Conductive wave-absorbing adhesive tape and preparation method thereof

Abstract

The invention relates to a conductive wave-absorbing adhesive tape and a preparation method thereof.The conductive wave-absorbing adhesive tape comprises a conductive frame, the upper surface and / or the lower surface of the conductive frame are / is provided with adhesive areas, through holes distributed in an array mode are formed in the conductive frame in the length direction, and the through holes are filled with composite wave-absorbing materials; the composite wave-absorbing material comprises Fe-Co-Ni alloy nanoparticles and a wave-absorbing material, the wave-absorbing material is of a laminated structure, a plurality of holes are formed between two adjacent layers in the laminated structure, the Fe-Co-Ni alloy nanoparticles are mainly distributed in the holes, and the surface layer of the wave-absorbing material is doped with nitrogen and sulfur. The conductive wave-absorbing adhesive tape disclosed by the invention can realize an excellent electromagnetic wave shielding and inhibiting effect in a wide frequency band and multiple directions, and meanwhile, the interference of electromagnetic waves inside and outside is reduced.

Description

Technical Field

[0001] This invention relates to the field of conductive tape technology, and in particular to a conductive absorbing tape and its preparation method. Background Technology

[0002] In high-frequency applications such as 5G communication and millimeter-wave radar, electromagnetic interference is becoming increasingly prominent. Furthermore, with the miniaturization of electronic devices, traditional metal shielding covers are no longer sufficient to meet the electromagnetic compatibility requirements of complex structures. Compared to traditional metal shielding covers, conductive tape not only perfectly conforms to complex curved structures but also significantly reduces production costs, making it the mainstream choice for electromagnetic shielding of electronic devices. Currently, conductive tape is mainly used for internal shielding of plastic housings, cable wrapping, and local protection of printed circuit boards, playing a crucial role in preventing electrostatic breakdown and electromagnetic interference.

[0003] However, traditional conductive tape still has many technical problems: (1) Compared with traditional metal wires or welding, conductive tape has higher resistance, which will cause signal attenuation or power loss, resulting in poor shielding effect of the whole equipment system and is not suitable for high current or high frequency equipment; (2) The edge seams of traditional conductive tape will cause antenna effect, resulting in internal electromagnetic wave leakage or external electromagnetic wave intrusion interference; (3) Traditional conductive tape usually conducts electricity in the vertical direction. Since it cannot form a continuous shielding layer in the horizontal direction, electromagnetic bypass will occur, which limits its flexibility in complex circuit design. Summary of the Invention

[0004] Therefore, it is necessary to provide a conductive absorbing tape and its preparation method to address the above problems. The conductive absorbing tape of the present invention can achieve excellent electromagnetic wave shielding and suppression effects in a wide frequency band and multiple directions, while reducing internal and external electromagnetic wave interference.

[0005] A conductive absorbing tape includes a conductive frame, an adhesive area on the upper and / or lower surface of the conductive frame, and an array of through holes distributed along the length of the conductive frame, the through holes being filled with a composite absorbing material.

[0006] The composite microwave absorbing material includes iron-cobalt-nickel alloy nanoparticles and a microwave absorbing material. The microwave absorbing material has a layered structure, in which multiple cavities are formed between adjacent layers. The iron-cobalt-nickel alloy nanoparticles are mainly distributed in the cavities, and the surface of the microwave absorbing material is doped with nitrogen and sulfur elements.

[0007] In one embodiment, the composite absorbing material satisfies at least one of the following conditions:

[0008] (1) The substrate of the absorbing material is selected from graphite;

[0009] (2) The number of layers of the absorbing material is less than or equal to 10;

[0010] (3) The cavities in the absorbing material are elliptical in shape, with the major axis of the elliptical shape being 500nm~800nm ​​and the minor axis being 400nm~600nm;

[0011] (4) The thickness of the absorbing material is 2μm~3μm;

[0012] (5) The iron-cobalt-nickel alloy nanoparticles include 35wt%~45wt% Fe, 30wt%~40wt% Co, 5wt%~10wt% Ni, 5wt%~10wt% Mn and 5wt%~10wt% Al;

[0013] (6) The particle size of the iron-cobalt-nickel alloy nanoparticles is less than or equal to 150 nm;

[0014] (7) The mass ratio of the iron-cobalt-nickel alloy nanoparticles to the microwave absorbing material is 4:1 to 2:1;

[0015] (8) The total doping rate of nitrogen and sulfur elements in the surface layer of the composite microwave absorbing material is 5%~10%;

[0016] (9) The mass ratio of nitrogen to sulfur is 1:1 to 2:3.

[0017] In one embodiment, the conductive frame satisfies at least one of the following conditions:

[0018] (1) The volume fraction of the through hole is 48%~62.5%;

[0019] (2) The conductive frame has 4 to 6 through holes along the thickness direction inside;

[0020] (3) The conductive frame has 5 to 7 through holes along the width direction inside;

[0021] (4) The thickness of the conductive layer on the surface of the conductive frame is 0.5mm~1mm;

[0022] (5) The substrate of the conductive frame is selected from graphite.

[0023] In one embodiment, the conductive absorbing tape satisfies at least one of the following conditions:

[0024] (1) In the thickness direction of the conductive absorbing tape, the total thickness of the composite absorbing material accounts for 60% to 72%;

[0025] (2) In the width direction of the conductive absorbing tape, the total width of the composite absorbing material accounts for 80%~87%.

[0026] In one embodiment, the surface where the adhesive area is located further includes an array of conductive structures, and satisfies at least one of the following conditions:

[0027] (1) The conductive structure is a pyramid-shaped structure;

[0028] (2) The height of the conductive structure is 30% to 40% greater than the thickness of the adhesive area.

[0029] A method for preparing the conductive absorbing tape as described above includes the following steps:

[0030] The dispersion of the microwave absorbing substrate is mixed evenly with iron-cobalt-nickel alloy nanoparticles and dried to obtain a primary composite material. The primary composite material is then mixed with a nitrogen source and a sulfur source and heat-treated to obtain a composite microwave absorbing material.

[0031] The conductive substrate is mixed with the first adhesive and placed in a mold. After the first curing, the mold is removed to obtain the conductive frame.

[0032] The composite absorbing material is mixed with a second adhesive and placed in the through-hole of the conductive frame. After a second curing, an adhesive area is pre-set on the upper and / or lower surface of the conductive frame to obtain a conductive absorbing tape.

[0033] In one embodiment, the method for preparing the microwave absorbing substrate includes: preparing graphite powder into a graphite dispersion, and obtaining the microwave absorbing substrate by gradient ultrasound and centrifugation, wherein the gradient ultrasound includes first treating at 175W~225W for 1h~2h, and then increasing to 275W~325W for 1h~2h, and the ultrasound adopts a pulse mode, and the temperature of the dispersion is ≤18℃ during the ultrasound process.

[0034] In one embodiment, the method for preparing the iron-cobalt-nickel alloy nanoparticles includes:

[0035] Metal raw materials are mixed and smelted to obtain a first product, wherein the metal raw materials include iron powder, cobalt powder, nickel powder, manganese powder and aluminum powder, and the particle size of the metal raw materials is ≤25μm;

[0036] In a vacuum environment, the first product was thermally reduced to obtain iron-cobalt-nickel alloy nanoparticles.

[0037] In one embodiment, after removing the oxides from the surface of the primary composite material, it is heated and mixed with a nitrogen source and a sulfur source in an organic solvent at 180°C to 200°C for 4 to 6 hours. Then, it is subjected to a first heat treatment at 770°C to 820°C for 1 to 1.5 hours in a protective gas, and then cooled to 720°C to 750°C for a second heat treatment for 1 to 1.5 hours to obtain the composite microwave absorbing material.

[0038] In one embodiment, the preparation method further satisfies at least one of the following conditions:

[0039] (1) The conductive substrate is selected from graphite;

[0040] (2) The mass ratio of the conductive substrate to the first adhesive is 1:(1.5~2.5);

[0041] (3) The mass ratio of the composite absorbing material to the second adhesive is 1:(1.5~2.5);

[0042] (4) The first curing includes holding at 50℃~70℃ for 15min~25min, and then holding at 90℃~110℃ for 20min~40min;

[0043] (5) The second curing includes first holding at 50℃~70℃ for 15min~25min, then holding at 90℃~110℃ for 20min~40min, and then holding at 110℃~130℃ for 20min~40min.

[0044] The conductive absorbing tape of this invention, through its unique structure and materials, improves resistivity while suppressing electromagnetic waves through multiple loss mechanisms—polarization loss, conductivity loss, and magnetic loss. This optimizes absorption performance, effectively suppressing electromagnetic waves across a wide frequency range. The electromagnetic waves are essentially absorbed after passing through the composite absorbing material, significantly reducing secondary propagation interference caused by secondary reflection and minimizing internal and external electromagnetic interference. Furthermore, this conductive absorbing tape overcomes the technical challenge of traditional conductive tapes, which cannot simultaneously achieve multi-angle conductivity and multi-directional shielding and suppression of electromagnetic waves, thus optimizing and improving the overall performance of equipment using the conductive absorbing tape. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the cross-sectional structure of the conductive absorbing tape according to one embodiment of the present invention;

[0047] Figure 2 This is a schematic diagram of the longitudinal cross-sectional structure of the conductive absorbing tape according to one embodiment of the present invention;

[0048] Figure 3This is a schematic diagram of the surface structure of the conductive absorbing tape in one embodiment of the present invention;

[0049] Figure 4 This is a SEM image of the primary composite material obtained in Example 1 of the present invention;

[0050] Figure 5 This is a SEM image of the composite absorbing material prepared in Example 1 of the present invention.

[0051] Reference numerals: 10, conductive frame; 101, adhesive area; 102, conductive structure; 20, composite absorbing material. Detailed Implementation

[0052] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. In this invention, when referring to numerical ranges, unless otherwise specified, such ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Furthermore, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0054] Combination Figure 1 , Figure 2 and Figure 3 As shown, the present invention provides a conductive absorbing tape, including a conductive frame 10, wherein the upper surface and / or the lower surface of the conductive frame 10 are provided with an adhesive area 101, and the conductive frame 10 is provided with an array of through holes distributed along the length direction, wherein the through holes are filled with a composite absorbing material 20.

[0055] The composite microwave absorbing material 20 includes iron-cobalt-nickel alloy nanoparticles and a microwave absorbing material. The microwave absorbing material has a layered structure, in which multiple cavities are formed between adjacent layers. The iron-cobalt-nickel alloy nanoparticles are mainly distributed in the cavities, and the surface of the microwave absorbing material is doped with nitrogen and sulfur elements.

[0056] The conductive absorbing tape of this invention, through its unique structure and materials, improves resistivity while suppressing electromagnetic waves through multiple loss mechanisms—polarization loss, conductivity loss, and magnetic loss. This optimizes absorption performance, effectively suppressing electromagnetic waves across a wide frequency range. The electromagnetic waves are essentially absorbed after passing through the composite absorbing material, significantly reducing secondary propagation interference caused by secondary reflection and minimizing internal and external electromagnetic interference. Furthermore, this conductive absorbing tape overcomes the technical challenge of traditional conductive tapes, which cannot simultaneously achieve multi-angle conductivity and multi-directional shielding and suppression of electromagnetic waves, thus optimizing and improving the overall performance of equipment using the conductive absorbing tape.

[0057] It should be noted that the length, width, and height of the conductive frame 10 correspond to the length, width, and height of the conductive absorbing tape; the through holes are parallel to the long side of the conductive frame 10; the length of the through hole is equal to the length of the conductive frame 10 and the length of the conductive absorbing tape; the present invention does not limit the longitudinal cross-sectional shape of the through hole, including but not limited to rectangles, circles, polygons, and other irregular shapes. Figure 1 and Figure 2 The through hole is exemplified by a rectangle.

[0058] In one embodiment of the present invention, the volume fraction of the through hole is 48% to 62.5%. By adjusting the volume of the through hole, the filling volume of the composite absorbing material 20 can be controlled, which not only further optimizes the structure of the conductive absorbing tape, but also helps to balance the conductivity and electromagnetic wave shielding performance.

[0059] It is understood that the volume fraction of the through-hole includes, but is not limited to, any one of 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 62.5% or any range between two of them.

[0060] In one embodiment of the present invention, the conductive frame 10 has 4 to 6 through holes along the thickness direction. By refining the longitudinal structure of the conductive absorbing tape, it is beneficial to further optimize the multi-directional shielding and electromagnetic wave suppression effect of the conductive absorbing tape.

[0061] In one embodiment of the present invention, the conductive frame 10 has 5 to 7 through holes along the width direction. By refining the design of the transverse structure of the conductive absorbing tape, it is beneficial to further optimize the multi-directional shielding and electromagnetic wave suppression effect of the conductive absorbing tape.

[0062] It should be noted that this application does not impose any restrictions on the specific dimensions of the longitudinal section of the through hole. The design can be made according to the actual application. For example, when the longitudinal section of the through hole is square, the side length of the square can be 2mm to 3mm.

[0063] In one embodiment of the present invention, the thickness of the conductive layer on the surface of the conductive frame 10 is 0.5mm to 1mm. It can be understood that in order to reduce internal and external electromagnetic interference, there is no exposed filling composite absorbing material 20 on the surface of the conductive frame 10, that is, the surface of the conductive absorbing tape is mainly a conductive layer.

[0064] In one embodiment of the present invention, the substrate of the conductive frame 10 is selected from graphite, which is beneficial to further improve the conductivity.

[0065] In one embodiment of the present invention, the total thickness of the composite absorbing material 20 accounts for 60% to 72% in the thickness direction of the conductive absorbing tape. By refining the longitudinal structure of the conductive absorbing tape, it is beneficial to further optimize the multi-directional shielding and electromagnetic wave suppression effect of the conductive absorbing tape.

[0066] In one embodiment of the present invention, the total width of the composite absorbing material 20 accounts for 80% to 87% in the width direction of the conductive absorbing tape. By refining the longitudinal structure of the conductive absorbing tape, it is beneficial to further optimize the multi-directional shielding and electromagnetic wave suppression effect of the conductive absorbing tape.

[0067] In one embodiment of the present invention, the surface where the adhesive region 101 is located further includes an array of conductive structures 102. By designing the conductive structures, it is beneficial to enhance the conductivity between the conductive adhesive and the device.

[0068] Preferably, the conductive structure 102 is a pyramid-shaped structure, which realizes a conical contact design and helps to further enhance the conductivity between the conductive adhesive and the device.

[0069] Preferably, the height of the conductive structure 102 is 30% to 40% greater than the thickness of the adhesive region 101, which helps to further ensure the conductivity between the conductive adhesive and the device.

[0070] It is understood that the present invention does not limit the material of the conductive structure 102, including but not limited to conductive metals such as silver and copper.

[0071] Through long-term experiments, the applicant discovered that although the combination of conventional magnetic materials and microwave absorbing materials can improve both conductivity and magnetic loss characteristics, it can usually only absorb electromagnetic waves in a specific frequency band, resulting in a single absorption frequency band. Furthermore, when electromagnetic waves approach the microwave absorbing material, there is still a certain problem of secondary electromagnetic wave reflection, which is not conducive to the transmission of electromagnetic wave signals.

[0072] Based on this, the present invention provides a composite microwave absorbing material, comprising iron-cobalt-nickel alloy nanoparticles and a microwave absorbing material. The microwave absorbing material has a layered structure, in which multiple cavities are formed between adjacent layers. The iron-cobalt-nickel alloy nanoparticles are mainly distributed in the cavities, and the surface layer of the microwave absorbing material is doped with nitrogen and sulfur elements.

[0073] The composite absorbing material of this invention achieves electromagnetic wave suppression through the synergistic effect of iron-cobalt-nickel alloy nanoparticles, the absorbing material itself, and nitrogen-sulfur co-doping on its surface. This suppresses multiple loss mechanisms, including polarization loss, conductivity loss, and magnetic loss, thus optimizing the absorption effect. It effectively absorbs and suppresses electromagnetic waves over a wide frequency range, especially achieving tunable absorption across the entire 20MHz to 1.5GHz frequency range. This allows electromagnetic waves to be essentially absorbed after passing through the composite absorbing material, thereby significantly reducing electromagnetic wave secondary propagation interference caused by secondary reflection.

[0074] In the laminated structure of the absorbing material, multiple holes are formed between adjacent layers. Electromagnetic waves can be absorbed by multiple reflections inside the holes. It is understood that the present invention does not restrict the distribution of holes between adjacent layers; they can be arranged in an ordered or disordered manner.

[0075] In one embodiment of the present invention, the substrate of the absorbing material is selected from graphite. Graphite has a high electron mobility. When electromagnetic waves are incident, the free electrons inside it will generate strong oscillations, converting electromagnetic energy into heat energy through conductive loss. At the same time, the large specific surface area of ​​graphite can also cause electromagnetic waves to be reflected and scattered multiple times, thereby enhancing the absorption efficiency.

[0076] In one embodiment of the present invention, the number of layers of the absorbing material is less than or equal to 10, which not only helps to improve the structural stability of the composite absorbing material, but also improves the surface doping effect.

[0077] Preferably, the substrate of the absorbing material is selected from graphite and the number of layers is less than or equal to 10. It is understood that the number of layers includes, but is not limited to, any value of 2, 4, 6, 8, or 10 layers or any range between the two.

[0078] Further preferably, the thickness of the absorbing material is 2μm to 3μm, including but not limited to any one of 2μm, 2.2μm, 2.5μm, 2.7μm, and 3μm or any range between two of them, which is beneficial to further improve the absorption effect and expand the absorption frequency band.

[0079] In one embodiment of the present invention, the cavities in the absorbing material are preferably elliptical, with the major axis of the elliptical shape preferably being 500nm~800nm ​​and the minor axis preferably being 400nm~600nm. This is more conducive to increasing the relative size of the cavities in the absorbing material, enabling the absorbing material to better reflect and absorb electromagnetic waves.

[0080] It is understood that the major axis of the elliptical shape includes, but is not limited to, any point value of 500nm, 600nm, 700nm, 800nm ​​or any range of values ​​between two of them, and the minor axis includes, but is not limited to, any point value of 400nm, 450nm, 500nm, 550nm, 600nm or any range of values ​​between two of them; in other embodiments, the cavities of the absorbing material may also be other shapes such as circular, conical or cylindrical, and the present invention does not limit them.

[0081] Compared to pure nickel or iron-nickel alloys, iron-cobalt-nickel alloys have better eddy current loss performance. Combining iron-cobalt-nickel alloys with graphite is beneficial for further widening the low-frequency magnetic loss band.

[0082] Preferably, the iron-cobalt-nickel alloy nanoparticles comprise 35wt%~45wt% Fe, 30wt%~40wt% Co, 5wt%~10wt% Ni, 5wt%~10wt% Mn, and 5wt%~10wt% Al. The iron-cobalt-nickel alloy with the above components, when combined with graphite, can significantly improve the charge transport efficiency of the composite microwave absorbing material and enhance its conductivity.

[0083] Preferably, the particle size of the iron-cobalt-nickel alloy nanoparticles is less than or equal to 150 nm, which is more conducive to the full embedding of the iron-cobalt-nickel alloy nanoparticles into the cavities of the absorbing material, optimizing the structure of the composite absorbing material, thereby improving the absorption performance and reducing secondary reflection interference.

[0084] In one embodiment of the present invention, the mass ratio of the iron-cobalt-nickel alloy nanoparticles to the microwave absorbing material is 4:1 to 2:1. By adjusting the mass ratio of the iron-cobalt-nickel alloy nanoparticles to the microwave absorbing material, it is beneficial to further optimize the structure of the composite microwave absorbing material, thereby improving the microwave absorption performance and reducing secondary reflection interference.

[0085] In one embodiment of the present invention, the total doping rate of nitrogen and sulfur elements in the surface layer of the composite absorbing material is 5% to 10%, including but not limited to any one of 5%, 6%, 7%, 8%, 10% or any range between the two.

[0086] In one embodiment of the present invention, the mass ratio of nitrogen to sulfur is 1:1 to 2:3, including but not limited to any one of 1:1, 4:5, 6:7, 3:4, 2:3 or any range between the two.

[0087] By adjusting the doping amounts of nitrogen and sulfur elements in the surface layer of the composite absorbing material, it is beneficial to improve the high polarization loss performance of the composite absorbing material, optimize the synergistic effect of multiple losses, thereby further improving the electromagnetic wave absorption effect and reducing secondary reflection interference.

[0088] It should be noted that the mass percentage of nitrogen and sulfur elements in the surface layer of the composite microwave absorbing material represents the total doping rate of nitrogen and sulfur elements in the surface layer of the composite microwave absorbing material.

[0089] This invention provides a method for preparing the conductive absorbing tape as described above, comprising the following steps:

[0090] Step 1: Mix the dispersion of the microwave absorbing substrate with iron-cobalt-nickel alloy nanoparticles evenly, and dry to obtain a primary composite material. Mix the primary composite material with a nitrogen source and a sulfur source and heat treat to obtain a composite microwave absorbing material.

[0091] Step 2: Mix the conductive substrate with the first adhesive and place it in a mold. After the first curing, remove the mold to obtain the conductive frame.

[0092] Step 3: Mix the composite absorbing material with the second adhesive and place it in the through hole of the conductive frame. After a second curing, pre-set adhesive areas on the upper and / or lower surfaces of the conductive frame to obtain conductive absorbing tape.

[0093] In step one, a special filtering structure channel is formed by first compositing the absorbing substrate with iron-cobalt-nickel alloy nanoparticles. Then, nitrogen and sulfur are co-doped on the surface of the composite material. This allows the composite absorbing material to meet the requirements of electrical and magnetic losses, while also synergizing with surface polarization loss. As a result, the composite absorbing material has multiple loss mechanisms of polarization loss, conductivity loss, and magnetic loss, thereby achieving broadband tunable absorption, reducing secondary reflection, and improving absorption rate.

[0094] In one embodiment of the present invention, the preferred method for preparing the microwave absorbing substrate includes: preparing graphite powder into a graphite dispersion, obtaining the microwave absorbing substrate by gradient ultrasound and centrifugation, using specific gradient ultrasound to peel and delaminate the graphite, and combining it with a pulse mode, which is beneficial to form a certain space between adjacent layers in the graphite, and then screening out a thinner microwave absorbing substrate by centrifugation.

[0095] The gradient ultrasound process involves initial treatment at 175W~225W for 1-2 hours, followed by treatment at 275W~325W for another 1-2 hours. The ultrasound is performed in pulse mode, and the temperature of the dispersion is ≤18℃ during the process. It should be noted that pulse mode means the ultrasound waves are emitted in periodic short pulses with intermittent pauses. The duty cycle is typically 0.1%~50%, preferably 50%, with intervals of 5-10 minutes. For example, a cycle can be defined as 5 minutes of ultrasound followed by a 5-minute pause.

[0096] Preferably, the solvent for the graphite dispersion is water. Before gradient ultrasonication, the dispersion is initially carried out by magnetic stirring for 30 to 60 minutes. Centrifugation is preferably carried out in stages. The first stage of centrifugation is performed at a speed of 300 to 400 rpm for 0.5 to 1 hour to remove large unpeeled graphite particles. The second stage of centrifugation is performed at a speed of 5000 to 10000 rpm for 0.5 to 1 hour, which is more conducive to screening out thinner microwave absorbing substrates.

[0097] In one embodiment of the present invention, the solvent in the dispersion of the microwave absorbing substrate is preferably an organic solvent, including but not limited to ethanol. Preferably, adding a small amount of ionic liquid to the dispersion of the microwave absorbing substrate can reduce graphite agglomeration.

[0098] In one embodiment of the present invention, the method for preparing the iron-cobalt-nickel alloy nanoparticles includes:

[0099] Metal raw materials are mixed and smelted to obtain a first product, wherein the metal raw materials include iron powder, cobalt powder, nickel powder, manganese powder and aluminum powder, and the particle size of the metal raw materials is ≤25μm;

[0100] In a vacuum environment, the first product was thermally reduced to obtain iron-cobalt-nickel alloy nanoparticles.

[0101] Preferably, the metal raw materials are mixed by intermittent high-energy ball milling, for example, under argon protection, ball milling at 30 rpm for 24 hours, with a 10-15 minute pause every 2 hours to cool down, and 1%-2% stearic acid added as a process control agent. The metal raw materials preferably have a purity ≥99.9%.

[0102] As a preferred method, the mixed metal raw materials are pressed into billets and then melted in an electric arc melting furnace under a vacuum argon atmosphere. Repeated melting multiple times can ensure uniform melting.

[0103] As a preferred embodiment, the thermal reduction process includes placing the first product in a copper crucible, evacuating it, and then introducing a protective gas containing hydrogen. After the first product evaporates, it reacts with hydrogen atoms to generate iron-cobalt-nickel alloy nanoparticles, which are then collected by cyclone separation.

[0104] In one embodiment of the present invention, before the primary composite material is dried, the mixing system of the dispersion of the microwave absorbing substrate and the iron-cobalt-nickel alloy nanoparticles is adjusted to an acidic environment, which is beneficial to remove oxides from the surface of the primary composite material.

[0105] In one embodiment of the present invention, after removing the oxides on the surface of the primary composite material, it is heated and mixed with a nitrogen source and a sulfur source in an organic solvent at 180°C to 200°C for 4 to 6 hours. Then, it is subjected to a first heat treatment at 770°C to 820°C for 1 to 1.5 hours in a protective gas, and then cooled to 720°C to 750°C for a second heat treatment for 1 to 1.5 hours to obtain the composite microwave absorbing material.

[0106] Preferably, the nitrogen source is ammonia water and the sulfur source is sodium sulfide.

[0107] In step two, the conductive frame is prepared using a mold method, which is simple and convenient. This invention does not limit the material of the mold; for example, non-woven fabric can be used as the mold template.

[0108] In one embodiment of the present invention, the conductive substrate is selected from graphite, which is beneficial to further improve the conductivity.

[0109] In one embodiment of the present invention, the mass ratio of the conductive substrate to the first adhesive is 1:(1.5~2.5), including but not limited to any one of 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.5 or any range between the two.

[0110] In one embodiment of the present invention, it is preferable to mix the conductive substrate with the first adhesive in batches, which helps to avoid the agglomeration of the conductive substrate.

[0111] In one embodiment of the present invention, the first curing includes holding the mixture at 50°C to 70°C for 15 min to 25 min, and then holding it at 90°C to 110°C for 20 min to 40 min, so that the mixture is initially cured and the main mold is removed to form a conductive frame structure.

[0112] It is understandable that, in the subsequent preparation process, in order to avoid placing the composite absorbing material on the surface of the conductive frame structure, the internal mold of the conductive frame structure can be removed first, and the mold covering the surface of the conductive frame structure can be removed after the composite absorbing material has been initially cured in step three.

[0113] In one embodiment of the present invention, the mass ratio of the composite absorbing material to the second adhesive is 1:(1.5~2.5), including but not limited to any one of 1:1.5, 1:1.8, 1:2, 1:2.2, 1:2.5 or any range between the two.

[0114] It should be noted that the present invention does not limit the types of the first adhesive and the second adhesive; conventional commercial adhesives can be used. The first adhesive and the second adhesive can be the same or different.

[0115] In one embodiment of the present invention, the second curing includes first holding at 50°C to 70°C for 15 min to 25 min, then holding at 90°C to 110°C for 20 min to 40 min, and then holding at 110°C to 130°C for 20 min to 40 min, so that the conductive frame, i.e. the composite microwave absorbing material filling its openings, is completely cured.

[0116] The conductive absorbing tape and its preparation method will be further described below through specific embodiments. However, those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0117] Example 1

[0118] S1. Add 1g of graphite powder to 50mL of aqueous solution and stir magnetically for 30min for initial dispersion. Then, sonicate at 200W for 1h, then increase to 300W for 1h, with a pulse mode of 50% duty cycle. The temperature of the dispersion during sonication should be ≤18℃. Centrifuge the dispersion at 400rpm / h for 30min to remove large unpeeled graphite particles, then centrifuge at 8000rpm / h for 30min to obtain the precipitate as the microwave absorbing substrate. Redisperse the microwave absorbing substrate in ethanol for later use, and add a small amount of ionic liquid to reduce agglomeration.

[0119] S2. Metal powders Fe, Co, Ni, Mn, and Al with a purity ≥ 99.9% were mixed in a mass ratio of 6:5:1:1:1 and placed in a high-energy ball mill jar (ball-to-powder ratio 5:1). Under argon protection, the mixture was ball-milled at 300 rpm for 24 hours, with a 15-minute pause every 2 hours to cool it down. 1% stearic acid was added as a process control agent. The ball-milled powder was pressed into a compact and melted in an electric arc melting furnace under a vacuum argon atmosphere at a current of 500 A. The melting was repeated 5 times to ensure uniformity, ultimately yielding a precipitate. The precipitate was placed in a copper crucible and evacuated to a vacuum of 2 × 10⁻⁶. - After passing through ³Pa, a mixture of hydrogen and argon gas is introduced. After the precipitate evaporates, it reacts with hydrogen atoms to generate iron-cobalt-nickel alloy nanoparticles, which are then collected by cyclone separation.

[0120] S3. A dispersion containing 100g of microwave absorbing substrate is mixed and stirred with 300g of iron-cobalt-nickel alloy nanoparticles to embed the nanoparticles into the microwave absorbing substrate. Hydrochloric acid is then added to create an acidic environment to remove surface oxides. After drying, a primary composite material is obtained. Its SEM image is shown below. Figure 4 As shown.

[0121] S4. Dissolve 300g of the primary composite material, 10g of ammonia, and 10g of sodium sulfide in an ethanol solution, heat at 180℃ for 6 hours, then treat in argon atmosphere at 800℃ for 1 hour, followed by further treatment at 750℃ for 1 hour to obtain the composite microwave absorbing material. Its SEM image is shown below. Figure 5 As shown.

[0122] S5. The graphite precipitate obtained in S1 is used as a conductive substrate and mixed with epoxy resin adhesive in batches, wherein the mass ratio of graphite to adhesive is 1:2. During mixing, the mixture is stirred at a low speed of 200 rpm for 30 minutes to form a mixture. A vertical grid template is prepared using non-woven fabric. The mixture is injected into the grid mold, dried at 60℃ for 20 minutes, and then the temperature is increased to 100℃ for preliminary curing for 30 minutes. The central mold is removed to form a through hole, while the surrounding mold is retained.

[0123] S6. Mix the composite absorbing material obtained in S4 with epoxy resin adhesive, wherein the mass ratio of the composite absorbing material to the adhesive is 1:2. Stir at a low speed of 200 rpm for 30 minutes to form a mixture. Inject the mixture into the through-hole, dry at 60℃ for 20 minutes, then raise the temperature to 100℃ for preliminary curing for 30 minutes. After removing the surrounding mold, cure completely at 120℃ for 30 minutes. Use the lower surface of the obtained conductive frame as the preset adhesive area to obtain the conductive absorbing tape.

[0124] Example 2

[0125] S1. Add 1g of graphite powder to 50mL of aqueous solution and stir magnetically for 30min for initial dispersion. Then, sonicate at 175W for 1h, then increase to 275W for 1h, with a pulse mode of 50% duty cycle. The temperature of the dispersion during sonication should be ≤18℃. Centrifuge the dispersion at 400rpm / h for 30min to remove large unpeeled graphite particles, then centrifuge at 8000rpm / h for 30min to obtain the precipitate as the microwave absorbing substrate. Redisperse the microwave absorbing substrate in ethanol for later use, and add a small amount of ionic liquid to reduce agglomeration.

[0126] S2. Metal powders Fe, Co, Ni, Mn, and Al with a purity ≥ 99.9% were mixed in a mass ratio of 7:6:1:1:1 and placed in a high-energy ball mill jar (ball-to-powder ratio 5:1). Under argon protection, the mixture was ball-milled at 300 rpm for 24 hours, with a 15-minute pause every 2 hours to cool it down. 1% stearic acid was added as a process control agent. The ball-milled powder was pressed into a compact and melted in an electric arc melting furnace under a vacuum argon atmosphere at a current of 500 A. The melting was repeated 5 times to ensure uniformity, ultimately yielding a precipitate. The precipitate was placed in a copper crucible and evacuated to a vacuum of 2 × 10⁻⁶. - After passing through ³Pa, a mixture of hydrogen and argon gas is introduced. After the precipitate evaporates, it reacts with hydrogen atoms to generate iron-cobalt-nickel alloy nanoparticles, which are then collected by cyclone separation.

[0127] S3. Mix and stir a dispersion containing 100g of microwave absorbing substrate with 200g of iron-cobalt-nickel alloy nanoparticles to embed the iron-cobalt-nickel alloy nanoparticles into the microwave absorbing substrate. Then add hydrochloric acid to form an acidic environment to remove the oxides on the surface. After drying, a primary composite material is obtained.

[0128] S4. Dissolve 400g of primary composite material, 10g of ammonia water, and 10g of sodium sulfide in an ethanol solution, heat at 180℃ for 4h, then treat in argon at 770℃ for 1h, and then continue to treat at 720℃ for 1h to obtain composite microwave absorbing material.

[0129] S5. The graphite precipitate obtained in S1 is used as a conductive substrate and mixed with epoxy resin adhesive in batches, wherein the mass ratio of graphite to adhesive is 1:1.5. During mixing, the mixture is stirred at a low speed of 200 rpm for 30 minutes to form a mixture. A vertical grid template is prepared using non-woven fabric. The mixture is injected into the grid mold, dried at 50℃ for 15 minutes, and then the temperature is increased to 90℃ for preliminary curing for 20 minutes. The central mold is removed to form a through hole, while the surrounding mold is retained.

[0130] S6. Mix the composite absorbing material obtained in S4 with epoxy resin adhesive, wherein the mass ratio of the composite absorbing material to the adhesive is 1:1.5. Stir at a low speed of 200 rpm for 30 minutes to form a mixture. Inject the mixture into the through holes, dry at 50℃ for 15 minutes, then raise the temperature to 90℃ for preliminary curing for 20 minutes. After removing the surrounding mold, cure completely at 110℃ for 20 minutes. Use the lower surface of the obtained conductive frame as the preset adhesive area to obtain the conductive absorbing tape.

[0131] Example 3

[0132] S1. Add 1g of graphite powder to 50mL of aqueous solution and stir magnetically for 30min for initial dispersion. Then, sonicate at 200W for 1.5h, then increase to 300W for 1.5h, with a pulse mode of 50% duty cycle. The temperature of the dispersion during sonication should be ≤18℃. Then, centrifuge the dispersion at 400rpm / h for 30min to remove large unpeeled graphite particles, and then centrifuge at 8000rpm / h for 30min to obtain the precipitate as the microwave absorbing substrate. Take the microwave absorbing substrate and redisperse it in ethanol for later use, and add a small amount of ionic liquid to reduce agglomeration.

[0133] S2. Metal powders Fe, Co, Ni, Mn, and Al with a purity ≥ 99.9% were mixed in a mass ratio of 16:14:3:3:3 and placed in a high-energy ball mill jar (ball-to-powder ratio 5:1). Under argon protection, the mixture was ball-milled at 300 rpm for 24 hours, with a 15-minute pause every 2 hours to cool it down. 1% stearic acid was added as a process control agent. The ball-milled powder was pressed into a compact and melted in an electric arc melting furnace under a vacuum argon atmosphere at a current of 500 A. The melting was repeated 5 times to ensure uniformity, ultimately yielding a precipitate. The precipitate was placed in a copper crucible and evacuated to a vacuum of 2 × 10⁻⁶. - After passing through ³Pa, a mixture of hydrogen and argon gas is introduced. After the precipitate evaporates, it reacts with hydrogen atoms to generate iron-cobalt-nickel alloy nanoparticles, which are then collected by cyclone separation.

[0134] S3. Mix and stir a dispersion containing 100g of microwave absorbing substrate with 300g of iron-cobalt-nickel alloy nanoparticles to embed the iron-cobalt-nickel alloy nanoparticles into the microwave absorbing substrate. Then add hydrochloric acid to form an acidic environment to remove the oxides on the surface. After drying, a primary composite material is obtained.

[0135] S4. Dissolve 300g of the primary composite material, 10g of ammonia water, and 10g of sodium sulfide in an ethanol solution, heat at 190℃ for 1.25h, then treat in argon at 800℃ for 1.25h, and then continue to treat at 730℃ for 1.25h to obtain the composite microwave absorbing material.

[0136] S5. The graphite precipitate obtained in S1 is used as a conductive substrate and mixed with epoxy resin adhesive in batches, wherein the mass ratio of graphite to adhesive is 1:2.5. During mixing, the mixture is stirred at a low speed of 200 rpm for 30 minutes to form a mixture. A vertical grid template is prepared using non-woven fabric. The mixture is injected into the grid mold and dried at 70℃ for 25 minutes. Then, the temperature is increased to 110℃ for preliminary curing for 40 minutes. The central mold is removed to form a through hole, while the surrounding mold is retained.

[0137] S6. Mix the composite absorbing material obtained in S4 with epoxy resin adhesive, wherein the mass ratio of the composite absorbing material to the adhesive is 1:2.5. Stir at a low speed of 200 rpm for 30 minutes to form a mixture. Inject the mixture into the through holes, dry at 70℃ for 25 minutes, then raise the temperature to 110℃ for preliminary curing for 40 minutes. After removing the surrounding mold, cure completely at 130℃ for 40 minutes. Use the middle part of the lower surface of the obtained conductive frame as the preset adhesive area. Mix the elastic adhesive silicone with the conductive filler silver powder to prepare pyramid-shaped conductive contact points, and the height of the conductive structure is 40% greater than the thickness of the adhesive area to obtain the conductive absorbing tape.

[0138] Example 4

[0139] S1. Add 1g of graphite powder to 50mL of aqueous solution and stir magnetically for 30min for initial dispersion. Then, sonicate at 225W for 2h, then increase to 325W for 2h, with a pulse mode of 50% duty cycle. The temperature of the dispersion during sonication should be ≤18℃. Centrifuge the dispersion at 400rpm / h for 30min to remove large unpeeled graphite particles, then centrifuge at 8000rpm / h for 30min to obtain the precipitate as the microwave absorbing substrate. Redisperse the microwave absorbing substrate in ethanol for later use, and add a small amount of ionic liquid to reduce agglomeration.

[0140] S2. Metal powders Fe, Co, Ni, Mn, and Al with a purity ≥ 99.9% were mixed in a mass ratio of 9:8:2:2:2 and placed in a high-energy ball mill jar (ball-to-powder ratio 5:1). Under argon protection, the mixture was ball-milled at 300 rpm for 24 hours, with a 15-minute pause every 2 hours to cool it down. 1% stearic acid was added as a process control agent. The ball-milled powder was pressed into a compact and melted in an electric arc melting furnace under a vacuum argon atmosphere at a current of 500 A. The melting was repeated 5 times to ensure uniformity, ultimately yielding a precipitate. The precipitate was placed in a copper crucible and evacuated to a vacuum of 2 × 10⁻⁶. - After passing through ³Pa, a mixture of hydrogen and argon gas is introduced. After the precipitate evaporates, it reacts with hydrogen atoms to generate iron-cobalt-nickel alloy nanoparticles, which are then collected by cyclone separation.

[0141] S3. Mix and stir a dispersion containing 100g of microwave absorbing substrate with 400g of iron-cobalt-nickel alloy nanoparticles to embed the iron-cobalt-nickel alloy nanoparticles into the microwave absorbing substrate. Then add hydrochloric acid to form an acidic environment to remove the oxides on the surface. After drying, a primary composite material is obtained.

[0142] S4. Dissolve 250g of the primary composite material, 10g of ammonia water, and 10g of sodium sulfide in an ethanol solution, heat at 200℃ for 6h, then treat in argon at 820℃ for 1.5h, and then continue to treat at 750℃ for 1.5h to obtain the composite microwave absorbing material.

[0143] S5. The graphite precipitate obtained in S1 is used as a conductive substrate and mixed with epoxy resin adhesive in batches, wherein the mass ratio of graphite to adhesive is 1:1.5. During mixing, the mixture is stirred at a low speed of 200 rpm for 30 minutes to form a mixture. A vertical grid template is prepared using non-woven fabric. The mixture is injected into the grid mold, dried at 60℃ for 20 minutes, and then the temperature is raised to 100℃ for preliminary curing for 30 minutes. The central mold is removed to form a through hole, while the surrounding mold is retained.

[0144] S6. Mix the composite absorbing material obtained in S4 with epoxy resin adhesive, wherein the mass ratio of the composite absorbing material to the adhesive is 1:2.5. Stir at a low speed of 200 rpm for 30 minutes to form a mixture. Inject the mixture into the through holes, dry at 60°C for 20 minutes, then raise the temperature to 100°C for preliminary curing for 30 minutes. After removing the surrounding mold, cure completely at 120°C for 30 minutes. Use the middle part of the lower surface of the obtained conductive frame as the preset adhesive area. Mix the elastic adhesive silicone with conductive filler silver powder to prepare pyramid-shaped conductive contact points, and the height of the conductive structure is 30% greater than the thickness of the adhesive area to obtain conductive absorbing tape.

[0145] Example 5

[0146] The difference between Example 5 and Example 1 is that gradient ultrasound was not used when preparing the microwave absorbing substrate. After initial dispersion, it was directly centrifuged after ultrasonic treatment at 250W for 2 hours.

[0147] Comparative Example 1

[0148] The difference between Comparative Example 1 and Example 1 is that an equal amount of iron-chromium-cobalt alloy nanoparticles were used instead of iron-cobalt-nickel alloy nanoparticles, and the composite material was prepared by mixing it with the dispersion of the microwave absorbing substrate.

[0149] Comparative Example 2

[0150] The difference between Comparative Example 2 and Example 1 is that an equal amount of silver nanoparticles were used instead of iron-cobalt-nickel alloy nanoparticles, and the composite material was prepared by mixing it with the dispersion of the microwave absorbing substrate.

[0151] Comparative Example 3

[0152] The difference between Comparative Example 3 and Example 1 is that no sulfur source was used; only a nitrogen source was used to dope and prepare the composite microwave absorbing material.

[0153] Comparative Example 4

[0154] The difference between Comparative Example 4 and Example 1 is that no nitrogen source was used; only a sulfur source was used to dope and prepare the composite microwave absorbing material.

[0155] Comparative Example 5

[0156] The difference between Comparative Example 5 and Example 1 is that no doping was performed, and the primary composite material was directly used as the composite microwave absorbing material.

[0157] Comparative Example 6

[0158] Comparative Example 6 uses the same conductive material and composite absorbing material as Example 1. The difference is that no conductive frame is prepared. Instead, a structure of alternating conductive and absorbing layers is prepared directly by coating. There are 4 conductive layers and 4 absorbing layers. The thicknesses of the conductive and absorbing layers are 1 mm and 1 mm, respectively.

[0159] The microwave absorbing substrates, iron-cobalt-nickel alloy nanoparticles, composite microwave absorbing materials, and conductive microwave absorbing tapes prepared in all embodiments were characterized (characterization methods included SEM), and the results are as follows: Figure 4 , Figure 5 And as shown in Tables 1 to 4.

[0160] Table 1

[0161]

[0162] Table 2

[0163]

[0164] Table 3

[0165]

[0166] Table 4

[0167]

[0168] The conductive absorbing tapes prepared in all embodiments and comparative examples were subjected to performance tests (refer to GB / T32596 for testing absorption bandwidth and absorption loss), and the results are shown in Table 5.

[0169] Table 5

[0170]

[0171] As shown in Tables 1-5, the conductive absorbing tape provided by this invention achieves adjustable absorption across the entire frequency range of 20MHz to 1.5GHz, while maintaining high conductivity. Comparative Examples 1 and 2, using iron-chromium-cobalt alloy and nano-silver particles respectively to suppress electromagnetic waves in terms of magnetic loss, suffer from a single permeability frequency response, resulting in poor absorption at high frequencies. Comparative Examples 3 and 4, using nitrogen doping and sulfur doping respectively, optimize dielectric loss, but lack magnetic loss components and exhibit uneven doping, leading to decreased high-frequency absorption and significant fluctuations in the absorption frequency band. Comparative Example 5 shows decreased high-frequency absorption and significant fluctuations in the absorption frequency band. Comparative Example 6 employs a conventional layered structure, resulting in significantly deteriorated absorption performance and conductivity.

[0172] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0173] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A conductive absorbing tape, characterized in that, The device includes a conductive frame, the upper surface and / or the lower surface of which are provided with adhesive areas, and the interior of the conductive frame is provided with an array of through holes distributed along the length direction, the through holes being filled with a composite microwave absorbing material. The composite microwave absorbing material includes iron-cobalt-nickel alloy nanoparticles and a microwave absorbing material. The microwave absorbing material has a layered structure, in which multiple cavities are formed between adjacent layers. The iron-cobalt-nickel alloy nanoparticles are mainly distributed in the cavities, and the surface of the microwave absorbing material is doped with nitrogen and sulfur elements.

2. The conductive absorbing tape according to claim 1, characterized in that, The composite absorbing material satisfies at least one of the following conditions: (1) The substrate of the absorbing material is selected from graphite; (2) The number of layers of the absorbing material is less than or equal to 10; (3) The cavities in the absorbing material are elliptical in shape, with the major axis of the elliptical shape being 500nm~800nm ​​and the minor axis being 400nm~600nm; (4) The thickness of the absorbing material is 2μm~3μm; (5) The iron-cobalt-nickel alloy nanoparticles include 35wt%~45wt% Fe, 30wt%~40wt% Co, 5wt%~10wt% Ni, 5wt%~10wt% Mn and 5wt%~10wt% Al; (6) The particle size of the iron-cobalt-nickel alloy nanoparticles is less than or equal to 150 nm; (7) The mass ratio of the iron-cobalt-nickel alloy nanoparticles to the microwave absorbing material is 4:1 to 2:1; (8) The total doping rate of nitrogen and sulfur elements in the surface layer of the composite microwave absorbing material is 5%~10%; (9) The mass ratio of nitrogen to sulfur is 1:1 to 2:

3.

3. The conductive absorbing tape according to claim 1, characterized in that, The conductive frame satisfies at least one of the following conditions: (1) The volume fraction of the through hole is 48%~62.5%; (2) The conductive frame has 4 to 6 through holes along the thickness direction inside; (3) The conductive frame has 5 to 7 through holes along the width direction inside; (4) The thickness of the conductive layer on the surface of the conductive frame is 0.5mm~1mm; (5) The substrate of the conductive frame is selected from graphite.

4. The conductive absorbing tape according to claim 1, characterized in that, The conductive absorbing tape satisfies at least one of the following conditions: (1) In the thickness direction of the conductive absorbing tape, the total thickness of the composite absorbing material accounts for 60% to 72%; (2) In the width direction of the conductive absorbing tape, the total width of the composite absorbing material accounts for 80%~87%.

5. The conductive absorbing tape according to claim 1, characterized in that, The surface where the adhesive area is located also includes an array of conductive structures, and satisfies at least one of the following conditions: (1) The conductive structure is a pyramid-shaped structure; (2) The height of the conductive structure is 30% to 40% greater than the thickness of the adhesive area.

6. A method for preparing the conductive absorbing tape according to any one of claims 1 to 5, characterized in that, Includes the following steps: The dispersion of the microwave absorbing substrate is mixed evenly with iron-cobalt-nickel alloy nanoparticles and dried to obtain a primary composite material. The primary composite material is then mixed with a nitrogen source and a sulfur source and heat-treated to obtain a composite microwave absorbing material. The conductive substrate is mixed with the first adhesive and placed in a mold. After the first curing, the mold is removed to obtain the conductive frame. The composite absorbing material is mixed with a second adhesive and placed in the through-hole of the conductive frame. After a second curing, an adhesive area is pre-set on the upper and / or lower surface of the conductive frame to obtain a conductive absorbing tape.

7. The method for preparing the conductive absorbing tape according to claim 6, characterized in that, The method for preparing the microwave absorbing substrate includes: preparing graphite powder into a graphite dispersion, and obtaining the microwave absorbing substrate by gradient ultrasound and centrifugation. The gradient ultrasound includes first treating at 175W~225W for 1h~2h, and then increasing to 275W~325W for 1h~2h. The ultrasound adopts a pulse mode, and the temperature of the dispersion is ≤18℃ during the ultrasound process.

8. The method for preparing the conductive absorbing tape according to claim 6, characterized in that, The preparation method of the iron-cobalt-nickel alloy nanoparticles includes: Metal raw materials are mixed and smelted to obtain a first product, wherein the metal raw materials include iron powder, cobalt powder, nickel powder, manganese powder and aluminum powder, and the particle size of the metal raw materials is ≤25μm; In a vacuum environment, the first product was thermally reduced to obtain iron-cobalt-nickel alloy nanoparticles.

9. The method for preparing the conductive absorbing tape according to claim 6, characterized in that, After removing the surface oxides of the primary composite material, it is heated and mixed with nitrogen and sulfur sources in an organic solvent at 180°C to 200°C for 4 to 6 hours. Then, it is subjected to a first heat treatment at 770°C to 820°C for 1 to 1.5 hours in a protective gas environment, followed by a second heat treatment at 720°C to 750°C for 1 to 1.5 hours to obtain the composite microwave absorbing material.

10. The method for preparing the conductive absorbing tape according to claim 6, characterized in that, The preparation method also satisfies at least one of the following conditions: (1) The conductive substrate is selected from graphite; (2) The mass ratio of the conductive substrate to the first adhesive is 1:(1.5~2.5); (3) The mass ratio of the composite absorbing material to the second adhesive is 1:(1.5~2.5); (4) The first curing includes holding at 50℃~70℃ for 15min~25min, and then holding at 90℃~110℃ for 20min~40min; (5) The second curing includes first holding at 50℃~70℃ for 15min~25min, then holding at 90℃~110℃ for 20min~40min, and then holding at 110℃~130℃ for 20min~40min.

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