JPH01290206A - Fe-based dust core - Google Patents

Abstract

PURPOSE:To obtain an Fe-based dust core whose saturation magnetic flux density is high in a high-frequency region, whose soft magnetic characteristic is excellent and which can be shaped arbitrarily by using an alloy powder having a fine crystal particle of a specific composition. CONSTITUTION:An alloy powder expressed by Formula I and having a fine crystal particle is used. In Formula I, M represents at least one or more kinds selected from group IVa elements, group Va elements and group VIa elements in the periodic table, and M represents at least one or more elements selected from Mn, Co, Ni, Al and elements of a platinum group. In addition, the following conditions are set: 3<a<=8; 0.1<b<=8; 0<=c<=15; 8<=d<=22; 3<=e<=15; 15<=d+e<=28. By this setup, it is possible to obtain an Fe-based dust core whose saturation magnetic flux density is high, whose soft magnetic characteristic in a high frequency is excellent and which can be shaped arbitrarily.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a Fe-based powder magnetic core.

(Prior Art) Crystalline materials such as permalloy and ferrite have conventionally been used as magnetic cores used in high frequency applications such as switching regulators.

However, since permalloy has a low resistivity, iron loss at high frequencies increases. Further, although ferrite has a small loss at high frequencies, its magnetic flux density is also small, at most 5000 G, and therefore, when used at a large operating magnetic flux density, it approaches saturation, resulting in an increase in iron loss. Recently, there has been a desire to reduce the size of transformers used at high frequencies, such as power transformers used in switching regulators, smoothing choke coils, and common mode choke coils. Therefore, the increase in iron loss of ferrite becomes a big problem in practice.

For this reason, amorphous magnetic alloys that do not have a crystalline structure have recently attracted attention and have been put into practical use in some cases because they exhibit excellent soft magnetic properties such as high magnetic permeability and low coercive force.

These amorphous magnetic alloys are based on Fe, Co, N1, etc., and P% as an amorphous element (metalloid).
This includes CS8% Si% Afi% Ge and the like.

However, not all of these amorphous magnetic alloys have small iron loss in the high frequency range.

For example, Fe-based amorphous alloys are inexpensive and 50~60H
In the low frequency range of z, it shows a very small iron loss of about 174 compared to silicon steel, but in the high frequency range of 10 to 50KHz, it shows a significantly large iron loss, making it very suitable for use in high frequency ranges such as switching regulators. It's not something you do. In order to improve this, some of the Fe was replaced with NbS.
By substituting non-magnetic metals such as Mo and Cr, magnetostriction is reduced, and low core loss and high magnetic permeability are achieved, but the magnetic properties are also relatively significantly deteriorated due to curing shrinkage of the resin during resin molding, for example. As a soft magnetic material used in a high frequency region, sufficient characteristics have not yet been obtained.

On the other hand, Co-based amorphous alloys have low core loss and high squareness ratios in the high frequency range, and are therefore put to practical use in magnetic parts for electronic devices such as saturable reactors, but they are relatively expensive.

In addition, from the technical field of powder magnetic cores, iron powder dust cores, M
O permalloy dust cores and the like are used in noise filters and choke coils, and have relatively large iron losses, which poses a problem for higher frequency power supplies.

(Problems to be Solved by the Invention) As described above, although Fe-based amorphous alloys are inexpensive soft magnetic materials, they have relatively large magnetostriction, and have lower iron loss and permeability than CO-based amorphous alloys. It also has poor magnetic property, which poses a problem for use in high frequency ranges.

On the other hand, although Co-based amorphous alloys have good magnetic properties,
It was not industrially advantageous due to the high cost of the material.

In addition, the materials used for the powder magnetic core also had relatively large core losses, which caused problems with higher frequency power supplies.

Therefore, in view of the above problems, it is an object of the present invention to provide an Fe-based powder magnetic core that has excellent soft magnetic properties with high saturation magnetic flux density in a high frequency region and can be formed into various shapes.

[Summary of the Invention] (Means for Solving the Problems) In order to achieve the above object, as a result of various studies on Fe-based alloys, at least one member selected from the general formula % M-; Mn, Co , Ni, AJ! , at least one selected from platinum metal elements: 3<a≦8 0.1<b≦8 0≦c≦15 8≦d≦22 3≦e≦15 15≦d+e≦28, and is a fine crystal. It was discovered for the first time that alloy powder having grains has excellent properties, leading to the present invention.

The present invention is characterized in that particularly fine crystal grains are present in the alloy powder having the above composition. In particular, it is preferable that the fine crystal grains exist in the alloy in an area ratio of 30% or more, and furthermore, the fine crystal grains are present in the alloy powder in an area ratio of 30% or more. 50～
It is preferable that 80% or more of 300A crystal grains exist.

The reason for limiting the composition of the alloy of the present invention and the reason for limiting the fine crystal grains will be explained below.

First, the reason for limiting the composition will be explained.

Cu 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. If the content is too large, the magnetic properties deteriorate, so the range was set to exceed 3 and be below 8 atomic %. Especially in the case of powder magnetic core C
This is preferable because the filling rate increases as u increases. Preferably it is more than 3 and less than 5 atomic %.

M is an element that is effective in making the crystal grain size uniform, reducing magnetostriction and magnetic anisotropy, and improving soft magnetic properties and magnetic properties against temperature changes, but if its amount is too small, The effect of addition cannot be obtained, and conversely, if too much is added, the saturation magnetic flux density will be low, so the amount should be adjusted to 0.1 to 8
Expressed as atomic %.

Preferably 1 to 7 at%, more preferably 1.5 to 5
It is atomic percent. Here, in addition to the above-mentioned effects, each additive element in M has the following effects: IVa group elements expand the range of heat treatment conditions to obtain optimal magnetic properties, and Va group elements improve embrittlement resistance and workability such as cutting. , Group VIa elements have the effect of improving corrosion resistance and surface properties, and thereby have effects such as improving magnetostriction and soft magnetic properties.

Among the M elements, Nb and Mo are particularly useful for lowering iron loss.

Ta, W, Zr, and Hf are preferred.

M is an element effective in improving the soft magnetic properties, but if the amount is too large, the saturation magnetic flux density will decrease, which is undesirable, so the amount is set to 15 at % or less. Preferably it is 10 atomic % or less.

Here, the total amount of Cu, M, and M- is preferably 3.1 to 25 atomic %. This is because if the total amount is too small, the effect of addition is small, and conversely, if the total amount is too large, the saturation magnetic flux density tends to become too small.

Si is an effective element for making the alloy amorphous or directly precipitating fine crystals during manufacturing, and if its amount is too small, it will be difficult to obtain the effect of ultra-quenching during manufacturing, and the above state will not be obtained, resulting in the opposite effect. If the amount is too large, the saturation magnetic flux density becomes low and it becomes difficult to obtain the above state, making it impossible to obtain excellent magnetic properties. Preferably it is 10 to 20 atom %, more preferably 12 to 18 atom %.

Like Si, B is an effective element for making the alloy amorphous or directly precipitating fine crystals, and if its amount is too small, it is difficult to obtain the effect of ultra-quenching during manufacturing, and the above state cannot be obtained. On the other hand, if the amount is too large, problems will occur from the viewpoint of magnetic properties, so the amount is set to 3 to 15 at %. Preferably it is 5 to 10 at%.

Here, if the total amount of Si and B is too small, the effect will not be obtained. On the other hand, if the amount is too large, it will be difficult to obtain the effect as well, and the saturation magnetic flux density will decrease. The amount is preferably 15 to 28 at.%.

The Fe-based magnetic alloy powder of the present invention is pulverized to obtain an amorphous alloy ribbon by, for example, a liquid quenching method, or
After obtaining the rapidly cooled powder by the atomization method, mechanical alloying method, etc.,
1 at a temperature of +120°C, preferably -30 to +100°C.
It can be obtained by a method in which the intended fine crystals are precipitated by heat treatment for 10 minutes to 10 hours, preferably 10 minutes to 5 hours, or by a method in which fine crystal grains are precipitated by controlling the quenching rate in a quenching method. Become.

Next, the fine crystal grains of the Fe-based magnetomagnetic alloy of the present invention will be described.

In the alloy of the present invention, if there are too few fine crystal grains, that is, if there are too many amorphous phases, the iron loss will be large, the magnetic permeability will be low, the magnetostriction will be large, and the deterioration of magnetic properties due to resin molding will increase. It is preferable that the fine crystal grains in the alloy exist in an area ratio of 30% or more.

Furthermore, if the grain size of the fine crystal grains is too small, the magnetic properties cannot be improved, and if the grain size is too large, the magnetic properties deteriorate. It is preferable that 80% or more of 300A crystals exist.

Next, we will discuss the powder magnetic core.

First, regarding the particle size, if the particle size is too small, the filling rate will decrease.
On the other hand, if the particle size is too large, the loss will increase and it will be unsuitable for high frequency applications, so the particle size is preferably in the range of 1 to 100 μm.

Furthermore, the shape of the particles is not specified, such as spherical or flat. The shape of these powders depends on the manufacturing method; for example, in the case of an atomization method, a spherical powder is obtained, but when this powder is subjected to a rolling process, it becomes a flat powder.

These powders are subjected to normal pressure molding to give a powder of 450 to 650
Heat treatment is performed at 10° C. for 10 minutes to 10 hours, and sintering is performed.

During this molding, an inorganic insulating material such as metal alkoxide, water glass, or low melting point glass is used as a binder.

(Example) Example I Fe 75-XCux Nba Si 15B
In the alloy system 7, X-1, 2, 3, 4, 5, 6,
Regarding No. 7, spherical powder of 10 to 50 μm was produced by the atomization method.

Using water glass as a binder, 38X 19X 12
．． Pressure molded to the toroidal core of 5 dragons, then X-1~
3 was sintered at BOmin at 550°C, X-4 and 5 were sintered at 530°C and 80m1n, and X-6 and 7 were sintered at 500°C and 80a+in.

When the filling factor of these cores was investigated, it was found that the filling factor increased as the amount of Cu increased, as shown in FIG.

In addition, μ'' and Q-f characteristics were measured for X-2 and X-4 among these samples.In this measurement, LC
An R meter is used, a magnetic core is wound with 10 turns, and a voltage of 1 V is set as the condition. The results are shown in FIG. Second
As is clear from the figure, the alloy (X-4) of the present invention exhibits higher μ and Q than the comparative alloy (X-2), and is effective as a magnetic core for choke coil transformers and the like.

Also, the DC superposition characteristics were measured using the same sample.

The results are shown in FIG. As is clear from these results, it is clear that the magnetic core of the present invention is superior.

Example 2 Each alloy powder shown in Table 1 was produced by an atomization method. The obtained powder is a spherical powder, and the powder diameter is 10 to 50μ.
It is m.

Using water glass as a binder, add this to 38X19X12.
They were pressure-molded into a 5 mm toroidal core, and samples 1 to 6 were heat-treated at 540°C and 80 iin to prepare measurement samples.

For comparison, Sample 7 was also produced in the same manner. Furthermore, as a comparative example, F e 79 S 1 to B t
□A toroidal core sample 8 in which the amorphous ribbon was wound in the same shape, heat treated, resin impregnated, and gap formed, and an iron powder dust core in the same shape were also evaluated.

μ 1DKHz” 100KHz per these cores
As shown in Table 1, it is clear that the core of the present invention has a high μ' and a high Q value.

(The following is a blank space) Table 1 Example 3 An alloy powder having a composition of Fe79-XClx Nb251 taBa was produced by an atomization method. The obtained powder is a spherical powder with a particle size of 10 to 50 μm.

Using water glass as a binder, 38X 19X 12
．． Pressure molded into a 5-section toroidal core, heated at 500℃, 90℃
fflin was heat-treated and used as a measurement sample.

The saturation magnetization of the obtained sample was adjusted to 10KO using VSM.
It was measured in a magnetic field of e. The results are shown in FIG.

As is clear from FIG. 4, the saturation magnetization decreases due to the substitution of Cu for Fe, and when Cu exceeds 8 at %, it becomes a practical problem.

[Effects of the Invention] As described above, the present invention makes it possible to provide an Fe-based powder magnetic core that has a high saturation magnetic flux density and excellent soft magnetic properties at high frequencies, and can be formed into various shapes.

[Brief explanation of the drawing]

Fig. 11 is a graph showing the influence of the filling rate as the amount of Cu changes, Fig. 2 is a graph showing μ' and Q-f characteristics of the present invention and comparative examples, and Fig. 3 is a graph showing the effects of the present invention and comparative examples. A graph showing the DC superimposition characteristics and FIG. 4 are graphs showing the influence on saturation magnetization due to a change in the amount of Cu.

Claims (1)

[Claims] Fe_1_0_0_-_a_-_b_-_c_-_d_
-_eCu_aM_bM'_cSi_dB_e M: At least one or more elements selected from the IVa, Va, and VIa group elements of the periodic table M': At least one or more elements selected from the group elements Mn, Co, Ni, Al, and platinum group 3<a≦ 8 0.1<b≦8 0≦c≦15 8≦d≦22 3≦e≦15 15≦d+e≦28 Fe-based, characterized by using an alloy powder having fine crystal grains Powder magnetic core.