JPWO2018062310A1 - Nanocrystal alloy core, magnetic core unit and method of manufacturing nanocrystal alloy core - Google Patents

Abstract

A method of manufacturing a nanocrystalline alloy core is a method of manufacturing a nanocrystalline alloy core in which a magnetic core of a wound or laminated amorphous alloy ribbon is nanocrystallized by heat treatment, wherein the magnetic core starts crystallization in no magnetic field. There is a primary heat treatment step of performing a primary heat treatment that raises the temperature from a temperature lower than the temperature to at least the crystallization start temperature, and a secondary heat treatment step that is performed thereafter, and the secondary heat treatment step It has a secondary temperature holding step of holding at a constant temperature below the crystallization start temperature, and then a secondary temperature lowering step of decreasing the temperature while applying a magnetic field in a direction perpendicular to the magnetic path.

Description

  The present application relates to a nanocrystal alloy core wound or stacked with a nanocrystal alloy, a core unit, and a method of manufacturing the nanocrystal alloy core.

  Examples of a core unit in which a conductor is wound around a core include a common mode choke coil and a current transformer. Common mode choke coils are used as filters that distinguish between noise and signals according to the conduction mode. The current transformer is a current transformer for measurement, and is used, for example, in a current measuring instrument or a leak breaker. These have a magnetic core of soft magnetic material used for a closed magnetic circuit. Patent Document 1 discloses that a magnetic core produced from a ribbon (ribbon) of a nanocrystal alloy of Fe or Co group is suitable as a magnetic core used for these. The nanocrystalline alloy exhibits higher saturation magnetic flux density than permalloy or Co-based amorphous alloy, and has higher permeability than Fe-based amorphous alloy.

  A typical composition of the nanocrystal alloy is disclosed, for example, in Patent Document 2 and the like. A typical example of a method of manufacturing a magnetic core using a nanocrystalline alloy includes the steps of: quenching the melt of a raw material alloy having a desired composition to form an amorphous alloy ribbon; and winding the amorphous alloy ribbon to form a ring Forming an amorphous core material, and crystallizing the amorphous alloy ribbon by heat treatment to obtain a magnetic core having a nanocrystalline structure.

  In addition, the nanocrystal alloy core can largely change magnetic properties such as permeability μ and squareness ratio by applying a temperature profile during heat treatment or applying a magnetic field in a specific direction during heat treatment. For example, in Patent Document 3, high permeability with a permeability μ (50 Hz to 1 kHz) of 70,000 or more and a squareness ratio of 30% or less by setting the direction of magnetic field application to the height direction or radial direction of the core. Low core ratio magnetic cores are described. Further, (0018) of Patent Document 3 described above performs a primary heat treatment of nanocrystallization while maintaining the surface temperature of the alloy core at a crystallization temperature + 100 ° C. or less as a manufacturing method. As a result, excellent soft magnetic characteristics can be obtained even with large magnetic cores, and even if heat treatment is performed on a large amount of magnetic cores, characteristic variations are small, mass production is possible, and nanocrystalline alloy cores with excellent soft magnetic characteristics can be manufactured. It is pointed out that if this temperature range is exceeded, problems such as an increase in coercivity will occur.

  Further, Patent Document 4 discloses a magnetic core for a pulse transformer using a nanocrystal alloy, which has a relative initial permeability of 50,000 or more at -20 ° C and 50 ° C. As a specific manufacturing method of this magnetic core, the primary heat treatment is performed within two hours at 500 ° C. to 580 ° C. for crystallization, and thereafter, the bcc phase formed by crystallization lower than the heat treatment of crystallization above 300 ° C. It is disclosed that the secondary heat treatment is further performed at a temperature lower than the Curie temperature of The same document also describes that heat treatment in a magnetic field can be used in combination, and in the example, FIG. 1 and FIG. 2, the profile of heat treatment in a magnetic field in which a magnetic field is applied from the time of holding temperature is described in secondary heat treatment. It is done.

  Further, Patent Document 5 describes, as in Patent Document 4, an example in which the primary heat treatment and the secondary heat treatment are performed on the nanocrystal alloy core, and FIGS. 4, 5 (a), (b), and FIG. In 6, the temperature and magnetic field application profile from which the magnetic field is applied from the point of holding the temperature is lowered without holding the temperature and the temperature and magnetic field application profile is simultaneously applied. ,Have been described. The feature of the invention of Patent Document 5 is that the cooling rate after the primary heat treatment is defined (cooling to 400 ° C. at 20 ° C./min or more).

Patent No. 2501860 gazette Japanese Examined Patent Publication No. 4-4393 Japanese Patent Application Laid-Open No. 7-278764 Japanese Patent Application Laid-Open No. 7-94314 JP-A-8-85821

  The nanocrystal alloy core is required to further enhance the characteristics that the permeability and impedance ratio permeability at 1 MHz or less are high and the temperature fluctuation of the permeability is small. The present disclosure provides a nanocrystal alloy core, a core unit, and a method of manufacturing a nanocrystal alloy core capable of enhancing at least one of these two properties.

  A first method for producing a nanocrystalline alloy core according to the present disclosure is a method for producing a nanocrystalline alloy core, in which a magnetic core of a wound or laminated amorphous alloy ribbon is nanocrystallized by heat treatment, There is a primary heat treatment step of performing a primary heat treatment in which the temperature is raised from a temperature lower than the crystallization start temperature to a crystallization start temperature or higher in a no magnetic field, and a secondary heat treatment step performed thereafter. A second temperature holding step of holding at a constant temperature of at least 200 ° C. and less than the crystallization start temperature in a magnetic field, and then a second temperature lowering step of decreasing the temperature while applying the magnetic field in a direction orthogonal to the magnetic path; Have.

  In the second temperature holding step, after the temperature of the magnetic core is in the range of ± 5 ° C. with respect to the temperature at the time when the application of the magnetic field is started, the holding time in the temperature range is 1 minute or more May be

  The magnetic field may be applied at a magnetic field strength of 60 kA / m or more.

  The holding temperature of the secondary heat treatment may be 200 ° C. or more and 500 ° C. or less.

  The holding temperature of the primary heat treatment may be 550 ° C. or more and 600 ° C. or less.

  The amorphous alloy ribbon may have a thickness of 7 μm to 15 μm.

The amorphous alloy ribbon has a general formula: (Fe _1-a M _a ) _{100-xyz-α-β-γ} Cu _x Si _y B _z M ′ _α M ′ ′ _β X _γ (atomic%) (where M is Co And / or Ni, M 'is at least one element selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V, Cr, Mn and W, M "is Al, a platinum group element Sc, at least one element selected from the group consisting of rare earth elements, Zn, Sn and Re, and X is at least one selected from the group consisting of C, Ge, P, Ga, Sb, In, Be and As The elements of the species, a, x, y, z, α, β and γ are respectively 0 ≦ a ≦ 0.5, 0.1 ≦ x ≦ 3, 0 ≦ y ≦ 30, 0 ≦ z ≦ 25, 5 ≦ y + z 30, 0 ≦ α ≦ 20, 0 ≦ β ≦ 20, and 0 ≦ γ ≦ 20.

  You may have the process of further impregnating resin after the said 2nd heat processing.

  In the secondary heat treatment, after holding at a constant temperature of 200 ° C. or more and less than the crystallization start temperature in the non-magnetic field, hold at this temperature while applying a magnetic field in a direction orthogonal to the magnetic path; Thereafter, the temperature may be lowered while applying a magnetic field in the direction orthogonal to the magnetic path.

  In the secondary temperature holding step, after the temperature of the magnetic core falls within the range of ± 5 ° C. with respect to the temperature decrease start temperature, the holding time in the temperature range is made 1 minute or more, and then the temperature range is held However, the magnetic field may be applied in the direction orthogonal to the magnetic path.

  In the secondary heat treatment step, after holding at a constant temperature of 200 ° C. or more and less than the crystallization start temperature in the non-magnetic field, the magnetic field is directed in the direction orthogonal to the magnetic path from the start of temperature decrease. The temperature may be lowered while applying

The volume of the magnetic core may be 3000 mm ³ or more.

  The temperature rising rate in the step of the primary heat treatment may be less than 1.0 ° C./min.

  In the step of the primary heat treatment, the maximum temperature may be more than 550 ° C. and 585 ° C. or less.

  In the step of the secondary heat treatment, the maximum temperature when applying a magnetic field may be 200 ° C. or more and less than 400 ° C.

  In the step of the secondary heat treatment, the magnetic field may be applied while decreasing the temperature at an average speed of 4 ° C./min or less.

  The second method for producing a nanocrystalline alloy core according to the present disclosure raises an amorphous core material composed of an amorphous alloy ribbon capable of nanocrystallization from a temperature lower than the crystallization start temperature to a crystallization start temperature or more in a non-magnetic field. A method of manufacturing a nanocrystal alloy core comprising: a primary heat treatment step of heating and nanocrystallizing; and a secondary heat treatment step of applying a magnetic field in a direction perpendicular to the magnetic path at a temperature lower than the crystallization start temperature. The temperature rising rate in the step of the primary heat treatment is less than 1.0.degree. C./min.

  The third method for manufacturing a nanocrystal alloy core according to the present disclosure raises an amorphous core material composed of an amorphous alloy ribbon capable of nanocrystallization from a temperature lower than the crystallization start temperature to a crystallization start temperature or more in a non-magnetic field. A method of manufacturing a nanocrystal alloy core comprising: a primary heat treatment step of heating and nanocrystallizing; and a secondary heat treatment step of applying a magnetic field in a direction perpendicular to the magnetic path at a temperature lower than the crystallization start temperature. In the step of the primary heat treatment, the maximum temperature is more than 550 ° C. and not more than 585 ° C.

  The fourth method for producing a nanocrystalline alloy core according to the present disclosure raises an amorphous core material made of an amorphous alloy ribbon capable of nanocrystallization from a temperature lower than the crystallization start temperature to a crystallization start temperature or more in a non-magnetic field. A method of manufacturing a nanocrystal alloy core comprising: a primary heat treatment step of heating and nanocrystallizing; and a secondary heat treatment step of applying a magnetic field in a direction perpendicular to the magnetic path at a temperature lower than the crystallization start temperature. In the step of the secondary heat treatment, the maximum temperature when applying a magnetic field is 200.degree. C. or more and less than 400.degree.

  According to a fifth method for producing a nanocrystalline alloy core of the present disclosure, an amorphous core material composed of an amorphous alloy ribbon capable of nanocrystallization is raised from a temperature lower than the crystallization start temperature to a crystallization start temperature or more in a non-magnetic field. A method of manufacturing a nanocrystal alloy core comprising: a primary heat treatment step of heating and nanocrystallizing; and a secondary heat treatment step of applying a magnetic field in a direction perpendicular to the magnetic path at a temperature lower than the crystallization start temperature. In the step of the second heat treatment, a magnetic field is applied while decreasing the temperature at an average speed of 4 ° C./min or less.

  In the third to fifth methods for producing a nanocrystal alloy core, the temperature raising rate in the step of the primary heat treatment may be less than 1.0 ° C./min.

  In the second, fourth and fifth methods of manufacturing a nanocrystal alloy core, the maximum temperature in the step of the primary heat treatment may be more than 550 ° C. and not more than 585 ° C.

  In the second, third and fifth methods of manufacturing a nanocrystal alloy core, the maximum temperature when applying a magnetic field may be 200 ° C. or more and less than 400 ° C.

  In the second, third and fourth methods for manufacturing a nanocrystal alloy core, the magnetic field may be applied while the temperature is lowered at an average speed of 4 ° C./min or less during the step of the secondary heat treatment.

  The step of the secondary heat treatment may include the step of lowering the temperature to at least 100 ° C. while applying the magnetic field.

  The magnetic field may be applied at a magnetic field strength of 50 kA / m or more.

  The thickness of the amorphous alloy ribbon may be 7 μm or more and 15 μm or less.

  The nanocrystalline alloy core of the present disclosure includes a wound or stacked nanocrystalline alloy ribbon, and an alternating magnetic field with a frequency f of 1 kHz and an amplitude H of 0.05 amperes / meter (A / m) is applied. The permeability μ (1 kHz) measured at room temperature is 70,000 or more, the squareness ratio Br / Bm is 50% or less, and the coercivity is 1.0 A / m or less.

  Another nanocrystal alloy core of the present disclosure includes a wound or stacked nanocrystal alloy ribbon, and the nanocrystal alloy ribbon is made of an Fe-based material, and the impedance relative permeability μrz is 48, at a frequency of 100 kHz. It is over 000.

  The impedance relative permeability μrz may be 90,000 or more at a frequency of 10 kHz, 48,000 or more at a frequency of 100 kHz, and 8,500 or more at a frequency of 1 MHz.

  The thickness of the nanocrystal alloy ribbon may be 7 μm or more and 15 μm or less.

  The nanocrystal alloy core may be impregnated with a resin.

  The nanocrystal alloy core may be for a common mode choke coil.

  A core unit of the present disclosure includes the nanocrystal alloy core according to any one of the above and a wire wound around the nanocrystal alloy core.

  According to a method of manufacturing a nanocrystal alloy core, a core unit and a nanocrystal alloy core of the present disclosure, temperature fluctuation of permeability is reduced and / or permeability / impedance ratio permeability at 1 MHz or less is increased. Is possible.

It is a figure which shows the relationship of the temperature change rate (25 degreeC-100 degreeC) of coercive force and magnetic permeability in the nanocrystal alloy core of 1st Embodiment. It is a graph which shows the example of the temperature of 1st heat processing and secondary heat processing in Example 1, and the profile of magnetic field intensity. FIG. 5 is a diagram showing a B-H curve of the nanocrystalline alloy core of Example 1. It is a figure which shows the BH curve of the nanocrystal alloy core of the comparative example 1. FIG. It is a figure showing an outline of a magnetic core arranged in a heat treatment furnace. It is a graph which shows the example of the temperature of 1st heat processing and secondary heat processing in Example 2-1, and the profile of magnetic field intensity. It is the elements on larger scale of FIG. It is a figure which shows the BH curve of the nanocrystal alloy core obtained in Example 2-1, 2-2, 2-3. It is a graph which shows the example of the temperature of the primary heat processing in this embodiment of Example 2-3, and secondary heat processing, and the profile of magnetic field intensity. It is the elements on larger scale of FIG. It is a graph which shows the example of the temperature of 1st heat processing and secondary heat processing in Example 3-1, and the profile of magnetic field intensity. It is a figure which shows the BH curve of the nanocrystal alloy core obtained in Example 3-1, 3-2. It is a graph which shows the example of the temperature of 1st heat processing and 2nd heat processing in Example 3-2, and the profile of magnetic field intensity. It is a graph which shows the example of the temperature of the primary heat treatment in this embodiment of Example 4, and secondary heat processing, and the profile of magnetic field intensity. FIG. 16 is a diagram showing a B-H curve of a nanocrystal alloy core obtained in Example 4. FIG. 16 is a diagram showing the impedance relative permeability μrz in the nanocrystal alloy core of Example 4. FIG. 16 is a diagram showing initial permeability frequency characteristics (the real part μ ′ of complex relative permeability) in the nanocrystal alloy core of Example 4. FIG. 16 is a diagram showing initial permeability frequency characteristics (imaginary part μ of complex relative permeability) in the nanocrystal alloy core of Example 4. FIG. 16 is a diagram showing a B-H curve before and after resin impregnation in the nanocrystal alloy core of Example 5. FIG. 16 is a diagram showing initial permeability frequency characteristics (the real part μ ′ of complex relative permeability) before and after resin impregnation in the nanocrystal alloy core of Example 5. FIG. 18 is a diagram showing initial permeability frequency characteristics (imaginary part μ ′ ′ of complex relative permeability) before and after resin impregnation in the nanocrystal alloy core of Example 5. It is a figure which shows the relationship of the frequency and impedance relative magnetic permeability (micro | micron | mu) rz which looked at each kind of heat processing in a magnetic field. It is a graph which shows the example of the temperature of the primary heat treatment and secondary heat treatment in this embodiment, and the profile of magnetic field intensity. It is the figure which showed the relationship between the temperature rising rate and the impedance relative magnetic permeability μrz for each frequency. It shows the relationship between the frequency and the real part μ 'of the complex relative permeability. The relationship between the frequency and the imaginary part μ ′ ′ of the complex relative permeability is shown. It is the figure which showed the relationship between the highest temperature of primary heat treatment, and impedance relative magnetic permeability murz for every measurement frequency. It shows the relationship between the frequency and the real part μ 'of the complex relative permeability. The relationship between the frequency and the imaginary part μ ′ ′ of the complex relative permeability is shown. It is the figure which showed the relationship between the frequency and the impedance relative magnetic permeability μrz for every maximum temperature to which a magnetic field is applied. It shows the relationship between the frequency and the real part μ 'of the complex relative permeability. The relationship between the frequency and the imaginary part μ ′ ′ of the complex relative permeability is shown. It is the figure which showed the relationship between the frequency and the impedance relative magnetic permeability μrz for every temperature-fall rate. It shows the relationship between the frequency and the real part μ 'of the complex relative permeability. The relationship between the frequency and the imaginary part μ ′ ′ of the complex relative permeability is shown. It is the figure which showed the relationship between the frequency and the impedance relative magnetic permeability μrz for each minimum temperature to which a magnetic field is applied. It shows the relationship between the frequency and the real part μ 'of the complex relative permeability. The relationship between the frequency and the imaginary part μ ′ ′ of the complex relative permeability is shown. It is the figure which showed the magnetic field intensity of secondary heat processing, and the relationship of impedance relative magnetic permeability (mu) rz for every measurement frequency. It shows the relationship between the frequency and the real part μ 'of the complex relative permeability. The relationship between the frequency and the imaginary part μ ′ ′ of the complex relative permeability is shown.

  When the heat treatment profile at the time of manufacturing the nanocrystal alloy core was examined in detail in order to further improve the characteristics of the nanocrystal alloy core, it is necessary to reduce the coercivity in order to reduce the temperature change of the magnetic permeability I found that. In order to reduce the coercivity, it was found that the uniformity of the temperature distribution inside the magnetic core when performing the heat treatment while applying the magnetic field is related. In addition, in order to obtain high permeability and high impedance relative permeability, it was found that temperature control in the process of nanocrystallization of an amorphous alloy is important. Based on these two findings, the inventor of the present application conceived a method of manufacturing a nanocrystal alloy core capable of reducing temperature fluctuation of permeability and / or obtaining high permeability and high impedance relative permeability. .

First Embodiment
Hereinafter, a first embodiment of the present disclosure will be described. The present embodiment relates to a nanocrystal alloy core, a core unit, and a method of manufacturing a nanocrystal alloy core in which the temperature change of permeability is small. According to the first embodiment, it is possible to establish a manufacturing method in which the coercive force Hc is stably reduced when obtaining a nanocrystalline alloy core having a high magnetic permeability and a low squareness ratio. By applying this manufacturing method, a nanocrystalline alloy core having a permeability μ (1 kHz) of 70,000 or more and a squareness ratio Br / Bm of 50% or less, and a nanocrystalline alloy core having a coercive force Hc of 1 A / m or less It is also possible to obtain

  Conventionally, a nanocrystal alloy core used for a current transformer or a common mode choke coil is required to have a high permeability and a low squareness ratio core having a large permeability μ and a small squareness ratio. However, in addition to these characteristics, the nanocrystal alloy core may need to have a small variation in permeability with respect to a temperature change in order to cope with the variation in the environment of the apparatus such as the operating temperature.

  As described above, in manufacturing a high permeability, low squareness magnetic core having a permeability μ (1 kHz) of 70,000 or more and a squareness ratio of 50% or less, the inventors of the present invention have the permeability μ (1 kHz) The characteristics at which the rate of temperature change at 25 ° C. and 100 ° C. is 15% or less were determined, and many studies were conducted. As a result, as shown in FIG. 1, the temperature change rate of the magnetic permeability μ (1 kHz) and the coercivity Hc are correlated, and in order to reduce the temperature change rate of the magnetic permeability μ (1 kHz) It turned out that it was necessary to make it smaller.

  Patent document 3 obtains an alloy magnetic core having a magnetic permeability μ (1 kHz) of 70,000 or more and a squareness ratio of 30% or less, which has similar characteristics, in terms of reducing the coercivity, as described in the specification (0018). As described above, it is suggested that the increase in coercivity can be suppressed by performing the primary heat treatment of nanocrystallization while maintaining the surface temperature of the alloy core at the crystallization start temperature + 100 ° C. or less. The method of heat treatment in a magnetic field disclosed in Patent Document 3 basically applies a magnetic field during primary heat treatment of nano crystallization.

  However, when the present inventors manufactured a magnetic core by the same method, the effect which can suppress the increase in the coercive force was not confirmed. This is considered to be due to the fact that the temperature control in the furnace is difficult because the nanocrystal alloy self-heats upon nanocrystallization.

  Then, the present inventors used the manufacturing method which performs the timing which applies a magnetic field not by the primary heat processing for nano crystallization but by the subsequent secondary heat processing like patent document 4 or patent document 5. FIG. However, it was still difficult to reduce the coercivity.

  Based on these studies, the present inventors have conceived of a method of producing a novel nanocrystal alloy core. A method of manufacturing a nanocrystalline alloy core according to a first embodiment of the present disclosure is a method of manufacturing a nanocrystalline alloy core, wherein a magnetic core of a wound or laminated amorphous alloy ribbon is nanocrystallized by heat treatment, A primary heat treatment step of raising the temperature from a temperature lower than the crystallization start temperature to a crystallization start temperature or higher in a non-magnetic field, and a secondary heat treatment step performed thereafter; A second temperature holding step of holding at a constant temperature of at least 200 ° C. in the magnetic field and less than the crystallization start temperature, and then a second temperature lowering step of lowering the temperature while applying the magnetic field in the direction orthogonal to the magnetic path. Have.

  Note that "hold at a constant temperature" in the secondary temperature holding step of the present application means that the temperature control means capable of setting the temperature of the heat treatment furnace holds the temperature at a constant temperature, and the heat treatment furnace controls the temperature according to the setting. It refers to the state of being The target whose temperature control means controls the temperature may be the temperature of the inner wall of the heat treatment furnace or the temperature of the magnetic core of the object to be heat treated. The temperature control means can use known ones.

  By applying this manufacturing method, a nanocrystal alloy core having a small coercive force can be obtained. The obtained nanocrystalline alloy core is, for example, one obtained by winding or laminating a nanocrystalline alloy ribbon, and has a permeability μ (1 kHz) of 70,000 or more and a squareness ratio Br / Bm of 50% or less It is also possible to obtain a magnetic core having a coercivity of 1.0 A / m or less. In addition, when the temperature is lowered while applying a magnetic field, a B-H curve (hysteresis loop) with excellent linearity can be obtained.

  Also, in the secondary temperature holding step, the coercive force can be further reduced by holding at a constant temperature of 200 ° C. or more and less than the crystallization start temperature even after applying a magnetic field. Specifically, a magnetic core having a coercivity of 0.9 A / m or less is obtained. On the other hand, after the application of the magnetic field, the impedance relative permeability μrz can be increased by lowering the temperature without maintaining the temperature at a constant temperature. When the impedance relative permeability μrz is high, characteristics preferable as a core for a common mode choke coil can be obtained. When holding at a constant temperature, holding at a temperature gradient of, for example, about ± 0.2 ° C./min is an equivalent range. Details will be described later.

  The reason why the coercivity is reduced by the above manufacturing method is presumed to be that magnetic anisotropy is once given in the direction orthogonal to the magnetic path to form a magnetic domain. That is, the magnetization process of the magnetic body includes the rotational component of the magnetic moment and the domain wall displacement component. Since the rotational component of the magnetic moment is oriented in a direction of magnetic anisotropy when the external magnetic field is removed, it ideally has no residual magnetization or coercivity. On the other hand, with regard to the domain wall displacement component, movement of the domain wall is pinned due to a defect inside the magnetic body, an impurity layer, surface roughness or the like, so that even if external magnetization is removed, it has finite residual magnetization and coercivity. When the magnetic domain is orthogonal to the magnetic path, the magnetization process when the operating magnetic field is applied to the magnetic path is dominated by the rotational component of the magnetic moment in each magnetic domain, and the ratio of the domain wall displacement component is relatively It becomes smaller. From this, it is estimated that the coercivity decreases when the magnetic anisotropy is imparted in the direction orthogonal to the magnetic path. Furthermore, by performing the secondary heat treatment in a state where the temperature distribution inside the magnetic core is small, the magnetic property becomes different at each part of the magnetic core, the linearity of the B-H curve becomes thin, and the coercivity increases. It is estimated that

  In the present application, as for the crystallization initiation temperature, an exothermic reaction due to the start of nanocrystallization is detected when the measurement conditions of differential scanning calorimetry (DSC: Differential Scanning Calorimetry) are carried out at a temperature rising rate of 10 ° C./min. Defined as temperature.

(Primary heat treatment)
The primary heat treatment includes a process of raising the temperature from a temperature lower than the crystallization start temperature to a temperature higher than the crystallization start temperature. The temperature for raising the temperature may be set in the range of 510 ° C. or more and 600 ° C. or less. When the heat treatment temperature is lower than 510 ° C. or higher than 600 ° C., the magnetostriction becomes large. If the heat treatment temperature is 550 ° C. or more, the magnetostriction can be further reduced. Specifically, it is possible to reduce the magnetostriction to 3 ppm or less, further to 2 ppm or less, and further to 1 ppm or less. If the heat treatment is performed at a temperature of 550 ° C. to 600 ° C., the coercivity tends to increase. However, in the second embodiment, the heat treatment method in a magnetic field that can reduce the coercivity is applied. Both of the magnetic forces can be reduced. Thereby, even if it impregnates resin, it can be set as the nanocrystal alloy core with a small characteristic change.

  In the primary heat treatment, it is not necessary to maintain the temperature at the highest reaching temperature, and even if the holding time at the highest temperature is 0 minutes (no holding time), nanocrystallization can be performed, but preferably, it is 5 minutes or more Set within the range of 24 hours or less. If the holding time is 5 minutes or more, it is easy to make the temperature of the entire alloy constituting the core uniform, and it is easy to make the magnetic characteristics uniform. On the other hand, when the holding time is longer than 24 hours, not only the productivity is deteriorated, but also the magnetic characteristics are easily deteriorated due to excessive growth of crystal grains or generation of nonuniform crystal grains.

  In the primary heat treatment, the temperature rises from a temperature lower than the crystallization start temperature to a higher temperature, but the temperature rise rate at the crystallization start temperature is a gradual temperature rise rate of 0.2 to 1.2 ° C./min. By raising the temperature, it is possible to suppress the formation of a coarse crystal grain size due to self-heating which occurs at the time of nanocrystallization, and stable nanocrystallization can be performed. In addition, since the magnetostriction can be reduced, a nanocrystal alloy core having a small change in characteristics can be obtained even by resin impregnation. The temperature may be increased relatively rapidly at a temperature rising rate of, for example, 3 to 5 ° C./min, up to a temperature 20 ° C. lower than the crystallization start temperature.

  Moreover, it is preferable to cool at a cooling rate of 1 to 5 ° C./min from the highest temperature to the holding temperature of the secondary heat treatment. After the secondary heat treatment, the magnetic core can be taken out to the atmosphere when the temperature is usually 100 ° C. or lower.

  Note that the temperature rise rate at the crystallization start temperature is the average temperature rise rate between the temperature 5 ° C. lower and the temperature 5 ° C. higher at the crystallization start temperature, that is, the average temperature rise rate at the temperature rise in the primary heat treatment step. Point to

(Secondary heat treatment)
In the secondary heat treatment step, the temperature maintained in the absence of a magnetic field in the secondary temperature holding step is a temperature of 200 ° C. or more and less than the crystallization start temperature, but is preferably 200 ° C. or more and 500 ° C. or less. The higher the holding temperature, the lower the magnetic permeability. Therefore, the magnetic permeability can be controlled by changing the holding temperature of the secondary heat treatment. However, at temperatures below 200 ° C., the effect of changing the permeability may not be sufficiently obtained. On the other hand, if the temperature is higher than 500 ° C., crystal grain growth of the nanocrystal phase is promoted, which may increase the coercivity. That is, by applying a magnetic field in the range of 200 ° C. to 500 ° C., it is easy to obtain a magnetic characteristic having a coercive force of 1.0 A / m.

  It is preferable that the time to hold at a constant temperature of 200 ° C. or more and less than the crystallization start temperature in the non-magnetic field is 1 minute or more. Hereinafter, the time to hold at a constant temperature may be referred to as actual holding time. In the present application, the “actual holding time” refers to the time from when the temperature of the magnetic core becomes the holding setting temperature until the application of the magnetic field is started. More specifically, it refers to the time from when the temperature of the magnetic core reaches a temperature range of ± 5 ° C. with respect to the set temperature of the magnetic core at which the application of the magnetic field is started until the application of the magnetic field is started.

  The actual holding time will be further described. In the temperature profile of the heat treatment shown in FIG. 2, the plotted temperature is a set temperature profile controlled by the temperature control means, and the actual core temperature may be different from the control temperature. Particularly in the cooling process, the cooling rate of the core tends to be slower than the cooling rate set in the heat treatment furnace. As a result of paying attention to the actual temperature of the magnetic core, the present inventors noted that, in addition to the temperature holding in the control of the temperature control means, the above-mentioned “temperature at which the magnetic core is constant (the magnetic core It has been found that it is preferable to apply “the time from when the application temperature of the magnetic field is started to the range of ± 5 ° C. with respect to the set temperature of) as the management target value. In the present application, in the method of measuring the temperature of the core at the time of measuring the actual holding time, the temperature was measured in a state in which the thermocouple is in direct contact with the core. However, in the manufacturing method of the present embodiment, it is not always necessary to measure the temperature of the core directly. In determining the temperature profile of heat treatment in the heat treatment furnace according to the manufacturing method of the present embodiment, if the conditions for securing a sufficient actual holding time are determined, the temperature of the core is not actually measured and manufactured. It is also good.

  By setting the actual holding time to 1 minute or more, the coercive force Hc can be sufficiently reduced. More preferably, the actual holding time is 5 minutes or more, and more preferably 10 minutes or more. Although the upper limit of the actual holding time is not particularly limited, if it is 10 hours or less, the time required for the heat treatment can be shortened, so that an increase in mass production cost can be suppressed.

  When it is desired to obtain a nanocrystal alloy core having a smaller coercive force, the secondary temperature holding step holds the core temperature at a constant temperature of 200 ° C. or more and less than the crystallization start temperature in the absence of a magnetic field. After reaching the holding temperature, it is preferable to hold at this temperature while applying a magnetic field in a direction orthogonal to the magnetic path, and then perform a second temperature lowering step. It is considered that the coercivity decreases as the B-H curve inclines as the time for applying the magnetic field is extended. When this manufacturing method is applied, in order to reduce the coercivity, the temperature of the magnetic core is kept within the range of ± 5 ° C. with respect to the temperature decrease start temperature in the secondary temperature holding step, and then held within that temperature range. It is preferable to set the time to one minute or more, and then apply a magnetic field in the direction orthogonal to the magnetic path while maintaining the temperature range. The holding time is preferably 5 minutes or more, more preferably 10 minutes or more.

  If it is desired to achieve both low coercivity and high impedance relative permeability μrz, the temperature is lowered after maintaining at a constant temperature of at least 200 ° C. and less than the crystallization start temperature in the absence of a magnetic field in the secondary heat treatment step. It is preferable to lower the temperature while applying a magnetic field in the direction orthogonal to the magnetic path from the start time.

In addition, as the nanocrystal alloy core to be used is larger, the cooling rate of the core tends to be slower than the cooling rate set in the heat treatment furnace. When the volume of the nanocrystal alloy core is less than 3000 mm ³ , the effect of reducing the coercive force by the production method of the present disclosure can be more easily obtained when the volume of the core is more than 3000 mm ³ . If the volume is 5000 mm ³ or more, it is still easy to obtain the effect of reducing the coercive force. The volume is an effective volume obtained by multiplying the volume calculated from the outer shape of the magnetic core by the space factor, and can also be determined by the product of the effective magnetic path length and the effective sectional area.

  The magnetic field applied in the cooling process of the secondary heat treatment is preferably applied at a magnetic field strength of 60 kA / m or more. Since the squareness ratio Br / Bm can be reduced, the coercive force Hc can be further reduced. Specifically, the coercive force Hc can be set to 1.0 A / m or less. In addition, it is easy to apply induced magnetic anisotropy under actual working conditions. A more preferable range of the magnetic field strength is 100 kA / m or more.

  The upper limit of the magnetic field strength is not particularly limited, but even if it exceeds 400 kA / m, the induced magnetic anisotropy is not further imparted, so it is preferable to set it to 400 kA / m or less. The time for applying a magnetic field is not particularly limited as long as it is in the above temperature range, but about 1 to 180 minutes is practical.

  When the temperature is lowered while applying the magnetic field, it is preferable to keep applying the magnetic field between the holding temperature and 200 ° C. As a result, it is possible to obtain a soft magnetic characteristic having high linearity and a slope of the B-H curve. It is more preferable that the lower limit temperature at which the magnetic field is continuously applied is up to 150 ° C.

  The direction of the applied magnetic field is perpendicular to the magnetic path direction. If it is a wound magnetic core, a magnetic field is applied in the height direction of the magnetic core. The application of the magnetic field may be by either a direct current magnetic field, an alternating current magnetic field, or a pulse magnetic field.

  By this heat treatment in a magnetic field, although the magnetic permeability is lowered, the residual magnetic flux density Br is lowered, Br / Bm can be made small, and a magnetic core which is less likely to generate biased magnetization can be obtained. For this reason, it is suitable for a magnetic core for a common mode choke coil or for a current transformer. In the present application, the saturation magnetic flux density Bm is defined as the magnetic flux density B (80) in the magnetic field H = 80 A / m.

  The primary heat treatment and the secondary heat treatment are preferably performed in a non-reactive atmosphere gas. In the case of heat treatment in nitrogen gas, sufficient permeability can be obtained, and nitrogen gas can be handled substantially as non-reactive gas. Inert gases can also be used as non-reactive gases. Heat treatment may also be performed in vacuum. Specifically, it is preferable to perform the primary heat treatment in an atmosphere having an oxygen concentration of 10 ppm or less. The coercivity can be further reduced.

(Nanocrystal alloy core)
A nanocrystalline alloy core according to a first embodiment of the present disclosure is a nanocrystalline alloy core in which a nanocrystalline alloy ribbon is wound or stacked, the frequency f = 1 kHz, the amplitude H = 0.05 amps / meter (A The permeability μ (1 kHz) measured at room temperature is 70,000 or more, the squareness ratio Br / Bm is 50 or less, and the coercivity is 1.0 A / m in a state where an alternating magnetic field of 1 / m) is applied. It is below. Preferably, the squareness ratio Br / Bm is 30% or less. Thereby, a nanocrystal alloy core having a temperature change rate at 25 ° C. and 100 ° C. of magnetic permeability μ (1 kHz) of 15% or less can be obtained.

  In addition, the nanocrystal alloy core according to the first embodiment of the present disclosure is excellent in impedance characteristics in that the impedance relative permeability μrz at 100 kHz is 48,000 or more. Also, high impedance relative permeability μrz can be obtained in a wide frequency range, such as 90,000 or more at 10 kHz and 8,500 or more at 1 MHz. Further, high impedance relative permeability μrz can be obtained in a wide frequency range, such as 100,000 or more at 10 kHz and 10,000 at 1 MHz. Furthermore, high impedance relative permeability μrz can be obtained in a wide frequency range of 105,000 or more at 10 kHz, 50,000 or more at 100 kHz, and 10,500 at 1 MHz.

  Thus, the reason for the large impedance ratio permeability μrz of the nanocrystal alloy core of the present disclosure is that when the coercive force is small, there are few domain wall displacement components in the magnetization process, so local anomalous eddy current loss due to domain wall motion can be reduced. As a result, since it can suppress that a core loss increases, it is guessed that it is because a high frequency characteristic can be improved.

  The above-mentioned magnetic core with high impedance relative permeability μrz is useful as a nanocrystal alloy core for a common mode choke coil. As a frequency band used as a common mode choke, an application capable of supporting low to high frequencies, specifically, an application capable of supporting 10 kHz to 1 MHz is required.

The characteristic index as a common mode choke often uses the impedance relative permeability μrz. The impedance relative permeability μrz is described, for example, in JIS C2531 (revised in 1999). The impedance relative permeability μrz can be considered as being equal to the absolute value of the complex relative permeability (μ′−iμ ′ ′) as shown in the following equation (1) (eg, “Point of selection of magnetic material , November 10, 1989, editor: Keizo Ota.
μrz = (μ ' ² + μ " ² ) ^1/2 (1)

  The real part μ ′ of the complex relative permeability in the above equation (1) represents a magnetic flux density component without phase lag with respect to the magnetic field, and generally corresponds to the magnitude of the impedance relative permeability μrz in the low frequency range. On the other hand, the imaginary part μ ′ ′ represents the magnetic flux density component including the phase delay with respect to the magnetic field, and corresponds to the loss of magnetic energy. If the impedance relative permeability μrz has a high value in a wide frequency band, it has excellent ability to absorb and remove common mode noise.

  In addition, the nanocrystalline alloy core of the present disclosure can be impregnated with a resin. Since the nanocrystalline alloy core becomes brittle during heat treatment for nanocrystallization, the core may be impregnated with a resin in order to enhance mechanical properties. At this time, when the resin is impregnated, the nanocrystal alloy ribbon is distorted, so that there is a problem in the design of characteristics that the impedance of the winding core changes and it does not meet the customer's requirements. In particular, common mode choke coils tend to emphasize impedance characteristics.

  Even if it impregnates resin, the nanocrystal alloy core of this indication can make change of an impedance characteristic small as much as possible. Also, similarly, the change of the B-H curve can be made as small as possible. As a resin to be impregnated, an epoxy resin, an acrylic resin or the like can be appropriately used. Moreover, it is common to use the volume of the resin solvent used when impregnating these resin as about 5 wt%-40 wt% with respect to the weight of resin.

(Core unit)
The nanocrystal alloy core according to the first embodiment of the present disclosure can be made into a core unit for a common mode choke coil, a current transformer, etc., for example, by winding or penetrating a conducting wire. It is particularly useful for common mode choke coils.

(Nano crystallization alloy)
As an amorphous alloy which can be nanocrystallized, for example, a general formula: (Fe _1-a M _a ) _{100-xyz-α-β-γ} Cu _x Si _y B _z M ′ _α M ′ ′ _β X _γ (atom (Wherein, M is Co and / or Ni, M ′ is at least one element selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V, Cr, Mn and W, M ′ ′ is at least one element selected from the group consisting of Al, platinum group elements, Sc, rare earth elements, Zn, Sn and Re, and X is from C, Ge, P, Ga, Sb, In, Be, As At least one element selected from the group consisting of: a, x, y, z, α, β and γ, respectively, wherein 0 ≦ a ≦ 0.5, 0.1 ≦ x ≦ 3, 0 ≦ y ≦ 30,0 Using an alloy having a composition represented by ≦ z ≦ 25,5 ≦ y + z ≦ 30, 0 ≦ α ≦ 20, 0 ≦ β ≦ 20 and 0 ≦ γ ≦ 20. Can. Preferably, in the above general formula, a, x, y, z, α, β and γ are respectively 0 ≦ a ≦ 0.1, 0.7 ≦ x ≦ 1.3, 12 ≦ y ≦ 17, 5 ≦ It is a range that satisfies z ≦ 10, 1.5 ≦ α ≦ 5, 0 ≦ β ≦ 1, and 0 ≦ γ ≦ 1.

  The alloy of the said composition is fuse | melted above melting | fusing point, and a long amorphous alloy ribbon (thin strip) can be obtained by quenching and solidifying by a single roll method.

  By performing the above-mentioned primary heat treatment on an amorphous alloy ribbon, a nanocrystal ribbon can be obtained. In the nanocrystallized alloy, at least 50% by volume or more, preferably 80% by volume or more is occupied by fine crystal grains having an average particle size of 100 nm or less at the maximum dimension. Further, the portion of the alloy other than the fine crystal grains is mainly amorphous. The proportion of fine grains may be substantially 100% by volume.

The ratio of fine crystal grains is an arbitrary straight line of length Lt drawn in the TEM photograph of each sample, and the total length Lc of the portion where each straight line intersects with the fine crystal grains is determined, and the crystal grains along each straight line The ratio Ll = Lc / Lt is calculated, and this operation is repeated five times to obtain the average of Ll. Here, the ratio of fine crystal grains Vl = Vc / Vt (Vc is the sum of the volumes of microcrystalline grains and Vt is the volume of the sample) approximates V1 ≒ Lc ³ / Lt ³ = Ll ³ Dealing with.

  As the amorphous alloy ribbon used in the method of manufacturing a nanocrystalline alloy core of the present disclosure, one having a thickness of 7 μm or more and 30 μm or less is preferably used. If it is less than 7 μm, the mechanical strength of the ribbon is insufficient and it is easily broken during handling. When it exceeds 30 μm, it is difficult to stably obtain an amorphous state. In addition, when the amorphous alloy ribbon is used as a core for high frequency applications after nanocrystallization, an eddy current is generated in the ribbon, but the loss due to the eddy current becomes larger as the ribbon becomes thicker.

  A more preferable thickness of the amorphous alloy ribbon is 7 μm or more and 15 μm or less. If the thickness is 15 μm or less, generation of eddy current in high frequency applications can be suppressed, and impedance relative permeability μrz can be improved. In addition, by using a ribbon having a thickness of 7 μm to 15 μm, the nanocrystalline alloy core of the present disclosure having a coercive force of 0.65 A / m or less can be obtained.

  The width of the amorphous alloy ribbon obtained by roll cooling is preferably 10 mm or more from the practical shape of the core. Since it is possible to reduce costs by slitting (cutting) a wide alloy ribbon, a wide width is preferable, but a width of 250 mm or less is preferable for stable production of the alloy ribbon. In order to manufacture more stably, 70 mm or less width is more preferable.

Next, an embodiment of a method of manufacturing a core for a current transformer according to the present disclosure will be described. First, a ribbon-like amorphous alloy to be a soft magnetic material layer is formed from a molten alloy having the above composition by a known liquid quenching method (super-quenching method) such as a single roll method or a twin roll method. The circumferential speed of the cooling roll can be set, for example, to about 15 to 50 m / sec. The cooling roll may be formed of pure copper having good thermal conductivity, or a copper alloy such as Cu-Be, Cu-Cr, Cu-Zr, Cu-Zr-Cr or the like. For mass production, the chill roll can be water cooled. Depending on the cooling rate, differences in the formation of the amorphous structure of the alloy may occur so that the temperature change of the roll is kept small in the formation of the amorphous alloy ribbon. The thickness t of the amorphous alloy ribbon is a value obtained by weight conversion. For example, the weight M of a sample of 2 m (longitudinal direction) x 50 mm (width direction) is measured from a long amorphous alloy ribbon, and the density d [kg / m ³ ] is a dry density measurement by constant volume expansion method The thickness t [m] = M / ((2 × 50 ⁻³ ) × d) can be calculated by (for example, measurement by using an AccuPic II 1340 series manufactured by Shimadzu Corporation).

  The obtained amorphous alloy ribbon can be slit if necessary and used as a ribbon having a desired width.

  By winding or laminating the amorphous alloy ribbon, a structure having a ring shape can be produced. The ring-like structure (core material) produced in this manner has a structure in which a plurality of amorphous alloy layers are stacked. There may be a slight gap or other material between each amorphous alloy layer. The volume percentage of the amorphous alloy layer in the core material is, for example, about 70% to 90%.

<Permeability>
The term "permeability" in the present application is synonymous with "relative permeability". The permeability measured at room temperature in the state where an alternating magnetic field of frequency f = 1 kHz and amplitude H = 0.05 amperes / meter (A / m) is applied is expressed as μ (1 kHz).

  Also, the impedance permeability is expressed as μrz. The impedance permeability was measured by an impedance / gain phase analyzer (model number 4194A) manufactured by Keysight Corporation. The insulation coated conductor was penetrated through the center of the winding core and connected to the input / output terminal for measurement.

  In the following examples, a core material formed by winding an amorphous alloy ribbon is used. However, the present disclosure is not limited to such an example.

Example 1
The alloy melt consisting of 1% of Cu, 3% of Nb, 35.5% of Si, 6.5% of B, and the balance of Fe and unavoidable impurities in atomic percent is quenched by the single roll method, and the width is 50 mm, A 14 μm thick Fe-based amorphous alloy ribbon was obtained. The Fe-based amorphous alloy ribbon was slit (cut) to a width of 6 mm, and wound to an outer diameter of 21.0 mm and an inner diameter of 11.8 mm to produce a wound magnetic core (height 6 mm). The volume of the magnetic core is 1421 mm ³ . The onset of crystallization of this alloy was 500 ° C. as measured by differential scanning calorimetry (DSC).

  With respect to the produced core, primary heat treatment and secondary heat treatment were performed with the profiles of temperature and magnetic field application shown in FIG. The temperature shown here is the temperature of the atmosphere in the heat treatment furnace controlled by a temperature controller (KP 1000C manufactured by CHINO corporation). The temperature to be controlled is the temperature of the outer periphery in the furnace.

  In the primary heat treatment, first, the temperature was raised from room temperature to 450 ° C. in 90 minutes (heating rate 4.8 ° C./min), held for 30 minutes, and then raised to 580 ° C. in 240 minutes (heating rate 0. It was set to 5 ° C / min. Thereafter, the temperature is maintained at 580 ° C. for 60 minutes, and then the temperature is lowered to 400 ° C. (a temperature decrease rate of 1.4 ° C./min) over 130 minutes.

  Thereafter, secondary heat treatment was performed. First, the setting of the heat treatment furnace was set to hold at 400 ° C. for 90 minutes. The “actual holding time” defined in the present application (in this example, the time from 405 ° C. to the start of application of the magnetic field (start of temperature decrease)) was 60 minutes. The processes up to here including the process of the primary heat treatment were performed in the absence of a magnetic field. Thereafter, while applying a magnetic field of 159.5 kA / m, the temperature was lowered to 150 ° C. over 150 minutes. The applied direction of the magnetic field was the width direction of the alloy ribbon, ie, the height direction of the core. After that, it was allowed to cool in a non-magnetic field. The heat treatment in the magnetic field was performed in an atmosphere having an oxygen concentration of 10 ppm or less (2 ppm).

  Thus, the nanocrystal alloy core of this example was obtained. This nanocrystalline alloy core had a permeability μ (1 kHz) of 100,000 and a squareness ratio Br / Bm of 12.7%. The magnetostriction was 1 ppm or less.

  FIG. 3 is a diagram showing a B-H curve of a nanocrystal alloy core obtained by the present embodiment. A nanocrystalline alloy core having a coercivity of 1 A / m or less (0.64 A / m) was obtained.

(Comparative example 1)
FIG. 4 is a diagram showing a B-H curve of a nanocrystal alloy core for comparison. In the secondary heat treatment, the used nanocrystalline alloy core is manufactured with the same profile of temperature and magnetic field application as that of FIG. 2 except that a period for holding the temperature is not provided as setting of the heat treatment furnace. That is, it was manufactured in the same manner as the nanocrystal alloy core of Example 1 except that the temperature was maintained at a constant temperature of 200 ° C. or more and the crystallization start temperature or less. It is understood that the B-H curve of this nanocrystalline alloy core spreads to the left and right, and the coercive force is 2.19 A / m, which is larger than that of the nanocrystalline alloy core of Example 1.

(Examples 2-1 to 2-3)
The relationship between the actual retention time and the coercivity was examined in yet another embodiment. The alloy melt consisting of 1% of Cu, 3% of Nb, 35.5% of Si, 6.5% of B, and the balance of Fe and unavoidable impurities in atomic percent is quenched by the single roll method, and the width is 50 mm, A 14 μm thick Fe-based amorphous alloy ribbon was obtained. The Fe-based amorphous alloy ribbon was slit (cut) to a width of 20 mm, and wound to an outer diameter of 22 mm and an inner diameter of 14 mm to produce a wound magnetic core (height 20 mm). The volume of the core is 4522 mm ³ . The onset of crystallization of this alloy was 500 ° C. as measured by differential scanning calorimetry (DSC).

  In the heat treatment furnace, as shown in FIG. 5, a plurality of wound magnetic cores are arranged in the axial direction. The heat treatment furnace 10 in a magnetic field has a configuration in which the wound cores 6 are arranged side by side in a container 3 having a heater 4. A solenoid coil 5 is installed outside the container 3. The wound magnetic cores are arranged coaxially through the nonmagnetic holder 2 (SUS 304) in the hole on the inner diameter side. The solenoid coil 5 can apply a magnetic field in the vertical direction (the height direction of the winding core) of the magnetic path of the winding core. The same nonmagnetic spacer 1 is disposed every 10 successive wound magnetic cores. A thermocouple was interposed between the fifth and sixth magnetic cores from the end, and the temperature of the magnetic cores on both sides was measured.

  In this state, the primary heat treatment and the secondary heat treatment were performed with the profiles of temperature and magnetic field application shown in FIG. The temperature indicated by the thin broken line is the set temperature of the heat treatment furnace.

  In the primary heat treatment, first, the temperature is raised to 470 ° C. in 100 minutes (heating rate 4.5 ° C./min), held for 30 minutes, and then raised to 560 ° C. in 100 minutes (heating rate 0.9 ° C. / Min) was set. Thereafter, the temperature is maintained at 560 ° C. for 30 minutes, and then the temperature is lowered to 350 ° C. (temperature lowering rate of 4.7 ° C./min) in 40 minutes.

  Thereafter, secondary heat treatment was performed. First, it was set to hold at 350 ° C. for 140 minutes. The processes up to here including the process of the primary heat treatment were performed in the absence of a magnetic field. Thereafter, while applying a magnetic field of 53.1 kA / m, the temperature was lowered to 100 ° C. in 90 minutes. The applied direction of the magnetic field was the width direction of the alloy ribbon, ie, the height direction of the core.

  In FIG. 6, the temperature indicated by the solid line is the temperature of the magnetic core of Example 2-1.

  FIG. 7 is an enlarged view of the heat treatment time in the range of 400 ° C. to 500 ° C. in FIG. The temperature at which the temperature starts to fall while applying a magnetic field is from 350 ° C, but 25 minutes before that, it becomes 355 ° C which is 350 ° C to 5 ° C higher. That is, the actual retention time defined in the present disclosure is 25 minutes. The coiled core obtained by this has a relatively small value of coercive force of 1.29 A / m, as shown by the solid line in FIG.

  Moreover, the nanocrystal alloy core was manufactured like Example 2-1 except having changed the installation place in the furnace of a magnetic core. In FIG. 6, FIG. 7, the temperature shown with a dashed-dotted line is the temperature of the magnetic core of this embodiment (Example 2-2). A magnetic field is applied from 355.degree. C., and a temperature drop is started, but reaches 7.7.degree. C. from 360.degree. That is, the actual retention time defined in the present disclosure is 7.7 minutes. Further, as shown by the broken line in FIG. 8, the coercivity of this wound core was 2.19 A / m. In addition, a nanocrystal alloy core was manufactured in the same manner as in Example 2-1 except that the actual holding time was increased. In FIG. 9, the temperature indicated by a two-dot broken line is the temperature of the magnetic core of the present embodiment (Example 2-3).

  FIG. 10 is a diagram showing the temperature of the magnetic core in the range of 400 ° C. to 500 ° C. for the heat treatment time. The temperature at which the magnetic field starts to be applied is from 350 ° C., but 45 minutes before that, it becomes 355 ° C. which is 350 ° C. to 5 ° C. That is, the actual holding time defined in the present disclosure is 45 minutes. The obtained wound magnetic core substantially overlapped the B-H curve of the nanocrystal alloy core of FIG. 8 in which the actual holding time was 25 minutes. The coercivity of this nanocrystalline alloy core is a relatively small value of 1.17 A / m. When the actual holding time is compared with the nanocrystal alloy core of 7.7 minutes, 25 minutes, and 45 minutes, the coercivity decreases as the actual holding time increases.

  In the present embodiment, the coercive force is not less than 1 A / m because the strength of the applied magnetic field is a relatively low value of less than 60 kA / m, but as described above, the longer the actual holding time However, the coercivity tends to decrease. However, in the nanocrystal alloy core with an actual holding time of 25 minutes and 45 minutes, the coercivity does not change so much, and as shown in FIG. 8, since the B-H curve is almost the same, the applied magnetic field It is understood that, even if the strength of the above is less than 60 kA / m, the effect of making the coercivity sufficiently small can be obtained by setting the actual holding time to 10 minutes or more.

(Example 3)
The relationship between the actual holding time and the coercivity was investigated with a nanocrystal alloy core manufactured under the condition that the strength of the applied magnetic field was 60 kA / m or more. The alloy melt consisting of 1% of Cu, 3% of Nb, 35.5% of Si, 6.5% of B, and the balance of Fe and unavoidable impurities in atomic percent is quenched by the single roll method, and the width is 50 mm, A 14 μm thick Fe-based amorphous alloy ribbon was obtained. The Fe-based amorphous alloy ribbon was slit (cut) to a width of 8 mm, and wound to an outer diameter of 96.5 mm and an inner diameter of 88.5 mm to produce a wound magnetic core (height 8 mm). The volume of the core is 9294 mm ³ . The onset of crystallization of this alloy was 500 ° C. as measured by differential scanning calorimetry (DSC). In the same manner as in Example 2, a plurality of wound magnetic cores were arranged side by side in the axial direction in the heat treatment furnace.

  In the primary heat treatment, first, the temperature is raised from room temperature (25 ° C.) to 450 ° C. in 100 minutes (heating rate 4.3 ° C./min), held for 30 minutes, and then raised to 580 ° C. in 240 minutes (raised The temperature rate was set to 0.5 ° C./min. Thereafter, the temperature is maintained at 580 ° C. for 60 minutes, and then the temperature is decreased to 420 ° C. (temperature decrease rate 1.1 ° C./min) over 140 minutes.

  Thereafter, secondary heat treatment was performed. First, the heat treatment furnace was set to hold at 420 ° C. for 50 minutes. The “actual holding time” (in the present embodiment, the time from 425 ° C. to 420 ° C.) defined in the present application was 11 minutes as shown in FIG. The processes up to here including the process of the primary heat treatment were performed in the absence of a magnetic field. Thereafter, while applying a magnetic field of 159.5 kA / m, the temperature was lowered to room temperature over 320 minutes. The applied direction of the magnetic field was the width direction of the alloy ribbon, ie, the height direction of the core. After that, it was allowed to cool in a non-magnetic field. The heat treatment in the magnetic field was performed in an atmosphere having an oxygen concentration of 10 ppm or less (2 ppm).

  Thereby, the nanocrystal alloy core of the present embodiment (Example 3-1) was obtained. As indicated by the broken line in FIG. 12, the B-H curve was very excellent in linearity and small in coercive force. The coercivity of this nanocrystalline alloy core is a small value of 0.71 A / m. The nanocrystal alloy core had a permeability μ (1 kHz) of 92,000 and a squareness ratio Br / Bm of 10.7%. The magnetostriction was 3 ppm or less.

  In addition, a nanocrystal alloy core was manufactured so as to increase the actual holding time.

  The primary heat treatment was performed on the wound magnetic core in the same manner as in Example 3-1. As in Example 3-1, after performing the same setting up to the step of holding at 580 ° C. for 60 minutes, the temperature was lowered to 420 ° C. (temperature lowering rate of 1.8 ° C./min) in 90 minutes.

  Thereafter, secondary heat treatment was performed. The heat treatment furnace was set to hold at 420 ° C. for 100 minutes. The “actual holding time” defined in the present application (in the present embodiment, the time from 425 ° C. to the application of the magnetic field (starting temperature decrease)) was 52 minutes as shown in FIG. The processes up to here including the process of the primary heat treatment were performed in the absence of a magnetic field. Thereafter, while applying a magnetic field of 159.5 kA / m, the temperature was lowered to room temperature over 240 minutes. The applied direction of the magnetic field was the width direction of the alloy ribbon, ie, the height direction of the core. After that, it was allowed to cool in a non-magnetic field. The heat treatment in the magnetic field was performed in an atmosphere having an oxygen concentration of 10 ppm or less (2 ppm).

  Thereby, the nanocrystal alloy core of this embodiment (Example 3-2) was obtained. As shown by the solid line in FIG. 12, the B-H curve was very excellent in linearity and small in coercive force. The coercivity of this nanocrystalline alloy core is an extremely small value of 0.57 A / m. The nanocrystalline alloy core had a permeability μ (1 kHz) of 104,000 and a squareness ratio Br / Bm of 8.9%. The magnetostriction was 3 ppm or less.

  When the actual holding time is compared with the nanocrystal alloy core of 11 minutes and 52 minutes, the coercivity decreases as the actual holding time increases. In this embodiment, since the strength of the applied magnetic field is a value of 60 kA / m or more, a nanocrystal alloy core having a coercivity of 1 A / m or less (0.71 A / m) is obtained even with an actual holding time of 11 minutes. It was done.

(Example 4)
In the secondary heat treatment, after holding at a constant temperature of 200 ° C. or more and less than the crystallization start temperature in the above-mentioned no magnetic field, hold at this temperature while applying a magnetic field in a direction orthogonal to the magnetic path A nanocrystal alloy core was manufactured using a manufacturing method in which the temperature is lowered while applying a magnetic field in the direction orthogonal to the magnetic path.

  The alloy melt consisting of 1% of Cu, 3% of Nb, 35.5% of Si, 6.5% of B, and the balance of Fe and unavoidable impurities in atomic percent is quenched by the single roll method, and the width is 50 mm, A 14 μm thick Fe-based amorphous alloy ribbon was obtained. The Fe-based amorphous alloy ribbon was slit (cut) to a width of 6.5 mm, and wound to an outer diameter of 20 mm and an inner diameter of 10 mm to produce a magnetic core material (height 6.5 mm). The onset of crystallization of this alloy was 500 ° C. as measured by differential scanning calorimetry (DSC).

  Primary heat treatment was performed on the produced magnetic core with the profile of temperature and magnetic field application shown in FIG. In the primary heat treatment, first, the temperature is raised to 450 ° C. in 90 minutes (heating rate 5.0 ° C./min), held for 30 minutes, and then raised to 580 ° C. in 240 minutes (heating temperature 0.5 ° C. / Min) was set. Thereafter, the temperature is maintained at 580 ° C. for 60 minutes, and then the temperature is lowered to 350 ° C. (temperature lowering rate 2.5 ° C./min) over 130 minutes.

  Thereafter, the magnetic core was subjected to secondary heat treatment. First, it was set to hold at 350 ° C. for 60 minutes. The processes up to here including the process of the primary heat treatment were performed in the absence of a magnetic field.

  Then, it hold | maintained at 350 degreeC, applying the magnetic field of 159.5 kA / m. The holding time (hereinafter referred to as holding time in a magnetic field) was 0 minutes, 20 minutes, and 40 minutes. The application direction of the magnetic field was the width direction of the alloy ribbon, ie, the height direction of the magnetic core. The heat treatment in the magnetic field was performed in an atmosphere having an oxygen concentration of 10 ppm or less (2 ppm). The profiles of temperature and magnetic field application shown in FIG. 14 correspond to those in which the holding time in the magnetic field is 0 minutes.

  Thereafter, while applying a magnetic field of 159.5 kA / m, temperature was set to fall at a temperature lowering rate of 1.7 ° C./min between 350 ° C. and room temperature. The application direction of the magnetic field was the width direction of the alloy ribbon, ie, the height direction of the magnetic core. The heat treatment in the magnetic field was performed in an atmosphere having an oxygen concentration of 10 ppm or less (2 ppm). Thereby, the nanocrystal alloy core of this embodiment was obtained.

  As indicated by the solid line in FIG. 15, the B-H curve was very excellent in linearity and small in coercive force. The coercivity of the nanocrystal alloy core is extremely small, such as 0.92 A / m, 0.87 A / m, and 0.80 A / m, when the holding time in a magnetic field is 0 minutes, 20 minutes, and 40 minutes. is there. Table 2 shows measured values of impedance relative permeability μrz at frequencies from 1 kHz to 10 MHz. Further, FIG. 16 is a measurement result corresponding to Table 2.

  The coercive force Hc tends to be smaller as the holding time in the magnetic field is longer. However, even in the case of a nanocrystal alloy core having a holding time of 0 minutes in a magnetic field, the coercive force Hc is sufficiently small at 1 A / m or less (0.92 A / m).

  On the other hand, the impedance relative permeability μrz tends to be smaller as the holding time in the magnetic field is longer. The impedance relative permeability μrz can be considered as being equal to the absolute value of the complex relative permeability (μ'-i '' ') as described above.

  FIG. 17 shows the result of measurement of the real part μ ′ of the complex relative permeability of the obtained nanocrystal alloy core. FIG. 18 shows the results of measurement of the imaginary part '' 'of the complex relative magnetic permeability.

  As the holding time in the magnetic field becomes longer in the range of 0 to 40 minutes, the value of the real part μ 'at 10 kHz or higher tends to decrease. In the frequency characteristic of the imaginary part μ ′ ′, the peak is shifted to the lower frequency side as the holding time in the magnetic field is longer. This is the main factor to increase the impedance relative permeability μrz of 100 kHz in the present embodiment as the holding time in the magnetic field becomes longer.

  From these experimental results, when it is desired to obtain a nanocrystal alloy core having a still smaller coercive force, in the secondary heat treatment, after holding at a constant temperature of 200 ° C. or more and less than the crystallization start temperature in no magnetic field, It is understood that it is preferable to apply the manufacturing method of holding at this temperature while applying a magnetic field in a direction orthogonal to the path and then lowering the temperature while applying a magnetic field in a direction orthogonal to the magnetic path.

  When it is desired to make small coercivity and high impedance relative magnetic permeability μrz compatible, the secondary heat treatment is performed at a constant temperature of 200 ° C. or more in the absence of a magnetic field and less than the crystallization start temperature, and then for the magnetic path. It is understood that it is preferable to apply a manufacturing method in which the temperature is lowered while applying the magnetic field in the direction perpendicular to the magnetic path without applying the magnetic field in the direction perpendicular to the magnetic path without applying the magnetic field.

(Example 5)
FIG. 19 to FIG. 21 show that the nano-crystalline alloy core of the present embodiment is impregnated with a resin, and the influence on the magnetic characteristics at that time is examined.

  The nanocrystalline alloy core obtained in Example 1 was impregnated with a resin. The resin used was an epoxy resin. The resin was diluted with an organic solvent, the magnetic core was immersed, and the magnetic core was impregnated with the resin.

  FIG. 19 shows B-H curves of the nanocrystal alloy core of the present embodiment before and after the resin impregnation. Almost all B-H curves overlap in all loops, and B-H curves do not change even if resin impregnation is performed. Table 3 shows measured values of residual magnetic flux density Br, coercivity Hc, and squareness ratio. The residual magnetic flux density Br, the coercive force Hc, and the rate of change of squareness ratio before and after the resin impregnation was about 3%, and it was found that there was almost no change.

  FIG. 20 and FIG. 21 show the measurement results of permeability frequency characteristics (the real part μ ′ of complex relative permeability and the imaginary part μ ′ of complex relative permeability) before and after resin impregnation. Also, Table 4 shows measured values of the real part μ ′ and the imaginary part μ ′ ′ of the complex relative permeability at 10 kHz, 100 kHz, 1 MHz, and 10 MHz in FIGS.

  The real part μ ′ and the imaginary part μ ′ ′ of the complex relative permeability hardly change before and after the resin impregnation, and the change rate is 2% or less at any frequency of 10 kHz to 10 MHz, particularly 100 kHz real number The change rate of the part μ ′ and the imaginary part μ ′ ′ is further smaller, and both are 0.5% or less.

  That is, the nanocrystal alloy core of this embodiment has a small rate of change in impedance permeability even when impregnated with a resin.

  As described above, the nanocrystal alloy core of the present embodiment can minimize changes in B-H curve and impedance characteristics even when impregnated with a resin, so product design relating to these characteristics is easy.

Second Embodiment
A second embodiment of the present disclosure will be described. The present embodiment relates to a nanocrystal alloy core having high permeability and impedance ratio permeability at 1 MHz or less, a core unit, and a method of manufacturing the nanocrystal alloy core. According to the present embodiment, it is possible to establish a manufacturing method capable of obtaining a nanocrystal alloy core having high impedance relative permeability μrz. In addition, it is possible to provide a nanocrystalline alloy core having a high impedance relative permeability μrz. This nanocrystal alloy core can be applied as a core for a common mode coil excellent in the ability to absorb and remove common mode noise.

  The present inventors first studied heat treatment methods in various magnetic fields. As a result, by applying the heat treatment patterns in the magnetic field of the following (1) to (3), it was possible to obtain a prospect of obtaining a nanocrystal alloy core having a high impedance relative permeability μrz.

(1) Heat treatment in a later stage magnetic field The heat treatment in a later stage magnetic field means the following heat treatment.

  Amorphous magnetic core material consisting of amorphous alloy ribbon capable of nano-crystallization is subjected to primary heat treatment in which the temperature is raised from the temperature lower than the crystallization start temperature to the crystallization start temperature or more in the absence of a magnetic field to perform nanocrystallization. A heat treatment having a heat treatment pattern in a magnetic field which performs a secondary heat treatment in which a magnetic field is applied in a direction perpendicular to the magnetic path at a temperature lower than the crystallization start temperature.

(2) Heat treatment in magnetic field during temperature rise 1
The heat treatment 1 in the magnetic field during temperature rising means the following heat treatment.

  An amorphous magnetic core material composed of an amorphous alloy ribbon capable of nanocrystallization is subjected to primary heat treatment in which the temperature is raised from a temperature lower than the crystallization start temperature to a crystallization start temperature or more to perform nanocrystallization. During the temperature rise period which does not exceed 50 ° C. high temperature of the crystallization start temperature including at least a part of the temperature range from 50 ° C. low temperature of crystallization start temperature to 20 ° C. high temperature of crystallization start temperature with scanning calorimeter A heat treatment having a heat treatment pattern in a magnetic field which applies a magnetic field in a direction perpendicular to the magnetic path in a temperature range of.

(3) Heat treatment 2 in magnetic field during heating (corresponds to the manufacturing method of Patent Document 3)
The heat treatment 2 in the magnetic field during temperature rising means the following heat treatment.

  An amorphous magnetic core material made of an amorphous alloy ribbon capable of nanocrystallization is subjected to a primary heat treatment in which the temperature is raised from a temperature lower than the crystallization start temperature to a crystallization start temperature or more to perform nanocrystallization. The magnetic field in the direction perpendicular to the magnetic path within 10 minutes to 60 minutes, limited to within the temperature range during the temperature rising period corresponding to the high temperature of 25 ° C. of the crystallization start temperature to the high temperature of 60 ° C. of the crystallization start temperature. Heat treatment with heat treatment pattern in magnetic field to apply

  Next, since the impedance relative permeability μrz is increased or decreased depending on the thickness of the amorphous alloy ribbon to be used, the ribbons having the same thickness (18 μm in thickness) are used in the heat treatment pattern in the magnetic field of the above (1) to (3) The nanocrystal alloy core was fabricated and evaluated at a frequency of 1 kHz to 10 MHz.

  First, the evaluation results of the nanocrystal alloy core obtained by the heat treatment pattern in the magnetic field described in (3) above will be described. This nanocrystal alloy core is different from the nanocrystal alloy core described in Patent Document 3 in that the thickness of the ribbon is changed from 13 μm to 18 μm. As the thickness of the ribbon is increased, the value of the impedance relative permeability μrz is smaller than the value described in Patent Document 3. Specifically, the impedance relative permeability μrz was less than 48,000 at a frequency of 100 kHz.

  Next, evaluation results of the nanocrystal alloy core obtained by the heat treatment pattern in the magnetic field of the above (1) and (2) will be described. As shown in FIG. 22, the nanocrystal alloy core obtained by the heat treatment 1 in the magnetic field during temperature raising in (2) has an impedance ratio higher than that of the nanocrystal alloy core obtained by the heat treatment in the subsequent magnetic field of (1). The permeability μrz was small.

  That is, among the heat treatment patterns in the magnetic field of (1) to (3), the nanocrystal alloy core obtained by the heat treatment in the subsequent magnetic field of (1) has the largest impedance relative permeability μrz at a frequency of 1 kHz to 10 MHz. showed that.

  On the basis of this result, the present inventors diligently reviewed the temperature profile in order to identify the technical point for improving the impedance relative permeability μrz when applying the heat treatment in the subsequent magnetic field. As a result, the following four technical means were found.

  (A: First technical means) A nanocrystalline alloy core is manufactured by applying heat treatment in a later stage magnetic field, and further, in the step of primary heat treatment, the temperature rising rate at the crystallization start temperature is 1.0 ° C./min. Less than. By applying this manufacturing method, the impedance relative permeability μrz of the nanocrystal alloy core obtained by the heat treatment in the subsequent magnetic field can be increased. In the present application, the temperature rising rate at the crystallization start temperature is the average temperature rising rate between the temperature 5 ° C. lower and the temperature 5 ° C. higher at the crystallization start temperature, that is, the average temperature at the temperature rise in the primary heat treatment step. It shall refer to a temperature rising rate.

  (B: Second technical means) A heat treatment in a later stage magnetic field is applied to manufacture a nanocrystal alloy core, and further, in the primary heat treatment step, the maximum temperature is made more than 550 ° C. and not more than 585 ° C. By applying this manufacturing method, the impedance relative permeability μrz of the nanocrystal alloy core obtained by the heat treatment in the subsequent magnetic field can be increased.

  (C: Third technical means) A nanocrystalline alloy core is manufactured by applying a heat treatment in a later stage magnetic field, and further, in the secondary heat treatment step, the maximum temperature for applying a magnetic field is 200 ° C. or more and less than 400 ° C. I assume. By applying this manufacturing method, the impedance relative permeability μrz of the nanocrystal alloy core obtained by the heat treatment in the subsequent magnetic field can be increased.

  (D: Fourth technical means) A heat treatment in a later stage magnetic field is applied to manufacture a nanocrystal alloy core, and further, in a secondary heat treatment step, a magnetic field is applied while decreasing the temperature at an average speed of 4 ° C./min or less Do. By applying this manufacturing method, the impedance relative permeability μrz of the nanocrystal alloy core obtained by the heat treatment in the subsequent magnetic field can be increased.

  The features of (a) to (d) can be combined. The impedance relative permeability μrz is further enhanced by combining two or more of the features (a) to (d), or by combining two or more of the features (a) to (d) and the features of the first embodiment. be able to.

  Hereinafter, a method of manufacturing a nanocrystal alloy core according to a second embodiment of the present disclosure, and a nanocrystal alloy core will be described in detail.

(Amorphous alloy ribbon capable of nanocrystallization)
As in the first embodiment, an Fe-based amorphous alloy ribbon capable of nanocrystallization can be used.

As an Fe-based amorphous alloy ribbon, for example, a general formula: (Fe _1-a M _a ) _{100-xyz-α-β-γ} Cu _x Si _y B _z M ′ _α M ” _β X _γ (atomic%) (wherein , M is Co and / or Ni, M ′ is at least one element selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V, Cr, Mn and W, and M ′ ′ is Al And at least one element selected from the group consisting of platinum group elements, Sc, rare earth elements, Zn, Sn and Re, and X is selected from the group consisting of C, Ge, P, Ga, Sb, In, Be and As At least one element, a, x, y, z, .alpha., .Beta. And .gamma. , 5 ≦ y + z ≦ 30, 0 ≦ α ≦ 20, 0 ≦ β ≦ 20, and 0 ≦ γ ≦ 20. it can. Preferably, in the above general formula, a, x, y, z, α, β and γ are respectively 0 ≦ a ≦ 0.1, 0.7 ≦ x ≦ 1.3, 12 ≦ y ≦ 17, 5 ≦ It is a range that satisfies z ≦ 10, 1.5 ≦ α ≦ 5, 0 ≦ β ≦ 1, and 0 ≦ γ ≦ 1.

  The long amorphous alloy ribbon can be obtained by melting the alloy of the said composition above melting | fusing point and quenching-solidifying with a single roll method.

  The amorphous alloy is nano-crystallized by performing heat treatment on the amorphous alloy ribbon by raising the temperature from a temperature lower than the crystallization start temperature to a crystallization start temperature or higher in a non-magnetic field. At least 50% by volume, and even 80% by volume, of the nanocrystallized alloy is occupied by fine crystal grains having an average particle size of 100 nm or less measured at the maximum dimension. Further, the portion of the alloy other than the fine crystal grains is mainly amorphous. The proportion of fine grains may be substantially 100% by volume.

  Thinning of the ribbon is important in order to obtain a nanocrystalline alloy core having a high impedance relative permeability μrz. Therefore, the preferred thickness of the amorphous alloy ribbon is 15 μm or less. If the thickness is 15 μm or less, generation of eddy current in high frequency applications can be suppressed, and impedance relative permeability μrz can be improved. A further preferred thickness is 13 μm or less. The lower limit of the thickness is not particularly limited, but when producing an amorphous alloy ribbon by a single roll method, if it is 7 μm or more, continuous casting is easy to perform, which is preferable in production.

Next, a method of manufacturing the amorphous alloy ribbon will be described. First, a ribbon-shaped amorphous alloy is formed from a molten alloy having the above composition by a known liquid quenching method (super-quenching method) such as a single roll method or a twin roll method. The circumferential speed of the cooling roll can be set, for example, to about 15 to 50 m / sec. The cooling roll may be formed of pure copper having good thermal conductivity, or a copper alloy such as Cu-Be, Cu-Cr, Cu-Zr, Cu-Zr-Cr or the like. For mass production, the chill roll can be water cooled. Depending on the cooling rate, differences in the formation of the amorphous structure of the alloy may occur so that the temperature change of the roll is kept small in the formation of the amorphous alloy ribbon. The thickness t of the amorphous alloy ribbon is a value obtained by weight conversion. For example, the weight M of a 2 m (longitudinal direction) x 50 mm (width direction) sample is measured from a long amorphous alloy ribbon, and the density d [kg / m ³ ] is a dry density measurement by a constant volume expansion method (for example, The thickness t [m] = M / ((2 × 50 ⁻³ ) × d) can be calculated by the measurement using an AccuPic II 1340 series manufactured by Shimadzu Corporation).

  An amorphous core material can be obtained by winding or laminating the amorphous alloy ribbon. The amorphous core material may have a slight gap or other substance between each alloy layer. The volume space factor of the amorphous alloy ribbon in the amorphous core material is, for example, 70% to 90%.

  The amorphous alloy ribbon is subjected to heat treatment in a subsequent magnetic field to be nanocrystallized to obtain a nanocrystalline alloy having a permeability μ (1 kHz) of 70,000 or more and a square Br / Bm of 30% or less.

  As in the first embodiment, the crystallization start temperature is determined by the start of nanocrystallization when the measurement conditions of differential scanning calorimetry (DSC: Differential Scanning Calorimetry) are performed at a temperature rising rate of 10 ° C./min. Defined as the temperature at which an exothermic reaction is detected.

  The heat treatment in the subsequent magnetic field of the present disclosure will be described below. The heat treatment in the subsequent magnetic field has a primary heat treatment for nanocrystallization and a secondary heat treatment for heating in a magnetic field for adjusting the magnetic characteristics. The temperature described in the second embodiment indicates the set temperature of the furnace.

(Primary heat treatment)
The primary heat treatment includes a process of raising the temperature from a temperature lower than the crystallization start temperature to a temperature higher than the crystallization start temperature. The maximum temperature in the primary heat treatment may be set in the range of 510 ° C. or more and 600 ° C. or less. If the maximum temperature is lower than 510 ° C. or higher than 600 ° C., the magnetostriction becomes large. When the magnetostriction is large, when the magnetic core is impregnated with a resin, the magnetic characteristics largely change and it is difficult to obtain desired characteristics. It is not necessary to hold the temperature at the highest temperature, and it can be nano-crystallized even at 0 minutes (no hold time). Preferably, the holding time is set in the range of 5 minutes to 24 hours. If the heat treatment time is 5 minutes or more, it is easy to make the temperature of the entire alloy constituting the magnetic core uniform, and it is easy to make the magnetic characteristics uniform. On the other hand, when the heat treatment time is longer than 24 hours, not only the productivity is deteriorated, but also the magnetic characteristics are easily deteriorated due to excessive growth of crystal grains or generation of nonuniform crystal grains.

  The present inventors have found a first technical means capable of improving the above-mentioned impedance relative permeability μrz in this primary heat treatment.

  The first technical means is to provide a gradual temperature rise rate of less than 1.0 ° C./min at the crystallization start temperature in the step of raising the temperature from a temperature lower than the crystallization start temperature to at least the crystallization start temperature. . In the present invention, the temperature rising rate at the crystallization start temperature refers to the average temperature rising rate between the temperature 5 ° C. lower and the temperature 5 ° C. higher than the crystallization start temperature. The reason is described below.

  Since the reaction of crystallization is an exothermic reaction, the temperature of the core material may rise instantaneously near the crystallization start temperature. At this time, since the nanocrystals are unevenly coarsened in the ribbon, a uniform magnetic anisotropy is not formed, and the impedance relative permeability μrz of the magnetic core is likely to be lowered. By reducing the temperature rising rate at the crystallization start temperature to less than 1.0 ° C./min, such an instantaneous temperature rise can be suppressed, and the impedance permeability can be improved. The temperature may be raised relatively rapidly at a temperature rising rate of, for example, 1.0 or more until the temperature lower by 20 ° C. than the crystallization start temperature. In addition, as another effect, it is possible to stably perform nanocrystallization, and as a result, it is possible to reduce the magnetostriction, so that it is possible to obtain a nanocrystal alloy core having a small characteristic change even when impregnated with a resin.

  The impedance relative permeability μrz can be further improved when the temperature rising rate at the crystallization start temperature is 0.9 ° C./min or less, further 0.85 or less. The lower limit of the temperature rising rate is not particularly limited, but is preferably 0.1 ° C./min or more, and more preferably 0.2 ° C./min or more, in order to shorten the manufacturing process.

  Also, as the second technical means, the impedance relative permeability μrz can be improved by setting the maximum temperature in this primary heat treatment to more than 550 ° C. and not more than 585 ° C. I found it. The reasons are described below.

  When the maximum temperature in the primary heat treatment exceeds 585 ° C., the crystal grain size of the nanocrystals is enlarged and the coercivity of the core material is rapidly increased. A magnetic core material having a large coercivity contains a large amount of domain wall displacement components in the magnetization process, and it is presumed that an eddy current (anomalous eddy current) is generated due to the domain wall motion, and the impedance relative permeability μrz decreases. Conversely, when the maximum temperature in the primary heat treatment is 550 ° C. or lower, the coercivity of the core material decreases but the magnetostriction increases but the magnetic domain structure is disturbed by the influence of external stress, and the impedance relative permeability μrz decreases. Be done.

  Moreover, if it is this temperature range, there also exists an effect which can make magnetostriction small. Specifically, it is possible to reduce the magnetostriction to 3 ppm or less, further to 2 ppm or less, and further to 1 ppm or less. The lower limit value of the maximum temperature is preferably 555 ° C. or higher. Further, the upper limit value of the maximum temperature is preferably 583 ° C. or less. Thereby, the impedance relative permeability μrz can be further enhanced.

(Secondary heat treatment)
After the primary heat treatment, a secondary heat treatment is performed by applying a magnetic field in a direction perpendicular to the magnetic path at a temperature lower than the crystallization start temperature. The application of the magnetic field can be performed while keeping the temperature constant, or can be performed while raising or lowering the temperature. When a magnetic field is applied while the temperature is lowered, the hysteresis BH curve is inclined, and the inclined portion is particularly preferable because it becomes linear.

  The direction of the applied magnetic field is perpendicular to the magnetic path direction. In the case of a wound magnetic core, a magnetic field is applied in the height direction of the magnetic core (axial direction of the wound magnetic core). The application of the magnetic field may be by either a direct current magnetic field, an alternating current magnetic field, or a pulse magnetic field.

  By this heat treatment in a magnetic field, although the magnetic permeability is lowered, the residual magnetic flux density Br is lowered, Br / Bm can be made small, and a magnetic core which is less likely to generate biased magnetization can be obtained. For this reason, it is suitable for a magnetic core for a common mode choke coil.

  When the maximum temperature for applying a magnetic field is in the range of 200 ° C. or more and less than the crystallization start temperature, the magnetic permeability is easily changed, and the magnetic characteristics necessary for a coil for a common mode choke coil can be easily obtained. When a magnetic field is applied at a temperature higher than the crystallization start temperature, crystal grain growth of the nanocrystal phase is promoted, which may increase the coercive force. It is further preferable to set the maximum temperature to which the magnetic field is applied to 500 ° C. or less (and below the crystallization start temperature).

  In this case, the temperature is preferably lowered to at least 100 ° C. in a magnetic field. Thereby, the impedance relative permeability μrz can be increased. In addition, it is possible to obtain soft magnetic characteristics with high linearity and a slope of the B-H curve.

  The magnetic field is preferably applied at a magnetic field strength of 50 kA / m or more. Thereby, the impedance relative permeability μrz can be increased. A more preferable range is 60 kA / m or more, and further 150 kA / m or more. The upper limit of the magnetic field strength is not particularly limited, but it is practical to set it to 500 kA / m or less from the relationship of the amount of current that can be supplied to the magnetic field generating coil. Moreover, the time to apply a magnetic field is not particularly limited, but about 1 to 180 minutes is practical.

  The primary heat treatment and the secondary heat treatment can be performed continuously. That is, after the primary heat treatment is performed to the highest temperature, the temperature may be lowered to the temperature of the secondary heat treatment, and the magnetic field may be applied as it is to perform the secondary heat treatment.

  Of course, the primary heat treatment and the secondary heat treatment can also be performed separately. That is, after performing the primary heat treatment, the temperature may be lowered to the temperature of the secondary heat treatment, and then the temperature may be raised to the temperature of the secondary heat treatment to apply a magnetic field.

  The present inventors have found a third technical means capable of improving the impedance relative permeability μrz in this secondary heat treatment. The third technical means is to set the maximum temperature for applying a magnetic field to 200 ° C. or more and less than 400 ° C. The reason is described below.

  The impedance relative permeability μrz exhibits a maximum value at low frequencies near 1 kHz, and starts to decrease as the frequency increases, and finally decreases along the Snoek limit line. At frequencies above 2 MHz, the impedance relative permeability μrz is along the Snoek limit and does not depend on the maximum temperature at which the magnetic field is applied. However, as described later, the impedance relative permeability μrz in the vicinity of 1 to 100 kHz changes in value depending on the maximum temperature at which a magnetic field is applied. The reason for this is that the magnetic anisotropy along the height direction of the core material changes, so that the slope of the BH curve becomes large when the maximum temperature at which the magnetic field is applied is low. When the maximum temperature at which a magnetic field is applied is 200 ° C. or more and less than 400 ° C., the impedance relative permeability μrz of 100 kHz exhibits a sufficiently high value. The maximum temperature for applying a magnetic field is preferably 370 ° C. or less. The impedance relative permeability μrz can be further improved.

  Moreover, the present inventors discovered the 4th technical means which can improve impedance relative magnetic permeability murz in this secondary heat treatment. A fourth technical means is to apply a magnetic field while lowering the temperature at an average speed of 4 ° C./min or less when applying a magnetic field in the secondary heat treatment.

  The reason why the impedance relative permeability μrz is improved by this is unclear, but when the magnetic core material is rapidly cooled while applying a magnetic field, the temperature distribution is generated in the magnetic core material during heat treatment, and therefore, the magnetic core material is It is presumed that the phenomenon occurs that the magnetic anisotropy is different depending on the place and the uniform magnetic domain is not formed.

  The average velocity of 4 ° C./min or less when applying the magnetic field in the secondary heat treatment refers to the average velocity during the temperature decrease to 100 ° C. from the temperature at which the application of the magnetic field is started.

  In addition, it is preferable to make temperature-fall rate in 100 degreeC into 4 degrees C / min or less. The impedance relative permeability μrz can be further increased. In the present invention, the temperature lowering rate at 100 ° C. refers to the average temperature lowering rate between 105 ° C. and 95 ° C.

  The primary heat treatment and the secondary heat treatment are preferably performed in a non-reactive atmosphere gas. For example, when heat treatment is performed in nitrogen gas, sufficient permeability can be obtained, and nitrogen gas can be treated as substantially non-reactive gas. Inert gases can also be used as non-reactive gases. Heat treatment can also be performed in a vacuum.

  The primary heat treatment is preferably performed in an atmosphere having an oxygen concentration of 10 ppm or less. The coercive force of the obtained magnetic core can be reduced.

(Nanocrystal alloy core)
The nanocrystal alloy core of the present disclosure has a permeability μ (1 kHz) of 70 measured at room temperature in the state where an alternating magnetic field of frequency f = 1 kHz and amplitude H = 0.05 amperes / meter (A / m) is applied. It can be made more than 2,000 cores.

  Moreover, it is also possible to obtain a nanocrystal alloy core having an impedance relative permeability μrz of 48,000 or more at 100 kHz by applying the above-described manufacturing method. It is also possible to obtain high impedance ratio permeability μrz in a wide frequency range, such as 90,000 or more at 10 kHz and 8,500 or more at 1 MHz. Furthermore, it is also possible to obtain a nanocrystal alloy core having an impedance relative permeability μrz of 49,000 or more, and further 50,000 or more at 100 kHz. In addition, it is also possible to obtain an impedance relative permeability μrz of 95,000 or more, or even 100,000 or more at 10 kHz. Also, at 1 MHz, it is possible to obtain an impedance relative permeability μrz of 8,800 or more, or even 9,000 or more.

(Core unit)
The nanocrystal alloy core of the present disclosure can be made into a core unit for a common mode choke coil, for example, by winding or penetrating a conducting wire.

<Impedance relative permeability μrz, real part μ ′ of complex relative permeability, imaginary part μ ′ ′>
The measurement of the impedance relative permeability μrz, the real part μ ′ of the complex relative permeability and the imaginary part μ ′ ′ was performed under conditions of an oscillation level of 0.5 V and an average 16 using an HP 4194A manufactured by Agilent Technologies. . The insulation coated conducting wire was penetrated to the center part of the toroidal core, connected to the input / output terminal, and measured.

  Hereinafter, the manufacturing method will be described in more detail.

(Example 6)
The alloy melt consisting of 1% of Cu, 3% of Nb, 35.5% of Si, 6.5% of B, and the balance of Fe and unavoidable impurities in atomic percent is quenched by the single roll method, and the width is 50 mm, A 14 μm thick Fe-based amorphous alloy ribbon was obtained. The Fe-based amorphous alloy ribbon was slit (cut) to a width of 6.5 mm, and wound to an outer diameter of 20 mm and an inner diameter of 10 mm to produce a magnetic core material (height 6.5 mm). The onset of crystallization of this alloy was 500 ° C. as measured by differential scanning calorimetry (DSC).

  With respect to the manufactured magnetic core, primary heat treatment and secondary heat treatment were performed with the profiles of temperature and magnetic field application shown in FIG. In the primary heat treatment, first, the temperature is raised to 450 ° C. in 90 minutes (heating rate 5.0 ° C./min), held for 30 minutes, and then raised to 580 ° C. in 240 minutes (heating temperature 0.5 ° C. / Min) Thereafter, the temperature was maintained at 580 ° C. for 60 minutes, and then the temperature was lowered to 350 ° C. (a temperature decrease rate of 2.5 ° C./min) over 130 minutes.

  Thereafter, the core material was subjected to secondary heat treatment. First, it was kept at 350 ° C. for 60 minutes. The processes up to here including the process of the primary heat treatment were performed in the absence of a magnetic field. Thereafter, while applying a magnetic field of 159.5 kA / m from 350 ° C. to room temperature, the temperature was lowered at a temperature decrease rate of 1.7 ° C./min. The application direction of the magnetic field was the width direction of the alloy ribbon, ie, the height direction of the magnetic core. The heat treatment in the magnetic field was performed in an atmosphere having an oxygen concentration of 10 ppm or less (2 ppm). Thereby, the nanocrystal alloy core of this embodiment was obtained. This nanocrystal alloy core had an impedance relative permeability μrz of 126, 524 at 10 kHz, 50, 644 at 100 kHz, and 9, 938 at 1 MHz. The permeability μ (1 kHz) was 100,000 and the squareness ratio Br / Bm was 12.7%.

(Example 7)
With respect to the profiles of the temperature and magnetic field application shown in FIG. 23, the temperature rise rate when raising the temperature from 450 ° C. to 580 ° C. is changed in the range of 0.5 ° C./min to 4.4 ° C./min. The influence on μrz was examined.

  Specifically, the heating time from 450 ° C. to 580 ° C. is set to 240 minutes (heating rate 0.5 ° C./min), 180 minutes (heating rate 0.8 ° C./min), 120 minutes (The temperature rising rate was 1.1 ° C./min), 60 minutes (the temperature rising rate 2.2 ° C./min), and 30 minutes (the temperature rising rate 4.4 ° C./min). The magnetic core material was subjected to heat treatment in a subsequent magnetic field in the same manner as in Example 6 except for the above.

  FIG. 24 is a diagram showing the relationship between the temperature rise rate and the impedance relative permeability μrz for each frequency. Table 5 shows the numerical values. As shown in FIG. 24 and Table 5, the impedance relative permeability μrz is increased by setting the temperature raising rate to a low rate (less than 1.0 ° C./min). The impedance relative permeability μrz at 100 kHz is 50,000 or more in both measured values of the heating rate of 0.8 ° C./min and 0.5 ° C./min, and is almost the same value. If the temperature rise rate is slow, the production time will be longer, so when obtaining a high impedance ratio of permeability μrz at 100 kHz, the temperature rise rate around 0.4 ° C / min (0.4 ° C / min or more and 0.9 ° C / It is preferable to manufacture in less than min.

  Also, when obtaining high impedance relative permeability μrz at 1 MHz or 10 MHz, the impedance relative permeability μrz of 0.5 ° C./min is higher than 0.8 ° C./min, so that it is around 0.5 ° C./min. It is preferable to manufacture at a temperature rising rate (0.3 ° C./min or more and 0.7 ° C./min or less).

  The nanocrystalline alloy core having a heating rate of 0.5 ° C./min had a permeability μ (1 kHz) of 134,766 and a squareness ratio Br / Bm of 29.6%. The nanocrystalline alloy core having a heating rate of 0.8 ° C./min had a permeability μ (1 kHz) of 137, 116 and a squareness ratio Br / Bm of 32.8%.

  FIG. 25 shows the relationship between the frequency and the real part μ ′ of the complex relative magnetic permeability, for the nanocrystal alloy core obtained in Example 7. The nanocrystal alloy core obtained at a heating rate of less than 1 ° C./min (0.5 ° C./min, 0.8 ° C./min) is 10 kHz compared to that obtained at a slower heating rate. At the above frequencies, the decrease in the real part μ ′ is small. In addition, when the heating rate is 0.5 ° C./min and the real part μ ′ of 0.8 ° C./min, both show substantially the same value in all frequency ranges.

  FIG. 26 shows the relationship between the frequency and the imaginary part μ ′ ′ of the complex relative magnetic permeability, as in FIG. The nanocrystal alloy core obtained at a heating rate of less than 1 ° C./min (0.5 ° C./min, 0.8 ° C./min) has an imaginary number compared to that obtained at a slower heating rate. The peak of the part μ ′ ′ is on the high frequency side. Specifically, the nanocrystal alloy core having a heating rate of less than 1 ° C./min has a smaller imaginary part μ ′ ′ at a frequency of 2 kHz or more and less than 50 kHz as compared to that obtained at a slower heating rate. However, the imaginary part μ ′ ′ becomes larger at a frequency of 50 kHz or more. In addition, when the heating rate is 0.5 ° C./min and 0.8 ° C./min, the real part μ 'is almost the same in all frequency ranges. This phenomenon is the main factor to increase the impedance relative magnetic permeability μrz at 100 kHz according to the present embodiment when the temperature rising rate at the time of temperature rising from 450 ° C. to 580 ° C. is less than 1.0 ° C./min. .

  In addition, in nanocrystal alloys with a heating rate of 0.5 ° C./min and 0.8 ° C./min, the frequency characteristics are almost the same for both real part μ ′ and imaginary part μ ′ ′. It can be seen that it is easy to produce a nanocrystalline alloy having a stable impedance relative permeability μrz by making the value of 1 ° C./min or less.

(Example 8)
The maximum temperature in the temperature and magnetic field application profiles shown in FIG. 23 was changed in the range of 500 ° C. to 600 ° C., and the influence on the impedance relative permeability μrz was examined. Specifically, the maximum temperatures were 500 ° C., 520 ° C., 540 ° C., 560 ° C., 580 ° C., 590 ° C., and 600 ° C. The magnetic core material was subjected to heat treatment in a subsequent magnetic field in the same manner as in Example 6 except for the above. The time to reach from 450 ° C. to the maximum temperature was 4 hours.

  FIG. 27 is a diagram showing the relationship between the maximum temperature of the primary heat treatment and the impedance relative permeability μrz for each measurement frequency. Table 6 shows the numerical values. As shown in FIG. 27 and Table 6, the nanocrystal alloy core obtained at the maximum temperature of 580 ° C. in the primary heat treatment has a large impedance relative permeability μrz, and its value is 50,000 or more at 100 kHz (50, 690). Next, a nanocrystal alloy core having a maximum temperature of 560 ° C. having a high impedance relative permeability μrz is 49,000 or more (49,540).

  Furthermore, the impedance relative permeability μrz is 48, 198 at 100 kHz, which is slightly lower than that at 560 ° C., at a maximum temperature of 540 ° C. The impedance maximum permeability μrz is 39,136 at the maximum temperature of 590 ° C., and drops sharply with respect to the value of 580 ° C. (50,690). From this point, when the maximum temperature of the primary heat treatment is in the range of more than 550 ° C. and 585 ° C. or less, an impedance relative permeability μrz of 49,000 is easily obtained. If the temperature is 555 ° C. or more and 590 ° C. or less, an impedance relative permeability μrz of 49000 can be easily obtained.

  The nanocrystal alloy core having a maximum temperature of 560 ° C. had a permeability μ (1 kHz) of 143,248 and a squareness ratio Br / Bm of 28.3%. The nanocrystal alloy core having a maximum temperature of 580 ° C. had a permeability μ (1 kHz) of 134,766 and a squareness ratio Br / Bm of 29.6%.

  FIG. 28 shows the relationship between the frequency and the real part μ ′ of the complex relative magnetic permeability, for the nanocrystal alloy core obtained in Example 8. The nanocrystal alloy core obtained with the maximum temperature in the step of the primary heat treatment at more than 550 ° C. and not more than 585 ° C. (560 ° C., 580 ° C.) was obtained with a large real part μ ' .

  FIG. 29 shows the relationship between the frequency and the imaginary part μ ′ ′ of the complex relative magnetic permeability, as in FIG. Similar to FIG. 28, the nanocrystal alloy core obtained with the maximum temperature of more than 550 ° C. and not more than 585 ° C. (560 ° C., 580 ° C.) has a large imaginary part μ ′ ′ in the range of 10 kHz or more.

  In addition, as shown in FIG. 28, the nanocrystal alloy core obtained with the maximum temperature in the step of primary heat treatment as 540 ° C. also has the same real part μ 'as the nanocrystal alloy core obtained as 560 ° C. and 580 ° C. Although the value is large, as shown in FIG. 29, the value of the imaginary part μ ′ ′ is 100 kHz and slightly smaller than that at 560 ° C. and 580 ° C. This phenomenon is the main factor that increases the impedance relative permeability μrz at 100 kHz according to the present embodiment when the maximum temperature in the primary heat treatment step is 550 ° C. to 585 ° C. or less (560 ° C., 580 ° C.). .

(Example 9)
With respect to the profiles of the temperature and magnetic field application shown in FIG. 23, the temperature range to which the magnetic field is applied in the secondary heat treatment was changed, and the influence on the impedance relative permeability μrz was examined. Specifically, the maximum temperature at which a magnetic field is applied in the secondary heat treatment is 350 ° C., 400 ° C., 450 ° C., 500 ° C., and the magnetic field is applied and cooled to room temperature. The Fe-based amorphous alloy ribbon used had a thickness of 10.6 μm. The magnetic core material was subjected to heat treatment in a subsequent magnetic field in the same manner as in Example 6 except for the above.

  FIG. 30 is a diagram showing the relationship between the frequency and the impedance relative permeability μrz for each temperature range to which a magnetic field is applied. Table 7 shows the numerical values. As shown in FIG. 30 and Table 7, when the temperature range to which the magnetic field is applied is limited to a low range in the secondary heat treatment, the impedance relative permeability μrz at 100 kHz is increased. The impedance relative permeability μrz has a value of 66, 003 for which the maximum temperature is 350 ° C. Looking at frequencies other than 100 kHz, the impedance relative permeability μrz increases as the applied temperature range decreases at 2 MHz or less, and the impedance relative permeability μrz decreases as the applied temperature range decreases at frequencies above 2 MHz. There is a tendency to

  In addition, the nanocrystal alloy core of the present embodiment in which the maximum temperature is 350 ° C. has an impedance relative permeability μrz at 10 kHz of 120,000 or more (129, 625). Also, the impedance relative permeability μrz at 1 MHz is 13,000 or more (13, 488). The nanocrystalline alloy core having a maximum temperature of 350 ° C. at which the magnetic field was applied in the secondary heat treatment had a permeability μ (1 kHz) of 135.998 and a squareness ratio Br / Bm of 20.8%.

  FIG. 31 shows the relationship between the frequency and the real part μ ′ of the complex relative magnetic permeability, for the nanocrystal alloy core obtained in Example 9. The nanocrystal alloy core obtained with the maximum temperature when applying the magnetic field in the secondary heat treatment as 350 ° C. has a large real part μ 'at 100 kHz or less, compared with that obtained at other maximum temperatures. But at frequencies above 100 kHz it gets smaller.

  FIG. 32 shows the relationship between the frequency and the imaginary part μ ′ ′ of the complex relative magnetic permeability, as in FIG. 31. The nanocrystal alloy core obtained at 350 ° C. as the maximum temperature at which a magnetic field is applied in the secondary heat treatment has a large imaginary part μ ′ ′, especially from 100 kHz, as compared with those obtained at other maximum temperatures. The difference in value increases over the following frequencies. This phenomenon is a main factor that increases the impedance relative permeability μrz at 100 kHz according to the present embodiment when the maximum temperature for applying a magnetic field in the secondary heat treatment is 350 ° C.

  In addition, the influence on the impedance relative permeability μrz by reducing the thickness of the ribbon was investigated. The nanocrystal alloy core obtained in Example 6 (thin strip thickness 14 μm, temperature range for applying a magnetic field is 350 ° C. or less only) has an impedance ratio permeability μrz of 126, 524 at 10 kHz, 50 at 100 kHz, It is 9,938 at 644 and 1 MHz. On the other hand, the nanocrystal alloy core obtained in the present embodiment (thin ribbon 10.6 μm, temperature range for applying magnetic field is the same at 350 ° C. or less only) is 129,625 at 10 kHz, 66,003 at 100 kHz. , 13 488 at 1 MHz. The impedance relative permeability μrz is higher in the nanocrystal alloy core of the present embodiment having a ribbon thickness of 10.6 μm even at frequencies of 1 kHz and 10 MHz.

(Example 10)
With respect to the profiles of the temperature and magnetic field application shown in FIG. 23, the magnetic field is applied while lowering the temperature in the secondary heat treatment, and the temperature decrease rate at that time is in the range of 4.4 ° C./min to 1.0 ° C./min. Then, the influence on the impedance relative permeability μrz was examined.

  FIG. 33 is a diagram showing the relationship between the frequency and the impedance relative permeability μrz for each temperature decrease rate. Table 8 shows the numerical values. As shown in FIG. 33 and Table 8, in the present embodiment, the temperature drop rate during application of the magnetic field is 3.0 ° C./min, 1.7 ° C./min, and 1.0 ° C./min. The impedance relative permeability μrz in the above is 50,000 or more (50, 770, 50, 690, 52, 194). Also, although the impedance relative permeability μrz at 10 kHz is the highest at 134 ° 326 at a temperature drop rate of 3.0 ° C./min, it is at least 11,500 (134, 326, 124, 167, 125, 205). Also, the impedance relative permeability μrz at 1 MHz is 10,000 or more (10, 041, 10, 151, 10, 793) in all cases.

  Further, the nanocrystalline alloy core having a temperature decrease rate of 3.0 ° C./min had a permeability μ (1 kHz) of 147, 915 and a squareness ratio Br / Bm of 36.6%. The nanocrystalline alloy core having a temperature lowering rate of 1.7 ° C./min had a permeability μ (1 kHz) of 134,776 and a squareness ratio Br / Bm of 29.6%. Further, the nanocrystalline alloy core having a temperature lowering rate of 1.0 ° C./min had a magnetic permeability μ (1 kHz) of 125, 205 and a squareness ratio Br / Bm of 20.8%.

  FIG. 34 shows the relationship between the frequency and the real part μ ′ of the complex relative magnetic permeability, for the nanocrystal alloy core obtained in Example 10. The nanocrystal alloy core obtained at the above-mentioned temperature lowering rate of 4 ° C./min or less (3.0 ° C./min, 1.7 ° C./min, 1.0 ° C./mi) exhibits substantially the same frequency characteristics. Moreover, these nanocrystalline alloy cores have larger values of the real part μ ′ in the range of 5 kHz or more than those obtained at a temperature lowering rate of 4.4 ° C./min.

  FIG. 35 shows the relationship between the frequency and the imaginary part μ ′ ′ of the complex relative magnetic permeability, as in FIG. As the temperature decrease rate slows down, the imaginary part μ ′ ′ value frequency characteristic has its peak shifted to the high frequency side, provided that the temperature decrease rate was obtained at 3.0 ° C./min to 1.0 ° C./min. The nanocrystal alloy core exhibits substantially the same frequency characteristics on the high frequency side from about 80 kHz.

  When the temperature decrease rate while applying the magnetic field is 4 ° C./min or less, the value of the imaginary part μ ′ ′ at a frequency of 80 kHz or more increases, which mainly increases the impedance relative permeability μrz of the present embodiment. It is a cause.

(Example 11)
With respect to the profiles of temperature and magnetic field application shown in FIG. 23, in the secondary heat treatment, the magnetic field is applied while lowering the temperature, and the minimum temperature when applying the magnetic field is changed in the range of 100 ° C. to 300 ° C. The influence on the permeability μrz was investigated. Specifically, the minimum temperature at the time of applying a magnetic field was 100 ° C., 200 ° C., 250 ° C., and 300 ° C.

  FIG. 36 is a diagram showing the relationship between the frequency and the impedance relative permeability μrz at each lowest temperature of the secondary heat treatment. Table 9 shows the numerical values. As shown in FIG. 36 and Table 9, the nanocrystal alloy core obtained at a minimum temperature of 100 ° C. when applying a magnetic field has an impedance relative permeability μrz of at least 50,000 (50, 690) at 100 kHz. It is. The impedance relative permeability μrz at 10 kHz is 12,000 or more (124, 167). Also, the impedance relative permeability μrz at 1 MHz is 10,000 or more (10, 151) in all cases.

  The nanocrystal alloy core having a minimum temperature of 100 ° C. for applying a magnetic field had a permeability μ (1 kHz) of 134,766 and a squareness ratio Br / Bm of 29.6%.

  FIG. 37 shows the relationship between the frequency and the real part μ ′ of the complex relative magnetic permeability, for the nanocrystal alloy core obtained in Example 11. In the secondary heat treatment, the lower the lowest temperature when applying the magnetic field, the larger the real part μ 'tends to be at a frequency of 10 kHz or more.

  FIG. 38 shows the relationship between the frequency and the imaginary part μ ′ ′ of the complex relative magnetic permeability, as in FIG. Similarly, the lower the lowest temperature when applying the magnetic field, the more the imaginary part μ ′ ′ tends to increase at a frequency of 10 kHz or higher. This phenomenon is a main factor in that the impedance relative permeability μrz at 100 kHz in the present embodiment is increased as the minimum temperature at the time of applying a magnetic field is lower in the secondary heat treatment.

(Example 12)
With respect to the profiles of temperature and magnetic field application shown in FIG. 23, in the secondary heat treatment, the strength of the applied magnetic field is changed in the range of 39.9 kA / m to 319.2 kA / m to influence the impedance relative permeability μrz Examined. Specifically, the strengths of the applied magnetic field were 39.9 kA / m, 79.8 kA / m, and 319.2 kA / m.

  FIG. 39 is a diagram showing the relationship between the applied magnetic field strength and the impedance relative permeability μrz for each measurement frequency. Table 10 shows the numerical values. As shown in FIG. 39 and Table 10, the impedance relative permeability μrz tends to increase as the strength of the applied magnetic field increases. The nanocrystal alloy core obtained by applying a magnetic field of 79.8 kA / m has an impedance ratio of 30% or more at frequencies of 1 kHz, 10 kHz, 100 kHz, 1 MHz and 10 MHz with respect to that of 39.9 kA / m. There is an increase in the permeability μrz. On the other hand, when comparing nanocrystalline alloy cores obtained by applying magnetic fields of 79.8 kA / m and 319.2 kA / m, the increase in impedance relative permeability μrz is 6% or less at any frequency. The impedance relative permeability μrz at 100 kHz is 48,000 or more (48, 677, 50, 690) for both 79.8 kA / m and 319.2 kA / m nanocrystal alloy cores. From these points, it is understood that a sufficiently high impedance ratio permeability μrz can be obtained if the strength of the applied magnetic field is 79.8 kA / m.

  The nanocrystal alloy core having a magnetic field strength of 79.8 kA / m applied had a permeability μ (1 kHz) of 132983 and a squareness ratio Br / Bm of 32.6%. The nanocrystal alloy core having a magnetic field strength of 319.2 kA / m applied had a permeability μ (1 kHz) of 134,766 and a squareness ratio Br / Bm of 29.6%.

  FIG. 40 shows the relationship between the frequency and the real part μ ′ of the complex relative magnetic permeability, for the nanocrystal alloy core obtained in Example 12. The nanocrystal alloy core obtained with the strength of the applied magnetic field of 50 kA / m or more (79.8 kA / m, 319.2 kA / m) in the secondary heat treatment was obtained at 39.9 kA / m. In contrast, the real part μ 'becomes large in the range of 1 kHz to 10 MHz. Further, both of the strengths of 79.8 kA / m and 319.2 kA / m of the applied magnetic field have substantially the same frequency characteristics.

  FIG. 41 shows the relationship between the frequency and the imaginary part μ ′ ′ of the complex relative magnetic permeability, as in FIG. The nanocrystal alloy core obtained with the strength of the applied magnetic field of 50 kA / m or more (79.8 kA / m, 319.2 kA / m) is less than 10 kHz compared to that obtained at 39.9 kA / m. The imaginary part μ ′ ′ is small, but the imaginary part μ ′ ′ at 10 kHz or more is large. This phenomenon is a main factor that the impedance relative magnetic permeability μrz at 100 kHz in the present embodiment is increased if the strength of the magnetic field to be applied is 50 kA / m or more.

  The method of manufacturing a nanocrystal alloy core, a core unit, and a nanocrystal alloy core according to the present disclosure is suitably used as a core of a common mode choke coil, a current transformer, or the like.

1 spacer 2 holder 3 container 4 heater 5 solenoid coil 6 wound core 10 heat treatment furnace in magnetic field

Claims (34)

A method of manufacturing a nanocrystalline alloy core, wherein a magnetic core of a wound or laminated amorphous alloy ribbon is nanocrystallized by heat treatment,
A primary heat treatment step of performing a primary heat treatment in which the magnetic core is heated from a temperature lower than the crystallization start temperature to a crystallization start temperature or higher in a non-magnetic field;
And a secondary heat treatment step to be performed thereafter,
The secondary heat treatment step is
A second temperature holding step of holding at a constant temperature of 200 ° C. or more and less than the crystallization start temperature in the absence of a magnetic field;
Thereafter, a method of producing a nanocrystal alloy core, comprising: a second temperature lowering step of decreasing a temperature while applying a magnetic field in a direction orthogonal to the magnetic path.   In the second temperature holding step, after the temperature of the magnetic core is in the range of ± 5 ° C. with respect to the temperature at the time of starting the application of the magnetic field, the holding time in the temperature range is one minute or more. The manufacturing method of the nanocrystal alloy core as described in claim 1.   The method according to claim 1 or 2, wherein the magnetic field is applied at a magnetic field strength of 60 kA / m or more.   The manufacturing method of the nanocrystal alloy core in any one of Claim 1 to 3 whose holding temperature of the said secondary heat processing is 200 to 500 degreeC.   The manufacturing method of the nanocrystal alloy core in any one of Claim 1 to 4 whose holding temperature of the said primary heat processing is 550 to 600 degreeC.   The method for producing a nanocrystalline alloy core according to any one of claims 1 to 5, wherein the amorphous alloy ribbon has a thickness of 7 μm to 15 μm. The amorphous alloy ribbon has a general formula: (Fe _1-a M _a ) _{100-xyz-α-β-γ} Cu _x Si _y B _z M ′ _α M ′ ′ _β X _γ (atomic%) (where M is Co And / or Ni, M 'is at least one element selected from the group consisting of Nb, Mo, Ta, Ti, Zr, Hf, V, Cr, Mn and W, M "is Al, a platinum group element Sc, at least one element selected from the group consisting of rare earth elements, Zn, Sn and Re, and X is at least one selected from the group consisting of C, Ge, P, Ga, Sb, In, Be and As The elements of the species, a, x, y, z, α, β and γ are respectively 0 ≦ a ≦ 0.5, 0.1 ≦ x ≦ 3, 0 ≦ y ≦ 30, 0 ≦ z ≦ 25, 5 ≦ y + z 7. The composition according to any one of claims 1 to 6, which has a composition represented by ≦ 30, 0 ≦ α ≦ 20, 0 ≦ β ≦ 20 and 0 ≦ γ ≦ 20. Method of producing nanocrystalline alloy core.   The method for producing a nanocrystal alloy core according to any one of claims 1 to 7, further comprising the step of impregnating a resin after the secondary heat treatment.   In the secondary heat treatment, after holding at a constant temperature of 200 ° C. or more and less than the crystallization start temperature in the non-magnetic field, hold at this temperature while applying a magnetic field in a direction orthogonal to the magnetic path; The method for manufacturing a nanocrystal alloy core according to any one of claims 1 to 8, wherein the temperature is lowered while applying a magnetic field in a direction orthogonal to the magnetic path.   In the secondary temperature holding step, after the temperature of the magnetic core falls within the range of ± 5 ° C. with respect to the temperature decrease start temperature, the holding time in the temperature range is made 1 minute or more, and then the temperature range is held The method for producing a nanocrystal alloy core according to any one of claims 1 to 9, wherein the magnetic field is applied in a direction orthogonal to the magnetic path while the magnetic field is being applied.   In the secondary heat treatment step, after holding at a constant temperature of 200 ° C. or more and less than the crystallization start temperature in the non-magnetic field, the magnetic field is directed in the direction orthogonal to the magnetic path from the start of temperature decrease. The method for producing a nanocrystal alloy core according to any one of claims 1 to 10, wherein the temperature is lowered while applying. The method for producing a nanocrystalline alloy core according to any one of claims 1 to 11, wherein a volume of the magnetic core is 3000 mm ³ or more.   The method for producing a nanocrystal alloy core according to any one of claims 1 to 12, wherein the temperature rising rate in the step of the primary heat treatment is less than 1.0 ° C / min.   The method for producing a nanocrystalline alloy core according to any one of claims 1 to 13, wherein the maximum temperature in the step of the primary heat treatment is more than 550 ° C and not more than 585 ° C.   The method for producing a nanocrystalline alloy core according to any one of claims 1 to 14, wherein in the step of the secondary heat treatment, the maximum temperature when applying a magnetic field is 200 ° C or more and less than 400 ° C.   The method for producing a nanocrystal alloy core according to any one of claims 1 to 15, wherein the magnetic field is applied while decreasing the temperature at an average speed of 4 ° C / min or less in the step of the secondary heat treatment. A process of primary heat treatment in which an amorphous magnetic core material made of an amorphous alloy ribbon capable of nanocrystallization is heated to a temperature lower than the crystallization start temperature to a crystallization start temperature or more in a no magnetic field to perform nanocrystallization; And a second heat treatment step of applying a magnetic field in a direction perpendicular to the magnetic path at a temperature lower than the start temperature.
The manufacturing method of the nanocrystal alloy core whose heating rate in the process of the said primary heat treatment is less than 1.0 degreeC / min. A process of primary heat treatment in which an amorphous magnetic core material made of an amorphous alloy ribbon capable of nanocrystallization is heated to a temperature lower than the crystallization start temperature to a crystallization start temperature or more in a no magnetic field to perform nanocrystallization; And a second heat treatment step of applying a magnetic field in a direction perpendicular to the magnetic path at a temperature lower than the start temperature.
In the process of the said primary heat treatment, the manufacturing method of the nanocrystal alloy core whose maximum temperature is more than 550 degreeC and 585 degrees C or less. A process of primary heat treatment in which an amorphous magnetic core material made of an amorphous alloy ribbon capable of nanocrystallization is heated to a temperature lower than the crystallization start temperature to a crystallization start temperature or more in a no magnetic field to perform nanocrystallization; And a second heat treatment step of applying a magnetic field in a direction perpendicular to the magnetic path at a temperature lower than the start temperature.
In the process of the said secondary heat treatment, the manufacturing method of the nanocrystal alloy core whose maximum temperature at the time of applying a magnetic field is 200 degreeC or more and less than 400 degreeC. A process of primary heat treatment in which an amorphous magnetic core material made of an amorphous alloy ribbon capable of nanocrystallization is heated to a temperature lower than the crystallization start temperature to a crystallization start temperature or more in a no magnetic field to perform nanocrystallization; And a second heat treatment step of applying a magnetic field in a direction perpendicular to the magnetic path at a temperature lower than the start temperature.
A method of manufacturing a nanocrystal alloy core, wherein a magnetic field is applied while decreasing the temperature at an average speed of 4 ° C./min or less in the step of the secondary heat treatment.   The method for producing a nanocrystalline alloy core according to any one of claims 18 to 20, wherein a temperature raising rate in the step of the primary heat treatment is less than 1.0 ° C / min.   The method for producing a nanocrystalline alloy core according to any one of claims 17, 19 and 20, wherein the maximum temperature in the step of the primary heat treatment is more than 550 ° C and 585 ° C or less.   The method for producing a nanocrystalline alloy core according to any one of claims 17, 18 and 20, wherein the maximum temperature when applying a magnetic field in the step of the secondary heat treatment is 200 ° C or more and less than 400 ° C.   The method for producing a nanocrystal alloy core according to any one of claims 17, 18 and 19, wherein the magnetic field is applied while decreasing the temperature at an average rate of 4 ° C / min or less in the step of the secondary heat treatment.   The method for producing a nanocrystal alloy core according to any one of claims 17 to 24, wherein the step of the second heat treatment includes a step of lowering the temperature to at least 100 ° C while applying the magnetic field.   The method according to any one of claims 17 to 25, wherein the magnetic field is applied at a magnetic field strength of 50 kA / m or more.   The method for producing a nanocrystalline alloy core according to any one of claims 17 to 26, wherein the thickness of the amorphous alloy ribbon is 7 μm to 15 μm. A nanocrystal alloy core comprising a wound or stacked nanocrystal alloy ribbon,
Permeability μ (1 kHz) measured at room temperature with an applied alternating magnetic field of frequency f = 1 kHz and amplitude H = 0.05 amps / meter (A / m) is 70,000 or more,
Squareness ratio Br / Bm is 50% or less,
A nanocrystal alloy core having a coercive force of 1.0 A / m or less. A nanocrystal alloy core comprising a wound or stacked nanocrystal alloy ribbon,
The nanocrystalline alloy ribbon comprises an Fe-based material,
A nanocrystal alloy core having an impedance relative permeability μrz of 48,000 or more at a frequency of 100 kHz. The impedance relative permeability μrz is
Over 90,000 at a frequency of 10 kHz,
More than 48,000 at a frequency of 100kHz,
More than 8,500 at a frequency of 1 MHz,
The nanocrystal alloy core according to claim 29, which is   The nanocrystal alloy core according to claim 29 or 30, wherein the thickness of the nanocrystal alloy ribbon is 7 μm or more and 15 μm or less.   The nanocrystal alloy core according to any one of claims 29 to 31, wherein the core is impregnated with a resin.   The nanocrystal alloy core according to any one of claims 29 to 32, wherein the nanocrystal alloy core is for a common mode choke coil. The nanocrystal alloy core according to any one of claims 29 to 33,
The nanocrystalline alloy core wound wire;
Core unit equipped with

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