JPH07230909A - Manganese-zinc ferrite core and its manufacture - Google Patents

Abstract

PURPOSE:To provide a low-loss manganese-zinc ferrite core having high permeability and high resistance, and its manufacturing method. CONSTITUTION:This core is made up of a material having a main component composed of 45-48.6mol% of Fe2O3, Mn2O3 of a molar ratio whose sum with the mole percentage of Fe2O3 is approximately 50mol%, 28-50mol% of MnO, and the remaining ZnO, and 0.01-0.5wt.% of a subcomponent including SiO2 and CaO, and Fe<2+> is less than 1mol% (other than 0mol%). By making the sum of Fe2O3 and Mn2O3 approximately 50mol% in spite of Fe2O3<50mol%, perfect spinel structure can be adopted and it is beneficial to the magnetic characteristic. By selecting sintering conditions, the production of Fe<2+> in a sintering process is lessened, and Mn<3+> of an Mn component supplementing the shortage of Fe2O3 in place of Fe<2+>, and consequently the production of Fe<2+> is suppressed. And it becomes possible to make the resistance higher by bringing in the grain boundary high-resistance phases of SiO2 and CaO.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manganese-zinc ferrite core suitable for a deflection yoke core and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, deflection yoke cores have been required to have characteristics such as high permeability (high saturation magnetic flux density) and low loss (low core loss) more than ever before. High resistance is also required at the same time so that it can be directly wound around the core.

In order to obtain high magnetic permeability and low loss, manganese zinc (MnZn) -based ferrite having a composition of iron oxide (Fe ₂ O ₃ )> 50 mol% is generally used to control the oxygen partial pressure. 1 mol% or more of divalent iron ion (Fe ²⁺ )
Is being generated. However, the resistance of the ferrite of this composition system is 1 × 10 ⁴ Ω, which is remarkably low as compared with the ferrite (1 × 10 ⁸ Ω) having a composition of Fe ₂ O ₃ <50 mol% (see the table below). 1 and 2). In addition, it has been attempted to increase the resistance with this ferrite, but the surface oxidation treatment method of that example improves the surface resistance, but it is not practical because residual stress on the surface and inside deteriorates the magnetic characteristics. . Further, although a method of coating an insulating layer on the surface has been put into practical use, the cost is high.

Further, as a ferrite core having a high resistance, nickel zinc (N ₂ having a composition of Fe ₂ O ₃ <50 mol% is used).
iZn) -based and magnesium zinc (MgZn) -based ferrites have been put to practical use. However, the ferrite core loss of this composition system has a saturation magnetic flux density of 300 as compared with MnZn ferrite (saturation magnetic flux density = 510 mT, core loss = 3 kW / m ³ ) of Fe ₂ O ₃ > 50 mol% composition.
It has a drawback that it is as low as mT and the core loss is as high as 40 kW / m ³ (see Tables 1 and 2 described later).

Fe ₂ O ₃ <50 mol% composition of Mn
Zn-based ferrite has not been put to practical use because its magnetic properties are inferior and sufficient resistance cannot be obtained.

Although the object is different from that of the present invention, Fe ₂
As a ferrite having a composition of O ₃ <50 mol%, 35 to 4
A high-density ferrite having a composition of 8 mol% Fe ₂ O ₃ , 22 to 50 mol% MnO and 15 to 30 mol% ZnO is known (JP-A-48-57193). Also known is a ferrite magnetic core in which 1.3 to 1.5 mol% of cobalt oxide is added to MnZn ferrite composed of 48 to 50 mol% of Fe ₂ O ₃ , 11 mol% of ZnO and the balance of MnO ( Japanese Patent Publication No. 52-475
3 gazette).

[0007]

As described above, in the conventional ferrite core, high resistance is not obtained even if high permeability and low loss can be achieved. Even if high resistance is achieved, high permeability and low permeability are achieved. Since no loss can be obtained, there has been a problem in recent years that the high permeability, low loss and high resistance required for the deflection yoke core cannot be satisfied.

In the high-density ferrite disclosed in Japanese Patent Laid-Open No. 48-57193, the Fe ₂ O ₃ deficiency is reduced to Mn.
^In the composition range of 35 <Fe ₂ O ₃ <48 mol% when ³⁺ occupies, the density is set to about 1 O ⁴ Ω because a vacuum portion is provided in the firing process to increase the density. Also, F
In the composition range of e ₂ O ₃ <45 mol%, high saturation magnetic flux density and low core loss are lost, so that it cannot be put to practical use.

Further, in the ferrite core disclosed in Japanese Patent Publication No. 52-4753, when Mn ³⁺ occupies the Fe ₂ O ₃ deficiency, in the composition range of 48 <Fe ₂ O ₃ <50 mol%, Since the amount of Fe ₂ O ₃ is large and the valence control by the above-mentioned Mn component is incomplete, the composition region becomes Fe.
^The amount of ²⁺ produced sharply increases and high resistance is impaired.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a manganese-zinc ferrite core having a high magnetic permeability, a low loss, and a high resistance, and a method for manufacturing the same. is there.

[0011]

A manganese-zinc-based ferrite core according to claim 1 has an F content of 45 to 48.6 mol%.
e ₂ O ₃ and Fe ₂ O ₃ are contained in a molar ratio of about 50 mol% Mn ₂ O ₃ , 28 to 50 mol% MnO and the balance ZnO, and SiO ₂ and CaO. It is characterized in that it is made of a material having 0.01 to 0.5% by weight of an accessory component, and Fe ²⁺ is 1 mol% or less (excluding 0 mol%).

A method for producing a manganese-zinc-based ferrite core according to claim 2 is 45 to 48.6 mol% of Fe ₂ O.
₃ , the molar ratio of M such that the sum of Fe ₂ O ₃ and Fe ₂ O ₃ is approximately 50 mol%.
n ₂ O ₃ , 28 to 50 mol% MnO and balance Zn
0.0 including a main component of O and SiO ₂ and CaO
A method for producing a manganese-zinc-based ferrite core made of a material having 1 to 0.5% by weight of an accessory component, wherein Fe ^{2+ is set} to 1 mol% or less (excluding 0 mol%) by selecting firing conditions. It is characterized by that.

In the method for producing a manganese-zinc-based ferrite core according to claim 3, the oxygen partial pressure at the maximum holding temperature is 1
The firing is performed at 100% to 100%.

[0014]

The operation of the manganese-zinc-based ferrite core according to claim 1 will be described with reference to FIGS. 1 to 3. Figure 1 shows Fe
₂ is a relationship diagram between the amount of ₂ O ₃ and core loss, FIG. 2 is a relationship diagram between the amount of Fe ₂ O ₃ and saturation magnetic flux density, and FIG. 3 is a relationship diagram between Fe ₂ O ₃ and contact resistance.

According to the manganese-zinc-based ferrite core having the above-described structure, Fe ₂ O ₃ <50 mol% but Fe ₂
By setting the sum of O ₃ and Mn ₂ O ₃ to about 50 mol%, the valence of Mn is controlled, and a complete spinel structure is adopted, which is advantageous in terms of magnetic properties. Also, by selecting the firing conditions, the production of Fe ²⁺ is reduced in the firing process, and Mn ^{3+ of} Mn component that supplements the shortage of Fe ₂ O ₃ is produced instead of Fe ²⁺ , and as a result, the resistance of The production of Fe ²⁺ which causes a decrease is suppressed. In addition, by introducing a grain boundary high resistance phase of SiO ₂ and CaO, it is possible to promote high resistance.

When Fe ₂ O ₃ <45 mol%,
As shown in FIG. 1, the core loss (Pcv) is 12 kW / m ³
As described above, the saturation magnetic flux density (Bs) becomes 320 mT or less as shown in FIG. 2, and the high saturation magnetic flux density and the low core loss which are the objects of the present invention cannot be achieved, and it becomes unusable for practical use. When 48.6 mol% <Fe ₂ O ₃ , the contact resistance sharply decreases as shown in FIG. Therefore, the Fe ₂ O ₃ content is in the range of 45 to 48.6 mol%.

When the amount of the sub-components containing SiO ₂ and CaO is 0.01% by weight or less, the grain boundary high resistance phase of SiO ₂ and CaO affects the overall resistance, so that the effect of increasing the resistance is small. Become. When the amount of the subcomponents including SiO ₂ and CaO exceeds 0.5% by weight, the thickness of the grain boundary phase increases and the magnetic interaction of ferrite grains is weakened, resulting in excellent magnetic properties (high saturation magnetic flux density, low core loss, high The magnetic permeability) cannot be obtained, and the component forming the grain boundary phase is mainly a low melting point substance, so that it affects the formation process and structure of ferrite. Therefore, the subcomponents containing SiO ₂ and CaO are set within the above range.

If Fe ²⁺ exceeds 1 mol%, the movement of electrons is facilitated and the resistance of the ferrite itself is lowered. ^Therefore , Fe ^{2+ is set} to 1 mol% or less.

Therefore, with the above structure, Fe ₂ O ₃ > 5
It has a high magnetic permeability (saturation magnetic flux density) and a low loss (core loss) close to that of a 0 mol% composition MnZn ferrite, and has a resistance comparable to that of a NiZn ferrite and a MgZn ferrite having a Fe ₂ O ₃ <50 mol% composition. To have.

According to the method for producing a manganese-zinc-based ferrite core according to claim 2, Fe ²⁺ is 1 mol% or less (excluding 0 mol%) by selecting firing conditions for the material having the above composition ratio.
Therefore, as in the case of claim 1, Fe ₂ O ₃
It has a high magnetic permeability (saturation magnetic flux density) and a low loss (core loss) close to that of a MnZn ferrite having a composition of> 50 mol%, and has a resistance comparable to that of a NiZn ferrite and a MgZn ferrite having a composition of Fe ₂ O ₃ <50 mol%. To have.

According to the method for producing a manganese-zinc-based ferrite core according to claim 3, by firing at an oxygen partial pressure of 1 to 100% at the maximum holding temperature, Fe ²⁺ is suppressed and high resistance is obtained. It will not be lost. That is, Fe ²⁺
The oxygen partial pressure for satisfying 1 mol% or less depends on the maximum holding temperature, and the maximum holding temperature required for firing ferrite is usually 1000 to 1400 ° C. Under this temperature condition, Fe ²⁺ 1 mol% or less In order to satisfy the above condition, it is necessary to carry out the oxygen partial pressure at 1% or more. If the oxygen partial pressure does not reach 1%, the production of Fe ²⁺ will remarkably increase and the resistance of the ferrite itself will decrease. Therefore, the oxygen partial pressure is set to 1% or more.

[0022]

EXAMPLES Examples of the present invention will be described in detail below.

<Example 1>

Manganese zinc (MnZn) of this Example 1
The ferrite core is composed of 48.6 mol% iron oxide (Fe ₂
O ₃ ), the sum of iron oxide (Fe ₂ O ₃ ) is 50 mol% ±
For example, 1.4 mol% of manganese (III) oxide (Mn ₂ O ₃ ), 41 mol% of manganese (II) oxide (MnO) and the balance of 9 mol% of zinc oxide ( ZnO) and a material having a main component of 0.03 wt% silicon dioxide (SiO ₂ ) and 0.1 wt% of calcium oxide (CaO).
Valuate iron ion (Fe ²⁺ ) is 1 mol% or less (excluding 0 mol%).

One manufacturing method of the first embodiment will be described.

First, each of the powder raw materials was weighed and sampled in the composition ratio and mechanically mixed, and then the mixed powder was calcined at 700 to 1100 ° C. for a predetermined time, and the calcined powder was pulverized. After that, it is granulated into particles of an appropriate size. The MnZn-based ferrite core of Example 1 is obtained by press-molding the powder thus granulated into a desired shape and then firing the molded body in a batch furnace.

As shown in FIG. 4, the firing conditions are as follows: after the temperature is raised in the atmosphere, the oxygen partial pressure at the maximum holding temperature (for example, a temperature of 1000 to 1300 ° C.) in the atmosphere is constant at 1 to 100% ( For example, 10% for a long time (for example, 2
After producing the final target product, the product is cooled to room temperature in the atmosphere and an inert gas such as nitrogen without changing the structure and valence of the product at the maximum holding temperature. In order to prevent oxidation of Fe ²⁺ , Mn ^2+, etc. generated in this cooling process, oxygen partial pressure (equilibrium oxygen partial pressure) PO _{2 at} each temperature T
Log (PO ₂ [%]) = α / T [° K] + β
(Α and β are constants). As a result, Fe ²⁺ is suppressed and Fe
²⁺ can be 1 mol% or less, and high resistance is not lost. By the long-term treatment with a constant oxygen partial pressure, the change in valence of the element or the like can be terminated and the desired product (spinel structure) can be obtained.

The effects of Example 1 thus obtained will be described with reference to Table 1. Table 1 shows Example 1 and Fe ₂ O ₃
It shows a comparison of characteristics with a NiZn-based ferrite core having a composition of <50 mol% (conventional example).

[0029]

[Table 1]

As is clear from Table 1, Example 1 can improve the saturation magnetic flux density by about 20% as compared with the conventional example, so that an inexpensive ferrite core can be provided.

<Example 2>

The MnZn-based ferrite core of Example 2 has a molar ratio such that the sum of 47.0 mol% of Fe ₂ O ₃ and Fe ₂ O ₃ is 50 mol% ± 0.5 mol%, for example, 3.0. Mol% Mn ₂ O ₃ , 34 mol% MnO and balance 16
Main component consisting of moles of ZnO and 0.06% by weight of Si
It is made of a material having O ₂ and an auxiliary component containing 0.08% by weight of CaO, and Fe ²⁺ is 1 mol% or less (excluding 0 mol%). The second embodiment is manufactured in the same manner as the first embodiment.

The effect of the second embodiment will be described with reference to Table 2 and FIG. Table 2 shows Example 2 when applied to a deflection yoke core, a MgZn-based ferrite core of Fe ₂ O ₃ <50 mol% composition (conventional example) and a MnZn-based ferrite core of Fe ₂ O ₃ > 50 mol% composition ( It shows a comparison of characteristics with the conventional example). FIG. 5 is a relationship diagram between core loss and temperature rise in a CRT display.

[0034]

[Table 2]

As is clear from Table 2, according to the second embodiment, the core loss can be greatly improved as compared with the conventional example. Therefore, as shown in FIG. 5, the CRT display has a higher frequency and a larger screen. The heat generated from the core can be reduced by about 5 ° C. as compared with the conventional material.

According to the embodiments described above in detail, by appropriate selection of the selection and firing conditions and firing at an oxygen partial pressure of the mixed materials ratios, yet Fe ₂ O ₃ <50 mol% Fe ₂
By setting the sum of O ₃ and Mn ₂ O ₃ to about 50 mol%, the valence of Mn is controlled, and a complete spinel structure is adopted, which is advantageous in terms of magnetic properties. Also, by selecting the firing conditions, the production of Fe ²⁺ is reduced during the firing process, and trivalent manganese ion (Mn ³⁺ ) of Mn component that supplements the shortage of Fe ₂ O ₃ is produced instead of Fe ^2+. As a result, the production of Fe ²⁺ that causes a decrease in resistance is suppressed. Further, by introducing a grain boundary high resistance phase of SiO ₂ and CaO, the resistance can be increased, and at this time, the ferrite component is Fe ₂
Since it is more stable than MnZn-based ferrite having a composition of O ₃ > 50 mol%, it is difficult to cause a grain boundary-intra-grain interaction, and the amount of grain boundary phase can be increased. As a result, the magnetic properties were conventionally poor and the resistance was low.
In the composition of Fe ₂ O ₃ of 48.6 mol% to Fe
High resistance can be realized by composition design, selection of firing conditions and active introduction of grain boundary high resistance phase so that generation of ²⁺ is 1 mol% or less, and oxygen partial pressure control to prevent oxidation in the cooling process. Fe, which was conventionally considered to be inferior,
_Since core loss reduction of MnZn-based ferrite having a composition of ₂ O ₃ <50 mol% was realized, Fe ₂ O ₃ <5
0 has a NiZn-based ferrite and MgZn ferrite par resistor mole percent composition (1 × 10 ⁷ to ^{6 × 10 7 Ω), Fe} 2 O 3> 50 saturation magnetic flux density close to MnZn ferrite mole percent composition (320 To 410 mT) and core loss (5.8 to 12 kW / m ³ ) and a method for producing the same can be provided (see FIGS. 1, 2 and 3).

The present invention is not limited to the above embodiment, but can be modified in various ways.

[0038]

According to the present invention described in detail above, the following effects can be obtained.

According to the invention of claim 1, Fe ₂ O ₃
Despite being <50 mol%, the sum of Fe ₂ O ₃ and Mn ₂ O ₃ is set to about 50 mol%, a grain boundary high resistance phase of SiO ₂ and CaO is introduced, and Fe ²⁺ is 1 mol% or less (0 (Except for mol%), it is possible to provide a manganese-zinc ferrite core having high magnetic permeability, low loss and high resistance.

According to the invention described in claim 2, since Fe ^{2+ is set} to 1 mol% or less (excluding 0 mol%) in the material having the above composition ratio by selecting the firing conditions, high permeability, low loss and It is possible to provide a method for producing a manganese-zinc based ferrite core having high resistance.

According to the third aspect of the invention, since the firing is carried out at an oxygen partial pressure of 1 to 100% at the maximum holding temperature, Fe ²⁺ is suppressed and high resistance is not lost.

[Brief description of drawings]

Fig. 1 Relationship between Fe ₂ O ₃ content and core loss

[Fig. 2] Relationship between Fe ₂ O ₃ content and saturation magnetic flux density

[Fig. 3] Relationship between Fe ₂ O ₃ and contact resistance

FIG. 4 is a diagram showing firing conditions.

FIG. 5 is a relationship diagram between core loss and temperature rise in a CRT display.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01F 41/02 D

Claims (3)

[Claims] 1. 45 to 48.6 mol% Fe ₂ O ₃ ,
Mn _{2 in a} molar ratio such that the sum of Fe ₂ O ₃ and Fe ₂ O ₃ is approximately 50 mol%.
O ₃ , a material containing 28 to 50 mol% of MnO and the balance of ZnO and 0.01 to 0.5% by weight of sub-components containing SiO ₂ and CaO.
A manganese-zinc-based ferrite core, characterized in that ²⁺ is 1 mol% or less (excluding 0 mol%). 2. 45 to 48.6 mol% Fe ₂ O ₃ ,
Mn _{2 in a} molar ratio such that the sum of Fe ₂ O ₃ and Fe ₂ O ₃ is approximately 50 mol%.
Manganese-zinc-based ferrite core made of a material containing O ₃ , 28 to 50 mol% of MnO and the balance ZnO, and 0.01 to 0.5% by weight of sub-components containing SiO ₂ and CaO. The method for producing a manganese-zinc-based ferrite core, wherein Fe ^{2+ is set} to 1 mol% or less (excluding 0 mol%) by selecting firing conditions. 3. The method for producing a manganese zinc-based ferrite core according to claim 2, wherein the firing condition is that the oxygen partial pressure at the maximum holding temperature is 1 to 100%.