Array type flaky carbonyl iron composite PDMS flexible wave-absorbing film and preparation method thereof

Abstract

The invention relates to the technical field of wave-absorbing materials, in particular to an array type flaky carbonyl iron composite PDMS flexible wave-absorbing film and a preparation method thereof. PDMS is used as a matrix, flaky carbonyl iron is used as a filler, and the flaky carbonyl iron is regularly arranged in an array manner in the radial direction of the matrix; and the wave-absorbing response frequency band when RL is less than or equal to-5 dB is 2.7-18.0 GHz, so that the absorption of low-frequency S / C wave band electromagnetic waves is enhanced. The preparation method comprises the following steps: weighing PDMS, adding a solvent, magnetically stirring uniformly, and then adding a curing agent to obtain a precursor solution; preparing a flaky carbonyl iron dispersion liquid; adding the precursor solution into the flaky carbonyl iron dispersion liquid, and mechanically stirring until the solution is in a homogeneous state; and transferring the mixed solution to a mold, carrying out vacuum degassing, applying a uniform magnetic field, heating and curing to obtain the array type flaky carbonyl iron composite PDMS flexible film. The technical problems of weak low-frequency response and narrow wave-absorbing frequency band of the wave-absorbing material are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of wave-absorbing materials, and in particular to an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film and a preparation method thereof. Background Art

[0002] The widespread application of electronic communications technology, particularly satellite communications, broadband radar, wireless networks, and multi-band, high-power electronic devices, has greatly improved people's lives, but has also led to serious problems with electromagnetic interference and radiation. Common electronic devices, such as mobile phones, Wi-Fi routers, Bluetooth devices, and microwave ovens, generally operate in the 2-6 GHz frequency range. Military radar systems primarily operate in the 4-18 GHz frequency range, defined as the C-band, X-band, and Ku-band. This situation has led to an increasingly urgent demand for broadband electromagnetic wave absorbing materials in both military and civilian applications, and has also placed higher demands on their performance. In practical applications, broadband electromagnetic wave absorbing materials must not only possess excellent absorption capabilities but also achieve efficient absorption across a wider frequency range. This is particularly true in the low-frequency band, where the longer wavelengths and more dispersed energy distribution of electromagnetic waves significantly increase the difficulty of absorbing these waves. Consequently, electromagnetic wave absorbing materials often face challenges in low-frequency bands, such as weak low-frequency response and a narrow absorption bandwidth. Improving low-frequency absorption has become a key research area for absorbing materials.

[0003] However, achieving compatibility between strong low-frequency response and wide absorption bandwidth is not easy, and this is a technical challenge that needs to be overcome in the design of absorbing materials. To solve this problem, researchers need to conduct in-depth research on the material's microstructure, electromagnetic properties, and interaction mechanism with electromagnetic waves. Through innovative material design and preparation processes, they can develop absorbing materials that can perform well in both low-frequency bands and broadband ranges. In addition to absorbing performance, the physical properties of absorbing materials also play a decisive role in their practical applications. Their lightness, thinness, and flexibility make them easier to integrate into various devices and structures, meeting the trend of miniaturization and lightweighting in modern electronic devices. Their excellent mechanical strength ensures that the material is not easily damaged during use, improving its reliability and service life. Their hydrophobicity helps them maintain stable performance in complex environments, preventing degradation of their absorbing performance due to factors such as moisture. Therefore, while improving the absorbing performance of absorbing materials, continuously optimizing their physical properties, such as lightness, flexibility, mechanical strength, and hydrophobicity, will further expand their practical application space and enable them to play a greater role in numerous fields, including aerospace, electronic communications, and national defense and military affairs. Summary of the Invention The purpose of the present invention is to provide an array-type sheet-like carbonyl iron composite PDMS flexible absorbing film and a preparation method thereof, which solves the technical problems of weak low-frequency response and narrow absorbing frequency band of absorbing materials.

[0004] The present invention is achieved through the following technical solutions: The present invention discloses an array-type flaky carbonyl iron composite PDMS flexible wave-absorbing film, wherein PDMS serves as a matrix and flaky carbonyl iron serves as a filler, and the flaky carbonyl iron is neatly arranged in an array along the radial direction of the matrix; In the array-type flaky carbonyl iron composite PDMS flexible wave-absorbing film, the mass fraction of the flaky carbonyl iron is 68%-75%, and the rest is the matrix.

[0005] Furthermore, the effective absorption bandwidth for RL≤ -10 dB (absorbing 90% of electromagnetic waves) is 8.6 GHz (9.2-17.8 GHz); the absorption response band for RL≤ -5 dB (absorbing 68% of electromagnetic waves) is 2.7-18.0 GHz, which enhances the absorption of low-frequency S / C band electromagnetic waves.

[0006] Furthermore, the array-type sheet-like carbonyl iron composite PDMS flexible absorbing film has a hydrophilic contact angle of 114-120° and a tensile strength of 0.68-0.8 MPa.

[0007] The present invention also discloses a method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film, comprising the following steps: (1) Weigh PDMS, add solvent, stir magnetically until uniform, then add curing agent, continue magnetic stirring to obtain a precursor solution; Weighing flaky carbonyl iron powder, adding a solvent, and ultrasonically dispersing to obtain a flaky carbonyl iron dispersion; (2) Add the precursor solution to the flaky carbonyl iron dispersion and mechanically stir until the solution is in a homogeneous state; transfer the mixed solution to a mold, vacuum degas, apply a uniform magnetic field and heat to cure, thereby obtaining an array-type flaky carbonyl iron composite PDMS flexible film.

[0008] Furthermore, in step (1), the mass ratio of PDMS, curing agent, and solvent in the precursor solution is 10:1:10.

[0009] Furthermore, in step (1), the mass ratio of the flaky carbonyl iron dispersion to the precursor solution is (1.5-2.0):1.

[0010] Furthermore, in step (1), the concentration of the flaky carbonyl iron dispersion is (64-71) wt%.

[0011] Furthermore, in step (1), the solvent is n-hexane, chloroform or petroleum ether.

[0012] Furthermore, in step (2), the vacuum degassing conditions are: vacuum degree of -0.1 MPa, time of 30 to 60 min; The curing temperature is 70~90 ℃ and the curing time is 2~4 h.

[0013] Furthermore, in step (2), the uniform magnetic field is generated by a one-dimensional Helmholtz coil, the magnetic field direction is perpendicular to the surface of the mixed liquid, the magnetic field intensity is 50~70 mT, and the magnetic field uniformity is 94%~96%.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention discloses an array-type flaky carbonyl iron composite PDMS flexible absorbing film and its preparation method. Using flaky carbonyl iron as a filler and PDMS as a matrix, uniform magnetic field induced assembly technology is used to manipulate the flaky carbonyl iron into an orderly radial arrangement. Simultaneously, PDMS encapsulates the ordered structure, resulting in an array-type flaky carbonyl iron composite PDMS flexible absorbing film. The flaky carbonyl iron exhibits excellent dielectric loss and magnetic loss properties. The vertically oriented, ordered arrangement effectively increases electromagnetic wave resonant loss, improves low-frequency electromagnetic wave response, and further broadens the effective absorbing frequency band.

[0015] Furthermore, the film has strong low-frequency absorption capabilities, with a minimum reflection loss value of -42.7 dB; the absorption bandwidth is wide, and the effective absorption bandwidth for RL≤ -10 dB (absorbing 90% of electromagnetic waves) is 8.6 GHz (9.2-17.8 GHz); the absorption response band for RL≤-5 dB (absorbing 68% of electromagnetic waves) is 2.7-18.0 GHz, almost covering the S-band, C-band, X-band and Ku-band, strongly compensating for the shortcomings of existing absorbing materials.

[0016] Furthermore, the hydrophilic contact angle of the film is 114~120°, and the tensile strength of the film is 0.7~0.8 MPa. It has excellent hydrophobic properties, flexibility, and mechanical strength, further expanding the practical application range of the absorbing film. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The following are the physical photos and mechanical properties diagrams of the film of Example 1; Figure 2 is a reflection loss curve of the film of Example 1; Figure 3 is a reflection loss curve of the film of Example 2; Figure 4 is a reflection loss curve of the film of Example 3; Figure 5 is a reflection loss curve of the film of Example 4; Figure 6 is a reflection loss curve of the film of Example 5; Figure 7 The water contact angle diagram of the film of Example 1-5; Figure 8 These are SEM images of the cross-section of the wave-absorbing and heat-conducting flexible composite film prepared in the present invention; wherein, Figure (a) is the SEM image at 30 μm; Figure (b) is the SEM image at 10 μm. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear, the following is a further detailed description with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0019] The detailed description of the embodiment of the present invention provided in the following figures is not intended to limit the scope of the claimed invention, but merely represents a selected embodiment of the present invention. All other embodiments derived by those skilled in the art based on the figures and embodiments of the present invention without inventive effort shall fall within the scope of protection of the present invention.

[0020] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0021] Example 1 This embodiment discloses a method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film, comprising the following steps: (1) Weigh 4.2 g of polydimethylsiloxane (PDMS), add 4.2 g of n-hexane, stir magnetically until evenly mixed, then add 0.42 g of curing agent, and continue magnetic stirring for 10 min to obtain a precursor solution.

[0022] (2) Weigh 9.8 g of flaky carbonyl iron powder, add 4 g of n-hexane, and disperse by ultrasonication for 10 min to obtain a flaky carbonyl iron dispersion.

[0023] (3) Then, the precursor solution prepared in (1) is added to the flake carbonyl iron dispersion, and mechanically stirred until the solution is in a homogeneous state; The mixed liquid was placed in a mold and transferred to the sample stage in the center of the Helmholtz coil. A 60 mT uniform magnetic field was applied and vacuum degassing was carried out for 1 h with a vacuum degree of -0.1 MPa. The temperature was then raised to 80 °C and kept for 3 h to obtain an array-type sheet-like carbonyl iron composite PDMS flexible film.

[0024] The curing agent used in the present invention is Dow Corning DC184 curing agent, and the core component of Dow Corning DC184 curing agent is usually a silicon-containing cross-linking agent.

[0025] like Figure 1 The figure shows a photograph of the array-type sheet-like carbonyl iron composite PDMS flexible film prepared by the present invention. The film can be folded multiple times and has good flexibility. Its maximum strain is 61.4% and the maximum stress is 0.66 MPa.

[0026] In the array-type flaky carbonyl iron composite PDMS flexible film prepared in this example, the mass fraction of the flaky carbonyl iron is 68%.

[0027] like Figure 7 As shown in FIG, the water contact angle test was performed on the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in this embodiment, and the contact angle was 120°.

[0028] The tensile strength test of the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in Example 1 was performed, and the tensile strength was 0.7 MPa.

[0029] like Figure 2 As shown, the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in this embodiment reaches a minimum reflection loss value of -42.73 dB at a frequency of 5.59 GHz in the C band, that is, the wave absorbing ability is the strongest at this frequency.

[0030] At 9.0 GHz in the X-band, the minimum return loss value is -19.41 dB.

[0031] At the Ku-band frequency of 13.8 GHz, the minimum return loss value is -14.26 dB.

[0032] As shown in Table 1, the effective absorption bandwidth for RL ≤ -10 dB (90% absorption of electromagnetic waves) is 8.0 GHz (9.5-17.5 GHz); the absorption response bandwidth for RL ≤ -5 dB (68% absorption of electromagnetic waves) is 2.8-18.0 GHz.

[0033] Example 2 This embodiment discloses a method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film, comprising the following steps: (1) Weigh 4.2 g of PDMS, add 4.2 g of chloroform, stir magnetically, then add 0.42 g of curing agent, and continue magnetic stirring for 10 min to obtain a precursor solution.

[0034] (2) Weigh 12.6 g of flaky carbonyl iron powder, add 7 g of chloroform, and disperse by ultrasonication for 10 min to obtain a flaky carbonyl iron dispersion.

[0035] (3) Then, the precursor solution prepared in (1) is added to the flake carbonyl iron dispersion, and mechanically stirred until the solution is in a homogeneous state; The mixed liquid was placed in a mold and transferred to the sample stage in the center of the Helmholtz coil. A 50 mT uniform magnetic field was applied and vacuum degassing was carried out for 30 min at a vacuum degree of -0.1 MPa. The temperature was then raised to 70 °C and kept for 4 h to obtain an array-type sheet-like carbonyl iron composite PDMS flexible film.

[0036] In the array-type flaky carbonyl iron composite PDMS flexible film prepared in this example, the mass fraction of the flaky carbonyl iron is 73.2%.

[0037] like Figure 7 As shown in FIG, the water contact angle test of the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in this embodiment was conducted, and the contact angle was 116°.

[0038] The tensile strength test of the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in Example 2 was performed, and the tensile strength was 0.68 MPa.

[0039] like Figure 3 As shown, the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in this embodiment reaches a minimum reflection loss value of -42.26 dB at a frequency of 6.10 GHz in the C band, that is, the wave absorbing ability is the strongest at this frequency.

[0040] At 9.0 GHz in the X-band, the minimum return loss value is -19.41 dB.

[0041] At the Ku-band frequency of 13.8 GHz, the minimum return loss value is -14.26 dB.

[0042] As shown in Table 1, the effective absorption bandwidth for RL ≤ -10 dB (90% absorption of electromagnetic waves) is 7.7 GHz (8.9-16.6 GHz); the absorption response bandwidth for RL ≤ -5 dB (68% absorption of electromagnetic waves) is 2.8-18.0 GHz.

[0043] Example 3 This embodiment discloses a method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film, comprising the following steps: (1) Weigh 8.0 g of PDMS, add 8.0 g of petroleum ether, stir magnetically until evenly mixed, then add 0.8 g of curing agent, and continue magnetic stirring for 15 min to obtain a precursor solution.

[0044] (2) Weigh 18.7 g of flaky carbonyl iron powder, add 10 g of petroleum ether, and ultrasonically disperse for 15 min to obtain a flaky carbonyl iron dispersion.

[0045] (3) Then, the precursor solution prepared in (1) is added to the flake carbonyl iron dispersion, and mechanically stirred until the solution is in a homogeneous state; The mixed liquid was placed in a mold and transferred to the sample stage in the center of the Helmholtz coil. A 70 mT uniform magnetic field was applied and vacuum degassing was carried out for 1 h with a vacuum degree of -0.1 MPa. The temperature was then raised to 90 °C and kept for 2 h to obtain an array-type sheet-like carbonyl iron composite PDMS flexible film.

[0046] like Figure 7 As shown in FIG, the water contact angle test of the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in this embodiment was conducted, and the contact angle was 115°.

[0047] The tensile strength test of the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in Example 1 was performed, and the tensile strength was 0.7 MPa.

[0048] In the array-type flaky carbonyl iron composite PDMS flexible film prepared in this example, the mass fraction of the flaky carbonyl iron is 68%.

[0049] like Figure 4 As shown in the figure, the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in this embodiment reaches a minimum reflection loss value of -43.14 dB at a frequency of 6.23 GHz in the C band, that is, the wave absorption ability is the strongest at this frequency; at a frequency of 8.6 GHz in the X band, the minimum reflection loss value is -19.75 dB; at a frequency of 12.4 GHz in the Ku band, the minimum reflection loss value is -16.38 dB. As shown in Table 1, the effective absorption bandwidth for RL ≤ -10 dB (90% absorption of electromagnetic waves) is 8.0 GHz (9.0-17.0 GHz); the absorption response bandwidth for RL ≤ -5 dB (68% absorption of electromagnetic waves) is 3.0-18.0 GHz.

[0050] Example 4 This embodiment discloses a method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film, comprising the following steps: (1) Weigh 4.2 g of PDMS, add 4.2 g of n-hexane, stir magnetically until evenly mixed, then add 0.42 g of curing agent, and continue magnetic stirring for 10 min to obtain a precursor solution.

[0051] (2) Weigh 11 g of flaky carbonyl iron powder, add 6 g of n-hexane, and disperse by ultrasonication for 10 min to obtain a flaky carbonyl iron dispersion.

[0052] (3) Then, the precursor solution prepared in (1) is added to the flake carbonyl iron dispersion, and mechanically stirred until the solution is in a homogeneous state; The mixed liquid was placed in a mold and transferred to the sample stage in the center of the Helmholtz coil. A 50 mT uniform magnetic field was applied and vacuum degassing was carried out for 30 min at a vacuum degree of -0.1 MPa. The temperature was then raised to 70 °C and kept for 4 h to obtain an array-type sheet-like carbonyl iron composite PDMS flexible film.

[0053] In the array-type flaky carbonyl iron composite PDMS flexible film prepared in this example, the mass fraction of the flaky carbonyl iron is 70.4%.

[0054] like Figure 7 As shown in FIG, the water contact angle test of the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in this embodiment was conducted, and the contact angle was 116°.

[0055] like Figure 5 As shown in the graph, the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in this embodiment reaches a minimum reflection loss value of -40.29 dB at a frequency of 5.59 GHz in the C band, that is, the wave absorption ability is the strongest at this frequency; at a frequency of 8.0 GHz in the X band, the minimum reflection loss value is -21.84 dB; and at a frequency of 12.0 GHz in the Ku band, the minimum reflection loss value is -14.56 dB. As shown in Table 1, the effective absorption bandwidth for RL ≤ -10 dB (90% absorption of electromagnetic waves) is 8.1 GHz (9.5-17.6 GHz); the absorption response bandwidth for RL ≤ -5 dB (68% absorption of electromagnetic waves) is 2.7-18.0 GHz.

[0056] Example 5 This embodiment discloses a method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film, comprising the following steps: (1) Weigh 7 g of PDMS, add 7 g of n-hexane, stir magnetically, then add 0.7 g of curing agent, and continue magnetic stirring for 10 min to obtain a precursor solution.

[0057] (2) Weigh 16.3 g of flaky carbonyl iron powder, add 8.1 g of n-hexane, and ultrasonically disperse for 10 min to obtain a flaky carbonyl iron dispersion.

[0058] (3) Then, the precursor solution prepared in (1) is added to the flake carbonyl iron dispersion, and mechanically stirred until the solution is in a homogeneous state; The mixed liquid was placed in a mold and transferred to the sample stage in the center of the Helmholtz coil. A 60 mT uniform magnetic field was applied and vacuum degassing was carried out for 30 min with a vacuum degree of -0.1 MPa. The temperature was then raised to 80 °C and kept for 4 h to obtain an array-type sheet-like carbonyl iron composite PDMS flexible film.

[0059] In the array-type flaky carbonyl iron composite PDMS flexible film prepared in this example, the mass fraction of the flaky carbonyl iron is 67.9%. like Figure 7 As shown in FIG, the water contact angle test of the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in this embodiment was conducted, and the contact angle was 114°.

[0060] The tensile strength test of the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in Example 1 was performed, and the tensile strength was 0.8 MPa.

[0061] like Figure 6 As shown, the array-type sheet-like carbonyl iron composite PDMS flexible film prepared in this embodiment reaches a minimum reflection loss value of -39.66 dB at a frequency of 4.74 GHz in the C band, that is, the wave absorption ability is the strongest at this frequency; at a frequency of 8.0 GHz in the X band, the minimum reflection loss value is -23.46 dB; at a frequency of 12.2 GHz in the Ku band, the minimum reflection loss value is -14.87 dB. As shown in Table 1, the effective absorption bandwidth for RL ≤ -10 dB (90% absorption of electromagnetic waves) is 8.0 GHz (9.1-17.1 GHz); the absorption response bandwidth for RL ≤ -5 dB (68% absorption of electromagnetic waves) is 2.7-18.0 GHz.

[0062] Table 1 Performance comparison of films of Examples 1-5 and other similar patented results

[0063] In Table 1, Comparative Example 1 cites patent document with application number 202311574625.4, which discloses a method for preparing a carbonyl iron absorbing coating with anti-corrosion and self-repairing functions; Comparative Example 2 cites patent document with application number 202311322683.8, which discloses a surface-coated low-frequency composite absorber of electromagnetic waves and a preparation method thereof; Comparative Example 3 cites patent document with application number 202311130878.2, which discloses a polycrystalline carbonyl iron, a preparation method thereof, and an application thereof in an absorber; Comparative Example 4 cites patent document with application number 202310253287.8, which discloses a preparation method and application of a flexible carbonyl iron inverted pyramid metamaterial film; Comparative Example 5 cites patent document with application number 202311098750.2, which discloses a modified carbonyl iron powder and a preparation method thereof.

[0064] The present invention provides a preparation method and broadband application of an array-type sheet-like carbonyl iron composite PDMS flexible absorbing film, which expands the assembly objects of magnetic induction technology from isotropic spherical materials to anisotropic two-dimensional structural materials, and effectively solves the technical problems of weak low-frequency response and narrow absorbing bandwidth in the field of absorbing waves.

[0065] like Figure 8 As shown in Figures (a) and (b) of the present invention, the array-type flaky carbonyl iron composite PDMS flexible microwave-absorbing film comprises polydimethylsiloxane as the matrix and flaky carbonyl iron as the filler. The flaky carbonyl iron is neatly arranged radially along the matrix. In the array-type flaky carbonyl iron composite PDMS flexible microwave-absorbing film, the carbonyl iron flaky carbonyl iron has a size of 1-5 μm and a mass fraction of 68%-75%, with the remainder being the matrix.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the present invention.

Claims

1. An array-type sheet-like carbonyl iron composite PDMS flexible absorbing film, characterized in that: PDMS is used as the matrix and flake carbonyl iron is used as the filler. The flake carbonyl iron is arranged in a neat array along the radial direction of the matrix. In the array-type flaky carbonyl iron composite PDMS flexible wave-absorbing film, the mass fraction of the flaky carbonyl iron is 68%-75%, and the rest is the matrix.

2. The array-type sheet-like carbonyl iron composite PDMS flexible absorbing film according to claim 1, characterized in that: The effective absorption bandwidth for RL≤ -10 dB (90% absorption of electromagnetic waves) is 8.6 GHz (9.2-17.8 GHz); the absorption response bandwidth for RL≤ -5 dB (68% absorption of electromagnetic waves) is 2.7-18.0 GHz, which enhances the absorption of low-frequency S / C band electromagnetic waves.

3. The array-type sheet-like carbonyl iron composite PDMS flexible absorbing film according to claim 1, characterized in that: The array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film has a hydrophilic contact angle of 114-120° and a tensile strength of 0.68-0.8 MPa.

4. A method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film, characterized in that: The following steps are involved: (1) Weigh PDMS, add solvent, stir magnetically until uniform, then add curing agent, continue magnetic stirring to obtain a precursor solution; Weighing flaky carbonyl iron powder, adding a solvent, and ultrasonically dispersing to obtain a flaky carbonyl iron dispersion; (2) Add the precursor solution to the flaky carbonyl iron dispersion and mechanically stir until the solution is in a homogeneous state; transfer the mixed solution to a mold, vacuum degas, apply a uniform magnetic field and heat to cure, thereby obtaining an array-type flaky carbonyl iron composite PDMS flexible film.

5. The method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film according to claim 4, characterized in that: In step (1), the mass ratio of PDMS, curing agent, and solvent in the precursor solution is 10:1:

10.

6. The method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film according to claim 4, characterized in that: In step (1), the mass ratio of the flaky carbonyl iron dispersion to the precursor solution is (1.5-2.0):

1.

7. The method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film according to claim 4, characterized in that: In step (1), the concentration of the flaky carbonyl iron dispersion is (64 to 71) wt%.

8. The method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film according to claim 4, characterized in that: In step (1), the solvent is n-hexane, chloroform or petroleum ether.

9. The method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible wave-absorbing film according to claim 4, characterized in that: In step (2), the vacuum degassing conditions are: vacuum degree of -0.1 MPa, time of 30-60 min; The curing temperature is 70~90 ℃ and the curing time is 2~4 h.

10. The method for preparing an array-type sheet-like carbonyl iron composite PDMS flexible absorbing film according to claim 4, wherein in step (2), the uniform magnetic field is generated by a one-dimensional Helmholtz coil, the magnetic field direction is perpendicular to the surface of the mixed liquid, the magnetic field intensity is 50-70 mT, and the magnetic field uniformity is 94%-96%.

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