A layered double magnetic metal hydroxide-derived magnetic metal@carbon composite wave-absorbing material and a preparation method thereof

Abstract

The application discloses a layered double magnetic metal hydroxide-derived magnetic metal-carbon composite wave-absorbing material and a preparation method thereof. The composite wave-absorbing material takes a layered double magnetic metal hydroxide (LDH) as a precursor, and a magnetic metal-carbon composite wave-absorbing material with a multi-dimensional, multi-level and porous structure is synthesized through subsequent heat treatment. The preparation method is simple in process and low in cost, and can realize large-scale industrial production. The prepared composite wave-absorbing material is small in density, thin in thickness, wide in effective absorption frequency band and strong in reflection loss.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic wave absorbing materials, in particular to a layered double magnetic metal hydroxide derived magnetic metal@carbon composite wave-absorbing material and a preparation method thereof. BACKGROUND

[0002] With the development of wireless technology and information industry, electronic products have been widely used, which also brings a series of electromagnetic radiation problems, which has a great impact on people's production and life. With the development of electronic technology towards miniaturization, integration and high frequency, this kind of problem is becoming more and more prominent. Therefore, eliminating electromagnetic interference, avoiding electromagnetic information leakage and reducing electromagnetic radiation pollution have become the key problems that need to be solved urgently in today's society.

[0003] As a new type of material with high specific surface area and rich internal interface, layered double magnetic metal hydroxide (LDH) can be combined with the booming material technology to design and prepare a variety of lightweight and efficient wave-absorbing materials. LDH as a wave-absorbing material has the following three advantages: first, the preparation method is simple and economical, without complex experimental process; second, the microstructure is controllable. It is easy to form nanosheet, nanowire, ultrathin structure and hollow structure; third, the components are diverse. However, in the LDH precursor, only organic ligand and metal cation are combined, and the complex has no magnetism. Through structure design and composite material modification methods, LDH derivatives with unique electromagnetic properties can be obtained. In particular, by introducing a carbon source during the synthesis of LDH and through appropriate heat treatment, a magnetic metal carbon composite material that retains the micro-morphology characteristics of the precursor can be obtained, which has both magnetic loss and dielectric loss, and is an ideal wave-absorbing material. SUMMARY

[0004] The purpose of the present application is to provide a layered double magnetic metal hydroxide derived magnetic metal@carbon composite wave-absorbing material and a preparation method thereof, i.e. using layered double magnetic metal hydroxide (LDH) as a precursor to synthesize a magnetic metal carbon composite wave-absorbing material with multi-dimensional, multi-level and porous structure, so as to reduce the density of the wave-absorbing material, realize multiple reflection and absorption of electromagnetic waves, and improve the wave-absorbing performance. The preparation process of the present application is simple, low in cost, and can realize large-scale industrial production. The wave-absorbing material prepared has small density, thin thickness, wide effective absorption frequency band and strong reflection loss.

[0005] The technical scheme for achieving the purpose of the present application is as follows:

[0006] A preparation method of a layered double magnetic metal hydroxide derived magnetic metal@carbon composite wave-absorbing material, comprising the following steps:

[0007] 1) Preparation of layered double magnetic metal hydroxide:

[0008] The magnetic metal source, urea and glucose are sequentially added into deionized water to mix uniformly, the obtained mixed solution is transferred into a reaction kettle, hydrothermal reaction is carried out at 160-200 DEG C for 6-24 h, then cooled to room temperature, the reaction product is suction filtered to obtain dark brown precipitate, the dark brown precipitate is washed with deionized water and anhydrous ethanol and dried to prepare a layered double magnetic metal hydroxide precursor; wherein the substance amount ratio of the magnetic metal source, urea and glucose is (2-6):(6-10):(1-4).

[0009] 2) Preparation of the magnetic metal@carbon composite wave-absorbing material:

[0010] The layered double magnetic metal hydroxide precursor prepared in step 1) is placed in a tube furnace, a protective atmosphere Ar is introduced, the tube furnace is heated to 500-900 DEG C at a rate of 1-10 DEG C / min, and calcination is carried out for 1-4 h to prepare a layered double magnetic metal hydroxide derived magnetic metal@carbon composite wave-absorbing material.

[0011] In step 1), the magnetic metal source is any two of a divalent nickel ion compound, a trivalent iron ion compound and a divalent cobalt ion compound.

[0012] The divalent nickel ion compound is any one of nickel nitrate, nickel chloride and nickel sulfate.

[0013] The trivalent iron ion compound is any one of iron nitrate, iron chloride and iron sulfate.

[0014] The divalent cobalt ion compound is any one of cobalt nitrate, cobalt chloride and cobalt sulfate.

[0015] In step 1), the washing is carried out for 3-6 times.

[0016] In step 1), the drying is carried out at a temperature of 60-90 DEG C for 12-24 h.

[0017] The layered double magnetic metal hydroxide derived magnetic metal@carbon composite wave-absorbing material and the preparation method thereof have the following advantages compared with the prior art.

[0018] 1) Compared with the prior art, the three-dimensional flower-like structure magnetic metal carbon composite wave-absorbing material synthesized by using the double magnetic metal hydroxide as a precursor has small density, large specific surface area, rich hollow structure, various structures and various compositions, the balance between dielectric loss and magnetic loss can be realized by adjusting the ratio of the magnetic metal source and the carbon source, good impedance matching characteristics are obtained, and thus the material has a wide effective wave-absorbing frequency band and strong reflection loss.

[0019] 2、The magnetic metal-carbon composite wave-absorbing material prepared by the application has a special three-dimensional flower ball structure, and the three-dimensional flower ball structure and the rich pore structure can not only reduce the weight and density, but also can realize multiple reflection and absorption of incident electromagnetic waves.

[0020] 3、The magnetic metal-carbon composite wave-absorbing material prepared by the application has excellent wave-absorbing performance, and the special three-dimensional multi-level structure causes the electromagnetic wave multiple reflection and absorption mechanism, the interface polarization effect, the natural resonance and exchange resonance generated by the magnetic alloy, and the electric conduction loss and dielectric loss generated by the carbon material, wherein the widest effective wave-absorbing frequency band of the FeNi@C composite wave-absorbing material is 4.6 GHz, and the strongest reflection loss is-35.4 dB. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is an XRD graph of the FeNi hydroxide precursor in the implementation case 1.

[0022] Figure 2 It is an XRD graph of the FeNi@C composite wave-absorbing material in the implementation case 1.

[0023] Figure 3 It is a Raman graph of the FeNi@C composite wave-absorbing material in the implementation case 1.

[0024] Figure 4 It is an SEM graph of the FeNi@C composite wave-absorbing material in the implementation case 1.

[0025] Figure 5 It is a reflection loss graph of the FeNi@C composite wave-absorbing material in the implementation case 1.

[0026] Figure 6 It is an SEM graph of the FeNi@C composite wave-absorbing material in the implementation case 2.

[0027] Figure 7 It is a reflection loss graph of the FeNi@C composite wave-absorbing material in the implementation case 2.

[0028] Figure 8 It is an SEM graph of the FeCo hydroxide in the implementation case 3.

[0029] Figure 9 It is an SEM graph of the NiCo hydroxide in the implementation case 4. DETAILED DESCRIPTION

[0030] The content of the application is further described below in combination with the drawings and examples, but is not limited to the application.

[0031] Example 1:

[0032] A preparation method of a layered double magnetic metal hydroxide derived magnetic metal@carbon composite wave-absorbing material, comprising the following steps:

[0033] 1) 0.6058g Fe (NO3)3·9H2O, 0.8724g Ni (NO3)2·6H2O, 0.4830g CH4N2O and 0.54g C6H 12 O6 were sequentially dissolved in 50ml deionized water, and after being uniformly mixed by magnetic stirring for 30min, the mixed solution was transferred into a 100ml high-pressure reaction kettle, and after hydrothermal reaction at 180℃ for 12h, the reaction product was vacuum filtered to obtain dark brown precipitate; the dark brown precipitate was washed with deionized water for three times and rinsed with anhydrous ethanol for two times, and then the precipitate was placed in an oven for drying at 60℃ for 12h to obtain FeNi hydroxide (FeNi-LDH) precursor;

[0034] 2) The FeNi-LDH precursor prepared in step 1) was placed in a tube furnace, a protective atmosphere Ar was introduced, and sintering was carried out at 700℃ for 2h to finally obtain three-dimensional flower ball-shaped FeNi@C composite wave-absorbing material.

[0035] Example 2:

[0036] A preparation method of a layered double magnetic metal hydroxide derived magnetic metal@carbon composite wave-absorbing material, comprising the following steps:

[0037] 1) 0.6058g Fe (NO3)3·9H2O, 0.8724g Ni (NO3)2·6H2O, 0.4830g CH4N2O and 0.54g C6H 12 O6 were sequentially dissolved in 50ml deionized water, and after being uniformly mixed by magnetic stirring for 30min, the mixed solution was transferred into a 100ml high-pressure reaction kettle, and after hydrothermal reaction at 180℃ for 12h, the reaction product was vacuum filtered to obtain dark brown precipitate; the dark brown precipitate was washed with deionized water for three times and rinsed with anhydrous ethanol for two times, and then the precipitate was placed in an oven for drying at 60℃ for 12h to obtain FeNi hydroxide (FeNi-LDH) precursor;

[0038] 2) The FeNi-LDH precursor prepared in step 1) was placed in a tube furnace, a protective atmosphere Ar was introduced, and sintering was carried out at 700℃ for 2h to finally obtain three-dimensional flower ball-shaped FeNi@C composite wave-absorbing material.

[0039] Example 3:

[0040] A preparation method of a layered double magnetic metal hydroxide derived magnetic metal@carbon composite wave-absorbing material, comprising the following steps:

[0041] 1) Take 0.6058g Fe (NO3)3·9H2O, 0.8730g Co (NO3)2·6H2O, 0.4830g CH4N2O and 0.54g C6H 12 O6 are sequentially dissolved in 50ml deionized water, and after being mixed uniformly by magnetic stirring for 30min, the mixed solution is transferred to a 100ml high-pressure reaction kettle, and after hydrothermal reaction at 180℃ for 12h, the reaction product is vacuum filtered to obtain dark brown precipitate, the dark brown precipitate is washed with deionized water three times and washed with anhydrous ethanol twice, and then the precipitate is placed in an oven and dried at 60℃ for 12h to obtain a FeCo hydroxide (FeCo-LDH) precursor;

[0042] 2) The FeCo-LDH precursor prepared in step 1) is placed in a tube furnace, Ar protection atmosphere is introduced, and sintering is carried out at 700℃ for 2h, and finally a three-dimensional flower ball-shaped FeNi@C composite wave-absorbing material is obtained.

[0043] Example 4:

[0044] A preparation method of a layered double magnetic metal hydroxide-derived magnetic metal@carbon composite wave-absorbing material, comprising the following steps:

[0045] 1) Take 0.8724g Ni (NO3)2·6H2O, 0.4365g Co (NO3)2·6H2O, 0.4830g CH4N2O and 0.54g C6H 12 O6 are sequentially dissolved in 50ml deionized water, and after being mixed uniformly by magnetic stirring for 30min, the mixed solution is transferred to a 100ml high-pressure reaction kettle, and after hydrothermal reaction at 180℃ for 12h, the reaction product is vacuum filtered to obtain dark brown precipitate, the dark brown precipitate is washed with deionized water three times and washed with anhydrous ethanol twice, and then the precipitate is placed in an oven and dried at 60℃ for 12h to obtain a FeCo hydroxide (FeCo-LDH) precursor;

[0046] 2) The FeCo-LDH precursor prepared in step 1) is placed in a tube furnace, H2 / Ar mixed gas is introduced, and sintering is carried out at 700℃ for 2h, and finally a three-dimensional flower ball-shaped FeNi@C composite wave-absorbing material is obtained.

[0047] The FeNi-LDH precursor prepared in Example 1 is subjected to XRD test, and the test result is as shown in Figure 1as shown in FIG. 4, wherein 2θ = 11.5°, 23.2°, 34.5°, 39.0° and 60.2° correspond to the (003), (006), (012), (015) and (110) crystal planes of nickel-iron hydroxide (ICDD.00-051-0463), respectively, indicating that the FeNi-LDH precursor was successfully synthesized.

[0048] The FeNi@C composite wave-absorbing material prepared in Example 1 was subjected to XRD testing, and the testing results are shown in FIG. 5. Figure 2 as shown in FIG. 5, wherein 2θ = 44.2°, 51.5° and 75.8° correspond to the (111), (200) and (220) crystal planes of FeNi3 (ICDD.01-088-1715), respectively, indicating that the FeNi alloy was successfully synthesized.

[0049] The FeNi@C composite wave-absorbing material prepared in Example 1 was subjected to Raman testing, and the testing results are shown in FIG. 6. Figure 3 as shown in FIG. 6, 1350 and 1575 cm-1 correspond to the D peak and G peak of the carbon material, respectively, indicating that the glucose was converted into carbon after high-temperature pyrolysis. -1

[0050] The FeNi@C composite wave-absorbing material prepared in Example 1 was subjected to SEM testing, and the testing results are shown in FIG. 7. Figure 4 as shown in FIG. 7, it can be clearly seen from the figure that the FeNi@C composite wave-absorbing material is a three-dimensional flower ball structure. This special structure not only reduces the mass density of the wave-absorbing agent, but also prolongs the attenuation path of the electromagnetic wave.

[0051] The FeNi@C composite wave-absorbing material prepared in Example 1 was subjected to wave-absorbing performance testing, and the reflectance loss of the absorbent at 1-5 mm is shown in FIG. 8. Figure 5 as shown in FIG. 8, the FeNi@C composite wave-absorbing material can achieve a reflectance loss of -30.4 dB at a thickness of 1.2 mm, and has an effective wave-absorbing bandwidth of 4.6 GHz at a thickness of 1.4 mm. The excellent wave-absorbing performance is related to the structure and composition. First, the special three-dimensional flower ball structure can reduce the density of the wave-absorbing agent and prolong the attenuation path of the electromagnetic wave. Second, the magnetic loss mainly caused by natural resonance and exchange resonance of the FeNi magnetic metal and the dielectric loss and electric conduction loss introduced by the carbon material. Finally, the carbon-coated magnetic nanoparticles form a large number of heterogeneous interfaces, which produce interface polarization effect and enhance the dielectric loss ability of the wave-absorbing agent.

[0052] The FeNi@C composite wave-absorbing material prepared in Example 2 was subjected to SEM testing, and the testing results are shown in FIG. 9. Figure 6 as shown in FIG. 9, it can be seen from the figure that the sheet-like structure on the three-dimensional flower ball collapses, which is not conducive to the multiple reflection and absorption of the electromagnetic wave.​

[0053] The FeNi@C composite wave-absorbing material prepared in Example 2 was subjected to wave-absorbing performance test, and the test result is shown in Figure 7 The maximum reflection loss value is only 15.7 dB, and the widest effective wave-absorbing bandwidth is 4.0 GHz. The decline in wave-absorbing performance is related to the structure collapse and the increase in conductivity.

[0054] The FeCo-LDH precursor prepared in Example 3 was subjected to SEM test, and the test result is shown in Figure 8 The FeCo-LDH precursor is a three-dimensional flower ball structure.

[0055] The NiCo-LDH precursor prepared in Example 4 was subjected to SEM test, and the test result is shown in Figure 9 The NiCo-LDH precursor is a three-dimensional flower ball structure.

Claims

1. A method for preparing a layered dual-magnetic metal hydroxide-derived magnetic metal@carbon composite microwave absorbing material, characterized in that, Includes the following steps: 1) Take 0.6058g Fe(NO3)3·9H2O, 0.8724g Ni(NO3)2·6H2O, 0.4830g CH4N2O and 0.54g C6H in the following mass ratio. 12 O6 was dissolved in deionized water and stirred until homogeneous. The mixture was then transferred to a high-pressure reactor and subjected to hydrothermal reaction at 160-200℃ for 6-24 hours. The reaction product was then vacuum filtered to obtain a dark brown precipitate. The dark brown precipitate was washed with deionized water and rinsed with anhydrous ethanol. After drying, the FeNi hydroxide (FeNi-LDH) precursor was obtained. 2) The FeNi-LDH precursor obtained in step 1) was placed in a tube furnace, and a protective atmosphere of Ar was introduced. It was sintered at 700℃ for 2 hours to finally obtain a three-dimensional flower-shaped FeNi@C composite microwave absorbing material. Carbon materials encapsulate magnetic alloy nanoparticles, forming a heterogeneous interface.

2. A method for preparing a layered dual-magnetic metal hydroxide-derived magnetic metal@carbon composite microwave absorbing material, characterized in that, Includes the following steps: 1) Take 0.6058g Fe(NO3)3·9H2O, 0.8730g Co(NO3)2·6H2O, 0.4830g CH4N2O and 0.54g C6H in a mass ratio of 12 O6 was dissolved in deionized water and stirred until homogeneous. The mixture was then transferred to a high-pressure reactor and subjected to hydrothermal reaction at 160-200℃ for 6-24 hours. The reaction product was then vacuum filtered to obtain a dark brown precipitate. The dark brown precipitate was washed with deionized water and rinsed with anhydrous ethanol. After drying, the FeCo hydroxide (FeCo-LDH) precursor was obtained. 2) The FeCo-LDH precursor obtained in step 1) was placed in a tube furnace, and a protective atmosphere of Ar was introduced. The furnace was sintered at 700℃ for 2 hours to finally obtain a three-dimensional flower-shaped FeCo@C composite microwave absorbing material. Carbon materials encapsulate magnetic alloy nanoparticles, forming a heterogeneous interface.

3. A three-dimensional flower-shaped FeNi@C composite microwave absorbing material prepared by the preparation method described in claim 1.

4. A three-dimensional flower-shaped FeCo@C composite microwave absorbing material prepared by the preparation method described in claim 2.

5. The application of the three-dimensional flower-shaped FeNi@C composite microwave absorbing material as described in claim 1 in the field of microwave absorbing materials.

6. The application of the three-dimensional flower-shaped FeCo@C composite microwave absorbing material as described in claim 2 in the field of microwave absorbing materials.

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