JP2019106414A - Method for manufacturing soft magnetic powder-compact magnetic core and soft magnetic powder-compact magnetic core - Google Patents

Abstract

To provide a method for manufacturing a soft magnetic powder-compact magnetic core which is low in coercive force and high in specific resistance, and the other.SOLUTION: A method for manufacturing a soft magnetic powder-compact magnetic core comprises the steps of: obtaining soft magnetic powder made of a soft magnetic alloy; and compacting the soft magnetic powder. In the step of compacting the magnetic powder, the compacting temperature is in a range of 400°C or above and 700°C or below, and the compacting pressure is in a range of 400 MPa or more and 2000 MPa or less. The soft magnetic alloy includes Fe as a primary component; when in a continuous measurement range, Fe contents (atom%) of 80000 or more grids of 1 nm×1 nm×1 nm of the soft magnetic alloy are taken for Y axis, and cumulative frequencies (%) of Fe contents of the grids, which are determined cumulatively from their higher sides, are taken for X axis, the soft magnetic alloy has an inclination of -0.1 to -0.4 for each approximate straight line in a range of 20-80% in cumulative frequency, and is amorphous, of which the rate X of amorphous is 85% or more.SELECTED DRAWING: None

Description

  The present invention relates to a method of manufacturing a soft magnetic dust core and a soft magnetic dust core.

  In recent years, lower power consumption and higher efficiency have been required in electronic, information, communication devices and the like. Furthermore, the above-mentioned requirements are becoming stronger toward a low carbon society. Therefore, reduction of energy loss and improvement of power supply efficiency are also required for power supply circuits of electronic, information, and communication devices. And the improvement of magnetic permeability and the reduction of core loss (magnetic core loss) are calculated | required by the magnetic core of the ceramic element used for a power supply circuit. By reducing the core loss, the loss of power energy is reduced, and high efficiency and energy saving can be achieved.

  Patent Document 1 describes that, by changing the particle shape of the powder, a soft magnetic alloy powder suitable for a magnetic core is obtained, which has a large magnetic permeability and a small core loss. However, magnetic cores with smaller core loss are now required.

Japanese Patent Laid-Open No. 2000-30924

  As a method of reducing the core loss of the magnetic core, it is conceivable to reduce the coercivity of the magnetic material constituting the magnetic core.

  An object of the present invention is to provide a method of manufacturing a soft magnetic powder magnetic core having a low coercive force and a high specific resistance, and a soft magnetic powder magnetic core.

In order to achieve the above object, a method of manufacturing a soft magnetic powder core according to the present invention is:
A method of manufacturing a soft magnetic powder core comprising the steps of: obtaining a soft magnetic powder comprising a soft magnetic alloy; and forming the soft magnetic powder,
The molding temperature in the step of molding the soft magnetic powder is 400 ° C. or more and 700 ° C. or less, and the molding pressure is 400 MPa or more and 2000 MPa or less,
The soft magnetic alloy is mainly composed of Fe,
Cumulative frequency (%) determined with the Fe content (atomic%) of 80,000 or more grids of 1 nm × 1 nm × 1 nm in the continuous measurement range of the soft magnetic alloy as the y-axis and the Fe content of each grid in descending order When the x axis has an approximate straight line inclination of -0.1 to -0.4 at a cumulative frequency of 20 to 80%,
It is characterized in that the amorphization ratio X shown in the following formula (1) is amorphous with 85% or more.
X = 100− (Ic / (Ic + Ia) × 100) (1)
Ic: crystalline scattering integral intensity Ia: amorphous scattering integral intensity

  In the method of manufacturing a soft magnetic powder core according to the present invention, the coercivity and ratio of the soft magnetic powder core obtained by setting the inclination of the approximate line to the above range and setting the amorphization ratio X to the above range Good resistance and relative density.

The slope of the approximate straight line has -0.1 to -0.2,
The amorphization ratio X shown in the formula (1) may be 95% or more.

The soft magnetic alloy has C;
The content of C in the soft magnetic alloy may be 0.1 to 7.0 atomic%.

The soft magnetic alloy has B,
The variation σB of the B content in the grid with a cumulative frequency of 95% or more of the Fe content may be 2.8 or more.

The soft magnetic alloy is a Fe-Si-M1-B-Cu-C soft magnetic alloy,
M1 is one or more selected from the group consisting of Nb, Ti, Zr, Hf, V, Ta, Mo and P,
The variation σ M1 of the M1 content in the grid with the cumulative frequency of 95% or more of the Fe content may be 2.8 or more.

The soft magnetic alloy is a Fe-M2-B-C soft magnetic alloy,
M2 is one or more selected from the group consisting of Nb, Cu, Zr and Hf,
The variation σ M2 of the M2 content in the grid with the cumulative frequency of 95% or more of the Fe content may be 2.8 or more.

  The soft magnetic powder magnetic core according to the present invention is a soft magnetic powder magnetic core obtained by any of the above-described manufacturing methods, and is characterized by having a relative density of 0.90 or more.

FIG. 1 is a schematic view showing a measurement range and a grid in an embodiment of the present invention. FIG. 2 is an example of a graph obtained when the Fe content (atomic%) of the grid in the measurement range is taken as the y-axis, and the cumulative frequency (%) found in descending order of the Fe content of each grid is taken as the x-axis It is. FIG. 3 is an example of a chart obtained by X-ray crystal structure analysis. FIG. 4 is an example of a pattern obtained by profile fitting the chart of FIG. FIG. 5 is a schematic view of the single roll method.

  Hereinafter, embodiments of the present invention will be described.

  The soft magnetic alloy according to the present embodiment is a soft magnetic alloy containing Fe as a main component. Specifically, “having Fe as a main component” refers to a soft magnetic alloy in which the content of Fe in the entire soft magnetic alloy is 65 atomic% or more.

  The composition of the soft magnetic alloy according to the present embodiment is not particularly limited except that it is mainly composed of Fe. Examples of Fe-Si-M1-B-Cu-C soft magnetic alloys and Fe-M2-B-C soft magnetic alloys may be mentioned, but other soft magnetic alloys may also be used.

  In the following description, the content ratio of each element of the soft magnetic alloy is 100 at.

When the Fe-Si-M1-B-Cu-C soft magnetic alloy is used, the composition of the Fe-Si-M1-B-Cu-C soft magnetic alloy is changed to Fe _a Cu _b M1 _c Si _d B _When expressing as _e C _f , it is preferable to satisfy the following equation. By satisfying the following formula, the coercivity is reduced, and it tends to be easy to obtain a soft magnetic alloy excellent in toughness. In addition, the soft magnetic alloy having the following composition has a relatively inexpensive raw material. The soft magnetic alloy of the Fe-Si-M1-B-Cu-C system in the present application includes f = 0, that is, a soft magnetic alloy not containing C.

a + b + c + d + e + f = 100
0.1 ≦ b ≦ 3.0
1.0 ≦ c ≦ 10.0
0.0 ≦ d ≦ 17.5
6.0 ≦ e ≦ 13.0
0.0 ≦ f ≦ 7.0

  The Cu content (b) is preferably 0.1 to 3.0 atomic percent, and more preferably 0.5 to 1.5 atomic percent. In addition, as the content of Cu is smaller, it tends to be easier to produce a ribbon made of a soft magnetic alloy by a single roll method described later.

  M1 is at least one selected from transition metal elements and P. Preferably, it is at least one selected from the group consisting of Nb, Ti, Zr, Hf, V, Ta, Mo, P and Cr. Furthermore, more preferably, Nb and / or P is contained as M1.

  The content (c) of M1 is preferably 1.0 to 10.0 atomic percent, and more preferably 3.0 to 5.0 atomic percent. By adding M1 within the above range, the coercivity can be reduced and the toughness can be improved.

  The content (d) of Si is preferably 0.0 to 17.5 atomic percent, more preferably 11.5 to 17.5 atomic percent, and still more preferably 13.5 to 15.5 atomic percent. It is. By adding Si within the above range, the coercive force can be reduced and the toughness can be improved.

  It is preferable that it is 6.0-13.0 atomic%, and, as for content (e) of B, it is more preferable that it is 9.0-11.0 atomic%. By adding B within the above range, the coercivity can be reduced and the toughness can be improved.

  The content (f) of C is preferably 0.0 to 7.0 at%, more preferably 0.1 to 7.0 at%, still more preferably 0.1 to 5.0 at% It is. By adding C within the above range, the coercivity can be reduced and the toughness can be improved.

  In addition, Fe is the remainder of the soft magnetic alloy of the Fe-Si-M1-B-Cu-C system according to the present embodiment.

Moreover, when using a soft magnetic alloy of the Fe-M2-B-C system, when the composition of the soft magnetic alloy of the Fe-M2-B-C system is expressed as Fe _α M 2 _β B _γ C _Ω , It is preferable to satisfy the formula. By satisfying the following formula, the coercivity is reduced, and it tends to be easy to obtain a soft magnetic alloy excellent in toughness. In addition, the soft magnetic alloy having the following composition has a relatively inexpensive raw material. The soft magnetic alloy of the Fe-M2-B-C system in the present application includes Ω = 0, that is, a soft magnetic alloy not containing C.

α + β + γ + Ω = 100
1.0 ≦ β ≦ 14.1
2.0 ≦ γ ≦ 20.0
0.0 ≦ Ω ≦ 7.0

  M2 is a transition metal element. Preferably, it is at least one selected from the group consisting of Nb, Cu, Zr, and Hf. More preferably, M 2 contains one or more selected from the group consisting of Nb, Zr, and Hf.

  The content (β) of M 2 is preferably 1.0 to 14.1 atomic percent, and more preferably 7.0 to 0.11 atomic percent.

  It is preferable that content ((gamma)) of B is 2.0-20.0 atomic%. Further, the content (γ) of B is preferably 4.5 to 18.0 atomic% when Nb is contained as M2, and is preferably 2.0 to 2 when Zr and / or Hf are contained as M2. It is preferable that it is 8.0 atomic%. The lower the B content, the lower the amorphousness. And when content of B is in a predetermined | prescribed range, coercive force Hc can be reduced and toughness can be improved.

  The content (Ω) of C is preferably 0.0 to 7.0 at%, more preferably 0.1 to 7.0 at%, still more preferably 0.1 to 5.0 at% It is. The addition of C tends to improve the amorphousness. When the C content is within the predetermined range, the coercivity Hc can be reduced and the toughness can be enhanced.

  Here, the cumulative frequency of the Fe content in the soft magnetic alloy according to the present embodiment and the inclination of the approximate straight line will be described.

  In the soft magnetic alloy according to the present embodiment, the Fe content (atomic%) of 80,000 or more grids of 1 nm × 1 nm × 1 nm in the continuous measurement range is y-axis, and the Fe content of each grid is determined in descending order When the cumulative frequency (%) is the x-axis, the slope of the approximate straight line at the cumulative frequency of 20 to 80% has -0.1 to -0.4.

  Hereinafter, how to obtain the cumulative frequency of the Fe content in the soft magnetic alloy according to the present embodiment and the inclination of the approximate straight line will be described.

  First, as shown in FIG. 1, in the soft magnetic alloy 11, a rectangular parallelepiped or cube having a length of at least 40 nm × 40 nm × 50 nm is set as the measurement range 12 and the measurement range 12 of the rectangular parallelepiped or cube is one long Divided into 1 nm cube-shaped grids 13. That is, there are 40 × 40 × 50 = 80000 or more grids in one measurement range. In the measurement range according to the present embodiment, the shape of the measurement range is not particularly limited as long as 80,000 or more grids that are finally present exist continuously.

  Next, the Fe content (atomic%) contained in each grid 13 is measured using a three-dimensional atom probe (hereinafter sometimes referred to as 3DAP). Then, the cumulative frequency (%) is calculated for the Fe content in 80,000 or more grids.

  Here, the cumulative frequency (%) of the Fe content is determined as follows. First, the grid is divided according to Fe content, and arranged in descending order of Fe content. Next, the ratio (frequency) of the number of grids in each content to the whole is calculated. And the value which displayed the sum (cumulative sum) of the frequency from the first content (the highest content) to each content with percentage (%) is a cumulative frequency (%). For the above grid, plotting the Fe content on the y-axis and the cumulative frequency (%) determined in descending order of the Fe content on each grid on the x-axis yields, for example, a graph as shown in FIG. From the graph of FIG. 2, it can be seen that the grid having an Fe content of 90 at% or more is approximately 20% of the whole, since the cumulative frequency of an Fe content of 90 at% is approximately 20%. Similarly, since the cumulative frequency of the Fe content of 80 at% is approximately 80%, it can be seen that the grid having the Fe content of at least 80 at% is approximately 80% of the whole. In this graph, the slope of the approximate straight line of the plot in the range of 20 to 80% of the cumulative frequency is calculated. The smaller the absolute value of the slope, the smaller the variation in the Fe content among the grids. And by making the variation between grids small about Fe content, coercive force can be reduced and the soft-magnetic alloy which is excellent in toughness can be obtained.

  The approximate straight line has the Fe content on the y-axis, and the cumulative frequency (%) determined in descending order of the Fe content of each grid on the x-axis, and the cumulative frequency of the Fe content is at least two in the range of 20 to 80%. Perform linear approximation using multiplication.

  In the soft magnetic alloy according to the present embodiment, the Fe content (atomic%) of 80,000 or more grids of 1 nm × 1 nm × 1 nm in the continuous measurement range is y-axis, and the Fe contents of each grid are determined in descending order When the cumulative frequency (%) is the x axis, the slope of the approximate straight line at the cumulative frequency of 20 to 80% is -0.1 to -0.4, preferably -0.1 to -0.38. More preferably, it is -0.1 to -0.35, more preferably -0.1 to -0.2. By making the inclination of the said approximate straight line into the said range, coercive force is reduced and the soft-magnetic alloy which is excellent in toughness can be obtained.

  The approximate straight line of the plot in the range of 20 to 80% of the cumulative frequency is the plot of the plot in the range of less than 20% and 80% of the cumulative frequency and the plot of the plot in the range of 20 to 80% of the cumulative frequency The intention is to exclude that range as it tends to be far from the straight line.

  Further, in the soft magnetic alloy according to the present embodiment, when the cumulative frequency (%) is calculated for the Fe content in 80,000 or more grids as described above, the grid having a cumulative frequency of 95% or more, ie, FIG. The variation σB of the B content in the grid having a cumulative frequency (%) in the range of 95 to 100% in the graph is preferably 2.8 or more, more preferably 2.9 or more, still more preferably 3.0 or more . By setting the variation σB of the B content in the above range, the coercivity is reduced, and a soft magnetic alloy excellent in toughness can be obtained. In addition, variation (sigma) B of B content is calculated by B content measured using 3DAP.

  Similarly, in the soft magnetic alloy according to the present embodiment, when the cumulative frequency (%) is calculated for the Fe content in 80,000 or more grids as described above, the M1 content in the grid is 95% or more. Variation [sigma] M1 or variation in M2 content [sigma] M2 is preferably 2.8 or more, more preferably 2.9 or more, and still more preferably 3.0 or more. By setting the variation σM1 of the M1 content or the variation σM2 of the M2 content in the above range, the coercivity is reduced, and a soft magnetic alloy excellent in toughness can be obtained. The variation σM1 of the M1 content or the variation σM2 of the M2 content is calculated from the M1 content or the M2 content measured using 3DAP.

  The cumulative frequency (%) of the grid with 95% or more of cumulative frequency (%) in the case where the cumulative frequency (%) is calculated for the Fe content in the 80,000 or more grids is in the range of 95-100% in FIG. It refers to a grid and means a grid in the range of 5% to the lower of the Fe content. For example, when grids in the range from the lower of the Fe content to 5% are extracted from 80,000 grids, 4000 grids are extracted.

  The accuracy of the calculated result can be made sufficiently high by performing the measurement shown above several times in each different measurement range. Preferably, the measurement is performed three or more times in different measurement ranges.

In the soft magnetic alloy according to the present embodiment, when the Fe content (atomic%) is the y axis, and the cumulative frequency (%) obtained in descending order of the Fe content of each grid is the x axis, the cumulative frequency 20 The slope of the approximate straight line at -80% has -0.1 to -0.4, and the amorphization ratio X shown in the following formula (1) is 85% or more, preferably 90% or more, more preferably It is 95% or more, more preferably 96% or more, and particularly preferably 98% or more. By setting the amorphization ratio X in the above range, the coercive force is reduced, and a soft magnetic alloy excellent in toughness can be obtained.
X = 100− (Ic / (Ic + Ia) × 100) (1)
Ic: crystalline scattering integral intensity Ia: amorphous scattering integral intensity

  The amorphization ratio X performs X-ray crystal structure analysis by XRD, performs phase identification, and peaks of crystallized Fe or compound (Ic: crystalline scattering integral intensity, Ia: noncrystalline scattering integral intensity The crystallization rate is determined from the peak intensity, and calculated according to the above equation (1). Specifically, it is as follows.

The soft magnetic alloy according to the present embodiment is subjected to X-ray crystal structure analysis by XRD to obtain a chart as shown in FIG. This is subjected to profile fitting using the Lorentz function of the following formula (2), and a crystalline component pattern α _c showing a crystalline scattering integral intensity as shown in FIG. 4 and an amorphous showing a noncrystalline scattering integral intensity A component pattern α _a and a pattern α _{c + a} combining them are obtained. From the crystalline scattering integral intensity and the amorphous scattering integral intensity of the obtained pattern, the amorphization ratio X is determined by the above equation (1). In addition, a measurement range is taken as the range of the diffraction angle 2 (theta) = 30 degrees-60 degrees in which the halo derived from amorphous can be confirmed. Within this range, the error between the actual integral intensity measured by XRD and the integral intensity calculated using the Lorentz function should be within 1%.

In the present embodiment, in the case of obtaining a soft magnetic alloy in the form of a ribbon by the single roll method described later, the amorphization ratio X _A in the surface in contact with the roll surface and the non-contact in the surface not in contact with the roll surface The average value with the crystallization ratio X _B is defined as the amorphization ratio X.

  In the soft magnetic alloy according to the present embodiment, the inclination of the approximate straight line is −0.1 to −0.4, and the amorphization ratio X shown in the formula (1) is 85% or more, that is, The variation in the Fe content among the grids is small, and the coercivity is low and the toughness is excellent because the soft magnetic alloy is highly amorphous.

  Furthermore, in the soft magnetic alloy according to the present embodiment, the inclination of the approximate straight line is set to −0.1 to −0.2, and the amorphization ratio X shown in the formula (1) is set to 95% or more. preferable. Such soft magnetic alloys are easily obtained when the heat treatment described later is not performed. By setting the inclination of the approximate straight line and the amorphization ratio X represented by the formula (1) in the above range, the coercive force Hc is reduced and the toughness is improved.

  Hereinafter, a method of manufacturing the soft magnetic alloy according to the present embodiment will be described.

  Although it does not specifically limit about the manufacturing method of the soft-magnetic alloy which concerns on this embodiment, For example, the method of manufacturing the thin strip of a soft-magnetic alloy by a single roll method is mentioned.

  In the single roll method, first, pure metals of each metal element contained in the soft magnetic alloy finally obtained are prepared, and weighed so as to have the same composition as the soft magnetic alloy finally obtained. Then, pure metals of the respective metal elements are melted and mixed to prepare a mother alloy. The method of dissolving the pure metal is not particularly limited. For example, there is a method in which the pure metal is dissolved by high frequency heating after being evacuated in a chamber. The mother alloy and the soft magnetic alloy finally obtained generally have the same composition.

  Next, the produced mother alloy is heated and melted to obtain a molten metal (bath water). The temperature of the molten metal is not particularly limited, but can be, for example, 1200 to 1500 ° C.

  The schematic diagram of the apparatus used for a single roll method is shown in FIG. In the single roll method according to the present embodiment, the ribbon 24 is manufactured in the rotation direction of the roll 23 by injecting and supplying the molten metal 22 from the nozzle 21 to the roll 23 rotating in the direction of the arrow in the chamber 25. Be done. In the present embodiment, the material of the roll 23 is not particularly limited. For example, a roll made of Cu is used.

  Heretofore, in the single roll method, it has been considered preferable to improve the cooling rate and to rapidly quench the molten metal 22 and to improve the cooling rate by prolonging the contact time between the molten metal 22 and the roll 23 Was considered preferable. Therefore, as shown in FIG. 8, by rotating in the direction opposite to the normal roll rotation direction, the time for which the roll 23 and the thin strip 24 are in contact becomes longer, and the thin strip 24 is made more rapidly. I was able to cool.

  Furthermore, as a merit of rotating the roll 23 in the direction shown in FIG. 5, the strength of the cooling by the roll 23 can be controlled by controlling the gas pressure of the peeling gas injected from the peeling gas injection device 26 shown in FIG. It is. For example, by increasing the gas pressure of the peeling gas, the time in which the roll 23 and the thin strip 24 are in contact can be shortened, and the cooling can be weakened. Conversely, by weakening the gas pressure of the peeling gas, the time for which the roll 23 and the ribbon 24 are in contact can be extended, and the cooling can be strengthened.

  In the single roll method, the thickness of the thin ribbon obtained can be adjusted mainly by adjusting the rotational speed of the roll 23. For example, the distance between the nozzle 21 and the roll 23, the temperature of the molten metal, etc. are adjusted. The thickness of the ribbon obtained can also be adjusted. The thickness of the ribbon is not particularly limited, but may be, for example, 15 to 30 μm.

  There is no particular limitation on the temperature of the roll 23 and the vapor pressure inside the chamber 25. The temperature of the roll 23 may be 50 to 70 ° C., and the vapor pressure in the chamber 25 may be 11 hPa or less using Ar gas whose dew point is adjusted.

  Conventionally, in the single roll method, it is considered preferable to improve the cooling rate and to rapidly quench the molten metal 22, and to increase the cooling rate by widening the temperature difference between the molten metal 22 and the roll 23. It was considered preferable. Therefore, it has been considered that the temperature of the roll 23 is usually preferably about 5 to 30 ° C. However, the inventors set the temperature of the roll 23 to 50 to 70 ° C., which is higher than that of the conventional single roll method, and set the vapor pressure in the chamber 25 to 11 hPa or less, whereby the molten metal 22 is uniformly cooled. It has been found that the ribbon of the resulting soft magnetic alloy before heat treatment can be easily made uniform amorphous. The lower limit of the vapor pressure inside the chamber does not particularly exist. The vapor pressure may be set to 1 hPa or less by filling an Ar gas whose dew point is adjusted, or the vapor pressure may be set to 1 hPa or less as a state close to vacuum.

  The soft magnetic alloy thus obtained may be heat-treated. The heat treatment conditions are not particularly limited. Preferred heat treatment conditions differ depending on the composition of the soft magnetic alloy. Usually, the preferable heat treatment temperature is about 550 to 600 ° C., and the preferable heat treatment time is about 10 minutes to 180 minutes. However, depending on the composition, preferable heat treatment temperatures and heat treatment times may exist outside the above ranges.

  Next, although the pulverizing step of pulverizing the obtained soft magnetic alloy to obtain the soft magnetic powder will be described, the pulverizing step can be performed by any method.

  The pulverizing step can be performed in two steps, for example, a coarse pulverizing step of pulverizing to a particle diameter of several hundred μm to several mm and a pulverizing step of pulverizing to a particle diameter of several μm to about several μm . However, it may be performed in one step of the pulverizing process.

  In the coarse grinding process, the soft magnetic alloy is coarsely ground to a particle size of several hundred μm to several mm. Thereby, a coarsely pulverized powder of soft magnetic alloy is obtained. Coarse grinding can be performed by any method. For example, after allowing a soft magnetic alloy to occlude hydrogen, hydrogen is released based on the difference in hydrogen storage amount between different phases, and dehydrogenation is performed to cause self-disintegrating pulverization (hydrogen occlusion and pulverization). It can be carried out.

  In addition to the method using hydrogen storage and pulverization as described above, the coarse pulverizing step is carried out by a method using a coarse pulverizer such as a stamp mill, jaw crusher or brown mill in an inert gas atmosphere. It is also good.

  After roughly grinding the soft magnetic alloy, the roughly ground powder of the obtained soft magnetic alloy is finely ground until the average particle size becomes about several μm. Thereby, soft magnetic powder is obtained. The pulverized powder may be further pulverized to obtain a pulverized powder having an average particle diameter of 0.5 μm to 300 μm.

The pulverizing step is carried out using a pulverizer such as a jet mill or bead mill while appropriately adjusting the conditions such as the pulverizing time. The jet mill opens high-pressure inert gas (for example, N ₂ gas) from a narrow nozzle to generate a high-speed gas flow, and accelerates the coarsely pulverized powder of soft magnetic alloy by the high-speed gas flow to generate soft magnetism. It is a dry grinding method in which collisions between coarsely crushed powders of the alloy and collisions with the target or the container wall are generated to grind.

  In particular, when it is intended to obtain soft magnetic powder with a fine particle size using a jet mill, the crushed powder surface is very active, so reagglomeration of the crushed soft magnetic powder with each other, to the container wall, Adhesion tends to occur and the yield tends to be low. Therefore, when finely pulverizing the coarsely pulverized powder of the soft magnetic alloy, a pulverization aid such as zinc stearate or oleic acid amide is added to prevent reaggregation of the soft magnetic powders and adhesion to the container wall. Thus, soft magnetic powder can be obtained in high yield. In addition, by adding a grinding aid in this manner, it becomes possible to obtain a finely ground powder which is easy to be oriented when used for molding. The addition amount of the grinding aid may vary depending on the particle size of the pulverized powder and the type of the grinding aid to be added, but may be about 0.1% to 1% by mass% with respect to the pulverized powder.

  As a method other than the dry pulverizing method such as the jet mill, there is a wet pulverizing method. As a wet grinding method, for example, a bead mill in which high speed stirring is performed using small diameter beads can be used. In addition, after dry grinding with a jet mill, multi-stage grinding may be performed in which wet grinding is further performed with a bead mill.

  Further, the method of obtaining the soft magnetic powder according to the present embodiment is not limited to the above method, and the soft magnetic powder according to the present embodiment may be obtained by, for example, a water atomization method or a gas atomization method.

  For example, in the gas atomization method, a molten alloy at 1200 to 1500 ° C. is obtained in the same manner as the single roll method described above. Thereafter, the molten alloy is sprayed in a chamber to produce a powder. At this time, the gas injection temperature is preferably 50 to 100 ° C., and the vapor pressure in the chamber is preferably 4 hPa or less.

  After the powder is produced by the gas atomizing method, the obtained powder may be used as a soft magnetic powder as it is. If necessary, heat treatment may be performed at 550 to 600 ° C. for 10 to 180 minutes, and coarse grinding and / or fine grinding may be performed by the method described above.

  In particular, since the soft magnetic alloy according to the present embodiment is excellent also in toughness, it can be suitably used also for a high pressure dust core.

  Soft magnetic powder can be obtained by the above method. When the soft magnetic alloy before grinding has the inclination of the above-mentioned approximate straight line and the amorphization ratio X, the soft magnetic powder after grinding also has the inclination and the non-appearance of the approximate straight line similar to the soft magnetic alloy before grinding. It has a crystallization ratio X.

  Hereinafter, the process of shape | molding the obtained soft-magnetic powder is demonstrated.

  The soft magnetic powder having the slope of the approximate straight line and the amorphization ratio X is easily deformed because the phase containing Fe is relatively soft. Therefore, a high density and low coercive force powder magnetic core can be obtained by a method in which a soft magnetic powder having the slope of the approximate straight line and the amorphization ratio X described above is filled in a mold and then molded at high pressure while heating. be able to.

  First, the binder and the additive are mixed with the soft magnetic powder before the soft magnetic powder having the slope of the approximate straight line and the amorphization ratio X is filled into the mold.

  As a method of obtaining a magnetic core from soft magnetic powder, for example, after mixing with a binder and an additive as appropriate, a method of molding using a mold may be mentioned. In addition, before mixing with the binder and the additive, the surface of the soft magnetic powder may be subjected to an oxidation treatment, an insulating coating or the like. The resistivity can be improved, and a soft magnetic powder magnetic core adapted to a higher frequency band can be obtained.

  The type of binder is arbitrary. For example, silicone resin can be used. The mixing ratio of the soft magnetic powder to the binder is arbitrary. For example, a binder of 1 to 10% by mass is mixed with 100% by mass of the soft magnetic powder.

  The type of additive is optional. It is preferable to use an additive having an appropriate softening point according to the heating temperature (molding temperature) during molding described later. As an additive, glass, an oxide, etc. can be used, for example. As glass, for example, phosphate glass, bismuth glass, borosilicate glass, vanadic glass and the like can be used. As the oxide, for example, bismuth oxide, vanadium oxide or the like can be used. The mixing ratio of the soft magnetic powder to the additive is arbitrary. For example, an additive of 0.05 to 20% by mass is mixed with 100% by mass of the soft magnetic powder.

  In the method of manufacturing a soft magnetic powder core according to the present embodiment, it is important to perform compression molding at a high temperature and a high pressure within a predetermined range at the time of molding. When the soft magnetic powder has the slope of the above-mentioned approximate straight line and the amorphization ratio X, it is easily deformed as compared with the conventional soft magnetic powder. Therefore, when adding a binder and additives to soft magnetic powder having the slope of the above-mentioned approximate straight line and the amorphization ratio X and performing compression molding at high temperature and high pressure, it is compared with a conventional soft magnetic powder core. Thus, a soft magnetic powder core having higher density and good magnetic properties can be manufactured. Specifically, the high density herein refers to a relative density of 0.90 or more. More preferably, the relative density is 0.95 or more. Further, the relative density is a ratio of the actual density to the theoretical density, and the theoretical density is calculated using the Archimedes method for the soft magnetic powder.

  Specifically, the molding temperature is set to 400 ° C. to 700 ° C., and the molding pressure is set to 400 MPa to 2000 MPa. When the molding temperature is less than 400 ° C., the relative density is low. When the molding temperature is higher than 700 ° C., high coercivity is obtained. In addition, when the molding pressure is less than 400 MPa, the relative density is low. When the molding pressure is over 2000 MPa, a high coercive force is obtained.

  Moreover, it is preferable to make shaping | molding temperature into 10 degreeC or more and 100 degrees C or less and high temperature from the softening point of the additive mentioned above. In other words, it is preferable to select an additive having a softening point 10 ° C. to 100 ° C. lower than the molding temperature.

  A magnetic field can be applied simultaneously with the step of forming the soft magnetic powder or to the formed soft magnetic powder magnetic core. The magnitude of the applied magnetic field is arbitrary.

  In addition, the soft-magnetic powder magnetic core which concerns on this embodiment can be made into arbitrary shapes. For example, it can be made into the toroidal shape shown in FIG. Further, the size of the soft magnetic dust core is not particularly limited.

  Furthermore, the above-mentioned soft magnetic dust core may be further subjected to a heat treatment for distortion removal. By performing distortion removal, core loss is reduced and availability is enhanced.

  In addition, an inductance component can be obtained by winding the above-mentioned soft magnetic dust core. There are no particular limitations on the method of forming the winding and the method of manufacturing the inductance component. For example, there is a method of winding a winding at least one turn or more around the magnetic core manufactured by the above method.

  Furthermore, the inductance component may be manufactured by molding and integrating the winding coil and the soft magnetic powder in a state of being placed in a mold. In this case, it is easy to obtain an inductance component corresponding to a high frequency and a large current.

  Here, in the case of manufacturing an inductance component using soft magnetic powder, it is an excellent Q characteristic that using soft magnetic powder having a maximum particle diameter of 45 μm or less in sieve diameter and a central particle diameter (D50) of 30 μm or less It is preferable to obtain In order to make the maximum particle size 45 μm or less in sieve diameter, a sieve of 45 μm mesh may be used, and only soft magnetic powder passing through the sieve may be used.

  The Q value in the high frequency region tends to decrease as the soft magnetic powder with the largest particle diameter is larger, and especially when using a soft magnetic powder with a maximum particle diameter exceeding 45 μm, the Q value in the high frequency region May drop significantly. However, when not emphasizing the Q value in the high frequency region, it is possible to use a soft magnetic powder having a large variation. Since the soft magnetic powder with large variation can be manufactured at relatively low cost, the cost can be reduced when the soft magnetic powder with large variation is used.

  There are no particular limitations on the application of the dust core according to the present embodiment. For example, it can be suitably used as a core for inductors, in particular for power inductors.

  Hereinafter, the present invention will be specifically described based on examples.

(Experiment 1)
The pure metal materials were respectively weighed so as to obtain a master alloy of the composition of each sample shown in Table 1. And after vacuuming in a chamber, it melt | dissolved by high frequency heating and produced the mother alloy.

  Thereafter, 50 g of the produced mother alloy is heated and melted to form a molten metal at 1300 ° C. Then, the metal is sprayed onto the roll by the single roll method shown in FIG. I made a band. The material of the roll was Cu. The single roll method is a thin strip obtained by setting the rotational speed of the roll 25 m / s under Ar atmosphere, differential pressure 105 kPa between the chamber and the jet nozzle, slit 5 mm nozzle diameter, 50 g fluidization amount, roll diameter φ 300 mm The thickness was 20 to 30 μm, the width 4 to 5 mm, and the length several tens of meters.

  In Experiment 1, the temperature of the roll was 50 ° C., the vapor pressure was 4 hPa, and the peeling injection pressure (quenching ability) was changed to prepare each sample shown in Table 1 below. In addition, the vapor pressure was adjusted by using Ar gas which performed dew point adjustment.

  The following measurements were performed on the obtained strip-shaped sample. The results are shown in Table 1.

(Slope of approximate straight line)
In the obtained ribbon, using a rectangular parallelepiped with a side length of 40 nm × 40 nm × 50 nm as a measurement range, the Fe content of 10000 × 1 nm × 1 nm grid in a continuous measurement range is measured by 3DAP. The slope of the approximate straight line at a cumulative frequency of 20 to 80% when the cumulative frequency (%) obtained with the Fe content (atomic%) as y-axis and the Fe content in each grid in descending order as the x-axis Calculated.

(Amorphization ratio X)
The obtained ribbon was subjected to X-ray crystal structure analysis by XRD to identify a phase. Specifically, the peak of crystallized Fe or compound (Ic: crystalline scattering integral intensity, Ia: non-crystalline scattering integral intensity) is read, and the crystallization rate is determined from the peak intensity, according to the following formula (1) The amorphization ratio X was calculated. In this example, both the surface of the thin ribbon in contact with the roll surface and the surface not in contact with the roll surface were measured, and the average value was defined as the amorphization ratio X.
X = 100− (Ic / (Ic + Ia) × 100) (1)
Ic: crystalline scattering integral intensity Ia: amorphous scattering integral intensity

  Next, each ribbon was crushed to obtain soft magnetic powder. Hydrogen gas was allowed to flow for 1 hour at room temperature for each soft magnetic alloy ribbon to occlude hydrogen. Next, the atmosphere was switched to Ar gas, dehydrogenation treatment was performed at 400 ° C. to 600 ° C. for 1 hour, and the raw material alloy was pulverized with hydrogen. Furthermore, after cooling, a sieve was used to make a powder of a particle size of 425 μm or less. In addition, it was always set as the low oxygen atmosphere of less than 200 ppm of oxygen concentration from hydrogen grinding to the formation process mentioned later.

  Next, 0.1% oleic acid amide by mass ratio was added to and mixed with the powder after hydrogen grinding as a grinding aid.

  Next, the resultant was pulverized in a nitrogen stream using a collision plate type jet mill to obtain a soft magnetic powder having an average particle diameter of 20 to 30 μm. In addition, the said average particle diameter is average particle diameter D50 measured by the particle size distribution analyzer of laser diffraction type.

  The obtained soft magnetic powder, a silicone resin and an additive were mixed and kneaded using a kneader. As the silicone resin, SR2414 manufactured by Toray Industries, Inc. was used. Borosilicate glass having a softening point of 550 ° C. was used as the additive. The total content of the soft magnetic powder, the silicone resin and the additive was 100 wt%, and the content of the silicone resin was 1.2 wt% and the content of the additive was 0.5 wt%.

  Next, the powder magnetic core precursor obtained by the above-mentioned kneading is molded at a molding pressure and a molding temperature shown in the following Table 1 using a mold, and a disk shape (dimension = diameter 10.0 mm x thickness) A powder magnetic core of 4.0 mm) was produced. Then, the coercive force Hc, the specific resistance and the relative density of the produced dust core were measured. The results are shown in Table 1 below.

  The coercive force was measured using a Hc meter (K-Hc 1000 type manufactured by Tohoku Special Steel Co., Ltd.) with respect to the dust core. The results are shown in Table 1 below. The lower the coercivity, the better. In this example, 100 kA / m or less was considered to be good.

  The measurement of a specific resistance was performed by applying an In-Ga electrode on both surfaces of a dust core and measuring a direct current resistance value (unit: Ωm). The measurement was performed using an IR meter (SUPER MEGOHMMETER MODEL SM-5E manufactured by TOA Electoronics). In the present embodiment, the case of 1000 Ωm or more is considered to be good. In Table 1 below, the case where the specific resistance is 1000 Ωm or more is ○, and the case where it is less than 1000 Ωm is ×.

  In the measurement of relative density, the density of the dust core was calculated from the size and weight of the dust core, and the density of the dust core relative to the theoretical density was taken as the relative density. In the present embodiment, the relative density is good at 0.90 or more. The results are shown in Table 1 below.

  From Table 1, the powder magnetic core of the example in which the inclination of the approximate straight line, the amorphization ratio X, the molding pressure and the molding temperature are all controlled within the predetermined ranges is all good in coercive force Hc, specific resistance and relative density. Met. On the other hand, in the comparative example in which any one of the inclination of the approximate line, the amorphization ratio X, the molding pressure and the molding temperature is not controlled within the predetermined range, the coercive force Hc, the specific resistance and / or the relative density are good. It was not a result.

(Experiment 2)
Sample No. 1 of Experiment 1 The test was conducted under the same conditions except that the composition of No. 9 was changed to the compositions shown in Table 2 below. The results are shown in Table 2 below.

  From Table 2, in the powder magnetic core of the example in which the inclination of the approximate line, the amorphization ratio X, the molding pressure and the molding temperature are all controlled within the predetermined range, the coercivity Hc, the specific resistance and the relative density are all good. Met.

(Experiment 3)
The test was conducted under the same conditions except that the composition of the soft magnetic alloy in Experiment 1 was changed, the additive was changed, and the peeling injection pressure was 0.3 MPa. The phosphate glass used had a softening point of 350 ° C. The bismuth-based glass used had a softening point of 480 ° C. Furthermore, measurements of σB and σM1 or σM2 were performed. The results are shown in Table 3 below and Table 4 below.

(Σ B)
In the obtained ribbon, a rectangular parallelepiped having a side length of 40 nm × 40 nm × 50 nm is taken as a measurement range, and the cumulative frequency (%) of the Fe content of 10000 × 1 nm × 1 nm grid in a continuous measurement range Was calculated, and the B content in a grid having a cumulative frequency (%) of 95% or more was measured to calculate .sigma.B. Fe content and B content were measured by 3DAP.

(Σ M 1 or σ M 2)
In the obtained ribbon, a rectangular parallelepiped having a side length of 40 nm × 40 nm × 50 nm is taken as a measurement range, and the cumulative frequency (%) of the Fe content of 10000 × 1 nm × 1 nm grid in a continuous measurement range Was calculated, and the content of M1 or M2 in a grid having a cumulative frequency (%) of 95% or more was measured to calculate σM1 or σM2. Fe content and M1 or M2 content were measured by 3DAP.

  From Table 3 and Table 4, the dust core of the example in which the inclination of the approximate straight line, the amorphization ratio X, the molding pressure and the molding temperature are all controlled within the predetermined ranges has a coercive force Hc, a specific resistance and a relative density. Were all good.

(Experiment 4)
The pure metal materials were respectively weighed so as to obtain a master alloy having the composition shown in Table 5 below. And after vacuuming in a chamber, it melt | dissolved by high frequency heating and produced the mother alloy.

  Thereafter, the produced mother alloy was heated and melted to form a molten metal at 1300 ° C., and then the metal was sprayed by a gas atomizing method to form a powder. The gas injection temperature was 100 ° C., and the vapor pressure in the chamber was 4 hPa. The vapor pressure was adjusted by using an Ar gas whose dew point was adjusted. Then, the slope of the approximate curve, the amorphization ratio X, σB, and σM1 or σM2 were measured for the powder.

  And after mixing each obtained powder (soft-magnetic powder), a silicone resin, and an additive, it shape | molded on the same matter as Experiment 3, and measured coercive force Hc, specific resistance, and relative density. The types of additives, the molding pressure and the molding temperature are described in Table 5 below.

  From Table 5, the dust core of the example in which the inclination of the approximate straight line, the amorphization ratio X, the molding pressure and the molding temperature are all controlled within the predetermined ranges is all good in coercive force Hc, specific resistance and relative density. Met.

11 ... Soft magnetic alloy 12 ... Measurement range 13 ... Grid 21 ... Nozzle 22 ... Molten metal 23 ... Roll 24 ... Strip 25 ... Chamber 26 ... Peeling gas injection device

Claims (7)

A method of manufacturing a soft magnetic powder core comprising the steps of: obtaining a soft magnetic powder comprising a soft magnetic alloy; and forming the soft magnetic powder,
The molding temperature in the step of molding the soft magnetic powder is 400 ° C. or more and 700 ° C. or less, and the molding pressure is 400 MPa or more and 2000 MPa or less,
The soft magnetic alloy is mainly composed of Fe,
Cumulative frequency (%) determined with the Fe content (atomic%) of 80,000 or more grids of 1 nm × 1 nm × 1 nm in the continuous measurement range of the soft magnetic alloy as the y-axis and the Fe content of each grid in descending order When the x axis has an approximate straight line inclination of -0.1 to -0.4 at a cumulative frequency of 20 to 80%,
The manufacturing method of the soft-magnetic powder magnetic core which is amorphous which the amorphization ratio X shown to following formula (1) is 85% or more.
X = 100− (Ic / (Ic + Ia) × 100) (1)
Ic: crystalline scattering integral intensity Ia: amorphous scattering integral intensity The slope of the approximate straight line has -0.1 to -0.2,
The method for producing a soft magnetic powder core according to claim 1, wherein the amorphization ratio X represented by the formula (1) is 95% or more. The soft magnetic alloy has C;
The method for producing a soft magnetic powder core according to claim 1 or 2, wherein the content of C in the soft magnetic alloy is 0.1 to 7.0 atomic%. The soft magnetic alloy has B,
The method for manufacturing a soft magnetic powder core according to any one of claims 1 to 3, wherein the variation σB of the B content in the grid with a cumulative frequency of 95% or more of the Fe content is 2.8 or more. The soft magnetic alloy is a Fe-Si-M1-B-Cu-C soft magnetic alloy,
M1 is one or more selected from the group consisting of Nb, Ti, Zr, Hf, V, Ta, Mo and P,
The method of manufacturing a soft magnetic powder core according to any one of claims 1 to 4, wherein the variation σM1 of the M1 content in the grid with a cumulative frequency of 95% or more of the Fe content is 2.8 or more. The soft magnetic alloy is a Fe-M2-B-C soft magnetic alloy,
M2 is one or more selected from the group consisting of Nb, Cu, Zr and Hf,
The method for manufacturing a soft magnetic powder core according to any one of claims 1 to 4, wherein the variation? M2 of the M2 content in the grid with a cumulative frequency of 95% or more of the Fe content is 2.8 or more.   A soft magnetic dust core obtained by the method according to any one of claims 1 to 6, wherein the relative density is 0.90 or more.

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