Low-frequency wave-absorbing and corrosion-resistant composite material, and preparation method and application thereof

Abstract

This invention discloses a low-frequency absorbing and corrosion-resistant composite material, its preparation method, and its application. The preparation method includes: placing spherical carbonyl iron powder in a vacuum tube furnace and carrying out a micro-oxidation reaction under an air atmosphere and a reaction temperature of 200°C; placing the prepared sample at the tail gas end of a plasma reactor, mixing sodium hypophosphite and selenium powder evenly and placing the mixture at the inlet end of the vacuum tube furnace, and reacting under an Ar atmosphere and a certain plasma power to obtain an intermediate product of carbonyl iron / Fe3P / FeSe composite material; introducing an acetylene / Ar mixed gas, and reacting for a period of time at a certain reaction temperature and a certain plasma power to obtain the final product of carbonyl iron / Fe3P / FeSe / carbon composite material. The composite material prepared by this invention has the characteristics of high-efficiency low-frequency absorbing and salt spray corrosion resistance, and exhibits excellent radiation performance and RCS suppression capability when applied in patch antennas.

Description

Technical Field

[0001] This invention belongs to the field of radar stealth, specifically relating to a low-frequency absorbing and corrosion-resistant composite material, its preparation method, and its application. Background Technology

[0002] The rapid development of electronic and communication technologies, such as 5G, the Internet of Things, satellite internet, and various radar sensing systems, has greatly improved the efficiency of information exchange. However, the large-scale application of electromagnetic waves has also brought increasingly serious problems of electromagnetic radiation and electromagnetic pollution. In the military field, strong electromagnetic detection poses a continuous threat to platform survivability; in the civilian field, the risks of electromagnetic interference and bio-electromagnetic exposure are equally significant. Magnetic absorbing materials, which can convert incident electromagnetic waves into heat dissipation, have become one of the core technological paths to address these problems. Among them, spherical carbonyl iron (CIP), with its high saturation magnetization and good processability, has long been used as the basic absorber for S-band (2–4 GHz) and C-band (4–8 GHz) absorbing composite materials. However, this material itself has two inherent defects: first, poor low-frequency absorption performance, limited by the large demagnetization factor of spherical particles and the physical constraints of the Snoek limit, making it difficult to simultaneously obtain high real part of permeability and sufficient loss in the S and C bands; second, easy corrosion, carbonyl iron is extremely prone to oxidation and corrosion in humid or salt spray environments, leading to rapid degradation of absorption performance and even structural failure. These shortcomings become increasingly apparent when facing harsh marine environments.

[0003] The problem becomes further complicated when spherical carbonyl iron materials are used in stealth antennas to reduce radar cross section (RCS). The introduction of the absorbing layer directly conflicts with the antenna's radiation performance, leading to a decrease in gain and beam distortion. The limited space of the radome or back cavity forces the absorbing layer thickness to be compressed, further deteriorating the already insufficient reduction in the low-end RCS of the S-band. At the same time, electromagnetic coupling between the absorbing material and the antenna elements may cause impedance mismatch, enhanced mutual coupling, and parasitic resonances, while the cladding or encapsulation layers used for corrosion protection can also cause secondary interference to the antenna aperture field.

[0004] This creates a complex system engineering dilemma where low-frequency absorption, corrosion protection, and stealth antennas are interconnected: the high permeability and high fill ratio required for low-frequency absorption exacerbate the difficulty of corrosion protection and worsen antenna radiation performance; while the cladding or passivation layer required for corrosion protection further weakens the already limited low-frequency absorption capability and interferes with the antenna's near-field performance, creating a mutually restrictive relationship among the three. Therefore, achieving synergistic optimization of stealth antenna radiation efficiency and RCS reduction while meeting S / C band absorption specifications and salt spray protection requirements has become a critical technological bottleneck that urgently needs to be overcome. Summary of the Invention

[0005] To address the aforementioned problems or shortcomings, this invention proposes a low-frequency absorbing and corrosion-resistant composite material, its preparation method, and its application.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a low-frequency microwave absorbing and corrosion-resistant composite material includes the following steps: Step 1: Place a certain mass of spherical carbonyl iron powder in a vacuum tube furnace and carry out a micro-oxidation reaction for a period of time under air atmosphere and reaction temperature of 200℃. Step 2: Place the sample prepared in Step 1 at the tail gas end of the plasma reactor. Mix sodium hypophosphite and selenium powder in a certain mass ratio and place them at the inlet end of the vacuum tube furnace. After reacting for a period of time under Ar atmosphere, a certain reaction temperature and a certain plasma power, the intermediate product obtained is carbonyl iron / Fe3P / FeSe composite material. Step 3: After the reaction in step 2 is completed, a mixture of acetylene and Ar gas is introduced. Under a certain reaction temperature and a certain plasma power, the final product obtained after a period of time is carbonyl iron / Fe3P / FeSe / carbon composite material.

[0007] Specifically, in step 2, the mass of the carbonyl iron micro-oxidation sample is fixed.

[0008] Preferably, in step 2, the mass ratio of sodium hypophosphite to selenium powder is 2.0.

[0009] Specifically, in step 2, the plasma power and reaction time are fixed.

[0010] As a preferred option, the reaction temperature in step 3 is 200℃.

[0011] As another preferred option, the reaction temperature in step 3 is 300°C.

[0012] As another preferred option, the reaction temperature in step 3 is 400°C.

[0013] Specifically, in step 3, the plasma power and reaction temperature are the same as in step 2.

[0014] Preferably, in step 3, the ratio of acetylene to Ar gas flow rate is 1.0, and the reaction time is fixed.

[0015] The present invention also proposes a method for preparing a low-frequency absorbing and corrosion-resistant composite material.

[0016] This invention also proposes the application of low-frequency absorbing and corrosion-resistant composite materials in absorbing materials.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The carbonyl iron composite material prepared by this invention utilizes the oxidation of carbonyl iron, sodium hypophosphite, and selenium powder, acetylene cracking, and plasma gas-phase induced synthesis mechanism. By controlling parameters such as different reactant mass ratios, reaction time, temperature, plasma power, and reaction atmosphere, Fe3P / FeSe / carbon heterostructure interfaces are constructed in situ on the surface of carbonyl iron, thereby optimizing the microwave absorption and corrosion performance of spherical carbonyl iron. While ensuring the high-efficiency radiation performance of the antenna, RCS suppression is also achieved.

[0018] 2. The carbonyl iron composite material prepared by this invention possesses excellent multifunctional properties, integrating low-frequency absorption, salt spray corrosion protection, and stealth antenna functions. It exhibits adjustable impedance matching and electromagnetic wave attenuation capabilities in the S and C bands, enhancing its physical shielding ability against corrosive media. Simultaneously, as a stealth element in the stealth antenna, it demonstrates excellent radiation performance in the X-band (8-12GHz) and achieves full-band RCS suppression from 2-18GHz. The design of the Fe3P / FeSe / carbon heterostructure interface in this patent provides a new approach for the multifunctional application of carbonyl iron materials.

[0019] 3. The preparation process described in this invention has mild conditions, stable and controllable structure, low cost, high yield, and is environmentally friendly, with extremely high commercial application potential. Attached Figure Description

[0020] Figure 1 The images show the XRD and Raman spectra of the carbonyl iron original sample, and the samples prepared in Examples 1, 2 and 3 of this invention; where a is the XRD spectrum and b is the Raman spectrum. Figure 2 The images shown are SEM images of the original carbonyl iron sample, Example 3, and a mapping diagram of Example 3. Specifically, a1 is the SEM image of the original carbonyl iron sample (scale bar: 8 μm), a2 is the SEM image of the original carbonyl iron sample (scale bar: 3 μm), a3 is the SEM image of the original carbonyl iron sample (scale bar: 2 μm), b1 is the SEM image of the original carbonyl iron sample (scale bar: 8 μm), b2 is the SEM image of the original carbonyl iron sample (scale bar: 3 μm), and b3 is the SEM image of the original carbonyl iron sample (scale bar: 2 μm). m), c is the SEMMAP of Example 3 (scale bar is 2μm), d is the Fe element mapping diagram of Example 3 (scale bar is 2μm), e is the P element mapping diagram of Example 3 (scale bar is 2μm), f is the Se element mapping diagram of Example 3 (scale bar is 2μm), g is the C element mapping diagram of Example 3 (scale bar is 2μm), and h is the O element mapping diagram of Example 3 (scale bar is 2μm). Figure 3The above are the XPS analysis results of the sample prepared in Example 3 of the present invention; where a is the full spectrum, b is the XPS analysis result of Fe element, c is the XPS analysis result of P element, d is the XPS analysis result of Se element, e is the XPS analysis result of C element, and f is the XPS analysis result of O element. Figure 4 The images show the RL diagrams of the original carbonyl iron sample, samples prepared in Examples 1, 2, and 3 of this invention; where a is the RL diagram of the original carbonyl iron sample, b is the RL diagram of the sample prepared in Example 1, c is the RL diagram of the sample prepared in Example 2, and d is the RL diagram of the sample prepared in Example 3. Figure 5 Impedance matching diagrams are shown for the original carbonyl iron sample, samples prepared in Example 1, Example 2 and Example 3 of the present invention, where a is the impedance matching diagram of the original carbonyl iron sample, b is the impedance matching diagram of the sample prepared in Example 1, c is the impedance matching diagram of the sample prepared in Example 2 and d is the impedance matching diagram of the sample prepared in Example 3. Figure 6 The decay constant curves are for the carbonyl iron original sample, and the samples prepared in Example 1, Example 2 and Example 3 of this invention; Figure 7 The electrochemical corrosion results are shown for the original carbonyl iron sample, and the samples prepared in Examples 1, 2 and 3 of this invention; where a is the Tafel curve, b is the EIS curve, c is the impedance-frequency curve, and d is the phase angle-frequency curve. Figure 8 The antenna performance of the non-absorbing patch of the present invention and the sample prepared in Example 3 as the absorbing patch is shown below. In this diagram, a is the gain diagram of the non-absorbing antenna at 9.78 GHz; b is the gain diagram of the antenna prepared in Example 3 at 9.78 GHz; c is a comparison of the total radiation efficiency of the antennas with and without absorbing devices at 9.78 GHz; d is the gain diagram of the non-absorbing antenna at 10.35 GHz; e is the gain diagram of the antenna prepared in Example 3 at 10.35 GHz; and f is a comparison of the total radiation efficiency of the antennas with and without absorbing devices at 10.35 GHz. Figure 9 The S11 curve and RCS curves of electromagnetic waves at different incident angles are shown for the non-absorbing patch of the present invention, using the sample prepared in Example 3 as the absorbing patch; wherein, a is the S11 curve, b is the RCS curve of electromagnetic waves incident at 0°, c is the RCS curve of electromagnetic waves incident at 15°, d is the RCS curve of electromagnetic waves incident at 30°, e is the RCS curve of electromagnetic waves incident at 45°, and f is the RCS curve of electromagnetic waves incident at 60°. Detailed Implementation

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0022] A method for preparing a low-frequency microwave absorbing and corrosion-resistant composite material includes the following steps: Step 1: Place a certain mass of spherical carbonyl iron powder in a vacuum tube furnace and carry out a micro-oxidation reaction for a period of time under air atmosphere and reaction temperature of 200℃. Step 2: Place the sample prepared in Step 1 at the tail gas end of the plasma reactor. Mix sodium hypophosphite and selenium powder in a certain mass ratio and place them at the inlet end of the vacuum tube furnace. After reacting for a period of time under Ar atmosphere, a certain reaction temperature and a certain plasma power, the intermediate product obtained is carbonyl iron / Fe3P / FeSe composite material. Step 3: After the reaction in step 2 is completed, a mixture of acetylene and Ar gas is introduced. Under a certain reaction temperature and a certain plasma power, the final product obtained after a period of time is carbonyl iron / Fe3P / FeSe / carbon composite material.

[0023] In step 2, the mass of the carbonyl iron micro-oxidation sample is fixed.

[0024] In step 2, the mass ratio of sodium hypophosphite to selenium powder is 2.0.

[0025] In step 2, the plasma power and reaction time are fixed.

[0026] As a preferred option, the reaction temperature in step 3 is 200℃.

[0027] As another preferred option, the reaction temperature in step 3 is 300°C.

[0028] As another preferred option, the reaction temperature in step 3 is 400°C.

[0029] In step 3, the plasma power and reaction temperature are the same as in step 2.

[0030] In step 3, the ratio of acetylene to Ar gas flow rate is 1.0, and the reaction time is fixed.

[0031] The preparation method of this invention is based on the following principle: utilizing the plasma chemical vapor phase induced reaction mechanism, carbonyl iron powder is first micro-oxidized to lay the structural foundation for the construction of Fe3P / FeSe / carbon heterogeneous interface; then, the micro-oxidized sample undergoes a chemical reaction with vaporized sodium hypophosphite and selenium powder precursors at high temperature, converting the iron oxide on the surface into Fe3P and FeSe; next, an amorphous carbon layer of a certain thickness is grown on the carbonyl iron / Fe3P / FeSe surface, and multiple heterogeneous interfaces are constructed, ultimately preparing a carbonyl iron-based composite material with high efficiency, low frequency microwave absorption, and corrosion resistance.

[0032] The present invention also proposes a method for preparing a low-frequency absorbing and corrosion-resistant composite material.

[0033] This invention also proposes the application of low-frequency absorbing and corrosion-resistant composite materials in absorbing materials. It can be used as a low-frequency absorbing, corrosion-protected, and stealth antenna, exhibiting highly efficient low-frequency absorbing performance in the S and C bands, significantly improving corrosion protection capabilities, while also demonstrating excellent radiation performance and RCS suppression performance in stealth antennas.

[0034] Example 1 A method for preparing a low-frequency microwave absorbing and corrosion-resistant composite material includes the following steps: Step 1: Place 10g of spherical carbonyl iron powder in a vacuum tube furnace and perform a micro-oxidation reaction at 200℃ for 5 hours in an air atmosphere, with a heating rate of 10℃ / min.

[0035] Step 2: Weigh 2g of the sample prepared in Step 1 and place it at the tail gas end of the vacuum tube furnace. Mix sodium hypophosphite and selenium powder (3g) at a mass ratio of 2:1 evenly and place them at the inlet gas end of the vacuum tube furnace. Under Ar atmosphere, the plasma power is 250W, the Ar gas flow rate is 40ml / min, the heating rate is 5℃ / min, the reaction temperature is 200℃, and the reaction is carried out for 1h.

[0036] Step 3: After the reaction in Step 2 is completed, acetylene gas is introduced at a flow rate of 40 ml / min, and the reaction continues for 30 min. The final product obtained is the sample of Example 1, named CPSC200.

[0037] Example 2 The difference between this embodiment and Example 1 is that the reaction temperature in steps 2 and 3 is 300°C; the remaining steps are the same as in Example 1, and the prepared sample is named CPSC300.

[0038] Example 3 The difference between this embodiment and Example 1 is that the reaction temperature in steps 2 and 3 is 400℃; the remaining steps are the same as in Example 1, and the prepared sample is named CPSC400.

[0039] Figure 1 a represents the XRD patterns of the original carbonyl iron sample, and the samples prepared in Examples 1, 2, and 3 of this invention; (The last part, "a", appears to be a fragment and doesn't translate directly. It likely refers to a specific XRD pattern or data point.) Figure 1As can be seen from a, the carbonyl iron sample used in this invention exhibits three main characteristic peaks, corresponding to the (110), (200), and (211) crystal planes respectively, indicating that the carbonyl iron sample used has high purity. The CPSC200 and CPSC300 samples only showed the characteristic peaks of carbonyl iron, without showing obvious characteristic peaks of other substances, while the CPSC400 sample showed characteristic peaks of FeSe and Fe3P in addition to the three characteristic peaks of carbonyl iron. Therefore, the CPSC400 sample is mainly composed of carbonyl iron material, with FeSe and Fe3P as auxiliary materials, which means that FeSe and Fe3P substances were successfully grown under the combined action of sodium hypophosphite and selenium powder. Figure 1 b shows the Raman spectra of the carbonyl iron original sample, and the samples prepared in Examples 1, 2, and 3 of this invention. It can be seen that as the reaction temperature gradually increases, the D and G peaks of the carbon material become more pronounced, proving the successful construction of the carbon layer. Furthermore, for the CPSC300 and CPSC400 samples, the corresponding I... D / I G The values ​​are 1.25 and 1.09, respectively, indicating that the graphitization degree of the surface carbon layer gradually increases.

[0040] Figure 2 These are SEM images and mapping diagrams of the original carbonyl iron sample and the CPSC400 sample of this invention; from Figure 2 As can be seen from a1-a3, the carbonyl iron sample used in this invention exhibits a relatively regular spherical shape and a relatively smooth surface; from Figure 2 As shown in b1-b3, after micro-oxidation and plasma gas phase reaction, the overall structure can basically maintain a spherical shape, but the surface is relatively rough. At the same time, some particles show the case of shell layer peeling off, indicating that the surface treatment technology of the present invention can construct a core-shell structure. Figure 2 The results from ch showed that Fe, P, Se, C, and O elements were uniformly distributed on the particle surface.

[0041] Figure 3 This is the XPS analysis result of Example 3 of the present invention; Figure 3 The full spectrum and fine spectra of Fe2p, P2P and Se3d, C1s and O1s show that the surface material of the sample is mainly composed of Fe, P, Se, C and O elements, and the surface material is mainly FeSe, Fe3P and carbon. This result is basically consistent with the XRD and Raman analysis results, confirming that this method can grow FeSe, Fe3P and carbon heterostructure interfaces on the surface of spherical carbonyl iron.

[0042] Figure 4The images show the RL diagrams of the carbonyl iron original sample, and the samples prepared in Examples 1, 2, and 3 of this invention. The results show that, with a thickness of 2.0 mm, the carbonyl iron original sample achieves the lowest reflection loss value (RL) at 10.48 GHz. min The absorption efficiency is approximately -36.7 dB. However, its absorption performance in the S and C bands is poor; after surface treatment modification, the absorption performance in the S and C bands is significantly optimized, especially for the CPSC300 and CPSC400 samples. At a thickness of 4.5 mm, the CPSC300 sample achieved an absorption efficiency of approximately -36.7 dB in the S and C bands. min The value is approximately -38.0 dB, and the RL value of the CPSC400 sample at 2.78 GHz is... min The value is -35.22dB, indicating that the surface treatment technology proposed in this invention has excellent advantages and value in improving the low-frequency microwave absorption performance of spherical carbonyl iron materials.

[0043] Figure 5 Impedance matching diagrams of the original carbonyl iron sample, and the samples prepared in Example 1, Example 2 and Example 3 of this invention; Figure 5 The results show that the impedance matching value |Δ|<0.4 of the original carbonyl iron sample is mainly concentrated above 6 GHz, while the impedance matching value |Δ|<0.4 of the CPSC200, CPSC300 and CPSC400 samples is mainly concentrated in the S and C bands. This indicates that the impedance matching capability of the modified samples in the low frequency band has been significantly improved, which means that electromagnetic waves in the low frequency band can more easily enter the interior of the absorbing material, providing a prerequisite for the subsequent attenuation of electromagnetic waves.

[0044] Figure 6 The decay constant curves are for the carbonyl iron original sample, and the samples prepared in Example 1, Example 2 and Example 3 of this invention; Figure 6 The results show that the attenuation constant of the modified sample is significantly better than that of the original carbonyl iron sample in the full frequency band of 2-18 GHz, which means that the Fe3P / FeSe / carbon heterostructure can effectively improve the attenuation ability of the absorbing material to electromagnetic waves.

[0045] Figure 7 The electrochemical corrosion results are for the original carbonyl iron sample, and the samples prepared in Examples 1, 2 and 3 of this invention. Figure 7 The results of a show that the E of the modified sample corr The value gradually tends towards the positive direction of the X-axis, indicating that the corrosive activity of carbonyl iron has been effectively suppressed. Simultaneously, the corresponding I... corr The values ​​also showed a trend of shifting in the negative direction of the Y-axis, especially for the CPSC400 sample, which means that the corrosion rate of carbonyl iron was also significantly curbed. Figure 7The results in b show that the EIS of the modified samples gradually increased, indicating that the charge transfer ability was suppressed, especially the CPSC400 sample, which showed the most significant effect. Figure 7 The results show that the CPSC400 sample has the highest impedance value at 0.01 Hz, which means that the Fe3P / FeSe / carbon heterostructure constructed under this condition has the best shielding ability against corrosive media. Figure 7 The results showed that the CPSC400 sample had the largest phase angle at 10 Hz, which also indicated that it had the best corrosion resistance.

[0046] Figure 8 The antenna performance of the non-absorbing patch of the present invention and the sample prepared in Example 3 as the absorbing patch is shown. The results show that when the sample prepared in Example 3 is placed in the patch antenna, it can maintain excellent radiation performance at 9.78 GHz and 10.35 GHz, and the total radiation efficiency is also significantly improved.

[0047] Figure 9 The S11 curve and RCS curve of electromagnetic waves at different incident angles are shown for the non-absorbing patch of the present invention, using the sample prepared in Example 3 as the absorbing patch. Figure 9 The results showed that in the 8-12 GHz band, the S11 values ​​of the absorbers were all below -10 dB, which means that the introduction of the sample prepared in Example 3 can significantly improve the impedance matching capability of the patch antenna. Figure 9 The results from bf show that the sample prepared in Example 3 can reduce the RCS value of the antenna under different incident angles of electromagnetic waves, and is effective in a wide frequency band of 2-18 GHz. This indicates that the sample prepared in Example 3 can help the patch antenna achieve wide-angle and full-band electromagnetic stealth.

Claims

1. A method for preparing a low-frequency microwave absorbing and corrosion-resistant composite material, characterized in that, Includes the following steps: Step 1: Place a certain mass of spherical carbonyl iron powder in a vacuum tube furnace and carry out a micro-oxidation reaction for a period of time under air atmosphere and reaction temperature of 200 ℃. Step 2: Place the sample prepared in Step 1 at the tail gas end of the plasma reactor. Mix sodium hypophosphite and selenium powder in a certain mass ratio and place them at the inlet end of the vacuum tube furnace. After reacting for a period of time under Ar atmosphere, a certain reaction temperature and a certain plasma power, the intermediate product obtained is carbonyl iron / Fe3P / FeSe composite material. Step 3: After the reaction in step 2 is completed, a mixture of acetylene and Ar gas is introduced. Under a certain reaction temperature and a certain plasma power, the final product obtained after a period of time is carbonyl iron / Fe3P / FeSe / carbon composite material.

2. The method for preparing a low-frequency absorbing and corrosion-resistant composite material according to claim 1, characterized in that, In step 2, the mass ratio of sodium hypophosphite to selenium powder is 2.

0.

3. The method for preparing a low-frequency absorbing and corrosion-resistant composite material according to claim 1, characterized in that, In step 2, the plasma power and reaction time are fixed.

4. The method for preparing a low-frequency absorbing and corrosion-resistant composite material according to claim 1, characterized in that, In step 2, the reaction temperature is 200 ℃.

5. The method for preparing a low-frequency absorbing and corrosion-resistant composite material according to claim 1, characterized in that, In step 2, the reaction temperature is 300 ℃.

6. The method for preparing a low-frequency absorbing and corrosion-resistant composite material according to claim 1, characterized in that, In step 2, the reaction temperature is 400 ℃.

7. The method for preparing a low-frequency absorbing and corrosion-resistant composite material according to claim 1, characterized in that, In step 3, the plasma power and reaction temperature are the same as in step 2.

8. The method for preparing a low-frequency absorbing and corrosion-resistant composite material according to claim 1, characterized in that, In step 3, the ratio of acetylene to Ar gas flow rate is 1.0, and the reaction time is fixed.

9. The low-frequency absorbing and corrosion-resistant composite material prepared by the preparation method according to any one of claims 1-8.

10. The application of the low-frequency absorbing and corrosion-resistant composite material according to claim 9 in microwave absorbing materials.

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