KR20160022409A - ferrite composition, ferrite magnetic substance using the same and method of fabricating ferrite magnetic substance - Google Patents

Abstract

In a method for manufacturing a ferrite magnetic material according to an embodiment of the present invention, provided is a first mixture including 52.0-54.5 mol% of iron oxide (Fe2O3), 36.4-38.8 mol% of manganese oxide (MnO), 7.3-9.0 mol% of zinc oxide (ZnO), and other inevitable impurities. A second mixture is manufactured by adding 300-600 ppm of calcium oxide (CaO), 10-30 ppm of silicon oxide (SiO2), 250-500 ppm of niobium oxide (Nb2O3), and 3000-5000 ppm of cobalt oxide (Co3O4) powder to the first mixture. A sintered body is manufactured by thermally processing the second mixture.

Description

TECHNICAL FIELD The present invention relates to a ferrite composition, a ferrite magnetic material using the ferrite composition, and a method for producing the ferrite magnetic material,

More particularly, the present invention relates to a ferrite composition capable of preventing core loss and improving saturation magnetic flux density, a ferrite magnetic material using the ferrite composition, and a method for producing the ferrite magnetic material.

Ferrite is an oxide-based magnetic material containing iron oxide (Fe ₂ O ₃ ) as a main component and can be divided into soft ferrite, hard ferrite and radial ferrite depending on its magnetic properties. Soft ferrite is a soft magnetic material that exhibits magnetism in a magnetic field, and is characterized by less eddy current loss in a high frequency band as compared with a metal. Hard ferrite is a kind of permanent magnet and is applied to generate a magnetic field. As an example, Ba and Sr ferrite are typical, and magnetic anisotropy is large and low in value. The radial magnetic ferrite is not easily magnetized, but once magnetized, it can maintain its state. Further, the radial magnetic ferrite can be easily degauss, and is applied to a storage memory, a tape, a disk, or the like as a medium.

Among the above-mentioned applications, ferrite cores which are applied to the core of a coil part can be manufactured by compressing and heat-treating and sintering a ferrite material. The ferrite core is used as a magnetic core of a main transformer and an output inverter for a low voltage DC-DC converter (LDC), for example. Recently, the development of hybrid electric vehicle (HEV) or electric vehicle (EV) has expanded, and soft magnetic materials for transformers or inductors have begun to attract attention.

On the other hand, an important characteristic required for a magnetic body to be applied to a ferrite core for an LDC transformer or an inductor of a hybrid car is a low core loss and a high saturation magnetic flux density. That is, as the core loss value becomes smaller, the larger the saturation magnetic flux density, the more the heat loss due to the current decreases, so that the stable operation can be realized.

In recent years, ferrite cores have been mainly applied to transformers and inverters of home appliances and communication equipments. However, since the core loss value is relatively large and the saturation magnetic flux density value is relatively small to be applied to the LDC transformer or the magnetic core for inductors of recent hybrid cars, Performance deterioration due to heat generation may occur. In order to overcome this problem, there is a method of increasing the size of the ferrite core, but in this case, it may not be suitable for space-restricted automobiles. In addition, the conventional ferrite core may not be suitable for automobiles operating in extreme environments due to a significant change in core loss due to temperature changes. Accordingly, it is necessary to develop a low-loss ferrite core applicable to an LDC transformer of a hybrid car or a magnetic core for an inductor.

Embodiments of the present invention provide a ferrite composition applied to a magnetic core configured to have a low core loss and a high saturation magnetic flux density.

A method of manufacturing a ferrite magnetic body according to an aspect of the present invention is disclosed. In the method for producing a ferrite magnetic material, it is preferable that the ferrite magnetic material contains 52.0 to 54.5 mol% of iron oxide (F ₂ O ₃ ), 36.4 to 38.8 mol% of manganese oxide (MnO), 7.3 to 9.0 mol% of zinc oxide (ZnO) Thereby providing a first mixture. Wherein the first mixture contains 300 to 600 ppm of calcium oxide (CaO), 10 to 30 ppm of silicon oxide (SiO ₂ ), 250 to 500 ppm of niobium oxide (Nb ₂ O ₃ ), and cobalt oxide (Co ₃ O ₄ ) To 5,000 ppm of powder is added to prepare a second mixture. The second mixture is heat-treated to prepare a sintered body.

A ferrite composition according to another aspect of the present invention is disclosed. The ferrite composition is prepared by mixing an additive in a first mixture of 52.0 to 54.5 mol% of iron oxide (F2O3), 36.4 to 38.8 mol% of manganese oxide (MnO), 7.3 to 9.0 mol% of zinc oxide (ZnO), and other unavoidable impurities 2 mixture. The additive is the first of the two mixtures, calcium (CaO) 300 to 600 ppm, silicon dioxide oxide (SiO ₂₎ 10 to 30 ppm, and niobium (Nb ₂ O ₃₎ 250 to 500 ppm, the oxidation of cobalt oxide (Co ₃ O ₄ ) Has a concentration of 3000 to 5000 ppm.

The ferrite magnetic material according to another aspect of the present invention is a sintered product of the ferrite composition of the above composition and has a grain size of 5 to 10 mu m.

According to the embodiments of the present disclosure, by applying the ferrite composition having the composition described above, it is possible to manufacture a ferrite magnetic body having a smaller core loss value and a larger saturation magnetic flux density than conventional ones. Further, it is possible to manufacture a ferrite magnetic body having a small core loss value deviation per temperature as compared with the prior art.

Specifically, by incorporating calcium oxide, silicon oxide, cobalt oxide and niobium oxide in a predetermined composition as a minor additive in addition to iron oxide, manganese oxide and zinc oxide, which are main raw materials for mixing, a ferrite magnetic material that realizes the above- .

1 is a flowchart schematically showing a method of manufacturing a ferrite magnetic material according to an embodiment of the present application.
2 is a photomicrograph showing microstructure of a ferrite magnetic body manufactured according to an embodiment of the present invention.

In the description of the embodiments of the present disclosure, the description that a substrate is located on the "upper" or "upper" or "lower" side of a member refers to a relative positional relationship, But does not limit the particular case in which further elements are introduced. It should also be understood that the description of " connected " or " installed " to one component may be directly connected or connected to another component, Elements may be intervened to form a connection or connection relationship. Like reference numerals throughout the specification may mean substantially identical components.

1 is a flowchart schematically showing a method of manufacturing a ferrite magnetic material according to an embodiment of the present application. Referring to FIG. 1, first, in step S110, a first ( _first ) layer containing 52.0 to 54.5 mol% iron oxide (Fe ₂ O 3), 36.4 to 38.8 mol% manganese oxide (MnO), and 7.3 to 9.0 mol% Lt; / RTI > The first mixture may contain, in addition to the above-mentioned materials, other unavoidable impurities.

The iron oxide, manganese oxide and zinc oxide of the above-mentioned composition are provided in the form of powders and mixed so that the first mixture can be produced. In one embodiment, the powder of the iron oxide, the manganese oxide, and the zinc oxide may be pulverized to have a lower 50% average particle diameter of 1.10 to 1.20 mu m. More specifically, the iron oxide, the manganese oxide, and the zinc oxide powder may be pulverized to have a lower 90% average particle diameter of 1.80 to 1.90 탆.

The above-described iron oxide, manganese oxide and zinc oxide may have the following characteristics depending on the content of the ferrite magnetic body or the material constituting the basic framework of the ferrite magnetic body manufactured through the process described below. The iron oxide may be applied for the purpose of increasing the permeability, magnetic flux density and Curie temperature (Tc) of the ferrite magnetic body. The manganese oxide is known to affect the permeability ([mu] _i ) of the ferrite magnetic material, and the larger the specific surface area, the more advantageous it can be. As one example, the lower the content of manganese oxide in the ferrite magnetic body, the higher the magnetic permeability, saturation flux density, and core loss of the ferrite magnetic body. On the other hand, as the content of zinc oxide in the ferrite magnetic body increases, the permeability increases and the saturation magnetic flux density decreases. Also, as the content of zinc oxide increases, the Curie temperature decreases and the core loss increases. Taking this into consideration, in this embodiment, the mixing ratios of iron oxide, manganese oxide and zinc oxide as described above are presented.

Referring to S120, to the first mixture, calcium (CaO) 300 to 600 ppm, silicon dioxide oxide (SiO ₂₎ 10 to 30 ppm, niobium oxide (Nb ₂ O ₃₎ 250 to 500 ppm, cobalt oxide (Co ₃ O ₄ ) 3000 to 5000 ppm powder is added to prepare a second mixture. The concentration of the calcium oxide, silicon oxide, niobium oxide and cobalt oxide may be in terms of ppm by mass with respect to the whole second mixture.

The calcium oxide is segregated at the crystal grain boundaries to increase the grain boundary resistance and to prevent the core loss. In this case, when the concentration of calcium oxide is less than 300 ppm, the specific resistance decreases and the effect of preventing the core loss is small. On the contrary, when the concentration exceeds 600 ppm, the core loss increases and the material embrittlement may be increased.

The silicon oxide may be located at crystal grain boundaries when fabricating a sintered body to be described later, and may increase the specific resistance to prevent core loss. At this time, the silicon oxide may coexist with the calcium oxide and exist in the crystal grain boundaries. In this case, when the concentration of the silicon oxide is less than 10 ppm, the resistivity decreases and the effect of preventing the core loss is small. On the contrary, when the concentration exceeds 30 ppm, the core loss increases and the material embrittlement increases.

The niobium oxide can suppress the growth of the crystal grains and reduce the size of the crystal grains and increase the resistivity. As a result, the core loss can be prevented. In particular, niobium oxide can improve the high frequency characteristics of the ferrite magnetic body. In this case, when the concentration of niobium oxide is less than 250 ppm, the effect of suppressing the grain size is insufficient and the effect of decreasing the core loss is small. When the concentration exceeds 500 ppm, the defect occurrence rate in the ferrite magnetic body is increased and the core loss may be increased.

When the cobalt oxide is dissolved in the spinel lattice, it may be substituted with iron ions (Fe ²⁺ ) to reduce the crystal magnetic anisotropy. As a result, the permeability can be increased and the core loss can be reduced. However, when the concentration of the cobalt oxide is less than 3000 ppm, the effect of increasing the permeability and decreasing the core loss is small, and the amount of change in the core loss due to the temperature change may increase. If it exceeds 5,000 ppm, the rate of occurrence of defects in the ferrite magnetic body is increased and the core loss may increase.

Taking this into consideration, in this embodiment, mixing ratios in the second mixture of calcium oxide, silicon oxide, niobium oxide, and cobalt oxide as described above are presented.

Referring to S130, the second mixture is heat-treated to produce a sintered body. In one embodiment, the step of heat-treating the second mixture may be carried out by charging the second mixture into a sintering furnace and holding the mixture at a temperature of 1300 ° C to 1400 ° C for 5 hours to 6 hours. Thereafter, the ferrite magnetic body can be produced by cooling with a method of air cooling or nitrogen flow.

Through the above-described embodiment of the present invention, a ferrite magnetic body can be produced from a ferrite composition through a sintering process. The ferrite composition is characterized in that the additive is added to the first mixture of 52.0 to 54.5 mol% of iron oxide (Fe ₂ O ₃ ), 36.4 to 38.8 mol% of manganese oxide (MnO), 7.3 to 9.0 mol% of zinc oxide (ZnO) and other unavoidable impurities And may have the form of a mixed second mixture. In this case, the additive is the first of the two mixtures, calcium (CaO) 300 to 600 ppm, silicon dioxide oxide (SiO ₂₎ 10 to 30 ppm, niobium oxide (Nb ₂ O ₃₎ 250 to 500 ppm, cobalt oxide (Co ₃ O ₄ ) may have a concentration of 3000 to 5000 ppm.

2 is a photomicrograph showing microstructure of a ferrite magnetic body manufactured according to an embodiment of the present invention. Specifically, FIG. 2A is a photograph of a conventional ferrite magnetic body as a comparative example, and FIG. 2B is a photograph of a structure of a ferrite magnetic body according to an embodiment of the present invention.

The ferrite magnetic material as a comparative example was prepared by sintering a mixture containing 53.43 mol% iron oxide (Fe ₂ O ₃ ), 37.93 mol% manganese oxide (MnO) and 8.64 mol% zinc oxide (ZnO) at a temperature of 1300 ° C. On the other hand, the ferrite magnetic material as one embodiment is a mixture of calcium oxide (CaO) and magnesium oxide (CaO) in a first mixture containing 53.43 mol% iron oxide (Fe ₂ O ₃ ), 37.93 mol% manganese oxide (MnO), and 8.64 mol% A second mixture was prepared by adding additives such that the concentration of the first mixture was 400 ppm, silicon oxide (SiO ₂ ) 20 ppm, niobium oxide (Nb ₂ O ₃ ) 300 ppm, and cobalt oxide (Co ₃ O ₄ ) 4000 ppm. The second mixture was prepared by sintering at a temperature of 1300 ° C.

Referring to FIGS. 2 (a) and 2 (b), the grain size of the ferrite magnetic material of the comparative example of FIG. 2 (a) may be about 10 to 30 .mu.m, and the deviation may be about 20 .mu.m. On the contrary, the grain size of the ferrite magnetic material of the embodiment of the present invention shown in FIG. 2 (b) may be about 5 to 10 μm, and the deviation may be about 5 μm. As described above, the ferrite magnetic body according to the embodiment of the present invention has a crystal grain size uniformly distributed as compared with the conventional ferrite magnetic body, and therefore, it is judged to have a low internal defect density.

Then, the core loss and the saturation magnetic flux density of the conventional ferrite magnetic material as a comparative example and the ferrite magnetic material prepared according to the embodiment of the present invention were measured and shown in Table 1. The core loss per temperature was measured at 100 kHz, and 200 mT.

Saturated magnetic flux density (mT) Core loss (mW / cm ³ ) Temperature 25 ℃ 100 ℃ 25 ℃ 80 ℃ 100 ℃ 120 DEG C Comparative Example 480 370 650 450 350 400 Example 530 420 350 290 310 350

As shown in Table 1, the saturation magnetic flux density of the ferrite magnetic material according to the embodiment of the present invention is 530 mT at 25 ° C and 370 mT at 100 ° C, respectively, which is 50 mT higher than the ferrite magnetic material of the comparative example . As a result, it can be seen that the saturation magnetic flux density is superior to that of the conventional ferrite magnetic body.

On the other hand, in the case of the core loss, the core loss value according to the temperature of the ferrite magnetic body according to the embodiment of the present invention is maintained at a value of 290 to 350 mW / cm < 3 >. That is, the maximum deviation by temperature is 60 mW / cm 3. Particularly, since the same core loss was exhibited at 25 ° C and 120 ° C, it can be confirmed that the temperature-dependent variation was significantly reduced compared with the comparative example.

In addition, the absolute value of the core loss of the ferrite magnetic body was also lower than that of the comparative example by 40 to 360 mW / cm < 3 >. Particularly, the core loss value was relatively lower at 25 캜 and 80 캜 than the comparative example, and was lower than that of Comparative Example at 100 캜 and 120 캜 by 40 mW / cm 3.

From the experimental results shown in Table 1, it can be seen that the magnetic properties of the ferrite magnetic body manufactured according to the embodiment of the present invention are superior to those of the conventional ferrite magnetic body.

Although the embodiments of the present invention have been illustrated and described with reference to the drawings, it is to be understood that the present disclosure is intended to be illustrative and not restrictive. Various other modifications will be possible as long as the technical ideas presented in this disclosure are reflected.

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Claims (7)

Providing a first mixture comprising 52.0 to 54.5 mol% of iron oxide (Fe ₂ O ₃ ), 36.4 to 38.8 mol% of manganese oxide (MnO), 7.3 to 9.0 mol% of zinc oxide (ZnO), and other unavoidable impurities;
Wherein the first mixture contains 300 to 600 ppm of calcium oxide (CaO), 10 to 30 ppm of silicon oxide (SiO ₂ ), 250 to 500 ppm of niobium oxide (Nb ₂ O ₃ ), and cobalt oxide (Co ₃ O ₄ ) To 5,000 ppm of powder to prepare a second mixture; And
And heat treating the second mixture to produce a sintered body
A method of manufacturing a ferrite magnetic body.
The method according to claim 1,
The step of preparing the first mixture
Mixing the iron oxide (F2O3), the manganese oxide and the zinc oxide in powder form
A method of manufacturing a ferrite magnetic body.
3. The method of claim 2,
The iron oxide, manganese oxide and zinc oxide powder have a lower 50% average grain size of 1.10 to 1.20 mu m
A method of manufacturing a ferrite magnetic body.
The method according to claim 1,
The step of heat treating the second mixture
Lt; RTI ID = 0.0 > 1300 C < / RTI > to 1400 C for 5 to 6 hours
A method of manufacturing a ferrite magnetic body.
A second mixture of additives is added to a first mixture consisting of 52.0 to 54.5 mol% of iron oxide (Fe ₂ O ₃ ), 36.4 to 38.8 mol% of manganese oxide (MnO), 7.3 to 9.0 mol% of zinc oxide (ZnO) and other unavoidable impurities It is a form of mixture,
The additive is the first of the two mixtures, calcium (CaO) 300 to 600 ppm, silicon dioxide oxide (SiO ₂₎ 10 to 30 ppm, and niobium (Nb ₂ O ₃₎ 250 to 500 ppm, the oxidation of cobalt oxide (Co ₃ O ₄ ) Having a concentration of 3000 to 5000 ppm
Ferrite composition.
A sintered body having the composition of claim 5,
Having a grain size of 5 to 10 mu m
Ferrite magnetic body.
The method according to claim 6,
At 100 KHz and 200 mT,
Having a core loss of 290 to 350 mW / cm < 3 > within a temperature range of 25 &
Ferrite magnetic body.

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