Lightweight porous nickel ferrite composite electromagnetic absorbing material and preparation method thereof

Abstract

The invention relates to a lightweight porous nickel ferrite composite electromagnetic absorbing material and a preparation method thereof, and belongs to the field of electromagnetic wave absorbing materials, and the lightweight porous nickel ferrite composite electromagnetic absorbing material is a porous electromagnetic absorbing material prepared by high-temperature annealing of a mixture containing ferric salt, nickel salt, an acetic acid solution and chitosan. The lightweight and porous nickel ferrite composite electromagnetic absorbing material has both lightweight and electromagnetic absorbing properties.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic wave absorption materials, and particularly to a lightweight and porous nickel ferrite composite electromagnetic absorption material and a preparation method thereof. Background Art

[0002] As an important part of the traditional wave absorption material system, the electromagnetic wave absorption mechanism and performance optimization of ferrite have attracted much attention. This type of composite metal oxide is composed of iron group ions, oxygen ions and other metal ions through specific coordination. As a typical magnetic wave absorption material (MAM), the wave absorption mechanism of ferrite has the characteristics of double loss synergy: the magnetic loss mechanism dominated by domain wall resonance and natural resonance undertakes the main attenuation function, while the dielectric loss caused by interface polarization and electron transition plays an auxiliary enhancement role. Thanks to its unique high-frequency magnetic response characteristics, ferrite can still maintain a high complex magnetic permeability in the high-frequency band (such as Ku band and above). This combination of electromagnetic characteristics not only effectively suppresses the skin effect, but also significantly improves the high-frequency impedance matching ability of the material.

[0003] However, ferrite wave absorption materials still face three common challenges: First, the wave absorption bandwidth is narrow, and it is difficult for the traditional dense structure to achieve broadband impedance matching; second, the mass density is large (the density of spinel nickel ferrite reaches 4.8 - 5.2 g / cm 3 ), and the high atomic weight transition metal elements limit the wave absorption efficiency per unit mass; third, the thermal stability is insufficient, and lattice distortion or magnetic property attenuation is likely to occur at high temperatures. Among them, the density problem is particularly prominent. In fields with urgent lightweight requirements such as aerospace and mobile equipment, the high-quality load of materials not only increases the system energy consumption, but also causes structural adaptability obstacles, and even affects the mobility and stealth performance of the equipment. Therefore, how to achieve the coordinated optimization of the reduction of ferrite density and electromagnetic performance on the premise of simplifying the process and reducing the cost has become an important research direction for ferrite wave absorption materials. Summary of the Invention

[0004] In view of one or more technical problems existing in the prior art, the present invention provides a lightweight and porous nickel ferrite composite electromagnetic absorption material and a preparation method thereof, and the electromagnetic absorption material can take into account lightweight and electromagnetic absorption performance.

[0005] In the first aspect of the present invention, there is provided a lightweight and porous nickel ferrite composite electromagnetic absorption material, and the lightweight and porous nickel ferrite composite electromagnetic absorption material is a porous electromagnetic absorption material prepared by subjecting a mixture containing iron salt, nickel salt, acetic acid solution and chitosan to high-temperature annealing.

[0006] Preferably, the density of the lightweight and porous nickel ferrite composite electromagnetic absorption material is less than 2.3 g / cm 3 .

[0007] Preferably, the molar ratio of the iron salt to the nickel salt is 2-5:5-8.

[0008] Preferably, the iron salt is iron(III) nitrate nonahydrate; and / or

[0009] the nickel salt is nickel(II) nitrate hexahydrate.

[0010] Preferably, the dosage ratio of the acetic acid solution to the iron salt is 0.06-0.15 g:1 mmol.

[0011] Preferably, the mass fraction of acetic acid in the acetic acid solution is 95%.

[0012] Preferably, the dosage ratio of chitosan to the iron salt is 0.1-0.25 g:1 mmol.

[0013] Preferably, the temperature of the high-temperature annealing is 400-500 °C, and the time is 1-2 h.

[0014] Preferably, the heating rate during the high-temperature annealing is 1-5 °C / min.

[0015] In a second aspect, the present invention provides a method for preparing the light and porous nickel ferrite composite electromagnetic absorption material described in the first aspect, and the preparation method includes:

[0016] Grind and mix an iron salt and a nickel salt to obtain a nickel-iron composite;

[0017] Grind and mix the nickel-iron composite, an acetic acid solution and chitosan to obtain a dough-like mixture;

[0018] Subject the dough-like mixture to high-temperature annealing to obtain a light and porous nickel ferrite composite electromagnetic absorption material.

[0019] The present invention has at least the following beneficial effects compared with the prior art:

[0020] Based on the three-dimensional network guiding effect of the chitosan template, and utilizing the gas release effect generated by the decomposition of chitosan and the organic-inorganic interface interaction, the present invention constructs a hierarchical porous structure, which helps to form a three-dimensional conductive network while reducing the material density, and improves the electromagnetic absorption performance of the material; by adding acetic acid to promote the hydrolysis of chitosan and optimizing the porous structure after high-temperature annealing, the impedance matching and attenuation characteristics of the material are further balanced, and the electromagnetic wave absorption ability of the material is optimized and improved. The light and porous nickel ferrite composite electromagnetic absorption material provided by the present invention can take into account both light weight and electromagnetic absorption performance.

[0021] The present invention adopts a green synthesis route. Only by performing conventional grinding and mixing of raw materials and high-temperature annealing can a lightweight and porous nickel ferrite composite electromagnetic absorption material be prepared. It has the advantages of simple preparation process, controllable process parameters, low cost, large-scale production feasibility, and the ability for industrial application. Brief Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is the SEM image of the lightweight and porous nickel ferrite composite electromagnetic absorption material provided in Embodiment 1 of the present invention;

[0024] Figure 2 It is the SEM image of the lightweight and porous nickel ferrite composite electromagnetic absorption material provided in Embodiment 2 of the present invention;

[0025] Figure 3 It is the SEM image of the lightweight and porous nickel ferrite composite electromagnetic absorption material provided in Embodiment 3 of the present invention;

[0026] Figure 4 It is the SEM image of the lightweight and porous nickel ferrite composite electromagnetic absorption material provided in Embodiment 4 of the present invention;

[0027] Figure 5 It is the XRD pattern of the lightweight and porous nickel ferrite composite electromagnetic absorption material provided in Embodiments 1 - 4 of the present invention;

[0028] Figure 6 It is the real part of the dielectric constant of the lightweight and porous nickel ferrite composite electromagnetic absorption material provided in Embodiments 1 - 4 of the present invention;

[0029] Figure 7 It is the imaginary part of the dielectric constant of the lightweight and porous nickel ferrite composite electromagnetic absorption material provided in Embodiments 1 - 4 of the present invention;

[0030] Figure 8 It is the real part of the magnetic permeability of the lightweight and porous nickel ferrite composite electromagnetic absorption material provided in Embodiments 1 - 4 of the present invention;

[0031] Figure 9 It is the imaginary part of the magnetic permeability of the lightweight and porous nickel ferrite composite electromagnetic absorption material provided in Embodiments 1 - 4 of the present invention;

[0032] Figure 10It is the electromagnetic loss performance diagram of the lightweight porous nickel ferrite composite electromagnetic absorption material provided in Embodiment 1 of the present invention;

[0033] Figure 11 It is the electromagnetic loss performance diagram of the lightweight porous nickel ferrite composite electromagnetic absorption material provided in Embodiment 2 of the present invention;

[0034] Figure 12 It is the electromagnetic loss performance diagram of the lightweight porous nickel ferrite composite electromagnetic absorption material provided in Embodiment 3 of the present invention;

[0035] Figure 13 It is the electromagnetic loss performance diagram of the lightweight porous nickel ferrite composite electromagnetic absorption material provided in Embodiment 4 of the present invention;

[0036] Figure 14 It is the SEM diagram of the electromagnetic absorption material provided in Comparative Example 1 of the present invention;

[0037] Figure 15 It is the SEM diagram of the electromagnetic absorption material provided in Comparative Example 2 of the present invention;

[0038] Figure 16 It is the SEM diagram of the electromagnetic absorption material provided in Comparative Example 3 of the present invention;

[0039] Figure 17 It is the SEM diagram of the electromagnetic absorption material provided in Comparative Example 4 of the present invention;

[0040] Figure 18 It is the SEM diagram of the electromagnetic absorption material provided in Comparative Example 5 of the present invention;

[0041] Figure 19 It is the SEM diagram of the electromagnetic absorption material provided in Comparative Example 6 of the present invention;

[0042] Figure 20 It is the SEM diagram of the electromagnetic absorption material provided in Comparative Example 7 of the present invention;

[0043] Figure 21 It is the SEM diagram of the electromagnetic absorption material provided in Comparative Example 8 of the present invention;

[0044] Figure 22 It is the SEM diagram of the electromagnetic absorption material provided in Comparative Example 9 of the present invention. Detailed implementation manners

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0046] In the first aspect, the present invention provides a lightweight and porous nickel ferrite composite electromagnetic absorption material, which is a porous electromagnetic absorption material prepared by high-temperature annealing of a mixture containing iron salt, nickel salt, acetic acid solution, and chitosan.

[0047] Based on the three-dimensional network guiding effect of the chitosan template, the present invention utilizes the gas release effect generated by the decomposition of chitosan and the organic-inorganic interface interaction to construct a hierarchical porous structure, which helps to form a three-dimensional conductive network while reducing the material density and improving the electromagnetic absorption performance of the material. By adding acetic acid to promote the hydrolysis of chitosan and optimize the porous structure after high-temperature annealing, the impedance matching and attenuation characteristics of the material are further balanced, realizing the optimized improvement of the electromagnetic wave absorption ability of the material. The lightweight and porous nickel ferrite composite electromagnetic absorption material provided by the present invention can take into account both lightweight and electromagnetic absorption performance.

[0048] In addition, the porous structure increases the reaction sites of the material and broadens the scope of composite application of the electromagnetic absorption material with other materials; it can be used as a functional additive in electromagnetic wave absorption coatings to achieve the purpose of electromagnetic stealth and protection.

[0049] According to some preferred embodiments, the density of the lightweight and porous nickel ferrite composite electromagnetic absorption material is less than 2.3 g / cm 3 . The lightweight and porous nickel ferrite composite electromagnetic absorption material provided by the present invention has a density reduction of at least 52.1% compared to the average level of the density of nickel ferrite (4.80 g / cm 3 ).

[0050] According to some preferred embodiments, the molar ratio of the iron salt to the nickel salt is 2-5:5-8. By controlling the molar ratio of nickel to iron in the lightweight and porous nickel ferrite composite electromagnetic absorption material, the present invention can regulate the electromagnetic parameters of the material and optimize the electromagnetic wave absorption performance to meet different requirements.

[0051] According to some preferred embodiments, the iron salt is ferric nitrate nonahydrate.

[0052] According to some preferred embodiments, the nickel salt is nickel nitrate hexahydrate.

[0053] According to some preferred embodiments, the dosage ratio of the acetic acid solution to the iron salt is 0.06 - 0.15 g: 1 mmol.

[0054] According to some preferred embodiments, the mass fraction of acetic acid in the acetic acid solution is 95%.

[0055] According to some preferred embodiments, the dosage ratio of the chitosan to the iron salt is 0.1 - 0.25 g: 1 mmol.

[0056] According to some preferred embodiments, the temperature of the high - temperature annealing is 400 - 500 °C (for example, it can be 400 °C, 420 °C, 450 °C, 480 °C or 500 °C), and the time is 1 - 2 h (for example, it can be 1 h, 1.5 h, 2 h, 2.5 h or 3 h).

[0057] By controlling the annealing temperature within the above - mentioned range, the obtained lightweight and porous nickel ferrite composite electromagnetic absorption material of the present invention has more pores, a more complex porous structure and more excellent electromagnetic absorption performance. If the temperature is too high, it will cause the overall pores of the lightweight and porous nickel ferrite composite electromagnetic absorption material to become fewer, the density to increase, and the absorption performance to decline. By precisely controlling the annealing temperature and process conditions, the present invention can achieve precise regulation of the electromagnetic absorption performance of the material, thereby improving the wave - absorbing efficiency of the material, especially showing excellent wave - absorbing effects in the medium - high frequency band.

[0058] By precisely regulating the molar ratio of the iron salt and the nickel salt and the annealing temperature, the present invention regulates the internal structure of the lightweight and porous nickel ferrite composite electromagnetic absorption material, thereby optimizing the overall wave - absorbing effect.

[0059] According to some preferred embodiments, the heating rate during the high - temperature annealing is 1 - 5 °C / min (for example, it can be 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min or 5 °C / min).

[0060] In a second aspect, the present invention provides a preparation method of the lightweight and porous nickel ferrite composite electromagnetic absorption material as described in the first aspect, and the preparation method includes:

[0061] Grind and mix the iron salt and the nickel salt to obtain a nickel - iron complex;

[0062] Grind and mix the nickel - iron complex, the acetic acid solution and the chitosan to obtain a dough - like mixture;

[0063] Perform high - temperature annealing on the dough - like mixture to obtain a lightweight and porous nickel ferrite composite electromagnetic absorption material.

[0064] The present invention adopts a green synthesis route, and only needs to grind and mix the raw materials and anneal them at high temperature to obtain a lightweight and porous nickel ferrite composite electromagnetic absorption material, which has the advantages of simple preparation process, controllable process parameters, low cost, large-scale production, and industrial application capability. High-temperature annealing can be achieved by conventional high-temperature processing equipment (such as a tube furnace, a muffle furnace, etc.).

[0065] To ensure that the iron salt and nickel salt are fully ground, if the purchased iron salt and nickel salt are large in volume, the iron salt and nickel salt can be fully ground separately first, and then mixed and ground. To ensure that each substance is fully ground and mixed, when grinding and mixing the nickel-iron complex, acetic acid solution and chitosan, add acetic acid first and then chitosan. If chitosan is added first, incompletely ground nickel salt particles will be seen in the subsequent dough-like mixture.

[0066] In order to more clearly illustrate the technical solutions and advantages of the present invention, the present invention is further described below in conjunction with the examples. The present invention does not specifically limit the sources of the reagents used in the examples and comparative examples, and the reagents can be directly purchased or synthesized by themselves.

[0067] Example 1

[0068] 5mmol of nickel nitrate hexahydrate is put into a mortar and ground thoroughly until the whole solid is uniform in color; 5mmol of ferric nitrate nonahydrate is put into a mortar and ground thoroughly until the whole solid is uniform in color; the ground nickel nitrate hexahydrate and ferric nitrate nonahydrate are put into the same mortar and mixed and ground thoroughly until the whole solid is uniform in color. 0.3g of 95% acetic acid solution is added to the mixed solid and ground continuously until the viscosity does not change, and 0.5g of chitosan is added and ground continuously until a dough-like mixture with uniform color is obtained.

[0069] The prepared dough-like mixture is placed in a high-temperature resistant container, and placed in a muffle furnace and heated to 400° C. and kept warm for 2 hours. After natural cooling, a lightweight and porous nickel ferrite composite electromagnetic absorption material is obtained.

[0070] Example 2

[0071] The method is basically the same as Example 1, except that the amount of nickel nitrate hexahydrate is 6 mmol, and the amount of ferric nitrate nonahydrate is 4 mmol.

[0072] Example 3

[0073] The method is basically the same as Example 1, except that the amount of nickel nitrate hexahydrate is 7 mmol, and the amount of ferric nitrate nonahydrate is 3 mmol.

[0074] Example 4

[0075] Basically the same as Example 1, except that: the dosage of nickel nitrate hexahydrate is 8 mmol, and the dosage of iron nitrate nonahydrate is 2 mmol.

[0076] The present invention tested the SEM images of the light porous nickel ferrite composite electromagnetic absorption materials of Examples 1 - 4. From Figure 1 it can be seen that the light porous nickel ferrite composite electromagnetic absorption material prepared in Example 1 has an obvious porous structure. The size of the pores is mainly in the micron scale, there are certain voids between the main structures, and the overall structure is a layered structure. From Figure 2 it can be seen that the light porous nickel ferrite composite electromagnetic absorption material prepared in Example 2 has micron-scale holes, the voids between the main structures increase, and the overall structure is looser. From Figure 3 it can be seen that the light porous nickel ferrite composite electromagnetic absorption material prepared in Example 3 has fewer tiny pores, and the main structure is a coral-like skeleton structure, which helps to form a conductive network. From Figure 4 it can be seen that compared with Example 3, the proportion of the coral-like skeleton in the main structure of the light porous nickel ferrite composite electromagnetic absorption material prepared in Example 4 decreases, and the overall voids also decrease, and some skeleton structures merge into large holes.

[0077] The present invention used a pycnometer to measure the densities of the light porous nickel ferrite composite electromagnetic absorption materials of Examples 1 - 4 by Archimedes' principle, which are 2.25 g / cm 3 , 1.92 g / cm 3 , 1.83 g / cm 3 , 1.87 g / cm 3 respectively.

[0078] The present invention conducted XRD tests on the light porous nickel ferrite composite electromagnetic absorption materials of Examples 1 - 4. From Figure 5 it can be seen that the peak changes of the nickel peak and the iron peak in the light porous nickel ferrite composite electromagnetic absorption material are the same as the change trend of the nickel-iron ratio of nickel ferrite, proving that its structural change is related to the elemental change.

[0079] The present invention tested the dielectric constants of the light porous nickel ferrite composite electromagnetic absorption materials of Examples 1 - 4. From Figure 6 and Figure 7 it can be seen that by adjusting the molar ratio of nickel salt and iron salt, the dielectric constant of the electromagnetic absorption material can be adjusted. As the molar proportion of nickel salt increases, the real part of the dielectric constant increases; as the molar proportion of nickel salt increases, the imaginary part of the dielectric constant shows a trend of decreasing, increasing, and then decreasing.

[0080] The present invention tested the magnetic properties of the light porous nickel ferrite composite electromagnetic absorption materials of Examples 1 - 4. From Figure 8 andFigure 9 It can be seen that the permeability of the electromagnetic absorption material can be regulated by adjusting the molar ratio of nickel salt and iron salt. As the molar proportion of nickel salt increases, the real part of the permeability shows a trend of first increasing and then decreasing; as the molar proportion of nickel salt increases, the imaginary part of the permeability also shows a trend of first increasing and then decreasing.

[0081] The present invention tested the electromagnetic loss performance diagrams of the lightweight porous nickel ferrite composite electromagnetic absorption materials (with a thickness of 5.0 mm) in Examples 1 - 4, as Figure 10 shown. For the lightweight porous nickel ferrite composite electromagnetic absorption material prepared in Example 1, the absorption frequency band with an electromagnetic loss below -5 dB is 11.4 - 15.4 GHz (the frequency band width is 4.0 GHz). As Figure 11 shown. For the lightweight porous nickel ferrite composite electromagnetic absorption material prepared in Example 2, the absorption frequency bands with an electromagnetic loss below -10 dB are 5.0 - 6.0 GHz and 16.9 - 18.0 GHz (the frequency band width is 2.1 GHz). As Figure 12 shown. For the lightweight porous nickel ferrite composite electromagnetic absorption material prepared in Example 3, the absorption frequency bands with an electromagnetic loss below -10 dB are 5.0 - 6.0 GHz and 16.2 - 18.0 GHz (the frequency band width is 2.8 GHz). As Figure 13 shown. For the lightweight porous nickel ferrite composite electromagnetic absorption material prepared in Example 4, the absorption frequency band with an electromagnetic loss below -10 dB is 16.4 - 18.0 GHz (the frequency band width is 1.6 GHz). It can be seen that the present invention can control the electromagnetic absorption performance of the obtained lightweight porous nickel ferrite composite electromagnetic absorption material by adjusting the molar ratio of nickel salt and iron salt.

[0082] Comparative Example 1

[0083] It is basically the same as Example 1, except that citric acid is used to replace acetic acid.

[0084] Comparative Example 2

[0085] It is basically the same as Example 2, except that citric acid is used to replace acetic acid.

[0086] Comparative Example 3

[0087] It is basically the same as Example 3, except that citric acid is used to replace acetic acid.

[0088] Comparative Example 4

[0089] It is basically the same as Example 4, except that citric acid is used to replace acetic acid.

[0090] The present invention shows the SEM diagrams of the electromagnetic absorption materials in Comparative Examples 1 - 4, as Figures 14 - 17As shown, the electromagnetic absorption materials prepared in Comparative Examples 1 - 4 are all in block shape, and the SEM images have poor clarity, indicating poor conductivity of the materials.

[0091] The present invention uses a pycnometer to measure the densities of the electromagnetic absorption materials prepared in Comparative Examples 1 - 4 by the Archimedes principle, which are 3.92 g / cm 3 , 3.58 g / cm 3 , 3.65 g / cm 3 , 3.77 g / cm 3 .

[0092] Comparative Example 5

[0093] is basically the same as Example 1, with the only difference being that glucose is used to replace chitosan.

[0094] The SEM image of the electromagnetic absorption material of this comparative example is as shown in Figure 18 . The electromagnetic absorption material is in block shape, and the SEM image has poor clarity, indicating poor conductivity of the material.

[0095] Comparative Example 6

[0096] is basically the same as Example 1, with the only difference being that the temperature of high - temperature annealing is 600 °C.

[0097] Comparative Example 7

[0098] is basically the same as Example 2, with the only difference being that the temperature of high - temperature annealing is 600 °C.

[0099] Comparative Example 8

[0100] is basically the same as Example 3, with the only difference being that the temperature of high - temperature annealing is 600 °C.

[0101] Comparative Example 9

[0102] is basically the same as Example 4, with the only difference being that the temperature of high - temperature annealing is 600 °C.

[0103] The SEM images of the electromagnetic absorption materials of Comparative Examples 6 - 9 of the present invention are as shown in Figure 19 . Compared with Example 1, the pores in the main structure of the electromagnetic absorption material prepared in Comparative Example 6 are reduced, and the whole shows a relatively dense layered structure. As shown in Figure 20 , compared with Example 2, the pores in the main structure of the electromagnetic absorption material prepared in Comparative Example 7 are reduced, and the whole shows a relatively dense layered structure. As shown in Figure 21 , compared with Example 3, the small holes in the electromagnetic absorption material prepared in Comparative Example 8 increase, the coral - like framework structure decreases, the gaps in the main structure decrease, and the whole structure becomes more compact. As shown in Figure 22As shown, compared with Example 4, the overall porosity of the electromagnetic absorption material prepared in Comparative Example 9 is less, but the clarity of the SEM image is worse, proving that the conductivity is worse.

[0104] The density of the electromagnetic absorption materials prepared in Comparative Examples 1-4 measured by the Archimedes principle using a pycnometer in the present invention is 3.32 g / cm 3 , 2.57 g / cm 3 , 2.13 g / cm 3 , 2.53 g / cm 3 .

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A lightweight and porous nickel ferrite composite electromagnetic absorption material, characterized in that, The lightweight porous nickel ferrite composite electromagnetic absorption material is a porous electromagnetic absorption material prepared by subjecting a mixture containing iron salt, nickel salt, acetic acid solution and chitosan to high-temperature annealing.

2. The lightweight porous nickel ferrite composite electromagnetic absorption material according to claim 1, characterized in that, The density of the light and porous nickel ferrite composite electromagnetic absorption material is less than 2.3 g / cm 3 .

3. The lightweight porous nickel ferrite composite electromagnetic absorption material according to claim 1, characterized in that, The molar ratio of the iron salt to the nickel salt is 2-5:5-8.

4. The lightweight porous nickel ferrite composite electromagnetic absorption material according to claim 1, characterized in that, The iron salt is ferric nitrate nonahydrate; and / or The nickel salt is nickel nitrate hexahydrate.

5. The light porous nickel ferrite composite electromagnetic absorption material according to claim 1, characterized in that The dosage ratio of the acetic acid solution to the iron salt is 0.06-0.15 g:1 mmol.

6. The lightweight porous nickel ferrite composite electromagnetic absorption material according to claim 1, wherein The mass fraction of acetic acid in the acetic acid solution is 95%.

7. The lightweight and porous nickel ferrite composite electromagnetic absorption material according to claim 1, wherein The dosage ratio of the chitosan to the iron salt is 0.1-0.25 g:1 mmol.

8. The lightweight porous nickel ferrite composite electromagnetic absorption material according to claim 1, characterized in that, The temperature of the high-temperature annealing is 400-500 °C, and the time is 1-2 h.

9. The light porous nickel ferrite composite electromagnetic absorption material according to claim 1, characterized in that, The heating rate during the high-temperature annealing process is 1-5 °C / min.

10. A method for preparing the lightweight porous nickel ferrite composite electromagnetic absorption material according to any one of claims 1-9, characterized in that, The preparation method includes: Grinding and mixing the iron salt and the nickel salt to obtain a nickel-iron complex; Grinding and mixing the nickel-iron complex, the acetic acid solution and the chitosan to obtain a dough-like mixture; Subjecting the dough-like mixture to high-temperature annealing to obtain a lightweight porous nickel ferrite composite electromagnetic absorption material.

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