Insulating tiles and multi-layer insulation materials

Abstract

To provide a heat-resistant tile that exhibits high thermal insulation and high durability even in processing temperature ranges exceeding 2300°C, and a multilayer thermal insulation material equipped with the same. [Solution] The thermal insulation tile comprises a base material A made of porous carbon and a coating layer containing a high-melting-point metal carbide formed on at least one surface of the base material A, wherein the coating layer has a relative density of 95% or more. The multilayer thermal insulation material comprises a base material B made of a molded thermal insulation material containing carbon fibers and thermal insulation tiles disposed on the surface of the base material B, wherein the thermal insulation tiles are disposed on the surface of the base material B such that the coating layer faces the external atmosphere.

Description

[Technical Field]

[0001] The present invention relates to thermal insulation tiles and multilayer thermal insulation materials, and more particularly to thermal insulation tiles with excellent thermal insulation properties and durability, and multilayer thermal insulation materials equipped therewith. [Background technology]

[0002] SiC single crystals and AlN single crystals are generally manufactured using the sublimation method. Here, "sublimation method (also called sublimation recrystallization method or sublimation reprecipitation method)" refers to a method in which a sublimation raw material is sublimated and the sublimation gas is re-deposited (condensed) on the surface of a seed crystal.

[0003] The growth of single crystals using the sublimation method is generally carried out by placing a susceptor to which a seed crystal is attached above a crucible filled with sublimation material, and heating the seed crystal and sublimation material to a predetermined temperature using a graphite heater. At this time, insulating material is placed around the graphite heater to improve the thermal insulation of the growth space. Because the growth environment for single crystals is harsh, the various components used in single crystal growth require high durability. For this reason, various proposals have been made regarding the various components used in such single crystal growth.

[0004] For example, Patent Document 1 discloses a high-temperature crucible obtained by applying a slurry containing TaC to the surface of a substrate made of isotropic graphite and sintering the coating film. The document states: (a) When SiC single crystals are grown using a graphite crucible by sublimation, the surface of the graphite crucible becomes very rough due to the SiC sublimation gas, and amorphous graphite particles tend to be mixed into the grown crystal, and (b) When a SiC single crystal was grown by sublimation using a high-temperature crucible whose surface was coated with a TaC film, there was no damage to the TaC film, and no amorphous graphite particles were found in the grown crystal. It is stated.

[0005] Patent Document 2 discloses a highly heat-resistant member obtained by forming chamfered portions at the corners and edges of a substrate made of isotropic graphite, applying a slurry containing TaC to the surface of the substrate on which the chamfered portions are formed, and sintering the coating film. The document states that forming chamfered edges on the corners and edges of the substrate can suppress lifting and cracking of the TaC coating.

[0006] Patent Document 3 discloses a heat-resistant graphite member obtained by applying a slurry containing TaC to the surface of a substrate made of isotropic graphite having a thermal expansion coefficient and bulk density within a predetermined range, and then sintering the coating film. The document states that using isotropic graphite with a thermal expansion coefficient and bulk density within a specified range as the base material makes surface cracks and delamination less likely to occur in the TaC coating.

[0007] The heat-resistant materials described in Patent Documents 1 to 3 are primarily intended for use in crucibles, susceptors, heaters, etc., for holding objects to be heated. Therefore, the base material used is dense (porosity less than 15%), has high thermal conductivity (100-150 W / (m·K)), and isotropic graphite (CIP molded material) that is not anisotropic.

[0008] On the other hand, for heat treatment at high temperatures exceeding 2000°C in an inert atmosphere, and for the growth of SiC single crystals, heating furnaces consisting of a combination of a resistance heating type or high-frequency heating type graphite heater and molded insulation material made of graphite fiber are used. The molded insulation material made of graphite fiber is worn down by sublimation due to exposure to high temperatures, corrosion by corrosive gases (e.g., Si vapor), and plasma damage due to electrode discharge. In particular, in the processing temperature range exceeding 2300°C, even graphite has a high equilibrium vapor pressure (0.3 Pa or more), so the insulation material is consumed at an accelerating rate. As a result, the material cost and maintenance cost of the insulation material increase, which in turn contributes to the increase in the cost of the product. [Prior art documents] [Patent Documents]

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0010] The problem to be solved by the present invention is to provide a heat-resistant tile that exhibits high heat insulation and high durability even in a processing temperature range exceeding 2300°C. Another problem to be solved by the present invention is to provide a multilayer heat insulation material provided with such a heat-resistant tile.

Means for Solving the Problems

[0011] To solve the above problems, the heat insulation tile according to the present invention comprises a base material A made of porous carbon, and a coating layer containing a high melting point metal carbide formed on at least one surface of the base material A and is provided with the coating layer has a relative density of 95% or more. However, the "porous carbon" refers to a sintered body of carbon having a bulk density of 1.1 g / cm 3 or more and 1.6 g / cm 3 or less, the "high melting point metal carbide" refers to a carbide containing at least one metal having a melting point of 2000°C or more.

[0012] The multilayer heat insulation material according to the present invention comprises a base material B made of a formed heat insulation material containing carbon fibers, and a heat insulation tile according to the present invention disposed on the surface of the base material B and is provided with the heat insulation tile is disposed on the surface of the base material B such that the coating layer faces the external atmosphere side. At least one of the heat insulating tiles is preferably disposed on the surface of the high temperature side of the base material B so that the coating layer is on the high temperature side.

Advantages of the Invention

[0013] When a coating layer made of a high melting point metal carbide is formed on the surface of the base material A made of porous carbon, a heat insulating tile excellent in durability in a high temperature corrosion environment can be obtained. When such a heat insulating tile is disposed on the outer atmosphere side (particularly, the high temperature side) of the base material B made of a molded heat insulating material, the loss of the base material B can be suppressed. Furthermore, in a multilayer heat insulating material in which a heat insulating tile is disposed on the surface of the base material B, when the thickness of the base material A is optimized, not only the loss of the base material B is suppressed, but also the heater power required to heat an object to be heated to a predetermined temperature can be reduced.

Brief Description of the Drawings

[0014] [Figure 1] FIG. 1(A) is a SEM image of the TaC coating layer surface of the heat insulating tile (TaC-coated porous carbon). FIG. 1(B) is a SEM image of the fracture surface of the heat insulating tile. [Figure 2] Equilibrium vapor pressure data of carbon vapor on the graphite surface and fitting results by the Antoine equation. [Figure 3] FIG. 3(A) is a two-dimensional axisymmetric model for computer simulation of an electric furnace provided with a single-layer heat insulating material composed only of a molded heat insulating material. FIG. 3(B) is a two-dimensional axisymmetric model for computer simulation of an electric furnace provided with a multilayer heat insulating material composed of a combination of a heat insulating tile (TaC-coated porous carbon) and a molded heat insulating material.

[0015] [Figure 4] It is a diagram showing the relationship between the thickness of the heat insulating tile (≒ the thickness of the base material A) and the heater power required for the surface temperature of the heater to reach 2400°C in the multilayer heat insulating material of Example 2 (k = 1.1 W / (m·K), t1 = 100 mm). [Figure 5]This figure shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the edge temperature of the molded insulation material when the heater surface temperature is 2400°C, in the multilayer insulation material of Example 2 (k=1.1W / (m·K), t1=100mm). [Figure 6] This figure shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the carbon vapor pressure ratio at the insulation tile / molded insulation interface when the heater surface temperature is 2400°C, in the multilayer insulation material of Example 2 (k=1.1W / (m·K), t1=100mm).

[0016] [Figure 7] This figure shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the heater power required to reach a heater surface temperature of 2400°C in the multilayer insulation material of Example 3 (k=3.0W / (m·K), t1=100mm). [Figure 8] This figure shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the edge temperature of the molded insulation material when the heater surface temperature is 2400°C, in the multilayer insulation material of Example 3 (k=3.0W / (m·K), t1=100mm). [Figure 9] This figure shows the relationship between the thickness of the multilayer insulation material (≈thickness of base material A) and the carbon vapor pressure ratio at the insulation tile / molded insulation material interface when the heater surface temperature is 2400°C, in the multilayer insulation material of Example 3 (k=3.0W / (m·K), t1=100m).

[0017] [Figure 10] This figure shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the heater power required to reach a heater surface temperature of 2400°C in the multilayer insulation material of Example 4 (k=10.0W / (m·K), t1=100mm). [Figure 11] This figure shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the edge temperature of the molded insulation material when the heater surface temperature is 2400°C, in the multilayer insulation material of Example 4 (k=10.0W / (m·K), t1=100mm). [Figure 12]This figure shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the carbon vapor pressure ratio at the insulation tile / molded insulation material interface when the heater surface temperature is 2400°C, in the multilayer insulation material of Example 4 (k=10.0W / (m·K), t1=100mm).

[0018] [Figure 13] This figure shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the heater power required to reach a heater surface temperature of 2400°C in the multilayer insulation material of Comparative Example 1 (k=150.0W / (m·K), t1=100mm). [Figure 14] This figure shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the edge temperature of the molded insulation material when the heater surface temperature is 2400°C, in the multilayer insulation material of Comparative Example 1 (k=150.0W / (m·K), t1=100mm). [Figure 15] This figure shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the carbon vapor pressure ratio at the insulation tile / molded insulation material interface when the heater surface temperature is 2400°C, in the multilayer insulation material of Comparative Example 1 (k=150.0W / (m·K), t1=100mm).

[0019] [Figure 16] This figure shows the relationship between the thermal conductivity of base material A, the required thickness of base material A (the lower limit of the thickness of base material A required to keep the carbon vapor pressure ratio below 0.6), and the required heater power ratio when the total thickness of the multi-layer insulation material is 100 mm. [Figure 17] This figure shows the relationship between the total thickness of the multilayer insulation material, the required thickness of base material A (the lower limit of the thickness of base material A required to keep the carbon vapor pressure ratio below 0.6), and the maximum thickness of base material A (the upper limit of the thickness of base material A required to keep the required heater power ratio below 100%), when the thermal conductivity of base material A is 1.1 W / (m·K).

[0020] [Figure 18]This figure shows the relationship between the total thickness of the multilayer insulation material, the required thickness of base material A (the lower limit of the thickness of base material A required to keep the carbon vapor pressure ratio below 0.6), and the maximum thickness of base material A (the upper limit of the thickness of base material A required to keep the required heater power ratio below 100%), when the thermal conductivity of base material A is 3.0 W / (m·K). [Figure 19] This figure shows the relationship between the total thickness of the multilayer insulation material, the required thickness of base material A (the lower limit of the thickness of base material A required to keep the carbon vapor pressure ratio below 0.6), and the maximum thickness of base material A (the upper limit of the thickness of base material A required to keep the required heater power ratio below 100%), when the thermal conductivity of base material A is 10.0 W / (m·K).

[0021] [Figure 20] This figure shows the dependence of the slope a1 and y-intercept b1 of the linear regression equation, which represents the required thickness of base material A (the lower limit of the thickness of base material A required to keep the carbon vapor pressure ratio below 0.6), on the thermal conductivity of base material A. [Figure 21] This figure shows the dependence of the coefficients a2 and b2 of the quadratic regression equation, which represent the maximum thickness of base material A (the upper limit of the thickness of base material A required to keep the required heater power ratio below 100%), on the thermal conductivity of base material A. [Figure 22] This figure shows an example of a structure in which the thermal insulation tile and multilayer thermal insulation material according to the present invention are applied to SiC crystal growth. [Modes for carrying out the invention]

[0022] [Configuration 1] A substrate A made of porous carbon, A coating layer containing a high melting point metal carbide is formed on at least one surface of the substrate A. Equipped with, The coating layer has a relative density of 95% or more. Insulating tiles. however, The aforementioned "porous carbon" has a bulk density of 1.1 g / cm³. 3 More than 1.6g / cm 3 The following refers to a sintered carbon body: The aforementioned "high melting point metal carbide" refers to a carbide containing at least one metal with a melting point of 2000°C or higher.

[0023] [Configuration 2] The thermal insulation tile according to configuration 1, wherein the thickness of the coating layer is 20 μm or more and 200 μm or less.

[0024] [Configuration 3] The thermal insulation tile according to configuration 1 or 2, wherein the thickness of the base material A is 4.0 mm or more and 45.0 mm or less.

[0025] [Structure 4] The aforementioned high-melting-point metal carbide is a thermal insulation tile according to any one of configurations 1 to 3, comprising TaC.

[0026] [Composition 5] (a) A protective material for protecting the surface of a base material B made of a molded insulating material containing carbon fibers, or (b) A heat shield plate placed between the crucible filled with sublimation material and the base for holding the seed crystal, to prevent radiant heat from the crucible, which is heated to a high temperature, from directly reaching the seed crystal. An insulating tile described in any one of configurations 1 to 4 used as such.

[0027] [Composition 6] A base material B consisting of a molded insulation material containing carbon fiber, An insulating tile according to any one of configurations 1 to 5 arranged on the surface of the base material B, Equipped with The insulating tile is positioned on the surface of the substrate B such that the coating layer faces the external atmosphere. Multilayer insulation material.

[0028] [Composition 7] The multilayer thermal insulation material according to configuration 6, wherein at least one of the thermal insulation tiles is placed on the high-temperature side surface of the substrate B such that the coating layer is on the high-temperature side.

[0029] [Structure 8] A multilayer insulation material according to configuration 6 or 7 such that the following relationship (1) holds true. a1 × t1 + b1 ≤ t2 ≤ a2 × t1 2 +b² × t¹…(1) however, t1 is the total thickness (mm) of the multilayer insulation material. t2 is the thickness (mm) of the base material A included in the heat insulating tile. a1=-0.0014907+0.41177×[1-exp(-0.1037k)], b1=-2.6021+3.055×exp(-0.33985k), a2=0.0013938+0.0089152×exp(-0.72719k), b2=-0.25756+0.39576×[1-exp(-0.55089k)], k is the thermal conductivity (W / (m·K)) of the substrate A at room temperature.

[0030] [Composition 9] The aforementioned substrate A has a thermal conductivity of 1.1 ± 0.9 W / (m·K) at room temperature. The thickness ratio of the base material A is 4.0% or more and 45.0% or less. A multilayer insulation material as described in configuration 6 or 7. However, the "thickness ratio of base material A" refers to the ratio of the thickness t2 of base material A to the total thickness t1 of the multilayer insulation material (= t2 × 100 / t1).

[0031] [Configuration 10] The aforementioned substrate A has a thermal conductivity of 3.0 ± 1.0 W / (m·K) at room temperature. The thickness ratio of the base material A is 10.0% or more and 30.0% or less. A multilayer insulation material as described in configuration 6 or 7. However, the "thickness ratio of base material A" refers to the ratio of the thickness t2 of base material A to the total thickness t1 of the multilayer insulation material (= t2 × 100 / t1).

[0032] One embodiment of the present invention will be described in detail below. [1. Insulating Tiles] The heat-insulating tile according to the present invention is A substrate A made of porous carbon, A coating layer containing a high melting point metal carbide is formed on at least one surface of the substrate A. It is equipped with.

[0033] [1.1. Base material A] [1.1.1. Materials] Substrate A consists of porous carbon. "Porous carbon" refers to a material with a bulk density of 1.1 g / cm³. 3 More than 1.6g / cm 3 The following refers to a sintered carbon body. The above bulk density corresponds to a porosity of 50% to 23%.

[0034] [1.1.2. Shape] The shape of base material A is not particularly limited, and the optimal shape can be selected according to the purpose. The shapes of base material A include: (a) Flat boards such as square boards, rectangular boards, triangular boards, hexagonal boards, (b) A multifaceted plate, such as a semi-square tube, in which multiple flat plates are combined in a three-dimensional manner. (c) Curved plates such as semi-cylindrical, hemispherical shells, hollow semi-cones, and hollow cones. These are some examples.

[0035] [1.1.3. Thickness] The thickness of base material A is not particularly limited, and the optimal thickness can be selected according to the purpose. However, as will be described later, when insulating tiles are placed on the surface of base material B, which is made of molded insulating material, to form a multilayer insulating material, and the multilayer insulating material is used as insulating material for a single crystal growth apparatus, the thickness of base material A affects the heater power required to heat the object to be heated to a predetermined temperature and the lifespan of base material B.

[0036] When the heat-insulating tile according to the present invention is placed on the high-temperature surface of a base material B made of molded heat-insulating material, the thinner the thickness of the base material A, the less heater power is required to obtain the same heater surface temperature. This is thought to be because the emissivity of the coating layer is smaller than that of the molded heat-insulating material. However, if the thickness of base material A becomes too thin, the wear of base material B increases rapidly. This is thought to be because when the thickness of base material A decreases, the temperature at the thermal insulation tile / base material B interface increases, making it easier for carbon to volatilize from base material B. To suppress the wear of base material B, the thickness of base material A is preferably 4.0 mm or more. More preferably, the thickness is 6.0 mm or more, 8.0 mm or more, or 10.0 mm or more.

[0037] On the other hand, if the thickness of base material A becomes too thick, the heater power required to obtain the same heater surface temperature increases. This is thought to be because the thermal conductivity of base material A is higher than that of molded insulation material, so the contribution of heat diffusion due to the high thermal conductivity of base material A is greater than the contribution of insulation due to the low emissivity of the coating layer. Therefore, the thickness of base material A is preferably 45.0 mm or less. More preferably, the thickness is 35.0 mm or less, 30.0 mm or less, or 25.0 mm or less.

[0038] [1.1.4. Thermal conductivity] The thermal conductivity of base material A varies depending on its bulk density or porosity. Generally, the lower the bulk density of base material A, the lower its thermal conductivity. To obtain high thermal insulation, a lower thermal conductivity of base material A is desirable. By controlling the bulk density of base material A, its thermal conductivity can be set to between 1.0 W / (m·K) and 10.0 W / (m·K). Further control of the bulk density of base material A can result in a thermal conductivity of 5.0 W / (m·K) or less, or 3.0 W / (m·K) or less.

[0039] [1.2. Covering layer] [1.2.1. Materials] The coating layer contains high-melting-point metal carbides. In this invention, "high melting point metal carbide" means a carbide containing at least one high melting point metal. "High melting point metal" means a metal having a melting point of 2000°C or higher.

[0040] Examples of high-melting-point metals include Ta, W, Re, Mo, Nb, Ir, and Hf. The coating layer may contain one of these high-melting-point metals, or it may contain two or more. Examples of high-melting-point metal carbides include TaC, WC, ReC, Mo2C, NbC, IrC, and HfC. The coating layer may contain one of these high-melting-point metal carbides, or it may contain two or more.

[0041] In particular, TaC is preferred as the high-melting-point metal carbide. This is because TaC has high corrosion resistance, high high-temperature stability, and low emissivity (0.2-0.3). The coating layer may contain only TaC as the high-melting-point metal carbide, or it may contain TaC in addition to other high-melting-point metal carbides. Furthermore, the coating layer may contain other components in addition to the high-melting-point metal carbide (for example, residue from sintering aids).

[0042] [1.2.2. Relative Density] "Relative density" refers to the ratio of the apparent density of the coating layer to its theoretical density. The coating layer functions as a protective material for base material A. Furthermore, when the insulating tile is used as a protective material for multi-layer insulating material, the coating layer also functions as a protective material for base material B, which is made of molded insulating material. To suppress wear and tear on base materials A and B, the relative density of the coating layer must be 95% or higher. More preferably, the relative density is 97% or higher, or 99% or higher.

[0043] Porous carbon has a lower thermal conductivity than conventional graphite materials and can function as an insulator. However, porous carbon has a lower bulk density and higher open porosity than conventional graphite materials, resulting in inferior corrosion resistance and sublimation resistance. In contrast, dense films of high-melting-point metal carbides such as TaC, NbC, HfC, ZrC, WC, and Mo2C exhibit excellent gas impermeability and corrosion resistance. Therefore, coating the surface of porous carbon with a dense film made of high-melting-point metal carbides can compensate for the lack of corrosion resistance and sublimation resistance in porous carbon.

[0044] [1.2.3. Location of coating layer formation] The coating layer is formed on at least one surface of the substrate A. The location where the coating layer is formed is not particularly limited, and the optimal location can be selected depending on the purpose. For example, if the base material A is a flat plate, the coating layer may be formed on only one of the two opposing surfaces of the base material A, or on both. Furthermore, the coating layer may be formed on the side surfaces in addition to one or both of the two opposing surfaces.

[0045] Furthermore, when a coating layer is formed on the surface of substrate A, the coating layer may be formed over the entire surface of substrate A, or it may be formed on only a part of it. Even when the coating layer is formed on only a part of the surface of substrate A, the thermal insulation and corrosion resistance of the area where the coating layer is formed will be higher than those of the area where the coating layer is not formed.

[0046] [1.2.4. Thickness] The thickness of the coating layer is not particularly limited, and the optimal thickness can be selected according to the purpose. Generally, if the thickness of the coating layer is too thin, its function as a protective material will be insufficient, making it difficult to suppress the wear of base material A or base material B. Therefore, the thickness of the coating layer is preferably 20 μm or more. More preferably, the thickness is 30 μm or more, 40 μm or more, or 50 μm or more. On the other hand, if the thickness of the coating layer becomes too thick, cracks may occur in the coating layer, or the coating layer may peel off. Therefore, the thickness of the coating layer is preferably 200 μm or less. More preferably, the thickness is 150 μm or less, or 100 μm or less.

[0047] [1.3. Usage] The heat-insulating tile according to the present invention can be used for various purposes. For example, the heat-insulating tile can be used for: (a) A protective material for protecting the surface of the substrate B, which is made of a molded insulating material containing carbon fiber. (b) A heat shield plate placed between the crucible filled with sublimation material and the base for holding the seed crystal, to prevent radiant heat from the crucible, which is heated to a high temperature, from directly reaching the seed crystal. (c) Semiconductor manufacturing jigs (susceptors, etc.) (d) High-temperature crucible These are some examples.

[0048] [2. Method for manufacturing insulating tiles] The heat-insulating tile according to the present invention is (a) A slurry containing high-melting-point metal carbide powder is applied to the surface of substrate A. (b) Sinter the coating film It can be manufactured by doing so.

[0049] The slurry may contain only high-melting-point metal carbide powder, or it may contain high-melting-point metal carbide in addition to a sintering aid. To obtain a coating layer with high relative density, it is preferable that the slurry contains a sintering aid. Examples of sintering aids include Co, Ti, Cr, Fe, and Ni.

[0050] [3. Multilayer insulation] The multilayer insulation material according to the present invention is A base material B consisting of a molded insulation material containing carbon fiber, The heat insulating tile according to the present invention is arranged on the surface of the substrate B. It is equipped with.

[0051] [3.1. Base material B] [3.1.1. Materials] Base material B consists of a molded insulation material containing carbon fibers. "Molded thermal insulation material" refers to a thermal insulation material obtained by impregnating a carbon fiber base material with a resin that has a high carbonization rate, molding it into the desired shape, and then curing, carbonizing, and graphitizing the molded body. Molded thermal insulation material has high heat resistance and low thermal conductivity, making it suitable as a material for base material B.

[0052] The porous carbon used as the base material A for the insulating tiles has an insulating effect, but its insulating effect is lower compared to molded insulating materials. This is because the thermal conductivity of porous carbon is higher than that of molded insulating materials. The thermal conductivity of commercially available porous carbon at room temperature is about 1-3 W / (m·K). On the other hand, the thermal conductivity of commercially available molded insulating materials at room temperature is about 0.3 W / (m·K), and its bulk density is 0.16 g / cm³. 3 Therefore, it is preferable to use insulating tiles in combination with molded insulation materials rather than using them alone.

[0053] [3.1.2. Shape and Thickness] The shape of base material B is not particularly limited, and the optimal shape can be selected according to the purpose. The thickness of base material B affects the thermal insulation and durability of the multilayer insulation material. The optimal thickness of base material B will be discussed later.

[0054] [3.2. Insulating Tiles] Insulating tiles are A substrate A made of porous carbon, A coating layer containing a high melting point metal carbide is formed on at least one surface of the substrate A. It is equipped with.

[0055] [3.2.1. Base material A] The thermal conductivity and thickness of base material A affect the thermal insulation and durability of the multilayer insulation material. The optimal thermal conductivity and thickness of base material A will be described later. Other points regarding base material A are as described above, so we will omit further explanation.

[0056] [3.2.2. Covering layer] Details of the coating layer are as described above, so we will omit further explanation.

[0057] [3.3. Placement of Insulating Tiles] "The statement that 'insulating tiles are placed on the surface of base material B' means that..." (a) The heat insulation tile is physically in contact with the surface of the base material B, or (b) The base material B and the heat insulation tile are adhered via an adhesive. This is what is referred to.

[0058] When arranging a heat insulation tile on one surface of the base material B, one heat insulation tile may be arranged on one surface of the base material B, or a plurality of heat insulation tiles may be arranged. In particular, when the size of one surface of the base material B is large, it is preferable to spread a plurality of small heat insulation tiles (for example, heat insulation tiles with a side length of several centimeters) on one surface of the base material B.

[0059] The heat insulation tile needs to be arranged on the surface of the base material B such that the coating layer faces the external atmosphere side. This is because when the coating layer is formed only on one side of the heat insulation tile and is arranged on the surface of the base material B such that the coating layer faces the interface side of the heat insulation tile / base material B, the wear of the base materials A and B cannot be suppressed.

[0060] Also, when arranging one or more heat insulation tiles on one or more surfaces of the base material B, at least one heat insulation tile is preferably arranged on the high-temperature side surface of the base material B such that the coating layer faces the high-temperature side. When the heat insulation tile is arranged in this way, at least in that region, the heat insulation property and corrosion resistance are improved. When arranging a plurality of heat insulation tiles on the high-temperature side surface of the base material B, it is preferable that the coating layers of all the heat insulation tiles face the high-temperature side and are arranged on the high-temperature side surface of the base material B.

[0061] [3.4. Total Thickness of Multilayer Heat Insulation Material, Thickness of Base Material A, and Thermal Conductivity of Base Material A] Preferably, the following relational expression represented by the following formula (1) holds among the total thickness t1 of the multilayer heat insulation material, the thickness t2 of the base material A, and the thermal conductivity k of the base material A.

[0062] a1 × t1 + b1 ≤ t2 ≤ a2 × t1 2 + b2 × t1…(1) However, t1 is the total thickness (mm) of the multilayer insulation material. t2 is the thickness (mm) of the base material A included in the heat insulating tile. a1=-0.0014907+0.41177×[1-exp(-0.1037k)], b1=-2.6021+3.055×exp(-0.33985k), a2=0.0013938+0.0089152×exp(-0.72719k), b2=-0.25756+0.39576×[1-exp(-0.55089k)], k is the thermal conductivity (W / (m·K)) of the substrate A at room temperature.

[0063] Equation (1) is an empirical formula obtained through simulation that shows the relationship between t1, t2, and k that simultaneously satisfies the following two conditions. (a) When a graphite heater is surrounded by multi-layer insulation, the heater power required to reach a heater surface temperature of 2400°C is greater than when the graphite heater is surrounded by a single layer of insulation consisting only of molded insulation. (b) The carbon vapor pressure ratio at the interface between the insulating tile and substrate B is 0.6 or less.

[0064] Here, "carbon vapor pressure ratio" refers to the value expressed by the following equation (2). Carbon vapor pressure ratio=p / p0…(2) however, p is the vapor pressure of carbon at the interface between the insulating tile and substrate B when the graphite heater is surrounded by multi-layer insulation and the heater power is adjusted so that the heater surface temperature reaches 2400°C. p0 is the vapor pressure of carbon on the surface of the molded insulation material when the graphite heater is surrounded only by molded insulation material and the heater power is adjusted so that the heater surface temperature reaches 2400°C.

[0065] By optimizing the thickness ratio of base material A according to the thermal conductivity k of base material A so as to satisfy equation (1), it is possible to achieve both high thermal insulation and high durability in multilayer insulation materials. Here, "thickness ratio of base material A" refers to the ratio of the thickness t2 of base material A to the total thickness t1 of the multilayer insulation material (= t2 × 100 / t1).

[0066] For example, if the thermal conductivity of base material A at room temperature is 1.1 ± 0.9 W / (m·K), the thickness ratio of base material A is preferably 4.0% or more and 45.0% or less. Alternatively, if the thermal conductivity of base material A at room temperature is 3.0 ± 1.0 W / (m·K), the thickness ratio of base material A is preferably 10.0% or more and 30.0% or less.

[0067] [4. Effect] When a coating layer made of a high-melting-point metal carbide is formed on the surface of a substrate A made of porous carbon, an insulating tile with excellent durability in high-temperature corrosive environments can be obtained. When such an insulating tile is placed on the external atmosphere side (especially the high-temperature side) of a substrate B made of molded insulating material, wear and tear of the substrate B can be suppressed. Furthermore, in a multilayer insulation material in which insulating tiles are arranged on the surface of base material B, optimizing the thickness of base material A not only suppresses wear and tear on base material B, but also reduces the heater power required to heat the object to be heated to a predetermined temperature.

[0068] More specifically, by placing the insulating tiles on the high-temperature side of the molded insulation material so that the coating layer is on the high-temperature side, the lifespan of the multi-layer insulation material can be expected to be extended. This is because placing the insulating tiles on the high-temperature surface of the molded insulation material improves the durability of the molded insulation material and also lowers the temperature of the molded insulation material. In addition, even if the total thickness of the multi-layer insulation material is the same as that of a single-layer insulation material consisting only of molded insulation material, it is possible to design it to have even higher thermal insulation performance. [Examples]

[0069] (Example 1) [1. Sample Preparation] The porous carbon material is a high-transmission grade porous carbon material manufactured by Tanken Seal Seiko Co., Ltd. (bulk density: 1.2 g / cm³). 3A porosity of 35% and a thermal conductivity of 1.1 W / (m·K) at room temperature were used. A TaC slurry was spray-coated onto one side of a porous carbon substrate A measuring 50 x 40 x 5 mm. After the coating film dried, it was sintered.

[0070] [2. Test Method] [2.1. SEM Observation] SEM observation was performed on thermal insulation tiles (TaC-coated porous carbon).

[0071] [2.2. Calculation of the relationship between carbon vapor pressure and temperature] The relationship between p (Pa) and T (°C), which is necessary to calculate the carbon vapor pressure ratio, was obtained by fitting them to the Antoine equation. The value of the carbon vapor pressure p at temperature T was taken from the data described in Reference 1. [Reference 1] CRC Handbook of Chemistry and Physics, 92nd ed., CRC press, Boca Rato, 2011

[0072] [3. Results] [3.1. SEM Observation] Figure 1(A) shows an SEM image of the surface of the TaC coating layer of an insulating tile (TaC-coated porous carbon). Figure 1(B) shows an SEM image of the fracture surface of the insulating tile. The thickness of the TaC coating layer was approximately 100 μm. Furthermore, despite the relatively thick TaC coating layer, no defects such as cracks or voids were observed in the TaC coating layer.

[0073] [3.2. Relationship between carbon vapor pressure and temperature] Figure 2 shows the equilibrium vapor pressure data of carbon vapor on the graphite surface and the fitting results using the Antoine equation. It was found that the following relationship (3) holds between the carbon vapor pressure p (Pa) on the graphite surface and the temperature T (°C). The carbon vapor pressure ratio was calculated below using equation (3). Log 10 P=14.505-34403 / (-21.771+T(in ℃)) …(3)

[0074] (Examples 2-4, Comparative Example 1) [1. Computer Simulation] The temperature distribution of multi-layer insulation materials, consisting of molded insulation material with insulating tiles placed on its surface, or single-layer insulation materials consisting only of molded insulation material, was determined by computer simulation when used as insulation material in a large high-temperature graphite electric furnace. The computer simulation was performed using the heat transfer module of COMSOL Multiphysics®, manufactured by COMSOL. The thickness of the insulation tile (approximately the thickness t2 of the porous carbon) was set to 1 mm to 50 mm. The total thickness t1 of the molded insulation material and insulation tile was set to 100 mm. Since the thickness of the coating layer is significantly thinner than the thickness t2 of the porous carbon (base material A), the thickness of the insulation tile can be considered the same as the thickness t2 of the porous carbon.

[0075] The thermal conductivity k of porous carbon (substrate A) at room temperature is: (a) 1.1 W / (m·K) (Example 2), (b) 3.0 W / (m·K) (Example 3), or, (c) 10.0 W / (m·K) (Example 4) That's what I decided. In Comparative Example 1, base material A was a general graphite material with a thermal conductivity of 150 W / (m·K) at room temperature and a thermal conductivity of 150 × 300 / T (in K) at high temperatures.

[0076] Figure 3(A) shows a two-dimensional axisymmetric model for computer simulation of an electric furnace equipped with a single-layer insulation consisting only of molded insulation material. Figure 3(B) shows a two-dimensional axisymmetric model for computer simulation of an electric furnace equipped with a multi-layer insulation consisting of a combination of insulating tiles (TaC-coated porous carbon) and molded insulation material. The computer simulation was performed assuming that the heater power was adjusted so that the surface temperature of the graphite heater was 2400°C. The heater power and the edge temperature of the molded insulation material were then determined. Here, "edge temperature of molded insulation material" refers to the interface temperature between the insulation tile and the molded insulation material, or the temperature of the graphite heater side surface of a single-layer insulation material consisting only of molded insulation material.

[0077] [2. Results] [2.1. Example 2] Figure 4 shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the heater power required to reach a heater surface temperature of 2400°C in the multilayer insulation material of Example 2 (k=1.1W / (m·K), t1=100mm). From Figure 4, it can be seen that when the thickness of the insulation tile is 30mm or less, the required heater power is several percent lower than when there is no TaC coating layer (□), resulting in energy savings. This is due to the effect of the low emissivity (0.2) of the TaC coating layer.

[0078] It was found that as the thickness of the insulation tile increases, the required heater power gradually increases, and when the thickness of the insulation tile exceeds approximately 45 mm, it requires more power than when there is no TaC coating layer. In other words, when the thermal conductivity k of porous carbon is 1.1 W / (m·K), it was found that it is preferable to keep the thickness of the insulation tile within 45 mm. Put another way, it was found that keeping the thickness ratio of porous carbon (substrate A) (= t2 × 100 / t1) within 45% is preferable from an energy balance perspective.

[0079] Figure 5 shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the edge temperature of the molded insulation material when the heater surface temperature is 2400°C, in the multilayer insulation material of Example 2 (k=1.1W / (m·K), t1=100mm). From Figure 5, it can be seen that the surface temperature of the TaC coating layer is almost constant regardless of the thickness of the insulation tile, while the edge temperature of the molded insulation material decreases significantly as the thickness of the insulation tile increases. The carbon vapor pressure ratio was calculated using the edge temperature of the molded insulation material obtained in Figure 5.

[0080] Figure 6 shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the carbon vapor pressure ratio at the insulation tile / molded insulation interface when the heater surface temperature is 2400°C, for the multilayer insulation material of Example 2 (k=1.1W / (m·K), t1=100mm). From Figure 6, it can be seen that the carbon vapor pressure ratio is 0.6 or less when the thickness of the insulation tile is 4.0 mm or more. In other words, if the thickness of the insulation tile is 4.0 mm or more, the degradation rate of the molded insulation material will be 0.6 times or less, and the lifespan of the molded insulation material will be 1.67 times or more.

[0081] From the above results, it was found that, from the perspective of both the lifespan of the molded insulation material and the energy balance, when the thermal conductivity k of porous carbon is 1.1 W / (m·K), the thickness of the insulation tile (≒ thickness of base material A) is preferably between 4.0 mm and 45 mm. Furthermore, it was found that the thickness ratio of base material A is preferably between 4.0% and 45.0%.

[0082] [2.2. Example 3] Figure 7 shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the heater power required to reach a heater surface temperature of 2400°C in the multilayer insulation material of Example 3 (k=3.0W / (m·K), t1=100mm). From Figure 7, it can be seen that when the thickness of the insulation tile (≈thickness of base material A) is 20mm or less, the required heater power is several percent lower than when there is no TaC coating layer (□), resulting in energy savings. This is due to the effect of the low emissivity (0.2) of the TaC coating layer.

[0083] It was found that as the thickness of the insulation tile increases, the required heater power gradually increases, and when the thickness of the insulation tile exceeds approximately 30 mm, it requires more power than when there is no TaC coating layer. In other words, when the thermal conductivity k of porous carbon is 3.0 W / (m·K), it was found that it is preferable to keep the thickness of the insulation tile within 30 mm. Put another way, it was found that keeping the thickness ratio of porous carbon (= t2 × 100 / t1) within 30% is preferable from an energy balance perspective.

[0084] Figure 8 shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the edge temperature of the molded insulation material when the heater surface temperature is 2400°C, in the multilayer insulation material of Example 3 (k=3.0W / (m·K), t1=100mm). From Figure 8, it can be seen that the surface temperature of the TaC coating layer is almost constant regardless of the thickness of the insulation tile, while the edge temperature of the molded insulation material gradually decreases as the thickness of the insulation tile increases. The carbon vapor pressure ratio was calculated using the edge temperature of the molded insulation material obtained in Figure 8.

[0085] Figure 9 shows the relationship between the thickness of the multilayer insulation material (≈thickness of base material A) and the carbon vapor pressure ratio at the insulation tile / molded insulation material interface when the heater surface temperature is 2400°C, for the multilayer insulation material of Example 3 (k=3.0W / (m·K), t1=100m). From Figure 9, it can be seen that the carbon vapor pressure ratio is 0.6 or less when the thickness of the insulation tile is 10.0 mm or more. In other words, if the thickness of the insulation tile is 10.0 mm or more, it is estimated that the degradation rate of the molded insulation material will be 0.6 times or less, and the lifespan of the molded insulation material will be 1.67 times or more.

[0086] From the above results, it was found that, from the perspective of both the lifespan of the molded insulation material and the energy balance, when the thermal conductivity k of porous carbon is 3.0 W / (m·K), the thickness of the insulation tile (≒ thickness of base material A) is preferably between 10.0 mm and 30 mm. Furthermore, it was found that the thickness ratio of base material A is preferably between 10.0% and 30.0%.

[0087] [2.3. Example 4] Figure 10 shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the heater power required to reach a heater surface temperature of 2400°C in the multilayer insulation material of Example 4 (k=10.0W / (m·K), t1=100mm). From Figure 10, it can be seen that when the thickness of the insulation tile (≈thickness of base material A) is 20mm or less, the required heater power is several percent lower than when there is no TaC coating layer (□), resulting in energy savings. This is due to the effect of the low emissivity (0.2) of the TaC coating layer.

[0088] It was found that as the thickness of the insulation tile increases, the required heater power gradually increases, and when the thickness of the insulation tile exceeds approximately 30 mm, it requires more power than when there is no TaC coating layer. In other words, when the thermal conductivity k of porous carbon is 10.0 W / (m·K), it was found that it is preferable to keep the thickness of the insulation tile within 30 mm. In other words, it was found that keeping the thickness ratio of porous carbon (= t2 × 100 / t1) within 30% is preferable from an energy balance perspective.

[0089] Figure 11 shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the edge temperature of the molded insulation material when the heater surface temperature is 2400°C, in the multilayer insulation material of Example 4 (k=10.0W / (m·K), t1=100mm). From Figure 11, it can be seen that the surface temperature of the TaC coating layer is almost constant regardless of the thickness of the insulation tile, while the edge temperature of the molded insulation material gradually decreases as the thickness of the insulation tile increases. The carbon vapor pressure ratio was calculated using the edge temperature of the molded insulation material obtained in Figure 11.

[0090] Figure 12 shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the carbon vapor pressure ratio at the insulation tile / molded insulation interface when the heater surface temperature is 2400°C, for the multilayer insulation material of Example 4 (k=10.0W / (m·K), t1=100mm). From Figure 12, it can be seen that the carbon vapor pressure ratio is 0.6 or less when the thickness of the insulation tile is 25.0 mm or more. In other words, if the thickness of the insulation tile is 25.0 mm or more, it is estimated that the degradation rate of the molded insulation material will be 0.6 times or less, and the lifespan of the molded insulation material will be 1.67 times or more.

[0091] From the above results, it was found that, from the perspective of both the lifespan of the molded insulation material and the energy balance, when the thermal conductivity k of porous carbon is 10.0 W / (m·K), the thickness of the insulation tile (≒ thickness of base material A) is preferably 25.0 mm or more and 30 mm or less. Furthermore, it was found that the thickness ratio of base material A is preferably 25.0% or more and 30.0% or less.

[0092] [2.4. Comparative Example 1] Figure 13 shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the heater power required to reach a heater surface temperature of 2400°C in the multilayer insulation material of Comparative Example 1 (k=150.0W / (m·K), t1=100mm). From Figure 13, it can be seen that when the thickness of the insulation tile (≈thickness of base material A) is 20mm or less, the required heater power is several percent lower than when there is no TaC coating layer (□), resulting in energy savings. This is due to the effect of the low emissivity (0.2) of the TaC coating layer.

[0093] It was found that as the thickness of the insulation tile increases, the required heater power gradually increases, and when the thickness of the insulation tile exceeds approximately 28 mm, it requires more power than when there is no TaC coating layer. In other words, when the thermal conductivity k of the base material A is 150.0 W / (m·K), it was found that it is preferable to keep the thickness of the insulation tile within 28 mm. In other words, it was found that keeping the thickness ratio of the base material A (= t2 × 100 / t1) within 28% is preferable from an energy balance perspective.

[0094] Figure 14 shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the edge temperature of the molded insulation material when the heater surface temperature is 2400°C, for the multilayer insulation material of Comparative Example 1 (k=150.0W / (m·K), t1=100mm). From Figure 14, it can be seen that the surface temperature of the TaC coating layer is almost constant regardless of the thickness of the insulation tile, and the edge temperature of the molded insulation material is also almost constant regardless of the thickness of the insulation tile. The carbon vapor pressure ratio was calculated using the edge temperature of the molded insulation material obtained in Figure 14.

[0095] Figure 15 shows the relationship between the thickness of the insulation tile (≈thickness of base material A) and the carbon vapor pressure ratio at the insulation tile / molded insulation interface when the heater surface temperature is 2400°C, for the multilayer insulation material of Comparative Example 1 (k=150.0W / (m·K), t1=100mm). From Figure 15, it can be seen that the carbon vapor pressure ratio is 0.6 or less when the thickness of the insulation tile is 35.0 mm or more. In other words, if the thickness of the insulation tile is 35.0 mm or more, the degradation rate of the molded insulation material will be 0.6 times or less, and the lifespan of the molded insulation material will be estimated to be 1.67 times or more. However, it can be said that there is no suitable thickness range from the viewpoint of both the lifespan of the molded insulation material and the energy balance.

[0096] [2.5. Suitable range of thermal conductivity for base material A] Based on the computer simulation results of Examples 2-4 and Comparative Example 1, the suitable range of thermal conductivity for base material A was determined. Figure 16 shows the relationship between the thermal conductivity of base material A, the required thickness of base material A (the lower limit of the thickness of base material A at which the carbon vapor pressure ratio is 0.6 or less), and the required heater power ratio when the total thickness of the multilayer insulation material is 100 mm. The "required heater power ratio" refers to the value expressed by the following equation (4).

[0097] Required heater power ratio = PW × 100 / PW 0 ... (4) however, PW surrounds the graphite heater with multi-layer insulation, and the heater power required for the heater surface temperature to reach 2400°C PW0 is the heater power required for the heater surface temperature to reach 2400°C when the graphite heater is surrounded only by molded insulation.

[0098] Figure 16 shows that both the required thickness of base material A and the required heater power ratio decrease logarithmically as the thermal conductivity of base material A decreases. In particular, when the thermal conductivity of base material A falls below 10 W / (m·K) or below, or below 5.0 W / (m·K), the required thickness of base material A and the required heater power ratio decrease significantly. This result indicates that keeping the thermal conductivity of base material A below 10 W / (m·K) or below, or below 5.0 W / (m·K), is important for achieving both a long lifespan and energy savings for molded insulation materials.

[0099] [2.6. Suitable Thickness Range for Multilayer Insulation and Insulation Tiles] Figure 17 shows the relationship between the total thickness of the multilayer insulation material, the required thickness of base material A, and the maximum thickness of base material A, when the thermal conductivity of base material A is 1.1 W / (m·K). Figure 18 shows the relationship between the total thickness of the multilayer insulation material, the required thickness of base material A, and the maximum thickness of base material A, when the thermal conductivity of base material A is 3.0 W / (m·K). Figure 19 shows the relationship between the total thickness of the multilayer insulation material, the required thickness of base material A, and the maximum thickness of base material A, when the thermal conductivity of base material A is 10.0 W / (m·K).

[0100] "Required thickness of base material A" refers to the lower limit of the thickness of base material A required to reduce the carbon vapor pressure ratio to 0.6 or less. "Maximum thickness of base material A" refers to the upper limit of the thickness of base material A required to keep the required heater power ratio below 100%.

[0101] In Figures 17-18, the data at the position where the total thickness of the multilayer insulation material is 100 mm is the value obtained in Examples 2-4. The data at the positions of 50 mm and 250 mm are values ​​obtained by performing the same computer simulation as in Examples 2-4. In Figures 17-18, the region between the straight line representing the required thickness of base material A and the curve representing the maximum thickness of base material A represents the suitable range for the total thickness of the multilayer insulation material.

[0102] The total thickness of the multilayer insulation material is t1, and the required thickness of base material A is t2.min Therefore, from Figures 17 to 19, t1 and t2 min The relationship can be expressed as a linear equation like the following equation (5). t2 min = a1 × t1 + b1 ... (5) On the other hand, the maximum thickness of base material A is t2 max Therefore, t1 and t2 max The relationship can be expressed as a quadratic equation like the following equation (6). t2 max = a² × t¹ 2 +b² × t¹…(6)

[0103] Figure 20 shows the dependence of the slope a1 and y-intercept b1 of the linear regression equation representing the required thickness of substrate A on the thermal conductivity of substrate A. Figure 21 shows the dependence of the coefficients a2 and b2 of the quadratic regression equation representing the maximum thickness of substrate A on the thermal conductivity of substrate A. From Figures 20 and 21, it was found that the coefficients a1, b1, a2, and b2 can be more accurately fitted to the thermal conductivity k of substrate A by either an exponential decay or exponential rise function. The regression equations are shown below.

[0104] a1=-0.0014907+0.41177×[1-exp(-0.1037k)] b1=-2.6021+3.055×exp(-0.33985k) a2=0.0013938+0.0089152×exp(-0.72719k) b2=-0.25756+0.39576×[1-exp(-0.55089k)]

[0105] From these regression equations, as well as equations (5) and (6), it is possible to determine the range of thickness t2 of the base material A that can achieve both thermal insulation and durability, regardless of the thermal conductivity k of the base material A and the total thickness t1 of the multilayer insulation material.

[0106] [2.7. Application Examples] Figure 22 shows an example structure in which the thermal insulation tile and multilayer thermal insulation material according to the present invention are applied to SiC crystal growth. Direct heating of a graphite crucible by high-frequency heating is used for SiC crystal growth. In addition to heating the graphite crucible to a high temperature of 2000°C to 2400°C, the gas sublimated from the SiC raw material powder is highly corrosive, so the molded thermal insulation material deteriorates quickly. By placing the thermal insulation tile on the high-temperature side of the molded thermal insulation material, the lifespan of the molded thermal insulation material can be improved and cost reduction can be expected. Furthermore, by placing insulating tiles inside the crucible and using them as a heat shield to block the heat radiated from the SiC raw material powder, it is expected that temperature gradient control will become easier.

[0107] Although embodiments of the present invention have been described in detail above, the present invention is not limited in any way to the above embodiments, and various modifications are possible without departing from the spirit of the present invention. [Industrial applicability]

[0108] The heat-insulating tile according to the present invention can be used as a protective material for the high-temperature side surface of molded heat-insulating material, a heat shielding plate for blocking radiant heat, and the like. The multilayer insulation material according to the present invention can be used as an insulation material placed around a graphite heater.

Claims

1. A substrate A made of porous carbon, A coating layer containing a high melting point metal carbide is formed on at least one surface of the substrate A. Equipped with, The coating layer has a relative density of 95% or more. Insulating tiles. however, The aforementioned "porous carbon" refers to a material with a bulk density of 1.1 g / cm³. 3 1.6g / cm or more 3 The following refers to a sintered carbon body: The aforementioned "high melting point metal carbide" refers to a carbide containing at least one metal having a melting point of 2000°C or higher.

2. The heat insulating tile according to claim 1, wherein the thickness of the coating layer is 20 μm or more and 200 μm or less.

3. The heat insulating tile according to claim 1, wherein the thickness of the base material A is 4.0 mm or more and 45.0 mm or less.

4. The thermal insulation tile according to claim 1, comprising the aforementioned high-melting-point metal carbide, TaC.

5. (a) A protective material for protecting the surface of a base material B made of a molded insulating material containing carbon fibers, (b) A heat shield plate placed between the crucible filled with sublimation material and the base for holding the seed crystal, to prevent radiant heat from the crucible, which is heated to a high temperature, from directly reaching the seed crystal. An insulating tile according to any one of claims 1 to 4, used as such.

6. A base material B consisting of a molded insulation material containing carbon fibers, The heat insulating tile according to claim 1, which is arranged on the surface of the substrate B Equipped with The insulating tile is positioned on the surface of the substrate B such that the coating layer faces the external atmosphere. Multilayer insulation material.

7. The multilayer thermal insulation material according to claim 6, wherein at least one of the thermal insulation tiles is arranged on the high-temperature side surface of the substrate B such that the coating layer is on the high-temperature side.

8. The multilayer insulation material according to claim 6, wherein the following relationship (1) holds true. a 1 ×t 1 +b 1 ≦t 2 ≦a 2 ×t 1 2 +b 2 ×t 1 …(1) however, t 1 The total thickness (mm) of the multilayer insulation material is t 2 The thickness (mm) of the base material A included in the heat insulating tile, a 1 =-0.0014907+0.41177×[1-exp(-0.1037k)]、 b 1 =-2.6021+3.055×exp(-0.33985k)、 a 2 =0.0013938+0.0089152exp(-0.72719k)、 b 2 =-0.25756+0.39576×[1-exp(-0.55089k)]、 k is the thermal conductivity of the substrate A at room temperature (W / (m·K)).

9. The substrate A has a thermal conductivity of 1.1 ± 0.9 W / (m·K) at room temperature. The thickness ratio of the base material A is 4.0% or more and 45.0% or less. The multilayer insulation material according to claim 6. However, the "thickness ratio of base material A" refers to the total thickness t of the multilayer insulation material. 1 The thickness t of the base material A 2 The proportion (= t 2 ×100 / t 1 ) refers to.

10. The aforementioned substrate A has a thermal conductivity of 3.0 ± 1.0 W / (m·K) at room temperature. The thickness ratio of the base material A is 10.0% or more and 30.0% or less. The multilayer insulation material according to claim 6. However, the "thickness ratio of base material A" refers to the total thickness t of the multilayer insulation material. 1 The thickness t of the base material A 2 The proportion (= t 2 ×100 / t 1 ) refers to.

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