A radar wave absorber and its preparation method

Abstract

A radar wave absorber, comprising component A and component B, wherein component A is Fe 1‑x‑y Si x Cr y powder, 0.08 ≤ x + y ≤ 0.1; component B is Ba z (Co 2‑m‑n Ni m Zn n )(MnFe) w O u powder, 0.5 ≤ m + n ≤ 1.2, w / z = 8 - 16. The present invention has excellent wave absorption performance at low frequencies and good corrosion resistance; it can also play a role when the dosage is small; the radar wave absorber of the present invention can also be added to materials such as resins and rubbers to form wave-absorbing materials in various forms such as coatings, patches, skins, and plates, and is used for wave absorption and stealth of various equipment; the preparation method is simple and suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to an absorbing material and a preparation method thereof, and particularly to a radar wave absorbing material and a preparation method thereof. Background Art

[0002] Radar absorbing materials can dissipate the energy of incident radar waves through forms such as electrical loss, dielectric loss, and magnetic loss, reduce the reflectivity, and thus achieve stealth against radar waves. In recent years, the research work on radar absorbing materials has mainly focused on dealing with the working frequency range of fire control radars (i.e., X and Ku bands, 8-18 GHz frequency band), and good results have been achieved in the thinning and weight reduction of absorbing materials in the high-frequency band. There is less research on absorbing materials for the working frequency range of search and tracking radars (L, S, and C bands, 1-8 GHz frequency band).

[0003] Ferrite absorbing materials have excellent corrosion resistance and can be applied to harsh environments with high salinity (chloride ions Cl - multi) and humidity in the ocean. For traditional spinel-type ferrite absorbing materials, when in the frequency band below 8 GHz, a very large thickness is required to achieve good absorbing performance. For example, when manganese-zinc ferrite and nickel-zinc ferrite are used as absorbing bricks in microwave anechoic chambers, the thickness is generally 5-7 mm. While barium ferrite absorbing materials have good absorbing performance in the high-frequency band, they cannot be applied to the low-frequency band of 1-4 GHz, and also require a thickness of more than 2 mm in the range of 4-8 GHz. Patent CN103922716A uses the nitrate solution method to prepare zinc-doped W-type barium ferrite BaZn x Co 2-x Fe 16 O 27 , and the particle size of the material is 0.5-1 μm. Among them, the absorbing material with the composition of BaZn 0.7 Co 1.3 Fe 16 O 27 has an absorbing performance of -49 dB at a frequency of 12.8 GHz with a thickness of 2.1 mm. Patent CN104628372B discloses a niobium-nickel (NbNi) co-doped barium ferrite absorbing powder material with the chemical formula BaFe 12-2x Nb x Ni x O 19 (M-type), where x = 0.4-0.6, and is prepared by a self-propagating combustion method combined with ball milling and subsequent secondary high-temperature heat treatment process. The effective absorbing frequency band of this material is in the frequency range of 18-40 GHz. Patent CN103086706A discloses a preparation method of a Zr-Mn-Co multi-doped barium ferrite absorbing material, and uses a hydrothermal-assisted sol-gel method to prepare M-type barium ferrite, but does not explain whether the absorbing performance of this material is in the high-frequency or low-frequency range.

[0004] FeSiCr alloy is based on FeSi alloy. By adding an appropriate amount of Cr, it has the characteristics of high saturation magnetization intensity and low high-frequency loss, and is particularly suitable for making key inductance components with small volume, high frequency, and high power. The addition of Cr can increase the resistivity and corrosion resistance of the alloy, reduce magnetic anisotropy, and improve the oxidation resistance of the alloy. Some studies have used FeSiCr as a wave-absorbing material. For example, Xiong Houdong, Zhong Zhenchen, etc. in the article "Microwave Absorbing Properties of Graphene Oxide Modified FeSiCr Nanocomposites", by introducing graphene oxide GO, can increase the conductivity and interfacial polarization ability of the material, and significantly improve the microwave absorption performance of FeSiCr / GO. It can be found from the reflection loss curve when the coating thickness is 2.8 mm that at 6 GHz, the reflection loss peak of FeSiCr / GO reaches -31 dB. Hong Qihu, Yan Shaojiu, etc. in the article "Effect of Surface Modification on the Temperature-resistant Wave Absorbing Properties of FeSiCr Magnetic Wave Absorbing Materials", calculated the reflection loss value of the coating with a thickness of 2 mm according to the line transmission theory. Among them, the original iron-silicon-chromium magnetic powder reaches the minimum reflection loss of -12 dB at 3.5 GHz at room temperature. Thus, it can be seen that iron-silicon-chromium has good wave absorption performance at low frequencies, but requires a relatively large coating thickness. The relatively thick thickness leads to an increase in the weight of the wave-absorbing material, which affects its scope of use to a certain extent. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the above-mentioned defects existing in the prior art, and provide a radar wave absorber and its preparation method. The radar wave absorber has good wave absorption performance in the low-frequency band, has good corrosion resistance, and can also play a wave absorption role in a relatively thin coating.

[0006] A radar wave absorber includes component A and component B. Component A is Fe 1-x-y Si x Cr y powder, 0.08 ≤ x + y ≤ 0.1; Component B is Ba z (Co 2-m-n Ni m Zn n )(MnFe) w O u powder, 0.5 ≤ m + n ≤ 1.2, w / z = 8 - 16. The amount of oxygen element in the chemical formula of component B is determined by the amount of metal elements.

[0007] Preferably, in component A, x = 0.03 - 0.07, y = 0.02 - 0.06; in component B, z = 1 - 3.

[0008] Preferably, the mass ratio of component A to component B is 0.01 - 1:1.

[0009] Preferably, the component A is a flat powder with D50 = 10 - 15 microns.

[0010] Preferably, the component B is a flat powder with D50 = 12 - 15 microns.

[0011] Preferably, the raw material of the component A is an element or an alloy.

[0012] Preferably, the raw materials of the component B are barium carbonate, cobalt oxide, nickel oxide, zinc oxide and iron oxide.

[0013] Preferably, the preparation method of the component A is as follows:

[0014] (a1) Take the raw material of the component A and melt it into an iron - silicon - chromium alloy liquid;

[0015] (a2) By gas atomization method, make the iron - silicon - chromium alloy liquid into spherical powder,

[0016] (a3) Screen to obtain powder with D50 = 5 - 8 microns;

[0017] (a4) Grind the powder obtained in step (a3) into a flat powder under the protection of ethanol;

[0018] (a5) The flat powder is separated by air flow to obtain a flat powder with D50 = 10 - 15 microns, thus completing the preparation.

[0019] Preferably, the preparation method of the component B is as follows:

[0020] (b1) Take the raw materials of the component B, mix them evenly, and sinter them into a block in an air atmosphere;

[0021] (b2) Mechanically crush the block into powder;

[0022] (b3) After air - flow separation of the powder obtained in step (b2), select a flat powder with D50 = 12 - 15 microns, thus completing the preparation.

[0023] More preferably, the sintering temperature is 1200 - 1500 °C and the sintering time is 1 - 10 h.

[0024] The preparation method of the radar wave absorber of the present invention is to mix each component evenly, thus completing the preparation.

[0025] The present invention conducts a composite design on the radar wave absorber applied to low frequencies. On the ferrite substrate, by compounding iron - silicon - chromium alloy powder, the advantages of the two components are fully utilized to achieve excellent wave - absorbing performance and good corrosion resistance at low frequencies. The radar wave absorber of the present invention can be added to materials such as resins and rubbers to make wave - absorbing materials such as coatings, patches, skins, and plates, and can be used for wave - absorption and stealth of various equipment.

[0026] Based on the fact that the resonance frequencies of Z-type barium ferrite (z = 3, w / z = 8) and W-type barium ferrite (z = 1, w / z = 16) are lower than that of M-type barium ferrite, by optimizing and adjusting the ratios of Ni, Zn, and Co, it has good wave absorption performance in the range of 5 - 8 GHz. And by adjusting the contents of silicon and chromium in the Fe-Si-Cr alloy, while maintaining excellent wave absorption performance in the range of 1 - 6 GHz, its corrosion resistance is optimized to improve the comprehensive performance of the absorber. When the thickness is 1.8 mm, in the range of 1 - 2 GHz, the wave absorption performance is below -4 dB, and in the range of 2 - 8 GHz, the wave absorption performance is below -7 dB. And it has excellent weather resistance, with the neutral salt spray test exceeding 3000 h.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] (1) The present invention has excellent wave absorption performance at low frequencies and good corrosion resistance;

[0029] (2) The present invention can also play a role when the dosage is small. When a coating with a thickness of 1.8 mm is made, in the range of 1 - 2 GHz, the wave absorption performance is below -4 dB, and in the range of 2 - 8 GHz, the wave absorption performance is below -7 dB; and it has excellent weather resistance, with the neutral salt spray test exceeding 3000 h;

[0030] (3) The radar wave absorber of the present invention can also be added to materials such as resins and rubbers to make wave absorption materials in various forms such as coatings, patches, skins, and plates, which are used for wave absorption and stealth of various equipment;

[0031] (4) The preparation method of the present invention is simple and suitable for large-scale industrial production. Description of the Drawings

[0032] Figure 1 It is the scanning electron microscope image of the component B powder in Example 1 of the present invention. Detailed Embodiments

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the embodiments and the drawings:

[0034] The raw materials used in the embodiments of the present invention are all obtained through conventional commercial channels.

[0035] Example 1

[0036] The radar wave absorber in this example includes component A and component B. Component A is Fe 0.91 Si 0.04 Cr 0.05 powder, and component B is Ba3(Co 1.5Ni 0.2 Zn 0.3 )(MnFe) 24 O 41 Powder; the mass ratio of component A to component B is 0.1:1. Component A is a flat powder with D50 = 10 μm; component B is a flat powder with D50 = 12 μm.

[0037] The raw materials of component A are the simple substances of Fe, Si and Cr.

[0038] The raw materials of component B are barium carbonate, cobalt oxide, nickel oxide, zinc oxide and iron oxide.

[0039] The preparation method of the said component A is as follows:

[0040] (a1) Take the raw materials of component A and melt them into an iron-silicon-chromium alloy liquid at high temperature by using an induction melting furnace;

[0041] (a2) By means of gas atomization method, make the said iron-silicon-chromium alloy liquid into spherical powder,

[0042] (a3) Screen to obtain powder with D50 = 5 μm;

[0043] (a4) Put the powder obtained in step (a3) into a ball milling barrel, add steel balls and ethanol, and ball mill it into a flat powder under the protection of ethanol;

[0044] (a5) The said flat powder is sorted by air flow to obtain a flat powder with D50 = 10 μm, thus completed.

[0045] The preparation method of the said component B is as follows:

[0046] (b1) Take the raw materials of component B, mix them evenly, load them into a crucible, and sinter them into a block in an air atmosphere in a high-temperature furnace; the sintering temperature is 1200 °C and the sintering time is 6 h;

[0047] (b2) Mechanically crush the said block into powder;

[0048] (b3) After the powder obtained in step (b2) is sorted by air flow, select a flat powder with D50 = 12 μm, thus completed. The scanning electron microscope image of component B powder is as Figure 1 shown, and it can be seen that the morphology of component B powder is in the shape of flat flakes.

[0049] The radar wave absorber of this embodiment is made by mixing component A and component B evenly in a mixer.

[0050] The prepared radar wave absorber was tested using a vector network analyzer. The wave absorption performance test method was as follows: after mixing the radar wave absorber of this embodiment with paraffin in a ratio of 8:2, a coaxial ring was made, and its electrical parameters were measured using the coaxial method, and the loss values at different frequencies under a thickness of 1.8 mm were calculated through simulation. The corrosion resistance test method was as follows: after mixing the radar wave absorber of this embodiment with resin and curing agent in a ratio of powder:resin:curing agent of 8:2:1, it was scraped on an aluminum plate. After the resin was cured, it was placed in a salt spray test chamber for continuous spraying at 35 °C, and its surface was regularly observed for rust. The specific results are shown in Table 1.

[0051] Example 2

[0052] The radar wave absorber of this embodiment includes component A and component B. Component A is a powder of Fe 0.9 Si 0.05 Cr 0.05 Powder, and component B is a powder of Ba3(Co 0.8 Ni 0.6 Zn 0.6 )(MnFe) 24 O 41 Powder; the mass ratio of component A to component B is 0.05:1. Component A is a flat powder with D50 = 13 μm; component B is a flat powder with D50 = 15 μm.

[0053] The raw materials of component A are the simple substances of Fe, Si, and Cr.

[0054] The raw materials of component B are barium carbonate, cobalt oxide, nickel oxide, zinc oxide, and iron oxide.

[0055] The preparation method of the said component A is as follows:

[0056] (a1) Take the raw materials of component A, and use an induction melting furnace to melt them into an iron-silicon-chromium alloy liquid at high temperature;

[0057] (a2) Through gas atomization, make the iron-silicon-chromium alloy liquid into spherical powder,

[0058] (a3) Screen to obtain powder with D50 = 8 μm;

[0059] (a4) Put the powder obtained in step (a3) into a ball milling barrel, add steel balls and ethanol, and ball mill it into a flat powder under the protection of ethanol;

[0060] (a5) The flat powder is sorted by air flow to obtain a flat powder with D50 = 13 μm, and that's it.

[0061] The preparation method of the said component B is as follows:

[0062] (b1) Mix the raw materials of component B evenly, put them in a sagger, and sinter them into a block in an air atmosphere in a high-temperature furnace; the sintering temperature is 1300 °C and the sintering time is 4 h;

[0063] (b2) Mechanically crush the block into powder;

[0064] (b3) After air classification of the product obtained in step (b2), select flat powder with D50 = 15 μm, and that's it.

[0065] The radar wave absorber of this example is made by mixing component A and component B evenly in a mixer.

[0066] Test the wave absorption performance and corrosion resistance of the radar wave absorber of this example. The test method is the same as that of Example 1, and the test results are shown in Table 1.

[0067] Example 3

[0068] The radar wave absorber of this example includes component A and component B. Component A is Fe 0.91 Si 0.03 Cr 0.06 powder, and component B is Ba(Co 1.2 Ni 0.3 Zn 0.5 )(MnFe) 16 O 27 powder; the mass ratio of component A to component B is 1:1. Component A is flat powder with D50 = 14 μm; component B is flat powder with D50 = 14 μm.

[0069] The raw materials of component A are the elements of Fe, Si and Cr.

[0070] The raw materials of component B are barium carbonate, cobalt oxide, nickel oxide, zinc oxide and iron oxide.

[0071] The preparation method of the said component A is:

[0072] (a1) Take the raw materials of component A, and melt them into an iron-silicon-chromium alloy liquid at high temperature by an induction melting furnace;

[0073] (a2) By gas atomization method, make the iron-silicon-chromium alloy liquid into spherical powder,

[0074] (a3) Screen to obtain powder with D50 = 6 μm;

[0075] (a4) Put the powder obtained in step (a3) into a ball milling barrel, add steel balls and ethanol, and ball mill it into flat powder under the protection of ethanol;

[0076] (a5) The flat powder is air classified to obtain flat powder with D50 = 14 μm, and that's it.

[0077] The preparation method of the component B is as follows:

[0078] (b1) Mix the raw materials of component B evenly, put them in a sagger, and sinter them into a block in an air atmosphere in a high-temperature furnace; the sintering temperature is 1500 °C, and the sintering time is 2 h;

[0079] (b2) Mechanically crush the block into powder;

[0080] (b3) After air classification of the product obtained in step (b2), select flat powder with D50 = 14 μm, and that's it.

[0081] The radar wave absorber of this embodiment is made by mixing component A and component B evenly in a mixer.

[0082] The radar wave absorber of this embodiment is tested for wave absorption performance and corrosion resistance. The test method is the same as that of Example 1, and the test results are shown in Table 1.

[0083] Comparative Example 1

[0084] This comparative example is basically the same as Example 1, except that the powder particle size D50 of component A in this comparative example is 5.6 μm.

[0085] The radar wave absorber of this comparative example is tested for wave absorption performance and corrosion resistance. The test method is the same as that of Example 1, and the test results are shown in Table 1.

[0086] Comparative Example 2

[0087] This comparative example is basically the same as Example 1, except that the powder particle size D50 of component A in this comparative example is 20.5 μm.

[0088] The radar wave absorber of this comparative example is tested for wave absorption performance and corrosion resistance. The test method is the same as that of Example 1, and the test results are shown in Table 1.

[0089] Comparative Example 3

[0090] This comparative example is basically the same as Example 1, except that the chemical formula of component A in this comparative example is Fe 0.85 Si 0.05 Cr 0.1 , which has a higher chromium content compared to Example 1.

[0091] The radar wave absorber of this comparative example is tested for wave absorption performance and corrosion resistance. The test method is the same as that of Example 1, and the test results are shown in Table 1.

[0092] Comparative Example 4

[0093] This comparative example is basically the same as Example 1, except that there is no Component B in this comparative example.

[0094] The radar wave absorber of this comparative example was tested for wave absorption performance and corrosion resistance. The test method was the same as that of Example 1, and the test results are shown in Table 1.

[0095] Comparative Example 5

[0096] This comparative example is basically the same as Example 1, except that there is no Component A in this comparative example.

[0097] The radar wave absorber of this comparative example was tested for wave absorption performance and corrosion resistance. The test method was the same as that of Example 1, and the test results are shown in Table 1.

[0098] Table 1 Performance test results of the radar wave absorbers of Examples 1 - 3 and Comparative Examples 1 - 5

[0099]

[0100] As can be seen from Table 1, Examples 1 - 3 had higher peaks in the wave absorption performance test, and had good wave absorption performance in the 1 - 8 GHz frequency band, and had good salt spray resistance.

[0101] Compared with Examples 1 - 3 of the present invention, the radar wave absorbers of Comparative Examples 1 - 5 all had certain deficiencies: the radar wave absorber of Comparative Example 1 had insufficient wave absorption performance in the 1 - 2 GHz frequency band; the radar wave absorber of Comparative Example 2 had poor low - frequency wave absorption performance, and when the ratio of the powder to paraffin was 8:2, a smooth ring could not be made, and it was not easy to form a thin coating; the radar wave absorber of Comparative Example 3 had poor low - frequency wave absorption performance; the radar wave absorber of Comparative Example 4 had poor wave absorption performance in the 4 - 8 GHz frequency band; the radar wave absorber of Comparative Example 5 had poor wave absorption performance in the 1 - 4 GHz frequency band.

Claims

1. A radar wave absorber, characterized in that, It includes component A and component B. Component A is Fe 1-x-y Si x Cr y powder, 0.08 ≤ x + y ≤ 0.1, x = 0.03 - 0.07, y = 0.02 - 0.06; Component B is Ba z (Co 2-m-n Ni m Zn n )(MnFe) w O u powder, 0.5 ≤ m + n ≤ 1.2, w / z = 8 - 16, and it is a flat powder with D50 = 12 - 15 μm.

2. The radar wave absorber according to claim 1, wherein In the component B, z = 1 to 3.

3. The radar wave absorber according to claim 1 or 2, characterized in that, The mass ratio of the component A to the component B is 0.01 to 1:

1.

4. The radar wave absorber according to any one of claims 1 to 3, characterized in that The component A is a flat powder with D50 = 10 to 15 microns.

5. The radar wave absorber according to any one of claims 1 to 4, characterized in that, The raw material of the component A is a single element or an alloy.

6. The radar wave absorber according to any one of claims 1 to 5, characterized in that, The raw materials of the component B are barium carbonate, cobalt oxide, nickel oxide, zinc oxide and iron oxide.

7. The radar wave absorber according to any one of claims 1 to 6, characterized in that, The preparation method of the component A is as follows: (a1) Take the raw material of the component A and melt it into an iron-silicon-chromium alloy liquid; (a2) By gas atomization method, make the iron-silicon-chromium alloy liquid into spherical powder, (a3) Screen to obtain powder with D50 = 5 to 8 microns; (a4) Ball-mill the powder obtained in step (a3) into a flat powder under the protection of ethanol; (a5) The flat powder is sorted by air flow to obtain a flat powder with D50 = 10 to 15 microns, thus completing.

8. The radar wave absorber according to any one of claims 1 to 7, characterized in that, The preparation method of the component B is as follows: (b1) Take the raw materials of the component B and mix them evenly, and sinter them into a block in an air atmosphere; (b2) Mechanically crush the block into powder; (b3) After the powder obtained in step (b2) is sorted by air flow, select a flat powder with D50 = 12 to 15 microns, thus completing.

9. The radar wave absorber according to claim 8, wherein, The temperature of the sintering is 1200 to 1500 °C, and the time of the sintering is 1 to 10 h.

10. The preparation method of the radar wave absorber according to any one of claims 1 to 9, characterized in that, Mix each component evenly, thus completing.

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