JPH04237104A - Ferrite magnetic material and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain superlow shrinkage factor ferrite magnetic material, having no DC superpositional deterioration, which can be utilized for various electronic parts. CONSTITUTION:A ferrite magnetic material, having excellent DC superpositional characteristics and ultra-low shrinkage factor, can be obtained by heat-treating the mixture of glass powder, containing Sb component, and high crystallinity ferrite powder at the temperature higher than glass softening point and lower than the calcination temperature of the above-mentioned ferrite powder; and high crystallinity ferrite powder 1, abundantly containing Sb component, is bonded on the outside surface of the above-mentioned powder.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention applies to transformers, inductors,
The present invention relates to a ferrite magnetic material with an ultra-low shrinkage rate obtained by bonding and solidifying highly crystalline ferrite powder with a glass material, which is used in various electronic components such as magnetic heads, and a method for manufacturing the same.

0002

[Prior Art] The conventional method for manufacturing ferrite magnetic material is as follows:
Most of the methods are powder metallurgy, that is, sintering methods that require powder compaction and high-temperature firing steps.

[0003] When producing a Ni-Zn-Cu based ferrite magnetic material, the starting materials Fe2O3, NiO, ZnO,
CuO is mixed in a predetermined ratio, pre-calcined at about 700 to 1000°C in order to proceed with degassing and a certain degree of solid phase reaction, and then through the steps of pulverization, granulation, and molding.
A polycrystalline ferrite magnetic material is obtained by subjecting the compact to main firing in an appropriate atmosphere at a temperature of about 1,000 to 1,400°C, which is higher than the above-mentioned calcination temperature.

In order to obtain desired magnetic properties, small amounts of various oxides are often added to the above-mentioned starting materials. For example, JP-A-55-67565, JP-A-60
Many studies have been made, including the addition of various oxides, as seen in Japanese Patent Application Laid-open No. 210572, Japanese Patent Application Laid-Open No. 63-260006, and Japanese Patent Application Laid-Open No. 63-275104.

[0005]

[Problems to be Solved by the Invention] Ferrite magnetic materials obtained by conventional techniques undergo firing shrinkage of several tens of percent during main firing, causing distortion and cracks in the shape of the fired product.

[0006] Therefore, it has been possible to suppress the firing shrinkage rate to several percent in the following manner. That is, a highly crystalline ferrite powder that has been sufficiently spinelized at a high temperature is mixed with a glass powder that has a softening point lower than this firing temperature, and after molding, An ultra-low shrinkage ferrite magnetic material in which highly crystalline ferrite powder is bonded with glass was obtained by heat treatment at a temperature below the sintering temperature of ferrite powder.

However, since the ultra-low shrinkage ferrite magnetic material described above has a structure in which it is bonded with a non-magnetic material, it has the disadvantage that the DC superimposition characteristics are worse than that of conventional ferrite magnetic materials.

[0008] The present invention particularly aims at improving the direct current superimposition characteristics in an ultra-low shrinkage ferrite magnetic material.

[0009]

[Means for Solving the Problems] In order to solve the above problems, the present invention uses highly crystalline ferrite powder and at least S
A mixture with a glass powder containing component b or a mixture of a highly crystalline ferrite powder, a glass powder, and powdered antimony trioxide is heated at a temperature higher than the temperature at which a melting reaction occurs between the glass powder and antimony trioxide, and at the above-mentioned temperature. The material is heat-treated at a temperature below the firing temperature of crystalline ferrite powder to produce an ultra-low shrinkage ferrite magnetic material having a structure in which highly crystalline ferrite powder is bound with a glass material.

0010

[Function] As mentioned above, the Sb component contained in the glass material, which is the binder for the highly crystalline ferrite powder, diffuses into the highly crystalline ferrite powder during heat treatment, and the treatment time is short. Sb cannot be sufficiently diffused, resulting in a structure in which a large amount of Sb is present on the outer surface of the highly crystalline ferrite powder.
It is thought that the DC superposition characteristics are improved.

[0011] Similar results were obtained even when a mixture of highly crystalline ferrite powder, glass powder, and antimony trioxide was used because the melting reaction between the glass powder and antimony trioxide occurred first, and the Sb component This is thought to be due to the fact that the same state occurs when glass containing Sb is mixed, and then a part of the Sb component diffuses to the outer surface of the ferrite powder.

0012

[Examples] Examples of the present invention will be described below.

That is, the present invention, as shown in FIG. 1, uses a glass material 2 that softens and melts a highly crystalline ferrite powder 1 having a large Sb component on its outer surface at a temperature below the firing temperature of the highly crystalline ferrite powder 1. It is intended to have a cohesive structure. In the figure, 3 is a void, and 4 is a highly crystalline ferrite powder 1.
It is the pore inside.

Specifically, highly crystalline ferrite powder 1 and glass powder containing an Sb component are thoroughly mixed. In some cases, for example, in cases where it is desired to contain so much Sb that it is difficult to make glass, highly crystalline ferrite powder 1, glass powder, and powdered antimony trioxide are thoroughly mixed, and this mixture is granulated. After pressure molding, by softening and melting the glass powder mixed between the highly crystalline ferrite powders 1 in this compact, the highly crystalline ferrite powders 1 are bound and solidified with the glass material 2 to form ferrite magnetism. Body. However, when mixing powdered antimony trioxide, it is necessary to heat the glass powder to a temperature at which the antimony trioxide melts and reacts.

Highly crystalline ferrite powder 1 used here
is one that has been sufficiently turned into spinel by firing at a high temperature, and is usually preferably one that is fired at a temperature of 1000° C. or higher.

In order to obtain a soft ferrite magnetic material, the smaller the coercive force Hc of the highly crystalline ferrite powder 1, the better; therefore, the larger the size of the magnetic powder, the better.
Since the packing density of the highly crystalline ferrite powder 1 decreases, a diameter of 100 to 200 μm is actually suitable.

Next, the softening temperature of the glass material 2 that binds the highly crystalline ferrite powder 1 may be lower than the heat treatment temperature, but considering the application of the ferrite magnetic material according to the present invention, the lower limit must be set from the viewpoint of heat resistance. It is desirable that the temperature is 300°C or higher. The amount of glass powder added to the highly crystalline ferrite powder 1 is preferably 0.3 to 30 wt%, and if it is less than 0.3 wt%, the binding effect of the highly crystalline ferrite powder 1 is small and mechanical strength cannot be ensured. On the other hand, if the amount of glass is more than 30 wt%, the binding force will be sufficiently strong, but since the amount of non-magnetic material will increase, the magnetic properties as a ferrite magnetic material will be significantly deteriorated, which is not preferable.

A specific example will be described below. (Example 1) A mixture of Fe2O3, NiO, ZnO, and CuO in a molar ratio of 49.0:16.0:28.0:7.0, and a mixture of 0.09 Sb2O3 to the above mixture.
The mixtures added in parts by weight were separately calcined at 1320° C. for 6 hours to prepare two types of Ni-Zn-Cu-based ferrite powders having an average particle size of 70 μm. As a result of X-ray analysis, sharp spinel structure diffraction lines characteristic of soft ferrite were obtained for both types, confirming that they were ferrite magnetic powders with extremely high crystallinity, that is, spinelization had progressed sufficiently.

On the other hand, 5 wt% of Sb2O3 was added to an alkali-free lead borosilicate glass containing no Sb component, and 80
After heating and melting at 0°C, the S
A glass powder containing component b was prepared. As a result of X-ray analysis, a diffraction pattern unique to glass was obtained, confirming that sufficient reaction had occurred and vitrification had occurred.

[0020] 3 parts by weight of the above-mentioned glass powder containing 5.0 wt% of Sb component was mixed with the above-mentioned highly crystalline ferrite powder to which no Sb2O3 was added, and after granulating the mixture, the inner diameter was 7mm, outer diameter 12mm
, a ring-shaped molded product with a thickness of 3 mm was created. This molded product was placed in an electric furnace and heat-treated in air at 1200° C. for 60 minutes to obtain a glass-bonded ring-shaped ferrite core (Product 1 of the present invention).

On the other hand, the above-mentioned highly crystalline ferrite powder to which no Sb2O3 is added, glass powder containing no Sb component, and Sb2O3 are thoroughly mixed in a weight ratio of 100:2.85:0.15, and from this mixture, a book is prepared. A glass-bound ring-shaped ferrite core was obtained under the same conditions as Invention Product 1 (Invention Product 2).

For comparison, a glass was prepared under the same conditions as Inventive Product 1 from a mixture in which 3.0 parts by weight of alkali-free lead borosilicate glass containing no Sb component was added to the above-mentioned highly crystalline ferrite powder to which Sb2O3 was added. A bonded ring-shaped ferrite core was obtained (comparative product).

Inventive product 1, inventive product 2, and comparative product are completely the same compositionally. FIG. 2 is a diagram showing the rate of change of initial magnetic permeability in each DC superimposed magnetic field with respect to the case without the DC superimposed magnetic field, and the closer it is to zero, the better the DC superimposed characteristics are. As shown in Table 1, the firing shrinkage rate is less than 1%, and there is almost no difference in the density of the compacts. Moreover, no difference is observed in scanning electron microscopy of these microstructures. Nevertheless, by containing the Sb component, Invention Product 1 and Invention Product 2 have smaller changes in initial magnetic permeability with respect to a DC superimposed magnetic field than comparative products, that is, an improvement in DC superimposition characteristics is observed.

[0024]

[Table 1]

(Example 2) Three ring-shaped molded bodies were prepared under the same conditions as in Example 1 (inventive product 1, inventive product 2).
, comparative products) were placed in an electric furnace and heat-treated at 1200°C. The temperature profile at that time was a temperature increase rate of 240℃/1h, a high temperature rate of 300℃/h, and a temperature profile of 120℃/1h.
The holding time at 0°C was 30 to 180 minutes. The characteristics of the obtained magnetic material are shown in FIG. There is almost no difference in the characteristics between Inventive Product 1 and Inventive Product 2, and both have excellent DC superimposition characteristics at all holding times compared to the comparative product. However, as the holding time becomes longer, the characteristics become closer to those of the comparative product. The microstructure was observed using a scanning electron microscope, but no structural changes such as ferrite grain growth were observed. This indicates that the product of the present invention has an Sb component on the outer surface of the highly crystalline ferrite powder, and the retention time is This is thought to mean that as the length increases, the Sb component diffuses into the highly crystalline ferrite powder, and the composition distribution approaches that of the comparative product. Retention time is 60 as shown in Figure 3.
The characteristics of the DC superimposition limit point of the present invention are clearly visible when the voltage is set to less than 1 minute.

(Example 3) Fe2O3, NiO and ZnO
The blending molar ratio of and CuO is 49.0:16.0:28.0
:7.0 was fired at 1320° C. for 6 hours to prepare Ni-Zn-Cu soft ferrite powder with an average particle size of 70 μm. As a result of X-ray analysis, sharp spinel structure diffraction lines characteristic of soft ferrite were obtained, confirming that the powder was a highly crystalline ferrite magnetic powder, that is, spinelization had progressed sufficiently.

[0027] Regarding the above-mentioned highly crystalline ferrite powder, Sb
A ring-shaped ferrite core was prepared under the same conditions as in Example 1 from a mixture containing 3 parts by weight of alkali-free lead borosilicate glass powder and 0 to 0.50 parts by weight of powdered Sb2O3.

[0028] When the amount added is greater than 0.20 parts by weight,
As shown in Fig. 4, although the initial permeability decreases, the DC superimposition characteristics do not change much, so Sb2O3
The addition amount is preferably 0.20 parts by weight or less.

[0029] Here, even if part or all of the powdered Sb2O3 mixed with the highly crystalline ferrite powder is used as the Sb component of the alkali-free lead borosilicate glass, the same characteristics can be obtained as shown in the example. It is clear from 1.

In the above example, the initial magnetic permeability was measured in accordance with the JIS standard (C2561). First, one layer of insulating tape was wrapped around the ring-shaped ferrite core, and then an insulated copper wire with a wire diameter of 0.26 mmφ was wrapped around the ring-shaped ferrite core. A sample was prepared that was wrapped in one layer around the entire circumference. Next, the self-inductance L at 10 kHz to 10 MHz was measured with a Maxwell bridge at a measurement magnetic field strength of 0.8 (A/m) or less, and the initial magnetic permeability was calculated from the self-inductance L.

Further, the DC superimposed magnetic field when the initial magnetic permeability decreased by 10% compared to the case without the superimposed magnetic field was defined as the DC superimposed limit point.

[0032]

As described above, according to the present invention, in a glass bonded ultra-low shrinkage ferrite magnetic material using highly crystalline ferrite powder, Sb components are present on the outer surface of the highly crystalline ferrite powder. With this structure, it becomes a magnetic material with excellent direct current superimposition characteristics, and can exhibit excellent effects as a useful electronic component material used in various magnetic application products.

[Brief explanation of the drawing]

[Fig. 1] Schematic diagram of a microstructure showing an example of the ferrite magnetic material of the present invention

[Fig. 2] DC superposition characteristic diagram in the first embodiment

[Figure 3]
Diagram showing the relationship between the holding time at 1200°C and the DC superposition limit point in the second example

[Fig. 4] A diagram showing the relationship between the blending amount of Sb2O3 and the DC superposition limit point in the third example.

[Explanation of symbols] 1 Highly crystalline ferrite powder 2 Glass material 3 Voids 4 Pore

Claims (3)

[Claims] Claim 1: Ni that has been sufficiently turned into spinel by high-temperature firing
- A ferrite magnetic material in which a Zn-based or Ni-Zn-Cu-based highly crystalline ferrite powder having a higher Sb content on its outer surface than its inside is bonded with a glass material having a softening point lower than that of the fired ferrite powder. Claim 2: Ni that has been sufficiently spinelized by high-temperature firing
- Pressure molding of a mixture obtained by mixing and granulating Zn-based or Ni-Zn-Cu-based highly crystalline ferrite powder and glass powder that has a softening point lower than this fired ferrite powder and contains at least an Sb component. After that, the glass powder mixed in the molded body is softened and melted by heat treatment at a temperature below the firing temperature of the highly crystalline ferrite powder, and the highly crystalline ferrite powder is bound with a glass material. . [Claim 3] Ni-Z that is sufficiently spinelized at high temperatures
A mixture of n-based or Ni-Zn-Cu-based highly crystalline ferrite powder, glass powder with a softening point lower than that of the fired ferrite powder, and powdered antimony trioxide is mixed and granulated, and then the mixture is pressure-molded. and a method for producing a ferrite magnetic material, which comprises binding highly crystalline ferrite powder with a glass material by heat treatment at a temperature higher than the temperature at which the glass powder and antimony trioxide melt and react and lower than the firing temperature of the high crystalline ferrite powder.