Resonant multi-component fiber composite broadband wave-absorbing structure and preparation method thereof
By combining fiber bundles with different dielectric properties and designing irregularly shaped absorption units, the problem of insufficient absorption capacity of traditional microwave absorbing materials with thin thicknesses is solved, and broadband absorption performance is improved, with significant improvements in absorption bandwidth and reflection loss.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-25
- Publication Date
- 2026-03-27
AI Technical Summary
Traditional absorbing materials have insufficient broadband absorption capacity at relatively thin thicknesses, poor compatibility between structure and function, and the connection relationship between multiple layers in existing fiber composite materials is not fully considered, resulting in limited absorbing effect.
By combining SiCN fiber bundles and SiBCN fiber bundles with SiCf fiber bundles, which have significantly different dielectric properties, multilayer absorption units of various shapes are designed to form H-type or lamp-like structures, disrupting the phase of the reflected waves between layers. These are then combined with a substrate and a metal sheet to form a resonator, achieving impedance gradient transition.
A wide effective absorption bandwidth and strong absorption performance are achieved with a relatively thin thickness, with an absorption bandwidth of 12.4525GHz and a reflection loss of less than -10dB, which improves the absorption efficiency and absorption capability within the frequency band.
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Figure CN121394913B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a resonant multi-component fiber composite broadband wave-absorbing structure and a preparation method thereof, and belongs to the technical field of radar wave-absorbing material development. BACKGROUND
[0002] Traditional wave-absorbing materials are faced with the problem of insufficient effective absorption bandwidth, and it is difficult to achieve the characteristics of lightweight and high strength. Fiber composite materials not only provide necessary structural support, but also achieve effective absorption of radar electromagnetic waves due to their simple structure, high temperature resistance and light weight, and thus become an ideal choice for high-temperature electromagnetic wave absorbing materials. For example, fiber composite materials are used in key parts such as wings and tail wings of stealth aircraft. In fiber materials, SiC fibers not only have excellent properties such as high temperature resistance, oxidation resistance and corrosion resistance, but also have adjustable resistivity, which is more conducive to impedance matching, and are widely used in aerospace, weapons, nuclear energy and thermal machines, etc. However, the loss capacity of SiC fibers alone is often insufficient. SiCN and SiBCN ceramic materials have excellent high-temperature stability and oxidation resistance, and are the best choice for solving the problem of thermal end stealth. However, because of their wave-transparent characteristics, they are mostly used as wave-transparent materials, and it is often difficult to achieve ideal wave-absorbing effect when used alone.
[0003] To solve the above problems, the filler type wave-absorbing material is researched more at home and abroad. The powder wave-absorbing agent or fiber wave-absorbing agent is uniformly dispersed in the matrix. This type of wave-absorbing material can achieve very good wave-absorbing effect at a certain specific frequency, but its electromagnetic absorption performance is very dependent on the electromagnetic response characteristics of the filler, and mainly relies on the adjustment of the thickness resonance and the material mixing ratio composition to achieve strong absorption. Therefore, this type of wave-absorbing material usually shows narrow-band absorption characteristics.
[0004] To broaden the absorption bandwidth, the design of surface fiber periodic array structure is an effective method to achieve broadband absorption. This method simply embeds or attaches fibers on the surface of the substrate as a wave-absorbing functional unit, which can balance the mechanical properties and wave-absorbing properties without changing the mechanical properties of the substrate, and realize the high integration of structure and function. For example, Chinese patent application CN117791173A discloses a Cf / SiCf combined absorption unit and array resonant absorption structure. The structure adopts Cf / SiCf fibers to form an I-shaped array or a cross-shaped array, and forms a multi-layer array resonant absorption structure by arrangement, which has only a 7.4 GHz effective wave-absorbing bandwidth, and needs a large total thickness to play this wave-absorbing effect. However, due to the limitations of the I-shaped structure and the cross-shaped structure and the Cf material, the wave-absorbing capacity of the fibers is not fully utilized. In addition, the same shape is used between the multiple layers, and the connection relationship between adjacent layers is not considered, so the wave-absorbing effect is greatly limited. SUMMARY
[0005] In view of the problems of the traditional wave-absorbing materials, such as insufficient wide-band absorption ability, poor compatibility of structure and function, etc., at a relatively thin thickness, the first object of the present application is to provide a resonant multi-component fiber composite wide-band wave-absorbing structure, which realizes wide effective absorption bandwidth and strong wave-absorbing performance at a relatively thin thickness by selecting specific fiber types with significantly different dielectric properties for combination and synergizing the shape design between multiple layers.
[0006] The second object of the present application is to provide a preparation method of the resonant multi-component fiber composite wide-band wave-absorbing structure, which is simple and easy to implement, and the materials are common and easy to obtain, and the method can be mass-produced and repaired easily.
[0007] In order to achieve the above technical purposes, the present application provides a resonant multi-component fiber composite wide-band wave-absorbing structure, which comprises a metal sheet and a wave-absorbing layer; the wave-absorbing layer is a multi-layer structure, each layer of the wave-absorbing layer is composed of a base material and a composite fiber absorption layer on the surface of the base material; the composite fiber absorption layer has a periodic array structure; the periodic array structure comprises a plurality of absorption units, each absorption unit is formed in an H type or a lamp type shape by connecting a fiber bundle A and a SiCf fiber bundle; and the shapes of the absorption units in the composite fiber absorption layers of any two adjacent layers of the wave-absorbing layer are different; the fiber bundle A is selected from at least one of a SiCN fiber bundle and a SiBCN fiber bundle.
[0008] The key to realizing the wide effective absorption bandwidth and strong wave-absorbing performance under the total thickness of the thin wave-absorbing layer is the selection of the fiber type and the shape design between the multiple layers. Specifically, the present application designs the shapes of the absorbing units in the adjacent wave-absorbing layers to be different, which disrupts the phase relationship of the reflected waves between the layers, so that the overall structure has good response to electromagnetic waves of different polarization directions, and a multi-frequency point complementary resonance response can be formed. These resonance peaks are staggered and superimposed in the frequency domain, thereby effectively widening the absorption bandwidth of the overall structure of the material. In addition, the multiple patches in the multi-layer design will intensify the loss of electromagnetic waves. The patches in the lower layer and the substrate and metal sheet together form a fiber-substrate-metal resonator, thereby realizing the gradient transition of the impedance of the electromagnetic wave from the surface layer to the bottom layer, reducing the direct reflection of the incident wave, and further improving the wave-absorbing efficiency and wide frequency characteristics. In addition, the combination of the SiCN fiber bundle and / or the SiBCN fiber bundle with the SiCf fiber bundle in the present application makes the fibers with different dielectric properties fully exert their respective wave-absorbing advantages compared with the Cf / SiCf combination in the prior art. Based on the semiconductor characteristics of the SiCN fiber bundle and the SiBCN fiber bundle, the electromagnetic parameters of the composite material, especially the wide-range adjustability of the complex dielectric constant, are endowed, thereby significantly optimizing the impedance matching and reducing the surface reflection. At the same time, the rich heterogeneous interfaces formed by the fibers and the matrix and the defects inside the material jointly excite strong interface polarization and dipole polarization relaxation, thereby synergistically enhancing the dielectric loss in a wide frequency band. In this way, the synergistic effect of the material and the shape greatly improves the absorption bandwidth and enhances the performance of the wave-absorbing material, so that it can effectively absorb electromagnetic waves in a wider frequency range, and further reduces the minimum reflection loss.
[0009] The shape of the absorbing unit in the composite fiber absorbing layer of each layer of the wave-absorbing layer of the present application is one of the following.
[0010] As a preferred scheme, the H-shaped structure is composed of the fiber bundle A vertically connected between two parallel distributed SiCf fiber bundles.
[0011] As a preferred scheme, the lamp-like type is composed of four SiCf fiber bundles and four fiber bundles A, the four SiCf fiber bundles are respectively a first SiCf fiber bundle, a second SiCf fiber bundle, a third SiCf fiber bundle and a fourth SiCf fiber bundle, and the four fiber bundles A are respectively a first fiber bundle A, a second fiber bundle A, a third fiber bundle A and a fourth fiber bundle A; the four SiCf fiber bundles are arranged in parallel and at intervals, and the four fiber bundles A are arranged in parallel and at intervals; two ends of the first fiber bundle A are respectively connected perpendicularly to the middle of the first SiCf fiber bundle and the second SiCf fiber bundle, two ends of the second fiber bundle A are respectively connected perpendicularly to one end of the second SiCf fiber bundle and the third SiCf fiber bundle, two ends of the third fiber bundle A are respectively connected perpendicularly to the other end of the second SiCf fiber bundle and the third SiCf fiber bundle, and two ends of the fourth fiber bundle A are respectively connected perpendicularly to the middle of the third SiCf fiber bundle and the fourth SiCf fiber bundle.
[0012] It is found through experiments that when the H type or the lamp-like type is adopted, both types are polarization sensitive, when the arrangement of the long axis direction of the fiber bundle A is parallel to the electric field, continuous conduction current is generated on the surface of the fiber, the strong electromagnetic field excited by the conduction current is radiated outward, resulting in strong reflection of the whole, and the wave absorption performance is poor. When the arrangement direction of the fiber bundle A is perpendicular to the electric field direction in the electromagnetic wave, the material of the fiber bundle A in the application is SiCN fiber bundle or SiBCN fiber bundle, the axial conductivity is very high, the electrical behavior is similar to metal, and the fiber conductivity changes with the length, and the radial radius of the fiber is very small, so the conduction current generated when the fiber direction is perpendicular to the electric field is small and discontinuous, and the electromagnetic wave will not be directly reflected, the impedance matching is good, and at the same time, the loss capacity is strong, and the incoming electromagnetic wave can be rapidly attenuated. Therefore, the wave absorption performance is better when the arrangement direction of the fiber bundle A is perpendicular to the electric field direction in the electromagnetic wave.
[0013] As a preferred scheme, the size of the absorption unit in the composite fiber absorption layer is 7-10 mm, the thickness is 0.1-0.2 mm, and the same absorption units are arranged in parallel. The parallel arrangement of the same absorption units can realize direct reflection of the incident wave in the same direction.
[0014] As a preferred scheme, the distribution density of the A fibers in the fiber bundle A is 2-6 roots / cm 2 , and the distribution density of the SiCf fibers in the SiCf fiber bundle is 2-6 roots / cm 2 .
[0015] As a preferred scheme, the size of the composite fiber absorption layer of the application is 180 mm x 180 mm, and the length and width size can be adjusted according to the situation in actual operation.
[0016] As a preferred scheme, the thickness of the wave-absorbing layer is 0.5-3.5 mm. When the thickness increases, the overall reflection loss is obviously strengthened, and with the increase of the thickness, the minimum reflection loss value gradually moves from high frequency to low frequency.
[0017] As a preferred scheme, the fibers in the fiber bundle A and the SiCf fiber bundle in the absorbing unit are arranged in one direction. The fibers used in the present application are arranged in one direction, which can realize polarization sensitivity of the wave-absorbing structure.
[0018] As a preferred scheme, the wave-absorbing layer is 2 layers, the absorbing unit of the composite fiber absorbing layer in the surface wave-absorbing layer is H type, and the absorbing unit of the composite fiber absorbing layer in the lower wave-absorbing layer is lamp type. When this design is used, the effective absorbing bandwidth of 12.4525 GHz (less than -10 dB) and the excellent wave-absorbing performance of the minimum reflection loss of -20.18966 dB can be realized when the total thickness of the wave-absorbing layer is only 3 mm. This is because in the H type structure, a longer SiCN fiber bundle or SiBCN fiber bundle is used, and only two SiCf fiber bundles are used, which is two less than the lamp type structure, and the impedance matching is slightly poorer, but it is helpful for wave transmission. The impedance matching is better, and it has a certain electromagnetic wave loss capacity, which helps to quickly attenuate the entering electromagnetic wave, so that the H type used in the surface layer helps to realize the function of wave transmission, so that the electromagnetic wave quickly enters and is attenuated, and the lamp type used in the lower layer further utilizes the complex structure of the lamp type to intensify the loss of the entering electromagnetic wave, so that the overall structure greatly strengthens the loss capacity of the electromagnetic wave, thereby realizing a larger broadband wave-absorbing effect.
[0019] As a preferred scheme, the long axis direction of the fiber bundle A in the surface wave-absorbing layer is perpendicular to the electric field direction of the incident electromagnetic wave, and the long axis direction of the SiCf fiber bundle is parallel to the electric field direction of the incident electromagnetic wave.
[0020] As a preferred scheme, the SiCf fibers in the surface wave-absorbing layer and the lower wave-absorbing layer are distributed in parallel or vertically, and are further preferably distributed in parallel.
[0021] As a preferred scheme, the substrate is selected from one of an epoxy resin plate, a Si3N4 ceramic plate and a YB2C2 ceramic plate; and the metal sheet is selected from one of a copper sheet and an aluminum sheet. Further, the conductivity of the metal sheet is 10 7 S / m, and the thickness of the metal sheet is 0.02 mm, and the metal sheet is attached to the bottom of the substrate. The substrate is a low-loss substrate, the relative dielectric constant of which is less than 7, the loss tangent value of which is less than 0.02, and the thickness of which ranges from 0.5 mm to 2.5 mm.
[0022] The application further provides a preparation method of the resonant multi-component fiber composite broadband wave-absorbing structure.
[0023] The preparation method of the application is simple and easy to implement, the materials are common and easy to obtain, the application can be prepared on a large scale and is easy to repair.
[0024] Compared with the prior art, the application has the following beneficial effects:
[0025] (1) The specific fiber types with significant different dielectric properties are selected for combination and shape design between multiple layers in the application, so that a relatively wide effective absorption bandwidth and relatively strong wave-absorbing performance can be achieved at a relatively thin thickness, and the application can have an effective absorption bandwidth of 12.4525 GHz (less than -10 dB) and excellent wave-absorbing performance with a minimum reflection loss of -20.18966 dB when the total thickness of the wave-absorbing layer is only 3 mm.
[0026] (2) The shapes of the absorption units in the composite fiber absorption layers of any two adjacent wave-absorbing layers are different, which disrupts the phase relationship of the reflected waves between the layers, so that the overall structure can have good response to electromagnetic waves with different polarization directions, and can form multi-frequency point complementary resonance response, and these resonance peaks are staggered and superimposed in the frequency domain, thereby effectively widening the absorption bandwidth of the overall structure of the material. The multiple patches in the multi-layer design can intensify the loss of electromagnetic waves, and the patches in the lower layer, the substrate and the metal sheet together form a fiber-substrate-metal resonator, so that the impedance gradient transition of electromagnetic waves from the surface layer to the bottom layer is realized, the direct reflection of the incident wave is reduced, and the wave-absorbing efficiency and broadband characteristics are further improved.
[0027] (3) The preparation method of the application is simple and easy to implement, the materials are common and easy to obtain, the application can be prepared on a large scale and is easy to repair. BRIEF DESCRIPTION OF DRAWINGS
[0028] Figure 1 The figure is a real object diagram of the double-layer resonant SiCf-A broadband composite array wave-absorbing structure prepared in Example 1 of the application. Among them, (a) is the first wave-absorbing layer, and (b) is the second wave-absorbing layer.
[0029] Figure 2The reflectivity curve test result of the double-layer resonant SiCf-A broadband composite array wave-absorbing structure prepared in Example 1 in the present application in the range of 1-18 GHz.
[0030] Figure 3 The physical diagram of the double-layer resonant SiCf-A broadband composite array wave-absorbing structure prepared in Example 2 in the present application. Wherein, (a) is the first layer of wave-absorbing layer, (b) is the second layer of wave-absorbing layer.
[0031] Figure 4 The reflectivity curve test result of the double-layer resonant SiCf-A broadband composite array wave-absorbing structure prepared in Example 2 in the present application in the range of 1-18 GHz.
[0032] Figure 5 The physical diagram of the double-layer resonant SiCf-A broadband composite array wave-absorbing structure prepared in Example 3 in the present application. Wherein, (a) is the second layer of wave-absorbing layer, (b) is the first layer of wave-absorbing layer.
[0033] Figure 6 The reflectivity curve test result of the double-layer resonant SiCf-A broadband composite array wave-absorbing structure prepared in Example 3 in the present application in the range of 1-18 GHz.
[0034] Figure 7 The physical diagram of the double-layer resonant SiCf-A broadband composite array wave-absorbing structure prepared in Example 4 in the present application. Wherein, (a) is the second layer of wave-absorbing layer, (b) is the first layer of wave-absorbing layer.
[0035] Figure 8 The reflectivity curve test result of the double-layer resonant SiCf-A broadband composite array wave-absorbing structure prepared in Example 4 in the present application in the range of 1-18 GHz.
[0036] Figure 9 The physical diagram of the three-layer resonant SiCf-A broadband composite array wave-absorbing structure prepared in Example 5 in the present application. Wherein, (a) is the first layer of wave-absorbing layer, (b) is the second layer of wave-absorbing layer, (c) is the third layer of wave-absorbing layer.
[0037] Figure 10 The reflectivity curve test result of the three-layer resonant SiCf-A broadband composite array wave-absorbing structure prepared in Example 5 in the present application in the range of 1-18 GHz.
[0038] Figure 11 The physical diagram of the single-layer lamp-shaped SiCf-A combined array resonant absorbing structure with different thickness prepared in Comparative Example 1 in the present application, wherein (a) is longitudinally placed, (b) is transversely placed.
[0039] Figure 12 The reflectivity curve test results of the single-layer lamp-shaped SiCf-A combination array resonant absorption structure of different thickness prepared in the present application Comparative Example 1 in the range of 1-18 GHz in transverse placement or longitudinal placement.
[0040] Figure 13 The physical diagram of the double-layer H-shaped multi-element fiber composite broadband wave-absorbing structure prepared in the present application Comparative Example 2. Wherein, (a) is the first wave-absorbing layer, and (b) is the second wave-absorbing layer.
[0041] Figure 14 The reflectivity curve test results of the double-layer H-shaped multi-element fiber composite broadband wave-absorbing structure prepared in the present application Comparative Example 2 in the range of 1-18 GHz.
[0042] Figure 15 The physical diagram of the double-layer lamp-shaped multi-element fiber composite broadband wave-absorbing structure prepared in the present application Comparative Example 3. Wherein, (a) is the first wave-absorbing layer, and (b) is the second wave-absorbing layer.
[0043] Figure 16 The reflectivity curve test results of the double-layer lamp-shaped multi-element fiber composite broadband wave-absorbing structure prepared in the present application Comparative Example 3 in the range of 1-18 GHz.
[0044] Figure 17 The structure schematic diagram of the H-shaped absorption unit of the combination of fiber bundle A and SiCf fiber bundle.
[0045] Figure 18 The structure schematic diagram of the composite fiber absorption layer composed of the periodic array of H-shaped absorption units.
[0046] Figure 19 The structure schematic diagram of the lamp-shaped absorption unit of the combination of fiber bundle A and SiCf fiber bundle.
[0047] Figure 20 The structure schematic diagram of the composite fiber absorption layer composed of the periodic array of lamp-shaped absorption units.
[0048] Figure 21 The structure schematic diagram of the lamp-shaped absorption unit of the combination of fiber bundle A and SiCf fiber bundle in Comparative Example 1 and the relationship with electromagnetic field. DETAILED DESCRIPTION
[0049] The technical solutions of the present application are further illustrated by the specific embodiments. Those skilled in the art should understand that the embodiments are only used to understand the present application and should not be regarded as specific limitations to the present application.
[0050] The structure schematic diagram of the H-shaped absorption unit in the present application embodiments and comparative examples is shown in the accompanying drawings. Figure 17As shown in the attached diagram, a composite fiber absorption layer composed of a periodic array of H-shaped absorption units is also included. Figure 18 As shown in the attached diagram; a schematic diagram of the lamp-type absorption unit is also included. Figure 19 As shown in the attached diagram, a composite fiber absorption layer composed of a periodic array of lamp-like absorption units is also included. Figure 20 As shown in the physical image, whether it is a lamp-shaped or H-shaped structure, the longer fibers are SiCf fiber bundles, and the shorter fibers are fiber bundles A. The distribution density of A fibers in fiber bundle A is 2~6 fibers / cm. 2 The distribution density of SiCf fibers in SiCf fiber bundles is 2~6 fibers / cm. 2 .
[0051] Example 1
[0052] FR4 epoxy resin sheets with thicknesses of 2.5mm and 0.5mm are used, with a dielectric constant of 4.4 and a loss tangent of 0.02mm. The sheets of different thicknesses are cut to a size of 180mm×180mm, and a copper sheet with a thickness of 0.02mm is attached to the bottom surface of the second layer of FR4 epoxy resin sheet.
[0053] Fiber bundle A is cut to a length of 2mm-5mm, and SiCf fiber bundle is cut to a length of 7mm. The 5mm fiber bundle A and the 7mm SiCf fiber bundle are then embedded into the upper surface of the first layer substrate using a needle-punching method. In a 10mm × 10mm unit, two parallel SiCf bundles spaced 5mm apart are vertically arranged between two fiber bundles A, forming an H-shaped pattern. This pattern is then arrayed across the entire surface of the first layer epoxy resin substrate. The resulting pattern is shown in the attached figure. Figure 1 As shown in (a), it forms the first absorbing layer.
[0054] Four 2mm fiber bundles (A) and four 7mm SiCf fiber bundles (SCF) were embedded into the surface of the second epoxy resin substrate (0.5mm thick) using a needle-punching method. Fiber bundles A are SiCN fiber bundles. In a 10mm × 10mm unit, four parallel SiCf bundles spaced 1mm apart are vertically arranged in the center, forming a lamp-like pattern. This pattern is then arrayed across the entire surface of the second epoxy resin substrate. The resulting pattern is shown in the attached figure. Figure 1The SiCf-A fiber bundles in the H-shaped pattern are connected as follows: four SiCf fiber bundles are arranged in parallel and at intervals, and four fiber bundles A are arranged in parallel and at intervals; the two ends of the first fiber bundle A are connected perpendicularly to the middle of the first SiCf fiber bundle and the second SiCf fiber bundle, respectively; the two ends of the second fiber bundle A are connected perpendicularly to one end of the second SiCf fiber bundle and the third SiCf fiber bundle, respectively; the two ends of the third fiber bundle A are connected perpendicularly to the other end of the second SiCf fiber bundle and the third SiCf fiber bundle, respectively; and the two ends of the fourth fiber bundle A are connected perpendicularly to the middle of the third SiCf fiber bundle and the fourth SiCf fiber bundle, respectively.
[0055] The first layer of the wave-absorbing layer and the second layer of the wave-absorbing layer are stacked in a top-to-bottom manner, and a copper metal sheet with a thickness of 0.02 mm is attached to the bottom surface of the second layer of the wave-absorbing layer, to obtain a double-layer resonant SiCf-A broadband composite array wave-absorbing structure. The SiCf fibers in the upper and lower layers are arranged in parallel, and the long axis direction of the fiber bundle A in the H-shaped structure in the first layer is perpendicular to the electric field direction of the incident electromagnetic wave, and the long axis direction of the SiCf fiber bundle is parallel to the electric field direction of the incident electromagnetic wave, to form a resonator of fiber-dielectric-metal with a total thickness of 3 mm. The actual photographs of the upper and lower layers are shown in FIG. 6. Figure 1
[0056] According to the reflectivity test method for radar wave-absorbing materials in GJB2038-94, the reflectivity of the obtained wave-absorbing structure is tested by using a normal-temperature reflectivity measurement system based on the arch frame method flat plate. In the reflectivity measurement of radar wave-absorbing materials, the reflection of electromagnetic waves by objects around the measured sample directly affects the accuracy of the measurement. Therefore, high-loss cone wave-absorbing bodies are laid around the sample holder to simulate an infinite radiation boundary. The test frequency range is 1-18 GHz, the incident angle is 5°, and the test error (R>-10 dB) is <±1 dB.
[0057] The reflectivity curve of the prepared sample with a total thickness of 3 mm in the frequency range of 1-18 GHz is shown in FIG. 7, and the reflectivity curve of the prepared sample with a total thickness of 3 mm in the frequency range of 1-18 GHz is shown in FIG. 8. Figure 2 Figure 2 It is shown that the wave-absorbing structure of the embodiment has an effective absorption bandwidth of 12.4525 GHz (less than-10 dB) and excellent wave-absorbing performance with a minimum reflectivity of-20.18966 dB.
[0058] Example 2
[0059] The preparation of the first layer of the wave-absorbing layer and the second layer of the wave-absorbing layer in this embodiment is the same as in Embodiment 1, except that when the first layer of the wave-absorbing layer and the second layer of the wave-absorbing layer are stacked from top to bottom, the SiCf fibers of the upper and lower layers are vertically distributed, and the remaining steps and conditions are consistent to prepare a double-layer resonant SiCf-A wideband composite array wave-absorbing structure. A fiber-dielectric-metal resonator with a total thickness of 3 mm is formed, and the physical diagram of the upper and lower layers is shown in FIG. 8. Figure 3
[0060] The test is the same as in Embodiment 1. The reflectance loss curve of the prepared sample with a total thickness of 3 mm in the frequency range of 1-18 GHz is shown in FIG. 9. Figure 4 Figure 4 It can be seen from FIG. 9 that the wave-absorbing structure of this embodiment has an effective absorption bandwidth of 9.86 GHz (less than -10 dB) and excellent wave-absorbing performance with a minimum reflectance loss of -18.3307 dB.
[0061] Embodiment 3
[0062] The preparation of the first layer of the wave-absorbing layer and the second layer of the wave-absorbing layer in this embodiment is the same as in Embodiment 1, except that when the first layer of the wave-absorbing layer and the second layer of the wave-absorbing layer are stacked, the second layer of the wave-absorbing layer is placed on the surface layer, the first layer of the wave-absorbing layer is placed on the lower layer, and a copper metal sheet with a thickness of 0.02 mm is attached to the bottom surface of the first layer of the wave-absorbing layer. That is, the surface layer absorption unit adopts a lamp-like shape, the lower layer absorption unit adopts an H shape, and the SiCf fibers of the upper and lower layers are parallelly distributed to obtain a double-layer resonant SiCf-A wideband composite array wave-absorbing structure. Moreover, the long axis direction of the fiber bundle A of the H-shaped structure in the first layer is perpendicular to the electric field direction of the incident electromagnetic wave, and the long axis direction of the SiCf fiber bundle is parallel to the electric field direction of the incident electromagnetic wave to obtain a fiber-dielectric-metal resonator with a total thickness of 3 mm. The physical diagram of the upper and lower layers is shown in FIG. 10. Figure 5
[0063] The test is the same as in Embodiment 1. The reflectance loss curve of the prepared sample with a total thickness of 3 mm in the frequency range of 1-18 GHz is shown in FIG. 11. Figure 6 Figure 6 As shown in FIG. 11, the wave-absorbing structure of this embodiment has an effective absorption bandwidth of 5.6525 GHz (less than -10 dB) and excellent wave-absorbing performance with a minimum reflectance loss of -14.42771 dB. However, compared with Embodiment 1, the wave-absorbing bandwidth and minimum reflectance loss of this embodiment are slightly worse than those of Embodiment 1, indicating that the surface layer adopting an H shape and the bottom layer adopting a lamp-like shape have better effects.
[0064] Embodiment 4
[0065] The only difference between this embodiment and Embodiment 3 is that the SiCf fibers in the upper and lower layers are vertically distributed during stacking. All other steps and conditions remain the same, resulting in a double-layer resonant SiCf-A broadband composite array absorbing structure. This forms a fiber-dielectric-metal resonator with a total absorbing layer thickness of 3mm. Actual images of the upper and lower layers are attached. Figure 7 As shown.
[0066] The test was the same as in Example 1. The reflection loss curve of the prepared sample with a total thickness of 3 mm in the 1~18 GHz frequency band is shown in the attached figure. Figure 8 As shown in the attached document. Figure 8 As shown, the absorbing structure of this embodiment has both an effective absorption bandwidth of 7.055 GHz (less than -10 dB) and excellent absorption performance with a minimum reflection loss of -15.76796 dB. It also has dual-band absorption performance and has absorption bandwidth when the frequency is greater than or equal to 16 GHz.
[0067] Example 5
[0068] FR4 epoxy resin sheets with thicknesses of 0.5mm, 2.5mm, and 0.5mm were used, with a dielectric constant of 4.4 and a loss tangent of 0.02mm. Sheets of all thicknesses were cut to a size of 180mm × 180mm.
[0069] Four 2mm fiber bundles (A) and four 7mm SiCf fiber bundles (S) were embedded into the surface of the first and third epoxy resin substrates (each layer is 0.5mm thick) using a needle-punching method. Four parallel SiCf fiber bundles, spaced 1mm apart, were vertically arranged in the center of a 10mm × 10mm unit, forming a lamp-like pattern. This pattern was then arrayed across the entire surface of the first and third epoxy resin substrates, as shown in the attached diagram. Figure 9 As shown in (a) and (c) in the diagram. The connection relationship of each fiber bundle in the lamp-shaped pattern is as follows: four SiCf fiber bundles are arranged in parallel and spaced apart, and four fiber bundles A are arranged in parallel and spaced apart; the two ends of the first fiber bundle A are perpendicularly connected to the middle of the first SiCf fiber bundle and the second SiCf fiber bundle, respectively; the two ends of the second fiber bundle A are perpendicularly connected to one end of the second SiCf fiber bundle and the third SiCf fiber bundle, respectively; the two ends of the third fiber bundle A are perpendicularly connected to the other end of the second SiCf fiber bundle and the third SiCf fiber bundle, respectively; and the two ends of the fourth fiber bundle A are perpendicularly connected to the middle of the third SiCf fiber bundle and the fourth SiCf fiber bundle, respectively, thus obtaining the first absorbing layer and the third absorbing layer.
[0070] The fiber bundle A is cut to a length of 2 mm to 5 mm, the fiber bundle A is a SiCN fiber bundle, the SiCf fiber bundle is cut to a length of 7 mm, and the 5 mm fiber bundle A and the 7 mm SiCf fiber bundle are embedded on the upper surface (thickness of 2.5 mm) of the second layer of epoxy resin base material by the method of needle punching, a bundle of fiber bundle A is vertically arranged in the middle of the two parallel SiCf bundles spaced 5 mm apart in the middle of the 10 mm x 10 mm size unit, forming an H-shaped pattern, and the obtained pattern is shown in (b) of the accompanying Figure 9 , and the array is arranged on the entire surface of the second layer of base material to obtain a second layer of wave-absorbing layer.
[0071] The first layer of wave-absorbing layer to the third layer of wave-absorbing layer are stacked from top to bottom, and a copper metal sheet with a thickness of 0.02 mm is attached to the bottom surface of the third layer of wave-absorbing layer, and a three-layer resonant SiCf-A broadband composite array wave-absorbing structure is obtained. The SiCf fibers in the three layers are distributed in parallel, and the long axis direction of the H-shaped structure fiber bundle A in the second layer is perpendicular to the electric field direction of the incident electromagnetic wave, and the long axis direction of the SiCf fiber bundle is parallel to the electric field direction of the incident electromagnetic wave, forming a resonator of fiber-dielectric-metal with a total thickness of 3.5 mm of the wave-absorbing layer, and the physical diagram of the upper, middle and lower three layers is shown in the accompanying Figure 9 .
[0072] The test is the same as in Example 1, and the reflection loss curve of the prepared sample with a total thickness of 3.5 mm in the frequency range of 1 to 18 GHz is shown in the accompanying Figure 10 . As can be seen from the accompanying Figure 10 , the wave-absorbing structure of the present embodiment has an effective absorption bandwidth of 13.2175 GHz (less than -10 dB) and excellent wave-absorbing performance with a minimum reflection loss of -15.80275 dB. Compared with Example 3, it is shown that increasing one layer of wave-absorbing layer can further improve the absorption bandwidth and minimum reflection loss performance.
[0073] Comparative Example 1
[0074] FR4 epoxy resin plates with thicknesses of 0.5 mm, 1.5 mm, 2.5 mm and 3.0 mm, respectively, with a dielectric constant of 4.4 and a loss tangent of 0.02 mm. The plates with different thicknesses are all cut to a size of 180 mm x 180 mm, and are prepared according to the lamp-shaped pattern of the second layer of wave-absorbing layer in Example 1, and are arrayed on the entire FR4 epoxy resin plate. A copper metal sheet with a thickness of 0.02 mm is attached to the bottom of the epoxy resin plate to obtain a 0.5 mm single-layer lamp type, a 1.5 mm single-layer lamp type, a 2.5 mm single-layer lamp type and a 3.0 mm single-layer lamp type.
[0075] The single-layer lamp types with different thicknesses are tested in the electric field by placing them horizontally and vertically, respectively, and the test is the same as in Example 1. The results are shown in the accompanying Figure 12shown. Among them, the transverse placement refers to the overall pattern is transversely placed, that is, the long axis direction of the fiber bundle A in the lamp type pattern is perpendicular to the electric field direction of the incident electromagnetic wave, and the long axis direction of the SiCf fiber bundle is parallel to the electric field direction of the incident electromagnetic wave. The longitudinal placement refers to the overall pattern is longitudinally placed, that is, the long axis direction of the fiber bundle A in the lamp type pattern is parallel to the electric field direction of the incident electromagnetic wave, and the long axis direction of the SiCf fiber bundle is perpendicular to the electric field direction of the incident electromagnetic wave. The schematic diagram is shown in FIG. 2B. Figure 21
[0076] The results of the test are shown in FIG. 3B. Figure 12 It can be seen that there is no effective absorption bandwidth for the single-layer lamp type in different thicknesses, whether transversely placed or longitudinally placed.
[0077] Comparative Example 2
[0078] The test method and preparation process are consistent with Example 1, except that the second layer of wave-absorbing layer also adopts H-shaped pattern array with a thickness of 0.5 mm. The first layer of wave-absorbing layer and the second layer of wave-absorbing layer are stacked in the order from top to bottom, and a copper metal sheet with a thickness of 0.02 mm is attached to the bottom surface of the second layer of wave-absorbing layer, to obtain a double-layer H-shaped multi-element fiber composite broadband wave-absorbing structure. The SiCf fibers of the upper and lower layers are in parallel distribution, and the long axis direction of the fiber bundle A of the H-shaped structure in the first layer is perpendicular to the electric field direction of the incident electromagnetic wave, and the long axis direction of the SiCf fiber bundle is parallel to the electric field direction of the incident electromagnetic wave, to form a fiber-dielectric-metal resonator with a total thickness of 3 mm of the wave-absorbing layer. The actual photograph of the upper and lower layers is shown in FIG. 4B. Figure 13
[0079] The test is the same as Example 1, and the reflection loss curve of the prepared sample with a total thickness of 3 mm in the frequency range of 1-18 GHz is shown in FIG. 5B. Figure 14 The results of the test are shown in FIG. 5B. Figure 14 It can be seen from the results of the test that when the upper and lower layers both adopt H-shaped structure, the absorption bandwidth is obviously reduced when the thickness is 3 mm, and the minimum reflection loss is also obviously deteriorated.
[0080] Comparative Example 3
[0081] The test method and preparation process are consistent with Example 1, except that the first layer of wave-absorbing layer also adopts lamp type pattern array with a thickness of 0.5 mm. The first layer of wave-absorbing layer and the second layer of wave-absorbing layer are stacked in the order from top to bottom, and a copper metal sheet with a thickness of 0.02 mm is attached to the bottom surface of the second layer of wave-absorbing layer, to obtain a double-layer lamp type multi-element fiber composite broadband wave-absorbing structure. The SiCf fibers of the upper and lower layers are in parallel distribution, and the transverse placement is adopted, to form a fiber-dielectric-metal resonator with a total thickness of 3 mm of the wave-absorbing layer. The actual photograph of the upper and lower layers is shown in FIG. 6B. Figure 15
[0082] The reflection loss curve of the sample prepared in Example 1 with a total thickness of 3 mm in the frequency range of 1-18 GHz is shown in Fig. 2. It can be seen from the results shown in Fig. 2 that when the upper and lower layers are both in the lamp-like structure, the absorption bandwidth is obviously reduced when the thickness is 3 mm, and the minimum reflection loss is also obviously deteriorated. Figure 16 Figure 16 The reflection loss curve of the sample prepared in Example 1 with a total thickness of 3 mm in the frequency range of 1-18 GHz is shown in Fig. 2. It can be seen from the results shown in Fig. 2 that when the upper and lower layers are both in the lamp-like structure, the absorption bandwidth is obviously reduced when the thickness is 3 mm, and the minimum reflection loss is also obviously deteriorated.
Claims
1. A resonant multi-component fiber composite broadband absorbing structure, characterized in that: The metal sheet and the wave-absorbing layer are included; the wave-absorbing layer is 2 layers, each layer of the wave-absorbing layer is composed of a substrate and a composite fiber absorbing layer on the surface of the substrate; the composite fiber absorbing layer has a periodic array structure; the periodic array structure includes a plurality of absorbing units, each absorbing unit is formed into an H type or a lamp type shape by connecting a fiber bundle A and a SiCf fiber bundle; and the absorbing units of the composite fiber absorbing layer in the surface wave-absorbing layer are H type, and the absorbing units of the composite fiber absorbing layer in the lower wave-absorbing layer are lamp type; The fiber bundle A is selected from at least one of SiCN fiber bundle and SiBCN fiber bundle; The lamp type is composed of four SiCf fiber bundles and four fiber bundles A, the four SiCf fiber bundles are first SiCf fiber bundle, second SiCf fiber bundle, third SiCf fiber bundle and fourth SiCf fiber bundle respectively, the four fiber bundles A are first fiber bundle A, second fiber bundle A, third fiber bundle A and fourth fiber bundle A respectively, the four SiCf fiber bundles are arranged in parallel and at intervals, and the four fiber bundles A are arranged in parallel and at intervals; the two ends of the first fiber bundle A are vertically connected with the first SiCf fiber bundle and the second SiCf fiber bundle respectively, the two ends of the second fiber bundle A are vertically connected with the second SiCf fiber bundle and one end of the third SiCf fiber bundle respectively, the two ends of the third fiber bundle A are vertically connected with the second SiCf fiber bundle and the other end of the third SiCf fiber bundle respectively, and the two ends of the fourth fiber bundle A are vertically connected with the third SiCf fiber bundle and the middle of the fourth SiCf fiber bundle respectively.
2. The resonant multi-component fiber composite broadband wave-absorbing structure according to claim 1, wherein: the H type is composed of the fiber bundle A vertically connected between two parallel distributed SiCf fiber bundles. The size of the absorbing unit in the composite fiber absorbing layer ranges from 7 to 10 mm, the thickness is 0.1-0.2 mm, and the same absorbing units are arranged in parallel.
3. The resonant multi-pack fiber composite broadband wave-absorbing structure according to claim 1 or 2, characterized in that: The thickness of the wave-absorbing layer is 0.5-3.5 mm.
4. The resonant multi-cellular fiber composite broadband wave-absorbing structure according to claim 3, characterized in that: The fibers in the fiber bundle A and the SiCf fiber bundle in the absorbing unit are arranged in one direction.
5. The resonant multi-pack fiber composite broadband wave-absorbing structure according to claim 1, characterized in that: In the surface wave-absorbing layer, the long axis direction of the fiber bundle A is perpendicular to the electric field direction of the incident electromagnetic wave, and the long axis direction of the SiCf fiber bundle is parallel to the electric field direction of the incident electromagnetic wave.
6. The resonant multi-pack fiber composite broadband wave-absorbing structure according to claim 1, characterized in that: The SiCf fibers in the surface wave-absorbing layer and the lower wave-absorbing layer are arranged in parallel or vertically.
7. The resonant multi-cellular fiber composite broadband wave-absorbing structure according to claim 6, characterized in that: The substrate is selected from one of an epoxy resin plate, a Si3N4 ceramic plate and a YB2C2 ceramic plate; and the metal sheet is selected from one of a copper sheet and an aluminum sheet.
8. The resonant multi-pack fiber composite broadband wave-absorbing structure according to claim 1, characterized in that: After the fiber bundle A and the SiCf fiber bundle are cut into segments, the absorbing units are combined according to the designed shape, fixed on the surface of the substrate by needling or pasting, and arranged periodically on the surface of the substrate to obtain the wave-absorbing layer; and the wave-absorbing layer is pasted on the metal sheet to obtain the wave-absorbing structure.
9. The method for preparing a resonant multi-pack fiber composite broadband wave-absorbing structure according to any one of claims 1-8, characterized in that: The wave-absorbing layer is 2 layers, and the absorbing units of the composite fiber absorbing layer in the surface wave-absorbing layer are H type, and the absorbing units of the composite fiber absorbing layer in the lower wave-absorbing layer are lamp type. The fiber bundle A is selected from at least one of SiCN fiber bundle and SiBCN fiber bundle.
Citation Information
Patent Citations
Cf / SiCf combined absorption unit and array resonance absorption structure
CN117791173A