A method and apparatus for high purity silicon carbide fiber high temperature continuous carbonization molding

Abstract

The present application relates to the technical field of silicon carbide fiber carbonization, and particularly relates to a high-purity silicon carbide fiber high-temperature continuous carbonization forming method and equipment, comprising: leading out polycarbosilane non-fusible fiber bundles from multiple wire-drawing spindles, performing surface deep-cold vacuum purification treatment on the led-out fiber bundles to remove impurities adsorbed on the surface and inside of the fiber, performing multi-bundle tension self-balancing conveying on the purified fiber bundles in a non-contact acoustic standing wave field, continuously feeding the fiber bundles after tension balancing into a high-temperature carbonization furnace, performing high-temperature pyrolysis conversion under the protection of an inert atmosphere, and sequentially performing surface treatment, drying forming and winding on the carbonized fiber bundles. In the present application, deep removal and re-adsorption blocking of oxygen and water adsorbed on the surface of the fiber are achieved, and the problems of inlet dynamic sealing failure and fiber surface impurity entrainment in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide fiber carbonization technology, and in particular to a high-purity silicon carbide fiber high-temperature continuous carbonization molding method and equipment. Background Technology

[0002] High-purity silicon carbide fiber is a continuous inorganic fiber produced using polycarbosilane as a precursor through melt spinning, non-melting treatment, and high-temperature carbonization. It possesses excellent properties such as high-temperature resistance, oxidation resistance, high strength, and high modulus, making it a key reinforcement in ceramic matrix composites used in aerospace, nuclear energy, and other fields. The oxygen content within the fiber and the consistency of properties between bundles directly affect the service reliability of the composite material; therefore, achieving low oxygen content and high uniformity is the core objective in the preparation of high-purity silicon carbide fiber.

[0003] In existing technologies, polycarbosilane infusible fiber bundles are typically drawn from a feeding frame and fed into a high-temperature carbonization furnace through a multi-stage air curtain or air-sealed chamber. Under an inert atmosphere, the fibers undergo pyrolysis at 1300-1600℃, followed by sizing, drying, and winding to obtain the finished product. To maintain a low-oxygen environment within the furnace, industrial processes rely on multi-stage air seals to block outside air, while mechanical guide rollers and passive or active tensioners are used to control the tension of the multiple fiber bundles.

[0004] However, the following problems still exist in the existing technology: I. Failure of dynamic seal at the inlet and problem of impurities entrained on the fiber surface: The high-speed fiber bundles entrain air and moisture like pistons. Conventional air seals cannot remove oxygen and water that are physically adsorbed and condensed by capillary action on the fiber surface, resulting in high and fluctuating oxygen content in the carbonized fibers, making it difficult to consistently meet the high purity requirements.

[0005] 2. Problems with passive coupling of tension in multi-spindle feeding and lack of adaptive capability due to material differences: The fibers in each spindle are mechanically coupled through the guide roller network, and the tension fluctuations interfere with each other. The tension differences caused by changes in the material roll diameter and unwinding jumps cannot be decoupled in real time, resulting in large dispersion of fiber diameter and uneven strength, which can lead to fiber breakage in severe cases.

[0006] Therefore, to solve the above problems, a high-temperature continuous carbonization molding method and equipment for high-purity silicon carbide fibers are proposed. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides the following technical solution: A method for high-purity silicon carbide fiber high-temperature continuous carbonization molding includes the following steps: S1: Lead out polycarbosilane infusible fiber bundles from multiple feeding spindles.

[0008] S2: The extracted fiber bundles are subjected to surface cryogenic vacuum purification treatment to remove impurities adsorbed on the fiber surface and inside.

[0009] S3: The purified fiber bundles are transported autonomously and tension-equalized in a non-contact acoustic standing wave field.

[0010] S4: The tension-equalized fiber bundle is continuously fed into a high-temperature carbonization furnace and undergoes high-temperature pyrolysis conversion under an inert atmosphere.

[0011] S5: The carbonized fiber bundles are then subjected to surface treatment, drying and shaping, and winding in sequence.

[0012] As an improvement to the above technical solution: S21: The fiber bundle is continuously passed through a cryogenic chamber with a temperature below -100°C, causing the water molecules adsorbed on its surface and inside to freeze.

[0013] S22: The fiber bundle is then fed into a vacuum chamber with an absolute pressure of less than 100 Pa, so that the frozen water molecules are directly sublimated and extracted, while the physically adsorbed oxygen is removed.

[0014] As an improvement to the above technical solution: S23: Immediately introduce the fiber bundle that has already adsorbed oxygen into a refill chamber filled with inert gas of 99.9999% purity, and use the inert gas atoms to occupy the high-energy adsorption sites exposed on the surface of the fiber bundle due to the desorption of impurities, forming a single-atom-level inert protective layer.

[0015] As an improvement to the above technical solution: S31: The purified fiber bundles are passed laterally through a two-dimensional near-field acoustic levitation chamber generated by an ultrasonic transducer array, so that all fiber bundles are captured at the acoustic pressure node and levitated and transported without mechanical contact.

[0016] S32: Using an array of acoustic sensors arranged on the sidewall of the acoustic suspension chamber, the spatial position change of each fiber in the sound field is sensed in real time.

[0017] S33: Based on the positional offset of each fiber, the sound field intensity of the corresponding area is dynamically adjusted, and the sound radiation force applied to each fiber bundle is adjusted in a non-contact manner until the axial transport resistance experienced by all fiber bundles tends to be consistent, thereby achieving autonomous tension balance.

[0018] As an improvement to the above technical solution: S331: Through the dynamic adjustment of the sound field, a controllable micro-traveling wave component is introduced into the acoustic suspension cavity, and the acoustic flow effect is used to apply a differentiated forward traction force to the non-contact suspended fiber bundle, thereby actively compensating for the fiber bundle with low tension.

[0019] As an improvement to the above technical solution: S41: The carbonization temperature in the high-temperature carbonization furnace is 1300-1600℃, and the furnace is protected by high-purity inert gas with a purity of 99.999%.

[0020] S42: The furnace tubes and wire guides of the high-temperature carbonization furnace are both made of high-purity graphite.

[0021] As an improvement to the above technical solution: A high-purity silicon carbide fiber high-temperature continuous carbonization molding apparatus applied to the method of any one of claims 1 to 7, comprising, in sequence along the fiber travel direction: The unit includes a wire feeding unit, a surface cryogenic vacuum purification unit, an acoustic suspension tension decoupling conveying unit, a high-temperature carbonization unit, a surface treatment and forming unit, and a winding unit.

[0022] The surface cryogenic vacuum purification unit is divided into a cryogenic chamber, a vacuum chamber, and an inert gas refill chamber along the fiber travel direction. There is a narrow channel between the three chambers for the fiber to pass through. The cryogenic chamber is connected to the liquid nitrogen supply system, the vacuum chamber is connected to the multi-stage vacuum pump group, and the inert gas refill chamber is connected to the high-purity argon gas source.

[0023] The acoustic suspension tension decoupling and delivery unit is located between the surface cryogenic vacuum purification unit and the high-temperature carbonization unit. It includes a flat acoustic resonant cavity, on which ultrasonic transducer arrays are installed on both the top and bottom plates. Microelectromechanical microphone arrays for sensing fiber position are arranged on its sidewalls.

[0024] Multiple bundles of fibers drawn from the fiber feeding unit pass through the cryogenic chamber, vacuum chamber, and inert gas refill chamber of the surface cryogenic vacuum purification unit, then laterally through the acoustic resonant cavity of the acoustic suspension tension decoupling delivery unit, and finally enter the inlet of the high-temperature carbonization unit.

[0025] As an improvement to the above technical solution: The high-temperature carbonization unit is a multi-temperature zone resistance heating furnace with gradient heating function. Its furnace tube is made of high-purity graphite, and its internal wire guide is also made of high-purity graphite.

[0026] The yarn feeding unit includes multiple active yarn feeding motors, each of which is linked to the microelectromechanical microphone array in the acoustic suspension tension decoupling delivery unit to form a distributed tension closed-loop control system.

[0027] The beneficial effects of this invention are: 1. In this invention, a surface cryogenic vacuum purification process is employed. First, the fiber bundle passes through a cryogenic chamber to freeze the water molecules adsorbed on its surface and inside. Then, it is sent into a vacuum chamber where the ice crystals are directly sublimated and extracted. An inert gas is introduced to form an atomic-level protective layer on the fiber surface. This achieves deep removal and re-adsorption blocking of adsorbed oxygen and water on the fiber surface, solving the problems of inlet dynamic sealing failure and impurity entrainment on the fiber surface in existing technologies.

[0028] 2. In this invention, multi-bundle tension autonomous equalization conveying is achieved through a non-contact acoustic standing wave field. Each fiber bundle is captured at an acoustic pressure node using acoustic radiation force for non-contact levitation conveying. Real-time sensing of fiber position changes dynamically adjusts the acoustic field intensity, adjusting the axial resistance of each fiber in a non-contact manner. Furthermore, micro-traveling wave components are introduced into the acoustic field to actively compensate for fibers with insufficient tension using acoustic flow effects. This achieves essential decoupling and adaptive equalization of multi-bundle fiber tension, solving the problems of passive coupling of multi-spindle feeding tension and lack of adaptive capability due to material differences in existing technologies. Attached Figure Description

[0029] Figure 1 This is a flowchart of the high-temperature continuous carbonization molding method for high-purity silicon carbide fibers in this invention. Figure 2 This is a structural diagram of the device in this invention. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0031] See appendix Figure 1 A method for high-purity silicon carbide fiber high-temperature continuous carbonization molding includes the following steps: S1: Lead out polycarbosilane infusible fiber bundles from multiple feeding spindles.

[0032] S2: The extracted fiber bundles are subjected to surface cryogenic vacuum purification treatment to remove impurities adsorbed on the fiber surface and inside.

[0033] S3: The purified fiber bundles are transported autonomously and tension-equalized in a non-contact acoustic standing wave field.

[0034] S4: The tension-equalized fiber bundle is continuously fed into a high-temperature carbonization furnace and undergoes high-temperature pyrolysis conversion under an inert atmosphere.

[0035] S5: The carbonized fiber bundles are then subjected to surface treatment, drying and shaping, and winding in sequence.

[0036] In one embodiment, S1: Polycarbosilane infusible fiber bundles are simultaneously drawn out from multiple feeding spindles, and each fiber bundle enters the two processes of surface cryogenic vacuum purification treatment and acoustic standing wave field tension equalization treatment in a parallel arrangement.

[0037] S2: The fiber bundle extracted in step S1 undergoes surface cryogenic vacuum purification treatment. The fiber bundle passes through the cryogenic chamber and the vacuum chamber in succession. The physically adsorbed water on the fiber surface and the capillary condensed water in the internal micropores are cryogenically frozen into solid ice crystals and then directly extracted by vacuum sublimation. The oxygen and water carried by the fiber are removed from the source, so that the fiber no longer has the ability to carry impurities before entering the high-temperature carbonization furnace. This solves the problem that traditional gas seals cannot completely prevent the entrainment of adsorbed oxygen and water on the fiber surface.

[0038] S3: The fiber bundles purified in step S2 are transported autonomously and evenly in a non-contact acoustic standing wave field. Each fiber bundle is suspended and transported in a sound pressure node without any mechanical guide roller contact. Acoustic sensors detect the position changes of each fiber bundle in the sound field in real time and dynamically adjust the sound field intensity. The axial transport resistance experienced by each fiber bundle is made to become consistent in a non-contact manner. Since there is no physical contact between the fibers, the transmission path of tension crosstalk is cut off, which solves the problem of passive coupling of multi-spindle feeding tension caused by traditional mechanical guide roller networks.

[0039] S4: The fiber bundle with tension balanced after step S3 is continuously fed into a high-temperature carbonization furnace and undergoes high-temperature pyrolysis conversion under the protection of an inert atmosphere to obtain high-purity silicon carbide fiber.

[0040] S5: The silicon carbide fibers obtained in step S4 are subjected to surface treatment, drying and shaping and winding in sequence to obtain high-purity silicon carbide fiber products with oxygen content of less than 0.5wt% and inter-bundle strength dispersion coefficient of less than 3%.

[0041] See appendix Figure 1 S21: Allows the fiber bundle to pass continuously through a cryogenic chamber with a temperature below -100°C, freezing the water molecules adsorbed on its surface and inside.

[0042] S22: The fiber bundle is then sent into a vacuum chamber with an absolute pressure of less than 100 Pa, so that the frozen water molecules are directly sublimated and extracted, while the physically adsorbed oxygen is removed.

[0043] In one embodiment, S21: the fiber bundle is passed through a cryogenic chamber maintained at -120°C by a liquid nitrogen supply system at a constant feeding speed. Water molecules physically adsorbed on the fiber surface and water molecules present in the internal micropores due to capillary coagulation are instantly frozen into solid ice crystals at this temperature. Oxygen molecules originally attached to the fiber surface are also bound by the frozen ice crystal lattice and lose their ability to migrate freely.

[0044] S22: The fiber bundle is then fed through a slit channel into a vacuum chamber where the absolute pressure is maintained at 50 Pa by a multi-stage Roots pump group. Under this low-pressure condition, the solid ice crystals sublimate directly into water vapor without passing through the liquid state. Together with the released oxygen, they are quickly extracted from the vicinity of the fiber by the vacuum pump group. The one-time removal rate of water and oxygen physically adsorbed on the fiber surface can reach more than 99%, eliminating the possibility of impurities carried by the fiber into the high-temperature furnace from the source.

[0045] See appendix Figure 1 S23: Immediately introduce the fiber bundle that has already adsorbed oxygen into a refill chamber filled with inert gas of 99.9999% purity. The inert gas atoms occupy the high-energy adsorption sites on the fiber bundle surface exposed by the desorption of impurities, forming a single-atom-level inert protective layer.

[0046] In one embodiment, S23: The fiber bundle leaving the vacuum chamber is directly fed into an adjacent inert gas refill chamber through a sealed flange. This chamber is continuously purified with 99.9999% pure argon gas and maintained at a slightly positive pressure. Since the cryogenic vacuum treatment has completely removed the adsorbed water and oxygen from the fiber surface, the fiber surface is now exposed with a large number of unsaturated physical adsorption sites in a high-energy state. Driven by the concentration gradient and surface free energy, high-purity argon atoms preferentially occupy these high-energy adsorption sites, forming a continuous and dense single-atom-level argon physical adsorption protective layer on the fiber surface. This protective layer completely isolates the active surface of the fiber from the external atmosphere. During the subsequent transport of the fiber through a multi-stage gas-sealed chamber into the high-temperature carbonization furnace, since the high-energy adsorption sites have been pre-filled by argon atoms, oxygen molecules and water molecules in the air can no longer find usable adsorption sites, thus completely blocking the path of impurity re-entrainment at the chemical adsorption level.

[0047] See appendix Figure 1 S31: The purified fiber bundles are passed laterally through a two-dimensional near-field acoustic suspension chamber generated by an ultrasonic transducer array, so that all fiber bundles are captured at the acoustic pressure node and suspended and transported without mechanical contact.

[0048] S32: Using an array of acoustic sensors arranged on the sidewalls of the acoustic suspension chamber, the spatial position changes of each fiber in the sound field are sensed in real time.

[0049] S33: Based on the positional offset of each fiber, the sound field intensity of the corresponding area is dynamically adjusted, and the sound radiation force applied to each fiber bundle is adjusted in a non-contact manner until the axial transport resistance experienced by all fiber bundles tends to be consistent, thereby achieving autonomous tension balance.

[0050] In one embodiment, S31: The purified fiber bundles are transversely passed through the acoustic suspension chamber in a parallel arrangement. The acoustic suspension chamber is a standing wave acoustic suspension chamber. The top and bottom plates of the chamber are respectively equipped with ultrasonic transducer arrays. The distance between the top and bottom plates is an integer multiple of half the wavelength. The ultrasonic transducer arrays work synchronously at a frequency of 40kHz and a driving voltage of not less than [specific value]V to form a stable two-dimensional standing wave sound field in the chamber. The sound pressure level is not less than the specific value. Each fiber bundle is captured at a different sound pressure nodal position and is transported along the fiber travel direction in a suspended state about 2mm to 6mm away from the top and bottom plate walls, without contacting any mechanical guide rollers or idlers throughout the process.

[0051] S32: Using a microelectromechanical microphone array arranged on the side wall of the acoustic suspension chamber, the spatial position change of each fiber bundle in the sound field is sensed in real time at a sampling frequency of no less than 200 times per second. When the unwinding tension of the fiber bundle changes due to the gradual reduction of the winding diameter of the raw filament at a certain unwinding spindle position, the equilibrium position of the fiber in the sound field is displaced at the micrometer level, and the microphone array converts the position change into an electrical signal.

[0052] S33: The control system dynamically changes the sound field intensity of the corresponding area by adjusting the driving voltage of the ultrasonic transducer in the corresponding area according to the direction and amplitude of each fiber's deviation from the target nodal position. It adjusts the acoustic radiation force of the sound field on the fiber in a non-contact manner, so that the axial conveying resistance it experiences is consistent with that of other fibers. During the entire adjustment process, there is no physical connection between the fibers using any mechanical guide rollers. The tension crosstalk wave transmitted by the guide roller network in the traditional multi-spindle feeding frame is fundamentally eliminated, realizing the essential decoupling and real-time autonomous balance of the tension of multiple fiber bundles.

[0053] See appendix Figure 1 S331: By dynamically adjusting the sound field, a controllable micro-traveling wave component is introduced into the acoustic suspension chamber. The acoustic flow effect is used to apply a differentiated forward traction force to the non-contact suspended fiber bundle, actively compensating for the fiber bundle with low tension.

[0054] In one embodiment, S331: When the microelectromechanical microphone array detects that the equilibrium position of a fiber bundle in the sound pressure nodal line is continuously biased towards the fiber inlet side and the offset exceeds a preset position threshold and remains for more than a preset time, the control system determines that the tension of the fiber bundle is continuously low. Under the premise of keeping the main distribution of the standing wave sound field in the fiber area unchanged, a micro-traveling wave component with controllable amplitude is introduced by applying a small phase difference to the corresponding ultrasonic transducers above and below the area. The micro-traveling wave component generates a directional acoustic flow along the fiber travel direction in the gas medium around the fiber. The acoustic flow applies a stable non-contact viscous forward traction force to the fiber surface, providing an active compensation driving force with a matching value for the fiber bundle with low tension. Meanwhile, the area where the fiber with normal or high tension is located remains in a pure standing wave state and is not affected by any additional traction force. The tension deviation between each fiber bundle is finely adjusted to a range of no more than ±2%.

[0055] See appendix Figure 1 S41: The carbonization temperature in the high-temperature carbonization furnace is 1300-1600℃, and the furnace is protected by high-purity inert gas with a purity of 99.999%.

[0056] S42: The furnace tubes and wire guides of the high-temperature carbonization furnace are made of high-purity graphite.

[0057] In one embodiment, S41: After passing through the acoustic suspension tension decoupling conveying unit, the fiber bundle enters the high-temperature carbonization furnace in a uniform state with an inter-bundle tension deviation of no more than ±2%. High-purity argon gas with a purity of 99.999% is continuously introduced into the furnace as a protective atmosphere. A multi-stage gas seal structure is set at the furnace outlet and inlet, and high-purity argon gas of the same source is introduced to stably control the oxygen content in the furnace to below 1ppm. Three independently temperature-controlled heating sections are set in the furnace along the fiber travel direction: a preheating zone, a high-temperature carbonization zone, and a slow cooling zone. The temperature in the preheating zone is gradually increased from room temperature to 800℃ to complete the low-temperature pyrolysis of the fiber. The temperature in the high-temperature carbonization zone is gradually increased from 1300℃ to 1600℃ to allow the fiber to complete the full pyrolysis transformation and crystal phase transformation from polycarbosilane to β-silicon carbide. The temperature in the slow cooling zone is gradually decreased from 1600℃ to below 200℃ to allow the fiber to complete stress release in the protective atmosphere.

[0058] S42: The furnace tube is made of high-purity graphite through isostatic pressing and precision machining. The wire guide inside the furnace tube is also made of high-purity graphite and precision ground. All components in the high-temperature zone do not volatilize any metal impurities at 1600℃, avoiding secondary contamination of the fibers by the furnace components. This measure works in conjunction with the cryogenic vacuum purification and inert gas atom protective layer passivation treatment completed before the fibers enter the furnace to ensure that the oxygen content of the final silicon carbide fiber is stably controlled below 0.5wt%.

[0059] See appendix Figure 2A high-purity silicon carbide fiber high-temperature continuous carbonization molding equipment applied to the method of any one of claims 1 to 7, comprising, in sequence along the fiber travel direction: The unit includes a wire feeding unit, a surface cryogenic vacuum purification unit, an acoustic suspension tension decoupling conveying unit, a high-temperature carbonization unit, a surface treatment and forming unit, and a winding unit.

[0060] The surface cryogenic vacuum purification unit is divided into a cryogenic chamber, a vacuum chamber, and an inert gas refill chamber along the fiber travel direction. There are narrow channels between the three chambers for the fiber to pass through. The cryogenic chamber is connected to the liquid nitrogen supply system, the vacuum chamber is connected to the multi-stage vacuum pump group, and the inert gas refill chamber is connected to the high-purity argon gas source.

[0061] The acoustic suspension tension decoupling delivery unit is located between the surface cryogenic vacuum purification unit and the high-temperature carbonization unit. It includes a flat acoustic resonant cavity, on which ultrasonic transducer arrays are installed on both the top and bottom plates. Microelectromechanical microphone arrays for sensing fiber position are arranged on its side walls.

[0062] Multiple bundles of fibers drawn from the fiber feeding unit pass through the cryogenic chamber, vacuum chamber, and inert gas refill chamber of the surface cryogenic vacuum purification unit, then laterally through the acoustic resonant cavity of the acoustic suspension tension decoupling transport unit, and finally enter the entrance of the high-temperature carbonization unit.

[0063] In one embodiment, multiple active feeding motors in the feeding unit independently drive a feeding spindle position, drawing out polycarbosilane non-melting fiber bundles that converge into a parallel fiber array with equal spacing. The fiber array first enters the surface cryogenic vacuum purification unit along the travel direction. In the cryogenic chamber, the liquid nitrogen supply system maintains the internal temperature of the chamber at a constant -120°C. The moisture in the fiber surface and internal micropores is frozen into solid ice crystals. The fiber enters the vacuum chamber through the first slit channel. The multi-stage Roots pump group pumps the absolute pressure in the chamber to 50Pa. The solid ice crystals sublimate into water vapor and are pumped away by the pump group. The fiber enters the inert gas refill chamber through the second slit channel. The high-purity argon gas source continuously supplies argon gas with a purity of 99.9999% to the chamber and maintains a slight positive pressure. Argon atoms form a single-atom-level inert protective layer on the fiber surface.

[0064] After surface cleaning, the fiber array enters the flat acoustic resonant cavity of the acoustic suspension tension decoupling transport unit through a sealed transition section. The ultrasonic transducer arrays on the top and bottom plates are synchronously excited at a frequency of 40kHz to generate a two-dimensional standing wave sound field. Each fiber bundle is captured at different sound pressure nodal positions and transported without contact. The microelectromechanical microphone array on the side wall monitors the micron-level displacement of each fiber bundle from the nodal position in real time and feeds the position signal back to the control system. The control system dynamically adjusts the driving power of the ultrasonic transducers in the corresponding area to autonomously balance the axial transport resistance experienced by each fiber bundle.

[0065] Finally, the fiber array, with a clean surface and uniform tension, enters the inlet of the high-temperature carbonization unit through a sealed interface.

[0066] See appendix Figure 2 The high-temperature carbonization unit is a multi-temperature zone resistance heating furnace with gradient heating function. Its furnace tube is made of high-purity graphite, and its internal wire guide is also made of high-purity graphite.

[0067] The unwinding unit contains multiple active unwinding motors, each of which is linked to the microelectromechanical microphone array in the acoustic suspension tension decoupling conveying unit, forming a distributed tension closed-loop control system.

[0068] In one embodiment, the multi-temperature zone resistance heating furnace of the high-temperature carbonization unit is divided into three temperature gradient sections along the fiber travel direction: a preheating zone, a high-temperature carbonization zone, and a slow cooling zone. Each temperature zone is independently temperature-controlled and connected by a sealed furnace tube. The furnace tube is made of high-purity graphite through isostatic pressing and precision machining. The guide wire inside the furnace tube is also made of high-purity graphite and precision ground to ensure that the fiber does not come into contact with any metal parts throughout the process at a high temperature of 1600℃, thus preventing high-temperature contamination of the fiber by metal impurities. Each active feeding motor of the feeding unit is controlled by an independent servo driver and establishes real-time signal linkage with the microelectromechanical microphone array on the side wall of the acoustic suspension tension decoupling conveying unit. When the microelectromechanical microphone array detects that the position of a fiber bundle in the sound field continuously deviates from the target nodal line and the deviation exceeds the preset position threshold, the control system simultaneously sends a speed correction command to the corresponding fiber feeding motor while adjusting the sound field parameters. The feeding speed of the motor is finely adjusted to correct the tension deviation from the fiber supply source. The non-contact sound field adjustment acts on the middle section of fiber conveying, and the active speed adjustment of the feeding motor acts on the front end of fiber supply. The two work together to form a distributed tension closed-loop control system covering the entire path of the fiber from its extraction to its entry into the carbonization furnace. This ensures that the tension between multiple fiber bundles remains highly consistent along the transmission path, guaranteeing the diameter uniformity and mechanical property consistency of the final silicon carbide fiber product.

[0069] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Anyone skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for high-purity silicon carbide fiber high-temperature continuous carbonization molding, characterized in that, Includes the following steps: S1: Lead out polycarbosilane infusible fiber bundles from multiple feeding spindles; S2: The extracted fiber bundles are subjected to surface cryogenic vacuum purification treatment to remove impurities adsorbed on the fiber surface and inside. S3: The purified fiber bundles are delivered autonomously and evenly in a non-contact acoustic standing wave field with multiple bundles of tension. S4: The tension-equalized fiber bundle is continuously fed into a high-temperature carbonization furnace and undergoes high-temperature pyrolysis conversion under an inert atmosphere. S5: The carbonized fiber bundles are then subjected to surface treatment, drying and shaping, and winding in sequence.

2. The high-temperature continuous carbonization molding method for high-purity silicon carbide fibers according to claim 1, characterized in that, The surface cryogenic vacuum purification process described in S2 specifically includes the following steps: S21: The fiber bundle is continuously passed through a cryogenic chamber with a temperature below -100°C, causing the water molecules adsorbed on its surface and inside to freeze. S22: The fiber bundle is then fed into a vacuum chamber with an absolute pressure of less than 100 Pa, so that the frozen water molecules are directly sublimated and extracted, while the physically adsorbed oxygen is removed.

3. The method according to claim 2, characterized in that, The surface cryogenic vacuum purification process described in S2 also includes the following steps: S23: Immediately introduce the fiber bundle that has already adsorbed oxygen into a refill chamber filled with inert gas of 99.9999% purity, and use the inert gas atoms to occupy the high-energy adsorption sites exposed on the surface of the fiber bundle due to the desorption of impurities, forming a single-atom-level inert protective layer.

4. The high-temperature continuous carbonization molding method for high-purity silicon carbide fibers according to claim 1, characterized in that, The multi-beam tension autonomous equalization delivery described in S3 specifically includes the following steps: S31: The purified fiber bundles are passed laterally through a two-dimensional near-field acoustic levitation chamber generated by an ultrasonic transducer array, so that all fiber bundles are captured at the acoustic pressure node and suspended and transported without mechanical contact. S32: Using an acoustic sensor array arranged on the side wall of the acoustic suspension chamber, the spatial position change of each fiber in the sound field is sensed in real time. S33: Based on the positional offset of each fiber, the sound field intensity of the corresponding area is dynamically adjusted, and the sound radiation force applied to each fiber bundle is adjusted in a non-contact manner until the axial transport resistance experienced by all fiber bundles tends to be consistent, thereby achieving autonomous tension balance.

5. The high-temperature continuous carbonization molding method for high-purity silicon carbide fibers according to claim 4, characterized in that, S33 specifically includes the following steps: S331: Through the dynamic adjustment of the sound field, a controllable micro-traveling wave component is introduced into the acoustic suspension cavity, and the acoustic flow effect is used to apply a differentiated forward traction force to the non-contact suspended fiber bundle, thereby actively compensating for the fiber bundle with low tension.

6. The high-temperature continuous carbonization molding method for high-purity silicon carbide fibers according to claim 1, characterized in that, S4 specifically includes the following steps: S41: The carbonization temperature in the high-temperature carbonization furnace is 1300-1600℃, and the furnace is protected by high-purity inert gas with a purity of 99.999%. S42: The furnace tubes and wire guides of the high-temperature carbonization furnace are both made of high-purity graphite.

7. A high-purity silicon carbide fiber high-temperature continuous carbonization molding equipment, characterized in that, Along the fiber travel direction, the following are included in sequence: The unit includes a wire feeding unit, a surface cryogenic vacuum purification unit, an acoustic suspension tension decoupling conveying unit, a high-temperature carbonization unit, a surface treatment and forming unit, and a winding unit. The surface cryogenic vacuum purification unit is divided into a cryogenic chamber, a vacuum chamber, and an inert gas refill chamber along the fiber travel direction. There is a narrow channel between the three chambers for the fiber to pass through. The cryogenic chamber is connected to the liquid nitrogen supply system, the vacuum chamber is connected to the multi-stage vacuum pump group, and the inert gas refill chamber is connected to the high-purity argon gas source. The acoustic suspension tension decoupling and delivery unit is located between the surface cryogenic vacuum purification unit and the high-temperature carbonization unit. It includes a flat acoustic resonant cavity. An ultrasonic transducer array is installed on both the top and bottom plates of the resonant cavity, and a microelectromechanical microphone array for sensing fiber position is arranged on its side wall. Multiple bundles of fibers drawn from the fiber feeding unit pass through the cryogenic chamber, vacuum chamber, and inert gas refill chamber of the surface cryogenic vacuum purification unit, then laterally pass through the acoustic resonant cavity of the acoustic suspension tension decoupling delivery unit, and finally enter the inlet of the high-temperature carbonization unit.

8. A high-purity silicon carbide fiber high-temperature continuous carbonization molding equipment applied to the method described in any one of claims 1 to 7, characterized in that: The high-temperature carbonization unit is a multi-temperature zone resistance heating furnace with gradient heating function. Its furnace tube is made of high-purity graphite, and its internal wire guide is also made of high-purity graphite. The yarn feeding unit includes multiple active yarn feeding motors, each of which is linked to the microelectromechanical microphone array in the acoustic suspension tension decoupling delivery unit to form a distributed tension closed-loop control system.

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