Modified magnetic material-coated MoS2 / graphite composite wave-absorbing material and preparation method and application thereof

Abstract

The invention relates to a modified magnetic material (at) MoS2 / graphite composite wave-absorbing material as well as a preparation method and application thereof. The modified magnetic material (at) MoS2 / graphite composite wave-absorbing material is obtained by carrying out heat treatment on a magnetic material (at) MoS2 / graphite composite wave-absorbing material; the grain size of the magnetic material in the modified magnetic material and MoS2 / graphite composite wave-absorbing material is greater than that of the magnetic material in the magnetic material and MoS2 / graphite composite wave-absorbing material before heat treatment. According to the invention, the structure and components of the magnetic material coated MoS2 / graphite composite wave-absorbing material are optimized, so that the overall performance of the optimized modified magnetic material coated MoS2 / graphite composite wave-absorbing material, especially the electromagnetic wave absorbing capability, is obviously improved, that is, the material has a lower reflection loss value and a wider effective electromagnetic wave absorbing bandwidth.

Description

Technical Field

[0001] The present invention relates to the technical field of composite absorbing material preparation, and in particular to a modified magnetic material @MoS2 / graphite composite absorbing material and a preparation method and application thereof. Background Art

[0002] With the development of absorbing materials, two-dimensional materials have gradually become a promising choice in the future absorbing field. Metal-based, semiconductor-based, MXene-based, carbon-based two-dimensional materials and black phosphorus absorbing materials have attracted widespread attention because of their unique and effective electromagnetic wave attenuation methods. Semiconductor-based absorbing materials are gaining more and more attention in the field of electromagnetic wave absorption and shielding due to their unique electromagnetic properties and relatively lightweight advantages. Common semiconductor-based absorbing materials include molybdenum disulfide, tungsten disulfide, silicon nitride, gallium nitride, zinc oxide, and titanium dioxide. Among them, MoS2 has attracted more and more attention due to its good electromagnetic wave absorption performance, direct band gap, excellent chemical stability and mechanical strength.

[0003] At present, there are many methods for preparing composite absorbing materials, which can be mainly divided into hydrothermal method, solution gel method and ball milling method, etc. The hydrothermal method and solution gel method for preparing absorbing materials can make the reactants react fully to obtain materials with uniform composition and high purity. Moreover, since the reaction conditions (such as temperature, pressure, reaction time, solvent type, etc.) are controllable, the morphology of the finished product is also easy to adjust, and it is often used to prepare materials with complex structures. However, once it comes to mass production, the hydrothermal method and solution gel method have limitations. The amount of single preparation is extremely small and cannot meet the needs of mass production. Moreover, if the cost issue needs to be considered at the same time, the above two methods cannot meet the demand for low cost.

[0004] The ball milling method is used to prepare composite absorbing materials, which can be used to mass produce absorbing materials. It has a wide range of applications and can change the organizational structure of the material by adjusting the process parameters, making the high-speed ball milling method the future direction of industrial production of high-performance absorbing materials. For example, CN117123786A discloses a flaky FeSiAl absorbing powder and a preparation method thereof, wherein a flaky FeSiAl alloy powder is obtained by ball milling, and then a flaky FeSiAl absorbing powder is obtained by an annealing process under reducing atmosphere conditions. The ball milling process is simple, has good reproducibility, can be prepared in large quantities, and an appropriate annealing process can adjust the order of the crystal structure, so that the alloy grains grow, and can effectively adjust the magnetic properties of the material.

[0005] However, ball milling is rarely used to prepare MoS2 composite absorbing materials. In order to meet the material needs of more fields, how to further improve the absorption capacity of MoS2 composite absorbing materials prepared by ball milling for electromagnetic waves, so that they have lower reflection loss values ​​and wider effective electromagnetic wave absorption bandwidth on the existing basis, has become a problem that needs to be solved urgently. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a modified magnetic material @MoS2 / graphite composite absorbing material and its preparation method and application. The present invention optimizes the structure and components of the magnetic material @MoS2 / graphite composite absorbing material, so that the overall performance of the optimized modified magnetic material @MoS2 / graphite composite absorbing material is significantly improved, especially the ability to absorb electromagnetic waves, that is, it has a lower reflection loss value and a wider effective electromagnetic wave absorbing bandwidth.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a modified magnetic material @MoS2 / graphite composite wave absorbing material, wherein the modified magnetic material @MoS2 / graphite composite wave absorbing material is obtained by heat treating a magnetic material @MoS2 / graphite composite wave absorbing material;

[0009] The grain size of the magnetic material in the modified magnetic material @MoS2 / graphite composite wave absorbing material is larger than the grain size of the magnetic material in the magnetic material @MoS2 / graphite composite wave absorbing material before heat treatment.

[0010] It should be noted that the grain size of the magnetic material before and after modification of the present invention is calculated by the Debye-Scherrer formula (D=Kγ / bcosθ) based on the crystal plane corresponding to the characteristic diffraction peak of the magnetic material in the XRD diagram of each composite absorbing material.

[0011] In the present invention, heat treatment can optimize most of the defects and dislocations in the magnetic material @MoS2 / graphite composite absorbing material, thereby optimizing the structure of the magnetic material @MoS2 / graphite composite absorbing material, so that the overall performance of the optimized modified magnetic material @MoS2 / graphite composite absorbing material is improved, especially the ability to absorb electromagnetic waves. At the same time, the grain size can be further adjusted to a size that is more conducive to pinning, which can better fix the magnetic domain wall and prevent the magnetic domain wall from moving more freely, thereby reducing the magnetic loss, which is not conducive to the improvement of the absorbing performance.

[0012] As a preferred technical solution of the present invention, the modified magnetic material @MoS2 / graphite composite absorbing material includes a lamellar MoS2 / graphite mixed material and a flaky magnetic material.

[0013] Preferably, the lamellar MoS2 / graphite mixed material comprises granular magnetic material between the layers.

[0014] Preferably, the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with magnetic metal elements.

[0015] Preferably, the surface of the sheet-like magnetic material comprises a protruding structure.

[0016] Preferably, the protruding structure is a magnetic oxide obtained by oxidizing the flaky magnetic material.

[0017] In the present invention, on the basis of optimizing the structure of the magnetic material @MoS2 / graphite composite absorbing material, its components are also optimized. The magnetic oxide corresponding to the surface protrusion structure of the optimized modified magnetic material @MoS2 / graphite composite absorbing material can improve the magnetic loss performance of the composite absorbing material in the high-frequency region, that is, the composite absorbing material has more excellent absorbing performance in the high-frequency band.

[0018] Preferably, the diameter of the protrusion structure is 7 nm-10 nm, for example, 7 nm, 7.5 nm, 8 nm, 8.5 nm, 9 nm, 9.5 nm or 10 nm.

[0019] Preferably, the lamellar MoS2 / graphite mixed powder includes Mo oxide generated by oxidation of MoS2.

[0020] In the present invention, appropriate heat treatment of lamellar MoS2 causes MoS2 to oxidize, enriches the interfacial polarization mechanism of the material, adjusts the interlayer spacing of the lamellar MoS2, and enhances the capacitance effect.

[0021] Preferably, the Mo oxide includes MoO3 and / or MoO2.

[0022] As a preferred technical solution of the present invention, the surface of the modified magnetic material @MoS2 / graphite composite absorbing material includes a mixed layer of organic materials.

[0023] Preferably, the organic material mixed layer comprises an organic material and a thermal decomposition product of the organic material.

[0024] In the present invention, the organic material mixed layer includes organic materials and products of thermal decomposition of the organic materials (cyclic lactone organic matter), not a single organic material. The mixture of multiple materials will further enrich the interface polarization pattern of the material surface.

[0025] In a second aspect, the present invention also provides a method for preparing a modified magnetic material @MoS2 / graphite composite absorbing material, the preparation method comprising the following steps:

[0026] The magnetic material @MoS2 / graphite composite absorbing material is heat-treated to obtain a modified magnetic material @MoS2 / graphite composite absorbing material.

[0027] In the present invention, by subjecting the magnetic material @MoS2 / graphite composite absorber to heat treatment, the composition and structure of the composite absorber can be optimized at the same time, thereby effectively improving its dielectric loss and magnetic loss performance. In particular, for the composite absorber after high-speed ball milling, heat treatment at an appropriate temperature can adjust the grain size of the magnetic material inside the composite absorber, release part of the ball milling stress and most of the defects, and at the same time, due to the input of thermal energy, the grains inside the magnetic material may undergo a certain rearrangement and fine-tuning of the crystal structure, making the magnetic domain arrangement more orderly, thereby increasing the saturation magnetism and strengthening the composite material's ability to absorb electromagnetic waves.

[0028] As a preferred technical solution of the present invention, the temperature of the heat treatment is 100℃-350℃, for example, 100℃, 120℃, 150℃, 180℃, 200℃, 220℃, 250℃, 280℃, 300℃, 320℃ or 350℃, etc., preferably 150℃-300℃.

[0029] The present invention further regulates the temperature of the heat treatment to 150°C-300°C, which can better achieve the modification effect, more thoroughly eliminate the defects and dislocations introduced by ball milling, and the composite material has better absorbing performance. On the other hand, the pinning effect of the magnetic material caused by excessive growth of the grain size exceeding its critical size in the modified magnetic material @MoS2 / graphite composite absorbing material will not be reduced, and the magnetic domain wall movement becomes freer, resulting in further reduction of magnetic loss.

[0030] Preferably, the heat treatment time is 1 h-3 h, for example, 1 h, 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.5 h, 2.8 h or 3 h.

[0031] Preferably, the heating rate of the heat treatment is 3°C / min-8°C / min, for example, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min or 8°C / min.

[0032] Preferably, the heat treatment is performed under vacuum conditions.

[0033] Preferably, the oxygen partial pressure under the vacuum condition is 250Pa-300Pa, for example, 250Pa, 260Pa, 270Pa, 280Pa, 290Pa or 300Pa.

[0034] In the present invention, the oxygen partial pressure of the vacuum condition is regulated to be 250Pa-300Pa, and the amount of the generated magnetic oxide protrusion structure (the diameter of the protrusion structure) is regulated. Taking carbonyl iron as the magnetic material, since Fe and oxidized Fe3O4 are two different materials, under the action of the alternating electric field, the charges are accumulated at the interface of the two substances, thereby forming a significant interface polarization. Moreover, since the electrical conductivity of Fe3O4 is relatively low, under high-frequency conditions, the accumulation of charges on its interface will cause large dielectric losses. If the degree of oxidation is too large, too much Fe3O4 will be generated, and its conductivity and magnetism are weaker than those of Fe, which will cause the magnetic permeability to decrease too much, and thus the electromagnetic wave absorption capacity of the magnetic material @MoS2 / graphite composite absorbing material cannot be effectively improved.

[0035] As a preferred technical solution of the present invention, the magnetic material @MoS2 / graphite composite absorbing material is prepared by ball milling.

[0036] Preferably, the preparation method of the magnetic material @MoS2 / graphite composite absorbing material comprises the following steps:

[0037] The magnetic powder, lamellar MoS2 / graphite mixed powder and solvent are mixed and ball-milled to obtain the magnetic material@MoS2 / graphite composite absorbing material.

[0038] As a preferred technical solution of the present invention, the magnetic powder includes any one of carbonyl iron powder, carbonyl nickel powder, carbonyl cobalt powder, iron-nickel alloy powder, iron-cobalt alloy powder or ferrite magnetic powder, or a combination of at least two thereof.

[0039] Preferably, the magnetic powder is in a granular morphology.

[0040] Preferably, in the lamellar MoS2 / graphite mixed powder, graphite is dispersed in the lamellar MoS2 matrix.

[0041] Preferably, in the lamellar MoS2 / graphite mixed powder, the molar ratio of the graphite to the lamellar MoS2 matrix is ​​1:(8-14), for example, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13 or 1:14, etc.

[0042] Preferably, the molar ratio of the magnetic powder to the lamellar MoS2 / graphite mixed powder is (1-3):1, for example, 1:1, 1.5:1, 2:1, 2.5:1 or 3:1, etc.

[0043] As a preferred technical solution of the present invention, the mixing process also includes adding a dispersant and ball milling together.

[0044] Preferably, the dispersant comprises an organic substance containing a free carboxyl group.

[0045] Preferably, the dispersant comprises oleic acid.

[0046] Preferably, the solvent comprises anhydrous ethanol.

[0047] Preferably, the volume ratio of the dispersant to the solvent is 1:(2-5), such as 1:2, 1:3, 1:4 or 1:5.

[0048] It should be noted that the present invention does not impose any specific requirements or special limitations on the amount of the solvent added, as long as it can cover the powder. Those skilled in the art can make adaptive selections and adjustments based on actual conditions.

[0049] Preferably, the rotation speed of the ball mill is 400r / min-1000r / min, for example, 400r / min, 450r / min, 500r / min, 550r / min, 600r / min, 650r / min, 700r / min, 750r / min, 800r / min, 850r / min, 900r / min, 950r / min or 1000r / min, etc.

[0050] Preferably, the ball milling time is 18 h-24 h, for example, 18 h, 19 h, 20 h, 21 h, 22 h, 23 h or 24 h.

[0051] Preferably, after the ball milling, a washing and drying process is also included.

[0052] Preferably, the washing liquid for washing comprises anhydrous ethanol and / or deionized water.

[0053] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0054] The magnetic material @MoS2 / graphite composite absorbing material is heat treated at 100°C-350°C for 1h-3h under a vacuum condition with an oxygen partial pressure of 250Pa-300Pa to obtain a modified magnetic material @MoS2 / graphite composite absorbing material;

[0055] The magnetic material @MoS2 / graphite composite absorbing material is prepared by ball milling; the preparation method of the magnetic material @MoS2 / graphite composite absorbing material comprises the following steps:

[0056] The magnetic powder, lamellar MoS2 / graphite mixed powder, dispersant and solvent are mixed and ball milled at 400r / min-1000r / min for 18h-24h, washed and dried to obtain a magnetic material @MoS2 / graphite composite absorbing material;

[0057] Among them, the mass ratio of the magnetic powder to the lamellar MoS2 / graphite mixed powder is (1-3):1; in the lamellar MoS2 / graphite mixed powder, graphite is dispersed in the lamellar MoS2 matrix, and the molar ratio of the graphite to the lamellar MoS2 matrix is ​​1:(8-14); the volume ratio of the dispersant to the solvent is 1:(2-5).

[0058] In the third aspect, the present invention also provides an application of a modified magnetic material @MoS2 / graphite composite absorbing material, wherein the modified magnetic material @MoS2 / graphite composite absorbing material described in the first aspect, or the modified magnetic material @MoS2 / graphite composite absorbing material prepared by the preparation method described in the second aspect, is applied to a microwave absorbing device to absorb electromagnetic waves.

[0059] Compared with the prior art, the present invention has at least the following beneficial effects:

[0060] 1) The present invention optimizes the structure and components of the magnetic material @MoS2 / graphite composite absorbing material, so that the overall performance of the optimized modified magnetic material @MoS2 / graphite composite absorbing material is significantly improved, especially the ability to absorb electromagnetic waves, that is, it has a lower reflection loss value and a wider effective electromagnetic wave absorbing bandwidth.

[0061] 2) For Fe@MoS2 / graphite composite absorbing materials, the bandwidth of reflection loss ≤-10dB after modification is 3.52GHz-4.16GHz, and the minimum reflection loss can be as low as -59.80dB and below, and the minimum can reach -65.07dB compared with -58.66dB before modification; for Ni@MoS2 / graphite composite absorbing materials, the minimum reflection loss after modification can reach -58.03dB compared with -53.24dB before modification, and the bandwidth of reflection loss ≤-10dB is also increased; for Fe / Ni alloy@MoS2 / graphite composite absorbing materials, the minimum reflection loss after modification can reach -57.03dB compared with -55.32dB before modification, and the bandwidth of reflection loss ≤-10dB is also increased; it can be seen that the electromagnetic wave absorption performance of the composite absorbing material can be significantly improved after heat treatment at an appropriate temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is a SEM image of the modified Fe@MoS2 / graphite composite absorbing material prepared in Example 1 of the present invention.

[0063] Figure 2 This is a SEM image of the modified Fe@MoS2 / graphite composite absorbing material prepared in Example 2 of the present invention.

[0064] Figure 33 and 4. These are XRD diagrams of the modified Fe@MoS2 / graphite composite absorbing materials prepared in Examples 1, 2, 8 and 9 of the present invention.

[0065] Figure 4 It is a three-dimensional graph of “reflection loss-frequency-thickness” of the modified Fe@MoS2 / graphite composite absorbing material prepared in Example 1 of the present invention.

[0066] Figure 5 This is a graph of “reflection loss-frequency-thickness” of the modified Fe@MoS2 / graphite composite absorbing material prepared in Example 1 of the present invention.

[0067] Figure 6 It is a three-dimensional graph of “reflection loss-frequency-thickness” of the Fe@MoS2 / graphite composite absorbing material prepared in Comparative Example 1 of the present invention.

[0068] Figure 7 This is a graph of “reflection loss-frequency-thickness” of the Fe@MoS2 / graphite composite absorbing material prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0069] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0070] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0071] Example 1

[0072] The present embodiment provides a modified Fe@MoS2 / graphite composite absorbing material and a preparation method thereof, wherein in the modified Fe@MoS2 / graphite composite absorbing material, the grain size of the Fe(103) crystal plane is 12.5 nm, and in the Fe@MoS2 / graphite composite absorbing material before modification, the grain size of the Fe(103) crystal plane is 7.46 nm, wherein the critical grain size of Fe when generating the pinning effect is 12.5 nm;

[0073] The modified Fe@MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a lamellar Fe; the lamellar MoS2 / graphite mixed material comprises Fe particles between the layers; the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with Fe elements; the surface of the lamellar Fe comprises a Fe3O4 protrusion structure with a diameter of 8nm-10nm, and the lamellar MoS2 / graphite mixed powder comprises MoO3;

[0074] The preparation method comprises the following steps:

[0075] The Fe@MoS2 / graphite composite absorbing material was heat treated at 300°C for 2h under a vacuum condition with an oxygen partial pressure of 280Pa to obtain a modified Fe@MoS2 / graphite composite absorbing material;

[0076] The preparation method of the Fe@MoS2 / graphite composite absorbing material comprises the following steps:

[0077] According to the molar ratio of carbonyl iron powder and lamellar MoS2 / graphite mixed powder being 2:1, 10.78g of carbonyl iron powder and 15.41g of lamellar MoS2 / graphite mixed powder (the molar ratio of graphite and lamellar MoS2 matrix is ​​1:11) were weighed, and then 50mL of oleic acid and 150mL of anhydrous ethanol were added, and ball milled at a speed of 600r / min for 20h (ball-to-material ratio 20:1). After taking out, wash it with anhydrous ethanol for 3 times, and dry it in a vacuum drying oven at 60℃ for 12h to obtain the Fe@MoS2 / graphite composite absorbing material.

[0078] Figure 1 The SEM image of the modified Fe@MoS2 / graphite composite absorbing material prepared in Example 1 of the present invention is shown. It can be seen from the figure that there are a large number of 8nm-10nm protrusion structures on the surface of the flaky Fe, which are Fe3O4 obtained after Fe oxidation.

[0079] Example 2

[0080] This embodiment provides a modified Fe@MoS2 / graphite composite absorbing material and a preparation method thereof, wherein in the modified Fe@MoS2 / graphite composite absorbing material, the grain size of the Fe(103) crystal plane is 8.59 nm, and in the Fe@MoS2 / graphite composite absorbing material before modification, the grain size of the Fe(103) crystal plane is 7.46 nm, wherein the critical grain size of Fe when generating the pinning effect is 12.5 nm;

[0081] The modified Fe@MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a flaky Fe; the interlayers of the lamellar MoS2 / graphite mixed material comprise Fe particles; the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with Fe elements; the surface of the flaky Fe has no obvious changes;

[0082] The difference between the preparation method and Example 1 is that the heat treatment temperature is 200° C., and the other preparation methods and parameters are consistent with Example 1.

[0083] Figure 2The SEM image of the modified Fe@MoS2 / graphite composite absorbing material prepared in Example 2 of the present invention is shown. It can be seen from the figure that there is no obvious change on the surface of the flaky Fe. Since the heat treatment temperature is relatively low, the flaky Fe has no obvious oxidation phenomenon.

[0084] Example 3

[0085] The present embodiment provides a modified Fe@MoS2 / graphite composite absorbing material and a preparation method thereof, wherein in the modified Fe@MoS2 / graphite composite absorbing material, the grain size of the Fe(103) crystal plane is 8.32 nm, and in the Fe@MoS2 / graphite composite absorbing material before modification, the grain size of the Fe(103) crystal plane is 7.46 nm, wherein the critical grain size of Fe when generating the pinning effect is 12.5 nm;

[0086] The modified Fe@MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a flaky Fe; the interlayers of the lamellar MoS2 / graphite mixed material comprise Fe particles; the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with Fe elements; the surface of the flaky Fe has no obvious changes;

[0087] The difference between the preparation method and Example 1 is that the heat treatment temperature is 150° C., and the other preparation methods and parameters are consistent with Example 1.

[0088] Example 4

[0089] The present embodiment provides a modified Fe@MoS2 / graphite composite absorbing material and a preparation method thereof, wherein in the modified Fe@MoS2 / graphite composite absorbing material, the grain size of the Fe(103) crystal plane is 12.59 nm, and in the Fe@MoS2 / graphite composite absorbing material before modification, the grain size of the Fe(103) crystal plane is 7.46 nm, wherein the critical grain size of Fe when generating the pinning effect is 12.5 nm;

[0090] The modified Fe@MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a lamellar Fe; the lamellar MoS2 / graphite mixed material comprises Fe particles between the layers; the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with Fe elements; the surface of the lamellar Fe comprises a Fe3O4 protrusion structure with a diameter of 9nm-10nm, and the lamellar MoS2 / graphite mixed powder comprises MoO3;

[0091] The difference between the preparation method and Example 1 is that the heat treatment temperature is 350° C., and the other preparation methods and parameters are consistent with Example 1.

[0092] Example 5

[0093] The present embodiment provides a modified Ni@MoS2 / graphite composite absorbing material and a preparation method thereof. In the modified Ni@MoS2 / graphite composite absorbing material, the grain size of the Ni(111) crystal plane is 2.15 nm, and in the Ni@MoS2 / graphite composite absorbing material before modification, the grain size of the Ni(111) crystal plane is 2.034 nm; the critical grain size of Ni when the pinning effect occurs is 2.15 nm;

[0094] The modified Ni@MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a flaky Ni; the interlayers of the lamellar MoS2 / graphite mixed material comprise Ni particles; the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with Ni elements, and the lamellar MoS2 / graphite mixed powder comprises MoO3;

[0095] The preparation method comprises the following steps:

[0096] The Ni@MoS2 / graphite composite absorbing material was heat treated at 300°C for 1 h under a vacuum condition with an oxygen partial pressure of 280 Pa to obtain a modified Ni@MoS2 / graphite composite absorbing material;

[0097] The preparation method of the Ni@MoS2 / graphite composite absorbing material comprises the following steps:

[0098] According to the molar ratio of carbonyl nickel powder and lamellar MoS2 / graphite mixed powder being 2:1, 9.40g of carbonyl nickel powder and 15.41g of lamellar MoS2 / graphite mixed powder (the molar ratio of graphite and lamellar MoS2 matrix is ​​1:11) were weighed, and then 50mL of oleic acid and 150mL of anhydrous ethanol were added, and ball milled at a speed of 450r / min for 24h (ball-to-material ratio 20:1). After taking out, wash it with anhydrous ethanol for 3 times, and dry it in a vacuum drying oven at 60℃ for 12h to obtain the Ni@MoS2 / graphite composite absorbing material.

[0099] Example 6

[0100] The present embodiment provides a modified Fe / Ni alloy@MoS2 / graphite composite absorbing material and a preparation method thereof. In the modified Fe / Ni alloy@MoS2 / graphite composite absorbing material, the grain size of the Fe(103) crystal plane is 12.5 nm, and the grain size of the Ni(111) crystal plane is 2.15 nm. In the Fe / Ni@MoS2 / graphite composite absorbing material before modification, the grain size of the Fe(103) crystal plane is 7.46 nm, and the grain size of the Ni(111) crystal plane is 2.034 nm; wherein the critical grain size of Fe when the pinning effect is generated is 12.5 nm; and the critical grain size of Ni when the pinning effect is generated is 2.15 nm.

[0101] The modified Fe / Ni alloy@MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a lamellar Fe / Ni alloy; the interlayers of the lamellar MoS2 / graphite mixed material comprise Fe / Ni alloy particles; the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with Fe and Ni elements; the surface of the lamellar Fe / Ni alloy comprises a Fe3O4 protrusion structure with a diameter of 8nm-10nm, and the lamellar MoS2 / graphite mixed powder comprises MoO3;

[0102] The preparation method comprises the following steps:

[0103] The Fe / Ni alloy@MoS2 / graphite composite absorbing material was heat treated at 300°C for 3 h under a vacuum condition with an oxygen partial pressure of 280 Pa to obtain a modified Fe / Ni@MoS2 / graphite composite absorbing material;

[0104] The preparation method of the Fe / Ni@MoS2 / graphite composite absorbing material comprises the following steps:

[0105] According to the molar ratio of iron-nickel alloy powder (atomic ratio of 1:1) and lamellar MoS2 / graphite mixed powder of 2:1, 11.07g of iron-nickel alloy powder and 15.41g of lamellar MoS2 / graphite mixed powder (the molar ratio of graphite and lamellar MoS2 matrix is ​​1:11) were weighed, and then 50mL of oleic acid and 150mL of anhydrous ethanol were added, and ball milled at a speed of 600r / min for 18h (ball-to-material ratio of 20:1). After taking out, wash it with anhydrous ethanol for 3 times, and dry it in a vacuum drying oven at 60℃ for 12h to obtain Fe / Ni alloy@MoS2 / graphite composite absorbing material.

[0106] Example 7

[0107] The present embodiment provides a modified Fe@MoS2 / graphite composite absorbing material and a preparation method thereof, wherein in the modified Fe@MoS2 / graphite composite absorbing material, the grain size of the Fe(103) crystal plane is 12.5 nm, and in the Fe@MoS2 / graphite composite absorbing material before modification, the grain size of the Fe(103) crystal plane is 7.46 nm, wherein the critical grain size of Fe when generating the pinning effect is 12.5 nm;

[0108] The modified Fe@MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a flaky Fe; the interlayers of the lamellar MoS2 / graphite mixed material comprise Fe particles; the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with Fe elements; the surface of the flaky Fe comprises a Fe3O4 protrusion structure with a diameter of 15nm-20nm, and the lamellar MoS2 / graphite mixed powder comprises MoO3;

[0109] The difference between the preparation method and Example 1 is that the oxygen partial pressure under vacuum conditions is 400 Pa, and the other preparation methods and parameters are consistent with Example 1.

[0110] Example 8

[0111] The present embodiment provides a modified Fe@MoS2 / graphite composite absorbing material and a preparation method thereof, wherein in the modified Fe@MoS2 / graphite composite absorbing material, the grain size of the Fe(103) crystal plane is 14.27 nm, and in the Fe@MoS2 / graphite composite absorbing material before modification, the grain size of the Fe(103) crystal plane is 7.46 nm, wherein the critical grain size of Fe when generating the pinning effect is 12.5 nm;

[0112] The modified Fe@MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a lamellar Fe; the lamellar MoS2 / graphite mixed material comprises Fe particles between the layers; the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with Fe elements; the surface of the lamellar Fe comprises a Fe3O4 protrusion structure with a diameter of 40nm-60nm, and the lamellar MoS2 / graphite mixed powder comprises MoO3;

[0113] The difference between the preparation method and Example 1 is that the heat treatment temperature is 400° C., and the other preparation methods and parameters are consistent with Example 1.

[0114] Example 9

[0115] The present embodiment provides a modified Fe@MoS2 / graphite composite absorbing material and a preparation method thereof, wherein in the modified Fe@MoS2 / graphite composite absorbing material, the grain size of the Fe(103) crystal plane is 27.11 nm, and in the Fe@MoS2 / graphite composite absorbing material before modification, the grain size of the Fe(103) crystal plane is 7.46 nm, wherein the critical grain size of Fe when generating the pinning effect is 12.5 nm;

[0116] The modified Fe@MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a lamellar Fe; the interlayers of the lamellar MoS2 / graphite mixed material comprise Fe particles; the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with Fe elements; the surface of the lamellar Fe comprises a Fe3O4 protrusion structure with a diameter of 80nm-130nm, and the lamellar MoS2 / graphite mixed powder comprises MoO3;

[0117] The difference between the preparation method and Example 1 is that the heat treatment temperature is 500° C., and the other preparation methods and parameters are consistent with Example 1.

[0118] Example 10

[0119] The present embodiment provides a modified Fe@MoS2 / graphite composite absorbing material and a preparation method thereof, wherein in the modified Fe@MoS2 / graphite composite absorbing material, the grain size of the Fe(103) crystal plane is 7.46 nm, and in the Fe@MoS2 / graphite composite absorbing material before modification, the grain size of the Fe(103) crystal plane is 7.46 nm, wherein the critical grain size of Fe when generating the pinning effect is 12.5 nm;

[0120] The modified Fe@MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a flaky Fe; the interlayers of the lamellar MoS2 / graphite mixed material comprise Fe particles; the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with Fe elements; the surface of the flaky Fe has no obvious changes;

[0121] The difference between the preparation method and Example 1 is that the heat treatment temperature is 80° C., and the other preparation methods and parameters are consistent with Example 1.

[0122] Embodiment 11

[0123] The present embodiment provides a modified Fe@MoS2 / graphite composite absorbing material and a preparation method thereof, wherein in the modified Fe@MoS2 / graphite composite absorbing material, the grain size of the Fe(103) crystal plane is 13.46 nm, and in the Fe@MoS2 / graphite composite absorbing material before modification, the grain size of the Fe(103) crystal plane is 7.46 nm, wherein the critical grain size of Fe when generating the pinning effect is 12.5 nm;

[0124] The modified Fe@MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a lamellar Fe; the lamellar MoS2 / graphite mixed material comprises Fe particles between the layers; the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with Fe elements; the surface of the lamellar Fe comprises a Fe3O4 protrusion structure with a diameter of 11nm-14nm, and the lamellar MoS2 / graphite mixed powder comprises MoO3;

[0125] The difference between the preparation method and Example 1 is that the heat treatment time is 4 hours, and the other preparation methods and parameters are consistent with Example 1.

[0126] Example 12

[0127] The present embodiment provides a modified Fe@MoS2 / graphite composite absorbing material and a preparation method thereof, wherein in the modified Fe@MoS2 / graphite composite absorbing material, the grain size of the Fe(103) crystal plane is 11.67 nm, and in the Fe@MoS2 / graphite composite absorbing material before modification, the grain size of the Fe(103) crystal plane is 7.46 nm, wherein the critical grain size of Fe when generating the pinning effect is 12.5 nm;

[0128] The modified Fe@MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a lamellar Fe; the lamellar MoS2 / graphite mixed material comprises Fe particles between the layers; the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with Fe elements; the surface of the lamellar Fe comprises a Fe3O4 protrusion structure with a diameter of 8nm-10nm, and the lamellar MoS2 / graphite mixed powder comprises MoO3;

[0129] The difference between the preparation method and Example 1 is that the heating rate of the heat treatment is 10°C / min, and the other preparation methods and parameters are consistent with Example 1.

[0130] Comparative Example 1

[0131] This comparative example provides a Fe@MoS2 / graphite composite absorbing material and a preparation method thereof. The preparation method of the Fe@MoS2 / graphite composite absorbing material is consistent with that of Example 1, but no heat treatment modification is performed, that is, the Fe@MoS2 / graphite composite absorbing material before modification.

[0132] Comparative Example 2

[0133] This comparative example provides a Ni@MoS2 / graphite composite absorbing material and a preparation method thereof. The preparation method of the Ni@MoS2 / graphite composite absorbing material is consistent with that of Example 5, but no heat treatment modification is performed, that is, the Ni@MoS2 / graphite composite absorbing material before modification.

[0134] Comparative Example 3

[0135] This comparative example provides a Fe / Ni alloy@MoS2 / graphite composite absorbing material and a preparation method thereof. The preparation method of the Fe / Ni alloy@MoS2 / graphite composite absorbing material is consistent with that of Example 6, but no heat treatment modification is performed, that is, the Fe / Ni alloy@MoS2 / graphite composite absorbing material before modification.

[0136] The modified composite absorbing materials / absorbing materials prepared in Examples 1-12 and Comparative Examples 1-3 were tested for the bandwidth of reflection loss ≤-10 dB and the minimum reflection loss. The specific test results are shown in Table 1.

[0137] Figure 3 The XRD patterns of the modified Fe@MoS2 / graphite composite absorbing materials prepared in Examples 1, 2, 8 and 9 of the present invention are shown. It can be seen from the figure that the diffraction angles of Fe (JCPDS No.008-1441) in Examples 1, 2, 8 and 9 are 44.63°, 44.56°, 44.59° and 44.64°, respectively, corresponding to the (103) crystal plane, and calculated by the Debye-Scherrer formula (D=Kγ / bcosθ), the particle sizes of the respective Fe grains are 12.5nm, 8.59nm, 14.27nm and 27.11nm, respectively.

[0138] Figure 4 The three-dimensional graph of "reflection loss-frequency-thickness" of the modified Fe@MoS2 / graphite composite absorbing material prepared in Example 1 of the present invention is shown. Figure 5The graph of "reflection loss-frequency-thickness" of the modified Fe@MoS2 / graphite composite absorbing material prepared in Example 1 of the present invention is shown. It can be seen from the graph that the modified Fe@MoS2 / graphite composite absorbing material has a minimum reflection loss of -65.07dB at 10.4GHz and a bandwidth of 4.16GHz when the thickness is 2.59mm. An effective absorption bandwidth of electromagnetic waves of 11.52GHz (6.48GHz-18GHz) is obtained in the variable thickness region of 1.91-2.91mm, covering part of the C-band, the entire X-band and the entire Ku-band.

[0139] The reason why the composite absorbing material of Example 1 achieves excellent electromagnetic wave absorption performance is that the appropriate heat treatment temperature improves the internal stress and grain size of the flaky Fe, thereby improving the magnetic loss, and the appropriate amount of Fe3O4 on the surface can improve the magnetic loss performance of the material in the high frequency region. At the same time, the partial oxidation of each component in Example 1 and the partial decomposition of the organic material layer also make the material have a variety of interface polarization modes, thereby improving the dielectric loss capacity.

[0140] Figure 6 The three-dimensional graph of "reflection loss-frequency-thickness" of the Fe@MoS2 / graphite composite absorbing material prepared in Comparative Example 1 of the present invention is shown. Figure 7 The "reflection loss-frequency-thickness" curve of the Fe@MoS2 / graphite composite absorbing material prepared in Comparative Example 1 of the present invention is shown. It can be seen from the figure that the Fe@MoS2 / graphite composite absorbing material achieves a minimum reflection loss of -58.66dB at 11.2GHz and a bandwidth of 3.94GHz when the thickness is 2.2mm. An effective absorption bandwidth of electromagnetic waves of 10.08GHz (7.92GHz-18GHz) is obtained in the variable thickness region of 1.47-2.52mm, covering the entire X-band and the entire Ku-band.

[0141] pass Figure 4 , Figure 5 and Figure 6 , Figure 7 From the comparison, it can be seen that after heat treatment at an appropriate temperature, the minimum reflection loss can be further reduced under the condition of thicker thickness, which can significantly improve the electromagnetic wave absorption performance of the composite absorbing material.

[0142] Table 1

[0143] project Frequency bandwidth with reflection loss ≤-10dB (GHz) Minimum reflection loss (dB) Example 1 4.16 -65.07 Example 2 3.60 -63.91 Example 3 3.52 -60.04 Example 4 4.08 -59.80 Example 5 3.84 -58.03 Example 6 4.23 -57.03 Example 7 3.98 -55.62 Example 8 4.16 -46.11 Example 9 1.04 -14.03 Example 10 3.57 -57.80 Embodiment 11 3.75 -58.32 Example 12 4.02 -57.15 Comparative Example 1 3.94 -58.66 Comparative Example 2 3.62 -53.24 Comparative Example 3 4.10 -55.32

[0144] The test results show that:

[0145] (1) It can be seen from Examples 1 to 4 and Comparative Example 1 that the present invention optimizes the structure and components of the Fe@MoS2 / graphite composite absorbing material by heat treatment at 100°C-350°C, so that the overall performance of the optimized modified Fe@MoS2 / graphite composite absorbing material is significantly improved, especially the ability to absorb electromagnetic waves. Specifically, the bandwidth of the reflection loss ≤-10dB is 3.52GHz-4.16GHz, and the minimum reflection loss can be as low as -59.80dB or below, compared with -58.66dB before modification, and can reach a minimum of -65.07dB;

[0146] It can be seen from Example 5 and Comparative Example 2 that heat treatment can also optimize the structure and components of the Ni@MoS2 / graphite composite absorbing material. The minimum reflection loss can reach -58.03dB compared to -53.24dB before modification, and the bandwidth of the reflection loss ≤-10dB is also increased.

[0147] It can be seen from Example 6 and Comparative Example 3 that heat treatment can also optimize the structure and composition of the Fe / Ni@MoS2 / graphite composite absorbing material. The minimum reflection loss can reach -57.03dB compared to -55.32dB before modification, and the bandwidth of the reflection loss ≤-10dB is also increased.

[0148] (2) It can be seen from Examples 1 and 7 that the present invention can ensure that a trace amount of oxide components are obtained on the surface of the flaky magnetic material by further adjusting the oxygen partial pressure under vacuum conditions to 250 Pa-300 Pa, thereby improving the magnetic loss performance of the material in the high-frequency region. If the oxygen partial pressure is too high and the degree of oxidation is too large, the magnetic permeability will decrease too much, and the electromagnetic wave absorption capacity of the magnetic material @MoS2 / graphite composite absorbing material cannot be effectively improved.

[0149] (3) It can be seen from Examples 1 and 8 to 10 that the present invention can effectively improve the electromagnetic wave absorption capacity of the composite absorbing material by regulating the heat treatment temperature at 100°C-350°C. When the heat treatment temperature is too high, on the one hand, the grain size of the magnetic material in the modified magnetic material @MoS2 / graphite composite absorbing material will be larger than the critical grain size of the magnetic material when the pinning effect occurs. At this time, the movement of the magnetic domain wall becomes freer, thereby further reducing the magnetic loss. On the other hand, too high a heat treatment temperature will aggravate the oxidation degree of the flaky magnetic material, and MoS2 will also undergo a serious oxidation reaction to generate a large amount of Mo. Oxide destroys the layered structure, and the conductivity of Mo oxide is very low. Different from the semiconductor properties of MoS2 itself, a large amount of Mo oxide attached to the surface will significantly reduce the conductivity, significantly reduce the conductivity loss of the material, and reduce the absorption efficiency of electromagnetic waves; in addition, if the heat treatment temperature is too high, the oleic acid on the surface will seriously decompose to generate a large amount of cyclic lactone organic matter, and the surface of the composite material will gradually lose the protection of oleic acid, which will lead to a decrease in the dispersion of the composite absorbing material, and then agglomeration will occur, which is not conducive to the dispersion of the coating in the later stage; and when the heat treatment temperature is too low, the stress cannot be effectively eliminated, and there is no positive effect on the improvement of the electromagnetic wave absorption capacity;

[0150] Therefore, if the heat treatment temperature is too high or too low, it is not conducive to improving the performance. Instead, it will have the opposite effect, causing the performance to be lower than before the modification.

[0151] (4) It can be seen from Example 1 and Example 11-Example 12 that the present invention can better control the composition and morphology of the modified material and change the magnetic loss and dielectric loss capabilities by adjusting the heat treatment time to 1h-3h and the heat treatment rate to 3℃ / min-8℃ / min, thereby adjusting the minimum reflection loss and the effective absorption frequency band to achieve the optimal effect.

[0152] In summary, the present invention optimizes the structure and components of the magnetic material @MoS2 / graphite composite absorbing material, so that the overall performance of the optimized modified magnetic material @MoS2 / graphite composite absorbing material is significantly improved, especially the ability to absorb electromagnetic waves, that is, it has a lower reflection loss value and a wider effective electromagnetic wave absorbing bandwidth.

[0153] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A modified magnetic material @MoS2 / graphite composite absorbing material, characterized in that: The modified magnetic material @MoS2 / graphite composite wave absorbing material is obtained by heat treating the magnetic material @MoS2 / graphite composite wave absorbing material; The grain size of the magnetic material in the modified magnetic material @MoS2 / graphite composite wave absorbing material is larger than the grain size of the magnetic material in the magnetic material @MoS2 / graphite composite wave absorbing material before heat treatment.

2. The modified magnetic material @MoS2 / graphite composite absorbing material according to claim 1, characterized in that: The modified magnetic material @MoS2 / graphite composite absorbing material comprises a lamellar MoS2 / graphite mixed material and a lamellar magnetic material; Preferably, the interlayers of the lamellar MoS2 / graphite mixed material include granular magnetic material; Preferably, the MoS2 lattice of the lamellar MoS2 / graphite mixed material is also doped with magnetic metal elements; Preferably, the surface of the sheet-like magnetic material comprises a protruding structure; Preferably, the protruding structure is a magnetic oxide obtained by oxidation of the sheet-like magnetic material; Preferably, the diameter of the protrusion structure is 7nm-10nm; Preferably, the lamellar MoS2 / graphite mixed powder includes Mo oxide generated by oxidation of MoS2; Preferably, the Mo oxide includes MoO3 and / or MoO2.

3. The modified magnetic material @MoS2 / graphite composite absorbing material according to claim 1 or 2, characterized in that: The surface of the modified magnetic material @MoS2 / graphite composite absorbing material includes a mixed layer of organic materials; Preferably, the organic material mixed layer comprises an organic material and a thermal decomposition product of the organic material.

4. A method for preparing the modified magnetic material @MoS2 / graphite composite absorbing material according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: The magnetic material @MoS2 / graphite composite absorbing material is heat-treated to obtain a modified magnetic material @MoS2 / graphite composite absorbing material.

5. The preparation method according to claim 4, characterized in that: The temperature of the heat treatment is 100°C-350°C, preferably 150°C-300°C; Preferably, the heat treatment time is 1h-3h; Preferably, the heating rate of the heat treatment is 3°C / min-8°C / min; Preferably, the heat treatment is carried out under vacuum conditions; Preferably, the oxygen partial pressure under the vacuum condition is 250Pa-300Pa.

6. The preparation method according to claim 4 or 5, characterized in that: The magnetic material @MoS2 / graphite composite absorbing material is prepared by ball milling; Preferably, the preparation method of the magnetic material @MoS2 / graphite composite absorbing material comprises the following steps: The magnetic powder, lamellar MoS2 / graphite mixed powder and solvent are mixed and ball-milled to obtain the magnetic material@MoS2 / graphite composite absorbing material.

7. The preparation method according to claim 6, characterized in that: The magnetic powder includes any one of carbonyl iron powder, carbonyl nickel powder, carbonyl cobalt powder, iron-nickel alloy powder, iron-cobalt alloy powder or ferrite magnetic powder, or a combination of at least two thereof; Preferably, the magnetic powder is in a granular morphology; Preferably, in the lamellar MoS2 / graphite mixed powder, graphite is dispersed in the lamellar MoS2 matrix; Preferably, in the lamellar MoS2 / graphite mixed powder, the molar ratio of the graphite to the lamellar MoS2 matrix is ​​1:(8-14); Preferably, the molar ratio of the magnetic powder to the lamellar MoS2 / graphite mixed powder is (1-3):

1.

8. The preparation method according to claim 6, characterized in that: The mixing process also includes adding a dispersant for ball milling; Preferably, the dispersant comprises an organic substance containing free carboxyl groups; Preferably, the dispersant comprises oleic acid; Preferably, the solvent comprises anhydrous ethanol; Preferably, the volume ratio of the dispersant to the solvent is 1:(2-5); Preferably, the rotation speed of the ball mill is 400r / min-1000r / min; Preferably, the ball milling time is 18h-24h.

9. The preparation method according to claim 4, characterized in that: The preparation method comprises the following steps: The magnetic material @MoS2 / graphite composite absorbing material is heat treated at 100°C-350°C for 1h-3h under a vacuum condition with an oxygen partial pressure of 250Pa-300Pa to obtain a modified magnetic material @MoS2 / graphite composite absorbing material; The magnetic material @MoS2 / graphite composite absorbing material is prepared by ball milling; the preparation method of the magnetic material @MoS2 / graphite composite absorbing material comprises the following steps: The magnetic powder, lamellar MoS2 / graphite mixed powder, dispersant and solvent are mixed and ball milled at 400r / min-1000r / min for 18h-24h, washed and dried to obtain a magnetic material @MoS2 / graphite composite absorbing material; Among them, the mass ratio of the magnetic powder to the lamellar MoS2 / graphite mixed powder is (1-3):1; in the lamellar MoS2 / graphite mixed powder, graphite is dispersed in the lamellar MoS2 matrix, and the molar ratio of the graphite to the lamellar MoS2 matrix is ​​1:(8-14); the volume ratio of the dispersant to the solvent is 1:(2-5).

10. Application of a modified magnetic material @MoS2 / graphite composite absorbing material, characterized in that: The modified magnetic material @MoS2 / graphite composite absorbing material described in any one of claims 1 to 3, or the modified magnetic material @MoS2 / graphite composite absorbing material prepared by the preparation method described in any one of claims 4 to 9, is applied to a microwave absorbing device to absorb electromagnetic waves.

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