SiC fiber based on polycarbosilane raw material and production process thereof

Abstract

The invention discloses a SiC fiber based on a polycarbosilane raw material and a production process of the SiC fiber, and belongs to the technical field of silicon carbide fibers.The SiC fiber comprises 80-95 parts of linear polycarbosilane and 5-20 parts of hyperbranched polycarbosilane, and the hyperbranched polycarbosilane is obtained through polymerization of AB3 type monomers.The invention provides the SiC fiber based on the polycarbosilane raw material and the production process of the SiC fiber based on the polycarbosilane raw material and the production process of the SiC fiber based on the polycarbosilane raw material. The SiC fiber is prepared by preparing hyperbranched polycarbosilane obtained by polymerizing AB3 type monomers and mixing the hyperbranched polycarbosilane with linear polycarbosilane, and the hyperbranched polycarbosilane can be used as a part of solvent and cross-linking agent of the linear polycarbosilane, so that the step of oxidation curing is avoided, the oxygen content and carbon enrichment phenomenon of SiC are reduced, and the strength and heat resistance of SiC are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicon carbide fibers, and particularly relates to a SiC fiber based on a polycarbosilane raw material and a production process thereof. Background Art

[0002] Among high-temperature structural ceramics, silicon carbide (SiC) ceramics are extremely important special ceramics. SiC ceramics, also known as carborundum, are covalent inorganic substances. Their composition forms a regular tetrahedral crystal structure similar to diamond with equal amounts of silicon and carbon (in actual applications, SiC ceramics are rich in carbon or contain elements such as oxygen). The unique structure endows SiC ceramics with excellent properties, such as high-temperature stability, oxidation resistance, and high hardness. They have broad application prospects in the fields of aerospace, military, nuclear energy engineering, automotive industry, mechanical chemical industry, energy, electronic information, etc., and have become an irreplaceable high-temperature structural ceramic material. However, the main bonds in ceramics are ionic bonds and covalent bonds, and dislocations are difficult to slip, making it difficult to generate elastic deformation and plastic deformation. Usually, brittle fracture occurs. Therefore, it is often necessary to add a second phase such as particles, whiskers, and fibers to strengthen and toughen the ceramics. During the stress process of ceramic materials, the toughness of ceramic materials is significantly improved through methods such as whisker or fiber pull-out, bridging, and crack deflection. Among them, ceramic matrix composites prepared with continuous ceramic fibers as the reinforcement have the most obvious toughening effect.

[0003] There are mainly four methods for preparing continuous SiC fibers, namely: chemical vapor deposition method, chemical vapor reaction method, ultra-fine powder high-temperature sintering method, and precursor conversion method. Among them, the precursor conversion method uses the organic precursor polycarbosilane as the raw material, which is melt-spun, cross-linked and cured, and pyrolyzed to complete the transformation from an organic compound to a ceramic material, generating SiC fibers. The precursor conversion method has low preparation cost, easily available organic polymer precursors, and the composition can be designed according to the actual use of the target fiber, providing convenience for large-scale industrial production. It is the main method for industrial preparation of fine-diameter continuous SiC fibers and also the only preparation route for the successful application of SiC fibers in the hot-end components of aeroengines. However, polycarbosilane is a solid at room temperature and requires the use of a large amount of good solvents such as xylene, tetrahydrofuran, and n-hexane during the impregnation process; and it will cause carbon-rich phenomena, affecting the temperature resistance performance; in addition, the molecular weight of polycarbosilane is quite low, and the spinning ability is poor. When over-stretched, the fibers are easily broken, and it is difficult to obtain continuous small-diameter fibers. Therefore, there is research on adding polyvinylsilane as a plasticizer to polycarbosilane to improve its spinning ability, but the compatibility between polyvinylsilane and polycarbosilane is poor, and phase separation is likely to occur during the solvent removal process, and a freeze-drying step is required to remove the solvent, and the process is relatively complex. Summary of the Invention

[0004] To overcome the deficiencies of the above-mentioned prior art, the present invention provides a SiC fiber based on polycarbosilane raw materials and its production process. By preparing a hyperbranched polycarbosilane obtained by polymerizing AB 3 type monomers, and mixing it with linear polycarbosilane to prepare SiC fibers, wherein the hyperbranched polycarbosilane can serve as a partial solvent and cross-linking agent for the linear polycarbosilane, avoiding the oxidation curing step, reducing the oxygen content and carbon-rich phenomenon of SiC, and improving the strength and heat resistance of SiC.

[0005] The technical solutions to achieve the object of the present invention are as follows: A SiC fiber based on polycarbosilane raw materials, by weight, includes 80-95 parts of linear polycarbosilane and 5-20 parts of hyperbranched polycarbosilane. The hyperbranched polycarbosilane is obtained by polymerizing AB 3 type monomers, and the structural formula of the AB 3 type monomers is shown in Formula 1 or Formula 2: Formula 1, Formula 2.

[0006] The preparation method of the AB 3 type monomers is as follows: Under anhydrous and anaerobic conditions, 4-bromochlorobenzene or m-chlorobromobenzene, magnesium, and tetrahydrofuran are mixed in a container, heated to 50-80 °C and stirred, triethylvinylchlorosilane is added dropwise and reacted for 8-16 h, then the reaction temperature is raised to 100-110 °C, dimethylchlorosilane is added dropwise, and stirring reaction is continued for 8-16 hours. Water is added to quench the reaction, and the organic solution layer is collected by ether extraction, washed, dried, filtered, and the filtrate is concentrated under reduced pressure to obtain AB 3 type monomers.

[0007] Preferably, the molar ratio of 4-bromochlorobenzene or m-chlorobromobenzene, triethylvinylchlorosilane, and dimethylchlorosilane is (0.95-1.05):(0.95-1.05):(0.95-1.05).

[0008] Preferably, the molar amount of magnesium added is 2.0-2.5 times the molar amount of 4-bromochlorobenzene or m-chlorobromobenzene added.

[0009] Preferably, the preparation method of the hyperbranched polycarbosilane is: dissolving the monomers in toluene, then adding a Kästner catalyst, stirring and reacting at room temperature for 12-24 h, purifying and drying to obtain hyperbranched polycarbosilane.

[0010] The present invention also protects a production process of a SiC fiber based on polycarbosilane raw materials, including the following steps: S1. Dissolve the linear polycarbosilane and hyperbranched polycarbosilane in hexane to obtain a clear solution, and then vacuum dry at 60 °C to obtain a precursor mixture; S2. Spin the mixture through a melt spinning machine at a spinning temperature of 205 - 285 °C to obtain precursor fibers; S3. Cut the precursor fibers into staple fibers, and under nitrogen protection, heat them to 150 - 180 °C at a rate of 5 - 10 °C / h for cross - linking and curing, and keep the temperature for 1 - 2 h to obtain cured fibers; S4. Heat the cured fibers to 1000 - 1400 °C at a rate of 2 - 10 °C / min in a hydrogen atmosphere and keep the temperature for 5 - 90 min to obtain silicon carbide fibers.

[0011] In a specific embodiment, electron beam can also be used to cure the precursor fibers; it includes the following steps: S1. Dissolve linear polycarbosilane and hyperbranched polycarbosilane in hexane, and the addition amount of hexane is 300 - 500 wt% of the linear polycarbosilane to obtain a clear solution, and then vacuum - dry it at 60 °C to obtain a precursor mixture; S2. Spin the mixture through a melt spinning machine at a spinning temperature of 205 - 235 °C to obtain precursor fibers; S3. Irradiate the precursor fibers with an electron beam of a dose of 10 - 20 MGy for 3 - 5 s in an inert gas atmosphere for cross - linking and curing to obtain cured fibers; S4. Heat the cured fibers to 1000 - 1400 °C at a rate of 2 - 10 °C / min in a hydrogen atmosphere and keep the temperature for 5 - 90 min to obtain silicon carbide fibers.

[0012] In another specific embodiment, ultraviolet light can also be used to cure the precursor fibers, including the following steps: S1. Dissolve linear polycarbosilane and hyperbranched polycarbosilane in hexane to obtain a clear solution, and then vacuum - dry it at 60 °C to obtain a precursor mixture; S2. Spin the mixture through a melt spinning machine at a spinning temperature of 205 - 235 °C to obtain precursor fibers; S3. Irradiate the precursor fibers with ultraviolet light for 10 - 30 min in an inert gas atmosphere for cross - linking and curing to obtain cured fibers; S4. Heat the cured fibers to 1000 - 1400 °C at a rate of 2 - 10 °C / min in a hydrogen atmosphere and keep the temperature for 5 - 90 min to obtain silicon carbide fibers.

[0013] The present invention also protects the application of SiC fibers based on polycarbosilane raw materials in SiC ceramic matrix materials.

[0014] Beneficial effects The present invention has the following beneficial effects: (1) Use an AB 3Compared with the dual monomer system, the AB 3 The type monomer can generate a hyperbranched structure through one-step self-condensation. There is no need to precisely control the ratio of the two monomers, and there is no small molecular monomer residue, which reduces the purification steps. In addition, the molecular weight distribution is narrower, the degree of branching is higher, a compact spherical structure is formed, molecular chain entanglement is reduced, and low viscosity, high fluidity and high solubility are imparted.

[0015] (2) Hyperbranched polycarbosilane contains vinyl groups, and the cross-linking reaction is mainly a hydrosilylation reaction, which reduces the cross-linking temperature. At the same time, the hydrosilylation reaction does not produce small molecular gases. The introduction of vinyl groups can also cross-link with the residual Si-H in linear polycarbosilane to increase the cross-linking density, avoid rearrangement and escape of small molecules during high temperature and cause weight loss, and improve the ceramic yield.

[0016] (3) There is no need for oxidative cross-linking, and hydrogen is used to react excess carbon during the sintering stage. The oxygen content of the silicon carbide fiber product is low, the Si / C of the ceramic is more reasonable, and the product exhibits better high temperature resistance and antioxidant properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 For the present invention AB 3 The synthetic route and structural diagram of type monomer 1 and hyperbranched polycarbosilane; Figure 2 For the present invention AB 3 H NMR spectrum of type monomer 1; Figure 3 It is the infrared spectrum of the hyperbranched polycarbosilane 1 of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] In the examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0020] The raw materials and equipment used in the embodiments and comparative examples are described as follows: Trivinylchlorosilane: CAS: 1871-21-2, purity 95%, purchased from Beijing Bailingwei Technology Co., Ltd.; Dimethylmonochlorosilane: CAS: 1066-35-9, purity 98%, purchased from Sigma-Aldrich; 4-Bromochlorobenzene: CAS: 106-39-8, purity 99%, purchased from Shanghai Macklin Biochemical Co., Ltd.; m-Bromochlorobenzene: CAS: 108-37-2, purity 99%, purchased from Sigma-Aldrich; Karstedt's catalyst: CAS: 81032-58-8, purity 3000 ppm, purchased from Shanghai Macklin Biochemical Co., Ltd.; Hexane: n-Hexane, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Linear polycarbosilane: CAS: 62306-27-8, molecular weight 1400, purchased from Henan Weiti Xi Chemical Technology Co., Ltd., and the structural formula is as follows:

[0021] AB 3 Type AB monomer 1: The preparation method is as follows: Weigh 10 g of dry and anhydrous magnesium chips and place them in a three-necked flask. Continuously purge with an inert gas, add 20 ml of tetrahydrofuran, purge with an inert gas for 30 min, add 0.2 mol of 4-bromochlorobenzene, carry out reflux condensation at 65 °C, stir at a rate of 200 rpm, dropwise add 0.2 mol of trivinylchlorosilane, react for 16 h, raise the reaction temperature to 100 °C, dropwise add 0.2 mol of dimethylchlorosilane, continue stirring and reacting for 16 hours, add 150 ml of distilled water to quench the reaction, add 60 ml of ether for extraction three times, collect the organic solution layer, wash again with 100 ml of distilled water and 100 ml of saturated NaCl solution, dry over anhydrous sodium sulfate and then filter, and concentrate the filtrate under reduced pressure to obtain the AB 3 type monomer; the yield is 80%, and it is kept for use at 0 °C. The reaction route is as Figure 1 shown, and it is tested by an Avance 500 Bruker nuclear magnetic resonance spectrometer, with CDCl 3 as the solvent, 1 The 1H-NMR spectrum is as Figure 2 shown.

[0022] AB 3 Type AB monomer 2: The preparation method is different from that of AB 3 type monomer 1 in that 4-bromochlorobenzene is replaced by m-bromochlorobenzene, and the yield is 76%; Hyperbranched polycarbosilane 1: Weigh 0.2 mol of monomer 1 and 100 ml of toluene into a flask, slowly add a toluene solution of the Kaster catalyst dropwise, stir at room temperature for 24 h, add 100 ml of chloroform and 10 g of activated carbon, stir or shake vigorously, let stand for 6 hours, filter to collect the organic phase, concentrate under reduced pressure, add the residue to 500 ml of methanol to form a white precipitate, filter to collect the precipitate, and dry it in vacuo at 60 °C for 12 hours to obtain the hyperbranched polycarbosilane precursor 1.

[0023] Testing was carried out using a Nicolet 5700 infrared spectrometer produced by Thermo electron corporation, with a wave number range of 500 - 4000 cm -1 , using a KBr tablet, and the infrared spectrum is as Figure 3 shown. Among them, the antisymmetric stretching vibration peaks corresponding to C=C are at 3069 cm -1 and 1625 cm -1 . The characteristic peaks corresponding to CH -1 are at 2873 - 2952 cm 2 . The characteristic peaks corresponding to Si-H are at 2124 cm -1 and 928 cm -1 . The symmetric deformation vibration corresponding to Si-CH -1 is at 1248 cm 3 . The deformation vibration of C-H in Si-CH -1 -Si is at 1023 cm 2 . The stretching vibration corresponding to Si-C is at 746 cm -1 .

[0024] Hyperbranched polycarbosilane 2: The preparation method is different from that of hyperbranched polycarbosilane 1 in that monomer 1 is replaced by monomer 2; Example 1 A SiC fiber based on a polycarbosilane raw material, comprising 80 parts of linear polycarbosilane and 20 parts of hyperbranched polycarbosilane, and the preparation method is as follows: S1. Dissolve the linear polycarbosilane and hyperbranched polycarbosilane 1 in hexane, where the addition amount of hexane is 300 wt% of the mass of the linear polycarbosilane, to obtain a clear light yellow solution, and dry it in vacuo at 60 °C to obtain a white powdery precursor mixture; S2. Load the white powder obtained in step S1 into the storage tank of a melt spinning machine, then heat it to the melt spinning temperature under the protection of high-purity nitrogen, extrude the polymer melt through a single-hole spinneret, the orifice diameter is 0.3 mm, the spinning temperature is 220 °C, and the winding speed is fixed at 400 m / min to obtain the precursor fiber; S3. Under nitrogen protection, heat the precursor fiber in a tubular furnace at a heating rate of 10 °C / h to 170 °C and hold for 1 h to obtain a cured fiber; S4. Heat the cured fiber in high-purity hydrogen at a heating rate of 5 °C / min to 1250 °C and hold for 5 min to obtain a shiny black SiC fiber.

[0025] Example 2 Compared with Example 1, the difference is that hyperbranched polycarbosilane 1 is replaced by hyperbranched polycarbosilane 2; Example 3 Compared with Example 1, the difference is that it includes 95 parts of linear polycarbosilane and 5 parts of hyperbranched polycarbosilane, and the addition amount of hexane is 500 wt% of the linear polycarbosilane; Example 4 Compared with Example 1, the difference is that the thermal crosslinking in step S3 is replaced by electron beam irradiation crosslinking; the dose is 15 MGy and the curing time is 5 s; Example 5 Compared with Example 1, the difference is that the thermal crosslinking in step S3 is replaced by ultraviolet light irradiation crosslinking; the wavelength is 365 nm and the irradiation time is 30 min; Comparative Example 1 Compared with Example 1, the difference is that it includes 70 parts of linear polycarbosilane and 30 parts of hyperbranched polycarbosilane, and the addition amount of hexane is 200 wt% of the linear polycarbosilane; Comparative Example 2 Compared with Example 1, the difference is that no hyperbranched polycarbosilane is added, the addition amount of hexane is 1000 wt% of the linear polycarbosilane, and the spinning temperature is 285 °C.

[0026] The following are the test methods for the performance parameters involved in the present invention: (1) Molecular weight M w : Analyze the molecular weight and molecular weight distribution of hyperbranched polycarbosilane using gel permeation chromatography (GPC) (Agilent 1100 system, Agilent).

[0027] (2) Softening point: Test the softening point of the precursor mixture by the capillary method using a melting point instrument (MP30, Mettler Toledo). The test method refers to GB / T 21781 "Test Method for Melting Point and Melting Range of Chemicals - Capillary Method". Grind the sample into fine powder and pass through a 400-mesh filter screen. The filling height of the capillary is 3 mm and the heating rate is 1 °C / min.

[0028] (3) Ceramic yield: The ceramic yield of the precursor mixture was determined using a thermogravimetric analyzer (TGA2, Mettler Toledo). 5 mg of the sample was ground in a mortar to a mesh size between 60 and 80. The entire test system was evacuated and replaced with an inert gas using a vacuum pump. The sample was heated from 30 °C to 900 °C at a heating rate of 10 °C / min.

[0029] (4) Average diameter: The cross-sectional diameters of 50 sites of SiC fibers were measured using a scanning electron microscope (XL30, Philips-FEI). (5) Tensile strength: The tensile strength of a single SiC fiber was measured using a tensile testing machine (YG(B)003A, Wenzhou Darong Textile Instrument Co., Ltd.). The gauge length was 25 mm and the crosshead speed was 1 mm / min. The average value was calculated from testing 20 fibers.

[0030] (6) Heat resistance: The SiC fibers were heat-treated at 1200 °C, 1300 °C, and 1500 °C for 30 min respectively. The tensile strength after heat treatment was tested and compared with the tensile strength before testing to calculate the tensile strength retention rate.

[0031] Table 1 Molecular weight test of hyperbranched polycarbosilane

[0032] Table 2 Performance test of examples and comparative examples

[0033] It can be seen from the results of the examples and comparative examples that after adding hyperbranched polycarbosilane and linear polycarbosilane in blend, the softening point of polycarbosilane is reduced, enabling it to be spun at a lower melt spinning temperature, preventing degradation reactions such as chain breakage or excessive crosslinking of polycarbosilane at high temperatures, facilitating the maintenance of a stable molecular structure, and avoiding a sharp drop in molecular weight or the generation of impurities. At the same time, due to the presence of liquid hyperbranched polycarbosilane, only a small amount of solvent is needed to dissolve solid polycarbosilane, and a large number of vinyl groups are introduced by hyperbranched polycarbosilane, which act as both a partial solvent and a crosslinking agent, reducing the introduction of oxygen into the system. Using hydrogen to react with excessive carbon during the sintering stage makes the Si / C of the ceramic more reasonable, improves its density, thereby greatly increasing the ceramic yield and tensile strength, and also improving the heat resistance.

[0034] It can be seen from Examples 1, 4, and 5 that the mechanical properties and heat resistance of SiC fibers obtained by thermal crosslinking, electron beam irradiation crosslinking, and ultraviolet light irradiation crosslinking curing are all good, and electron beam irradiation is more advantageous due to its short time and high performance.

[0035] It can be seen from Comparative Example 1 and Comparative Example 2 that when the amount of hyperbranched polycarbosilane added is excessive, the softening point temperature is too low, resulting in too low melt viscosity, the melt is too thin, and it is difficult to form fibers, and wire breakage is likely to occur. When no hyperbranched polycarbosilane is added, the obtained fiber has a larger diameter and is more brittle, which is not conducive to subsequent weaving.

[0036] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A SiC fiber based on polycarbosilane raw material, characterized in that: In parts by weight, it comprises 80-95 parts of linear polycarbosilane and 5-20 parts of hyperbranched polycarbosilane, wherein the hyperbranched polycarbosilane is obtained by polymerizing AB3 type monomers, and the structural formula of the AB3 type monomers is shown in Formula 1 or Formula 2: Formula 1, Formula 2.

2. The SiC fiber based on polycarbosilane raw material according to claim 1, characterized in that: The preparation method of the AB3 type monomer is as follows: under anhydrous and oxygen-free conditions, 4-bromochlorobenzene or m-chlorobromobenzene, magnesium and tetrahydrofuran are mixed in a container, the temperature is raised to 50-80° C. and stirred, trivinyl chlorosilane is added dropwise to react for 8-16 hours, then the reaction temperature is raised to 100-110° C., dimethyl monochlorosilane is added dropwise, the reaction is continued to be stirred for 8-16 hours, water is added to quench the reaction, the organic solution layer is collected by ether extraction, the organic solution layer is washed, dried and filtered, and the filtrate is concentrated under reduced pressure to obtain the AB3 type monomer.

3. The SiC fiber based on polycarbosilane raw material according to claim 2, characterized in that: The molar ratio of the 4-bromochlorobenzene or m-chlorobromobenzene, trivinylchlorosilane and dimethylmonochlorosilane is (0.95-1.05): (0.95-1.05): (0.95-1.05).

4. The SiC fiber based on polycarbosilane raw material according to claim 2, characterized in that: The molar amount of magnesium added is 2.0 to 2.5 times the molar amount of 4-bromochlorobenzene or m-chlorobromobenzene added.

5. The SiC fiber based on polycarbosilane raw material according to claim 1, characterized in that: The preparation method of the hyperbranched polycarbosilane comprises: dissolving the monomer in toluene, then adding a Custer catalyst, stirring and reacting at room temperature for 12 to 24 hours, purifying and drying to obtain the hyperbranched polycarbosilane.

6. The process for producing SiC fiber based on polycarbosilane raw material according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. dissolving linear polycarbosilane and hyperbranched polycarbosilane in hexane to obtain a clear solution, and then drying under vacuum at 60° C. to obtain a precursor mixture; S2. The mixture is spun through a melt spinning machine at a spinning temperature of 205 to 235° C. to obtain a precursor fiber; S3. The precursor fiber is heated to 150-180°C at 5-10°C / h in an inert gas atmosphere for crosslinking and curing, and kept at this temperature for 1-2h to obtain a cured fiber; S4. The solidified fiber is heated to 1000-1400°C at 2-10°C / min in a hydrogen atmosphere and kept at this temperature for 5-90 minutes to obtain silicon carbide fiber.

7. The process for producing SiC fiber based on polycarbosilane raw material according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. dissolving linear polycarbosilane and hyperbranched polycarbosilane in hexane to obtain a clear solution, and then drying under vacuum at 60° C. to obtain a precursor mixture; S2. The mixture is spun through a melt spinning machine at a spinning temperature of 205 to 235° C. to obtain a precursor fiber; S3. The precursor fiber is cross-linked and cured by electron beam irradiation at a dose of 10 to 20 MGy for 3 to 5 seconds under an inert gas atmosphere to obtain a cured fiber; S4. The solidified fiber is heated to 1000-1400°C at 2-10°C / min in a hydrogen atmosphere and kept at this temperature for 5-90 minutes to obtain silicon carbide fiber.

8. The process for producing SiC fiber based on polycarbosilane raw material according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Dissolving linear polycarbosilane and hyperbranched polycarbosilane in hexane, wherein the amount of hexane added is 300 to 500 wt % of the linear polycarbosilane to obtain a clear solution, and then vacuum drying at 60° C. to obtain a precursor mixture; S2. The mixture is spun through a melt spinning machine at a spinning temperature of 205 to 235° C. to obtain a precursor fiber; S3. The precursor fiber is cross-linked and cured by ultraviolet irradiation for 10 to 30 minutes under an inert gas atmosphere to obtain a cured fiber; S4. The solidified fiber is heated to 1000-1400°C at 2-10°C / min in a hydrogen atmosphere and kept at this temperature for 5-90 minutes to obtain silicon carbide fiber.

9. Use of the SiC fiber based on polycarbosilane raw material as claimed in any one of claims 1 to 5 in SiC ceramic-based materials.

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