Functional gradient composite structural member and preparation method thereof

Abstract

The invention provides a functionally gradient composite structural member and a preparation method thereof. The structural member comprises a high-thermal-conductivity functional area and a controllable electromagnetic functional area which are spatially separated and distributed, are respectively composed of a high-thermal-conductivity functional layer and a controllable electromagnetic functional layer, and can integrate a core structural layer and a functional gradient interface packaging layer. The preparation method comprises the steps of planning a functional area according to a heat source and antenna layout; preparing a functional gradient preform through yarn weaving, prepreg laying or dry fabric laying; resin infiltration and curing are carried out by adopting a resin transfer molding, hot-pressing co-curing or vacuum-assisted introduction process, so that integrated molding is realized. The problems that heat dissipation and electromagnetic functions are difficult to give consideration to and the integration degree is low are solved, and function collaborative optimization and high-performance integrated preparation are achieved.

Description

Technical Field

[0001] This invention relates to the field of functional composite materials and structural integration technology, and in particular to a functionally graded composite structural component and its preparation method. Background Technology

[0002] As high-end equipment in aerospace, electronic communications, and other fields develops towards miniaturization and high performance, increasingly higher demands are being placed on the thermal management capabilities and electromagnetic compatibility of structural materials. In traditional designs, heat dissipation structures and wave-transmitting / electromagnetic control structures are often designed and manufactured independently, and then integrated through mechanical connections or adhesive bonding. This results in increased overall structural weight, discontinuous heat transfer paths, and electromagnetic performance that is susceptible to interface interference. Furthermore, the manufacturing process is complex and reliability is limited.

[0003] In existing technologies, although there have been attempts to use composite materials for integrated molding, most of them use functional homogeneous materials or simple layered designs, which make it difficult to achieve a "spatially separated" functional distribution with high thermal conductivity and low dielectric loss in the same structural component. This results in mutual interference between the heat dissipation area and the electromagnetic functional area, making it impossible to achieve both efficient heat conduction and good electromagnetic wave transmission performance.

[0004] This application solves the technical problems of existing technologies, such as difficulty in balancing heat dissipation and electromagnetic functions, low structural integration, and weak interface performance, by designing a functionally graded composite structural component that spatially separates the high thermal conductivity functional area and the controllable electromagnetic functional area within the structure and combines multiple integrated molding processes. Summary of the Invention

[0005] This invention provides a functionally graded composite structural component and its preparation method, which solves the technical problems of low integration, heavy weight, poor interface performance, and mutual interference of functions caused by the separate design of heat dissipation structure and electromagnetic functional structure in the prior art.

[0006] On the one hand, the present invention provides a functionally graded composite structure, comprising at least one high thermal conductivity functional layer and at least one controllable electromagnetic functional layer stacked together; The high thermal conductivity functional layer constitutes the high thermal conductivity functional region of the structural component, and its in-plane thermal conductivity is higher than that of other regions of the structural component. The controllable electromagnetic functional layer constitutes the controllable electromagnetic functional area of ​​the structure, and its dielectric loss in a specific electromagnetic frequency band is lower than that in other areas of the structure. The high thermal conductivity functional area and the controllable electromagnetic functional area are spatially separated within the structural component.

[0007] According to the present invention, a functionally graded composite structural component further includes a core structural layer, which is composed of a high-performance fiber-reinforced composite material and provides mechanical support for the high thermal conductivity functional layer and the controllable electromagnetic functional layer.

[0008] According to the present invention, a functionally graded composite structure further includes an interface encapsulation layer disposed on the outer surface of the core structural layer, the high thermal conductivity functional layer, and the controllable electromagnetic functional layer; wherein, the portion of the interface encapsulation layer above the high thermal conductivity functional region is a high thermal conductivity insulating medium, and the portion of the interface encapsulation layer above the controllable electromagnetic functional region is a low dielectric loss medium.

[0009] According to a functionally graded composite structural component provided by the present invention, the high thermal conductivity functional layer comprises a continuous fiber reinforced composite material, wherein the continuous fiber is selected from pitch-based carbon fiber or high thermal conductivity silicon carbide fiber; the in-plane thermal conductivity of the high thermal conductivity functional layer is not less than 10 W / (m·K).

[0010] According to the present invention, a functionally graded composite structural component is provided, wherein the controllable electromagnetic functional layer comprises a fiber-reinforced composite material, and the volume resistivity of the fibers is 10⁻⁶. 1 Ω·cm to 10 5 Within the range of Ω·cm; the insertion loss of the controllable electromagnetic functional region for 28GHz electromagnetic waves is no higher than -3.0dB.

[0011] On the other hand, the present invention provides a method for preparing a functionally graded composite structural component, comprising the following steps: (1) Based on the layout of the heat source and the antenna, a spatially separated high thermal conductivity functional area and a controllable electromagnetic functional area are planned; (2) Prepare a functionally graded preform corresponding to the planning, which includes the high thermal conductivity functional region and the controllable electromagnetic functional region; (3) The functional gradient preform is impregnated with a resin matrix and then cured to form a functional gradient composite structure.

[0012] According to the method for preparing a functionally graded composite structure provided by the present invention, in step (2), the functionally graded preform is integrally woven by a yarn weaving process.

[0013] According to the method for preparing a functionally graded composite structure provided by the present invention, in step (2), the functionally graded preform is formed by layering and splicing high thermal conductivity prepreg and controllable electromagnetic prepreg in sections.

[0014] According to the method for preparing a functionally graded composite structure provided by the present invention, in step (2), the functionally graded preform is formed by fixing a high thermal conductivity dry fiber fabric and a controllable electromagnetic dry fiber fabric by laying them in sections.

[0015] According to the method for preparing a functionally graded composite structural component provided by the present invention, in step (3), the curing process is one of hot-press co-curing, resin transfer molding curing, or vacuum-assisted induction curing.

[0016] The functionally graded composite structural component and its fabrication method provided by this invention have the following advantages compared with the prior art: (1) The present invention provides a functional gradient composite structure and its preparation method. By spatially separating the high thermal conductivity functional area and the controllable electromagnetic functional area inside the structure, the heat dissipation and electromagnetic wave transmission / control functions are optimized in a coordinated manner, avoiding mutual interference between functions and significantly improving the functional integration and comprehensive performance of the structure.

[0017] (2) The present invention provides a functional gradient composite structural component and its preparation method, which supports various preform preparation methods such as yarn weaving, prepreg layup, and dry fabric layup, and is matched with molding processes such as hot pressing co-curing, RTM, and VARI. The preparation path is flexible and can adapt to application scenarios with different batch sizes, costs and performance requirements.

[0018] (3) The functional gradient composite structural component and its preparation method provided by the present invention ensure that the original interface of chemical bonding is formed between different functional layers through resin system design and step curing process, which greatly improves the interlayer bonding strength and interface thermal / electrical properties, and realizes true integrated molding.

[0019] (4) The present invention provides a functionally graded composite structure and its preparation method, which can be equipped with a functionally graded interface encapsulation layer and apply a high thermal conductivity insulating or low dielectric loss medium to the surface of different functional areas, thereby further improving the durability, environmental adaptability and long-term reliability of the structure.

[0020] (5) The present invention provides a functionally graded composite structural component and its preparation method. The structural component, while maintaining light weight and high strength, also has excellent in-plane thermal conductivity (≥10W / (m·K)) and low insertion loss (≤-3.0dB) at a specific frequency band (e.g., 28GHz). It is suitable for integrated load-bearing structures with stringent requirements for thermal / electromagnetic performance. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the overall architecture of a functionally graded composite structural component provided by the present invention; Figure 2 This is an exploded view of a typical structure of a functionally graded composite structural component provided by the present invention; Figure 3 This is a process flow diagram of a method for preparing a functionally graded composite structural component provided by the present invention; Figure 4 This is a schematic diagram of the yarn weaving structure of a functionally graded composite structural component provided in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the autoclave molding process for a functionally graded composite structural component provided in Embodiment 2 of the present invention.

[0023] Figure label: 1. High thermal conductivity functional area; 2. Controllable electromagnetic functional area; 3. Interface encapsulation layer; 4. High thermal conductivity functional layer; 5. Controllable electromagnetic functional layer; 6. Core structure layer; 7. Transition zone; 8. Weft yarn; 9. Warp yarn. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] The following is combined with Figures 1-5 This invention describes a functionally graded composite structural component and its preparation method.

[0026] Figure 1 This is a schematic diagram of the overall architecture of a functionally graded composite structural component provided by the present invention; Figure 2 This is an exploded view of a typical structure of a functionally graded composite structural component provided by the present invention.

[0027] like Figure 1 and Figure 2 As shown, the present invention provides a functionally graded composite structural component, comprising at least one high thermal conductivity functional layer 4 and at least one controllable electromagnetic functional layer 5 stacked together; the high thermal conductivity functional layer 4 constitutes the high thermal conductivity functional region 1 of the structural component, and its in-plane thermal conductivity is higher than that of other regions of the structural component; the controllable electromagnetic functional layer 5 constitutes the controllable electromagnetic functional region 2 of the structural component, and its dielectric loss at a specific electromagnetic frequency band is lower than that of other regions of the structural component; the high thermal conductivity functional region 1 and the controllable electromagnetic functional region 2 are spatially separated within the structural component.

[0028] In this invention, a core structural layer 6 is also included. The core structural layer 6 is composed of high-performance fiber-reinforced composite material, which provides mechanical support for the high thermal conductivity functional layer 4 and the controllable electromagnetic functional layer 5.

[0029] In this invention, an interface encapsulation layer 3 is also included, which is disposed on the outer surface of the core structure layer 6, the high thermal conductivity functional layer 4 and the controllable electromagnetic functional layer 5; wherein, the portion of the interface encapsulation layer 3 above the high thermal conductivity functional region 1 is a high thermal conductivity insulating medium, and the portion of the interface encapsulation layer 3 above the controllable electromagnetic functional region 2 is a low dielectric loss medium.

[0030] In this invention, the high thermal conductivity functional layer 4 comprises a continuous fiber reinforced composite material, wherein the continuous fiber is selected from pitch-based carbon fiber or high thermal conductivity silicon carbide fiber; the in-plane thermal conductivity of the high thermal conductivity functional layer 4 is not less than 10 W / (m·K).

[0031] In this invention, the controllable electromagnetic functional layer 5 comprises a fiber-reinforced composite material, wherein the volume resistivity of the fibers is 10⁻⁶. 1 Ω·cm to 10 5 Within the range of Ω·cm; the insertion loss of the controllable electromagnetic functional region 2 for 28GHz electromagnetic waves is no higher than -3.0dB.

[0032] Figure 3 This is a process flow diagram of a method for preparing a functionally graded composite structural component provided by the present invention.

[0033] like Figure 3 As shown, the present invention provides a method for preparing a functionally graded composite structure, comprising the following steps: (1) planning a spatially separated high thermal conductivity functional region 1 and a controllable electromagnetic functional region 2 according to the layout of the heat source and the antenna; (2) preparing a functionally graded preform corresponding to the planning and containing the high thermal conductivity functional region 1 and the controllable electromagnetic functional region 2; (3) impregnating the functionally graded preform with a resin matrix and molding it into a functionally graded composite structure through a curing process.

[0034] In this invention, in step (2), the functionally graded preform is integrally woven using a yarn weaving process. First, using textile equipment such as a doubling machine, high thermal conductivity fibers and electromagnetic functional fibers are twisted together to prepare a composite functional yarn possessing both properties. Subsequently, a large fabric with predetermined zones is directly woven on a loom by precisely controlling the distribution of different yarns. Its main implementation modes include: weft yarn zone design, that is, keeping the warp yarns unchanged, introducing specific types of weft yarns in specific areas according to the functional zone layout during the weaving process; and structure variation design, that is, without changing the yarn type, but by changing the local weaving structure (such as plain weave, twill weave, satin weave) to regulate the density, thickness, and fiber orientation of the material, thereby achieving gradient control of thermal and electromagnetic properties. Thus, the continuity of functions and seamless integration of materials are achieved at the textile level, directly obtaining a functionally graded fabric as a preform.

[0035] In this invention, in step (2), the functionally graded preform is formed by layering and splicing high thermal conductivity prepreg and controllable electromagnetic prepreg in sections. First, prepreg for the high thermal conductivity functional area and prepreg for the controllable electromagnetic functional area are prepared separately. The prepregs are made by solution impregnation or hot-melt method to ensure that the fibers are fully impregnated with resin and reach a pre-cured state. Then, according to the shape and area of ​​the functional areas defined by the computer-aided design model, the two types of prepregs are precisely cut. Finally, in the mold, the cut prepregs with different functions are precisely layered and spliced ​​in a "puzzle-like" manner to form the functionally graded preform.

[0036] In this invention, in step (2), the functionally graded preform is formed by fixing a high thermal conductivity dry fiber fabric and a controllable electromagnetic dry fiber fabric in a zoned layup. First, according to the design, dry continuous fiber fabric for the high thermal conductivity zone and dry continuous fiber fabric for the controllable electromagnetic zone are cut separately. Then, in a mold, the cut dry fiber fabrics with different functions are precisely laid up according to the predetermined functional zone layout. During or after the layup process, temporary adhesives or sewing techniques can be used for fixing, thereby forming a structurally stable dry functionally graded preform.

[0037] In this invention, in step (3), the curing process is one of hot-press co-curing, resin transfer molding curing, or vacuum-assisted curing. If hot-press co-curing is used, it corresponds to the prepreg route. The specific steps are: after the prepreg is laid in a mold, under heating and pressurization, the resin in the prepreg melts, flows, and finally cross-links and cures, firmly bonding all functional layers into a dense whole. If resin transfer molding curing is used, it mainly corresponds to the dry preform route. The specific steps are: the dry preform is placed in a sealed mold, and low-viscosity resin is injected into the mold under pressure to completely impregnate the preform, followed by heating and curing in the mold. If vacuum-assisted curing is used, it also mainly corresponds to the dry preform route. The specific steps are: under vacuum negative pressure, the resin is introduced and completely impregnates the dry preform laid in the mold, followed by heating and curing.

[0038] In this invention, to ensure integrated fabrication and the formation of excellent interfaces during hot pressing, the resin matrix used for each functional layer must possess a compatible curing mechanism and a matching curing kinetic window. Therefore, this invention provides two main resin systems and process design approaches.

[0039] On the one hand, a chemical copolymer compatibility system can be adopted, that is, each functional layer preferably adopts a resin system with the same curing mechanism or that can undergo copolymerization reaction.

[0040] In a preferred embodiment of the present invention, an epoxy-cyanate hybrid system can be specifically employed, such as using cyanate-modified epoxy resin or epoxy resin-cyanate blend resin. Under the action of a catalyst (such as a transition metal chelate), the cyanate group (-OCN) can either self-polymerize to form a triazine ring network or copolymerize with epoxy groups to form an oxazolidinone structure, ultimately forming a uniform interpenetrating copolymer network and achieving strong interfacial bonding at the molecular level.

[0041] In another, more direct preferred embodiment of the present invention, each functional layer uses the same type of high-performance epoxy resin, cyanate ester resin or bismaleimide resin, which can essentially eliminate interface compatibility problems.

[0042] On the other hand, when different functional layers require the use of resins with different curing properties (such as standard epoxy and pure cyanate ester), a stepped curing compatibility system can be designed.

[0043] In this invention, the specific curing process is a multi-stage stepped curing procedure: First, the epoxy resin is held at a first curing temperature T1 (e.g., 150℃-180℃) for a time t1 to allow it to fully gel and initially cure, while simultaneously allowing the cyanate ester resin to begin prepolymerization. Then, the temperature is raised to a second curing temperature T2 (e.g., 220℃-250℃) and held for a time t2 to allow the cyanate ester resin to fully react and form a highly cross-linked triazine ring network, and to allow the epoxy resin to fully post-cur. This process achieves macroscopic integral molding by meeting the curing requirements of different resins at different stages.

[0044] Regardless of the system and process used, the ultimate goal is to ensure that the resin molecular chains are connected to each other through chemical covalent bonds at the interfaces of different functional layers, forming a native chemical interface with extremely low interfacial thermal resistance and extremely high interfacial shear strength.

[0045] In this invention, the preparation of functionally graded yarns is a key foundation for yarn weaving. Specifically, one or more strands of high thermal conductivity fiber can be twisted together with one or more strands of electromagnetic functional fiber using textile equipment such as a doubling machine to prepare a composite functional yarn that combines the properties of both fibers, providing a material basis for subsequent functionally graded fabric weaving.

[0046] In this invention, when a yarn weaving path is used, the warp system constitutes the "core structural layer" of the functionally graded composite structure. Silicon carbide multifilaments can be selected as the warp yarns that run through the entire fabric. While providing the main body stiffness and strength, their semiconductor properties also make them an "electromagnetically compatible friendly" basic platform, fundamentally avoiding the serious electromagnetic shielding problems caused by using good conductor fibers.

[0047] In this invention, the requirements for fiber resistivity in different functional zones are determined based on the priority of their functions: for the controllable electromagnetic zone, the fiber resistivity is a core functional parameter and must be precisely controlled within 10. 2 -10 4 Within a preferred range of Ω·cm, optimal wave transmission performance is achieved; for the structural reinforcement region, the resistivity of its fibers is a compatibility parameter, preferably also within the semiconductor range, as long as it does not exhibit good conductor characteristics (i.e., resistivity not much lower than 10). 2 The basic requirements can be met by Ω·cm.

[0048] In a preferred embodiment of the invention, the warp density and weft density of the functionally graded fabric can each be independently selected within the range of 5 threads / cm to 60 threads / cm. To achieve the best balance between mechanical properties, resin impregnation efficiency, and in-plane functional properties, the preferred range for warp density and weft density is 15 threads / cm to 40 threads / cm.

[0049] Example 1 This embodiment provides a method for preparing functionally graded composite structural components based on weft yarn partitioning weaving and resin transfer molding (RTM), specifically illustrating the path of preparing a preform through yarn weaving and integrating it with the RTM process for integrated molding.

[0050] 1. Preform Preparation: Weaving of Functionally Graded Fabrics Yarn system: 600Tex silicon carbide multifilament yarn is used as the warp yarn, with a warp density of 25 yarns / cm, forming a stable skeleton throughout the fabric. In the heat dissipation zone, 800Tex pitch-based carbon fiber multifilament is introduced as the high thermal conductivity weft yarn; in the signal transmission zone, 600Tex semiconductor silicon carbide multifilament yarn (volume resistivity approximately 5×10⁻⁶) is introduced. 2 Ω·cm) is used as a controllable electromagnetic weft yarn.

[0051] Weaving and Zoning Control: The fabric is woven on a CNC rapier loom according to a pre-programmed functional zone layout. To achieve consistent thickness, a five-end satin weave is used in the high thermal conductivity zone, with a weft density of 18 threads / cm; a plain weave is used in the controllable electromagnetic zone, with a weft density of 22 threads / cm. A transition zone of approximately 5 mm wide is set at the boundary between functional zones, and performance gradual changes are achieved through alternating weft insertion. In this way, a dry-state functional gradient fabric prefabricated with predetermined functional zones is woven integrally.

[0052] 2. Resin impregnation and integrated molding curing The above-mentioned fabric preform is placed in a preheated mold and molded using resin transfer molding (RTM) process.

[0053] After mold closing, the pre-degassed epoxy resin system is injected into the mold cavity under an injection pressure of 0.6 MPa to ensure complete impregnation.

[0054] After the resin is filled, the mold clamping pressure is increased to 20 MPa, and the curing procedure is executed: the temperature is increased to 125°C at a rate of 2°C / min, and the temperature and pressure are maintained at 125°C for 120 minutes to achieve complete curing of the resin.

[0055] 3. Post-processing and performance After curing, the parts are demolded and then precision-machined by CNC to obtain the final structural components.

[0056] Testing revealed that the in-plane thermal conductivity of the high thermal conductivity functional zone of this structural component is no less than 15 W / (m·K), and the insertion loss of the controllable electromagnetic functional zone for 28 GHz electromagnetic waves is no higher than -2.5 dB. The overall thickness is uniform, and the interlaminar shear strength is greater than 25 MPa, meeting the requirements for integrated structural load-bearing and functional performance.

[0057] Example 2 This embodiment provides an integrated molding method based on prepreg layup and autoclave curing, specifically illustrating the path to achieve integrated co-curing through prepreg layup and autoclave processes.

[0058] 1. Preform Preparation: Cutting and Laying of Functionally Graded Prepregs Material Preparation: Two types of prepregs were prepared. The first was a high thermal conductivity prepreg, made by impregnating 800Tex pitch-based carbon fiber plain weave fabric with medium-temperature curing epoxy resin (resin content 36-40% by mass). The second was a controllable electromagnetic prepreg, made from 600Tex semiconductor silicon carbide fiber plain weave fabric (resistivity approximately 5 × 10⁻⁶). 2 It is made by impregnating the same type of epoxy resin with Ω·cm.

[0059] Precision lay-up: Based on the functional area layout diagram, the two prepreg materials are precisely cut into corresponding shapes using lasers. In the mold, they are laid up in a "puzzle-like" manner, with the seams overlapping by no more than 1mm, to form a prepreg laminate.

[0060] 2. Integrated co-curing The prepreg layers are sealed using a vacuum bag system and transferred into an autoclave.

[0061] Start the vacuum (maintain a negative pressure of -0.1MPa) and simultaneously apply a compressed air pressure of 0.6MPa into the autoclave.

[0062] Perform the curing process: heat to 125°C at a rate of 2.5°C / min, and hold at this temperature and pressure for 120 minutes. The uniform pressure provided by the autoclave ensures that different prepregs are compacted simultaneously, and the resins at the interfaces fuse to form chemical bonds.

[0063] 3. Post-processing and performance After curing, the material is demolded and processed. The structural components prepared by this method have high fiber content and excellent consistency. Their high thermal conductivity and wave transmission properties are comparable to those of Example 1, and their interlaminar shear strength can reach over 30 MPa, with excellent interface integrity.

[0064] Example 3 This embodiment provides a low-cost integrated molding method based on dry preform and vacuum induction (VARI), specifically illustrating a fabrication scheme with low equipment requirements.

[0065] 1. Preform preparation: This step is exactly the same as the “weaving” part of Example 1, weaving the same functionally graded dry fabric preform.

[0066] 2. Resin impregnation and vacuum curing Place the dry preform into a single-sided mold and set up the vacuum bag system according to the standard Vacuum Assisted Resin Infusion (VARI) process.

[0067] The low-viscosity epoxy resin system is drawn in and completely impregnates the preform using only the -0.1MPa negative pressure generated by the vacuum pump as the driving force.

[0068] In the oven, curing is carried out at 125°C for 120 minutes, with the entire process relying solely on vacuum negative pressure for compaction.

[0069] 3. Performance Description: The structural components prepared by this method can still achieve clear functional gradient characteristics, and their performance is significantly better than that of traditional homogeneous materials. They are suitable for application scenarios with specific requirements on cost and equipment.

[0070] Example 4 This embodiment provides a method for fabricating an integrated structural component with a functionally graded interface encapsulation layer. Specifically, it describes adding a functionally graded interface encapsulation layer to the main body of the structural component obtained in Embodiment 1 or 2 to further improve performance and durability.

[0071] 1. Preparation of main structure: First, prepare and cure the functional gradient composite structure body according to the steps of Example 1 (braiding + RTM) or Example 2 (prepreg + autoclave).

[0072] 2. Fabrication of the interface encapsulation layer On the outer surface of the solidified body, different porous media are laid in different zones according to their functional layout: boron nitride fiber nonwoven fabric (high thermal conductivity insulating medium) is laid above the high thermal conductivity zone; quartz fiber cloth (low dielectric loss medium) is laid above the controllable electromagnetic zone.

[0073] The entire component is sealed using a vacuum bag system.

[0074] The VARI process is used to inject an epoxy resin compatible with the host resin to impregnate the porous media layer.

[0075] Secondary curing is performed at a temperature lower than the glass transition temperature of the main structure, so that the newly injected resin co-crosslinks with the resin on the main surface, forming a strong chemical bond interface.

[0076] 3. Beneficial Effects: The dense encapsulation layer effectively blocks environmental factors such as moisture and salt spray from corroding the internal fibers and resin, significantly extending product lifespan. This functionally graded interface encapsulation layer provides environmental protection while maximizing the heat flow and electromagnetic wave transmission efficiency of the underlying core functional areas, significantly improving the product's environmental durability and long-term reliability.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A functionally graded composite structural component, characterized in that, It includes at least one high thermal conductivity functional layer (4) and at least one controllable electromagnetic functional layer (5) stacked together. The high thermal conductivity functional layer (4) constitutes the high thermal conductivity functional area (1) of the structural component, and its in-plane thermal conductivity is higher than that of other areas of the structural component. The controllable electromagnetic functional layer (5) constitutes the controllable electromagnetic functional area (2) of the structure, and its dielectric loss in a specific electromagnetic frequency band is lower than that in other areas of the structure. The high thermal conductivity functional area (1) and the controllable electromagnetic functional area (2) are spatially separated within the structural component.

2. The functionally graded composite structural component according to claim 1, characterized in that, It also includes a core structural layer (6), which is made of high-performance fiber-reinforced composite material, providing mechanical support for the high thermal conductivity functional layer (4) and the controllable electromagnetic functional layer (5).

3. The functionally graded composite structural component according to claim 2, characterized in that, It also includes an interface encapsulation layer (3), which is disposed on the outer surface of the core structure layer (6), the high thermal conductivity functional layer (4) and the controllable electromagnetic functional layer (5); wherein, the portion of the interface encapsulation layer (3) above the high thermal conductivity functional area (1) is a high thermal conductivity insulating medium, and the portion of the interface encapsulation layer (3) above the controllable electromagnetic functional area (2) is a low dielectric loss medium.

4. The functionally graded composite structural component according to any one of claims 1-3, characterized in that, The high thermal conductivity functional layer (4) comprises a continuous fiber reinforced composite material, wherein the continuous fiber is selected from pitch-based carbon fiber or high thermal conductivity silicon carbide fiber; the in-plane thermal conductivity of the high thermal conductivity functional layer (4) is not less than 10 W / (m·K).

5. The functionally graded composite structural component according to any one of claims 1-3, characterized in that, The controllable electromagnetic functional layer (5) comprises a fiber-reinforced composite material, wherein the volume resistivity of the fibers is 10. 1 Ω·cm to 10 5 Within the range of Ω·cm; the insertion loss of the controllable electromagnetic functional region (2) for 28GHz electromagnetic waves is not higher than -3.0dB.

6. A method for fabricating a functionally graded composite structural component, characterized in that, Includes the following steps: (1) Based on the layout of the heat source and the antenna, a spatially separated high thermal conductivity functional area (1) and a controllable electromagnetic functional area (2) are planned. (2) Prepare a functional gradient preform corresponding to the plan, which includes the high thermal conductivity functional region (1) and the controllable electromagnetic functional region (2); (3) The functional gradient preform is impregnated with a resin matrix and then cured to form a functional gradient composite structure.

7. The preparation method according to claim 6, characterized in that, In step (2), the functional gradient preform is woven in one piece by yarn weaving process.

8. The preparation method according to claim 6, characterized in that, In step (2), the functionally graded preform is formed by layering and splicing high thermal conductivity prepreg and controllable electromagnetic prepreg in sections.

9. The preparation method according to claim 6, characterized in that, In step (2), the functional gradient preform is formed by fixing the high thermal conductivity dry fiber fabric and the controllable electromagnetic dry fiber fabric by laying them in sections.

10. The preparation method according to any one of claims 6-9, characterized in that, In step (3), the curing process is one of hot-press co-curing, resin transfer molding curing, or vacuum-assisted induction curing.

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