CVD growth type high-temperature-resistant silicon carbide and preparation method thereof

Abstract

The invention belongs to the technical field of silicon carbide preparation, and provides CVD growth type high-temperature-resistant silicon carbide and a preparation method thereof. Through chemical vapor deposition and synergistic application of three self-made functional additives, firstly, a boron-containing organosilicon polymer precursor solution is prepared by reacting polycarbosilane with a borane reagent; secondly, an organometallic compound containing an aluminum-nitrogen cage structure is synthesized by reacting amines with an aluminum hydride reagent; finally, preparing an organic chelate mixed solution containing yttrium and zirconium; in the deposition core stage, a vinyl-terminated boron modified polycarbosilane solution and aluminum-azacyclo-cubic alkane are periodically and alternately introduced, in-situ activation is performed on the surface by utilizing process byproducts, then a Y / Zr-beta-diketoester mixed solution is introduced, and the prepared silicon carbide product is highly ordered in microstructure, has high toughness and high temperature resistance, and can be used for preparing a silicon carbide material. And the comprehensive performance and reliability of the material under extreme working conditions are improved.

Description

TECHNICAL FIELD

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

[0002] Silicon carbide ceramics have been widely used in aerospace, energy and chemical industry and other extreme working conditions due to their high hardness, excellent high-temperature strength and chemical stability. However, the application range and reliability thereof are still limited by some inherent technical bottlenecks. First, the most significant defect of traditional silicon carbide materials is their inherent high brittleness, which leads to low fracture toughness and high sensitivity to internal microdefects, and thus catastrophic brittle fracture is prone to occur under external force or thermal shock, which seriously limits the reliability of the materials as key structural load-bearing components. Second, although silicon carbide has good oxidation resistance, the protective silicon dioxide layer formed on the surface thereof may fail due to volatilization or reaction with impurities when the material is used in a harsh environment with ultra-high temperature and oxygen for a long time, and especially when there are microcracks on the surface of the material, oxidation will erode the material along the cracks, leading to continuous degradation or even failure of the material performance. SUMMARY

[0003] In view of the deficiencies in the prior art, the purpose of the present application is to provide CVD growth type high-temperature-resistant silicon carbide and a preparation method thereof. First, a mixture of boron-containing organosilicon polymer, aluminum-nitrogen-containing cage organometallic compound and yttrium-zirconium-containing organic chelate is prepared, a pulse gradient process is adopted in the present application, the materials are alternately introduced periodically during the deposition process, and the supply thereof is accurately controlled over time, so as to construct a layered structure. Then, the surface is activated in situ by using a process by-product, and a yttrium-zirconium-containing precursor is introduced, so as to meet the needs of actual production.

[0004] To achieve the above purpose, the present application adopts the following technical solutions:

[0005] In a first aspect, the present application provides a preparation method of CVD growth type high-temperature-resistant silicon carbide, which comprises the following steps:

[0006] S1, dispersing polycarbosilane in anhydrous xylene, adding divinylbenzene for reflux reaction, adding borane-tetrahydrofuran for reaction after the reaction is completed, obtaining modified polycarbosilane, dispersing the modified polycarbosilane in anhydrous toluene to obtain an end-vinyl boron-modified polycarbosilane solution;

[0007] S2, dispersing lithium aluminum hydride in anhydrous diethyl ether, adding tert-butylamine for stirring at room temperature and reflux reaction, obtaining aluminum-nitrogen heterocyclic cubane;

[0008] S3, dispersing yttrium tris(2,2,6,6-tetramethyl-3,5-heptanedionate) and zirconium tetra(2,2,6,6-tetramethyl-3,5-heptanedionate) in a mixed solvent, and ultrasonic treatment to obtain a Y / Zr-beta-diketonate mixed solution, wherein the mixed solvent is a mixed solvent of tetrahydrofuran and n-butanol;

[0009] S4, after the graphite plate is cleaned and dried, the graphite plate is placed in a horizontal hot-wall CVD reaction furnace, vacuum pumping and argon replacement are performed, a deposition process is performed on the graphite plate using methylchlorosilane, the end-vinyl boron-modified polycarbosilane solution, the aluminum-nitrogen heterocyclic cubane, and the Y / Zr-beta-diketonate mixed solution, and after the deposition process is completed, a CVD growth type high-temperature-resistant silicon carbide is obtained.

[0010] Specifically includes:

[0011] S1, dispersing polycarbosilane in anhydrous xylene, adjusting the temperature to a first temperature, adding divinylbenzene, adjusting the temperature to a second temperature, and refluxing to react, cooling to room temperature after the reaction is completed, transferring to an ice water bath, adding borane-tetrahydrofuran, removing the ice water bath after the addition is completed, stirring to react at room temperature, and then re-heating to a third temperature to continue the reaction, cooling to room temperature after the reaction is completed, and adding the reaction solution to anhydrous n-hexane to collect the precipitate, washing, drying to obtain modified polycarbosilane, and then dispersing the modified polycarbosilane in anhydrous toluene to obtain an end-vinyl boron-modified polycarbosilane solution;

[0012] S2, dispersing lithium aluminum hydride in anhydrous diethyl ether in an argon atmosphere, adding tert-butylamine under ice water bath conditions, removing the ice bath and stirring at room temperature, adjusting the temperature to a fourth temperature to reflux to react, filtering to remove insoluble substances, vacuum distillation, anhydrous n-hexane washing, recrystallization, and vacuum drying to obtain aluminum-nitrogen heterocyclic cubane;

[0013] S3, dispersing yttrium tris(2,2,6,6-tetramethyl-3,5-heptanedionate) and zirconium tetra(2,2,6,6-tetramethyl-3,5-heptanedionate) in a mixed solvent, and ultrasonic treatment to obtain a Y / Zr-beta-diketonate mixed solution;

[0014] S4, after the graphite plate is cleaned and dried, the graphite plate is placed in a horizontal hot-wall CVD reaction furnace, vacuum pumping and argon replacement are performed, a deposition process is performed on the graphite plate using methylchlorosilane, the end-vinyl boron-modified polycarbosilane solution, the aluminum-nitrogen heterocyclic cubane, and the Y / Zr-beta-diketonate mixed solution, and after the deposition process is completed, a CVD growth type high-temperature-resistant silicon carbide is obtained.

[0015] Step S1 is crosslinking polycarbosilane by divinylbenzene. The mechanism is that the bifunctional group of divinylbenzene reacts with the active site on the polycarbosilane chain at high temperature to convert the linear polymer chain into a three-dimensional network structure, thereby improving the thermal stability and ceramic yield of the precursor and inhibiting the mass loss caused by excessive cracking into small molecules at a subsequent high temperature. The subsequent boronization modification step has a chemical mechanism of hydrogenation addition reaction of the boro-tetrahydrofuran complex to the residual vinyl double bond in the polymer network. The B-H bond in borane is broken and added to the carbon-carbon double bond, thereby stably introducing boron atoms into the molecular skeleton of the polymer in the form of a covalent bond. The end-vinyl boron-modified polycarbosilane precursor used is thermally cracked at a deposition temperature, and the silicon-carbon bonds in the molecular skeleton are retained and recombined into a β-SiC lattice, while the introduced boron atoms react with carbon to in-situ precipitate boron carbide nanowhisker phase. At the same time, part of the organic groups in the polymer are thermally cracked to produce exfoliated graphite carbon, and the three phases are co-deposited on a nanometer scale to form an in-situ generated nano-composite structure. In this structure, high-modulus silicon carbide and boron carbide serve as the reinforcing phase, and the graphite carbon phase wrapped therein serves as a flexible interface. When a crack propagates in such a micro-region, the energy will be dissipated due to the deflection of the crack path at different phase interfaces, thereby improving the fracture work and toughness of the material.

[0016] In step S2, the nucleophilic attack and deprotonation of the hydrogen anion in lithium aluminum hydride to the N-H bond in tert-butylamine are accompanied by the release of hydrogen gas to form an intermediate. Then the intermediate self-assembles into a thermodynamically stable aluminum-nitrogen heterocyclic cubane cage structure. The essential feature of this structure is that aluminum atoms and nitrogen atoms occupy the vertices of the cube in an alternating manner within the molecule. During the subsequent step S4 of gas-phase transport and thermal decomposition, aluminum and nitrogen can be released at the same rate and in the same spatial position, thereby maximizing their uniform co-doping in the growing silicon carbide lattice and avoiding element segregation caused by differences in decomposition rates when using a dual-source precursor.

[0017] Step S3 uses β-diketone ligands to chelate yttrium and zirconium metal ions, and the tert-butyl group forms effective steric hindrance to wrap the metal ions therein and shield their interaction with solvents or other molecules, thereby significantly improving the solubility and stability of the two metal organic compounds in non-polar organic solvents. Dissolving these two chelates with similar chemical properties in the same mixed solvent can form a uniform molecular solution, ensuring that yttrium and zirconium can be simultaneously and uniformly introduced into the reaction chamber at a preset molar ratio during the subsequent step S4 of gas-phase transport, thereby laying a material foundation for forming a dispersedly distributed oxide nanobiphase structure on the surface layer of the final product.

[0018] The high-temperature hydrogen flow in step S4 is to etch and reduce the oxides and impurities on the surface of the graphite substrate, forming active sites conducive to the heterogeneous nucleation of silicon carbide. The mechanism of A1 in the deposition process is to co-deposit the modified polycarbosilane prepared in step S1 with methyltrichlorosilane to form a nanocomposite transition layer rich in boron carbide and free carbon, which effectively alleviates the thermal mismatch stress between the subsequent deposition layer and the substrate through dispersion toughening. A2 uses the difference in cracking rate between the end-vinyl boron-modified polycarbosilane solution and the aluminum-nitrogen heterocyclic cubic alkane at a set temperature by high-speed and periodic pulse switching of different precursor gas sources to deposit nanometer thin layers with different compositions in each cycle. Preferably, by nonlinearly regulating the time length of the two pulses, the thickness ratio of the two nanometer layers is systematically changed, so that the microstructure and chemical composition of the material in the direction perpendicular to the substrate present a continuous gradient change. The mechanism of A3 is to use the chemical potential of the process byproduct hydrogen chloride to perform in-situ gas phase etching on the fresh growth surface, which removes unstable amorphous phases and dangling bonds, increases the surface energy, and provides a high-quality epitaxial growth interface for A4. The mechanism of A4 is to co-deposit the yttrium / zirconium precursor prepared in step S3 while growing the silicon carbide substrate, and the pyrolysis products of which are in the form of oxide nanoparticles coated in the surface layer grain boundaries and inside the grains, finally forming a structure with potential hierarchical self-healing ability.

[0019] The yttrium and zirconium organometallic salts deposited on the surface layer are dispersed in the form of oxide nanoparticles in the silicon carbide matrix after pyrolysis. When the material appears microcracks in a high-temperature oxygen-containing environment, the newly exposed silicon carbide surface at the crack tip will preferentially oxidize to form solid silicon dioxide. In the high-temperature range, the dispersed yttrium oxide reacts with the newly formed silicon dioxide to form a eutectic phase of yttrium silicate, which has fluidity and penetrates and fills the cracks under the action of capillary force, and solidifies after cooling, thereby repairing the micro-damage. In a higher temperature range, when the yttrium silicate may volatilize or become unstable, the more chemically stable zirconium oxide particles come into play. These particles, as a second phase, can pin and hinder the further expansion of the crack tip, forming a solid-phase toughening and repairing mechanism.

[0020] As a preferred technical solution of the present application, in S1, the mass-volume ratio of polycarbosilane, anhydrous xylene, divinylbenzene and borane-tetrahydrofuran is (20-22) g: 200 mL: (0.8-1.5) g: (100-110) mL, for example, it can be (20, 20.2, 20.4, 20.6, 20.8, 21.0, 21.2, 21.4, 21.6, 21.8 or 22) g: 200 mL: (0.8, 0.87, 0.94, 1.01, 1.08, 1.15, 1.22, 1.29, 1.36, 1.43 or 1.5) g: (100, 101, 102, 103, 104, 105, 106, 107, 108, 109 or 110) mL, but not limited to the listed values, other values not listed in the range are also applicable.

[0021] In some optional embodiments, the number average molecular weight of the polycarbosilane is 1100-2000, for example, it can be 1100, 1190, 1280, 1370, 1460, 1550, 1640, 1730, 1820, 1910 or 2000, but not limited to the listed values, other values not listed in the range are also applicable.

[0022] In some optional embodiments, the first temperature is 80-90℃, for example, it can be 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃ or 90℃, but not limited to the listed values, other values not listed in the range are also applicable.

[0023] In some optional embodiments, the second temperature is 130-140℃, for example, it can be 130℃, 131℃, 132℃, 133℃, 134℃, 135℃, 136℃, 137℃, 138℃, 139℃ or 140℃, but not limited to the listed values, other values not listed in the range are also applicable.

[0024] In some optional embodiments, the reflux reaction time is 6-8h, for example, it can be 6.0h, 6.2h, 6.4h, 6.6h, 6.8h, 7.0h, 7.2h, 7.4h, 7.6h, 7.8h or 8.0h, but not limited to the listed values, other values not listed in the range are also applicable.

[0025] In some optional embodiments, the concentration of borane-tetrahydrofuran is 1M.

[0026] In some optional embodiments, the time for the stirring reaction is 2-3h, for example, it can be 2.0h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3.0h, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0027] In some optional embodiments, the third temperature is 70-80℃, for example, it can be 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃ or 80℃, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0028] In some optional embodiments, the time for the continued reaction is 12-13h, for example, it can be 12.0h, 12.1h, 12.2h, 12.3h, 12.4h, 12.5h, 12.6h, 12.7h, 12.8h, 12.9h or 13.0h, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0029] In some optional embodiments, the mass fraction of the end-vinyl boron-modified polycarbosilane solution is 10wt.%.

[0030] As a preferred technical solution of the present application, in S2, the mass-volume ratio of lithium aluminum hydride, anhydrous diethyl ether and tert-butyl amine is (1.9-2.0)g:200mL:(14-15)g, for example, it can be (1.9, 1.91, 1.92, 1.93, 1.94, 1.95, 1.96, 1.97, 1.98, 1.99 or 2.0)g:200mL:(14.0, 14.1, 14.2, 14.3, 14.4, 14.5, 14.6, 14.7, 14.8, 14.9 or 15.0)g, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0031] In some optional embodiments, the time for the stirring at room temperature is 12-13h, for example, it can be 12.0h, 12.1h, 12.2h, 12.3h, 12.4h, 12.5h, 12.6h, 12.7h, 12.8h, 12.9h or 13.0h, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0032] In some optional embodiments, the fourth temperature is 33-36℃, for example, can be 33.0℃, 33.3℃, 33.6℃, 33.9℃, 34.2℃, 34.5℃, 34.8℃, 35.1℃, 35.4℃, 35.7℃ or 36.0℃, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0033] In some optional embodiments, the time of the reflux reaction is 24-25h, for example, can be 24.0h, 24.1h, 24.2h, 24.3h, 24.4h, 24.5h, 24.6h, 24.7h, 24.8h, 24.9h or 25.0h, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0034] As a preferred technical solution of the present application, in S3, the mass-volume ratio of yttrium tris(2,2,6,6-tetramethyl-3,5-heptanedionate), tetra(2,2,6,6-tetramethyl-3,5-heptanedionate) and mixed solvent is (3.2-3.3) g: (1.5-1.6) g: 200 mL, for example, can be (3.2, 3.21, 3.22, 3.23, 3.24, 3.25, 3.26, 3.27, 3.28, 3.29 or 3.3) g: (1.5, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58, 1.59 or 1.6) g: 200 mL, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0035] In some optional embodiments, the volume ratio of tetrahydrofuran to n-butanol in the mixed solvent is 4:1.

[0036] In some optional embodiments, the time of the ultrasonic treatment is 30-40min, for example, can be 30min, 31min, 32min, 33min, 34min, 35min, 36min, 37min, 38min, 39min or 40min, but not only limited to the listed values, other values not listed in the range of values are also applicable.

[0037] The deposition procedure comprises the following steps:

[0038] A0, at a rate of 10 °C / min, under a H2 / Ar mixed atmosphere at 20 kPa, with a flow rate of 10 SLM / 10 SLM, from room temperature to 1300-1320 °C, and holding for 30-40 min, and then decreasing to 1250 °C at a rate of 20 °C / min and stabilizing, for example, A0, at a rate of 10 °C / min, under a H2 / Ar atmosphere at 20 kPa, with a flow rate of 10 SLM / 10 SLM, from room temperature to 1300 °C, 1302 °C, 1304 °C, 1306 °C, 1308 °C, 1310 °C, 1312 °C, 1314 °C, 1316 °C, 1318 °C, or 1320 °C, and holding for 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min, or 40 min, but not limited to the listed values, other values not listed within this range are also applicable;

[0039] The deposition phase pressure is 4 kPa;

[0040] A1, the duration of A1 is from the 0th minute to the 45th minute after the deposition phase, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane source bottle temperature is 80 °C, delivered by a mass flow controller, the set flow rate corresponds to a mass flow rate of 0.9 g / min, and the end-vinyl boron-modified polycarbosilane solution mass flow rate is 0.1 g / min;

[0041] A2, the duration of A2 is in the range of 45-285 min, a PLC pulse program is used, 480 pulse cycles are performed, each cycle is 30 s, the parameters in the Nth cycle, N = 1-480, four sub-phases are performed in each cycle, and the sub-phases include B1, B2, B3, and B4;

[0042] B1, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 1.2 g / min, the aluminum-nitrogen heterocubane is heated to sublimation at 130 °C, the Ar carrier gas is 20 SCCM, corresponding to a mass flow rate of 0.008 g / min, the end-vinyl boron-modified polycarbosilane solution is closed, and the duration t1 = 14+6×[(N-1) / 479] seconds; 2

[0043] B2, the H2 / Ar purge is retained, the flow rate is 5 SLM / 5 SLM, and the duration is 1 s;

[0044] B3, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 0.6 g / min, the end-vinyl boron-modified polycarbosilane solution mass flow rate is 0.1 g / min, and the duration t2 = 14-6×[(N-1) / 479] seconds;

[0045] B4, the H2 / Ar purge is retained, the flow rate is 5 SLM / 5 SLM, and the duration is 1 s.​

[0046] A3, the time length of A3 is from the 285th minute to the 295th minute after the deposition stage, H2 is reserved, the flow rate is 2 SLM, the temperature is 1250℃, and the pressure is 4 kPa;

[0047] A4, the time length of A4 is from the 295th minute to the 355th minute after the deposition stage, the flow rate of H2 is 10.0 SLM, the mass flow rate of methyltrichlorosilane is 0.9 g / min, and the mass flow rate of the Y / Zr-beta-diketonate mixed solution is linearly reduced from 0.15 g / min to 0.05 g / min;

[0048] A5, an Ar atmosphere is reserved, the flow rate is 5 SLM, and the temperature is reduced to room temperature at a rate of 5℃ / min.

[0049] In a second aspect, the present application provides a CVD growth type high-temperature-resistant silicon carbide prepared by the preparation method in the first aspect.

[0050] Compared with the prior art, the present application has the following beneficial effects: by constructing a layered structure, the inherent brittleness of traditional silicon carbide is effectively overcome, the failure mode of the material is changed from brittle fracture to ductile failure, and the structural reliability is greatly improved; secondly, the self-healing system of the surface layer endows the material with active damage repair capability, can block microcracks in a wide temperature range, and significantly prolongs the high-temperature service life; and the pulse gradient process used in the present application realizes seamless gradient transition of each functional zone, eliminates the weak interface of traditional composite materials, and ensures the structural integrity and excellent comprehensive performance of the whole. DETAILED DESCRIPTION

[0051] The technical solutions of the present application will be described in detail below in combination with specific embodiments. The embodiments described herein are specific specific embodiments of the present application, which are used to illustrate the concept of the present application; these descriptions are all explanatory and exemplary, and should not be understood as limiting the embodiments of the present application and the protection scope of the present application. In addition to the embodiments described herein, those skilled in the art can also employ other technical solutions that are obvious based on the disclosure of the claims and the specification of the present application, which include technical solutions that make any obvious substitutions and modifications to the embodiments described herein.

[0052] The chemical reagents used in the embodiments and comparative examples of the present application are all commercially available goods and are not subjected to any further purification treatment.

[0053] Embodiment 1

[0054] The present embodiment provides a CVD growth type high-temperature-resistant silicon carbide and a preparation method thereof, and the preparation method specifically comprises the following steps:

[0055] S1, 21.0 g of polycarbosilane was dispersed in 200 mL of anhydrous xylene under argon atmosphere, the temperature was adjusted to 85°C and 1.0 g of divinylbenzene was added, the temperature was adjusted to 135°C and the reaction was refluxed for 7 h, after the reaction was completed, the temperature was cooled to room temperature and transferred to an ice water bath, 105 mL of 1M borane-tetrahydrofuran was added, after the addition was completed, the ice water bath was removed, the reaction was stirred at room temperature for 2.5 h and then the temperature was increased to 75°C and the reaction was continued for 12.5 h, after the reaction was completed, the temperature was cooled to room temperature and the reaction solution was added to 1000 mL of anhydrous n-hexane, the precipitate was collected, washed and dried to obtain modified polycarbosilane, and then the modified polycarbosilane was dispersed in anhydrous toluene to obtain a 10 wt.% end-vinyl boron modified polycarbosilane solution;

[0056] S2, 1.95 g of lithium aluminum hydride was dispersed in 200 mL of anhydrous ether under argon atmosphere, the ice water bath was adjusted to 14.5 g of tert-butylamine, the ice bath was removed and the reaction was stirred at room temperature for 12.5 h, then the temperature was adjusted to 34°C and the reaction was refluxed for 24.5 h, the insoluble matter was removed by filtration, and then distilled under reduced pressure, washed with anhydrous n-hexane, recrystallized, and dried under vacuum to obtain aluminum-nitrogen heterocyclic cubane;

[0057] S3, 3.25 g of yttrium tris(2,2,6,6-tetramethyl-3,5-heptanedionate) and 1.55 g of zirconium tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionate) were dispersed in 200 mL of a mixed solvent, and ultrasonic treatment was performed for 35 min to obtain a Y / Zr-β-diketonate mixed solution, the mixed solvent being a mixed solvent of tetrahydrofuran and n-butanol, the volume ratio of tetrahydrofuran to n-butanol in the mixed solvent being 4:1;

[0058] S4, after the graphite plate was washed and dried, it was placed in a horizontal hot-wall CVD reaction furnace, vacuum was applied and argon was introduced, methylchlorosilane, end-vinyl boron modified polycarbosilane solution, aluminum-nitrogen heterocyclic cubane and Y / Zr-β-diketonate mixed solution were used for deposition process on the graphite plate, after the deposition was completed, CVD grown high-temperature resistant silicon carbide was obtained.

[0059] The deposition process includes the following steps:

[0060] A0, at a rate of 10°C / min, under a H2 / Ar mixed gas atmosphere of 20 kPa, the flow rate was 10 SLM / 10 SLM, the temperature was increased from room temperature to 1310°C, and the temperature was maintained for 35 min, then the temperature was decreased to 1250°C at a rate of 20°C / min and stabilized;

[0061] The deposition stage pressure was 4 kPa;

[0062] A1, the duration of A1 is from the 0th minute to the 45th minute after the deposition stage, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane source bottle temperature is 80°C, delivered by mass flow controller, the set flow rate corresponds to a mass flow rate of 0.9 g / min, the end-vinyl boron-modified polycarbosilane solution mass flow rate is 0.1 g / min;

[0063] A2, the duration of A2 is from the 45th minute to the 285th minute after the deposition stage, a PLC pulse program is used, 480 pulse cycles are performed, each cycle is 30 seconds, the parameters in the Nth cycle, N = 1 ~ 480, four sub-stages are performed in each cycle, the sub-stages include B1, B2, B3 and B4;

[0064] B1, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 1.2 g / min, the aluminum-nitrogen heterocubane is heated to sublimation at 130°C, the Ar carrier gas is 20 SCCM, corresponding to a mass flow rate of 0.008 g / min, the end-vinyl boron-modified polycarbosilane solution is closed, the duration t1 = 14 + 6 × [(N-1) / 479] seconds; 2

[0065] B2, the H2 / Ar purge is retained, the flow rate is 5 SLM / 5 SLM, the duration is 1 s;

[0066] B3, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 0.6 g / min, the end-vinyl boron-modified polycarbosilane solution mass flow rate is 0.1 g / min, the duration t2 = 14 - 6 × [(N-1) / 479] seconds;

[0067] B4, the H2 / Ar purge is retained, the flow rate is 5 SLM / 5 SLM, the duration is 1 s;

[0068] A3, the duration of A3 is from the 285th minute to the 295th minute after the deposition stage, the H2 flow rate is retained, the flow rate is 2 SLM, the temperature is 1250°C, the pressure is 4 kPa, the duration is from the 285th minute to the 295th minute after the deposition stage;

[0069] A4, the duration of A4 is from the 295th minute to the 355th minute after the deposition stage, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 0.9 g / min, the Y / Zr-β-diketonate mixed solution mass flow rate is linearly reduced from 0.15 g / min to 0.05 g / min;

[0070] A5, the Ar atmosphere is retained, the flow rate is 5 SLM, the temperature is reduced to room temperature at a rate of 5°C / min.

[0071] Example 2 ​

[0072] The embodiment provides a CVD growth type high-temperature-resistant silicon carbide and a preparation method thereof, and the preparation method specifically comprises the following steps:

[0073] S1, 20.5 g of polycarbosilane is dispersed in 200 mL of anhydrous xylene in an argon atmosphere, the temperature is adjusted to 82 DEG C, 1.3 g of divinylbenzene is added, the temperature is adjusted to 132 DEG C, and the reaction is refluxed for 6.5 h; after the reaction is completed, the temperature is cooled to room temperature and transferred to an ice water bath, 102 mL of 1M borane-tetrahydrofuran is added, after the addition is completed, the ice water bath is removed, the reaction is stirred at room temperature for 2.2 h, and then the temperature is increased to 72 DEG C and the reaction is continued for 12.2 h; after the reaction is completed, the temperature is cooled to room temperature, and the reaction solution is added to 1000 mL of anhydrous n-hexane; the precipitate is collected, washed and dried to obtain modified polycarbosilane; and then the modified polycarbosilane is dispersed in anhydrous toluene to obtain a 10wt.% end-vinyl boron modified polycarbosilane solution;

[0074] S2, 1.92 g of lithium aluminum hydride is dispersed in 200 mL of anhydrous ether in an argon atmosphere, and 14.2 g of tert-butylamine is added under ice water bath conditions; the ice bath is removed and the reaction is stirred at room temperature for 12.8 h; then the temperature is adjusted to 35 DEG C, the reaction is refluxed for 24.2 h, and the insoluble matter is removed by filtration; after vacuum distillation, anhydrous n-hexane washing and recrystallization, aluminum-nitrogen heterocyclic cubane is obtained by vacuum drying;

[0075] S3, 3.22 g of yttrium tris (2, 2, 6, 6-tetramethyl-3, 5-heptanedionate) and 1.58 g of zirconium tetra (2, 2, 6, 6-tetramethyl-3, 5-heptanedionate) are dispersed in 200 mL of a mixed solvent to obtain a Y / Zr-beta-diketonate mixed solution by ultrasonic treatment for 38 min, wherein the mixed solvent is a mixed solvent of tetrahydrofuran and n-butanol, and the volume ratio of tetrahydrofuran to n-butanol in the mixed solvent is 4:1;

[0076] S4, after the graphite plate is washed and dried, it is placed in a horizontal hot-wall CVD reaction furnace, vacuumized and replaced with argon, and a deposition process is performed on the graphite plate by using methylchlorosilane, end-vinyl boron modified polycarbosilane solution, aluminum-nitrogen heterocyclic cubane and Y / Zr-beta-diketonate mixed solution; after the deposition is completed, a CVD growth type high-temperature-resistant silicon carbide is obtained.

[0077] The deposition process comprises the following steps:

[0078] A0, at a rate of 10 DEG C / min, under a H2 / Ar mixed gas atmosphere of 20 kPa, and with a flow rate of 10 SLM / 10 SLM, the temperature is increased from room temperature to 1305 DEG C and kept for 38 min, then decreased to 1250 DEG C at a rate of 20 DEG C / min and stabilized;

[0079] The pressure in the deposition stage is 4 kPa;

[0080] A1, the duration of A1 is from the 0th minute to the 45th minute after the deposition stage, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane source bottle temperature is 80°C, delivered by mass flow controller, the set flow rate corresponds to a mass flow rate of 0.9 g / min, the end-vinyl boron-modified polycarbosilane solution mass flow rate is 0.1 g / min;

[0081] A2, the duration of A2 is from the 45th minute to the 285th minute after the deposition stage, a PLC pulse program is used, 480 pulse cycles are performed, each cycle is 30 seconds, the parameters in the Nth cycle, N = 1 ~ 480, four sub-stages are performed in each cycle, the sub-stages include B1, B2, B3 and B4;

[0082] B1, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 1.2 g / min, the aluminum-nitrogen heterocubane is heated to sublimation at 130°C, the Ar carrier gas is 20 SCCM, corresponding to a mass flow rate of 0.008 g / min, the end-vinyl boron-modified polycarbosilane solution is closed, the duration t1 = 14 + 6 × [(N-1) / 479] seconds; 2

[0083] B2, the H2 / Ar purge is retained, the flow rate is 5 SLM / 5 SLM, the duration is 1 s;

[0084] B3, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 0.6 g / min, the end-vinyl boron-modified polycarbosilane solution mass flow rate is 0.1 g / min, the duration t2 = 14 - 6 × [(N-1) / 479] seconds;

[0085] B4, the H2 / Ar purge is retained, the flow rate is 5 SLM / 5 SLM, the duration is 1 s;

[0086] A3, the duration of A3 is from the 285th minute to the 295th minute after the deposition stage, the H2 is retained, the flow rate is 2 SLM, the temperature is 1250°C, and the pressure is 4 kPa;

[0087] A4, the duration of A4 is from the 295th minute to the 355th minute after the deposition stage, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 0.9 g / min, and the Y / Zr-β-diketonate mixed solution mass flow rate is linearly reduced from 0.15 g / min to 0.05 g / min;

[0088] A5, the Ar atmosphere is retained, the flow rate is 5 SLM, and the temperature is reduced to room temperature at a rate of 5°C / min.

[0089] Example 3

[0090] ​The embodiment provides a CVD growth type high-temperature-resistant silicon carbide and a preparation method thereof, and the preparation method specifically comprises the following steps.

[0091] S1, 21.8 g of polycarbosilane is dispersed in 200 mL of anhydrous xylene in an argon atmosphere, the temperature is adjusted to 88 DEG C, 0.9 g of divinylbenzene is added, the temperature is adjusted to 138 DEG C, and the reaction is refluxed for 7.8 h; after the reaction is completed, the temperature is cooled to room temperature and transferred to an ice water bath, 108 mL of 1M borane-tetrahydrofuran is added, after the addition is completed, the ice water bath is removed, the reaction is stirred at room temperature for 2.8 h, and then the temperature is increased to 78 DEG C and the reaction is continued for 12.8 h; after the reaction is completed, the temperature is cooled to room temperature, and the reaction solution is added to 1000 mL of anhydrous n-hexane; the precipitate is collected, washed and dried to obtain modified polycarbosilane; and then the modified polycarbosilane is dispersed in anhydrous toluene to obtain a 10wt.% vinyl-terminated boron-modified polycarbosilane solution;

[0092] S2, 1.98 g of lithium aluminum hydride is dispersed in 200 mL of anhydrous ether in an argon atmosphere, and 14.8 g of tert-butylamine is added under ice water bath conditions; the ice bath is removed and the reaction is stirred at room temperature for 12.2 h; then the temperature is adjusted to 33.5 DEG C and the reaction is refluxed for 24.8 h; the insoluble matter is removed by filtration, and the product is vacuum dried after distillation under reduced pressure, anhydrous n-hexane washing and recrystallization to obtain aluminum-nitrogen heterocyclic cubane;

[0093] S3, 3.28 g of yttrium tris(2,2,6,6-tetramethyl-3,5-heptanedionate) and 1.52 g of zirconium tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionate) are dispersed in 200 mL of a mixed solvent to obtain a Y / Zr-beta-diketonate mixed solution, the mixed solvent is a mixed solvent of tetrahydrofuran and n-butanol, and the volume ratio of tetrahydrofuran to n-butanol in the mixed solvent is 4:1;

[0094] S4, after the graphite plate is washed and dried, the graphite plate is placed in a horizontal hot-wall CVD reaction furnace, vacuumized and replaced with argon, and a deposition process is performed on the graphite plate by using methylchlorosilane, the vinyl-terminated boron-modified polycarbosilane solution, the aluminum-nitrogen heterocyclic cubane and the Y / Zr-beta-diketonate mixed solution; after the deposition is completed, a CVD growth type high-temperature-resistant silicon carbide is obtained.

[0095] The deposition process is as follows:

[0096] A0, at a rate of 10 DEG C / min, under a H2 / Ar atmosphere with a flow rate of 10 SLM / 10 SLM, the temperature is increased from room temperature to 1318 DEG C and kept for 32 min, and then the temperature is decreased to 1250 DEG C at a rate of 20 DEG C / min and stabilized;

[0097] The pressure in the deposition stage is 4 kPa;

[0098] A1, the duration of A1 is from the 0th minute to the 45th minute after the deposition stage, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane source bottle temperature is 80°C, delivered by mass flow controller, the set flow rate corresponds to a mass flow rate of 0.9 g / min, the end-vinyl boron-modified polycarbosilane solution mass flow rate is 0.1 g / min;

[0099] A2, the duration of A2 is from the 45th minute to the 285th minute after the deposition stage, a PLC pulse program is used, 480 pulse cycles are performed, each cycle is 30 seconds, the parameters in the Nth cycle, N = 1 ~ 480, four sub-stages are performed in each cycle, the sub-stages include B1, B2, B3 and B4;

[0100] B1, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 1.2 g / min, the aluminum-nitrogen heterocubane is heated to sublimation at 130°C, the Ar carrier gas is 20 SCCM, corresponding to a mass flow rate of 0.008 g / min, the end-vinyl boron-modified polycarbosilane solution is closed, the duration t1 = 14 + 6 × [(N-1) / 479] seconds; 2

[0101] B2, the H2 / Ar purge is retained, the flow rate is 5 SLM / 5 SLM, the duration is 1 s;

[0102] B3, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 0.6 g / min, the end-vinyl boron-modified polycarbosilane solution mass flow rate is 0.1 g / min, the duration t2 = 14 - 6 × [(N-1) / 479] seconds;

[0103] B4, the H2 / Ar purge is retained, the flow rate is 5 SLM / 5 SLM, the duration is 1 s;

[0104] A3, the duration of A3 is from the 285th minute to the 295th minute after the deposition stage, the H2 flow rate is retained, the flow rate is 2 SLM, the temperature is 1250°C, and the pressure is 4 kPa;

[0105] A4, the duration of A4 is from the 295th minute to the 355th minute after the deposition stage, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 0.9 g / min, the Y / Zr-β-diketonate mixed solution mass flow rate is linearly reduced from 0.15 g / min to 0.05 g / min, and the duration is from the 295th minute to the 355th minute after the deposition stage;

[0106] A5, the Ar atmosphere is retained, the flow rate is 5 SLM, and the temperature is reduced to room temperature at a rate of 5°C / min.

[0107] Example 4 ​

[0108] The embodiment provides a CVD growth type high-temperature-resistant silicon carbide and a preparation method thereof, and the preparation method specifically comprises the following steps:

[0109] S1, 21.5 g of polycarbosilane is dispersed in 200 mL of anhydrous xylene in an argon atmosphere, the temperature is adjusted to 86 DEG C, 1.2 g of divinylbenzene is added, the temperature is adjusted to 136 DEG C, and reflux reaction is carried out for 7.2 h; after the reaction is completed, the temperature is cooled to room temperature and transferred to an ice water bath, 106 mL of 1M borane-tetrahydrofuran is added, after the addition is completed, the ice water bath is removed, the reaction is stirred at room temperature for 2.6 h, and then the temperature is increased to 76 DEG C and the reaction is continuously carried out for 12.6 h; after the reaction is completed, the temperature is cooled to room temperature, and the reaction solution is added to 1000 mL of anhydrous n-hexane; the precipitate is collected, washed and dried to obtain modified polycarbosilane; and then the modified polycarbosilane is dispersed in anhydrous toluene to obtain a 10wt.% end-vinyl boron modified polycarbosilane solution;

[0110] S2, 1.96 g of lithium aluminum hydride is dispersed in 200 mL of anhydrous ether in an argon atmosphere, an ice water bath is used, 14.6 g of tert-butylamine is added, the ice bath is removed and stirring is carried out at room temperature for 12.6 h, the temperature is adjusted to 34.5 DEG C, and reflux reaction is carried out for 24.6 h; the insoluble matter is removed by filtration, vacuum distillation, anhydrous n-hexane washing, recrystallization and vacuum drying to obtain aluminum-nitrogen heterocyclic cubane;

[0111] S3, 3.26 g of yttrium tris (2, 2, 6, 6-tetramethyl-3, 5-heptanedionate) and 1.56 g of zirconium tetra (2, 2, 6, 6-tetramethyl-3, 5-heptanedionate) are dispersed in 200 mL of a mixed solvent to obtain a Y / Zr-beta-diketonate mixed solution, the mixed solvent is a mixed solvent of tetrahydrofuran and n-butanol, and the volume ratio of tetrahydrofuran to n-butanol in the mixed solvent is 4:1;

[0112] S4, after the graphite plate is washed and dried, the graphite plate is placed in a horizontal hot-wall CVD reaction furnace, vacuum pumping and argon replacement are carried out, methylchlorosilane, end-vinyl boron modified polycarbosilane solution, aluminum-nitrogen heterocyclic cubane and Y / Zr-beta-diketonate mixed solution are used for a deposition process on the graphite plate, and after the deposition is completed, a CVD growth type high-temperature-resistant silicon carbide is obtained.

[0113] The deposition process is as follows:

[0114] A0, at a rate of 10 DEG C / min, under a H2 / Ar atmosphere of 20 kPa, the flow rate is 10 SLM / 10 SLM, the temperature is increased from room temperature to 1315 DEG C and kept for 36 min, the temperature is decreased to 1250 DEG C at a rate of 20 DEG C / min and stabilized;

[0115] The deposition stage pressure is 4 kPa;

[0116] A1, the duration of A1 is from the 0th minute to the 45th minute after the deposition stage, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane source bottle temperature is 80°C, delivered by mass flow controller, the set flow rate corresponds to a mass flow rate of 0.9 g / min, the end-vinyl boron-modified polycarbosilane solution mass flow rate is 0.1 g / min;

[0117] A2, the duration of A2 is from the 45th minute to the 285th minute after the deposition stage, a PLC pulse program is used, 480 pulse cycles are performed, each cycle is 30 seconds, the parameters in the Nth cycle, N = 1 ~ 480, four sub-stages are performed in each cycle, the sub-stages include B1, B2, B3 and B4;

[0118] B1, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 1.2 g / min, the aluminum-nitrogen heterocubane is heated to sublimation at 130°C, the Ar carrier gas is 20 SCCM, corresponding to a mass flow rate of 0.008 g / min, the end-vinyl boron-modified polycarbosilane solution is closed, the duration t1 = 14 + 6 × [(N-1) / 479] seconds; 2

[0119] B2, the H2 / Ar purge is retained, the flow rate is 5 SLM / 5 SLM, the duration is 1 s;

[0120] B3, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 0.6 g / min, the end-vinyl boron-modified polycarbosilane solution mass flow rate is 0.1 g / min, the duration t2 = 14 - 6 × [(N-1) / 479] seconds;

[0121] B4, the H2 / Ar purge is retained, the flow rate is 5 SLM / 5 SLM, the duration is 1 s;

[0122] A3, the duration of A3 is from the 285th minute to the 295th minute after the deposition stage, the H2 flow rate is retained, the flow rate is 2 SLM, the temperature is 1250°C, and the pressure is 4 kPa;

[0123] A4, the duration of A4 is from the 295th minute to the 355th minute after the deposition stage, the H2 flow rate is 10.0 SLM, the methyltrichlorosilane mass flow rate is 0.9 g / min, and the Y / Zr-β-diketonate mixed solution mass flow rate is linearly reduced from 0.15 g / min to 0.05 g / min;

[0124] A5, the Ar atmosphere is retained, the flow rate is 5 SLM, and the temperature is reduced to room temperature at a rate of 5°C / min.

[0125] Comparative Example 1

[0126] ​This comparative example provides a CVD-grown high-temperature-resistant silicon carbide and a method for preparing the same, which is different from Example 1 in that no end-vinyl boron-modified polycarbosilane solution is used in S4, and other process parameters and operating conditions are exactly the same as in Example 1.

[0127] Comparative Example 2

[0128] This comparative example provides a CVD-grown high-temperature-resistant silicon carbide and a method for preparing the same, which is different from Example 1 in that no aluminum-nitrogen heterocubane is used in S4, and other process parameters and operating conditions are exactly the same as in Example 1.

[0129] Comparative Example 3

[0130] This comparative example provides a CVD-grown high-temperature-resistant silicon carbide and a method for preparing the same, which is different from Example 1 in that no Y / Zr-β-diketonate mixed solution is used in S4, and other process parameters and operating conditions are exactly the same as in Example 1.

[0131] Comparative Example 4

[0132] This comparative example provides a CVD-grown high-temperature-resistant silicon carbide and a method for preparing the same, which is different from Example 1 in that no pulse gradient program is used in S4, and a continuous co-deposition method is used to continuously pass equal amounts of methyltrichlorosilane, end-vinyl boron-modified polycarbosilane solution, aluminum-nitrogen heterocubane, and Y / Zr-β-diketonate mixed solution into the reaction chamber, and other process parameters and operating conditions are exactly the same as in Example 1.

[0133] The CVD-grown high-temperature-resistant silicon carbides prepared in Examples 1-4 and Comparative Examples 1-4 above are subjected to performance testing, and the testing methods are as follows:

[0134] The test method for fracture toughness is ASTM C1421-16 (Single-Edge Precracked Beam, SEPB).

[0135] Strength degradation rate test method: according to ASTM C1161 standard, the material to be tested is processed into a rectangular beam-shaped sample (3mm x 4mm x >36mm), the width and thickness of all samples (group A and group B) are measured to 0.01mm. The initial mass of the group B sample is accurately weighed, and for the group A sample, the room temperature bending strength test is carried out according to the ASTM C1161 standard, the fracture load is recorded, the original average strength of the material is calculated and recorded, the group B sample is placed on the clean alumina support of the high temperature furnace, and the temperature is raised to 1500℃ at 10℃ / min, and the temperature is kept for 72 hours at this temperature, after the end of the holding, the furnace is cooled to room temperature, the group B sample is taken out, and the final mass is accurately weighed, and for the group B sample after high temperature oxidation, the room temperature bending strength test is carried out according to the ASTM C1161 standard, and the average strength of the sample after oxidation is calculated and recorded. The mass change per unit area (Am / A) of the group B sample is calculated, which is used to evaluate the macroscopic oxidation degree, and the strength retention rate = final mass / initial mass x 100%.

[0136] The test results are shown in Table 1.

[0137] Table 1 Test results of CVD growth type high temperature resistant silicon carbide prepared by example 1- example 4 and comparative example 1- comparative example 4

[0138]

[0139] From Table 1, compared with example 1, the fracture toughness of comparative example 1 decreases, the mass change per unit area increases, and the strength retention rate decreases; the fracture toughness of comparative example 2 decreases, the mass change per unit area increases, and the strength retention rate decreases; the fracture toughness of comparative example 3 decreases, the mass change per unit area increases, and the strength retention rate decreases; the fracture toughness of comparative example 4 decreases, the mass change per unit area increases, and the strength retention rate decreases.

[0140] The end-vinyl boron-modified polycarbosilane solution is not used in Comparative Example 1, and the nanocomposite tough layer formed in situ after the solution is dissolved, which contains boron carbide nanowhiskers and turbostratic graphite carbon phases, is an important structure for toughening. The overall material is more sensitive to thermal shock due to the lack of toughness, and thus the fracture toughness of Comparative Example 1 decreases, the mass change per unit area increases, and the strength retention rate decreases. In Comparative Example 2, aluminum-nitrogen heterocyclic cubane is not used. The aluminum-nitrogen heterocyclic cubane cage structure is stable in thermodynamics, and thus the thermal stability of Comparative Example 2 decreases, the fracture toughness decreases, the mass change per unit area increases, and the strength retention rate decreases. In Comparative Example 3, Y / Zr-β-diketonate mixed solution is not used. The material surface lacks the mechanism of actively forming a dense yttrium zirconium silicate protective film, and is passively oxidized to form a silica protective layer at high temperatures. The silica protective layer reacts with silicon carbide to generate volatile SiO gas, and thus becomes unstable and porous, and thus the fracture toughness decreases, the mass change per unit area increases, and the strength retention rate decreases. In Comparative Example 4, all precursors are introduced at the same time in the continuous co-deposition mode, resulting in a random and dispersed composite structure in the substrate, rather than an ordered layered structure, and thus the fracture toughness decreases, the mass change per unit area increases, and the strength retention rate decreases.

[0141] The above merely provides a specific implementation of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily conceived by those skilled in the art, and all such changes and replacements fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for producing a high-temperature-resistant silicon carbide of the CVD growth type, characterized in that The preparation method comprises: S1, dispersing polycarbosilane in anhydrous xylene, adding divinylbenzene to reflux, adding borane-tetrahydrofuran to react, obtaining modified polycarbosilane, dispersing the modified polycarbosilane in anhydrous toluene to obtain a terminal vinyl boron modified polycarbosilane solution; S2, dispersing lithium aluminum hydride in anhydrous diethyl ether, adding tert-butylamine to obtain aluminum-nitrogen heterocyclic cubane; S3, dispersing yttrium tris(2,2,6,6-tetramethyl-3,5-heptanedionate) and zirconium tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionate) in a mixed solvent, ultrasonic treatment to obtain a Y / Zr-β-diketonate mixed solution, the mixed solvent being a mixed solvent of tetrahydrofuran and n-butanol; S4, after the graphite plate is cleaned and dried, it is placed in a horizontal hot-wall CVD reaction furnace, vacuumized and replaced by argon, methylchlorosilane, terminal vinyl boron modified polycarbosilane solution, aluminum-nitrogen heterocyclic cubane and Y / Zr-β-diketonate mixed solution are used for deposition program of the graphite plate, after deposition, a CVD grown high-temperature-resistant silicon carbide is obtained.

2. The method of claim 1, wherein the CVD growth type high-temperature-resistant silicon carbide is prepared by the steps of: preparing a silicon carbide powder; mixing the silicon carbide powder with a binder to form a mixture; and compressing the mixture to form a compact. In S1: The mass-volume ratio of the polycarbosilane, anhydrous xylene, divinylbenzene, borane-tetrahydrofuran is (20-22) g:200 mL:(0.8-1.5) g:(100-110) mL.

3. The method of claim 1, wherein the CVD growth type high-temperature-resistant silicon carbide is prepared by the steps of: preparing a silicon carbide powder; mixing the silicon carbide powder with a binder to form a mixture; and compressing the mixture to form a compact. In S1: The number average molecular weight of the polycarbosilane is 1100-2000.

4. The method of claim 1, wherein the CVD growth of high-temperature- resistant silicon carbide is prepared by the steps of: In S1: The mass fraction of the terminal vinyl boron modified polycarbosilane solution is 10wt.%.

5. The method of claim 1, wherein the CVD growth of high-temperature- resistant silicon carbide is prepared by the steps of: In S2: The mass-volume ratio of the lithium aluminum hydride, anhydrous diethyl ether and tert-butylamine is (1.9-2.0) g:200 mL:(14-15) g.

6. The method of claim 1, wherein the CVD growth of high-temperature- resistant silicon carbide is prepared by the steps of: In S3: The mass-volume ratio of the yttrium tris(2,2,6,6-tetramethyl-3,5-heptanedionate), (1.5-1.6g) tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionate) and the mixed solvent is (3.2-3.3) g:(1.5-1.6) g:200 mL.

7. The method of claim 1, wherein the CVD growth of high-temperature- resistant silicon carbide is prepared by the steps of: In S3: The volume ratio of tetrahydrofuran to n-butanol in the mixed solvent is 4:

1.

8. The method of claim 1, wherein the CVD growth of high-temperature- resistant silicon carbide is prepared by the steps of: In S4: The deposition program comprises the following steps: A0, at a rate of 10℃ / min, under a H2 / Ar mixed gas atmosphere of 20kPa, the flow rate is 10SLM / 10SLM, from room temperature to 1300-1320℃, keep warm for 30-40min, cool down to 1250℃ at a rate of 20℃ / min and stabilize; The deposition stage pressure is 4kPa; A1, the time length of A1 is from the 0th minute to the 45th minute after the deposition stage starts, the H2 flow rate is 10.0SLM, the methyltrichlorosilane source bottle temperature is 80℃, it is transported by a mass flow controller, the set flow rate corresponds to a mass flow rate of 0.9g / min, the mass flow rate of the terminal vinyl boron modified polycarbosilane solution is 0.1g / min; A2, the duration of A2 is from the 45th minute to the 285th minute after the deposition stage, using the PLC pulse program, 480 pulse cycles are performed, 30 seconds per cycle, the parameters in the Nth cycle, N = 1-480, four sub-stages are performed in each cycle, the sub-stages include B1, B2, B3 and B4; B1, H2 flow of 10.0 SLM, methyltrichlorosilane mass flow rate of 1.2 g / min, 130 °C heated aluminum-nitrogen heterocubane to sublimate, Ar carrier gas 20 SCCM, corresponding mass flow rate 0.008 g / min, end-vinyl boron-modified polycarbosilane solution off, time duration t1=14+6x[(N-1) / 479] seconds 2 seconds B2, H2 / Ar purge is retained, the flow rate is 5 SLM / 5 SLM, the duration is 1 s; B3, the flow rate of H2 is 10.0 SLM, the mass flow rate of methyltrichlorosilane is 0.6 g / min, the mass flow rate of end-vinyl boron-modified polycarbosilane solution is 0.1 g / min, the duration t2 = 14-6×[(N-1) / 479] seconds; B4, H2 / Ar purge is retained, the flow rate is 5 SLM / 5 SLM, the duration is 1 s; A3, the duration of A3 is from the 285th minute to the 295th minute after the deposition stage, H2 is retained, the flow rate is 2 SLM, the temperature is 1250℃, and the pressure is 4 kPa; A4, the duration of A4 is from the 295th minute to the 355th minute after the deposition stage, the flow rate of H2 is 10.0 SLM, the mass flow rate of methyltrichlorosilane is 0.9 g / min, and the mass flow rate of Y / Zr-β-diketonate mixed solution is linearly reduced from 0.15 g / min to 0.05 g / min; A5, Ar atmosphere is retained, the flow rate is 5 SLM, and the temperature is reduced to room temperature at a rate of 5℃ / min.

9. The CVD-grown high-temperature-resistant silicon carbide prepared by the method according to any one of claims 1-8.

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