Soft magnetic metal particles, soft magnetic metal powder, magnetic cores, magnetic components, and electronic devices

Abstract

The present invention provides soft magnetic metal particles that enable the production of a magnetic core with reduced core loss while maintaining a suitable relative permeability. [Solution] A soft magnetic metal particle comprising metal particles and a film coating the metal particles. The coating film contains at least an oxide of X1, an oxide of X2, and Mg. X1 is Fe, Co, or Ni. X2 is P, Si, B, Na, Al, Ca, Bi, Ba, or Zn. The coating film includes a first coating portion in contact with the metal particles and a second coating portion in contact with the first coating portion. The first coating portion is the portion where the atomic concentration of X1 is equal to or greater than the atomic concentration of X2. The second coating portion is the portion where the atomic concentration of X1 is less than the atomic concentration of X2. The maximum atomic concentration of Mg is contained in the coating film, and the atomic concentration of Mg at the maximum point is [Mg], and the atomic concentration of X1 at the maximum point is [X1], such that [Mg] / [X1] is between 0.05 and 2.00.

Description

[Technical Field]

[0001] The present invention relates to soft magnetic metal particles, soft magnetic metal powder, magnetic cores, magnetic components, and electronic devices. [Background technology]

[0002] Patent Document 1 describes an invention relating to an Fe-based soft magnetic alloy. This Fe-based soft magnetic alloy has a higher saturation magnetization compared to ferrite and exhibits excellent DC superposition characteristics. Therefore, it is suitable for miniaturizing magnetic cores and electronic components.

[0003] Patent Document 2 describes an invention relating to magnetic powder, etc. Generally, when powder using soft magnetic alloy is used as a magnetic core, core loss tends to occur, but in this magnetic powder, core loss is reduced by arranging an insulating layer on top of the magnetic metal particles. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 3342767 [Patent Document 2] Japanese Patent Publication No. 2017-34228 [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention aims to provide soft magnetic metal particles that can produce a magnetic core with reduced core loss while suitably maintaining relative permeability. [Means for solving the problem]

[0006] To achieve the above objective, the soft magnetic metal particles of the present invention are Soft magnetic metal particles comprising metal particles and a coating film covering the metal particles, The coating film comprises at least an oxide of X1, an oxide of X2, and Mg. The coating film includes a first coating portion that is in contact with the metal particles, and a second coating portion that is in contact with the first coating portion. The first coating portion is the part where the atomic concentration of X1 is equal to or greater than the atomic concentration of X2, and the second coating portion is the part where the atomic concentration of X1 is less than the atomic concentration of X2. X1 is the element that is present in the first coating portion in the most abundant amount on an atomic basis among Fe, Co, and Ni. X2 is the element that is most abundant in the second coating portion on an atomic basis from among P, Si, B, Na, Al, Ca, Bi, Ba, and Zn. The maximum atomic concentration of Mg is contained within the coating film, and the atomic concentration of Mg at the maximum point is [Mg], and the atomic concentration of Fe at the maximum point is [Fe]. The [Mg] / [Fe] ratio is between 0.05 and 2.00.

[0007] X1 may be the element that is most abundant in the first coating portion on an atomic basis among Fe, Co, and Ni, and X2 may be the element that is most abundant in the second coating portion on an atomic basis among P, Si, B, Na, Al, Ca, Bi, Ba, and Zn.

[0008] X1 may be Fe, Fe may be the element that is most abundant in the first coating portion on an atomic basis among Fe, Co, and Ni.

[0009] The soft magnetic metal powder of the present invention includes the soft magnetic metal particles described above.

[0010] The magnetic core of the present invention contains the above-mentioned soft magnetic metal particles.

[0011] The magnetic component of the present invention includes the above-mentioned soft magnetic metal particles.

[0012] The electronic device of the present invention includes the above-mentioned soft magnetic metal particles. [Brief explanation of the drawing]

[0013] [Figure 1] It is a graph showing the concentration distribution of each element near the surface of the soft magnetic metal particles. [Figure 2] It is a graph showing the concentration distribution of some elements for a part of FIG. 1. [Figure 3] It is a STEM image near the surface of the soft magnetic metal particles. [Figure 4] It is an Fe mapping image near the surface of the soft magnetic metal particles. [Figure 5] It is a Co mapping image near the surface of the soft magnetic metal particles. [Figure 6] It is an O mapping image near the surface of the soft magnetic metal particles. [Figure 7] It is a P mapping image near the surface of the soft magnetic metal particles. [Figure 8] It is a Si mapping image near the surface of the soft magnetic metal particles. [Figure 9] It is a Mg mapping image near the surface of the soft magnetic metal particles. [Figure 10] It is a Pt mapping image near the surface of the soft magnetic metal particles.

Mode for Carrying Out the Invention

[0014] Hereinafter, soft magnetic metal particles and the like according to embodiments of the present invention will be described.

[0015] The soft magnetic metal particles according to the present embodiment include metal particles 11 and a coating film 13 that coats the metal particles 11.

[0016] There is no particular limitation on the composition of the metal particles 11. For example, the metal particles 11 may contain one or more elements selected from Fe, Co, Ni, P, Si, B, Na, Al, Ca, Bi, Ba, and Zn. Further, it may contain one or more elements selected from C, Nb, Hf, Zr, Cu, Ta, Mo, W, Ti, and V, which are generally elements contained in soft magnetic metal particles.

[0017] There are no particular restrictions on the total content of Fe, Co, and Ni in the metal particles 11. For example, it may be between 70 at% and 100 at%. There are no particular restrictions on the total content of P, Si, B, Na, Al, Ca, Bi, Ba, and Zn in the metal particles 11. For example, it may be between 0 at% and 30 at%. There are no particular restrictions on the total content of C, Nb, Hf, Zr, Cu, Ta, Mo, W, Ti, and V in the metal particles 11. For example, it may be between 0 at% and 10 at%. In other words, elements other than Fe, Co, and Ni do not have to be included in the metal particles 11 and may be included only in the coating film 13. Also, since the proportion of metal particles 11 in the total soft magnetic metal particles is usually significantly larger than the proportion of coating film 13, it can be estimated that the composition of metal particles 11 and the composition of soft magnetic metal particles are substantially the same.

[0018] Furthermore, the metal particles 11 may contain elements other than Fe, Co, Ni, P, Si, B, Na, Al, Ca, Bi, Ba, Zn, C, Nb, Hf, Zr, Cu, Ta, Mo, W, Ti, and V, to the extent that they do not significantly impair the magnetic properties of the soft magnetic metal particles. For example, the total content of elements other than Fe, Co, Ni, P, Si, B, Na, Al, Ca, Bi, Ba, Zn, C, Nb, Hf, Zr, Cu, Ta, Mo, W, Ti, and V in the metal particles 11 may be 5% by mass or less.

[0019] The coating film 13 contains at least an oxide of X1, an oxide of X2, and Mg.

[0020] The coating film 13 includes a first coating portion that is in contact with the metal particles 11, and a second coating portion that is in contact with the first coating portion. The first coating portion is the portion where the atomic concentration of X1 is equal to or greater than the atomic concentration of X2. The second coating portion is the portion where the atomic concentration of X1 is less than the atomic concentration of X2.

[0021] X1 is Fe, Co, or Ni. X2 is P, Si, B, Na, Al, Ca, Bi, Ba, or Zn. In other words, one element is selected for X1 from a large number of candidates. One element is selected for X2 from a large number of candidates.

[0022] X1 may be the element that is most abundant in the first coating layer on a atomic basis among Fe, Co, and Ni. X2 may be the element that is most abundant in the second coating layer on a atomic basis among P, Si, B, Na, Al, Ca, Bi, Ba, and Zn.

[0023] The coating film 13 includes a first coating portion that is in contact with the metal particles 11, and a second coating portion that is in contact with the first coating portion. The first coating portion is the portion where the atomic concentration of X1 is equal to or greater than the atomic concentration of X2. The second coating portion is the portion where the atomic concentration of X1 is less than the atomic concentration of X2.

[0024] X1 and X2 are selected such that both the first and second coating portions are included in the coating film 13. The lower limit of the thickness of the first coating portion and the lower limit of the thickness of the second coating portion are 0.5 nm.

[0025] Furthermore, the maximum atomic concentration of Mg is contained within the coating film 13. The atomic concentration of Mg at the maximum point is [Mg], and the atomic concentration of X1 at the maximum point is [X1], where [Mg] / [X1] is between 0.05 and 2.00.

[0026] A magnetic core containing soft magnetic metal particles having the above configuration exhibits reduced core loss while maintaining a similar relative permeability compared to a magnetic core containing soft magnetic metal particles having an equivalent configuration except that the coating film 13 does not contain Mg.

[0027] The [Mg] / [X1] ratio changes depending on the type of X1. X1 and X2 are selected such that both the first and second coating portions are included in the coating film 13, and the [Mg] / [X1] ratio is between 0.05 and 2.00. In other words, regardless of how X1 and X2 are selected, soft magnetic metal particles in which the coating film 13 includes only one of the first and second coating portions, or in which the [Mg] / [X1] ratio is less than 0.05 or greater than 2.00, are not soft magnetic metal particles of this embodiment.

[0028] X1 may be Fe. Fe may be the element that is most abundant in the first coating on an atomic basis.

[0029] The following explanation, using diagrams, describes the case where the metal particles 11 contain Fe, Co, P, and Si, X1 is Fe, X2 is P, Fe is the element with the highest atomic content in the first coating, and P is the element with the highest atomic content in the second coating.

[0030] Figure 3 shows a STEM image obtained by observing the vicinity of the surface of soft magnetic metal particles according to this embodiment. Note that the STEM image in Figure 3 is a backscattered electron image. The soft magnetic metal particles have a Pt film 15 to suppress charge-up during STEM observation. If the soft magnetic metal particles do not have a Pt film, they will be affected by charge-up during STEM observation, but it is still possible to observe the soft magnetic metal particles using STEM.

[0031] Figures 4 to 10 show mapping images of each element produced by STEM-EDS within the same range as in Figure 3. Figure 1 shows a graph illustrating the concentration regions of each element along a straight line perpendicular to the surface of the soft magnetic metal particle, moving from the outside to the inside of the soft magnetic metal particle.

[0032] From Figures 1, 3, and 4, the atomic concentration of Fe is highest in metal particle 11 and decreases towards the outside of the soft magnetic metal particles.

[0033] Figures 1, 3, and 5 show that the atomic concentration of Co is highest in the metal particles 11. It also appears that the Pt film 15 contains Co. However, in reality, the Pt film 15 contains virtually no Co. This is because EDS detects a portion of the Pt as Co. As shown in Figures 3, 5, and 10, the Pt film 15 appears to have a high atomic concentration of Co even though it does not actually contain any. If the influence of the Pt film 15 is excluded, the atomic concentration of Co is considered to be highest in the metal particles 11 and decreases towards the outer edges of the soft magnetic metal particles.

[0034] Figures 1, 3, and 6-9 show that the atomic concentrations of O, P, Si, and Mg are all highest in the coating film 13, and decrease in both the metal particles 11 and the area outside the soft magnetic metal particles compared to the coating film 13. From Figures 1 and 6, it appears that O is present in the metal particles 11 and the Pt film 15 at approximately 5 at%, but in reality, the detection is based on the O present in the background.

[0035] Figure 2 shows a graph that is an enlarged portion of Figure 1, with only Fe, P, and Mg indicated. In Figure 2, the dotted line indicates the region where the atomic concentrations of Fe and P are the same, and this is the boundary between the first and second coating regions. From Figure 3, the boundary between the first and second coating regions cannot be confirmed even using STEM images. The boundary between the first and second coating regions can be confirmed by measuring the concentration distribution of each element using STEM-EDS analysis.

[0036] In Figure 2, the maximum atomic concentration of Mg is located slightly to the left of the dotted line. The atomic concentration of Mg at this maximum is [Mg], and the atomic concentration of X1 at this maximum is [X1].

[0037] The location of the maximum atomic concentration point of Mg is not particularly limited as long as it is inside the coating film 13. The distance of the maximum atomic concentration point of Mg from the surface of the metal particle 11 may be 0.5 nm or more. The distance of the maximum atomic concentration point of Mg from the surface of the coating film 13 may be 0.5 nm or more.

[0038] There are no particular restrictions on [Mg], but it may be between 0.1 at% and 49.0 at% and between 2.0 at% and 20.0 at%. Having [Mg] within the above range makes it easier to reduce core loss while maintaining a similar relative permeability.

[0039] When X1 is Fe, there are no particular restrictions on [X1], but it may be between 0.1 at% and 52.4 at%.

[0040] There are no particular restrictions on the thickness of the coating film 13. For example, it may be between 1 nm and 200 nm, between 1 nm and 100 nm, between 5 nm and 100 nm, or between 10 nm and 100 nm.

[0041] There are no particular restrictions on the particle size of the soft magnetic metal particles according to this embodiment. For example, it may be 1 μm or more and 50 μm or less.

[0042] There are no particular limitations on the microstructure of the soft magnetic metal particles according to this embodiment. The microstructure of the soft magnetic metal particles may be amorphous, a nanocrystalline structure containing nanocrystals, or a crystalline structure.

[0043] Soft magnetic metal particles containing nanocrystals can sometimes be obtained by heating soft magnetic alloy particles containing amorphous material at 400°C to 700°C.

[0044] Here, "amorphous structure" refers to a material state in which there is almost no long-range order like in crystals, and the amorphousness rate X is 85% or more. Amorphous structures include structures consisting only of amorphous material and structures consisting of heteroamorphous material. A heteroamorphous structure refers to a structure in which initial microcrystals exist within the amorphous material. In heteroamorphous structures, the average crystallite size of the initial microcrystals is preferably between 0.1 nm and 10 nm.

[0045] Furthermore, "nanocrystalline structure" refers to a material state having nanocrystals in which the amorphousness rate X is less than 85% and the average crystallite diameter is between 0.5 nm and 30 nm. Preferably, the maximum diameter of the crystallites in the nanocrystalline structure is 100 nm or less.

[0046] On the other hand, crystalline metallic magnetic materials have a crystalline structure, which is different from amorphous or nanocrystalline structures. A "crystalline structure" refers to a material state in which the amorphousness rate X is less than 85% and the average crystallite diameter is 100 nm or more.

[0047] Note that the amorphization rate X (unit: %) is such that the proportion of crystals is P C , the proportion of amorphous is P A , and X = (P A / (P C + P A )) × 100. When calculating the amorphization rate X using XRD, the crystalline scattering integrated intensity Ic measured using XRD can be regarded as P c , and the amorphous scattering integrated intensity Ia measured using XRD can be regarded as P A . When calculating the amorphization rate X using EBSD or an electron microscope, the area ratio of the crystalline part in the grain can be regarded as P C , and the area ratio of the amorphous part in the grain can be regarded as P A .

[0048] Examples of the material of the soft magnetic alloy particles with an amorphous microstructure include Fe-Co-B-P-Si-Cr alloy, Fe-Co-B-P-Si alloy, Fe-B-Si-C-Cr alloy, Fe-Si-B alloy, and Fe-B-Si-C alloy.

[0049] Examples of the material of the soft magnetic alloy particles with a nanocrystalline microstructure include Fe-Si-B-Nb-Cu alloy, Fe-B-P-Si-Cu alloy, Fe-B-P-Si-Nb-Cr alloy, Fe-Co-B-P-Si-Cu alloy, and Fe-Co-B-P-Si-Nb alloy.

[0050] Examples of the material of the soft magnetic alloy particles with a crystalline microstructure include pure Fe metal, Fe-Co alloy, Fe-Si alloy, Fe-Ni alloy, Fe-Co-Si alloy, Fe-Si-Cr alloy, Fe-Co-Si-Cr alloy, Fe-Co-V alloy, Fe-Si-Al alloy, Fe-Si-Al-Ni alloy, and Fe-Co-Si-Al alloy.

[0051] The soft magnetic metal powder according to this embodiment contains the soft magnetic metal particles described above. There are no particular restrictions on the content ratio of the soft magnetic metal particles. For example, it may be 5 wt% to 100 wt%, 20 wt% to 100 wt%, or 50 wt% to 100 wt%. Furthermore, the content ratio of the soft magnetic metal particles may be 5% to 100% when converted to a volume ratio.

[0052] The soft magnetic metal powder according to this embodiment may be mixed with well-known soft magnetic metal powders. Examples of well-known soft magnetic metal powders include Fe powder, Co powder, Fe-Co alloy powder, Fe-Si alloy powder, Fe-Ni alloy powder, Fe-Co-BP-Si alloy powder, Fe-B-Si-C-Cr alloy powder, Fe-Si-B-Nb-Cu alloy powder, Fe-BP-Si-Cu alloy powder, and Fe-BP-Si-Nb-Cr alloy powder. In particular, when a soft magnetic metal powder with a relatively small average particle size is mixed with the soft magnetic metal powder according to this embodiment, it becomes easier to improve the packing density of the magnetic core made using the soft magnetic metal powder. The soft magnetic metal particles contained in may have the above-mentioned coating film.

[0053] There are no particular restrictions on the average particle size (D50) of the soft magnetic metal powder according to this embodiment. For example, it may be 1 μm or more and 50 μm or less.

[0054] The magnetic core according to this embodiment includes the above-mentioned soft magnetic metal particles. By including the above-mentioned soft magnetic metal particles, core loss can be improved while suitably maintaining the relative permeability of the magnetic core.

[0055] The following describes a method for producing soft magnetic metal powder containing soft magnetic metal particles according to this embodiment.

[0056] The soft magnetic metal powder according to this embodiment can be produced, for example, by water atomization or gas atomization. The following describes a method for obtaining the soft magnetic metal powder according to this embodiment using gas atomization.

[0057] First, the raw materials for each element constituting the metal particles 11 contained in the soft magnetic metal powder are prepared and weighed to achieve the desired composition of the metal particles 11. Then, the raw materials for each element are dissolved to produce a master alloy. There are no particular limitations on the dissolution method. For example, the raw materials for each element may be dissolved by high-frequency heating in a chamber with a predetermined vacuum level.

[0058] Next, the master alloy is heated and melted to obtain molten metal. The temperature of the molten metal is adjusted according to the melting point of the alloy having the desired composition, and / or the melting points of the raw materials of each element mentioned above. For example, it may be set to 1200-1600°C.

[0059] Next, molten metal is ejected into a chamber to produce a powder. Specifically, molten metal is ejected from a discharge port towards the cooling section inside the chamber. At this time, high-pressure gas is injected towards the ejected molten metal. The injection of high-pressure gas causes the molten metal to break apart and scatter within the chamber, and the scattered molten metal collides with the cooling section (cooling water), causing it to rapidly cool and solidify, resulting in a soft magnetic metal powder containing metal particles 11. When using the water atomization method, water is injected instead of high-pressure gas.

[0060] There are no particular restrictions on the type of high-pressure gas. Examples include inert gases such as nitrogen, argon, and helium. Reducing gases such as ammonia decomposition gas may also be used.

[0061] There are no particular restrictions on the pressure of the injected high-pressure gas; it may be between 2.0 and 10.0 MPa. There are also no particular restrictions on the amount of molten metal injected; it may be between 0.5 and 16.0 kg / min. By controlling the ratio of the high-pressure gas pressure to the amount of molten metal injected, the particle size of the soft magnetic metal powder can be adjusted.

[0062] Furthermore, a magnesium-containing aqueous solution is sprayed onto the droplets of molten metal, which have been atomized by the injection of high-pressure gas. By spraying the magnesium-containing aqueous solution, a magnesium layer is formed on the surface of the droplets of molten metal. The higher the Mg concentration in the magnesium-containing aqueous solution, the higher the [Mg] value. Furthermore, the higher the oxygen concentration of the high-pressure gas used to break up the molten metal, the lower the [X1] value.

[0063] There are no particular restrictions on the type of magnesium-containing aqueous solution. For example, it may be an aqueous solution of magnesium chloride, an aqueous solution of magnesium hydroxide, or an aqueous solution of magnesium carbonate.

[0064] At this point, an oxide film containing magnesium is formed on the surface of the metal particles 11 obtained.

[0065] By adjusting the spraying height of the magnesium-containing aqueous solution, the position of the Mg maximum can be changed. Specifically, the closer the spraying position of the magnesium-containing aqueous solution is to the injection position of the high-pressure gas and the further it is from the cooling water, the closer the Mg maximum in the final soft magnetic metal particles tends to be to the metal particle 11. Conversely, the further the spraying position of the magnesium-containing aqueous solution is from the injection position of the high-pressure gas and the closer it is to the cooling water, the further the Mg maximum in the final soft magnetic metal particles tends to be to the metal particle 11.

[0066] In other words, by simultaneously controlling the Mg concentration in the magnesium-containing aqueous solution, the oxygen concentration of the high-pressure gas, and the spraying height of the magnesium-containing aqueous solution, the position of the Mg maximum point and the [Mg] / [X1] ratio can be controlled.

[0067] The particle size of the soft magnetic metal powder may be adjusted by classification.

[0068] Furthermore, by forming a coating film containing X2 on the powder obtained by cooling with cooling water, a coating film 13 is formed on the surface of the metal particles 11, and the soft magnetic metal powder according to this embodiment is obtained.

[0069] By changing the type and composition of the coating film, the composition of the second coating portion and the type of X2 can be changed in particular. That is, X1 is mainly an element derived from the master alloy, and X2 is mainly an element derived from the coating film formed at this stage. Furthermore, X1 may be contained in the coating film, and X2 may be contained in the master alloy.

[0070] There are no particular restrictions on the type of coating film formed at this stage. For example, it may be a coating containing inorganic materials. Examples of inorganic materials include phosphates, BN, SiO2, MgO, Al2O3, phosphate-based glass, silicate-based glass, borosilicate-based glass, and bismuth-based glass.

[0071] Phosphate-based glasses include P-Zn-Al-O glass and P-Zn-Al-RO glass (where R is one or more alkali metals). Silicate-based glasses include Si-O glass. Borosilicate-based glasses include Ba-Zn-B-Si-Al-O glass. Bismuth-based glasses include Bi-Zn-Al-O glass and Bi-Zn-B-Si-Al-O glass.

[0072] There are no particular restrictions on the method of forming the coating film. It may be formed by a well-known method selected according to the type of coating film. Examples of methods for forming the coating film include heat treatment, phosphate treatment, mechanical alloying, silane coupling treatment, and hydrothermal synthesis.

[0073] By forming a coating film on an oxide film containing Mg, Mg diffuses into the coating film. When preparing soft magnetic metal powder by gas atomization, the higher the height from which the aqueous solution containing Mg is sprayed, the more easily magnesium is incorporated into the oxide film. Therefore, Mg does not easily diffuse from the oxide film to the coating film. When preparing soft magnetic metal powder by gas atomization, the lower the height from which the aqueous solution containing Mg is sprayed, the more easily magnesium is located on the surface of the oxide film. Therefore, Mg diffuses easily from the oxide film to the coating film.

[0074] The following describes in more detail several methods for forming coating films.

[0075] When forming a coating film containing SiO2 (hereinafter sometimes referred to as an SiO2 film), a solution containing a silane coupling agent, which serves as a Si source, may be sprayed onto the powder. Alternatively, the powder may be impregnated with a solution containing a silane coupling agent, and then dried and / or heat-treated.

[0076] There are no particular restrictions on the type of silane coupling agent. Examples include tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), and hexyltrimethylsilane. Using TEOS is particularly preferred.

[0077] There are no particular restrictions on the type of solvent used in the solution containing the silane coupling agent. Examples include water, ethanol, acetone, and isopropyl alcohol. The thickness of the second coating can be controlled by controlling the concentration of the silane coupling agent in the solution, the spray volume per unit time, and the penetration treatment time. The higher the concentration of the silane coupling agent, the greater the spray volume per unit time, and the longer the penetration treatment time, the thicker the second coating becomes.

[0078] When forming a coating film containing phosphate (hereinafter sometimes referred to as a phosphate film), it can be formed by phosphate treatment. Specifically, first, a treatment solution is prepared by dissolving a phosphate containing additive elements, or phosphoric acid, in a solvent such as water or alcohol. Then, the powder is impregnated into the treatment solution or the treatment solution is sprayed onto the powder. After that, the powder is dried to form a phosphate film on the surface of the powder. Examples of additive elements include alkali metal elements, alkaline earth metal elements, Zn, and Al.

[0079] When forming coating films using various glass-based materials, these films can be formed by a mechanochemical method using a mechanofusion apparatus. Specifically, in the mechanochemical coating process, the powder to be coated and a powdered coating agent containing the constituent elements of the coating film are introduced into the rotating rotor of the mechanofusion apparatus, and the rotor is rotated. A press head is installed inside the rotating rotor. When the rotor rotates, the mixture of the powder to be coated and the coating agent is compressed in the gap between the inner wall of the rotor and the press head, generating frictional heat. This frictional heat softens the coating agent, and through compression, it adheres to the surface of the powder to be coated, forming an oxide glass coating film.

[0080] There are no particular limitations on the method for manufacturing the magnetic core according to this embodiment. The following describes the case where the magnetic core is a compacted magnetic core. Specifically, a method for obtaining the magnetic core by pressure molding will be described.

[0081] A resin compound is obtained by kneading the soft magnetic metal powder according to this embodiment with a resin. The resin compound may be granulated powder. At this time, soft magnetic metal powder other than the soft magnetic metal powder according to this embodiment, and / or non-magnetic powders may be added to the resin compound. Modifiers, preservatives, dispersants, etc. may also be added. Then, the resin compound is filled into a mold, pressure molded, and the resin is cured to obtain a magnetic core.

[0082] First, the soft magnetic metal powder and resin are mixed. Mixing with resin makes it easier to obtain a molded body with high strength through molding. There are no particular restrictions on the type of resin. Examples include phenolic resin and epoxy resin. There are no particular restrictions on the amount of resin added, but the total amount may be between 0.5 parts by mass and 5.0 parts by mass, based on a total mass of 100 parts by mass of the various magnetic materials.

[0083] A mixture of soft magnetic metal powder and resin is granulated to obtain granulated powder. There are no particular restrictions on the granulation method. For example, granulation may be carried out using a stirrer. There are no particular restrictions on the particle size of the granulated powder.

[0084] The resulting granulated powder is subjected to pressure molding to obtain a molded body. There are no particular restrictions on the molding pressure. For example, a surface pressure of 0.1 t / cm². 2 More than 20t / cm 2 The following is also possible: When using soft magnetic metal powder produced using an elliptical water flow atomizing device, the relative permeability μ can be increased with a smaller molding pressure compared to when using a conventional atomizing device.

[0085] Then, the resin contained in the molded body can be cured to obtain a magnetic core. There are no particular restrictions on the curing method, and heat treatment may be performed under conditions that can cure the resin used.

[0086] There are no particular restrictions on the applications of the magnetic core. For example, it can be suitably used as a magnetic core for inductors.

[0087] Furthermore, the magnetic cores and magnetic components using the above-mentioned magnetic cores can be suitably used in electronic devices.

[0088] In particular, the above-mentioned magnetic core is suitable for applications requiring miniaturization and low profile because it can easily maintain a favorable relative permeability while keeping core loss relatively low. For example, it can be suitably used in magnetic components such as inductors, transformers, and choke coils, as well as in electronic equipment that uses such magnetic components. [Examples]

[0089] The present invention will be specifically described below based on examples.

[0090] (Experimental Example 1) <Powder A> Various raw materials were weighed to obtain a soft magnetic metal composition of 57.4Fe-24.6Co-11.0B-3.0P-3.0Si-1.0Cr in atomic ratio, and the master alloy was prepared by melting them using high-frequency heating. Then, the weighed various raw materials were melted using high-frequency heating in a vacuum chamber to obtain the master alloy.

[0091] The prepared master alloy was heated and melted to a molten state of metal (molten metal) at 1200-1600°C. Then, soft magnetic metal powders with the alloy composition of each sample were prepared using the gas atomization method. Specifically, when the molten master alloy was discharged from the dropping molten metal outlet towards the cooling section (cooling water) in the chamber, high-pressure gas was injected towards the discharged dropping molten metal. The temperature of the molten metal was adjusted according to the melting point of each raw material. Argon gas was used as the high-pressure gas, and the oxygen concentration of the high-pressure gas is shown in each table.

[0092] Furthermore, magnesium chloride aqueous solutions containing Mg at the MgCl concentrations shown in each table were sprayed onto the finely atomized molten metal droplets using high-pressure gas injection. The spray positions for the magnesium chloride aqueous solution were set to upper, middle, and lower, starting from the molten metal discharge port. When the position of the Mg maximum in the final coating film was considered the boundary, the spray position was set to the middle; when the position of the Mg maximum in the final coating film was considered the first coating section, the spray position was set to the upper; and when the position of the Mg maximum in the final coating film was considered the first coating section, the spray position was set to the lower. The spray positions for the magnesium chloride aqueous solution were then set and sprayed so that the Mg maximum in the final coating film was at the positions shown in each table. The spray positions are shown in each table. Note that when the MgCl concentration was 0, deionized water was sprayed instead of magnesium chloride aqueous solution.

[0093] The molten metal, sprayed with a magnesium chloride aqueous solution, collides with the cooling section (cooling water), causing it to cool and solidify, resulting in powder A before coating.

[0094] For the gas atomization method, the pressure of the high-pressure gas was set to 5 MPa and the molten metal ejection rate was set to 6 kg / min. Powder A was screened and classified so that its average particle size was 25 μm.

[0095] ICP analysis confirmed that the composition of the master alloy and the composition of powder A were in general agreement. X-ray diffraction measurements were also performed on powder A, and the amorphousness rate X was calculated using the method described above. A structure consisting of amorphous material was considered to exist if the amorphousness rate X was 85% or higher. A structure consisting of nanocrystalline material was considered to exist if the amorphousness rate X was less than 85% and the average crystallite diameter was 100 nm or less. A structure consisting of crystals was considered to exist if the amorphousness rate X was less than 85% and the average crystallite diameter was greater than 100 nm. In Experimental Example 1, it was confirmed that all powders A had an amorphous structure. The average particle size was confirmed by bright-field XRD or STEM, and the average particle size was calculated.

[0096] In Experimental Example 1, pure iron powder with an average particle size of 0.8 μm was prepared as powder B.

[0097] Next, powder A was subjected to a coating film formation process using a mechanofusion apparatus (Hosokawa Micron Corporation: AMS-Lab) to form a P-Zn-Al-O oxide glass coating film on the surface of powder A. The thickness of the coating film was approximately 15 nm.

[0098] Next, powders A and B were mixed so that powder A made up 80 wt% and powder B made up 20 wt% to prepare a mixed powder. Then, a resin compound was obtained by kneading the mixed powder with epoxy resin. The amount of epoxy resin in the resin compound was set to 2.8 parts by weight per 100 parts by weight of mixed powder.

[0099] Next, a resin compound was filled into a mold and pressurized to obtain a toroidal molded body. The molding pressure at this time was 392 MPa. The obtained molded body was heat-treated at 180°C for 60 minutes to cure the epoxy resin and obtain a toroidal magnetic core with an outer diameter of 11 mm, an inner diameter of 6.5 mm, and a thickness of 2.5 mm.

[0100] Relative permeability was measured. First, polyurethane wire (UEW wire) was wound around a toroidal magnetic core. Then, the relative permeability of the magnetic core was measured using an LCR meter (Agilent Technologies: 4284A) at a measurement frequency of 1 MHz. Next, core loss was measured. Core loss was measured using a BH analyzer (Iwatsu Instruments: SY-8218). The magnetic flux density during core loss measurement was set to 10 mT and the measurement frequency to 3 MHz. For each example, the improvement rate of core loss and the decrease rate of relative permeability were calculated compared to the comparative example, which was conducted under the same conditions except that the oxygen concentration of the high-pressure gas was the same and deionized water was sprayed instead of magnesium chloride aqueous solution. The results are shown in the tables. A core loss improvement rate of 5.0% or more was considered good, 10.0% or more was considered particularly good, and 15.0% or more was considered even better. A decrease in relative permeability of less than 20.0% was considered good relative permeability, less than 10.0% was considered particularly good relative permeability, and less than 1.0% was considered even better relative permeability.

[0101] <Analysis of the coating film of powder A> A Pt film was applied to powder A after coating for STEM observation. Then, powder A and a thermosetting resin were mixed to form a mixture. Next, the mixture was molded, and after molding, the thermosetting resin was cured to obtain a molded body for coating film analysis. The molded body for coating film analysis was processed by ion milling to obtain a thin film. The cross-sections of 10 soft magnetic metal particles contained in the thin film were observed by STEM. Furthermore, the concentration distribution of each element was measured by measuring the concentration of each element along a direction perpendicular to the outermost surface of the soft magnetic metal particles using EDS. The spacing between measurement points in the concentration measurement was set to 0.5 nm. For the 10 soft magnetic metal particles, [Mg], [X1], and [Mg] / [X1] were calculated and averaged. Unless otherwise specified, Fe was selected as X1 and P as X2. Unless otherwise specified below, among Fe, Co, and Ni, Fe is the element with the highest atomic number content in the first coating layer. Furthermore, among P, Si, B, Na, Al, Ca, Bi, Ba, and Zn, P is the element with the highest atomic content in the second coating layer. The total content of Fe, Co, Ni, P, Si, B, Na, Al, Ca, Bi, Ba, Zn, and Mg at the point of maximum Mg concentration was set to 100 atomic percent, and [Mg], [X1], and [Mg] / [X1] were calculated. That is, the content of elements such as Pt and O was not considered when calculating the above concentrations. The results are shown in the respective tables.

[0102] For comparative examples where the average [Mg] / [X1] was less than 0.05 or greater than 2.00, it was confirmed that [Mg] / [X1] was less than 0.05 or greater than 2.00 for all soft magnetic metal particles for which [Mg] / [X1] was calculated. For comparative examples that do not contain Mg, there is no maximum point in the atomic concentration of Mg. Therefore, [X1] is inherently unknown. For convenience, it was assumed that [X1] is greater than 0 and [Mg] / [X1] is 0.

[0103] Of Fe, Co, and Ni, Fe was the element with the highest atomic content in the first coating layer, and of P, Si, B, Na, Al, Ca, Bi, Ba, and Zn, P was the element with the highest atomic content in the second coating layer.

[0104] The boundary between the first and second coating regions was defined as the region within 0.5 nm of the point where the atomic concentrations of X1 (Fe in Experimental Example 1) and X2 (P in Experimental Example 1) were equal. The researchers then examined which region—the first coating region excluding the boundary, the boundary region, or the second coating region excluding the boundary—had the maximum Mg concentration. The tables show the region where the Mg concentration was most frequently found among the 10 soft magnetic alloy particles. Unless otherwise specified, for all soft magnetic alloy particles, the distance from the surface of the metal particle to the point of maximum Mg atomic concentration was 0.5 nm or greater, and the distance from the surface of the coating film to the point of maximum Mg atomic concentration was also 0.5 nm or greater.

[0105] For samples 1-48, the coating thickness was 20 nm. X1 was Fe and X2 was P. Unless otherwise specified, the coating thickness was 20 nm for all subsequent samples.

[0106] [Table 1A]

[0107] [Table 1B]

[0108] [Table 1C]

[0109] Table 1A shows examples and comparative examples conducted under the same conditions except for varying the Mg concentration of the magnesium chloride aqueous solution, with the spray position of the magnesium chloride aqueous solution being the center. The higher the Mg concentration of the magnesium chloride aqueous solution, the higher the [Mg] / [X1] ratio tended to be. Each example where [Mg] / [X1] was within the specified range showed a favorable core loss improvement rate and relative permeability reduction rate. In contrast, sample number 2, where [Mg] / [X1] was too low, did not show sufficient improvement in core loss compared to sample number 1, which did not use magnesium chloride aqueous solution. Sample number 16, where [Mg] / [X1] was too high, showed a significant decrease in relative permeability compared to sample number 1, which did not use magnesium chloride aqueous solution.

[0110] Table 1B shows examples and comparative examples conducted under the same conditions except for changing the Mg concentration of the magnesium chloride aqueous solution, with the spray position of the magnesium chloride aqueous solution being set to the top. The higher the Mg concentration of the magnesium chloride aqueous solution, the higher the [Mg] / [X1] ratio tended to be. In each example where [Mg] / [X1] was within the specified range, the core loss improvement rate and relative permeability reduction rate were favorable. In contrast, sample number 18, where [Mg] / [X1] was too low, did not show sufficient improvement in core loss compared to sample number 17, which did not use magnesium chloride aqueous solution. Sample number 32, where [Mg] / [X1] was too high, showed a significant decrease in relative permeability compared to sample number 17, which did not use magnesium chloride aqueous solution.

[0111] Table 1C shows examples and comparative examples conducted under the same conditions except that the spray position of the magnesium chloride aqueous solution was set downwards and the Mg concentration of the magnesium chloride aqueous solution was varied. The higher the Mg concentration of the magnesium chloride aqueous solution, the higher the [Mg] / [X1] ratio tended to be. In each example where [Mg] / [X1] was within the specified range, the core loss improvement rate and relative permeability reduction rate were favorable. In contrast, sample number 34, where [Mg] / [X1] was too low, did not show sufficient improvement in core loss compared to sample number 33, which did not use magnesium chloride aqueous solution. Sample number 48, where [Mg] / [X1] was too high, showed a significant decrease in relative permeability compared to sample number 33, which did not use magnesium chloride aqueous solution.

[0112] Tables 1A to 1C show examples and comparative examples in which the spray position of the magnesium chloride aqueous solution was varied. The position where the Mg concentration is maximum (the position of the Mg concentration maxima) changed with the change in the spray position of the magnesium chloride aqueous solution, but similar trends were shown in each table for core loss and relative permeability.

[0113] (Experimental Example 2) Samples 49-121 were conducted in the same manner as the examples in Table 1A, except that the Mg concentration in the magnesium chloride aqueous solution and the oxygen concentration of the high-pressure gas used to break down the molten metal were varied. The results are shown in Tables 2A and 2B. In the tables below, core loss and relative permeability are omitted, and only the core loss improvement rate and relative permeability reduction rate are shown.

[0114] The core loss improvement rate and relative permeability reduction rate for each sample are the same as those for the comparative example, which was under identical conditions except that deionized water was used instead of magnesium chloride aqueous solution. Furthermore, in all the samples used in Experimental Example 2 and later, the magnesium chloride aqueous solution was sprayed in the middle, and the Mg maximum value was located at the boundary.

[0115] [Table 2A]

[0116] [Table 2B]

[0117] Tables 2A and 2B show that the higher the oxygen concentration in the high-pressure gas, the lower the [X1] tended to be, and the higher the MgCl concentration in the magnesium chloride aqueous solution, the higher the [Mg] tended to be.

[0118] In each example where [Mg] / [X1] was within the specified range, the core loss improvement rate and relative permeability reduction rate were favorable. In contrast, in each comparative example where [Mg] / [X1] was too small, the core loss was not sufficiently improved compared to the sample number that did not use magnesium chloride aqueous solution. Sample number 16, where [Mg] / [X1] was too large, showed a significant decrease in relative permeability compared to sample number 1, which did not use magnesium chloride aqueous solution.

[0119] (Experimental Example 3) Sample No. 122 was conducted under the same conditions as Sample No. 1, except that the oxygen concentration in the high-pressure gas was set to 13.0%. Furthermore, Sample No. 123 was conducted under the same conditions as Sample No. 122, except that the MgCl concentration was set to 69 g / L. In addition, for each of Sample No. 122 and 123, the composition of powder A was varied, and the concentration of the magnesium chloride aqueous solution and / or the oxygen concentration of the high-pressure gas were set appropriately, except that the conditions were the same. The results are shown in Tables 3A to 3B. The type of X1 is also indicated in each table. Note that the core loss for Sample No. 122 was 1151 kW / m 3 The relative permeability was 30.0. Sample number 123 had a core loss of 967 kW / m². 3 The relative permeability was 29.9.

[0120] In samples 126 and 127, among Fe, Co, and Ni, Co was the element with the highest atomic content in the first coating layer. In samples 155 and 156, among Fe, Co, and Ni, Ni was the element with the highest atomic content in the first coating layer.

[0121] [Table 3A]

[0122] [Table 3B]

[0123] Tables 3A and 3B show that even when the composition of powder A changes, the examples in which [Mg] / [X1] is within the predetermined range show improved core loss and favorable maintenance of magnetic permeability compared to the comparative example, which is substantially the same except that [Mg] / [X1] is outside the predetermined range.

[0124] (Experimental Example 4) For sample number 1 of Experimental Example 1, comparative examples of sample numbers 171, 182, 193, 204, and 215 were prepared under the same conditions except for the average particle size of powder A. Furthermore, for sample number 171, samples 172 to 181 were prepared under the same conditions except for changing the MgCl concentration in the magnesium chloride aqueous solution. For sample number 182, samples 183 to 192 were prepared under the same conditions except for changing the MgCl concentration in the magnesium chloride aqueous solution. For sample number 193, samples 194 to 203 were prepared under the same conditions except for changing the MgCl concentration in the magnesium chloride aqueous solution. For sample number 204, samples 205 to 214 were prepared under the same conditions except for changing the MgCl concentration in the magnesium chloride aqueous solution. For sample number 215, samples 216 to 225 were prepared under the same conditions except for changing the MgCl concentration in the magnesium chloride aqueous solution. The results are shown in Tables 4A and 4B.

[0125] [Table 4A]

[0126] [Table 4B]

[0127] Tables 4A and 4B show that even when the average particle size of powder A changes, the examples in which [Mg] / [X1] is within the predetermined range show improved core loss and favorable maintenance of magnetic permeability compared to the comparative example, which is substantially the same except that [Mg] / [X1] is outside the predetermined range.

[0128] (Experimental Example 5) For samples 122 and 123, the experiments were conducted under the same conditions except that the composition of powder B and the concentration of the magnesium chloride aqueous solution were changed. In all experimental examples from Experimental Example 5 onward, the composition of powder A was the same. The results are shown in Table 5.

[0129] [Table 5]

[0130] As shown in Table 5, even when the composition of powder B changed, the examples in which [Mg] / [X1] was within the predetermined range showed improved core loss and favorable maintenance of magnetic permeability compared to the comparative example, which was substantially the same except that [Mg] / [X1] was outside the predetermined range.

[0131] (Experimental Example 6) For samples 122 and 123, the experiment was conducted under the same conditions except that the average particle size of powder B was varied, and the concentration of the magnesium chloride aqueous solution was also varied. The results are shown in Table 6.

[0132] [Table 6]

[0133] As shown in Table 6, even when the average particle size of powder B changed, the examples in which [Mg] / [X1] was within the predetermined range showed improved core loss and favorable maintenance of magnetic permeability compared to the comparative example, which was substantially the same except that [Mg] / [X1] was outside the predetermined range.

[0134] (Experimental Example 7) The compositions of powders A and B were the same as in Experimental Example 1. However, the concentration of the magnesium chloride aqueous solution and the oxygen concentration during the preparation of powder A were changed as appropriate. Furthermore, powder C was prepared with an average particle size of 3.0 μm and the composition shown in Table 7. Powder C was not coated, similar to powder B. The mixing ratio of powders A, B, and C was 80:10:10 by weight. The results are shown in Table 7.

[0135] [Table 7]

[0136] As shown in Table 7, regardless of the composition of powder C, the examples in which the [Mg] / [X1] ratio was within the specified range showed improved core loss and favorable permeability compared to the comparative example, which was substantially the same except that the [Mg] / [X1] ratio was outside the specified range, even after adding powder C.

[0137] (Experimental Example 8) For samples 252 and 253 in Experimental Example 7, the experiment was conducted under the same conditions except that the average particle size of powder C was changed. The results are shown in Table 8.

[0138] [Table 8]

[0139] As shown in Table 8, even when the average particle size of powder C changed, the examples in which [Mg] / [X1] was within the predetermined range showed improved core loss and favorable maintenance of magnetic permeability compared to the comparative example, which was substantially the same except that [Mg] / [X1] was outside the predetermined range.

[0140] (Experimental Example 9) For samples 122 and 123, the experiments were conducted under the same conditions except that the thickness of the coating film of powder A obtained in the final product was varied, as well as the concentration of the magnesium chloride aqueous solution. Specifically, the thickness of the coating film of powder A was changed mainly by altering the thickness of the coating film formed by the coating film formation process. The coating film thickness and test results are shown in Table 9.

[0141] [Table 9]

[0142] Table 9 shows that even when the coating film thickness of powder A and the coating film thickness changed, the examples in which [Mg] / [X1] was within the predetermined range showed improved core loss and favorable maintenance of magnetic permeability compared to the comparative example, which was substantially the same except that [Mg] / [X1] was outside the predetermined range.

[0143] (Experimental Example 10) For samples 122 and 123, the same conditions were used except for the variation in the type of coating film of powder A. The types of coating films are shown in Table 10. When the type of coating film of powder A was a P-Zn-Al-Na-O oxide glass coating, a P-Zn-Al-Ca-O oxide glass coating, a Bi-Zn-B-Si-O oxide glass coating, or a Ba-Zn-B-Si-Al-O oxide glass coating, the procedure was the same as for samples 122 and 123. When the type of coating film of powder A was a phosphate coating, appropriate phosphate treatment was performed. When the type of coating film of powder A was an SiO2 coating, appropriate silane coupling treatment was performed. The results are shown in Table 10. The types of X2 are also shown in Table 10. In all examples, X2 was the element that was most abundant in the second coating layer on an atomic basis among P, Si, B, Na, Al, Ca, Bi, Ba, and Zn.

[0144] [Table 10]

[0145] As shown in Table 10, even when the type of coating film of powder A changed, the examples in which [Mg] / [X1] was within the predetermined range showed improved core loss and favorable maintenance of magnetic permeability compared to the comparative example, which was substantially the same except that [Mg] / [X1] was outside the predetermined range.

[0146] (Experimental Example 11) For samples 122 and 123, the experiment was conducted under the same conditions except that the mixing ratio of powder A and powder B was changed, and the concentration of the magnesium chloride aqueous solution was also changed. The results are shown in Table 11.

[0147] [Table 11]

[0148] As shown in Table 11, even when the mixing ratio of powder A and powder B changed, the examples in which [Mg] / [X1] was within the predetermined range showed improved core loss and favorable maintenance of magnetic permeability compared to the comparative example, which was substantially the same except that [Mg] / [X1] was outside the predetermined range.

[0149] (Experimental Example 12) For samples 252 and 253, the experiment was conducted under the same conditions except that the mixing ratios of powders A, B, and C were appropriately varied, as well as the concentration of the magnesium chloride aqueous solution. The results are shown in Table 12.

[0150] [Table 12]

[0151] As shown in Table 12, even when the mixing ratio of powders A to C changed, the examples in which [Mg] / [X1] was within the predetermined range showed improved core loss and favorable maintenance of magnetic permeability compared to the comparative example, which was substantially the same except that [Mg] / [X1] was outside the predetermined range.

[0152] (Experimental Example 13) Various raw materials were weighed to achieve a soft magnetic metal composition of 72.7Fe-10.8B-11.6Si-2.7C-2.2Cr in atomic ratio, i.e., the soft magnetic metal composition of powder C of sample number 252. These materials were then melted by high-frequency heating to prepare a master alloy. The weighed raw materials were then melted by high-frequency heating in a vacuum chamber to obtain the master alloy.

[0153] The prepared master alloy was heated and melted to a molten state of metal (molten metal) at 1200-1600°C. Then, soft magnetic metal powders with the alloy composition of each sample were prepared using the gas atomization method. Specifically, when the molten master alloy was discharged from the dropping molten metal outlet towards the cooling section (cooling water) in the chamber, high-pressure gas was injected towards the discharged dropping molten metal. The temperature of the molten metal was adjusted according to the melting point of each raw material. Argon gas was used as the high-pressure gas, and the oxygen concentration of the high-pressure gas is shown in each table.

[0154] Furthermore, a magnesium chloride aqueous solution containing Mg at the MgCl concentrations shown in each table was sprayed onto the finely atomized molten metal droplets using high-pressure gas injection. When the MgCl concentration was 0, deionized water was sprayed instead of the magnesium chloride aqueous solution.

[0155] When the molten metal, which had been sprayed with a magnesium chloride aqueous solution, collided with the cooling section (cooling water), it cooled and solidified into powder C.

[0156] For the gas atomization method, the pressure of the high-pressure gas was set to 8 MPa and the molten metal ejection rate to 0.6 kg / min. Powder C was air-classified so that its average particle size was 3.0 μm.

[0157] ICP analysis confirmed that the composition of the master alloy and the composition of powder C were generally consistent. X-ray diffraction measurements were also performed on powder C, and the amorphous ratio X was calculated using the method described above. A structure consisting of amorphous material was considered to exist if the amorphous ratio X was 85% or higher. A structure consisting of nanocrystalline material was considered to exist if the amorphous ratio X was less than 85% and the average crystallite diameter was 100 nm or less. A structure consisting of crystalline material was considered to exist if the amorphous ratio X was less than 85% and the average crystallite diameter was greater than 100 nm. In Experimental Example 13, it was confirmed that all powder C had an amorphous structure. The average particle size was confirmed by bright-field XRD or STEM, and the average particle size was calculated.

[0158] A Pt film was coated onto powder C for STEM observation. Then, a mixture was formed by mixing powder C with a thermosetting resin. Next, the mixture was molded, and after molding, the thermosetting resin was cured to obtain a molded body for coating film analysis. The molded body for coating film analysis was processed by ion milling to obtain a thin film. The cross-sections of 10 soft magnetic metal particles contained in the thin film were observed using STEM. Furthermore, the concentration distribution of each element was measured by measuring the concentration of each element along a direction perpendicular to the outermost surface of the soft magnetic metal particles using EDS. The spacing between measurement points in the concentration measurement was set to 0.5 nm. For the 10 soft magnetic metal particles, [Mg], [X1], and [Mg] / [X1] were calculated and averaged. Unless otherwise specified, Fe was selected as X1 and P as X2. Unless otherwise specified below, among Fe, Co, and Ni, Fe is the element with the highest atomic number content in the first coating layer. Furthermore, among P, Si, B, Na, Al, Ca, Bi, Ba, and Zn, P is the element with the highest atomic content in the second coating layer. The total content of Fe, Co, Ni, P, Si, B, Na, Al, Ca, Bi, Ba, Zn, and Mg at the point of maximum Mg concentration was set to 100 atomic percent, and [Mg], [X1], and [Mg] / [X1] were calculated. That is, the content of elements such as Pt and O was not considered when calculating the above concentrations. The results are shown in the respective tables.

[0159] For comparative examples where the average [Mg] / [X1] was less than 0.05 or greater than 2.00, it was confirmed that [Mg] / [X1] was less than 0.05 or greater than 2.00 for all soft magnetic metal particles for which [Mg] / [X1] was calculated. For comparative examples that do not contain Mg, there is no maximum point in the atomic concentration of Mg. Therefore, [X1] is inherently unknown. For convenience, it was assumed that [X1] is greater than 0 and [Mg] / [X1] is 0.

[0160] Of Fe, Co, and Ni, Fe was the element with the highest atomic content in the first coating layer, and of P, Si, B, Na, Al, Ca, Bi, Ba, and Zn, P was the element with the highest atomic content in the second coating layer.

[0161] The boundary between the first and second coating regions was defined as the region within 0.5 nm of the point where the atomic concentrations of X1 (Fe in Experimental Example 1) and X2 (P in Experimental Example 1) were equal. The researchers then examined which region—the first coating region excluding the boundary, the boundary region, or the second coating region excluding the boundary—had the maximum Mg concentration. The tables show the region where the Mg concentration was most frequently found among the 10 soft magnetic alloy particles. Unless otherwise specified, for all soft magnetic alloy particles, the distance from the surface of the metal particle to the point of maximum Mg atomic concentration was 0.5 nm or greater, and the distance from the surface of the coating film to the point of maximum Mg atomic concentration was also 0.5 nm or greater.

[0162] Powders A and B were the same as those used in Sample No. 1 (Comparative Example) of Experimental Example 1. The mixing ratio of powders A to C was varied as appropriate. The results are shown in Table 13.

[0163] [Table 13]

[0164] As shown in Table 13, unlike Experimental Examples 1 to 12, each example in which powder C included a first coating portion and a second coating portion and the [Mg] / [X1] ratio was within a predetermined range also showed favorable core loss improvement rates and relative permeability reduction rates.

[0165] (Experimental Example 14) The compositions of powders A to C were the same as those of samples 252 and 253. For powder A, the manufacturing conditions were appropriately changed so that it had the same structure as powder A of sample 252 or powder A of sample 253. For powder C, the manufacturing conditions were appropriately changed so that it had the same structure as powder C of sample 302 or powder C of sample 303. Then, magnetic cores for samples 316 to 327 were prepared by appropriately combining each powder A and each powder C in the mixing ratios shown in Table 14. The results are shown in Table 14.

[0166] [Table 14]

[0167] As shown in Table 14, in each example where powder A and powder C include the first and second coating portions and [Mg] / [X1] is within a predetermined range, the core loss improvement rate and relative permeability reduction rate were favorable, as were in each example where only one of powder A or powder C includes the first and second coating portions and [Mg] / [X1] is within a predetermined range. [Explanation of symbols]

[0168] 11...metal particles 13…Coating film 15...Pt film

Claims

1. Soft magnetic metal particles comprising metal particles and a film coating the metal particles, The coating film comprises at least an oxide of X1, an oxide of X2, and Mg. X1 is Fe, Co, or Ni, X2 is P, Si, B, Na, Al, Ca, Bi, Ba or Zn, The coating film includes a first coating portion that is in contact with the metal particles, and a second coating portion that is in contact with the first coating portion. The first coating portion is the part in which the atomic concentration of X1 is equal to or greater than the atomic concentration of X2, and the second coating portion is the part in which the atomic concentration of X1 is less than the atomic concentration of X2. The maximum atomic concentration of Mg is contained within the coating film, and the atomic concentration of Mg at the maximum atomic concentration is [Mg], and the atomic concentration of X1 at the maximum atomic concentration is [X1]. Soft magnetic metal particles having a [Mg] / [X1] ratio of 0.05 or more and 2.00 or less.

2. The soft magnetic metal particle according to claim 1, wherein X1 is the element that is most abundant in the first coating portion on an atomic basis among Fe, Co, and Ni, and X2 is the element that is most abundant in the second coating portion on an atomic basis among P, Si, B, Na, Al, Ca, Bi, Ba, and Zn.

3. X1 is Fe, The soft magnetic metal particle according to claim 1 or 2, wherein Fe is the element that is most abundant in the first coating portion on an atomic basis among Fe, Co, and Ni.

4. A soft magnetic metal powder comprising soft magnetic metal particles according to claim 1 or 2.

5. A magnetic core comprising soft magnetic metal particles according to claim 1 or 2.

6. A magnetic component comprising soft magnetic metal particles according to claim 1 or 2.

7. An electronic device comprising soft magnetic metal particles according to claim 1 or 2.

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