Amorphous magnetic core with high magnetic conductivity and low loss, preparation method and application

Abstract

The alloy component of the amorphous magnetic core is FeaSibBcPdCeCrfNig, subscripts represent the mass percent of the element in the components, a is larger than or equal to 80 and smaller than or equal to 90, b is larger than or equal to 0.1 and smaller than or equal to 12, c is larger than or equal to 0.1 and smaller than or equal to 6, d is larger than or equal to 0.2 and smaller than or equal to 10, e is larger than or equal to 0.1 and smaller than or equal to 1.0, f is larger than or equal to 0.5 and smaller than or equal to 6.0, g is larger than or equal to 0.5 and smaller than or equal to 10, and a + b + c + d + e + f + g is equal to 100. The magnetic conductivity of the amorphous magnetic core is larger than or equal to 60. The preparation method comprises the steps of ingredient smelting, atomization powder preparation and vacuum gradient annealing to obtain the amorphous magnetic core. Through the improved design of the alloy components and the processing technology, compared with a conventional technology, the magnetic conductivity is improved by more than 30%, the loss at low frequency is reduced by more than 10%, the loss at high frequency is also remarkably reduced, and the requirements of industrial use, high frequency and miniaturization of the amorphous magnetic core can be better met.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic materials, and in particular relates to an amorphous magnetic core with high magnetic permeability and low loss, a preparation method and an application thereof. Background Art

[0002] The magnetic core is made of soft magnetic material with low coercivity and high magnetic permeability. Adding a magnetic core to a magnetic component such as an inductor or transformer can increase the inductance of the coil. Common soft magnetic materials are iron-silicon alloy (silicon steel sheet), soft ferrite, amorphous alloy, etc.

[0003] Amorphous alloys are solid alloys formed by rapid cooling and solidification from a liquid state. Because atoms don't have time to arrange themselves and crystallize during rapid cooling and solidification, the resulting amorphous alloy has a long-range disordered structure, lacking the grains and grain boundaries of crystalline alloys. Amorphous alloys offer advantages such as high magnetic permeability, low loss at high frequencies, and high saturation flux density, leading to their increasing use in magnetic cores.

[0004] Amorphous magnetic powder cores are widely used in high-frequency power electronic equipment due to their high resistivity, low eddy current loss and good frequency stability. Traditional amorphous magnetic powder cores mostly use alloy systems such as FeSiB or FeSiBCr. For example, the invention patent application with publication number CN117497278A discloses a high magnetic permeability and low loss iron-based amorphous composite magnetic powder core and a preparation method. By adopting conventional FeSiBCCr and FeNi50 mixed powder and epoxy resin coating process, the prepared iron-based amorphous composite magnetic powder core is mainly composed of FeSiBCCr amorphous powder and FeNi powder. The particle size of FeSiBCCr amorphous powder is 10μm-20μm, and the particle size of FeNi powder is 1μm-5μm. The magnetic permeability of the magnetic powder core at a frequency of 100kHz is 45.3, and the total loss under 50mT, 500kHz conditions is 630mW / cm 3 , at 100mT, 50kHz, the loss Pcv = 203mW / cm 3 Although the magnetic permeability and saturation have been slightly improved, they are still not enough to meet the needs of industrialization, and the ultrafine iron-nickel powder used is expensive.

[0005] For example, the invention patent application with publication number CN117894540A discloses a high-permeability, low-power-consumption soft magnetic alloy material for sintered integrally molded inductors, as well as its preparation method and application. The soft magnetic alloy material is obtained by subjecting metal powder to multi-layer coating treatment, and then spray granulating, heat treating, pressing and sintering in sequence. The soft magnetic alloy material includes metal powder and an insulating layer coated on the metal powder; the metal powder includes the following components in weight percentage: Fe: 65%-80%, Ni: 10%-25%, Si: 3.5%-5.5%, Al: 3.5%-5.5%, B: 0.3%-1.5%, P: 0.1%-1.0%, Co: 0.05%-0.4%, C: 0.05%-0.5%, and the particle size of the metal powder is 4μm-45μm. Although the magnetic permeability has been improved, the matching of high magnetic permeability and low loss still has room for improvement, and it needs to be compounded with other alloy powders to obtain relatively good performance.

[0006] In view of the above-mentioned deficiencies in the existing technology, it is particularly important to develop amorphous magnetic core powders with high magnetic permeability and low loss by regulating the alloy composition and improving the preparation process to meet the key needs for amorphous magnetic cores in the current industrialization. Summary of the Invention

[0007] In view of the above-mentioned deficiencies in the prior art, the present invention provides an amorphous magnetic core with high magnetic permeability and low loss, a preparation method and an application thereof. The amorphous magnetic core has high magnetic permeability and low loss, meeting the current demand for amorphous magnetic cores in industrialization.

[0008] The present invention provides an amorphous magnetic core with high magnetic permeability and low loss, wherein the alloy composition of the amorphous magnetic core is Fe a Si b B c P d C e Cr f Ni g , a, b, c, d, e, f, g in the subscripts represent the mass percentage of the element in the composition, where 80≤a≤90, 0.1≤b≤12, 0.1≤c≤6, 0.2≤d≤10, 0.1≤e≤1.0, 0.5≤f≤6.0, 0.5≤g≤10, and a+b+c+d+e+f+g=100;

[0009] The magnetic permeability of the amorphous magnetic core is ≥60.

[0010] The functions of other elements of the amorphous magnetic core provided by the present invention are:

[0011] P: The addition of P improves the amorphous core's amorphous forming ability, enabling the production of a completely amorphous alloy during the amorphous alloy manufacturing process. This ensures a relatively uniform nanocrystalline phase after crystallization, thereby increasing the saturation magnetic induction and coercivity of the amorphous core material and improving the core's overall magnetic properties. When the P content is within an appropriate range, it, along with B and Si, reduces melt viscosity, enhances amorphous forming ability, and forms a passivation film on the surface, inhibiting oxidation. Therefore, the atomic percentage of P in the present invention is 0.2% to 10%.

[0012] Ni: The addition of Ni can adjust the anisotropy of the magnetocrystalline, increase the magnetic permeability (μ), and reduce the coercive force (Hc). In addition, Ni's thermal expansion coefficient complements that of Fe, reducing temperature drift. Therefore, the atomic percentage of Ni in the present invention is 0.5% to 10%.

[0013] Directly adding Ni and P elements into the amorphous powder composition can increase the formability of the amorphous powder, and achieve higher density molding without compounding with other alloy powders, thereby improving the magnetic permeability.

[0014] As the main magnetic element, Fe provides high saturation magnetization (Bs) and magnetic permeability, ensuring high energy storage and transmission efficiency of the magnetic core. The high content of 80%-90% ensures the dominance of magnetic properties. At the same time, it synergizes with other elements to inhibit crystallization and maintain the amorphous structure. Si, B and P work together to ensure the amorphous structure under rapid solidification, avoiding magnetic losses caused by grain boundaries; the synergistic effect of Si and Cr suppresses eddy currents; at the same time, Cr, C, P and Ni synergistically improve corrosion resistance and oxidation resistance, and synergistically adjust the expansion and magnetic temperature coefficients. By regulating the various alloy elements and their proportions, the magnetic permeability of the amorphous core is improved and the magnetic loss is reduced, ensuring working stability in a wide temperature range and expanding the application scenarios to harsh environments.

[0015] Preferably, the loss of the amorphous core at low frequency is less than 200 mW / cm 3 ; and / or the loss of the amorphous core at high frequency is less than 250mW / cm 3 .

[0016] The low frequency includes 50KHz and 100mT; the high frequency includes 1MHz and 20mT.

[0017] Preferably, the particle size of the amorphous magnetic core is 15 μm-40 μm.

[0018] The amorphous magnetic core within the above-mentioned particle size range shortens the movement path of the magnetic domain wall, reduces high-frequency eddy current loss, ensures the filling density of the amorphous magnetic core, and takes into account both the mechanical strength and high-frequency performance of the amorphous magnetic core.

[0019] On the other hand, the present invention also provides a method for preparing the amorphous magnetic core with high magnetic permeability and low loss, comprising the following steps:

[0020] (1) preparing ingredients and smelting according to the mass percentage of each component of the amorphous magnetic core to obtain an alloy ingot, and then preparing an amorphous powder by gas atomization;

[0021] (2) weighing an inorganic coating, dispersing the inorganic coating in an organic solvent to obtain a mixed solution, then adding a silane coupling agent and amorphous powder to the mixed solution, mixing and stirring, and drying to obtain a modified amorphous powder;

[0022] (3) dissolving the epoxy resin in an organic solvent to form an epoxy resin solution, mixing the epoxy resin solution with the modified amorphous powder, drying, and crushing to obtain the epoxy resin modified coated amorphous powder;

[0023] (4) The epoxy resin modified and coated amorphous powder is added into a mold and pressed, and an amorphous magnetic core is obtained by gradient annealing in a vacuum environment.

[0024] The present invention uses an aerosolization method to achieve rapid breakup and cooling of metal droplets, significantly improving magnetic properties and mechanical strength, reducing heat treatment defects, and forming a stable amorphous structure; combined with modified coating, it improves insulation properties and thermal conductivity and reduces losses; further, a gradient annealing process in a vacuum environment can fully release the stress inside the magnetic core, and the vacuum discharges the air in the air gap inside the magnetic powder core, making the magnetic core more compact and denser, thereby improving the magnetic permeability.

[0025] Preferably, the aerosolization is performed using an inert gas;

[0026] Further preferably, the inert gas is nitrogen or argon; and the pressure of the inert gas is 3 MPa to 10 MPa.

[0027] Preferably, the smelting temperature in step (2) is 1400°C-1600°C.

[0028] Preferably, the inorganic coating in step (2) is one or more of nano-alumina and nano-hexagonal boron nitride.

[0029] Conventional epoxy resin will thermally decompose when annealed at high temperature, destroying the insulating layer of the powder and deteriorating the magnetic properties. By introducing nano-alumina and nano-boron nitride to modify the epoxy resin, the resin's high-temperature resistance is improved, the structural temperature is maintained below 500°C, and the insulation properties and thermal conductivity are improved, thereby reducing losses.

[0030] More preferably, the weight of the inorganic coating is 0.1%-2% of the weight of the amorphous powder.

[0031] More preferably, the particle size of the nano-aluminum oxide is less than 100 nm, and the particle size of the nano-hexagonal boron nitride is less than 100 nm.

[0032] Using the above-mentioned particle size range for inorganic coating can effectively fill the nano-scale pores between magnetic powders, inhibit the energy dissipation during the movement of magnetic domain walls, and improve the effective magnetic permeability of the magnetic core; at the same time, nano-scale coating reduces the interface defects between the insulating layer and the magnetic powder, reduces dielectric loss, and significantly optimizes the comprehensive performance of the nano-magnetic core.

[0033] Further preferably, the mass ratio of the nano-alumina to the nano-hexagonal boron nitride is 3:1.

[0034] Preferably, the organic solvent in step (2) is anhydrous ethanol or acetone;

[0035] Further preferably, the mass ratio of the inorganic coating to the organic solvent in step (2) is 1:20-200.

[0036] Preferably, the dispersion time in step (2) is 0.5h-2h.

[0037] Preferably, the silane coupling agent described in step (2) is any one of KH550, KH560, and KH602.

[0038] The above-mentioned silane coupling agent contains -Si-O-, amino or epoxy functional groups, which form chemical bonds between the amorphous powder and the epoxy resin, which can significantly improve the interfacial bonding strength, reduce the porosity and defects of the coating layer, improve the insulation and mechanical integrity of the magnetic core, and also reduce the leakage current path and improve the resistivity of the magnetic core.

[0039] More preferably, the weight of the silane coupling agent is 0.1%-2% of the weight of the amorphous powder.

[0040] Preferably, the stirring time in step (2) is 1 h.

[0041] Preferably, the drying temperature in step (2) is 60° C.-100° C.; and the drying time is 0.5 h-2 h.

[0042] Preferably, the weight of the epoxy resin in step (3) is 1%-4% of the weight of the amorphous powder.

[0043] Further preferably, the mass ratio of the epoxy resin to the organic solvent is 1:20-200.

[0044] Preferably, the stirring time in step (3) is 0.5h-2h;

[0045] Preferably, the drying temperature in step (3) is 60° C.-100° C., and the drying time is 0.5 h-2 h.

[0046] Preferably, the pressure of the pressing in step (3) is 1500 MPa-2200 MPa, and the holding time of the pressing is 10 s-60 s.

[0047] Preferably, the gradient annealing in step (4) includes: the first stage annealing has a heating rate of 5°C / min-15°C / min and an annealing temperature of 200°C-300°C; the second stage annealing has a heating rate of 1°C / min-5°C / min and an annealing temperature of 400°C-500°C.

[0048] The first section of the annealing curve is a rapid heating stage, which allows the magnetic powder core to quickly pass through the easily oxidized zone. The second section is a slow heating stage, which allows the interior of the magnetic powder core to be evenly heated, reducing the temperature gradient and avoiding uneven heating due to an excessively rapid heating rate, internal stress concentration, and reduced magnetic permeability. At the same time, it also avoids the impact of an excessively slow heating rate on production efficiency and increased costs.

[0049] More preferably, after reaching the annealing temperature of the second stage, the temperature is maintained for 30 minutes to 120 minutes.

[0050] The above-mentioned holding time can fully release the internal compression stress of the magnetic powder core and reduce the hysteresis loss.

[0051] The present invention also provides application of the amorphous magnetic core with high magnetic permeability and low loss in high-frequency inductors or transformers.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) The present invention improves the design of the amorphous alloy composition and introduces P and Ni elements to increase the moldability of the amorphous powder. It can achieve higher density molding without compounding with other alloy powders, thereby improving the magnetic permeability.

[0054] (2) Based on the improved design of the amorphous alloy composition, the modified epoxy resin coating and vacuum gradient annealing process are further combined to form a stable amorphous structure, significantly improving the magnetic properties and mechanical strength, reducing the defects of heat treatment and reducing losses. The magnetic permeability is increased by more than 30% compared with the conventional process, the loss at low frequency is reduced by more than 10%, and the loss at high frequency is also significantly reduced.

[0055] (3) The high permeability and low loss amorphous magnetic core provided by the present invention can better meet the requirements of industrial use, high frequency and miniaturization of amorphous magnetic powder cores, and can be widely used in the manufacture of electromagnetic components such as high-frequency inductors and transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is the X-ray diffraction pattern (XRD) of the amorphous powder prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0057] In order to more clearly illustrate the purpose, technical solutions and advantages of the present invention, the following will be described in detail with reference to the embodiments. Please note that these embodiments are only used to explain the content of the present invention and are not intended to limit the scope of the present invention. Modifications or equivalent substitutions made by those skilled in the art based on the understanding of the technical solutions of the present invention are all within the scope of protection of the present invention.

[0058] The raw materials were purchased from the market.

[0059] Example 1

[0060] Example 1 of the present invention provides an alloy composition of Fe 82 Si 2.8 B 1.7 P6C 0.5 Cr 2.1 Ni 4.9 The preparation method of the amorphous magnetic core comprises the following specific steps:

[0061] 1) Weigh the ingredients according to the required elements and proportions, and smelt the iron block, silicon block, nickel plate, carbon block, ferrochrome alloy, ferroboron alloy, ferrophosphorus alloy and slag remover at 1500° C. to obtain an alloy ingot.

[0062] 2) The alloy ingot was atomized in a high-pressure nitrogen environment of 5 MPa to obtain an amorphous powder with a particle size of 21 μm.

[0063] 3) Modifying and coating the amorphous powder with epoxy resin, comprising the following steps:

[0064] ① Weigh 100g of the above amorphous powder for later use.

[0065] ② Weigh the inorganic coating, the weight of the inorganic coating is 0.5% of the weight of the amorphous powder, the inorganic coating is a mixture of nano-alumina (particle size below 100 nm) and nano-hexagonal boron nitride (particle size below 100 nm), the mixing ratio is 3:1, add it to 20 g of anhydrous ethanol, and disperse it in ultrasound for 0.5 h to obtain a mixed solution.

[0066] ③ Add KH560 silane coupling agent to the mixed solution M, the weight of KH560 silane coupling agent is 0.5% of the weight of the amorphous powder, then add 100g of the amorphous powder weighed in step ① and mix and stir for 1h, then put it into a drying oven at 80℃ and dry it for 0.5h-2h to obtain modified amorphous powder for use.

[0067] ④ Weigh epoxy resin E51 and completely dissolve it in 30g acetone. The weight of epoxy resin E51 is 2% of the weight of the amorphous powder. Then add the modified amorphous powder in step ③ and mix thoroughly for 0.5h. Then dry it at 80℃.

[0068] ⑤ Crush the dried powder and pass it through a 40-mesh sieve to obtain epoxy resin-modified coated amorphous powder.

[0069] 4) Add the epoxy resin modified coated amorphous powder into a 20.3mm*12.7mm annular mold and press at 1960MPa to obtain a pre-treated amorphous core; then put the pre-treated amorphous core into a vacuum annealing furnace for annealing at a vacuum degree of 5*10 -3 The annealing temperature curve is as follows: heating to 250°C at 10°C / min, heating to 470°C at 2°C / min, keeping the temperature for 60min and then cooling in the furnace to obtain an amorphous magnetic core.

[0070] The structure of the amorphous magnetic core obtained in this embodiment was characterized by X-ray diffraction analysis (XRD). Figure 1 As shown, the prepared magnetic core has an amorphous structure.

[0071] Example 2

[0072] The preparation process of Example 2 is basically the same as that of Example 1, except that the composition is Fe 83 Si 2.8 B 1.7 P 5.5 C 0.5 Cr 2.1 Ni 4.4 .

[0073] Example 3

[0074] The preparation process of Example 3 is basically the same as that of Example 1, except that the composition is Fe 84 Si 2.8 B 1.7 P5C 0.5 Cr 2.1 Ni 3.9 .

[0075] Example 4

[0076] The preparation process of Example 4 is basically the same as that of Example 1, except that the pre-treated amorphous core is placed in a vacuum annealing furnace for annealing at a vacuum degree of 5*10 -3 The annealing temperature curve is as follows: heating to 250°C at 10°C / min, heating to 450°C at 2°C / min, keeping the temperature for 60min and then cooling in the furnace to obtain an amorphous magnetic core.

[0077] Comparative Example 1

[0078] The preparation process of Comparative Example 1 is basically the same as that of Example 1, except that the alloy composition is designed to be Fe s2 Si 7.6 B1.8 P6C 0.5 Cr 2.1 .

[0079] Comparative Example 2

[0080] The preparation process of Comparative Example 2 is basically the same as that of Example 1, except that the alloy composition is designed to be Fe 86.7 Si 7.8 B 2.5 C 0.5 Cr 2.5 .

[0081] Comparative Example 3

[0082] The preparation process of Comparative Example 3 is basically the same as that of Example 1, except that the alloy composition is designed to be Fe 88.2 B 4.8 P 6.5 C 0.5 .

[0083] Comparative Example 4

[0084] The preparation process of Comparative Example 4 is basically the same as that of Example 1, except that the pre-treated amorphous core is placed in a vacuum annealing furnace for annealing at a vacuum degree of 5*10 -3 The annealing temperature curve is as follows: heating to 250°C at 10°C / min, heating to 510°C at 2°C / min, keeping the temperature for 60min and then cooling in the furnace to obtain an amorphous magnetic core.

[0085] Table 1 Magnetic properties test of Examples and Comparative Examples

[0086]

[0087]

[0088] The results in Table 1 show that by improving the alloy composition and adding Ni and P elements, the performance of the amorphous powder core can be significantly improved. Based on the improved alloy composition, a gradient annealing process in a vacuum environment can fully release the stress within the core. The vacuum expel the air from the air gap inside the magnetic powder core, making the core more compact and denser, thereby improving the magnetic permeability. The magnetic permeability of the amorphous core is ≥60; the loss of the amorphous core at low frequency (50KHz, 100mT) is <200mW / cm 3 ; The loss of amorphous core at high frequency (1MHz, 20mT) is less than 250mW / cm 3 , to achieve industrial applications and meet the needs of high frequency and miniaturization.

Claims

1. An amorphous magnetic core with high magnetic permeability and low loss, characterized in that: The alloy composition of the amorphous core is Fe a Si b B c P d C e Cr f Ni g , a, b, c, d, e, f, g in the subscripts represent the mass percentages of the elements in the alloy composition, where 80≤a≤90, 0.1≤b≤12, 0.1≤c≤6, 0.2≤d≤10, 0.1≤e≤1.0, 0.5≤f≤6.0, 0.5≤g≤10, and a+b+c+d+e+f+g=100; The magnetic permeability of the amorphous magnetic core is ≥60.

2. The high permeability and low loss amorphous magnetic core according to claim 1, characterized in that: The loss of the amorphous core at low frequency is less than 200mW / cm 3 ; And / or the loss of the amorphous core at high frequency is less than 250mW / cm 3 .

3. The high permeability and low loss amorphous magnetic core according to claim 1, characterized in that: The particle size of the amorphous magnetic core is 15 μm-40 μm.

4. A method for preparing an amorphous magnetic core with high magnetic permeability and low loss according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) preparing ingredients and smelting according to the mass percentage of each component of the amorphous magnetic core to obtain an alloy ingot, and then preparing an amorphous powder by gas atomization; (2) weighing an inorganic coating, dispersing the inorganic coating in an organic solvent to obtain a mixed solution, then adding a silane coupling agent and amorphous powder to the mixed solution, mixing and stirring, and drying to obtain a modified amorphous powder; (3) dissolving the epoxy resin in an organic solvent to form an epoxy resin solution, mixing the epoxy resin solution with the modified amorphous powder, drying, and crushing to obtain the epoxy resin modified coated amorphous powder; (4) The epoxy resin modified and coated amorphous powder is added into a mold and pressed, and an amorphous magnetic core is obtained by gradient annealing in a vacuum environment.

5. The preparation method according to claim 4, characterized in that The inorganic coating material in step (2) is one or more of nano-alumina and nano-hexagonal boron nitride; The particle size of the nano-aluminum oxide is less than 100 nm, and the particle size of the nano-hexagonal boron nitride is less than 100 nm; The weight of the inorganic coating is 0.1%-2% of the weight of the amorphous powder.

6. The preparation method according to claim 4, wherein the mass ratio of the inorganic coating to the organic solvent in step (2) is 1:20-200; In step (3), the mass ratio of epoxy resin to organic solvent is 1:20-200.

7. The preparation method according to claim 4, characterized in that The silane coupling agent is any one of KH550, KH560, and KH602; The weight of the silane coupling agent is 0.1%-2% of the weight of the amorphous powder.

8. The preparation method according to claim 4, characterized in that The weight of the epoxy resin in step (3) is 1%-4% of the weight of the amorphous powder.

9. The preparation method according to claim 4, characterized in that The gradient annealing in step (4) includes: a first stage annealing with a heating rate of 5°C / min-15°C / min and an annealing temperature of 200°C-300°C; a second stage annealing with a heating rate of 1°C / min-5°C / min and an annealing temperature of 400°C-500°C; After reaching the second stage annealing temperature, keep warm for 30min-120min.

10. Use of the high permeability and low loss amorphous magnetic core according to any one of claims 1 to 3 in high-frequency inductors or transformers.

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