Porous silicon carbide body and its manufacturing method

Abstract

To provide a highly pure silicon carbide porous body having a porous structure with a wide range of pore sizes from nanoscale to millimeter scale and showing a fractal property, and provide a method for producing the same.SOLUTION: A silicon carbide porous body has a fractal structure with multiple pores having pore diameters of 100 nm to 1 mm. A method for producing the silicon carbide porous body comprises the steps of: heating an organosilicon compound in a vapor of at least one metal selected from alkali metals and alkaline earth metals to form a composite of silicon carbide and a metal oxide; and eluting the metal oxide from the composite.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a porous silicon carbide body and a method for producing the same. [Background technology]

[0002] Porous materials with minute pores on the nano to micro order are promising materials that are expected to be used in a wide range of applications, including filters, supports for catalysts, heat insulation materials, adsorbents, energy conversion materials, insulating or semiconductor materials, scattering layers for electronic displays, magnetic recording materials, and cell culture substrates. The material for forming such a porous body is appropriately selected depending on the intended use, and typically includes various materials such as polymers, ceramics, and metals. For example, Patent Document 1 describes "a ceramic porous body having a three-dimensional network structure with an overall porosity of 60% to 90%, characterized in that the ceramic porous body is formed by laminating ceramics with a porosity of 30% to 80% on the skeletal surface of a ceramic substrate having a three-dimensional network structure with a porosity of 40% or less." Furthermore, Non-Patent Document 1 describes silicon carbide (SiC) particles having an internal porous structure and a surface covered with protrusions. Furthermore, Patent Document 2 describes "a composite material including a first carbon material having a plurality of pores, silicon particles disposed in the pores, and silicon oxide disposed in the pores," and describes a method for producing this composite material, which includes "a step of preparing a precursor composite including a first carbon material having a plurality of pores and siloxane disposed in the pores; a step of bringing magnesium vapor into contact with the precursor composite to reduce the siloxane to silicon and generate magnesium oxide and silicon oxide in the pores; and a step of removing the magnesium oxide." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-022929 [Patent Document 2] Japanese Patent Application Publication No. 2018-163776

[0004] [Non-Patent Document 1] J. Phys. Soc. Jpn., Vol.78, NO.3, 2009, 034802 Summary of the Invention [Problem to be solved by the invention]

[0005] Among the materials that constitute porous bodies, silicon carbide has a high heat resistance temperature and exhibits excellent properties as a semiconductor material, and therefore, it is expected that these porous bodies will also be used in a variety of applications by taking advantage of their excellent properties. However, in order to apply silicon carbide porous bodies to a variety of applications, there is room for consideration not only of the excellent properties of silicon carbide, but also of the structure (porous structure) of the porous body. However, Patent Documents 1 and 2 and Non-Patent Document 1 do not consider the porous structure, etc. of silicon carbide porous bodies.

[0006] An object of the present invention is to provide a high-purity porous silicon carbide body that has a porous structure with pore sizes ranging from the nanoscale to the millimeter scale and exhibits fractal properties. Another object of the present invention is to provide a simple method for producing a high-purity porous silicon carbide body. [Means for solving the problem]

[0007] The object of the present invention has been achieved by the following means. <1> A porous silicon carbide body with a fractal structure that has multiple pores with diameters of 100 nm to 1 mm. <2> the above <1> A method for producing the silicon carbide porous body according to claim 1, a step of heating an organosilicon compound in vapor of at least one metal selected from alkali metals and alkaline earth metals to form a composite of silicon carbide and an oxide of the metal; eluting the metal oxide from the composite; The method for producing a silicon carbide porous body has the above-mentioned steps. <3> the metal is an alkaline earth metal; <2> The method for producing the silicon carbide porous body according to claim 1. [Effects of the Invention]

[0008] The present invention can provide a high-purity porous silicon carbide body that has a porous structure with pore sizes ranging from the nanoscale to the millimeter scale and exhibits fractal properties. The present invention also provides a simple method for producing a high-purity porous silicon carbide body. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating the steps of forming a complex in the examples. [Figure 2] FIG. 2 shows powder X-ray diffraction charts of the composites and porous silicon carbide bodies synthesized in Examples 1 and 2. [Figure 3] FIG. 3 shows electron microscope images of the composites and porous silicon carbide bodies synthesized in Examples 1 and 2. [Figure 4] FIG. 4 shows the results of fractal dimension analysis of the porous silicon carbide body synthesized in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0010] In this invention and this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the lower and upper limits. In this specification, when multiple numerical ranges are set in stages for the content of a component, physical properties, etc., the upper and lower limits forming the numerical range are not limited to the specific combination written before and after "to", and the upper and lower limit numerical values ​​forming each numerical range can be combined as appropriate.

[0011] [Porous silicon carbide] The silicon carbide porous body of the present invention has a porous structure with a plurality of pores having pore diameters of 100 nm to 1 mm, and exhibits fractal properties. The skeleton of the porous structure of this silicon carbide porous body is formed from high-purity silicon carbide. Here, high-purity silicon carbide is not particularly limited, but refers to a purity in which the peak (the most intense peak) of an alkali metal or alkaline earth metal oxide can be confirmed at approximately the detection limit in a powder X-ray diffraction chart in the Examples described below, specifically a purity of 85 mass% or more. High-purity silicon carbide porous bodies are achieved by the method for producing a silicon carbide porous body of the present invention described below, which has a high conversion rate of raw material compounds and produces little by-products other than silicon carbide during the production process. The silicon carbide porous body is determined to have an appropriate shape depending on the application, etc. Examples of the shape include particulate (granular), sheet, and block shapes.

[0012] The silicon carbide porous body (porous structure) has a plurality of pores (voids) with a pore diameter of 100 nm to 1 mm. The pores may be bottomed holes (holes) or through holes (transmission holes). The pores may exist independently of adjacent pores, or may be connected to adjacent pores to form a continuous pore. The number of pores in the silicon carbide porous body is determined appropriately depending on the application, properties, etc., and may be, for example, 1 mm 2 or less per surface. 2 10 per 2 ~10 8 It can be made into one. The silicon carbide porous body has a plurality of pores with a pore diameter of 100 nm to 1 mm. The presence of a plurality of pores with a pore diameter of 100 nm to 1 mm in the silicon carbide porous body can be confirmed by observing the surface or cross section using a scanning electron microscope (SEM). It is preferable that the majority of the pores in the silicon carbide porous body (e.g., 90% or more of the total number of pores) have a pore diameter of 100 nm to 1 mm. The pore diameter of the silicon carbide porous body is not particularly limited and is determined appropriately depending on the application, etc., but is preferably, for example, 200 nm to 500 μm, and more preferably 300 nm to 300 μm. The pore diameter of each pore can be calculated by image analysis of an SEM image of the silicon carbide porous body.

[0013] The silicon carbide porous body (porous structure) having a plurality of pores has a fractal structure (self-similar structure) (exhibits fractal properties). Specifically, a two-dimensional image is obtained from an SEM image, and the fractal dimension obtained from this two-dimensional image is greater than 1 and less than 2, preferably 1.1 to 1.8, more preferably 1.15 to 1.75, and even more preferably 1.2 to 1.7. The fractal dimension can be calculated from the observed SEM image by a box counting method, and in more detail, can be calculated by the measurement method in the examples described below.

[0014] The physical properties and characteristics of the silicon carbide porous body, such as porosity, are determined appropriately depending on the intended use. The porosity of the silicon carbide porous body can be, for example, 20% or more, and preferably 30% or more. The porosity is the volume ratio of the volume of pores (air in the pores) (A) to the apparent volume (including pores) (D) of the obtained silicon carbide porous body, and can be calculated by the formula: A / D x 100 (%). The apparent volume (including pores) (D) of the silicon carbide porous body can be measured by measuring the length, width, and height of a sample at 25°C, and the pore volume (A) can be measured by measuring the diameter of the pores using an SEM or the like at 25°C and multiplying this by the pore density. When the silicon carbide porous body is in the form of a sheet, its thickness is determined appropriately depending on the intended use, etc., and can be, for example, 0.1 to 20 mm.

[0015] The silicon carbide (SiC) forming the silicon carbide porous body may have any crystal system (crystal structure), or may have a mixture of multiple crystal systems. Examples of the crystal system of silicon carbide include hexagonal, cubic, and rhombohedral crystals. The silicon carbide porous body is formed from high-purity silicon carbide, but may contain components other than silicon carbide. The purity of the silicon carbide porous body varies depending on the production method, production conditions, etc., but is as described above. Examples of components other than silicon carbide include inevitable impurities in the raw material compounds, by-products, and metal oxides, which will be described later.

[0016] The porous silicon carbide body of the present invention, particularly the porous silicon carbide body produced by the method for producing a porous silicon carbide body of the present invention, is formed from high-purity silicon carbide as described above and has a porous structure formed of a plurality of pores with a wide range of pore sizes from the nanoscale to the millimeter scale. This porous silicon carbide body exhibits fractal properties and can achieve a high porosity. The silicon carbide porous body of the present invention can be used for the above-mentioned applications depending on its physical properties and characteristics, and is particularly suitable for various applications such as energy conversion materials and semiconductor materials.

[0017] [Method for manufacturing porous silicon carbide] The method for producing a silicon carbide porous body of the present invention (hereinafter sometimes simply referred to as the production method of the present invention) comprises the following steps. Complex formation step: a step of heating an organosilicon compound in vapor of at least one metal selected from alkali metals and alkaline earth metals to form a complex of silicon carbide and an oxide of the metal. Leaching step: A step of eluting metal oxide from the composite obtained in the composite formation step.

[0018] <Complex formation process> The metal used in the composite formation step is an alkali metal or alkaline earth metal, with alkaline earth metals being preferred. Usually, one metal species is used, but multiple species, for example, two or more, may be used. Examples of alkali metals (metals belonging to Group 1 of the periodic table) include lithium, sodium, potassium, rubidium, and cesium. Examples of alkaline earth metals (metals belonging to Group 2 of the periodic table) include beryllium, magnesium, calcium, strontium, barium, and radium, with magnesium being preferred.

[0019] The organosilicon compound (organosilicon compound) may be any compound that can be converted to silicon carbide, and examples thereof include silicon compounds having a main skeleton consisting of -Si-O- bonds and at least one organic group. Among these, polysilsesquioxane compounds are preferred, and (RSiO 1.5 ) n (R represents a hydrogen atom or a substituent, at least one of which is an organic group or has an organic group, and n is a number of 2 or more), and a cage polysilsesquioxane compound (POSS) is even more preferred. In the present invention, the polysilsesquioxane compound encompasses oligosilsesquioxane compounds. The substituents of the organosilicon compound are not particularly limited and can be hydrogen atoms or various other substituents, but at least one of the substituents is preferably an organic group. Examples of the substituent include an organic group and a silyloxy group (-O-Si(R)H (R represents an organic group)). The organic group of the organosilicon compound is not particularly limited as long as it contains carbon atoms, and examples thereof include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an aliphatic heterocyclic group, and an aromatic heterocyclic group, with an aliphatic hydrocarbon group and an aromatic hydrocarbon group being preferred. The aliphatic hydrocarbon group is not particularly limited and examples thereof include an alkyl group, an alkenyl group, and an alkynyl group, with an alkyl group and an alkenyl group being preferred. The structure of the aliphatic hydrocarbon group may be a straight chain, a branched chain, or a cyclic chain. The aromatic hydrocarbon group may be a monocyclic or fused ring. The number of carbon atoms in the aliphatic hydrocarbon group and the aromatic hydrocarbon group are not particularly limited and can be, for example, 1 to 26.

[0020] As the organosilicon compound, those shown in the following formulas 1 to 5 are preferred. [ka]

[0021] In each formula, R is a hydrogen atom or a substituent, as described above, but the following are particularly preferred. [ka]

[0022] In the composite formation step, an organosilicon compound is brought into contact with metal vapor and heated. That is, the organosilicon compound is heated in a metal vapor atmosphere. As a result, the organosilicon compound is decomposed and reduced to form silicon carbide, and the metal is oxidized to form a metal oxide, resulting in a composite of silicon carbide and metal oxide. The resulting composite may be a simple mixture of silicon carbide and metal oxide, but is preferably a composite in which silicon carbide and metal oxide are integrated and the metal oxide is dispersed in the silicon carbide. It is preferable that the metal oxide is dispersed in the silicon carbide in a microphase-separated state in order to form a porous structure.

[0023] The complex formation step can be carried out, for example, by placing an organosilicon compound and a metal in a reaction vessel or the like and heating them to generate metal vapor within the system. The conditions for the complex formation step may be any conditions that allow the formation of the complex. The metal is usually used in the form of powder, ribbon, pellet, or the like. The metal does not need to be premixed with the organosilicon compound as long as its vapor can contact the organosilicon compound. The mixing ratio of the organosilicon compound and the metal is not particularly limited and is determined appropriately depending on the porous structure of the desired silicon carbide porous body. For example, the metal may be 1.0 part by mass or more, preferably 2.0 to 10 parts by mass, and more preferably 2.5 to 10 parts by mass, per part by mass of the organosilicon compound. The heating atmosphere may be a metal vapor atmosphere or an inert gas atmosphere as long as metal vapor is present. Examples of inert gas include rare gases such as helium and argon, and nitrogen gas. The pressure of the heating atmosphere is not particularly limited and may be vacuum, reduced pressure, atmospheric pressure, or pressurized pressure. The heating temperature is determined appropriately depending on the type of metal and can be, for example, 300° C. or higher, and preferably 500 to 1500° C. More specifically, when magnesium is used, the heating temperature is preferably 900° C. or higher, and more preferably 1000 to 1500° C., in order to produce silicon carbide (form a high-purity composite) while suppressing the production of by-products. The heating time is determined appropriately and can be, for example, 1 to 20 hours.

[0024] In the composite formation step, the production of by-products such as silicon and silicon oxide is suppressed, and the composite can be formed with high purity and high yield (high conversion rate, high efficiency).

[0025] <Elution process> The leaching step is a step of leaching the metal oxide from the composite obtained in the composite-forming step, and typically uses a dissolving solution that does not dissolve silicon carbide but dissolves (by decomposing or reacting with) the metal oxide. The dissolving solution is not particularly limited and may be appropriately determined depending on the type of metal oxide, etc., and examples thereof include aqueous solutions of acids or alkalis. Examples of acids include inorganic acids such as sulfuric acid, boric acid, phosphoric acid, hydrogen chloride (hydrochloric acid), and nitric acid, and organic acids such as acetic acid, oxalic acid, succinic acid, and malonic acid, with inorganic acids being preferred. Examples of alkalis include ammonium salts such as ammonium chloride, and hydroxides of alkali metals or alkaline earth metals. The acid or alkali is preferably used as an aqueous solution, but it can also be used as a solution in a water-soluble organic solvent such as alcohol, or as a mixed solution of water and an organic solvent. The concentration of the aqueous solution is appropriately determined taking into account the reaction time, etc., and can be, for example, 1 to 3 mol / L.

[0026] The elution step is carried out, for example, by contacting the complex with a dissolution solution, preferably by immersing the complex in the dissolution solution. The conditions for the elution step may be any conditions that allow the metal oxide to be eluted. The mixing ratio of the complex to the dissolving solution is not particularly limited and may be determined appropriately. For example, the dissolving solution may be 1 part by mass or more, preferably 50 to 500 parts by mass, per 1 part by mass of the complex. The elution temperature (contact temperature) may be determined appropriately depending on the type of metal oxide, etc., and may be, for example, 5 to 80°C, preferably 10 to 30°C. The elution time (contact time) may be determined appropriately and may be, for example, 2 to 100 hours. When the complex is not immersed in a dissolution solution, the atmosphere in the elution step is not particularly limited and is usually an air atmosphere or an inert gas atmosphere. The pressure of the atmosphere is not particularly limited and may be vacuum, reduced pressure, atmospheric pressure, or increased pressure.

[0027] In the leaching step, the metal oxides dispersed in the composite are leached out, and a porous skeleton made of silicon carbide can be formed.

[0028] In the manufacturing method of the present invention, in order for the silicon carbide porous body to exhibit fractal properties, it is necessary for the body to have pores of various size scales. Small-scale pores are formed by phase separation between silicon carbide and the oxide of the above metal in a composite of silicon carbide and the oxide of the above metal. Since this is generally a few nanometers to a few tens of nanometers, small pores are formed by the elution of the oxide of the above metal. On the other hand, large-scale pores are thought to be formed by gas generated during the decomposition and reduction of organosilicon compounds. While it is fundamentally difficult to control the pores formed to a specific size, pores of various scales can be formed. As described above, the formation of small-scale pores and large-scale pores is thought to form a fractal structure having multiple pores with pore diameters of a few nanometers to mm, particularly 100 nm to 1 mm.

[0029] As described above, the production method of the present invention makes it possible to simply and efficiently (high yield, high conversion rate) produce a high-purity silicon carbide porous body having a porous structure with pore sizes ranging from the nanoscale to the millimeter scale and exhibiting fractal properties. [Example]

[0030] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited thereto.

[0031] As an organic silicon compound, 1,3,5,7,9,11,13,15-octaphenylpentacyclo9.5.1.1 3,9 .1 5,15 .1 7,13 Octasiloxane (Octaphenyl-POSS, C 48 H 40 O 12 Si8 (o-POSS, manufactured by Aldrich, a compound in which all eight Rs in the above formula 1 are phenyl groups) was prepared.

[0032] [Example 1] Approximately 100 mg of the organosilicon compound 21 powder was placed in a boron nitride crucible 12 (inner diameter φ6 mm × height 13 mm, manufactured by Showa Denko K.K., 99.5%), and approximately 250 mg of Mg powder 22 was placed in a separate boron nitride crucible 13. As shown in FIG. 1 , the crucible 12 containing the organosilicon compound 21 was placed on top of the crucible 13 containing the Mg powder 22, and the two crucibles were placed vertically in a stainless steel container 11 (inner diameter φ9 mm × height 80 mm), filled with argon gas, and sealed. Next, the container 11 was heated in an electric furnace at 900 °C for 10 hours, after which the heater was turned off and the container was cooled to room temperature (composite formation step). After heating, the container 11 was opened in the atmosphere, and the sample (the composite of Example 1) was removed from the crucible 12. During heating, the container 11 was filled with Mg vapor (0.2 atm) (melting point: 650° C.). Next, the obtained sample was immersed in a hydrochloric acid aqueous solution with a concentration of 2 mol / L for 48 hours (elution step). In this way, the silicon carbide porous body of Example 1 was obtained.

[0033] [Example 2] A composite and a silicon carbide porous body of Example 2 were obtained in the same manner as in Example 1, except that the heating temperature in the composite formation step was changed to 1100°C. During the composite formation process, the container was filled with Mg vapor (1.1 atm) during heating.

[0034] [evaluation] The crystalline phases of the composites and porous silicon carbide bodies of Examples 1 and 2 were identified by powder X-ray diffraction measurement (Bruker D2 Phaser, CuKα radiation (1.5418 Å)). The morphology of the bulk bodies was also observed using a scanning electron microscope (SEM) and an attached energy dispersive analyzer (JEOL JXA-8200 system SEM-EPMA), and qualitative analysis of the constituent elements was performed.

[0035] <Powder X-ray diffraction measurement> The results of powder X-ray diffraction measurements of the composites and silicon carbide porous bodies of Examples 1 and 2 are shown in Fig. 2. In Fig. 2, (a) shows the diffraction chart of the composite of Example 1, (b) shows the silicon carbide porous body of Example 1, (c) shows the composite of Example 2, and (d) shows the diffraction chart of the silicon carbide porous body of Example 2. In addition, the simulation patterns of α-SiC and MgO are shown together at the bottom of Fig. 2.

[0036] <SEM Observation> The results of SEM observations of the composites and silicon carbide porous bodies of Examples 1 and 2 at four magnifications are shown in Fig. 3. In Fig. 3, (a) shows the SEM image of the composite of Example 1, (b) shows the silicon carbide porous body of Example 1, (c) shows the composite of Example 2, and (d) shows the SEM image of the silicon carbide porous body of Example 2. In Fig. 3, the results of increasing the resolution from the topmost SEM image to the bottommost SEM image are shown. The top two SEM images are referred to as "low-resolution SEM images", and the bottom two SEM images are referred to as "high-resolution SEM images".

[0037] <Calculation of Fractal Dimension> Fractal dimension analysis was performed on the SEM image of the silicon carbide porous body of Example 2 by the box-counting method using image analysis software (Image J, manufactured by NIH). After binarizing the obtained SEM image into pores and SiC parts, fractal dimension analysis was performed using a box-counting method plug-in. The obtained results are shown in Fig. 4. In Fig. 4, the vertical axis is the length of the counted line segments, and the horizontal axis is the box size.

[0038] <Discussion> The following can be understood from the powder X-ray diffraction chart. As shown in Fig. 2, diffraction peaks derived from MgO and α-SiC were observed in the composites of Examples 1 and 2 (Fig. 2(a) and Fig. 2(c)). The diffraction peaks of α-SiC and MgO in the composite of Example 1 were broader than those of the composite of Example 2. This suggests that the lower the heating temperature, the smaller the particle size of the generated α-SiC and MgO, or the lower the crystallinity of those phases. It is presumed that α-SiC and MgO were produced by the reaction between the decomposition products of the organosilicon compound caused by heating during the composite formation process and the Mg vapor that filled the container.

[0039] The porous silicon carbide bodies of Examples 1 and 2 obtained by immersing the composites of Examples 1 and 2 in a 2 mol / L aqueous hydrochloric acid solution for two days (the elution step) showed no visible changes in the color or morphology of the composites. However, the main diffraction peaks in the powder XRD patterns of both porous silicon carbides were those attributable to α-SiC, and the only diffraction peak for MgO was a weak peak at 42.9°, its strongest peak (Figures 2(b) and 2(d)). This suggests that most of the MgO in the composites was removed (eluted) from the composites by the reaction with the aqueous hydrochloric acid solution as shown in the following formula: MgO + 2HCl → MgCl2 + H2O

[0040] On the other hand, the results of SEM observation reveal the following: The composites of Examples 1 and 2 were both black, distorted lumps, and as shown in Figures 3(a) and 3(c), were porous bodies having numerous pores with diameters of several hundred microns. 3(b) and 3(d), the silicon carbide porous bodies of Examples 1 and 2 are black, distorted blocks, and have multiple small pores with diameters of 100 nm to several tens of microns, which are not seen in composites. As such, it is clear that these silicon carbide porous bodies are porous bodies having multiple pores with diameters of 100 nm to 1 mm. Furthermore, differences in the morphology of the observed samples due to the heating temperature in the composite formation process and before and after the acid treatment (elution process) were evident in the high-resolution SEM images (though they could not be confirmed in the low-resolution SEM images). The surfaces of the composites of Examples 1 and 2 were relatively smooth and dense, although there were some undulations of several tens of nanometers (see the third and fourth rows of Figure 3(a) and the third and fourth rows of Figure 3(c)). On the other hand, the surfaces of the porous silicon carbide bodies of Examples 1 and 2 were rough and not dense, and numerous particle aggregates were observed, which contained a relatively large number of voids (see the third and fourth rows of Figure 3(b) and the third and fourth rows of Figure 3(d)). From the powder XRD measurement results and the elemental composition analysis (of the particles) by EPMA, the particles forming the porous silicon carbide bodies of Examples 1 and 2 were identified as α-SiC. The porous silicon carbide body of Example 1 was an aggregate of α-SiC granular particles of 10 to 30 nm. Furthermore, in addition to the α-SiC particles of several tens of nanometers observed in the porous silicon carbide body of Example 1, the porous silicon carbide body of Example 2 also contained numerous linear particles with a diameter of approximately 50 nm and a maximum length of 500 nm.

[0041] As a result of the above fractal dimension analysis, it was found that the fractal dimension of the silicon carbide porous body of Example 2 was 1.2. This is equivalent to the fractal dimension of the Koch curve, and it was revealed that the obtained silicon carbide porous body has fractal properties.

[0042] As shown in the results of Examples 1 and 2, according to the present invention, the target composite can be produced with high purity and high yield (high conversion rate, high efficiency) while suppressing the production of by-products such as silicon and silicon oxide derived from the organosilicon compound in the composite formation step. As a result, a high-purity porous silicon carbide body having a porous structure with a wide range of pore sizes from the nanoscale to the millimeter scale and exhibiting fractal properties can be produced by a simple method. [Explanation of symbols]

[0043] 11 Container 12 Crucible 13 Crucible 21 Organosilicon Compounds 22 Mg powder

Claims

1. A porous silicon carbide body having a fractal structure with a plurality of pores having a pore diameter of 100 nm to 1 mm and a fractal dimension of 1.1 to 1.8 when a scanning electron microscope image is measured by a box counting method.

2. A method for producing the silicon carbide porous body according to claim 1, a step of heating an organosilicon compound in vapor of at least one metal selected from alkali metals and alkaline earth metals to form a composite of silicon carbide and an oxide of the metal; eluting the metal oxide from the composite; The method for producing a silicon carbide porous body has the above-mentioned steps.

3. The method for producing a silicon carbide porous body according to claim 2 , wherein the metal is an alkaline earth metal.

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