Polycarbosilane fiber crosslinking device

Abstract

The utility model discloses a polycarbosilane fiber cross-linking device, which comprises an air inlet system, a cross-linking and heat treatment system and a control system, the air inlet system comprises an air inlet chamber, the air inlet chamber is communicated with a plurality of air inlet channels, a plurality of groups of first automatic heaters are arranged in the air inlet chamber, and a plurality of groups of second automatic heaters are arranged in the air inlet chamber. The cross-linking and heat treatment system comprises a closed treatment chamber, a gas outlet channel is communicated between the gas inlet chamber and the closed treatment chamber, a treatment platform used 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 the second automatic heaters are communicated with the gas inlet chamber. A microwave resonant coupling emitter is also arranged on the inner wall of the closed treatment chamber. According to the crosslinking device for the polycarbosilane fibers, rapid, efficient and controllable crosslinking of the polycarbosilane fibers can be achieved at low temperature, meanwhile, chemical crosslinking agents are prevented from being used, and pollution to the environment is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of fiber crosslinking treatment, specifically relates to a kind of crosslinking device of polycarbosilane fiber. BACKGROUND

[0002] Polycarbosilane as an important class of high molecular compounds, in the preparation of high-performance ceramic materials occupies the core position, especially the preparation of silicon carbide (SiC) fiber. In traditional process, polycarbosilane is converted into high-performance SiC fiber through melt spinning, infusibilization treatment, pyrolysis and final firing etc. steps. Among them, infusibilization treatment is the key step to ensure the morphology of fiber in subsequent high-temperature pyrolysis process.

[0003] At present, the infusibilization treatment of polycarbosilane fiber mainly adopts thermal oxidation method, electron beam irradiation crosslinking and chemical vapor infusibilization etc. methods, wherein:

[0004] 1. Thermal oxidation method is a commonly used infusibilization 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 by air infusibilization, which introduces a certain amount (10 wt%~20 wt%) of oxygen into the fiber, which seriously affects the high-temperature mechanical properties of the fiber.

[0005] 2. Electron beam irradiation or γ ray irradiation realizes infusibilization in inert atmosphere, which can prepare ceramic fiber with lower oxygen content. However, this method requires huge initial investment in equipment, high dose for infusibilization treatment, which leads to rising cost. At the same time, conventional irradiation processing is difficult, which further increases the manufacturing cost of fiber and reduces the production efficiency of polycarbosilane fiber.

[0006] 3. Chemical vapor infusibilization method, such as oxygen-free infusibilization method of polycarbosilane fiber, has the advantages of avoiding the introduction of oxygen, realizing the infusibilization of polycarbosilane fiber at lower temperature, uniform active atmosphere flow field, uniform heating of fiber at different positions by axial heating etc. However, it requires high reaction conditions. On the one hand, the treatment process is complex, involving the use and control of chemical gas, which increases the difficulty and complexity of the process. On the other hand, the emission of chemical gas may have adverse effects on the environment, which is poor in environmental protection. In addition, the unsaturated hydrocarbon vapor used in chemical vapor crosslinking is toxic and harmful, which is not conducive to large-scale production and application. UTILITY MODEL CONTENTS

[0007] The utility model aims to provide a kind of crosslinking device of polycarbosilane fiber, which can realize rapid, efficient and controllable crosslinking of polycarbosilane fiber at low temperature, while avoiding the use of chemical crosslinking agent and reducing environmental pollution.

[0008] In order to achieve the above object, the utility model discloses a solution is:

[0009] A crosslinking device of polycarbosilane fiber, including air intake system, crosslinking and heat treatment system and control system, the air intake system includes air inlet chamber, a plurality of air inlet channels are communicated to the air inlet chamber, a plurality of sets of first automatic heater are arranged in the air inlet chamber, the crosslinking and heat treatment system includes sealed processing chamber, the air inlet chamber and the sealed processing chamber are communicated with the air outlet channel, the sealed processing chamber is provided with the processing platform for placing polycarbosilane fiber bundle silk, the inner wall of the sealed processing chamber is provided with a plurality of sets of second automatic heater that surrounds the processing platform distribution, the inner wall of the sealed processing chamber is also provided with a plurality of microwave resonance coupling transmitters that surround the processing platform distribution, a plurality of gas outlets are provided on the sealed processing chamber and are communicated with vacuum processing system, the sealed processing chamber is also provided with the exhaust valve and communicates with the outside, the control system is connected with the first automatic heater, second automatic heater and microwave resonance coupling transmitter control respectively.

[0010] Each set of second automatic heater and each microwave resonance coupling transmitter are spaced and are alternately distributed.

[0011] The vacuum processing system is a vacuum pump.

[0012] The air inlet chamber and the sealed processing chamber are respectively provided with temperature sensors connected with the control system.

[0013] Each air inlet channel is provided with a flow valve, and the flow valve is connected with the control system.

[0014] One end of the sealed processing chamber is provided with a material passing opening, and the sealed processing chamber is provided with a sealing valve cover corresponding to the material passing opening, the inner surface of the sealing valve cover is fixedly connected with the processing platform, the outer surface of the sealing valve cover is provided with a sliding frame, the sealed processing chamber is fixed on a fixed frame, and the sliding frame is slidingly connected with the fixed frame, and the sealed processing chamber is also provided with a sliding rail slidingly matched with the processing platform.

[0015] After the above technical scheme is adopted, the crosslinking device of polycarbosilane fiber has the following advantages:

[0016] 1. Using microwave resonance coupling transmitter, plasma is generated in a closed process, and the polycarbosilane molecules are crosslinked under the action of plasma. High-energy particles (such as electrons, ions, radicals, etc.) in the plasma can interact with polycarbosilane molecules, causing chemical bond breakage and recombination on the molecular chain, thereby forming a crosslinked structure. This microwave resonance coupling technology improves energy conversion efficiency, and compared with the traditional high-frequency electric field excitation gas molecule ionization method for generating plasma, energy consumption is reduced by about 30%-50%;

[0017] 2. Compared with the traditional high-temperature crosslinking method, plasma-assisted in-situ crosslinking is carried out at a lower temperature, avoiding the damage of high temperature to the performance of polycarbosilane material, and also reducing energy consumption; and the crosslinking of polycarbosilane can be realized in a short time, improving the production efficiency;

[0018] 3. The gas source realizes flow and efficient mixing in the gas inlet chamber, ensuring uniform distribution of plasma in the entire closed processing chamber, improving processing efficiency and quality;

[0019] 3. By adjusting the discharge power and discharge time of the microwave resonance coupling transmitter, the heating temperature and time of the second automatic heater can be controlled, so that the degree of in-situ crosslinking reaction and the performance of polycarbosilane material can be accurately controlled to meet the needs of different application fields;

[0020] 5. Combining thermal crosslinking and plasma-assisted crosslinking, plasma-assisted crosslinking mainly forms a crosslinked layer on the surface of polycarbosilane fibers, and thermal crosslinking further consolidates and perfects the crosslinked structure from the inside. The combination of the two can form a more uniform and dense three-dimensional network structure for polycarbosilane fibers, effectively improving the overall stability and performance of the fibers;

[0021] 6. No chemical crosslinking agent is needed, avoiding environmental pollution and the influence on material performance that may be caused by chemical crosslinking agent;

[0022] 7. By controlling the system to monitor the state of plasma in real time and automatically adjusting the discharge power and gas flow, the crosslinking reaction can be ensured to run stably and efficiently, so as to realize the controllability of the crosslinking reaction;

[0023] 8. After the combined crosslinking treatment, the polycarbosilane fiber bundle has good thermal stability, mechanical properties and chemical stability. In a high-temperature environment, it can maintain good shape and structural integrity, withstand higher tensile stress, and greatly improve resistance to chemical reagents, meeting more demanding use conditions;

[0024] 9. The crosslinking device is simple and suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1The utility model relates to a crosslinking device for polycarbosilane fiber, which comprises an air inlet system, a crosslinking and heat treatment system and a control system.

[0026] Figure 2 The utility model discloses a crosslinking and heat treatment system's schematic diagram of top view structure for air inlet system in the utility model;

[0027] Figure 3 The utility model discloses a crosslinking and heat treatment system's schematic diagram of side structure for air inlet system in the utility model;

[0028] Figure 4 It is the electron microscope diagram of the silicon carbide fiber that polycarbosilane fiber in embodiment two is obtained after post-processing.

[0029] Figure 5 It is the electron microscope diagram of the silicon carbide fiber that polycarbosilane fiber in embodiment three is obtained after post-processing.

[0030] In the drawing,

[0031] Air inlet chamber 1;Air inlet channel 11;

[0032] Flow valve 12;First automatic heater 2;

[0033] Closed processing chamber 3;Slide rail 31;

[0034] Second automatic heater 32;Microwave resonance coupling transmitter 33;

[0035] Vacuum pump 34;Exhaust valve 35;

[0036] Processing platform 4;Sliding frame 5;

[0037] Pulley 51;Fixed frame 6;

[0038] Guide rail 61;Air outlet channel 7;

[0039] Control system 8. DETAILED DESCRIPTION

[0040] In order to further explain the technical scheme of the utility model, the utility model will be described in detail through specific embodiments below.

[0041] Embodiment one

[0042] A crosslinking device for polycarbosilane fiber, as shown in the figure, comprises an air inlet system, a crosslinking and heat treatment system and a control system, the air inlet system comprises an air inlet chamber 1, the air inlet chamber 1 is communicated with a plurality of air inlet channels 11 for introducing gas source, and a flow valve 12 is arranged on each air inlet channel 11. Figures 1-3

[0043] ​The first automatic heater 2 is a heating rod or a heating pipe.

[0044] The crosslinking and heat treatment system comprises a closed treatment chamber 3, one end of the closed treatment chamber 3 is provided with a material inlet, the closed treatment chamber 3 is provided with a sealing valve cover corresponding to the material inlet, the closed treatment chamber 3 is provided with a treatment platform 4 for placing a polycarbosilane fiber bundle, the inner surface of the sealing valve cover is fixedly connected with one end of the treatment platform 4, the outer surface of the sealing valve cover is provided with a sliding frame 5, the closed treatment chamber 3 is fixed on a fixed frame 6, and the lower ends of the two sides of the sliding frame 5 are symmetrically provided with pulleys 51, the two sides of the fixed frame 6 are provided with guide rails 61 which are in sliding cooperation with the pulleys 51, so that the sliding frame 5 is in sliding cooperation with the fixed frame 6, and the closed treatment chamber 3 is further provided with a sliding rail 31 which is in sliding cooperation with the treatment platform 4. In this way, the treatment platform 4 can slide relative to the closed treatment chamber 3, and the feeding and discharging are more convenient.

[0045] The closed treatment chamber 3 is provided with a plurality of second automatic heaters 32 which are distributed around the treatment platform 4 on the inner wall of the closed treatment chamber 3, and the second automatic heater 32 is a heating rod or a heating pipe.

[0046] The closed treatment chamber 3 is provided with a plurality of gas outlets which are in communication with a vacuum treatment system, specifically, the closed treatment chamber 3 is provided with two gas outlets which are arranged at the other end of the closed treatment chamber 3. The vacuum treatment system is a vacuum pump 34. The closed treatment chamber 3 is further provided with an exhaust valve 35 which is in communication with the outside, and a control system 8 is in control connection with each flow valve 12, the first automatic heater 2, the second automatic heater 32, the microwave resonance coupling transmitter 33. The control system 8 is a known PLC control system, and the control mode is also a known control mode in the art.

[0047] The closed treatment chamber 3 is provided with a plurality of gas outlets which are in communication with a vacuum treatment system, specifically, the closed treatment chamber 3 is provided with two gas outlets which are arranged at the other end of the closed treatment chamber 3. The vacuum treatment system is a vacuum pump 34. The closed treatment chamber 3 is further provided with an exhaust valve 35 which is in communication with the outside, and a control system 8 is in control connection with each flow valve 12, the first automatic heater 2, the second automatic heater 32, the microwave resonance coupling transmitter 33. The control system 8 is a known PLC control system, and the control mode is also a known control mode in the art.

[0048] The terms "first", "second" and the like in the description and claims of the utility model are used to distinguish different objects, and are not used to distinguish a specific order.

[0049] Embodiment two

[0050] A cross-linking method using the cross-linking device for polycarbosilane fibers of Example One, comprising the following steps:

[0051] Step 1, first place the polycarbosilane fiber bundle with a diameter of 12-13 μm (thinner) on the processing platform 4, then send it into the closed processing chamber 3, use the vacuum pump 34 to create a vacuum, then pass helium into the closed processing chamber 3 through the gas outlet channel 7 of the gas inlet chamber 1, control the flow rate of the helium through the flow valve 12 to be 50 mL / min;

[0052] Step 2, then control the discharge power and discharge time of the microwave resonance coupling transmitter 33, where the discharge power is 50 W and the discharge time is 15 minutes, carry out plasma cross-linking treatment, then control the heating rate, heating temperature and time of the second automatic heater 32, where the heating rate is 3°C / min, the holding temperature is 180°C, and the holding time is 5 hours, to carry out thermal cross-linking treatment on the polycarbosilane fiber bundle;

[0053] Step 3, finally control the heating rate, heating temperature and time of the second automatic heater 32, where the heating rate is 2°C / min, the holding temperature is 340°C, and the holding time is 25 minutes, to carry out post-treatment on the polycarbosilane fiber bundle, so that the fiber molecules are completely converted into a non-melting network structure, and the gas in the closed processing chamber 3 is discharged through the exhaust valve 35.

[0054] In Step 1, control the heating temperature and time of the first automatic heater 2, which is mainly used to control the temperature of the heated helium, and the holding temperature is consistent with that of the second automatic heater 32, to reduce the heat loss caused by the temperature difference of the gas entering the closed processing chamber 3, and to reduce the fluctuations in the performance of the fiber.

[0055] Example Three

[0056] A cross-linking method using the cross-linking device for polycarbosilane fibers of Example One, comprising the following steps:

[0057] Step 1, first place the polycarbosilane fiber bundle with a diameter of 15-16 μm (thicker) on the processing platform 4, then send it into the closed processing chamber 3, use the vacuum pump 34 to create a vacuum, then pass helium into the closed processing chamber 3 through the gas outlet channel 7 of the gas inlet chamber 1, control the flow rate of the helium through the flow valve 12 to be 150 mL / min;

[0058] Step 2, then control the discharge power and discharge time of the microwave resonance coupling transmitter 33, wherein the discharge power is 300 W and the discharge time is 20 minutes, perform plasma crosslinking treatment, and then control 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, to perform thermal crosslinking treatment on the polycarbosilane fiber bundle;

[0059] 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 minutes, to post-treat the polycarbosilane fiber bundle, completely convert the fiber molecules into a non-melting network structure, and release the gas in the closed treatment chamber 3 through the exhaust valve 35.

[0060] In Step 1, control the heating temperature and time of the first automatic heater 2, which is mainly used to control the temperature of the heated helium gas, and the holding temperature is consistent with that of the second automatic heater 32, so as to reduce the heat loss caused by the temperature difference of the gas entering the closed treatment chamber 3 and to avoid fluctuations in the performance of the fiber.

[0061] Performance test

[0062] 1. Morphology of silicon carbide fiber

[0063] The polycarbosilane crosslinked filaments obtained by crosslinking in Example 2 and Example 3 are converted into high-performance SiC fibers through the steps of 1250°C hydrogen pyrolysis and 1600°C high-temperature final firing, and the morphology of the silicon carbide fiber is as shown in Figure 4 and Figure 5 The diameter of the fiber is shown in Table 1.

[0064] Table 1. Single fiber diameter

[0065]

[0066] The single fiber diameter of Example 2 is 10.8 μm, and the relatively thin diameter makes the fiber have advantages in some specific applications. For example, when preparing high-performance composites, thinner fibers can be more uniformly dispersed in the matrix, enhancing the overall performance of the material. At the same time, the smaller diameter also makes the fiber easier to apply in some narrow spaces or occasions where the thickness of the material is strictly required. The single fiber diameter Cv is 6.75%, indicating that the fiber diameter is uniform, which helps to ensure the stability and reliability of the material performance. In practical applications, the uniformity of the fiber diameter is crucial for the control of product quality.

[0067] The single fiber diameter of Example Three is 12.7 μm, and a thicker diameter can have unique advantages in certain applications. For example, in situations requiring to withstand greater external force or requiring higher wear resistance, a thick diameter fiber can provide stronger load bearing capacity and better durability. In addition, thicker fibers can be easier to handle during processing and handling, reducing production difficulty. The single fiber diameter Cv is 7.75%, also showing good diameter consistency. This helps to ensure the stability of fiber performance during use, reducing quality problems caused by diameter differences.

[0068] 2. Tensile property test

[0069] Table 2. Tensile property test results

[0070]

[0071] The tensile strength of the silicon carbide fiber processed by the present crosslinking device is above 2.8 GPa, and the tensile modulus is as high as 350 GPa, with excellent fiber performance and broad application prospects.

[0072] 3. High temperature strength retention rate

[0073] (1) Silicon carbide fiber processed by Example 2

[0074] Table 3. High temperature strength retention rate of silicon carbide fiber

[0075]

[0076] The silicon carbide fiber corresponding to Example Two exhibits relatively stable performance under different temperature and atmosphere conditions. For example, under the condition of air-1300℃-2000s, the tensile strength is 2.57 GPa, and the high temperature strength retention rate is 82.9%; under the condition of Ar-1300℃-2000s, the tensile strength is 2.72 GPa, and the high temperature strength retention rate is 87.8%. This shows that whether in air or argon atmosphere, at a relatively low temperature (1300℃), the fiber can well maintain the strength, showing high stability.

[0077] With the increase of temperature, although the strength decreases, the decrease is reasonable. For example, under the condition of air-1400℃-2000s, the tensile strength is 1.74 GPa, and the high temperature strength retention rate is 56.1%; under the condition of Ar-1400℃-2000s, the tensile strength is 1.97 GPa, and the high temperature strength retention rate is 63.5%. Even at a higher temperature, the fiber can still maintain a certain strength, showing its adaptability in different temperature ranges and excellent high temperature resistance, further proving that the fiber has extremely broad application prospects in the field of high temperature resistant structural parts.

[0078] (2) The silicon carbide fiber processed by Example 3

[0079] Table 4 High temperature strength retention rate of silicon carbide fiber

[0080]

[0081] Example Three The silicon carbide fiber processed by Example 3 exhibits good strength retention capability at high temperature. Under the condition of air-1300℃-2000s, the tensile strength is 2.35 GPa, and the high temperature strength retention rate is 81.0%; under the condition of Ar-1300℃-2000s, the tensile strength is 2.43 GPa, and the high temperature strength retention rate is 83.7%. This indicates that the fiber can maintain a certain strength even in a high temperature environment, showing its good high temperature resistance characteristics.

[0082] With the increase of temperature, although the strength decreases, it can still be maintained at a certain level. For example, under the condition of air-1400℃-2000s, the tensile strength is 1.63 GPa, and the high temperature strength retention rate is 56.2%; under the condition of Ar-1400℃-2000s, the tensile strength is 1.85 GPa, and the high temperature strength retention rate is 63.8%. This indicates that the fiber has a certain stability at different temperatures and can adapt to a certain range of high temperature changes.

[0083] Owing to its excellent high temperature performance, the silicon carbide fiber processed by the crosslinking method of Example Two and Example Three has broad application prospects in high-precision fields such as aerospace. In these fields, the high temperature resistance of materials is extremely high, and the fiber can maintain a high strength in a high temperature environment, providing reliable material selection for key parts such as the thermal protection system of spacecraft and engine components.

[0084] In other industrial fields such as metallurgy and chemical industry, there are also high requirements for the high temperature resistance and strength stability of materials. The silicon carbide fiber obtained by the present application can meet these needs and provide high-performance material solutions for the manufacture of parts of high temperature equipment, improving the service life and production efficiency of the equipment.

[0085] The above examples and drawings do not limit the product form and style of the present application, and any appropriate changes or modifications made by ordinary skilled persons in the art shall be considered as not departing from the patent scope of the present application.

Claims

1. A crosslinking device for polycarbosilane fibers, comprising a gas inlet system, a crosslinking and heat treatment system, and a control system, characterized in that: The air intake system comprises an air intake chamber, a plurality of air intake channels are communicated with the air intake chamber, a plurality of groups of first automatic heaters are arranged in the air intake chamber, the cross-linking and heat treatment system comprises a sealed treatment chamber, an air outlet channel is communicated between the air intake chamber and the sealed treatment chamber, a treatment platform for placing a polycarbosilane fiber bundle is arranged in the sealed treatment chamber, a plurality of groups of second automatic heaters are arranged on the inner wall of the sealed treatment chamber and surround the treatment platform, a plurality of microwave resonance coupling emitters are arranged on the inner wall of the sealed treatment chamber and surround the treatment platform, a plurality of gas outlets are arranged on the sealed treatment chamber and are communicated with a vacuum treatment system, an exhaust valve is further arranged on the sealed treatment chamber and is communicated with the outside, and the control system is respectively connected with the first automatic heaters, the second automatic heaters and the microwave resonance coupling emitters.

2. A crosslinking device for polycarbosilane fibers according to claim 1, characterized in that: The second automatic heaters and the microwave resonance coupling emitters are alternately distributed.

3. A crosslinking device for polycarbosilane fibers according to claim 1, characterized in that: The vacuum treatment system is a vacuum pump.

4. A crosslinking device for polycarbosilane fibers according to claim 1, characterized in that: Temperature sensors connected with the control system are arranged in the air intake chamber and the sealed treatment chamber.

5. A crosslinking device for polycarbosilane fibers according to claim 1, characterized in that: Flow valves are arranged on the air intake channels, and the flow valves are connected with the control system.

6. A crosslinking device for polycarbosilane fibers according to claim 1, characterized in that: One end of the sealed treatment chamber is provided with a material passing opening, a sealing valve cover is arranged on the position corresponding to the material passing opening of the sealed treatment chamber, the inner surface of the sealing valve cover is fixedly connected with the treatment platform, the outer surface of the sealing valve cover is provided with a sliding frame, the sealed treatment chamber is fixed on a fixed frame, the sliding frame is slidingly connected with the fixed frame, and the sealed treatment chamber is further provided with a sliding rail slidingly matched with the treatment platform.

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