A high-frequency magnetic composite material, a high-frequency magnetic device and a processing method thereof

Abstract

The present invention belongs to the technical field of magnetic materials, and particularly relates to a high-frequency magnetic composite material, a high-frequency magnetic device and a processing method thereof. Among them, the processing method of the high-frequency magnetic composite material includes: mixing magnetic metal particles with a magnetic vortex structure, a solvent and a non-magnetic ceramic phase material and grinding them into a slurry; placing the slurry in a mold and forming it under a low-temperature and low-pressure process; wherein, the conditions of the low-temperature and low-pressure process are that the temperature is lower than 300 °C and the pressure is less than 500 MPa. By using magnetic particles with a magnetic vortex structure, there are no magnetic domain walls in the present invention. At high frequencies, magnetization mainly occurs through magnetization rotation, rather than the traditional domain wall displacement mechanism, which can significantly increase the working frequency of the material to above 100 MHz; in addition, the low-temperature and low-pressure process is adopted to avoid various defects of extreme conditions such as high temperature and high pressure in the traditional process.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic materials, and particularly relates to a high-frequency magnetic composite material, a high-frequency magnetic device and a processing method thereof. Background Art

[0002] Magnetic materials can generate magnetic responses under the excitation of an external magnetic field and are basic materials for the electronic information industry. By winding one or more sets of metal coils around a magnetic material and passing an electric current, magnetic devices such as transformers, inductors, mutual inductors, and filters can be made. Electronic devices are developing rapidly towards high frequency, integration, and low power consumption. Especially the rapid development of the third-generation power semiconductors has put forward an urgent demand for high-frequency magnetic materials with a cut-off frequency in the megahertz range. When an alternating current flows through a coil, energy is temporarily stored in the magnetic field induced inside the coil and the magnetic core. According to the electromagnetic induction law, the alternating magnetic field can induce an alternating electric field and magnetic field and radiate to the outside of the device. These radiated electromagnetic fields can interfere with or reduce the performance of other electronic devices around the magnetic device. In addition, the electric and magnetic fields from other electronic components on the circuit board can also interfere with and reduce the performance of the magnetic device. With the increasingly serious electromagnetic interference phenomenon of magnetic devices, higher requirements are put forward for the shielding characteristics of magnetic devices.

[0003] The magnetic materials traditionally used in magnetic devices mainly include metal soft magnetic materials, soft magnetic composite materials, soft magnetic ferrites, etc. Metal soft magnetic materials have extremely low resistivity, and the eddy current loss increases sharply at high frequencies, and they are only suitable for power frequency (from dozens to hundreds of hertz). Soft magnetic composite materials are made by insulating coating, bonding, and pressing metal magnetic powders with a particle size of dozens of micrometers to hundreds of micrometers. The working frequency is increased to dozens of kilohertz, but the eddy current loss is still serious at frequencies above megahertz. Soft magnetic ferrites are sintered from metal oxides at high temperatures (above 1000 degrees). Due to their high resistivity, they can work in the megahertz frequency band, but their saturation magnetic flux is low, which is not conducive to reducing the volume of the device. At the same time, the above-mentioned magnetic materials are all multi-domain structures, and the magnetic domain walls inside will generate domain wall resonance under the excitation of an external magnetic field, resulting in a rapid decay of the magnetic permeability, and none of them can be applied to frequencies above 100 MHz. The coils used in magnetic devices are generally wound with enameled wires, and the heat-resistant temperature of the insulating paint is generally below 400°C. Since the preparation of the above three magnetic materials requires extreme processes such as high-temperature melting (metal soft magnetic materials), high-pressure molding (soft magnetic composite materials), and high-temperature sintering (soft magnetic ferrites), the insulating structure of the enameled wire coil will be damaged, and it can only be realized by winding the coil on the surface of the bulk material, thus the above-mentioned electromagnetic interference problem cannot be avoided. Summary of the Invention

[0004] Based on the above-mentioned drawbacks and deficiencies existing in the prior art, one of the objectives of the present invention is to at least solve one or more of the above-mentioned problems existing in the prior art. In other words, one of the objectives of the present invention is to provide a high-frequency magnetic composite material, a high-frequency magnetic device, and a processing method thereof that meet one or more of the foregoing requirements.

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

[0006] A processing method of a high-frequency magnetic composite material, comprising:

[0007] Mixing and grinding magnetic metal particles with a magnetic vortex structure, a solvent, and a non-magnetic ceramic phase material into a slurry;

[0008] Placing the slurry in a mold and forming it under a low-temperature and low-pressure process;

[0009] Among them, the conditions of the low-temperature and low-pressure process are that the temperature is lower than 300 °C and the pressure is less than 500 MPa.

[0010] As a preferred solution, the magnetic metal particles are based on iron, nickel, cobalt, rare earth metals, and their alloys; preferably, the magnetic metal particles are one or several of iron, iron-silicon, iron-silicon-aluminum, iron-nickel, iron-nickel-chromium, iron-silicon-chromium, iron-silicon-nickel, iron-nickel-molybdenum, iron-cobalt, iron-cobalt-silicon, iron-based amorphous, and iron-based nanocrystals; preferably, the shape of the magnetic metal particles is spherical or quasi-spherical; preferably, the size of the magnetic metal particles is 50 nm to 5 μm.

[0011] As a preferred solution, the non-magnetic ceramic phase material is dissolved in the solvent.

[0012] As a preferred solution, the solvent is one of water, alcohol solvents, organic acid solutions, inorganic acid solutions, and alkali solutions; preferably, the solvent is one of water, ethanol, acetic acid solution, citric acid solution, and oxalic acid solution.

[0013] As a preferred solution, the mass fraction of the solvent in the slurry is 5-50%.

[0014] As a preferred solution, the non-magnetic ceramic phase material is a ceramic or a ceramic precursor. The ceramic is selected from one of molybdenum trioxide, zinc oxide, titanium oxide, barium titanate, bismuth trioxide, boron trioxide, and lead oxide. The ceramic precursor is selected from one of molybdic acid, ammonium molybdate, bismuth nitrate, basic bismuth nitrate, boric acid, lead nitrate, metal acetate, acetylacetonate, oxalate, and citrate.

[0015] The present invention also provides a high-frequency magnetic composite material prepared by the processing method described in any of the above solutions, with a metal mass fraction of 80.0-99.9%, a ceramic phase mass fraction of 0.1-20.0%, and a relative density of more than 80%.

[0016] As a preferred solution, the saturation magnetic flux density is greater than 800 mT, the resistivity is higher than 10 5 μΩ·cm, the cut-off frequency is higher than 100 MHz, the magnetic permeability is greater than 5, and the heat-resistant temperature is higher than 500 °C.

[0017] The present invention also provides a high-frequency magnetic device, including a metal coil, and further including the high-frequency magnetic composite material described in any one of the above solutions, wherein the metal coil is buried in the high-frequency magnetic composite material.

[0018] The present invention also provides a processing method of the high-frequency magnetic device described in the above solution, including:

[0019] Magnetic metal particles with a magnetic vortex structure, a solvent and a non-magnetic ceramic phase material are mixed and ground into a slurry;

[0020] The metal coil is buried in the slurry of the mold and formed under a low-temperature and low-pressure process.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] In the present invention, since traditional magnetic materials all have a multi-domain structure, the domain walls therein undergo domain wall resonance at high frequencies, resulting in a rapid attenuation of the magnetic permeability and thus being unusable. However, in the present invention, by using magnetic particles with a magnetic vortex structure, there are no domain walls, and magnetization at high frequencies is mainly based on magnetization rotation, rather than the traditional domain wall displacement mechanism, which can significantly increase the working frequency of the material to above 100 MHz. Due to the very large friction between ultra-fine powders (less than 10 μm) during pressing and forming, it is very difficult to form even with a pressure above 1 GPa, and it will cause the rupture of the insulating layer on the surface of the magnetic powder, and the magnetic powders will come into contact with each other to generate domain walls, reducing the working frequency. Therefore, the traditional method of preparing magnetic composite materials by die pressing is difficult to apply to ultra-fine magnetic powder composite materials. The high-frequency magnetic composite material and device obtained by the low-temperature and low-pressure sintering method of the present invention can be prepared under very low temperature (less than 300 °C) and very low pressure (less than 500 MPa) conditions, avoiding various defects of extreme conditions such as high temperature and high pressure in the traditional process, which is of great significance for energy conservation, consumption reduction, process simplification and efficiency improvement. At the same time, the enameled wire coil can be buried inside the magnetic composite material during the preparation process, avoiding high-frequency electromagnetic interference. Description of the Drawings

[0023] Figure 1 is the size diagram of the Fe-Si-Al magnetic powder in Embodiment 1 of the present invention;

[0024] Figure 2 is the schematic diagram of the magnetic vortex structure of the Fe-Si-Al magnetic powder in Embodiment 1 of the present invention;

[0025] Figure 3It is a comparison chart of the high-frequency magnetic spectrum of the magnetic composite material in Embodiment 1 of the present invention and that of the magnetic composite material obtained by traditional molding Detailed implementation manners

[0026] The technical solution of the present invention will be further explained and illustrated through specific embodiments below.

[0027] Embodiment 1:

[0028] The processing method of the magnetic composite material in this embodiment includes the following steps:

[0029] The gas-atomized iron-silicon-aluminum powder with an average particle size of 3 μm, water, and ammonium molybdate are mixed according to a mass percentage of 1:0.2:0.08, ground evenly into a slurry, placed in a mold, heated to 250 °C at a rate of 10 °C per minute, and at the same time, a pressure of 400 MPa is applied and the pressure is maintained for 1 hour to obtain the magnetic composite material.

[0030] Among them, as Figure 1 shown, the average size of the iron-silicon-aluminum magnetic powder is 3 μm and it has a magnetic vortex structure, as Figure 2 shown.

[0031] The performance of the magnetic composite material in this embodiment is tested. The saturation magnetization intensity is 0.85 T, the magnetic permeability is 13, the cut-off frequency is 1050 MHz, the resistivity is 2.1×10 6 μΩ·cm, the density is 5.0 g / cm 3 , and the heat-resistant temperature is 550 °C.

[0032] As Figure 3 shown, the magnetic permeability of the magnetic composite material in this embodiment can remain stable without attenuation at 1000 MHz, while if the traditional molding method (which can only be molded under a pressure of more than 1 GPa) is used, the magnetic composite material prepared will rapidly attenuate at 100 MHz.

[0033] The high-frequency magnetic device in this embodiment includes a metal coil and the magnetic composite material in this embodiment, and the metal coil is buried in the magnetic composite material.

[0034] The processing method of the high-frequency magnetic device of the present invention includes:

[0035] Mixing magnetic metal particles with a magnetic vortex structure, a solvent, and a non-magnetic ceramic phase material and grinding them into a slurry;

[0036] Burying the metal coil in the slurry of the mold and molding it under low-temperature and low-pressure processes.

[0037] Embodiment 2:

[0038] The processing method of the magnetic composite material in this embodiment includes the following steps:

[0039] The gas-atomized iron-silicon powder with an average particle size of 5 μm, 1 mol / L acetic acid solution, and zinc oxide are mixed in a mass percentage of 1:0.1:0.04, ground evenly into a slurry, placed in a mold, heated to 200 °C at a rate of 5 °C per minute, and simultaneously a pressure of 250 MPa is applied, and the pressure is maintained for 0.5 hours to obtain a magnetic composite material.

[0040] The magnetic composite material of this example is tested for performance. The saturation magnetization intensity is 1.65 T, the magnetic permeability is 50, the cut-off frequency is 1500 MHz, and the resistivity is 9.0×10 5 μΩ·cm, and the density is 6.3 g / cm 3 , and the heat-resistant temperature is 720 °C.

[0041] The high-frequency magnetic device of this example includes a metal coil and the magnetic composite material of this example, and the metal coil is buried in the magnetic composite material.

[0042] The processing method of the high-frequency magnetic device of the present invention includes:

[0043] Magnetic metal particles with a magnetic vortex structure, a solvent, and a non-magnetic ceramic phase material are mixed and ground into a slurry;

[0044] The metal coil is buried in the slurry of the mold and formed under low-temperature and low-pressure processes.

[0045] Example 3:

[0046] The processing method of the magnetic composite material of this example includes the following steps:

[0047] The carbonyl spherical iron powder with an average particle size of 2 μm, 0.5 mol / L citric acid solution, and titanium oxide are mixed in a mass percentage of 1:0.4:0.05, ground evenly into a slurry, placed in a mold, heated to 180 °C at a rate of 8 °C per minute, and simultaneously a pressure of 200 MPa is applied, and the pressure is maintained for 2 hours to obtain a magnetic composite material.

[0048] The magnetic composite material of this example is tested for performance. The saturation magnetization intensity is 1.90 T, the magnetic permeability is 90, the cut-off frequency is 1200 MHz, and the resistivity is 3.0×10 5 μΩ·cm, and the density is 6.9 g / cm 3 , and the heat-resistant temperature is 780 °C.

[0049] The high-frequency magnetic device of this example includes a metal coil and the magnetic composite material of this example, and the metal coil is buried in the magnetic composite material.

[0050] The processing method of the high-frequency magnetic device of the present invention includes:

[0051] Magnetic metal particles with a magnetic vortex structure, a solvent, and a non-magnetic ceramic phase material are mixed and ground into a slurry.

[0052] A metal coil is buried in the slurry of the mold and formed under a low-temperature and low-pressure process.

[0053] Example 4:

[0054] The processing method of the magnetic composite material in this example includes the following steps:

[0055] Water-vapor co-atomized amorphous iron-silicon-chromium powder with an average particle size of 5 μm, 1 mol / L oxalic acid solution, and molybdenum trioxide are mixed according to a mass percentage of 1:0.3:0.1, ground evenly into a slurry state, placed in a mold, heated to 280 °C at a rate of 10 °C per minute, and at the same time, a pressure of 350 MPa is applied, and the pressure is maintained for 1.5 hours to obtain a magnetic composite material.

[0056] The performance of the magnetic composite material in this example is tested. The saturation magnetization intensity is 1.05 T, the magnetic permeability is 20, the cut-off frequency is 930 MHz, and the resistivity is 2.5×10 6 μΩ·cm, and the density is 5.7 g / cm 3 , and the heat-resistant temperature is 550 °C.

[0057] The high-frequency magnetic device in this example includes a metal coil and the magnetic composite material in this example, and the metal coil is buried in the magnetic composite material.

[0058] The processing method of the high-frequency magnetic device of the present invention includes:

[0059] Magnetic metal particles with a magnetic vortex structure, a solvent, and a non-magnetic ceramic phase material are mixed and ground into a slurry.

[0060] A metal coil is buried in the slurry of the mold and formed under a low-temperature and low-pressure process.

[0061] Comparative Example 1:

[0062] Commercially available mechanically crushed iron-silicon powder is sieved through 400 meshes, and the average particle size is 30 μm, which has a typical multi-domain structure powder. Iron-silicon powder, water, and ammonium molybdate are mixed according to a mass percentage of 1:0.2:0.08, ground evenly into a slurry state, placed in a mold, heated to 250 °C at a rate of 10 °C per minute, and at the same time, a pressure of 400 MPa is applied, and the pressure is maintained for 1 hour to obtain a magnetic composite material.

[0063] The performance of the magnetic composite material in this comparative example is tested. The saturation magnetization intensity is 1.7 T, the magnetic permeability is 50, the cut-off frequency is 500 KHz, and the resistivity is 3.8×10 5 μΩ·cm, and the density is 6.8 g / cm3 , heat resistance temperature is 550 °C.

[0064] It can be seen that using metal particles with a vortex magnetic structure can significantly increase the cut-off frequency of the magnetic composite material.

[0065] Comparative Example 2:

[0066] The gas atomized Fe-Si-Al powder with an average particle size of 3 μm, water, and ammonium molybdate were mixed according to a mass percentage of 1:0.2:0.08, ground evenly into a slurry, placed in a mold, and formed by a traditional die pressing method at a pressure of 1.5 GPa for 30 seconds to obtain a magnetic composite material.

[0067] The performance of the magnetic composite material of this comparative example was tested. The saturation magnetization intensity was 0.91 T, the magnetic permeability was 21, the cut-off frequency was 100 MHz, and the resistivity was 0.8×10 6 μΩ·cm, and the density was 5.3 g / cm 3 , heat resistance temperature is 550 °C.

[0068] It can be seen that using metal particles with a vortex magnetic structure and the low-temperature and low-pressure sintering method proposed in the present invention are necessary conditions for increasing the cut-off frequency of the magnetic composite material.

[0069] As an alternative to the above embodiment, a magnetic composite material is sintered from metal particles with a vortex magnetic structure, a solvent, and a non-magnetic ceramic or ceramic precursor under the combined action of low temperature and low pressure, wherein the metal mass fraction is 80.0 - 99.9%, the ceramic phase mass fraction is 0.1 - 20.0%, and the relative density is above 80%, preferably above 90%.

[0070] As an alternative to the above embodiment, the magnetic metal particles are based on iron, nickel, cobalt, rare earth metals, and their alloys. Preferably, the metal is based on one or several of iron, Fe-Si, Fe-Si-Al, Fe-Ni, Fe-Ni-Cr, Fe-Si-Cr, Fe-Si-Ni, Fe-Ni-Mo, Fe-Co, Fe-Co-Si, iron-based amorphous, and iron-based nanocrystals. Preferably, the metal is spherical or quasi-spherical in shape, and the metal particle size is 5 nm to 10 μm, preferably 50 nm to 5 μm.

[0071] As an alternative to the above embodiment, the solvent is one of water, alcohol solvents, organic acid solutions, inorganic acid solutions, and alkali solutions. Preferably, it is an easily volatile or decomposable solvent, and preferably one of water, ethanol, acetic acid solution, citric acid solution, and oxalic acid solution.

[0072] As an alternative to the above embodiments, the non-magnetic ceramic precursor is soluble in a solvent and is one of molybdic acid, ammonium molybdate, bismuth nitrate, bismuth subnitrate, boric acid, lead nitrate, metal acetate, acetylacetonate, oxalate, citrate. The non-magnetic ceramic is partially soluble in the solvent under low-temperature and low-pressure conditions and is the first one among molybdenum trioxide, zinc oxide, titanium oxide, barium titanate, bismuth trioxide, boron trioxide, lead oxide.

[0073] As an alternative to the above embodiments, the low-temperature and low-pressure conditions are that the temperature is lower than 300 °C, the pressure is less than 500 MPa, the heating rate is 1-20 °C / minute, and the pressure holding time is 1 minute to 2 hours, which can be specifically determined according to actual application requirements.

[0074] In view of the large number of embodiments of the present invention, all components, component contents, and process parameters can be determined according to application requirements within the corresponding ranges. The experimental data of each embodiment are huge and numerous, and it is not suitable to list them one by one here. However, the contents to be verified and the final conclusions obtained in each embodiment are close.

[0075] The above description only details the preferred embodiments and principles of the present invention. For those of ordinary skill in the art, based on the idea provided by the present invention, there will be changes in the specific implementation manners, and these changes should also be regarded as the protection scope of the present invention.

Claims

1. A processing method for a high-frequency magnetic composite material, characterized in that, Comprising: Magnetic metal particles with a magnetic vortex structure, a solvent, and a non-magnetic ceramic phase material are mixed and ground into a slurry; The slurry is placed in a mold and formed under a low-temperature and low-pressure process; Among them, the conditions of the low-temperature and low-pressure process are that the temperature is lower than 300 °C and the pressure is less than 500 MPa.

2. The processing method according to claim 1, characterized in that, The magnetic metal particles are based on iron, nickel, cobalt, rare earth metals, and their alloys, and the shape of the magnetic metal particles is spherical or quasi-spherical.

3. The processing method according to claim 2, characterized in that, The magnetic metal particles are one or more of iron, iron-silicon, iron-silicon-aluminum, iron-nickel, iron-nickel-chromium, iron-silicon-chromium, iron-silicon-nickel, iron-nickel-molybdenum, iron-cobalt, iron-cobalt-silicon, iron-based amorphous, and iron-based nanocrystals.

4. The processing method according to claim 1, characterized in that, The non-magnetic ceramic phase material is dissolved in the solvent.

5. The processing method according to claim 1, characterized in that, The solvent is one of water, alcohol solvents, organic acid solutions, inorganic acid solutions, and alkali solutions.

6. The processing method according to claim 5, characterized in that, The solvent is one of ethanol, acetic acid solution, citric acid solution, and oxalic acid solution.

7. The processing method according to claim 1, characterized in that, The mass fraction of the solvent in the slurry is 5-50%.

8. The processing method according to claim 1, characterized in that, The non-magnetic ceramic phase material is a ceramic or a ceramic precursor. The ceramic is selected from one of molybdenum trioxide, zinc oxide, titanium oxide, barium titanate, bismuth trioxide, boron trioxide, and lead oxide. The ceramic precursor is selected from one of molybdic acid, ammonium molybdate, bismuth nitrate, basic bismuth nitrate, boric acid, lead nitrate, metal acetate, acetylacetonate, oxalate, and citrate.

9. A high-frequency magnetic composite material prepared by the processing method according to any one of claims 1-8, characterized in that, The mass fraction of the metal is 80.0-99.9%, the mass fraction of the ceramic phase is 0.1-20.0%, and the relative density is above 80%.

10. The high-frequency magnetic composite material according to claim 9, characterized in that, The saturation magnetic flux density is greater than 800 mT, the resistivity is higher than 10 5 μΩ·cm, the cut-off frequency is higher than 100 MHz, the magnetic permeability is greater than 5, and the heat-resistant temperature is higher than 500 °C.

11. A high-frequency magnetic device, including a metal coil, characterized in that, It also includes the high-frequency magnetic composite material as described in claim 8, and a metal coil is buried in the high-frequency magnetic composite material.

12. The processing method of the high-frequency magnetic device according to claim 11, characterized in that, Comprising: Magnetic metal particles with a magnetic vortex structure, a solvent, and a non-magnetic ceramic phase material are mixed and ground into a slurry; A metal coil is buried in the slurry of the mold and formed under a low-temperature and low-pressure process.

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