Low-loss high-iron nanocrystalline soft magnetic powder core and preparation method thereof

Abstract

The invention relates to a low-loss high-iron nanocrystalline soft magnetic powder core and a preparation method thereof. Comprising the following steps: (1) carrying out embrittlement heat treatment on an amorphous ribbon, and crushing to obtain a pretreated amorphous ribbon; (2) the pretreated amorphous ribbon and an inorganic coating material are mixed and then subjected to ball milling, and inorganic coating soft magnetic powder is obtained; (3) adding an organic binding material and a lubricant into the inorganic coated soft magnetic powder, granulating and sieving to obtain organic-inorganic coated soft magnetic powder particles; and (4) after pressing and heat treatment, the low-loss high-iron nanocrystalline soft magnetic powder core is obtained. According to the method, the amorphous ribbon with the iron content of 80-86 wt% serves as the raw material to prepare the high-iron nanocrystalline soft magnetic powder core, the inorganic coating process and the pretreated amorphous ribbon ball-milling powder preparation process are combined, nanocrystalline powder is coated with inorganic nanometer oxide in the ball-milling powder preparation process, the independent inorganic coating process of nanocrystalline finished product powder is omitted, and the preparation process is simple and convenient. The process of the preparation method is shortened, and the simplification of the preparation process is realized.

Description

Technical Field

[0001] The invention relates to a low-loss high-iron nanocrystalline soft magnetic powder core and a preparation method thereof, belonging to the technical field of soft magnetic composite materials. Background Art

[0002] With the development of electronic products becoming increasingly miniaturized, high-frequency, energy-saving and integrated, the performance requirements for magnetic components are becoming increasingly higher. Metal soft magnetic powder cores have the characteristics of high saturation magnetic induction intensity, which enables them to maintain good magnetic properties under high magnetic field intensity. In addition, metal soft magnetic powder cores have good high-frequency characteristics and can maintain stable magnetic properties under high frequencies. Moreover, they can be made into magnetic cores of various complex shapes through methods such as powder metallurgy, which can well meet the requirements of integrated design. At present, Finemet system nanocrystalline soft magnetic materials have ultra-high magnetic permeability, extremely low coercive force and relatively excellent saturation magnetization intensity due to their special amorphous and nanocrystalline dual-phase structure, and have become one of the preferred materials for high-frequency, low-consumption and small magnetic components in the future. In particular, Finemet nanocrystalline soft magnetic materials with high Fe content have the aforementioned excellent magnetic properties and show higher saturation magnetization intensity, which can meet the working conditions of high power and high current. However, the increase in Fe content will cause the amorphous formation ability of such materials to decrease. In order to obtain a completely amorphous structure, they are usually prepared into strips using a single-roller rapid quenching technology with a high cooling rate. In recent years, metal soft magnetic powder cores have shown excellent frequency stability and high-frequency and low-loss characteristics due to their distributed air gaps, so their application demand has continued to grow. For this reason, crushing high-Fe-content nanocrystalline strips into powder and further preparing them into metal magnetic powder cores has become one of its product applications.

[0003] The current research on the preparation process of metal soft magnetic powder cores mainly focuses on the powder coating process. The coating layer design of soft magnetic powder mainly includes: organic coating, inorganic coating, organic-inorganic composite coating, and the preparation method can be achieved by chemical method and physical method. Among them, organic-inorganic composite coating has attracted much attention because it balances the shortcomings of a single coating layer, but most preparation processes are relatively complicated, especially inorganic nano-metal oxides usually use chemical methods to obtain a relatively uniform coating layer. Although the mechanical and physical stirring method is simple to operate, it has poor uniform dispersion and is not conducive to obtaining magnetic powder cores with excellent performance.

[0004] For nanocrystalline soft magnetic strips with high Fe content, the existing magnetic powder core preparation process is generally: strip embrittlement → strip coarse crushing → ball milling / air flow milling (preparation of nanocrystalline powder) → inorganic coating → organic coating → pressing and forming → heat treatment. When nano metal oxide is used as the inorganic coating material, conventional mechanical stirring is usually used for inorganic coating and subsequent organic binder coating to achieve efficient preparation of coated powder. There is a high probability that nano oxides will agglomerate between particles, and there is also the problem of uneven inorganic coating layer. Both of these points will lead to increased loss of nanocrystalline soft magnetic powder cores. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a low-loss high-iron nanocrystalline soft magnetic powder core and a preparation method thereof.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core comprises the following steps:

[0008] (1) keeping an amorphous ribbon having an iron content of more than 80 wt% under vacuum conditions at 350 to 450° C. for 40 to 70 minutes, and crushing it to obtain a pretreated amorphous ribbon (coarsely crushed strip);

[0009] (2) mixing the pretreated amorphous ribbon and the inorganic coating material and then ball milling them, and sieving them after the ball milling to obtain inorganic coated soft magnetic powders with different particle size distributions;

[0010] (3) adding an organic binder and a lubricant to the inorganic coated soft magnetic powder, fully mixing, granulating, and sieving to obtain organic-inorganic coated soft magnetic powder particles;

[0011] (4) After pressing and heat treating the organic-inorganic coated soft magnetic powder particles, a low-loss high-iron nanocrystalline soft magnetic powder core is obtained.

[0012] Preferably, according to the present invention, in step (1), the amorphous ribbon is a FeSiBCuNb amorphous ribbon having an iron content of 80-86 wt%.

[0013] Further preferably, the Fe content of the FeSiBCuNb amorphous ribbon is 80-86wt%, the Si content is 5-10wt%, the B content is 2-6wt%, the Cu content is 1wt%, and the Nb content is 3wt%.

[0014] According to the preferred embodiment of the present invention, in step (2), the inorganic coating material is Fe 3 O 4 、Al 2 O 3 、SiO 2One or more of the following; particle size distribution is D50<30nm, D90<50nm.

[0015] Preferably, according to the present invention, in step (2), the mass ratio of the pretreated amorphous ribbon to the inorganic coating material is 100:(1-4).

[0016] Preferably, in step (2), the ball milling is carried out in a planetary ball mill, and the ball milling parameters are: ball milling speed 200-300 r / min, ball to material ratio (8-12): 1, and ball milling time 3-5 h.

[0017] Further preferably, the ball milling parameters are: ball milling speed 260r / min, ball to material ratio 10:1, and ball milling time 4h.

[0018] Preferably, according to the present invention, in step (2), the particle size distribution of the inorganic coated soft magnetic powder is: D10 is 18-23 μm, D50 is 55-65 μm, and D90 is 110-130 μm.

[0019] Preferably according to the present invention, in step (3), the organic bonding material is epoxy resin or silicone resin; and the lubricant is zinc stearate or barium stearate.

[0020] Preferably, according to the present invention, in step (3), the mass ratio of the inorganic coated soft magnetic powder, the organic binding material and the lubricant is 100:(1-4):(0.1-1).

[0021] Preferably, in step (4), the pressing pressure is 1300-1500 MPa; and the heat treatment refers to keeping the temperature at 450-550° C. under vacuum conditions for 40-70 min.

[0022] The present invention also provides a low-loss high-iron nanocrystalline soft magnetic powder core prepared by the above method.

[0023] Anything not described in detail in the present invention can be carried out according to the prior art.

[0024] Technical features and beneficial effects of the present invention:

[0025] 1. The present invention uses FeSiBCuNb amorphous ribbons with an iron content of 80-86wt% as raw materials to prepare high-iron nanocrystalline soft magnetic powder cores, simplifies the preparation process, combines the inorganic coating process with the ball milling process of the pre-treated amorphous ribbons, and realizes the coating of the nanocrystalline powder by inorganic nano-oxides during the ball milling process, omits the separate inorganic coating process of the nanocrystalline finished powder, shortens the process of the preparation method, and simplifies the preparation process.

[0026] 2. Compared with the coating method of directly subjecting the nanocrystalline finished powder to composite mechanical physical stirring of inorganic coating materials and organic binders, the preparation method provided by the present invention has a more uniform distribution of inorganic coating materials, which effectively solves the problem of uneven coating layer of magnetic powder core. The prepared nanocrystalline soft magnetic powder core has higher effective magnetic permeability and lower loss.

[0027] 3. Compared with the process of chemically coating nano-oxides, the preparation method provided by the present invention simplifies the process, greatly shortens the process flow of preparing magnetic powder cores from flaky powders, and effectively solves the problem of complex and time-consuming inorganic coating process for magnetic powder cores.

[0028] 4. The low-loss high-iron nanocrystalline soft magnetic powder core prepared by the present invention has a uniform distribution of inorganic coating materials. Under the current molding and heat treatment conditions, the loss at 20mT and 500kHz can reach a minimum of 230.6mW / cm 3 , 20mT, the loss at 1MHz can reach as low as 658.5mW / cm 3 This shows that the preparation method of the present invention not only simplifies the preparation process, but also further reduces the loss of the high-iron nanocrystalline soft magnetic powder core. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 1 is the XRD spectrum of the original strip, embrittled strip and magnetic powder core in Example 1.

[0030] Figure 2 The SEM images of the ball-milled powders of Comparative Example 1 (left picture) and Example 1 (right picture) are shown. DETAILED DESCRIPTION

[0031] The present invention is further described below by specific examples and drawings, but the scope of the present invention is not limited. The raw materials used in the examples are all conventional raw materials, and the equipment used is all conventional equipment, which can be purchased from the market.

[0032] The FeSiBCuNb amorphous ribbons used in Examples 1 to 4 and Comparative Examples 1 to 3 have an Fe content of 85.2 wt %, an Si content of 8.5 wt %, a B content of 2.3 wt %, a Cu content of 1 wt %, and a Nb content of 3 wt %.

[0033] The FeSiBCuNb amorphous ribbon used in Example 5 has an Fe content of 82.3wt%, an Si content of 9.4wt%, a B content of 4.3wt%, a Cu content of 1wt%, and a Nb content of 3wt%.

[0034] Example 1

[0035] A method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core comprises the following steps:

[0036] (1) A FeSiBCuNb amorphous ribbon (original ribbon) with an iron content of 85.2 wt% was kept at 400° C. under vacuum conditions for 60 min to obtain a brittle FeSiBCuNb amorphous ribbon (brittle ribbon); and a pre-crushed FeSiBCuNb amorphous ribbon (coarsely crushed ribbon) was obtained after pre-crushing it using a crusher;

[0037] (2) Pre-treated FeSiBCuNb amorphous ribbon and inorganic nano-Fe 3 O 4 The powders were mixed and placed in a planetary ball mill for 4 hours at a ball milling speed of 260 r / min and a ball-to-material ratio of 10:1 to obtain inorganic coated soft magnetic powders with different particle size distributions; the inorganic coated soft magnetic powders with different particle size distributions were sieved to obtain inorganic coated soft magnetic powders with D10 of 20.3 μm, D50 of 63.4 μm, and D90 of 116.2 μm, respectively;

[0038] Wherein, the pre-treated FeSiBCuNb amorphous ribbon and inorganic nano-Fe 3 O 4 The mass ratio of the powder is 100:2.5; the inorganic nano-Fe 3 O 4 The D50 of the powder is 27.5 nm;

[0039] (3) adding silicone resin and zinc stearate to the inorganic coated soft magnetic powder, mixing thoroughly and evenly, passing through a 60-mesh sieve, and granulating to obtain organic-inorganic coated soft magnetic particles;

[0040] The mass ratio of the inorganic coated soft magnetic powder, silicone resin and zinc stearate is 100:3:0.5:

[0041] (4) The organic-inorganic coated soft magnetic particles are pressed into a magnetic powder core under a pressure of 1400 MPa; the dimensions of the magnetic powder core are an outer diameter of 25.5 mm, an inner diameter of 16.0 mm, and a height of 5 mm; the pressed magnetic powder core is kept at 500°C under vacuum for 60 minutes to obtain a low-loss high-iron nanocrystalline soft magnetic powder core.

[0042] The XRD patterns of the original strip, embrittled strip, and low-loss high-iron nanocrystalline soft magnetic powder core of this embodiment are shown in FIG. Figure 1 shown.

[0043] Depend on Figure 1 It can be seen that the original strips and the embrittled strips have no obvious crystal diffraction peaks, which are amorphous structures, while the magnetic powder core after heat treatment has significant crystal diffraction peaks, which are analyzed to be α-Fe(Si) nanocrystalline phases, and the average grain size is estimated to be about 13.2nm by fitting. This indicates that the crystallization process of the nanocrystalline powder described in this embodiment occurs during the stress relief heat treatment stage.

[0044] Example 2

[0045] A method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core, the specific steps are the same as those described in Example 1, except that step (2) is: pre-treating FeSiBCuNb amorphous ribbon and inorganic nano-Fe 3 O 4 The powders were mixed and placed in a planetary ball mill for 4 hours at a ball milling speed of 260 r / min and a ball-to-material ratio of 10:1 to obtain inorganic coated soft magnetic powders of different particle sizes; the inorganic coated soft magnetic powders of different particle sizes were sieved to obtain inorganic coated soft magnetic powders with D10 of 21.3 μm, D50 of 62.4 μm, and D90 of 118.2 μm;

[0046] Wherein, the pre-treated FeSiBCuNb amorphous ribbon and inorganic nano-Fe 3 O 4 The mass ratio of the powder is 100:1.5; the inorganic nano-Fe 3 O 4 The D50 of the powder was 27.5 nm.

[0047] Example 3

[0048] A method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core, the specific steps are the same as those described in Example 1, except that step (2) is: pre-treating FeSiBCuNb amorphous ribbon and inorganic nano-Al 2 O 3 The powders were mixed and placed in a planetary ball mill for 4 hours at a ball milling speed of 260 r / min and a ball-to-material ratio of 10:1 to obtain inorganic coated soft magnetic powders of different particle sizes; the inorganic coated soft magnetic powders of different particle sizes were sieved to obtain inorganic coated soft magnetic powders with D10 of 19.8 μm, D50 of 64.1 μm, and D90 of 115.7 μm;

[0049] Wherein, the pre-treated FeSiBCuNb amorphous thin strip and inorganic nano-Al 2 O 3 The mass ratio of the powder is 100:2.5; the inorganic nano Al 2 O 3 The D50 of the powder was 25.5 nm.

[0050] Example 4

[0051] A method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core, the specific steps are the same as those described in Example 1, except that step (2) is: pre-treating FeSiBCuNb amorphous ribbon and inorganic nano-SiO 2The powders were mixed and placed in a planetary ball mill for 4 hours at a ball milling speed of 260 r / min and a ball-to-material ratio of 10:1 to obtain inorganic coated soft magnetic powders of different particle sizes; the inorganic coated soft magnetic powders of different particle sizes were sieved to obtain inorganic coated soft magnetic powders with D10 of 22.0 μm, D50 of 61.8 μm, and D90 of 124.3 μm;

[0052] Wherein, the pre-treated FeSiBCuNb amorphous ribbon and inorganic nano-SiO 2 The mass ratio of the powder is 100:2.5; the inorganic nano-SiO 2 The D50 of the powder was 26.1 nm.

[0053] Example 5

[0054] A method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core, the specific steps are the same as those described in Example 1, except that step (1) is: a FeSiBCuNb amorphous ribbon (original ribbon) with an iron content of 82.3wt% is kept at 400°C under vacuum conditions for 60 minutes to obtain a brittle FeSiBCuNb amorphous ribbon (brittle ribbon); and a pre-crushing treatment is performed on the amorphous ribbon using a crusher to obtain a pre-treated FeSiBCuNb amorphous ribbon (coarsely crushed ribbon).

[0055] Step (2) is: pre-treating FeSiBCuNb amorphous ribbon and inorganic nano-Fe 3 O 4 The powders were mixed and placed in a planetary ball mill, and ball milled for 4 hours at a ball mill speed of 260 r / min and a ball-to-material ratio of 10:1 to obtain inorganic coated soft magnetic powders with different particle size distributions; the inorganic coated soft magnetic powders with different particle size distributions were sieved to obtain inorganic coated soft magnetic powders with D10 of 22.3 μm, D50 of 60.4 μm, and D90 of 115.2 μm.

[0056] Comparative Example 1

[0057] A method for preparing a high-iron nanocrystalline soft magnetic powder core comprises the following steps:

[0058] (1) A FeSiBCuNb amorphous ribbon (original ribbon) with an iron content of 85.2 wt% was kept at 400° C. under vacuum conditions for 60 min to obtain a brittle FeSiBCuNb amorphous ribbon (brittle ribbon); and a pre-crushed FeSiBCuNb amorphous ribbon (coarsely crushed ribbon) was obtained after pre-crushing it using a crusher;

[0059] (2) placing the pretreated FeSiBCuNb amorphous ribbon in a planetary ball mill and milling it for 4 h at a ball milling speed of 260 r / min and a ball-to-material ratio of 10:1 to obtain a soft magnetic powder; sieving the soft magnetic powder to obtain a soft magnetic powder with a D10 of 20.8 μm, a D50 of 62.4 μm, and a D90 of 118.2 μm;

[0060] (3) Adding inorganic nano-Fe to the soft magnetic powder 3 O 4 The powder is stirred and mixed to obtain an inorganic coated soft magnetic powder; wherein the soft magnetic powder and the inorganic nano-Fe 3 O 4 The mass ratio of the powder is 100:2.5; the inorganic nano-Fe 3 O 4 The D50 of the powder is 27.5 nm;

[0061] (4) adding silicone resin and zinc stearate to the inorganic coated soft magnetic powder, mixing them thoroughly and evenly, passing them through a 60-mesh sieve, and granulating them to obtain organic-inorganic coated soft magnetic particles;

[0062] The mass ratio of the inorganic coated soft magnetic powder, silicone resin and zinc stearate is 100:3:0.5:

[0063] (5) The organic-inorganic coated soft magnetic particles are pressed into a magnetic powder core under a pressure of 1400 MPa; the dimensions of the magnetic powder core are an outer diameter of 25.5 mm, an inner diameter of 16.0 mm, and a height of 5 mm; the pressed magnetic powder core is kept at 500°C under vacuum for 60 minutes to obtain a high-iron nanocrystalline soft magnetic powder core.

[0064] Comparative Example 2

[0065] A method for preparing a high-iron nanocrystalline soft magnetic powder core, the specific steps are the same as those described in Comparative Example 1, except that in step (3), the soft magnetic powder and the inorganic nano-Fe 3 O 4 The mass ratio of the powder is 100:1.5; the inorganic nano-Fe 3 O 4 The D50 of the powder was 27.5 nm.

[0066] Comparative Example 3

[0067] A method for preparing a high-iron nanocrystalline soft magnetic powder core, the specific steps are the same as those described in Comparative Example 1, except that step (3) is not performed and the soft magnetic powder is directly organically coated.

[0068] Test example

[0069] 1. The SEM images of the soft magnetic powder obtained in step (2) of the comparative example 1 and the inorganic coated soft magnetic powder obtained in step (2) of the embodiment 1 are as follows: Figure 2 As shown, the left figure is comparative example 1 and the right figure is embodiment 1.

[0070] Depend on Figure 2 It can be seen that after nano-Fe 3 O 4 A large number of tiny particles are evenly distributed on the surface of the powder particles after ball milling, which indicates that the nano-Fe 3 O 4 The powder particles are evenly attached to the surface of the nanocrystalline soft magnetic powder, which is one of the fundamental reasons why the magnetic powder core maintains a high level of effective magnetic permeability while having lower losses.

[0071] 2. The magnetic properties of the low-loss high-iron nanocrystalline soft magnetic powder cores prepared in Examples 1 to 6 and the high-iron nanocrystalline soft magnetic powder cores prepared in Comparative Examples 1 to 2 were tested. The results are shown in Table 1.

[0072] The magnetic property detection method is: the magnetic permeability of the high-speed iron nanocrystalline soft magnetic powder core is tested at 1V voltage and 1MHz using the LCR-8210 digital bridge, and 35 turns of 0.5mm enameled wire are used for winding. The DC bias of the high-speed iron nanocrystalline soft magnetic powder core is measured by LCR plus bias DC power supply (TH1778A) at 1V, 1MHz, and 35 turns of winding. The loss of the high-speed iron nanocrystalline soft magnetic powder core is tested using the soft magnetic AC measuring instrument (MAST-3000SA) produced by Hunan Lianzhong, with 15 turns of primary winding and 15 turns of secondary winding.

[0073] Table 1. Properties of soft magnetic powder cores of Examples 1 to 6 and Comparative Examples 1 to 3

[0074]

[0075] From the results in Table 1, it can be seen that, compared with Comparative Example 1, Examples 1, 3 and 4 all achieved lower losses after adding 2.5wt% of inorganic nano-oxide, and Examples 1, 3 and 4 did not perform a separate inorganic coating material mixing step, thus having a shorter process flow. 3 O 4 After that, lower loss can still be obtained, while the effective magnetic permeability is maintained at a high level. Compared with comparative example 3, examples 1 to 5 all add inorganic nano-oxide coating layers to form organic-inorganic composite coatings, and the loss of the magnetic powder core is significantly reduced, which can achieve a reduction of about 47%, while the effective magnetic permeability can still be maintained at a high level.

[0076] Finally, it should be noted that for those skilled in the art, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification or equivalent replacement of the technical solution of the present invention should fall within the protection scope of the claims attached to the present invention.

Claims

1. A method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core, characterized in that: The steps include: (1) keeping an amorphous ribbon having an iron content of more than 80 wt% under vacuum conditions at 350 to 450° C. for 40 to 70 minutes, and crushing the ribbon to obtain a pretreated amorphous ribbon; (2) mixing the pretreated amorphous ribbon and the inorganic coating material and then ball milling them, and sieving them after the ball milling to obtain inorganic coated soft magnetic powders with different particle size distributions; (3) adding an organic binder and a lubricant to the inorganic coated soft magnetic powder, fully mixing, granulating, and sieving to obtain organic-inorganic coated soft magnetic powder particles; (4) After pressing and heat treating the organic-inorganic coated soft magnetic powder particles, a low-loss high-iron nanocrystalline soft magnetic powder core is obtained.

2. The method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core according to claim 1, characterized in that: In step (1), the amorphous ribbon is a FeSiBCuNb amorphous ribbon having an iron content of 80 to 86 wt%.

3. The method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core according to claim 2, characterized in that: The FeSiBCuNb amorphous ribbon has an Fe content of 80-86wt%, a Si content of 5-10wt%, a B content of 2-6wt%, a Cu content of 1wt% and a Nb content of 3wt%.

4. The method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core according to claim 1, characterized in that: In step (2), the inorganic coating material is one or more of Fe3O4, Al2O3, SiO2; and the particle size distribution is D50<30nm, D90<50nm.

5. The method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core according to claim 1, characterized in that: In step (2), the mass ratio of the pretreated amorphous ribbon to the inorganic coating material is 100:(1-4).

6. The method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core according to claim 1, characterized in that: In step (2), the ball milling is carried out in a planetary ball mill, and the ball milling parameters are: ball milling speed 200-300 r / min, ball to material ratio (8-12): 1, and ball milling time 3-5 h; Further preferably, the ball milling parameters are: ball milling speed 260r / min, ball to material ratio 10:1, and ball milling time 4h.

7. The method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core according to claim 1, characterized in that: In step (2), the particle size distribution of the inorganic coated soft magnetic powder is: D10 is 18-23 μm, D50 is 55-65 μm, and D90 is 110-130 μm.

8. The method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core according to claim 1, characterized in that: In step (3), the organic bonding material is epoxy resin or silicone resin; the lubricant is zinc stearate or barium stearate; and the mass ratio of the inorganic coated soft magnetic powder, the organic bonding material and the lubricant is 100:(1-4):(0.1-1).

9. The method for preparing a low-loss high-iron nanocrystalline soft magnetic powder core according to claim 1, characterized in that: In step (4), the pressing pressure is 1300-1500 MPa; the heat treatment refers to keeping warm at 450-550° C. under vacuum conditions for 40-70 minutes.

10. A low-loss high-iron nanocrystalline soft magnetic powder core, characterized in that: It is prepared according to the method according to any one of claims 1 to 9.

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