A foldable integrally formed flexible heat transport pipe and a continuous process for its production

Abstract

The application belongs to the technical field of spacecraft thermal control, and particularly relates to a flexible heat transport pipe material capable of being folded and integrally formed and a continuous preparation process thereof. The pipe material is a polyimide fiber woven reinforced heat-conducting resin continuous pipe material, and a heat-conducting resin matrix is formed by polyimide, phosphorus-containing titanate modified gallium-based liquid metal microsphere composite heat-conducting filler and polysilazane. In the preparation, a tubular fiber framework is first woven, composite heat-conducting slurry is impregnated on line through vacuum assistance, and integrated forming is realized through multi-temperature zone gradient curing. The application modifies the resin system through multi-stage interface modification filler and silazane, and is matched with woven integrated non-segmented structure, solves the leakage and fatigue failure defects of traditional segmented pipe joints, takes into account high axial heat conduction and repeated bending flexibility, and simultaneously improves the atomic oxygen erosion resistance of the pipe material, so that the long-life and high-reliability heat transport use requirements of a large-scale deployable radiator of a spacecraft can be met.

Description

Technical Field

[0001] This invention belongs to the field of spacecraft thermal control technology, specifically relating to a foldable, integrally formed flexible heat transport pipe and its continuous manufacturing process. Background Technology

[0002] With the continuous improvement of spacecraft mission capabilities, the power density of spacecraft such as high-power communication satellites, space station platforms, and deep space probes is constantly increasing. The heat generated by their internal electronic equipment and payload systems is growing exponentially, making the thermal control system one of the key factors restricting spacecraft performance and reliability. Traditional spacecraft heat dissipation mainly relies on fixed radiators, releasing heat into the space environment through infrared radiation. However, the outer surface of spacecraft is increasingly occupied by solar arrays, communication antennas, propulsion systems, and other equipment, continuously reducing the fixed area available for heat dissipation. Simultaneously, the size limitations of the launch fairing make it difficult to simply increase the fixed radiating area. Against this backdrop, deployable radiator technology has emerged. By folding or collapsing during launch to reduce the launch envelope, and then unfolding after entering orbit to form a larger radiating area, the spacecraft's heat dissipation capacity is significantly improved. In recent years, with the development of flexible materials and lightweight structure technologies, deployable radiators are evolving from traditional rigid deployable structures to flexible deployable structures. Flexible heat transport pipelines, as the core component connecting the heat source and the radiating surface, directly affect the reliability and heat dissipation efficiency of the entire thermal control system.

[0003] In existing flexible deployable radiator technologies, flexible heat transport pipelines typically employ a segmented structural design. This involves multiple rigid pipes or flexible hoses connected in series via mechanical joints, welded joints, or flanges to allow for dynamic deformation during the radiator's folding and unfolding. For example, Chinese patent CN114084380A discloses an inflatable deployable flexible heat radiator for spacecraft, which uses a combination of rigid and flexible pipes or fully flexible series pipes, with each pipe segment fixedly connected by rigid connectors. Furthermore, Chinese patent CN121493287A discloses a commercial aerospace flexible deployment mechanism with deformable liquid metal thermal control, where flexible fluid circulation pipelines are integrated inside or on the surface of the flexible deployment mechanism body, folding and unfolding synchronously with the mechanism. While these existing solutions functionally meet the basic requirements of flexible heat transport, their piping systems generally rely on multiple pipe segments connected by joints. This segmented structure presents significant technical drawbacks in aerospace applications.

[0004] First, joints are the weakest link in the piping system. During the intense vibrations of spacecraft launch and the alternating high and low temperatures during on-orbit operation, the difference in thermal expansion coefficients of different materials can cause cyclic thermal stress at the joints. Over time, this can easily lead to seal failure and working fluid leakage. Once the heat transfer fluid leaks, the entire thermal control system risks failure, posing a serious threat to the spacecraft's on-orbit lifespan and mission reliability. Second, flexible radiators require repeated folding and unfolding operations in orbit, and the joint area is precisely where stress is most concentrated. Repeated bending can easily cause fatigue damage or even fracture. Third, existing flexible piping manufacturing processes mostly involve segmented molding followed by assembly, making it difficult to achieve ultra-long, seamless, continuous piping, thus limiting the further expansion of the radiator's heat dissipation area.

[0005] Therefore, there is an urgent need for a flexible heat transport pipe that can be integrally formed, jointless, foldable, and has excellent heat transport performance, as well as its continuous manufacturing process, in order to fundamentally solve the leakage risk and fatigue failure problems caused by segmented pipe joints, and meet the long life and high reliability requirements of high-power spacecraft for flexible deployable radiator systems. Summary of the Invention

[0006] This invention addresses the problems existing in the prior art by providing a foldable, integrally molded flexible heat transport pipe and its continuous manufacturing process. By integrating a braided reinforcement with a thermally conductive resin matrix, a jointless, continuous flexible pipe is produced, eliminating the leakage risk and fatigue failure problems caused by joints in segmented pipelines. At the same time, it endows the pipe with excellent bending flexibility and axial thermal conductivity to meet the urgent needs of flexible deployable radiators in spacecraft for long-life, high-reliability, and large-scale layout of heat transport pipelines.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The first aspect of this invention provides a foldable, integrally molded flexible heat transport pipe, wherein the pipe is a fiber-reinforced resin-based composite pipe, comprising: The fiber braided reinforcement layer is a tubular fabric skeleton formed by two-dimensional weaving of multiple fiber bundles. A thermally conductive resin matrix is ​​filled in the pores between the fiber bundles of the tubular fabric skeleton and coated on the surface of each fiber bundle, forming an integrated composite tube wall with the fiber braiding reinforcement layer. The thermally conductive resin matrix is ​​formed by curing raw materials containing the following components: (A) Polyimide resin, 100 parts by weight; (B) Composite modified thermally conductive filler, 15-35 parts by weight; the composite modified thermally conductive filler is gallium-based liquid metal microspheres modified with phosphorus titanate coupling agent; (C) Polysilazane, 1.0 to 3.0 parts by weight; The pipe is a continuous tubular structure without joints.

[0009] Furthermore, the gallium-based liquid metal is a gallium-indium alloy or a gallium-indium-tin alloy.

[0010] Further, the phosphorus-containing titanate coupling agent is at least one of isopropyl tris(dioctyl pyrophosphate) titanate, isopropyl tris(dioctyl phosphate) titanate, and isopropyl tris(stearoyl) titanate.

[0011] Furthermore, the composite modified thermally conductive filler is prepared by the following method: (a) Gallium-based liquid metal microspheres are stirred in an oxygen-containing atmosphere at 60–100 °C for 2–10 hours to generate a gallium oxide layer in situ on the surface of the liquid metal microspheres; (b) Disperse liquid metal microspheres with a gallium oxide layer on the surface in an organic solvent, add a phosphorus titanate coupling agent, the amount of the phosphorus titanate coupling agent being 0.5% to 2% of the mass of the gallium-based liquid metal microspheres, react at 40 to 80°C for 1 to 5 hours to graft the coupling agent onto the surface of the gallium oxide layer, and obtain the composite modified thermally conductive filler after washing and drying.

[0012] Further, the organic solvent in step (b) is at least one of toluene, xylene, acetone, and ethanol.

[0013] In this invention, the composite modified thermally conductive filler uses gallium-based liquid metal microspheres as its core. The gallium oxide thin layer generated in situ on its surface not only serves as a natural transition layer to constrain the morphological stability of the liquid metal during processing, but also provides ample chemical bonding sites for subsequent coupling agent modification. The alkoxy groups of the phosphorus titanate coupling agent react with the hydroxyl groups on the surface of the gallium oxide layer to form chemical bonds, creating an organic interface layer outside the filler particles. The long-chain organic portion at the other end of this interface layer has good compatibility with the polyimide matrix, enabling molecular-level interfacial bonding between the filler and the matrix. This modified structure establishes a multi-level chemical bonding network between the thermally conductive filler and the matrix, extending from the metal core through the oxide intermediate layer to the organic shell layer. This effectively reduces the interfacial thermal resistance between the filler and the matrix, while preventing the aggregation and migration of the liquid metal microspheres during resin curing. Thus, while improving the thermal conductivity of the composite material, it also ensures the structural integrity of the pipe under repeated folding conditions.

[0014] Furthermore, the polysilazane is an organopolysilazane or a perhydropolysilazane.

[0015] The addition of polysilazane serves two main purposes: firstly, as a low-viscosity component, it improves the flowability of the impregnation slurry and its wettability to the fiber braided layer; secondly, during thermosetting, polysilazane cross-links to form a Si-CN-containing network structure, which forms an interpenetrating network with the polyimide matrix. Simultaneously, the active groups in polysilazane exhibit good chemical affinity with the gallium oxide layer surface and the end groups of the polyimide molecular chains, which helps reduce the interfacial tension between the filler and the matrix and inhibits filler agglomeration. Furthermore, the inorganic ceramic phase formed by polysilazane under thermal action can improve the anti-ionic oxygen erosion resistance of the pipe surface to a certain extent. This is of positive significance for thermal control pipelines in spacecraft operating in low Earth orbit environments for extended periods. With proper control, its addition amount will not significantly adversely affect the flexibility of the pipe.

[0016] Furthermore, the fiber bundle is a polyimide fiber bundle.

[0017] Furthermore, the angle between the weaving direction of the fiber bundle and the axis of the tube is 30° to 60°.

[0018] Furthermore, the pipe has a wall thickness of 0.5–5 mm, an inner diameter of 2–20 mm, and a continuous length of 1–200 m.

[0019] The pipe of this invention adopts an integrated composite pipe wall structure of a fiber braided reinforcement layer and a thermally conductive resin matrix. The fiber braided layer acts as a flexible skeleton to bear the main stress during pipe bending, preventing cracks in the resin matrix during repeated folding. The thermally conductive resin matrix fills the braided pores and coats the fiber surface, allowing the fibers and resin to deform collaboratively under stress, resulting in a more uniform stress distribution. Simultaneously, the braiding angle is controlled between 30° and 60°, achieving a reasonable balance between longitudinal tension and radial buckling, meeting both the axial load requirements in the unfolded state and the low bending resistance in the folded state. Furthermore, this integrated pipe wall is a continuous, jointless structure, structurally eliminating stress concentration and weak sealing points caused by connectors in traditional segmented pipelines, providing a structural foundation for the long-term reliability of the pipe under repeated unfolding and retraction conditions in orbit.

[0020] The second aspect of this invention provides a manufacturing process for the aforementioned foldable, integrally formed flexible heat transport pipe, comprising the following steps: (1) Fiber weaving: Multiple fiber bundles are woven in two dimensions to form a tubular fabric skeleton. During the weaving process, the angle between the weaving direction of the fiber bundles and the axis of the tube is controlled to be 30° to 60°. (2) Preparation of impregnation slurry: Polyimide resin, composite modified thermally conductive filler and polysilazane are mixed in proportion to obtain impregnation slurry; (3) Online impregnation: The tubular fabric skeleton obtained in step (1) is continuously pulled through an impregnation tank containing impregnation slurry, so that the impregnation slurry fully wets and fills the pores between the fiber bundles of the tubular fabric skeleton and covers the surface of each fiber bundle. (4) Curing and molding: The impregnated tubular fabric skeleton is heated and cured to obtain an integrated composite pipe wall, which is the foldable integrated flexible heat transport pipe.

[0021] Further, the temperature of the impregnation tank in step (3) is 40-60°C, and the impregnation is carried out under vacuum-assisted conditions; the heating and curing in step (4) adopts a gradient heating method, and is held at 80°C, 120°C and 180°C in sequence, with a total curing time of 1.5-3 hours.

[0022] Compared with the prior art, the present invention has the following beneficial effects: This invention employs in-situ oxidation combined with gallium-based liquid metal filler modified with phosphorus titanate, along with a small amount of polysilazane to synergistically modify the polyimide matrix. This improves the interfacial bonding between the filler and the resin, inhibits filler agglomeration and migration, and effectively enhances the overall thermal conductivity and structural stability of the tube under repeated folding conditions. The integrated continuous braiding molding scheme eliminates the sealing weaknesses and stress concentration problems caused by segmented pipe connections, significantly reducing the risk of on-orbit leakage and fatigue failure. The braided skeleton can evenly distribute bending loads, ensuring good folding flexibility of the tube. The polysilazane in the system can also give the tube excellent low-orbit atomic oxygen protection performance. The entire manufacturing process can achieve continuous mass production of long-scale tubes, and is comprehensively adapted to the long-term service requirements of flexible radiators in spacecraft. Attached Figure Description

[0023] Figure 1 This is a photograph showing the appearance of the flexible heat transport pipe obtained in Example 1. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the raw materials used in the embodiments are all commercially available products. The following sources are illustrative examples.

[0025] The organopolysilazane was purchased from Anhui Aiyota Silicon Oil Co., Ltd., model IOTA 9118; the perhydropolysilazane was purchased from Anhui Aiyota Silicon Oil Co., Ltd., model IOTA-PHPS.

[0026] Example 1 This embodiment provides a foldable, integrally formed flexible heat transport pipe, the manufacturing process of which includes the following steps: (I) Preparation of composite modified thermally conductive fillers: (a) Gallium indium tin alloy liquid metal microspheres with an average particle size of 5 μm (melting point 12 °C) were placed in an air atmosphere and stirred at 80 °C for 6 hours to generate a gallium oxide layer in situ on the surface of the liquid metal microspheres. (b) Liquid metal microspheres with gallium oxide layer on the surface are dispersed in toluene, and isopropyltris(dioctylpyrophosphate)titanate coupling agent is added. The amount of coupling agent is 1.0% of the mass of gallium-based liquid metal microspheres. The reaction is carried out at 60°C for 3 hours to graft the coupling agent onto the surface of gallium oxide layer. After washing and drying, a composite modified thermally conductive filler is obtained.

[0027] (II) Pipe preparation: (1) Fiber weaving: Polyimide fiber bundles (monofilament diameter 10μm) are woven in two dimensions on a weaving machine to form a tubular fabric skeleton. During the weaving process, the angle between the weaving direction of the fiber bundle and the axis of the tube is controlled to be 45°, and the weaving traction speed is 2m / h. (2) Preparation of impregnation slurry: Mix 100 parts by weight of thermosetting polyimide resin, 22 parts by weight of the above-mentioned composite modified thermally conductive filler and 1.5 parts by weight of organopolysilazane evenly to obtain impregnation slurry; (3) Online impregnation: The tubular fabric skeleton obtained in step (1) is continuously pulled through an impregnation tank containing the above impregnation slurry. The temperature of the impregnation tank is 50°C. Impregnation is carried out under vacuum-assisted conditions so that the impregnation slurry can fully wet and fill the pores between the fiber bundles of the tubular fabric skeleton and cover the surface of each fiber bundle. (4) Curing and molding: The impregnated tubular fabric skeleton is continuously pulled through a multi-temperature zone continuous curing oven. The temperature is increased in a gradient manner, and the polyimide resin is kept in the 80°C preheating zone for 30 minutes, the 120°C gel zone for 30 minutes, and the 180°C curing zone for 60 minutes in sequence to crosslink and cure the polyimide resin, thereby obtaining an integrated composite pipe wall, which is the foldable integrated flexible heat transport pipe.

[0028] The flexible heat transport pipe manufactured in this embodiment has a wall thickness of 2mm, an inner diameter of 8mm, and a continuous length of 50m. Its appearance is shown in the attached figure. Figure 1 As shown.

[0029] Example 2 This embodiment provides a foldable, integrally formed flexible heat transport pipe, the manufacturing process of which includes the following steps: (I) Preparation of composite modified thermally conductive fillers: (a) Gallium-indium alloy liquid metal microspheres with an average particle size of 12 μm (melting point 16 °C) were placed in an air atmosphere and stirred at 70 °C for 8 hours to generate a gallium oxide layer in situ on the surface of the liquid metal microspheres. (b) Liquid metal microspheres with gallium oxide layer on the surface are dispersed in toluene, and isopropyl tris(dioctylphosphoyloxy)titanate coupling agent is added. The amount of coupling agent is 1.5% of the mass of gallium-based liquid metal microspheres. The reaction is carried out at 50°C for 4 hours to graft the coupling agent onto the surface of gallium oxide layer. After washing and drying, a composite modified thermally conductive filler is obtained.

[0030] (II) Pipe preparation: (1) Fiber weaving: Polyimide fiber bundles (monofilament diameter 10μm) are woven in two dimensions on a weaving machine to form a tubular fabric skeleton. During the weaving process, the angle between the weaving direction of the fiber bundle and the axis of the tube is controlled to be 35°, and the weaving traction speed is 3m / h. (2) Preparation of impregnation slurry: Mix 100 parts by weight of thermosetting polyimide resin, 18 parts by weight of the above-mentioned composite modified thermally conductive filler and 2.2 parts by weight of perhydropolysilazane evenly to obtain impregnation slurry; (3) Online impregnation: The tubular fabric skeleton obtained in step (1) is continuously pulled through an impregnation tank containing the above impregnation slurry. The temperature of the impregnation tank is 45°C. Impregnation is carried out under vacuum-assisted conditions so that the impregnation slurry can fully wet and fill the pores between the fiber bundles of the tubular fabric skeleton and cover the surface of each fiber bundle. (4) Curing and molding: The impregnated tubular fabric skeleton is continuously pulled through a multi-temperature zone continuous curing oven. The temperature is increased in a gradient manner, and the polyimide resin is kept in the 80℃ preheating zone for 20 minutes, the 120℃ gelation zone for 30 minutes, and the 180℃ curing zone for 50 minutes in sequence to crosslink and cure the polyimide resin, thereby obtaining an integrated composite pipe wall, which is the foldable integrated flexible heat transport pipe.

[0031] The flexible heat transport pipe prepared in this embodiment has a wall thickness of 3mm, an inner diameter of 5mm, and a continuous length of 80m.

[0032] Example 3 This embodiment provides a foldable, integrally formed flexible heat transport pipe, the manufacturing process of which includes the following steps: (I) Preparation of composite modified thermally conductive fillers: (a) Gallium indium tin alloy liquid metal microspheres with an average particle size of 5 μm (melting point 12 °C) were placed in an air atmosphere and stirred at 90 °C for 4 hours to generate a gallium oxide layer in situ on the surface of the liquid metal microspheres. (b) Liquid metal microspheres with gallium oxide layer on the surface are dispersed in toluene, and isopropyl tris(stearoyl) titanate coupling agent is added. The amount of coupling agent is 0.8% of the mass of gallium-based liquid metal microspheres. The reaction is carried out at 70°C for 2 hours to graft the coupling agent onto the surface of gallium oxide layer. After washing and drying, a composite modified thermally conductive filler is obtained.

[0033] (II) Pipe preparation: (1) Fiber weaving: Polyimide fiber bundles (monofilament diameter 10μm) are woven in two dimensions on a weaving machine to form a tubular fabric skeleton. During the weaving process, the angle between the weaving direction of the fiber bundle and the axis of the tube is controlled to be 55°, and the weaving traction speed is 4m / h. (2) Preparation of impregnation slurry: Mix 100 parts by weight of thermosetting polyimide resin, 28 parts by weight of the above-mentioned composite modified thermally conductive filler and 1.2 parts by weight of organopolysilazane evenly to obtain impregnation slurry; (3) Online impregnation: The tubular fabric skeleton obtained in step (1) is continuously pulled through an impregnation tank containing the above impregnation slurry. The temperature of the impregnation tank is 55°C. Impregnation is carried out under vacuum-assisted conditions so that the impregnation slurry can fully wet and fill the pores between the fiber bundles of the tubular fabric skeleton and cover the surface of each fiber bundle. (4) Curing and molding: The impregnated tubular fabric skeleton is continuously pulled through a multi-temperature zone continuous curing oven. The temperature is increased in a gradient manner, and the polyimide resin is kept in the 80°C preheating zone for 40 minutes, the 120°C gel zone for 25 minutes, and the 180°C curing zone for 45 minutes in sequence to crosslink and cure the polyimide resin, thereby obtaining an integrated composite pipe wall, which is the foldable integrated flexible heat transport pipe.

[0034] The flexible heat transport pipe prepared in this embodiment has a wall thickness of 1.5 mm, an inner diameter of 12 mm, and a continuous length of 100 m.

[0035] Comparative Example 1 The difference between this comparative example and Example 1 is that the composite modified thermally conductive filler is replaced with silane-modified gallium-based liquid metal filler. The preparation method of the silane-modified gallium-based liquid metal filler is as follows: (a) Take gallium indium tin alloy liquid metal microspheres with an average particle size of 5 μm and a melting point of 12 °C, without pre-oxidation treatment; (b) Disperse liquid metal microspheres in toluene, add 1.0% by mass of KH-550 aminosilane coupling agent, react at 60°C for 3 h, wash and dry to obtain silane-modified gallium-based liquid metal filler.

[0036] Everything else is the same as in Example 1.

[0037] Comparative Example 2 The difference between this comparative example and Example 1 is that the composite modified thermally conductive filler is replaced with an equal mass of hexagonal boron nitride (h-BN) thermally conductive filler. All other aspects are the same as in Example 1.

[0038] Comparative Example 3 The difference between this comparative example and Example 1 is that the organopolysilazane is replaced with an equal part by mass of methylphenylpolysiloxane. All other aspects are the same as in Example 1.

[0039] Comparative Example 4 The difference between this comparative example and Example 1 is that the organopolysilazane is replaced with an equal part by mass of aminosilane KH-550. All other aspects are the same as in Example 1.

[0040] Performance testing Test samples: Foldable integrated flexible heat transport pipes prepared in each embodiment and comparative example. All samples were cut from the middle stable forming section to eliminate end forming defects.

[0041] Test method: 1. Thermal conductivity of the pipe (axial room temperature thermal conductivity) Long strip samples were cut along the axial direction of the pipe at room temperature of 25℃ and tested using a one-dimensional axial steady-state heat flow device. The heat flow was conducted unidirectionally along the length of the pipe to obtain the effective axial thermal conductivity of the pipe.

[0042] 2. Repeated bending fatigue performance The test was conducted according to the general test criteria for cyclic fatigue in GB / T 35465.5-2020 "Test Methods for Fatigue Properties of Polymer-Based Composite Materials Part 5: Bending Fatigue". A special reciprocating bending tester with two clamps was used to adapt to the tubular flexible tube of this invention. The two ends of the sample were rigidly fixed. The span was 16 times the outer diameter of the tube. The reciprocating bending angle was ±90° and the bending frequency was 30 times / min. The constant frequency cyclic loading was continuously applied, and the cracks, delamination and internal working fluid leakage of the sample were observed simultaneously. The number of cycles corresponding to the first occurrence of any defect was the number of fatigue failures.

[0043] 3. Pipe air tightness According to GB / T 15820-2019 "Test Method for Air Tightness of Plastic Pressure Piping Systems", the pipe is filled with 0.5MPa of dry air, and the pressure is maintained for 30 minutes to test the overall gas leakage rate of the pipe.

[0044] 4. Mass loss rate due to atomic oxygen erosion Referring to GJB 2502.9-2020 "Test Methods for Thermal Control Coatings of Spacecraft - Part 9: Atomic Oxygen Test", the atomic oxygen flux was 5.0 × 10⁻⁶. 20 atoms / cm 2The test was conducted under the specified conditions to measure the mass loss rate per unit area of ​​the sample. The lower the value, the better the resistance to atomic oxygen.

[0045] 5. Pipe bending stiffness Referring to GB / T 1449-2005 "Test Method for Bending Properties of Fiber Reinforced Plastics", the bending elastic modulus of the pipe was tested using a three-point bending loading method. The span was 16 times the outer diameter of the pipe. The lower the modulus, the better the bending flexibility of the pipe and the smaller the folding resistance.

[0046] The test results are shown in Table 1.

[0047] Table 1 Performance Test Results

[0048] The test results above show that the flexible heat transport pipes prepared in Examples 1-3 of this invention have excellent axial thermal conductivity, bending fatigue stability, airtight sealing and space environment tolerance. The performance indicators are synergistic and balanced, and can effectively adapt to the long-term on-orbit service conditions of flexible deployable radiators in spacecraft.

[0049] Comparative Example 1 uses conventional silane coupling agents to modify liquid metal without constructing an in-situ gallium oxide transition layer. This results in the inability to form a stable multi-level chemically bonded interface structure, poor compatibility between the filler and the resin matrix, high interfacial thermal resistance, and the tendency of liquid metal microspheres to agglomerate and migrate, ultimately leading to an overall deterioration in the pipe's thermal conductivity, fatigue resistance, and airtightness. Comparative Example 2 uses traditional hexagonal boron nitride solid thermally conductive filler instead of gallium-based liquid metal filler. This type of solid ceramic filler struggles to form continuous and stable thermal conduction pathways, and these pathways are prone to breakage during repeated bending of the pipe. It fails to balance high thermal conductivity with structural flexibility, significantly reducing the pipe's overall thermal transport and mechanical durability. Comparative Example 3 uses polysiloxane instead of polysilazane. However, polysiloxane cannot achieve interfacial bridging or auxiliary cross-linking or interpenetrating network effects between the filler and the matrix, nor can it form a protective inorganic ceramic phase under thermal conditions. This not only fails to optimize interfacial heat transfer but also significantly reduces the pipe's resistance to atomic oxygen attack, resulting in a substantial decrease in its space service stability. Comparative Example 4 introduced a small molecule silane coupling agent to replace the large molecule polysilazane. The small molecule silane can only achieve simple surface modification and cannot be uniformly distributed in the matrix to build a full-domain cross-linking system, resulting in a significant deterioration in the overall performance of the pipe.

[0050] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A foldable, integrally molded flexible heat transport pipe, characterized in that, The pipe is a fiber-reinforced resin-based composite pipe, comprising: The fiber braided reinforcement layer is a tubular fabric skeleton formed by two-dimensional weaving of multiple fiber bundles. A thermally conductive resin matrix is ​​filled in the pores between the fiber bundles of the tubular fabric skeleton and coated on the surface of each fiber bundle, forming an integrated composite tube wall with the fiber braiding reinforcement layer. The thermally conductive resin matrix is ​​formed by curing raw materials containing the following components: (A) Polyimide resin, 100 parts by weight; (B) Composite modified thermally conductive filler, 15-35 parts by weight; the composite modified thermally conductive filler is gallium-based liquid metal microspheres modified with phosphorus titanate coupling agent; (C) Polysilazane, 1.0 to 3.0 parts by weight; The pipe is a continuous tubular structure without joints.

2. The foldable, integrally formed flexible heat transport pipe according to claim 1, characterized in that, The gallium-based liquid metal is a gallium-indium alloy or a gallium-indium-tin alloy.

3. The foldable, integrally formed flexible heat transport pipe according to claim 1, characterized in that, The phosphorus-containing titanate coupling agent is at least one of isopropyl tris(dioctyl pyrophosphoryloxy) titanate, isopropyl tris(dioctyl phosphoryloxy) titanate, and isopropyl tris(stearoyl) titanate.

4. The foldable, integrally formed flexible heat transport pipe according to claim 1, characterized in that, The composite modified thermally conductive filler is prepared by the following method: (a) Gallium-based liquid metal microspheres are stirred in an oxygen-containing atmosphere at 60–100 °C for 2–10 hours to generate a gallium oxide layer in situ on the surface of the liquid metal microspheres; (b) Disperse liquid metal microspheres with a gallium oxide layer on the surface in an organic solvent, add a phosphorus titanate coupling agent, the amount of the phosphorus titanate coupling agent being 0.5% to 2% of the mass of the gallium-based liquid metal microspheres, react at 40 to 80°C for 1 to 5 hours to graft the coupling agent onto the surface of the gallium oxide layer, and obtain the composite modified thermally conductive filler after washing and drying.

5. The foldable, integrally formed flexible heat transport pipe according to claim 1, characterized in that, The polysilazane is an organopolysilazane or a perhydropolysilazane.

6. The foldable, integrally formed flexible heat transport pipe according to claim 1, characterized in that, The fiber bundle is a polyimide fiber bundle.

7. The foldable, integrally formed flexible heat transport pipe according to claim 1, characterized in that, The angle between the braiding direction of the fiber bundle and the axis of the tube is 30° to 60°.

8. The foldable, integrally formed flexible heat transport pipe according to claim 1, characterized in that, The pipe has a wall thickness of 0.5–5 mm, an inner diameter of 2–20 mm, and a continuous length of 1–200 m.

9. The manufacturing process of the foldable, integrally formed flexible heat transport pipe according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Fiber weaving: Multiple fiber bundles are woven in two dimensions to form a tubular fabric skeleton. During the weaving process, the angle between the weaving direction of the fiber bundles and the axis of the tube is controlled to be 30° to 60°. (2) Preparation of impregnation slurry: Polyimide resin, composite modified thermally conductive filler and polysilazane are mixed in proportion to obtain impregnation slurry; (3) Online impregnation: The tubular fabric skeleton obtained in step (1) is continuously pulled through an impregnation tank containing impregnation slurry, so that the impregnation slurry fully wets and fills the pores between the fiber bundles of the tubular fabric skeleton and covers the surface of each fiber bundle. (4) Curing and molding: The impregnated tubular fabric skeleton is heated and cured to obtain an integrated composite pipe wall, which is the foldable integrated flexible heat transport pipe.

10. The preparation process according to claim 9, characterized in that, The temperature of the impregnation tank in step (3) is 40-60℃, and the impregnation is carried out under vacuum-assisted conditions; the heating and curing in step (4) adopts a gradient heating method, and is held at 80℃, 120℃ and 180℃ in sequence, with a total curing time of 1.5-3 hours.

Images