A multi-layer lightweight composite structural material capable of achieving electromagnetic shielding in a wide frequency range

Abstract

The application belongs to the field of electromagnetic shielding materials, and particularly relates to a multi-layer lightweight composite structural material capable of realizing electromagnetic shielding in a wide frequency range. The material is formed by alternately stacking FeCrAl / Cu / FeCrAl sandwich structures constructed by FeCrAl ultra-thin strips and purple Cu nets as component materials and carbon fiber prepregs. The high magnetism of the FeCrAl ultra-thin strips can effectively shield low-frequency magnetic field interference below 100 kHz, and the high conductivity of the purple Cu net ensures the shielding effect of high-frequency magnetic field interference, so that the material can realize shielding in a wide frequency range, greatly improve the shielding effectiveness of the overall material, and be suitable for various scenes. Meanwhile, the extremely small thickness size of the FeCrAl ultra-thin strips and the net structure of the purple copper can effectively reduce the weight of the structure, and meet the development requirements of lightweight, wide frequency range shielding and high shielding effectiveness of electromagnetic shielding materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electromagnetic shielding materials, and particularly relates to a multi-layer lightweight composite structure material capable of realizing electromagnetic shielding in a wide frequency range. BACKGROUND

[0002] With the rapid development of electronic information technology, the emergence of various electronic products and equipment, the harm caused by electromagnetic wave radiation is becoming more and more serious. On the one hand, electromagnetic radiation seriously threatens human health, for example, electromagnetic radiation generated by high-voltage lines can greatly increase the incidence of childhood leukemia and also cause other diseases; on the other hand, the mutual influence of different frequency bands between different electronic devices can also cause the devices to malfunction, resulting in huge economic losses. In particular, in the field of national defense and security, information exchange in combat command requires a large number of high-precision electronic instruments and equipment to transmit electromagnetic signals for communication, which is easy to be interfered by the enemy using external electromagnetic waves, causing serious security incidents. Therefore, the development of electromagnetic shielding technology is of great significance in both civilian and military fields. In view of the problems existing in the above fields, the most widely used technology at present is to use electromagnetic shielding materials to ensure the safety of electronic equipment.

[0003] At present, there are several major categories of electromagnetic shielding materials, mainly including metal-based electromagnetic shielding materials, composite electromagnetic shielding materials, and coating-type electromagnetic shielding materials. Among them, metal-based electromagnetic shielding materials are the most common, and common ones include high magnetic permeability metal materials such as iron, nickel, and high electrical conductivity materials such as copper and silver, but most high magnetic permeability materials are difficult to achieve effective shielding of high-frequency electromagnetic waves. In order to solve this problem, the conventional method is to use chemical deposition, electroplating and other processes to combine iron, cobalt, nickel with copper, silver, gold, so that the synthesized material has high electrical conductivity and magnetic permeability, and the shielding range can reach 100 kHz-18 GHz. However, pure metal shielding materials are not conducive to weight reduction due to their high density, so lightweight conductive particle materials such as graphite, carbon nanotubes, and graphene are used to be compounded with carbon fiber materials and high polymer materials to prepare composite materials with electromagnetic shielding function. However, the shielding effect of this type of material is easily affected by the process, and the filling particles used are prone to uneven distribution and clumping, resulting in a decrease in the shielding efficiency of the material. Coating-type electromagnetic shielding materials are thin conductive layers formed on the surface of the structure by spraying conductive coating, which can improve the shielding efficiency of electromagnetic waves, and has the advantages of simple process and low cost, but this technology has the disadvantages of surface coating gradually falling off over time, difficult to repair, and short service life. In addition, a series of new intrinsic conductive polymers and metal oxides developed in recent years have excellent shielding performance, but are difficult to be widely applied due to complex preparation process and high cost. SUMMARY

[0004] Based on the development trend of light weight, wide frequency range shielding and high shielding efficiency of electromagnetic shielding materials, the present application proposes a kind of electromagnetic shielding material with multi-layer composite structure capable of realizing electromagnetic shielding function in wide frequency range by using the high magnetism of FeCrAl ultra-thin strip, the high conductivity of purple Cu net and the light weight and high strength characteristics of carbon fiber composite material.

[0005] To achieve the above object, the present application is realized by the following technical solutions:

[0006] A preparation method of a multi-layer light weight composite structure material capable of realizing wide frequency range electromagnetic shielding, comprising the following steps:

[0007] Step 1: according to the material size design requirements, cut several pieces of FeCrAl ultra-thin strip and purple Cu net;

[0008] Step 2: roughen the cut FeCrAl ultra-thin strip and purple Cu net to increase the surface roughness, and then clean the surface with alcohol or acetone to ensure that the surface of the two types of metal component materials is clean and oil-free;

[0009] Step 3: immerse the FeCrAl ultra-thin strip in NaOH solution, and dry after taking out;

[0010] Step 4: after smearing high-temperature solidified conductive adhesive on one side of the FeCrAl ultra-thin strip, stack the FeCrAl ultra-thin strip and the purple Cu net in the order of FeCrAl / Cu / FeCrAl;

[0011] Step 5: roll the prepared FeCrAl / Cu / FeCrAl sandwich structure, and after each rolling, reverse the FeCrAl / Cu / FeCrAl sandwich structure and roll again, and repeat the rolling until the surface is completely flat;

[0012] Step 6: smear silane coupling agent on one side of the outer surface of the FeCrAl / Cu / FeCrAl sandwich structure after rolling, and alternately stack the carbon fiber prepreg according to the specific structure design scheme; wherein the FeCrAl / Cu / FeCrAl sandwich structure can be regarded as a single unit, and the unit can be appropriately increased or decreased in the carbon fiber prepreg layer according to the specific requirements of shielding efficiency, and a plurality of sandwich structure units are uniformly distributed at a certain distance along the thickness direction;

[0013] Step 7: solidify the stacked material to complete the preparation.

[0014] Further, the thickness of the FeCrAl ultra-thin strip in step 1 is 50-100 μm.

[0015] Further, the mesh number of the purple Cu net in step 1 is 200 meshes.

[0016] Further, the cutting number of the FeCrAl ultra-thin strip in step 1 is 2 times of the purple Cu net.

[0017] Further, the soaking time in step 3 is 6-8 hours.

[0018] Further, the concentration of the NaOH solution in step 3 is 5%.

[0019] Further, the high-temperature curing conductive adhesive in step 4 is 6529 epoxy resin conductive adhesive.

[0020] Further, the roll gap before rolling in step 5 is less than 5%-10% of the thickness of the prepared FeCrAl / Cu / FeCrAl sandwich structure.

[0021] Further, the silane coupling agent in step 6 is KH-550.

[0022] Further, the specific process of solidification and molding in step 6 is as follows: the entire material after completing the stacking is placed in a vacuum bag, and a hole isolation film, a glue absorption felt or a glue absorption cloth is laid, and after the vacuum bag is sealed with a sealing strip, it is transferred into a hot press tank for solidification and molding.

[0023] Compared with the prior art, the beneficial effects of the present application are as follows:

[0024] 1) The forming process is simple and efficient, and can be mass-produced with low manufacturing cost and high economic benefit; 2) The high magnetism of the FeCrAl ultra-thin strip can effectively shield low-frequency magnetic field interference below 100 kHz, and the high electrical conductivity of the purple copper net ensures the shielding effect of high-frequency magnetic field interference, which can realize shielding in a wide frequency range, greatly improving the shielding efficiency of the overall material, and is suitable for various scenes; 3) The small thickness size of the FeCrAl ultra-thin strip and the net structure of the purple copper can effectively reduce the weight of the structure, and the flexibility of the metal component material can be used to prepare various complex curved surface structures; 4) Compared with pure fiber composite materials, the addition of metal materials improves the toughness of the overall material, making the material processing and cutting easier. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the schematic diagram of the FeCrAl / Cu / FeCrAl sandwich structure in Example 1 of the present application.

[0026] Figure 2 is the schematic diagram of the overall structure of the finally formed multi-layer composite structure electromagnetic shielding material in Example 1 of the present application.

[0027] In the figure, 1-FeCrAl ultra-thin strip; 2-purple Cu net; 3-FeCrAl ultra-thin strip; 4-0° direction carbon fiber prepreg; 5-90° direction carbon fiber prepreg; 6-FeCrAl / Cu / FeCrAl sandwich structure unit. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present application, the present application will be described more fully below. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0029] Example 1

[0030] Step one, cut 4 pieces of FeCrAl ultra-thin strip with a thickness of 50 microns, cut 2 pieces of purple Cu net with a thickness of 100 microns, 200 mesh, and the planar size is 500mm*500mm. After cleaning the surface of the material with acetone solution, dry naturally.

[0031] Step two, use laser texturing equipment to texturize the surface of FeCrAl ultra-thin strip and purple Cu net, after finishing, use acetone solution to clean FeCrAl ultra-thin strip and purple Cu net, remove oil stains and impurities on the surface of the material.

[0032] Step three, place the FeCrAl ultra-thin strip in a 5% concentration NaOH solution for 6-8 hours, then take it out and dry naturally.

[0033] Step four, after applying 6529 epoxy resin conductive adhesive on one side of the FeCrAl, place it on the purple Cu net according to the stacking structure sequence shown in the accompanying Figure 1

[0034] Step five, adjust the roll gap of the rolling mill to 180 microns, place the FeCrAl / Cu / FeCrAl sandwich structure unit between the rolls for rolling, after rolling once, reverse and roll again.

[0035] Step six, cut 11 pieces of T700 carbon fiber unidirectional prepreg with the same planar size, spray silane coupling agent KH-550 on the outer surface of the FeCrAl ultra-thin strip in the FeCrAl / Cu / FeCrAl sandwich structure unit after rolling, according to the stacking structure sequence shown in the accompanying Figure 2

[0036] ​​Step seven, after the carbon fiber prepreg and stainless steel short microfilament FeCrAl / Cu / FeCrAl sandwich structure are laid, a vacuum bag is used for wrapping, and a hole isolation film, a glue absorption felt, a glue absorption cloth and the like are laid, and after the vacuum bag is sealed by using a sealing rubber strip, the vacuum bag is transferred into a hot pressing tank for curing and forming, and the preparation is completed.

[0037] The above merely describes the embodiments of the present application for better explaining the present application, and is not intended to limit the present application. Any modification or equivalent replacement without departing from the spirit and scope of the present application shall fall within the scope of the present application.

Claims

1. A method for preparing a multi-layered lightweight composite structural material that can achieve electromagnetic shielding in a wide frequency range, characterized by: The method comprises the following steps: Step 1: cutting a plurality of FeCrAl ultra-thin strips and purple Cu nets according to the size design requirements of the materials; Step 2: performing roughening treatment on the cut FeCrAl ultra-thin strips and purple Cu nets, and then cleaning the surfaces with alcohol or acetone; Step 3: soaking the FeCrAl ultra-thin strips in a NaOH solution, and then taking out and air-drying after the soaking is completed; Step 4: after applying high-temperature curing conductive adhesive to one side of the FeCrAl ultra-thin strips, stacking the FeCrAl ultra-thin strips and the purple Cu nets in the order of FeCrAl / Cu / FeCrAl; Step 5: roll pressing the prepared FeCrAl / Cu / FeCrAl sandwich structure, and after each roll pressing, reversing the FeCrAl / Cu / FeCrAl sandwich structure and then roll pressing again, and repeating the roll pressing until the surface is completely flat; Step 6: applying silane coupling agent to one side of the outer surface of the FeCrAl ultra-thin strips in the FeCrAl / Cu / FeCrAl sandwich structure after the roll pressing is completed, and then alternately stacking the carbon fiber prepreg according to the specific structure design scheme; Step 7: curing and forming the stacked material to complete the preparation; The thickness of the FeCrAl ultra-thin strips in step 1 is 50-100 μm.

2. The method for preparing a multilayer lightweight composite material capable of achieving wide-band electromagnetic shielding according to claim 1, characterized in that: The mesh number of the purple Cu net in step 1 is 200.

3. The method of claim 1, wherein the method further comprises: The number of FeCrAl ultra-thin strips cut in step 1 is twice the number of purple Cu nets.

4. The method of claim 1, wherein the method further comprises: The soaking time in step 3 is 6-8 hours.

5. The method of claim 1, wherein the method further comprises: The concentration of the NaOH solution in step 3 is 5%.

6. The method of claim 1, wherein the method further comprises: The high-temperature curing conductive adhesive in step 4 is 6529 epoxy resin conductive adhesive.

7. The method of claim 1, wherein the method further comprises: Before roll pressing in step 5, the gap between the rollers is set to be less than 5%-10% of the thickness of the prepared FeCrAl / Cu / FeCrAl sandwich structure. ​ 8. The method of claim 1, wherein the method further comprises: The silane coupling agent in step 6 is KH-550. ​ 9. The method of claim 1, wherein the method further comprises: The specific process of curing and forming in step 7 is as follows: placing the stacked material in a vacuum bag, laying a hole isolation film, a glue absorption felt or a glue absorption cloth, sealing the vacuum bag with a sealing glue strip, and then transferring the vacuum bag into a hot press tank for curing and forming. ​

Images