Lightweight flame-retardant broadband wave-absorbing structure

Abstract

The utility model discloses a kind of lightweight flame-retardant broadband wave-absorbing structures in the technical field of wave-absorbing material, including composite material component, the composite material component includes flame-retardant wave-transparent layer and flame-retardant reflection layer, the flame-retardant wave-transparent layer is set to structure top layer, flame-retardant wave-transparent layer and flame-retardant reflection layer between be provided with flame-retardant absorption layer, each layer is connected using flame-retardant adhesive film between all adoption.The utility model is through using multilayer gradient impedance design, through the optimization combination of different functional materials, realize broadband high-efficiency electromagnetic wave absorption, the alternative arrangement of medium layer and resistance layer forms progressive impedance matching, so that electromagnetic wave repeatedly attenuates between multilayer interface, finally converts into heat energy dissipation, to keep stable low reflection characteristic in relatively wide frequency range, simultaneously, structure whole selects high oxygen index flame-retardant material, and reliable combination between layers is ensured by hot-pressing process, so that product has excellent fire safety.

Description

Technical Field

[0001] This utility model relates to the field of microwave absorbing materials technology, and in particular to a lightweight, flame-retardant, broadband microwave absorbing structure. Background Technology

[0002] The rapid development of modern military radar detection technology has led to increasingly serious threats to surface ships. Stealth of ship superstructures is a major concern for navies worldwide. The application of radar-absorbing materials, utilizing this advanced inorganic non-metallic material, aims to effectively reduce radar cross-section (RCS) and improve stealth performance. Related technologies, such as CN118372519A and CN222407517U, disclose a lightweight flame-retardant composite material radar-absorbing structure for ships, including ferrite radar-absorbing putty, a glass fiber flame-retardant layer, a carbon fiber structural layer, and a honeycomb interlayer. The ferrite radar-absorbing putty is located on the outer surface of the composite material structure to provide radar absorption capabilities.

[0003] However, this type of absorbing structure uses traditional ferromagnetic absorbing material technology, which has problems such as high density and narrow absorption bandwidth. In addition, ferromagnetic absorbers are susceptible to salt spray corrosion in marine environments, which leads to a decrease in absorbing performance. Therefore, it cannot meet the increasingly high requirements for broadband absorbing performance and resistance to marine environments in the stealth of ship superstructures.

[0004] Therefore, we propose a lightweight, flame-retardant, broadband absorbing structure. Utility Model Content

[0005] To address the shortcomings of existing technologies, this invention provides a lightweight, flame-retardant, broadband microwave absorption structure. The purpose of this utility model is achieved as follows: a lightweight flame-retardant broadband absorbing structure, comprising a composite material component, wherein the composite material component comprises a flame-retardant transparent layer and a flame-retardant reflective layer, wherein the flame-retardant transparent layer is disposed on the top layer of the structure, and a flame-retardant absorption layer is disposed between the flame-retardant transparent layer and the flame-retardant reflective layer, and each layer is connected by a flame-retardant adhesive film.

[0006] Optionally, both the flame-retardant wave-transparent layer and the flame-retardant reflective layer are prepreg structures.

[0007] Optionally, the flame-retardant absorption layer includes a flame-retardant medium layer and a resistive layer, wherein the flame-retardant medium layer and the resistive layer are connected by a flame-retardant adhesive film.

[0008] Optionally, both sides of the flame-retardant absorption layer are provided with flame-retardant medium layers, and the flame-retardant medium layers and resistive layers are alternately stacked.

[0009] Optionally, the flame-retardant medium layer includes a flame-retardant phenolic foam layer, a flame-retardant PVC foam layer, a flame-retardant PMI foam layer, and a flame-retardant PET foam layer.

[0010] Optionally, the flame-retardant film is a flame-retardant epoxy resin film.

[0011] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. By adopting a multi-layer gradient impedance design and optimizing the combination of different functional materials, wide-band high-efficiency electromagnetic wave absorption is achieved. The alternating arrangement of dielectric and resistive layers forms a progressive impedance matching, which causes electromagnetic waves to repeatedly attenuate between the multi-layer interfaces and eventually be converted into heat dissipation, thereby maintaining stable low reflection characteristics over a wide frequency range.

[0012] 2. The overall structure is made of high oxygen index flame-retardant materials, and the hot pressing process ensures reliable interlayer bonding, giving the product excellent fire safety. The use of lightweight composite materials greatly reduces the structural weight, making it particularly suitable for applications that are weight-sensitive and require strict flame-retardant requirements. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0014] Fig. 1 This is a schematic diagram of the overall structure provided by this utility model.

[0015] Fig. 2 This is a schematic diagram of the flame-retardant absorption layer structure provided by this utility model.

[0016] In the figure: 1. Composite material component; 11. Flame-retardant wave-transparent layer; 12. Flame-retardant reflective layer; 13. Flame-retardant absorbing layer; 2. Flame-retardant dielectric layer; 21. First dielectric layer; 22. Second dielectric layer; 23. Third dielectric layer; 24. Fourth dielectric layer; 3. Resistive layer; 31. First resistive layer; 32. Second resistive layer; 33. Third resistive layer; 4. Flame-retardant adhesive film. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0018] like Figs. 1-2The lightweight flame-retardant broadband absorbing structure shown includes a composite material component 1. The composite material component 1 includes a flame-retardant wave-transmitting layer 11 and a flame-retardant reflective layer 12. The flame-retardant wave-transmitting layer 11 is disposed on the top layer of the structure. A flame-retardant absorption layer 13 is disposed between the flame-retardant wave-transmitting layer 11 and the flame-retardant reflective layer 12. Each layer is connected by a flame-retardant adhesive film 4, which is a flame-retardant epoxy resin adhesive film.

[0019] Furthermore, the lightweight flame-retardant broadband absorbing structure proposed in this application optimizes the electromagnetic wave loss mechanism by stacking multiple layers of flame-retardant materials and curing them by hot pressing, thereby effectively solving the problems of high density, narrow bandwidth and insufficient weather resistance of traditional ferrite materials. Furthermore, the flame-retardant wave-transparent layer 11 is used to ensure that the incident electromagnetic waves enter the absorption layer efficiently, while the alternating flame-retardant medium layer 2 and resistive layer 3 broaden the effective absorption frequency band through impedance gradient and multiple scattering mechanism, while the flame-retardant adhesive film enhances the interlayer bonding strength and inhibits the spread of flame. Secondly, the structure uses a low-density foam substrate and a flame-retardant resin system, which significantly reduces weight while ensuring mechanical properties, and is resistant to salt spray corrosion and damp heat aging, making it suitable for harsh marine environments.

[0020] Specifically, both the flame-retardant wave-transparent layer 11 and the flame-retardant reflective layer 12 are prepreg structures.

[0021] It should be noted that the flame-retardant and wave-transparent layer 11 is obtained by curing glass fiber reinforced flame-retardant epoxy resin prepreg in an autoclave. The thickness of the wave-transparent layer is 0.6-1.0 mm, and the limiting oxygen index of the wave-transparent layer is ≥40%. Furthermore, using a prepreg structure as the flame-retardant wave-transparent layer 11 and the flame-retardant reflective layer 12 can ensure that the material has excellent mechanical properties and stable electromagnetic characteristics. After curing, the prepreg forms a dense and uniform composite material layer, which can not only ensure structural strength, but also precisely control the dielectric constant and magnetic permeability, thereby optimizing the electromagnetic wave transmission and reflection behavior. In addition, prepregs have a high degree of technological maturity, making it easy to achieve large-area lay-up and complex curved surface molding, thus meeting the structural design requirements of ship superstructures.

[0022] Specifically, the flame-retardant absorption layer 13 includes a flame-retardant medium layer 2 and a resistive layer 3. The flame-retardant medium layer 2 and the resistive layer 3 are connected by a flame-retardant adhesive film 4. Both sides of the flame-retardant absorption layer 13 are provided with flame-retardant medium layers 2, and the flame-retardant medium layers 2 and the resistive layers 3 are alternately stacked.

[0023] Furthermore, the flame-retardant absorption layer 13 is composed of four flame-retardant dielectric layers and three resistive layers stacked alternately. The flame-retardant dielectric layer 2 provides impedance matching to ensure that electromagnetic waves can smoothly enter the absorber, while the resistive layer 3 converts electromagnetic energy into heat energy through ohmic loss. The alternating stacked layout forms a multiple reflection-absorption mechanism, which broadens the effective absorption frequency band. At the same time, the flame-retardant adhesive film 4 not only ensures the interlayer bonding strength, but also further inhibits the spread of flames.

[0024] Specifically, the flame-retardant medium layer 2 includes a flame-retardant phenolic foam layer, a flame-retardant PVC foam layer, a flame-retardant PMI foam layer, and a flame-retardant PET foam layer.

[0025] Furthermore, the flame-retardant medium layer 2 has a density ≤120kg / 3 and a thickness of 2.5~5.5mm. The flame-retardant medium layer 2 includes flame-retardant phenolic foam, flame-retardant PVC foam, flame-retardant PMI foam, and flame-retardant PET foam. The limiting oxygen index of the flame-retardant medium layer is ≥35%.

[0026] The substrate of the resistive layer 3 is PI, with a thickness of 0.05 to 0.1 mm, and the sheet resistance of the first resistive layer 31 is greater than that of the second resistive layer 32, which is greater than that of the third resistive layer 33.

[0027] Furthermore, phenolic foam provides excellent high-temperature resistance, PVC foam enhances chemical stability, PMI foam ensures high specific strength, and PET foam optimizes dielectric properties. Together, they construct a lightweight and high-strength electromagnetic wave control carrier. All materials meet the high oxygen index requirements, enabling the overall structure to effectively self-extinguish when exposed to high temperatures or open flames. At the same time, the ultra-low density characteristics significantly reduce the load on the ship's superstructure.

[0028] An exemplary lightweight, flame-retardant, broadband microwave absorbing structure includes the following steps: 0.8mm glass fiber reinforced epoxy resin composite material is used as flame-retardant wave-transparent layer 11, 0.5mm carbon fiber reinforced epoxy resin composite material is used as flame-retardant reflective layer 12, 2.5mm flame-retardant phenolic foam is used as first dielectric layer 21, 5.5mm flame-retardant phenolic foam is used as second dielectric layer 22, 5mm flame-retardant phenolic foam is used as third dielectric layer 23, and 4.8mm flame-retardant phenolic foam is used as fourth dielectric layer 24. A PI substrate with a sheet resistance of 300Ω / port and a thickness of 0.05mm is used as the first resistive layer 31, a PI substrate with a sheet resistance of 200Ω / port and a thickness of 0.05mm is used as the second resistive layer 32, and a PI substrate with a sheet resistance of 100Ω / port and a thickness of 0.05mm is used as the third resistive layer 33.

[0029] The above layers of materials are connected and sealed with a 0.15mm epoxy film 4 and then placed in a thermostatic precipitator for curing to obtain a flame-retardant broadband absorbing structure. The absorbing structure is then trimmed to the required size according to standard requirements. According to GB / T8924 Test Method for Combustion Performance of Fiber Reinforced Plastics, the limiting oxygen index of the absorbing structure reached 35% using the oxygen index method. Reflectivity was tested according to GJB2038A-2011, and the results showed that it achieved an absorption effect of over 90% (reflectivity less than -10dB) in the 2-18GHz frequency band.

[0030] In summary, by using composite layers with different reinforcing fibers as wave-transmitting and wave-reflecting functional units, combined with gradient thickness dielectric layers and gradually deformable resistive layers, an efficient electromagnetic wave absorption path is constructed. The hot-pressing curing process ensures that the layers are tightly bonded together, forming a stable multilayer composite system. Tests show that this application not only has good flame retardant properties and meets strict fire protection standards, but also exhibits excellent wave absorption performance over a wide frequency range, effectively attenuating electromagnetic wave energy while taking into account the requirements of lightweight, flame retardant safety and broadband stealth.

[0031] The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.

Claims

1. A lightweight, flame-retardant, broadband microwave absorbing structure, comprising composite material components, characterized in that: The composite material component includes a flame-retardant wave-transparent layer and a flame-retardant reflective layer. The flame-retardant wave-transparent layer is disposed on the top layer of the structure. A flame-retardant absorption layer is disposed between the flame-retardant wave-transparent layer and the flame-retardant reflective layer. All layers are connected by a flame-retardant adhesive film.

2. The lightweight flame-retardant broadband absorbing structure according to claim 1, characterized in that: Both the flame-retardant transparent layer and the flame-retardant reflective layer are prepreg structures.

3. The lightweight flame-retardant broadband absorbing structure according to claim 1, characterized in that: The flame-retardant absorption layer includes a flame-retardant medium layer and a resistive layer, and the flame-retardant medium layer and the resistive layer are connected by a flame-retardant adhesive film.

4. The lightweight flame-retardant broadband absorbing structure according to claim 3, characterized in that: Both sides of the flame-retardant absorption layer are provided with flame-retardant medium layers, and the flame-retardant medium layers and resistive layers are alternately stacked.

5. The lightweight flame-retardant broadband absorbing structure according to claim 4, characterized in that: The flame-retardant medium layer includes a flame-retardant phenolic foam layer, a flame-retardant PVC foam layer, a flame-retardant PMI foam layer, and a flame-retardant PET foam layer.

6. The lightweight flame-retardant broadband absorbing structure according to claim 1, characterized in that: The flame-retardant adhesive film is a flame-retardant epoxy resin adhesive film.

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