JP2023097903A - ZIRCONIA SETTER AND METHOD FOR PRODUCING MnZn-BASED FERRITE - Google Patents

Abstract

To provide: a zirconia setter capable of producing a ferrite having high specific initial permeability and high Curie temperature; a MnZn-based ferrite produced using the setter; and a method for producing the same.SOLUTION: A zirconia setter has a CaO content of 0.28 mass% or less and a porosity of 45.0 volume% or less. A method for producing an MnZn-based ferrite includes producing the MnZn-based ferrite which is mainly composed of Fe2O3, ZnO, and MnO, using the zirconia setter. The MnZn-based ferrite is produced using the method, wherein the ZnO content on a setter ground surface in a sintered body obtained by sintering the MnZn-based ferrite raw material is 95.0% or more of the ZnO content inside the sintered body.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a zirconia setter, a MnZn-based ferrite, and a method for producing the same.

MnZn-based ferrites are used as magnetic core materials for noise countermeasure parts mounted in home electric appliances and electronic equipment. Further, MnZn-based ferrites have been studied to have high functionality such as achievement of high magnetic permeability and maintenance of excellent frequency stability of magnetic permeability according to the intended use.

In addition, in automotive applications, for which demand has been increasing in recent years, the temperature of the external environment is expected to rise, so in addition to the above characteristics, improvements in Curie temperature and heat resistance are required. Here, it is known that the Curie temperature of ferrite tends to depend on the compounding ratio of the ferrite composition.

In Patent Document 1, by controlling the amount of carbon in the basic components, subcomponents, and inevitable impurities in ferrite within a specified range, a high relative initial permeability in a specific temperature range (-20 ° C. to 150 ° C.) A Mn--Zn--Co based ferrite is disclosed which can have a

JP 2015-229626 A

However, with the technique described in Patent Document 1, the range of the Curie temperature and relative initial permeability of the obtained ferrite is limited, and development of a technique that can be applied to a wider range has been desired. In addition, many of the conventional techniques focus on the composition of ferrite itself, and very few of them focus on the composition of the setter used when sintering the ferrite raw material.

The present invention has been made in view of such a background, and provides a zirconia setter capable of producing ferrite having a high relative initial permeability and a high Curie temperature, an MnZn-based ferrite produced using the setter, and production thereof. The purpose is to provide a method.

The zirconia setter according to the present invention is characterized by having a CaO content of 0.28% by mass or less and a porosity of 45.0% by volume or less.

One embodiment of the zirconia setter does not contain CaO.

One embodiment of the zirconia setter has a porosity of 25.0% by volume or less.

In one embodiment of the zirconia setter, the content of Y ₂ O ₃ is 1.0% by mass or more and 10.0% by mass or less, the content of MgO is 1.0% by mass or less, and the content of CeO ₂ is 1 .0% by weight or less, and the content of _SiO2 is 10.0% by weight or less.

A method for producing MnZn-based ferrite according to the present invention is characterized by producing MnZn-based ferrite containing Fe ₂ O ₃ , ZnO and MnO as main components using the zirconia setter of the present invention described above.

In one embodiment of the above manufacturing method, the oxygen concentration in the temperature rising temperature range of 600° C. or higher and 1310° C. or lower when sintering the MnZn-based ferrite raw material is set to 5.0% by volume or less.

In one embodiment of the manufacturing method, the temperature of the MnZn-based ferrite raw material whose temperature is raised is maintained at a temperature of 1250° C. or higher and 1360° C. or lower and an oxygen concentration of 1.5% by volume or higher and 20% by volume or lower.

In one embodiment of the above manufacturing method, the oxygen concentration at a cooling temperature of 1000° C. or less is 300 ppm or less when cooling the MnZn-based ferrite raw material held after the temperature rise.

The MnZn-based ferrite according to the present invention is a MnZn-based ferrite manufactured using the method for manufacturing the MnZn-based ferrite of the present invention described above,
In the sintered body obtained by sintering the MnZn-based ferrite raw material, the ZnO content of the setter contact surface is 95.0% or more with respect to the ZnO content inside the sintered body. and

The MnZn-based ferrite according to the present invention contains 50.9 to 53.2 mol% of Fe ₂ O ₃ , 21.0 to 24.4 mol% of ZnO, and the balance of MnO in 100 mol% of the main component, When the total amount of the main components is 100 parts by mass, 0.000 to 0.009 parts by mass of SiO ₂ , 0.010 to 0.034 parts by mass of CaO, and 0.000 parts by mass of Bi ₂ O ₃ are used as subcomponents. ~ 0.060 parts by mass, containing 0.000 to 0.039 parts by mass of MoO ₃ ,
The ZnO content of at least part of the surface is characterized by being 95.0% or more of the ZnO content of the interior.

One embodiment of the MnZn-based ferrite has a relative initial permeability μ′ of 12000 or more at 23° C. and 10 kHz.

An embodiment of the MnZn-based ferrite has a Curie temperature of 110° C. or more and a relative initial magnetic permeability μ″ of the imaginary part at 23° C. and 200 kHz of 7500 or more.

The MnZn-based ferrite according to the present invention contains 50.6 to 53.7 mol% of Fe ₂ O ₃ , 18.0 to 20.0 mol% of ZnO, and the balance of MnO in 100 mol% of the main component, When the total amount of the main components is 100 parts by mass, 0.000 to 0.010 parts by mass of SiO ₂ , 0.015 to 0.030 parts by mass of CaO, and 0.001 part by mass of Bi ₂ O ₃ are used as subcomponents. ~0.030 parts by mass, 0.001 to 0.020 parts by mass of _MoO3 , 0.10 to 0.55 parts by mass _{of Co2O3} , and _0.10 to 2.50 parts by mass of TiO2,
The ZnO content of at least part of the surface is characterized by being 95.0% or more of the ZnO content of the interior.

An embodiment of the MnZn-based ferrite has a relative initial permeability μ′ of 8500 or more at 23° C. and 10 kHz.

An embodiment of the MnZn-based ferrite has a Curie temperature of 150° C. or more and a relative initial magnetic permeability μ″ of the imaginary part at 23° C. and 500 kHz of 5500 or more.

The MnZn-based ferrite according to the present invention contains 50.5 to 54.0 mol% of Fe ₂ O ₃ , 11.0 to 18.0 mol% of ZnO, and the balance of MnO in 100 mol% of the main component, When the total amount of the main components is 100 parts by mass, 0.000 to 0.010 parts by mass of SiO ₂ , 0.015 to 0.030 parts by mass of CaO, and 0.001 part by mass of Bi ₂ O ₃ are used as subcomponents. ~0.030 parts by mass, 0.001 to 0.020 parts by mass of _MoO3 , 0.10 to 0.55 parts by mass _{of Co2O3} , and _0.10 to 2.50 parts by mass of TiO2,
The ZnO content of at least part of the surface is characterized by being 95.0% or more of the ZnO content of the interior.

One embodiment of the MnZn-based ferrite has a relative initial permeability μ′ of 7000 or more at 23° C. and 10 kHz.

An embodiment of the MnZn-based ferrite has a Curie temperature of 170° C. or more and a relative initial magnetic permeability μ″ of the imaginary part at 23° C. and 900 kHz of 5000 or more.

The MnZn-based ferrite according to the present invention contains 51.3 to 54.5 mol% of Fe ₂ O ₃ , 9.0 to 14.3 mol% of ZnO, and the balance of MnO in 100 mol% of the main component, When the total amount of the main components is 100 parts by mass, 0.000 to 0.015 parts by mass of SiO ₂ , 0.020 to 0.060 parts by mass of CaO, and 0.030 to 0.030 parts by mass of ZrO ₂ are used as secondary components. .070 parts by weight, 0.010 to 2.500 parts by weight of TiO ₂ , 0.15 to 0.45 parts by weight of Co ₂ O ₃ ,
The ZnO content of at least part of the surface is characterized by being 95.0% or more of the ZnO content of the interior.

One embodiment of the MnZn-based ferrite has a relative initial magnetic permeability μ′ of 4500 or more at 23° C. and 10 kHz.

An embodiment of the MnZn-based ferrite has a Curie temperature of 200° C. or more and a relative initial magnetic permeability μ″ of the imaginary part at 23° C. and 1.5 MHz of 3000 or more.

According to the present invention, it is possible to provide a zirconia setter capable of producing ferrite having a high relative initial permeability and a high Curie temperature, an MnZn-based ferrite produced using the setter, and a production method thereof.

As described above, many of the conventional techniques mainly focus on the ferrite composition, and very few focus on the setter used to manufacture ferrite.
The present inventors have found that by setting the CaO component contained in the zirconia setter and the setter porosity within specific ranges, the ferrite produced using the zirconia setter has a high relative initial permeability and a high It was newly found to have a Curie temperature.
Here, when the relationship between the strength H of the magnetic field and the magnetic flux density B is expressed by B=μH, the constant μ of proportionality is called magnetic permeability. Also, the relative magnetic permeability is obtained by dividing the magnetic permeability μ by the vacuum magnetic permeability μ ₀ =4π×10 ⁻⁷ [H/m]. In particular, in the initial magnetization curve, the relative magnetic permeability when a minute magnetic field is applied near the origin is referred to as the relative initial magnetic permeability μ'. The Curie temperature is the temperature at which a ferromagnetic material changes to a paramagnetic material. The Curie temperature can be measured according to JIS standards.

By using the zirconia setter according to the present invention for sintering electronic materials, etc., it is possible to produce ferrite having a wider range of compositions than conventional ferrites capable of achieving the various characteristics described above. Furthermore, by setting the composition of the ferrite to a more appropriate range, it is possible to provide ferrite having both a higher relative magnetic permeability and a higher Curie temperature.

The zirconia setter, MnZn-based ferrite, and method for producing the same according to the present invention will be described below.
In addition, unless otherwise specified, "-" indicating a numerical range includes its lower limit and upper limit.

<Zirconia Setter>
The zirconia setter according to the present invention (hereinafter also referred to as the "main setter") has a CaO content of 0.28% by mass or less and a porosity of 45.0% by volume or less. By satisfying the above requirements, the reaction between the ferrite raw material and the setter component can be suppressed, and ferrite having a high relative magnetic permeability and a high Curie temperature can be produced. Of course, among the constituent components of this setter, the balance other than CaO (and other components described later) is ZrO ₂ .

More specifically, when the CaO content in the setter is 0.28% by mass or less, the ferrite manufactured using the setter has a high relative initial permeability μ′ at 23° C. and 10 kHz. The CaO content in the setter is preferably 0.14% by mass or less, more preferably 0% by mass (that is, the setter does not contain CaO). If the content of CaO in the setter is 0.14% by mass or less, the relative initial permeability μ′ at 23° C. and 10 kHz of the ferrite manufactured using the setter becomes higher. Furthermore, if CaO is not contained in the setter, the relative initial magnetic permeability μ′ at 23° C. 10 kHz and the relative initial magnetic permeability μ″ of the imaginary part at 23° C. 200 kHz of the ferrite produced using the setter are higher.

Further, when the porosity of the setter is 45.0% by volume or less, the ferrite manufactured using the setter has a high relative initial permeability μ′ at 23° C. and 10 kHz. Furthermore, from the viewpoint of obtaining a higher relative initial permeability, the porosity of the setter is preferably 30.0% by volume or less, more preferably 25.0% by volume or less, and 12.0% by volume or less. is more preferable. Even when the porosity of the setter is 0% by volume, ferrite having a high relative initial permeability μ' can be easily produced. The porosity of the setter can be measured according to JIS R 2205-74.

This setter is a zirconia setter and can be used, for example, for sintering electronic materials. In addition to ZrO ₂ and CaO described above, the constituents of the setter can include conventionally known components such as Y ₂ O ₃ , MgO, CeO ₂ and SiO ₂ . The content of these other components can be set as appropriate and is not particularly limited, but can be within the following ranges, for example. That is, the content of Y ₂ O ₃ in the setter is 1.0% by mass or more and 10.0% by mass or less, the content of MgO is 1.0% by mass or less, and the content of CeO ₂ is 1.0% by mass or less. , the content of SiO ₂ can be 10.0 mass % or less.
The setter does not have to contain these other ingredients, and when the amount of these other ingredients mixed in the setter is small or when these other ingredients are not included (that is, when the other ingredients are The closer the blending amount is to 0% by mass, the higher the relative initial permeability tends to be achieved. The composition of each component compounded by the setter can be measured by ICP analysis.

The setter can be appropriately manufactured using a conventionally known manufacturing method, and the manufacturing method is not particularly limited. For example, the setter raw material (powder) mixed with each component constituting the setter is formed into a desired shape by a hydraulic press or the like, dried, and fired to manufacture the setter. In addition, the drying conditions and baking conditions at that time can also be appropriately set, and are not particularly limited. For example, firing can be carried out in the atmosphere at a temperature of 1350 to 1600° C. for 1 to 5 hours.

<Method for producing MnZn ferrite>
The method for producing MnZn-based ferrite according to the present invention (hereinafter also referred to as the present production method) uses the zirconia setter according to the present invention to produce Fe ₂ O ₃ (iron oxide (III)) and ZnO (zinc oxide). A MnZn-based ferrite (MnZn-based ferrite core) containing MnO (manganese oxide) as a main component is produced. This production method can be preferably applied to ferrite having a Curie temperature of 110°C to 245°C. In this manufacturing method, the reaction between the ferrite and the setter component can be suppressed, and the formation of abnormal grains on the ferrite surface can be suppressed. As a result, the frequency characteristics of the relative initial permeability of the obtained ferrite are improved, and the relative initial permeability μ″ of the imaginary part in the frequency band of 200 kHz or higher can be increased. The manufacturing method will be described in detail below.

The manufacturing method can have a mixing step, a first drying and granulating step, a calcining step, a crushing step, a second drying and granulating step, a molding step, and a sintering step.
First, powders of raw materials for each component are weighed so that the ferrite composition after sintering has a desired composition.
Next, all raw material powders are mixed and pulverized to obtain a mixed powder (mixing step). Specifically, using a device such as an attritor, the aggregated raw material powders are crushed and mixed until the median diameter D50 of the mixed powder reaches a desired value (for example, 0.5 μm or more and 1.5 μm or less). The particle size distribution of the mixed powder can be measured with a particle size distribution analyzer.

Subsequently, an appropriate amount of a binder such as polyvinyl alcohol is added to the mixed powder obtained in the mixing step (for example, 0.5 to 1.0 parts by mass when the total weight of the mixed powder is 100 parts by mass), Granules are obtained by spraying using a spray dryer or the like (first drying and granulation step).

Next, the granules obtained by the first drying and granulation step are calcined, for example, in an air atmosphere at an appropriate temperature and time (for example, at a temperature of 750° C. for 1 hour) to obtain a calcined product (calcined process).

Subsequently, in accordance with the desired Curie temperature and relative initial permeability, desired amounts of other components (subcomponents) are added to the obtained calcined material. Examples of the other components include SiO ₂ (silicon dioxide), CaO (calcium oxide) (in the form of Ca(OH) ₂ when actually added), Bi ₂ O ₃ (bismuth oxide), MoO ₃ (trioxide molybdenum), ZrO ₂ (zirconium dioxide), TiO ₂ (titanium oxide), Co ₂ O ₃ (cobalt oxide) (in the form of Co ₃ O ₄ when actually added) can be used. After adding each additive, the calcined material is pulverized to obtain a pulverized powder (pulverizing step). Specifically, in the crushing step, the calcined material is crushed until the median diameter D50 of the particle size after crushing reaches a desired value (for example, 0.5 μm or more and 1.0 μm or less) to obtain a crushed powder. get

Next, to the crushed powder obtained in the crushing step, an appropriate amount (for example, 0.5 to 1.0 parts by mass when the total weight of the crushed powder is 100 parts by mass) binder such as polyvinyl alcohol is added and sprayed with a spray dryer or the like to obtain granules (second drying and granulation step). At this time, the median diameter D50 of the granules can be appropriately set, and can be, for example, 40 μm or more and 200 μm or less.

The granules obtained in the second drying and granulation step are then formed into a desired shape, for example a toroidal core with an outer diameter of 19 mm, an inner diameter of 13 mm and a height of 11 mm (forming step).

Next, the obtained core is loaded on the zirconia setter according to the present invention having the above-described structure, and sintered using a sintering furnace (sintering step).
Here, in this production method, as the sintering conditions for sintering the MnZn-based ferrite raw material, it is preferable that the oxygen concentration in the temperature rise temperature range of 600° C. or higher and 1310° C. or lower is 5.0% by volume or less. . By satisfying the conditions, the ratio of the ZnO component on the surface of the ferrite to the ZnO component inside the obtained ferrite (sintered body) is increased, that is, the difference in the content of the ZnO component inside and outside the sintered body is suppressed to be smaller. can be done. As a result, it is possible to easily suppress the occurrence of internal stress due to nonuniform composition in the ferrite, and to easily suppress the decrease in the relative initial permeability μ′ and the relative initial permeability μ″ of the imaginary part.

Further, in this manufacturing method, it is preferable to maintain the heated MnZn-based ferrite raw material at a temperature of 1250° C. or higher and 1360° C. or lower and an oxygen concentration of 1.5% by volume or higher and 20% by volume or lower. By satisfying the conditions, the crystal grains of the sintered body can be easily grown.

Furthermore, in the present manufacturing method, it is preferable that the oxygen concentration at a cooling temperature of 1000° C. or lower when cooling the MnZn-based ferrite raw material held after the temperature rise is 300 ppm or lower. By satisfying the conditions, the crystal grains of the sintered body can be easily grown.

From the above, it is particularly preferable to manufacture ferrite under the following sintering conditions in the present manufacturing method. That is, when sintering the MnZn-based ferrite raw material, the oxygen concentration in the temperature rising temperature range of 600° C. or higher and 1310° C. or lower is set to 5.0% by volume or less (heating step). Then, the MnZn-based ferrite raw material whose temperature has been raised is maintained at a temperature of 1250° C. or higher and 1360° C. or lower and an oxygen concentration of 1.5% by volume or higher and 20% by volume or lower (temperature holding step). Subsequently, the oxygen concentration in the sintering furnace is (continuously) decreased in accordance with the temperature in the sintering furnace, and the oxygen concentration at the cooling temperature of 1000° C. or less is 300 ppm or less (cooling step).
By using such a manufacturing method, the crystal grains of the sintered body can be easily grown. In addition, by controlling the temperature and oxygen concentration during sintering within a predetermined range, the method reduces the oxygen vacancies in the ferrite, suppresses the diffusion of Co ions in a high-temperature environment, and is long-lasting in a high-temperature environment. Even if it is exposed for a long time, it is possible to suppress deterioration in characteristics from the initial characteristics. By including TiO ₂ in the MnZn-based ferrite, the effect of suppressing diffusion of Co ions in a high-temperature environment can be further enhanced.
In addition, by loading the MnZn-based ferrite raw material (sintered material) on the main setter and performing sintering using the above manufacturing conditions, the reaction between the ferrite raw material and the components contained in the setter can be easily suppressed. Furthermore, it is possible to easily suppress the reduction of the ZnO component having a high saturated vapor pressure. As a result, it is possible to easily obtain ferrite having a high relative initial permeability μ′ as well as a high μ″ as described above.

As an example of a conventional method for producing MnZn-based ferrite, the temperature in the temperature holding step is set to a high temperature of 1380 to 1420° C. to grow the crystal grain size of the sintered body, and the ZnO component having a high saturated vapor pressure is produced in the sintered body. In order to suppress the decrease from the sintered body, a method is known in which the body to be fired is placed in a ferrite powder having the same composition as the sintered body and sintered. However, in the present invention, it is possible to obtain a MnZn-based ferrite having a high relative initial permeability by the simple method as described above without using such a complicated and costly manufacturing method.

<MnZn ferrite>
The MnZn ferrite according to the present invention (hereinafter also referred to as the present ferrite) can be produced by the method for producing the MnZn ferrite according to the present invention using the above-described zirconia setter according to the present invention.
This ferrite includes the following first to fifth MnZn-based ferrites. The Curie temperature of MnZn-based ferrite tends to be specified by the composition ratio of Fe ₂ O ₃ , MnO and ZnO, which are the main components. In addition, the composition of each component in which ferrite is mixed can be measured by fluorescent X-ray analysis. The compositions (main component compositions) of the second to fifth MnZn ferrites are set so that the Curie temperature is 110.degree. C. to 245.degree. As the Curie temperature of the MnZn-based ferrite increases, the magnetocrystalline anisotropy constant and the magnetostriction constant at room temperature (for example, 25° C.) increase, so the relative initial permeability decreases as the Curie temperature increases. Tend. However, the present ferrite obtained by using the present manufacturing method can have a high relative initial permeability even when the Curie temperature is kept high.
Since this ferrite can have a high Curie temperature and a high relative initial permeability, it can be used as the magnetic core of common mode choke coils and other coils according to various operating temperature environments. high performance can be achieved.

(First MnZn-based ferrite)
The first MnZn-based ferrite (hereinafter also referred to as the first ferrite) can be manufactured using the present manufacturing method described above, and the setter in the sintered body obtained by sintering the first ferrite raw material The ZnO content of the ground plane is 95.0% or more of the ZnO content inside the sintered body. Thus, if the ZnO ratio inside and outside the ferrite is 95.0% or more, it is possible to suppress the occurrence of internal stress due to non-uniform composition, and easily suppress the decrease in the relative initial permeability.

(Second MnZn-based ferrite)
The second MnZn-based ferrite (hereinafter also referred to as the second ferrite) contains 50.9 to 53.2 mol% of Fe ₂ O ₃ , 21.0 to 24.4 mol% of ZnO, and the balance of 100 mol% of the main component. It is contained in an amount that becomes MnO. Further, when the total amount of the main components is 100 parts by mass, the second ferrite contains 0.000 to 0.009 parts by mass of SiO ₂ , 0.010 to 0.034 parts by mass of CaO, and 0.010 to 0.034 parts by mass of Bi as subcomponents. It contains 0.000 to 0.060 parts by mass of ₂ O ₃ and 0.000 to 0.039 parts by mass of MoO ₃ . Furthermore, in the second ferrite, the ZnO content in at least part of the surface is 95.0% or more of the ZnO content in the interior.

A desired Curie temperature can be easily obtained by setting the content ratios of the main components Fe ₂ O ₃ , ZnO and MnO within the above ranges. More specifically, when the content of Fe ₂ O ₃ is equal to or higher than the above lower limit, it is possible to easily prevent the Curie temperature from falling below the desired temperature. Further, when the content of Fe ₂ O ₃ is equal to or less than the above upper limit, a high relative initial permeability can be easily maintained. Furthermore, if the content of ZnO is at least the above lower limit, a high relative initial permeability can be easily maintained. Further, when the content of ZnO is equal to or less than the above upper limit, it is possible to easily prevent the Curie temperature from falling below the desired temperature.

By containing Bi ₂ O ₃ and MoO ₃ in the amounts within the above ranges, the growth of crystal grains in the sintered body can be promoted, and as a result, a high relative initial permeability can be obtained at 10 kHz. Here, Bi ₂ O ₃ tends to make the grain size of ferrite non-uniform. Therefore, it is preferable to grow the grain size of ferrite while minimizing the amount of Bi ₂ O ₃ added. When the content of Bi ₂ O ₃ is equal to or higher than the above lower limit, sufficient crystal grain growth occurs, and a high relative initial permeability can be obtained at 10 kHz. Further, when the content of Bi ₂ O ₃ is equal to or less than the above upper limit, a sintered body having a uniform crystal grain size can be easily obtained, so that deterioration of frequency characteristics can be easily prevented. In addition, if the content of _MoO3 is equal to or higher than the above lower limit, a sintered body with a uniform crystal grain size can be easily obtained, so deterioration of the frequency characteristics can be easily prevented. can be prevented, and a high μ” can be obtained. Further, when the content of MoO ₃ is equal to or less than the above upper limit, grain growth is not suppressed, and a decrease in μ' value at 10 kHz can be easily prevented.

In addition, by containing SiO ₂ and CaO in amounts within the above range, the specific resistance of ferrite is improved, so the frequency characteristics of the relative initial permeability can be improved, and the μ″ value in the frequency range of 200 kHz or higher can be increased. More specifically, when the content of SiO ₂ is equal to or higher than the above lower limit, it is possible to easily prevent the μ″ value from decreasing at 200 kHz to 1.5 MHz. Further, if the content of SiO ₂ is equal to or less than the above upper limit, it is possible to easily prevent the µ' value from decreasing at 10 kHz. In addition, if the CaO content is at least the above lower limit, it is possible to easily prevent a decrease in the μ″ value at 200 kHz to 1.5 MHz. Further, if the CaO content is below the above upper limit , the μ′ value at 10 kHz can be easily prevented from declining.

Further, if the ZnO ratio inside and outside the ferrite is 95.0% or more, it is possible to suppress the occurrence of internal stress due to non-uniform composition, and easily suppress the decrease in the relative initial permeability.

The second ferrite preferably has a Curie temperature of 110° C. or higher. In addition, the Curie temperature of the second ferrite can be, for example, 245° C. or less as described above. Also, the second ferrite preferably has a relative initial magnetic permeability μ′ of 12000 or more at 23° C. and 10 kHz. Further, the second ferrite preferably has a relative initial magnetic permeability μ″ of the imaginary part at 23° C. and 200 kHz of 7500 or more.

(Third MnZn ferrite)
The third MnZn-based ferrite (hereinafter also referred to as the third ferrite) contains 50.6 to 53.7 mol% of Fe ₂ O ₃ , 18.0 to 20.0 mol% of ZnO, and the balance of 100 mol% of the main component. It is contained in an amount that becomes MnO. Further, when the total amount of the main components is 100 parts by mass, the third ferrite contains 0.000 to 0.010 parts by mass of SiO ₂ , 0.015 to 0.030 parts by mass of CaO, Bi _0.001 to 0.030 parts by weight of _2O3 , 0.001 to 0.020 parts by weight of _MoO3 , 0.10 to 0.55 parts by weight _{of Co2O3} , 0.10 _{to 2} parts by weight of TiO2 .50 parts by mass. Furthermore, in the third ferrite, the ZnO content of at least part of the surface is 95.0% or more of the ZnO content inside.

A desired Curie temperature can be easily obtained by setting the content ratios of the main components Fe ₂ O ₃ , ZnO and MnO within the above ranges. More specifically, when the content of Fe ₂ O ₃ is equal to or higher than the above lower limit, it is possible to easily prevent the Curie temperature from falling below the desired temperature. Further, when the content of Fe ₂ O ₃ is equal to or less than the above upper limit, a high relative initial permeability can be easily maintained. Furthermore, if the content of ZnO is at least the above lower limit, a high relative initial permeability can be easily maintained. Further, when the content of ZnO is equal to or less than the above upper limit, it is possible to easily prevent the Curie temperature from falling below the desired temperature.

By containing Bi ₂ O ₃ and MoO ₃ in the amounts within the above ranges, the growth of crystal grains in the sintered body can be promoted, and as a result, a high relative initial permeability can be obtained at 10 kHz. Here, Bi ₂ O ₃ tends to make the grain size of ferrite non-uniform. Therefore, it is preferable to grow the grain size of ferrite while minimizing the amount of Bi ₂ O ₃ added. When the content of Bi ₂ O ₃ is equal to or higher than the above lower limit, sufficient crystal grain growth occurs, and a high relative initial permeability can be obtained at 10 kHz. Further, when the content of Bi ₂ O ₃ is equal to or less than the above upper limit, a sintered body having a uniform crystal grain size can be easily obtained, so that deterioration of frequency characteristics can be easily prevented. In addition, if the content of _MoO3 is equal to or higher than the above lower limit, a sintered body with a uniform crystal grain size can be easily obtained, so deterioration of the frequency characteristics can be easily prevented. can be prevented, and a high μ” can be obtained. Further, when the content of MoO ₃ is equal to or less than the above upper limit, grain growth is not suppressed, and a decrease in μ' value at 10 kHz can be easily prevented.

In addition, by containing SiO ₂ and CaO in amounts within the above range, the specific resistance of ferrite is improved, so the frequency characteristics of the relative initial permeability can be improved, and the μ″ value in the frequency range of 200 kHz or higher can be increased. More specifically, when the content of SiO ₂ is equal to or higher than the above lower limit, it is possible to easily prevent the μ″ value from decreasing at 200 kHz to 1.5 MHz. Further, if the content of SiO ₂ is equal to or less than the above upper limit, it is possible to easily prevent the µ' value from decreasing at 10 kHz. In addition, if the CaO content is at least the above lower limit, it is possible to easily prevent a decrease in the μ″ value at 200 kHz to 1.5 MHz. Further, if the CaO content is below the above upper limit , the μ′ value at 10 kHz can be easily prevented from declining.
Furthermore, by containing Co ₂ O ₃ in the above range, the magnetocrystalline anisotropy constant can be reduced over a wide temperature range, and the relative initial permeability can be increased over a wider temperature range.
In addition, by adding TiO ₂ and Co ₂ O ₃ in combination with Co 2 O 3 in the above range, the thermal diffusion of Co ions by Co ₂ O ₃ in a high temperature environment can be suppressed, and even when exposed to a high temperature environment for a long time, the initial characteristics can be improved. characteristic deterioration can be suppressed. In addition, TiO ₂ has the effect of suppressing electron exchange between divalent and trivalent metal ions by adding it to the MnZn-based ferrite, and has the effect of increasing the intragranular resistance. Here, for example, when the Curie temperature Tc of the third ferrite is 150° C. or higher (eg, 170° C. or higher), if the content of TiO ₂ is at least the above lower limit, the high temperature (eg, 150° C.) storage test , the rate of change of μ' can be kept lower. Further, in this case, if the content of TiO ₂ is equal to or less than the above upper limit, it is possible to easily prevent the μ′ value from decreasing at 10 kHz. Furthermore, when the Curie temperature of the third ferrite is 200° C. or more, if the content of TiO ₂ is at least the above lower limit, it is possible to easily prevent the μ″ value at 1.5 MHz from decreasing. In this case, if the content of TiO ₂ is equal to or less than the above upper limit, it is possible to easily prevent the µ' value from decreasing at 10 kHz.
Furthermore, if the ZnO ratio inside and outside the ferrite is 95.0% or more, it is possible to suppress the occurrence of internal stress due to non-uniform composition, and it is possible to easily suppress the decrease in the relative initial permeability.

The third ferrite preferably has a Curie temperature of 150° C. or higher. Note that the Curie temperature of the third ferrite can be set to, for example, 245° C. or less as described above. Also, the third ferrite preferably has a relative initial magnetic permeability μ′ of 8500 or more at 23° C. and 10 kHz. Further, the third ferrite preferably has a relative initial magnetic permeability μ″ of the imaginary part at 23° C. and 500 kHz of 5500 or more.

(Fourth MnZn ferrite)
The fourth MnZn-based ferrite (hereinafter also referred to as the fourth ferrite) contains 50.5 to 54.0 mol% of Fe ₂ O ₃ , 11.0 to 18.0 mol% of ZnO, and the balance of 100 mol% of the main component. It is contained in an amount that becomes MnO. Further, when the total amount of the main components is 100 parts by mass, the fourth ferrite contains 0.000 to 0.010 parts by mass of SiO ₂ , 0.015 to 0.030 parts by mass of CaO, and 0.015 to 0.030 parts by mass of Bi as secondary components. _0.001 to 0.030 parts by weight of _2O3 , 0.001 to 0.020 parts by weight of _MoO3 , 0.10 to 0.55 parts by weight _{of Co2O3} , 0.10 _{to 2} parts by weight of TiO2 .50 parts by mass. Furthermore, in the fourth ferrite, the ZnO content of at least part of the surface is 95.0% or more of the ZnO content of the inside.

A desired Curie temperature can be easily obtained by setting the content ratios of the main components Fe ₂ O ₃ , ZnO and MnO within the above ranges. More specifically, when the content of Fe ₂ O ₃ is equal to or higher than the above lower limit, it is possible to easily prevent the Curie temperature from falling below the desired temperature. Further, when the content of Fe ₂ O ₃ is equal to or less than the above upper limit, a high relative initial permeability can be easily maintained. Furthermore, if the content of ZnO is at least the above lower limit, a high relative initial permeability can be easily maintained. Further, when the content of ZnO is equal to or less than the above upper limit, it is possible to easily prevent the Curie temperature from falling below the desired temperature.

By containing Bi ₂ O ₃ and MoO ₃ in the amounts within the above ranges, the growth of crystal grains in the sintered body can be promoted, and as a result, a high relative initial permeability can be obtained at 10 kHz. Here, Bi ₂ O ₃ tends to make the grain size of ferrite non-uniform. Therefore, it is preferable to grow the grain size of ferrite while minimizing the amount of Bi ₂ O ₃ added. When the content of Bi ₂ O ₃ is equal to or higher than the above lower limit, sufficient crystal grain growth occurs, and a high relative initial permeability can be obtained at 10 kHz. Further, when the content of Bi ₂ O ₃ is equal to or less than the above upper limit, a sintered body having a uniform crystal grain size can be easily obtained, so that deterioration of frequency characteristics can be easily prevented. In addition, if the content of _MoO3 is equal to or higher than the above lower limit, a sintered body with a uniform crystal grain size can be easily obtained, so deterioration of the frequency characteristics can be easily prevented. can be prevented, and a high μ” can be obtained. Further, when the content of MoO ₃ is equal to or less than the above upper limit, grain growth is not suppressed, and a decrease in μ' value at 10 kHz can be easily prevented.

In addition, by containing SiO ₂ and CaO in amounts within the above range, the specific resistance of ferrite is improved, so the frequency characteristics of the relative initial permeability can be improved, and the μ″ value in the frequency range of 200 kHz or higher can be increased. More specifically, when the content of SiO ₂ is equal to or higher than the above lower limit, it is possible to easily prevent the μ″ value from decreasing at 200 kHz to 1.5 MHz. Further, if the content of SiO ₂ is equal to or less than the above upper limit, it is possible to easily prevent the µ' value from decreasing at 10 kHz. In addition, if the CaO content is at least the above lower limit, it is possible to easily prevent a decrease in the μ″ value at 200 kHz to 1.5 MHz. Further, if the CaO content is below the above upper limit , the μ′ value at 10 kHz can be easily prevented from declining.
Furthermore, by containing Co ₂ O ₃ in the above range, the magnetocrystalline anisotropy constant can be reduced over a wide temperature range, and the relative initial permeability can be increased over a wider temperature range.
In addition, by adding TiO ₂ and Co ₂ O ₃ in combination with Co 2 O 3 in the above range, the thermal diffusion of Co ions by Co ₂ O ₃ in a high temperature environment can be suppressed, and even when exposed to a high temperature environment for a long time, the initial characteristics can be improved. characteristic deterioration can be suppressed. In addition, TiO ₂ has the effect of suppressing electron exchange between divalent and trivalent metal ions by adding it to the MnZn-based ferrite, and has the effect of increasing the intragranular resistance. Here, for example, when the Curie temperature Tc of the fourth ferrite is 150° C. or higher (eg, 170° C. or higher), if the content of TiO ₂ is at least the above lower limit, the high temperature (eg, 150° C.) storage test , the rate of change of μ' can be kept lower. Further, in this case, if the content of TiO ₂ is equal to or less than the above upper limit, it is possible to easily prevent the μ′ value from decreasing at 10 kHz. Furthermore, when the Curie temperature of the fourth ferrite is 200° C. or more, if the content of TiO ₂ is at least the above lower limit, it is possible to easily prevent the μ″ value at 1.5 MHz from decreasing. In this case, if the content of TiO ₂ is equal to or less than the above upper limit, it is possible to easily prevent the µ' value from decreasing at 10 kHz.
Furthermore, if the ZnO ratio inside and outside the ferrite is 95.0% or more, it is possible to suppress the occurrence of internal stress due to non-uniform composition, and it is possible to easily suppress the decrease in the relative initial permeability.

The fourth ferrite preferably has a Curie temperature of 170° C. or higher. Note that the Curie temperature of the fourth ferrite can be set to, for example, 245° C. or less as described above. Further, the fourth ferrite preferably has a relative initial magnetic permeability μ′ of 7000 or more at 23° C. and 10 kHz. Further, the fourth ferrite preferably has a relative initial magnetic permeability μ″ of the imaginary part at 23° C. and 900 kHz of 5000 or more.

(Fifth MnZn ferrite)
The fifth MnZn-based ferrite (hereinafter also referred to as the fifth ferrite) contains 51.3 to 54.5 mol% of Fe ₂ O ₃ , 9.0 to 14.3 mol% of ZnO, and the balance of 100 mol% of the main component. It is contained in an amount that becomes MnO. Further, when the total amount of the main components is 100 parts by mass, the fifth ferrite contains 0.000 to 0.015 parts by mass of SiO ₂ , 0.020 to 0.060 parts by mass of CaO, ZrO 0.030 to 0.070 parts by mass of ₂ , 0.010 to 2.500 parts by mass of TiO ₂ and 0.15 to 0.45 parts by mass of Co ₂ O ₃ . Furthermore, in the fifth ferrite, the ZnO content of at least part of the surface is 95.0% or more of the ZnO content of the inside.

A desired Curie temperature can be easily obtained by setting the content ratios of the main components Fe ₂ O ₃ , ZnO and MnO within the above ranges. More specifically, when the content of Fe ₂ O ₃ is equal to or higher than the above lower limit, it is possible to easily prevent the Curie temperature from falling below the desired temperature. Further, when the content of Fe ₂ O ₃ is equal to or less than the above upper limit, a high relative initial permeability can be easily maintained. Furthermore, if the content of ZnO is at least the above lower limit, a high relative initial permeability can be easily maintained. Further, when the content of ZnO is equal to or less than the above upper limit, it is possible to easily prevent the Curie temperature from falling below the desired temperature.

By containing SiO ₂ , CaO and ZrO ₂ in amounts within the above ranges, the specific resistance of ferrite is improved, so the frequency characteristics of the relative initial permeability are improved, and the μ″ value in the frequency range of 200 kHz or higher can be increased. More specifically, when the content of SiO ₂ is equal to or higher than the above lower limit, it is possible to easily prevent the μ″ value from decreasing at 200 kHz to 1.5 MHz. Further, if the content of SiO ₂ is equal to or less than the above upper limit, it is possible to easily prevent the µ' value from decreasing at 10 kHz. In addition, if the CaO content is at least the above lower limit, it is possible to easily prevent a decrease in the μ″ value at 200 kHz to 1.5 MHz. Further, if the CaO content is below the above upper limit , the μ′ value at 10 kHz can be easily prevented from decreasing.In addition, if the content of ZrO ₂ is equal to or higher than the above lower limit, the μ″ value at 1.5 MHz can be easily prevented from decreasing. can be done. Further, if the content of ZrO ₂ is equal to or less than the above upper limit, it is possible to easily prevent the µ' value from decreasing at 10 kHz.
Furthermore, by containing Co ₂ O ₃ in the above range, the magnetocrystalline anisotropy constant can be reduced over a wide temperature range, and the relative initial permeability can be increased over a wider temperature range.
In addition, by adding TiO ₂ and Co ₂ O ₃ in combination with Co 2 O 3 in the above range, the thermal diffusion of Co ions by Co ₂ O ₃ in a high temperature environment can be suppressed, and even when exposed to a high temperature environment for a long time, the initial characteristics can be improved. characteristic deterioration can be suppressed. In addition, TiO ₂ has the effect of suppressing electron exchange between divalent and trivalent metal ions by adding it to the MnZn-based ferrite, and has the effect of increasing the intragranular resistance. Here, for example, when the Curie temperature Tc of the fifth ferrite is 150° C. or higher (eg, 170° C. or higher), if the content of TiO ₂ is the above lower limit value or higher, the high temperature (eg, 150° C.) storage test , the rate of change of μ' can be kept lower. Further, in this case, if the content of TiO ₂ is equal to or less than the above upper limit, it is possible to easily prevent the μ′ value from decreasing at 10 kHz. Furthermore, when the Curie temperature of the fifth ferrite is 200° C. or higher, if the content of TiO ₂ is at least the above lower limit, it is possible to easily prevent the μ″ value at 1.5 MHz from decreasing. In this case, if the content of TiO ₂ is equal to or less than the above upper limit, it is possible to easily prevent the µ' value from decreasing at 10 kHz.
Furthermore, if the ZnO ratio inside and outside the ferrite is 95.0% or more, it is possible to suppress the occurrence of internal stress due to non-uniform composition, and it is possible to easily suppress the decrease in the relative initial permeability.

The fifth ferrite preferably has a Curie temperature of 200° C. or higher. Note that the Curie temperature of the fifth ferrite can be set to, for example, 245° C. or less as described above. Further, the fifth ferrite preferably has a relative initial magnetic permeability μ′ of 4500 or more at 23° C. and 10 kHz. Furthermore, the fifth ferrite preferably has a relative initial magnetic permeability μ″ of the imaginary part at 23° C. and 1.5 MHz of 3000 or more.

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples. In addition, these descriptions do not limit the present invention.

[Method for evaluating properties]
First, the samples used for evaluating the characteristics of the manufactured ferrite will be described. Ferrites produced in Examples and Comparative Examples described later were formed into toroidal ferrite cores having an outer diameter of 19 mm, an inner diameter of 13 mm, and a height of 11 mm. A copper wire having a wire diameter of 0.26 mm was wound 10 times around this ferrite core to prepare a sample, and the relative initial permeability μ′ and imaginary part relative initial permeability μ″ were measured using an impedance analyzer. In addition, the current value at the time of measurement was 0.2 mA.

[Example 1]
First, Fe _{2 O 3 and Mn were added so that the Fe 2 O 3} content after sintering was 52.20 mol %, the ZnO content was _22.50 mol %, and the MnO content was 25.30 mol %, resulting in a total of 100 mol %. Raw material powders of ₃ O ₄ and ZnO were weighed.
Next, these raw material powders were mixed and pulverized with an attritor until the median diameter D50 of the resulting mixture was 0.5 μm or more and 1.5 μm or less.
Subsequently, 0.5 part by mass of polyvinyl alcohol was added to the obtained mixed powder, and sprayed with a spray dryer to obtain granules.
Next, the granules were calcined at 750° C. for 1 hour in an air atmosphere to obtain a calcined material.
SiO ₂ was added to the calcined material so that the SiO ₂ content after sintering was 0.005 parts by mass when the total mass of the obtained calcined material was 100 parts by mass. Similarly, Ca(OH) ₂ was added so that the CaO content after sintering was 0.021 parts by mass, and the _Bi2O3 content after sintering was 0.014 parts by mass _{. Bi2O3 was} added. Furthermore, _MoO3 was added to the calcined material so that the _MoO3 content after sintering was 0.003 parts by mass.
Next, the mixture of the obtained calcined material and additives is pulverized with a pulverizer so that the median diameter D50 of the particle size after pulverization is 0.5 μm or more and 1.0 μm or less to obtain a pulverized powder. got
Subsequently, to this crushed powder, 1 part by weight of polyvinyl alcohol was added to 100 parts by weight of the total weight of the crushed powder, and the mixture was sprayed with a spray dryer to obtain granules. The median diameter D50 of the granules at this time was 110 µm.

Next, the sintered ferrite core was formed into a toroidal shape having an outer diameter of 19 mm, an inner diameter of 13 mm, and a height of 11 mm, and was mounted on a setter.
The composition of the setter component used at this time was 5.0 mass % Y ₂ O ₃ content, 0.28 mass % CaO content, 0.0 mass % MgO content, and 0.0 mass % CeO ₂ content. 0% by mass, _SiO2 content was 7.0% by mass, the balance was _ZrO2 , and the setter porosity was 25.0% by volume. The composition of the setter component was measured by ICP analysis, and the setter porosity was measured according to JIS R 2205-74.

The sintering conditions used were such that the oxygen concentration in the temperature rising temperature range (temperature rising portion) of 600° C. or higher and 1310° C. or lower was 5.0% by volume or less. Further, the ferrite raw material whose temperature was raised (holding portion) was held at a temperature of 1310° C., and the oxygen concentration was set to 2.5% by volume. Further, after that, the oxygen concentration was continuously decreased in accordance with the cooling temperature until the cooling temperature reached 1000° C., and the oxygen concentration in the cooling temperature range (cooling section) of 1000° C. or lower was set to 300 ppm or lower. That is, the oxygen concentration was set to 5.0% by volume or less in the heating process to 600° C. or higher, 2.5% by volume in the temperature holding process, and 300 ppm or less in the cooling process.

The ferrite obtained by the above manufacturing method had a relative initial magnetic permeability μ′ of 12,192 at 23° C. and 10 kHz, a relative initial magnetic permeability μ″ of the imaginary part at 200 kHz of 8349, and a Curie temperature of 126° C. The Curie temperature was measured according to JIS standards.

[Examples 2 to 16 and Comparative Examples 1 to 3]
MnZn-based ferrites of Examples 2 to 16 and Comparative Examples 1 to 3 were produced in the same manner as in Example 1, except that the setter component composition and setter porosity were changed as shown in Table 1, and their properties were measured. It was measured.
The composition of the setter component and the setter porosity produced in Examples 1 to 16 and Comparative Examples 1 to 3, the relative initial permeability μ′ at 10 kHz and the imaginary part at 200 kHz of the ferrite produced using these setters The magnetic permeability μ″ (23° C.) and the Curie temperature are shown in Table 1. The ZnO content of at least a part of the ferrite surface obtained in Examples 1 to 16 was 95.0% with respect to the ZnO content inside. It was 0% or more.

As shown in Table 1, this setter having a specific composition and porosity is used to sinter an MnZn-based ferrite raw material to obtain an MnZn-based ferrite having a high relative initial permeability and a high Curie temperature. I was able to

[Example 17]
A MnZn-based ferrite was produced in the same manner as in Example 1, except that the oxygen concentration in the sintering temperature range of 600° C. to 1310° C. was 0.01% by volume, and its characteristics were measured.
The ferrite obtained by the above manufacturing method had a relative initial magnetic permeability μ′ of 12,082 at 23° C. and 10 kHz, a relative initial magnetic permeability μ″ of the imaginary part at 200 kHz of 8345, and a Curie temperature of 126° C. rice field.

[Examples 18 and 19, Comparative Example 4]
MnZn of Examples 18 and 19 and Comparative Example 4 in the same manner as in Example 17 except that the oxygen concentration in the sintering temperature range of 600 ° C. or higher and 1310 ° C. or lower was changed as shown in Table 2. We fabricated system ferrites and measured their properties.
Oxygen concentration at 600 ° C to 1310 ° C in the temperature rising process in the sintering process of the MnZn-based ferrites produced in Examples 17 to 19 and Comparative Example 4, the ratio of surface ZnO to the ZnO component inside the ferrite (ZnO ratio), ferrite Table 2 shows the relative initial permeability μ′ at 10 kHz, the imaginary component μ″ (23° C.) of the relative initial permeability at 200 kHz, and the Curie temperature. The composition of ferrite was measured by fluorescent X-ray analysis. .

As shown in Table 2, by performing sintering under specific sintering conditions, a MnZn-based ferrite having a high relative initial permeability and a high Curie temperature could be obtained. Specifically, by increasing the ratio of the ZnO component on the surface of the ferrite to the ZnO component inside the obtained ferrite (sintered body), a high relative initial permeability and a high Curie temperature are obtained. Furthermore, by setting the oxygen concentration to 5.0% by volume or less in the temperature rise temperature range of 600° C. or higher and 1310° C. or lower, the decrease in the relative initial permeability can be suppressed.

[Example 20]
A MnZn-based ferrite of Example 20 was produced in the same manner as in Example 1, except that the following points were changed, and its characteristics were measured.
That is, when weighing each raw material powder, the Fe ₂ O ₃ content after sintering is 50.90 mol%, the ZnO content is 22.50 mol%, and the MnO content is 26.60 mol%, so that the total is 100 mol%. Raw material powders of Fe ₂ O ₃ , Mn ₃ O ₄ and ZnO were weighed as follows.
In addition, the setter component composition was such that the _Y2O3 content was 5.0% by mass, the CaO content was 0.05% by mass, _the MgO content was 0.0% by mass, and the _CeO2 content was 0.0% by mass. , the _SiO2 content was 7.0% by mass, and the balance was _ZrO2 .

The ferrite obtained by the above manufacturing method had a relative initial magnetic permeability μ' at 23°C and 10 kHz of 16,189, a μ″ at 200 kHz of 8583, and a Curie temperature of 110°C.

[Examples 21 to 35 and Comparative Examples 5 to 13]
MnZn ferrites of Examples 21 to 35 and Comparative Examples 5 to 13 were produced in the same manner as in Example 20, except that the ferrite component composition was changed as shown in Table 3, and their properties were measured.
Main component and subcomponent compositions of ferrites of Examples 20 to 35 and Comparative Examples 5 to 13, relative initial permeability μ′ (23° C.) of manufactured ferrites at 10 kHz, imaginary part component μ″ of relative initial permeability at 200 kHz (23 ° C.) and the Curie temperature are shown in Table 3. The ZnO content of at least a part of the ferrite surface obtained in Examples 20 to 35 is 95.0% or more with respect to the ZnO content inside. Met.

As shown in Table 3, it was found that the second MnZn-based ferrite according to the present invention has a high relative initial permeability and a high Curie temperature.

[Example 36]
A MnZn-based ferrite of Example 36 was produced in the same manner as in Example 1, except that the following points were changed, and its characteristics were measured.
That is, when weighing each raw material powder, the Fe ₂ O ₃ content after sintering is 50.60 mol%, the ZnO content is 18.50 mol%, and the MnO content is 30.90 mol%, so that the total is 100 mol%. Raw material powders of Fe ₂ O ₃ , Mn ₃ O ₄ and ZnO were weighed as follows.
Further, SiO ₂ was added to the calcined material so that the SiO ₂ content after sintering was 0.004 parts by mass when the total mass of the obtained calcined material was 100 parts by mass. Similarly, Ca(OH) ₂ was added so that the CaO content after sintering was 0.021 parts by mass, and the _Bi2O3 content after sintering was 0.014 parts by mass _{. Bi2O3 was} added. Furthermore, MoO ₃ was added to the calcined material so that the MoO ₃ content after sintering was 0.003 parts by mass, and Co was added so that the Co ₂ O ₃ after sintering was 0.29 parts by mass. ₃ O ₄ was added, and TiO ₂ was added to the calcined product so that the TiO ₂ content after sintering was 0.75 parts by mass.
Furthermore, the composition of the setter component used was such that Y ₂ O ₃ content was 5.0% by mass, CaO content was 0.05% by mass, MgO content was 0.0% by mass, and CeO ₂ content was 0.05% by mass. 0 wt%, _SiO2 content was 7.0 wt%, balance was _ZrO2 .

The ferrite obtained by the above manufacturing method had a relative initial magnetic permeability μ' of 8,642 at 23°C and 10 kHz, a relative initial magnetic permeability μ" of the imaginary part at 500 kHz of 5,635, and a Curie temperature of 150°C.
In addition, the rate of change in μ′ at 120° C. before and after the high temperature storage test at 150° C. for 1000 hours in this ferrite was −5.1%.

[Examples 37-53 and Comparative Examples 14-28]
MnZn ferrites of Examples 37 to 53 and Comparative Examples 14 to 28 were produced in the same manner as in Example 36, except that the compositions of the main components and subcomponents of the ferrite were changed as shown in Table 4. properties were measured.
Main components, secondary components, relative initial permeability μ′ (23° C.) at 10 kHz, imaginary part component μ″ (23° C.) of relative initial permeability at 500 kHz of ferrites of Examples 36 to 53 and Comparative Examples 14 to 28 , the rate at which the relative initial permeability μ' (120°C) after being left in a constant temperature bath (air atmosphere) at 150°C for 1000 hours changed relative to the relative initial permeability μ' (120°C) before being left, Curie The temperatures are shown in Table 4. The ZnO content in at least part of the ferrite surface obtained in Examples 36 to 53 was 95.0% or more of the ZnO content in the interior.

As shown in Table 4, it was found that the third MnZn-based ferrite according to the present invention has a high relative initial permeability and a high Curie temperature.

[Example 54]
A MnZn-based ferrite of Example 54 was produced in the same manner as in Example 1, except that the following points were changed, and its characteristics were measured.
That is, when weighing each raw material powder, the Fe ₂ O ₃ content after sintering is 50.50 mol%, the ZnO content is 16.00 mol%, and the MnO content is 33.50 mol%, so that the total is 100 mol%. Raw material powders of Fe ₂ O ₃ , Mn ₃ O ₄ and ZnO were weighed as follows.
Further, SiO ₂ was added to the calcined material so that the SiO ₂ content after sintering was 0.004 parts by mass when the total mass of the calcined material was 100 parts by mass. Similarly, Ca(OH) ₂ was added so that the CaO content after sintering was 0.021 parts by mass, and the _Bi2O3 content after sintering was 0.014 parts by mass _{. Bi2O3 was} added. Furthermore, _MoO3 is added so that the MoO3 content after sintering is _0.003 parts by mass, and _{Co3O4 is} added so that the _Co2O3 after sintering is 0.290 parts by _mass. was added, and TiO ₂ was added to the calcined product so that the TiO ₂ content after sintering was 1.000 parts by mass.
Furthermore, the composition of the setter component used was such that Y ₂ O ₃ content was 5.0% by mass, CaO content was 0.05% by mass, MgO content was 0.0% by mass, and CeO ₂ content was 0.05% by mass. 0 wt%, _SiO2 content was 7.0 wt%, balance was _ZrO2 .

The ferrite obtained by the above manufacturing method had a relative initial magnetic permeability μ' at 23°C and 10 kHz of 7,151, a relative initial magnetic permeability μ" of the imaginary part at 900 kHz of 5,327, and a Curie temperature of 170°C.
The change rate of μ' at 120° C. before and after the high temperature storage test at 150° C. for 1000 hours in this ferrite was −4.8%.

[Examples 55-71 and Comparative Examples 29-43]
MnZn-based ferrites of Examples 55 to 71 and Comparative Examples 29 to 43 were produced in the same manner as in Example 54, except that the compositions of the main and subcomponents of the ferrite were changed as shown in Table 5. properties were measured.
The main components and subcomponents of the ferrites of Examples 54 to 71 and Comparative Examples 29 to 43, the relative initial permeability μ′ (23° C.) at 10 kHz, the imaginary part component μ″ (23° C.) of the relative initial permeability at 900 kHz, Curie temperature are shown in Table 5. The ZnO content of at least a portion of the ferrite surface obtained in Examples 54 to 71 was 95.0% or more of the ZnO content inside.

As shown in Table 5, it was found that the fourth MnZn-based ferrite according to the present invention has a high relative initial permeability and a high Curie temperature.

[Example 72]
A MnZn-based ferrite of Example 72 was produced in the same manner as in Example 1, except that the following points were changed, and its characteristics were measured.
That is, when weighing each raw material powder, the Fe ₂ O ₃ content after sintering is 51.30 mol%, the ZnO content is 11.50 mol%, and the MnO content is 37.20 mol%, so that the total is 100 mol%. Raw material powders of Fe ₂ O ₃ , Mn ₃ O ₄ and ZnO were weighed as follows.
Further, SiO ₂ was added to the calcined material so that the SiO ₂ content after sintering was 0.007 parts by mass when the total mass of the calcined material was 100 parts by mass. Similarly, Ca(OH) ₂ was added so that the CaO content after sintering was 0.040 parts by mass, and _ZrO2 was added so that the _ZrO2 content after sintering was 0.050 parts by mass. was added. Furthermore, _TiO2 is added so that the TiO2 content after sintering is 0.200 parts by mass, and _{Co3O4 is} added so that the _{Co2O3 after} sintering is 0.300 parts by _mass . was added to the calcined product.
Furthermore, the setter component used had a composition of 5.0 mass % Y ₂ O ₃ content, 0.05 mass % CaO content, 0.0 mass % MgO content, and 0.0 mass % CeO ₂ content. 0% by weight, _SiO2 content was 7.0% by weight, the balance was _ZrO2 .

The ferrite obtained by the above manufacturing method has a relative initial magnetic permeability μ′ of 4,856 at 23° C. and 10 kHz, a relative initial magnetic permeability μ″ of the imaginary part at 1.5 MHz of 3,612, and a Curie temperature of The temperature was 201° C. and the saturation magnetic flux density was 501 mT.

[Examples 73-89 and Comparative Examples 44-56]
MnZn-based ferrites of Examples 73 to 89 and Comparative Examples 44 to 56 were produced in the same manner as in Example 72, except that the compositions of the main and subcomponents of the ferrite were changed as shown in Table 6. properties were measured.
Main components, subcomponents, relative initial permeability μ′ (23° C.) at 10 kHz, imaginary part component μ″ (23° C.) of relative initial permeability at 1.5 MHz of ferrites of Examples 72 to 89 and Comparative Examples 44 to 56 ), the relative initial permeability (150 ° C.), the Curie temperature, and the saturation magnetic flux density (23 ° C.) at 10 kHz are shown in Table 6. Here, the saturation magnetic flux density is obtained using the MnZn-based ferrite obtained in each example as a ring core. , The saturation magnetic flux density measured when the primary winding is wound 50 times and the secondary winding is wound 20 times around the ring core, and a DC magnetic field of 1196 A / m is applied.In addition, obtained in Examples 72 to 89 The ZnO content of at least a portion of the ferrite surface was 95.0% or more with respect to the ZnO content inside.

As shown in Table 6, it was found that the fifth MnZn-based ferrite according to the present invention has a high relative initial permeability and a high Curie temperature.

Thus, by using the zirconia setter according to the present invention, it was possible to provide an MnZn ferrite having a high relative initial permeability and a high Curie temperature.

It should be noted that the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the scope of the invention.

Claims (21)

A zirconia setter characterized by having a CaO content of 0.28% by mass or less and a porosity of 45.0% by volume or less. 2. The zirconia setter of claim 1, which does not contain CaO. 3. The zirconia setter according to claim 1, having a porosity of 25.0% by volume or less. The content of Y ₂ O ₃ is 1.0% by mass or more and 10.0% by mass or less, the content of MgO is 1.0% by mass or less, the content of CeO ₂ is 1.0% by mass or less, and the content of SiO ₂ A zirconia setter according to any one of claims 1 to 3, wherein the amount is 10.0% by weight or less. Production of MnZn-based ferrite characterized by producing MnZn-based ferrite containing Fe ₂ O ₃ , ZnO and MnO as main components by using the zirconia setter according to any one of claims 1 to 4. Method. 6. The method for manufacturing an MnZn-based ferrite according to claim 5, wherein the oxygen concentration in the temperature rising temperature range of 600° C. or higher and 1310° C. or lower is set to 5.0% by volume or less when sintering the MnZn-based ferrite raw material. 7. The method for producing an MnZn-based ferrite according to claim 6, wherein the temperature of the MnZn-based ferrite raw material whose temperature has been raised is maintained at a temperature of 1250° C. or higher and 1360° C. or lower and an oxygen concentration of 1.5% by volume or higher and 20% by volume or lower. 8. The method for producing MnZn ferrite according to claim 7, wherein the oxygen concentration at a cooling temperature of 1000[deg.] C. or less is 300 ppm or less when cooling the MnZn ferrite raw material held after raising the temperature. An MnZn-based ferrite manufactured using the method for manufacturing an MnZn-based ferrite according to any one of claims 5 to 8,
In the sintered body obtained by sintering the MnZn-based ferrite raw material, the ZnO content of the setter contact surface is 95.0% or more with respect to the ZnO content inside the sintered body. MnZn-based ferrite. In 100 mol% of the main component, 50.9 to 53.2 mol% of Fe ₂ O ₃ , 21.0 to 24.4 mol% of ZnO, and the balance is MnO, and the total amount of the main component is 100 parts by mass. 0.000 to 0.009 parts by mass of SiO ₂ , 0.010 to 0.034 parts by mass of CaO, 0.000 to 0.060 parts by mass of Bi ₂ O ₃ , and MoO ₃ as subcomponents. Contains 0.000 to 0.039 parts by mass,
A MnZn-based ferrite, wherein the ZnO content of at least part of the surface is 95.0% or more of the ZnO content of the interior. 11. The MnZn-based ferrite according to claim 10, having a relative initial permeability μ' of 12000 or more at 23° C. and 10 kHz. 12. The MnZn ferrite according to claim 10, which has a Curie temperature of 110[deg.] C. or more and a relative initial magnetic permeability [mu]'' of the imaginary part at 23[deg.] C. and 200 kHz of 7500 or more. In 100 mol% of the main component, 50.6 to 53.7 mol% of Fe ₂ O ₃ , 18.0 to 20.0 mol% of ZnO, and the balance is MnO, and the total amount of the main component is 100 parts by mass. 0.000 to 0.010 parts by mass of SiO ₂ , 0.015 to 0.030 parts by mass of CaO, 0.001 to 0.030 parts by mass of Bi ₂ O ₃ , and MoO ₃ as subcomponents. 0.001 to 0.020 parts by mass, 0.10 to 0.55 parts by mass of Co ₂ O ₃ and 0.10 to 2.50 parts by mass of TiO ₂
A MnZn-based ferrite, wherein the ZnO content of at least part of the surface is 95.0% or more of the ZnO content of the interior. 14. The MnZn-based ferrite according to claim 13, having a relative initial permeability μ' at 23°C and 10 kHz of 8500 or more. 15. The MnZn-based ferrite according to claim 13 or 14, having a Curie temperature of 150° C. or more and a relative initial magnetic permeability μ″ of the imaginary part at 23° C. and 500 kHz of 5500 or more. In 100 mol% of the main component, 50.5 to 54.0 mol% of Fe ₂ O ₃ , 11.0 to 18.0 mol% of ZnO, and the balance is MnO, and the total amount of the main component is 100 parts by mass. 0.000 to 0.010 parts by mass of SiO ₂ , 0.015 to 0.030 parts by mass of CaO, 0.001 to 0.030 parts by mass of Bi ₂ O ₃ , and MoO ₃ as subcomponents. 0.001 to 0.020 parts by mass, 0.10 to 0.55 parts by mass of Co ₂ O ₃ and 0.10 to 2.50 parts by mass of TiO ₂
A MnZn-based ferrite, wherein the ZnO content of at least part of the surface is 95% or more of the ZnO content of the interior. 17. The MnZn-based ferrite according to claim 16, which has a relative initial permeability μ' of 7000 or more at 23° C. and 10 kHz. 18. The MnZn ferrite according to claim 16 or 17, which has a Curie temperature of 170° C. or more and a relative initial magnetic permeability μ″ of the imaginary part at 23° C. and 900 kHz of 5000 or more. In 100 mol% of the main component, 51.3 to 54.5 mol% of Fe ₂ O ₃ , 9.0 to 14.3 mol% of ZnO, and the balance is MnO, and the total amount of the main component is 100 parts by mass. 0.000 to 0.015 parts by mass of _SiO2 , 0.020 to 0.060 parts by mass of CaO, 0.030 to 0.070 parts by mass of _ZrO2 , and 0 parts by _{mass of TiO2} as secondary components. .010 to 2.500 parts by mass, containing 0.15 to 0.45 parts by mass of Co ₂ O ₃ ,
A MnZn-based ferrite, wherein the ZnO content of at least part of the surface is 95.0% or more of the ZnO content of the interior. 20. The MnZn-based ferrite according to claim 19, having a relative initial permeability μ' at 23°C and 10 kHz of 4500 or more. 21. The MnZn ferrite according to claim 19 or 20, which has a Curie temperature of 200[deg.] C. or more and a relative initial magnetic permeability [mu]'' of the imaginary part at 23[deg.] C. and 1.5 MHz of 3000 or more.