JP2010236021A - Soft magnetic powder, soft magnetic material and method for producing the material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide soft magnetic powder the magnetic properties and yield of which are effectively improved and to provide a soft magnetic material and a method for producing the soft magnetic material. <P>SOLUTION: A boron-containing insulated film is formed on the surface of the soft magnetic powder. The insulated film-formed soft magnetic powder is subjected to compression molding to obtain a molding. The molding is heat-treated to remove the strain thereof and form another insulated film consisting of boron nitride on the surface of the molding. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention suitably produces a soft magnetic powder containing iron and oxygen and having an insulating coating formed on the surface, a soft magnetic material formed from such a soft magnetic powder, and such a soft magnetic material. The present invention relates to a method, and more particularly to improvement of an insulating coating.

  Soft magnetic materials are used for electromagnetic parts such as motors and transformers. FIG. 4 is a conventional method for producing a soft magnetic material, and shows a schematic configuration of a product in each step. In FIGS. 4A and 4B, only one particle of soft magnetic powder is shown for convenience. In the conventional manufacturing method, an insulating coating 102 is formed on the surface of the soft magnetic powder 101 containing iron shown in FIG. 4 (A) as shown in FIG. 4 (B), and then in FIG. 4 (C). As shown, the soft magnetic powder 101 is compression-molded to obtain a molded body 103. As shown in FIG. 5A, the molded body 103 is obtained by compression-molding the soft magnetic powder 101 with an upper mold D1 and a lower mold D2.

  When the molded body 103 is obtained, the molded body 103 is then heat-treated to remove distortion generated during compression molding. As described above, the soft magnetic material in which the surface of the soft magnetic powder is subjected to the insulation coating process is manufactured. The insulating film 102 is formed in order to improve the magnetic characteristics of the electromagnetic component. Specifically, the insulating coating 102 suppresses the generation of eddy currents when an alternating magnetic field passes and increases the efficiency of the electromagnetic component.

  In general, in a method for producing a soft magnetic material, it is desirable to perform the heat treatment at a high temperature in order to effectively remove strain. Therefore, as the material of the insulating coating 102, an inorganic material such as a metal oxide is used instead of a resin having poor fire resistance. Examples of such metal oxides include silicon oxide, aluminum oxide, magnesium oxide, and soft ferrite. Patent Document 1 proposes an oxide containing at least one selected from the group consisting of aluminum oxide, zirconium oxide and silicon oxide in order to optimize the electrical resistivity.

JP 2005-79511 A

  However, since inorganic insulating coatings such as metal oxides are hard and brittle, the following problems have occurred. That is, even if compression molding is performed, the density of the molded body is difficult to increase, and the magnetic properties per unit volume decrease. In addition, as shown in FIG. 5B, damage such as cracks (indicated by symbol C) is likely to occur in the insulating coating 102 during molding, and such damage increases eddy current loss and further increases the magnetic characteristics. descend. Further, since the strength of the molded body 103 is low, damage such as cracking is likely to occur in the post-molding process, and the yield decreases.

  Accordingly, an object of the present invention is to provide a soft magnetic powder, a soft magnetic material, and a method for producing a soft magnetic material, which can effectively improve magnetic characteristics and yield.

  The soft magnetic powder of the present invention contains iron and oxygen, and an insulating coating containing boron is formed on the surface.

  The insulating film containing boron according to the present invention is less dense and deformable than the conventional insulating film that is hard and brittle. For this reason, at the time of compression molding, the insulating coating is easily deformed following the molding and is easily compressed to a high density. Moreover, since damage such as cracks is unlikely to occur in the insulating coating, the compression-molded molded body exhibits high strength. Therefore, problems such as a decrease in magnetic characteristics per unit volume and an increase in eddy current loss are solved, and magnetic characteristics are improved and yield is also improved.

  In the soft magnetic powder of the present invention, the insulating coating includes boron nitride. In this embodiment, boron nitride has high thermal conductivity, so that heat generated by eddy current is easily dissipated, thereby further improving the magnetic characteristics.

  The soft magnetic powder of the present invention includes a form in which a metal film is formed inside the insulating film. In this embodiment, the metal film is made of a metal that produces a metal oxide having a standard free energy of absolute value larger than that of iron oxide. This is because oxygen in the soft magnetic powder is reduced when heat treatment is performed. This is a preferable form in that an oxide film with high insulating properties is easily formed and magnetic characteristics are improved.

  Next, the soft magnetic material of the present invention is formed by compression-molding the soft magnetic powder of the present invention. As described above, the insulating coating formed on the surface of the soft magnetic powder of the present invention has low density and high deformability. Therefore, the soft magnetic material of the present invention in which the soft magnetic powder is compression-molded has a high density. As a result, an increase in strength is achieved, and magnetic characteristics and yield are improved.

  The soft magnetic material of the present invention which is a compression molded body includes a form to be heat-treated. This heat treatment may be performed not only in the air but also in a nitrogen atmosphere or an ammonia atmosphere. When the soft magnetic material that is a compression-molded body is heat-treated, the reduction reaction of the boron compound in the insulating coating proceeds to form the insulating coating densely, thereby further improving the magnetic properties.

  Next, a method for producing the soft magnetic material of the present invention is a method for suitably producing the soft magnetic material of the present invention, wherein an insulating coating containing boron is formed on the surface of the soft magnetic powder containing iron and oxygen. A step of compression forming the soft magnetic powder having the insulating coating formed thereon to obtain a molded body, a heat treatment of the molded body to remove distortion of the molded body, and a surface of the molded body And a step of forming an insulating film made of boron nitride.

  The method for producing a soft magnetic material of the present invention includes a form in which a metal film is formed on the surface of the soft magnetic powder before the step of forming the insulating film. In this embodiment, it is a preferable embodiment that the metal film is made of a metal that generates a metal oxide whose absolute value of standard free energy of generation is larger than that of iron oxide, as described above.

  In the method for producing a soft magnetic material of the present invention, it is preferable that the insulating film forming step is performed using a solution obtained by dissolving at least one of boron or a boron compound in a nonpolar solvent or a polar solvent. Form. In this form, since boron or boron compound is solvated, boron or boron compound can be thinly and uniformly coated on the surface of soft magnetic powder. For this reason, the surface of the soft magnetic powder can be coated with boron or a boron compound easily and with as little usage as possible, and an increase in cost can be suppressed. In addition, since the coating is uniformly and reliably performed, the magnetic characteristics can be improved.

  The heat treatment in the method for producing a soft magnetic material of the present invention may be performed in a nitrogen atmosphere or an ammonia atmosphere in addition to the air.

  According to the present invention, since the insulating coating formed on the surface of the soft magnetic powder as a material contains boron, the insulating coating is low in density and rich in deformability. In this state, the strength is improved as the density is increased, so that the magnetic characteristics and the yield are improved.

It is a figure which shows typically the manufacturing method of the soft-magnetic material which concerns on 1st Embodiment of this invention. The state which compressed-molded the soft-magnetic powder in the manufacturing method which concerns on 1st Embodiment is shown, (A) is a sectional side view, (B) is an enlarged view of powder. It is a figure which shows typically the manufacturing method of the soft-magnetic material which concerns on 2nd Embodiment of this invention. It is a figure which shows the manufacturing method of the conventional soft magnetic material. The state which compressed and formed soft-magnetic powder in the manufacturing method of the conventional soft-magnetic material is shown, (A) is a sectional side view, (B) is an enlarged view of powder.

Embodiments according to the present invention will be described below with reference to the drawings.
[1] First Embodiment FIG. 1 shows a process of a soft magnetic material manufacturing method according to a first embodiment. In this method, first, a soft magnetic powder 1 shown in FIG. The soft magnetic powder 1 is a metal powder mainly containing iron and containing oxygen, and the composition is, for example, high purity Fe, Fe—N, Fe—Ni, Fe—Si, Fe—Co, Fe—Al—Si. Or a mixture thereof. An oxide film 11 is formed on the surface of the soft magnetic powder 1.

Next, as shown in FIG. 1 (B), the particulate material P made of boron, a boron-based compound, or a mixture of both is dissolved in a solvent S to solvate the particulate material P. The boron compound is not particularly limited, but B ₂ O ₃ , melamine borate (C ₃ N ₆ H ₆ .2H ₃ BO ₃ ), a borazine derivative (borazine [B ₃ N ₃ H ₆ ] and at least one hydrogen of the borazine) Organic compounds having atoms substituted with substituents), alkali borides, boron trichloride (BCl ₃ ), and the like.

  The solvent S is not particularly limited, and examples thereof include water in which boron or a boron compound is dissolved, warm water, ethylene glycol, and ethanol. In this case, after the particulate material P is dissolved in a nonpolar solvent, the nonpolar solvent may be mixed with a highly volatile polar solvent. The mixing method of the particulate material P to the solvent S is not particularly limited, and various mixing methods such as a container rotating method, a mechanical stirring method, and a fluid stirring method are applicable.

  Next, as shown in FIG. 1 (C), the solvent S in which the particulate material P is dissolved to form a boron solvent is uniformly applied to the surface of the soft magnetic powder 1, and is further dried to soft magnetic Boron is fixed to the surface of the powder 1. As a result, an insulating coating 2 containing boron is formed on the surface of the soft magnetic powder 1, that is, on the surface of the oxide film 11. In the following description, the surface of the soft magnetic powder 2 refers to the surface of the oxide film 11.

  In the insulating coating 2, boron in the solvent S is first deposited in the form of nuclei on the surface of the soft magnetic powder 1, and as precipitation proceeds, the entire surface of the soft magnetic powder 1 is covered with boron. The insulating coating 2 is formed. By using the solvent S (boron solvent) having a low viscosity, the insulating coating 2 is thinly and uniformly formed on the surface of the soft magnetic powder 1.

  Although the formation method of the insulating film 2 is not specifically limited, For example, ultrasonic irradiation, an air current spray method, barrel mixing, a hybridizer etc. are mentioned. The thickness of the insulating coating 2 is not particularly limited, but is preferably about 1 nm to 10 μm. If the film thickness of the insulating coating 2 is less than 1 nm, the film thickness is too thin to obtain an insulating effect, and if it exceeds 10 μm, the magnetic permeability is greatly reduced, so the practicality is lost.

  Next, as shown in FIG. 1D, the soft magnetic powder 1 having the insulating coating 2 formed on the surface thereof is compression molded in a mold (not shown) to obtain a molded body 3 (compression molded body). The molding pressure is not particularly limited, but is preferably about 100 MPa to 2500 MPa. When the molding pressure is less than 100 MPa, the density of the molded body 3 is not increased and the magnetic characteristics are not improved. On the other hand, when the molding pressure exceeds 2500 MPa, the life of the mold is shortened, resulting in an increase in cost and a decrease in productivity, which is not practical. The temperature at the time of molding is not particularly limited, but it may be performed at normal temperature or a warm temperature. Further, a lubricant during compression molding is used as necessary.

  In such compression molding, since the insulating coating 2 on the surface of the soft magnetic powder 1 contains boron or a boron compound and has high density and high deformability, it corresponds to plastic deformation of the soft magnetic powder 1. It can follow well. Thereby, as shown to FIG. 2 (A), the density of the molded object 3 obtained by compression molding can be made high. In addition, as shown in FIG. 2B, it is possible to prevent the insulating coating 2 from being damaged such as cracks.

  Next, as shown in FIG. 1E, the molded body 3 is heat-treated to obtain a final soft magnetic material. The molded body 3 is subjected to heat treatment to remove distortion generated during compression molding. The atmosphere of the heat treatment may be in the air, but may be performed in a vacuum or an atmospheric gas such as argon, nitrogen, ammonia, hydrogen. By performing the heat treatment, the boron compound reacts with the atmospheric gas or is reduced by a thermal decomposition reaction, and the insulating coating 2 is densely formed on the surface of the soft magnetic powder 1 by this reduction reaction. In addition, a reaction may occur between the insulating coatings 2 and the insulating coatings 2 may be coupled to each other. In order to sufficiently proceed such a reduction reaction, it is effective to contain a reducing agent or a reduction catalyst in the insulating coating 2 before the heat treatment.

In the insulating film 2, for example, boron nitride generated by performing a heat treatment in nitrogen gas is a highly preferable insulating film having excellent heat resistance. An example of the reduction reaction in that case is shown in the following formula. N ₂ is an atmospheric gas (nitrogen gas), and BN is boron nitride that forms an insulating film. The molecular structure of boron nitride includes hexagonal crystal, cubic crystal, zinc blende, and nanotube, but is not limited. Furthermore, w (wurtzite type) -BN, BN (compound containing amorphous etc.), BCN, BC2N, BC3N, BCN (compound containing amorphous etc.) etc. are mentioned.

(1) Fe ₂ O ₃ + 3B → Fe + FeB + B ₂ O ₃
FeB + (1/2) N ₂ → Fe + BN
(2) B ₂ O ₃ + 3C + N ₂ → 2BN + 3CO

  The temperature during the heat treatment is not particularly limited, but if it is less than 400 ° C., it is not possible to sufficiently remove the strain generated during molding, and in addition, the formation reaction of boron nitride is difficult to proceed. Preferred. In addition, the atmospheric pressure during the heat treatment is not particularly limited, but when a strong insulating coating is required, it can be considered that the pressure is increased to 100 MPa or more. Also, the above-described compression molding can be performed at a heat treatment temperature, and a soft magnetic material can be obtained by hot pressing.

A soft magnetic material molded into a predetermined shape is obtained by the above manufacturing method.
The obtained soft magnetic material is low in density and rich in deformability compared to the conventional hard insulating and hard brittle insulating film since the insulating film 2 contains boron. For this reason, when the compression molding is performed, the insulating coating 2 is easily deformed following the molding and is compression molded at a high density. In addition, since damage such as cracks is unlikely to occur in the insulating coating 2, the compression molded body 3 exhibits high strength. Therefore, problems such as a decrease in magnetic characteristics per unit volume and an increase in eddy current loss are solved, and magnetic characteristics are improved and yield is also improved.

  Further, when the insulating coating 2 is boron nitride, the heat generated by the eddy current is easily radiated due to the characteristic of boron nitride that the thermal conductivity is high, so that the magnetic characteristics can be further improved.

  Further, when the insulating coating 2 is formed on the surface of the soft magnetic powder 1, the particulate material P is made into a solvent to have a low viscosity, and this is applied to the surface of the soft magnetic powder 1. For this reason, the surface of the soft magnetic powder 1 can be thinly and uniformly coated with boron or a boron compound. As a result, the surface of the soft magnetic powder can be coated with boron or a boron compound easily and with as little usage as possible, and an increase in cost can be suppressed. In addition, since the coating is uniformly and reliably performed, the magnetic characteristics can be improved. Further, since there is no need for resistance heating or an electron beam, there is an advantage that the manufacturing method is simplified.

[2] Second Embodiment FIG. 3 shows a process of a soft magnetic material manufacturing method according to a second embodiment. This method adds a step of forming a metal film on the surface of the soft magnetic powder 1 before the step of forming the insulating film 2 on the surface of the soft magnetic powder 1 in the manufacturing method of the first embodiment. .

  In the method of the second embodiment, the surface of the oxide film 11 of the soft magnetic powder 1 similar to the above shown in FIG. 3A is applied to at least one of a metal or a semimetal as shown in FIG. A metal film 12 is formed. The metal coating 12 referred to here is a coating made of metal or metalloid, and the material used is one whose absolute value of the standard free energy of formation of the oxide of the metal (or metalloid) is larger than that of iron oxide. . Specifically, Al (aluminum), Si (silicon), Mg (magnesium), Nb (niobium), Li (lithium), Gd (gadolinium), Y (yttrium), Pr (praseodymium), La (lanthanum), Nd (neodymium) etc. are mentioned. Note that these materials may be heat-treated in order to sufficiently contain oxygen.

  The method for forming the metal coating 12 is not particularly limited, and for example, a vapor deposition method such as sputtering, thermal evaporation or ion plating, a wet deposition method such as plating, a chemical vapor deposition method such as thermal decomposition or vapor reduction, A mechanical film formation method such as mechanofusion or hybridization is appropriately selected.

  Subsequently, as shown in FIG. 3B, the particulate material P made of boron or a boron compound is dissolved in the solvent S by the same method as in the first embodiment, and the particulate material P is solvated. Next, as shown in FIG. 3C, a solvent S, which is a boron solvent, is uniformly applied to the surface of the soft magnetic powder 1, that is, the surface of the oxide film 11, and further dried to form boron. Secure to. Thereby, the insulating coating 2 containing boron is formed on the surface of the metal coating 12. Next, as shown in FIG. 3D, the soft magnetic powder 1 having the metal coating 12 and the insulating coating 2 formed on the surface thereof is compression molded in a mold (not shown) in the same manner as in the first embodiment. A molded body 3 (compression molded body) is obtained.

  At the time of compression molding, the metal coating 12 has high ductility, and the insulating coating 2 is also highly deformable as described above, so that the metal coating 12 and the insulating coating 2 follow the plastic deformation of the soft magnetic powder 1. be able to. As a result, the molded body 3 has a high density, and the metal coating 12 and the insulating coating 2 are less susceptible to damage such as cracks. Therefore, effects such as improvement in magnetic properties accompanying high strength and improvement in yield are obtained. It is done.

  Next, as shown in FIG. 3E, similarly to the first embodiment, the molded body 3 is heat-treated to remove distortion, and the metal film 12 is oxidized to form a metal oxide film 13. The metal oxide film 13 is generated when the metal coating 12 reacts with oxygen in the iron oxide constituting the oxide film 11.

  In the said 2nd Embodiment, the effect (an improvement of a magnetic characteristic and a yield) after compression molding can be acquired similarly to the manufacturing method of 1st Embodiment. The metal oxide film 13 formed by oxidizing the metal film 12 by heat-treating the molded body 3 has high strength, while the insulating film 2 remains. Accordingly, it is possible to improve insulation and increase strength without impairing moldability. As a result, magnetic characteristics and yield are greatly improved.

Examples of the present invention and comparative examples other than the present invention are presented below to demonstrate the effects of the present invention.
[Example 1]
Boron oxide was completely dissolved in warm water around 80 to 100 ° C., then melamine was added to the solution and completely dissolved with stirring and ultrasonic irradiation to prepare a melamine borate solution. Subsequently, the melamine borate solution and the water atomized pure iron powder were temporarily mixed in a beaker, and then subjected to ultrasonic irradiation under conditions of 40 kHz / 250 W / 60 minutes while stirring, and then cooled. At this time, aggregates of melamine borate crystals are formed on the surface of the water atomized pure iron powder. Next, after filtration, drying was performed while irradiating with ultrasonic waves under a vacuum of 5 kPa or less under conditions of 40 kHz / 50 W / 60 minutes to obtain a soft magnetic powder having a boron-containing insulating coating formed on the surface. Next, this powder was compression-molded using a ring-shaped mold having an outer diameter of 40 mm and an inner diameter of 25 mm at a molding pressure of 600 MPa to produce a ring-shaped molded body.

[Example 2]
The molded object produced in Example 1 was heat-treated in a nitrogen-ammonia atmosphere. The heat treatment was performed in two stages, the first stage being performed at 500 ° C. for 2 hours, and the second stage being performed at 1000 ° C. for 30 minutes. The heat treatment in the first stage forms a BN film, and the heat treatment in the second stage is performed to remove distortion generated in the molded body. The reason why the heat treatment is performed in two stages as described above is that if the heat treatment is performed at a high temperature at a time, the BN film may be incomplete and insulation may not be ensured. Thus, heat treatment in two stages is preferable.

[Comparative Example 1]
The same water atomized pure iron powder as that used in Example 1 was compression molded at a molding pressure of 600 MPa using the same mold as that used in Example 1 to produce a ring-shaped molded body.

[Comparative Example 2]
The molded body obtained in Comparative Example 1 was subjected to the same heat treatment as in Example 2.

[Comparative Example 3]
Soft magnetic powder in which stearate soap: 0.5 wt% and epoxy resin: 1.5 wt% are mixed with the same water atomized pure iron powder used in Example 1, and a resin film is formed as an insulating film on the surface Got. Next, this powder was compression-molded at a molding pressure of 600 MPa using the same mold as that used in Example 1, and the obtained molded body was subjected to heat treatment heated to 130 ° C. in the atmosphere.

[Comparative Example 4]
A ferrite film was formed as an insulating coating on the same water atomized pure iron powder used in Example 1. Next, this powder was compression-molded at a molding pressure of 600 MPa using the same mold as that used in Example 1 to produce a ring-shaped molded body.

[Comparative Example 5]
The molded body obtained in Comparative Example 4 was subjected to a heat treatment that was heated to 500 ° C. in the air.

  For the molded bodies of Examples 1 and 2 and Comparative Examples 1 to 5, permeability, iron loss, and strength were measured as density, electrical resistivity, and magnetic properties, respectively. These measurement methods are as follows.

・ Density Weight and dimensions were measured and calculated as relative density from the following formula.
Relative density (%) = (molded body density / true density) × 100
-Electrical resistivity Measured by the 4-terminal method.
-Permeability and iron loss Using a 0.6 mm magnet wire, the primary side is wound 100 turns and the secondary side is 30 turns, and the magnetic permeability and iron loss are measured by a BH analyzer (SY-8232 made by Iwatatsu). Was measured.
-Strength Determined by a three-point bending strength test according to JIS R 1601. In the test, the span was 30 mm and the crosshead speed was 0.1 mm / min.

  The measurement results are shown in Table 1 and Table 2, respectively, divided into Example 1, Comparative Examples 1, 3, and 4 and Example 2, Comparative Examples 2, 3, and 5. In Table 1, the result of Comparative Example 1 is set as a reference (= 1), in Table 2, the result of Comparative Example 2 is set as a reference (= 1), and other results are expressed as ratios to these references.

  According to Table 1, it is suggested that the density of Example 1 is almost the same as that of Comparative Example 1 without an insulating film, and therefore the moldability is not lowered. When the molded body of Example 1 was actually observed, no cracks or minute chips were confirmed, and the moldability was also good. Moreover, the electrical resistivity of Example 1 is 5.39 times that of Comparative Example 1, and it is recognized that the insulating property is extremely high. Therefore, it can be seen that Example 1 has a high density and good moldability and insulation.

  Further, according to Table 1, in Example 1, the iron loss was reduced by 16% compared to Comparative Example 1. Further, Example 1 has higher magnetic permeability and reduced iron loss as compared with Comparative Example 3 and Comparative Example 4. From these, it can be seen that Example 1 has high magnetic properties, and such a soft magnetic material is suitable for high frequency applications.

  Next, according to Table 2, the electrical resistivity of Example 2 was 27.3 times that of Comparative Example 2 without an insulating coating. Thereby, it can be seen that the insulation of Example 2 is very good. Further, in Example 2, the eddy current loss is greatly reduced to 83% as compared with Comparative Example 2. Thereby, it is estimated that the dielectric breakdown by heat processing does not generate | occur | produce in the insulating film containing a boron compound.

  Furthermore, in Example 2, the iron loss was significantly reduced as compared with Example 1 that was not heat-treated, and was comparable to Comparative Example 2. In addition, the iron loss of Example 2 is reduced by 83% compared to Comparative Example 2. Further, Example 2 has higher magnetic permeability and reduced iron loss as compared with Comparative Example 3 and Comparative Example 5. Therefore, Example 2 has high magnetic properties, and such a soft magnetic material is suitable for high magnetic properties.

DESCRIPTION OF SYMBOLS 1 ... Soft magnetic powder 2 ... Insulating film 3 ... Molded body (compression molded body, soft magnetic material)
DESCRIPTION OF SYMBOLS 11 ... Oxide film 12 ... Metal coating 13 ... Metal oxide film P ... Particulate material S ... Solvent

Claims (12)

  A soft magnetic powder characterized in that it contains iron and oxygen, and an insulating coating containing boron is formed on the surface.   The soft magnetic powder according to claim 1, wherein the insulating coating is made of boron nitride.   The soft magnetic powder according to claim 1, wherein a metal film is formed inside the insulating film.   A soft magnetic material obtained by compression-molding the soft magnetic powder according to claim 1.   The soft magnetic material according to claim 4, wherein the soft magnetic material is heat-treated.   The soft magnetic material according to claim 5, wherein the heat treatment is performed in a nitrogen atmosphere or an ammonia atmosphere.   4. The soft magnetic powder according to claim 3, wherein the metal coating is made of a metal that generates a metal oxide having an absolute value of standard generation free energy larger than that of iron oxide. 5. Forming an insulating coating containing boron on the surface of the soft magnetic powder containing iron and oxygen;
A step of compression-molding the soft magnetic powder having the insulating coating formed thereon to obtain a molded body;
Heat-treating the molded body to remove distortion of the molded body, and forming an insulating film made of boron nitride on the surface of the molded body;
A method for producing a soft magnetic material, comprising:   9. The method for producing a soft magnetic material according to claim 8, wherein a metal film is formed on the surface of the soft magnetic powder before the step of forming the insulating film.   10. The soft magnetic material according to claim 8, wherein the step of forming the insulating film is performed using a solution obtained by dissolving at least one of boron or a boron compound in a nonpolar solvent or a polar solvent. Manufacturing method.   11. The method of manufacturing a soft magnetic material according to claim 9, wherein the metal coating is made of a metal that generates a metal oxide having an absolute value of standard generation free energy larger than that of iron oxide.   The method for producing a soft magnetic material according to claim 8, wherein the heat treatment is performed in a nitrogen atmosphere or an ammonia atmosphere.

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