JPS6214647B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention mainly relates to a method for producing silicon carbide fibers made of SiC. The present inventors previously applied for a patent in the 1970s.
No. 50223, patent application No. 50-52471, patent application No. 50-52472
Japanese Patent Application No. 50-58033, Japanese Patent Application No. 58034, Japanese Patent Application No. 70302, Japanese Patent Application No. 70303, Japanese Patent Application No. 1987
−77219, Patent Application No. 1972-79972, Patent Application No. 1972-
As described in No. 107371 and Japanese Patent Application No. 51-19378, an organosilicon polymer compound whose main skeleton components are silicon and carbon is spun into fibers, and the spun fibers are treated in an oxidizing atmosphere. After melting, in vacuum or inert gas, CO gas, hydrogen gas, hydrocarbon gas,
After preheating in at least one atmosphere selected from organosilicon compound gas and ammonia gas, in vacuum or in at least one atmosphere selected from inert gas, CO gas, and hydrogen gas. We have invented that silicon carbide fibers can be obtained by high-temperature firing in the temperature range of 1000-2000°C. The present invention relates to an improvement on the above-mentioned invention by the present inventors, and is to produce silicon carbide fibers mainly made of SiC at low cost and in large quantities, which have high strength, high elasticity, and excellent oxidation resistance at high temperatures. The present invention was completed based on the new finding that the above-mentioned infusibility treatment can be carried out by irradiation. Conventionally, organosilicon polymer compounds are spun, and in order to make the spun yarn infusible, 50 to 400
Infusibility treatment has been carried out by heating in the temperature range of °C to create an oxide film. However, in this case, only organosilicon polymer compounds with a softening temperature of 50°C or higher can be used; if an organosilicon polymer compound with a low softening temperature is used, it is necessary to raise the softening temperature by solvent extraction and aging. Ta. In the present invention, in order to improve this drawback, by making it infusible by irradiation, it is possible to use organosilicon polymer compounds containing low molecular weight compounds, which could not be used until now, as raw materials. Now I can do it. In other words, an organosilicon polymer compound containing a low molecular weight compound is used as a raw material, and the spun yarn produced by spinning this is subjected to an oxidizing atmosphere, vacuum, inert gas, hydrogen gas, CO,
The spun yarn is made infusible by heating if necessary under at least one atmosphere selected from CO ₂ , ammonia, hydrocarbon gas, and organosilicon compound gas, and irradiating it while applying tension if necessary, By firing in a post-process, silicon carbide fibers can be obtained. Next, the present invention will be explained in detail. Organosilicon compounds (1) that can be used as starting materials for the silicon carbide fibers of the present invention
Any one selected from those classified as type (10)
It consists of a species or two or more species. (1) Organosilicon compounds containing only Si-C bonds,
called silahydrocarbon
R ₄ Si, R ₃ Si (R′SiR) _o R′SiR ₂ , etc. and their carbon −
Functional derivatives belong to this category. Example (CH ₃ ) ₄ Si, (CH ₂ = CH) ₄ Si, (CH ₃ ) ₃ SiC
=CSi(CH ₃ ) ₃ , (CH ₂ ) ₅ Si(CH ₂ ) ₄ ,
(C ₂ H ₅ ) ₃ SiCH ₂ CH ₂ Cl, (C ₆ H ₅ ) ₃ SiCO ₂ H

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

[Formula] (2) Organosilicon compounds containing Si-H bonds in addition to Si-C bonds, such as mono-, di-, and triorganosilanes, belong to this category. Examples (C ₂ H ₅ ) ₂ SiH ₂ , (CH ₂ ) ₅ SiH ₂ ,
_{( CH3} ) _3SiCH2Si ( _CH3 ) _2H , _{ClCH2SiH3 ,}

【formula】

【formula】

【formula】

[Formula] (3) Organosilicon compound having a Si-Hal bond An organohalogen silane other than monosilane. Example CH ₂ = CHSiF ₃ , C ₂ H ₅ SiHCl ₂ , (CH ₃ ) ₂
(ClCH ₂ )SiSi(CH ₃ ) ₂ Cl, (C ₆ H ₅ ) ₃ SiBr,

【formula】

[Formula] (4) An organosilicon compound organoalkoxy (or alloxy) silane having a Si-OR bond. Example (CH ₃ ) ₂ Si (OC ₂ H ₅ ) ₂ , C ₂ H ₅ SiCl ₂
( _OC2H5 ), P _{- ClC6H4OSi} ( _CH3 ) _{3 ,}

[Formula] (5) Organosilicon compound having a Si-OH bond Examples of organosilanols (C ₂ H ₅ ) ₃ SiOH, (CH ₃ ) ₂ Si(OH) ₂ ,
_C6H5Si (OH) ₃ , ( _HO ) _{( CH3} ) _2SiCH2Si
( _CH3 ) ₂・(OH)

[Formula] (6) Examples of organosilicon compounds containing Si-Si bonds (CH ₃ ) ₃ SiSi(CH ₃ ) ₂ Cl, (CH ₃ ) ₃ SiSi
( _CH3 ) ₃ , ( _{C6H5 ) 3SiSi} ( _{C6H5 ) 2Si} ( _C6H5 ) _{2Cl ,}

【formula】

【formula】

【formula】

【formula】

【formula】

【formula】

[Formula] (7) Organosilicon compound organosiloxane containing a Si-O-Si bond. Example (CH ₃ ) ₃ SiOSi(CH ₃ ) ₃ , HO(CH ₃ ) ₂ SiOSi
( _CH3 ) _2OH , _Cl2 ( _CH3 )SiOSi( _CH3 )ClOSi
(CH ₃ )Cl ₂ , [(C ₆ H ₅ ) ₂ SiO] ₄ , CH ₂ =C
(CH ₃ )CO ₂ CH ₂ Si・(CH ₃ ) ₂ CH ₂ O ₂ C (CH ₃ )=
CH ₂

【formula】

【formula】

【formula】

【formula】

【formula】

[Formula] (8) Organosilicon compound ester; an ester thought to be formed from silanol and acid,
(CH ₃ ) ₂ Si(OCOCH ₃ ) ₂ , etc. belong to this category. (9) Organosilicon compound peroxide;
(CH ₃ ) ₃ SiOOC・(CH ₃ ) ₃・(CH ₃ ) ₃ SiOOSi
( _CH3 ) ₃ etc. (10) Examples of organosilicon compounds with Si-N bonds (C ₂ H ₅ ) ₃ SiNH ₂ , (CH ₃ ) ₃ SiNHSi
( _CH3 ) ₃ , ( _CH3 ) _3Si (CN)( _CH3 ) _3SiNCO ,
(CH ₃ ) ₃ SiNCS, (11) Organometallic compounds containing group metals (coordination compounds) Examples BCH ₅ O ₂ , BC ₃ H ₉ , AlC ₂ H ₇ , GaCH ₃ O,
InC ₂ H ₈ N, InC ₃ H ₉ , TlC ₃ H ₉ , Sc
(CH ₃ COCHCOCH ₃ ) ₃ , La
( _{CH3COCHCOCH3 )3 ,} Ce
(CH ₃ COCHCOCH ₃ ) ₄ , Pr
( _CH3COCHCOCH3 ) _{3 ,} Nd
(CH ₃ COCHCOCH ₃ ) ₃ , Sm
(CH ₃ COCHCOCH ₃ ) ₃ , Eu
( _CH3COCHCOCH3 ) _{3 ,} Gd
( _CH3COCHCOCH3 ) _{3 ,} Tb
(CH ₃ COCHCOCH ₃ ) ₃ , Dy
(CH ₃ COCHCOCH ₃ ) ₃ , Ho
(CH ₃ COCHCOCH ₃ ) ₃ , Er
(CH ₃ COCHCOCH ₃ ) ₃ , Tm
(CH ₃ COCHCOCH ₃ ) ₃ , Yb
(CH ₃ COCHCOCH ₃ ) ₃ , Ln
(CH ₃ COCHCOCH ₃ ) ₃ In the present invention, an organosilicon polymer compound having silicon and carbon as main skeleton components, for example, a compound having the following molecular structure, is produced from the above-mentioned raw materials. (stomach)

【formula】 (B)

【formula】 (c)

[Formula] n=3, polysiltrimethylene n=6, polysilphenylene n=12, polysildiphenylene (d) The skeleton components described in (a) to (c) above are combined into a chain, cyclic and three-dimensional structure or a mixture of (a), (b), and (c). In the method of the present invention, the starting materials (1) to
In order to produce an organosilicon polymer compound whose main skeleton components are silicon and carbon from organosilicon compounds belonging to the classification type (10), organosilicon compounds belonging to the classification types (1) to (10) above must be used. is subjected to a polycondensation reaction using at least one of irradiation, heating, and addition of a polycondensation catalyst. For example, by selecting 10 compounds from among the organosilicon compounds belonging to the classification types (1) to (10) above, a catalyst, irradiation, and heating are used to obtain an organosilicon polymer compound whose main skeleton components are silicon and carbon. The reaction formula of a known reaction involving at least one of the following is as follows. Furthermore, one or more organosilicon compounds selected from the organosilicon compounds belonging to the classification types (1) to (10) above are heated in a temperature range of 200 to 1500°C in a vacuum or with an inert gas or hydrogen. gas, CO
Under any atmosphere selected from gas, CO ₂ gas, hydrocarbon gas, and organosilicon compound gas,
An organosilicon polymer compound having silicon and carbon as main skeleton components can be synthesized by polymerization under pressure if necessary. The reason for the temperature range of 200 to 1500°C in the above synthesis reaction is that at temperatures lower than 200°C, the synthesis reaction does not proceed sufficiently, and at temperatures higher than 1500°C, SiC compounds are formed, which can be made into fibers in a later process. Therefore, it is necessary to use a temperature range of 200-1500℃, and the best results are obtained in a temperature range of 300-1200℃. In the synthesis reaction, a radical initiator may be added and mixed in an amount of 10% or less to the starting materials, if necessary. As the radical initiator, benzoyl peroxide, di-tert-butyl peroxyoxalate, di-tert-butyl peroxide, azoisobutyronitrile, etc. can be used. Although these radical initiators are not necessarily required in the synthesis reaction, their use can lower the reaction initiation temperature by subsequent heating or increase the average molecular weight of the heated product. . In the synthesis reaction, if oxygen is present during the heating reaction, the radical polycondensation reaction will not occur due to oxygen, or even if it occurs, it will stop midway.
It is necessary to heat under at least one atmosphere selected from inert gas, hydrogen gas, CO gas, CO ₂ gas, hydrocarbon gas, and organosilicon compound gas, or under vacuum. During the pyrolysis polycondensation reaction in the synthesis reaction,
Since pressure is applied, pressurization is not necessarily necessary, but if pressurized, any one selected from the above-mentioned inert gas, hydrogen gas, CO gas, CO ₂ gas, hydrocarbon gas, and organosilicon compound gas is used. Alternatively, pressure can be applied using two or more atmospheres. The mechanism by which an organosilicon polymer compound having silicon and carbon as main skeleton components is produced by the synthesis reaction will be described below, for example, in the case of synthesis from methylchlorosilane. That is, the methyl group of methylchlorosilane decomposes into methyl radicals and silyl radicals by heating. Among these, the methyl free radical extracts hydrogen from the methyl group bonded to silicon and becomes a carbon free radical, which itself becomes methane gas. On the other hand, hydrogen radicals are generated from silicon-bonded methyl groups, and carbon radicals are also generated at the same time. It is believed that the silyl free radicals and carbon free radicals generated as described above combine to form a bond between silicon and carbon, and based on these reactions, an organosilicon polymer compound is generated, and the hydrogen free radicals become hydrogen gas. It will be done. An example of a device for carrying out the synthesis reaction is a stationary autoclave. In this case, the heating temperature is preferably in the range of 300 to 500°C. Further, another example of carrying out the above-mentioned synthesis reaction is shown in FIG. In Fig. 1, the raw material is charged into the heating reaction tower 2 through the valve 1, and the temperature range is 300 to 1500°C.
It is preferably heated in a temperature range of 600 to 1200°C, and a part of the organosilicon polymer compound for silicon carbide fibers of the present invention in the reaction product is taken out of the system through valve 3, and is also produced in heating reaction tower 2. The low molecular weight compounds are sent to the separation column 5 via valve 4 and separated by distillation, the gas is discharged to the outside of the system via valve 6, and the high molecular weight polymer is taken out of the system via valve 7. Note that the low molecular weight compounds separated in the separation column 5 are circulated again to the heating reaction column 2 via a valve 8. In the production method of the present invention, the reason why an organosilicon polymer compound whose main skeleton components are silicon and carbon is used as a raw material for spinning is that even if silicon or carbon is present as a side chain, it is easily separated and volatilized by heating. However, on the other hand, silicon and carbon that constitute the skeleton components do not easily decompose and volatilize even when heated, and silicon and carbon can combine at high temperatures to form SiC. In addition, one or more organosilicon compounds selected from the organosilicon compounds belonging to the classification types (1) to (10) above may be used in a vacuum or in an inert gas, hydrogen gas, CO gas, oxidizing gas, At least one selected from gamma rays, X-rays, electron beams, and light is applied in an atmosphere selected from hydrocarbon gas and organosilicon compound gas, while heating as necessary. By irradiating it, a polymerization reaction can be carried out and an organosilicon polymer compound can be produced. When irradiating with γ-rays, the dose of γ-rays is preferably within the range of 1×10 ⁶ to 1×10 ¹¹ Roentgens. If the irradiation is less than 1× ¹⁰⁶ Roentgen, the polymerization reaction will not proceed sufficiently;
It is not economical to irradiate more than 10 ¹¹ X-rays. When irradiating X-rays, an output of 1KV or more is required. When using an electron beam, the acceleration voltage of the electron beam is preferably within the range of 0.1 to 1 x ¹⁰³ kilovolts; if it is lower than 0.1 millivolt, the polymerization reaction will not proceed, and if it is higher than 1 x ¹⁰³ kilovolts, the polymerization reaction will not proceed. This is not suitable because the energy is too strong and the polymerization reaction progresses too much. When irradiating with light, good results can be obtained by using a power within the range of 10 to 1×10 ⁷ watts.
If it is less than 10 watts, the polymerization reaction will not occur, and 1×
If the amount is more than 10 ⁷ watts, the polymerization reaction will proceed too much, which is not practical. The various irradiation times include gamma rays,
It is economical to perform X-ray and light irradiation for 1 to 100 hours. In the case of electron beam irradiation, it is economical to perform it within 10 hours. Further, when performing the above-mentioned irradiation, heating to a temperature of 300° C. or lower may be advantageous because the polymerization reaction is accelerated. Furthermore, examples of organosilicon polymer compounds containing different elements other than silicon, carbon, hydrogen, and oxygen that can be used in the present invention include the following (v) to (g). (E)

【formula】 polysilazane (F)

[Formula] Polysilthian(t) Polymer having a carborane nucleus The organosilicon polymer compound containing the above-mentioned different element can be synthesized by a known method. In addition to the organosilicon compound containing a different element synthesized by the known method, at least one organosilicon compound selected from (1) to (10) above, and the organometallic compound of (11) above. A polycondensation reaction can be performed on a mixed raw material with at least one of heating and irradiation to produce an organosilicon polymer compound containing a different element other than silicon, carbon, oxygen, and hydrogen. The conditions for the polycondensation reaction by heating and irradiation are the same as described above. The ratio of mixing the organometallic compound to the organosilicon compound is preferably in the range of 0.01 to 20% of the different elements contained in the produced polymer, and the amount of the different elements is
If the amount of the different element is less than 0.01%, the effect of adding the different element will not be noticeable, and if the amount of the different element exceeds 20%, an organosilicon polymer compound containing the different element will not be produced, so a range of 0.01 to 20% is preferable. be. The softening temperature of the organosilicon polymer compound that is the raw material for the silicon carbide fiber is not constant. Even an organosilicon polymer compound having a softening temperature below room temperature may be spun while being cooled, and then the spun yarn may be made infusible while being cooled. However, spinning and infusibility while cooling are not practical. Therefore, the softening temperature of the organosilicon polymer compound is preferably room temperature (20° C.) or higher. When using an organosilicon polymer compound with a softening point of 20℃ or less, remove low volatile components by distillation (normal pressure distillation, vacuum distillation),
It is advantageous for spinning and infusibility to set the softening temperature of the organosilicon polymer compound to 20° C. or higher. The organosilicon polymer compound may be, for example, benzene, toluene, xylene, ethylbenzene, styrene, cumene, pentane, hexane, octane,
Cyclopentadiene, cyclohexane, cyclohexene, methylene chloride, chloroform, carbon tetrachloride, 1,1-dichloroethane, 1,2-dichloroethane, methylchloroform, 1,1,2
- trichloroethane, hexachloroethane, chlorobenzene, dichlorobenzene, ethyl ether, dioxane, tetrahydrofuran, methyl acetate, ethyl acetate, acetonitrile,
A spinning stock solution is prepared by dissolving carbon disulfide and other organosilicon polymer compounds in a solvent, and after removing macrogels, impurities, and other harmful substances during spinning, the spinning stock solution is usually used. The fibers are spun using a dry spinning method using a synthetic fiber spinning device, and by increasing the draft, the desired thin fibers can be obtained. At this time, the atmosphere in the spinning tube of the spinning device is set to a mixed atmosphere of a saturated vapor atmosphere of at least one of the above solvents and at least one gas selected from air and an inert gas. or air, inert gas, hot air, hot inert gas,
The use of a steam atmosphere is advantageous in that the solidification of the spun fibers in the spinning tube can be controlled. In addition to the method of preparing a spinning stock solution using the above-mentioned solvent, a spinning stock solution is prepared by heating and melting the organosilicon polymer compound, and then macrogel,
It is also possible to remove substances such as impurities that are harmful during spinning, and then spin them using the spinning apparatus. The temperature of the spinning dope during spinning varies depending on the softening temperature of the organic silicon polymer compound used as the raw material.
A temperature range of 20-400°C is advantageous. In the spinning device, a spinning tube is attached as necessary, and the atmosphere inside the spinning tube is changed to air, inert gas, hot air,
Fibers with a narrow diameter can be obtained by increasing the draft in an atmosphere of one or more selected from thermal inert gas and steam. The spinning speed in the melt spinning varies depending on the average molecular weight, molecular weight distribution, and polymer molecular structure of the organosilicon polymer compound that is the raw material, but is 50 to 5000.
Good results are obtained in the m/min range. Next, the spun yarn is made infusible by irradiation. The irradiation can be performed with at least one selected from gamma rays, neutral rays, alpha rays, beta rays, electron beams, X-rays, and light. Of these, gamma rays, electron beams, X-rays, and light are practically used. γ
When irradiating with radiation, the amount of gamma rays is 1×10 ³ to 1×10 ¹¹
It is appropriate to be within the range of X-rays. If the dose is less than 1×10 ³ Roentgen, sufficient infusibility will not be achieved and the thread will stick in the subsequent firing stage. If the dose is higher than 1×10 ¹¹ Roentgen, the infusibility treatment can be carried out in a very short time, but this is not practical because the γ-rays are too strong. γ
It is best to irradiate the material for a period of 1 to 100 hours; if it is less than 1 hour, infusibility will not be achieved sufficiently.
If it exceeds 100 hours, it becomes impractical. When irradiating with an electron beam, the acceleration voltage of the electron beam is 0.01 to 1×
A range of 10 ^{to 3} kilovolts is good. Acceleration voltage is 0.01
If it is lower than kilovolts, the energy of the electron beam is too low to achieve sufficient infusibility, and if it is higher than 1×10 ³ kilovolts, the energy of the electron beam is too strong to be practical. The practical time for electron beam irradiation is one hour or less. When irradiating X-rays, the output of X-rays should be within the range of 0.1 to 1 x 10 ³ kilovolts; if the output is lower than 0.1 kilovolts, infusibility will not occur, and if the output is higher than 1 x 10 ³ kilovolts, it is not practical. Not on target. The time of X-ray irradiation is the same as that of γ-ray irradiation1
~100 hours. When irradiating light (ultraviolet light), the energy of the light should preferably be within the range of 10 to 1 x 10 ⁷ watts; if it is less than 1 x 10 watts, infusibility will not be achieved, and if it is more than 1 x 10 ⁷ watts, it will not be infusible. Not practical. The time for irradiating light is the same as for gamma rays. This irradiation is performed under at least one atmosphere selected from oxidizing atmosphere, vacuum, inert gas, hydrogen, CO, CO ₂ , ammonia, hydrocarbon gas, and organosilicon compound gas. The reaction mechanism of infusibility due to irradiation is thought to be as follows. i.e. vacuum, inert gas, hydrogen,
In CO, hydrocarbon gas, and organosilicon compound gas, the bonds of the organosilicon polymer compounds that make up the spun yarn are broken by irradiation, and free radicals are generated, and these radicals react with each other and attack the bonds by the radicals. A new bond is formed. Due to the formation of this bond, the organosilicon polymer compound develops cross-bonds and does not melt even when heated. Also in oxidizing atmospheres (air, ozone, _CO2
and a mixed gas of these gases) or in an ammonia atmosphere, the cross bonds are generated by irradiation, and the free radicals generated by cutting the bonds of the organosilicon polymer compound react with oxygen or nitrogen, Cross-links due to the oxygen or nitrogen also occur. The generation of these two crosslinks makes the spun yarn infusible. In the case of infusibility caused by the irradiation, heating is not necessarily necessary, but it is advantageous to irradiate while heating because the formation of the cross-links is promoted. The heating temperature is particularly preferably within the range of 20 to 250°C. Further, it can also be partially rendered infusible by irradiation and then heated in an oxidizing atmosphere. In this case, the heating time in an oxidizing atmosphere can be shortened compared to the case where infusibility is achieved without irradiation at all, which may be advantageous. When tension is applied during the infusibility, it is possible to prevent the spun yarn from becoming wavy during the infusibility. As mentioned above, the applied tension only needs to be small enough to prevent the spun yarn from shrinking and forming a wavy shape, but in order to practically apply tension to the spun yarn and heat it at a low temperature, Good results can be obtained by applying a tension in the range of 0.001 to 5 Kg/mm ² , and even if a tension of 0.001 Kg/mm ² or less is applied, it is possible to apply tension that does not cause the spinning yarn to slack. First, if a tension of 5 kg/mm ² or more is applied, the tension is too large and the spun yarn may break, so the tension is preferably in the range of 0.001 to 5 kg/mm ² . Next, the infusible spun yarn is placed in a vacuum or in an atmosphere of one or more gases selected from inert gas, CO gas, hydrogen gas, hydrocarbon gas, and organosilicon compound gas. , preheat in the temperature range of 350-1000℃ while applying tension. During this preheating, the organosilicon polymer compound forming the spun yarn releases easily volatile components through a thermal polycondensation reaction and a thermal decomposition reaction. High-temperature firing is performed on the pre-fired spun yarn in a temperature range of 1000 to 2000°C in a vacuum or at least one atmosphere selected from inert gas, CO gas, and hydrogen gas, and the silicon carbide fiber is heated to a high temperature. can be obtained with high purity. As shown in Figure 2, the volatilization of easily volatile components is
The largest in the temperature range of 500-700℃. The spun yarn therefore shrinks and bends, but tension can be applied during preheating to prevent this bending. At this time, the tension may be large enough to at least prevent the spun yarn from forming a wavy shape even if it shrinks during the preheating, but practically it is 0.001 to 20 kg. Good results can be obtained by applying a tension in the range of 0.001Kg/mm ² to the spun yarn, and even if a tension of 0.001Kg/mm ² or less is applied to the spun yarn, it is not possible to apply tension that will not cause the spun yarn to sag. ,20Kg/
If a tension of mm ² or more is applied, the tension is too large and the spun yarn may break, so the tension applied to the spun yarn during preheating is preferably in the range of 0.001 to 20 Kg/mm ² . After preheating under the action of such tension,
When fired at high temperature in a vacuum or in at least one atmosphere selected from inert gas, CO gas, and hydrogen gas, SiC becomes ultrafine particles and a silicon carbide fiber with high strength can be obtained. Although the mechanism by which these ultrafine silicon carbide particles are produced is not clear, it is thought that SiC is produced by thermal decomposition of an organosilicon polymer compound. Although it is not necessarily necessary to apply tension in the high temperature firing, high strength silicon carbide fibers with less bending can be obtained by performing high temperature firing while applying tension in the range of 0.001 to 100 Kg/ ^mm2 . There is no effect even if a tension of 0.001Kg/mm ² or less is applied, and 100Kg/mm ²
Since there is no change in the effect even if the tension is applied above, the tension to be applied is preferably in the range of 0.001 to 100 Kg/mm ² . The preheated and high-temperature fired silicon carbide fibers often contain free carbon, and in order to remove this carbon, the fibers are preferably oxidized at a temperature in the range of 600 to 1700°C. By firing in a neutral atmosphere, the carbon can be oxidized and removed. Firing in the oxidizing atmosphere is 600℃
At temperatures below, free carbon is not oxidized, and at temperatures above 1700°C, free carbon is easily oxidized;
This is not preferable because the progress of the SiO ₂ production reaction increases. The time for the carbon to oxidize is determined by the oxidation temperature;
Varies depending on fiber processing temperature, e.g. 1200℃
When treating fibers fired at 800 DEG C. in an oxidizing atmosphere, 0.1 to 3 hours is appropriate, and generally better results are obtained by treating the fibers at a lower temperature for a relatively longer time. The silicon carbide fibers of the present invention can be made into monofilaments, yarns, rovings, cables, strands, and filaments. The strength and elastic modulus of the silicon carbide fiber of the present invention produced by firing in a vacuum at 1300°C are as shown in the table below, and silicon carbide fibers with such high tensile strength have not been known to date.

[Table] The elastic modulus of the silicon carbide fiber of the present invention exceeds that of carbon fiber, which has the highest elastic modulus among various currently known fibers, and is about 6 times that of glass fiber. The diffraction pattern of the silicon carbide fiber of the present invention, which was produced by firing in a vacuum at 1500°C, was investigated by the X-ray diffract method, as shown in Figure 2.
There are three diffraction peaks at θ≒36°, 60°, and 72°, indicating that the SiC crystal in this fiber is β-SiC crystal. Furthermore, Laue photographs of silicon carbide fibers calcined at various temperatures mentioned above, measured by the X-ray transmission Laue method, are shown in Reference Figures 1 to 3. Reference figure 1 is a Laue photograph of silicon carbide fiber fired in a vacuum at 1200℃, reference figure 2 is a Laue photograph of silicon carbide fiber fired at 1300℃.
Reference Figure 3 is a Laue photograph of silicon carbide fibers fired in a vacuum at 1500°C. The innermost diffraction ring in the above Laue photo is β
This is a diffraction ring due to the (111) plane of -SiC, and it can be seen that as the firing temperature increases, the diffraction ring becomes clearer and the β-SiC crystal grows. Furthermore, since no diffraction spots are observed in the diffraction rings, it is clear that the β-SiC crystals are extremely small particles. The average grain size of the SiC crystal can be calculated using the following formula. L=0.9×λ/β×cosθ L: Average particle size (Å) λ: X-ray wavelength (Å) β: Half width of diffraction peak (radian) θ: Black reflection angle High temperature firing according to the above formula When determining the size of SiC crystals in silicon carbide fibers fired at various temperatures, for example, the average grain size of SiC crystals in silicon carbide fibers fired in a vacuum at 1100°C is approximately 20 Å; The average grain size of SiC crystals in silicon carbide fibers fired in vacuum is approximately 30 Å, and the average grain size of SiC crystals in silicon carbide fibers fired in vacuum at 1500°C is approximately
80 Å, and the relationship between the firing temperature of silicon carbide fibers and the average grain size of SiC crystals is such that the higher the firing temperature, the larger the average grain size of SiC crystals. The SiC crystal in the silicon carbide fiber of the present invention obtained by firing in vacuum at 1500°C is
Among the photographs shown in Figures 3 to 6, which were observed using a 1000 kilovolt ultra-high voltage electron microscope, Figure 3 is a photograph of silicon carbide fiber taken at 5000x magnification, and it can be seen that the surface of the fiber is extremely smooth. Recognize. Figure 4 is a photograph of a silicon carbide fiber taken at 20,000 times magnification.As the electron beam passes through only the thin peripheral area, images of SiC crystal particles can be seen, and the average particle size distributed over the entire surface is approximately A very small number of particles of 100 to 1000 Å are scattered among the 50 Å particles. Figure 5 is a photograph taken at 20,000x magnification of the cut end surface of a silicon carbide fiber. It shows that between approximately 50 Å particles distributed over the entire surface, there are very small numbers of 100 to 1000 Å particles.
large particles are scattered. Figure 6 is a photograph taken at a magnification of 50,000 times the cut end surface of a silicon carbide fiber, and shows that particles of about 50 Å are uniformly distributed, and very few large particles of 100 to 1,000 Å are scattered. It can be seen that the carbide fibers are mainly composed of fine particles of about 50 Å. Next, the present invention will be explained with reference to examples. Example 1 A mixture of 10 kg of dodecamethylsilclohexasilane and 0.5 kg of hexamethyldisilazane was subjected to a thermal polycondensation reaction using the flow type apparatus shown in FIG. The mixture preheated to 120° C. was heated to 650° C. with a heating device 2 (pipe heater with a total length of 1.5 m) through valve 1 at a flow rate of 2/hour to produce a nitrogen-containing organosilicon polymer compound. The organosilicon compound is sent to a separation column 4, where it is separated into a gas, a low molecular weight compound, and a high molecular weight polymer. The gas is discharged outside the system through a valve 5, and the high molecular weight polymer is discharged outside the system through a valve 7. taken out. The low molecular weight compound passes through the valve 6 and is sent to the heating device 2 again as a recycled raw material. The obtained organosilicon polymer compound is heated and then heated in a vacuum.
It was heated and concentrated to 40°C to form a solid polymer compound. The softening temperature of this polymer compound was 35°C. This polymer compound is dissolved in benzene to make a spinning stock solution, and then it is passed through a nozzle with a diameter of 300 μm at room temperature.
Fibers of 15 μm were obtained by spinning at a speed of 400 m/min. Note that air with a benzene partial pressure of 0.01 was introduced into the spinning tube. The spun yarn was irradiated with ultraviolet rays for 25 hours using a 10 kilowatt ultraviolet lamp at room temperature in vacuum while applying a tension of 150 g/mm ² to make it infusible. Next, while applying a tension of 500 g/mm ² to the spinning yarn, the temperature was raised from room temperature to 1000°C over 3 hours in a nitrogen gas atmosphere containing a trace amount of oxygen, and then heated at 100°C/hour to 1300°C in vacuum. SiC by increasing temperature
It was made into fiber. The average tensile strength of this SiC fiber is 300
Kg/mm ² (average fiber diameter 10μm), and the elastic modulus is
It was 25ton/ ^mm2 . Example 2 Anhydrous decalin 5 and sodium 800 g were placed in a 10-inch three-necked flask, heated under a stream of N ₂ gas,
Melt the sodium. Dimethyldichlorosilane (2) was added dropwise thereto. After completion of the dropwise addition, the mixture was heated and refluxed for 3 hours to form a precipitate. This precipitate is filtered, first washed with methanol, and then thoroughly washed with water.
830 g of white powder polysilane was obtained. 100 g of this polysilane and BC ₃ H ₉ O ₂ were sealed in a glass tube purged with argon gas and polymerized by irradiation with 135 Roentgen gamma rays using a Co-60 45 KCi radiation source at room temperature. 83 g of an organosilicon polymer compound containing boron was obtained. The number average molecular weight of this organosilicon polymer compound was 1,400. The organosilicon polymer compound was heated and melted at 250°C to obtain a spinning stock solution. This spinning dope is processed into a diameter by a spinning device.
Melt spinning was performed from a 300 μm spinneret at a spinning speed of 250 m/min to obtain fibers with a diameter of 10 μm. Using a Co-60 45KCi radiation source in an argon atmosphere, this fiber was irradiated with γ-rays at a rate of 45 Roentgens/hour.
The mixture was heated to 50°C for 10 hours for infusibility treatment.
This infusible fiber was heated to 1300°C in vacuum (1 x 10 ^-3 mmHg) at a heating rate of 100°C/hour and held at 1300°C for 1 hour to obtain SiC fibers. The tensile strength of this fiber was 300 Kg/mm ² on average for fibers with an average diameter of 10 μm, and the elastic modulus was 27 ton/mm ² on average. Example 3 Among the polycarbosilanes produced in Example 2,
10 g of a product having an average molecular weight of 400 g and 3 g of AlC ₃ H ₉ were sealed in a glass tube after replacing with argon gas. This sample was irradiated with 180 Roentgen gamma rays using a Co-60 45KCi radiation source to obtain 11.5 g of an organosilicon polymer compound containing aluminum. The average molecular weight of this organosilicon polymer compound was 1,500. The organosilicon polymer compound was heated and melted at 280°C to obtain a spinning stock solution. The above-mentioned spinning stock solution was melt-spun using a spinning device at a spinning speed of 300 m/min through a spinneret with a diameter of 300 μm to obtain fibers with a diameter of 10 μm. This fiber was infusible by being irradiated with gamma rays at a dose rate of 45 Roentgens/hour for 16 hours using a Co-60 45KCi radiation source in air at room temperature. The infusible fibers were heated to 1250°C at a rate of 100°C/hour in an argon stream and held at 1300°C for 1 hour to obtain SiC fibers. The tensile strength of this fiber was 350 Kg/mm ² on average for fibers with an average diameter of 10 μm, and the elastic modulus was 20 ton/mm ² on average. When this fiber was heated to 1300℃ in air for 50 hours and an oxidation test was performed, the weight increase due to oxidation was due to the absence of aluminum.
Reduced to less than 50% compared to SiC fiber. Example 4 Poly(silmethylene siloxane) A compound with an average molecular weight of about 10,000 was synthesized and used as a raw material. The polymer was melted and filtered to obtain a spinning stock solution, which was melt-spun using a spinneret of 300 μm, a spinning temperature of 150° C., and a spinning speed of 500 m/min to obtain fibers with a diameter of 15 μm. The spun yarn was irradiated with an electron beam at an acceleration voltage of 10 kilovolts for 1 minute at room temperature in a vacuum while applying a tension of 100 g/mm ² to make it infusible.
While applying a tension of g/mm ² , the temperature was raised from room temperature to 800°C over 3 hours in a vacuum to preheat.
Furthermore, the temperature was raised to 1400°C at a heating rate of 200°C/hour and fired at a high temperature to obtain silicon carbide fibers. The strength of this 1400℃ treated fiber is 390Kg/ ^mm2 , and since there is no bend in this fiber,
The uniformity of its strength properties is very good, with an average diameter of
With 15 μm fibers, the average tensile strength was 350 Kg/mm ² and the average elastic modulus was 23 ton/mm ² . Example 5 Poly(silarylene siloxane) A compound with an average molecular weight of 7000 was synthesized and used as a raw material. The above-mentioned polymer compound is melted and filtered to obtain a spinning stock solution, which is melt-spun to a diameter of 10 μm at a spinning temperature of 203° C., a spinneret diameter of 250 μm, and a spinning speed of 1000 m/min.
m fibers. A tension of 200 g/mm ² was applied to the spun yarn, and it was irradiated in air using a Co-60 45KCi radiation source while heating to 70° C. until it became 1×10 ⁸ roentgen. Then 400 min in nitrogen gas
Preheat by raising the temperature from room temperature to 800°C over 3 hours while applying a tension of g/mm ² , and then raise the temperature to 1700°C at a rate of 200°C/hour in argon gas for high-temperature firing. and made into silicon carbide fiber. In the silicon carbide fiber, 1000
The tensile strength of the °C treated fiber is 280Kg/mm ² and the elastic modulus is
10ton/ ^mm2 , and the tensile strength of the fiber treated at 1300℃ is
380Kg/mm ² , the elastic modulus is 22ton/mm ² , and the tensile strength of the fiber treated at 1700℃ is 65Kg/mm ² , the elastic modulus is 18ton/mm 2
It was warm in ^mm2 . Example 6 Polysilmethylene A compound with an average molecular weight of about 4000 was synthesized. The softening temperature of the polymer is 40℃ or less, and it is
Aged at 280℃ for 2 hours, then filtered to obtain a spinning stock solution.The spinning temperature was 180℃ and the diameter of the spinneret was 200μ.
m, and was spun at a spinning speed of 150 m/min to obtain fibers with a diameter of 10 μm. The spun yarn was heated to 70°C in air while applying a tension of 250g/mm ² for 10
The fibers were irradiated with kilovolt X-rays for 20 hours to make them infusible, and then the fibers were preheated by slowly passing through a ¹ m long furnace at a temperature of 800°C in the center while applying a tension of 500 g/mm 2 in nitrogen gas. , while applying a tension of 5Kg/ ^mm2 , the center was placed in an argon gas atmosphere.
The fibers were passed slowly through a 2 m long furnace at 1300°C and fired at high temperatures to produce silicon carbide fibers. The tensile strength of the silicon carbide fiber treated at 1300° C. was 340 Kg/mm ² and the elastic modulus was 28 ton/mm ² . Example 7 Polysiltrimethylene The average molecular weight of approximately 3000 was synthesized, and after sufficient filtration, it was melt-spun at a spinning temperature of 140°C, a spinning speed of 800 m/min, and a spinneret diameter of 240 μm to a diameter of 10 μm.
fibers were obtained. While applying a tension of 150 g/mm ² to the spinning yarn, it was irradiated using a Co-60 45-KCi radiation source until it reached 3 x 10 ⁷ roentgens, and then heated in air to 100°C for 1 hour. Then, while applying a tension of 300 g/mm ² , the temperature was raised from room temperature to 800°C over 3 hours in vacuum to preheat, and then heated to 1600°C in argon gas.
Silicon carbide fibers were obtained by increasing the temperature at a rate of 200°C/hour. In the fiber, 1000
The tensile strength of the °C treated fiber is 310Kg/mm ² and the elastic modulus is
13ton/ ^mm2 , and the tensile strength of the fiber treated at 1300℃ is
The weight was 380Kg/mm ² and the elastic modulus was 25ton/mm ² . As described above, the silicon carbide fiber obtained by the method of the present invention can easily have a strength comparable to that of piano wire, which has the highest tensile strength among steel materials, at 300 to 400 kg/ ^mm2 , and has a specific gravity of about 3.0. Yes, acid resistant,
It has excellent oxidation resistance and heat resistance, has better leakage with metals and alloys than carbon fiber, and has poor reactivity with metals and alloys, so it is suitable for fiber-reinforced metals, plastic and rubber fiber materials, and electric heating. Fibers, fireproof fabrics, acid-resistant diaphragms, nuclear reactor materials, aircraft structural materials, bridges, building materials, fusion reactor materials, rocket materials, luminous materials, abrasive cloth, wire ropes,
It is extremely useful for marine development materials, golf shaft materials, ski stock materials, tennis racket materials, fishing rods, shoe sole materials, etc.

[Brief explanation of the drawing]

Figure 1 shows a flow-through synthesis device, Figure 2 shows
X-ray diffraction diagram by the diffract method of fibers fired at a high temperature of 1500℃, Figure 3 is a transmission electron micrograph at 5000x magnification, Figure 4 is a transmission electron micrograph at 20000x magnification, and Figure 5 is a transmission electron micrograph at 20000x magnification. Transmission electron micrograph, Figure 6 is a transmission electron micrograph at a magnification of 50,000 times. 1, 3, 4, 6, 7, 8... Valve, 2... Reaction tower, 5... Fractionation tower.

Claims (1)

[Claims] 1 (1) Organosilicon compound containing only Si-C bonds (2) Organosilicon compound containing Si-H bonds in addition to Si-C bonds (3) Organosilicon compound containing Si-Hal bonds Compound (4) Organosilicon compound with Si-OR (R=alkyl, aryl) bond (5) Organosilicon compound with Si-OH bond (6) Organosilicon compound containing Si-Si bond (7) Si-O -Organosilicon compounds containing Si bonds (8) Organosilicon compound esters (9) Organosilicon compound peroxides (10) Organosilicon compounds containing Si-N bonds Organosilicon compounds of the above (1) to (10) Organosilicon compounds consisting of one or more of these are subjected to a polycondensation reaction by at least one of the addition of a polycondensation catalyst, irradiation, and heating to form an organosilicon compound containing silicon and carbon as main skeleton components. a first step of producing a molecular compound, a second step of preparing a spinning dope from the organosilicon polymer compound and spinning it, and the second step of producing a spinning solution.
The spun yarn from the process is heated _under tension or A third step of making the yarn infusible by irradiation with light or radiation under the action of no tension; a fourth step of preheating at 350°C to 1000°C under the action of tension or no tension in an atmosphere of one or more gases selected from compound gases; and a fourth step of preheating the preheated spun yarn in a vacuum. or a fifth step of producing SiC fibers by firing at a high temperature of 1000°C to 2000°C under tension or no tension in one or more atmospheres selected from inert gas, CO gas, and hydrogen gas; 1. A method for producing silicon carbide fiber mainly made of SiC, characterized by comprising: 2 (1) Organosilicon compounds containing only Si-C bonds (2) Organosilicon compounds containing Si-H bonds in addition to Si-C bonds (3) Organosilicon compounds containing Si-Hal bonds (4) Si- Organosilicon compounds with OR (R=alkyl, aryl) bonds (5) Organosilicon compounds with Si-OH bonds (6) Organosilicon compounds with Si-Si bonds (7) Organic compounds with Si-O-Si bonds Silicon compound (8) Organosilicon compound esters (9) Organosilicon compound peroxide (10) Organosilicon compound having a Si-N bond Any one or two of the above organosilicon compounds (1) to (10) Produced by a polycondensation reaction using at least one of the addition of a polycondensation catalyst, irradiation, and heating using a mixture of an organosilicon compound consisting of more than one species and an organometallic compound containing a group metal as a starting material. A first step of producing an organosilicon polymer compound whose main skeleton components are silicon and carbon, the structure of which contains at least one element selected from a heterogeneous element other than silicon, carbon, hydrogen, and oxygen; A second step for preparing and spinning a spinning dope of the organosilicon polymer compound.
step, and the spun yarn is placed in at least one atmosphere selected from an oxidizing atmosphere, vacuum, inert gas, hydrogen, CO, CO ₂ , ammonia, hydrocarbon gas, and organosilicon compound gas, A third step of infusibilizing by irradiation with light or radiation under the action of tension or no tension, and infusible spun yarn in vacuum or with inert gas, CO gas, hydrogen gas, hydrocarbon gas, 350°C to 1000°C under tension or no tension in an atmosphere of one or more gases selected from organosilicon compound gases
a fourth step of preheating the preheated spun yarn in a vacuum or in an atmosphere of one or more selected from inert gas, CO gas, and hydrogen gas under tension or no tension; 1000℃～2000℃
A method for producing silicon carbide fibers mainly made of SiC, the method comprising: a fifth step of producing SiC fibers by firing at a high temperature. 3 Preheating in the fourth step is performed in vacuum with a small amount of one or more selected from air, oxygen, ozone, and steam, inert gas, CO gas, hydrogen gas, hydrocarbon gas, organic The silicon mainly composed of SiC according to claim 1, characterized in that the silicon compound is produced under tension or no tension in a mixed atmosphere consisting of one or more selected from silicon compound gas and ammonia gas. Method for producing carbide fibers. 4. A method for producing silicon carbide fibers mainly made of SiC as claimed in claim 1 or 3, characterized in that part of the firing in the fifth step is carried out in an oxidizing atmosphere to reduce the amount of free carbon. 5 Preheating in the fourth step is performed in a vacuum with a small amount of one or more selected from air, oxygen, ozone, and steam, inert gas, CO gas, hydrogen gas, hydrocarbon gas, organic The silicon mainly composed of SiC according to claim 2, characterized in that the silicon compound is produced under tension or no tension in a mixed atmosphere consisting of one or more selected from silicon compound gas and ammonia gas. Method for producing carbide fibers. 6. The method for producing silicon carbide fibers mainly composed of SiC as claimed in claim 2 or 4, characterized in that part of the firing in the fifth step is carried out in an oxidizing atmosphere to reduce the amount of free carbon.