High-performance wave-absorbing material Ni6W6C as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a high-performance wave-absorbing material Ni6W6C, which comprises the following steps: preparing a mixed solution A of sodium tungstate and nickel nitrate by taking deionized water as a solvent; dropwise adding ethanol and ethylene glycol into the mixed solution A, and stirring to obtain a precursor solution; transferring the precursor solution into a reaction kettle, and carrying out hydrothermal reaction at 180 DEG C for 16 hours; after the reaction is finished, centrifuging and washing to remove impurities, drying in a drying oven at 60 DEG C, mixing and grinding the dried hydrothermal product with C6H12O6 and Co2O3 in different mass ratios, and calcining in a tubular furnace in an argon environment to obtain the high-performance wave-absorbing material Ni6W6C. The high-performance wave-absorbing material prepared by the preparation method is green, environment-friendly and simple in synthesis method, the microstructure of the wave-absorbing material is a porous structure formed by agglomeration of nanoparticles on a carbon shell, and the wave-absorbing material Ni6W6C lays a foundation for application research in the field of electromagnetic wave absorption and has a good application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic wave absorption, and particularly relates to a high-performance wave-absorbing material Ni6W6C and its preparation method and application. Background Art

[0002] In recent years, due to its own thermal stability, unique three-dimensional pore structure and various metal species, the MOF structure has dielectric loss, magnetic loss and excellent impedance matching ability at the same time. Therefore, the MOF structure has become a hot topic explored by more and more researchers. However, the single metal species of single-metal MOF limits the introduction amount of magnetic substances, and it is difficult to solve the impedance matching problem. The multi-metal MOF structure can well overcome this problem. Whether it is the magnetic metal atoms before carbonization or the metal oxides obtained after carbonization, they can match the dielectric loss of carbon materials. Although significant progress has been made in this field, the existing wave-absorbing materials still face many challenges.

[0003] Wave-absorbing materials synthesized based on green and environmentally friendly natural materials have always been a hot research topic, but green and environmentally friendly materials with both high performance and simple synthesis steps still need to be developed. High-performance wave-absorbing materials are often accompanied by high costs and complex preparation processes, which limit their large-scale application. Secondly, the existing wave-absorbing materials are difficult to simultaneously meet the comprehensive performance requirements of "thin, light, wide, and strong". Especially when keeping the material thin and light, it faces great challenges to achieve strong absorption of electromagnetic waves in a wide frequency band. In addition, it is also an inevitable defect that many wave-absorbing materials are prone to oxidation, have poor stability, and high density. Environmental stability and durability are important factors in the practical application of wave-absorbing materials. Summary of the Invention

[0004] Aiming at the deficiencies of the existing wave-absorbing materials, the purpose of the present invention is to propose a high-performance wave-absorbing material Ni6W6C with green environmental protection and simple synthesis method, and its preparation method and application. The present invention uses glucose and MOF to prepare a composite material with strong wave-absorbing ability and low cost. Glucose is a green natural product sold on the market. Through a simple synthesis method of hydrothermal treatment and annealing, a MOF derivative with a carbon shell skeleton nanostructure is constructed. According to the results of transmission line theory analysis, the RL value of the Ni6W6C / Co2O3 material is -56.68 dB at 5.43 GHz and 4.76 mm. In addition, the effective absorption bandwidth EAB at 2.04 mm can reach 7.12 GHz. The composite structure of glucose and MOF derivative improves the impedance matching of the material, and a high-performance wave-absorbing material with green environmental protection and simple synthesis method is prepared. min Value is -56.68 dB. In addition, the effective absorption bandwidth EAB at 2.04 mm can reach 7.12 GHz. The composite structure of glucose and MOF derivative improves the impedance matching of the material, and a high-performance wave-absorbing material with green environmental protection and simple synthesis method is prepared.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions to achieve:

[0006] A preparation method of a high-performance wave-absorbing material Ni6W6C specifically includes the following steps:

[0007] Step 1: Using deionized water as a solvent, prepare sodium tungstate solution and nickel nitrate solution respectively, and then mix the sodium tungstate solution and nickel nitrate solution and stir evenly to obtain a mixed solution A;

[0008] Step 2: Dropwise add ethanol and ethylene glycol to the mixed solution A, and stir to obtain a precursor solution with alternating light green and white colors;

[0009] Step 3: Transfer the precursor solution to a reaction kettle lined with polytetrafluoroethylene, and then place the reaction kettle in an oven for hydrothermal experiments;

[0010] Step 4: After the reaction in Step 3 ends, take out the hydrothermal product, centrifuge and wash the hydrothermal product to remove impurities, dry the hydrothermal product after removing impurities in an oven, and mix and grind the dried hydrothermal product with C6H 12 O6 and Co2O3 with different mass ratios, and calcine the mixture in a tubular furnace under an argon atmosphere to obtain the high-performance wave-absorbing material Ni6W6C.

[0011] Further, in Step 1, the sodium tungstate solution and nickel nitrate solution are mixed according to a molar ratio of 1:1.

[0012] Further, in Step 1, the concentration of sodium tungstate in the mixed solution A is 0.4 mol / L, and the concentration of nickel nitrate is 0.4 mol / L.

[0013] Further, the conditions for the hydrothermal experiment in Step 3 are: hydrothermal time 16 h, hydrothermal temperature 180 °C.

[0014] Further, in Step 4, the drying temperature in the oven is 60 °C, and the drying time is 10 - 15 h.

[0015] Further, in Step 4, the dried hydrothermal product is mixed and ground with C6H 12 O6 and Co2O3 with different mass ratios for 0.5 h.

[0016] Further, in Step 4, the calcination temperature in the tubular furnace is 800 °C, and the calcination time is 2 h.

[0017] The microstructure of the high-performance wave-absorbing material Ni6W6C prepared according to the above preparation method of a high-performance wave-absorbing material Ni6W6C is a porous structure formed by nanoparticles agglomerating on a carbon shell.

[0018] Application of the high-performance wave-absorbing material Ni6W6C in electromagnetic wave absorption.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention selects environmentally friendly and low-cost glucose as the carbon skeleton, and constructs a nanostructure of carbon skeleton MOF derivatives through a hydrothermal method and an annealing method.

[0021] 2. The present invention also adds Co2O3 powder in different proportions during annealing, and utilizes the interaction between the two magnetic metals Co and Ni to further improve the microwave absorption performance of the material.

[0022] 3. During the synthesis process of this microwave absorption material, not only are the raw materials green and environmentally friendly, but the preparation process is also simple. At the same time, the RL value of the material prepared in Example 2 is -56.68 dB at 5.43 GHz and 4.76 mm; the effective absorption bandwidth EAB at 2.04 mm can reach 7.12 GHz (10.19 - 17.28 GHz), indicating that this material has very ideal microwave absorption performance in the Ku band. min Value is -56.68 dB; the effective absorption bandwidth EAB at 2.04 mm can reach 7.12 GHz (10.19 - 17.28 GHz), showing that this material has very ideal microwave absorption performance in the Ku band. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 XRD pattern of the high-performance microwave absorption material Ni6W6C prepared in Example 1 of the present invention;

[0024] Figure 2 XRD pattern of the high-performance microwave absorption material Ni6W6C prepared in Example 2 of the present invention;

[0025] Figure 3 XRD pattern of the high-performance microwave absorption material Ni6W6C prepared in Example 3 of the present invention;

[0026] Figure 4 SEM image of the high-performance microwave absorption material Ni6W6C prepared in Example 1 of the present invention;

[0027] Figure 5 SEM image of the high-performance microwave absorption material Ni6W6C prepared in Example 2 of the present invention;

[0028] Figure 6 SEM image of the high-performance microwave absorption material Ni6W6C prepared in Example 3 of the present invention;

[0029] Figure 7 RL value diagram, 3D RL diagram and 2D RL projection diagram of the microwave absorption performance test of the high-performance microwave absorption material Ni6W6C prepared in Examples 1 - 3 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0031] A preparation method of a high-performance microwave absorption material Ni6W6C specifically includes the following steps:

[0032] Step 1: Using deionized water as a solvent, prepare a sodium tungstate solution and a nickel nitrate solution respectively. Then mix the sodium tungstate solution and the nickel nitrate solution in a molar ratio of 1:1, and stir evenly to obtain a mixed solution A. The concentration of sodium tungstate in the mixed solution A is 0.4 mol / L, and the concentration of nickel nitrate is 0.4 mol / L.

[0033] Step 2: Slowly add ethanol and ethylene glycol dropwise to the mixed solution A, and stir to obtain a precursor solution with an alternating light green and white color.

[0034] Step 3: Transfer the precursor solution to a reaction kettle lined with polytetrafluoroethylene, and then place the reaction kettle in an oven for a hydrothermal experiment. The hydrothermal time is 16 h, and the hydrothermal temperature is 180 °C.

[0035] Step 4: After the reaction in Step 3 is completed, take out the hydrothermal product, centrifuge and wash the hydrothermal product to remove impurities. Dry the hydrothermal product after removing impurities in an oven. The drying temperature is 60 °C, and the drying time is 10 - 15 h. Mix the dried hydrothermal product with C6H 12 O6 and Co2O3 with different mass ratios and grind them for 0.5 h. Calcinate the mixture in a tubular furnace under an argon atmosphere. The calcination temperature is 800 °C, and the calcination time is 2 h to obtain a high-performance microwave absorption material Ni6W6C.

[0036] This example also relates to a high-performance microwave absorption material Ni6W6C prepared by the above method. The microstructure of the high-performance microwave absorption material Ni6W6C is a porous structure formed by nanoparticles agglomerating on a carbon shell.

[0037] This example also relates to the application of a high-performance microwave absorption material Ni6W6C prepared by the above method in electromagnetic wave absorption.

[0038] Example 1

[0039] First, take 4 mmol of Na2WO4·H2O and dissolve it in 10 mL of deionized water, and stir it until it is completely dissolved to form a colorless Na2WO4·H2O solution. Then, take 4 mmol of Ni(NO3)2·6H2O and dissolve it in 10 mL of deionized water, and stir it until it is completely dissolved to form a green Ni(NO3)2·6H2O solution. Then, slowly add the Ni(NO3)2·6H2O solution dropwise to the Na2WO4·H2O solution to obtain a mixed solution A.

[0040] Slowly add 10 ml of ethanol and 5 ml of ethylene glycol dropwise to the mixed solution A, and then stir for 30 minutes to obtain a precursor solution with an alternating light green and white color.

[0041] Transfer the precursor solution to a 50 mL reaction kettle lined with polytetrafluoroethylene, and then place the reaction kettle in an oven for a hydrothermal experiment at 180 °C for 16 h.

[0042] After the hydrothermal experiment is completed, take out the hydrothermal product and perform centrifugation and washing three times to remove impurities. After washing, place the hydrothermal product in an oven at 60 °C for drying for 10 h. After the hydrothermal product is completely dried, add the hydrothermal products NiWO4, C6H 12 O6 and Co2O3 into a mortar and grind for 0.5 h to obtain a mixed powder. Among them, the mass ratio of NiWO4 to C6H 12 O6 is 1:1.5, and the mass ratio of NiWO4 to Co2O3 is 10:3. Finally, transfer the mixed powder to a tube furnace under an argon atmosphere and calcine at a temperature of 800 °C for 2 h to obtain a high-performance wave-absorbing material of Ni6W6C / Co2O3.

[0043] Figure 1 XRD pattern of the high-performance wave-absorbing material Ni6W6C prepared in Example 1. It can be observed from the figure that the microstructure of the Ni6W6C / Co2O3 material consists of a porous structure formed by nanoparticles agglomerated on a carbon shell. This porous structure enables the electromagnetic waves incident on the absorber to be multiply reflected. At the same time, there are a large number of interfaces between nanoparticles, and the existence of this interface enhances the polarization relaxation loss, thereby making the wave-absorbing material have excellent wave-absorbing performance.

[0044] Figure 4XRD pattern of the high-performance microwave absorbing material Ni6W6C prepared in Example 1. According to the XRD results of the sample, the 2θ values of nine diffraction characteristic peaks are 23.0598°, 32.8394°, 40.5102°, 43.0861°, 47.1260°, 50.1756°, 60.6184°, 70.6818°, and 73.6875°, respectively. By comparing with the standard card of Ni6W6C (PDF#04-005-4044), it is found that these diffraction characteristic peaks correspond to the (220), (400), (422), (511), (440), (442), (711), (733), and (822) crystal planes of the Ni6W6C material. For the other four diffraction characteristic peaks with 2θ values of 25.5048°, 37.5869°, 43.2105°, and 52.3963°, respectively, by comparing with the standard card of Co2O3 (PDF#04-007-3332), it is found that these diffraction characteristic peaks correspond to the (012), (110), (113), and (024) crystal planes of the Co2O3 material. It shows that the obtained Ni6W6C / Co2O3 high-performance microwave absorbing material in this example is a composite material of Ni6W6C and Co2O3. There are a large number of heterogeneous interfaces at the contact interface between Ni6W6C and Co2O3, which enhances the interfacial polarization loss of the composite material and promotes the microwave absorbing performance of the composite material.

[0045] In this example, the microwave absorbing performance of the composite material was tested. Figure 7 (a1-a3) are the RL value diagram, 3D RL diagram, and 2D RL projection diagram of the composite material with a filling ratio of 30 wt% in the range of 2-18 GHz. When the matching thickness of the composite material is 2.13 mm, the effective absorption bandwidth is 6.01 GHz, and when the matching thickness is 2.22 mm, the RL min value is -50.53 dB.

[0046] Example 2

[0047] First, 4 mmol of Na2WO4·H2O was dissolved in 10 mL of deionized water and stirred until completely dissolved to form a colorless Na2WO4·H2O solution. Then, 4 mmol of Ni(NO3)2·6H2O was dissolved in 10 mL of deionized water and stirred until completely dissolved to form a green Ni(NO3)2·6H2O solution. Then, the Ni(NO3)2·6H2O solution was added dropwise to the Na2WO4·H2O solution to obtain a mixed solution A.

[0048] 10 ml of ethanol and 5 ml of ethylene glycol were added dropwise to the mixed solution A, and then stirred for 30 minutes to obtain a precursor solution with alternating light green and white colors.

[0049] Transfer the precursor solution to a 50 mL reaction kettle lined with polytetrafluoroethylene, and then place the reaction kettle in an oven for a hydrothermal experiment at 180 °C for 16 h.

[0050] After the hydrothermal experiment is completed, take out the hydrothermal product and perform centrifugation and washing three times to remove impurities. After washing, place the hydrothermal product in an oven at 60 °C for drying for 12 h. After the hydrothermal product is completely dried, add the hydrothermal products NiWO4, C6H 12 O6 and Co2O3 into a mortar and grind for 0.5 h to obtain a mixed powder. Among them, the mass ratio of NiWO4 to C6H 12 O6 is 1:1.5, and the mass ratio of NiWO4 to Co2O3 is 10:4. Finally, transfer the mixed powder to a tubular furnace under an argon atmosphere and calcine at a temperature of 800 °C for 2 h to obtain a high-performance microwave absorption material of Ni6W6C / Co2O3.

[0051] Figure 2 XRD pattern of the high-performance microwave absorption material Ni6W6C prepared in Example 2. From Figure 2 it can be observed that the microstructure of the Ni6W6C / Co2O3 material consists of a porous structure formed by the aggregation of nanoparticles on the carbon shell. This porous structure enables the electromagnetic waves incident on the absorber to be multiply reflected. At the same time, there are a large number of interfaces between the nanoparticles, and the existence of this interface enhances the polarization relaxation loss, thereby making the composite material have excellent microwave absorption performance.

[0052] Figure 4XRD pattern of the high-performance microwave absorption material Ni6W6C prepared in Example 2. According to the XRD results of the sample, the 2θ values of nine diffraction characteristic peaks are 23.0598°, 32.8394°, 40.5102°, 43.0861°, 47.1260°, 50.1756°, 60.6184°, 70.6818°, and 73.6875° respectively. By comparing with the standard card of Ni6W6C (PDF#04-005-4044), it is found that these diffraction characteristic peaks correspond to the (220), (400), (422), (511), (440), (442), (711), (733), and (822) crystal planes of the Ni6W6C material. For the other four diffraction characteristic peaks with 2θ values of 25.5048°, 37.5869°, 43.2105°, and 52.3963° respectively, by comparing with the standard card of Co2O3 (PDF#04-007-3332), it is found that these diffraction characteristic peaks correspond to the (012), (110), (113), and (024) crystal planes of the Co2O3 material. It shows that the obtained Ni6W6C / Co2O3 high-performance microwave absorption material in this example is a composite material of Ni6W6C and Co2O3. There are a large number of hetero-interfaces at the contact interface between Ni6W6C and Co2O3, which enhances the interfacial polarization loss of the composite material and promotes the microwave absorption performance of the composite material.

[0053] In this example, the microwave absorption performance of the composite material was tested. Figure 7 (b1-b3) are the RL value diagram, 3D RL diagram, and 2D RL projection diagram of the composite material with a filling ratio of 30 wt% in the range of 2-18 GHz. When the matching thickness of the composite material is 2.04 mm, the effective absorption bandwidth is 7.12 GHz, and when the matching thickness is 4.76 mm, the RL min value is -56.58 dB.

[0054] Example 3

[0055] First, dissolve 4 mmol of Na2WO4·H2O in 10 mL of deionized water and stir it until completely dissolved to form a colorless Na2WO4·H2O solution. Then, dissolve 4 mmol of Ni(NO3)2·6H2O in 10 mL of deionized water and stir it until completely dissolved to form a green Ni(NO3)2·6H2O solution. Then, slowly add the Ni(NO3)2·6H2O solution dropwise to the Na2WO4·H2O solution to obtain a mixed solution A.

[0056] Slowly add 10 ml of ethanol and 5 ml of ethylene glycol dropwise to the mixed solution A. Then stir for 30 minutes to obtain a precursor solution with an alternating light green and white color.

[0057] Transfer the precursor solution to a 50 mL reaction kettle lined with polytetrafluoroethylene, and then place the reaction kettle in an oven for a hydrothermal experiment at 180 °C for 16 h.

[0058] After the hydrothermal experiment is completed, take out the product and perform centrifugation and washing several times to remove impurities. After washing, place the product in an oven at 60 °C for drying for 15 h. After the hydrothermal product is completely dried, add the hydrothermal products NiWO4, C6H 12 O6 and Co2O3 to a mortar and grind for 0.5 h to obtain a mixed powder. Among them, the mass ratio of NiWO4 to C6H 12 O6 is 1:1.5, and the mass ratio of NiWO4 to Co2O3 is 10:5. Finally, transfer the mixed powder to a tube furnace under an argon atmosphere and calcine at 800 °C for 2 h to obtain a high-performance wave-absorbing material of Ni6W6C / Co2O3.

[0059] Figure 3 XRD pattern of the high-performance wave-absorbing material Ni6W6C prepared in Example 3. It can be observed from the figure that the microstructure of the Ni6W6C / Co2O3 material consists of a porous structure formed by nanoparticles agglomerated on a carbon shell. This porous structure enables the electromagnetic waves incident on the absorber to be multiply reflected. At the same time, there are a large number of interfaces between nanoparticles, and the existence of this interface enhances the polarization relaxation loss, thus enabling the composite material to have excellent wave-absorbing performance.

[0060] Comparison Figures 1-3 shows that with the increase in the composite amount of Co2O3, affected by the oxide, the size of the nanoparticle agglomeration gradually becomes smaller. Due to the surface effect, as the particle size decreases, the specific surface area increases, resulting in an increase in the proportion of surface atoms in the particles. When the particle size drops below the electron mean free path, the electron mean free path in the particles is restricted by the particle dimension, which will affect the wave-absorbing characteristics of the particles.

[0061] Figure 6XRD pattern of the high-performance microwave absorbing material Ni6W6C prepared in Example 3. According to the XRD results of the sample, the 2θ values of nine diffraction characteristic peaks are 23.0598°, 32.8394°, 40.5102°, 43.0861°, 47.1260°, 50.1756°, 60.6184°, 70.6818°, and 73.6875°, respectively. By comparing with the standard card of Ni6W6C (PDF#04-005-4044), it is found that these diffraction characteristic peaks correspond to the (220), (400), (422), (511), (440), (442), (711), (733), and (822) crystal planes of the Ni6W6C material. For the other four diffraction characteristic peaks with 2θ values of 25.5048°, 37.5869°, 43.2105°, and 52.3963°, respectively, by comparing with the standard card of Co2O3 (PDF#04-007-3332), it is found that these diffraction characteristic peaks correspond to the (012), (110), (113), and (024) crystal planes of the Co2O3 material. It shows that the obtained Ni6W6C / Co2O3 high-performance microwave absorbing material in this example is a composite material of Ni6W6C and Co2O3. There are a large number of hetero-interfaces at the contact interface between Ni6W6C and Co2O3, which enhances the interfacial polarization loss of the composite material and promotes the microwave absorbing performance of the composite material.

[0062] In this example, the microwave absorbing performance of this composite material was tested. Figure 7 (c1-c3) are the RL value diagram, 3D RL diagram, and 2D RL projection diagram of the composite material with a filling ratio of 30 wt% in the range of 2-18 GHz. When the matching thickness of the composite material is 2.11 mm, the corresponding effective absorption bandwidth is 5.42 GHz, and when the matching thickness is 1.44 mm, the RL min value is -47.71 dB.

[0063] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that this is only for illustration purposes. The protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these embodiments, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A method for preparing high-performance absorbing material Ni6W6C, characterized in that: The specific steps include: Step 1, using deionized water as a solvent, preparing a sodium tungstate solution and a nickel nitrate solution respectively, then mixing the sodium tungstate solution and the nickel nitrate solution, and stirring them evenly to obtain a mixed solution A; Step 2, adding ethanol and ethylene glycol dropwise to the mixed solution A, and stirring to obtain a precursor solution of light green and white; Step 3, transferring the precursor solution to a reactor lined with polytetrafluoroethylene, and then placing the reactor in an oven for a hydrothermal experiment; Step 4: After the reaction in step 3 is completed, the hydrothermal product is taken out, centrifuged and washed to remove impurities, the hydrothermal product after impurities are removed is dried in an oven, and the dried hydrothermal product is mixed with C6H 12 O6 and Co2O3 are mixed and ground, and the mixture is calcined in a tube furnace under an argon environment to obtain a high-performance absorbing material Ni6W6C.

2. The method for preparing a high-performance absorbing material Ni6W6C according to claim 1, characterized in that: In step 1, the sodium tungstate solution and the nickel nitrate solution are mixed in a molar ratio of 1:

1.

3. The method for preparing a high-performance absorbing material Ni6W6C according to claim 1, characterized in that: In step 1, the concentration of sodium tungstate in the mixed solution A is 0.4 mol / L, and the concentration of nickel nitrate is 0.4 mol / L.

4. The method for preparing a high-performance absorbing material Ni6W6C according to claim 1, characterized in that: The conditions of the hydrothermal experiment in step 3 are: hydrothermal time 16 h, hydrothermal temperature 180°C.

5. The method for preparing a high-performance absorbing material Ni6W6C according to claim 1, characterized in that: In step 4, the drying temperature in the oven is 60° C. and the drying time is 10-15 hours.

6. The method for preparing a high-performance absorbing material Ni6W6C according to claim 1, characterized in that: In step 4, the dried hydrothermal product is mixed with C6H 12 O6 and Co2O3 were mixed and ground for 0.5h.

7. The method for preparing a high-performance absorbing material Ni6W6C according to claim 1, characterized in that: In step 4, the calcination temperature in the tubular furnace is 800° C. and the calcination time is 2 h.

8. The high-performance absorbing material Ni6W6C prepared by the method for preparing the high-performance absorbing material Ni6W6C according to any one of claims 1 to 7 is characterized in that: The microstructure of the absorbing material Ni6W6C is a porous structure formed by nanoparticles agglomerated on a carbon shell.

9. Use of the high performance absorbing material Ni6W6C according to claim 8 in electromagnetic wave absorption.

Images