Polycarbosilane fiber cross-linking device and cross-linking method thereof

Abstract

The invention discloses a polycarbosilane fiber cross-linking device, which comprises a gas inlet system, a cross-linking and heat treatment system and a control system, the gas inlet system comprises a gas inlet chamber, the gas inlet chamber is communicated with a plurality of gas inlet channels, a plurality of groups of first automatic heaters are arranged in the gas inlet chamber, the cross-linking and heat treatment system comprises a closed treatment chamber, and the closed treatment chamber is communicated with the gas inlet channels. An air outlet channel is communicated between the air inlet chamber and the closed treatment chamber, a treatment platform for placing polycarbosilane fiber bundles is arranged in the closed treatment chamber, a plurality of groups of second automatic heaters are arranged on the inner wall of the closed treatment chamber, and a microwave resonant coupling emitter is further arranged on the inner wall of the closed treatment chamber. The invention further discloses a cross-linking method of the polycarbosilane fiber, rapid, efficient and controllable cross-linking of the polycarbosilane fiber can be achieved at the low temperature, meanwhile, the use of a chemical cross-linking agent is avoided, and pollution to the environment is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of fiber crosslinking treatment, and in particular to a crosslinking device and a crosslinking method for polycarbosilane fibers. Background Art

[0002] As an important class of polymer compounds, polycarbosilane plays a core role in the preparation of high-performance ceramic materials, especially the preparation of silicon carbide (SiC) fibers. In traditional processes, polycarbosilane is converted into high-performance SiC fibers through melt spinning, infusibility treatment, pyrolysis and final calcination. Among them, infusibility treatment is a key step to ensure that the fiber maintains its shape during the subsequent high-temperature pyrolysis process.

[0003] At present, the infusibility treatment of polycarbosilane fibers mainly adopts thermal oxidation, electron beam irradiation crosslinking and chemical vapor phase infusibility, among which: 1. Thermal oxidation is a commonly used infusible treatment method, but it introduces a large amount of oxygen, which is not conducive to the high-temperature performance of the final ceramic fiber. For example, the existing silicon carbide fiber is treated with air infusibility, which introduces a certain amount (10 wt %~20 wt %), which seriously affects the high-temperature mechanical properties of the fiber; 2. Electron beam irradiation or gamma ray irradiation can achieve infusibility in an inert atmosphere and produce ceramic fibers with low oxygen content. However, this method requires huge initial investment in equipment and requires a high dose for infusibility treatment, which leads to rising costs. At the same time, conventional irradiation processing is difficult, which further increases the manufacturing cost of the fiber and reduces the production efficiency of polycarbosilane fiber. 3. Chemical vapor infusibility method, such as the oxygen-free infusibility method of polycarbosilane fiber, has the advantages of avoiding the introduction of oxygen, achieving the infusibility of polycarbosilane fiber at a lower temperature, uniform active atmosphere air flow field, and axial heating to make the fibers in different positions heated evenly. However, its reaction conditions are demanding. On the one hand, the treatment process is relatively complicated, involving the use and control of chemical gases, which increases the difficulty and complexity of the process. On the other hand, the emission of chemical gases may have adverse effects on the environment and has poor environmental protection. In addition, in the infusibility treatment of polycarbosilane and other fibers, the unsaturated hydrocarbon vapor used for chemical vapor crosslinking is toxic and harmful, and takes a long time, which is not conducive to large-scale production and application. Summary of the invention

[0004] The object of the present invention is to provide a cross-linking device and a cross-linking method for polycarbosilane fibers, which can achieve rapid, efficient and controllable cross-linking of polycarbosilane fibers at low temperatures, while avoiding the use of chemical cross-linking agents and reducing pollution to the environment.

[0005] In order to achieve the above object, the solution of the present invention is: A crosslinking device for polycarbosilane fibers, comprising an air intake system, a crosslinking and heat treatment system and a control system, wherein the air intake system comprises an air intake chamber, the air intake chamber is connected to a plurality of air intake channels, a plurality of groups of first automatic heaters are arranged in the air intake chamber, the crosslinking and heat treatment system comprises a closed treatment chamber, an air outlet channel is connected between the air intake chamber and the closed treatment chamber, a treatment platform for placing polycarbosilane fiber bundles is arranged in the closed treatment chamber, a plurality of groups of second automatic heaters distributed around the treatment platform are arranged on the inner wall of the closed treatment chamber, a plurality of microwave resonant coupling transmitters distributed around the treatment platform are also arranged on the inner wall of the closed treatment chamber, a plurality of gas outlets connected to a vacuum treatment system are arranged on the closed treatment chamber, an exhaust valve connected to the outside is also arranged on the closed treatment chamber, and the control system is respectively controlled and connected to the first automatic heater, the second automatic heater and the microwave resonant coupling transmitter.

[0006] Each group of the second automatic heaters and each of the microwave resonance coupling launchers are alternately distributed.

[0007] The vacuum processing system is a vacuum pump.

[0008] The air inlet chamber and the closed processing chamber are respectively provided with temperature sensors connected to the control system.

[0009] A flow valve is provided on each of the air inlet passages, and the flow valve is controllably connected to the control system.

[0010] A feeding port is provided at one end of the closed processing chamber, a sealing valve cover is provided at a position of the closed processing chamber corresponding to the feeding port, the inner surface of the sealing valve cover is fixedly connected to the processing platform, a sliding frame is provided on the outer surface of the sealing valve cover, the closed processing chamber is fixed on the fixed frame, and the sliding frame is slidably connected to the fixed frame, and a slide rail that slidably cooperates with the processing platform is also provided in the closed processing chamber.

[0011] A cross-linking method for polycarbosilane fibers comprises the following steps: Step 1: first place the polycarbosilane fiber bundle on the processing platform, then send it into a closed processing chamber, evacuate it, and then pass the air source into the closed processing chamber through the air inlet chamber; Step 2, then controlling the discharge power and discharge time of the microwave resonant coupled transmitter to perform plasma crosslinking treatment, and then controlling the heating rate, heating temperature and time of the second automatic heater to perform thermal crosslinking treatment on the polycarbosilane fiber bundle; Step 3: Finally, the heating rate, heating temperature and time of the second automatic heater are controlled to post-treat the polycarbosilane fiber bundles so that the fiber molecules are completely transformed into an infusible mesh structure.

[0012] In step 1, the gas source is one or a mixture of helium, argon and nitrogen, and the flow rate of the gas source is 50-150 mL / min.

[0013] In step 2, the discharge power is controlled according to the thickness of the polycarbosilane fiber bundle, the discharge power is 50~300 W, the discharge time is 15~30 minutes, the heating rate is 1~3℃ / min, the insulation temperature is 180~220℃, and the insulation time is 3~6 h.

[0014] In step 3, the heating rate is 1-3°C / min, the insulation temperature is 340-360°C, and the insulation time is 25-35 min.

[0015] After adopting the above technical solution, the cross-linking device and cross-linking method of polycarbosilane fiber of the present invention have the following advantages: 1. Using microwave resonance coupling technology, plasma is generated in a closed process, so that polycarbosilane molecules undergo cross-linking reaction under the action of plasma. High-energy particles in the plasma (such as electrons, ions, free radicals, etc.) can interact with polycarbosilane molecules, causing the chemical bonds on the molecular chain to break and recombine, thereby forming a cross-linked structure. Microwave resonance coupling technology improves energy conversion efficiency. Compared with the traditional method of generating plasma by exciting gas molecules with high-frequency electric fields, energy consumption is reduced by about 30% to 50%; 2. Compared with the traditional high-temperature cross-linking method, the plasma-assisted in-situ cross-linking method is carried out at a lower temperature, which avoids the damage of high temperature to the performance of polycarbosilane materials and also reduces energy consumption; and can achieve cross-linking of polycarbosilane in a short time, thus improving production efficiency; 3. The gas source is realized to flow and mix efficiently in the air inlet chamber, ensuring that the plasma is evenly distributed in the entire closed processing chamber, thus improving the processing efficiency and quality; 3. By adjusting the discharge power and discharge time of the microwave resonant coupled transmitter and controlling the heating temperature and time of the second automatic heater, the degree of in-situ cross-linking reaction and the performance of the polycarbosilane material can be accurately controlled to meet the needs of different application fields; 5. Combining thermal crosslinking and plasma-assisted crosslinking, plasma-assisted crosslinking mainly forms a crosslinking layer on the surface of polycarbosilane filaments, while thermal crosslinking further consolidates and improves the crosslinking structure from the inside. The combination of the two can make polycarbosilane filaments form a more uniform and dense three-dimensional network structure, effectively improving the overall stability and performance of the fiber; 6. No chemical cross-linking agent is required, thus avoiding the environmental pollution and influence on material properties caused by chemical cross-linking agents; 7. The control system monitors the state of plasma in real time and automatically adjusts the discharge power and gas flow rate to ensure that the cross-linking reaction runs stably and efficiently, so as to achieve the controllability of the cross-linking reaction; 8. After the combined cross-linking treatment, the polycarbosilane fiber bundle has good thermal stability, mechanical properties and chemical stability. Under high temperature environment, it can maintain good shape and structural integrity, withstand higher tensile stress, and its tolerance to chemical reagents is greatly improved, which can meet more demanding use conditions; 9. The cross-linking device and the cross-linking method are simple and suitable for large-scale production.

[0016] Furthermore, factors such as the processing time and power of the microwave resonant coupled transmitter will affect the cross-linking effect. If the processing time is too short, the degree of cross-linking will be insufficient; if the processing time is too long, it may lead to excessive cross-linking of the fiber surface, affecting the performance of the fiber. The power determines the energy and number of active particles, which in turn affects the rate and degree of the cross-linking reaction. For polycarbosilane fibers with a smaller diameter, the discharge power can be controlled between 50 and 150 W. For thicker polycarbosilane fibers, the discharge power can be appropriately increased to 150 to 300 W.

[0017] Furthermore, the heating temperature, heating time and heating rate are key factors affecting the thermal cross-linking effect. If the temperature is too low or the holding time is too short, the cross-linking reaction is incomplete and the ideal infusibility effect cannot be achieved. If the temperature is too high or the holding time is too long, the polycarbosilane filament may be over-cross-linked, making it brittle and reducing its flexibility. In addition, a too fast heating rate may cause thermal stress inside the polycarbosilane filament, affecting its structure and performance.

[0018] Furthermore, plasmas generated by different gas sources have different chemical activities. For example, oxygen plasma has a stronger oxidizing property and can introduce more oxygen elements to participate in the cross-linking reaction, while argon plasma is relatively inert and mainly induces cross-linking through physical action. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a cross-linking device of polycarbosilane fiber of the present invention; Figure 2 It is a schematic diagram of the top view of the air intake system and the cross-linking and heat treatment system in the present invention; Figure 3 It is a side view structural schematic diagram of the cross-linking and heat treatment system in the present invention; Figure 4 This is an electron microscope image of silicon carbide fiber obtained by post-processing the polycarbosilane fiber in Example 2; Figure 5 This is an electron microscope image of the silicon carbide fiber obtained by post-processing the polycarbosilane fiber in Example 3.

[0020] In the figure: Intake chamber 1; intake passage 11; Flow valve 12; first automatic heater 2; Sealed processing chamber 3; slide rail 31; A second automatic heater 32; a microwave resonance coupled transmitter 33; Vacuum pump 34; exhaust valve 35; Processing platform 4; Sliding rack 5; Pulley 51; Fixed frame 6; Guide rail 61; air outlet channel 7; Control system 8. DETAILED DESCRIPTION

[0021] In order to further explain the technical solution of the present invention, the present invention is described in detail below through specific embodiments.

[0022] Embodiment 1 A cross-linking device for polycarbosilane fibers, such as Figure 1-Figure 3 As shown, it includes an air intake system, a cross-linking and heat treatment system and a control system. The air intake system includes an air intake chamber 1. The air intake chamber 1 is connected to a plurality of air intake channels 11 for introducing an air source. A flow valve 12 is provided on each air intake channel 11.

[0023] A plurality of groups of first automatic heaters 2 are arranged in the air intake chamber 1. Each group of first automatic heaters 2 is arranged axially around the inner wall of the air intake chamber 1. The first automatic heaters 2 are heating rods or heating tubes.

[0024] The cross-linking and heat treatment system includes a closed processing chamber 3, one end of which is provided with a feeding port, a sealing valve cover is provided at a position corresponding to the feeding port of the closed processing chamber 3, a processing platform 4 for placing polycarbosilane fiber bundles is provided in the closed processing chamber 3, the inner surface of the sealing valve cover is fixedly connected to one end of the processing platform 4, and a sliding frame 5 is provided on the outer surface of the sealing valve cover. The closed processing chamber 3 is fixed on a fixed frame 6, and pulleys 51 are symmetrically provided on both sides of the lower end of the sliding frame 5, and guide rails 61 that slide with each pulley 51 are provided on both sides of the fixed frame 6, so that the sliding frame 5 is slidably connected with the fixed frame 6, and a slide rail 31 that slides with the processing platform 4 is also provided in the closed processing chamber 3. This arrangement enables the processing platform 4 to slide relative to the closed processing chamber 3, making it more convenient to load and unload materials.

[0025] An air outlet channel 7 is connected between the air inlet chamber 1 and the closed processing chamber 3. The air outlet channel 7 is used to pass the gas source into the closed processing chamber 3. The inner wall of the closed processing chamber 3 is provided with a plurality of groups of second automatic heaters 32 distributed around the processing platform. The second automatic heaters 32 are heating rods or heating tubes. The inner wall of the closed processing chamber 3 is also provided with a plurality of microwave resonant coupling transmitters 33 distributed around the processing platform 4. The microwave resonant coupling transmitters 33 are well-known devices in the art. The groups of second automatic heaters 32 and the microwave resonant coupling transmitters 33 are alternately distributed at intervals.

[0026] The closed processing chamber 3 is provided with a plurality of gas outlets connected to the vacuum processing system. Specifically, there are two gas outlets, which are respectively provided at the other end of the closed processing chamber 3. The vacuum processing system is a vacuum pump 34. The closed processing chamber 3 is also provided with an exhaust valve 35 connected to the outside. The control system 8 is used to control the switches of each flow valve 12, the first automatic heater 2, the second automatic heater 32, and the microwave resonance coupling transmitter 33. The control system 8 is a well-known PLC control system, and the control method is also a well-known control method in the art.

[0027] Temperature sensors (not shown in the figure) connected to the control system 8 are respectively provided in the air intake chamber 1 and the closed processing chamber 3, so as to achieve accurate control of the temperature in the air intake chamber 1 and the closed processing chamber 3.

[0028] The terms "first", "second" and the like in the description and claims of the present invention are used to distinguish different objects rather than to distinguish a specific order.

[0029] Embodiment 2 A cross-linking method for polycarbosilane fibers comprises the following steps: Step 1: First, place a polycarbosilane fiber bundle with a diameter of 12-13 μm (thinner) on the processing platform 4, and then send it into the closed processing chamber 3, use the vacuum pump 34 to evacuate, and then pass helium into the closed processing chamber 3 through the outlet channel 7 of the inlet chamber 1, and control the flow rate of helium to 50 mL / min through the flow valve 12; Step 2, then controlling the discharge power and discharge time of the microwave resonant coupled transmitter 33, wherein the discharge power is 50 W, the discharge time is 15 minutes, and plasma cross-linking treatment is performed, and then controlling the heating rate, heating temperature and time of the second automatic heater 32, wherein the heating rate is 3°C / min, the holding temperature is 180°C, and the holding time is 5 hours, and the polycarbosilane fiber bundle is subjected to thermal cross-linking treatment; Step 3, finally control the heating rate, heating temperature and time of the second automatic heater 32, wherein the heating rate is 2°C / min, the holding temperature is 340°C, and the holding time is 25 min, and the polycarbosilane fiber bundle is post-processed to completely transform the fiber molecules into an infusible network structure, and the gas in the closed processing chamber 3 is released through the exhaust valve 35.

[0030] In step 1, the heating temperature and time of the first automatic heater 2 are controlled. The first automatic heater 2 is mainly used to control the temperature of the heated helium. The insulation temperature is kept consistent with the second automatic heater 32 to reduce the heat taken away by the gas temperature difference entering the closed processing chamber 3 and causing fluctuations in fiber properties.

[0031] Embodiment 3 A cross-linking method for polycarbosilane fibers comprises the following steps: Step 1: First, place a polycarbosilane fiber bundle with a diameter of 15-16 μm (thicker) on the processing platform 4, and then send it into the closed processing chamber 3, use the vacuum pump 34 to evacuate, and then pass helium into the closed processing chamber 3 through the outlet channel 7 of the inlet chamber 1, and control the flow rate of helium to 150 mL / min through the flow valve 12; Step 2, then controlling the discharge power and discharge time of the microwave resonant coupled transmitter 33, wherein the discharge power is 300 W, the discharge time is 20 minutes, and plasma cross-linking treatment is performed, and then controlling the heating rate, heating temperature and time of the second automatic heater 32, wherein the heating rate is 3°C / min, the holding temperature is 210°C, and the holding time is 5 hours, and the polycarbosilane fiber bundle is subjected to thermal cross-linking treatment; Step 3, finally control the heating rate, heating temperature and time of the second automatic heater 32, wherein the heating rate is 2°C / min, the holding temperature is 360°C, and the holding time is 35 min, and post-process the polycarbosilane fiber bundles to completely transform the fiber molecules into an infusible network structure, and release the gas in the closed processing chamber 3 through the exhaust valve 35.

[0032] In step 1, the heating temperature and time of the first automatic heater 2 are controlled. The first automatic heater 2 is mainly used to control the temperature of the heated helium. The insulation temperature is kept consistent with the second automatic heater 32 to reduce the heat taken away by the gas temperature difference entering the closed processing chamber 3 and causing fluctuations in fiber properties.

[0033] Performance Testing 1. Morphology of silicon carbide fiber The polycarbosilane cross-linked fibers obtained by cross-linking in Example 2 and Example 3 were converted into high-performance SiC fibers through steps such as hydrogen pyrolysis at 1250°C and high-temperature final calcination at 1600°C. The morphology of the silicon carbide fibers is as follows: Figure 4 and Figure 5 Its diameter is shown in Table 1.

[0034] Table 1 Single fiber diameter

[0035] The single fiber diameter of Example 2 is 10.8 μm. The relatively thin diameter gives the fiber an advantage in some specific applications. For example, when preparing high-performance composite materials, thinner fibers can be more evenly dispersed in the matrix, enhancing the overall performance of the material. At the same time, the smaller diameter may also make the fiber easier to use in some narrow spaces or in situations where there are strict requirements on material thickness. The single fiber diameter Cv is 6.75%, indicating that the consistency of the fiber diameter is good, which helps to ensure the stability and reliability of the material performance. In practical applications, the uniformity of fiber diameter is crucial to the control of product quality.

[0036] The single fiber diameter of Example 3 is 12.7 μm. A thicker diameter may have unique advantages in certain applications. For example, in situations where greater external forces need to be withstood or higher wear resistance is required, thicker diameter fibers can provide stronger load-bearing capacity and better durability. In addition, thicker fibers may be easier to handle during processing and handling, reducing production difficulties. The single fiber diameter Cv is 7.75%, which also shows good diameter consistency. This helps to ensure the performance stability of the fiber during use and reduce quality problems caused by diameter differences.

[0037] 2. Tensile performance test Table 2 Tensile properties test results

[0038] The tensile strength of the silicon carbide fiber processed by the cross-linking method reaches more than 2.8 GPa, and the tensile modulus is as high as 350 GPa. The fiber has excellent performance and broad application prospects.

[0039] 3. High temperature strength retention rate (1) Silicon carbide fiber obtained by processing in Example 2 Table 3 High temperature strength retention rate of silicon carbide fiber

[0040] Under different temperature and atmosphere conditions, the silicon carbide fibers corresponding to Example 2 all showed relatively stable performance. For example, under air-1300℃-2000s conditions, the tensile strength was 2.57 GPa, and the high-temperature strength retention rate was 82.9%; under Ar-1300℃-2000s, the tensile strength was 2.72 GPa, and the high-temperature strength retention rate was 87.8%. This shows that whether in air or argon atmosphere, at a relatively low temperature (1300℃), the fiber can maintain its strength well, reflecting high stability.

[0041] As the temperature rises, although the strength decreases, the decrease is reasonable. For example, under the conditions of air-1400℃-2000s, the tensile strength is 1.74 GPa, and the high-temperature strength retention rate is 56.1%; under Ar-1400℃-2000s, the tensile strength is 1.97 GPa, and the high-temperature strength retention rate is 63.5%. Even at higher temperatures, the fiber can still maintain a certain strength, showing its adaptability in different temperature ranges and excellent high-temperature resistance, which further strongly proves that the fiber has extremely broad prospects for use in the field of high-temperature resistant structural parts.

[0042] (2) Silicon carbide fiber obtained by processing in Example 3 Table 4 High temperature strength retention rate of silicon carbide fiber

[0043] Example 3 Silicon carbide fiber exhibits good strength retention at high temperatures. Under the conditions of air-1300℃-2000s, the tensile strength is 2.35 GPa, and the high-temperature strength retention rate is 81.0%; under Ar-1300℃-2000s, the tensile strength is 2.43 GPa, and the high-temperature strength retention rate is 83.7%. This shows that even in a high-temperature environment, the fiber can maintain a certain strength, showing its good high-temperature resistance.

[0044] As the temperature rises, although the strength decreases, it can still be maintained at a certain level. For example, under the conditions of air-1400℃-2000s, the tensile strength is 1.63 GPa, and the high-temperature strength retention rate is 56.2%; under Ar-1400℃-2000s, the tensile strength is 1.85 GPa, and the high-temperature strength retention rate is 63.8%. This shows that the fiber has a certain stability at different temperatures and can adapt to high-temperature changes within a certain range.

[0045] With its excellent high-temperature performance, the silicon carbide fiber processed by the cross-linking method of Example 2 and Implementation Case 3 has broad application prospects in high-precision fields such as aerospace. In these fields, the high-temperature resistance of the material is extremely high, and the fiber can maintain a high strength in a high-temperature environment, providing a reliable material choice for key parts such as thermal protection systems and engine components of spacecraft.

[0046] In other industrial fields, such as metallurgy and chemical industry, there are also high requirements for high temperature resistance and strength stability of materials. The silicon carbide fiber produced by the present invention can meet these requirements, provide high-performance material solutions for the manufacture of components of high-temperature equipment, and improve the service life and production efficiency of equipment.

[0047] The above embodiments and drawings do not limit the product form and style of the present invention. Any appropriate changes or modifications made by ordinary technicians in the relevant technical field should be deemed to be within the patent scope of the present invention.

Claims

1. A crosslinking device for polycarbosilane fibers, comprising an air intake system, a crosslinking and heat treatment system and a control system, characterized in that: The air intake system includes an air intake chamber, which is connected to a plurality of air intake channels, and a plurality of groups of first automatic heaters are arranged in the air intake chamber. The crosslinking and heat treatment system includes a closed treatment chamber, and an air outlet channel is connected between the air intake chamber and the closed treatment chamber. A treatment platform for placing polycarbosilane fiber bundles is arranged in the closed treatment chamber, and a plurality of groups of second automatic heaters distributed around the treatment platform are arranged on the inner wall of the closed treatment chamber. A plurality of microwave resonant coupling transmitters distributed around the treatment platform are also arranged on the inner wall of the closed treatment chamber. A plurality of gas outlets connected to the vacuum treatment system are arranged on the closed treatment chamber, and an exhaust valve connected to the outside is also arranged on the closed treatment chamber. The control system is respectively controlled and connected to the first automatic heater, the second automatic heater and the microwave resonant coupling transmitter.

2. A cross-linking device for polycarbosilane fibers according to claim 1, characterized in that: Each group of the second automatic heaters and each of the microwave resonance coupling launchers are alternately distributed.

3. A cross-linking device for polycarbosilane fibers according to claim 1, characterized in that: The vacuum processing system is a vacuum pump.

4. The cross-linking device for polycarbosilane fibers according to claim 1, characterized in that: The air inlet chamber and the closed processing chamber are respectively provided with temperature sensors connected to the control system.

5. The cross-linking device for polycarbosilane fibers according to claim 1, characterized in that: A flow valve is provided on each of the air inlet passages, and the flow valve is controllably connected to the control system.

6. The cross-linking device for polycarbosilane fibers according to claim 1, characterized in that: A feeding port is provided at one end of the closed processing chamber, a sealing valve cover is provided at a position of the closed processing chamber corresponding to the feeding port, the inner surface of the sealing valve cover is fixedly connected to the processing platform, a sliding frame is provided on the outer surface of the sealing valve cover, the closed processing chamber is fixed on the fixed frame, and the sliding frame is slidably connected to the fixed frame, and a slide rail that slidably cooperates with the processing platform is also provided in the closed processing chamber.

7. A cross-linking method using the cross-linking device for polycarbosilane fibers according to claim 1, characterized in that: The following steps are involved: Step 1: first place the polycarbosilane fiber bundle on the processing platform, then send it into a closed processing chamber, evacuate it, and then pass the air source into the closed processing chamber through the air inlet chamber; Step 2, then controlling the discharge power and discharge time of the microwave resonant coupled transmitter to perform plasma crosslinking treatment, and then controlling the heating rate, heating temperature and time of the second automatic heater to perform thermal crosslinking treatment on the polycarbosilane fiber bundle; Step 3: Finally, the heating rate, heating temperature and time of the second automatic heater are controlled to post-treat the polycarbosilane fiber bundles so that the fiber molecules are completely transformed into an infusible mesh structure.

8. A method for crosslinking polycarbosilane fibers according to claim 7, characterized in that: In step 1, the gas source is one or a mixture of helium, argon and nitrogen, and the flow rate of the gas source is 50-150 mL / min.

9. The cross-linking method of polycarbosilane fiber according to claim 7, characterized in that: In step 2, the discharge power is controlled according to the thickness of the polycarbosilane fiber bundle, the discharge power is 50~300 W, the discharge time is 15~30 minutes, the heating rate is 1~3℃ / min, the insulation temperature is 180~220℃, and the insulation time is 3~6h.

10. The cross-linking method of polycarbosilane fiber according to claim 7, characterized in that: In step 3, the heating rate is 1-3°C / min, the insulation temperature is 340-360°C, and the insulation time is 25-35 min.

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