Preparation method of fiber-reinforced radar wave-absorbing gradient composite material

Abstract

The invention discloses a preparation method of a fiber-reinforced radar wave-absorbing gradient composite material, and the specific process is as follows: dielectric material solution preparation: uniformly dispersing a dielectric material in a plurality of groups of independently subpackaged dissolving solutions, and regulating and controlling the concentration of the dielectric material in the dissolving solutions to obtain a plurality of groups of dielectric material solutions of which the concentration changes in a gradient manner; dielectric solution absorption: soaking a plurality of groups of high-water-absorptivity fibers in a plurality of groups of prepared dielectric material solutions respectively, and absorbing the solution by utilizing the high water absorptivity of the high-water-absorptivity fibers; drying the super absorbent fibers: drying the super absorbent fibers fully absorbing the dielectric solution, and removing the dielectric material on the surfaces of the dried super absorbent fibers, so that the dielectric material is only dispersed in the super absorbent fibers; and preparing a composite material plate: taking the prepared super absorbent fibers with different dielectric material concentrations as fiber reinforced phases, and paving according to a certain sequence to prepare the gradient fiber reinforced radar wave-absorbing composite material plate.

Description

Technical Field

[0001] This invention relates to the field of radar absorbing materials technology, and specifically to a method for preparing a fiber-reinforced radar absorbing gradient composite material. Background Technology

[0002] Radar absorbing materials are a class of special materials that can absorb electromagnetic energy, especially radar signals. Their core function is to convert electromagnetic energy into heat energy or other forms of energy through the electromagnetic loss mechanism inside the material, thereby reducing the reflection of radar waves.

[0003] Currently, radar absorbing materials are mainly ferrite and carbonyl iron powder composite absorbing coatings. Although these materials can absorb electromagnetic energy through dielectric loss or magnetic loss, they have significant drawbacks: high density leads to increased equipment weight; coatings have poor adhesion and weak weather resistance, making them prone to peeling after long-term use; and they can only achieve effective absorption in narrow frequency bands (such as 2-18GHz), making them unsuitable for the broadband requirements of complex electromagnetic environments. Furthermore, aerospace and other fields have stringent requirements for the structural load-bearing capacity of materials, and simple absorbing materials cannot be directly used as structural components due to insufficient mechanical properties.

[0004] Against this backdrop, structurally and functionally integrated radar-absorbing fiber-reinforced composite materials have emerged. These materials use high-performance fibers (such as carbon fiber, glass fiber, and aramid fiber) as the reinforcing phase and a resin matrix (such as epoxy resin and phenolic resin) as the continuous phase. By introducing absorbing agents (such as graphene, carbon nanotubes, and magnetic particles) into the resin or designing fiber weaving structures (such as multi-directional weaving and honeycomb sandwich structures), the mechanical load-bearing and radar-absorbing functions are integrated.

[0005] Early methods were based on carbon fiber reinforced resin matrix composites (CFRP), utilizing the dielectric properties of carbon fiber itself to achieve preliminary wave absorption, but the absorption frequency band was relatively narrow; in the middle stage, magnetic nanoparticles were doped into the matrix to expand the magnetic loss mechanism and improve broadband wave absorption performance.

[0006] However, the existing technology system still faces bottlenecks: (1) Impedance matching characteristics are difficult to control, and the mismatch between the surface impedance of the material and the free space impedance will significantly enhance electromagnetic reflection. (2) The interfacial compatibility between the fiber matrix and the functional filler and the uniformity of the dielectric material distribution are still difficult to control precisely, resulting in insufficient impedance matching stability in the broadband. (3) There are technical limitations in adjusting the material gradient structure. Gradient design is an effective means to broaden the absorption frequency band. The traditional stacking method requires multiple impregnations with different dielectric material parameters, which is not only complicated (requiring strict control of temperature, humidity and slurry ratio), but also has low loading rate, low control accuracy, and low yield. Furthermore, the method of doping particles in the matrix cannot prepare a high-precision gradient distribution. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for preparing fiber-reinforced radar absorbing gradient composite materials. This method, through gradient design, enables the fiber-reinforced radar absorbing composite materials to simultaneously possess variable impedance matching and internal absorption. Furthermore, the dielectric properties of each fiber phase are precisely controllable, and the prepared gradient fiber-reinforced radar absorbing composite materials can meet the electromagnetic environment requirements of different application scenarios.

[0008] A method for preparing fiber-reinforced radar absorbing gradient composite material, the specific process of which is as follows: Step 1, preparation of dielectric material solution: The dielectric material is uniformly dispersed in multiple independently packaged solutions. By adjusting the concentration of the dielectric material in the solutions, multiple dielectric material solutions with gradient concentrations are obtained. Step 2, dielectric solution absorption: Immerse multiple groups of highly absorbent fibers in the multiple dielectric material solutions prepared in Step 1, and use the high water absorption of the fibers to absorb the solution. Step 3, Drying the superabsorbent fiber: Dry the superabsorbent fiber that has fully absorbed the dielectric solution in Step 2, and remove the dielectric material from the surface of the dried superabsorbent fiber so that the dielectric material is only dispersed inside the superabsorbent fiber. Step 4, preparation of composite material plate: The highly absorbent fibers with different dielectric material concentrations prepared in Step 3 are used as fiber reinforcement phases and laid in a certain order to prepare a gradient fiber reinforced radar absorbing composite material plate.

[0009] As a preferred embodiment of the above technical solution, in step one, the dielectric material is one or more of ferrite absorbing materials, carbon-based absorbing materials, and ceramic absorbing materials.

[0010] As a preferred embodiment of the above technical solution, in step one, the dissolving solution is one or more of the following: dimethylformamide, deionized water, dimethyl sulfoxide, toluene, ethyl acetate, xylene, tetrahydrofuran, ethanol, and isopropanol.

[0011] As a preferred embodiment of the above technical solution, in step one, the concentration of the dielectric material solution prepared is 0.1-30 mg / mL.

[0012] As a preferred embodiment of the above technical solution, in step two, the highly absorbent fiber can be any one of fiber fabric, fiber bundle, or fiber felt.

[0013] As a preferred embodiment of the above technical solution, in step three, the dielectric material on the surface of the highly absorbent fiber can be removed by mechanical vibration or tapping.

[0014] As a preferred embodiment of the above technical solution, in step four, the thickness of the prepared composite material plate is 0-50 mm.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The process is simple. By utilizing the high water absorption of superabsorbent fibers, the solution containing dielectric materials can be directly absorbed. Then, by drying, fiber phases loaded with dielectric materials of different concentrations can be obtained for subsequent preparation of gradient composite materials. 2. Through high-precision gradient design, the composite material achieves both surface impedance matching and internal wave absorption. 3. Highly absorbent fibers are lightweight, resulting in composite boards with low density and light weight, making them suitable for lightweight electronic devices and military equipment. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the preparation process of the present invention.

[0017] Figure 2 This is a reflection loss diagram of the composite material prepared by this method. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The present invention will now be described in further detail with reference to the accompanying drawings: like Figure 1 The method for preparing a fiber-reinforced radar absorbing gradient composite material is shown below, and the specific process is as follows: Step 1, preparation of dielectric material solution: The dielectric material is uniformly dispersed in multiple independently packaged solutions. By adjusting the concentration of the dielectric material in the solutions, multiple dielectric material solutions with gradient concentrations are obtained. Step 2, dielectric solution absorption: Immerse multiple groups of highly absorbent fibers in the multiple dielectric material solutions prepared in Step 1, and use the high water absorption of the fibers to absorb the solution. Step 3, Drying the superabsorbent fiber: Dry the superabsorbent fiber that has fully absorbed the dielectric solution in Step 2, and remove the dielectric material from the surface of the dried superabsorbent fiber so that the dielectric material is only dispersed inside the superabsorbent fiber. Step 4, preparation of composite material plate: The highly absorbent fibers with different dielectric material concentrations prepared in Step 3 are used as fiber reinforcement phases and laid in a certain order to prepare a gradient fiber reinforced radar absorbing composite material plate.

[0020] In this embodiment, in step one, the dielectric material is one or more of ferrite absorbing materials, carbon-based absorbing materials, and ceramic absorbing materials.

[0021] In this embodiment, in step one, the dissolving solution is one or more of dimethylformamide, deionized water, dimethyl sulfoxide, toluene, ethyl acetate, xylene, tetrahydrofuran, ethanol, and isopropanol.

[0022] In this embodiment, in step one, the concentration of the dielectric material solution prepared is 0.1-30 mg / mL.

[0023] In this embodiment, in step two, the highly absorbent fiber can be any one of fiber fabric, fiber bundle, or fiber felt.

[0024] In this embodiment, in step three, the dielectric material on the surface of the superabsorbent fiber can be removed by mechanical vibration or beating.

[0025] In this embodiment, in step four, the thickness of the prepared composite material plate is 0-50 mm.

[0026] The specific implementation method is as follows: Example 1

[0027] (1) Take 500 mL of dimethylformamide and add it to a 1000 mL beaker. Weigh 1 g of graphene oxide and slowly add it to the solvent. Use an ultrasonic cleaner to ultrasonically disperse it for 30 min. Then transfer it to a magnetic stirrer and stir continuously for 1 h to obtain a graphene oxide solution with a concentration of 2 mg / mL. (2) Cut the silk fabric into 100mm×100mm samples, immerse them completely in the above graphene oxide solution, and let them stand at room temperature (25℃) for 24 hours. During this period, use an ultrasonic cleaner to ultrasonically disperse for 30 minutes every 2 hours. (3) Take out a portion of the fabric, use filter paper to absorb the excess solution on the surface, and put it into a vacuum drying oven at 50°C for 12 hours to obtain 5 sheets of silk fabric initially loaded with graphene oxide. (4) Select the remaining fabrics and repeat the above "soak-dry" operation once, then select a portion of the fabrics and repeat the above "soak-dry" operation once, and so on for subsequent operations. Finally, place all fabrics on a low-frequency vibration table and vibrate for 30 minutes to remove unbonded graphene oxide from the surface; (5) Weigh the epoxy resin matrix according to the mass ratio of silk fabric to epoxy resin matrix (epoxy resin E-51 and polyamide 650 curing agent, with a mass ratio of 10:3) as 4:6. Lay out the graphene-loaded silk fabric with the following thicknesses: 0.58 mm for the first layer, 1.6 mm for the second layer, 1.4 mm for the third layer, 0.74 mm for the fourth layer, and 1.6 mm for the fifth layer. Pour in the prepared epoxy resin matrix and hot-press to form a composite material. After curing, obtain the gradient fiber reinforced radar absorbing composite material loaded with graphene oxide. Its reflection loss is as follows: Figure 2 As shown. Example 2

[0028] (1) Take 500mL of deionized water and add it to a 1000mL beaker. Weigh 10g, 9g, 8g, 7g, 6g, 5g, 4g, 3g, 2g and 1g of Fe3O4 particles in sequence and slowly add them to the solvent. Use an ultrasonic cleaner to ultrasonically disperse the Fe3O4 particles for 30min. Then transfer the Fe3O4 particles to a magnetic stirrer and stir continuously for 1h to obtain a series of Fe3O4 solutions of corresponding concentrations. (2) Cut the flax fabric into 10 samples of 100mm×100mm, immerse them completely in the above Fe3O4 solution, let them stand at room temperature (25℃) for 24h, and use an ultrasonic cleaner to ultrasonically disperse them for 30min every 2 hours during this period. (3) Take out all the fabrics, use filter paper to remove excess solution from the surface, and put them into a vacuum drying oven at 50°C for 12 hours to obtain flax fabric loaded with Fe3O4. (4) Place the fabric on a low-frequency vibration table and vibrate for 30 minutes to remove unbonded Fe3O4 from the surface.

[0029] (5) Weigh the epoxy resin matrix according to the mass ratio of flax fabric to epoxy resin matrix (epoxy resin E-51, polyamide 650 curing agent, mass ratio 10:3) of 4:6. Lay the Fe3O4-loaded flax fabric in descending order of the concentration of the soaking solution into the mold, pour in the prepared epoxy resin matrix, and hot-press to complete curing, thus obtaining a gradient fiber-reinforced radar absorbing composite material loaded with graphene oxide. Its reflection loss is as follows: Figure 2 As shown. Example 3

[0030] (1) Take 500 mL of ethanol and add it to a 1000 mL beaker. Weigh 5 g of carbon nanotubes, 5 g of SiC particles and 5 g of nano iron particles and slowly add them to the solvent. Use an ultrasonic cleaner to ultrasonically disperse them for 30 min. Then transfer them to a magnetic stirrer and stir continuously for 1 h to obtain a carbon nanotube, SiC and nano iron solution with a concentration of 10 mg / mL. (2) Cut the sisal fiber felt into three 100mm×100mm samples, immerse them completely in the above three solutions, and let them stand at room temperature (25℃) for 24 hours. During this period, use an ultrasonic cleaner to ultrasonically disperse them for 30 minutes every 2 hours. (3) Take out the fiber felt, use filter paper to remove excess solution from the surface, and put it into a vacuum drying oven at 50°C for 12 hours to obtain sisal fiber felt loaded with carbon nanotubes, SiC and nano iron. (4) Place the fabric on a low-frequency vibration table and vibrate for 30 minutes to remove unbonded carbon nanotubes, SiC and nano iron on the surface; (5) Weigh the epoxy resin matrix according to the mass ratio of sisal fiber felt to epoxy resin matrix (epoxy resin E-51, polyamide 650 curing agent, mass ratio 10:3) of 2:8. Lay the sisal fiber felt loaded with carbon nanotubes, SiC, and nano-iron sequentially in a mold, pour in the prepared epoxy resin matrix, and hot-press to form a composite material. After curing, obtain a gradient fiber-reinforced radar absorbing composite material loaded with multiple dielectric materials. Its reflection loss is as follows: Figure 2 As shown.

[0031] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a fiber-reinforced radar absorbing gradient composite material, characterized in that: The specific process is as follows: Step 1, preparation of dielectric material solution: The dielectric material is uniformly dispersed in multiple independently packaged solutions. By adjusting the concentration of the dielectric material in the solutions, multiple dielectric material solutions with gradient concentrations are obtained. Step 2, dielectric solution absorption: Immerse multiple groups of highly absorbent fibers in the multiple dielectric material solutions prepared in Step 1, and use the high water absorption of the fibers to absorb the solution. Step 3, Drying the superabsorbent fiber: Dry the superabsorbent fiber that has fully absorbed the dielectric solution in Step 2, and remove the dielectric material from the surface of the dried superabsorbent fiber so that the dielectric material is only dispersed inside the superabsorbent fiber. Step 4, preparation of composite material plate: The highly absorbent fibers with different dielectric material concentrations prepared in Step 3 are used as fiber reinforcement phases and laid in a certain order to prepare a gradient fiber reinforced radar absorbing composite material plate.

2. The method for preparing a fiber-reinforced radar absorbing gradient composite material according to claim 1, characterized in that: In step one, the dielectric material is one or more of ferrite absorbing materials, carbon-based absorbing materials, and ceramic absorbing materials.

3. The method for preparing a fiber-reinforced radar absorbing gradient composite material according to claim 1, characterized in that: In step one, the dissolving solution is one or more of the following: dimethylformamide, deionized water, dimethyl sulfoxide, toluene, ethyl acetate, xylene, tetrahydrofuran, ethanol, and isopropanol.

4. The method for preparing a fiber-reinforced radar absorbing gradient composite material according to claim 1, characterized in that: In step one, the concentration of the dielectric material solution prepared is 0.1-30 mg / mL.

5. The method for preparing a fiber-reinforced radar absorbing gradient composite material according to claim 1, characterized in that: In step two, the highly absorbent fiber can be any one of fiber fabric, fiber bundle, or fiber felt.

6. The method for preparing a fiber-reinforced radar absorbing gradient composite material according to claim 1, characterized in that: In step three, the dielectric material on the surface of the superabsorbent fiber can be removed by mechanical vibration or tapping.

7. The method for preparing a fiber-reinforced radar absorbing gradient composite material according to claim 1, characterized in that: In step four, the thickness of the prepared composite material plate is 0-50 mm.

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