Light broadband wave-absorbing structure based on 3D printing and resistive film and preparation method of light broadband wave-absorbing structure

Abstract

The invention provides a light broadband wave-absorbing structure based on 3D printing and a resistive film and a preparation method thereof.The light broadband wave-absorbing structure comprises a metal bottom layer, a supporting layer, a resistive film layer and a structural wave-absorbing material layer which are sequentially arranged from bottom to top, the structural wave-absorbing material layer is of a 3D printing structure and is made of CNTs doped with ABS, and the supporting layer is made of carbon nanotubes doped with ABS. Periodic units of the 3D printing structure are two kinds of regular hexagonal cylinder periodic units with different sizes. The CNTs-doped ABS 3D printing structure is introduced into the single-layer resistive film wave-absorbing structure, the 3D printing structure, the size and the resistance value of the resistive film are optimized, the wave-absorbing structure small in thickness and weight is obtained, meanwhile, the wave-absorbing structure has excellent wave-absorbing performance, and the reflection loss is smaller than-10 dB within 2.0 GHz to 18 GHz.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic absorbing materials, and in particular to a lightweight broadband absorbing structure based on 3D printing and a resistor film and a preparation method thereof. Background Art

[0002] Absorbing materials refer to a type of material that can absorb or significantly reduce the electromagnetic wave energy received on its surface, thereby reducing the interference of electromagnetic waves. With the development of modern science and technology, various detection technologies are constantly enhanced, and the requirements for broadband and electromagnetic wave absorbing materials are getting higher and higher. Microwave absorbing materials can effectively absorb and attenuate incident electromagnetic waves and are widely used in electromagnetic protection such as military stealth and electromagnetic shielding. With the continuous expansion of the application fields of absorbing materials, traditional absorbing materials such as absorbing coatings have the advantages of high process maturity and easy construction, but they also have disadvantages such as large mass and the absorbing bandwidth has frequency band targeting and cannot cover multiple bands.

[0003] Patent CN118673814A discloses an absorbing structure and a design method of the absorbing structure, wherein the absorbing structure is a structure integrally formed by an absorbing material, wherein the absorbing material is composed of carbon fiber and nylon; the absorbing structure obtained by integrally forming, and the overall absorbing material thereof is consistent, thereby enhancing the stability of the absorbing structure and improving the protection performance; the absorbing structure includes a plurality of cells arranged periodically to maintain the stability of the absorbing structure; the cells include at least one target polygonal tortoise shell unit, and the thickness of the target polygonal tortoise shell unit gradually decreases from the edges and corners of the edges to the grooves in the center; the electric field excited by the absorbing structure during the absorbing process forms a multi-layer equipotential surface inside the absorbing structure; the overall absorbing performance of the absorbing structure ensures that the effective absorbing bandwidth covers more than 85% in the frequency range of 2-40 GHz, but the effective absorption band generally does not cover the band mainly concentrated in the S band, and the absorbing structure cannot meet the absorbing performance requirements of the S band.

[0004] In view of this, the present invention provides a lightweight, broadband absorbing structure based on 3D printing and a resistor film and a preparation method thereof, and obtains an absorbing structure with light weight, thin thickness and wide absorbing bandwidth by optimizing materials and structural design. Summary of the invention

[0005] In order to solve the shortcomings of the prior art, the main purpose of the present invention is to provide a lightweight broadband absorbing structure based on 3D printing and resistor film and a preparation method thereof. The present invention introduces a CNTs-doped ABS 3D printing structure into a single-layer resistor film absorbing structure, and optimizes the 3D structure and size of the CNTs-doped ABS and the resistance value of the resistor film to obtain an absorbing structure with a smaller thickness and weight. At the same time, the absorbing structure has excellent absorbing performance, and the reflection loss is less than -10dB within 2.0GHz~18GHz.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A lightweight broadband absorbing structure based on 3D printing and resistive film, comprising a metal base layer, a support layer, a resistive film layer and a structural absorbing material layer arranged in sequence from bottom to top, wherein the structural absorbing material layer is a 3D printed structure made of CNTs-doped ABS material, and the 3D printed structure is a regular hexagonal column periodic unit of two different sizes.

[0007] Preferably, the regular hexagonal prism periodic unit is a first regular hexagonal prism with a side length of 4.00 mm, a first bottom regular hexagonal opening with a side length of 0.88 mm, a first top regular hexagonal side length of 3.77 mm, a second regular hexagonal prism with a side length of 4.00 mm, a second bottom regular hexagonal opening with a side length of 0.30 mm, and a second top regular hexagonal side length of 3.77 mm.

[0008] Preferably, the real part ɛ' and the imaginary part ɛ'' of the dielectric constant of the CNTs-doped ABS material satisfy: 5.5≤ɛ'≤11.4, 1.6≤ɛ''≤3.9.

[0009] Preferably, the resistor film layer material is a graphite screen-printed Pi film.

[0010] Preferably, the resistance value of the resistance film layer is 100-150 Ohm / sq.

[0011] Preferably, the support layer material is PMI foam, the relative dielectric constant ε' satisfies: 3.0≤ɛ'≤3.5, and the loss tangent tanδ satisfies: 0.002≤tanδ≤0.0025.

[0012] Preferably, the support layer has a thickness of 4.7-5.7 mm, and the 3D absorbing material has a thickness of 12-16 mm.

[0013] More preferably, the support layer has a thickness of 4.7 mm, and the 3D absorbing material has a thickness of 16 mm.

[0014] More preferably, the support layer has a thickness of 5.7 mm, and the 3D absorbing material has a thickness of 12 mm.

[0015] The present invention also provides a method for preparing the above-mentioned lightweight broadband absorbing structure based on 3D printing and resistor film, comprising the following steps: S1, obtaining a structural absorbing material layer and a resistive film layer; S2. Apply a release agent on the compression molding die, and sequentially lay a support foam, a wave-transmitting adhesive film, a resistor film layer, a wave-transmitting adhesive film, and a structural wave-absorbing material layer; S3, placing a metal plate on the top surface of the above-mentioned structure absorbing material layer to evenly distribute the molding pressure, setting the molding temperature, molding pressure and molding time for molding; S5. After the compression molding is completed, the compression molded flat plate blank is taken out, excess materials are removed, and the flat plate blank is cut to size to obtain the lightweight broadband absorbing structure flat plate sample based on 3D printing and resistive film.

[0016] The present invention provides a lightweight broadband absorbing structure based on 3D printing and a resistor film. The 3D structure of CNTs-doped ABS can provide more resonance cavities and excite more induced electromagnetic energy. The induced electromagnetic energy is lost by the CNTs-doped ABS and the resistor film. The 3D structure of CNTs-doped ABS enhances the absorbing strength of the absorbing structure. The CNTs-doped ABS and the resistor film cooperate to broaden the absorbing frequency band bandwidth of the absorbing structure.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The absorbing structure provided by the present invention introduces a 3D printed structure using CNTs-doped ABS as the printing material and two regular hexagonal prism structures of different sizes as periodic units into the single-layer resistive film absorbing structure, and utilizes the multi-frequency resonance characteristics of the 3D printed structure and the electromagnetic loss characteristics of the resistive film and CNTs-doped ABS to synergistically broaden the absorbing frequency bandwidth of the absorbing structure and enhance the absorbing intensity.

[0018] 2. The absorbing structure provided by the present invention is not only light in weight and thin in thickness, but also has excellent absorbing performance. Within 2.0GHz~18GHz, the reflection loss is less than -10dB (absorption rate is greater than 90%). BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings: Figure 1 is a schematic structural diagram of a lightweight broadband absorbing structure prepared in an embodiment of the present invention; Figure 2 is a top view of a lightweight broadband absorbing material prepared in an embodiment of the present invention; Figure 3 is a side view of a structural absorbing structure prepared according to an embodiment of the present invention; Figure 4 is a relative dielectric constant curve of the structural absorbing material in an embodiment of the present invention; Figure 5 is a reflectivity curve of a lightweight broadband absorbing structure under vertical incidence in Example 1 of the present invention; Figure 6 is a reflectivity curve of a lightweight broadband absorbing structure under vertical incidence in Example 2 of the present invention; Figure 7 is a schematic structural diagram of a lightweight broadband wave absorbing structure prepared in Comparative Example 1 of the present invention; Figure 8 is a top view of a lightweight broadband absorbing structure prepared in Comparative Example 1 of the present invention; Fig. 9 is a side view of a lightweight broadband absorbing structure prepared in Comparative Example 1 of the present invention; Fig.10 This is the reflectivity curve of the lightweight broadband absorbing structure under vertical incidence in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0020] In the following examples and comparative examples, carbon nanotubes are abbreviated as CNTs, and acrylonitrile-butadiene-styrene is abbreviated as ABS.

[0021] Figure 4 The relative dielectric constant curve of CNTs-doped ABS material of the lightweight broadband absorbing structure based on 3D printing and resistive film provided by the present invention. As can be seen from the figure, the real part ɛ' and the imaginary part ɛ'' of the relative dielectric constant of the CNTs-doped ABS material satisfy: 5.5≤ɛ'≤11.4, 1.6≤ɛ''≤3.9.

[0022] Embodiment 1: like Figure 1 As shown, this embodiment provides a lightweight broadband absorbing structure based on 3D printing and a resistive film, including a metal bottom layer, a support layer, a resistive film layer and a structural absorbing material layer arranged in sequence from bottom to top.

[0023] like Figure 2-3 As shown, the support layer material is PMI foam with a thickness of 5.7 mm, the relative dielectric constant ε' satisfies: 3.0≤ɛ'≤3.5, and the loss tangent tanδ satisfies: 0.002≤tanδ≤0.0025; the unit size of the resistor film layer is 4 mm, and the resistance value is 100 Ohm / sq; the absorbing material layer is a 3D printed structure, the material is CNTs-doped ABS material, and the 3D printed structure is two regular hexagonal prism periodic units of different sizes, and the size of the regular hexagonal prism periodic unit is shown in Table 1 below.

[0024] Table 1

[0025] The preparation method of the above-mentioned lightweight broadband absorbing structure based on 3D printing and resistor film is as follows: 1. According to the size information of the regular hexagonal column periodic unit, the raw material is CNTs doped with ABS, and the structural absorbing material layer is printed and manufactured using 3D printing technology. The size of the structural absorbing material layer is 500mm×500mm×5.7mm (length×width×height); 2. According to the resistance value of the resistor film layer of 100Ohm / sq, the raw material is graphite slurry, and the resistor film layer is obtained by screen printing on one side of the Pi film. The plane size of the resistor film is 500mm×500mm; 3. First, apply a release agent on the compression molding die, and then layer the support foam, 0.1mm transparent film, resistor film, 0.1mm transparent film and structural absorbing material layer in sequence (bottom side down, top side up). Before compression molding, place a metal plate on the top of the structural absorbing material layer to evenly distribute the compression pressure. Set the compression temperature to 80℃, the compression pressure to 0.1MPa~0.15MPa and the compression time to 6h before compression molding. 4. After the compression molding is completed, the compression-molded absorbing structure flat blank is taken out, and after removing the excess material, the plane size is cut to obtain a lightweight broadband absorbing structure based on 3D printing and resistive film with a plane size of 500mm×500mm and a thickness of about 17.8mm.

[0026] The lightweight broadband absorbing structure based on 3D printing and resistive film provided in this embodiment has a reflection curve under TE and TM polarization in the frequency band of 1 GHz to 18 GHz under vertical incidence. Figure 5 As can be seen from the figure, taking -10dB as the standard, the effective absorbing bandwidth of the absorbing structure is 2.0GHz~18GHz, and within the low frequency range of 2.0GHz~18GHz, the reflection loss is less than -10dB.

[0027] Embodiment 2: like Figure 1 As shown, this embodiment provides a lightweight broadband absorbing structure based on 3D printing and a resistive film, including a metal bottom layer, a support layer, a resistive film layer and an absorbing material layer arranged in sequence from bottom to top.

[0028] like Figure 2-3 As shown, the support layer material is PMI foam with a thickness of 4.7 mm, the relative dielectric constant ε' satisfies: 3.0≤ɛ'≤3.5, and the loss tangent tanδ satisfies: 0.002≤tanδ≤0.0025; the resistance value of the resistor film layer is 150 Ohm / sq; the structural absorbing material layer is a 3D printed structure, the material is CNTs-doped ABS, and the 3D printed structure periodic unit is two different sizes of regular hexagonal prism periodic units, and the size information of the regular hexagonal prism periodic unit is as shown in Table 2.

[0029] Table 2

[0030] The preparation method of the above-mentioned lightweight broadband absorbing structure based on 3D printing and resistor film is as follows: 1. According to the size information of the regular hexagonal column periodic unit, the raw material is CNTs doped with ABS, and the structural absorbing material layer is printed and manufactured using 3D printing technology. The size of the structural absorbing material layer is 500mm×500mm×4.7mm (length×width×height); 2. According to the resistance value of the resistor film layer of 150Ohm / sq, the raw material is graphite slurry, and the entire surface of the Pi film is screen-printed to obtain the resistor film layer, and the plane size of the resistor film is 500mm×500mm; 3. First, apply a release agent on the compression molding die, and then layer the support foam, 0.1mm transparent film, resistor film, 0.1mm transparent film and structural absorbing material layer in sequence (bottom side down, top side up). Before compression molding, place a metal plate on the top of the structural absorbing material layer to evenly distribute the compression pressure. Set the compression temperature to 80℃, the compression pressure to 0.1MPa~0.15MPa and the compression time to 6h before compression molding. 4. After the compression molding is completed, the compression-molded absorbing structure flat sheet blank is taken out, and after removing the excess material, the plane size is cut to obtain a lightweight broadband absorbing structure based on 3D printing and resistive film with a plane size of 500 mm×500 mm and a thickness of about 20.8 mm.

[0031] The lightweight broadband absorbing structure based on 3D printing and resistive film provided in this embodiment has a reflection curve under TE and TM polarization in the frequency band of 1 GHz to 18 GHz under vertical incidence. Figure 6 As can be seen from the figure, taking -10dB as the standard, the effective absorbing bandwidth of the absorbing structure is 2.0GHz~18GHz, and within the low frequency range of 2.0GHz~18GHz, the reflection loss is less than -10dB.

[0032] Comparative Example 1: like Figure 7 As shown, this comparative example provides a wave absorbing structure based on a resistor film, including a metal bottom layer, a support layer, a resistor film layer and a wave absorbing material layer arranged in sequence from bottom to top.

[0033] like Figure 8-9 As shown, the support layer material is PMI foam with a thickness of 4.7 mm, the relative dielectric constant ε' satisfies: 3.0≤ɛ'≤3.5, and the loss tangent tanδ satisfies: 0.002≤tanδ≤0.0025; the resistance value of the resistor film layer is 100 Ohm / sq; the absorbing material layer is made of CNTs-doped ABS, and the periodic unit size information of the absorbing structure based on the resistor film is shown in Table 3.

[0034] Table 3

[0035] The preparation method of the above-mentioned wave absorbing structure based on the resistor film is as follows: 1. According to the thickness dimension information of the absorbing material layer, the raw material is CNTs doped with ABS, and the absorbing material layer is printed and manufactured by using 3D printing technology. The dimension of the structural absorbing material layer is 500mm×500mm×4.7mm (length×width×height); 2. According to the resistance value of the resistor film layer of 100Ohm / sq, the raw material is graphite slurry, and the resistor film layer is obtained by screen printing on one side of the Pi film. The plane size of the resistor film is 500mm×500mm; 3. The composite material compression molding technology was adopted to prepare the resistive film-based absorbing structure of this comparative example. First, a release agent was applied to the compression molding mold, and then the supporting foam, 0.1 mm wave-transmitting adhesive film, the resistive film layer, the 0.1 mm wave-transmitting adhesive film and the absorbing material layer were layered in sequence. Before compression molding, a metal plate was placed on the top surface of the absorbing material layer to evenly distribute the compression pressure. The compression temperature was set to 80° C., the compression pressure was 0.1 MPa to 0.15 MPa, and the compression time was 6 h, and then compression molding was performed; 4. After the compression molding is completed, the compression molded absorbing structure flat blank is taken out, and after removing the excess material, the planar size is cut to obtain a resistive film-based absorbing structure with a planar size of 500 mm×500 mm and a thickness of about 17.8 mm.

[0036] The absorbing structure based on the resistor film provided in this comparative example has a reflection curve under TE and TM polarization in the frequency band of 1 GHz to 18 GHz under vertical incidence. Fig.10 As can be seen from the figure, taking -10dB as the standard, the effective absorbing bandwidth of the absorbing structure is 1.2GHz to 1.7GHz.

[0037] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A lightweight broadband absorbing structure based on 3D printing and resistive film, characterized by: It includes a metal bottom layer, a support layer, a resistance film layer and a structural absorbing material layer arranged in sequence from bottom to top. The structural absorbing material layer is a 3D printed structure made of CNTs-doped ABS material. The periodic units of the 3D printed structure are regular hexagonal column periodic units of two different sizes.

2. According to claim 1, a lightweight broadband absorbing structure based on 3D printing and resistive film, characterized in that: The regular hexagonal prism periodic unit is a first regular hexagonal prism with a side length of 4.00 mm, a first bottom regular hexagonal opening with a side length of 0.88 mm, a first top regular hexagonal side length of 3.77 mm, a second regular hexagonal prism with a side length of 4.00 mm, a second bottom regular hexagonal opening with a side length of 0.30 mm, and a second top regular hexagonal side length of 3.77 mm.

3. According to claim 1, a lightweight broadband absorbing structure based on 3D printing and resistive film, characterized in that: The dielectric constant of the CNTs-doped ABS material satisfies the real part ɛ' and the imaginary part ɛ'': 5.5≤ɛ'≤11.4, 1.6≤ɛ''≤3.

9.

4. According to claim 1, a lightweight broadband absorbing structure based on 3D printing and resistive film, characterized in that: The resistor film layer material is a graphite screen-printed Pi film.

5. According to claim 1, a lightweight broadband absorbing structure based on 3D printing and resistive film, characterized in that: The resistance value of the resistance film layer is 100-150 Ohm / sq.

6. According to claim 1, a lightweight broadband absorbing structure based on 3D printing and resistive film, characterized in that: The support layer material is PMI foam, the relative dielectric constant ε' satisfies: 3.0≤ɛ'≤3.5, and the loss tangent tanδ satisfies: 0.002≤tanδ≤0.0025.

7. The lightweight broadband absorbing structure based on 3D printing and resistive film according to claim 1, characterized in that: The support layer has a thickness of 4.7-5.7 mm, and the 3D absorbing material has a thickness of 12-16 mm.

8. A method for preparing a lightweight broadband absorbing structure based on 3D printing and a resistor film according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, obtaining a structural absorbing material layer and a resistive film layer; S2. Apply a release agent on the compression molding die, and sequentially lay a support foam, a wave-transmitting adhesive film, a resistor film layer, a wave-transmitting adhesive film, and a structural wave-absorbing material layer; S3, placing a metal plate on the top surface of the above-mentioned structure absorbing material layer to evenly distribute the molding pressure, setting the molding temperature, molding pressure and molding time for molding; S5. After the compression molding is completed, the compression molded flat blank is taken out, excess materials are removed, and the flat size is cut to obtain the lightweight broadband absorbing structure.

Images