Fireproof composite material

Abstract

A refractory composite material comprising a Si-SiC sintered body having a framework with a three-dimensional structure, wherein the porosity of the Si-SiC sintered body is 50 to 98%, the SiC content of the framework is 35 to 70 wt.% and the metal Si content of the framework is 25 to 60 wt.%, characterized in that the three-dimensional structure is mesh-shaped and the scaffold has a porosity of 1% or less.

Description

Technical area

[0001] The present invention relates to a refractory composite material that can be used for a cassette suitable for use in the degreasing process or the firing process of electronic ceramic components. General state of the art

[0002] For several years, there has been a need for a cassette that can be used for both the degreasing and firing processes, with the aim of increasing the firing efficiency of small electronic components. A cassette for the degreasing process requires air permeability to ensure rapid release of binder, while a cassette for the firing process requires properties that prevent reaction with the fired electronic ceramic component, in addition to heat resistance and mechanical strength.

[0003] As a cassette that meets the requirements for the firing process, a cassette in which an intermediate layer and a reaction-resistant coating are formed on an alumina-mullite base material surface is known. JP 2012-56831 A discloses a technique in which the cassette is made thinner and higher kiln efficiency and energy efficiency are achieved by using a Si-SiC sintered body as the base material instead of the alumina-mullite base material. Compared to an alumina-silica sintered body, the Si-SiC sintered body exhibits excellent high-temperature strength and corrosion resistance, as well as high strength and high thermal conductivity.

[0004] However, the cassette in JP 2012 - 56 831 A is not suitable for simultaneous use in the degreasing process because it lacks air permeability. As a cassette with air permeability, JP 2011 - 117 669 A discloses a technology that uses a metal mesh instead of the usual ceramic plate material.

[0005] However, the metal mesh tends to bend slightly during the firing process due to its high temperature. Furthermore, since it has poorer thermal conductivity compared to a Si-SiC sintered body, the temperature is distributed unevenly between the products arranged on the metal mesh, resulting in the problem of inconsistent product quality.

[0006] Regarding ceramic structural bodies with air permeability, a technique is also known in which an open-pore foam ceramic is produced according to the so-called Schwarzwalder process. Since conventional open-pore foam ceramics had the problem that cracks could easily develop in the porous parts of the framework, thereby reducing their mechanical strength, US Pat. No. 6,635,339 B1 discloses a technique for increasing strength by adding Si to the porous parts of the SiC foam ceramic framework.

[0007] However, with the increased strength of the ceramic of US 6 635 339 B1, the elastic modulus also increases, and since an increase in the elastic modulus is associated with a reduction in the thermal shock resistance (thermal shock fracture resistance coefficient R' = σ(1-v)λ / (αE), where σ: strength, E: elastic modulus), the problem arises that an application for purposes where thermal shock resistance and high strength are required at the same time is not possible.

[0008] DE 10 2007 000 840 A1 describes a Si-SiC sintered body which is dense with a porosity of 0 to 5% and is a refractory material with excellent strength used for the inner surface of a rotary kiln.

[0009] EP 1 277 714 B1 describes a honeycomb structure made of SiC for an exhaust gas purification filter, which has the features of the preamble of patent claim 1.

[0010] DE 196 21 638 C2, DE 196 12 985 A1 and DE 38 12 156 A1 describe processes for producing ceramics with open cells, which can be used, for example, as filters. Brief description of the inventionTask of the invention

[0011] The object of the present invention is to solve the above-mentioned problems and to provide a fire-resistant composite material having high strength and high thermal conductivity, excellent thermal shock resistance and air permeability, and which does not cause breakage and deformation such as buckling when used under high temperature conditions. Means of solving the task

[0012] The refractory composite material of the present invention, which was made to solve the above-mentioned problems, is a refractory composite material having the features of claim 1.

[0013] The subclaims deal with advantageous developments of the invention. Effect of the invention

[0014] It is possible to obtain a refractory composite material having high strength and high thermal conductivity, excellent thermal shock resistance and air permeability, and free from breakage and deformation such as buckling when used under high temperature conditions by using Si-SiC having high strength and high thermal conductivity, and the skeleton whose porosity is 1% or less is a three-dimensional mesh structure, wherein its SiC content is 35 to 70 wt% and its Si content is 25 to 60 wt%, and more preferably its SiC content is 40 to 65 wt% and its Si content is 30 to 55 wt%. Short description of the characters Fig. 1 (a) shows an overall perspective view of a cassette according to a first embodiment, and Fig. 1 (b) shows an enlarged view of the framework of the cassette of the first embodiment. Fig.Figure 2 shows horizontal cross-sectional and vertical cross-sectional images of the composition of the Si-SiC framework of the cassette of the embodiment (image taken with a JEOL JSM-5600 scanning electron microscope). Fig. 3 shows a flowchart explaining the manufacturing steps of the first embodiment. Fig. Fig. 4 is a diagram explaining the manufacturing steps of the first embodiment. Fig. Figure 5 shows metal Si deposited on the surface of a urethane foam that has undergone a urethane molding firing step. Fig. 6 shows a flowchart explaining the manufacturing steps of the first embodiment. Fig. Fig. 7 (a) shows an overall perspective view of a cassette according to a second embodiment, and Fig. 7 (b) shows an enlarged view of the framework of the first embodiment. Fig.8 shows enlarged images of the second embodiment in vertical cross section and horizontal cross section (photographed with a JEOL JSM-5600 scanning electron microscope). Fig. 9 shows a flowchart explaining the manufacturing steps of the first embodiment. Fig. Fig. 10(a) shows an overall perspective view of a cassette according to the third embodiment, and Fig. 10(b) shows an enlarged view of the framework of the first embodiment. Embodiments of the invention

[0015] Preferred embodiments of the present invention will be described below. First embodiment: single layer, without compaction

[0016] The refractory composite material of the present embodiment is a cassette having a single-layer structure whose base material is a Si-SiC sintered body as shown in Fig.1(a). The cassette comprises a framework with a three-dimensional mesh-like structure, as shown in Fig. 1 (b). The porosity of the scaffold is 1% or less.

[0017] In the firing step for electronic components, etc., the cassette is used at a high temperature (around 1300°C) near the melting point of Si (around 1400°C). If the framework is formed entirely of Si, problems arise, such as creep deformation during the high-temperature firing step, the easy formation of SiO2 due to oxidation on the surface layer, and high oxygen ingress into the firing furnace. In contrast, these problems are avoided in the present invention by using a Si-SiC composite because SiC is highly resistant to oxidation and heat resistance, as well as having high strength.

[0018] In an air-permeable cassette, the porous portion formed for air permeability often functions as a heat-insulating layer. When a metal mesh made of stainless steel or Ni, etc., which has low thermal conductivity, is used as the air-permeable cassette, temperature distribution is likely to occur on the cassette during heating and cooling, resulting in temperature unevenness among the products placed on the cassette, resulting in uneven product quality. Meanwhile, in the firing step, with its high temperature, the temperature distribution, i.e., a difference in thermal expansion, easily causes the cassette to deform due to bending. In contrast, in the present invention, an air-permeable cassette is formed by using a Si-SiC sintered body, which has a higher thermal conductivity than a metal mesh made of stainless steel, Ni, etc.has excellent thermal conductivity, as a three-dimensional mesh-like structure is formed, so that these problems can be avoided.

[0019] In the present invention, the amount of each component is determined such that the SiC content of the skeleton is 35 to 70 wt% and the Si content is 25 to 60 wt%. The chemical components are measured according to JIS R 2011 (Chemical Analysis Method for Carbon and Silicon Carbide Refractories). If the SiC content of the skeleton is higher than 70 wt%, pores may remain between the SiC particles, resulting in a problem of reduced strength, and if it is below 35 wt%, the hot strength decreases, resulting in a problem of easier creep deformation in the firing step with its high temperature. If the Si content of the skeleton is higher than 60 wt%, the hot strength decreases, resulting in a problem of easier creep deformation in the firing step with its high temperature, and if it is below 25 wt%, the hot strength decreases, resulting in a problem of easier creep deformation in the firing step with its high temperature.-%, pores may remain between the SiC particles, resulting in the problem of reduced strength.

[0020] When the Si content of the framework is higher than 55 wt%, Si oxidizes and SiO2 is more likely to form on the surface layer, and when it is below 30 wt%, pores may remain between the SiC particles, and SiC may oxidize and SiO2 is more likely to form on the surface layer. In either case, due to SiO2 forming on the surface layer, thermal shock resistance and high-temperature strength decrease, which makes it easier to cause problems such as cracks and flexural deformation, increased oxygen input into the kiln, and reaction with the processed workpiece. Therefore, from the perspective of prolonging the service life of the product, it is preferable to set the amount of each component so that the SiC content is between 40 and 65 wt% and the Si content is between 30 and 55 wt%.

[0021] In the present invention, by setting the SiC content to 35 to 70 wt% and the Si content to 25 to 60 wt% for SiC, which has a high elastic modulus (elastic modulus: about 400 GPa), and for Si, which has a low elastic modulus (elastic modulus: about 100 GPa), and more preferably the SiC content to 40 to 65 wt% and the Si content to 30 to 55 wt%, a Si-SiC sintered body with a reduced elastic modulus is obtained by forming the framework. A reduction in the elastic modulus is accompanied by an increase in thermal shock resistance. (Thermal shock fracture resistance coefficient R' = σ(1-v)λ / (αE), where σ: strength, E: elastic modulus), therefore, according to this configuration, a refractory composite material can be obtained which, in addition to the properties of high strength and high thermal conductivity, also has the property of excellent thermal shock resistance.

[0022] In the present embodiment, as another configuration for reducing the elastic modulus of the Si-SiC sintered body, a configuration can be adopted in which the shape of the pores and the framework constituting the three-dimensional mesh structure satisfies a mean value of [pore diameter / framework diameter] of ≥ 3. By satisfying a mean value of [pore diameter / framework diameter] of ≥ 3, it is possible to maintain the strength of the product and achieve a reduction in the elastic modulus. The porosity of the cassette is preferably 50 to 98%. If the porosity is 49% or less, sufficient air permeability is not achieved, and if it is 99% or more, breakage is likely to occur due to a significant reduction in strength, and therefore both are undesirable.

[0023] As in Fig. 1(b) and Fig.As shown in Figure 2, the framework is constructed from a core section 1 and a surface layer section 3, which is adjacent to a pore section 2. [Table 1] (wt.%) Sample (1) Sample (2) Sample (3) Core section Surface layer section Core section Surface layer section Core section Surface layer section Element unit Si 80,22 53,19 88,93 66,44 93,99 83,98 C 19,78 46,81 11,07 33,56 6,01 16,02 *According to quantitative EDS analysis

[0024] Table 1 shows the result of an EDS analysis at any two locations of the composition images from Fig.2. As shown in Table 1, each section (core section 1 and surface layer section 3) has different constituent element contents. In core section 1, the C element content is 5 to 20 wt% and the Si element content is 80 to 95 wt%, while in surface layer section 3, the C element content is 15 to 50 wt% and the Si element content is 50 to 85 wt%. The free carbon (FC) content in the framework is 0.1% or less, and the C element exists mainly as SiC in the framework. Therefore, in core section 1 with the above-mentioned element content, metal Si is the main component and contains a small amount of SiC. In surface layer section 3, SiC is the main component, just like a conventional Si-SiC sintered body, and it has a structure in which the pores are filled with Si.

[0025] If the element C content of the core portion 1 is higher than 20 wt%, pores may remain in the core portion 1, thus reducing the strength. Conversely, if the content is below 5 wt%, the high-temperature strength decreases, making creep deformation more likely to occur during the high-temperature firing step. Therefore, the element C content of the core portion 1 is preferably within the above-mentioned range.

[0026] If the C element content of the surface layer portion 3 is higher than 50 wt%, pores may remain between the SiC particles, thus reducing the strength. Conversely, if the content is below 15 wt%, the high-temperature strength decreases, making creep deformation more likely to occur during the high-temperature firing step. Therefore, the C element content of the surface layer portion 3 is preferably within the above-mentioned range.

[0027] The method for manufacturing the cassette of the present embodiment will be described in detail below. The cassette of the present embodiment is manufactured in a gel casting process by steps ST1 to ST8 of Fig. 3. The gel casting method is a powder molding method for obtaining a molded article of a desired shape, wherein a slurry prepared by dispersing a powder selected from one or more of a group consisting of ceramic, glass, and metal onto a dispersion medium using a dispersant and hardening it by adding a material (gelling agent) having gelling ability to the slurry. ST1:

[0028] Since the cartridge of the present embodiment is molded by the gel casting method, the molding slurry is first prepared. The molding slurry of the present embodiment can be prepared by dispersing SiC powder in an organic solvent and then adding a gelling agent to the slurry, or by simultaneously adding SiC powder and gelling agent to the organic solvent and dispersing them.

[0029] In addition to SiC powder, powders of carbon, boron carbide, etc. can be used as needed. There is no particular restriction on the particle size of the ceramic powder as long as the slurry can be produced, and it can be determined as needed depending on the molded article selected as the production target.

[0030] As the organic solvent serving as a dispersion medium, there can be mentioned polyhydric alcohols, e.g. diols such as ethylene glycol, etc. or triols such as glycerol, etc., polybasic acids such as dicarboxylic acid, etc., polybasic acid esters such as dimethyl glutaric acid, dimethyl malonic acid, etc. or esters of polyhydric alcohols, etc.

[0031] The gelling agent should be an organic compound having a reactive functional group that cures the ceramic slurry. Examples of such organic compounds include prepolymers that achieve three-dimensional crosslinking through the mediation of a crosslinking agent, such as urethane resin, acrylic resin, epoxy resin, phenolic resin, etc. Considering the reactivity with the organic compound in the dispersion medium, the gelling agent preferably selected is one having a favorable reactive functional group. When an ester, which is relatively inert, is used as the organic solvent, the organic compound having the reactive functional group constituting the gelling agent is preferably selected as an organic compound having a reactive isocyanate group (-N=C=O) and / or isothiocyanate group (-N=C=S).Since in the present embodiment, as described below for ST2, the molding slurry is molded by impregnating a urethane foam, a urethane resin having high rubber elasticity is preferably used to prevent damage to the SiC slurry molded body associated with elastic deformation (bending, etc.) of the urethane foam.

[0032] Preferably, the molding slurry does not harden during the impregnation of the urethane foam, but hardens rapidly after molding. Therefore, when preparing the ceramic slurry, it is preferable to consider the temperature of the slurry, the type and content of the dispersion medium, the type and content of the gelling agent, the presence of a catalyst that accelerates the gelling reaction, the type and content of such a catalyst, etc. In terms of processability, the slurry viscosity is preferably 50 dPa s or less at 20°C, and more preferably 20 dPa s or less at 20°C.

[0033] In the molding slurry preparation step, the ceramic powder, dispersion medium, and dispersant are prepared and mixed. The final preparation is then carried out by adding the gelling agent and catalyst, etc., to the slurry, which is then defoamed in preparation for impregnating the urethane foam.

[0034] The molding slurry is mixed in a pot mill or ball mill, etc., using nylon balls, and the mixing is carried out at 15°C to 35°C for 12 hours or more, preferably 72 hours or more. The slurry is defoamed by stirring the slurry in a vacuum atmosphere, where the vacuum degree is -0.090 MPa or less, preferably -0.095 MPa or less, the stirring speed is preferably 100 rpm to 500 rpm, and the stirring time is preferably 5 minutes to 30 minutes. ST2 to ST4:

[0035] After the urethane foam is impregnated with the molding slurry prepared in ST1, excess slurry is squeezed out to ensure that no slurry closes the pores of the urethane foam. The urethane foam is placed on a fixation tool and allowed to rest for several to several dozen hours at normal temperature up to 40°C. In this way, the molding slurry gels and hardens, forming the molded body.

[0036] As in Fig. 4 (A), the urethane foam is formed of a skeleton portion 4 and a cavity portion 5, wherein in ST2, as shown in Fig. 4(B), the SiC slurry molded body 10 is formed adjacent to the cavity portion 5. ST5 to ST6:

[0037] Then, drying is carried out at 40°C to 100°C for 3 to 12 hours; then, heating is carried out at 100°C to 200°C for 3 to 12 hours to fire the urethane mold, which is a processing to eliminate the elasticity of the urethane foam.

[0038] During drying, the SiC slurry molded body 10 shrinks. When an aqueous slurry containing water is used as the dispersion medium, it is not possible to ensure the shrinkage amount of the SiC slurry molded body 10 during drying because the urethane foam does not swell upon impregnation with the molding slurry, resulting in the problem that cracks are likely to form in the SiC slurry molded body 10. In contrast, in the present embodiment, an organic solvent is used as the dispersion medium, so that the urethane foam can swell upon impregnation with the molding slurry, thereby ensuring the shrinkage amount of the SiC slurry molded body 10 during drying and preventing cracks from forming in the SiC slurry molded body 10 during drying. ST7 to ST8:

[0039] As in Fig. 4 (C) and Fig.As shown in Figure 5, metal Si 7 is applied to the surface of the urethane foam, which has been rendered inelastic, and heating is carried out at 1400°C to 1500°C for 1 to 3 hours under an inert gas atmosphere. The framework section 4 of the urethane foam burns off at about 500°C, and by, as shown in Fig. As shown in Figure 4 (D), by impregnating the cavities formed by burning the framework section 4 with metal Si7, a novel refractory composite material (porosity 50 to 98%) is obtained, which has a compact SiC-Si framework with a three-dimensional mesh structure. According to this method, impregnation with metal Si7 can be achieved through the framework formed by the SiC slurry molded body 10, thus enabling uniform impregnation without metal Si7 clogging the cavity section 5.

[0040] If required, as in Fig.As shown in Figure 6, after step ST8, a step ST9 for firing a coating with reaction resistance may also be provided, and on the side of the upper layer of the base material, which forms the contact surface with the workpiece, a surface coating with reaction resistance with respect to the workpiece may be formed. The surface coating is formed from a material with low reactivity with respect to the workpiece, and the material varies depending on the type of workpiece. For example, in the case of a ceramic capacitor formed from barium titanate, a zirconium dioxide compound with low reactivity with respect to the workpiece is preferably selected.As the zirconia compound, a zirconia compound comprising at least one of stabilized zirconia stabilized with calcium oxide (CaO) or yttrium oxide (Y2O3), BaZrO3, and CaZrO3 can be appropriately selected as the most suitable zirconia considering reactivity. Depending on the type of electronic component, a sprayed film containing a eutectic with alumina and zirconia can also be used as the surface coating. There is no particular limitation on the method for forming the surface coating, and the most suitable method can be used, such as sputtering, spray coating, etc.

[0041] Depending on the need, it is possible to form a frame portion comprising a compact Si-SiC layer having a porosity of 0.1 to 2% at the edge portion of the base material after closing the pores by impregnating the edge portion of the base material with the molding slurry prepared in ST1 by curing, drying, and Si impregnation as described in ST5 to ST8 above.

[0042] Depending on the requirements, it is also possible to use a frame member that supports the base material. Preferably, the frame member is made of a nickel alloy, etc. In order to absorb the thermal expansion difference between the base material comprising the Si-SiC sintered body and the nickel alloy, it is preferable in this case not to fix the base material and the frame member, but to maintain a certain distance between the frame member and the base material. Second embodiment: single layer, with compaction of the urethane foam

[0043] In step ST3 “Fix to a desired thickness / shape” from Fig. 3 and Fig. 6 the urethane foam can be fixed by compaction.

[0044] By compacting the urethane foam in this way before the curing of the molding slurry (ST4), the structural density of the new refractory composite material with a three-dimensional mesh structure can be increased, thereby achieving increased strength. As shown in Fig. As shown in Figure 7(a), this also allows the cassette to be made thinner.

[0045] The fire-resistant composite material of the present embodiment obtained by compressing the urethane foam has, as shown in Fig. 7 (b) shows a flat framework structure and, as in Fig.As shown in Figure 8, the scaffold density differs between the vertical cross section and the horizontal cross section. If the scaffold density ratio between the vertical cross section and the horizontal cross section is greater than 40 times, sufficient air permeability cannot be achieved on the side surface (at the vertical cross section). In addition, the effective surface (horizontal cross section) will be clogged by sludge, so sufficient air permeability cannot be achieved, so the ratio is preferably 40 times or less. If the scaffold density ratio between the vertical cross section and the horizontal cross section is less than 1.1 times, sufficient effect cannot be achieved in terms of strengthening the cassette, so the ratio is preferably 1.1 times or higher.

[0046] The framework density can be measured using the following procedure. First, the refractory composite material is embedded in a phenolic resin, etc., after which the refractory composite material is cut and ground in the vertical and horizontal directions to produce test specimens. Next, the specimens are examined using a JEOL JSM-5600 scanning electron microscope with a field of view of 0.1 cm. 2Composition images of the vertical cross-section and horizontal cross-section of the test samples were created. The composition images utilize the brightness difference between the elements, allowing the Si-SiC framework section and the cavity section to be clearly seen. Next, the obtained composition images are converted into a bivalent black-and-white image using image processing software under constant brightness conditions, and the total number of pixels of the framework section and the cavity section is measured. The freeware ImageNos (Ver. 1.04), for example, can be used as image processing software. In this way, the framework density can be determined based on the total number of pixels of the framework section relative to the total number of pixels in the field of view (framework density = total number of pixels of the framework section / total number of pixels of the framework section and the cavity section).This allows the scaffold density ratio between the vertical cross-section and the horizontal cross-section to be calculated (scaffold density ratio = scaffold density at the vertical cross-section / scaffold density at the horizontal cross-section). However, since the scaffolds are randomly arranged in a three-dimensional mesh structure, the scaffold density cannot be determined from cross-sectional composite images of a single field of view. To calculate the scaffold density, cross-sectional composite images of at least five fields of view, and more preferably 10 or more fields of view, must be used for the vertical cross-section and the horizontal cross-section.

[0047] In step ST3 “Fix to a desired thickness / shape” from Fig. 3 and Fig.6, the urethane foam can be fixed by compression using a mold of a specific shape. By fixing the urethane foam in this way in a specific shape before the curing of the molding slurry (ST4), the shape freedom of the new refractory composite material with a three-dimensional mesh structure can be increased, allowing the production of cassettes with complex shapes. Examples of cassettes with complex shapes that can be produced include scorching capsules or cassettes with feet for stacking. Third embodiment: multiple layers

[0048] As in Fig. As shown in Figure 9, before the curing of the molding slurry (ST4), a step ST10 for applying and integrally forming a urethane foam layer with a different compaction rate may be provided.

[0049] The fire-resistant composite material of the present embodiment has, as shown in Fig.10, a laminated structure in which layers with different framework densities are laminated to one another. For example, consider roller conveyance in a roller hearth furnace. Depending on the type of use, the most suitable lamination structure can be formed by, for example, a first layer 8 being a compact layer with high strength and a second layer 9 being a layer with high air permeability. In this case, the first layer 8 is the compact layer, while the second layer 9 has the three-dimensional mesh structure, which is why high air permeability can be achieved on the surface and side surfaces of the second layer 9. The top layer can also be formed as a compact layer with a porosity of 0.1 to 2%. Examples of implementation A

[0050] Using cassettes of the following working examples 1 to 6 and Comparative Examples 1 to 2, the occurrence of cracks and deformations due to bending was tested; for Working Examples 1 to 6, no cracks and deformations due to bending were observed, whereas for Comparative Examples 1 to 2, cracks and / or deformations due to bending were observed. Example 1

[0051] SiC (-C, -B4C) was dispersed in an organic solvent. A 150 × 150 × 5 mm urethane foam was immersed in the SiC slurry to which urethane resin (isocyanate and catalyst) was added. Excess slurry was removed and cured. The molded body, in which a SiC (-C, -B4C) layer was formed on the skeleton surface of the urethane foam, was dried at 120°C to prepare a SiC molded body. Next, metal Si was coated on the SiC molded body at a weight ratio of 90%, and fired at 1500°C under reduced pressure and in a reducing atmosphere, thereby producing a 5 mm thick Si-SiC cassette with a three-dimensional mesh structure and air permeability. The porosity of the manufactured cassette with air permeability was 95%. Example 2

[0052] SiC (-C, -B4C) was dispersed in an organic solvent. A 150 × 150 × 5 mm urethane foam was immersed in the SiC slurry to which urethane resin (isocyanate and catalyst) was added. Excess slurry was removed. Using a clamping tool, the urethane foam was pressed and compacted to a thickness of 1 mm. The slurry was then cured, producing a 1 mm thick SiC molded body. Firing was then carried out in the same manner as in Example 1, thereby producing a 1 mm thick air-permeable cassette. The porosity of the fabricated air-permeable cassette was 60%. The framework density ratio, calculated as described in

[0055] , was 1.4 times. Example 3

[0053] SiC (-C, -B4C) was dispersed in an organic solvent. A 180 × 180 × 5 mm urethane foam was immersed in the SiC slurry mixed with urethane resin (isocyanate and catalyst). Excess slurry was removed. The urethane foam was fixed into the shape of a sprue using a box-shaped fixing tool. The slurry was then cured, producing a 5 mm thick box-shaped SiC molded body. Firing was then carried out in the same manner as in Example 1, producing a 5 mm thick air-permeable sprue. The porosity of the resulting air-permeable sprue was 95%. Example 4

[0054] On one surface or both surfaces of the SiC molded body obtained in Embodiment 1, the SiC molded body obtained in Embodiment 2 was bonded, and the thus integrally formed SiC molded body was fired in the same way as in Embodiment 1, thereby obtaining a 6 to 7 mm thick air permeable cassette having a multilayer structure. Example 5

[0055] On one surface of the SiC molded body obtained in Example 2, a SiC molded body having a thickness of 1 mm, which was formed by curing the SiC slurry without using urethane foam, was bonded, and the thus integrally formed SiC molded body was fired in the same way as in Example 1, thereby producing a 2 mm thick air permeable cassette having a multi-layer structure including a compact layer with high strength. Example 6

[0056] The edge portion of the SiC formed body obtained in Embodiment 2 was impregnated with SiC slurry in a width of 5 mm to close its pores and cured, and the thus integrally formed SiC formed body was fired in the same manner as in Embodiment 1, thereby producing a 1 mm thick air permeable cassette having a 5 mm wide edge portion with a high strength compact layer. Example 7

[0057] On one surface or both surfaces of the Si-SiC sintered body obtained in Embodiment 2, slurry comprising ZrO2 and / or Al2O3-SiO2 was applied by spraying, followed by firing at 1350°C, thereby forming a layer of ZrO2 and / or Al2O3-SiO2. Comparison example 1

[0058] A cassette was made from a Ni-metal mesh. Comparison example 2

[0059] A 1 mm thick cassette was manufactured according to the method described in JP 2012 - 56 831 A. Design examples Design example 8

[0060] SiC (-C, -B4C) was dispersed in an organic solvent. A 150 × 150 × 5 mm urethane foam was immersed in the SiC slurry mixed with urethane resin (isocyanate and catalyst). Excess slurry was removed. Using a clamping tool, the urethane foam was pressed to a thickness of 1 mm. The slurry was then cured, producing a 1 mm thick SiC molded body. Following firing, the molded body was prepared in the same manner as in Example 1, producing a 1 mm thick air-permeable cassette. The porosity of the resulting air-permeable cassette was 60%. The total SiC content in the framework was 46.5 wt%, the Si content was 48.4 wt%, the C content in the core portion of the framework was 19.8 wt%, and the C content in the surface layer portion was 46.8 wt%. The ratio [pore diameter / framework diameter] was 4.9. Example 9

[0061] A 1 mm thick air-permeable cassette was fabricated using a 150 × 150 × 3 mm urethane foam using the same method as in Example 8. The porosity of the fabricated air-permeable cassette was 70%. The SiC content in the entire framework was 54.1 wt%, the Si content was 40.0 wt%, the C content in the core portion of the framework was 11.1 wt%, and the C content in the surface layer portion was 33.6 wt%. The ratio [pore diameter / framework diameter] was 4.6. Example 10

[0062] A 1 mm thick air-permeable cassette was fabricated using a 150 × 150 × 2 mm urethane foam using the same method as in Example 8. The porosity of the fabricated air-permeable cassette was 80%. The SiC content in the entire framework was 58.8 wt%, the Si content was 35.8 wt%, the C content in the core portion of the framework was 6.0 wt%, and the C content in the surface layer portion was 16.0 wt%. The ratio [pore diameter / framework diameter] was 3.9. Comparison example 3

[0063] SiC (-C, -B4C) was dispersed in an organic solvent. A 150 × 150 × 5 mm urethane foam was immersed in the SiC slurry mixed with urethane resin (isocyanate and catalyst). Excess slurry was removed. Using a clamping tool, the urethane foam was pressed to a thickness of 1 mm. The slurry was then cured, producing a 1 mm thick SiC molded body. Next, metal Si was coated onto the SiC molded body at a weight ratio of 60%, and fired at 1500°C under reduced pressure and in a reducing atmosphere, producing a 1 mm thick air-permeable cassette. The porosity of the fabricated air-permeable cassette was 60%. The total SiC content in the framework was 73.3 wt%, the Si content was 21.6 wt%, the C content in the core portion of the framework was 10.1 wt%, and the C content in the surface layer portion was 55.7 wt%.-%. The ratio [pore diameter / scaffold diameter] was 3.6. Comparison example 4

[0064] Following the same procedure as in Comparative Example 3, a 1 mm thick SiC preform was prepared. Next, metal Si was coated onto the SiC preform at a weight ratio of 120%, and fired at 1500°C under reduced pressure and a reducing atmosphere, thereby producing a 1 mm thick air-permeable cassette. The porosity of the produced air-permeable cassette was 60%. The SiC content in the entire framework was 28.4 wt%, the Si content was 66.2 wt%, the C content in the core portion of the framework was 11.4 wt%, and the C content in the surface layer portion was 13.6 wt%. The ratio [pore diameter / framework diameter] was 4.2. Comparison example 5

[0065] SiC (-C, -B4C) was dispersed in an organic solvent. A 150 × 150 × 5 mm urethane foam was immersed in the SiC slurry mixed with urethane resin (isocyanate and catalyst). Excess slurry was removed insufficiently. Using a clamping tool, the urethane foam was pressed to a thickness of 1 mm. The slurry was then cured, producing a 1 mm thick SiC molded body. Next, metal Si was coated onto the SiC molded body at a weight ratio of 60%, and fired at 1500°C under reduced pressure and in a reducing atmosphere, producing a 1 mm thick air-permeable cassette. The porosity of the fabricated air-permeable cassette was 40%. The total SiC content in the framework was 68.8 wt%, the Si content was 23.8 wt% and the C content in the core section of the framework was 11.1 wt%.-% and the C content in the surface layer section was 55.4 wt.%. The ratio [pore diameter / framework diameter] was 1.3. Examples B [Table 2] Example 8 Example 9 Example 10 Comparison example 3 Comparison example4 Comparison example5 Chemical components (wt%) Entire scaffolding SiC 46,5 54,1 58,8 73,3 28,4 68,8 Metal-Si 48,4 40,0 35,8 21,6 66,2 23,8 Element content (wt%) Core section C 19,8 11,1 6,0 10,1 11,4 11,1 Si 80,2 88,9 94,0 89,9 88,6 88,9 Surface layer section C 46,8 33,6 16,0 55,7 13,6 55,4 Si 53,2 66,4 84,0 44,3 86,4 44,6 [Pore diameter / scaffold diameter] 4,9 4,6 3,9 3,6 4,2 1,3 Porosity (%) 60 70 80 60 60 40 Compressive strength (MPa) 30 26 5 3 6 32 Elastic modulus (GPa) 5,8 5,6 2,6 5,4 10,8 120 Thermal shock resistance Thermal shock resistance coefficient R' 19 17 7 2 2 1 Result of the rapid heating test fracture No (OK) No (OK) No (OK) Yes (NG) Yes (NG) Yes (NG) Heat resistance Deformation by bending No (OK) No (OK) No (OK) No (OK) Yes (NG) No (OK) *Chemical components: According to JIS R 2011 *Element ratio: According to quantitative EDS analysis *Thermal shock resistance coefficient R': Indication of the indexed value with comparative example 5 as reference

[0066] After producing the cassettes of Working Examples 8 to 10 and Comparative Examples 3 to 5, the thermal shock resistance and the heat resistance were tested, and in each case an improvement in the thermal shock resistance and the heat resistance was found in the Working Examples 8 to 10 compared to Comparative Examples 3 to 5. 1 Core section of the Si-SiC framework 2 pore section 3 Surface layer section of the Si-SiC framework 4 Framework section of the urethane foam 5 Cavity section 7 Metal-Si 8 first layer 9 second layer 10 SiC slurry moldings

Claims

[1] Refractory composite material comprising a Si-SiC sintered body having a framework with a three-dimensional structure, wherein the porosity of the Si-SiC sintered body is 50 to 98%, the SiC content of the framework is 35 to 70 wt.% and the metal Si content of the framework is 25 to 60 wt.%, characterized by , that the three-dimensional structure is mesh-shaped and the scaffold has a porosity of 1% or less. [2] The refractory composite material according to claim 1, wherein the SiC content is 40 to 65 wt% and the Si content is 30 to 55 wt%. [3] The refractory composite material according to claim 1, wherein in the three-dimensional mesh-like structure, the shape of the pores and the framework constituting the three-dimensional mesh-like structure satisfies an average value of ≥ 3 for [pore diameter / framework diameter]. [4] The refractory composite material according to claim 1, wherein the framework density forming the three-dimensional mesh structure is different in the vertical cross section and the horizontal cross section, the framework density in the vertical cross section being 1.1 to 40 times that of the horizontal cross section. [5] The refractory composite material according to claim 1, further comprising a surface coating on the Si-SiC sintered body formed of a material having low reactivity with respect to a workpiece that comes into contact with the surface coating. [6] The refractory composite material according to claim 1, further comprising a compact Si-SiC layer having a porosity of 0.1 to 2% laminated on the Si-SiC sintered body. [7] A refractory composite material according to claim 1, wherein the Si-SiC sintered body has a structure in which layers (8, 9) having different porosity are laminated one on top of the other. [8] A refractory composite material according to claim 7, wherein an uppermost layer in the laminated structure is a compact layer having a porosity of 0.1 to 2%. [9] The refractory composite material according to claim 1, wherein an edge portion of the Si-SiC sintered body forms a frame portion comprising a compact layer having a porosity of 0.1 to 2%. [10] The refractory composite material according to claim 1, further comprising a frame member formed of a nickel alloy supporting the Si-SiC sintered body.

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