High-silicon steel powder composite wave-absorbing material as well as preparation method and application thereof

Abstract

The invention discloses a high silicon steel powder composite wave-absorbing material and a preparation method and application thereof, and relates to the technical field of wave-absorbing materials, the high silicon steel powder composite wave-absorbing material comprises 30wt%-70wt% of a wave-absorbing agent and 30wt%-70wt% of a base material, the base material comprises a polyimide solution, and the solid content of polyimide is 35%-45%; the wave-absorbing agent comprises high-silicon steel powder and carbon nanotubes, the carbon nanotubes grow on the surface of the high-silicon steel powder in situ, and the high-silicon steel powder comprises, by mass, 5%-8% of Si, 0.01%-1% of LA2O3 and the balance Fe; the technical problems that a traditional wave-absorbing material is poor in dispersion, so that the wave-absorbing effect or the oxidation resistance is poor, and the service life is affected can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of absorbing materials, and in particular to a high-silicon steel powder composite absorbing material and a preparation method and application thereof. Background Art

[0002] The function of absorbing materials is to absorb electromagnetic wave energy and convert it into other forms of energy (such as heat energy), thereby reducing the reflection and propagation of electromagnetic waves. Compared with electromagnetic shielding materials, absorbing materials focus more on electromagnetic wave absorption and energy conversion.

[0003] Currently, absorbing materials are generally composed of fiber-reinforced resin-based composites and absorbing fillers, and have the dual functions of absorbing and carrying. According to the loss mechanism of electromagnetic waves, they are divided into electrical loss-type absorbing materials and magnetic loss-type absorbing materials. Electrical loss-type absorbing materials mainly include conductive loss (such as non-magnetic metal powders, carbon nanotubes, graphene, and conductive polymers) and dielectric loss (such as silicon carbide ceramics and barium titanate ceramics). These are mainly nanomaterials. Due to the huge surface activity of nanomaterials, they have poor dispersion in the matrix material, resulting in insignificant absorption effect. Magnetic loss-type absorbing materials mainly include ferrite, carbonyl iron, magnetic metals (such as Fe, Co, Ni), and their alloys. However, carbonyl iron and ferrite powders are often spherical, requiring ball milling to flaky them to achieve good absorption effect, which increases the process and cost. In addition, although carbonyl iron and ferrite powders can increase the bandwidth of the absorbing material, they also bring low oxidation resistance and weight gain. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a high-silicon steel powder composite absorbing material and its preparation method and application, aiming to solve the technical problems that traditional absorbing materials have poor dispersion, resulting in poor absorbing effect or poor oxidation resistance, which affects the service life.

[0005] A first aspect of the present invention is to provide a high-silicon steel powder composite absorbing material, the high-silicon steel powder composite absorbing material comprising:

[0006] 30wt% to 70wt% of a wave absorbing agent and 30wt% to 70wt% of a matrix material;

[0007] The wave absorbing agent comprises high silicon steel powder and carbon nanotubes, wherein the carbon nanotubes are in-situ grown on the surface of the high silicon steel powder, and the high silicon steel powder comprises Si: 5% to 8%, LA2O3: 0.01% to 1%, and the balance is Fe according to mass percentage;

[0008] The matrix material comprises a polyimide solution, and the solid content of the polyimide is 35% to 45%.

[0009] Compared with the prior art, the present invention has the following beneficial effects: a high-silicon steel powder composite absorbing material provided by the present invention includes: an absorbing agent and a matrix material, wherein the absorbing agent includes high-silicon steel powder and carbon nanotubes, and the carbon nanotubes are in-situ grown on the surface of the high-silicon steel powder, which can effectively solve the problem of difficult dispersion of nanomaterials in the matrix material, and can increase the corrosion resistance and oxidation resistance of the silicon steel powder, meet complex application environments, and extend the service life. At the same time, the carbon nanotubes, as a fiber material, can effectively increase the strength of the matrix material and improve the toughness. In addition, the carbon nanotubes are also a good thermal conductive material and a low-density material, which can make the absorbing material lightweight, thereby solving the technical problem that traditional absorbing materials have poor dispersion, resulting in poor absorbing effect or poor oxidation resistance, which affects the service life.

[0010] According to one aspect of the above technical solution, the high silicon steel powder is a flaky powder, and the D50 of the high silicon steel powder is 18 μm to 22 μm.

[0011] A second aspect of the present invention is to provide a method for preparing a high-silicon steel powder composite absorbing material. The method is used to prepare the high-silicon steel powder composite absorbing material, and the method comprises:

[0012] Weighing raw materials, which include Si: 5% to 8%, LA2O3: 0.01% to 1%, and the balance Fe in percentage by mass, and obtaining flaky high silicon steel powder through alloy smelting-cooling spraying-annealing-crushing;

[0013] The high silicon steel powder is placed in a reaction furnace, a preset reaction gas is introduced, and carbon nanotubes are synthesized in situ on the high silicon steel powder at a preset reaction temperature to obtain a wave absorbing agent;

[0014] 30 wt% to 70 wt% of an absorber and 30 wt% to 70 wt% of a matrix material are mixed and ultrasonically stirred to obtain an absorbing slurry, wherein the matrix material comprises a polyimide solution, and the solid content of the polyimide is 35% to 45%;

[0015] The absorbing slurry is injected into a 3D printer, and printed into a honeycomb structure coating on the silicon carbide fiber cloth at a preset printing temperature and a preset printing speed;

[0016] Another silicon carbide fiber cloth is covered on the honeycomb structure coating and cured to obtain a high silicon steel powder composite absorbing material.

[0017] According to one aspect of the above technical solution, the step of placing the high silicon steel powder in a reactor, introducing a preset gas, and in-situ synthesizing carbon nanotubes on the high silicon steel powder at a preset reaction temperature to obtain the absorber specifically includes:

[0018] The high silicon steel powder is placed in a reaction furnace, and nitrogen is introduced after vacuuming;

[0019] The temperature is raised to the preset preheating temperature at a preset heating rate, and nitrogen and hydrogen are introduced into the reactor simultaneously to maintain the temperature for 20 to 40 minutes;

[0020] The temperature is raised to a preset reaction temperature, a preset reaction gas is introduced and reacted for a preset time, carbon nanotubes are synthesized in situ on the high silicon steel powder, and the powder is sieved to obtain a wave absorbing agent.

[0021] According to one aspect of the above technical solution, the preset heating rate is 50°C / min to 60°C / min, and the preset preheating temperature is 580°C to 620°C.

[0022] According to one aspect of the above technical solution, the preset reaction temperature is 800°C to 900°C, the preset reaction gases are nitrogen, hydrogen, and acetylene, the volume ratio of nitrogen, hydrogen, and acetylene is (4 to 8):2:2, and the preset time is 20 minutes to 40 minutes.

[0023] According to one aspect of the above technical solution, the ultrasonic power of the absorbing slurry is 250W to 350W, the stirring speed of the absorbing slurry is 80rmb / min to 120rmb / min, and the ultrasonic stirring time of the absorbing slurry is 50min to 70min.

[0024] According to one aspect of the above technical solution, the step of injecting the absorbing slurry into a 3D printer and printing a honeycomb structure coating on the silicon carbide fiber cloth at a preset printing temperature and a preset printing speed specifically includes:

[0025] A layer of microwave absorbing slurry with a thickness of 0.1 mm to 0.5 mm is coated on a silicon carbide fiber cloth with a thickness of 0.1 mm to 1 mm, and the slurry is cured at a temperature of 300° C. to 390° C. to obtain a silicon carbide fiber cloth coated with the slurry;

[0026] The absorbing slurry is loaded into a syringe of a 3D printer and vacuum centrifuged to remove bubbles;

[0027] A honeycomb structure coating is printed on the silicon carbide fiber cloth coated with the slurry at a preset printing temperature and a preset printing speed. The thickness of the honeycomb structure coating is 1 mm to 2 mm. The preset printing speed is 7 cm / s to 13 cm / s. The preset printing temperature is 20°C to 40°C.

[0028] According to one aspect of the above technical solution, the thickness of the high silicon steel powder composite absorbing material is 2 mm to 4 mm.

[0029] A third aspect of the present invention is to provide an application of a high silicon steel powder composite absorbing material prepared by the above-mentioned method for preparing a high silicon steel powder composite absorbing material in an NFC antenna absorbing device for a mobile phone or electronic product. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0031] Figure 1 This is a schematic diagram of the preparation method of the high silicon steel powder composite absorbing material of the present invention;

[0032] Figure 2 This is a scanning electron microscope (SEM) image of carbon nanotubes in situ grown on the surface of high silicon steel powder in the present invention. DETAILED DESCRIPTION

[0033] To make the objectives, features, and advantages of the present invention more readily apparent, the following detailed description of specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The accompanying drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0034] The present invention provides a high-silicon steel powder composite absorbing material, which comprises:

[0035] 30wt% to 70wt% of a wave absorbing agent and 30wt% to 70wt% of a matrix material;

[0036] The wave absorbing agent comprises high silicon steel powder and carbon nanotubes, wherein the carbon nanotubes are in-situ grown on the surface of the high silicon steel powder, and the high silicon steel powder comprises Si: 5% to 8%, LA2O3: 0.01% to 1%, and the balance is Fe according to mass percentage;

[0037] The matrix material comprises a polyimide solution, and the solid content of the polyimide is 35% to 45%.

[0038] like Figure 2The figure shows carbon nanotubes deposited in situ by CVD on the surface of high-silicon steel powder. By incorporating carbon nanotubes (CNTs) onto the surface of high-silicon steel powder, the difficulty of dispersing nanomaterials in the matrix material can be effectively resolved. Furthermore, in-situ CVD deposition of CNTs on the surface of high-silicon steel powder enhances the corrosion and oxidation resistance of the silicon steel powder, meeting the requirements of complex application environments and effectively addressing the poor oxidation resistance of ferrite absorbers such as carbonyl iron powder. Furthermore, as a fiber material, CNTs can effectively increase the strength and toughness of polyimide. Furthermore, CNTs are also an excellent thermal conductor and a low-density material, which can make the absorber lightweight.

[0039] Furthermore, the high-silicon steel powder is a flaky powder with a D50 of 18 to 22 μm. The ultra-thin flaky high-silicon steel powder is obtained through alloy smelting, cooling spraying, annealing, and crushing. This powder exhibits excellent microwave absorption, effectively resolving the issue of ferrite or carbonyl iron requiring ball milling to form flaks, which increases the process and costs. Furthermore, the ultra-thin flaky high-silicon steel powder also has a high saturation magnetic induction intensity (Bs) value, providing excellent high-frequency microwave absorption.

[0040] Therefore, high silicon steel powder is used as a good magnetic loss type absorbing material, and carbon nanotubes are used as an excellent conductive absorbing material. The two are matched and compounded to form an excellent conductive / magnetic loss type composite absorber.

[0041] Preferably, the mass percentage of Si is 5% to 8%, for example, it can be 5%, 5.5%, 6%, 6.5%, 7%, 7.5% or 8%, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0042] Preferably, the mass percentage of LA2O3 is 0.01% to 1%, for example, it can be 0.01%, 0.05%, 0.1%, 0.2%, 0.5% or 1%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] Accordingly, the present invention further provides a method for preparing a high-silicon steel powder composite absorbing material, the method comprising steps S10-S14:

[0044] Step S10, weighing raw materials, wherein the raw materials include Si: 5% to 8%, LA2O3: 0.01% to 1%, and the balance is Fe in percentage by mass, and obtaining flaky high silicon steel powder through alloy smelting-cooling spraying-annealing-crushing;

[0045] The thickness of the strip prepared by the cooling spray belt is 0.03 mm, and the D50 of the flaky high silicon steel powder obtained by crushing is 18 μm to 22 μm.

[0046] Ultra-thin flakes of high-silicon steel powder produced through the ultra-cold crushing method have excellent electromagnetic properties, making them ideal materials for microwave absorbers. This avoids the need for flake processing of ferrite or carbonyl iron, which increases the process and costs.

[0047] Step S11, placing the high silicon steel powder into a reactor, introducing a preset reaction gas, and in-situ synthesizing carbon nanotubes on the high silicon steel powder at a preset reaction temperature to obtain a wave absorbing agent;

[0048] Specifically, the high silicon steel powder is placed in a reaction furnace, and nitrogen is introduced after vacuuming;

[0049] The temperature is raised to the preset preheating temperature at a preset heating rate, and nitrogen and hydrogen are introduced into the reactor simultaneously to maintain the temperature for 20 to 40 minutes;

[0050] Wherein, the preset heating rate is 50°C / min to 60°C / min, and the preset preheating temperature is 580°C to 620°C.

[0051] The temperature is raised to a preset reaction temperature, a preset reaction gas is introduced and reacted for a preset time, carbon nanotubes are synthesized in situ on the high silicon steel powder, and the powder is sieved to obtain a wave absorbing agent.

[0052] The preset reaction temperature is 800°C to 900°C, the preset reaction gases are nitrogen, hydrogen, and acetylene, the volume ratio of nitrogen, hydrogen, and acetylene is (4-8):2:2, and the preset time is 20min to 40min.

[0053] Specifically, acetylene is used as the carbon source of carbon nanotubes, hydrogen and nitrogen are used as carrier gases, and carbon nanotubes are deposited on the surface of high-silicon steel powder using CVD in-situ deposition. In addition, the iron in the high-silicon steel powder can be used as a catalyst for carbon nanotube synthesis, improving the reaction process and reaction selectivity.

[0054] In addition, in order to filter out coarse particles of powder, the size of the sieve holes is 350 mesh to 450 mesh.

[0055] Step S12, mixing 30 wt% to 70 wt% of the absorber and 30 wt% to 70 wt% of the matrix material, and ultrasonically stirring to obtain a absorbing slurry, wherein the matrix material includes a polyimide solution, and the solid content of the polyimide is 35% to 45%;

[0056] In order to achieve uniform mixing of the absorber and the matrix material, ultrasonic stirring is performed. The ultrasonic power of the absorbing slurry is 250W to 350W, the stirring speed of the absorbing slurry is 80rmb / min to 120rmb / min, and the ultrasonic stirring time of the absorbing slurry is 50min to 70min.

[0057] Step S13, injecting the absorbing slurry into a 3D printer, and printing it into a honeycomb structure coating on the silicon carbide fiber cloth at a preset printing temperature and a preset printing speed;

[0058] Specifically, a layer of absorbing slurry with a thickness of 0.1mm to 0.5mm is coated on a silicon carbide fiber cloth with a thickness of 0.1mm to 1mm, and then cured at a curing temperature of 300°C to 390°C to obtain a silicon carbide fiber cloth coated with the slurry;

[0059] A layer of absorbing slurry is pre-coated to increase the tensile strength of the material.

[0060] The absorbing slurry is loaded into a syringe of a 3D printer and vacuum centrifuged to remove bubbles;

[0061] A honeycomb structure coating is printed on the silicon carbide fiber cloth coated with the slurry at a preset printing temperature and a preset printing speed. The thickness of the honeycomb structure coating is 1 mm to 2 mm. The preset printing speed is 7 cm / s to 13 cm / s. The preset printing temperature is 20°C to 40°C.

[0062] Among them, silicon carbide fiber cloth has the advantages of good thermal conductivity, great strength, and corrosion resistance. Silicon carbide fiber cloth is then covered on both sides of the honeycomb structure coating to further solve the strength and corrosion resistance problems of high-silicon steel powder composite absorbing materials.

[0063] Step S14, covering the honeycomb structure coating with another silicon carbide fiber cloth and curing it to obtain a high silicon steel powder composite absorbing material;

[0064] Specifically, another silicon carbide fiber cloth coated with slurry is covered on the honeycomb structure coating and cured to obtain a high silicon steel powder composite absorbing material. The curing temperature is 300°C to 390°C.

[0065] The thickness of the high silicon steel powder composite wave absorbing material is 2 mm to 4 mm.

[0066] It should be noted that in order to further reduce the weight of the product, a honeycomb structure coating is obtained through 3D printing technology, and then covered with silicon carbide fiber cloth on both sides to form a hollow absorbing layer.

[0067] In addition, the present invention also provides the use of the high-silicon steel powder composite absorbing material prepared by the above-mentioned preparation method of the high-silicon steel powder composite absorbing material in the NFC antenna absorbing device of a mobile phone or electronic product.

[0068] The present invention is further described below with specific examples:

[0069] Example 1

[0070] A first embodiment of the present invention provides a high silicon steel powder composite absorbing material, wherein the high silicon steel powder composite absorbing material comprises:

[0071] 40wt% absorber and 60wt% matrix material;

[0072] The wave absorbing agent comprises high silicon steel powder and carbon nanotubes, wherein the carbon nanotubes are in-situ grown on the surface of the high silicon steel powder, and the high silicon steel powder comprises Si: 6.5%, LA2O3: 0.05%, and the balance Fe according to mass percentage;

[0073] The matrix material includes a polyimide solution, and the solid content of the polyimide is 40%.

[0074] Furthermore, the high silicon steel powder is a flaky powder, and the D50 of the high silicon steel powder is 20 μm.

[0075] Accordingly, the preparation method of the high silicon steel powder composite absorbing material includes steps S10-S14:

[0076] Step S10, weighing raw materials, wherein the raw materials include Si: 5% to 8%, LA2O3: 0.01% to 1%, and the balance is Fe in percentage by mass, and obtaining flaky high silicon steel powder through alloy smelting-cooling spraying-annealing-crushing;

[0077] The thickness of the strip prepared by the cooling spray belt is 0.03 mm, and the D50 of the flaky high silicon steel powder obtained by crushing is 20 μm.

[0078] Step S11, placing the high silicon steel powder into a reactor, introducing a preset reaction gas, and in-situ synthesizing carbon nanotubes on the high silicon steel powder at a preset reaction temperature to obtain a wave absorbing agent;

[0079] Specifically, the high silicon steel powder is placed in a reaction furnace, and nitrogen is introduced after vacuuming;

[0080] The temperature was raised to the preset preheating temperature at a preset heating rate, and nitrogen and hydrogen were introduced into the reactor simultaneously and kept at this temperature for 30 minutes;

[0081] Wherein, the preset heating rate is 55°C / min, and the preset preheating temperature is 600°C.

[0082] The temperature is raised to a preset reaction temperature, a preset reaction gas is introduced and reacted for a preset time, carbon nanotubes are synthesized in situ on the high silicon steel powder, and the powder is sieved to obtain a wave absorbing agent.

[0083] Among them, the preset reaction temperature is 800°C to 900°C, the preset reaction gases are nitrogen, hydrogen, and acetylene, the volume ratio of nitrogen, hydrogen, and acetylene is 6:2:2, the preset time is 25 minutes, and the sieve size is 400 mesh.

[0084] After the reaction was completed, the mixture was cooled to room temperature in a nitrogen atmosphere.

[0085] Step S12, mixing 30 wt% to 70 wt% of the absorber and 30 wt% to 70 wt% of the matrix material, and ultrasonically stirring to obtain a absorbing slurry, wherein the matrix material includes a polyimide solution, and the solid content of the polyimide is 35% to 45%;

[0086] In order to achieve uniform mixing of the absorber and the matrix material, ultrasonic stirring is performed. The ultrasonic power of the absorbing slurry is 300 W, the stirring speed of the absorbing slurry is 100 rmb / min, and the ultrasonic stirring time of the absorbing slurry is 60 min.

[0087] Step S13, injecting the absorbing slurry into a 3D printer, and printing it into a honeycomb structure coating on the silicon carbide fiber cloth at a preset printing temperature and a preset printing speed;

[0088] Specifically, a layer of 0.3mm thick absorbing slurry is coated on a 0.5mm thick silicon carbide fiber cloth, and then cured at a curing temperature of 300°C to 390°C to obtain a silicon carbide fiber cloth coated with the slurry;

[0089] The absorbing slurry is loaded into a syringe of a 3D printer and vacuum centrifuged to remove bubbles;

[0090] A honeycomb structure coating is printed on the silicon carbide fiber cloth coated with the slurry at a preset printing temperature and a preset printing speed. The thickness of the honeycomb structure coating is 1.4 mm. The preset printing speed is 10 cm / s and the preset printing temperature is 20°C to 40°C.

[0091] Step S14, covering the honeycomb structure coating with another silicon carbide fiber cloth and curing it to obtain a high silicon steel powder composite absorbing material;

[0092] Specifically, another silicon carbide fiber cloth coated with slurry is covered on the honeycomb structure coating and cured to obtain a high silicon steel powder composite absorbing material. The curing temperature is 300°C to 390°C.

[0093] The thickness of the high silicon steel powder composite wave absorbing material is 3 mm.

[0094] Comparative Example 1

[0095] The first comparative example of the present invention provides a high silicon steel powder composite absorbing material. The high silicon steel powder composite absorbing material in this comparative example differs from the high silicon steel powder composite absorbing material in the first embodiment in that:

[0096] No high silicon steel powder.

[0097] Comparative Example 2

[0098] The second comparative example of the present invention provides a high silicon steel powder composite absorbing material. The high silicon steel powder composite absorbing material in this comparative example differs from the high silicon steel powder composite absorbing material in the first embodiment in that:

[0099] No carbon nanotubes.

[0100] Comparative Example 3

[0101] The third comparative example of the present invention provides a high silicon steel powder composite absorbing material. The high silicon steel powder composite absorbing material in this comparative example differs from the high silicon steel powder composite absorbing material in the first embodiment in that:

[0102] No high silicon steel powder and carbon nanotubes.

[0103] Please refer to Table 1 below, which shows the performance test results of high-silicon steel powder composite absorbing materials prepared under different embodiments and comparative examples.

[0104] Table 1

[0105]

[0106] It should be noted that the test method for the number of high and low temperature impacts is to set the high temperature to 125°C and the low temperature to -55°C. Each impact of high temperature airflow or low temperature airflow lasts for 15 minutes. One cycle is counted as one time. The cycle operation is repeated and the number of impacts is recorded.

[0107] According to the data in Table 1, the absorbing performance and reliability of the high silicon steel powder composite absorbing material can be effectively improved by in-situ growing carbon nanotubes on the surface of the high silicon steel powder.

[0108] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0109] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A high silicon steel powder composite absorbing material, characterized in that: The high silicon steel powder composite absorbing material comprises: 30wt% to 70wt% of a wave absorbing agent and 30wt% to 70wt% of a matrix material; The wave absorbing agent comprises high silicon steel powder and carbon nanotubes, wherein the carbon nanotubes are in-situ grown on the surface of the high silicon steel powder, and the high silicon steel powder comprises Si: 5% to 8%, LA2O3: 0.01% to 1%, and the balance is Fe according to mass percentage; The matrix material comprises a polyimide solution, and the solid content of the polyimide is 35% to 45%.

2. The high silicon steel powder composite absorbing material according to claim 1, characterized in that: The high silicon steel powder is a flaky powder, and the D50 of the high silicon steel powder is 18 μm to 22 μm.

3. A method for preparing a high silicon steel powder composite absorbing material, characterized in that: The preparation method is used to prepare the high silicon steel powder composite absorbing material according to any one of claims 1 to 2, and the preparation method comprises: Weighing raw materials, which include Si: 5% to 8%, LA2O3: 0.01% to 1%, and the balance Fe in percentage by mass, and obtaining flaky high silicon steel powder through alloy smelting-cooling spraying-annealing-crushing; The high silicon steel powder is placed in a reaction furnace, a preset reaction gas is introduced, and carbon nanotubes are synthesized in situ on the high silicon steel powder at a preset reaction temperature to obtain a wave absorbing agent; 30 wt% to 70 wt% of an absorber and 30 wt% to 70 wt% of a matrix material are mixed and ultrasonically stirred to obtain an absorbing slurry, wherein the matrix material comprises a polyimide solution, and the solid content of the polyimide is 35% to 45%; The absorbing slurry is injected into a 3D printer, and printed into a honeycomb structure coating on the silicon carbide fiber cloth at a preset printing temperature and a preset printing speed; Another silicon carbide fiber cloth is covered on the honeycomb structure coating and cured to obtain a high silicon steel powder composite absorbing material.

4. The method for preparing a high silicon steel powder composite absorbing material according to claim 3, wherein: The step of placing the high silicon steel powder in a reactor, introducing a preset gas, and in-situ synthesizing carbon nanotubes on the high silicon steel powder at a preset reaction temperature to obtain the wave absorbing agent specifically includes: The high silicon steel powder is placed in a reaction furnace, and nitrogen is introduced after vacuuming; The temperature is raised to the preset preheating temperature at a preset heating rate, and nitrogen and hydrogen are introduced into the reactor simultaneously to maintain the temperature for 20 to 40 minutes; The temperature is raised to a preset reaction temperature, a preset reaction gas is introduced and reacted for a preset time, carbon nanotubes are synthesized in situ on the high silicon steel powder, and the powder is sieved to obtain a wave absorbing agent.

5. The method for preparing a high silicon steel powder composite absorbing material according to claim 4, characterized in that: The preset heating rate is 50°C / min to 60°C / min, and the preset preheating temperature is 580°C to 620°C.

6. The method for preparing a high silicon steel powder composite absorbing material according to claim 4, characterized in that: The preset reaction temperature is 800° C. to 900° C., the preset reaction gases are nitrogen, hydrogen, and acetylene, the volume ratio of nitrogen, hydrogen, and acetylene is (4 to 8):2:2, and the preset time is 20 min to 40 min.

7. The method for preparing a high silicon steel powder composite absorbing material according to claim 3, characterized in that: The ultrasonic power of the wave-absorbing slurry is 250W to 350W, the stirring speed of the wave-absorbing slurry is 80rmb / min to 120rmb / min, and the ultrasonic stirring time of the wave-absorbing slurry is 50min to 70min.

8. The method for preparing a high silicon steel powder composite absorbing material according to claim 3, characterized in that: The step of injecting the absorbing slurry into a 3D printer and printing a honeycomb structure coating on the silicon carbide fiber cloth at a preset printing temperature and a preset printing speed specifically includes: A layer of microwave absorbing slurry with a thickness of 0.1 mm to 0.5 mm is coated on a silicon carbide fiber cloth with a thickness of 0.1 mm to 1 mm, and the slurry is cured at a temperature of 300° C. to 390° C. to obtain a silicon carbide fiber cloth coated with the slurry; The absorbing slurry is loaded into a syringe of a 3D printer and vacuum centrifuged to remove bubbles; A honeycomb structure coating is printed on the silicon carbide fiber cloth coated with the slurry at a preset printing temperature and a preset printing speed. The thickness of the honeycomb structure coating is 1 mm to 2 mm. The preset printing speed is 7 cm / s to 13 cm / s. The preset printing temperature is 20°C to 40°C.

9. The method for preparing a high silicon steel powder composite absorbing material according to claim 3, wherein: The thickness of the high silicon steel powder composite wave absorbing material is 2 mm to 4 mm.

10. Use of the high silicon steel powder composite absorbing material prepared by the method for preparing the high silicon steel powder composite absorbing material according to any one of claims 3 to 9 in an NFC antenna absorbing device for a mobile phone or electronic product.

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