Metallic soft magnetic composite material, method for producing the same, and magnetic device

Abstract

The application provides a metal soft magnetic composite material, a preparation method thereof and a magnetic device. The metal soft magnetic composite material comprises: a nanocrystalline alloy powder, a first insulating coating layer and a second insulating coating layer, the first insulating coating layer is coated on the surface of the nanocrystalline alloy powder, and the second insulating coating layer is coated on the surface of the first insulating coating layer; the nanocrystalline alloy powder has a general formula of Fe (100‑a‑b‑c‑d‑e‑f‑g) Co a Si b B c Cu d Nb e P f Y g , wherein 10<=a<=30, 4<=b<=14, 5<=c<=12, 0.5<=d<=1.6, 0<=e<=2.5, 1<=f<=5, 18<=(b+c+f)<=30, and 1<=g<=5; the second insulating coating layer comprises magnetic amorphous nanoparticles. The metal soft magnetic composite material of the application has low power consumption, high magnetic permeability, good longitudinal voltage resistance and excellent salt mist resistance when used at high frequencies (such as 1 MHz).

Description

Technical Field

[0001] This invention relates to the field of soft magnetic materials technology, and in particular to a metal soft magnetic composite material for high-frequency magnetic devices and its preparation method. Background Technology

[0002] With the rapid development of third-generation semiconductors (SiC, GaN, ZnO, etc.), 5G / 6G communications, and new energy technologies, the electronics and power industry is rapidly moving towards higher frequencies, miniaturization, and higher currents. This places higher demands on the core loss, permeability stability, and DC bias resistance of soft magnetic materials under MHz high-frequency operating conditions. Iron-based nanocrystalline soft magnetic alloys have become a research hotspot in the field of magnetic powder cores due to their combination of high saturation magnetic induction, low coercivity, and tunable high-frequency characteristics.

[0003] Traditionally, iron-based nanocrystalline soft magnetic alloy powders are mostly obtained by crushing strips prepared by rapid quenching. However, powders prepared by this method tend to retain sharp edges, increasing the difficulty of subsequent insulation coating processes and making it difficult to achieve uniform insulation layer coverage, thus limiting further optimization of magnetic powder core losses. Although atomization methods (including gas atomization and water atomization) can directly prepare spherical or near-spherical powders, improving powder flowability and facilitating coating, their cooling rate is usually lower than that of rapid quenching, making it difficult to prepare amorphous nanocrystalline powders with high iron content.

[0004] Patent CN111910054A discloses a heat treatment method for high-performance iron-based amorphous nanocrystalline ribbons, but its application is limited to ribbons and is difficult to widely use in the field of metal magnetic powder cores. Patent CN119724805A discloses a soft magnetic composite material and its preparation method, which improves performance through composition optimization, rapid heat treatment, and organic-inorganic coating, but the non-magnetic substances used in its coating layer significantly dilute the magnetic properties of the composite material.

[0005] Therefore, there is an urgent need in this field for a new soft magnetic composite material that can provide excellent intrinsic magnetic properties through optimized alloy composition and microstructure, reduce high-frequency eddy current losses through effective insulation coating, and avoid significant degradation of magnetic properties due to the introduction of an insulating layer.

[0006] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention provides a metal soft magnetic composite material, its preparation method, and a magnetic device. While possessing low loss and high resistivity / voltage withstand capability, it can significantly reduce or avoid the decrease in magnetic performance (magnetic dilution effect) caused by the introduction of the insulating coating layer, thereby achieving synergistic optimization of low power consumption, high magnetic permeability, good insulation, and environmental resistance.

[0008] The present invention adopts the following technical solution: In a first aspect, a soft magnetic composite material is provided, comprising: nanocrystalline alloy powder, a first insulating coating layer, and a second insulating coating layer, wherein the first insulating coating layer coats the surface of the nanocrystalline alloy powder, and the second insulating coating layer coats the surface of the first insulating coating layer; the nanocrystalline alloy powder has the general formula Fe. (100-a-b-c-d-e-f-g) Co a Si b B c Cu d Nb e P f Y g , where 10≤a≤30, 4≤b≤14, 5≤c≤12, 0.5≤d≤1.6, 0≤e≤2.5, 1≤f≤5, 18≤(b+c+f)≤30, 1≤g≤5; the second insulating coating layer includes magnetic amorphous nanoparticles.

[0009] In a second aspect, a method for preparing the metal soft magnetic composite material described in the first aspect is provided, comprising the following steps: S1. Rapid heat treatment of amorphous alloy powder yields nanocrystalline alloy powder; the general formula of the amorphous alloy powder is the same as that of the nanocrystalline alloy powder, which is Fe. (100-a-b-c-d-e-f-g) Co a Si b B c Cu d Nb e P f Y g , where 10≤a≤30, 4≤b≤14, 5≤c≤12, 0.5≤d≤1.6, 0≤e≤2.5, 1≤f≤5, 18≤(b+c+f)≤30, 1≤g≤5; S2. The nanocrystalline alloy powder is subjected to a first insulating coating treatment to form a first insulating coating layer on its surface, thereby obtaining a first coated powder; S3. Perform a second insulating coating treatment on the first coating powder to form a second insulating coating layer on its surface, thereby obtaining the metal soft magnetic composite material.

[0010] Thirdly, a magnetic device is provided, comprising the metal soft magnetic composite material described in the first aspect.

[0011] The beneficial effects of this invention include: The metal soft magnetic composite material provided by this invention achieves excellent comprehensive performance through specific composition design and a double-layer insulating coating structure. First, through optimized design of the Fe-Co-Si-B-Cu-Nb-PY multi-element alloy system, combined with rapid heat treatment, a nanocrystalline structure with fine grain size (e.g., 12-25 nm) and uniform distribution is obtained. This microstructure helps reduce coercivity and hysteresis loss. Second, the first insulating coating layer (e.g., a phosphating layer) provides good basic insulation performance and improves powder resistivity. Most importantly, magnetic amorphous nanoparticles are introduced into the second insulating coating layer. These particles, while providing insulation, partially compensate for the decrease in magnetic flux density caused by the introduction of the insulating layer, mitigating the magnetic dilution effect and thus maintaining high permeability while reducing eddy current loss. The synergistic effect of these technical features enables the metal soft magnetic composite material of this invention to exhibit low power consumption, high permeability, good longitudinal withstand voltage, and excellent salt spray resistance in high-frequency applications (e.g., 1 MHz). Attached Figure Description

[0012] Figure 1 This is a flowchart illustrating the preparation process of the magnetic ring sample in Embodiment 1 of the present invention.

[0013] Figure 2 This is a schematic diagram comparing the salt spray resistance of the magnetic ring samples in Example 1 and Comparative Example 5 of the present invention. Detailed Implementation

[0014] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0015] This invention provides a soft magnetic metal composite material comprising: nanocrystalline alloy powder, a first insulating coating layer, and a second insulating coating layer. The first insulating coating layer covers the surface of the nanocrystalline alloy powder, and the second insulating coating layer covers the surface of the first insulating coating layer. The nanocrystalline alloy powder has the general formula Fe. (100-a-b-c-d-e-f-g) Co a Si b B c Cu d Nb e P f Y g, where 10≤a≤30, 4≤b≤14, 5≤c≤12, 0.5≤d≤1.6, 0≤e≤2.5, 1≤f≤5, 18≤(b+c+f)≤30, 1≤g≤5; the second insulating coating layer includes magnetic amorphous nanoparticles.

[0016] In some embodiments, the particle size D50 of the nanocrystalline alloy powder is 10~30μm, preferably 15~20μm; the average grain size of the nanocrystalline alloy powder is 12~25nm.

[0017] The electromagnetic properties of the material were optimized by controlling the particle size distribution and grain size of the nanocrystalline alloy powder.

[0018] In some embodiments, the thickness of the first insulating coating layer is 10-20 nm; the total thickness of the first insulating coating layer and the second insulating coating layer is 30-200 nm.

[0019] By controlling the thickness of the first insulating coating layer to be 10~20nm and the total thickness of the two coating layers to be 30~200nm, it is possible to ensure sufficient insulation while avoiding excessive damage to magnetic properties caused by excessively thick coating layers, thus achieving a better balance between insulation performance and magnetic properties.

[0020] In some embodiments, the first insulating coating layer is a phosphating layer. Using a phosphating layer as the first insulating coating layer provides strong adhesion and good density to the nanocrystalline alloy powder matrix, effectively serving as a basic insulating layer.

[0021] In some embodiments, the second insulating coating layer further includes silicone resin, and the surface of the magnetic amorphous nanoparticles is also coated with SiO2, with the SiO2-coated magnetic amorphous nanoparticles dispersed in the silicone resin.

[0022] The second insulating coating layer also contains silicone resin, and the magnetic particles are coated with SiO2, allowing the magnetic amorphous nanoparticles to be well dispersed and fixed in the silicone resin matrix. While the SiO2 shell provides insulation, the magnetic amorphous nanoparticles (such as FeCoB@SiO2) also reduce the magnetic resistance of the magnetic circuit and mitigate the magnetic dilution effect through their magnetic core. This second insulating coating layer, possessing insulation, mechanical strength, and partial magnetic functionality, achieves a balance between high-frequency low loss and high magnetic permeability in the composite material. The silicone resin includes commercially available methyl silicone resins, phenyl silicone resins, or methylphenyl silicone resins, such as Shin-Etsu Chemical's KR112, KR255, and KR311.

[0023] In some embodiments, magnetic amorphous nanoparticles coated with SiO2, at a defined particle size, are advantageous for forming a more uniform and dense coating layer.

[0024] In some embodiments, the magnetic amorphous nanoparticles are FeCoB particles coated with a SiO2 layer; the atomic content of each element in FeCoB is: Fe: 35~80 at.%, Co: 10~60 at.%, and B: 5~25 at.%; preferably, the atomic content of each element in FeCoB is: Fe: 45~70 at.%, Co: 15~45 at.%, and B: 8~15 at.%. Preferably, the particle size of FeCoB particles is 20~100 nm, more preferably 20~30 nm.

[0025] By limiting the magnetic amorphous nanoparticles to FeCoB particles and optimizing their elemental atomic content and particle size, we can ensure that they exert an effective magnetic dilution effect.

[0026] The present invention also provides a method for preparing the aforementioned soft magnetic metal composite material, comprising the following steps: S1, rapidly heat-treating amorphous alloy powder to obtain nanocrystalline alloy powder; wherein the general formula of the amorphous alloy powder is the same as that of the nanocrystalline alloy powder, being Fe (100-a-b-c-d-e-f-g) Co a Si b B c Cu d Nb e P f Y g S1, where 10≤a≤30, 4≤b≤14, 5≤c≤12, 0.5≤d≤1.6, 0≤e≤2.5, 1≤f≤5, 18≤(b+c+f)≤30, 1≤g≤5; S2, the nanocrystalline alloy powder is subjected to a first insulating coating treatment to form a first insulating coating layer on its surface, thereby obtaining a first coated powder; S3, the first coated powder is subjected to a second insulating coating treatment to form a second insulating coating layer on its surface, thereby obtaining the metal soft magnetic composite material.

[0027] The preparation method provided by this invention changes the microstructure of amorphous alloy powder while keeping the composition unchanged through a rapid heat treatment process, which can efficiently obtain nanocrystalline alloy powder with fine and uniform grains, laying the foundation for excellent magnetic properties; the double-layer insulation structure constructed by stepwise first and second insulation coating treatments can further regulate the comprehensive electromagnetic properties of the metal soft magnetic composite material.

[0028] In some embodiments, amorphous alloy powder with a particle size D50 of 10-30 μm is used. The powder is heated to 460-620°C at a heating rate of 200-250°C / min, held for 1-15 minutes, and then cooled to 200-400°C and held for at least 1 hour (preferably 1-2 hours) to obtain nanocrystalline alloy powder with an average grain size of 12-25 nm. Nanocrystals are formed through rapid heating heat treatment, and then the internal stress of the powder is removed by cooling, ultimately yielding nanocrystalline alloy powder.

[0029] In some embodiments, the first insulating coating layer in step S2 is a phosphating layer, and the first insulating coating process includes: phosphating the nanocrystalline alloy powder obtained in step S1 in a phosphating solution at 25~120°C to coat the surface of the nanocrystalline alloy powder with a phosphating layer of 10~20 nm thickness; wherein, in the phosphating solution, the solvent is at least one of water, ethanol, and acetone, and the solute is at least one of phosphoric acid and zinc dihydrogen phosphate; the mass ratio of the nanocrystalline alloy powder to the solute in the phosphating solution is 100:(0.05~1).

[0030] In some embodiments, in step S3, the second insulating coating layer comprises silicone resin and SiO2-coated magnetic amorphous nanoparticles dispersed in the silicone resin, wherein the SiO2-coated magnetic amorphous nanoparticles are represented as FeCoB@SiO2; the second insulating coating process comprises: S31, mixing FeCoB@SiO2 nanoparticles and silicone resin uniformly in a solvent to obtain a mixed solution; preferably, the solvent is at least one of acetone, ethanol, toluene, and xylene; S32, mixing the first coating powder with the mixed solution uniformly and drying (e.g., drying at 100~150°C after removing the solvent) to obtain the metal soft magnetic composite material; wherein, the mass ratio of FeCoB@SiO2 nanoparticles to the first coating powder is (0.5~3):100, the mass ratio of silicone resin to the first coating powder is (1~3):100, and the mass ratio of solvent to the first coating powder is (8~35):100.

[0031] In some embodiments, the preparation of the FeCoB@SiO2 nanopowder includes the following steps: (1) dissolving cobalt salt (e.g., CoCl2·6H2O) and iron salt (e.g., FeCl2·4H2O) in a mixed solvent of water and ethanol, adding NaBH4 aqueous solution dropwise under the protection of an inert gas (e.g., nitrogen) (e.g., the dropwise addition rate of NaBH4 aqueous solution is 1 mL / min to 30 mL / min), adjusting the pH value to 9-12 (e.g., pH adjustment using NaOH aqueous solution), and stirring the reaction (e.g., stirring continuously at room temperature) to generate FeCoB nanopowder; wherein, the mass ratio of iron salt to cobalt salt is (0.7~9.6):1; the mass ratio of NaBH4 in the NaBH4 aqueous solution is 10 ... The mass ratio of FeCoB nanopowder to the total mass of iron salt and cobalt salt is (0.09~0.4):1; (2) FeCoB nanopowder, tetraethyl orthosilicate (TEOS) and a mixed solvent of water and ethanol are mixed evenly, and ammonia water is added dropwise (e.g., the ammonia water is added at a rate of 0.5~5 mL / min) and stirred (e.g., stirred continuously at room temperature to 60°C). After washing and drying the product, FeCoB@SiO2 nanopowder is obtained, with a particle size of 20~100 nm, preferably 20~30 nm; wherein, the mass ratio of tetraethyl orthosilicate to FeCoB nanopowder is (0.3~3):100, and the mass ratio of ammonia water to tetraethyl orthosilicate is (0.5~2):1.

[0032] By optimizing the parameters in the rapid heat treatment, phosphating treatment, and FeCoB@SiO2 nanopowder preparation process, high-performance materials can be prepared stably and reproducibly.

[0033] This invention also provides a magnetic device comprising the aforementioned soft magnetic metal composite material. The magnetic device incorporating the soft magnetic metal composite material of this invention possesses the advantages of high frequency, low loss, and high permeability. The magnetic device includes high-frequency transformers, inductors, chokes, etc.

[0034] The preparation process of the magnet for magnetic devices using the metal soft magnetic composite material obtained by this invention includes: (1) Granulation: The metal soft magnetic composite material, resin and organic solvent are mixed evenly, dried and passed through a 100-250 mesh sieve to obtain granulated powder; wherein, the mass ratio of the metal soft magnetic composite material to the resin is 100:(0-3), and the mass ratio of the metal soft magnetic composite material to the organic solvent is 100:(6-30); the resin is at least one of epoxy resin and phenolic resin; the organic solvent is at least one of acetone, ethanol, toluene and xylene.

[0035] (2) Pressing and molding: The above granulated powder is pressed into a magnet blank using a press.

[0036] (3) Heat treatment: The magnet blank is heat-treated in an atmosphere to obtain a magnet; wherein the atmosphere is one of air, nitrogen, argon, or nitrogen-hydrogen mixture; the heat treatment temperature is 50~300℃ and the holding time is 0~24h.

[0037] The following describes specific embodiments of the present invention. Unless otherwise specified, all chemical reagents in the following embodiments are of analytical grade (AR).

[0038] Example 1 Example 1 combines an optimized Fe-Co-Si-B-Cu-Nb-PY nanocrystalline alloy composition (Co, P, and rare earth Y elements can improve the amorphous forming ability of the material) with a rapid thermal treatment process (controlling the microstructure of the material to form an amorphous nanocrystalline alloy with an average grain size of 12~25nm) to obtain an ultrafine nanocrystalline structure, providing low intrinsic loss. Simultaneously, a double-layer insulating coating strategy is adopted: the inner layer is a dense phosphating layer, providing basic insulation and corrosion resistance; the outer layer is a silicone resin layer containing SiO2-coated magnetic amorphous FeCoB nanoparticles. This composite layer provides additional high resistance while the magnetic particles within mitigate the magnetic dilution effect of traditional non-magnetic insulating layers, thus achieving a balance between low loss and high permeability. Specifically, as... Figure 1 As shown, the preparation method of the metal soft magnetic composite material in this embodiment includes the following steps: 1. Preparation of nanocrystalline alloy powder: Amorphous alloy powder (Fe) prepared by water-vapor combined atomization method is used... 60.1 Co 15 Si 12.5 B5Cu 0.9 Nb1P3Y 2.5 After sieving, select amorphous alloy powder with a particle size D50 of 10~30μm and perform the following rapid heat treatment: heat up to 530℃ at a heating rate of 250℃ / min and hold for 5min, then rapidly cool down and hold at 350℃ for 1h to obtain nanocrystalline alloy powder.

[0039] 2. First Insulation Coating Treatment: Weigh 0.05g of phosphoric acid and 0.05g of zinc dihydrogen phosphate, add them to 20g of anhydrous ethanol, and mix thoroughly to obtain a phosphating solution. Take 100g of the nanocrystalline alloy powder obtained in step 1 and add it to the phosphating solution. Stir at 60℃ until the solvent is completely evaporated to form a first insulation coating layer on the surface of the nanocrystalline alloy powder, thus obtaining the first coated powder.

[0040] 3. Second insulation coating treatment: Weigh 1.5g FeCoB@SiO2 nanopowder, 1.5g silicone resin (using KR 311 silicone resin produced by Shin-Etsu Chemical Co., Ltd.) and 20g acetone, and ultrasonically stir to mix evenly. Then add 100g of the first coating powder obtained in step 2 to the mixed solution, stir at 60°C until the solvent is completely evaporated, and bake at 150°C under vacuum for 2 hours to obtain a metal soft magnetic composite material.

[0041] The preparation process of FeCoB@SiO2 nanopowder is as follows: 3.4 g CoCl2·6H2O and 6.2 g FeCl2·4H2O are dissolved in a mixed solvent of 50 g ethanol and water in a volume ratio of 1:1. The pH value is adjusted to about 10 with NaOH solution. N2 is introduced for at least 30 minutes to remove dissolved oxygen in the system. N2 is continuously introduced to maintain positive pressure throughout the reaction process. Then, 55 mL of 0.8 mol / L NaBH4 aqueous solution (i.e., the mass of NaBH4 in the NaBH4 aqueous solution is 1.66 g) is added dropwise at a rate of 17 mL / min. The reaction temperature is controlled below 30℃. After separation and washing with ethanol, the product powder obtained from the reaction is dried under vacuum at 60℃ for 6 h to obtain FeCoB powder. Take 0.7g TEOS and 30g 50% ethanol solution and mix them evenly. Then add 100g FeCoB powder to the mixed solution and stir continuously to disperse. Add 1g ammonia water dropwise at a rate of 1ml / min and stir continuously for 3h. After separation and washing with ethanol, the powder is dried under vacuum at 60℃ for 8h to obtain FeCoB@SiO2 nanopowder.

[0042] The metal soft magnetic composite material prepared in this embodiment was used to prepare magnetic ring samples for performance testing. The preparation process of the magnetic ring samples is as follows: (1) Granulation: Take 1g of epoxy resin and 20g of acetone, mix them evenly, add 100g of the metal soft magnetic composite material prepared above, mix thoroughly, air dry, and pass through a 100~250 mesh sieve to obtain granulated powder.

[0043] (2) Press molding: The above granulated powder is pressed into a magnetic ring blank with an outer diameter of 10 mm, an inner diameter of 5 mm and a height of 2 mm using a press at 1500 MPa.

[0044] (3) Heat treatment: The magnetic ring blank is kept at 150°C in air for 2 hours to obtain the magnetic ring sample.

[0045] Example 2 The difference between this embodiment and Embodiment 1 is that the heating rate during rapid heat treatment in step 1 is 200℃ / min, while the rest is the same as in Embodiment 1.

[0046] Example 3 The difference between this embodiment and Embodiment 1 is that the amount of FeCoB@SiO2 nanopowder in step 3 is 3g, while the rest is the same as in Embodiment 1.

[0047] Example 4 The difference between this embodiment and Embodiment 1 is that the chemical formula of the amorphous alloy powder in step 1 is Fe. 50 Co 23 Si 12 B 7.5 Cu1Nb 0.5 P3Y3, the rest is the same as in Example 1.

[0048] Comparative Example 1 The difference between this comparative example and Example 1 is that the amorphous alloy powder is not subjected to rapid heat treatment, i.e., it does not form nanocrystals. Otherwise, it is the same as Example 1, i.e., the amorphous alloy powder is directly subjected to the same steps 2 and 3 as in Example 1 to obtain the metal soft magnetic composite material.

[0049] Comparative Example 2 The difference between this comparative example and Example 1 is that in step 1, the amorphous alloy powder is heat-treated at a relatively slow heating rate of 5°C / min, while the rest is the same as in Example 1.

[0050] Comparative Example 3 The difference between this comparative example and Example 1 is that the temperature is raised to 660°C during the rapid heat treatment in step 1 (530°C in Example 1), otherwise it is the same as Example 1.

[0051] Comparative Example 4 The difference between this comparative example and Example 1 is that FeCoB@SiO2 nanopowder is not added in step 3, and the second insulating coating treatment is performed directly with silicone resin.

[0052] Comparative Example 5 The difference between this comparative example and Example 1 is that the nanocrystalline alloy powder was not subjected to insulating coating treatment. In this comparative example, the nanocrystalline alloy powder was prepared into a magnetic ring sample using the same method as in Example 1.

[0053] Performance tests were performed on the metal soft magnetic composite materials and magnetic ring samples of each embodiment and comparative example. The average grain size of the nanocrystals was measured by XRD or TEM. Under no external magnetic field, the inductance of the magnetic ring sample at 1 MHz was measured using an LCR meter (inductance (L), capacitance (C), resistance (R) meter), and the permeability was calculated from the inductance. The power dissipation of the magnetic ring sample was measured using a BH analyzer (model SY-8218) at 25℃, 50mT, and 1 MHz. The breakdown voltage between the two flat surfaces of the magnetic ring sample was measured using a withstand voltage tester; this is the longitudinal withstand voltage value.

[0054] The salt spray resistance test conditions are as follows: at any point in the workspace, the horizontal collection area is 80 cm². 2 The collector collects 1.0 mL to 2.0 mL per hour; the salt solution is a (5±1) wt% sodium chloride solution, and its pH value should be 6.5 to 7.2 at a temperature of (35±2)℃. The test temperature is 35±2℃, and the test time is 48 hours. Photos are taken and recorded at 0, 12, 24, 36, 48, and 60 hours after the test. Salt spray resistance refers to the time during which performance (such as no visible red rust) is maintained. For example, a salt spray resistance of 60 hours means that no red rust appears after 60 hours.

[0055] The test results are shown in the table below: Example 1 13 23 1125 60 4105 Example 2 15 23 1050 60 4394 Example 3 13 24 1090 60 4381 Example 4 16 22 1202 60 4467 Comparative Example 1 amorphous 15 39 ＜12 9005 Comparative Example 2 29 22 906 60 6790 Comparative Example 3 / 20 998 60 10861 Comparative Example 4 14 20 582 36 4651 The " / " in Comparative Example 3 in the table indicates that due to the excessively high heat treatment temperature, a non-magnetic phase was generated, and the average grain size of the nanocrystals could not be calculated.

[0056] As shown in the table above, the power consumption of nanocrystalline materials is much lower than that of amorphous materials of the same composition. Overall, materials with smaller average grain sizes have lower power consumption. Adding FeCoB can improve the permeability of soft magnetic composite materials. After insulating coating treatment, the longitudinal withstand voltage of the material increases, the power consumption decreases, and the salt spray resistance is improved. Comparative Example 1, because the amorphous alloy did not undergo rapid heat treatment, did not precipitate nanocrystalline materials, resulting in higher power consumption and lower permeability. Comparative Example 2, due to the slow heating rate, resulted in grain growth and increased power consumption. Comparative Example 3, with its high holding temperature, may precipitate borides that deteriorate magnetic properties. Comparative Example 4, without the addition of magnetic FeCoB nanopowder, had coatings made entirely of non-magnetic materials, resulting in a more pronounced magnetic dilution effect.

[0057] like Figure 2 As shown, this is a comparison of the salt spray resistance of the magnetic ring samples in Example 1 and Comparative Example 5. The magnetic ring sample in Comparative Example 5 was not coated. Figure 2 (See the image above) After 24 hours of salt spray treatment, the surface of the sample showed severe rusting and the sample became ineffective. Example 1 showed a magnetic ring sample that underwent coating treatment (…). Figure 2 (See the image below) After 24 hours of salt spray treatment, the surface did not rust, indicating that it has better reliability.

[0058] In the above embodiments, on the one hand, the composition of the nanocrystalline alloy powder is designed, and its microstructure is controlled by heat treatment to develop an alloy material with excellent intrinsic properties; on the other hand, the nanocrystalline alloy powder is surface coated to improve the powder resistivity, increase interparticle insulation, and reduce interparticle eddy currents, thereby achieving the purpose of low power consumption. The magnetic material contained in the coating layer can reduce the magnetic performance loss of the soft magnetic composite material. Specifically, (1) in terms of composition design and microstructure control, the general formula of the nanocrystalline alloy powder is Fe (100-a-b-c-d-e-f-g) Co a Si b Bc Cu d Nb e P f Y g In this alloy, Fe, as the matrix element, determines the saturation magnetic induction intensity; Co adjusts the saturation magnetostriction coefficient λs and enhances exchange coupling, thereby improving the overall magnetic properties of the alloy; Si can improve the amorphous formation capability and increase resistivity, thus suppressing eddy current losses. Y (0.227 nm), Nb (0.148 nm), and Fe (0.127 nm) have relatively large atomic radii, while Si (0.112 nm), P (0.110 nm), and B (0.095 nm) have relatively small atomic radii. This large difference in atomic radii leads to denser disordered packing, increased melt viscosity, reduced crystallization kinetics, and thus improved amorphous formation capability. Y can significantly improve the amorphous formation capability of the alloy, increasing the temperature difference ∆Tx between α-Fe(Si) and Fe-B phase precipitation, expanding the heat treatment temperature range, and facilitating grain control during subsequent heat treatment. Furthermore, Y can promote nanocrystal formation; therefore, the introduction of Y increases the amorphous formation capability and is beneficial for nanocrystal formation and grain refinement. P mainly exists in the residual amorphous matrix, making the grains more fine and uniformly dispersed in the matrix. (2) In terms of preparation process, rapid heat treatment allows the material to quickly obtain a large amount of energy through ultra-fast heating and short holding time, causing the atomic structure inside to rearrange, significantly inhibiting grain growth. Combined with the uniformly dispersed nucleation sites in the material, it eventually forms grains with smaller size, more concentrated particle size distribution, and more uniform dispersion. Nanocrystals are usually obtained by heat treatment to precipitate nanoscale grains on the basis of amorphous materials. For nanocrystalline materials, when the grain size is comparable to the magnetic domain wall thickness, the coercivity is very large due to the influence of magnetocrystalline anisotropy; when the grain size is smaller than the magnetic domain wall thickness, the smaller the grain, the lower the coercivity and the lower the power consumption. (3) In terms of insulation coating treatment, phosphate is generated by the reaction of nanocrystalline alloy powder and phosphating solution to uniformly cover the powder surface, thereby improving the powder resistivity. The FeCoB@SiO2 nanopowder and silicone resin mixture is coated on the powder surface to further improve the powder resistivity, so that the powder particles have good insulation performance, reduce the eddy current generated between particles at high frequency, and thus reduce the loss. In addition, the coating layer contains magnetic material FeCoB, which can reduce the dilution effect on the magnetic properties of the metal soft magnetic composite material.

[0059] It should be noted that when detecting the composition of the metal soft magnetic composite material, the particles can be cut open using focused ion beam (FIB) to obtain a cross-section, and then the morphology and thickness can be observed and measured using scanning electron microscopy (SEM) or transmission electron microscopy (TEM). Compositional analysis is then performed using energy dispersive spectroscopy (EDS). The composition of the FeCoB nanoparticles is ensured by the raw materials and processes used in their preparation. Due to the characteristics of boron (B), direct detection of it presents certain challenges, but the soft magnetic properties of the particles can serve as evidence of their amorphous boron-containing alloy structure.

[0060] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A soft magnetic metal composite material, characterized in that, include: The nanocrystalline alloy powder, the first insulating coating layer, and the second insulating coating layer are provided. The first insulating coating layer covers the surface of the nanocrystalline alloy powder, and the second insulating coating layer covers the surface of the first insulating coating layer. The general formula of the nanocrystalline alloy powder is Fe. (100-a-b-c-d-e-f-g) Co a Si b B c Cu d Nb e P f Y g , where 10≤a≤30, 4≤b≤14, 5≤c≤12, 0.5≤d≤1.6, 0≤e≤2.5, 1≤f≤5, 18≤(b+c+f)≤30, 1≤g≤5; The first insulating coating layer is a phosphating layer; the second insulating coating layer includes magnetic amorphous nanoparticles and silicone resin, wherein the surface of the magnetic amorphous nanoparticles is further coated with SiO2, and the SiO2-coated magnetic amorphous nanoparticles are dispersed in the silicone resin; the magnetic amorphous nanoparticles are FeCoB particles, and the atomic content of each element in FeCoB is: Fe: 35~80 at.%, Co: 10~60 at.%, and B: 5~25 at.%.

2. The soft magnetic metal composite material as described in claim 1, characterized in that, The particle size D50 of the nanocrystalline alloy powder is 10~30μm; the average grain size of the nanocrystalline alloy powder is 12~25nm.

3. The soft magnetic metal composite material as described in claim 1, characterized in that, The thickness of the first insulating coating layer is 10~20nm; the total thickness of the first insulating coating layer and the second insulating coating layer is 30~200nm.

4. The soft magnetic metal composite material as described in claim 1, characterized in that, The particle size D50 of the nanocrystalline alloy powder is 15~20μm.

5. The soft magnetic metal composite material as described in claim 1, characterized in that, The atomic content of each element in FeCoB is: Fe: 45~70 at.%, Co: 15~45 at.%, and B: 8~15 at.%.

6. A method for preparing a soft magnetic metal composite material according to any one of claims 1-5, characterized in that, The steps include the following: S1. Rapid heat treatment of amorphous alloy powder yields nanocrystalline alloy powder; the general formula of the amorphous alloy powder is the same as that of the nanocrystalline alloy powder, which is Fe. (100-a-b-c-d-e-f-g) Co a Si b B c Cu d Nb e P f Y g , where 10≤a≤30, 4≤b≤14, 5≤c≤12, 0.5≤d≤1.6, 0≤e≤2.5, 1≤f≤5, 18≤(b+c+f)≤30, 1≤g≤5; S2. The nanocrystalline alloy powder is subjected to a first insulating coating treatment to form a first insulating coating layer on its surface, thereby obtaining a first coated powder, wherein the first insulating coating layer is a phosphating layer. S3. Perform a second insulating coating treatment on the first coating powder to form a second insulating coating layer on its surface, thereby obtaining the metal soft magnetic composite material.

7. The preparation method according to claim 6, characterized in that: Step S1 includes: using amorphous alloy powder with a particle size D50 of 10~30μm, heating it to 460~620℃ at a heating rate of 200~250℃ / min, holding it at that temperature for 1min~15min, and then cooling it to 200~400℃ and holding it at that temperature for more than 1h to obtain nanocrystalline alloy powder, wherein the average grain size of the nanocrystalline alloy powder is 12~25nm.

8. The preparation method according to claim 6, characterized in that: In step S2, the first insulation coating process includes: The nanocrystalline alloy powder obtained in step S1 is subjected to phosphating treatment in a phosphating solution at 25~120℃ to coat the surface of the nanocrystalline alloy powder with a phosphating layer of 10~20nm thickness; wherein, in the phosphating solution, the solvent is at least one of water, ethanol, and acetone, and the solute is at least one of phosphoric acid and zinc dihydrogen phosphate; the mass ratio of nanocrystalline alloy powder to solute in the phosphating solution is 100:(0.05~1).

9. A magnetic device, characterized in that, Including the soft magnetic metal composite material according to any one of claims 1-5.

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