A flaky nickel-zinc ferrite / polyaniline composite wave-absorbing material, a preparation method and application thereof

Abstract

The application discloses a flaky nickel-zinc ferrite / polyaniline composite wave-absorbing material and a preparation method and application thereof. The preparation method comprises the following steps: dissolving metal salt in deionized water, stirring to obtain solution A; dissolving sodium carbonate and sodium hydroxide in water, stirring to obtain solution B; adding solution B into solution A drop by drop, adjusting pH, standing for crystallization, centrifuging, washing and drying the product to obtain a precursor; high-temperature calcining the precursor in a muffle furnace, adding the obtained flaky nickel-zinc ferrite into a mixed solution of hydrochloric acid and ethanol, adjusting pH, and drying to obtain a hydroxylated ferrite; ultrasonic dispersing the hydroxylated ferrite in an ammonium persulfate hydrochloric acid solution to obtain a dispersion liquid, adding the dispersion liquid into an aniline dichloromethane solution drop by drop, standing for reaction at constant temperature for a period of time, and centrifuging, washing and drying to obtain the flaky nickel-zinc ferrite / polyaniline composite wave-absorbing material. The preparation method is mild, and the prepared wave-absorbing material has good wave-absorbing performance.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing materials technology, specifically to a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material, its preparation method, and its application. Background Technology

[0002] With the rapid development of the modern economy and the widespread application of electrical equipment, electromagnetic wave technology has permeated various fields such as industrial and agricultural production, communication and information industry, transportation, and national defense. While these products of scientific and technological progress have brought great convenience to human production and life, they have also placed humans in an environment full of electromagnetic radiation, causing significant harm. Following air pollution, wastewater pollution, and noise pollution, electromagnetic pollution has been listed by the World Health Organization as the fourth largest source of pollution globally. Electromagnetic pollution not only harms human health but also interferes with the normal use of precision electronic instruments, interrupts signal transmission, and can even lead to the leakage of electromagnetic information, causing national defense security problems.

[0003] Ferrites are among the most mature and widely used microwave absorbing materials, primarily relying on magnetic loss for absorption. However, ferrites, when used alone, suffer from drawbacks such as high material density, poor high-frequency absorption performance, narrow absorption bandwidth, and a relatively thick matching layer, limiting their practical application in electromagnetic wave absorption. For example, Chinese patent (CN103922716A) discloses a zinc-doped W-type barium ferrite composite absorbing material and its preparation method. This patent reduces the absorption frequency through zinc doping, but the absorbing layer is relatively thick, reaching 5.2 mm for 17.5 GHz matching, resulting in poor practicality and low preparation efficiency. Therefore, the development of ferrite absorbing materials has always been a research hotspot. Summary of the Invention

[0004] The main objective of this invention is to propose a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material, its preparation method, and its application. The aim is to provide a method for efficiently and cost-effectively preparing a composite material with superior stability, lower density, and good microwave absorption performance by combining ferrite and polyaniline under mild conditions.

[0005] To achieve the above objectives, this invention proposes a method for preparing a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material, comprising the following steps:

[0006] S1. Dissolve the metal salt in deionized water and stir to obtain solution A. Then dissolve sodium carbonate and sodium hydroxide in deionized water and stir to obtain solution B.

[0007] S2. Add solution B dropwise to solution A, adjust the pH, allow to stand and crystallize to obtain the product, centrifuge, wash and dry the product to obtain the hydrotalcite-like material NiZn-LDH precursor;

[0008] S3. The precursor is calcined at high temperature in a muffle furnace to obtain sheet-like nickel-zinc ferrite. The sheet-like nickel-zinc ferrite is then added to a mixed solution of hydrochloric acid and ethanol, the pH is adjusted, and the mixture is dried to obtain hydroxylated ferrite.

[0009] S4. The hydroxylated ferrite is ultrasonically dispersed in a hydrochloric acid solution of ammonium persulfate to obtain a dispersion. The dispersion is then added dropwise to a dichloromethane solution of aniline. The mixture is kept at a constant temperature and allowed to react for a period of time. After centrifugation, washing, and drying, a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material is obtained.

[0010] Preferably, in step S1, the metal salt is ferric nitrate nonahydrate, ferrous sulfate heptahydrate, nickel nitrate hexahydrate, or zinc nitrate hexahydrate.

[0011] The preferred molar ratio of the nonahydrate ferric nitrate, heptahydrate ferrous sulfate, hexahydrate nickel nitrate, and hexahydrate zinc nitrate is (2-4):(4-6):(1-3):(1-3).

[0012] Preferably, in step S2, the pH is adjusted to 5-10, and the static crystallization time is 2-6 hours.

[0013] Preferably, in step S2, the drying temperature is 50–100°C, and the drying time is 6–12 hours.

[0014] Preferably, in step S3, the high-temperature calcination temperature is 600–1000°C, the high-temperature calcination time is 1–4 hours, and the pH is adjusted to 4–7.

[0015] Preferably, in step S4, the concentration of the hydrochloric acid solution is 0.5–2 mol / L, the reaction time is 6–16 h, and the reaction temperature is 0–25 °C.

[0016] Preferably, in step S4, the mass ratio of the hydroxylated ferrite to aniline is (1:9) to (9:1), and the molar ratio of aniline to ammonium persulfate is (2:1) to (1:2).

[0017] The present invention also proposes a method for preparing sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material as described above.

[0018] This invention further proposes the application of the sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material as described above in the preparation of composite microwave absorbing materials.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] (1) This invention provides a method for preparing sheet-like nickel-zinc ferrite / polyaniline composite material. First, highly dispersed and highly stable sheet-like nickel-zinc ferrite is obtained by adjusting the ion ratio and calcination temperature, which serves as an inorganic magnetic material. Then, the sheet-like nickel-zinc ferrite / polyaniline composite material is prepared by interfacial polymerization. The preparation process of this composite microwave absorbing material is simple, environmentally friendly, low in cost, low in density, and has good absorption performance, and has broad industrialization prospects.

[0021] (2) This invention provides a method for preparing a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material. First, a layered structure is obtained by synthesizing a hydrotalcite-like material NiZn-LDH precursor. Then, the layered precursor is calcined to obtain sheet-like nickel-zinc ferrite. The stacking of the sheet-like structure can suppress the eddy current effect, which is beneficial to the multiple reflection and absorption of electromagnetic waves. It has better space charge polarization than ferrite with particle morphology and can also provide more nucleation sites, so that polyaniline can grow uniformly around it.

[0022] (3) This invention provides a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material. Polyaniline is grown on the surface of the sheet-like nickel-zinc ferrite, while retaining the original sheet-like morphology of the nickel-zinc ferrite and introducing coral-like polyaniline. This makes the surface of the composite material have a rough, irregular and fine structure at the same time, which improves impedance matching, enhances interface polarization and thus enhances microwave absorption capability. At the same time, polyaniline grows between the sheets to form a sandwich structure, which extends the propagation path of electromagnetic waves under the condition of coexistence of electrical loss and magnetic loss, which is beneficial to the energy consumption of electromagnetic waves. Compared with traditional ferrite microwave absorbing materials, this sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material has better microwave absorption performance, larger absorption bandwidth, smaller matching thickness and lower density. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The image shows the XRD pattern of the sheet-like nickel-zinc ferrite prepared in Example 3 of this invention.

[0025] Figure 2 The image shows the XRD pattern of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of this invention.

[0026] Figure 3 This is a SEM image of the sheet-like nickel-zinc ferrite prepared in Example 3 of the present invention;

[0027] Figure 4This is a SEM image of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of the present invention;

[0028] Figure 5 The reflection loss curve of the sheet-like nickel-zinc ferrite prepared in Example 3 of the present invention is shown.

[0029] Figure 6 The reflection loss curve of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of the present invention is shown.

[0030] Figure 7 The real part curve of the complex dielectric constant of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of the present invention is shown.

[0031] Figure 8 The image shows the imaginary part of the complex dielectric constant of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of this invention.

[0032] Figure 9 The graph shows the real part of the complex permeability of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of this invention.

[0033] Figure 10 The image shows the imaginary part of the complex permeability of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of this invention.

[0034] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0037] Example 1

[0038] A method for preparing a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material includes the following steps:

[0039] (1) Preparation of NiZn-LDH precursor, a hydrotalcite-like material: Weigh 8.0g of ferric nitrate nonahydrate, 9.3g of ferrous sulfate heptahydrate, 3.9g of nickel nitrate hexahydrate, and 4g of zinc nitrate hexahydrate and add them to 100ml of deionized water and stir until homogeneous to obtain solution A. Weigh 7.4g of sodium carbonate and 6g of sodium hydroxide and dissolve them in 100ml of deionized water to obtain solution B. Add solution B dropwise to solution A and stir until the pH reaches 8. Let it stand at 50℃ for 10h to crystallize and obtain the product. Wash the product three times alternately with deionized water and anhydrous ethanol and dry it in a vacuum drying oven at 60℃ for 8h to obtain the NiZn-LDH precursor, a hydrotalcite-like material.

[0040] (2) The hydrotalcite-like material NiZn-LDH precursor was spread in a quartz boat and heated in a muffle furnace at a rate of 5℃ / min. It was calcined at 600℃ for 2h to obtain sheet-like nickel-zinc ferrite. The sheet-like nickel-zinc ferrite was then added to 100ml of anhydrous ethanol and ultrasonically dispersed. After adjusting the pH to 5 by adding concentrated hydrochloric acid, it was dried to obtain hydroxylated ferrite.

[0041] (3) Weigh 2.0g of hydroxylated ferrite and 1.1g of ammonium persulfate and add them to 50ml of 1mol / L hydrochloric acid solution. Sonicate to obtain a suspension. Dissolve 0.4g of aniline in 50ml of dichloromethane solution to obtain an organic phase. Slowly inject the suspension onto the surface of the organic phase with a dropper and allow it to separate into layers. After standing at 5℃ for 12h, centrifuge, wash, and dry at 60℃ to obtain sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material.

[0042] Example 2

[0043] A method for preparing a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material includes the following steps:

[0044] (1) Preparation of NiZn-LDH precursor, a hydrotalcite-like material: Weigh 8.0g of ferric nitrate nonahydrate, 9.3g of ferrous sulfate heptahydrate, 3.9g of nickel nitrate hexahydrate, and 4g of zinc nitrate hexahydrate and add them to 100ml of deionized water and stir until homogeneous to obtain solution A. Weigh 7.4g of sodium carbonate and 6g of sodium hydroxide and dissolve them in 100ml of deionized water to obtain solution B. Add solution B dropwise to solution A and stir until the pH reaches 8. Let it stand at 50℃ for 10h to crystallize and obtain the product. Wash the product three times alternately with deionized water and anhydrous ethanol and dry it in a vacuum drying oven at 60℃ for 8h to obtain the NiZn-LDH precursor, a hydrotalcite-like material.

[0045] (2) The hydrotalcite-like material NiZn-LDH precursor was spread in a quartz boat and heated in a muffle furnace at a rate of 5℃ / min. It was calcined at 800℃ for 2h to obtain sheet-like nickel-zinc ferrite. The sheet-like nickel-zinc ferrite was then added to 100ml of anhydrous ethanol and ultrasonically dispersed. After adjusting the pH to 5 by adding concentrated hydrochloric acid, it was dried to obtain hydroxylated ferrite.

[0046] (3) Weigh 2.0g of hydroxylated ferrite and 1.1g of ammonium persulfate and add them to 50ml of 1mol / L hydrochloric acid solution. Sonicate to obtain a suspension. Dissolve 0.4g of aniline in 50ml of dichloromethane solution to obtain an organic phase. Slowly inject the suspension onto the surface of the organic phase with a dropper and allow it to separate into layers. After standing at 5℃ for 12h, centrifuge, wash, and dry at 60℃ to obtain sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material.

[0047] Example 3

[0048] A method for preparing a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material includes the following steps:

[0049] (1) Preparation of NiZn-LDH precursor, a hydrotalcite-like material: Weigh 8.0g of ferric nitrate nonahydrate, 9.3g of ferrous sulfate heptahydrate, 3.9g of nickel nitrate hexahydrate, and 4g of zinc nitrate hexahydrate and add them to 100ml of deionized water and stir until homogeneous to obtain solution A. Weigh 7.4g of sodium carbonate and 6g of sodium hydroxide and dissolve them in 100ml of deionized water to obtain solution B. Add solution B dropwise to solution A and stir until the pH reaches 8. Let it stand at 50℃ for 10h to crystallize and obtain the product. Wash the product three times alternately with deionized water and anhydrous ethanol and dry it in a vacuum drying oven at 60℃ for 8h to obtain the NiZn-LDH precursor, a hydrotalcite-like material.

[0050] (2) The hydrotalcite-like material NiZn-LDH precursor was spread in a quartz boat and heated in a muffle furnace at a rate of 5℃ / min. It was calcined at 1000℃ for 2h to obtain sheet-like nickel-zinc ferrite. The sheet-like nickel-zinc ferrite was then added to 100ml of anhydrous ethanol and ultrasonically dispersed. After adjusting the pH to 5 by adding concentrated hydrochloric acid, it was dried to obtain hydroxylated ferrite.

[0051] (3) Weigh 2.0g of hydroxylated ferrite and 1.1g of ammonium persulfate and add them to 50ml of 1mol / L hydrochloric acid solution. Sonicate to obtain a suspension. Dissolve 0.4g of aniline in 50ml of dichloromethane solution to obtain an organic phase. Slowly inject the suspension onto the surface of the organic phase with a dropper and allow it to separate into layers. After standing at 5℃ for 12h, centrifuge, wash, and dry at 60℃ to obtain sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material.

[0052] Example 4

[0053] A method for preparing a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material includes the following steps:

[0054] (1) Preparation of NiZn-LDH precursor, a hydrotalcite-like material: Weigh 8.0g of ferric nitrate nonahydrate, 9.3g of ferrous sulfate heptahydrate, 3.9g of nickel nitrate hexahydrate, and 4g of zinc nitrate hexahydrate and add them to 100ml of deionized water and stir until homogeneous to obtain solution A. Weigh 7.4g of sodium carbonate and 6g of sodium hydroxide and dissolve them in 100ml of deionized water to obtain solution B. Add solution B dropwise to solution A and stir until the pH reaches 8. Let it stand at 50℃ for 10h to crystallize and obtain the product. Wash the product three times alternately with deionized water and anhydrous ethanol and dry it in a vacuum drying oven at 60℃ for 8h to obtain the NiZn-LDH precursor, a hydrotalcite-like material.

[0055] (2) The hydrotalcite-like material NiZn-LDH precursor was spread in a quartz boat and heated in a muffle furnace at a rate of 5℃ / min. It was calcined at 1000℃ for 2h to obtain sheet-like nickel-zinc ferrite. The sheet-like nickel-zinc ferrite was then added to 100ml of anhydrous ethanol and ultrasonically dispersed. After adjusting the pH to 5 by adding concentrated hydrochloric acid, it was dried to obtain hydroxylated ferrite.

[0056] (3) Weigh 2.0g of hydroxylated ferrite and 1.1g of ammonium persulfate and add them to 50ml of 1mol / L hydrochloric acid solution. Sonicate to obtain a suspension. Dissolve 0.4g of aniline in 50ml of dichloromethane solution to obtain an organic phase. Slowly inject the suspension onto the surface of the organic phase with a dropper and allow it to separate into layers. After standing at 5℃ for 12h, centrifuge, wash, and dry at 60℃ to obtain sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material.

[0057] Example 5

[0058] A method for preparing a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material includes the following steps:

[0059] (1) Preparation of NiZn-LDH precursor, a hydrotalcite-like material: Weigh 8.0g of ferric nitrate nonahydrate, 9.3g of ferrous sulfate heptahydrate, 3.9g of nickel nitrate hexahydrate, and 4g of zinc nitrate hexahydrate and add them to 100ml of deionized water and stir until homogeneous to obtain solution A. Weigh 7.4g of sodium carbonate and 6g of sodium hydroxide and dissolve them in 100ml of deionized water to obtain solution B. Add solution B dropwise to solution A and stir until the pH reaches 8. Let it stand at 50℃ for 10h to crystallize and obtain the product. Wash the product three times alternately with deionized water and anhydrous ethanol and dry it in a vacuum drying oven at 60℃ for 8h to obtain the NiZn-LDH precursor, a hydrotalcite-like material.

[0060] (2) The hydrotalcite-like material NiZn-LDH precursor was spread in a quartz boat and heated in a muffle furnace at a rate of 5℃ / min. It was calcined at 1000℃ for 2h to obtain sheet-like nickel-zinc ferrite. The sheet-like nickel-zinc ferrite was then added to 100ml of anhydrous ethanol and ultrasonically dispersed. After adjusting the pH to 5 by adding concentrated hydrochloric acid, it was dried to obtain hydroxylated ferrite.

[0061] (3) Weigh 2.0g of hydroxylated ferrite and 1.1g of ammonium persulfate and add them to 50ml of 1mol / L hydrochloric acid solution. Sonicate to obtain a suspension. Dissolve 0.4g of aniline in 50ml of dichloromethane solution to obtain an organic phase. Slowly inject the suspension onto the surface of the organic phase with a dropper and allow it to separate into layers. After standing at 15℃ for 12h, centrifuge, wash, and dry at 60℃ to obtain sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material.

[0062] Example 6

[0063] A method for preparing a sheet-like nickel-zinc ferrite / polyaniline microwave absorbing composite material includes the following steps:

[0064] (1) Preparation of NiZn-LDH precursor, a hydrotalcite-like material: Weigh 8.0g of ferric nitrate nonahydrate, 9.3g of ferrous sulfate heptahydrate, 3.9g of nickel nitrate hexahydrate, and 4g of zinc nitrate hexahydrate and add them to 100ml of deionized water and stir until homogeneous to obtain solution A. Weigh 7.4g of sodium carbonate and 6g of sodium hydroxide and dissolve them in 100ml of deionized water to obtain solution B. Add solution B dropwise to solution A and stir until the pH reaches 8. Let it stand at 50℃ for 10h to crystallize and obtain the product. Wash the product three times alternately with deionized water and anhydrous ethanol and dry it in a vacuum drying oven at 60℃ for 8h to obtain the NiZn-LDH precursor, a hydrotalcite-like material.

[0065] (2) The hydrotalcite-like material NiZn-LDH precursor was spread in a quartz boat and heated in a muffle furnace at a rate of 5℃ / min. It was calcined at 1000℃ for 2h to obtain sheet-like nickel-zinc ferrite. The sheet-like nickel-zinc ferrite was then added to 100ml of anhydrous ethanol and ultrasonically dispersed. After adjusting the pH to 5 by adding concentrated hydrochloric acid, it was dried to obtain hydroxylated ferrite.

[0066] (3) Weigh 2.0g of hydroxylated ferrite and 1.1g of ammonium persulfate and add them to 50ml of 1mol / L hydrochloric acid solution. Sonicate to obtain a suspension. Dissolve 0.4g of aniline in 50ml of dichloromethane solution to obtain an organic phase. Slowly inject the suspension onto the surface of the organic phase with a dropper and allow it to separate into layers. After standing at 25℃ for 12h, centrifuge, wash, and dry at 60℃ to obtain sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material.

[0067] Example 7

[0068] A method for preparing a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material includes the following steps:

[0069] (1) Preparation of NiZn-LDH precursor, a hydrotalcite-like material: Weigh 8.0g of ferric nitrate nonahydrate, 9.3g of ferrous sulfate heptahydrate, 3.9g of nickel nitrate hexahydrate, and 4g of zinc nitrate hexahydrate and add them to 100ml of deionized water and stir until homogeneous to obtain solution A. Weigh 7.4g of sodium carbonate and 6g of sodium hydroxide and dissolve them in 100ml of deionized water to obtain solution B. Add solution B dropwise to solution A and stir until the pH reaches 8. Let it stand at 50℃ for 10h to crystallize and obtain the product. Wash the product three times alternately with deionized water and anhydrous ethanol and dry it in a vacuum drying oven at 60℃ for 8h to obtain the NiZn-LDH precursor, a hydrotalcite-like material.

[0070] (2) The hydrotalcite-like material NiZn-LDH precursor was spread in a quartz boat and heated in a muffle furnace at a rate of 5℃ / min. It was calcined at 1000℃ for 2h to obtain sheet-like nickel-zinc ferrite. The sheet-like nickel-zinc ferrite was then added to 100ml of anhydrous ethanol and ultrasonically dispersed. After adjusting the pH to 5 by adding concentrated hydrochloric acid, it was dried to obtain hydroxylated ferrite.

[0071] (3) Weigh 2.0g of hydroxylated ferrite and 0.54g of ammonium persulfate and add them to 50ml of 1mol / L hydrochloric acid solution. Sonicate to obtain a suspension. Dissolve 0.2g of aniline in 50ml of dichloromethane solution to obtain an organic phase. Slowly inject the suspension onto the surface of the organic phase with a dropper and allow it to separate into layers. After standing at 25℃ for 12h, centrifuge, wash, and dry at 60℃ to obtain sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material.

[0072] Example 8

[0073] A method for preparing a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material includes the following steps:

[0074] (1) Preparation of NiZn-LDH precursor, a hydrotalcite-like material: Weigh 8.0g of ferric nitrate nonahydrate, 9.3g of ferrous sulfate heptahydrate, 3.9g of nickel nitrate hexahydrate, and 4g of zinc nitrate hexahydrate and add them to 100ml of deionized water and stir until homogeneous to obtain solution A. Weigh 7.4g of sodium carbonate and 6g of sodium hydroxide and dissolve them in 100ml of deionized water to obtain solution B. Add solution B dropwise to solution A and stir until the pH reaches 8. Let it stand at 50℃ for 10h to crystallize and obtain the product. Wash the product three times alternately with deionized water and anhydrous ethanol and dry it in a vacuum drying oven at 60℃ for 8h to obtain the NiZn-LDH precursor, a hydrotalcite-like material.

[0075] (2) The hydrotalcite-like material NiZn-LDH precursor was spread in a quartz boat and heated in a muffle furnace at a rate of 5℃ / min. It was calcined at 1000℃ for 2h to obtain sheet-like nickel-zinc ferrite. The sheet-like nickel-zinc ferrite was then added to 100ml of anhydrous ethanol and ultrasonically dispersed. After adjusting the pH to 5 by adding concentrated hydrochloric acid, it was dried to obtain hydroxylated ferrite.

[0076] (3) Weigh 2.0g of hydroxylated ferrite and 1.1g of ammonium persulfate and add them to 50ml of 1mol / L hydrochloric acid solution. Sonicate to obtain a suspension. Dissolve 0.4g of aniline in 50ml of dichloromethane solution to obtain an organic phase. Slowly inject the suspension onto the surface of the organic phase with a dropper and allow it to separate into layers. After standing at 25℃ for 12h, centrifuge, wash, and dry at 60℃ to obtain sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material.

[0077] Example 9

[0078] A method for preparing a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material includes the following steps:

[0079] (1) Preparation of NiZn-LDH precursor, a hydrotalcite-like material: Weigh 8.0g of ferric nitrate nonahydrate, 9.3g of ferrous sulfate heptahydrate, 3.9g of nickel nitrate hexahydrate, and 4g of zinc nitrate hexahydrate and add them to 100ml of deionized water and stir until homogeneous to obtain solution A. Weigh 7.4g of sodium carbonate and 6g of sodium hydroxide and dissolve them in 100ml of deionized water to obtain solution B. Add solution B dropwise to solution A and stir until the pH reaches 8. Let it stand at 50℃ for 10h to crystallize and obtain the product. Wash the product three times alternately with deionized water and anhydrous ethanol and dry it in a vacuum drying oven at 60℃ for 8h to obtain the NiZn-LDH precursor, a hydrotalcite-like material.

[0080] (2) The hydrotalcite-like material NiZn-LDH precursor was spread in a quartz boat and heated in a muffle furnace at a rate of 5℃ / min. It was calcined at 900℃ for 2h to obtain sheet-like nickel-zinc ferrite. The sheet-like nickel-zinc ferrite was then added to 100ml of anhydrous ethanol and ultrasonically dispersed. After adjusting the pH to 5 by adding concentrated hydrochloric acid, it was dried to obtain hydroxylated ferrite.

[0081] (3) Weigh 2.0g of hydroxylated ferrite and 2.7g of ammonium persulfate and add them to 50ml of 1mol / L hydrochloric acid solution. Sonicate to obtain a suspension. Dissolve 1g of aniline in 50ml of dichloromethane solution to obtain an organic phase. Slowly inject the suspension onto the surface of the organic phase with a dropper and allow it to separate into layers. After standing at 5℃ for 12h, centrifuge, wash, and dry at 60℃ to obtain sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material.

[0082] Example 10

[0083] A method for preparing a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material includes the following steps:

[0084] (1) Preparation of NiZn-LDH precursor, a hydrotalcite-like material: Weigh 8.0g of ferric nitrate nonahydrate, 9.3g of ferrous sulfate heptahydrate, 3.9g of nickel nitrate hexahydrate, and 4g of zinc nitrate hexahydrate and add them to 100ml of deionized water and stir until homogeneous to obtain solution A. Weigh 7.4g of sodium carbonate and 6g of sodium hydroxide and dissolve them in 100ml of deionized water to obtain solution B. Add solution B dropwise to solution A and stir until the pH reaches 8. Let it stand at 50℃ for 10h to crystallize and obtain the product. Wash the product three times alternately with deionized water and anhydrous ethanol and dry it in a vacuum drying oven at 60℃ for 8h to obtain the NiZn-LDH precursor, a hydrotalcite-like material.

[0085] (2) The hydrotalcite-like material NiZn-LDH precursor was spread in a quartz boat and heated in a muffle furnace at a rate of 5℃ / min. It was calcined at 900℃ for 2h to obtain sheet-like nickel-zinc ferrite. The sheet-like nickel-zinc ferrite was then added to 100ml of anhydrous ethanol and ultrasonically dispersed. After adjusting the pH to 5 by adding concentrated hydrochloric acid, it was dried to obtain hydroxylated ferrite.

[0086] (3) Weigh 2.0g of hydroxylated ferrite and 5.4g of ammonium persulfate and add them to 50ml of 1mol / L hydrochloric acid solution. Sonicate to obtain a suspension. Dissolve 2g of aniline in 50ml of dichloromethane solution to obtain an organic phase. Slowly inject the suspension onto the surface of the organic phase with a dropper and allow it to separate into layers. After standing at 5℃ for 12h, centrifuge, wash, and dry at 60℃ to obtain sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material.

[0087] Test methods and results

[0088] Figure 1 The X-ray diffraction (XRD) pattern of the sheet-like nickel-zinc ferrite prepared in Example 3 is shown below. Figure 2 The XRD pattern of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 is shown below. Figures 1-2 It can be seen that the 2θ angles corresponding to each diffraction peak of the sheet nickel-zinc ferrite and the sheet nickel-zinc ferrite / polyaniline composite material did not change, indicating that the original structural morphology of nickel-zinc ferrite was preserved during the preparation of the sheet nickel-zinc ferrite / polyaniline composite material from the sheet nickel-zinc ferrite.

[0089] Figure 3 This is a SEM image of the sheet-like nickel-zinc ferrite prepared in Example 3 of the present invention. Figure 4 This is a SEM image of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of the present invention. Figures 3-4It can be seen that the sheet-like nickel-zinc ferrite has a stacked sheet structure, and the sheet-like nickel-zinc ferrite / polyaniline composite material has a sheet structure with a coral-like rough, irregular and fine structure.

[0090] Figure 5 This is a reflection loss curve of the sheet-like nickel-zinc ferrite prepared in Example 3 of the present invention. Figure 6 This is a reflection loss curve of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of the present invention. Figures 5-6 It can be seen that the effective absorption band of the sheet-like nickel-zinc ferrite is relatively narrow, mainly concentrated in the low-frequency region of 6-9 GHz, with poor high-frequency absorption. However, after in-situ polymerization and growth of polyaniline, the composite material exhibits good absorption performance. With a thickness of only 2.5 mm, the maximum reflection loss of electromagnetic waves is close to -35 dB, the effective absorption band covers the entire X-band, and the absorption peak shifts to lower frequencies with increasing thickness, showing good performance tunability.

[0091] Figure 7 This is a graph showing the real part of the complex dielectric constant of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of this invention. Figure 8 The image shows the imaginary part of the complex dielectric constant of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of this invention. Figure 9 The graph shows the real part of the complex permeability of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of this invention. Figure 10 The image shows the imaginary part curve of the complex permeability of the sheet-like nickel-zinc ferrite / polyaniline composite material prepared in Example 8 of this invention. Figures 7-10 It can be seen that the addition of polyaniline did not affect the complex permeability of the sheet nickel-zinc ferrite, and the imaginary part of the magnetic loss still decreased with increasing frequency. The composite material has a high real and imaginary part of the complex dielectric constant due to the presence of conductive polymer, indicating that polyaniline grows well on the surface of the sheet nickel-zinc ferrite and significantly improves the high-frequency absorption performance and dielectric loss performance of the composite material.

[0092] In summary, the sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material prepared by the method provided in this invention retains the original sheet-like morphology of nickel-zinc ferrite while introducing coral-like polyaniline. This results in a surface of the composite material with both rough, irregular, and fine structures, improving impedance matching and enhancing interfacial polarization, thereby enhancing microwave absorption capability. Simultaneously, the growth of polyaniline between the sheets forms a sandwich structure, extending the propagation path of electromagnetic waves under conditions of both electrical and magnetic losses, which is beneficial for electromagnetic wave energy consumption. Compared with traditional ferrite microwave absorbing materials, this sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material has better microwave absorption performance, a wider absorption bandwidth, a smaller matching thickness, and a lower density.

[0093] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A method for preparing a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material, characterized in that, Includes the following steps: S1. Dissolve the metal salt in deionized water and stir to obtain solution A. Then dissolve sodium carbonate and sodium hydroxide in deionized water and stir to obtain solution B. S2. Add solution B dropwise to solution A, adjust the pH, allow to stand and crystallize to obtain the product, centrifuge, wash and dry the product to obtain the hydrotalcite-like material NiZn-LDH precursor; S3. The precursor is calcined at high temperature in a muffle furnace to obtain sheet-like nickel-zinc ferrite. The sheet-like nickel-zinc ferrite is then added to a mixed solution of hydrochloric acid and ethanol, the pH is adjusted, and the mixture is dried to obtain hydroxylated ferrite. S4. The hydroxylated ferrite is ultrasonically dispersed in a hydrochloric acid solution of ammonium persulfate to obtain a dispersion. The dispersion is then added dropwise to a dichloromethane solution of aniline. The mixture is kept at a constant temperature and allowed to react for a period of time. After centrifugation, washing, and drying, a sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material is obtained. In step S4, the mass ratio of the hydroxylated ferrite to aniline is (1:9) to (9:1), and the molar ratio of aniline to ammonium persulfate is (2:1) to (1:2).

2. The preparation method of the sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material as described in claim 1, characterized in that, In step S1, the metal salt is ferric nitrate nonahydrate, ferrous sulfate heptahydrate, nickel nitrate hexahydrate, or zinc nitrate hexahydrate.

3. The preparation method of the sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material as described in claim 2, characterized in that, The molar ratio of ferric nitrate nonahydrate, ferrous sulfate heptahydrate, nickel nitrate hexahydrate, and zinc nitrate hexahydrate is (2~4):(4~6):(1~3):(1~3).

4. The preparation method of the sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material as described in claim 1, characterized in that, In step S2, the pH is adjusted to 5-10, and the static crystallization time is 2-6 hours.

5. The method for preparing the sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material as described in claim 1, characterized in that, In step S2, the drying temperature is 50~100℃, and the drying time is 6~12h.

6. The method for preparing the sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material as described in claim 1, characterized in that, In step S3, the high-temperature calcination temperature is 600~1000℃, the high-temperature calcination time is 1~4h, and the pH is adjusted to 4~7.

7. The method for preparing the sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material as described in claim 1, characterized in that, In step S4, the concentration of the hydrochloric acid solution is 0.5~2 mol / L, the reaction time is 6~16 h, and the reaction temperature is 0~25℃.

8. A sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material prepared by the preparation method of the sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material according to any one of claims 1 to 7.

9. The application of the sheet-like nickel-zinc ferrite / polyaniline composite microwave absorbing material as described in claim 8 in the preparation of composite microwave absorbing materials.

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