阅读说明：本技术 软磁性合金粉末 (Soft magnetic alloy powder ) 是由 木野泰志 水野刚彦 林慎吾 小林久也 飞世正博 齐藤伸 于 2021-06-23 设计创作，主要内容包括：本发明是一种软磁性合金粉末,其中,以铁为主要成分且具有软磁性的合金粉末被具有绝缘性的绝缘被膜被覆。该绝缘被膜包括：与构成软磁性合金粉末的合金粉末的表面相接的第一被膜,与第一被膜相接的第二被膜。其中,第二被膜的厚度相对于第一被膜的厚度的比值为0.02～300。(The present invention provides a soft magnetic alloy powder, wherein the alloy powder containing iron as a main component and having soft magnetism is coated with an insulating coating having insulation properties. The insulating film includes: a first film in contact with the surface of the alloy powder constituting the soft magnetic alloy powder, and a second film in contact with the first film. Wherein the ratio of the thickness of the second film to the thickness of the first film is 0.02 to 300.)

1. A soft magnetic alloy powder comprising iron as a main component and an alloy powder having soft magnetism, the alloy powder being coated with an insulating coating,

the insulating film includes a first film in contact with the surface of the alloy powder, a second film in contact with the first film,

the ratio of the thickness of the second film to the thickness of the first film is 0.02 to 300.

2. The soft magnetic alloy powder according to claim 1, wherein the ratio of the particle diameter D50 of the alloy powder to the thickness of the insulating coating is 1.4 to 10000.

3. The soft magnetic alloy powder according to claim 1 or 2, wherein the particle diameter D50 of the alloy powder is 0.5 to 20 μm.

4. The soft magnetic alloy powder according to any one of claims 1 to 3, wherein the first coating film contains at least 1 or more of B, Cr, and Al.

5. The soft magnetic alloy powder according to claim 4, wherein the first capsule is a nitride.

6. The soft magnetic alloy powder according to any one of claims 1 to 5, wherein the second coating film is formed of SiO₂Is the main component.

7. The soft magnetic alloy powder according to any one of claims 4 to 6, wherein the first coating film and/or the second coating film further contains at least 1 of Mn or Ti.

8. The soft magnetic alloy powder according to any one of claims 1 to 6,

the alloy powder

Contains Si and Al in amounts satisfying the relationship of Si not less than 2% by weight, Al not less than 1% by weight, and Si + Al not more than 12% by weight, and the balance may be made up of Fe and unavoidable impurities,

and has an amorphous structure.

9. A soft magnetic alloy powder according to claim 8, which has a negative core loss temperature characteristic at 25 ℃ to 150 ℃.

10. The soft magnetic alloy powder according to claim 8 or 9, wherein a part of Fe is substituted for at least 1 or more of B, Cr, and Al in the alloy powder constituting the soft magnetic alloy powder.

11. The soft magnetic alloy powder according to claim 10, wherein the total amount of B, Cr, and Al substituted with Fe in the alloy powder is 1 to 10 wt% based on the entire alloy powder.

Technical Field

The present invention relates to a soft magnetic alloy powder.

Background

In recent years, soft magnetic materials that can be used at high currents and high frequencies have been desired as power inductors used in power supply circuits in view of the demands for smaller size and lower height. Conventionally, ferrite-based materials, which are oxides, have been used as main materials of inductors, but since saturation magnetization is low, miniaturization is not facilitated, and in recent years, metal inductors using alloy-based materials having high saturation magnetization and advantageous for miniaturization and height reduction have been rapidly increased. As a metal inductor, there has been known a dust core or the like obtained by mixing a soft magnetic alloy powder mainly composed of iron (hereinafter, also referred to as a soft magnetic alloy powder) with a resin and compression-molding the mixture. The magnetic properties (saturation magnetization, permeability, core loss, frequency characteristics, etc.) of the dust core depend on the magnetic properties and particle size distribution, filling properties, and electric resistance of the soft magnetic alloy powder used.

In the process of increasing concern about energy, the electric driving of automobiles and the power saving of electronic devices are promoted, and there is a demand for a compact magnetic core that can be further miniaturized and has less energy loss. For example, there is an example of "mechatronics" for coping with reinforcement for achieving control of high environmental performance and drivability in an automobile. Here, in order to mount an ECU (Electronic Control Unit) to an actuator such as a motor or a solenoid, there is an increasing demand for providing the ECU in an engine room or the like having a higher ambient temperature. Therefore, there is a demand for development of magnetic powder for use in powder magnetic cores and the like suitable for ECUs, which can be used at higher ambient temperatures.

Since ferrite materials used in the past are oxides, reliability such as insulation and heat resistance is high, and reliability of these properties of alloy materials is lower than that of ferrite materials. As a measure for improving the insulation property and heat resistance of the soft magnetic alloy powder, a measure for forming a coating film on the soft magnetic alloy powder is known (for example, patent document 1). However, in order to obtain high insulation and high heat resistance, the thickness of the insulating film needs to be increased. Therefore, it is difficult to achieve both of the reliability such as insulation and heat resistance and the magnetic characteristics.

Patent document 1: japanese patent laid-open No. 2003-272911

Disclosure of Invention

The purpose of the present invention is to provide a soft magnetic alloy powder having high magnetic characteristics and having both insulation properties and reliability such as heat resistance.

One aspect of the present invention is a soft magnetic alloy powder in which an alloy powder containing iron as a main component and having soft magnetism is coated with an insulating coating film having insulating properties. The insulating film includes: a first film in contact with the surface of the alloy powder constituting the soft magnetic alloy powder, and a second film in contact with the first film. Wherein the thickness (t) of the second coating film₂) Relative to the thickness (t) of the first coating₁) Ratio (t)₂/t₁) Is 0.02 to 300.

In one embodiment of the present invention, the ratio (D/T) of the particle diameter (D50) (D) of the alloy powder to the thickness (T) of the insulating film may be 1.4 to 10000.

In one embodiment of the present invention, the particle diameter (D50) of the alloy powder may be 0.5 to 20 μm.

In one embodiment of the present invention, the first coating may contain at least 1 or more of B, Cr, and Al.

In one embodiment of the present invention, the first capsule may be a nitride.

In one embodiment of the present invention, the second coating film may be formed of SiO₂Is the main component.

In one embodiment of the present invention, the first coating and/or the second coating may further contain at least any one of 1 kind of Mn or Ti.

In one embodiment of the present invention, the alloy powder may contain Si and Al in amounts satisfying the relationship of Si ≥ 2 wt%, Al ≥ 1 wt%, and Si + Al ≤ 12 wt%, and the remainder may be composed of Fe and unavoidable impurities. Among them, it may have an amorphous composition.

In one embodiment of the present invention, the soft magnetic alloy powder may have a negative core loss temperature characteristic at 25 ℃ to 150 ℃.

In one embodiment of the present invention, in the alloy powder, a part of Fe may be substituted with at least 1 or more of B, Cr, and Al.

In one embodiment of the present invention, the total amount of B, Cr, and Al substituted with Fe in the alloy powder may be 1 to 10 wt% based on the entire alloy powder.

Effects of the invention

The present invention provides an iron-based soft magnetic alloy powder having both high magnetic characteristics and reliability such as insulation and heat resistance.

Detailed Description

Hereinafter, an embodiment of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented by applying appropriate modifications within a range not impairing the effects of the present invention.

The soft magnetic alloy powder of the present embodiment is formed by coating the surface of an alloy powder containing iron as a main component with an insulating coating. The insulating film is formed of a first film covering the surface of the alloy powder and a second film covering the powder covered with the first film. Although high heat resistance can be obtained by thickening the insulating film, the insulating film is easily peeled off from the alloy powder due to, for example, a difference in thermal expansion coefficient between the insulating film and the alloy powder. Therefore, in order to improve the adhesion of the second film, the first film is formed on the surface of the alloy powder, and the second film is formed thereon. That is, high heat resistance can be ensured by the second film, and an impact that causes peeling of the second film can be absorbed by the first film. Here, if the thickness t of the second film is set₂Thickness t relative to the first coating₁Ratio (t)₂/t₁) If the thickness is too large, the cushioning effect of the first film cannot be sufficiently obtained. On the other hand, if the ratio is too small, the insulation property is lowered. The thickness t of the second coating is satisfied to achieve both high insulation and high heat resistance₂Thickness t relative to the first coating₁Ratio (t)₂/t₁) Is 0.02 to 300, preferably 0.1 to 100, and more preferably 2 to 25.

[ film thickness ]

The thickness of the insulating coating of the soft magnetic alloy powder according to the present embodiment is an actual measurement value of the thickness measured by a transmission electron microscope or the like.

[ insulating coating ]

The "insulating coating" in the present specification means a coating having insulating properties formed on the surface of an alloy powder having soft magnetism. The material of the coating is not particularly limited as long as the coating has insulation properties.

[ Soft magnetic alloy powder ]

In the present specification, the term "soft magnetic alloy powder" refers to a powder in which an insulating coating is coated on the surface of an alloy powder having soft magnetism mainly composed of iron (hereinafter, simply referred to as "alloy powder"). In view of the magnetic characteristics, productivity, and the like, the alloy powder is preferably produced by an atomization method. The particle size of the soft magnetic alloy powder is not particularly limited, and can be adjusted according to the desired magnetic properties.

[ particle diameter (D50)/thickness of insulating coating ]

In the soft magnetic alloy powder of the present embodiment, if the ratio (D/T) of the particle diameter D of the alloy powder to the thickness T of the insulating coating is too large, the proportion of the magnetic component in the volume decreases, and therefore sufficient magnetic properties cannot be obtained. On the other hand, if the ratio is too small, the insulation is low, and sufficient magnetic characteristics cannot be obtained. In order to have excellent magnetic properties and to achieve both high insulation and high heat resistance, the ratio (D/T) of the particle diameter D of the alloy powder to the thickness T of the insulating coating is 1.4 to 10000, preferably 30 to 1500, and more preferably 40 to 1000. Here, the "particle diameter of the soft magnetic alloy powder" refers to the median particle diameter (D50) of the soft magnetic alloy powder, and can be measured by a conventionally known method, for example, a laser diffraction scattering method. Further, "the ratio of the particle diameter of the soft magnetic alloy powder to the thickness of the insulating coating" means the median particle diameter of the soft magnetic powder: the ratio of the measured value of D50 to the measured value of the film thickness of the insulating film is a dimensionless quantity having no unit. By setting the ratio within the above range, the soft magnetic alloy powder can have excellent properties as a material for the dust core.

[ particle diameter ]

The effects of the above soft magnetic alloy powder relating to the saturation magnetic flux density (Bs), the magnetic permeability, and the negative core loss temperature characteristics described below can be obtained from soft magnetic alloy powder having a wide range of particle diameters. Particularly good effects can be obtained by having the particle diameter (D50) of 0.5 to 20 μm.

[ first coating film ]

The first film plays a role of suppressing the peeling of the second film as described above. The material of the first film is not particularly limited as long as it has high affinity with the alloy powder and the second film or has an effect of absorbing an impact that tends to peel off the second film. In particular, by containing at least 1 or more of B, Cr, and Al, not only can peeling of the second coating be suppressed, but also the magnetic properties of the soft magnetic alloy powder in a high frequency band can be improved. Further, by making the first film nitride, the magnetic characteristics in a high frequency band can be further improved. Here, the high band means a region of 1MHz or more.

The first coating may further contain at least 1 of Mn or Ti. By adding these elements in a small amount, the effects of further improving the adhesion between the alloy powder and the second film, further improving the ability of the second film to absorb an impact that tends to peel off, and further improving the magnetic properties in a high frequency range can be obtained.

[ second coating film ]

The second coating can be Al₂O₃、SiO₂And materials with high insulating properties such as MgO. In the present embodiment, the second coating film contains SiO as a main component₂. Since the insulating coating is dense and chemically very stable SiO₂The coating film can provide a soft magnetic alloy powder which is less likely to peel off and has high insulation and heat resistance.

The second coating may further contain at least 1 of Mn or Ti. By adding these elements in a trace amount, effects of further improving the adhesion to the first film, improving the peelability of the second film, and further improving the insulation and heat resistance of the second film can be obtained. In addition, when the same element as the element added in a trace amount in the first coating is contained, the adhesion between the first coating and the second coating is further improved.

[ alloy powder ]

In the soft magnetic alloy powder of the present embodiment, the alloy powder contains Si and Al in amounts satisfying the relationship of Si ≥ 2 wt%, Al ≥ 1 wt%, and Si + Al ≤ 12 wt%, with the remainder consisting of Fe and unavoidable impurities. The soft magnetic alloy powder of the present embodiment preferably contains Si and Al in amounts satisfying the relationship of Si.gtoreq.3.5 wt%, Al.gtoreq.2.5 wt%, and Si + Al.ltoreq.12 wt%. Since the soft magnetic alloy powder is a powder of an amorphous composition containing Si and Al in amounts satisfying the above relationship, the saturation magnetic flux density (Bs) and the magnetic permeability of the soft magnetic alloy powder are improved. Due to this effect, the soft magnetic alloy powder of the present embodiment is advantageous for downsizing of electronic components.

Further preferably, the alloy powder has an amorphous composition. Since the alloy powder has an amorphous structure having the above composition, it has flame retardancy in addition to excellent soft magnetic characteristics.

In the alloy powder of the soft magnetic alloy powder of the present embodiment, a part of Fe may be substituted with at least 1 or more of B, Cr, and Al. By substituting these elements, the soft magnetic characteristics are improved, and the reliability of the insulation property and the heat resistance is improved. However, if these elements are too large, the content of Fe is relatively reduced, and therefore the magnetic properties of the soft magnetic alloy powder are degraded. On the other hand, if the amount is too small, the substitution effect cannot be sufficiently obtained. The total amount of B, Cr and Al substituted with Fe is 1 to 10 wt%, preferably 1.5 to 5 wt%, based on the total weight of the alloy powder.

The alloy powder of the soft magnetic alloy powder of the present embodiment may contain an element such as N, S, O as an inevitable impurity within a range that does not affect the target characteristics.

In addition, the soft magnetic alloy powder containing Si and Al in amounts satisfying the above relationship, with the balance being Fe and inevitable impurities has a negative core loss temperature characteristic in the range of 25 ℃ to 120 ℃. The soft magnetic alloy powder of the present embodiment, which contains Si and Al in amounts satisfying the relationship of Si.gtoreq.3.5 wt%, Al.gtoreq.2.5 wt%, and Si + Al.ltoreq.12 wt%, further has a negative core loss temperature characteristic in the range of 120 to 150 ℃.

[ negative temperature characteristics of magnetic core loss ]

The negative core loss temperature characteristic is a characteristic in which the core loss of the soft magnetic alloy powder has a negative coefficient with respect to temperature, that is, the core loss of the soft magnetic alloy powder decreases with an increase in temperature. The soft magnetic alloy powder of the present embodiment having a negative core loss temperature characteristic can suppress an increase in temperature of the core itself due to heat generation caused by the core loss at the time of use because the core loss decreases with an increase in temperature, and has suitable characteristics as a material for electronic components such as powder magnetic cores that have been difficult to use in a high-temperature environment. The soft magnetic alloy powder of the present embodiment has a negative core loss temperature characteristic, and is considered to have a positive value in the magnetostriction constant determined by the composition.

[ production method ]

The soft magnetic alloy powder according to the embodiment of the present invention is produced by forming an insulating coating on an iron-based alloy powder having soft magnetism.

The alloy powder as a material can be produced by a conventionally known method exemplified below as a method for producing a metal powder, but the production method is not particularly limited as long as the alloy powder has the composition of the present embodiment and can have the above-described magnetic properties.

Atomization method: water atomization, gas atomization, centrifugal atomization, and the like

Mechanical treatment: pulverizing method, mechanical alloying method, etc

Melt spinning process

Rotary electrolysis process (REP process): plasma REP method and the like

Chemical treatment process: oxide reduction, chloride reduction, hydrometallurgical techniques, carbonyl reactions, and the like

Among the above-exemplified production methods, particularly the atomization method enables mass production of small-diameter spherical alloy powder under atmospheric pressure. Among them, the water atomization method can be used for production at low cost. Further, by producing the alloy powder by the water atomization method so as to reduce the particle diameter of the alloy powder, eddy current loss can be suppressed, and a dust core or the like having excellent magnetic characteristics can be produced.

In the case of producing alloy powder by the water atomization method, high-pressure water having set parameters is sprayed to a melt obtained by melting a material adjusted to a desired composition so as to achieve a desired cooling condition and particle diameter, whereby the melt can be scattered and solidified to obtain powder. Then, the obtained powder is dried and classified, and if necessary, surface-treated to obtain a desired alloy powder.

The insulating film is formed by a step of forming a first film and a step of forming a second film.

The first coating film can be formed by a known technique such as plasma treatment, heat treatment, chemical treatment, sputtering, or the like.

The second coating can be formed by a conventionally known method such as a vapor phase method such as Chemical Vapor Deposition (CVD) or Physical Vapor Deposition (PVD) or a sputtering method. Particularly, from the viewpoint of productivity and cost, it is preferably carried out by a sol-gel method. In the sol-gel method, a solution of a metal alkoxide and/or a metal acetate, which is a raw material of an oxide as a coating component, water for hydrolysis, an alcohol as a solvent, an acid or an alkali as a catalyst, and the like is mixed with the soft magnetic alloy powder obtained as described above, and then the solvent is removed by heating, thereby forming an insulating coating. The mixing can be carried out by, for example, a planetary mixer, a kneader, a mortar machine, a ribbon mixer, etc., and the apparatus used for mixing is not particularly limited as long as it has a mechanism for mixing the powder and the solution. In the sol-gel method, the thickness of the insulating film can be adjusted to a desired thickness by adjusting conditions such as the amount of the insulating material to be mixed, the mixing time, the method of dropping the solution, the amount of dropping, and the temperature.

After the insulating film is formed, the soft magnetic alloy powder having a target particle diameter corresponding to the desired magnetic properties can be obtained by classification.

Examples

The powder magnetic core produced from the soft magnetic alloy powder of the above embodiment was not lowered in resistance value and withstand voltage after 3000 hours of operation at 180 ℃. In addition, good results were obtained in terms of magnetic permeability and core loss as magnetic characteristics also at high frequencies of 1MHz or more. Therefore, the soft magnetic alloy powder of one embodiment can produce an electronic component having excellent characteristics even under a high-temperature environment.