Wave-absorbing and wave-transmitting integrated soft magnetic material and preparation method thereof

Abstract

The application discloses a wave-absorbing and wave-transmitting integrated soft magnetic material and a preparation method thereof. The preparation method comprises the following steps: S1, drying and uniformly mixing samarium oxide or nickel oxide, iron oxide, lithium carbonate, zinc oxide, manganese oxide, copper oxide or bismuth oxide, ball milling, sieving, and then performing magnetic field heat treatment to obtain a primary heat treatment product; and S2, performing heat treatment on the primary heat treatment product to obtain the wave-absorbing and wave-transmitting integrated soft magnetic material. The method is realized by an in-situ solid-phase sintering method under a magnetic field, and the magnetic field heat treatment is combined, so that the material can simultaneously absorb and transmit electromagnetic waves.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing and transmitting materials, specifically to an integrated microwave absorbing and transmitting soft magnetic material and its preparation method. Background Technology

[0002] With the continuous iteration and upgrading of electronic devices and communication base stations, traditional absorbing materials with only single absorption characteristics can no longer meet the needs of both absorbing interfering electromagnetic waves and accommodating their own information exchange. In existing technologies, achieving "integrated absorption and transmission" of materials often employs complex composite material systems or macroscopic structural designs (such as frequency-selective surfaces and multilayer sandwich structures). These methods are complex, costly, and difficult to achieve intrinsic performance uniformity in a single homogeneous material. Chinese patent application CN 111559133A discloses an integrated absorption / transmission material and its preparation method. A periodic structure is etched onto a carbon nanotube coating as a metamaterial layer, followed by a foam layer and a magnetic dielectric material layer, sequentially laid to a specified thickness, bonded, and cured to obtain the integrated absorption / transmission material. Although absorption and transmission are balanced to some extent, the periodic arrangement structure is sensitive to the incident wave angle and polarization mode, and its performance is affected at large angles or under different electromagnetic waves. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention aims to provide a soft magnetic material that integrates wave absorption and wave transmission and is prepared with magnetic field assistance.

[0004] The present invention solves the above-mentioned technical problems through the following technical means:

[0005] A method for preparing an integrated soft magnetic material that absorbs and transmits waves includes the following steps:

[0006] S1. After drying samarium oxide or nickel oxide, iron oxide, lithium carbonate, zinc oxide, manganese oxide, copper oxide or bismuth oxide, mix them evenly, ball mill them, sieve them, and then perform magnetic field heat treatment to obtain a first heat treatment product.

[0007] S2. The product of the first heat treatment is subjected to a second heat treatment to obtain the integrated soft magnetic material that absorbs and transmits waves; wherein the heat treatment temperature is 1000-1100℃.

[0008] Preferably, in S1, the molar ratio of samarium oxide or nickel oxide, iron oxide, lithium carbonate, zinc oxide, manganese oxide, copper oxide or bismuth oxide is 0.01-0.15: 1.05-1.14: 0.15-0.175: 0.20-0.3: 0.05-0.10: 0.01-0.10.

[0009] Preferably, in S1, the molar ratio of samarium oxide or nickel oxide, iron oxide, lithium carbonate, zinc oxide, manganese oxide, copper oxide or bismuth oxide is 0.01:1.14:0.15:0.20:0.10:0.10 or 0.01:1.14:0.15:0.30:0.05:0.05 or 0.1:1.115:0.15:0.25:0.10:0.01 or 0.15:1.05:0.175:0.20:0.05:0.05.

[0010] Preferably, in S1, during the ball milling process, stainless steel grinding balls with diameters of 10mm, 6mm, and 3mm are used as grinding balls; and the mass ratio of grinding balls with diameters of 10mm:6mm:3mm is 3:4:4; the mass ratio of ball to material is 15-20:1.

[0011] Preferably, in S1, during the ball milling process, the rotation speed is 250-300 rpm, and the total ball milling time is 8-12 hours, with a 10-minute pause every 30 minutes of ball milling.

[0012] Preferably, in S1, a 200-mesh sieve is used for sieving.

[0013] Preferably, in S1, the temperature of the magnetic field heat treatment is 800-900℃ and the time is 3-4 hours.

[0014] Preferably, in S1, the magnetic field strength of the magnetic field heat treatment is 0.5-2T.

[0015] Preferably, in S2, the heat treatment time is 4-6 hours.

[0016] Preferably, in step S2, the heat treatment process further includes grinding and sieving.

[0017] This invention also proposes an integrated soft magnetic material for absorbing and transmitting waves, which is prepared using the aforementioned method for preparing integrated soft magnetic materials for absorbing and transmitting waves.

[0018] Preferably, the integrated soft magnetic material for absorbing and transmitting electromagnetic waves absorbs electromagnetic waves in the 2-10 GHz band and transmits electromagnetic waves in the band greater than 10 GHz and less than or equal to 18 GHz.

[0019] The advantages of this invention are:

[0020] This invention provides a magnetically assisted fabrication of a soft magnetic ferrite material that integrates wave absorption and wave transmission, achieving both low-frequency broadband wave absorption and high-frequency wave transmission. This method utilizes in-situ solid-state sintering under a magnetic field, combined with magnetic field heat treatment, to achieve the material's simultaneous wave absorption and transmission properties. Furthermore, the fabrication process of this invention is short-cycle, low-cost, and suitable for large-scale production. Attached Figure Description

[0021] Figure 1 The diagram shows the reflection loss performance of the material in Embodiment 1 of the present invention at 2-18 GHz.

[0022] Figure 2 The diagram shows the reflection loss performance of the material in Embodiment 2 of the present invention at 2-18 GHz.

[0023] Figure 3 The diagram shows the reflection loss performance of the material in Embodiment 3 of the present invention at 2-18 GHz.

[0024] Figure 4 The diagram shows the reflection loss performance of the material in Example 4 of this invention at 2-18 GHz.

[0025] Figure 5 The diagram shows the reflection loss performance of the material in Embodiment 5 of the present invention at 2-18 GHz.

[0026] Figure 6 This is a performance diagram of the material of Comparative Example 1 of the present invention in terms of reflection loss at 2-18 GHz;

[0027] Figure 7 This is a performance diagram of the material of Comparative Example 2 of the present invention in terms of reflection loss at 2-18 GHz;

[0028] Figure 8 This is a performance diagram of the material of Comparative Example 3 of the present invention in terms of reflection loss at 2-18 GHz;

[0029] Figure 9 This is a performance graph of the material of Comparative Example 4 of the present invention in terms of reflection loss at 2-18 GHz;

[0030] Figure 10 This is a scanning electron microscope image of the material in Embodiment 1 of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0033] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0034] Example 1

[0035] A method for preparing an integrated soft magnetic material that absorbs and transmits waves includes the following steps:

[0036] (1) The samarium oxide, iron oxide, lithium carbonate, zinc oxide, manganese oxide and copper oxide were dried in an oven at 100°C for 5 hours to remove adsorbed moisture. The raw materials were initially mixed evenly according to the molar ratio of Sm2O3:Fe2O3:Li2CO3:ZnO:MnO:CuO =0.01:1.14:0.15:0.20:0.10:0.10.

[0037] (2) Place the mixed raw material powder from (1) and stainless steel grinding balls into a planetary ball mill jar. The stainless steel grinding balls are a mixture of 10mm diameter grinding balls, 6mm diameter grinding balls, and 3mm diameter grinding balls in a mass ratio of 3:4:4, with a ball-to-material mass ratio of 15:1. Grind for 12 hours at a speed of 250 rpm, with a 10-minute pause every 30 minutes to change the grinding direction.

[0038] (3) Use a 200-mesh sieve to sieve the powder to remove any possible large particles or contaminants. Then, place the sieved powder into a high-temperature furnace with a magnetic field strength of 2T and a temperature of 850℃ for 4 hours.

[0039] (4) After the furnace cools to room temperature, grind the heat-treated raw material for 3 hours and then sieve it through a 200-mesh sieve to refine it. Place the refined mixed powder in the furnace and heat treat it at 1000℃ for 4 hours.

[0040] (5) After cooling to room temperature in the furnace, the heat-treated raw material is ground for 3 hours and then sieved through a 200-mesh sieve to obtain the integrated soft magnetic material that absorbs and transmits waves. Its scanning electron microscope image is shown below. Figure 10 As shown.

[0041] The microwave-absorbing and microwave-transmitting integrated soft magnetic material was mixed with paraffin at a mass ratio of 7:3 and pressed into a ring with an outer diameter of 7.0 mm and an inner diameter of 3.0 mm. The sample was then tested using a vector network analyzer.

[0042] Figure 1 The graph shows the reflection loss performance of the material in Example 1 from 2 to 18 GHz. At 6.9 GHz, the reflection loss reaches -43.67 dB, and the effective absorption bandwidth is 3.95-9.0 GHz. Above 11 GHz, the curve gradually flattens and approaches 0, indicating that the material achieves high-frequency transmission while absorbing high-frequency waves at low frequencies.

[0043] Example 2

[0044] A method for preparing an integrated soft magnetic material that absorbs and transmits waves includes the following steps:

[0045] (1) The samarium oxide, iron oxide, lithium carbonate, zinc oxide, manganese oxide and copper oxide were dried in an oven at 100°C for 5 hours to remove adsorbed moisture. The raw materials were initially mixed evenly according to the molar ratio of Sm2O3:Fe2O3:Li2CO3:ZnO:MnO:CuO =0.01:1.14:0.15:0.30:0.05:0.05.

[0046] (2) Place the mixed raw material powder from (1) and stainless steel grinding balls into a planetary ball mill jar. The stainless steel grinding balls are a mixture of 10mm diameter grinding balls, 6mm diameter grinding balls, and 3mm diameter grinding balls in a mass ratio of 3:4:4, with a ball-to-material mass ratio of 20:1. Grind for 10 hours at a speed of 280 rpm, with a 10-minute pause every 30 minutes to change the grinding direction.

[0047] (3) Use a 200-mesh sieve to sieve the powder to remove any possible large particles or contaminants. Then, place the sieved powder into a high-temperature furnace with a magnetic field strength of 1T and a temperature of 900℃ for 3 hours.

[0048] (4) After the furnace cools to room temperature, grind the heat-treated raw material for 3 hours and then sieve it through a 200-mesh sieve to refine it. Place the refined mixed powder in the furnace and heat treat it at 1100℃ for 4 hours.

[0049] (5) After the furnace cools to room temperature, the heat-treated raw material is ground for 3 hours and then sieved through a 200-mesh sieve to obtain the integrated soft magnetic material that absorbs and transmits waves.

[0050] The microwave-absorbing and microwave-transmitting integrated soft magnetic material was mixed with paraffin at a mass ratio of 6:4 and pressed into a ring with an outer diameter of 7.0 mm and an inner diameter of 3.0 mm. The sample was then tested using a vector network analyzer.

[0051] Figure 2 The graph shows the reflection loss performance of the material in Example 2 from 2 to 18 GHz. At 6.55 GHz, the reflection loss reaches -16.68 dB, and the effective absorption bandwidth is 4.8-8.65 GHz. Above 11 GHz, the curve gradually flattens and approaches 0, indicating that the material achieves high-frequency transmission while absorbing high-frequency waves at low frequencies.

[0052] Example 3

[0053] A method for preparing an integrated soft magnetic material that absorbs and transmits waves includes the following steps:

[0054] (1) Dry nickel oxide, iron oxide, lithium carbonate, zinc oxide, manganese oxide and bismuth oxide in an oven at 110°C for 3 hours to remove adsorbed moisture. Mix the raw materials evenly in a molar ratio of NiO:Fe2O3:Li2CO3:ZnO:MnO:Bi2O3=0.1:1.115:0.15:0.25:0.10:0.01.

[0055] (2) Place the mixed raw material powder from (1) and stainless steel grinding balls into a planetary ball mill jar. The stainless steel grinding balls are a mixture of 10mm diameter grinding balls, 6mm diameter grinding balls, and 3mm diameter grinding balls in a mass ratio of 3:4:4, with a ball-to-material mass ratio of 15:1. Grind for 8 hours at a speed of 300 rpm, with a 10-minute pause every 30 minutes to change the grinding direction.

[0056] (3) Use a 200-mesh sieve to sieve the powder to remove any possible large particles or contaminants. Then, place the sieved powder into a high-temperature furnace with a magnetic field strength of 0.5T and a temperature of 900℃ for 3 hours.

[0057] (4) After the furnace cools to room temperature, grind the heat-treated raw material for 3 hours and then sieve it through a 200-mesh sieve to refine it. Place the refined mixed powder in the furnace and heat treat it at 1100℃ for 4 hours.

[0058] (5) After the furnace cools to room temperature, the heat-treated raw material is ground for 3 hours and then sieved through a 200-mesh sieve to obtain the integrated soft magnetic material that absorbs and transmits waves.

[0059] The microwave-absorbing and microwave-transmitting integrated soft magnetic material was mixed with paraffin at a mass ratio of 6:4 and pressed into a ring with an outer diameter of 7.0 mm and an inner diameter of 3.0 mm. The sample was then tested using a vector network analyzer.

[0060] Figure 3 The graph shows the reflection loss performance of the material in Example 3 from 2 to 18 GHz. At 5.3 GHz, the reflection loss reaches -13.10 dB, and the effective absorption bandwidth is 4.55-6.95 GHz. Above 10 GHz, the curve gradually flattens and approaches 0, indicating that the material achieves high-frequency transmission while absorbing high-frequency waves at low frequencies.

[0061] Example 4

[0062] A method for preparing an integrated soft magnetic material that absorbs and transmits waves includes the following steps:

[0063] (1) The nickel oxide, iron oxide, lithium carbonate, zinc oxide, manganese oxide and bismuth oxide were dried in an oven at 110°C for 3 hours to remove adsorbed moisture. The raw materials were initially mixed evenly according to the molar ratio of NiO:Fe2O3:Li2CO3:ZnO:MnO:Bi2O3=0.15:1.05:0.175:0.20:0.05:0.05.

[0064] (2) Place the mixed raw material powder from (1) and stainless steel grinding balls into a planetary ball mill jar. The stainless steel grinding balls are a mixture of 10mm diameter grinding balls, 6mm diameter grinding balls, and 3mm diameter grinding balls in a mass ratio of 3:4:4, with a ball-to-material mass ratio of 20:1. Grind for 10 hours at a speed of 280 rpm, with a 10-minute pause every 30 minutes to change the grinding direction.

[0065] (3) Use a 200-mesh sieve to sieve the powder to remove any possible large particles or contaminants. Then, place the sieved powder into a high-temperature furnace with a magnetic field strength of 1T and a temperature of 800℃ for 4 hours.

[0066] (4) After the furnace cools to room temperature, grind the heat-treated raw material for 3 hours and then sieve it through a 200-mesh sieve to refine it. Place the refined mixed powder in the furnace and heat treat it at 1000℃ for 4 hours.

[0067] (5) After the furnace cools to room temperature, the heat-treated raw material is ground for 3 hours and then sieved through a 200-mesh sieve to obtain the integrated soft magnetic material that absorbs and transmits waves.

[0068] The microwave-absorbing and microwave-transmitting integrated soft magnetic material was mixed with paraffin at a mass ratio of 6:4 and pressed into a ring with an outer diameter of 7.0 mm and an inner diameter of 3.0 mm. The sample was then tested using a vector network analyzer.

[0069] Figure 4 The graph shows the reflection loss performance of the material in Example 4 from 2 to 18 GHz. At 6.85 GHz, the reflection loss reaches -17.59 dB, and the effective absorption bandwidth is 4.15-8.1 GHz. Above 10 GHz, the curve gradually flattens and approaches 0, indicating that the material achieves high-frequency transmission while absorbing high-frequency waves at low frequencies.

[0070] Example 5

[0071] The difference between this embodiment and embodiment 1 is that the heat treatment temperature in step (4) is 1100℃ and the heat treatment time is 6 hours.

[0072] Figure 5The graph shows the reflection loss performance of the material in Example 5 from 2 to 18 GHz. At 6.45 GHz, the reflection loss reaches -26.18 dB, and the effective absorption bandwidth is 4.2-8.75 GHz. Above 11 GHz, the curve gradually flattens and approaches 0, indicating that the material achieves high-frequency transmission while absorbing high-frequency waves at low frequencies.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is that no magnetic field treatment was performed during the heat treatment process in step (3).

[0075] Figure 6 The graph shows the reflection loss performance of the powder without magnetic field heat treatment in Comparative Example 1 of this invention in the 2-18 GHz range. As can be seen from the graph, the reflection loss reaches -8.61 dB at 13.1 GHz, indicating weak reflection loss. The curve does not approach 0 at high frequencies, and the high-frequency transmission characteristics are not achieved.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 1 is that the secondary heat treatment in step (4) was not performed after step (3) was completed.

[0078] Depend on Figure 7 It can be seen that the reflection loss at 8.3 GHz is -6.38 dB. It does not have the characteristic of low-frequency absorption and high-frequency transmission.

[0079] Comparative Example 3

[0080] The difference between this comparative example and Example 2 is that the heat treatment temperature in step (4) is 1200°C.

[0081] Figure 8 The graph shows the reflection loss performance of Comparative Example 3 from 2 to 18 GHz. As can be seen from the graph, the reflection loss at 8.25 GHz is -11.50 dB. The curves above 11 GHz are much smaller than 0. This indicates that excessively high secondary heat treatment temperatures are detrimental to high-frequency transmission performance.

[0082] Comparative Example 4

[0083] The difference between this comparative example and Example 1 is that in step (1), the zinc oxide raw material is replaced with cobalt oxide.

[0084] Figure 9 This is a performance graph showing the reflection loss of the cobalt oxide-doped raw material in Comparative Example 4 of this invention at 2-18 GHz. As can be seen from the graph, the integrated absorption and transmission characteristics were not achieved.

[0085] To meet the requirements of efficient absorption in the low-frequency band and complete wave transmission in the high-frequency band, this invention designs a practical soft magnetic material that integrates wave absorption and transmission. By introducing a magnetic field during the heat treatment process, the growth of grains is promoted, the anisotropy of magnetocrystalline material and magnetic loss are controlled, and the electromagnetic parameters are adjusted to achieve impedance mismatch at high frequencies. Ultimately, a frequency-selective absorbing material with strong broadband absorption in low frequencies and wave transmission in high frequencies is achieved, which has broad application prospects in radar antennas, communication base stations, stealth technology, and RCS reduction.

[0086] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an integrated soft magnetic material that absorbs and transmits waves, characterized in that: Includes the following steps: S1. After drying, samarium oxide or nickel oxide, iron oxide, lithium carbonate, zinc oxide, manganese oxide, copper oxide or bismuth oxide are mixed evenly, ball-milled, sieved, and then subjected to magnetic field heat treatment to obtain a first-stage heat-treated product; the magnetic field strength of the magnetic field heat treatment is 0.5-2T, and the temperature is 800-900℃; the molar ratio of samarium oxide or nickel oxide, iron oxide, lithium carbonate, zinc oxide, manganese oxide, copper oxide or bismuth oxide is 0.01-0.15:1.05-1.14:0.15-0.175:0.20-0.3:0.05-0.10:0.01-0.10; S2. The product of the first heat treatment is subjected to further heat treatment to obtain the integrated soft magnetic material that absorbs and transmits waves; wherein, the heat treatment temperature in step S2 is 1000-1100℃.

2. The method for preparing the integrated soft magnetic material for absorbing and transmitting waves according to claim 1, characterized in that: In S1, during the ball milling process, stainless steel grinding balls with diameters of 10mm, 6mm, and 3mm are used as grinding balls; and the mass ratio of grinding balls with diameters of 10mm:6mm:3mm is 3:4:4; the mass ratio of ball to material is 15-20:

1.

3. The method for preparing the integrated soft magnetic material for absorbing and transmitting waves according to claim 1, characterized in that: In S1, during the ball milling process, the rotation speed is 250-300 rpm, and the total ball milling time is 8-12 hours, with a 10-minute pause every 30 minutes of ball milling.

4. The method for preparing the integrated soft magnetic material for absorbing and transmitting waves according to claim 1, characterized in that: In S1, a 200-mesh sieve is used for sieving.

5. The method for preparing the integrated soft magnetic material for absorbing and transmitting waves according to claim 1, characterized in that: In S1, the magnetic field heat treatment time is 3-4 hours.

6. The method for preparing the integrated soft magnetic material for absorbing and transmitting waves according to any one of claims 1-5, characterized in that: In S2, the heat treatment time is 4-6 hours.

7. A soft magnetic material that integrates wave absorption and wave transmission, characterized in that: It is prepared using the method for preparing the integrated soft magnetic material for absorbing and transmitting waves as described in any one of claims 1-6.

8. The integrated soft magnetic material for absorbing and transmitting waves according to claim 7, characterized in that: It achieves electromagnetic wave absorption in the 2-10GHz band and electromagnetic wave transmission in the band greater than 10GHz and less than or equal to 18GHz.

Images