Composite magnetic material, preparation method thereof and magnetic device

Abstract

The invention provides a composite magnetic material, a preparation method thereof and a magnetic device. The composite magnetic material comprises alloy powder and an epoxy resin material, the epoxy resin material and the alloy powder are uniformly distributed, and the composite magnetic material is composite powder; the alloy powder comprises a first nanocrystalline with a first particle size, a second alloy with a second particle size and a third alloy with a third particle size; the first particle size is larger than the second particle size which is larger than the third particle size; the alloy powder further comprises inorganic coating layers arranged on the surfaces of the first nanocrystalline, the second alloy and the third alloy. The composite magnetic material prepared by the invention not only has good fluidity, but also can realize relatively high relative permeability and relatively low magnetic loss in a high-frequency band, and provides powerful support for miniaturization, lightness, thinness and high-performance development of magnetic devices.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite magnetic materials, and particularly relates to a composite magnetic material, a preparation method thereof and a magnetic device. BACKGROUND

[0002] At present, the preparation process of inductors includes winding type, laminated type, one-piece molding type and thin film inductor. The winding type inductor is generally preformed with a magnetic core and then wound, and needs to be shielded by magnetic glue. Due to the structural defects, there is a large leakage magnetic flux, which will interfere with the nearby magnetic components. The laminated inductor is formed by the slurry flow casting and lamination, and the solid content of the magnetic phase is 50%-60%. After sintering, the magnet density is low, and the performance of the prepared inductor is slightly low. The one-piece inductor needs to be formed by high pressure, which will deform the coil and cause problems such as poor turn-to-turn voltage resistance. The product reliability has a great risk, and the internal stress of the magnetic powder formed by high pressure is difficult to eliminate, resulting in high inductor loss and low temperature rise current.

[0003] At present, the inductor made of the existing plastic packaging material has certain defects in performance, such as poor magnetic permeability and power consumption of the material.

[0004] Therefore, it is necessary to develop a new plastic packaging material to improve the magnetic permeability of the material and reduce the power consumption. SUMMARY

[0005] In view of the deficiencies in the prior art, the purpose of the present application is to provide a composite magnetic material, a preparation method thereof and a magnetic device, in particular to provide a high-conductivity high-saturation low-loss plastic packaging material suitable for sheet-type magnetic devices, a preparation method thereof and a magnetic device. The composite magnetic material not only has good fluidity, but also can realize high relative magnetic permeability and low magnetic loss in the high frequency band.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a composite magnetic material, which comprises an alloy powder and an epoxy resin material; the epoxy resin material is uniformly distributed with the alloy powder and the composite magnetic material is a composite powder; the alloy powder comprises first nanocrystals of a first particle size, second alloys of a second particle size and third alloys of a third particle size; the first particle size is larger than the second particle size, and the second particle size is larger than the third particle size; the alloy powder further comprises an inorganic coating layer arranged on the surfaces of the first nanocrystals, the second alloys and the third alloys.

[0008] The present application is specially designed as follows: on the one hand, by grading mixing coarse-grained nanocrystalline alloy, medium-grained Fe-based alloy and fine-grained alloy, a structure similar to close packing is constructed, effectively reducing the internal voids and defects of the material; on the other hand, an epoxy resin material with a low softening point (about 100℃) and a low viscosity (for example, 20cps at 150℃, ICI test under the condition of 750rpm) is selected, which significantly improves the flowability of the plastic packaging material. This optimized material can fully spread during mold filling, effectively avoiding problems such as holes, bubbles and insufficient filling, and is especially suitable for one-piece molding or whole board molding of magnetic devices.

[0009] In the present application, the composite magnetic material refers to a functional composite material formed by compounding a magnetic material and a plastic matrix (such as an epoxy resin). The composite magnetic material can be prepared by processes commonly used in the art, such as plastic packaging, hot pressing and / or packaging.

[0010] Preferably, the particle size of the first nanocrystalline is in the range of 10-20 μm, for example, it can be 10 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm, etc., but is not limited to the listed values, and other unlisted values within the range are also applicable.

[0011] Preferably, the volume proportion of the first nanocrystalline in the alloy powder is 70-80%, for example, it can be 70%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79% or 80%, etc., but is not limited to the listed values, and other unlisted values within the range are also applicable.

[0012] Preferably, the particle size of the second alloy is in the range of 2-5 μm, for example, it can be 2 μm, 2.4 μm, 2.7 μm, 3 μm, 3.4 μm, 3.7 μm, 4 μm, 4.4 μm, 4.7 μm or 5 μm, etc., but is not limited to the listed values, and other unlisted values within the range are also applicable.

[0013] Preferably, the volume proportion of the second alloy in the alloy powder is 5-15%, for example, it can be 5%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, etc., but is not limited to the listed values, and other unlisted values within the range are also applicable.

[0014] Preferably, the particle size of the third alloy is in the range of 0.5-1.5 μm, for example, it can be 0.5 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm or 1.5 μm, etc., but is not limited to the listed values, and other unlisted values within the range are also applicable.

[0015] Preferably, the third alloy accounts for 10-20% of the volume of the alloy powder, for example, it can be 10%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0016] Preferably, the first nanocrystal, the second alloy, and the third alloy each independently comprise an iron-based alloy.

[0017] Preferably, the first nanocrystal, the second alloy, and the third alloy are each independently selected from any one or at least two combinations of FeSi alloys, FeSiB alloys, FeSiAl alloys, FeNi alloys, FeCuNi alloys, FeCo alloys, FeCrSi alloys, FeSiCo alloys, carbonyl iron, FeMn alloys, FeZn alloys, FeZr alloys, or FeNb alloys. Preferably, the first iron-based nanocrystal, the second iron-based alloy, and the third iron-based alloy are made of different materials. Typical but non-limiting combinations include combinations of FeSi alloys and FeSiB alloys, combinations of FeSiAl alloys and FeSiB alloys, combinations of FeSi alloys and FeSiAl alloys, combinations of FeNi alloys and FeZr alloys, combinations of FeCo alloys and FeSiB alloys, combinations of FeNb alloys and FeCo alloys, and combinations of FeCrSi alloys and FeNb alloys.

[0018] Preferably, the powders of the first nanocrystal, the second alloy, and the third alloy are all prepared by gas atomization. Compared with water atomization powder preparation, the powder obtained by this method has better sphericity, which helps to improve the flowability of the iron-based alloy powder.

[0019] Preferably, the thickness of the inorganic coating layer is 10~40nm, for example, it can be 10nm, 14nm, 17nm, 20nm, 24nm, 27nm, 30nm, 34nm, 37nm or 40nm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the inorganic coating layer is made of any one or at least two of Al2O3, SiO2, TiO2, ZrO2, ZnO, SnO2, MgO or CaO, wherein typical but non-limiting combinations are the combination of Al2O3 and SiO2, the combination of TiO2 and SiO2, the combination of CaO and TiO2, the combination of ZrO2 and SiO2, the combination of ZnO and SnO2, and the combination of Al2O3 and MgO.

[0021] Preferably, the inorganic coating layer comprises, in a radial direction outward, a first inorganic coating layer, a second inorganic coating layer, and a third inorganic coating layer.

[0022] Preferably, the first inorganic coating layer, the second inorganic coating layer, and the third inorganic coating layer are made of different materials.

[0023] Preferably, the first inorganic coating layer is Al2O3, the second inorganic coating layer is SiO2, and the third inorganic coating layer is TiO2.

[0024] The present invention preferably employs a three-layer inorganic coating layer, which can improve the overall performance of the composite magnetic material.

[0025] Preferably, the epoxy resin material in the composite magnetic material accounts for 2-4% by mass, for example, 2%, 2.3%, 2.5%, 2.7%, 2.9%, 3.2%, 3.4%, 3.6%, 3.8% or 4%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] Preferably, the softening point of the epoxy resin material is ≤110℃, for example, it can be 110℃, 109℃, 108℃, 107℃, 105℃, 102℃, 101℃, 100℃, 98℃, 97℃ or 95℃, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0027] Preferably, the raw materials for preparing the epoxy resin material include epoxy resin, phenolic resin, curing accelerator, wax, and aluminate coupling agent.

[0028] Preferably, the epoxy resin comprises any one or a combination of at least two of glycidyl ethers, glycidyl esters, glycidyl amines, aliphatic resins, or alicyclic resins, wherein typical but non-limiting combinations are combinations of glycidyl ethers and glycidyl esters, combinations of glycidyl amines and glycidyl esters, combinations of glycidyl ethers and glycidyl amines, combinations of aliphatic resins and glycidyl esters, combinations of alicyclic resins and aliphatic resins, and combinations of alicyclic resins and glycidyl esters.

[0029] Preferably, the epoxy resin includes, but is not limited to, any one or a combination of at least two of the following: ethylbenzene-phenol type self-flame-retardant epoxy resin, aralkylphenol type self-flame-retardant epoxy resin, trifunctional epoxy resin, bisphenol A type phenolic epoxy resin, tetramethylbisphenol F crystalline epoxy resin, tetramethylbiphenyl crystalline epoxy resin, o-methylphenolic epoxy resin, bisphenol S type epoxy resin, bisphenol propane type epoxy resin, phenolic polyepoxy resin (such as phenol-formaldehyde type, o-cresol-formaldehyde type polyepoxy resin), resorcinol type epoxy resin, resorcinol-formaldehyde type epoxy resin, tetraphenol ethane type epoxy resin, trihydroxyphenylmethane type epoxy resin, aliphatic polyol glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, alicyclic epoxy resin, or aliphatic epoxy resin.

[0030] Preferably, the phenolic resin is a synthetic resin prepared by addition reaction and condensation reaction of phenolic compounds (phenol, cresol, nonylphenol, aralkylphenol, cashew phenol, octylphenol, bisphenol A, xylenol or a mixture of several phenols) and aldehyde compounds (formaldehyde, acetaldehyde, furfural or a mixture of several aldehydes).

[0031] Preferably, the phenolic resin includes any one or a combination of at least two of the following: phenol-formaldehyde type phenolic resin, bisphenol A type phenolic resin, XYLOK type aralkyl phenolic resin, biphenyl phenol type phenolic resin, trifunctional phenolic resin, naphthol phenolic resin, thermoplastic phenolic resin (obtained by reacting excess phenol with formaldehyde under acidic conditions), thermosetting phenolic resin (formaldehyde-phenol molar ratio greater than 1, obtained by reacting under alkaline catalyst and heating), or butylphenol-cresol resin (such as phenolic resin 7522, commonly used in rubber materials such as chloroprene rubber and compression adhesive formulation systems).

[0032] Preferably, the curing accelerator comprises any one of 2-ethyl-4-methylimidazole, 1-cyanoethyl-substituted imidazole, 2-undecylimidazole, or 2-phenylimidazole, wherein typical but non-limiting combinations are combinations of 2-ethyl-4-methylimidazole and 1-cyanoethyl-substituted imidazole, combinations of 2-undecylimidazole and 1-cyanoethyl-substituted imidazole, and combinations of 2-ethyl-4-methylimidazole and 2-undecylimidazole.

[0033] Preferably, the wax comprises at least one or a combination of at least two of fully refined paraffin wax, Clariant wax, carnauba wax, palm wax, or microcrystalline wax, wherein typical but non-limiting combinations are combinations of fully refined paraffin wax and Clariant wax, combinations of carnauba wax and Clariant wax, combinations of fully refined paraffin wax and carnauba wax, combinations of palm wax and Clariant wax, and combinations of fully refined paraffin wax and microcrystalline wax.

[0034] Preferably, the particle size range of the composite magnetic material is 20~30μm, for example, it can be 20μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm or 30μm, etc., but is not limited to the listed values, and other unlisted values ​​in this range are also applicable.

[0035] Preferably, the fluidity of the composite magnetic material is 45~50s, for example, 45s, 46s, 47s, 48s, 49s or 50s, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Flowability refers to the ability of composite magnetic materials to fill the mold during injection molding. It is generally measured by a flowability tester, such as the JL-T-6857 flowability tester, which records the time it takes for all the powder to flow out after the flow tester is filled and spread out. The unit is seconds.

[0037] Preferably, the loose packing density of the composite magnetic material is 2.2~2.4 g / cm³. 3 For example, it could be 2.2 g / cm³ 3 2.23 g / cm 3 2.25g / cm 3 2.27 g / cm 3 2.29 g / cm 3 2.32 g / cm 3 2.34 g / cm 3 2.36 g / cm 3 2.38g / cm 3 Or 2.4g / cm 3 This includes, but is not limited to, the listed values; other unlisted values ​​within this range also apply.

[0038] Loose packing density refers to the mass per unit volume of a composite magnetic material when it is freely filled into a container of a specified volume in a naturally loose state. It can generally be tested using a loose packing density tester.

[0039] Preferably, the magnetic permeability μi of the composite magnetic material at 100KHz is ≥55, for example, it can be 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65 or 68, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] Preferably, the composite magnetic material comprises the following components by weight percentage: Fe: 70~75%, Ni: 9.5~12%, C: 1.5~7%, Si: 4~5.5%, Cr: 2.5~4.5%, Cu: 0.3~1.5%, P: 0.3~1.5%, Al: 0.3~1.5%, Nb: 0.2~0.8%, with the remainder being O.

[0041] Wherein, Fe: 70~75%, for example, it can be 70%, 70.6%, 71.2%, 71.7%, 72.3%, 72.8%, 73.4%, 73.9%, 74.5% or 75%, etc., but is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0042] Ni: 9.5~12%, for example, it can be 9.5%, 9.8%, 10.1%, 10.4%, 10.7%, 10.9%, 11.2%, 11.5%, 11.8% or 12%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] C: 1.5~7%, for example, it can be 1.5%, 2.2%, 2.8%, 3.4%, 4%, 4.6%, 5.2%, 5.8%, 6.4% or 7%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Si: 4~5.5%, for example, it can be 4%, 4.2%, 4.4%, 4.5%, 4.7%, 4.9%, 5%, 5.2%, 5.4% or 5.5%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Cr: 2.5~4.5%, for example, it can be 2.5%, 2.8%, 3%, 3.2%, 3.4%, 3.7%, 3.9%, 4.1%, 4.3% or 4.5%, etc., but is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0046] Cu: 0.3~1.5%, for example, it can be 2.5%, 2.8%, 3%, 3.2%, 3.4%, 3.7%, 3.9%, 4.1%, 4.3% or 4.5%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] P: 0.3~1.5%, for example, it can be 2.5%, 2.8%, 3%, 3.2%, 3.4%, 3.7%, 3.9%, 4.1%, 4.3% or 4.5%, etc., but is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0048] Al: 0.3~1.5%, for example, it can be 2.5%, 2.8%, 3%, 3.2%, 3.4%, 3.7%, 3.9%, 4.1%, 4.3% or 4.5%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0049] Ti: 0.2~0.8%, for example, it can be 0.2%, 0.27%, 0.34%, 0.4%, 0.47%, 0.54%, 0.6%, 0.67%, 0.74% or 0.8%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] In a second aspect, the present invention provides a method for preparing the composite magnetic material described in the first aspect, the method comprising:

[0051] (1) Mix the first nanocrystal with the first particle size, the second alloy with the second particle size, and the third alloy with the third particle size to obtain graded powder.

[0052] (2) The graded powder is acidified with chromic acid or phosphoric acid, and then atomic layer deposition is performed to coat the surface of the first nanocrystal, the second alloy and the third alloy with an inorganic coating layer to obtain the first coated graded powder.

[0053] (3) The raw materials, solvent and first coated grade powder of epoxy resin material are mixed to obtain slurry, and the slurry is spray granulated to obtain the composite magnetic material.

[0054] The preparation method provided by the present invention improves the surface activity of the alloy powder and enhances the adhesion of the subsequent coating layer by acidifying the graded powder with chromic acid or phosphoric acid.

[0055] Preferably, the acidification temperature in step (2) is 40~60℃, for example, it can be 40℃, 43℃, 45℃, 47℃, 49℃, 52℃, 54℃, 56℃, 58℃ or 60℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0056] Preferably, the mass ratio of phosphoric acid or chromic acid to graded powder in the acidification treatment is 0.05~0.3wt%, for example, it can be 0.05wt%, 0.08wt%, 0.11wt%, 0.14wt%, 0.17wt%, 0.19wt%, 0.22wt%, 0.25wt%, 0.28wt%, or 0.3wt%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] Preferably, after the acidification treatment, the product is further subjected to air drying, baking, and sieving in sequence.

[0058] Preferably, the drying temperature is 100~130℃, for example, it can be 100℃, 104℃, 107℃, 110℃, 114℃, 117℃, 120℃, 124℃, 127℃ or 130℃, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0059] Preferably, the drying time is 40 to 80 minutes, for example, 40 minutes, 45 minutes, 49 minutes, 54 minutes, 58 minutes, 63 minutes, 67 minutes, 72 minutes, 76 minutes or 80 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0060] Preferably, the sieving process involves passing through a 60-mesh sieve.

[0061] Preferably, the solvent in step (3) includes any one or a combination of at least two of anhydrous ethanol, acetone, toluene, xylene or butyl acetate, wherein typical but non-limiting combinations are the combination of anhydrous ethanol and acetone, the combination of toluene and acetone, the combination of anhydrous ethanol and toluene, the combination of xylene and acetone, and the combination of anhydrous ethanol and butyl acetate.

[0062] Preferably, the mixing speed in step (3) is 30~60 rpm, for example, it can be 30 rpm, 34 rpm, 37 rpm, 40 rpm, 44 rpm, 47 rpm, 50 rpm, 54 rpm, 57 rpm or 60 rpm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0063] Preferably, the mixing time in step (3) is 30 to 60 minutes, for example, it can be 30 minutes, 34 minutes, 37 minutes, 40 minutes, 44 minutes, 47 minutes, 50 minutes, 54 minutes, 57 minutes or 60 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0064] Preferably, the mixing in step (3) includes: first mixing the raw materials and solvent of the epoxy resin material, and then adding the first coated grade powder.

[0065] Preferably, the solid content of the slurry is 75-85 wt%, for example, it can be 75 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, or 85 wt%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0066] Preferably, the inlet air temperature for spray granulation is 140~160℃, for example, it can be 140℃, 143℃, 145℃, 147℃, 149℃, 152℃, 154℃, 156℃, 158℃ or 160℃, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0067] Preferably, the outlet air temperature of the spray granulation is 70~90℃, for example, it can be 70℃, 73℃, 75℃, 77℃, 79℃, 82℃, 84℃, 86℃, 88℃ or 90℃, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0068] Preferably, the rotation speed of the spray granulation is 7000~9000 rpm, for example, it can be 7000 rpm, 7223 rpm, 7445 rpm, 7667 rpm, 7889 rpm, 8112 rpm, 8334 rpm, 8556 rpm, 8778 rpm or 9000 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0069] Thirdly, the present invention provides a magnetic device, the magnetic device comprising the composite magnetic material described in the first aspect.

[0070] Compared with the prior art, the present invention has at least the following beneficial effects:

[0071] (1) The composite magnetic material provided by the present invention solves the problem of high permeability and high bias, improves the permeability and saturation characteristics of magnetic materials, and increases the initial permeability of iron-based alloy powder used for plastic encapsulation by 50%.

[0072] (2) The composite magnetic material provided by this invention uses a plastic encapsulation process, resulting in a loss as low as 1543 mw / cm. 3 (1MHz@50mT) and below;

[0073] (3) The composite magnetic material provided by the present invention can be injection molded in one piece without complicated processes. The process is simple and easy to automate, which can effectively reduce costs. Detailed Implementation

[0074] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0075] It should be understood that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0076] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0077] Examples 1-7

[0078] Examples 1-7 provide a composite magnetic material, which includes alloy powder and epoxy resin material; the epoxy resin material and the alloy powder are uniformly distributed and the composite magnetic material is a composite powder.

[0079] The alloy powder comprises 75% by volume of 15μm first iron-based nanocrystals (FeSi nanocrystals, Fe content 85%, Si content 15%), 10% by volume of 2.5μm second iron-based alloy (FeSiCr alloy, Fe content 85%, Si content 10%, Cr content 5%), and 15% by volume of 0.7μm third iron-based alloy (FeNi alloy, Fe content 80%, Ni content 20%). The alloy powder also includes a 15nm inorganic coating layer disposed on the surface of the first iron-based nanocrystals, the second iron-based alloy, and the third iron-based alloy. The inorganic coating layer comprises, in radial direction outward, a first inorganic coating layer Al2O3, a second inorganic coating layer SiO2, and a third inorganic coating layer TiO2.

[0080] The softening point of the epoxy resin material is 102℃.

[0081] Examples 1-7 also provide a method for preparing the above-mentioned composite magnetic material, the method comprising:

[0082] (1) Mix the first iron-based nanocrystals with the first particle size, the second iron-based alloy with the second particle size, and the third iron-based alloy with the third particle size to obtain graded powder;

[0083] (2) The graded powder is acidified with a phosphoric acid to alcohol mixture (the mass ratio of phosphoric acid to alcohol is 1:10) according to the mass ratio of phosphoric acid to graded powder of 0.3wt%. After acidification, it is air-dried, dried at 120℃ for 50min and passed through a 60-mesh sieve. Then, atomic layer deposition is performed to coat the surface of the first iron nanocrystal, the second iron alloy and the third iron alloy with an inorganic coating layer to obtain the first coated graded powder.

[0084] (3) Epoxy resin (specifically KUKDO SMP-105), phenolic resin (specifically BASF PF85), curing accelerator (specifically 2-ethyl-4-methylimidazolium), wax and aluminate coupling agent are added to a solvent (anhydrous ethanol), stirred for 40 min, and then the first coated gradation powder is added. After stirring at a speed of 45 rpm, a slurry with a solid content of 80 wt% is obtained. The slurry is then spray-granulated. The inlet air temperature of the spray granulation is 150 ℃, the outlet air temperature is 80 ℃, and the speed is 8000 rpm to obtain the composite magnetic material.

[0085] Comparative Example 1

[0086] Comparative Example 1 provides a composite magnetic material, which differs from Example 1 in that the first iron-based nanocrystals are replaced with FeSiCr amorphous materials of the same particle size (FeSiCr alloy, with Fe content of 85%, Si content of 10%, and Cr content of 15%).

[0087] Comparative Example 2

[0088] Comparative Example 2 provides a composite magnetic material, which differs from Example 7 in that the first iron-based nanocrystals are replaced with FeSiCr amorphous materials of the same particle size (FeSiCr alloy, with Fe content of 85%, Si content of 10%, and Cr content of 15%).

[0089] Comparative Example 3

[0090] Comparative Example 3 provides a composite magnetic material, which differs from Example 1 in that the particle sizes of the first iron-based nanocrystals and the third iron-based alloy are interchanged, i.e., the particle size of the first iron-based nanocrystals is 0.7 μm and the particle size of the third iron-based alloy is 15 μm.

[0091] The compositions of the composite magnetic materials in Examples 1-7 and Comparative Examples 1-3 are shown in Table 1.

[0092] Table 1

[0093]

[0094] The elemental composition of the composite magnetic materials in Examples 1-7 and Comparative Examples 1-3 is shown in Table 2.

[0095] Table 2

[0096]

[0097] Test methods: The particle size range of the composite magnetic material was tested using a laser particle size analyzer; the loose density of the composite magnetic material was tested using a loose density tester (container volume 56.4mL); the flowability of the composite magnetic material was measured using a JL-T-6857 flowability tester; the modulus flow was tested after curing at 180℃ for 300s; the permeability μi was tested at 1MHz and 1V; the rate of decrease of the superimposed current of 18A was tested at 100kHz and 1V (instrument 6500B), with each 1A as one node; the insulation performance was tested at 100V and 1MΩ; the withstand voltage performance was tested at 0.1mA, test time: 10s, voltage: 500~6000V; and the power consumption was tested at 1MHz, 50mT, and 25℃.

[0098] The properties of the composite magnetic materials in Examples 1-7 and Comparative Examples 1-3 are shown in Table 3.

[0099] Table 3

[0100]

[0101] Example 8

[0102] This embodiment provides a composite magnetic material, which includes alloy powder and epoxy resin material; the epoxy resin material and the alloy powder are uniformly distributed, and the composite magnetic material is a composite powder.

[0103] The alloy powder comprises 70% by volume of 10μm first iron-based nanocrystals (FeSi nanocrystals, Fe content 85%, Si content 15%), 10% by volume of 5μm second iron-based alloy (FeSiCr alloy, Fe content 85%, Si content 10%, Cr content 5%), and 20% by volume of 1.5μm third iron-based alloy (FeNi alloy, Fe content 80%, Ni content 20%). The alloy powder also includes a 40nm inorganic coating layer disposed on the surface of the first iron-based nanocrystals, the second iron-based alloy, and the third iron-based alloy. The inorganic coating layer comprises, in radial direction outward, a first inorganic coating layer Al2O3, a second inorganic coating layer SiO2, and a third inorganic coating layer TiO2.

[0104] The epoxy resin material accounts for 2% of the mass of the composite magnetic material; the softening point of the epoxy resin material is 102℃.

[0105] This embodiment also provides a method for preparing the above-mentioned composite magnetic material, the method comprising:

[0106] (1) Mix the first iron-based nanocrystals with the first particle size, the second iron-based alloy with the second particle size, and the third iron-based alloy with the third particle size to obtain graded powder;

[0107] (2) The graded powder is acidified with a phosphoric acid to alcohol mixture (the mass ratio of phosphoric acid to alcohol is 2:10) according to the mass ratio of phosphoric acid to graded powder of 0.05wt%. After acidification, it is air-dried, dried at 130℃ for 80min and passed through a 60-mesh sieve. Then, atomic layer deposition is performed to coat the surface of the first iron nanocrystal, the second iron alloy and the third iron alloy with an inorganic coating layer to obtain the first coated graded powder.

[0108] (3) Epoxy resin (specifically KUKDO SMP-105), phenolic resin (specifically BASF PF85), curing accelerator (specifically 1-cyanoethyl substituted imidazole), wax and aluminate coupling agent are added to a solvent (anhydrous ethanol), stirred for 30 min, and then the first coated gradation powder is added. After stirring at a speed of 60 rpm, a slurry with a solid content of 85 wt% is obtained. The slurry is then spray-granulated. The inlet air temperature of the spray granulation is 160 ℃, the outlet air temperature is 70 ℃, and the speed is 7000 rpm to obtain the composite magnetic material.

[0109] Example 9

[0110] This embodiment provides a composite magnetic material, which includes alloy powder and epoxy resin material; the epoxy resin material and the alloy powder are uniformly distributed, and the composite magnetic material is a composite powder.

[0111] The alloy powder comprises 80% by volume of 20μm first iron-based nanocrystals (FeSi nanocrystals, Fe content 85%, Si content 15%), 5% by volume of 2μm second iron-based alloy (FeSiB alloy, Fe content 85%, Si content 10%, B content 5%), and 15% by volume of 0.5μm third iron-based alloy (FeNi alloy, Fe content 80%, Ni content 20%). The alloy powder also includes a 10nm inorganic coating layer disposed on the surface of the first iron-based nanocrystals, the second iron-based alloy, and the third iron-based alloy. The inorganic coating layer comprises, in radial direction outward, a first inorganic coating layer Al2O3, a second inorganic coating layer SiO2, and a third inorganic coating layer TiO2.

[0112] The epoxy resin material accounts for 4% of the mass of the composite magnetic material; the softening point of the epoxy resin material is 102 (≤110)℃.

[0113] This embodiment also provides a method for preparing the above-mentioned composite magnetic material, the method comprising:

[0114] (1) Mix the first iron-based nanocrystals with the first particle size, the second iron-based alloy with the second particle size, and the third iron-based alloy with the third particle size to obtain graded powder;

[0115] (2) The graded powder is acidified with a phosphoric acid to alcohol mixture (the mass ratio of phosphoric acid to alcohol is 3:10) according to the mass ratio of phosphoric acid to graded powder of 0.3wt%. After acidification, it is air-dried, dried at 100℃ for 40 min and passed through a 60-mesh sieve. Then, atomic layer deposition is performed to coat the surface of the first iron nanocrystal, the second iron alloy and the third iron alloy with an inorganic coating layer to obtain the first coated graded powder.

[0116] (3) Epoxy resin (specifically KUKDO SMP-105), phenolic resin (specifically BASF PF85), curing accelerator (specifically 2-phenylimidazole), wax and aluminate coupling agent are added to a solvent (anhydrous ethanol), stirred for 60 min, and then the first coated gradation powder is added. After stirring at a speed of 30 rpm, a slurry with a solid content of 75 wt% is obtained. The slurry is then spray-granulated. The inlet air temperature of the spray granulation is 1460℃, the outlet air temperature is 90℃, and the speed is 9000 rpm to obtain the composite magnetic material.

[0117] Example 10

[0118] This embodiment provides a composite magnetic material. Except for the inorganic coating layer, which is only an Al2O3 coating layer, the composite magnetic material is the same as that in Embodiment 1, and will not be described again here.

[0119] Example 11

[0120] This embodiment provides a composite magnetic material. Except for the inorganic coating layer, which is only a SiO2 coating layer, the composite magnetic material is the same as that in Embodiment 1, and will not be described again here.

[0121] Example 12

[0122] This embodiment provides a composite magnetic material. Except for the total thickness of the inorganic coating layer being 50 nm, the composite magnetic material is the same as that in Embodiment 1, and will not be described again here.

[0123] Example 13

[0124] This embodiment provides a composite magnetic material. Except for the total thickness of the inorganic coating layer being 5 nm, the composite magnetic material is the same as that in Embodiment 1, and will not be described again here.

[0125] Example 14

[0126] This embodiment provides a composite magnetic material. Except for not performing the acidification treatment in step (2), the composite magnetic material is the same as that in embodiment 1, and will not be described again here.

[0127] The composition of the composite magnetic materials in Examples 8 and 9 is shown in Table 4.

[0128] Table 4

[0129]

[0130] In Examples 10-14, the mass ratios of alloy-grade powder, epoxy resin, phenolic resin, curing accelerator, wax, and aluminate coupling agent in the composite magnetic materials are the same as in Example 1.

[0131] The properties of the composite magnetic materials in Examples 8-14 are shown in Table 5.

[0132] Table 5

[0133]

[0134] As can be seen from the above, the composite magnetic material obtained by this invention has a mold flow ≥100cm, a flowability of 45s~50s, and a loose packing density of 2.2g / cm³. 3 ~2.4g / cm 3 The permeability μi (100KHz) is 55, the inductance decrease rate is ≤30% when the superimposed current is 18A, the insulation resistance is ≥2000MΩ, the withstand voltage is ≥150V / mm, and the power dissipation PCV (1MHz, 50mT) is <2000mW / cm. 3 It has excellent performance and broad application prospects.

[0135] The present invention has been illustrated with the above embodiments to illustrate its detailed features, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the selected technical features, additions of auxiliary technical features, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A composite magnetic material, characterized in that, The composite magnetic material comprises alloy powder and epoxy resin material; the epoxy resin material and the alloy powder are uniformly distributed, and the composite magnetic material is a composite powder. The alloy powder comprises a first nanocrystal with a first particle size, a second alloy with a second particle size, and a third alloy with a third particle size. The first particle size is larger than the second particle size, and the second particle size is larger than the third particle size; The alloy powder also includes an inorganic coating layer disposed on the surface of the first nanocrystal, the second alloy, and the third alloy.

2. The composite magnetic material according to claim 1, characterized in that, The particle size range of the first nanocrystal is 10~20μm; Preferably, the first nanocrystals account for 70-80% of the volume of the alloy powder; Preferably, the particle size range of the second alloy is 2~5μm; Preferably, the second alloy accounts for 5-15% of the volume of the alloy powder; Preferably, the particle size range of the third alloy is 0.5~1.5μm; Preferably, the third alloy accounts for 10-20% of the volume of the alloy powder.

3. The composite magnetic material according to claim 1 or 2, characterized in that, The first nanocrystal, the second alloy, and the third alloy each independently comprise an iron-based alloy; Preferably, the first nanocrystal, the second alloy, and the third alloy are each independently selected from any one or at least a combination of two of the following: FeSi alloys, FeSiB alloys, FeSiAl alloys, FeNi alloys, FeCuNi alloys, FeCo alloys, FeCrSi alloys, FeSiCo alloys, carbonyl iron, FeMn alloys, FeZn alloys, FeZr alloys, or FeNb alloys. Preferably, the first nanocrystal, the second alloy, and the third alloy are made of different materials.

4. The composite magnetic material according to any one of claims 1 to 3, characterized in that, The thickness of the inorganic coating layer is 10~40nm; Preferably, the inorganic coating layer is made of any one or a combination of at least two of Al2O3, SiO2, TiO2, ZrO2, ZnO, SnO2, MgO or CaO; Preferably, the inorganic coating layer comprises, in a radial direction outward, a first inorganic coating layer, a second inorganic coating layer, and a third inorganic coating layer; Preferably, the first inorganic coating layer, the second inorganic coating layer, and the third inorganic coating layer are made of different materials; Preferably, the first inorganic coating layer is Al2O3, the second inorganic coating layer is SiO2, and the third inorganic coating layer is TiO2.

5. The composite magnetic material according to any one of claims 1 to 4, characterized in that, The epoxy resin material in the composite magnetic material accounts for 2-4% of the mass. Preferably, the softening point of the epoxy resin material is ≤110℃; Preferably, the raw materials for preparing the epoxy resin material include epoxy resin, phenolic resin, curing accelerator, wax, and aluminate coupling agent.

6. The composite magnetic material according to any one of claims 1 to 5, characterized in that, The particle size range of the composite magnetic material is 20~30μm; Preferably, the fluidity of the composite magnetic material is 45-50 s; Preferably, the loose packing density of the composite magnetic material is 2.2~2.4 g / cm³. 3 ; Preferably, the magnetic permeability μi of the composite magnetic material at 100 kHz is ≥ 55; Preferably, the composite magnetic material comprises the following components by weight percentage: Fe: 70~75%, Ni: 9.5~12%, C: 1.5~7%, Si: 4~5.5%, Cr: 2.5~4.5%, Cu: 0.3~1.5%, P: 0.3~1.5%, Al: 0.3~1.5%, Ti: 0.2~0.8%, with the remainder being O.

7. A method for preparing the composite magnetic material according to any one of claims 1 to 6, characterized in that, The preparation method includes: (1) Mix the first nanocrystals with the first particle size, the second alloy with the second particle size, and the third alloy with the third particle size to obtain graded powder; (2) The graded powder is acidified with chromic acid or phosphoric acid, and then atomic layer deposition is performed to coat the surface of the first nanocrystal, the second alloy and the third alloy with an inorganic coating layer to obtain the first coated graded powder; (3) The raw materials, solvent and first coated grade powder of epoxy resin material are mixed to obtain slurry, and the slurry is spray granulated to obtain the composite magnetic material.

8. The preparation method according to claim 7, characterized in that, In step (2), the mass ratio of phosphoric acid or chromic acid to graded powder in the acidification treatment is 0.05~0.3wt%.

9. The preparation method according to claim 7 or 8, characterized in that, The solvent mentioned in step (3) includes any one or a combination of at least two of anhydrous ethanol, acetone, toluene, xylene or butyl acetate; Preferably, the mixing in step (3) includes: first mixing the raw materials and solvent of the epoxy resin material, and then adding the first coated grade powder; Preferably, the solid content of the slurry is 75-85 wt%; Preferably, the inlet air temperature for the spray granulation is 140~160℃; Preferably, the outlet air temperature of the spray granulation is 70~90℃; Preferably, the rotation speed of the spray granulation is 7000~9000 rpm.

10. A magnetic device, characterized in that, The magnetic device includes the composite magnetic material as described in any one of claims 1 to 6.

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