Preparation method of short-period ultrahigh-temperature modified C / SiC fastener

Abstract

The application discloses a short-period ultrahigh-temperature modified C / SiC fastener preparation method and belongs to the technical field of ceramic matrix composite materials. The preparation method comprises the following steps: first, performing CVI deposition on a preform; then, introducing ultrahigh-temperature powder slurry into the preform through suction filtration; then, introducing in-situ grown SiC nanowires through a PIP process; then, introducing polycarbosilane through the PIP process; and finally, finishing and forming to obtain the product. Through optimization of the process flow, the application can strengthen high-temperature stability, reduce high-temperature long-time processes, realize rapid densification of the fastener, significantly reduce the preparation cost, realize the organic combination of low production cost, high preparation efficiency, high-temperature stability and excellent mechanical properties of the fastener, and has wide application prospect and practical value. The application solves the problems of long preparation period, high cost, great processing difficulty and easy defects of the existing C / SiC fastener.

Description

Technical Field

[0001] This invention relates to the field of ceramic matrix composites technology, and more specifically to a method for preparing short-cycle ultra-high temperature modified C / SiC fasteners. Background Technology

[0002] Carbon fiber reinforced silicon carbide (C / SiC) composites possess excellent properties such as high-temperature oxidation resistance, high specific strength, high specific stiffness, and low coefficient of thermal expansion, making them a core candidate material for key structural components in extreme high-temperature environments in aerospace, defense, and other fields. Bolts, as core components of mechanical connections, must withstand temperatures above 1200 ℃ and complex stresses for extended periods in scenarios such as aerospace vehicle thermal protection systems and hot-end components of aero-engines. Traditional high-temperature alloy bolts have a temperature resistance limit of less than 1100 ℃, and graphite and C / C composites have poor oxidation resistance, failing to meet the service requirements of high-end equipment. Therefore, the research and application of C / SiC bolts has become crucial for overcoming technological bottlenecks.

[0003] Currently, the fabrication of C / SiC fasteners mainly relies on traditional processes such as chemical vapor infiltration (CVI) and precursor impregnation pyrolysis (PIP). CVI processes are time-consuming and costly, making mass production difficult. PIP processes require multiple impregnation-pyrolysis cycles, increasing both cost and time, and easily leading to defects such as chipped threads and missing corners in bolt threads. Furthermore, the high hardness and brittleness of C / SiC composites make thread machining challenging; traditional machining methods are inefficient and cause severe tool wear, further increasing fabrication costs and limiting their engineering application and large-scale deployment.

[0004] With the rapid development of aerospace, energy, and other fields, the demand for C / SiC fasteners is increasing, while higher requirements are being placed on their manufacturing costs and production efficiency. Developing a short-cycle C / SiC bolt manufacturing process that guarantees product performance has become a research hotspot and urgent need in the materials science field. While existing research attempts to optimize process parameters and improve processing methods to reduce costs, a mature and efficient industrial-scale manufacturing technology has not yet been established. Therefore, research on short-cycle, ultra-high temperature modified C / SiC bolt manufacturing methods, breaking through process bottlenecks and optimizing the manufacturing process, has significant theoretical and practical value for promoting the engineering application of C / SiC composite materials and improving the localization level of core components for high-end equipment. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a short-cycle ultra-high temperature modified C / SiC fastener preparation method, thereby solving the problems of long preparation cycle, high cost, difficult processing, and easy defects in existing C / SiC fasteners.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides a method for preparing short-cycle ultra-high temperature modified C / SiC fasteners, comprising the following steps: S1, Interface Deposition: CVI deposition was performed on the preform to obtain preform I; S2, Slurry filtration: The ultra-high temperature powder slurry was introduced into preform I by vacuum filtration and dried to obtain preform II; S3 and SiC nanowire PIP fabrication: Preform II was subjected to vacuum impregnation and pressure impregnation in SiC nanowire precursor, and then subjected to high temperature treatment to obtain preform III for growing SiC nanowires. S4, Polycarbosilane PIP processing: Preform III was subjected to vacuum impregnation and pressure impregnation in polycarbosilane in sequence, followed by drying and high-temperature pyrolysis to obtain preform IV; S5, Finishing: Preform IV was machined and shaped according to the fastener dimensions to obtain short-cycle ultra-high temperature modified C / SiC fasteners.

[0007] The beneficial effects of this invention are as follows: This invention prepares ultra-high temperature modified C / SiC fasteners through the CVI+PIP process. By optimizing the process flow, it enhances high-temperature stability while reducing long-time high-temperature processes, achieving rapid densification of fasteners and significantly reducing preparation costs. It achieves an organic combination of fasteners with low production costs, high preparation efficiency, high-temperature stability, and excellent mechanical properties, and has broad application prospects and practical value.

[0008] Furthermore, the preform in S1 is a needle-punched preform.

[0009] Furthermore, the CVI deposition conditions in S1 were: propylene flow rate of 0.1~20 L / min, argon flow rate of 0.5~21 L / min, deposition time of 10~80 h, and temperature of 400~1100 ℃.

[0010] Furthermore, the number of interface deposition furnace cycles in S1 is 2 to 8.

[0011] Furthermore, the interface in S1 is subjected to high-temperature treatment after deposition.

[0012] Furthermore, the high-temperature treatment in S1 is carried out at a temperature of 1500~2000 ℃ for a time of 1~5 h.

[0013] Furthermore, in S2, the preform I is pre-processed into a cylinder with a diameter of 10~20 mm.

[0014] Furthermore, the ultra-high temperature powder in S2 includes at least one of ZrB2, HfB2, ZrC, and HfC.

[0015] Furthermore, the volume fraction of the ultra-high temperature powder slurry in S2 is 2%~30%.

[0016] Furthermore, the drying temperature in S2 is 50~300 ℃, and the drying time is 5~12 h.

[0017] Furthermore, the SiC nanowire precursor in S3 is composed of solid polycarbosilane, hyperbranched polycarbosilane, organic solvent and catalyst.

[0018] Furthermore, the total mass fraction of polycarbosilane is 1% to 50%.

[0019] Furthermore, the mass ratio of solid polycarbosilane to hyperbranched polycarbosilane is 0.1 to 100.

[0020] Furthermore, the organic solvent includes at least one of ethanol, toluene, and xylene.

[0021] Furthermore, the catalyst comprises ferrocene or nickel ferrocene, with a mass of 1% to 10% of the total polycarbosilane mass.

[0022] Furthermore, the vacuum impregnation time in S3 is 10~45 min.

[0023] Furthermore, the pressure for impregnation in S3 is 0.2~1.5 MPa, and the time is 10~45 min.

[0024] Furthermore, the high-temperature treatment in S3 is carried out at a temperature of 1200~1600 ℃ for a time of 1~5 h.

[0025] Furthermore, the SiC nanowire PIP processing in S3 is repeated 1 to 5 times.

[0026] Furthermore, the vacuum impregnation time in S4 is 10~45 min.

[0027] Furthermore, the pressure for impregnation in S4 is 0.2~1.5 MPa, and the time is 10~45 min.

[0028] Furthermore, the drying temperature in S4 is 25~100 ℃, and the drying time is 0.5~15 h.

[0029] Furthermore, the high-temperature pyrolysis temperature in S4 is 700~1600 ℃, and the time is 0.5~5 h.

[0030] Furthermore, the polycarbosilane PIP processing in S4 is repeated 3 to 8 times.

[0031] In a second aspect, the present invention provides a short-cycle ultra-high temperature modified C / SiC fastener, which is prepared by the above-described preparation method.

[0032] The present invention has the following beneficial effects: 1. This invention optimizes the number of cycles by combining CVI with PIP process, thereby achieving rapid densification of fasteners, reducing high-temperature and long-time processes, and significantly reducing manufacturing costs.

[0033] 2. This invention enhances the high-temperature stability while improving the quality and mechanical properties of fasteners. The shear strength (double shear) of the ultra-high temperature modified M8 bolt prepared by this process is >100 MPa.

[0034] 3. This invention has low requirements for equipment and processing conditions, can effectively utilize PCS pyrolysis products to grow SiC nanowires, and the method is safer and more reliable than chemical vapor deposition. Attached Figure Description

[0035] Figure 1 A process roadmap for the preparation of short-cycle ultra-high temperature modified C / SiC fasteners; Figure 2 The image shows the cross-sectional morphology of prefabricated body III obtained in Example 1, where scale bar a is 50 μm and scale bar b is 5 μm. Figure 3 The load-displacement curves of the short-cycle ultra-high temperature modified C / SiC fasteners prepared in Example 1 are shown, where a is the load-displacement curve of the shear test and b is the load-displacement curve of the tensile test. Detailed Implementation

[0036] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0037] Example 1: A method for preparing short-cycle ultra-high temperature modified C / SiC fasteners (process flow diagram as follows) Figure 1 (As shown), including the following steps: S1, Shaping and Interface Deposition: In this embodiment, a needle-punched preform is used. The preform that has been shaped is subjected to CVI deposition at a gas flow rate of 10 L / min for propylene and 10 L / min for argon. The deposition time is 45 h and the temperature is 750 ℃. According to actual requirements, after 5 heats of deposition, it is subjected to high-temperature treatment at 1750 ℃ ​​for 3 h to obtain a needle-punched preform I with a thick interface layer.

[0038] S2, Processing: According to the bolt size requirements, the needle-punched preform I is pre-processed into a cylinder I with a diameter of 15 mm.

[0039] S3. Slurry filtration: First, ultra-high temperature powder HfC is mixed with deionized water to prepare an ultra-high temperature powder slurry with a volume fraction of 15%. Then, the ultra-high temperature powder slurry is introduced into the interior of cylinder I by vacuum filtration. Finally, cylinder I is dried overnight in an oven at 200 °C to obtain cylinder II containing ultra-high temperature powder.

[0040] S4, PIP-SiC nanowires: The SiC nanowire precursor is introduced into cylinder II using a vacuum impregnation process, specifically including the following steps: S401, Preparation of SiC nanowire precursor: First, solid polycarbosilane, hyperbranched polycarbosilane, and ethanol were weighed separately to prepare a polycarbosilane solution with a mass fraction of 25%, wherein the mass ratio of solid polycarbosilane to hyperbranched polycarbosilane was 1:1. Then, ferrocene catalyst with a mass fraction of 5% of the total polycarbosilane was weighed and added to the obtained polycarbosilane solution. After ultrasonic dispersion for 20 min, the mixture was stirred continuously for 90 min until the catalyst was completely dissolved, thus obtaining the SiC nanowire precursor.

[0041] S402, Vacuum Impregnation: The cylinder II was completely immersed in the SiC nanowire precursor and vacuum impregnated for 30 min.

[0042] S403, Pressure Impregnation: The vacuum-impregnated cylinder II was immersed in the SiC nanowire precursor and then transferred to a pressure vessel for pressure impregnation at a pressure of 1 MPa for 30 min, resulting in cylinder III containing the SiC nanowire precursor.

[0043] S404, High-temperature treatment: Cylinder III was placed in a crucible and then placed in a tube furnace. Argon gas was introduced and heat-treated at 1400 °C for 3 h to obtain cylinder IV with grown SiC nanowires. Repeat the S402-S404 process three times to obtain a cylindrical V.

[0044] S5, PIP-PCS: The process of introducing polycarbosilane (PCS) into cylinder V using a vacuum impregnation technique includes the following steps: S501, Vacuuming: Suspend the cylinder V above the PCS without immersing it, and evacuate for 30 minutes.

[0045] S502, Vacuum Impregnation: The cylinder V was completely immersed in PCS and vacuum impregnated for 30 min.

[0046] S503, Pressure Impregnation: The cylinder V obtained after vacuum impregnation was immersed in PCS and then transferred to a pressure tank for pressurized impregnation at a pressure of 1 MPa for 30 min.

[0047] S504, Drying: The sample obtained after pressure impregnation was transferred to an oven at 60 °C to slowly evaporate the solvent for 10 h, resulting in a cylindrical VI containing PCS.

[0048] S505, pyrolysis: The obtained cylinder VI was placed in a vacuum pyrolysis furnace and pyrolyzed at 1050 °C for 3 h to obtain cylinder VII; Repeat the S501-S505 machining process 5 times to obtain cylinder VIII.

[0049] S6, Finishing The obtained cylindrical VIII is processed and shaped according to the fastener dimensions to obtain a short-cycle ultra-high temperature modified C / SiC M8 bolt.

[0050] Example 2: A method for preparing short-cycle ultra-high temperature modified C / SiC fasteners (process flow diagram as follows) Figure 1 (As shown), including the following steps: S1, Shaping and Interface Deposition: In this embodiment, a needle-punched preform is used. The preform that has been shaped is subjected to CVI deposition at a gas flow rate of 5 L / min for propylene and 15 L / min for argon. The deposition time is 60 h and the temperature is 1000 ℃. According to actual requirements, after 8 heats of deposition, it is subjected to high-temperature treatment at 1750 ℃ ​​for 3 h to obtain a needle-punched preform I with a thick interface layer.

[0051] S2, Processing: According to the bolt size requirements, the needle-punched preform I is pre-processed into a cylinder I with a diameter of 10 mm.

[0052] S3. Slurry filtration: First, ultra-high temperature powder HfB2 is mixed with deionized water to prepare an ultra-high temperature powder slurry with a volume fraction of 20%. Then, the ultra-high temperature powder slurry is introduced into the interior of cylinder I by vacuum filtration. Finally, cylinder I is dried in an oven at 100 °C overnight to obtain cylinder II containing ultra-high temperature powder.

[0053] S4, PIP-SiC nanowires: The SiC nanowire precursor is introduced into cylinder II using a vacuum impregnation process, specifically including the following steps: S401, Preparation of SiC nanowire precursor: First, solid polycarbosilane, hyperbranched polycarbosilane, and ethanol were weighed separately to prepare a polycarbosilane solution with a mass fraction of 30%, wherein the mass ratio of solid polycarbosilane to hyperbranched polycarbosilane was 10:1. Then, ferrocene catalyst with a mass of 5% of the total polycarbosilane mass was weighed and added to the obtained polycarbosilane solution. After ultrasonic dispersion for 20 min, the mixture was stirred continuously for 90 min until the catalyst was completely dissolved, thus obtaining the SiC nanowire precursor.

[0054] S402, Vacuum Impregnation: The cylinder II was completely immersed in the SiC nanowire precursor and vacuum impregnated for 40 min.

[0055] S403, Pressure Impregnation: The vacuum-impregnated cylinder II was immersed in the SiC nanowire precursor and then transferred to a pressure vessel for pressure impregnation at a pressure of 0.5 MPa for 40 min to obtain cylinder III containing the SiC nanowire precursor.

[0056] S404, High-temperature treatment: Cylinder III was placed in a crucible and then placed in a tube furnace. Argon gas was introduced and heat-treated at 1200 °C for 4 h to obtain cylinder IV with grown SiC nanowires. Repeat the S402-S404 process four times to obtain a cylindrical V.

[0057] S5, PIP-PCS: The process of introducing polycarbosilane (PCS) into cylinder V using a vacuum impregnation technique includes the following steps: S501, Vacuuming: The cylinder V is suspended above the PCS without being immersed, and a vacuum is applied for 40 minutes.

[0058] S502, Vacuum Impregnation: The cylinder V was completely immersed in PCS and vacuum impregnated for 40 min.

[0059] S503, Pressure Impregnation: The cylinder V obtained after vacuum impregnation was immersed in PCS and then transferred to a pressure tank for pressurized impregnation at a pressure of 0.5 MPa for 40 min.

[0060] S504, Drying: The sample obtained after pressure impregnation was transferred to an oven at 80 °C to slowly evaporate the solvent for 8 h, resulting in a cylindrical VI containing PCS.

[0061] S505, pyrolysis: The obtained cylinder VI was placed in a vacuum pyrolysis furnace and pyrolyzed at 1200 ℃ for 2 h to obtain cylinder VII; Repeat the S501-S505 machining process for 8 rounds to obtain cylinder VIII.

[0062] S6, Finishing The obtained cylindrical VIII is processed and shaped according to the fastener dimensions to obtain a short-cycle ultra-high temperature modified C / SiC M8 bolt.

[0063] Example 3: A method for preparing short-cycle ultra-high temperature modified C / SiC fasteners (process flow diagram as follows) Figure 1 (As shown), including the following steps: S1, Shaping and Interface Deposition: In this embodiment, a needle-punched preform is used. The preform that has been shaped is subjected to CVI deposition at a gas flow rate of 15 L / min for propylene and 5 L / min for argon. The deposition time is 30 h and the temperature is 650 ℃. According to actual requirements, after two deposition cycles, it is subjected to high-temperature treatment at 1750 ℃ ​​for 3 h to obtain a needle-punched preform I with a thick interface layer.

[0064] S2, Processing: According to the bolt size requirements, the needle-punched preform I is pre-processed into a cylinder I with a diameter of 20 mm.

[0065] S3. Slurry filtration: First, ultra-high temperature powder ZrC is mixed with deionized water to prepare an ultra-high temperature powder slurry with a volume fraction of 10%. Then, the ultra-high temperature powder slurry is introduced into the interior of cylinder I by vacuum filtration. Finally, cylinder I is dried overnight in an oven at 300 °C to obtain cylinder II containing ultra-high temperature powder.

[0066] S4, PIP-SiC nanowires: The SiC nanowire precursor is introduced into cylinder II using a vacuum impregnation process, specifically including the following steps: S401, Preparation of SiC nanowire precursor: First, solid polycarbosilane, hyperbranched polycarbosilane, and ethanol were weighed separately to prepare a polycarbosilane solution with a mass fraction of 20%, wherein the mass ratio of solid polycarbosilane to hyperbranched polycarbosilane was 1:10. Then, nickel-cerocenium catalyst with a mass of 5% of the total polycarbosilane mass was weighed and added to the obtained polycarbosilane solution. After ultrasonic dispersion for 20 min, the mixture was stirred continuously for 90 min until the catalyst was completely dissolved, thus obtaining the SiC nanowire precursor.

[0067] S402, Vacuum Impregnation: The cylinder II was completely immersed in the SiC nanowire precursor and vacuum impregnated for 20 min.

[0068] S403, Pressure Impregnation: The vacuum-impregnated cylinder II was immersed in the SiC nanowire precursor and then transferred to a pressure vessel for pressure impregnation at a pressure of 1.5 MPa for 20 min to obtain cylinder III containing the SiC nanowire precursor.

[0069] S404, High-temperature treatment: Cylinder III was placed in a crucible and then placed in a tube furnace. Argon gas was introduced and heat-treated at 1600 °C for 2 h to obtain cylinder IV with grown SiC nanowires. Repeat the S402-S404 process twice to obtain a cylindrical V.

[0070] S5, PIP-PCS: The process of introducing polycarbosilane (PCS) into cylinder V using a vacuum impregnation technique includes the following steps: S501, Vacuuming: Suspend cylinder V above PCS without immersing it, and evacuate for 20 minutes.

[0071] S502, Vacuum Impregnation: The cylinder V was completely immersed in PCS and vacuum impregnated for 20 min.

[0072] S503, Pressure Impregnation: The cylinder V obtained after vacuum impregnation was immersed in PCS and then transferred to a pressure tank for pressurized impregnation at a pressure of 1.5 MPa for 20 min.

[0073] S504, Drying: The sample obtained after pressure impregnation was transferred to an oven at 40°C to slowly evaporate the solvent for 12 hours, resulting in a cylindrical VI containing PCS.

[0074] S505, pyrolysis: The obtained cylinder VI was placed in a vacuum pyrolysis furnace and pyrolyzed at 950℃ for 4 h to obtain cylinder VII; Repeat the S501-S505 machining process three times to obtain cylinder VIII.

[0075] S6, Finishing The obtained cylindrical VIII is processed and shaped according to the fastener dimensions to obtain a short-cycle ultra-high temperature modified C / SiC M8 bolt.

[0076] Experimental Example 1: Performance Characterization The cross-sectional micromorphology of the cylindrical IV with grown SiC nanowires prepared in Example 1 was characterized, and the mechanical properties of the short-cycle ultra-high temperature modified C / SiC fastener prepared in Example 1 were characterized.

[0077] Experimental results are as follows Figure 2 and Figure 3 As shown.

[0078] like Figure 2 As shown, the cross-sectional morphology reveals that the cylindrical IV section prepared in Example 1 of this invention exhibits a clear SiC nanowire structure, indicating the successful preparation of in-situ grown SiC nanowires according to this invention. Figure 3 As shown, the short-cycle ultra-high temperature modified C / SiC fastener prepared in Example 1 of the present invention has excellent mechanical properties. The shear strength (double shear) of the obtained short-cycle ultra-high temperature modified C / SiC M8 bolt is >100 MPa. Under the premise of meeting the shear strength requirements of M8 bolt, the preparation process is greatly reduced, the production cost is reduced, and the high temperature resistance is improved.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing short-cycle ultra-high temperature modified C / SiC fasteners, characterized in that, Includes the following steps: S1, Interface Deposition: CVI deposition was performed on the preform to obtain preform I; S2, Slurry filtration: The ultra-high temperature powder slurry was introduced into preform I by vacuum filtration and dried to obtain preform II; S3 and SiC nanowire PIP fabrication: Preform II was subjected to vacuum impregnation and pressure impregnation in SiC nanowire precursor, and then subjected to high temperature treatment to obtain preform III for growing SiC nanowires. S4, Polycarbosilane PIP processing: Preform III was subjected to vacuum impregnation and pressure impregnation in polycarbosilane in sequence, followed by drying and high-temperature pyrolysis to obtain preform IV; S5, Finishing: Preform IV was machined and shaped according to the fastener dimensions to obtain short-cycle ultra-high temperature modified C / SiC fasteners.

2. The method for preparing short-cycle ultra-high temperature modified C / SiC fasteners according to claim 1, characterized in that, The preform in S1 is a needle-punched preform; The CVI deposition conditions are as follows: propylene flow rate of 0.1~20 L / min, argon flow rate of 0.5~21 L / min, deposition time of 10~80 h, and temperature of 400~1100 ℃.

3. The method for preparing short-cycle ultra-high temperature modified C / SiC fasteners according to claim 1, characterized in that, In S2, the preform I is pre-processed into a cylinder with a diameter of 10~20 mm.

4. The method for preparing short-cycle ultra-high temperature modified C / SiC fasteners according to claim 1, characterized in that, The ultra-high temperature powder in S2 includes at least one of ZrB2, HfB2, ZrC, and HfC; The volume fraction of ultra-high temperature powder slurry is 2%~30%; The drying temperature is 50~300 ℃, and the time is 5~12 h.

5. The method for preparing short-cycle ultra-high temperature modified C / SiC fasteners according to claim 1, characterized in that, The SiC nanowire precursor in S3 is composed of solid polycarbosilane, hyperbranched polycarbosilane, organic solvent and catalyst. The total mass fraction of polycarbosilane is 1% to 50%; The mass ratio of solid polycarbosilane to hyperbranched polycarbosilane is 0.1~100; Organic solvents include at least one of ethanol, toluene, and xylene; The catalyst includes ferrocene or nickel ferrocene, with a mass of 1% to 10% of the total polycarbosilane mass.

6. The method for preparing short-cycle ultra-high temperature modified C / SiC fasteners according to claim 1, characterized in that, The vacuum impregnation time in S3 is 10~45 min; The pressure for pressure impregnation is 0.2~1.5 MPa, and the time is 10~45 min; The high-temperature treatment is carried out at a temperature of 1200~1600 ℃ for 1~5 h.

7. The method for preparing short-cycle ultra-high temperature modified C / SiC fasteners according to claim 1, characterized in that, The SiC nanowire PIP processing in S3 is repeated 1 to 5 times.

8. The method for preparing short-cycle ultra-high temperature modified C / SiC fasteners according to claim 1, characterized in that, The vacuum impregnation time in S4 is 10~45 min; The pressure for pressure impregnation is 0.2~1.5 MPa, and the time is 10~45 min; The drying temperature is 25~100 ℃, and the time is 0.5~15 h; The high-temperature pyrolysis temperature is 700~1600 ℃, and the time is 0.5~5 h.

9. The method for preparing short-cycle ultra-high temperature modified C / SiC fasteners according to claim 1, characterized in that, The polycarbosilane PIP processing in S4 is repeated 3 to 8 times.

10. A short-cycle ultra-high temperature modified C / SiC fastener, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 9.

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