Fiber composite multilayer structure reinforced wave-absorbing material and preparation method thereof

Abstract

The application discloses a kind of fiber composite multilayer structure reinforced wave-absorbing materials, it is characterized in that, the wave-absorbing material is composed of fiber layer and wave-absorbing layer, the fiber layer is located wave-absorbing layer top, located wave-absorbing layer bottom or between two wave-absorbing layers.The wave-absorbing material can improve the wave-absorbing performance of single wave-absorbing sheet, tensile strength, also can realize wave-absorbing peak to low frequency movement.The application further discloses a kind of preparation method of fiber composite multilayer structure reinforced wave-absorbing material.

Description

Technical Field

[0001] This invention belongs to the field of microwave absorbing materials, specifically relating to a fiber composite multilayer structure reinforced microwave absorbing material and its preparation method. Background Technology

[0002] With the development of 5G+ and Internet of Things communication technologies, electromagnetic interference inside high-frequency electronic devices seriously affects the normal operation of related equipment. At the same time, military equipment has an urgent need for radar stealth. Therefore, it is crucial to develop absorbing materials with high electromagnetic wave absorption intensity.

[0003] Furthermore, the rapid updates and iterations of artificial intelligence technology are driving the rapid development of self-driving cars and military drones. Therefore, developing integrated stealth wave-absorbing materials with excellent wave absorption and high mechanical strength will help to make up for the shortcomings of material technology and promote the application of new materials to a new level.

[0004] Patent application CN109880377A discloses a method for preparing a silicone / carbonyl iron powder composite broadband absorbing sheet, comprising the following steps: A) Wet modification of carbonyl iron powder and non-magnetic inorganic powder using a silane coupling agent to obtain modified carbonyl iron powder and modified non-magnetic inorganic powder; the mass ratio of the silane coupling agent to the carbonyl iron powder is (0.3-2):100; the mass ratio of the silane coupling agent to the non-magnetic inorganic powder is (0.3-2):100; B) Mixing a vinyl silicone oil composition, a hydrogen-containing silicone oil composition, the modified carbonyl iron powder and the modified non-magnetic inorganic powder obtained in step A) to obtain a premixed adhesive; C) Adding an inhibitor and a platinum catalyst to the premixed adhesive to obtain a mixed adhesive; D) Calendering the mixed adhesive and curing it at high temperature to obtain a silicone / carbonyl iron powder composite broadband absorbing sheet. This invention also provides a silicone / carbonyl iron powder composite broadband absorbing sheet. However, the mechanical properties of the absorbing sheet disclosed in this patent are poor, and it cannot effectively control the absorption peak towards low frequencies.

[0005] Patent application CN109207123A discloses a double-shell carbonyl iron powder composite microwave absorbing material and its preparation method. The composite microwave absorbing material has a double-shell core-shell structure, with carbonyl iron powder as the core, an inner insulating layer, and an outer magnetic layer. The thickness of the insulating layer is 1 nm-1 μm, and the thickness of the magnetic layer is 1 nm-5 μm. The preparation method includes coating the surface of the carbonyl iron powder with an insulating layer using a chemical co-precipitation method and coating the surface of the core-shell structure precursor with a magnetic layer. This invention uniformly coats the surface of the carbonyl iron powder with a double-shell structure through chemical co-precipitation, significantly improving the impedance matching characteristics of the material. Simultaneously, it forms a large number of nano-interfacial heterojunctions at the core-shell interface, effectively inducing interfacial polarization and creating a scattering effect on electron migration. This significantly enhances the material's electromagnetic wave loss mechanisms, such as multiple reflection absorption, strong ferromagnetic resonance, and eddy current loss, thereby significantly improving the material's microwave absorption performance. The preparation method is simple, the coating is uniform and dense, and the coating thickness and particle size are controllable. However, the mechanical properties of the absorbing sheet disclosed in this patent are poor. Summary of the Invention

[0006] This invention provides a fiber composite multilayer structure reinforced microwave absorbing material, which can improve the microwave absorption performance and tensile strength of a single microwave absorbing sheet, and can also achieve the shift of the absorption peak to low frequency.

[0007] The present invention provides a fiber composite multilayer structure reinforced microwave absorbing material, the microwave absorbing material being composed of a fiber layer and a microwave absorbing layer, wherein the fiber layer is located at the top of the microwave absorbing layer, at the bottom of the microwave absorbing layer, or between two microwave absorbing layers.

[0008] Preferably, the fiber layer is a single-layer woven fabric or multiple single-layer woven fabrics stacked together. The single-layer woven fabric is made of a mixture of magnetic fibers and glass fibers in warp and weft weaving. The magnetic fibers are woven and arranged at intervals, and the spacing between the magnetic fibers is 1-100mm.

[0009] The absorbing layer is composed of an electromagnetic wave composite matrix and an electromagnetic wave absorber.

[0010] Since the magnetic fibers and glass fibers provided by this invention have high tensile strength, the woven fiber layer also has high tensile strength. Thus, the combination of the absorbing sheet and the fiber layer with high tensile strength can obtain a composite absorbing material with high tensile strength. This invention enhances the absorption performance and absorption bandwidth by controlling the spacing of the magnetic fibers.

[0011] Preferably, the magnetic fiber consists of a magnetic core and a glass outer layer that encloses the magnetic core, or is composed of a magnetic core.

[0012] More preferably, the magnetic core is made of cobalt-based amorphous alloy fiber, iron fiber, cobalt-nickel alloy fiber, or iron-nickel alloy fiber. The fibers provided by this invention possess high permeability, wide bandwidth, high saturation magnetization, and low coercivity. Therefore, in synergy with the absorbing layer, they can enhance the absorption performance and expand the absorption bandwidth.

[0013] Preferably, the diameter of the magnetic fiber is 5-200 μm.

[0014] More preferably, the diameter of the magnetic fiber is 10-100 μm, the diameter of the magnetic core is 5-95 μm, and the thickness of the glass outer layer is 2.5-25 μm.

[0015] Preferably, the magnetic fibers and glass fibers of the single-layer woven fabric have a weave structure of at least one of plain weave, twill weave, and satin weave.

[0016] Preferably, the electromagnetic wave composite matrix is ​​epoxy resin, phenolic resin, polyurethane, polypropylene, polyetheretherketone, or silicone.

[0017] The electromagnetic wave absorber is one or more of the following: carbonyl iron, iron-silicon-aluminum, iron-nickel, amorphous alloy, graphene, carbon black, and MXene.

[0018] Preferably, the fiber layer is located on top of the microwave absorbing layer, and the magnetic fiber is composed of a magnetic inner core and a glass outer layer that wraps the magnetic inner core, with the spacing between each magnetic fiber being 10-30 mm;

[0019] The thickness of the absorbing layer is 0.5-5mm, and the electromagnetic wave absorber is carbonyl iron, with the carbonyl iron accounting for 10%-95% of the mass of the absorbing layer.

[0020] When the fiber layer is located on top of the absorbing layer, by controlling the thickness of the absorbing layer, the mass ratio of the electromagnetic absorber carbonyl iron, and the spacing between each magnetic fiber, the tensile strength, absorption intensity, and effective absorption bandwidth of a single absorbing sheet can be improved simultaneously.

[0021] Preferably, the fiber layer is located at the bottom of the microwave absorbing layer, the magnetic fiber is composed of a magnetic core, and the spacing between the magnetic fibers in the fiber layer is 1-100 mm;

[0022] The thickness of the absorbing layer is 0.8-1.1 mm, and the electromagnetic wave absorber is carbonyl iron, with the carbonyl iron accounting for 10%-95% of the mass of the absorbing layer.

[0023] When the fiber layer is located at the bottom of the absorbing layer, by controlling the thickness of the absorbing layer, the mass ratio of the electromagnetic absorber carbonyl iron, and the spacing of each magnetic fiber, the tensile strength and absorption intensity of a single absorbing sheet can be improved simultaneously, and the absorption peak can be shifted to lower frequencies, so that the composite absorbing material provided by the present invention can be better applied in more scenarios.

[0024] Preferably, the absorption frequency band of the fiber composite multilayer structure reinforced microwave absorbing material is 1-40 GHz.

[0025] On the other hand, the present invention also provides a method for preparing the fiber composite multilayer structure reinforced microwave absorbing material, comprising:

[0026] Magnetic cores are prepared by melt drawing, hydrospinning or spinning. Glass is wrapped around the outer surface of the magnetic core to obtain magnetic fibers. The magnetic fibers are mixed with glass fibers at a set interval and woven into a single layer. The single layer or multiple single layers are stacked to obtain a fiber layer.

[0027] An electromagnetic wave composite matrix and an electromagnetic wave absorber are stirred and mixed, and then calendered to obtain a wave-absorbing sheet.

[0028] The fiber layer is attached to the top or bottom of the absorbing layer or between two absorbing layers to obtain the absorbing material.

[0029] On the other hand, the fiber composite multilayer structure reinforced microwave absorbing material provided by the present invention can be applied to scenarios in military and civilian fields that require electromagnetic compatibility and electromagnetic environment optimization.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] This invention achieves superior mechanical properties by attaching fiber layers with good magnetic and mechanical properties to the top, bottom, or between absorbing layers. This enhances the absorption performance of individual absorbing layers. Furthermore, attaching fiber layers to the top of the absorbing layers shifts the absorption peak to lower frequencies, facilitating the widespread application of the composite absorbing material provided by this invention in practice. Attached Figure Description

[0032] Figure 1 The absorption performance diagrams of the microwave absorbing composite material with a thickness of 0.5 mm are provided for Examples 1-3 and Comparative Examples 1-2.

[0033] Figure 2 The absorption performance diagrams of the microwave absorbing composite material with a thickness of 2.5 mm are provided for Examples 4-6 and Comparative Examples 3-4.

[0034] Figure 3The absorption performance diagrams of the microwave absorbing composite material with a thickness of 5 mm are provided for Examples 7-8 and Comparative Examples 5-6.

[0035] Figure 4 The microwave absorption performance diagrams are for the microwave absorbing composite materials provided in Examples 9-14 and Comparative Examples 7-9.

[0036] Figure 5 The microwave absorption performance diagrams are for the microwave absorbing composite materials provided in Examples 15-17 and Comparative Examples 10-12. Detailed Implementation

[0037] The present invention will be further described in detail below through embodiments. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments.

[0038] Examples 1-9 and Comparative Examples 1-6

[0039] In Examples 1-9 of this invention, a fiber layer is adhered to the surface of an absorbing sheet to prepare a composite absorbing material.

[0040] Magnetic fibers with a diameter of 50 micrometers were prepared using a melt-drawing method. The magnetic core diameter was 30 micrometers, and the magnetic core material was CoFeSiBCrMo. The glass-coated outer layer was 10 micrometers thick. The magnetic fibers were mixed with glass fibers and woven in a plain weave at intervals of 10 mm, 20 mm, and 30 mm to form a woven fabric. The specific spacing of the magnetic fibers is shown in Table 1.

[0041] Table 1. Distribution of magnetic fiber spacing in different fiber layers

[0042] Sample Name Z (Comparative Example 1) A B C Magnetic fiber spacing Non-magnetic fibers 10 mm 20 mm 30 mm

[0043] Meanwhile, carbonyl iron (80% by mass) and silica gel (20% by mass) were thoroughly mixed and then passed through a casting film machine to prepare microwave absorbing sheets with thicknesses of 0.5, 2.5, and 5 mm, respectively, named 80-0.5, 80-2.5, and 80-5.

[0044] The above-mentioned fiber braided layer and the absorbing sheet are compositely stacked, with the fiber layer on top and the absorbing sheet on the bottom, and bonded with silicone to obtain a composite absorbing material. The sample name A+80-0.5 means that the upper fiber layer is A and the lower absorbing layer is 80-0.5, and so on.

[0045] Tensile testing showed that the tensile strength of the composite absorbing material prepared in this embodiment increased from 2 MPa for a single absorbing sheet to 20 MPa, representing a tenfold increase in mechanical tensile strength. The tensile strength of the composite absorbing sheets with different magnetic fiber spacings remained almost unchanged at 20 MPa, because the tensile strength of both magnetic fibers and glass fibers is approximately 1000 MPa. Reflectivity testing revealed that the composite absorbing material prepared by stacking different fiber layers with absorbing layers of varying thicknesses exhibited the following absorption performance: Figure 1 , 2 As shown in Tables 2, 3, and 4, compared to absorbers without fiber layers, absorbers with composite fiber layers exhibit improved absorption intensity and absorption bandwidth.

[0046] Table 2. Wave absorption performance of composite materials with different fiber layers and 0.5mm absorbing sheets

[0047]

[0048] Table 3. Absorption performance of composite materials with different fiber layers and 2.5mm absorbing sheets

[0049]

[0050]

[0051] Table 4. Absorption Performance of Composites with Different Fiber Layers and 5mm Absorbers

[0052]

[0053] Examples 9-14 and Comparative Examples 7-9

[0054] In this embodiment, a fiber layer is placed in the middle interlayer of the absorbing sheet to prepare a composite absorbing sheet.

[0055] Magnetic fibers with a diameter of 50 micrometers were prepared by melt drawing method. The magnetic core diameter was 30 micrometers. The magnetic core material was CoFeSiBCrMo. The thickness of the glass-coated outer layer was 10 micrometers. The magnetic fibers were mixed with glass fibers at intervals of 5 to 30 millimeters and woven in a twill pattern to form a fiber braided layer. The specific spacing is shown in Table 1.

[0056] Meanwhile, carbonyl iron (70% by mass) and silica gel (30% by mass) were thoroughly mixed and then passed through a casting film machine to prepare microwave absorbing sheets with thicknesses of 0.5 mm and 1 mm, respectively.

[0057] The above-mentioned fiber braided layer and the absorbing sheet are compositely superimposed, with the fiber layer in the middle layer and the absorbing sheet placed in the upper and lower layers, and bonded with silicone to obtain a composite absorbing material. The sample name 70-1.5 (0.5-A-1) means that the upper layer is a 0.5 mm absorbing layer, the middle layer is an A fiber layer, and the lower layer is a 1 mm absorbing layer, and so on.

[0058] Tensile testing showed that the tensile strength of the composite absorbing material prepared in this embodiment increased from 2 MPa for a single absorbing sheet to 20 MPa, representing a tenfold increase in mechanical tensile strength. The tensile strength of the composite absorbing sheets with different magnetic fiber spacings remained at 20 MPa, because the tensile strength of both magnetic fibers and glass fibers is approximately 1000 MPa. Reflectivity testing revealed the absorbing performance of the composite absorbing materials prepared by superimposing different fiber layers at different locations within the absorbing layer. Figure 4 As shown in Table 5, compared to the absorber without a fiber layer, the absorber with a composite fiber layer has improved absorption intensity and absorption bandwidth.

[0059] Table 5. Composite absorption performance of different fiber layers with a total thickness of 1.5 mm for upper and lower absorbing sheets.

[0060]

[0061]

[0062] Examples 15-17 and Comparative Examples 10-12

[0063] In this embodiment, a fiber layer is placed at the bottom of the absorbing sheet to prepare a composite absorbing sheet.

[0064] Magnetic fibers with a diameter of 100 micrometers were prepared by hydrospinning. These fibers had no glass outer coating and were made of CoFeSiBCr. The magnetic fibers were then mixed with glass fibers at 1 mm intervals and woven in a plain weave to form a fiber braid layer, named the E-fiber layer.

[0065] Meanwhile, carbonyl iron (85% by mass) and silica gel (15% by mass) were thoroughly mixed and then passed through a casting film machine to prepare microwave absorbing sheets with thicknesses of 0.8, 0.9, and 1.1 mm.

[0066] The above-mentioned fiber braided layer and the absorbing sheet are compositely superimposed, with the fiber layer at the bottom and the absorbing sheet at the top, and bonded with silicone to obtain a composite absorbing material. The sample name 85-0.8+E represents the upper 0.8 mm absorbing layer and the lower E fiber layer, and so on.

[0067] Tensile testing showed that the tensile strength increased from 2 MPa for a single absorbing sheet to 20 MPa for the fiber composite absorbing sheet, representing a tenfold increase in mechanical tensile strength. Reflectivity testing revealed the absorbing performance of composite absorbing materials prepared by superimposing different fiber layers and absorbing layers at different locations within the composite layer. Figure 5 As shown in Table 6, compared to the absorber without a fiber layer, the absorber with a composite fiber layer shows a significant increase in absorption intensity, and the peak position of the absorption frequency band shifts to the lower frequency band.

[0068] Table 6. Absorption Performance of E-fiber Layer Composite with Absorbers of Different Thicknesses

[0069]

[0070]

[0071] Furthermore, it should be noted that the specific embodiments described in this specification may differ in the shape and name of their components, etc. The above description is merely illustrative of the structure of the present invention. All equivalent or simple variations made based on the structure, features, and principles described in this patent concept are included within the protection scope of this patent. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, all of which should fall within the protection scope of this invention.

Claims

1. A fiber-reinforced multilayer composite microwave absorbing material, characterized in that, The absorbing material consists of a fiber layer and an absorbing layer, wherein the fiber layer is located at the top of the absorbing layer, at the bottom of the absorbing layer, or between two absorbing layers. The fiber layer is obtained by stacking a single layer of woven fabric or multiple single layers of woven fabric. The single layer of woven fabric is obtained by weaving a mixture of magnetic fibers and glass fibers, and the spacing between each magnetic fiber is 1-100mm. The absorbing layer is composed of an electromagnetic wave composite matrix and an electromagnetic wave absorber. The magnetic fiber consists of a magnetic core and a glass outer layer that wraps the magnetic core, or it consists of a magnetic core. The magnetic core is made of cobalt-based amorphous alloy fiber, cobalt-nickel alloy fiber, or iron-nickel alloy fiber.

2. The fiber composite multilayer structure reinforced microwave absorbing material according to claim 1, characterized in that, The material of the magnetic core is CoFeSiBCrMo or CoFeSiBCr.

3. The fiber composite multilayer structure reinforced microwave absorbing material according to claim 1, characterized in that, The diameter of the magnetic core is 5-95 μm, and the thickness of the glass outer layer is 2.5-25 μm.

4. The fiber composite multilayer structure reinforced microwave absorbing material according to claim 1, characterized in that, The magnetic fibers and glass fibers of the single-layer woven fabric are woven in at least one of plain weave, twill weave, and satin weave.

5. The fiber composite multilayer structure reinforced microwave absorbing material according to claim 1, characterized in that, The electromagnetic wave composite matrix is ​​epoxy resin, phenolic resin, polyurethane, polypropylene, polyetheretherketone, or silicone. The electromagnetic wave absorber is one or more of the following: carbonyl iron, iron-silicon-aluminum, iron-nickel, amorphous alloy, graphene, carbon black, and MXene.

6. The fiber composite multilayer structure reinforced microwave absorbing material according to claim 1, characterized in that, The fiber layer is located on top of the microwave absorbing layer. The magnetic fiber consists of a magnetic inner core and a glass outer layer that wraps the magnetic inner core. The spacing between each magnetic fiber is 10-30 mm. The thickness of the absorbing layer is 0.5-5mm, and the electromagnetic wave absorber is carbonyl iron, with the carbonyl iron accounting for 10%-95% of the mass of the absorbing layer.

7. The fiber composite multilayer structure reinforced microwave absorbing material according to claim 1, characterized in that, The fiber layer is located at the bottom of the absorbing layer, and the magnetic fiber is composed of a magnetic core. The spacing between the magnetic fibers in the fiber layer is 1-100 mm. The thickness of the absorbing layer is 0.8-1.1 mm, and the electromagnetic wave absorber is carbonyl iron, with the carbonyl iron accounting for 10%-95% of the mass of the absorbing layer.

8. A method for preparing a fiber-reinforced multilayer structure microwave absorbing material according to claim 6, characterized in that, include: Magnetic cores are prepared by melt drawing, hydrospinning or spinning. Glass is wrapped around the outer surface of the magnetic core to obtain magnetic fibers. The magnetic fibers are mixed with glass fibers at a set interval and woven into a single layer. The single layer or multiple single layers are stacked to obtain a fiber layer. An electromagnetic wave composite matrix and an electromagnetic wave absorber are stirred and mixed, and then a wave-absorbing layer is obtained by calendering. The fiber layer is attached to the top or bottom of the absorbing layer or between two absorbing layers to obtain the absorbing material.

Images