Carbon fiber mask aluminum profile heat preservation cabin door electromagnetic shielding structure and manufacturing process

Abstract

The invention provides a carbon fiber mask aluminum profile heat preservation cabin door electromagnetic shielding structure and a manufacturing process thereof. The carbon fiber mask aluminum profile heat preservation cabin door electromagnetic shielding structure comprises a carbon fiber mask provided with a metal aluminum spraying layer, an aluminum profile framework and heat preservation foam filled in a cavity. And a semi-fluid sealant layer for forming a physical isolation dam and a conductive sealant layer for electric connection are sequentially arranged on the contact surface of the mask and the framework from inside to outside. According to the invention, internal insulation structural adhesive is prevented from overflowing to pollute a conductive surface by utilizing the physical barrier effect of the inner side semi-fluid sealant layer, and reliable electromagnetic shielding and sealing are realized by combining the connection effect of the outer side conductive sealant layer; the problems of shielding failure and water seepage of the composite cabin door caused by the fact that dissimilar materials cannot be welded and glue overflow are effectively solved, and the shielding effectiveness and reliability of the cabin door are improved.

Description

Technical Field

[0001] This invention relates to the field of composite material cabin manufacturing technology, and in particular to an electromagnetic shielding process for a carbon fiber-coated aluminum profile insulated cabin door. Background Technology

[0002] With increasingly stringent requirements for lightweight, high-strength, and electromagnetic stealth performance in modern defense and special equipment, the traditional welded hatch structure of "aluminum panel + aluminum profile" is gradually being replaced by a new structure of "carbon fiber composite panel + aluminum profile frame" due to its heavy weight and large radar cross-section. However, this change in material system brings significant challenges to electromagnetic shielding technology.

[0003] In existing manufacturing processes, to ensure the structural rigidity and thermal insulation performance of the hatch, it is typically necessary to fill the cavity formed by the carbon fiber panel and the aluminum profile frame with insulating foam and then bond them together using structural adhesive. However, existing technology has a serious and hidden technical flaw: the structural adhesive (usually epoxy resin-based) is a fluid liquid before curing and is essentially a highly insulating material. During the assembly and compaction of the hatch and the expansion of the internal foam, the high internal pressure drives the fluid insulating structural adhesive to diffuse disorderly to the surrounding edges. Since the carbon fiber panel and the aluminum profile frame cannot be welded like metal, they are only connected by contact. This disordered flowing insulating liquid easily seeps into the precise contact gaps between the panel and the frame through capillary action, forming a layer of "insulating film" that is difficult to detect with the naked eye but is electrically completely isolated.

[0004] This thin layer of "insulating film" completely severs the conductive path between the carbon fiber cover (even after aluminum spraying) and the aluminum profile frame, resulting in discontinuous conductivity on the hatch surface. Under electromagnetic wave irradiation, this discontinuous contact surface will form a slot antenna effect, causing serious electromagnetic leakage and significantly reducing or even completely failing the electromagnetic shielding effectiveness of the hatch.

[0005] Furthermore, existing solutions typically attempt to address this by adding sealant externally. However, if the issue of internal insulating adhesive leakage remains unresolved, external conductive measures often rely on the insulating adhesive layer, failing to create a truly low-impedance connection. Alternatively, existing technologies require extremely wide adhesive application surfaces (e.g., 30mm or more) in the frame profiles to prevent adhesive overflow, severely limiting the lightweight design and space utilization of the hatch. Therefore, effectively curbing the "aggressive" flow of internal insulating media and establishing stable and reliable conductive channels within limited structural space is a critical technical challenge that urgently needs to be addressed in the current field of composite material cabin manufacturing. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: in the prior art, after the hatch is changed from aluminum mask to carbon fiber mask in pursuit of lightweight and high strength, the carbon fiber mask and aluminum profile frame cannot achieve continuous conductivity through welding, and when filling with thermal insulation foam, the insulating structural adhesive can easily flow to the contact surface between the mask and the frame to form an insulating layer, resulting in discontinuous conductivity on the surface of the hatch, failure of electromagnetic shielding performance, and the risk of water seepage.

[0007] The technical solution adopted by this invention to solve its technical problem is: An electromagnetic shielding structure for a carbon fiber-coated aluminum profile insulated door includes: Carbon fiber sheet with an aluminum spray layer on its inner surface; The aluminum profile skeleton is in the form of a closed frame, and the aluminum profile skeleton forms a contact surface with the inner surface of the carbon fiber mask. Thermal insulation foam and structural adhesive are filled in the cavity formed by the aluminum profile frame and carbon fiber cover plate. A semi-fluid sealant layer is arranged in a closed loop on the inner area of ​​the contact surface; The conductive sealant layer is arranged in a closed loop on the outer area of ​​the contact surface and is located outside the semi-fluid sealant layer. The semi-fluid sealant layer forms a physical isolation dam, blocking the structural adhesive inside the cavity from flowing to the conductive sealant layer. The conductive sealant layer connects the aluminum profile skeleton to the metal sprayed aluminum layer on the surface of the carbon fiber mask, forming an electrical connection path.

[0008] Preferably, the resistivity of the metal sprayed aluminum layer is 6.892μΩ~13.352μΩ, and the carbon fiber mask is formed by curing carbon fiber cloth and resin through a vacuum infusion process.

[0009] Preferably, the semi-fluid sealant layer has viscosity characteristics that block fluid flow before curing, and deforms under compaction to form a physical isolation dam.

[0010] Preferably, the conductive sealant layer is filled between the aluminum profile skeleton and the metal sprayed aluminum layer in a compacted state, forming a continuous conductive path and a waterproof sealing structure.

[0011] Preferably, the width of the semi-fluid sealant layer after compaction is 10mm-25mm, and the width of the conductive sealant layer after compaction is 25mm-40mm.

[0012] A manufacturing process for an electromagnetic shielding structure of a carbon fiber-coated aluminum profile insulated door includes the following steps: S1. Prepare carbon fiber masking plate and spray aluminum on its inner surface to form a metal aluminum spray layer. S2. Apply adhesive in sections on the contact surfaces of the aluminum profile frame: apply a closed-loop semi-fluid sealant to the inner side of the contact surface and apply a closed-loop conductive sealant to the outer side of the contact surface. S3. Assembly and compaction: The carbon fiber mask is covered on the aluminum profile skeleton and compacted; during the compaction process, the semi-fluid sealant layer is deformed under pressure to form a sealant barrier dam, and the conductive sealant layer is deformed under pressure to establish an electrical connection with the metal sprayed aluminum layer. S4. Filling and curing: Insulating foam is filled into the cavity enclosed by the aluminum profile frame and bonded with structural adhesive; the structural adhesive is blocked by the adhesive barrier formed by the semi-fluid sealant layer during the flow process and cannot enter the area where the conductive sealant layer is located. S5. Curing and molding: After each adhesive layer and structural adhesive has cured, the electromagnetic shielding door is formed as a whole.

[0013] Preferably, in step S1, after aluminum spraying, a DC low-resistance tester is used to test the resistivity of the aluminum sprayed layer to ensure that the resistivity is reduced to a preset range before proceeding to subsequent steps.

[0014] The beneficial effects of this invention include the following: 1. By setting a semi-fluid sealant layer on the inner side of the contact surface between the carbon fiber mask and the aluminum profile frame to form a physical isolation dam, and setting a conductive sealant layer on the outer side to connect the metal sprayed aluminum layer and the frame, the flow of the internal insulating structural adhesive is physically blocked and the external conductive path is reliably established. This effectively solves the problem of electromagnetic shielding failure caused by the penetration of the insulating structural adhesive cutting off the conductive path. It also solves the technical problem that dissimilar materials such as carbon fiber and aluminum profile cannot be welded to achieve conductive connection, thus ensuring the high-efficiency electromagnetic shielding performance of the hatch.

[0015] 2. By setting a conductive sealant layer in a closed loop on the outer side of the aluminum profile frame contact surface, and filling it between the carbon fiber cover plate and the aluminum profile frame, a dual-function structure with low resistance conductivity and waterproof sealing is formed. This effectively solves the problems of easy water seepage at the edges of composite material doors and poor weather resistance, and significantly improves the reliability and service life of the doors in harsh environments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the carbon fiber-coated aluminum profile insulated door in an embodiment of the present invention; Figure 2 This is a schematic diagram showing the location and distribution of adhesive on the contact surface of the aluminum profile frame in an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the connection structure effect of the aluminum-sprayed carbon fiber mask and the glued aluminum profile skeleton after compaction in an embodiment of the present invention.

[0017] Reference numerals: 1. Carbon fiber sheet; 11. Metal sprayed aluminum layer; 2. Aluminum profile frame; 21. Contact surface; 3. Thermal insulation foam; 4. Semi-fluid sealant layer; 5. Conductive sealant layer; 6. Structural adhesive. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments, but these specific embodiments do not limit the scope of protection of the present invention in any way. Example

[0019] See appendix Figure 1-3 An electromagnetic shielding structure for a carbon fiber-coated aluminum profile insulated hatch is disclosed, comprising a carbon fiber coating 1, an aluminum profile frame 2, insulating foam 3, a semi-fluid sealant layer 4, and a conductive sealant layer 5. This structure primarily addresses the discontinuous conductivity issues arising during the manufacturing of composite material hatches due to the inability to weld carbon fiber to the aluminum profile and the tendency of the insulating sealant 6 to overflow. It ensures the electromagnetic shielding effectiveness and watertightness of the hatch surface while meeting the design requirements for lightweight and high-strength hatch bodies.

[0020] The carbon fiber cover plate 1, serving as the outer surface covering component of the hatch, has a plate-like structure and is formed by curing carbon fiber cloth and resin through a vacuum infusion process. To overcome the inherent defects of high resistivity and poor conductivity of carbon fiber composite materials, a metal-sprayed aluminum layer 11 is provided on the inner surface of the carbon fiber cover plate 1 (i.e., the side in contact with the aluminum profile frame 2). This metal-sprayed aluminum layer 11 is formed by spraying aluminum onto the surface of the carbon fiber plate and covers the contact side between the carbon fiber cover plate 1 and the aluminum profile frame 2, significantly reducing the resistivity of the cover plate surface. After spraying, the resistivity of the metal-sprayed aluminum layer 11 is 6.892 μΩ to 13.352 μΩ, giving it excellent metallic conductivity and laying the physical foundation for electromagnetic shielding.

[0021] The aluminum profile frame 2 serves as the supporting structure for the hatch, forming a closed frame that supports the carbon fiber cover plate 1 and defines the edge contour of the hatch. Made of aluminum, the aluminum profile frame 2 possesses excellent electrical conductivity. It is bonded to the carbon fiber cover plate 1 via adhesive, creating a contact surface 21 of a certain width between them. The cavity enclosed by the aluminum profile frame 2 is filled with insulating foam 3 to provide thermal insulation for the hatch. The carbon fiber cover plate 1 and the insulating foam 3 are bonded together with structural adhesive 6, an insulating liquid that exhibits some fluidity before curing and is prone to seeping outwards under pressure without any obstruction.

[0022] A semi-fluid sealant layer 4 is applied to the inner area of ​​the contact surface 21 between the aluminum profile skeleton 2 and the carbon fiber cover plate 1, i.e., the side closest to the thermal insulation foam 3. The semi-fluid sealant layer 4 is continuously coated in a closed-loop shape onto the aluminum profile skeleton 2, forming a continuous physical isolation barrier. This semi-fluid sealant has high viscosity and thixotropy, used to construct a robust "isolation dam" during assembly and compaction. The main function of this isolation dam is to physically prevent the internal insulating structural adhesive 6 used to bond the thermal insulation foam 3 from flowing outwards, preventing the insulating adhesive liquid from seeping into the outer conductive connection area, thereby avoiding the formation of an insulating film between the carbon fiber cover plate 1 and the aluminum profile skeleton 2.

[0023] The conductive sealant layer 5 is located on the outer side of the contact surface 21 between the aluminum profile frame 2 and the carbon fiber cover plate 1, that is, on the side near the outer edge of the hatch, surrounding the semi-fluid sealant layer 4. The conductive sealant layer 5 is also coated in a closed-loop shape on the aluminum profile frame 2. This conductive sealant layer 5 has both sealing and conductive functions: on the one hand, it fills the space between the metal-sprayed aluminum layer 11 of the carbon fiber cover plate 1 and the aluminum profile frame 2, establishing a low-resistance conductive path to ensure reliable electrical connection between the cover plate and the frame, meeting the requirement of continuous and integrated surface conductivity for electromagnetic shielding; on the other hand, it eliminates the gap between the periphery of the carbon fiber and the contact surface 21 of the door frame aluminum profile, forming a waterproof sealing structure to prevent external moisture from seeping into the interior of the hatch.

[0024] In the specific implementation structure, based on the width of the aluminum profile frame 2 and experience in applying adhesive, the semi-fluid sealant layer 4 and the conductive sealant layer 5 are distributed in inner and outer layers on the contact surface 21 of the aluminum profile frame 2. The width of the semi-fluid sealant layer 4 after compaction is designed to effectively block the internal adhesive pressure, while the width of the outer conductive sealant layer 5 is designed to provide sufficient conductive contact area and sealing reliability. After assembly and compaction, a conductive sealing area consisting of "aluminum profile frame 2 - conductive sealant layer 5 - carbon fiber mask 1 metal sprayed aluminum layer 11" and an adhesive-blocking isolation area consisting of "aluminum profile frame 2 - semi-fluid sealant layer 4 - carbon fiber mask 1 metal sprayed aluminum layer 11" are formed sequentially from the outside to the inside at the connection.

[0025] The working principle and method of the above-mentioned electromagnetic shielding structure for carbon fiber-coated aluminum profile insulated cabin doors are as follows: The first step involves the operator fabricating a carbon fiber board using carbon fiber cloth and resin through a vacuum infusion process. Then, a smart DC low-resistance tester (TH2512B model) is used to test the resistance of the carbon fiber board. If the test results show an excessively high resistance value (e.g., exceeding the maximum resistance or no value), it indicates that its conductivity does not meet the shielding requirements. In this case, the operator needs to perform aluminum spraying on the surface of the carbon fiber board until its resistivity is reduced to the predetermined low resistance range upon retesting, forming a highly conductive aluminum sprayed layer 11 to ensure the shielding plate has the conductivity required for electromagnetic shielding.

[0026] The second step involves the operator applying adhesive to the aluminum profile frame 2 in sections: On the contact surface 21 of the door frame aluminum profile frame 2, adhesive is applied according to predetermined positions. First, a ring of semi-fluid sealant is applied to the inner side of the contact surface 21 (the side closer to where the foam will be filled) to create a barrier against adhesive flow; then, a ring of conductive sealant is applied to the outer side of the contact surface 21 (the side closer to the edge) to create a conductive and waterproof channel.

[0027] The third step involves the operator covering the treated carbon fiber mask 1 with the metal sprayed aluminum layer 11 onto the glue-coated aluminum profile frame 2 and compacting it. During compaction, the inner semi-fluid sealant layer 4 is compressed and deformed, forming a dense "isolation dam" using its high viscosity properties. This isolation dam physically blocks the outward flow of the internal insulating structural adhesive 6. Simultaneously, the outer conductive sealant layer 5 is compressed and filled, tightly adhering between the aluminum profile and the mask's sprayed aluminum layer 11, completing the electrical connection and sealing.

[0028] The fourth step involves filling and curing the insulating foam 3. After the cover plate and frame are fixed, the insulating foam 3 is filled into the cavity, and the structural adhesive 6 is bonded. Due to the presence of the semi-fluid sealant layer 4 (isolation dam), the internally flowing insulating structural adhesive 6 is strictly confined within the isolation zone and cannot flow to the external conductive connection area. After all the adhesive has cured, the hatch becomes a single unit.

[0029] Step 5: Implementation and Verification of Electromagnetic Shielding Function: When electromagnetic waves irradiate the hatch surface, the aluminum spray layer 11 on the carbon fiber mask 1 and the aluminum profile frame 2 are connected by a continuous, low-resistance layer 5, and the contact surface 21 is not contaminated by the insulating structural adhesive 6. This forms a continuous conductor across the entire hatch surface. Induced current can smoothly conduct between the mask and the frame without any insulation breaks, effectively reflecting or absorbing electromagnetic waves and achieving highly efficient electromagnetic shielding of the hatch.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any innovative improvements or substitutions based on the present invention should fall within the scope of the claims of the present invention. Furthermore, the parameters, materials, and processes mentioned in the above embodiments are not unique. Without departing from the technical essence of the present invention, those skilled in the art can make various alternative choices, and these alternative solutions should also be considered to fall within the scope of protection of the present invention.

Claims

1. An electromagnetic shielding structure for a carbon fiber-coated aluminum profile insulated cabin door, characterized in that, include: Carbon fiber sheet with an aluminum spray layer on its inner surface; The aluminum profile skeleton is in the form of a closed frame, and the aluminum profile skeleton forms a contact surface with the inner surface of the carbon fiber mask. Thermal insulation foam and structural adhesive are filled in the cavity formed by the aluminum profile frame and carbon fiber cover plate. A semi-fluid sealant layer is arranged in a closed loop on the inner area of ​​the contact surface; The conductive sealant layer is arranged in a closed loop on the outer area of ​​the contact surface and is located outside the semi-fluid sealant layer. The semi-fluid sealant layer forms a physical isolation dam, blocking the structural adhesive inside the cavity from flowing to the conductive sealant layer. The conductive sealant layer connects the aluminum profile skeleton to the metal sprayed aluminum layer on the surface of the carbon fiber mask, forming an electrical connection path.

2. The electromagnetic shielding structure of the carbon fiber-coated aluminum profile insulated cabin door according to claim 1, characterized in that, The resistivity of the aluminum spray layer is 6.892μΩ~13.352μΩ, and the carbon fiber mask is formed by curing carbon fiber cloth and resin through a vacuum infusion process.

3. The electromagnetic shielding structure of the carbon fiber-coated aluminum profile insulated cabin door according to claim 1, characterized in that, The semi-fluid sealant layer has viscosity characteristics that block fluid flow before curing, and deforms under compaction to form the physical isolation dam.

4. The electromagnetic shielding structure of the carbon fiber-coated aluminum profile insulated cabin door according to claim 1, characterized in that, The conductive sealant layer, under compaction, fills the space between the aluminum profile skeleton and the metal sprayed aluminum layer, forming a continuous conductive path and a waterproof sealing structure.

5. The electromagnetic shielding structure of the carbon fiber-coated aluminum profile insulated cabin door according to claim 1, characterized in that, The width of the semi-fluid sealant layer after compaction is 10mm-25mm, and the width of the conductive sealant layer after compaction is 25mm-40mm.

6. A manufacturing process for the electromagnetic shielding structure of a carbon fiber-coated aluminum profile insulated cabin door as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Prepare carbon fiber masking plate and spray aluminum on its inner surface to form a metal aluminum spray layer. S2. Apply adhesive in sections on the contact surfaces of the aluminum profile frame: apply a closed-loop semi-fluid sealant to the inner side of the contact surface and apply a closed-loop conductive sealant to the outer side of the contact surface. S3. Assembly and compaction: The carbon fiber mask is covered on the aluminum profile skeleton and compacted; during the compaction process, the semi-fluid sealant layer is deformed under pressure to form a sealant barrier dam, and the conductive sealant layer is deformed under pressure to establish an electrical connection with the metal sprayed aluminum layer; S4. Filling and curing: Fill the cavity enclosed by the aluminum profile frame with thermal insulation foam and bond it with structural adhesive. During the flow process, the structural adhesive is blocked by the adhesive barrier formed by the semi-fluid sealant layer and cannot enter the area where the conductive sealant layer is located. S5. Curing and molding: After each adhesive layer and structural adhesive has cured, the electromagnetic shielding door is formed as a whole.

7. The manufacturing process according to claim 6, characterized in that, In step S1, after aluminum spraying, the resistivity of the metal aluminum spray layer is tested using a DC low-resistivity tester to ensure that the resistivity is reduced to a preset range before proceeding to subsequent steps.

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