Magnetic powder core and hot-pressing preparation method and application thereof

Abstract

The invention provides a hot-pressing preparation method and application of a magnetic powder core. The hot-pressing preparation method comprises the following steps: carrying out insulation coating on glassy state soft magnetic amorphous alloy powder to obtain an intermediate powder material with a coating structure; the coating structure comprises a first coating layer or comprises a first coating layer and a second coating layer which are arranged in sequence; the first coating layer comprises nano inorganic particles and phosphate, and the second coating layer comprises an organic coating material; carrying out hot pressing treatment on the material containing the intermediate powder material to obtain a magnetic powder core; the adopted glassy soft magnetic amorphous alloy powder has a supercooled liquid phase region, the lowest temperature and the highest temperature of the supercooled liquid phase region are Tg and Tx respectively, the temperature of the hot pressing treatment is (Tg-20 DEG C)-(Tx-20 DEG C), the pressure of the hot pressing treatment is 100-500 MPa, and the holding time is 2 s-120 min. According to the magnetic powder core provided by the invention, the coating layer can be kept complete in the hot pressing process, and the magnetic powder core has relatively high density, high resistivity, high magnetic conductivity and low loss.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology, specifically relating to a magnetic powder core and its hot-pressing preparation method and application, including coating and hot-pressing glassy soft magnetic amorphous alloy powder to prepare a magnetic powder core or a magnetic functional device containing the magnetic powder core. Background Technology

[0002] In the field of soft magnetic materials, amorphous alloys are widely used due to their excellent magnetic properties, especially in transformers, inductors, motors, and electromagnetic shielding. With the development of third-generation semiconductor technology, the eddy current loss problem of traditional metallic soft magnetic materials at high frequencies has become increasingly prominent. To adapt to high-frequency applications, amorphous alloys are being shifted towards magnetic powder cores, using surface-coating with insulating materials to reduce eddy current losses. However, the hard and brittle characteristics of amorphous materials at room temperature mean that higher stress is required for the same deformation, and the accumulated residual stress is difficult to release through heat treatment (due to the thermal stability limitations of amorphous alloys, it is difficult to completely release residual stress). This results in the current performance of amorphous materials in magnetic powder core products not being fully realized, necessitating further optimization of their manufacturing processes and material combinations.

[0003] Existing magnetic powder core fabrication processes suffer from low density and relatively low permeability. Furthermore, while increasing hot-pressing pressure can improve core density to some extent, high pressures can lead to deformation during hot-pressing, causing the surface coating of the core to crack and drastically deteriorate its soft magnetic properties. Therefore, developing a fabrication process for amorphous magnetic powder cores that can adapt to hot-pressing deformation requirements and achieve higher density, higher relative permeability, and lower losses is a crucial issue that urgently needs to be addressed to advance the application of amorphous materials in high-frequency fields. Summary of the Invention

[0004] To address the above problems, the present invention provides the following technical solution:

[0005] One objective of this invention is to provide a hot-pressing method for preparing magnetic powder cores, comprising:

[0006] An insulating coating is applied to glassy soft magnetic amorphous alloy powder to obtain an intermediate powder material with a coating structure; the coating structure includes a first coating layer, or the coating structure includes a first coating layer and a second coating layer sequentially arranged along a direction away from the glassy soft magnetic amorphous alloy powder; the first coating layer includes nano-inorganic particles and phosphate, and the second coating layer includes an organic coating material;

[0007] The material containing the intermediate powder material is subjected to hot pressing to obtain a magnetic powder core.

[0008] The glassy soft magnetic amorphous alloy powder is a glassy soft magnetic amorphous alloy powder containing a supercooled liquid phase region in DSC testing, wherein the minimum and maximum temperatures of the supercooled liquid phase region are T, respectively. g T x T g and T x Given the glass transition temperature and first crystallization initiation temperature of the glassy soft magnetic amorphous alloy powder measured at a heating rate of 40℃ / min, the temperature of the hot pressing treatment is (T g -20℃~(T x -20℃);

[0009] The hot pressing treatment is either isobaric pressing or non-isobaric pressing. The isobaric pressing pressure is 100–500 MPa, and the time is 2 seconds–120 minutes. The maximum pressing pressure P of the non-isobaric pressing is... max The pressure ranges from 100 to 500 MPa, with a total time of 2 seconds to 120 minutes, and the pressure during the non-isobaric pressing process is greater than 1 / 2 P. max The time ranges from 0.1s to 30s.

[0010] Compared to traditional cold pressing processes, the method provided by this invention can obtain magnetic powder cores with high density, high permeability, and low loss under appropriate hot pressing pressure conditions. These magnetic powder cores can be directly formed into magnetic blocks, or they can be combined with insulated wires during the molding process to form various magnetic components (such as inductors, transformers, etc.). Alternatively, the molded blocks can be combined with insulated wires to form various magnetic components. The magnetic blocks and magnetic components based on these magnetic powder cores exhibit high permeability, low loss, high strength, and do not shed powder upon touch.

[0011] In some embodiments, the non-isotropic pressing can be performed using a camshaft.

[0012] In some embodiments, the method specifically includes: providing a first mixture containing glassy soft magnetic amorphous alloy powder, nano-inorganic particles, phosphoric acid, and a first solvent; removing at least a portion of the first solvent from the first mixture to obtain a first intermediate powder material with a first coating layer; and performing the hot pressing treatment on the material containing the first intermediate powder material to obtain the magnetic powder core.

[0013] In this invention, phosphoric acid is used to form the first coating layer. On the one hand, phosphoric acid can form good passivation and bonding with the surface of glassy soft magnetic amorphous alloy powder. On the other hand, phosphoric acid reacts chemically with inorganic coatings to form phosphates. The two aspects work together to make the first coating layer well-formed and firm, so that it is not easy to break during hot pressing and can remain intact.

[0014] In some embodiments, the mass of the nano-inorganic particles in the first mixture is 0.01 wt.% to 2.5 wt.% of the mass of the glassy soft magnetic amorphous alloy powder. That is, the coating amount of the nano-inorganic particles is 0.01 wt.% to 2.5 wt.% of the mass of the glassy soft magnetic amorphous alloy powder. If the content of nano-inorganic particles is low, the low inorganic coating amount will not significantly improve the permeability and density of the magnetic powder core. If the inorganic coating amount is high, the coating layer will be too thick, resulting in a large air gap, which will disrupt the magnetic circuit.

[0015] In some embodiments, the phosphoric acid content in the first mixture is 0.01–1.5 wt.%. If the phosphoric acid content is too low, the first coating layer will be incomplete; if the phosphoric acid content is too high, the first coating layer will be too thick and uneven.

[0016] In some embodiments, the first solvent includes at least one of water, ethanol, acetone, gasoline, benzene, or xylene. However, it is not limited to this.

[0017] In some embodiments, the method specifically includes:

[0018] A first mixture containing glassy soft magnetic amorphous alloy powder, nano-inorganic particles, phosphoric acid and a first solvent is provided, and at least part of the first solvent is removed from the first mixture to obtain a first intermediate powder material having a first coating layer.

[0019] A second mixture comprising the first intermediate powder material, an organic coating material, and a second solvent is provided, and at least a portion of the second solvent is removed from the second mixture to obtain a second intermediate powder material having a first coating layer and a second coating layer.

[0020] The material containing the second intermediate powder material is subjected to the aforementioned hot pressing treatment to obtain the magnetic powder core.

[0021] By forming a second coating layer containing organic coating material on the first coating layer, the deformation capability of the magnetic powder core during the hot pressing process can be further improved.

[0022] In some embodiments, the content of the organic coating material in the second mixture is 0.01% to 2.5 wt.% of the mass of the first intermediate powder material. That is, the coating amount of the organic coating material is 0.01 wt% to 2.5 wt% of the mass of the glassy soft magnetic amorphous alloy powder with the first coating layer. Too low an organic coating amount will result in the coating layer being difficult to cover all surfaces, while too high an organic coating amount will result in the coating layer being too thick, resulting in a large air gap and thus breaking the magnetic circuit.

[0023] In some embodiments, the second mixture further includes an organic coating accelerator, which includes at least one of a crosslinking agent, a curing agent, an initiator, and a surface modifier.

[0024] Furthermore, the amount of the crosslinking agent is 0-20% of the organic coating material, the amount of the curing agent is 0-20% of the organic coating material, and the amount of the initiator is 0-20% of the organic coating material. The specific selection of the crosslinking agent, curing agent, and initiator is determined according to the specific selection of the silicone resin or polyimide; any crosslinking agent, curing agent, or initiator suitable for the silicone resin or polyimide can be used.

[0025] In some embodiments, the second solvent includes at least one of water, ethanol, acetone, gasoline, benzene, or xylene. However, it is not limited to this.

[0026] In some embodiments, the material containing the intermediate powder material is a powder material or a blank, wherein the blank is obtained by cold pressing of the powder material containing the intermediate powder material.

[0027] In some embodiments, the preparation method includes directly performing the hot pressing treatment on the powder material, or performing the hot pressing treatment on the blank, or first removing the glue from the blank and then performing the hot pressing treatment.

[0028] In some embodiments, the nano-inorganic particles include at least one of nano-oxides, nano-carbides, nano-nitrides, nano-carbonates, nano-hydroxides, and nano-inorganic minerals.

[0029] Furthermore, the nano-oxide includes at least one of SiO2, Al2O3, MgO, ZrO2, TiO2, ZnO, MnO, Mn2O3, FeO, Fe2O3, Fe3O4, manganese-zinc ferrite, and nickel-zinc ferrite, but is not limited thereto.

[0030] Furthermore, the nano-carbide includes at least one of silicon carbide, boron carbide, aluminum carbide, zirconium carbide, and titanium carbide, but is not limited thereto.

[0031] Furthermore, the nano-nitrides include at least one of silicon nitride, boron nitride, aluminum nitride, zirconium nitride, and titanium nitride, but are not limited thereto.

[0032] Furthermore, the nano carbonate includes at least one of calcium carbonate, magnesium carbonate, zinc carbonate, and manganese carbonate, but is not limited thereto.

[0033] Furthermore, the nano hydroxide includes at least one of calcium hydroxide, magnesium hydroxide, zinc hydroxide, and manganese hydroxide, but is not limited thereto.

[0034] Furthermore, the nano-inorganic minerals include at least one of wollastonite, mica, kaolin, metakaolin, paraffin wax, talc, feldspar, fly ash, cordierite, and sapphire, but are not limited thereto.

[0035] In some embodiments, the average particle size D of the nano-inorganic particles 50 The particle size is 1–1000 nm, with an preferred average particle size D. 50 The wavelength range is 5–50 nm.

[0036] In some embodiments, the nano-inorganic particles include at least MgO. The MgO-containing coating layer has high strength, ensuring its integrity during subsequent hot pressing, thereby further improving the resistivity of the resulting magnetic powder core.

[0037] Specifically, the nano-inorganic particles in the first coating layer are composed of MgO. x Y y Where Y represents other nano-inorganic particles besides MgO, x and y represent the mass percentage content of MgO and other nano-inorganic particles Y, respectively, and x+y=100, 0.1≤x≤100.

[0038] In some embodiments, the nano-inorganic particles include SiO2, Al2O3, and MgO.

[0039] In some preferred embodiments, the composition of the nano-inorganic particles in the first coating layer is A. a B b C c In this paper, A, B, and C represent SiO2, Al2O3, and MgO, respectively, and a, b, and c represent the mass percentages of SiO2, Al2O3, and MgO in the nano-inorganic particles, respectively, with a+b+c=100, 5≤a≤95, 5≤b≤95, and 5≤c≤95. The invention unexpectedly discovered that the above-mentioned mass ratio of SiO2, Al2O3, and MgO results in a smoother and more complete first coating layer, exhibiting better fluidity during hot pressing. This leads to more uniform powder deformation during magnetic core preparation. Poor fluidity can cause the powder to become stuck in certain areas during deformation, potentially leading to coating layer cracking under large deformation requirements. Furthermore, the above mass ratio yields magnetic powder cores with high permeability and density and low magnetic loss. More preferably, 40≤a≤80, 5≤b≤35, and 5≤c≤35. Within this mass ratio range, the eddy current loss of the obtained magnetic powder core is further reduced, and unexpectedly, eddy current loss under high-frequency conditions is also improved.

[0040] In some embodiments, the organic coating material includes one or more combinations of polyimide, silicone resin, or epoxy resin.

[0041] In some embodiments, the silicone resin includes one or more of polyalkyl silicone resin, polyaryl silicone resin, and polyalkylaryl silicone resin, but is not limited thereto. The epoxy resin includes pure epoxy resin and modified epoxy resin, but is not limited thereto.

[0042] In some embodiments, the composition of the organic coating material in the second coating layer is EeFfGg, where E represents silicone resin, F represents epoxy resin, G represents polyimide, and e, f, and g represent the mass percentages of silicone resin, epoxy resin, and polyimide in the organic coating material, respectively, with e+f+g=100, 0≤e≤100, 0≤f≤100, and 0≤g≤100. More preferably, 60≤e≤95 and 5≤f≤40. When the compounding ratio of silicone resin and epoxy resin is within this range, it can better balance the stability and flowability under high-temperature conditions.

[0043] The glassy soft magnetic amorphous alloy powder can be any glassy soft magnetic amorphous alloy powder known in the art that has a supercooled liquid phase region in DSC testing. The present invention does not make any particular limitation on this. For example, it can include one or more of FePBNbCr, FeSiBP, FePC, FeCoPC, FeNiBP, FeNiBPNb, FeNbBY, FeCoNbBRe, FeSiBPNb, FeSiBPNbCu, FeSiBPC, and FeMoPCBSi, but is not limited thereto.

[0044] In some embodiments, the average particle size D of the glassy soft magnetic amorphous alloy powder 50 The range is 1–100 μm.

[0045] In some embodiments, the volume fraction of the crystalline phase in the glassy soft magnetic amorphous alloy powder is less than 2%.

[0046] In some embodiments, the average thickness of the first coating layer is 1 to 500 nm, preferably 5 to 300 nm.

[0047] In some embodiments, the average thickness of the second coating layer is 0 to 500 nm, preferably 5 to 300 nm.

[0048] In some embodiments, the average total thickness of the first coating layer and the second coating layer is 1 to 1000 nm, preferably 5 to 500 nm.

[0049] The thickness of the coating layer affects both the permeability and loss of the magnetic powder core. If the coating layer is too thick, the soft magnetic properties will deteriorate. The coating layer of the above-mentioned appropriate thickness can remain intact during the hot pressing process, while giving the magnetic powder core good permeability and low loss.

[0050] In some embodiments, the mass percentage of the intermediate powder material in the material is 10% to 100%.

[0051] In some embodiments, the material containing the intermediate powder material may further include non-glassy powder. That is, the coated intermediate powder material can be directly hot-pressed, or the coated intermediate powder material can be mixed with other non-glassy powders to form a mixture before hot pressing.

[0052] The hot pressing can be performed using ordinary resistance wire or silicon carbide rod, infrared, microwave, or other methods. It can also be performed by directly heating the mold with electric current or by hot pressing sintering with discharge plasma. The present invention does not make any particular limitation on this method. The heating can be performed in a vacuum, a protective atmosphere, diluted atmosphere, air, or an atmosphere containing the above gases and exceeding atmospheric pressure.

[0053] In some embodiments, the method further includes: after completing the hot pressing process, subjecting the obtained magnetic powder core to heat treatment, wherein the heat treatment is isothermal or non-isothermal; the isothermal heat treatment is performed at a temperature of 300–560°C for a holding time of 5–120 min; the non-isothermal heat treatment involves an average heating rate of 1–100°C / s, a temperature of 340–600°C, and a holding time of 5–60 min at 340–600°C. This heat treatment can further reduce the already limited residual stress in the magnetic powder core and improve its soft magnetic properties.

[0054] In some embodiments, the temperature of the isothermal heat treatment is (T x -160)℃~(T x -100)℃, heat preservation time is 10min~120min.

[0055] The second objective of this invention is to provide a magnetic powder core, which is prepared by the method described in any of the above technical solutions.

[0056] The third objective of this invention is to provide a magnetic functional device, which includes magnetic inductor components composed of magnetic powder cores and wires as described in any of the above technical solutions. The magnetic inductor components include, but are not limited to, high-frequency inductors, chip inductors, high-frequency transformers, or magnetic powder core motors.

[0057] Compared with the prior art, the present invention has at least the following beneficial effects:

[0058] (1) The magnetic powder core prepared by the preparation method provided by the present invention has high permeability and density, and effectively reduces the loss of magnetic powder core; compared with the traditional cold pressing process, the method provided by the present invention can obtain magnetic powder core with high density and high permeability under moderate hot pressing pressure, and the obtained magnetic powder core has high strength and does not fall off when touched.

[0059] (2) In this invention, nano-MgO and other nano-inorganic materials are used to inorganically coat glassy soft magnetic amorphous alloy powder, while organic silicone resin, epoxy resin and other materials are used for organic coating. By adjusting the amount of inorganic coating and organic coating, the obtained coating layer is not easy to fail in the hot pressing process, the coating layer can be kept intact, and the magnetic permeability, density and loss of the magnetic powder core are improved at the same time.

[0060] (3) Under the hot pressing process conditions provided by the present invention, the eddy current loss of the magnetic powder core can be reduced by adjusting the mass percentage of SiO2, Al2O3 and MgO, especially the eddy current loss under high frequency environment. When the mass percentages a, b and c of SiO2, Al2O3 and MgO satisfy 40≤a≤80, 5≤b≤35 and 5≤c≤35, the effect of reducing the eddy current loss of the magnetic powder core is excellent.

[0061] (4) Heat treatment of the magnetic powder core obtained by hot pressing can further improve the permeability and density. In addition, heat treatment can reduce stress to optimize soft magnetic properties, reduce hysteresis loss, and thus reduce total loss. Attached Figure Description

[0062] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0063] Figure 1a This is a graph showing the total loss of the magnetic powder cores prepared in Examples 1-4 as a function of frequency at 50mT;

[0064] Figure 1b , Figure 1c , Figure 1d The images are SEM images of the magnetic powder cores prepared in Examples 2, 3, and 4, respectively.

[0065] Figure 2 The graph shows the total loss of the magnetic powder cores prepared in Examples 4-7 and Comparative Example 8 at 50mT as a function of frequency.

[0066] Figure 3The graph shows the total loss of the magnetic powder cores prepared in Examples 3, 8-11 and Comparative Example 3 at 50mT as a function of frequency.

[0067] Figure 4 This is a graph showing the total loss of the magnetic powder cores prepared in Examples 10, 12 and 13 at 50mT as a function of frequency.

[0068] Figure 5 This is a graph showing the total loss of the magnetic powder cores prepared in Examples 14-19 as a function of frequency at 50mT;

[0069] Figure 6 The graph shows the total loss of the magnetic powder cores prepared in Example 12 and Comparative Example 1 at 50mT and 100mT as a function of frequency. Detailed Implementation

[0070] The technical solutions of the present invention will be described in detail below with reference to specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the present invention. The specific functional details disclosed herein should not be construed as limiting, but are merely intended to form the basis of the claims and to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0071] In addition, unless otherwise specified, all raw materials used in the following embodiments can be purchased from the market or other sources, and all production and testing equipment used are known in the art, as are the testing methods used.

[0072] In the specific embodiments of the present invention, the inorganic nanoparticle coating amount refers to the mass percentage of the inorganic nanoparticles used relative to the amorphous powder, and the organic coating amount refers to the mass percentage of the organic coating agent used relative to the amorphous powder with the inorganic coating layer.

[0073] Example 1

[0074] This embodiment provides a magnetic powder core and its hot-pressing preparation method. FePBNbCr amorphous powder is used as raw material, which undergoes inorganic and organic coating before hot pressing. The details are as follows:

[0075] 0.2 wt.% phosphoric acid, 0.1 wt.% hydrophilic nano-SiO2, 0.1 wt.% nano-Al2O3 and 0.3 wt.% nano-MgO were added to 25 wt.% ethanol and ultrasonically stirred for 4 min. Then, 0.06 wt.% PVP and 0.1 wt.% polyethylene glycol were added and ultrasonically stirred for 1 min. Then, a mixture of 0.1 wt.% KH550, 5 wt.% ethanol and 1 wt.% deionized water was added and manually stirred for 2 min to obtain a nano-oxide mixture for inorganic coating.

[0076] FePBNbCr amorphous powder was mixed with the above-prepared nano-oxide mixture, with the amount of nano-inorganic particles being 0.5 wt.% of the total mass of FePBNbCr amorphous powder and the content of phosphoric acid being 0.2 wt%. Ethanol was evaporated on a heating stage at 90°C with a stirring rate of 200 rpm. The powder after ethanol evaporation was passed through a 40-mesh sieve and placed in a drying oven to dry at 80°C for 1 hour and then at 160°C for 2 hours. The dried powder was then passed through a 40-mesh sieve again to obtain FePBNbCr amorphous powder with an inorganic coating layer. The inorganic coating layer contains the above-mentioned inorganic nanoparticles and also contains phosphate formed by the reaction of phosphoric acid and inorganic nanoparticles.

[0077] An organic coating mixture was obtained by dissolving silicone resin (Shin-Etsu KR5230), epoxy resin (TT310 resin), and curing agent (TT310 special curing agent) in 20 wt.% acetone at a mass ratio of 12:1:0.5. Then, the FePBNbCr amorphous powder with the inorganic coating layer was added to the mixture, with the total amount of silicone resin and TT310 resin being 1 wt.% of the FePBNbCr amorphous powder with the inorganic coating layer. After stirring until the particles were distinct, the mixture was passed through a 40-mesh sieve and then baked in an oven at 60°C for 2 hours to dry the acetone. The dried powder was then passed through a 100-mesh sieve to obtain FePBNbCr amorphous powder with both inorganic and organic coating layers.

[0078] Hot pressing was performed on FePBNbCr amorphous powder with inorganic and organic coatings: a release agent was sprayed onto the mold parts at both ends in contact with the powder, and 3g of FePBNbCr amorphous powder with coatings was added into the mold. In order to ensure that the powder is evenly dispersed in the mold, the powder was shaken or vibrated before hot pressing. Then, hot pressing (isobaric pressing) was performed at a pressure of 200MPa, a temperature of 390℃, and a holding time of 20min. A regular magnetic powder core ring sample with an outer diameter of 12.7mm and an inner diameter of 7.5mm was obtained.

[0079] The obtained magnetic powder core is measured for dimensions, inductance, and loss, and the corresponding permeability and loss per unit volume parameters are obtained by calculation.

[0080] It should be noted that the glass transition temperature (T0) of FePBNbCr amorphous powder was measured at 40℃ / min. g ) and the first crystallization initiation temperature (T x The temperatures are 475℃ and 506℃ respectively, meaning the suitable hot pressing temperature range is 455~486℃.

[0081] Examples 2-14

[0082] The only difference between Examples 2-14 and Example 1 is that the hot pressing pressure, hot pressing temperature, SiO2:Al2O3:MgO mass ratio and resin coating amount are changed according to Table 1. The rest are the same as in Example 1.

[0083] Examples 15-19

[0084] The only difference between Examples 15-19 and Example 12 is that after the hot pressing process, the obtained magnetic powder core is subjected to isothermal heat treatment. The temperature of the heat treatment is varied as shown in Table 1, and the heat treatment time is 1 hour.

[0085] Comparative Example 1

[0086] The difference between Comparative Example 1 and Example 12 is that the inorganic coating of Comparative Example 1 is the same as that of Example 12, but 2% W-6D epoxy resin is used for organic coating, and the coated powder is subjected to cold pressing: the cold pressing temperature is room temperature, the pressure is 2000 MPa, and the pressing time is 6 s (0.1 min). After pressing, it is heat-treated at 390℃ for 60 min.

[0087] Comparative Example 2

[0088] The only difference between Comparative Example 2 and Example 10 is that the inorganic nanoparticle coating amount of Comparative Example 2 is 3wt%, while the rest is the same as that of Example 10, and will not be repeated here.

[0089] Comparative Example 3

[0090] The only difference between Comparative Example 3 and Example 10 is that the inorganic nanoparticle coating amount of Comparative Example 3 is 0.005wt%, and the rest is the same as that of Example 10, which will not be repeated here.

[0091] Comparative Example 4

[0092] The only difference between Comparative Example 4 and Example 12 is that the organic nanoparticle coating amount of Comparative Example 4 is 3wt%, while the rest is the same as that of Example 12, and will not be repeated here.

[0093] Comparative Example 5

[0094] The only difference between Comparative Example 5 and Example 12 is that the hot pressing pressure of Comparative Example 5 is 800 MPa. The rest is the same as that of Example 12, and will not be repeated here.

[0095] Comparative Example 6

[0096] The only difference between Comparative Example 6 and Example 12 is that the hot pressing pressure of Comparative Example 6 is 80 MPa. The rest of the implementation is the same as that of Example 12, and will not be repeated here.

[0097] Comparative Example 7

[0098] The only difference between Comparative Example 7 and Example 12 is that the hot pressing temperature of Comparative Example 7 is 450°C. The rest of the implementation is the same as that of Example 12, and will not be repeated here.

[0099] Comparative Example 8

[0100] The only difference between Comparative Example 8 and Example 12 is that the hot pressing temperature of Comparative Example 8 is 505°C. The rest of the implementation is the same as that of Example 12, and will not be repeated here.

[0101] Comparative Example 9

[0102] The only difference between Comparative Example 9 and Example 12 is that the heat treatment temperature of Comparative Example 9 is 450°C. The rest of the implementation is the same as that of Example 12, and will not be repeated here.

[0103] After measuring the basic dimensional parameters (outer diameter, inner diameter, height, etc.) of the magnetic powder core ring samples prepared by the above cold pressing and hot pressing, the effective magnetic circuit parameters were calculated according to the GB 3658-2022 standard. After the surface of the magnetic powder core ring sample was wrapped with raw material tape for insulation, it was wound with enameled wire in a two-strand 10-turn winding manner. The inductance and loss data were tested according to the IEC-60404 magnetic measurement standard. After calculation, the permeability (100kHz) and loss (Pcv for 50mT@1MHz) of the magnetic powder cores prepared in the above embodiments and comparative examples can be obtained.

[0104] Table 1. Relevant process and performance parameters for preparing magnetic powder cores in Examples 1-19 and Comparative Examples 1-9 of the present invention.

[0105]

[0106]

[0107]

[0108] Figure 1aThe graph shows the change in total loss of the magnetic powder cores in Examples 1-4 with frequency at 50mT. It can be seen that the total loss of the magnetic powder core is significantly improved compared to 100MPa as the hot-pressing pressure increases. This invention separates the total loss of the magnetic powder core and finds that the loss obtained by this invention mainly originates from hysteresis loss. The method of this invention can effectively reduce eddy current loss because it controls the pressure to create smaller gaps between the magnetic powder core particles. Smaller gaps reduce air gaps in the magnetic powder core, reducing eddy current generation and thus reducing eddy current loss. Furthermore, the hot-pressing pressure should not be too high, as excessive pressure can damage the magnetic powder core particles. Damage to the particle surface creates more irregular shapes, increasing the energy required for magnetization and leading to increased hysteresis loss. Particle damage may also increase voids in the magnetic powder core, thereby increasing the generation and propagation of eddy currents.

[0109] Figure 1b , Figure 1c , Figure 1d The images show SEM images of the magnetic powder cores prepared in Examples 2, 3, and 4, respectively. A comparison reveals that the magnetic powder core particles prepared in Example 2 under 300 MPa pressure underwent slight deformation under hot pressing. This is because amorphous materials have good plasticity in the supercooled liquid phase, resulting in smaller gaps between the powder particles and increased core density. The size of the powder gaps directly affects the permeability and loss of the magnetic powder core. When the gaps are smaller, the contact area between particles increases, enhancing the magnetic coupling effect and thus improving permeability. The magnetic powder core prepared in Example 4 under a hot pressing pressure of 500 MPa may have suffered some particle damage due to the higher pressure, increasing internal inhomogeneity and reducing particle contact, thus hindering magnetic field transmission within the core and resulting in a decreasing trend in permeability.

[0110] Compared to cases where the hot-pressing pressure is too low or too high (e.g., Comparative Examples 4 and 5), the magnetic powder core performance is superior when the hot-pressing pressure is within the range of 100–500 MPa provided by this invention. Furthermore, considering the comprehensive factors of obtaining higher permeability, higher magnetic powder core density, and lower loss, the preferred hot-pressing pressure is 400 MPa.

[0111] Figure 2 The graph shows the total loss of the magnetic powder cores in Examples 4-7 and Comparative Example 8 at 50mT as a function of frequency. It can be seen that when the hot-pressing temperature is in the range of 460℃-480℃, the magnetic loss decreases with increasing temperature. However, in the range of 480℃-486℃, the magnetic loss increases with increasing temperature. This may be because if the hot-pressing temperature is too high, it will lead to severe crystallization of the magnetic powder core, and a significant increase in hysteresis loss and eddy current loss. Systematic research of this invention has found that when the hot-pressing temperature is (T... g -20℃~(T xWithin the temperature range of -20℃, the magnetic loss is at a low level. When it exceeds T... x At -20℃ (e.g., Comparative Example 8), magnetic loss increases significantly. Considering the overall factors of obtaining higher magnetic permeability, higher magnetic powder core density, and lower loss, the optimal hot-pressing temperature is 480℃.

[0112] Figure 3 This is a graph showing the total loss of the magnetic powder cores in Examples 3 and 8-11 as a function of frequency at 50 mT. The present invention found that, without resin coating (Example 8), the magnetic loss is low at low frequencies, but increases dramatically above 500 kHz, significantly higher than the loss after resin coating. After resin coating, the magnetic loss shows a trend of first decreasing and then increasing. Furthermore, at 50 mT and 200 kHz, the total loss of Example 8 is lower than that of Examples 3 and 9-11. The systematic study of this invention found that without resin coating, the hysteresis loss is low, but the eddy current loss increases sharply, especially at high frequencies. After resin coating, the hysteresis loss of the magnetic powder core increases slightly, but the eddy current loss decreases significantly. This may be because without resin, the magnetic powder particles are in direct contact, resulting in high permeability and low hysteresis loss. However, this direct contact also creates a larger eddy current loop, causing a sharp increase in eddy current loss at high frequencies, leading to higher total losses. While adding resin reduces permeability and increases hysteresis loss, the resin coating isolates the eddy current loop, significantly reducing eddy current loss at high frequencies and thus lowering total losses. Therefore, in some preferred embodiments, resin coating is preferred, and more preferably, a magnetic powder core with a resin coating of 1.5 wt.% exhibits superior overall performance.

[0113] Figure 4 The graph shows the total loss of the magnetic powder cores in Examples 10, 12, and 13 at 50 mT as a function of frequency. The total loss of the magnetic powder core is lowest when the mass ratio of SiO2:Al2O3:MgO is 3:1:1. This invention also investigated the effects of different oxide powder ratios on the loss, hysteresis loss, and eddy current loss of the magnetic powder core under 50 mT and 200 kHz conditions. When the mass ratio of SiO2:Al2O3:MgO is satisfied at 3:1:1, the eddy current loss is significantly reduced. Increasing the mass of SiO2 can effectively reduce the eddy current loss of the magnetic powder core, especially significantly reducing eddy current loss under high-frequency environments.

[0114] Figure 5 This is a graph showing the total loss of the magnetic powder cores in Examples 14-19 as a function of frequency at 50 mT. During heat treatment (annealing) in the temperature range of 350℃-390℃, the loss decreases with increasing annealing temperature. However, during annealing in the range of 390℃-430℃, the loss increases with increasing annealing temperature. The magnetic powder core loss reaches its lowest point at an annealing temperature of 390℃, with a loss of only 284 mW / cm² at 50 mT and 200 kHz. 3This invention also investigated the effects of different annealing temperatures on the loss, hysteresis loss, and eddy current loss of magnetic powder cores under conditions of 50 mT and 200 kHz. It was found that hot pressing significantly reduced the eddy current loss of the magnetic powder cores. For magnetic powder cores annealed at 350-390℃, the loss still mainly originated from hysteresis loss; however, for magnetic powder cores annealed at 410℃, hysteresis loss decreased while eddy current loss increased significantly. It was also found that the annealing temperature had a limited effect on improving hysteresis loss, but a significant improvement on eddy current loss. Eliminating residual stress can make the structure of the magnetic powder core more stable, reducing eddy current generation and thus reducing eddy current loss. However, when annealing above 390℃, the eddy current loss of the magnetic powder core increased sharply. This may be because excessively high annealing temperatures may lead to uneven particle size in the magnetic powder core, increasing the generation and propagation of eddy currents, thus increasing eddy current loss. The systematic research of this invention found that the heat treatment temperature and the minimum temperature T of the supercooled liquid phase region of the amorphous powder are related. x Satisfy: Heat treatment temperature is within (T) x -160)℃~(T x When the temperature is within the range of -100℃, the total loss of the magnetic powder core is at a low level.

[0115] Figure 6 The graph shows the total loss of the magnetic powder cores of Example 12 and Comparative Example 1 as a function of frequency at 50mT and 100mT. It can be seen that the hot pressing process of the present invention has lower loss than the traditional cold pressing process, especially the loss reduction is more obvious in the high frequency strong magnetic field environment. At the same time, the hot-pressed magnetic powder core has higher permeability and can play an important role in various electronic devices and systems.

[0116] The experiments conducted according to this invention have confirmed that using a composite of nano-SiO2, Al2O3, and MgO as the coating material obtained from the above-described steps for inorganic nanoparticles results in a smoother coating layer on the surface of amorphous powder, better powder flowability during hot pressing, easier attainment of good magnetic properties, and improved aging resistance after hot pressing. Therefore, in embodiments where both magnetic properties and aging resistance are required, it is preferable that the inorganic material comprises nano-SiO2, Al2O3, and MgO.

[0117] Examples 20-48

[0118] Examples 20-48 describe the inorganic and organic coating processes used to coat FePBNbCr amorphous powder. For the inorganic coating, the type, ratio, coating amount, and particle size of the inorganic nanoparticles were varied as shown in Table 2. The solvents shown in Table 2 are those used to disperse the inorganic nanoparticles, and the solvent amount was 20 wt.% for all processes. For the organic coating, silicone resin (Shin-Etsu KR5230) was used, with a coating amount of 1.5 wt.%. The hot-pressing temperature was 480°C, the pressure was 400 MPa, and the time was 20 min.

[0119] Table 2. Relevant process and performance parameters for preparing magnetic powder cores in Examples 20-48 of this invention.

[0120]

[0121]

[0122]

[0123] Note: The MgO mass ratio in Table 2 refers to its mass percentage in inorganic nanoparticles.

[0124] Examples 49-56

[0125] Examples 49-56 describe the inorganic and organic coating processes used to coat FePBNbCr amorphous powder. The inorganic coating employed MgO inorganic nanoparticles at a coating weight of 0.5 wt.%. The type, ratio, and amount of the organic coating material were varied according to Table 3. Hot pressing was performed at 400 MPa, 480°C, and for 20 min. Following hot pressing, isothermal heat treatment was conducted at 370°C for 60 min.

[0126] Table 3. Relevant process and performance parameters for preparing magnetic powder cores in Examples 49-56 of this invention.

[0127]

[0128] Examples 57-67

[0129] Examples 57-67 describe the inorganic coating of different types of amorphous powders shown in Table 4. The inorganic coating uses MgO inorganic nanoparticles with a coating amount of 0.5 wt%, and no organic coating is performed. Examples 57-67 use soft magnetic amorphous powders of various types and D... 50 The hot pressing temperature and time, and the heat treatment temperature vary as shown in Table 4.

[0130] Table 4. Relevant process and performance parameters for preparing magnetic powder cores in Examples 57-67 of this invention.

[0131]

[0132] Examples 68-71

[0133] Examples 68-71 involved sequentially applying inorganic and organic coatings to the glassy soft magnetic amorphous alloy powders shown in Table 5. The inorganic coating used MgO inorganic nanoparticles at a coating weight of 0.5 wt%, while the organic coating used polyimide at a coating weight of 1.50 wt%. The resulting magnetic powder cores were then mixed with the crystalline soft magnetic powders shown in Table 5, and the mixture was hot-pressed at 480°C, 400 MPa, and for 20 minutes. The permeability and loss of the hot-pressed material were then tested.

[0134] Table 5. Relevant process and performance parameters for preparing magnetic powder cores in Examples 68-71 of this invention.

[0135]

[0136]

[0137] In summary, the method provided by this invention can obtain magnetic bulk materials with high density under appropriate hot-pressing conditions, or can form various magnetic components (such as inductors, transformers, etc.) by combining them with insulated wires during the molding process, or combine the molded bulk materials with insulated wires to form various magnetic components. The bulk materials or magnetic components have high permeability and low loss, and the bulk materials or devices have high strength and do not shed powder when touched. Amorphous alloy / nanocrystalline alloy powder with a supercooled liquid phase region, after undergoing the above-mentioned coating process and hot pressing, can obtain an amorphous magnetic powder core with a complete coating layer, and the magnetic powder core density is significantly increased to 6.0-7.0 g / cm³. 3 Furthermore, the magnetic powder core has a high resistivity, approximately 10⁻⁶. 3 ~10 9 Due to the good integrity of the coating layer of the magnetic powder core, the final soft magnetic properties are excellent, with high relative permeability (75-200) and high frequency stability. The frequency of permeability fluctuation of different magnetic powder cores within 10% ranges from 1 to 100 MHz. Furthermore, the magnetic powder cores fabricated by this method have ultra-low losses, with a total loss P at 100 mT@100 kHz. cv It can reach 100-400mW / cm 3 In particular, its high-frequency loss performance is excellent, with a total loss P at 50mT@1MHz. cv It can be as low as 800-3000mW / cm 3 .

[0138] In addition, the inventors of this case also conducted experiments with other raw materials, process operations and process conditions described in this specification, referring to the aforementioned embodiments. For example, in the inorganic coating process, the mass of phosphoric acid in the first mixture was 0.01 wt.% and 1.5 wt.% of the mass of the glassy soft magnetic amorphous alloy powder, and relatively ideal results were obtained.

[0139] The various aspects, embodiments, and features of this invention are intended to explain and illustrate the invention, but are not intended to limit the invention. The scope of the invention is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of this invention.

[0140] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that other changes, omissions, and / or additions may be made without departing from the spirit and scope of the invention, and that substantially equivalents may be substituted for the materials described in the embodiments. Therefore, this document is not intended to limit the invention to the specific embodiments disclosed, but rather to include all embodiments falling within the scope of the appended claims. Furthermore, unless specifically stated otherwise, any use of the terms first, second, etc., does not indicate any order or importance, but is merely used to distinguish one element from another.

Claims

1. A method for hot-pressing a magnetic powder core, characterized in that, include: Glassy soft magnetic amorphous alloy powder is coated to obtain an intermediate powder material with a coating structure. The coating structure includes a first coating layer, or it includes a first coating layer and a second coating layer sequentially disposed along a direction away from the glassy soft magnetic amorphous alloy powder; the first coating layer includes nano-inorganic particles and phosphate, and the second coating layer includes an organic coating material; The material containing the intermediate powder material is subjected to hot pressing to obtain a magnetic powder core. The glassy soft magnetic amorphous alloy powder is a glassy soft magnetic amorphous alloy powder containing a supercooled liquid phase region in DSC testing, wherein the minimum and maximum temperatures of the supercooled liquid phase region are T, respectively. g T x T g and T x Given the glass transition temperature and first crystallization initiation temperature of the glassy soft magnetic amorphous alloy powder measured at a heating rate of 40℃ / min, the temperature of the hot pressing treatment is (T g -20℃~(T x -20℃); The hot pressing treatment is either isobaric pressing or non-isobaric pressing. The isobaric pressing pressure is 100–500 MPa, and the time is 2 seconds–120 minutes. The maximum pressing pressure P of the non-isobaric pressing is... max The pressure ranges from 100 to 500 MPa, the total time is from 2 seconds to 120 minutes, and the pressure during the non-isobaric pressing process is greater than 1 / 2 P. max The time ranges from 0.1s to 30s.

2. The hot-pressing preparation method according to claim 1, characterized in that: The nano-inorganic particles include at least one of nano-oxides, nano-carbides, nano-nitrides, nano-carbonates, nano-hydroxides, and nano-inorganic minerals; preferably, the nano-oxides include at least one of SiO2, Al2O3, MgO, ZrO2, TiO2, ZnO, MnO, Mn2O3, FeO, Fe2O3, Fe3O4, manganese-zinc ferrite, and nickel-zinc ferrite; the nano-carbides include at least one of silicon carbide, boron carbide, aluminum carbide, zirconium carbide, and titanium carbide; the nano-nitrides include at least one of silicon nitride, boron nitride, aluminum nitride, zirconium nitride, and titanium nitride; the nano-carbonates include at least one of calcium carbonate, magnesium carbonate, zinc carbonate, and manganese carbonate; the nano-hydroxides include at least one of calcium hydroxide, magnesium hydroxide, zinc hydroxide, and manganese hydroxide; and the nano-inorganic minerals include at least one of wollastonite, mica, kaolin, metakaolin, paraffin wax, talc, feldspar, fly ash, cordierite, and sapphire. And / or, the average particle size D of the nano-inorganic particles 50 The particle size is 1–1000 nm, with an preferred average particle size D. 50 The wavelength is 5–50 nm. And / or, the coating amount of the nano-inorganic particles is 0.01 wt.% to 2.5 wt.% of the mass of the glassy soft magnetic amorphous alloy powder; And / or, the organic coating material includes at least one of epoxy resin, silicone resin or polyimide; And / or, the coating amount of the organic coating material is 0.01wt% to 2.5wt% of the mass of the glassy soft magnetic amorphous alloy powder having the first coating layer.

3. The hot-pressing preparation method according to claim 2, characterized in that: The nano-inorganic particles include at least MgO; Preferably, the composition of the nano-inorganic particles in the first coating layer is MgOxYy, where Y represents other nano-inorganic particles besides MgO, x and y represent the mass percentage content of MgO and other nano-inorganic particles Y, respectively, and x+y=100, 0.1≤x≤100; Preferably, the nano-inorganic particles include nano-SiO2, Al2O3, and MgO; more preferably, the nano-inorganic particles in the first coating layer are composed of A. a B b C c Where A, B, and C represent SiO2, Al2O3, and MgO, respectively, and a, b, and c represent the mass percentage content of SiO2, Al2O3, and MgO in the nano-inorganic particles, respectively, a+b+c=100, and 5≤a≤95, 5≤b≤95, 5≤c≤95. More preferably, 40≤a≤80, 5≤b≤35, and 5≤c≤35.

4. The hot-pressing preparation method according to claim 2 or 3, characterized in that: The composition of the organic coating material in the second coating layer is E e F f G g In this formula, E represents silicone resin, F represents epoxy resin, G represents polyimide, and e, f, and g represent the mass percentages of silicone resin, epoxy resin, and polyimide in the organic coating material, respectively, and e+f+g=100, 0≤e≤100, 0≤f≤100, and 0≤g≤100.

5. The hot-pressing preparation method according to claim 1, characterized in that, Specifically, this includes: providing a first mixture containing glassy soft magnetic amorphous alloy powder, nano-inorganic particles, phosphoric acid, and a first solvent; removing at least a portion of the first solvent from the first mixture to obtain a first intermediate powder material having a first coating layer; and subjecting the material containing the first intermediate powder material to the hot pressing treatment to obtain the magnetic powder core. Alternatively, a first mixture comprising glassy soft magnetic amorphous alloy powder, nano-inorganic particles, phosphoric acid, and a first solvent is provided; at least a portion of the first solvent is removed from the first mixture to obtain a first intermediate powder material having a first coating layer; a second mixture comprising the first intermediate powder material, an organic coating material, and a second solvent is provided; at least a portion of the second solvent is removed from the second mixture to obtain a second intermediate powder material having a first coating layer and a second coating layer; the material containing the second intermediate powder material is subjected to the aforementioned hot pressing treatment to obtain the magnetic powder core; Alternatively, the material containing the intermediate powder material is a powder material or a blank, wherein the blank is obtained by cold pressing of the powder material containing the intermediate powder material; the preparation method includes directly performing the hot pressing treatment on the powder material, or performing the hot pressing treatment on the blank, or first removing the glue from the blank and then performing the hot pressing treatment.

6. The hot-pressing preparation method according to claim 5, characterized in that: The mass of the nano-inorganic particles in the first mixture is 0.01 wt.% to 2.5 wt.% of the mass of the glassy soft magnetic amorphous alloy powder, and the mass of the phosphoric acid is 0.01 wt.% to 1.5 wt.% of the mass of the glassy soft magnetic amorphous alloy powder. And / or, the content of the organic coating material in the second mixture is 0.01 wt% to 2.5 wt% of the mass of the first intermediate powder material; And / or, the second mixture further includes an organic coating accelerator, said organic coating accelerator including at least one of a crosslinking agent, a curing agent, an initiator, and a surface modifier; And / or, the first solvent and the second solvent independently include at least one of water, ethanol, acetone, gasoline, benzene or xylene.

7. The hot-pressing preparation method according to claim 1, characterized in that: The average particle size D of the glassy soft magnetic amorphous alloy powder 50 The range is 1–100 μm; And / or, the volume fraction of the crystalline phase in the glassy soft magnetic amorphous alloy powder is less than 2%; And / or, the material containing the intermediate powder material further includes non-glassy powder; And / or, the mass percentage of intermediate powder material in the material is 10% to 100%.

8. The hot-pressing preparation method according to claim 1, characterized in that, Also includes: After completing the hot pressing process, the obtained magnetic powder core is subjected to heat treatment, which is either isothermal or non-isothermal. The isothermal heat treatment is performed at a temperature of 300–560°C for a holding time of 5–120 min. The non-isothermal heat treatment is performed at an average heating rate of 1–100°C / s, at a temperature of 340–600°C for a holding time of 5–60 min at 340–600°C. Preferably, the temperature of the isothermal heat treatment is (T x -160)℃~(T x -100)℃, heat preservation time is 10min~120min.

9. A magnetic powder core, characterized in that: It is prepared by the hot pressing method of magnetic powder core according to any one of claims 1-8.

10. An application of a magnetic powder core, including magnetic functional devices, characterized in that, The magnetic inductor components comprised of the magnetic powder core and wires as described in claim 9, wherein the magnetic inductor components include high-frequency inductors, chip inductors, high-frequency transformers, or magnetic powder core motors.

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