High-temperature-resistant silicon carbide ceramic fiber and preparation method thereof

Abstract

The application belongs to the technical field of fiber preparation, and relates to a high-temperature-resistant silicon carbide ceramic fiber and a preparation method thereof. The silicon carbide ceramic fiber is prepared from a boron compound-containing modified organosilicon polymer precursor through steps including spinning, electron beam irradiation non-melting, sintering and high-temperature sintering; the boron compound-containing modified organosilicon polymer is obtained by grafting a boron compound onto an organosilicon polymer through electron beam irradiation; and the boron compound is a boroxin derivative. The preparation method of the silicon carbide fiber is simple and efficient, the non-melting efficiency is significantly improved, and the prepared silicon carbide ceramic fiber has low oxygen content, good mechanical properties and high-temperature resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fiber preparation and relates to a high-temperature-resistant silicon carbide ceramic fiber and a preparation method thereof. BACKGROUND

[0002] Silicon carbide fibers have excellent high-temperature resistance, oxidation resistance, radiation resistance and corrosion resistance, and have important application value in the fields of aviation, aerospace, nuclear industry and the like. The precursor conversion method is a mainstream method for preparing continuous silicon carbide fibers with a fine diameter at present, which includes precursor synthesis, spinning, infusibilization and sintering processes. Polycarbosilane (PCS) is a main precursor for preparing silicon carbide fibers, and the PCS precursor and the silicon carbide fiber thereof have realized mass production and commercialization and are widely applied to multiple fields. However, the high-temperature resistance of the PCS-based silicon carbide fiber still needs to be improved, which is mainly due to the phase decomposition reaction of SiC x O y of the silicon carbide fiber at high temperatures and the grain growth and coarsening of the silicon carbide, thereby causing the mechanical properties of the silicon carbide fiber to sharply decrease.

[0003] The introduction of heterogeneous elements such as aluminum, boron, zirconium and titanium into the PCS precursor can significantly improve the high-temperature resistance of the silicon carbide fiber. These heterogeneous elements are helpful to promote high-temperature sintering densification, make the internal structure of the fiber more compact, reduce pores and defects, and thereby improve the stability of the fiber at high temperatures. At the same time, they can inhibit the abnormal growth of the silicon carbide grains, keep the grain size small and uniform, and avoid the decrease of the mechanical properties caused by the grain growth. Polyaluminum carbosilane (PACS) is an important precursor for preparing high-temperature-resistant silicon carbide fibers, and aluminum as a sintering aid can promote the densification of the fiber structure after the phase decomposition of SiC x O y and inhibit the abnormal growth of the silicon carbide grains, thereby improving the high-temperature resistance of the fiber. The Japanese Ubukata Company and the National University of Defense Technology of China both use PACS to prepare high-temperature-resistant silicon carbide fibers, which are named as Tyranno SA fibers and KD-SA fibers, respectively. Boron is an important sintering aid for silicon carbide ceramics, and the high-temperature sintering densification of the silicon carbide ceramics can be realized by introducing a small amount of boron. Although boron is an effective sintering aid, due to the problems of toxicity, instability and easy volatilization of most boron sources, it is still difficult to realize the uniform distribution of boron in the silicon carbide fiber at present, and thus the sintering densification effect of boron cannot be fully exerted.

[0004] Infusibility is a key step for preparing silicon carbide fibers by precursor conversion method, which makes PCS fiber transform from fusible state to infusible state, so that the fiber morphology can be maintained in subsequent high temperature sintering. The infusibility methods mainly include air oxidation method and irradiation crosslinking method. In order to avoid PCS fiber fusion, the conventional air oxidation method must be carried out at a very slow heating rate, because the viscosity of PCS fiber decreases at high temperature, which is easy to stick and fuse, and slow heating can make the fiber surface slowly oxidize to form a crosslinked structure to prevent fusion, but this leads to extremely low production efficiency. The irradiation crosslinking method must also be carried out at a lower irradiation dose rate, otherwise it will cause excessive degradation or uneven crosslinking of the fiber, also leading to low efficiency. The low efficiency of these two methods makes the production efficiency of silicon carbide fiber extremely low and the production cost extremely high, which cannot meet the application requirements of some cost-sensitive fields.

[0005] Therefore, developing an efficient preparation technology and improving the high temperature resistance of silicon carbide fibers is of great significance to promote the rapid development of silicon carbide fibers. SUMMARY

[0006] In order to solve the above problems existing in the prior art, the purpose of the present application is to provide a high-temperature-resistant silicon carbide ceramic fiber and a preparation method thereof, so as to overcome the shortcomings of the prior art.

[0007] One object of the present application is to provide a high-temperature-resistant silicon carbide ceramic fiber, which is prepared from a boron-containing compound modified organosilicon polymer as a precursor through steps including spinning, electron beam irradiation infusibility, sintering and high temperature sintering;

[0008] The boron-containing compound modified organosilicon polymer is obtained by grafting a boron-containing compound onto an organosilicon polymer through electron beam irradiation;

[0009] The boron-containing compound is a derivative of boroxin, and its molecular structure is as follows:

[0010]

[0011] In the formula, R1, R2 and R3 are each independently selected from one of phenyl and substituted phenyl. The type of the substituent group is not particularly limited, and examples of the substituent group include an alkyl substituent group (such as methyl, ethyl, propyl, isopropyl, etc.), a phenyl substituent group, a halogen substituent group, a hydroxyl substituent group, an amino substituent group, a nitro substituent group, a carboxyl substituent group, an alkoxy substituent group, etc. The substitution position of the substituent group can be one or more of ortho substitution, para substitution and meta substitution. The number of the substituent group can be 1, 2, 3, 4 or 5.

[0012] Preferably, the organosilicon polymer is a metal element doped polycarbosilane, also known as poly-metal-carbosilane (PMCS), and the metal element (M) is one or more of aluminum, zirconium, titanium and yttrium.

[0013] Preferably, the organosilicon polymer is one or more of polyaluminum carbosilane, polyzirconium carbosilane, polytitanium carbosilane, polyyttrium carbosilane, etc.

[0014] Further preferably, the organosilicon polymer is polyaluminum carbosilane and polyyttrium carbosilane. Further preferably, the mass ratio of polyaluminum carbosilane and polyyttrium carbosilane is 70:30 to 95:5.

[0015] Preferably, the amount of metal element doping in the metal element-doped polycarbosilane is 0.1 to 10 wt%. Further preferably, it is 0.5 to 5 wt%.

[0016] Preferably, the method for preparing the boron compound-modified organosilicon polymer comprises the following steps:

[0017] The boron compound and the organosilicon polymer are dissolved in a solvent, electron beam irradiation grafting is performed under an inert atmosphere, and then the solvent is removed by drying to obtain the boron compound-modified organosilicon polymer.

[0018] Preferably, the content of the boron compound relative to the organosilicon polymer is 0.05 to 20 wt%. Further preferably, it is 0.1 to 10 wt%.

[0019] Preferably, the irradiation dose of the electron beam irradiation grafting is 5 to 200 kGy, further preferably 10 to 100 kGy, and the irradiation time is 1 to 120 min.

[0020] The inert atmosphere herein includes one of nitrogen, argon, and helium.

[0021] In the method for preparing the boron compound-modified organosilicon polymer, the solvent is any solvent capable of dissolving the boron compound and the organosilicon polymer, including but not limited to one or more of benzene, toluene, xylene, carbon tetrachloride, etc. The drying method can be vacuum drying, air blowing drying, room temperature natural drying, etc., as long as it is a drying means capable of removing the solvent.

[0022] The spinning includes methods such as melt spinning, dry spinning, electrospinning, and melt-blowing spinning, preferably melt spinning and dry spinning, to prepare continuous silicon carbide fibrils.

[0023] In the melt spinning, the boron compound modified organosilicon polymer is placed in a spinning cylinder, heated to 100-350℃ under inert atmosphere, spun through the spinning hole under the pressure (0.1-2 MPa) and collected by a spinning drum to obtain the precursor fiber. In the dry spinning, the boron compound modified organosilicon polymer is dissolved in an organic solvent to form a spinning solution, and then the spinning solution is placed in a spinning device to spin. The above-mentioned organic solvent is any solvent capable of dissolving the boron compound modified organosilicon polymer, including one or more of benzene, toluene, xylene, carbon tetrachloride, etc.

[0024] The electron beam irradiation of the present application is carried out in an oxygen-containing atmosphere. The electron beam energy is 1-5 MeV, and the beam current is 1-50 mA.

[0025] Preferably, the irradiation dose of the electron beam irradiation is 1-10 MGy, preferably 2-5 MGy.

[0026] Preferably, the irradiation time of the electron beam irradiation is 0.1-5 h, preferably 0.5-2 h.

[0027] Preferably, the oxygen-containing atmosphere is composed of oxygen and inert gas, wherein the content of oxygen is 0.5-10 v / v%. Preferably, it is 1-8 v / v%.

[0028] Preferably, the sintering is carried out in an inert atmosphere, the treatment temperature is 1000-1300℃, and the treatment time is 10-60 min. Further preferably, the sintering is carried out in a nitrogen atmosphere.

[0029] Preferably, the high-temperature sintering is carried out in an inert atmosphere, the treatment temperature is 1500-2000℃, and the treatment time is 10-60 min. Further preferably, the high-temperature sintering is carried out in an argon atmosphere.

[0030] Preferably, the high-temperature resistant silicon carbide ceramic fiber has an oxygen content of ≤1 wt%, a tensile strength of ≥2.0 GPa, a tensile modulus of ≥350 GPa, and a tensile strength loss of ≤10% after being treated in an inert atmosphere at 1800-2000℃ for 0.5-2 h.

[0031] Preferably, the high-temperature resistant silicon carbide ceramic fiber has a diameter of 3-15 μm, further preferably 5-9 μm.

[0032] Another object of the present application is to provide a method for preparing a high-temperature resistant silicon carbide ceramic fiber, comprising the following steps:

[0033] Spinning the raw material to obtain the precursor fiber, wherein the raw material comprises a boron compound modified organosilicon polymer;

[0034] The fibrils are subjected to electron beam irradiation in an oxygen-containing atmosphere for non-melting treatment;

[0035] The non-melting treated fibers are subjected to sintering and high-temperature sintering;

[0036] The boron-containing compound modified silicone polymer is obtained by grafting the boron-containing compound onto the silicone polymer through electron beam irradiation;

[0037] The boron-containing compound is a boroxin derivative, and its molecular structure is shown in the following formula:

[0038]

[0039] In the formula, R1, R2 and R3 are independently selected from one of a phenyl group and a substituted phenyl group.

[0040] Compared with the prior art, the present application has the following beneficial effects:

[0041] 1. The boron-containing compound modified silicone polymer is used as a raw material for preparing SiC fibers, so that the controlled introduction of boron into the SiC fibers is realized, the boron source is less lost and uniformly distributed in the fibers, and the high-temperature sintering densification is significantly promoted. It is proved that the raw material can be subjected to non-melting treatment by electron beam irradiation, and a higher irradiation dose rate can be used, and the non-melting treatment time is greatly shortened from 10-20 hours to 0.5-2 hours.

[0042] 2. The SiC fibers prepared by the present application have excellent mechanical properties, and the tensile strength is ≥2.0 GPa and the tensile modulus is ≥350 GPa.

[0043] 3. The SiC fibers prepared by the present application have a low oxygen content, and the oxygen content is ≤1 wt%.

[0044] 4. The SiC fibers prepared by the present application have good high-temperature resistance, and after being treated in an argon atmosphere at 1900℃ for 1h, the tensile strength loss of the SiC fibers is ≤10%.

[0045] 5. The SiC fibers prepared by using the boron-containing compound modified polyaluminum carbosilane and polyyttrium carbosilane as raw materials have more excellent mechanical properties and high-temperature resistance. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is an SEM photo of the SiC fibers prepared in Example 1 of the present application;

[0047] Figure 2 is an XRD photo of the SiC fibers prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0048] The technical solutions of the present application are described and explained further by specific examples and drawings. It should be understood that the specific examples described herein are only used to help understand the present application and are not used to limit the present application. The drawings used herein are only used to better illustrate the disclosed content of the present application and do not limit the scope of protection. If not specifically stated, the raw materials used in the examples of the present application are all commonly used raw materials in the art, and the methods used in the examples are all conventional methods in the art.

[0049] In the following examples and comparative examples:

[0050] The polyaluminum carbosilane has a weight average molecular weight of about 3000 g / mol and an aluminum content of about 1 wt %;

[0051] The polyzirconium carbosilane has a weight average molecular weight of about 3000 g / mol and a zirconium content of about 1 wt %;

[0052] The polytitanium carbosilane has a weight average molecular weight of about 3000 g / mol and a titanium content of about 1 wt %;

[0053] The polyyttrium carbosilane has a weight average molecular weight of about 3000 g / mol and a yttrium content of about 1 wt %;

[0054] The electron beam irradiation oxidation process uses a 2 MeV electron accelerator with a beam current of 2-20 mA.

[0055] Structural characterization and performance testing:

[0056] The mechanical properties of the silicon carbide fibers are tested by using a single fiber property analyzer (TEXTECHNO, Germany). The microstructure of the silicon carbide fibers is characterized by using a scanning electron microscope (SEM, FEI, USA). The crystal structure of the silicon carbide fibers is characterized by using an X-ray diffractometer (XRD, Bruker, Germany).

[0057] Example 1

[0058] The silicon carbide ceramic fibers of Example 1 are prepared by the following method:

[0059] 1 part by mass of triphenylboroxine (CAS No.: 3262-89-3) and 100 parts by mass of polyaluminocarbosilane were dissolved in 200 parts by mass of benzene, and electron beam irradiation was performed under a nitrogen atmosphere at a dose of 100 kGy for 10 minutes, followed by vacuum drying to remove the solvent, thereby obtaining triphenylboroxine-modified polyaluminocarbosilane. Using the triphenylboroxine-modified polyaluminocarbosilane as a raw material, a precursor fiber was prepared by melt spinning, and then unmelting treatment was performed under electron beam irradiation at a dose of 4 MGy for 1.5 hours in an atmosphere of argon and oxygen (95:5, v / v). The fiber after the unmelting treatment was subjected to firing treatment under a nitrogen atmosphere at 1200°C for 30 minutes, and then high-temperature sintering treatment was performed under an argon atmosphere at 1900°C for 30 minutes, thereby obtaining a SiC fiber.

[0060] The SiC fiber prepared in Example 1 had an oxygen content of 0.32%, a tensile strength of about 2.2 GPa, and a tensile modulus of about 375 GPa. The SiC fiber was treated under an argon atmosphere at 1900°C for 1 hour, and the tensile strength was lost by 8%.

[0061] An SEM photograph of the SiC fiber prepared in Example 1 is shown in Figure 1 As can be seen, the SiC fiber had a diameter of about 5 μm, and the surface and cross section were smooth and dense without any obvious defects. An XRD photograph of the SiC fiber is shown in Figure 2 As can be seen, the SiC fiber had a high degree of crystallinity.

[0062] Example 2

[0063] The silicon carbide ceramic fiber of Example 2 was prepared by the following method:

[0064] 2 parts by mass of triphenylboroxine and 100 parts by mass of polyaluminocarbosilane were dissolved in 200 parts by mass of toluene, and electron beam irradiation was performed under a nitrogen atmosphere at a dose of 80 kGy for 15 minutes, followed by vacuum drying to remove the solvent, thereby obtaining triphenylboroxine-modified polyaluminocarbosilane. Using the triphenylboroxine-modified polyaluminocarbosilane as a raw material, a precursor fiber was prepared by melt spinning, and then unmelting treatment was performed under electron beam irradiation at a dose of 2 MGy for 1 hour in an atmosphere of argon and oxygen (94:6, v / v). The fiber after the unmelting treatment was subjected to firing treatment under a nitrogen atmosphere at 1100°C for 35 minutes, and then high-temperature sintering treatment was performed under an argon atmosphere at 1800°C for 40 minutes, thereby obtaining a SiC fiber.

[0065] The SiC fiber prepared in Example 2 had an oxygen content of 0.41%, a tensile strength of about 2.0 GPa, and a tensile modulus of about 354 GPa. The SiC fiber was treated under an argon atmosphere at 1900°C for 1 hour, and the strength was lost by 5%.

[0066] Example 3

[0067] The silicon carbide ceramic fiber of Example 3 was prepared by the following method:

[0068] Ten parts by mass of triphenylboroxine was dissolved in 100 parts by mass of polyzirconocarbosilane in 200 parts by mass of xylene, and electron beam irradiation was performed under a nitrogen atmosphere at a dose of 100 kGy for 5 minutes. The solvent was then removed by vacuum drying to obtain triphenylboroxine-modified polyzirconocarbosilane. Using the triphenylboroxine-modified polyzirconocarbosilane as a raw material, a precursor fiber was prepared by melt spinning, and then subjected to infusibilization treatment under electron beam irradiation at a dose of 5 MGy for 2 hours in an atmosphere of argon and oxygen (98:2, v / v). The fiber after infusibilization treatment was subjected to firing treatment under a nitrogen atmosphere at 1200°C for 32 minutes, and then high-temperature sintering treatment under an argon atmosphere at 1850°C for 45 minutes to obtain a SiC fiber.

[0069] The SiC fiber prepared in Example 3 had an oxygen content of 0.46%, a tensile strength of about 2.1 GPa, and a tensile modulus of about 355 GPa. The SiC fiber had a strength loss of 6% after being treated under an argon atmosphere at 1900°C for 1 hour.

[0070] Example 4

[0071] The silicon carbide ceramic fiber of Example 4 was prepared by the following method:

[0072] Three parts by mass of triphenylboroxine was dissolved in 100 parts by mass of polytitanocarbosilane in 200 parts by mass of carbon tetrachloride, and electron beam irradiation was performed under a nitrogen atmosphere at a dose of 70 kGy for 7 minutes. The solvent was then removed by vacuum drying to obtain triphenylboroxine-modified polytitanocarbosilane. Using the triphenylboroxine-modified polytitanocarbosilane as a raw material, a precursor fiber was prepared by melt spinning, and then subjected to infusibilization treatment under electron beam irradiation at a dose of 3 MGy for 2 hours in an atmosphere of argon and oxygen (99:1, v / v). The fiber after infusibilization treatment was subjected to firing treatment under a nitrogen atmosphere at 1300°C for 25 minutes, and then high-temperature sintering treatment under an argon atmosphere at 1950°C for 25 minutes to obtain a SiC fiber.

[0073] The SiC fiber prepared in Example 4 had an oxygen content of 0.22%, a tensile strength of about 2.0 GPa, and a tensile modulus of about 370 GPa. The SiC fiber had a tensile strength loss of 9% after being treated under an argon atmosphere at 1900°C for 1 hour.

[0074] Example 5

[0075] The silicon carbide ceramic fiber of Example 5 was prepared by the following method:

[0076] One part by mass of triphenylboroxin, 90 parts by mass of polycarbosilane and 10 parts by mass of polyaluminocarbosilane were dissolved in 200 parts by mass of benzene, and electron beam irradiation was performed under a nitrogen atmosphere at a dose of 100 kGy for 10 minutes. The solvent was then removed by vacuum drying to obtain triphenylboroxin-modified polycarbosilane and polyaluminocarbosilane. Using the triphenylboroxin-modified polycarbosilane and polyaluminocarbosilane as raw materials, the subsequent steps were the same as in Example 1 to produce SiC fiber.

[0077] The SiC fiber produced in Example 5 had an oxygen content of 0.12%, a tensile strength of about 2.5 GPa and a tensile modulus of about 390 GPa. After treatment of the SiC fiber in an argon atmosphere at 1900°C for 1 hour, the tensile strength was lost by 6%.

[0078] Example 6

[0079] The silicon carbide ceramic fiber of Example 6 was prepared by the following method:

[0080] One part by mass of triphenylboroxin, 100 parts by mass of polyaluminocarbosilane were dissolved in 200 parts by mass of benzene, and electron beam irradiation was performed under a nitrogen atmosphere at a dose of 100 kGy for 10 minutes. The solvent was then removed by vacuum drying to obtain triphenylboroxin-modified polyaluminocarbosilane. Using the triphenylboroxin-modified polyaluminocarbosilane as raw materials, the subsequent steps were the same as in Example 1 to produce SiC fiber.

[0081] The SiC fiber produced in Example 6 had an oxygen content of 0.2%, a tensile strength of about 2.2 GPa and a tensile modulus of about 365 GPa. After treatment of the SiC fiber in an argon atmosphere at 1900°C for 1 hour, the tensile strength was lost by 8%.

[0082] Comparative Example 1

[0083] Comparative Example 1 differs from Example 1 in that the SiC fiber was produced using polycarbosilane which had not been irradiated to graft boroxin, and the subsequent steps were the same as in Example 1.

[0084] The SiC fiber produced in Comparative Example 1 had an oxygen content of 0.35%, a tensile strength of about 1.6 GPa and a tensile modulus of about 320 GPa. After treatment of the SiC fiber in an argon atmosphere at 1900°C for 1 hour, the tensile strength was lost by 20%.

[0085] Comparative Example 2

[0086] Comparative Example 2 differs from Example 1 in that Comparative Example 2 uses air-inerting treatment instead of electron beam irradiation-inerting treatment of Example 1, and the air-inerting treatment is as follows: the as-prepared fiber is subjected to inerting treatment in air at 200°C, the heating rate is 10°C / h, and the constant temperature time is 2h, to obtain the inerting treated fiber. The other steps are the same as those of Example 1.

[0087] The SiC fiber prepared in Comparative Example 2 has an oxygen content of 0.52%, a tensile strength of about 1.4 GPa, and a tensile modulus of about 300 GPa. After the SiC fiber is treated in argon at 1900°C for 1h, the tensile strength is lost by 15%.

[0088] Comparative Example 3

[0089] Comparative Example 3 differs from Example 1 in that Comparative Example 3 uses the polyaluminocarbosilane grafted with unirradiated boroxin as the raw material, and the as-prepared fiber is prepared by melt spinning, and Comparative Example 3 uses air-inerting treatment instead of electron beam irradiation-inerting treatment of Example 1, and the air-inerting treatment is the same as that of Comparative Example 2.

[0090] The SiC fiber prepared in Comparative Example 3 has an oxygen content of 0.53%, a tensile strength of about 1.3 GPa, and a tensile modulus of about 295 GPa. After the SiC fiber is treated in argon at 1900°C for 1h, the tensile strength is lost by 23%.

[0091] Comparative Example 4

[0092] The silicon carbide ceramic fiber of Comparative Example 4 is prepared by the following method:

[0093] 1 part by mass of triphenylboroxin and 100 parts by mass of polyaluminocarbosilane are dissolved in 200 parts by mass of benzene, stirred for 60 min, and then vacuum dried to remove the solvent, to obtain a blend of triphenylboroxin and polyaluminocarbosilane. The as-prepared fiber is prepared by melt spinning using the blend of triphenylboroxin and polyaluminocarbosilane as the raw material, and the subsequent steps are the same as those of Example 1.

[0094] The SiC fiber prepared in Comparative Example 4 has an oxygen content of 0.34%, a tensile strength of about 1.7 GPa, and a tensile modulus of about 330 GPa. After the SiC fiber is treated in argon at 1900°C for 1h, the tensile strength is lost by 16%.

[0095] Comparative Example 5

[0096] The silicon carbide ceramic fiber of Comparative Example 5 is prepared by the following method:

[0097] 1 part by mass of trimethylboroxine (CAS No.: 823-96-1) was dissolved in 100 parts by mass of polyaluminocarbosilane in 200 parts by mass of benzene, and electron beam irradiation was performed under a nitrogen atmosphere at a dose of 100 kGy for 10 minutes. The solvent was then removed by vacuum drying to obtain trimethylboroxine-modified polyaluminocarbosilane. Using the trimethylboroxine-modified polyaluminocarbosilane as a raw material, a precursor fiber was produced by melt spinning, and the subsequent steps were the same as in Example 1.

[0098] The SiC fiber produced in Comparative Example 6 had an oxygen content of 0.36%, a tensile strength of about 1.8 GPa, and a tensile modulus of about 345 GPa. After treatment at 1900°C under an argon atmosphere for 1 hour, the tensile strength of the SiC fiber was reduced by 15%.

[0099] Comparative Example 6

[0100] The SiC ceramic fiber of Comparative Example 6 was produced by the following method:

[0101] 1 part by mass of borazine (CAS No.: 6569-51-3) was dissolved in 100 parts by mass of polyaluminocarbosilane in 200 parts by mass of benzene, and electron beam irradiation was performed under a nitrogen atmosphere at a dose of 100 kGy for 10 minutes. The solvent was then removed by vacuum drying to obtain borazine-modified polyaluminocarbosilane. Using the borazine-modified polyaluminocarbosilane as a raw material, a precursor fiber was produced by melt spinning, and the subsequent steps were the same as in Example 1.

[0102] The SiC fiber produced in Comparative Example 6 had an oxygen content of 0.36%, a tensile strength of about 1.8 GPa, and a tensile modulus of about 345 GPa. After treatment at 1900°C under an argon atmosphere for 1 hour, the tensile strength of the SiC fiber was reduced by 15%.

[0103] The SiC fibers produced in Examples 1 to 6 had high tensile strengths and low tensile strength loss rates after treatment at high temperatures, indicating excellent high-temperature resistance. Using triphenylboroxine-modified polyaluminocarbosilane, triphenylboroxine-modified polyyttrium carbosilane, and triphenylboroxine-modified polyaluminocarbosilane and polyyttrium carbosilane as raw materials in Examples 1, 6, and 5, respectively, it was unexpectedly found that the SiC fibers produced using triphenylboroxine-modified polyaluminocarbosilane and polyyttrium carbosilane as raw materials exhibited superior performance to those produced in Examples 1 and 6.

[0104] As shown by comparing Comparative Examples 1, 2, and 3 with Example 1, using a boron-containing compound-modified organosilicon polymer as a raw material in combination with electron beam irradiation non-melting treatment is beneficial for improving the tensile strength, tensile modulus, and high-temperature resistance of SiC fibers.

[0105] Comparative Example 4: triphenylboroxin was physically mixed with polyaluminosilacarbosane, without electron beam irradiation graft modification. The blend of triphenylboroxin and polyaluminosilacarbosane was used as raw material, combined with electron beam irradiation non-melting treatment. The boron element could not be uniformly introduced into the fiber, resulting in a decrease in the performance of the prepared SiC fiber. Comparative Example 5 and Comparative Example 6: trimethylcyclotriboroxin and cyclotriborazane were used to replace triphenylboroxin to modify polyaluminosilacarbosane by electron beam irradiation, respectively. It can be found that the effect of trimethylcyclotriboroxin modified polyaluminosilacarbosane and cyclotriborazane modified polyaluminosilacarbosane is not as good as that of triphenylboroxin modified polyaluminosilacarbosane.

[0106] Aspects, embodiments, features, and the like of the present application are to be considered illustrative only and not restrictive in all respects. The scope of the present application is defined by the appended claims rather than the foregoing description. Other embodiments, modifications, and uses can be apparent to those skilled in the art, which do not depart from the spirit and scope of the claimed application.

[0107] In the preparation method of the present application, the order of each step is not limited to the order listed. For those skilled in the art, the order of each step can be changed without creative labor, which is within the protection scope of the present application. In addition, two or more steps or actions can be performed simultaneously.

[0108] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the scope of the present application. Those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace them. Here, it is not necessary or possible to fully exemplify all embodiments. Any obvious changes or variations derived from the essential spirit of the present application are still within the protection scope of the present application, and any interpretation as any additional limitation is contrary to the spirit of the present application.

Claims

1. A high-temperature resistant silicon carbide ceramic fiber, characterized in that, It is prepared by using boron-containing compound-modified organosilicon polymer as a precursor, through steps including spinning, electron beam irradiation non-melting, sintering, and high-temperature sintering; Boron-containing compound-modified organosilicon polymers are obtained by grafting boron-containing compounds onto organosilicon polymers via electron beam irradiation; The boron-containing compound is a cycloboroxane derivative, and its molecular structure is shown below: In the formula, R1, R2, and R3 are each individually selected from phenyl and phenyl containing substituents.

2. The high-temperature resistant silicon carbide ceramic fiber according to claim 1, characterized in that, The preparation method of boron-containing compound-modified organosilicon polymer includes the following steps: Boron-containing compounds and organosilicon polymers were dissolved in a solvent, grafted by electron beam irradiation under an inert atmosphere, and then dried to remove the solvent, yielding boron-containing compound-modified organosilicon polymers.

3. The high-temperature resistant silicon carbide ceramic fiber according to claim 1 or 2, characterized in that, The organosilicon polymer is a polycarbosilane doped with a metal element, wherein the metal element is one or more of aluminum, zirconium, titanium, and yttrium.

4. The high-temperature resistant silicon carbide ceramic fiber according to claim 1 or 2, characterized in that, The organosilicon polymers are polyaluminosilane and polyyttrium carbosilane; The mass ratio of polyaluminosilane to polyyttrium carbosilane is 70:30 to 95:

5.

5. A high-temperature resistant silicon carbide ceramic fiber according to claim 1 or 2, characterized in that, The irradiation dose for electron beam grafting is 5–200 kGy; And / or, the content of boron-containing compounds relative to organosilicon polymers is 0.05–20 wt%.

6. The high-temperature resistant silicon carbide ceramic fiber according to claim 1, characterized in that, Electron beam irradiation non-melting is carried out using electron beam irradiation in an oxygen-containing atmosphere; The electron beam irradiation dose for non-melting materials is 1–10 mgy, and the irradiation time is 0.1–5 h. The oxygen-containing atmosphere consists of oxygen and an inert gas, wherein the oxygen content is 0.5–10 v / v.

7. The high-temperature resistant silicon carbide ceramic fiber according to claim 1, characterized in that, The firing is carried out in an inert atmosphere, at a temperature of 1000–1300°C, for a time of 10–60 min. And / or, the high-temperature sintering is carried out in an inert atmosphere, with a processing temperature of 1500–2000°C and a processing time of 10–60 min.

8. The high-temperature resistant silicon carbide ceramic fiber according to claim 1, characterized in that, The high-temperature resistant silicon carbide ceramic fiber has an oxygen content of ≤1wt%, a tensile strength of ≥2.0GPa, a tensile modulus of ≥350GPa, and a tensile strength loss of ≤10% after treatment in an inert atmosphere at 1800~2000℃ for 0.5~2h.

9. A method for preparing high-temperature resistant silicon carbide ceramic fibers, characterized in that, Includes the following steps: The raw material is spun to obtain the fibrils, wherein the raw material includes a boron-containing compound-modified organosilicon polymer; The fibrils are subjected to electron beam irradiation in an oxygen-containing atmosphere to prevent melting. The fibers, after being treated to prevent melting, are then fired and sintered at high temperatures. Boron-containing compound-modified organosilicon polymers are obtained by grafting boron-containing compounds onto organosilicon polymers via electron beam irradiation; The boron-containing compound is a cycloboroxane derivative, and its molecular structure is shown below: In the formula, R1, R2, and R3 are each individually selected from phenyl and phenyl containing substituents.

10. The preparation method according to claim 9, characterized in that, The organosilicon polymer is a polycarbosilane doped with a metal element, wherein the metal element is one or more of aluminum, zirconium, titanium, and yttrium; And / or, the content of boron-containing compounds relative to organosilicon polymers is 0.05–20 wt%; And / or, electron beam irradiation non-melting is carried out in an oxygen-containing atmosphere by electron beam irradiation, with an irradiation dose of 1 to 10 mgy and an irradiation time of 0.1 to 5 h, wherein the oxygen-containing atmosphere is composed of oxygen and an inert gas, wherein the oxygen content is 0.5 to 10 v / v%. And / or, the firing is carried out in an inert atmosphere, at a temperature of 1000–1300°C, for a time of 10–60 min; And / or, the high-temperature sintering is carried out in an inert atmosphere, with a processing temperature of 1500–2000°C and a processing time of 10–60 min.

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