JPH029800A - Raw material composition for production of silicon carbide whisker - Google Patents

Abstract

PURPOSE:To continuously and efficiently produce the silicon carbide whiskers on an industrial scale by using a raw material compsn. consisting of silicon dioxide and carbonaceous material and having a specific structure at the time of producing the silicon carbide whiskers by a carbon reduction method. CONSTITUTION:The raw material compsn. for producing the silicon carbide whiskers consists of the silicon dioxide and the carbonaceous material and has 35-85% porosity, 5-1000mum average pore size and three-dimensional network structure. Carbon powder and a binder of a carbonized carbon system are preferably used for the above-mentioned carbonaceous material. Furnace black is particularly preferably as the carbon powder. The above-mentioned carbon binder may be the silicon dioxide or any material which can form the three- dimensional network structure with the silicon dioxide on the surface of the above-mentioned carbon powder; for example, said binder is exemplified by petroleum pitch, petroleum tar, coal tar, furan resin, lignin sulfonate, phenolic resin, etc.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention particularly relates to silicon carbide whiskers used in composite materials such as fiber-reinforced plastics (FRP), fiber-reinforced metals (FRM), and fiber-reinforced ceramics (FRC). Regarding the raw material composition used in the gap produced by the carbon reduction method, the present invention continuously processes silicon carbide whiskers on an industrial scale.
Silicon carbide whiskers suitable for efficient production! !
! This is a proposal regarding a raw material composition for manufacturing.

(Prior art) Currently known SiC whisker bonding methods include a solid phase method using solid raw materials of carbon and silicon, and a gas phase method using gases of carbon and silicon or reactions or mixed gases of them with solids. There is.

In the solid phase method, from solid Sin and C, SiO□+C
':: SiO+ C0540+ 3CO:: S
iC+2CO□Co, +C;: 2CO This is a method of leading to the reaction, and the so-called gaseous Si generated
This is a technique in which O and CO are reacted to precipitate and grow StC whiskers.

For example, the technology belonging to the solid-phase method is
The technique disclosed in Japanese Patent No. 9516 is a method in which rice husk ash is used as a Si source, carbon black is used as a zero source, and heating is performed to 1300 to 1700'C in a non-oxidizing atmosphere.

Furthermore, the technology disclosed in JP-A No. 61-2274)93 uses silicic anhydride as a Si source and activated carbon as a C source.
A method of heating at a temperature of C is described in IJ '41: L/.

As a manufacturing apparatus used to carry out the above-mentioned solid phase method, for example, Japanese Utility Model Publication No. 59-38441 discloses a container for producing SiC whiskers in a river, which is made of graphite material, and Japanese Patent Application Publication No. 1983-38441 discloses a container for producing SiC whiskers in a river. Publication No. 227993 discloses a furnace body having a passage with a temperature gradient along the longitudinal direction, a raw material filling area provided along the passage, a plurality of sample storage having a whisker generation area and an exhaust pipe. We are proposing an apparatus for manufacturing a SiC empty car, which consists of a container and a container.

On the other hand, the gas phase method involves reacting a gaseous silicon halide such as silicon tetrachloride as a Si source with a gaseous carbon compound such as carbon tetrachloride in a hydrogen stream at high temperature;
Methods using thermal decomposition of organic silanes such as methyltrichlorosilane are known.
The technique disclosed in Publication No. 635 introduces halogenated silicon gas and halogenated carbon gas into a heated reaction tube via a carrier gas (11□), and produces a SiC or SiC-containing bottomed tube provided with a plurality of slits. On the cylindrical substrate, S
This is a method for growing iC whiskers, and in Japanese Patent Publication No. 59-45635, a porcelain tube or a graphite tube filled with carbon powder is inserted into the outer tube, and then heated to 1300°C and then heated with silicon tetrachloride. We have proposed a method for producing silicon carbide whiskers by generating a hydrogen gas mixture.

(Problems to be solved by the invention) The above two conventional techniques shown as solid phase methods are (1)
In addition to the generation of a large amount of granular SiC, unreacted granular materials from the raw materials remain and are mixed in the generated SiC whiskers. not obtained, therefore
Further complicated steps are required to separate and purify these particulates, and the yield of whiskers is also low.

(2) Due to the slow reaction rate, it is difficult to continuously produce large amounts of high aspect ratio whiskers.

(3) Reaction temperature is high.

There were problems such as.

In addition, the equipment used in the solid phase method: η is a batch-type production equipment, which not only cannot perform continuous production, but also requires a large number of reaction vessels in order to perform large-scale and efficient production. However, there was a problem in that the equipment became large-scale.

Next, the above two conventional techniques described as gas phase methods both have a problem in that the silicon halide used as the raw material is expensive. In addition, these conventional methods do not contain any specific disclosure regarding continuous production means on an industrial scale.Furthermore, in these methods,
The generated whiskers are fixed and serve as a cylindrical substrate or this substrate! Precipitates and grows on the inner walls of fl pipes.

Therefore, since the precipitation is grown on the substrate, the length, diameter, and other shapes may vary due to subtle temperature variations on the substrate surface, the density of the precipitated whiskers, and differences in reactant gas concentration depending on the location of the substrate. It becomes uniform.

An object of the present invention is to develop a technique that can overcome the problems of the conventional solid phase method and gas phase method described above.

(Means for Solving the Problems) For the purpose of Tamade, the present invention aims to efficiently and continuously produce silicon carbide whiskers on an industrial scale in a solid-phase carbocyclic process using silicon dioxide powder and carbonaceous materials as raw materials. Focusing on the importance of creating a raw material composition suitable for producing °ζ whiskers using the above-mentioned raw materials in order to produce it, the feature is that a space is created in the raw material composition to generate silicon carbide whiskers. We have developed 42 raw material compositions for producing silicon carbide whiskers to solve the above-mentioned problems.

(Function) The basic principle of the present invention is that in the solid phase method using solid raw materials of carbon and silicon, the following reactions are assumed at a given temperature and yarn composition.

■ SiOx + C: SiO+ C0■ SiO
+2C=sic+c.

■ SiC+2Si(h::3SiO・t
CO■ S i + SiO□, II' 2SiO■
C+SiO';: Si+CO ■ SiC+ SiO2Si (-CO In the conventional industrial production of SiC granular materials, -C is produced by the reactions of ■ and ■ when silicon dioxide powder is used as the silicon raw material. .

On the other hand, SiC whiskers are produced by the reaction (1) and the reaction (2), that is, the reaction (3SiO+CO→SiC+2SiO□).

The formation and growth of whiskers is mainly caused by the gas phase reaction of SiO and CO produced in the solid raw material.

This indicates a chemical thermodynamic equilibrium state for the 5i-0-C system, W,8,Krinski and W,rl.

Schumann diagrams (generally known as Schumann diagrams) are known, and are shown by the molar partial pressure ratio and temperature of silicon monoxide and carbon monoxide in this system, and the whisker formation region is It is thought that the process proceeds in the reaction of (■).

Therefore, whiskers can be efficiently generated by appropriately determining the molar partial pressure ratio of silicon oxide and carbon monoxide and the temperature in the system.

Although silicon carbide whiskers are generated based on the above-mentioned basic principle, since the generation region (iii) is a metastable region in terms of equilibrium, appropriate operations may be required. Specifically, as shown in J18 of Japanese Patent Publication No. 54-17720, silicon monoxide gas is generated in a solid phase reaction, and after being introduced into another reactor, the molar partial pressure ratio with carbon monoxide from the outside is determined. After adjusting the temperature of the mixed gas, Si
C whiskers will be generated.

In other words, can the molar partial pressure and temperature be uniformly controlled? In order to produce 1[r], it can be produced efficiently by appropriately selecting and combining raw materials, raw material filling methods, and heating methods.

However, the selection of raw materials and the method of filling the raw materials have a particular influence on the above control, and this needs to be achieved not only in the temperature partial pressure control of the entire device but also in the minute parts of the raw materials. The selection of raw materials is important, and in addition, the formation space must be preserved in whisker production, including the filling method.

Based on the above circumstances, in the present invention, the raw materials are silicon dioxide t5) powder and carbonaceous material, which are made of silicon dioxide and carbonaceous material as described above, and the pores/t are 35 to 85.
% and an average pore diameter of 5 to 1000 μm.
t, and created a composition that fills the formation space necessary for silicon carbide whisker formation.

In other words, in the past, natural porous rice husk ash or silica gel was used as the silicon dioxide raw material in the direct method from solid-phase raw materials, and furnace carbon black with developed struts was used as the carbon raw material. However, the present invention is extremely efficient by forming a whisker forming space inside the raw material in the same way as these.
+iii A composition capable of controlling hill crop production has been newly discovered.

This will be explained in detail below.

First, the 11;I original j4, tjl composition has a porosity of 3
It is necessary that the B content is 5% to 5% and the average pore diameter is 5 to 1000 μm. The porosity of the raw material composition is 35-35.
The reason why it is necessary to be 85% is that the porosity is 35%.
If it is lower, the gas permeability in the composition is poor, the reaction product gas is difficult to release, and the partial pressure of silicon monoxide gas is locally high in the composition (this is because coarse granular silicon carbide is easily formed). On the other hand, it is preferable that the +if porosity is as high as possible in consideration of the reaction generation space of whiskers, but if it is higher than 85%, the strength of the composition will be extremely low, and the composition will be crushed in the reaction field 2z. This is because the filling density inside becomes high and air permeability deteriorates significantly.

Further, the average pore diameter of the raw material composition is 5 to 1000 μm.
The reason why this is necessary is that if the average pore diameter is smaller than 5 μm, the pores will be closed due to melting of silicon dioxide during high-temperature reaction, and if it is larger than 1000 μm, the contact reaction between silicon dioxide and carbonaceous material will be reduced. This is because

It is advantageous to use silicon dioxide having a specific surface area of 0.01 rrf/g or more as the St source in the composition. The reason for this is that if the specific surface area is smaller than 0.01 rrf/g, the reaction efficiency between silicon dioxide and the carbonaceous material decreases, and the gas generation of formula (110) tends to become insufficient. Moreover, silicon dioxide may remain unreacted, or coarse granular materials of silicon carbide may be produced.

Incidentally, the finer the silicon dioxide, the better, but even if a powder that is too fine is available, it is extremely expensive and therefore unsuitable for use as an industrial material.
．． Silicon dioxide in the range of 1 to 10 rd/ε is relatively easy to obtain and also provides suitable results.

The silicon dioxide can be used either naturally or synthetically,
The higher the purity, the better.

On the other hand, as the carbon powder of the carbonaceous material as the C source of the composition, the -silicon oxide gas partial pressure is adjusted,
In order to obtain very good silicon carbide whiskers, it is advantageous to use carbon powder with a specific surface area in the range 1=1000 m"/g. This is because the specific surface area is 1 m"/g.
/ [If it is smaller, there are fewer places where the reaction according to the above formula (1) occurs, and the -silicon oxide production reaction is trlt controlled, making it difficult to efficiently produce the silicon carbide whiskers that are the object of the present invention. On the other hand, 1000m”
Carbon powder with a specific surface area larger than /g is considered to be extremely suitable from the viewpoint of reactivity, but such carbon powder is not only difficult to obtain, but also has an extremely low bulk specific gravity. This is because, when used in the form of granules, the porosity becomes too high and the crushing strength becomes extremely low. Among these, carbon powder in the range of 10 to 500 m"/H is relatively easy to obtain, and Favorable results can be obtained. Carbon powder can be used for contact black, thermal black, furnace black, and lamp blanks obtained by incomplete combustion of petroleum-based or coal-based organic substances, or by thermal decomposition in an inert gas phase. It is preferable to use at least one selected from the following, and among them, furnace black with high strutness is preferable.

Moreover, as the carbonaceous binder as the carbonaceous material,
Any material that can form a three-dimensional network structure on the surface of the silicon dioxide or the silicon dioxide and the carbon powder may be used, such as crude oil, residual oil, petroleum pitch, wood lupidge, furan resin, petroleum tar, coal cour, Lignosulfonate, alginate, phenolic aromatic core polymer saccharide, 1st starch, polyvinyl acetate, tar pitch,
At least one selected from asphalt, chain vinyl systems such as polyacrylonitrile, and polymers consisting of biphenyl bonds between aromatic groups such as polyphenylene, among the above, phenolic resin, $J, W tfi, lignin sulfonate Easily water-soluble carbon-based binders, such as, can be advantageously added in the form of an aqueous solution. Among them, phenolic resins can be advantageously used because they have a relatively high carbon yield, and water-based phenolic resins are particularly suitable. The aqueous phenol is used for the silicon dioxide and +11
Water is used as a medium when mixing with the carbon powder (this is because it allows uniform mixing).

Incidentally, the poorly water-soluble carbonaceous binder is dispersed in water as an emulsion using a solvent and an emulsifier.

That is, the water-resistant carbon-based binder is made into a homogeneous mixture using a solvent, and hot water and an emulsifier are added while heating and stirring to form an emulsion. +'+iJ As the emulsifier, ethylene acetate, modified stearic acid, etc. can be used.

To obtain the silicon carbide whiskers that are the object of the present invention,
This can be achieved by using silicon dioxide and carbonaceous materials as raw materials, which improves air permeability and facilitates the outgassing of CO gas produced during the reaction, making it easier for the reaction to proceed, and reducing monoxide in the reaction vessel. The following manufacturing method is required to obtain a composition having pore diameter, porosity, and strength that allow proper control of silicon gas partial pressure.

According to the present invention, after the tIj compound consisting of borium/iron dioxide, carbon powder, and carbon-based binder is thoroughly and uniformly mixed,
Needs to be freeze-dried.

After making the slurry concentration of the mixture 10 to 50%, 11
By freeze-drying the mixture described in Item 11, water in the mixture is removed while maintaining the three-dimensional network state. This means that the morphology of the mixture determines the structure of the composition after drying, and the moisture wall during mixing and the subsequent drying method are important.

The reason why the slurry concentration of the mixture was set to 10 to 50% is that if the water solvent at the time of mixing is 50% or more, the dispersed mixing state becomes uniform, but after drying, a network of pore spaces is not formed.
Moreover, even if it is formed, the thickness of one mesh-like partition wall is thin and it becomes brittle.

On the other hand, if the water solvent during mixing is less than 10%, the dispersion and mixing state will not be uniform and will become a 'Q cluster' state, making it difficult to obtain a uniform network structure, and the thickness of the partition walls forming pore spaces will be large and the reaction will be reduced. Become.

In addition, the freeze-drying method is used to dry the mixture because, in general heat drying, migration occurs during drying and the pore spaces that are the object of the present invention are not formed, and the three-dimensional network structure that is the object of the present invention is not formed. It is difficult to form.

That is, the shape of the three-dimensional network structure formed after drying is determined by the amount of silicon dioxide and carbonaceous material blended and the amount of solvent, and the pore space ensures a whisker generation space that is rate-determining for the generation of silicon carbide whiskers. It will be done.

According to the present invention, in producing silicon carbide whiskers, the amount of carbon in the raw material is increased to increase the number of locations where the reaction of formula (3) occurs, thereby suppressing the increase in the -silicon oxide gas partial pressure It is effective to
It is advantageous for the o1 molar ratio to be in the range from 3 to 10.

The reason why the C/5i (h molar ratio is set to 3 to 10) is that if the amount of carbonaceous material is less than the theoretical blending amount (C/SiO□ molar ratio 3), the reaction in which silicon dioxide does not become a carbide and is reduced to a metal occurs. Furthermore, if there is too much carbon (2) exceeding the C/SiOx molar ratio 1O, excess carbon will remain, resulting in a decrease in quality, which is not economical.

In addition, the blended weight of the carbon-based binder-based binder as the carbonaceous material, 8 (po) is the total specific surface area of silicon dioxide,
B(nf) is the total specific surface area of the carbon powder. That is,
The amount of the carbon-based binder to be blended is determined based on the total specific surface area of the silicon dioxide and red carbon powder used.

This is because if the blending ratio M is smaller than o or oos, the crushing strength of the three-dimensional network structure within the granular raw material will be low and it will easily collapse during handling and within the reaction vessel.

On the other hand, if the blending ratio M is larger than 0.15, it will melt during the drying process, making it difficult to form a three-dimensional network structure and making it impossible to granulate it.

According to the present invention, the average particle size of the 1111 granules is 3 to 1
It is preferable to set the area within the range of 8 m5 for the following reasons: 1.
If the average particle size of the granules is smaller than 3IIIm, there is little effect as a granule (on the other hand, if it is larger than 181, the reaction rate within the granules becomes slow, making it uneconomical.

According to the present invention, when forming the relatively large granules, silicon dioxide and a carbonaceous material are thoroughly and uniformly mixed together with the composition consisting of this carbon powder and a carbon-based binder. For example, granulation may be performed using a granulator such as a pan-type granulator, a drum-type granulator, a horizontal vibration-type granulator, a briquette machine, or a fluidized mixing granulator; It is preferable to use a freeze-drying method that can process all of the ingredients all at once.

According to the present invention, the high density of granules is 0.20-0.70
Advantageously, it is within the range of g/cj. The reason why it is advantageous to set the true density within the range of 0.20 to 0.70 g/c+j is that although a lower bulk density is preferable in terms of whisker generation space and other aspects, granules with a density lower than 0.20 g/cd In order to achieve this, it is necessary to significantly increase the porosity of the composition, and if the porosity is too high, the strength of the composition will decrease significantly as described above, and the strength of the granular material will also decrease.

On the other hand, if it is higher than 0.70 g/cd, the permeability of the reaction product gas will be poor and the flow of high-temperature gas in the preheating zone will become uneven.
Not only is the heat exchange between the raw material and the high-temperature gas insufficient, but it is also susceptible to the effects of the silicon oxide gas precipitates, which impedes the smooth fall of the raw material under its own weight, resulting in long-term stable operation. This is because it becomes difficult to maintain. Also,
The main purpose is whisker growth space &? It becomes very difficult to maintain f. The bulk density of the granules is 0.30 to 0.
．． (The best results are obtained within the range of i0g8-.

Next, the whisker production reactor used in "Evaluating the original t'at product of the present invention" will be explained.

The granular raw material is charged from two sides of a reaction vessel having a preheating (IF) and a heating (iF) and cooling zone, and the charged raw material is processed while being continuously or intermittently lowered by its own weight in the preheating IF. It is brought to the tropics, heated horizontally in the heating zone to cause a gas generation reaction, and then lowered to the cooling zone and cooled in a non-oxidizing atmosphere. Silicon carbide whiskers are produced by discharging the reaction product intermittently.

Silicon carbide whiskers with extremely low graininess are the object of the present invention! ! ! During the production, the reaction temperature in the heating zone was controlled within the range of 1500 to 2000°C. The reason is that when the reaction temperature is lower than 1500'C, the formula
This is because the reaction rate shown by is extremely slow and it becomes difficult to efficiently produce silicon carbide whiskers.On the other hand, if the temperature is higher than 2000°C, silicon carbide powder is generated and crystals grow. This is because it is difficult to continuously produce β-type silicon carbide whiskers with very little graininess.

Next, one example of a continuous production apparatus used for the raw material composition for producing whiskers of the present invention will be specifically explained with reference to the drawings.

As shown in the figure, the apparatus directly used for carrying out the method of the present invention has a raw material charging port 1, a preheating zone 2, a heating zone 3, a cooling zone 4, and a sealable product outlet 5, which are connected vertically. Reaction vessels 6 connected in different directions, including 11 reactors 6 and 1
．． The tube 7 forming the band is made of graphite and is equipped with means 8.9 for indirectly electrically heating the charge in the heating zone, and at least a heat insulating layer 1 made of carbon or graphite is provided on the outside of the heating zone.
0.

The reaction vessel 6 is installed in the center of the apparatus, and the indirect heating means 8.9 is provided in a space surrounded by a graphite heating element 8 and a graphite reflector cylinder, which is provided close to the outside of the heating element 8. A non-oxidizing gas is charged [from T111, for example, Ar, He, N!
, Co, Hi, and other non-oxidizing gases to prevent the graphite heating element from being consumed by oxidation due to air intrusion.

Example 1 Silicon dioxide powder (S i O! 90.5% > 10
Thermal black powder (fixed carbon 98.5% by weight) 50 trtff with a specific surface area of 20 nf/H relative to the 0-weight star
1 part by weight of polyoxyethylene alkyl phenyl ether as a dispersant, 800 parts by weight of water, and 625 parts by weight of a 40% solution of an aqueous phenol resin containing 20% fixed carbon based on the solid content. After thorough mixing using a plastic ball mill, the mixture was dropped into liquid nitrogen and solidified by freezing. Furthermore, the solidified product was dried in a dryer under reduced pressure of 0.1 Torr to remove moisture. The obtained granules had a filling bulk density of 0.3 g/cJ, an average pore diameter of 2977 m based on observation of the fractured surface of the granules, and a three-dimensional structure in which silicon dioxide and thermal black formed a 14-molecular skeleton. It had a porous LT structure.

The porosity determined by mercury intrusion method was 78%.

Next, this granular material is charged from the upper part of the vertical indirect heating furnace, and is continuously lowered in the heating furnace,
A heating zone was established in which the reaction temperature was controlled at 1800°C. The charge in the heating zone is allowed to fall under its own weight at a rate of 0.2 m/hr while being heated in the horizontal direction by m1 to cause a reaction, and then allowed to fall under its own weight in the cooling (), and the reaction product is discharged from the discharge port. IJF was issued continuously.

Free carbon was removed from the resulting reaction product, and then the product was immersed in a 10% aqueous solution of hydrofluoric acid for 3 hours to remove 'mM silicon dioxide.

The obtained purified product was confirmed to be β-type silicon carbide by X-ray diffraction, and scanning electron l! I′i microscopic observation revealed that silicon carbide whiskers had an average diameter of 0.5 μm, an average length of 6 μm, and contained 12% of particulate matter.

Example 2 Anhydrous tar (ratio I! (1.15, water content 0.3% or less)
360 parts by weight and 360 parts by weight of toluene as a solvent were mixed and dissolved in a stainless steel container with a stirrer.
600 ffiffi parts of warm water at 600 °C and 9 parts by weight of an emulsifier (ethylene acetate + modified stearic acid) were added, and heated and stirred for about 1 hour while maintaining the temperature at 60 °C with a heater to form an emulsion. Adding 100 parts by weight of phosphor and ion dioxide used in Example 1 to the obtained emulsion liquid,
Stirring I↑ was performed in the container for about 2 hours to obtain a mixed solution.

Next, the mixture of 11:1 was freeze-dried in the same manner as in Example 1 to remove water. The obtained granules have a high density of 0. (
It had a three-dimensional network structure with ig/cj, porosity of 58%, and average pore diameter of 210ym.

Synthesis was carried out in the same manner as in Example 1 to obtain a reaction product. The obtained reaction product had an average diameter of 0.2 μm and an average length of 11 μm.
m, β-type silicon carbide whiskers containing 24% particulate matter.

3.4 1 to 3 Same as Example 1, but when using silicon dioxide as a raw material with a specific surface area of 0.22 bo/g and an average particle size of 14 μm (Example 3) Specific surface area, amount of addition, and addition of carbon-based binder (Example 4) When changing synthesis temperature conditions (Example 4) Silicon dioxide was the same as in Example 1, but the specific surface area of carbon powder and amount of addition were changed. and a case where the average pore size of the granules was made larger by changing the amount of solvent added (Comparative Example 1) Same as Example 3, but using pitch as the carbon-based binder and emulsifying with an emulsifier. When the pore diameter was relatively large and the pore size was increased (Comparative Example 2) The results were shown for the same as Example 2, but when the granulation movement was increased using the transfer granulation method (Comparative Example 3). The results are summarized in a table, and the results show that the amount of particulate matter in the reaction product was lower in all Examples than in the Comparative Example.

In Comparative Example 1, the reactor disintegrated into a wrinkled material during synthesis, making it impossible to close the reactor, and no reaction product was obtained.

(Effects of the Invention) As detailed above, the present invention is made of silicon dioxide and a carbonaceous material and has a porosity of 3 as exemplified in the above embodiment.
The composition for producing silicon carbide whiskers has a structural characteristic of 8 to 85% and an average pore size of 5 to 1000 μm, and by using it as a granule with an average particle size of 3 to 1Q mm, it can finally be made into granules. Silicon carbide whiskers containing less Bt in silicon carbide can be obtained.

[Brief explanation of the drawing]

FIG. 1 shows a whisker production reactor used in Examples and Comparative Examples. FIG. 2 is an enlarged cross-sectional view schematically showing a raw material composition for producing silicon carbide whiskers according to the present invention. Explanation of symbols 1-- Raw material charging inlet, 2-- Preheating zone, 3--
・-Heating・((2, 4-...- Cooling zone, 5--Product outlet, 6--Reaction vessel, 7- Heating cylinder; 8-... ...Graphite heating element, 9...
...-Black :) reflective part, 10...--Heat insulation layer, 1
1--Non-oxidizing gas charging port, 12--Indoor electrode, 13--Flexible conductor, 14--Bus bar, 15--@warm bar Eve, 16--Outer shell, 17--Refractory brick, 18--Exhaust duct, 19--Raw material hopper, 21--Silicon dioxide, 22-- ...More than carbonaceous materials

Claims (1)

[Claims] 1) Made of silicon dioxide and carbonaceous material, with a porosity of 35
85%, an average pore diameter of 5 to 1000 μm, and a three-dimensional network structure. 2) The raw material composition for producing silicon carbide whiskers according to claim 1, wherein the carbonaceous material comprises carbon powder and a carbonized carbon-based binder. 3) The raw material composition for producing silicon carbide whiskers according to claim 1, wherein the carbonaceous material comprises a carbonized carbon-based binder. 4) The raw material composition for producing silicon carbide whiskers according to claim 1, which is a granular material having an average particle size of 3 to 18 mm.