A surface electrically continuous composite material and a method for producing the same
By preparing a co-curing process of conductive resin and fabric in a composite material, a surface electrically continuous composite material is formed, which solves the problem of poor surface electrical continuity of aircraft, achieves low resistivity and reliable electromagnetic shielding performance, and is suitable for aerospace materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- AVIC BEIJING AERONAUTICAL MFG TECH RES INST
- Filing Date
- 2026-01-28
- Publication Date
- 2026-05-19
AI Technical Summary
Existing composite materials have poor electrical continuity on aircraft surfaces, rely on post-processing technology, and it is difficult to guarantee the electrical continuity performance of assembly and connection parts. Traditional methods have problems such as poor bonding force, easy damage, large weight, and complex processes.
Conductive resin is prepared using a resin matrix and conductive fillers, conductive adhesive film is prepared using a film-making machine, and then composited with conductive fabric. A co-curing process is used to form an integral surface-electrically continuous composite material, in which the conductive layer and structural layer are formed in one step and chemically bonded at the interface.
It achieves electrical continuity with a surface resistivity of less than 200 mΩ/sq, avoiding coating peeling and metal mesh stress problems, and has good electromagnetic shielding and lightning protection performance, making it suitable for structures such as aircraft skin.
Smart Images
Figure CN121590104B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of composite materials technology, and in particular to a surface electrically continuous composite material and its preparation method. Background Technology
[0002] Modern aircraft and aerospace vehicles face increasingly stringent requirements for electromagnetic shielding performance, radar stealth capabilities, electrostatic dissipation, and lightning current conduction efficiency. The realization of these functions relies on a fundamental premise: the surface skin must possess excellent electrical continuity, forming a complete, low-resistance conductive path. Current engineering fields primarily employ the following post-processing techniques to improve the electrical continuity of composite material surfaces:
[0003] Thermal spraying of metal coatings: A metal layer (such as aluminum, zinc, etc.) is formed on the surface of a composite material using arc spraying or flame spraying techniques. However, the coating prepared by this method has limited adhesion to the composite matrix (usually <5 MPa), and is prone to cracking or even peeling under thermal cycling and vibration loads; the coating itself also suffers from problems such as easy wear and poor corrosion resistance, resulting in high maintenance costs.
[0004] Metal mesh / foil layup: Copper mesh or aluminum foil is added during the composite material layup process. This method faces the challenge of a significant difference in the coefficients of thermal expansion between the metal and the composite material (the CTE of aluminum is approximately 23 × 10⁻⁶). -6 / ℃, while carbon fiber composites are typically 10 -2 ×10 -6 The curing process can cause warping and deformation problems due to the temperature (°C); it also significantly increases the structural weight (the areal density usually increases by more than 200 g / m²); during drilling and assembly, the metal mesh is prone to yarn unraveling around the holes, making it difficult to ensure the electrical continuity of the hole walls.
[0005] Coating with conductive paint: Surface coating is performed using conductive paint containing fillers such as silver, copper, or nickel. The coatings obtained by this method generally have insufficient adhesion and durability, and are prone to performance degradation in harsh environments such as humidity, heat, and salt spray. Furthermore, to achieve a low surface resistivity (<1Ω / sq), extremely high metal filler content is required, leading to high costs and reduced coating flexibility.
[0006] These traditional technologies are all "passive" surface repair solutions, failing to address the electrical continuity issue at the material design and manufacturing stage. More importantly, existing technologies struggle to achieve durable and reliable electrical continuity in critical areas such as the overlap areas of large and complex components, curved assembly holes, and sealing plates of moving parts (such as hatches and control surfaces). Summary of the Invention
[0007] This application provides a surface electrically continuous composite material and its preparation method to solve the technical problems of poor surface electrical continuity in existing aircraft composite material structures, reliance on post-processing technology, and difficulty in ensuring electrical continuity at assembly joints. Specifically, it overcomes the problems of poor adhesion, easy damage, large weight, and complex processes associated with traditional metal coatings and metal meshes.
[0008] In a first aspect, this application provides a method for preparing a surface electrically continuous composite material, comprising:
[0009] Conductive resin is prepared using a resin matrix and conductive fillers, and conductive adhesive film is prepared from the conductive resin using a film-making machine.
[0010] The conductive adhesive film is placed on the upper side of the conductive fabric, and an electrically continuous conductive prepreg is obtained by hot pressing or a prepreg machine.
[0011] The single-layer conductive prepreg and the multi-layer prepreg are combined through a co-curing process to form an integrated surface-electrically continuous composite material.
[0012] Furthermore, the resin matrix is any one of epoxy resin, bismaleimide resin, phenolic resin, polyimide resin, and cyanate ester resin.
[0013] Furthermore, the conductive filler is any one of metal-coated carbon particles, metal particles, metal-coated polymer particles, and carbon material particles, with a particle size range of 40-400 μm.
[0014] Furthermore, the mass ratio of the conductive filler to the resin matrix is 5~15:100.
[0015] Furthermore, the preparation of the conductive resin using a resin matrix and conductive fillers includes:
[0016] Heat the resin matrix to a viscosity ≤1000 Pa·s, control the temperature below 100℃, and slowly add the conductive filler;
[0017] The conductive filler and the resin matrix are mixed evenly using a low-speed shearing method to obtain a conductive resin.
[0018] Furthermore, the thickness of the conductive adhesive film ranges from 30 to 300 μm, and the thickness of the conductive adhesive film is less than or equal to the particle size of the conductive filler.
[0019] Furthermore, the conductive fabric is any one of carbon fiber cloth, metal-plated aramid cloth, metal-plated quartz cloth, and polymer conductive nonwoven fabric, with a surface density ranging from 30 to 300 g / m².
[0020] Furthermore, the surface resistivity of the conductive prepreg is ≤200mΩ / sq.
[0021] Furthermore, the co-curing process adopts a stepped temperature curing regime, and the curing pressure is controlled at 0.1-0.8 MPa.
[0022] Secondly, this application provides a surface electrically continuous composite material, which is obtained by the preparation method of the surface electrically continuous composite material as described above.
[0023] The above-mentioned technical solution of this application has the following advantages:
[0024] The surface electrically continuous composite material and its preparation method provided in this application solve the problem of electrical continuity from the material design source. The cured surface layer itself is a good conductor, and the surface resistivity can be stably reduced to below 200 mΩ / sq, fundamentally avoiding problems such as coating peeling and metal mesh stress. The conductive layer and the structural layer are co-cured in one step, with chemical bonding at the interface, resulting in extremely strong adhesion and no risk of peeling. The conductive network consists of a "point-to-surface" dual-pathway structure. Even if the micro-filler network is locally damaged due to scratches, the macro-conductive fabric network can still ensure basic electrical continuity and has damage tolerance. Due to its high conductivity, this material not only meets the surface electrical continuity requirements but also has good electromagnetic shielding and lightning protection performance, meeting the lightning protection requirements of Zone 2A. It can be used in structures requiring electromagnetic shielding, stealth, and lightning protection, such as aircraft skin. Attached Figure Description
[0025] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0026] Figure 1 This is a schematic cross-sectional view of the surface electrically continuous composite material provided in the embodiments of this application;
[0027] Figure 2 A schematic diagram of a "point-to-surface" dual-path conductive network provided in an embodiment of this application;
[0028] Figure 3 A flowchart illustrating a method for preparing a surface-electrically continuous composite material provided in this application embodiment. Detailed Implementation
[0029] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0030] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.
[0031] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0032] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.
[0033] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a well-known unit of mass in the chemical industry, such as µg, mg, g, or kg.
[0034] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first..." may also be referred to as "second...", and similarly, "second..." may also be referred to as "first...". Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.
[0035] Widely used resin-based composite materials (such as carbon fiber or glass fiber reinforced epoxy resins) have serious inherent defects in terms of electrical properties:
[0036] 1. Significant intrinsic insulation properties: The resin matrix in the composite material is a typical insulating material, with a volume resistivity typically as high as 10⁻⁶. 12 -10 15 Even when using intrinsically conductive carbon fibers as reinforcement, the interlaminar resistivity and in-plane resistivity of the final composite material remain high due to the insulating resin separating the fiber bundles and the large contact resistance between individual fibers. Typically, these values are only around 10 Ω·cm. 0 -10 2 Ω·cm and 10 0 -10 3 The Ω / sq range cannot meet the requirements for efficient electromagnetic shielding (which typically requires a surface resistivity of <1 Ω / sq) and lightning current conduction (which requires even lower resistivity).
[0037] 2. Structural Connections Disrupt Electrical Continuity: In actual aircraft structures, the skin contains numerous process seams, functional openings, and tens of thousands of metal fastener mounting holes. These structural features severely disrupt the electrical continuity of the material, creating numerous electromagnetic wave leakage points and impedance discontinuities. Particularly at mounting hole locations, gaps often exist between the metal fasteners and the composite material hole walls, preventing reliable ohmic contact. This interrupts the conduction path of lightning current or surface current, easily generating discharge sparks or electromagnetic leakage.
[0038] With the increasing demands for electromechanical continuity in next-generation aircraft, drones, and hypersonic vehicles, the development of a new type of "structure-function integrated" composite material with excellent electrical continuity, capable of co-curing with the main load-bearing structure, and able to withstand harsh service environments has become an urgent technological need in the field of aerospace materials.
[0039] The specific embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this application, but are not intended to limit the scope of this application.
[0040] This application provides a method for preparing a surface electrically continuous composite material, comprising: preparing a conductive resin using a resin matrix and conductive fillers, and preparing a conductive film using a film-making machine; placing the conductive film on the upper side of a conductive fabric, and obtaining an electrically continuous conductive prepreg by hot pressing or a prepreg machine; and combining the single-layer conductive prepreg with a multi-layer prepreg through a co-curing process to form an integrated surface electrically continuous composite material.
[0041] like Figure 1 and Figure 2As shown, the composite material is formed by co-curing a structural load-bearing layer and a surface electrically continuous layer. The surface electrically continuous layer is a special conductive prepreg, which consists of a conductive fabric impregnated with a resin system containing conductive fillers of specific sizes, forming a "point-to-surface" dual-path conductive network. Figure 3 As shown, this preparation method achieves excellent surface electrical continuity with a surface resistivity of less than 200 mΩ / sq by precisely constructing a conductive network. This material is particularly suitable for structures such as aircraft skin that have stringent requirements for electromagnetic shielding, stealth, and lightning protection, effectively solving problems such as poor bonding strength, susceptibility to damage, and difficulty in ensuring electrical continuity at assembly points that exist in traditional post-processing techniques.
[0042] In some embodiments, the resin matrix is any one of epoxy resin, phenolic resin, bismaleimide resin, polyimide resin, and cyanate ester resin.
[0043] In some embodiments, the conductive filler is any one of metal-coated carbon particles, metal particles, metal-coated polymer particles, and carbon material particles, with a particle size range of 40-400 μm.
[0044] In some embodiments, the mass ratio of the conductive filler to the resin matrix is 5~15:100.
[0045] In some embodiments, the preparation of conductive resin using a resin matrix and conductive filler includes: heating the resin matrix to a viscosity ≤1000 Pa·s, controlling the temperature below 100°C, and slowly adding the conductive filler; mixing the conductive filler and the resin matrix uniformly using a low-speed shearing method to obtain the conductive resin.
[0046] In some embodiments, the thickness of the conductive adhesive film ranges from 30 to 300 μm, and the thickness of the conductive adhesive film is less than or equal to the particle size of the conductive filler.
[0047] In some embodiments, the conductive fabric is any one of carbon fiber cloth, metal-plated aramid cloth, metal-plated quartz cloth, and polymer conductive nonwoven fabric, with a surface density ranging from 30 to 300 g / m².
[0048] In some embodiments, the surface resistivity of the conductive prepreg is ≤200mΩ / sq.
[0049] In some embodiments, the co-curing process employs a stepped temperature curing regime, with the curing pressure controlled between 0.1 and 0.8 MPa.
[0050] This application also provides a surface electrically continuous composite material, which is obtained by the preparation method of the surface electrically continuous composite material as described above.
[0051] 1. Preparation of electrically continuous conductive prepreg
[0052] This application provides a special electrically continuous conductive prepreg, which is composed of a conductive resin system and a conductive fabric, and has unique structural and performance characteristics:
[0053] 1. Preparation of conductive resin system
[0054] 1) The resin matrix used includes epoxy resin, phenolic resin, bismaleimide resin, polyimide resin and cyanate ester resin, etc.
[0055] 2) Conductive fillers are selected from metal-coated carbon particles, metal particles, metal-coated polymer particles, and carbon material particles of specific sizes, with the particle size range D controlled between 40-400μm.
[0056] 3) The ratio of filler to resin matrix is 5~15:100 parts by weight;
[0057] 4) Based on the viscosity and flow characteristics of the resin, heat the resin to a viscosity ≤1000 Pa·s, control the temperature below 100℃, slowly add the conductive filler, and then use a low-speed shearing method to mix the filler and the resin matrix evenly to obtain the conductive resin.
[0058] 5) Use a film-making machine to prepare conductive resin into a film with a thickness of T, ranging from 30 to 300 μm, while ensuring that T ≤ D;
[0059] 2. Selection and treatment of conductive fabrics
[0060] 1) Conductive fabrics, including carbon fiber cloth, metal-coated aramid cloth, metal-coated quartz cloth, and polymer conductive nonwoven fabrics such as polyarylate.
[0061] 2) The fabric surface density is 30-300 g / m² to ensure sufficient conductive network density;
[0062] 3) Surface treatment of the fabric to improve its wettability with resin.
[0063] 3. Prepreg Composite Process
[0064] 1) Calculate the thickness of the conductive film based on the thickness of the conductive fabric to ensure that the conductive fabric is fully impregnated with the conductive resin.
[0065] 2) Place the conductive adhesive film on the upper side of the conductive fabric and obtain the corresponding prepreg by hot pressing or a prepreg machine;
[0066] 3) Measure the sheet resistance of the conductive prepreg to ensure that its surface resistivity is ≤200mΩ / sq.
[0067] II: Preparation of Surface Electrically Continuous Composite Materials
[0068] The above-mentioned conductive prepreg and structural prepreg are combined through a co-curing process to form an integral surface-electrically continuous composite material:
[0069] 1. Ply structure design
[0070] Surface layer: A single layer of conductive prepreg serves as the functional layer, with a thickness of 0.05-0.15 mm;
[0071] Main body: Multi-layer prepreg serves as the load-bearing layer;
[0072] By optimizing the layup sequence, we can ensure that the conductivity function does not affect the mechanical properties.
[0073] 2. Process combination and co-curing process control
[0074] 1) By using the above-mentioned process combination, precise control of resin flow during the curing process can be ensured to prevent conductive particles from being submerged.
[0075] 2) A stepped temperature curing process is adopted to avoid premature resin gelation;
[0076] 3) Control the curing pressure at 0.1-0.8 MPa to ensure effective contact between the conductive particles and the fabric;
[0077] 3. Conductive network formation mechanism
[0078] Conductive fabrics provide a macroscopic conductive network; conductive particles guide the conductive pathways to the surface of the composite material, forming surface electrical continuity; the reliability of electrical continuity is ensured through a "point-to-surface" dual-pathway design.
[0079] The following is a description through specific embodiments.
[0080] Example 1
[0081] Preparation of conductive prepreg:
[0082] Resin: Tetrafunctional epoxy resin (100 parts)
[0083] Conductive filler: a mixture of nickel-coated carbon powder (5 parts).
[0084] Conductive fabric: Copper-plated organic conductive nonwoven fabric (area density 50 g / m²).
[0085] Process: Conductive prepreg is prepared using the hot melt prepreg method.
[0086] Composite material preparation:
[0087] Layup sequence: [Conductive prepreg] / [4 layers of T700 carbon fiber prepreg].
[0088] Curing regime: 180°C / 2 hours, autoclave pressure 0.6MPa.
[0089] performance:
[0090] Electrical properties: Surface resistivity: 0.1 Ω / sq
[0091] Electromagnetic shielding effectiveness: In the 1-18GHz frequency band, the average shielding effectiveness is >60dB.
[0092] Mechanical properties: The interlaminar shear strength is comparable to that of the reference specimen without a conductive layer, with no performance loss.
[0093] Example 2
[0094] Preparation of conductive prepreg:
[0095] Resin: Bismaleimide resin (100 parts).
[0096] Conductive filler: Nickel-coated carbon powder (10 parts).
[0097] Conductive fabric: Nickel-plated quartz fiber cloth.
[0098] Process: Melt impregnation method.
[0099] Composite material preparation: co-cured with quartz fiber prepreg at a curing temperature of 205°C.
[0100] performance:
[0101] Surface resistivity: 0.2 Ω / sq (stable at 150°C).
[0102] Heat resistance: Can work in environments above 150°C for extended periods.
[0103] The surface electrically continuous composite material and its preparation method provided in this application have the following significant advantages:
[0104] 1. Solid electrical continuity and reliable performance: The problem of electrical continuity is solved from the source of material design. The cured surface layer itself is a good conductor, and the surface resistivity can be stably reduced to below 0.2 Ω / sq, which fundamentally avoids problems such as coating peeling and metal mesh stress.
[0105] 2. Perfect interface bonding and process compatibility: The conductive layer and structural layer are co-cured in one step, with a chemically bonded interface resulting in extremely strong adhesion and no risk of peeling. This process is fully compatible with existing composite material manufacturing processes.
[0106] 3. Excellent durability and damage tolerance: The conductive network consists of a point-to-surface dual-pathway structure. Even if the surface is damaged locally due to scratches, the macroscopic conductive fabric network can still ensure basic electrical continuity and has damage tolerance capabilities.
[0107] 4. Due to its high conductivity, this material not only meets the requirements for surface electrical continuity, but also has good electromagnetic shielding and lightning protection performance, and can meet the lightning protection requirements of Zone 2A.
[0108] 5. Address application pain points:
[0109] Large-size overlap: The conductive prepreg itself can be butt-jointed or overlapped, and low-resistance electrical continuity is achieved through conductive adhesive film.
[0110] Assembly holes: After drilling, the conductive fabric and filler network on the hole wall are exposed, allowing direct ohmic contact with metal fasteners.
[0111] Moving parts: can be used as skins for components such as sealing plates, providing a stable and durable electrical continuity path.
[0112] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. This application is not limited to the specific methods described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.
[0113] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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. Such 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 this application, and should all be included within the protection scope of this application.
Claims
1. A method for preparing a surface-electrically continuous composite material, characterized in that, include: Conductive resin is prepared using a resin matrix and conductive fillers, and conductive adhesive film is prepared from the conductive resin using a film-making machine. The conductive adhesive film is placed on the upper side of the conductive fabric, and an electrically continuous conductive prepreg is obtained by hot pressing or a prepreg machine. The single-layer conductive prepreg and the multi-layer prepreg are combined through a co-curing process to form an integral surface-electrically continuous composite material. The conductive filler is any one of metal-coated carbon particles, metal particles, metal-coated polymer particles, and carbon material particles, with a particle size range of 40-400μm. The mass ratio of the conductive filler to the resin matrix is 5~15:100; The thickness of the conductive adhesive film ranges from 30 to 300 μm, and the thickness of the conductive adhesive film is less than or equal to the particle size of the conductive filler. The conductive fabric is any one of carbon fiber cloth, metal-coated aramid cloth, metal-coated quartz cloth, and polymer conductive nonwoven fabric, with a surface density ranging from 30 to 300 g / m². The surface resistivity of the conductive prepreg is ≤200mΩ / sq; The co-curing process employs a stepped temperature increase curing regime, with the curing pressure controlled between 0.1 and 0.8 MPa. The preparation of conductive resin using a resin matrix and conductive fillers includes: Heat the resin matrix to a viscosity ≤1000 Pa·s, control the temperature below 100℃, and slowly add the conductive filler; The conductive filler and the resin matrix are mixed evenly using a low-speed shearing method to obtain a conductive resin.
2. The method for preparing the surface electrically continuous composite material as described in claim 1, characterized in that, The resin matrix is any one of epoxy resin, phenolic resin, bismaleimide resin, polyimide resin, and cyanate ester resin.
3. A surface electrically continuous composite material, characterized in that, The surface electrically continuous composite material is obtained by the preparation method according to any one of claims 1 to 2.