JPH03280503A - Magnetic core - Google Patents

Abstract

PURPOSE:To increase the squareness ratio in high-frequency region of a magnetic amplifier assembled into a switching power supply while decreasing the saturated inductance by a method wherein an area ratio of the recession on the surface in the roll surface side of an alloy thin band is specified. CONSTITUTION:An alloy in specific composition melted down in a heat resisting vessel such as quartz etc., is injected into the turning surface of a rapidly turning metallic cooling down roll from a nozzle so as to manufacture a ribbon type thin band. At this time, fine ruggedness is inevitably formed on the surface of the manufactured alloy thin band (roll surface). Through these procedures, an area occupied by the recession existing on the roll surface side of this alloy thin band shall be strictly limited not to exceed 30% preferably 25% and 20% for meeting the optimum requirement thereby enabling the squareness ratio in high-frequency region to be rapidly increased while the saturated inductance to be decreased.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is particularly applicable to high frequencies (specifically, 50 kHz or higher).
A magnetic core that has excellent squareness characteristics and magnetic saturation characteristics as well as low iron loss, and is suitable for magnetic components such as saturable reactors used in high-frequency switching power supplies and reactors for semiconductor circuits, and a thin alloy used to manufacture this magnetic core. Regarding the obi.

(Prior art) In recent years, with the demand for smaller, lighter, and higher performance electronic devices,
Magnetic parts used as important functional parts are also required to have higher performance. Especially in switching power supplies used as power sources for OA equipment and communication equipment,
Higher frequencies are being considered due to the need for smaller size and lighter weight. Therefore, the magnetic materials used in these magnetic components are also required to have excellent high frequency magnetic properties. In particular, materials with high magnetic permeability are effective for many magnetic components such as current sensors such as zero-phase current transformers and noise filters.

In recent years, switching power supplies incorporating magnetic amplifiers have been widely used from the viewpoint of high reliability and high efficiency.

The main part constituting this magnetic amplifier is a saturable reactor, and a magnetic core material with excellent square magnetization characteristics is required. Conventionally, Sendelta (trade name), which is made of an Fe--Ni crystalline alloy, has been used as such a magnetic core material.

(Problems to be Solved by the Invention) However, although Sendelta has excellent square magnetization characteristics, at high frequencies of 20 kHz or higher, the coercive force increases, the thin current loss increases, and heat is generated, making it unusable. For this reason, the switching frequency of a switching power supply incorporating a magnetic amplifier has been limited to 20 KHz or less.

In recent years, along with the demand for smaller and lighter switching power supplies, there has been a demand for higher switching frequencies, and magnetic core materials with low coercive force at high frequencies and excellent squareness and thermal stability are being used. Amorphous alloys were studied (Japanese Patent Application Laid-Open No. 61-22580
4).

However, in order to meet the demand for higher efficiency in switching power supplies, it is essential to further improve the performance of amorphous alloy magnetic cores. It has been desired to improve the - layer (reduction of inductance).

The present invention has been made in consideration of the above problems,
The object of the present invention is to provide a magnetic core using an alloy ribbon that has a large squareness ratio particularly in a high frequency range and a small saturation inductance.

(Means for Solving the Problems) Summary of the Invention A magnetic core according to the present invention is a magnetic core that is formed by winding or laminating thin alloy ribbons and has excellent squareness characteristics in a high frequency region. By reducing the area occupancy of the recesses on the roll side surface to 30% or less,
It is characterized by an improved squareness ratio of the magnetic core.

The present inventors have discovered that by reducing the area occupancy of the four parts of the roll surface side surface of the alloy ribbon to 3096 or less, the squareness ratio in the high frequency range can be rapidly improved and the saturated inductance can be reduced. . Furthermore, the present inventor has determined that by reducing the area occupation rate of the surface recesses on the roll surface side of the alloy ribbon constituting the magnetic core to 30% or less, and at the same time reducing the surface roughness (Rf) on the free surface side to 0.39 ci or less. It was discovered that the squareness characteristics of the magnetic core, especially in the high frequency region, can be improved. The present invention has been made based on the above findings.

According to the present invention, at a frequency of 100kHz, 98% or more, preferably 98. 59δ or more, more preferably 999
A magnetic core having a squareness ratio of 0 or more is provided. Further, according to the present invention, it is possible to provide a magnetic core with saturation magnetic properties of 550 (G) or less, and further, 500 (G) or less. Here, the saturation magnetic characteristics usually differ depending on the shape of the magnetic core, the number of turns, and measurement conditions. In the present invention, as evaluation criteria, (1) the magnetic core has an outer diameter of 15 mm, an inner diameter of 10 m+*, and a height of 4.5 mm, the number of 2 turns is 10;
It is expressed as the value of the difference between the magnetic flux density and the residual magnetic flux when a 16 (Oe) magnetic field is applied at a frequency of 100 kHz as measurement conditions.

DETAILED DESCRIPTION OF THE INVENTION Recently, soft magnetic alloy ribbons used as magnetic core materials used in high frequencies are increasingly being manufactured by the so-called molten metal quenching method. In this method, a ribbon-shaped thin strip is obtained by injecting a molten alloy of a predetermined composition from a nozzle onto the rotating surface of a metal cooling roll that rotates at high speed and rapidly cooling it in a heat-resistant container such as quartz. It is. However, fine irregularities are inevitably formed on the surface of the alloy ribbon manufactured in this manner (roll surface, that is, the side that comes into contact with the cooling roll).

According to the research conducted by the present inventors, the area occupation rate of the recesses existing on the roll side surface of the alloy ribbon is strictly limited to 30% or less, preferably 25% or less, and more preferably 20% or less. It has been found that by doing so, the squareness ratio in the high frequency range can be rapidly improved and the saturation inductance can be reduced.

That is, in the magnetic core of the present invention according to the first aspect, an alloy ribbon is manufactured by injecting a molten alloy from a nozzle onto the surface of a cooling roll and rapidly cooling it, and the alloy ribbon is manufactured by The present invention is characterized in that it is formed of an alloy ribbon in which the area occupation rate of the recesses formed on the surface of the alloy ribbon in contact with the roll is 30% or less.

Normally, when producing alloy ribbons by the molten metal quenching method described above, the surface condition of the obtained alloy ribbons is as follows:
It mainly depends on the surface condition of the cooling roll and the wettability between the molten alloy and the roll. Wettability in this case is also influenced by the composition of the alloy. The recesses formed on the surface of the alloy ribbon are formed by air bubbles caught between the cooling roll and the molten metal.

As is clear from the results of the examples described below, according to the present invention, by limiting the area occupation rate of the recesses formed on the surface of the alloy ribbon on the side that contacts the cooling roll to 30% or less, The squareness ratio of the magnetic core can be significantly improved.

The effect of improving the squareness ratio as described above is particularly remarkable in amorphous alloys having a Curie temperature of 300° C. or lower. The reason for this is presumed to be the ratio between the induced magnetic anisotropy generated by heat treatment and the shape magnetic anisotropy caused by surface roughness. That is, this is noticeable in alloys with a Curie temperature of 300° C. or less and a relatively small induced magnetic anisotropy.

As mentioned above, methods for limiting the area occupation ratio of the four parts formed on the ribbon surface to 3096 or less include improving the wettability of the cooling roll and the molten alloy, and optimizing the cooling rate. Specific methods for this include the use of iron-based rolls (for example, 345C, high-speed steel), and in the case of Cu-based alloys (CuBeSCuTi, etc.), the temperature of the water cooled from inside the cooling roll is kept at 30 to 60°C. How to control or increase the injection temperature of molten alloy to 1
There is a method of increasing the temperature to 350°C or higher.

As a more preferable method, the production atmosphere can be reduced to a reduced pressure below atmospheric pressure, thereby reducing the generation of four parts (for example, to 10% or less).

Further, the definition and measurement method of "area occupancy rate of recesses formed on the surface of the ribbon" in the present invention are as follows.

A photograph of the roll surface is taken using a scanning electron microscope at 200x magnification. From this photograph, all recesses with a field of view major axis (diameter of the smallest circle that wraps and touches the recess) of 10 μm or more are picked up, and an image processing device (for example, LUZEX500 manufactured by Nippon Regulator) is used to calculate the number of recesses occupied per unit area. Find the area ratio. This process is performed at least 10 times, the average value is determined, and the second average value is defined as the "area occupancy rate."

Next, a second aspect of controlling the surface roughness of the alloy ribbon will be described.

That is, in the second aspect of the present invention, an alloy thin strip is produced by injecting a molten alloy onto the surface of a cooling roll through a nozzle and rapidly cooling the alloy thin strip, and the alloy thin strip that does not come into contact with the cooling roll is The surface roughness of the strip surface is Rf≦0.3 in the longitudinal direction of the alloy ribbon (however, Rf is the ten-point average roughness at a standard length of 2.5 fins specified in JIS-B-0601). , and the average plate thickness determined from the weight of the alloy ribbon, respectively, are Rz%T, and it is a parameter that characterizes the roughness determined by the following formula.)
It is characterized in that the magnetic core is formed by an alloy ribbon having a value of . The value of this Rf is preferably
It is 0.25 or less, more preferably 0.22 or less.

Normally, when producing alloy ribbon by the molten metal quenching method, the surface condition of the obtained alloy ribbon is affected by conditions such as the surface condition of the cooling roll and the stability of the molten metal pool between the nozzle and the roll. receive. According to the research of the present inventors, irregularities that appear periodically in the longitudinal direction of the ribbon (so-called fish scale), which are particularly likely to occur on the free surface (i.e., the surface of the ribbon on the side not in contact with the cooling roll), are It has been found that high-frequency magnetic properties of the band, especially the squareness ratio, are adversely affected.

That is, the surface roughness of the alloy ribbon in the longitudinal direction is set to Rf≦0.3, more preferably, according to the above-mentioned regulations.
By limiting Rf≦0.27, the squareness ratio in the high frequency region can be significantly improved, and
It can reduce saturation inductance.

Such an effect is particularly remarkable when an amorphous alloy having a Curie temperature of 300° C. or lower is used as the material. The reason for this is presumed to be related to the shape anisotropy caused by surface roughness, as described for the ribbon roll surface.

In order to control the surface roughness as described above, it is necessary to appropriately control manufacturing parameters such as the material of the cooling roll, the roll surface temperature, and the temperature of the molten metal during injection. For this purpose, it is necessary to adjust and optimize the cooling rate and roll circumferential speed, for example. Specifically, a method using a Cu-based alloy roll and setting the water temperature inside the roll at 30 to 80°C;
Alternatively, an effective method is to set the roll circumferential speed to 25 m/s or more.

Next, the alloy material used in the magnetic core of the present invention will be explained.

In the present invention, a Co-based amorphous alloy or a Fe-based magnetic alloy may be used.

Here, the preferred composition of the Co-based amorphous alloy is as follows: (Co FeM) (Si B
)1-b-c b c 100-y
1-m m y However, M is at least one of Ni and Nn b≦0.10 0, 01≦e≦0.10 0, 3≦m≦0.8 26≦y≦32 (C01-d-eFedM 'e) 1oo-2 (S11-
nBn)z However, M' is Ti, V, Cr, Cu, Zr
.

At least one selected from Nb5No, Hf5Ta, W, 0.03≦d≦0.10 0.01≦e≦0.06 0.3≦n≦0.8 224≦z≦32 (C01-f-g -h Fe f Mg M' h
) 100-W (S il-, B p) w However, M is at least one of Ni and Mn, f≦0.10 0.01≦gS0.10 0.01≦h≦0.08 0.3≦ p≦0.5 24≦w≦30, both of which have a saturation magnetostriction constant λS
A Co-based amorphous alloy in which -Ix10≦λs≦lX1O-6 (II') is in the range 6 is preferable.

The Co-based amorphous alloy used in the magnetic core of the present invention is expressed by the above four general formulas, but the most important thing here is the composition setting to set the Curie temperature to 300°C or less, and the combination of metal elements and The atomic ratio of metalloid elements is the main factor. In general formulas ■ to ■, X5YsZ is 26 to 32,
In ■ and ■, W is set to 24 to 30 for X5YS.
If Z is less than 26 or W is less than 24, the coercive force will be large, the iron loss value will be large, and the thermal stability will be poor.
On the other hand, if X5YxZ exceeds 32 or W exceeds 30, the Curie temperature decreases, making it impractical.

Fe is an element for adjusting magnetostriction to -1 x 10 to +1 x 10-6, and C
a, b showing the blending ratio with o.

d and f are each 0.02 to 0.08 and 0.10 or less,
This can be achieved by specifying it within the range of 0.03 to 0.10.0.10.

M (at least one selected from Ni or Mn) and M'(M' is T I SV s Cr, Cu.

At least one element selected from Zr, Nb, Mo5Hf, Ta, and W) is an effective element for further improving thermal stability, but its addition ff1c%h is 0.5%, respectively.
10 or less and 0.08 or less, and if C1h is 0.10 or more and 0.08 or more, the Curie temperature decreases too much, which is not preferable.

Si and B are essential components to make the alloy amorphous, but in order to obtain a magnetic core with particularly low core loss, high squareness ratio, and high thermal stability, the blending ratio of Si and B must be adjusted. Indicate l, m,
It is necessary to specify n or p in the range of 0.3 to 0.5 to make it Si rich. This is because if l, m, n, or p is less than 0.3 or more than 0.5, it becomes particularly difficult to obtain a high squareness ratio, and the thermal stability of the magnetic properties becomes somewhat poor.

Among the alloy compositions (1) to (2) above, the alloys (1) and (2) are the most preferred from the viewpoint of reducing concavities due to entrainment of air bubbles (first aspect of the present invention).

More preferably, M' is C', Nb or M'.
This is the case when o is selected. This is thought to be due to improved wettability and decreased viscosity.

In both the first and second aspects of the present invention described above, the effect of shape magnetic anisotropy is determined by the relationship with the magnitude of induced magnetic anisotropy. Therefore, especially when the magnitude of induced magnetic anisotropy is 1
The present invention is particularly effective for materials of 0.04 erg/cc or less. Furthermore, as mentioned earlier, the present invention is particularly effective in amorphous alloys with a Curie temperature of 300°C or lower;
In the following cases, the squareness ratio and saturation inductance do not reach a sufficiently good level. Therefore, in the present invention, the Curie temperature range is 160 to 300°C,
Furthermore, the temperature range is preferably from 180 to 280°C, and more preferably from 190 to 270°C.

Note that setting the Curie temperature to 300° C. or lower also has the meaning of improving thermal stability. It is generally known that an amorphous alloy can be obtained by rapidly cooling an alloy material having a predetermined composition ratio from a molten state at a cooling rate of 104° C./second or more (liquid quenching method).

The amorphous alloy of the present invention can also be easily produced by the conventional method described above. This amorphous alloy is used, for example, as a plate-shaped ribbon manufactured by a single roll method. In this case, since iron loss at high frequencies increases if the thickness exceeds 25 μm, it is preferable to set the thickness of the ribbon in the range of 5 to 25 μm.

The magnetic core of the present invention is produced by winding an amorphous alloy produced by the above manufacturing method into a predetermined shape and subjecting it to heat treatment to remove strain.
The cooling rate at that time may be about 0.5 to 50" C/sin, preferably in the range of 1 to b in.
Furthermore, heat treatment may be applied in a magnetic field at a temperature below the Curie temperature.

On the other hand, in the present invention, an Fe-based ultra-ultrafine crystal alloy can also be used. This alloy contains Cu, Nb, WSTa, and Zr in a Fe-5i-B alloy or the like.

One type of Bf, Ti, Mo, etc. is added to the alloy, and after it is formed into a thin strip similar to an amorphous alloy, fine crystal grains are precipitated by heat treatment in a temperature range above the crystallization temperature. It is something.

The present invention can be similarly applied to Fe-based ultra-ultrafine crystal alloys as described above.

The alloy composition used when producing the above Fe-based magnetic alloy ribbon is as follows: General formula: %Formula % (1) (wherein, E is at least 1 selected from Cu and Au)
G is IVaVa group element, a group element, VI'a
At least one element selected from the group consisting of group elements and rare earth elements, and J is Mn and AI.

at least lFi element selected from the group consisting of Ga, Ge, In, Sn and platinum group elements, 2 represents at least one element selected from the group consisting of C, N and P, es fs gs h -1 and j are numbers that satisfy the following formula. However, all numbers in the formula below are a
Indicates t%.

0.1≦e≦8 0.1≦f≦10 0≦g≦10 12≦h≦25 3≦i≦12 0≦j≦10 15≦h+i+j≦30゜The same applies below. ) is preferably used.

Here, E (Cu or Au) in the above formula (1) is an effective element for increasing corrosion resistance, preventing coarsening of crystal grains, and improving soft magnetic properties such as iron loss and magnetic permeability. be. It is particularly effective for precipitating the bcc phase at low temperatures. If this amount is too small, the above-mentioned effects cannot be obtained, while if it is too large, the magnetic properties will deteriorate, which is not preferable.

Therefore, the content of E is suitably in the range of 0.1 to 8 atomic %. The preferred range is 0.1 to 5 at.%.

G (at least one element selected from group IVaVa elements, group A elements, group VIa elements, and rare earth elements) is effective in making the crystal grain size uniform, reduces magnetostriction and magnetic anisotropy, and softens the It is an effective element for improving magnetic properties and improving magnetic properties against temperature changes, and E (e.g. Cu
) can stabilize the bcc phase over a wider temperature range. If this amount is too small, the above effects cannot be obtained, and if this amount is too large, amorphization will not occur during the manufacturing process, and the saturation magnetic flux density will further decrease. Therefore, the G content is 0. 1-10 atomic%
range is suitable. A more preferable range is 1 to 8 atomic %.

In addition, the effects of each element in E are as follows:
Expansion of heat treatment conditions to obtain magnetic properties suitable for group IVaVa elements, group Va elements are effective for improving embrittlement resistance and workability such as cutting, and group VIa elements are effective for improving corrosion resistance and surface roughness. It is.

Among these, Ta5NbSW and Mo have a remarkable effect of improving soft magnetic properties, and (2) has a remarkable effect of improving embrittlement resistance and surface properties, and these are preferable in this respect.

J (at least one element selected from Mn, Al, Ga, In, Sn, and platinum group elements) is an element that is effective in improving soft magnetic properties or corrosion resistance. However, if the amount is too large, the saturation magnetic flux density will decrease, so the number is set to 10 atoms, 96 or less. Among these, A1 is particularly effective for refining crystal grains, improving magnetic properties and stabilizing the BCC phase, Ge is effective for stabilizing the BCC phase, and platinum group elements are effective for improving corrosion resistance.

Si and B are elements that assist the amorphization of the alloy during manufacture, can improve the crystallization temperature, and are effective elements for heat treatment to improve magnetic properties. In particular, −
is dissolved in Fe, which is the main component of fine crystal grains, and contributes to reducing magnetostriction and magnetic anisotropy. If the amount is less than 12 at%, the improvement in soft magnetic properties will not be noticeable, and if it exceeds 25 at%, the ultra-quenching effect will be small, and comparatively coarse crystal grains on the μm level will precipitate, resulting in good soft magnetic properties. cannot be obtained. Furthermore, Si is particularly preferably contained in an amount of 12 to 22 atomic % for the appearance of a regular lattice. In addition, if B is less than 3 atomic %, relatively coarse crystal grains will precipitate, making it impossible to obtain good properties, and if it exceeds 12 atomic %, B compounds will tend to precipitate during heat treatment, deteriorating the soft magnetic properties. Undesirable.

In addition, Z (C, N5P) as other amorphous elements,
It may be contained in a range of 10 atomic % or less.

Note that the total amount of Si, B, and other amorphous elements is:
The range of 15 to 30 atomic % is preferable, and S i /
B≧1 is preferable in order to obtain excellent soft magnetic properties.

In particular, by setting the amount of Si to 13 to 21 at%, magnetostriction λs = 0 can be obtained, the deterioration of magnetic properties due to resin molding is eliminated, and the desired excellent soft magnetic properties can be effectively exhibited. .

Furthermore, even if the above Fe-based magnetomagnetic alloy contains a small amount of unavoidable impurities such as 0, S, etc., which are also contained in ordinary Fe-based alloys, this does not impair the effects of the present invention. .

(Example) The present invention will be explained in detail below.

Example A1 and Comparative Example A1 (Co 0.900 FeO, 05NbO, 05CrO
,02)75(Si0.58B0.44)25 Long ribbon samples a and b of 16 μm in thickness and 10 mm in width and having different surface properties on the roll surface were made by a single roll method. Created.

When the entrainment of air bubbles on the roll surface of Samples a and b was observed through photographs, differences as shown in FIGS. 1 and 2 were observed. The ratio is 38% for sample a (Figure 1) and 2396 for sample A (Figure 2).

The area occupancy rate of the recesses was measured as follows. First, using a scanning electron microscope, we examined the roll surface of the ribbon.
Photographs were taken at 200x magnification. Field of view 0 in this photo
．． Recesses with a major axis of 10 μm or more were extracted within a range of 45 wX O, 55 m, and image processing was performed to determine the area. By comparing this with the total visual field area, the area occupation rate of the concave portion was determined.

The obtained alloy ribbon was wound to an outer diameter of 18 mm and an inner diameter of 12 m.
■A toroidal core was molded. Next, this is heat treated at an appropriate temperature above the Curie temperature and below the crystallization temperature.
It was cooled at a rate of .degree. C./1n.

Primary and secondary windings were applied to the obtained core, an external magnetic field of 10e was applied, and an AC hysteresis curve was measured using an AC magnetization measuring device, and the squareness ratio Br/Bl (Br: residual magnetic flux density, Bl : magnetic flux density in a magnetic field of 10 e) was determined. The value at 100 KHz was 99.4% for the magnetic core using the material shown in FIG. 1, and 94.8% for the core using the material shown in FIG. 2, resulting in a difference of about 5%.

When these magnetic cores were applied as a saturable reactor in a power supply with a switching frequency of 100 KHz, the first
The magnetic core of this example using the thin ribbon shown in the figure had a smaller output uncontrollable range (dead angle) and improved efficiency by about 2% compared to the comparative magnetic core using the thin ribbon shown in FIG.

Example A2 By single roll method (coo, 90Fe0.05N1nO
, 02Nbo, o3) 75S113B12 were prepared in various ways so as to have various surface properties.

These materials were made into magnetic cores in the same manner as in Example A1, and the relationship with the squareness ratio at high frequencies was investigated. The results are summarized in FIG. 3, and it can be seen that the squareness ratio rapidly deteriorates when the area occupation rate reaches 30%.

In the following Examples and Comparative Examples, the area occupancy of the four parts of the roll surface was measured in the same manner as in Example A1 above.

Example B1 and Comparative Example B2 The following formula, (C00,94FeO,05NbO,01)71 (S
Regarding the amorphous alloy represented by iO,6B0.4)29, a plate thickness of 16 μm and width IC) was obtained by a single roll method.
am long ribbon samples a and b with different surface properties
was created.

The results of measuring sample aSb in the longitudinal direction of the ribbon using a surface roughness meter are 0.15.0.
It is 38. This is wound to have an outer diameter of 18 mm and an inner diameter of 12 mm.
A toroidal core was molded.

Next, this was heat-treated at an appropriate temperature above the Kinyly temperature and below the crystallization temperature, and then cooled at a rate of 4°C/1n.

Primary and secondary windings were applied to the obtained core, an external magnetic field of 10e was applied, and an AC hysteresis curve was measured using an AC magnetization measuring device, and the squareness ratio Br/Bl (Br: residual magnetic flux density, Bl : magnetic flux density in a magnetic field of 10 e) was determined.

The value at 50 KHz was 99.4% for the magnetic core using Rf-0.15 material, and 94.8% for Rf-0.38, resulting in a difference of about 5%.

When these magnetic cores were applied as a saturable reactor in a power supply with a switching frequency of 100 KHz, the magnetic core of this example using ribbons of Rf-0 and 15 had Rf
Compared to the comparative magnetic core using a -0.38 ribbon, the output uncontrollable range (dead angle) was also smaller and the efficiency improved by about 2%.

Example B2 Monomer method Niyori (600,90Fe0.05Mn0.
Various amorphous alloys having the compositions 02Nbo, o3)71Si15B14 were prepared so as to have various surface properties.

These materials were made into magnetic cores in the same manner as in Example B1, and the relationship with the squareness ratio at a frequency of 100 kHz was investigated. The results are summarized in FIG. 4, and it is clear that the squareness ratio deteriorates rapidly from Rf-0.3.

Example C1 and Comparative Example CI Fe 74CLl t N b a S l taB
EXAMPLE 9 An amorphous alloy having an alloy composition of 9 was produced by a single roll method as a ribbon having surface properties in which the concavity occupancy of the roll surface was 22% and 40%. This is 18 proverbs x 12
After molding into a toroidal core of 11×4.5 m+*, it was heat-treated at 560° C. for 1 hour in a N2 atmosphere.

Thereafter, magnetic field heat treatment was performed at 400° C. for 2 hours under the condition of 5 (Oe).

The squareness ratio at 100 KHz was measured in the same manner as in Example A1. The magnetic core of the present invention had a squareness ratio of 98.7%, and the comparative example had a squareness ratio of 94.5%.

As a result of applying these magnetic cores as a saturable reactor in a power supply with a switching frequency of 100 KHz, in the case of the magnetic core of the example, compared to the magnetic core of the comparative example, the output uncontrollability characteristic (dead angle) was smaller and the power supply efficiency was improved by about 2%. did.

Example A3 and Comparative Example A3 (C00,90FeO,05M00.03CrO,02
)75(-O,6Bo,4)25 With respect to the amorphous alloy represented by (-O,6Bo,4)25, ribbons with various thicknesses and surface properties were manufactured by changing the manufacturing conditions using a single roll method.

These ribbons were wound around a toroidal core having an outer diameter of 18II 1 m and an inner diameter of 12+ am, and after being subjected to strain relief heat treatment at 440° C. for 30 minutes, magnetic field heat treatment was performed at 200° C. for 2 hours under the condition of 5 (Oe). For the obtained core, Example A1
Similarly, the squareness ratio at 100KHz and 100
One meter of iron was evaluated at KHz and 2KG. Note that the plate thickness t was determined as an average plate thickness using a gravimetric method. The average plate thickness t in this case can be determined by the following formula, where the length is 1, the width W is 1, the weight is 1 and the density is ρ.

Theory A/(++w+ρ) The results are shown in Table 1, and it can be seen that the core made of the material with surface properties of the present invention has an excellent squareness ratio and low iron loss.

Note that the surface roughness Rf is 0. The iron loss at 100 KHz was measured for various plate thicknesses of 2 and 0.38, and as shown in Figure 5, the iron loss monotonically increased as the plate thickness increased, regardless of surface properties. ing.

/ / / / / / / Table 1 21゜18゜28゜28゜99゜96゜99゜97゜50 40 60 20 Single 0-''method'.From' (C00,90FeO,05
CrO,1NbO,02)73(SiO,55B0.4
5) Two types of amorphous alloys represented by 27 were prepared. The plate thickness is 19 μm and the width is 5 m+s. By changing the material of the roll used and the temperature of the roll cooling water, the concavities on the roll surface for type 1 were reduced to 22% and 3596.
, the surface roughness of the free surface side was set to 0.25 and 0.35. These thin strips were photoetched to an outer diameter of 8m+.
*, punched into a ring-shaped core with an inner diameter of 6nos, 430℃, 4
Heat treated for strain relief for 0 minutes, then heated at 200°C for 1 hour, 2 (
The magnetic core was heat-treated in a magnetic field under the conditions of Oe) and laminated to a height of about 5 mm to obtain a magnetic core for evaluation.

When the squareness ratio at 100 kHz was measured in the same manner as in Example A1, the squareness ratio of the magnetic core of the present invention was 99.1%, and that of the magnetic core of the comparative example was 95.2%.

When these magnetic cores were used as a saturable reactor core of a power supply with a switching frequency of 200 kHz, the magnetic core of the present invention had excellent output control characteristics and improved power supply efficiency by 2.5% compared to the comparative example.

A ribbon with a width of 5 mm was produced using the composition and production conditions listed in Table 2 by a single roll method.

Note that for the Co-based amorphous alloy, the Curie temperature was also measured.

Each ribbon was wound around a loidal magnetic core (outer diameter: 15 W, inner diameter: 10 mm). The obtained Co-based amorphous magnetic cores were each subjected to strain relief heat treatment at the optimum temperature for 30 minutes, and then heated to 1 (Oe) for 2 hours at a temperature below the Curie temperature of 30°C.
Magnetic field heat treatment was performed by applying a magnetic field in the longitudinal direction of the ribbon. In addition, since Fe-based alloys are in an amorphous state when rapidly cooled, they are 50°C above their respective crystallization temperatures (values determined using a differential scanning calorimeter under heating conditions of 10°C/min). After heat treatment at 450℃ for 1 hour,
Magnetic field heat treatment was performed by applying a magnetic field of 5 (Oe) in the longitudinal direction of the ribbon for an hour. All heat treatments were performed in a nitrogen atmosphere.

The obtained magnetic core was heated to 100kHz in the same manner as in Example A1.
The squareness ratio at 100kHz.

Iron loss at 2kHz was evaluated. The results are shown in Table 2, and it can be seen that the magnetic core of the present invention has an excellent squareness ratio. Furthermore, in these examples, the magnetic flux density was determined as a value corresponding to the saturation inductance. This magnetic flux density was determined from the difference between the magnetic flux density and the residual magnetic flux density under the condition that the number of turns of the magnetic core was 10 and a magnetic field of 16 (Oe) was applied at a frequency of 100 kHz.

〔Effect of the invention〕

According to the present invention, it is possible to provide a wound magnetic core with high squareness and extremely excellent output control characteristics, so that it can be widely applied as magnetic components of switching power supplies, such as magnetic amplifiers and reactors for semiconductor circuits. .

[Brief explanation of drawings]

Figures 1 and 2 are scanning electron fJ@mirror photographs showing the surface condition of the alloy ribbon in the present invention, and Figure 3 shows the area occupancy and squareness ratio of the recesses formed on the surface of the alloy ribbon. FIG. 4 is a graph showing the relationship between surface roughness and squareness ratio, and FIG. 5 is a graph showing the relationship between the thickness of the alloy ribbon and iron loss.

Claims (1)

[Claims] 1. A magnetic core formed by winding or laminating alloy ribbons, wherein the area occupation rate of the recesses formed on the surface of the alloy ribbons is 3.
A magnetic core characterized in that it is formed of an alloy ribbon having a surface roughness of 0% or less. 2. The magnetic core according to claim 1, wherein the alloy ribbon is a Co-based amorphous alloy ribbon. 3. The magnetic core according to claim 2, wherein the alloy ribbon is made of a Co-based amorphous alloy with a Curie temperature of 160 to 300°C. 4. The squareness ratio is 98% or more at a frequency of 50 KHz,
The magnetic core according to claim 1. 5. The molten alloy is injected from the nozzle onto the surface of the cooling roll,
The alloy ribbon is produced by rapid cooling, and the surface roughness of the surface of the alloy ribbon that does not come into contact with the cooling roll is Rf≦0.3 in the longitudinal direction of the alloy ribbon. , Rf is the following when the ten-point average roughness at a reference length of 2.5 mm specified in JIS-B-0601 and the average plate thickness determined from the weight of the alloy ribbon are Rz and T, respectively. It is a parameter that characterizes the roughness determined by the formula Rf=Rz/T.)
The magnetic core according to claim 1, characterized in that the magnetic core is formed by an alloy ribbon having a value of . 6. The magnetic core according to claim 5, wherein the alloy ribbon is a Co-based amorphous alloy ribbon. 7. The magnetic core according to claim 5, wherein the alloy ribbon is made of a Co-based amorphous alloy having a Curie temperature of 160 to 300°C. 8. The squareness ratio is 98% or more at a frequency of 50 KHz,
The magnetic core according to claim 5. 9. The magnetic core according to claim 1 or 5, wherein the alloy ribbon is a Co-based amorphous alloy ribbon having an alloy composition represented by the following general formula. (Co_1_-_aFe_a)_1_0_0_-_X(
Si_1_−_lB_l)_X (however, 0.02≦a
≦0.08 0.3≦l≦0.82 26≦X≦32. ) 10. The magnetic core according to claim 1 or 5, wherein the alloy ribbon is a Co-based amorphous alloy ribbon having an alloy composition represented by the following general formula. (Co_1_-_b_-_cFe_bM_c)_1_0
_0_-_y(Si_1_-_mB_m)_y (where M is at least one of Ni and Nn, b≦0.10 0.01≦e≦0.10 0.3≦m≦0.8 26 ≦y≦32.) 11. The magnetic core according to claim 1 or 5, wherein the alloy ribbon is a Co-based amorphous alloy ribbon having an alloy composition represented by the following general formula. (Co_1_-_d_-_eFe_dM'_e)_1_
0_0_-_z(Si_1_-_nB_n)_z (However, M' is Ti, V, Cr, Cu, Zr, Nb, No,
At least one selected from the group consisting of Hf, Ta, and W.
0.03≦d≦0.10 0.01≦e≦0.06 0.3≦n≦0.82 24≦z≦32. ) 12. The magnetic core according to claim 1 or 5, wherein the alloy ribbon is a Co-based amorphous alloy ribbon having an alloy composition represented by the following general formula. (Co_1_-_f_-_g_hFe_fM_gM'_
h)_1_0_0_-_w(Si_1_-_pB_p)
_w (However, M is at least one of Ni and Mn, f≦0.10 0.01≦g≦0.10 0.01≦h≦0.08 0.3≦p≦0.5 24≦w≦30.) 13. The magnetic core according to claim 1 or 5, wherein the alloy ribbon is an Fe-based soft magnetic alloy ribbon having an alloy composition represented by the following general formula. Fe_1_0_0_-_e_-_f_-_g_-_h_
−＿i＿−＿jE_eG_fJ_gSi_hB_iZ_
j (wherein E is at least one element selected from Cu and Au, G is at least one element selected from the group consisting of IVa group elements, Va group elements, VI'a group elements, and rare earth elements) Elements, J is Mn, Al, Ga, Ge, In,
At least one element selected from the group consisting of Sn and platinum group elements, Z represents at least one element selected from the group consisting of C, N and P, e, f, g, h,
i and j are numbers that satisfy the following formula. however,
All numbers in the formula below indicate at%. 0.1≦e≦8 0.1≦f≦10 0≦g≦10 12≦h≦25 3≦i≦12 0≦j≦10 15≦h+1+j≦30. ) 14. An alloy ribbon having a surface roughness such that the area occupation rate of the recesses formed on the surface of the alloy ribbon on the side that contacts a cooling roll is 30% or less. 15. The surface roughness of the surface of the alloy ribbon that does not come into contact with the cooling roll is Rf≦0.3 in the longitudinal direction of the alloy ribbon (however, Rf is the standard length 2 specified in JIS-B-0601). It is a parameter that characterizes the roughness determined by the following formula Rf = Rz / T, where the ten-point average roughness at .5 mm and the average plate thickness determined from the weight of the alloy ribbon are Rz and T, respectively. .)
The alloy ribbon according to claim 14, characterized in that it has a value of . 16. The magnetic core according to claim 13, characterized in that the squareness ratio is 96% or more at a frequency of 100 kHz.