to room temperature.

[0079] [Example 2] A coating layer made of a coating film was formed on the entire surface of the main body in the same manner as in Example 1, except that the coating agent of Example 1 was placed in a container and the main body was immersed in the coating agent for 5 minutes to apply it, thereby obtaining the crucible of Example 2. Thereafter, the fired product of Example 2 was produced in the same manner as in Example 1, except that the crucible of Example 2 was used instead of the crucible of Example 1, together with a coating sintered layer made of alumina.

[0080] [Example 3] A coating layer made of a coating film was formed on the entire surface of the main body in the same manner as in Example 1, except that the coating agent of Example 1 was applied to the entire surface of the main body using a spray, thereby obtaining the crucible of Example 3. Thereafter, the fired product of Example 3 was produced in the same manner as in Example 1, except that the crucible of Example 3 was used instead of the crucible of Example 1, together with a coating sintered layer made of alumina.

[0081] [Example 4] Except that the coating agent of Example 4 produced by the method shown below was applied instead of the coating agent of Example 1, a coating layer composed of a coating film was formed on the entire surface of the main body in the same manner as in Example 1, and the crucible of Example 4 was obtained. Thereafter, except that the crucible of Example 4 was used instead of the crucible of Example 1, the fired product of Example 4 was produced in the same manner as in Example 1 together with a coating sintered layer made of alumina.

[0082] (Preparation of Coating Agent) 1000 g of a colloidal alumina aqueous dispersion (manufactured by Nissan Chemical Industries, Ltd.; AS520A) containing 20% by mass (solid content concentration) of colloidal alumina, which is the same as that used in the preparation of the coating agent of Example 1, was used as the nanoparticle aqueous dispersion. Also, 960 g of ion-exchanged water was stirred using a magnetic stirrer, and 40 g of hydroxypropyl cellulose, which is the same as that of the coating agent of Example 1, was gradually added to the stirred ion-exchanged water to prepare 1000 g of a water-soluble polymer aqueous solution containing 4% by mass of hydroxypropyl cellulose.

[0083] Thereafter, the nanoparticle aqueous dispersion was stirred using a magnetic stirrer, and the water-soluble polymer aqueous solution was gradually added to the stirred nanoparticle aqueous dispersion and mixed and stirred to produce 2000 g of the coating agent of Example 4 containing 10% by mass of colloidal alumina and 2% by mass of hydroxypropyl cellulose.

[0084] [Example 5] The fired product of Example 1 was produced together with a coating sintered layer made of alumina. Thereafter, the fired product was taken out from the main body of the crucible, and a mixture, which is the same as that used in the production of the fired product in Example 1, was newly put into the main body and fired under the same firing conditions as in Example 1. In this way, firing and taking out of the fired product were repeated, and the fired product obtained by the 10th firing was used as the fired product of Example 5.

[0085] [Example 6] A main body (sagger; manufactured by Maruei Sangyo Co., Ltd., NA) made of mullite, having a square outer shape in plan view with a side length of 150 mm and a porosity of 27% by volume, and having a recess with a length of 130 mm, a width of 130 mm, and a depth of 40 mm was prepared.

[0086] (Preparation of Coating Agent) Next, a coating agent of Example 6 containing zirconia with an average particle diameter of primary particles as nanoparticles of 80 nm, water as a dispersion medium, and polyvinyl alcohol (W-20N manufactured by Denka Co., Ltd.; molecular weight 88,000) as a film-forming component was produced by the method shown below.

[0087] To 333 g of a colloidal zirconia aqueous dispersion (manufactured by Nissan Chemical Industries, Ltd.; Nano Use ZR-40BL) containing 40% by mass (solid content concentration) of colloidal zirconia, 667 g of ion-exchanged water was added to prepare 1000 g of a nanoparticle aqueous dispersion containing 13.3% by mass of colloidal zirconia. 980 g of ion-exchanged water was stirred using a magnetic stirrer, and 20 g of polyvinyl alcohol was gradually added to the stirred ion-exchanged water to prepare 1000 g of an aqueous solution of a water-soluble polymer containing 2% by mass of polyvinyl alcohol.

[0088] Thereafter, the nanoparticle aqueous dispersion was stirred using a magnetic stirrer, and the aqueous solution of the water-soluble polymer was gradually added to the stirred nanoparticle aqueous dispersion and mixed and stirred to produce 2000 g of the coating agent of Example 6 containing 6.65% by mass of colloidal zirconia and 1% by mass of polyvinyl alcohol.

[0089] The coating agent of Example 6 thus obtained was applied to the entire surface of the main body with a brush. Thereafter, the main body coated with the coating agent was placed in an oven set at 120°C and dried. By performing the above steps, a coating layer made of a coating film was formed on the entire surface of the main body, and the sagger of Example 6 was obtained.

[0090] Next, it was fired under the firing conditions shown below to produce a coating sintered layer made of zirconia. (Firing conditions) In an air atmosphere, the temperature was raised from room temperature to 1100°C at a rate of 5°C / min, held at 1100°C for 5 hours, and then cooled to room temperature.

[0091] [Example 7] A main body (sagger; manufactured by Maruei Sangyo Co., Ltd., NA) made of mullite, having a square outer shape with a side length of 150 mm in plan view, a porosity of 27% by volume, and having a recess with a length of 130 mm, a width of 130 mm, and a depth of 40 mm was prepared.

[0092] (Preparation of coating agent) Next, a coating agent for Example 7 containing silica with an average particle diameter of primary particles of 25 nm as nanoparticles, water as a dispersion medium, and hydroxypropyl cellulose (HPC-L: molecular weight 140,000, manufactured by Nippon Soda Co., Ltd.) as a film-forming component was produced by the method shown below.

[0093] 800 g of ion-exchanged water was added to 200 g of a colloidal silica aqueous dispersion (manufactured by Nissan Chemical Industries, Ltd.; Snowtex ST-30) containing 30% by mass (solid content concentration) of colloidal silica to prepare 1000 g of a nanoparticle aqueous dispersion containing 6.0% by mass of colloidal silica. 980 g of ion-exchanged water was stirred using a magnetic stirrer, and 20 g of hydroxypropyl cellulose was gradually added to the stirred ion-exchanged water to prepare 1000 g of an aqueous solution of a water-soluble polymer containing 2% by mass of hydroxypropyl cellulose.

[0094] Thereafter, the nanoparticle aqueous dispersion was stirred using a magnetic stirrer, and the aqueous solution of the water-soluble polymer was gradually added to the stirred nanoparticle aqueous dispersion and mixed and stirred to produce 2000 g of a coating agent for Example 7 containing 3% by mass of colloidal silica and 1% by mass of hydroxypropyl cellulose.

[0095] The coating agent of Example 7 thus obtained was applied to the entire surface of the main body with a brush. Then, the main body coated with the coating agent was placed in an oven set at 120 °C and dried. By performing the above steps, a coating layer composed of a coating film was formed on the entire surface of the main body, and the crucible of Example 7 was obtained. Next, the crucible of Example 7 was fired under the same firing conditions as the crucible of Example 6 to produce a coating sintered layer made of silica.

[0096] [Comparative Example 1] A fired product of Comparative Example 1 was produced in the same manner as in Example 1, except that the crucible prepared as the main body when manufacturing the crucible of Example 1 (crucible; manufactured by Maruei Sangyo Co., Ltd., NA) was used instead of the crucible of Example 1.

[0097] [Comparative Example 2] A crucible of Comparative Example 2 was obtained in the same manner as in Example 1, except that the coating agent of Comparative Example 2 produced by the method shown below was applied instead of the coating agent of Example 1.

[0098] (Preparation of Coating Agent) 1500 g of ion-exchanged water was added to 500 g of a colloidal alumina aqueous dispersion (manufactured by Nissan Chemical Industries, Ltd.; AS520A) containing 20% by mass (solid content concentration) of colloidal alumina, which is the same as that used in the preparation of the coating agent of Example 1, to prepare 2000 g of a nanoparticle aqueous dispersion containing 5% by mass of colloidal alumina, which was used as the coating agent of Comparative Example 2.

[0099] In Comparative Example 2, by drying the main body coated with the coating agent, most of the coating layer composed of the coating film did not adhere to the surface of the main body and peeled off. Therefore, in the crucible of Comparative Example 2, a coating layer composed of a coating film containing no film-forming components was formed only on a part of the surface of the main body.

[0100] Thereafter, a fired product of Comparative Example 2 was produced in the same manner as in Example 1, except that the crucible of Comparative Example 2 was used instead of the crucible of Example 1. In Comparative Example 2, the coating layer peeled off from the surface of the main body by manufacturing the fired product. Therefore, in Comparative Example 2, it was not possible to form a coating sintered layer on the surface of the main body by manufacturing the fired product.

[0101] [Comparative Example 3] A crucible of Comparative Example 3 was obtained in the same manner as in Example 1, except that the coating agent of Comparative Example 3 manufactured by the method shown below was applied instead of the coating agent of Example 1. Thereafter, a fired product of Comparative Example 3 was manufactured in the same manner as in Example 1, except that the crucible of Comparative Example 3 was used instead of the crucible of Example 1.

[0102] (Preparation of coating agent) 990 g of ion-exchanged water was stirred using a magnetic stirrer, and 10 g of hydroxypropyl cellulose, which was the same as that used in the preparation of the coating agent of Example 1, was gradually added to the stirred ion-exchanged water to prepare 1000 g of an aqueous polymer solution containing 1% by mass of hydroxypropyl cellulose, which was used as the coating agent of Comparative Example 3.

[0103] In Comparative Example 3, the coating layer thermally decomposed and disappeared by manufacturing the fired product. Therefore, in Comparative Example 3, it was not possible to form a coating sintered layer on the surface of the main body by manufacturing the fired product.

[0104] Table 1 shows the film-forming components, nanoparticles, molecular weights of the film-forming components, contents of the film-forming components in the coating agent, contents of the nanoparticles in the coating agent, and coating methods used when manufacturing the crucibles of Examples 1 to 7 and Comparative Examples 1 to 3.

[0105]

Table 1

[0106] The average particle diameters of the primary particles of the nanoparticles contained in the coating layers of Examples 1 to 7, Comparative Example 2, and Comparative Example 3 were measured by the methods shown below, respectively.

[0107] (Method for measuring the average particle diameter of the primary particles of the nanoparticles) The colloidal alumina used in the coating agents of Examples 1 to 5, Comparative Example 2, and Comparative Example 3 was observed at a magnification of 100,000 times using a transmission electron microscope (TEM) (product name: JEM-1400; manufactured by JEOL Ltd.). Then, the average particle diameters of 30 or more alumina particles in the field of view were measured, and the average value was calculated to obtain the average particle diameter of the primary particles of the nanoparticles contained in the coating layer. As a result, the average particle diameters of the primary particles of the nanoparticles contained in the coating layers of Examples 1 to 5, Comparative Example 2, and Comparative Example 3 were all 40 nm.

[0108] Also, regarding the colloidal zirconia used in the coating agent of Example 6 and the colloidal silica used in the coating agent of Example 7, they were observed using a transmission electron microscope (TEM) in the same manner as the colloidal alumina used in the coating agent of Example 1, and in the same manner as Example 1, the average particle diameter of the primary particles of the nanoparticles contained in the coating layer was determined. As a result, the average particle diameter of the primary particles of the nanoparticles contained in the coating layer of Example 6 was 80 nm, and the average particle diameter of the primary particles of the nanoparticles contained in the coating layer of Example 7 was 25 nm.

[0109] Also, test crucibles were manufactured in the same manner as the crucibles of Examples 1 to 7, Comparative Example 2, and Comparative Example 3. Then, for the test crucibles of Examples 1 to 7 and Comparative Example 3, excluding Comparative Example 2 in which the coating layer peeled off from the main body, the thickness of the coating layer was measured by the methods shown below, respectively.

[0110] (Method for measuring the thickness of the coating layer) For the test crucibles of Examples 1 to 5 and Comparative Example 3, the cross-sections of the fragments were analyzed using SEM (scanning electron microscope) - EDS (energy dispersive X-ray analyzer) (product name; JCM-7000; manufactured by JEOL Ltd.) to obtain elemental maps. Assuming that the region composed of Al, O, and C in the elemental map is the region where the coating layer is formed, the thicknesses at three locations within the field of view were measured, and the average value was calculated to obtain the thickness of the coating layer for Examples 1 to 5 and Comparative Example 3. The results are shown in Table 2.

[0111] For the test crucibles of Example 6 and Example 7, the cross-sections of the fragments were analyzed using SEM in the same manner as in Example 1 to obtain elemental maps. In Example 6, assuming that the region composed of Zr and O in the elemental map is the region where the coating layer is formed, and in Example 7, assuming that the region composed of Si and O in the elemental map is the region where the coating layer is formed, the thicknesses at three locations within the field of view were measured, and the average value was calculated to obtain the thickness of the coating layer for each of Example 6 and Example 7. The results are shown in Table 3.

[0112] Also, for the coating sintered layers obtained by manufacturing fired products using the crucibles of Examples 1 to 5 and Comparative Examples 1 to 3, and the coating sintered layers obtained by firing the crucibles of Example 6 and Example 7 at 1100 °C for 5 hours without putting the fired product, the thicknesses were measured by the methods shown below.

[0113] (Method for measuring the thickness of the coating sintered layer) Excluding Comparative Examples 2 and 3 where the coating sintered layer could not be formed, the fired product was taken out from the crucibles of Examples 1 to 5, the crucibles were broken, and the cross-sections of the fragments were analyzed using SEM (scanning electron microscope) - EDS (energy dispersive X-ray analyzer) (product name JCM-7000;; manufactured by JEOL Ltd.) to obtain elemental maps. Assuming that the region composed of Al and O in the elemental map is the region where the coating sintered layer is formed, the thicknesses at three locations within the field of view were measured, and the average value was calculated to obtain the thickness of the coating sintered layer. The results are shown in Table 2.

[0114] The fired saggers of Example 6 and Example 7 were broken, and the fragment cross-sections were analyzed using SEM in the same manner as in Example 1 to obtain elemental maps. In Example 6, the regions composed of Zr and O in the elemental map, and in Example 7, the regions composed of Si and O in the elemental map were regarded as the regions where the coating sintered layer was formed. The thicknesses at three locations within the field of view were measured, and the average value was calculated to obtain the thickness of the coating sintered layer for each of Example 6 and Example 7. The results are shown in Table 3.

[0115] The fired products of Examples 1 to 5 and Comparative Examples 1 to 3 were each visually observed to examine the presence or absence of a shiny feeling. The results are shown in Table 2.

[0116] In addition, the fired products of Examples 1 to 5 and Comparative Examples 1 to 3 were each observed at 1000 times magnification using a scanning electron microscope (SEM) (product name: JCM-7000; manufactured by JEOL Ltd.). As a result, it was confirmed that the fired products of Examples 1 to 5 and Comparative Examples 1 to 3 were all aggregates of plate-shaped alumina particles. Also, for 30 or more plate-shaped alumina particles within the field of view, the number of fine powders adhering to the surface of one plate-shaped alumina particle was measured, and the average value was calculated and evaluated according to the criteria shown below. The results are shown in Table 2.

[0117] The fine powders adhering to the surface of the plate-shaped alumina particles are presumed to be generated as a result of impurities derived from the material forming the main body of the sagger being mixed into the material to be fired and the reaction as a flux of the molybdenum compound being inhibited by the impurities when the material to be fired is fired.

[0118] [Evaluation Criteria] ○: The average value of the number of fine powders adhering to the surface of the plate-shaped alumina particles is 5 or less △: The average value of the number of fine powders adhering to the surface of the plate-shaped alumina particles is 6 or more and 20 or less ×: The average value of the number of fine powders adhering to the surface of the plate-shaped alumina particles is 21 or more

[0119]

Table 2

[0120] [Table 3]

[0121] As shown in Table 2, the fired products of Examples 1 to 5 had a brilliance. Also, as shown in Table 2, the fired products of Examples 1 to 5 were all plate-shaped alumina particles, and the average value of the number of fine powders adhering to the surface was 5 or less, which was very small.

[0122] On the other hand, as shown in Table 2, the fired products of Comparative Examples 1 to 3 had no brilliance. Also, as shown in Table 2, the fired products of Comparative Examples 1 to 3 were all plate-shaped alumina particles. However, the average value of the number of fine powders adhering to the surface of the plate-shaped alumina particles in the fired products of Comparative Examples 1 to 3 was 21 or more, which was very large.

[0123] Also, a small amount of the fired product of Example 1 was dispersed in water, and the particle size distribution was examined using a laser diffraction type particle size distribution analyzer (MasterSizer 3000; manufactured by Malvern). As a result, the fired product of Example 1 had a sufficiently small variation in particle size. This is presumably because in Example 1, impurities derived from the material forming the main body of the sagger were less likely to mix into the material to be fired, so that the reaction as a flux of the molybdenum compound functioned effectively without being inhibited by the impurities. As a result, the number of fine particles in the middle of the reaction inhibited by the impurities became extremely small, and it is presumed that the inorganic oxide was stably produced.

Explanation of symbols

[0124] 1, 2: Sagger, 10: Main body, 11: Inner surface, 12: Outer surface, 20: Coating layer, 30: Coating sintered layer.

Claims

1. It comprises an inorganic material, a main body for accommodating the material to be fired, and a coating layer formed on at least the contact surface of the main body surface that contacts the material to be fired. The coating layer has primary particles with an average particle diameter of 1 nm or more and 100 nm or less, and is a crucible containing nanoparticles composed of one or more selected from alumina, hydrated alumina, zirconia, hydrated zirconia, silica, titania, hydrated titania, magnesia, spinel, and garnet, and a film-forming component.

2. The crucible according to claim 1, wherein the thickness of the coating layer is 500 nm or less.

3. The crucible according to claim 1, which is used when firing a material to be fired in the presence of a molybdenum compound to produce an inorganic oxide.

4. The crucible according to claim 1, wherein the porosity of the main body is 25% by volume to 35% by volume.

5. It comprises an inorganic material and has a coating step of forming a coating layer on at least the contact surface of the surface of the main body for accommodating the material to be fired that contacts the material to be fired. The coating step includes a coating step of forming a coating layer composed of a coating film by applying a coating agent containing nanoparticles composed of one or more selected from alumina, hydrated alumina, zirconia, hydrated zirconia, silica, titania, hydrated titania, magnesia, spinel, and garnet with an average primary particle diameter of 1 nm or more and 100 nm or less and a film-forming component to at least the contact surface of the main body surface. A method for manufacturing a crucible.

6. The method for manufacturing a crucible according to claim 5, wherein the film-forming component is a water-soluble polymer.

7. The method for manufacturing a crucible according to claim 6, wherein the water-soluble polymer is hydroxypropyl cellulose.

8. The method for manufacturing a crucible according to claim 7, wherein the water-soluble polymer is hydroxypropyl cellulose having a mass average molecular weight of 40,000 to 200,000.

9. The method for manufacturing a crucible according to claim 5, wherein the nanoparticles are composed of one or two selected from alumina and hydrated alumina.

10. The method for manufacturing a crucible according to claim 5, wherein the porosity of the main body is 25% by volume to 35% by volume.

11. It comprises an inorganic material, a main body for accommodating the material to be fired, and a coating sintered layer formed on at least the contact surface of the surface of the main body that contacts the material to be fired. The coating sintered layer has a thickness of 50 nm to 500 nm and includes a sintered body of particles composed of one or more selected from alumina, hydrated alumina, zirconia, hydrated zirconia, silica, titania, hydrated titania, magnesia, spinel, and garnet. The sagger.

12. A step of forming a coating layer on at least the contact surface that contacts the material to be fired, among the surfaces of the main body made of an inorganic material and containing the material to be fired, wherein the average particle diameter of the primary particles is 1 nm or more and 100 nm or less. A coating agent containing nanoparticles composed of one or more selected from alumina, hydrated alumina, zirconia, hydrated zirconia, silica, titania, hydrated titania, magnesia, spinel, and garnet, and a film-forming component is applied to at least the contact surface of the surface of the main body. A coating step of forming a coating layer made of a coating film; A method for manufacturing a sagger, comprising a sintering step of sintering the nanoparticles contained in the coating layer.

13. The method for manufacturing a sagger according to claim 12, wherein in the sintering step, the material to be fired is placed in the main body on which the coating layer is formed and heated to obtain a fired product of the material to be fired.

14. The method for manufacturing a sagger according to claim 13, wherein the nanoparticles and the fired product contain the same compound.

15. A method for manufacturing a fired product, wherein the material to be fired is placed in the main body of the sagger according to any one of claims 1 to 4, and the material to be fired is fired to manufacture a fired product.

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