JPH07196322A - Production of oxide powder for ferrite and multiple oxide powder for ferrite - Google Patents

Abstract

PURPOSE:To obtain an oxide powder or multiple oxide powder for ferrite capable of producing high-performance and inexpensive ferrite magnets. CONSTITUTION:This oxide powder can be obtained by the following process: a solution of a complex of an amino acid and nitrates essentially containing Fe atom and also containing at least one kind selected from among Ba and Sr atom is heated to a temperature between the boiling point of the solvent and 400 deg.C followed by driving into powder. The multiple oxide powder can be obtained by the following process: a solution of a complex of an amino acid and nitrates essentially containing Fe atom and also containing at least two kinds of atoms selected from among Cu, Mn, Ni and Zn atoms is heated to a temperature between the boiling point of the solvent and 400 deg.C followed by drying into powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ferrite powder, and more specifically, oxide powder for ferrite,
And a method for producing a composite oxide powder for ferrite.

[0002]

2. Description of the Related Art Ferrite magnets, rare earth magnets and alnico magnets are examples of magnet materials used in electric devices such as various motors and speakers. Ferrite magnets are inferior in magnetic properties to other magnets, but are excellent in cost performance and are used in various fields. This ferrite magnet is obtained by firing oxide powder for ferrite or composite oxide powder for ferrite.

Hexagonal ferrite can be obtained by firing oxide powder for ferrite. Among these hexagonal ferrites, the M-type ferrite having a magnetoplumbite structure exhibits excellent magnetic properties. Yes, this high-performance sintered magnet is composed of single domain particles M
This is accomplished by creating a dense fired body of phases. In order to produce this high-density fired body, raising the secondary firing temperature is a simple method, but is not a useful method for realizing the high remanent magnetization Br and high coercive force Hc required as magnet characteristics. It cannot be. This is because the crystal grain size is increased by increasing the secondary firing temperature, and a domain wall that is a source of a demagnetization domain is formed in one crystal grain.
Fe ₂ O ₃ / BaO is used to make a high-density fired body.
A certain degree of improvement can be expected by adjusting the ratio, the Fe ₂ O ₃ / SrO ratio, so-called composition, but the predetermined magnetic characteristics cannot be satisfied due to the increase of the non-magnetic phase.

Therefore, the next measure is to reduce the particle size of the powder. As a method for making the powder particle size finer in the conventional powder metallurgy method, 1) a method for lengthening the pulverization time, 2) a method for lowering the primary firing temperature, and the like can be mentioned. With respect to 2), deterioration of magnetic properties due to mixing of impurities due to pulverization for a long time, and increase in running cost, phase inhomogeneity caused by primary firing at low temperature makes molding in a magnetic field impossible, which is out of the problem.

As described above, from the oxide powder for ferrite obtained by the conventional manufacturing method, a ferrite magnet having high characteristics and low cost could not be expected.

On the other hand, in order to obtain a composite oxide for ferrite, which is another raw material for ferrite magnets, it has been conventional to use C
It is obtained by mixing oxides of u, Fe, Mn, Ni and Zn and pre-firing. In addition, Cu, Fe,
An acid solution containing at least two kinds of Mn, Ni, and Zn is spray-roasted to obtain a powder.

In the case of the composite oxide powder for ferrite, which is produced by the method of mixing oxides of various raw materials and pre-calcining, the pre-calcining is usually carried out in the atmosphere at a temperature of about 800 to 1100 ° C. However, under these conditions, a powder consisting of a single spinel phase cannot be obtained, and only a powder having a non-uniform composition can be obtained. Therefore, when this powder is used for molding and firing, the diffusion of atoms is often insufficient, and only a non-uniform sintered body structure that is structurally disordered can be obtained, and excellent magnetic properties cannot be obtained. On the other hand, by increasing the pre-calcination temperature, it is possible to obtain a uniform composite oxide powder for ferrite in a single spinel phase. However, with this method, the powder particle size of the pre-calcined powder is significantly increased, and a long pulverization step is required thereafter. Therefore, not only is it disadvantageous in terms of cost,
Impurities in the pulverized powder increase due to contamination, and the magnetic properties of the sintered body deteriorate.

The Rusner method uses C, which is a component of ferrite.
In this method, a hydrochloric acid solution containing u, Fe, Mn, Ni and Zn is spray-roasted to obtain a composite oxide powder for ferrite. However, the vapor pressure of zinc chloride (hereinafter referred to as ZnCl) contained in the solution is high, the ratio of volatilizing without forming ZnO is high, and the composition deviation is remarkable. Moreover, since the hydrochloric acid solution is spray-roasted at a high temperature of 600 ° C. or higher, dedicated equipment is required, or the powder particle size of the powder to be produced becomes large and pulverization is required in the subsequent step, resulting in high cost. Furthermore, contamination of impurities from the furnace material of the equipment occurs.

As described above, even from the composite oxide powder for ferrite obtained by the conventional manufacturing method, a ferrite magnet having high characteristics and low cost could not be expected.

[0010]

In producing a high-performance ferrite magnet, the oxide powder for ferrite, which is one of the raw materials, has a uniform composition at the atomic level, and it is necessary to reduce impurities contained in the powder as much as possible. There is. More importantly, in order to obtain a magnetic material having a high residual magnetization Br and a high coercive force Hc, a fine powder having a sharp particle size distribution is required. Further, in order to obtain a magnet material having a high residual magnetization Br and a high coercive force Hc, it is necessary to prevent the generation of a magnetic domain wall, which is a generation source of a reverse magnetic domain, in one crystal grain as much as possible. In order to reduce the number of domain walls in a single crystal grain, it is the most effective means to obtain a predetermined density even at low temperature firing, and a small crystal grain size is the most effective means. At the stage, a powder having a powder particle size as small as possible and a sharp particle size distribution is required. Therefore, an object of the present invention is to provide an oxide powder for ferrite that enables the production of such a high-performance ferrite magnet.

Furthermore, in order to manufacture an inexpensive ferrite magnet with high performance, it is necessary to keep the cost of the oxide powder for ferrite as a raw material low. Therefore, it is an object of the present invention to provide an oxide powder for ferrite which makes it possible to manufacture an inexpensive ferrite magnet by reducing the powder manufacturing process and reducing the cost required for the process.

On the other hand, in producing high-performance ferrite,
Another raw material, a composite oxide powder for ferrite,
It is essential that the composition is uniform at the atomic level and that the particle size is such that the sinterability is good and that the particle size distribution is sharp. Further, it is necessary to reduce the impurities contained in the powder as much as possible. Therefore, another object of the present invention is to provide a composite oxide powder for ferrite that enables the production of such a high-performance ferrite magnet.

Furthermore, in order to manufacture an inexpensive ferrite magnet with high performance, it is necessary to keep the cost of the composite oxide powder for ferrite as a raw material low. Therefore, it is an object of the present invention to provide a composite oxide powder for ferrite that can manufacture an inexpensive ferrite magnet by reducing the number of powder manufacturing steps and reducing the cost of the steps.

As described above, an object of the present invention is to provide a method for producing a ferrite powder capable of producing a high-performance and inexpensive ferrite magnet.

[0015]

A method for producing an oxide powder for ferrite according to the present invention is a method for producing an oxide powder for ferrite having a magnetoplumbite structure, comprising:
e is essential, and a solution of a complex of a nitrate containing at least one of Ba and Sr and an amino acid is heated at a temperature not lower than the boiling point of the solvent to not higher than 400 ° C. and dried to obtain a powder.

Further, in the method for producing the composite oxide powder for ferrite of the present invention, Fe is essential and Cu, Mn, Ni,
In a method for producing a composite oxide powder for ferrite, which comprises, as a main component, a combination of at least two kinds of Zn oxides,
Obtaining a powder by heating a solution of a complex of a nitrate and an amino acid containing at least two kinds of Cu, Mn, Ni and Zn, which essentially contains Fe, at a temperature not lower than the boiling point of the solvent and not higher than 400 ° C. and dried. Is characterized by.

[0017]

The function of the ferrite oxide powder of the present invention is as follows:
It consists of dissolution of the raw material nitrate and amino acid in a solvent, mixing of the solution, and heating and drying at 400 ° C. or lower to evaporate the solvent. The residue produced by evaporation of the solvent self-ignites, after which a ferrite oxide powder is obtained.

According to the method for producing a ferrite oxide powder of the present invention, a powder having a powder particle size suitable for a fired ferrite body is directly obtained, and as a heating and drying method, spray heat drying for spraying and drying the solution in a high temperature atmosphere Using the method, a more uniform particle size powder is obtained. Also, since the components are mixed in a solvent, it is possible to mix the main components at the atomic level, and Fe and B are mixed.
A powder having a uniform composition of a and Sr is directly obtained. Furthermore, the residue is self-ignited after the solvent is heated and evaporated from the raw material, but the reaction at that time is a high temperature and a short time, and since it is a local reaction, it becomes a single phase with a magnetoplumbite structure and is fine and uniform. A powder of particle size is obtained. Since fine and uniform powder is obtained, it becomes sufficiently densified even at low temperature firing,
Uniform crystal grains can be obtained. In addition, since a powder with a particle size suitable for the ferrite fired body is directly obtained, the process of pulverizing the powder, which was required in the conventional manufacturing method, can be omitted. Is less. For the above reasons, the performance of the fired ferrite body using the oxide powder for ferrite obtained by the present invention is improved.

Further, since the step of mixing and pulverizing the powder can be omitted as compared with the manufacturing step of performing the primary firing through the conventional mixing process, the ferrite firing using the oxide powder for ferrite obtained according to the present invention can be omitted. The body becomes cheap.

According to the method for producing a ferrite oxide powder of the present invention, a powder having a powder particle size suitable for producing ferrite is directly obtained. In the method for producing an oxide for ferrite of the present invention, the required heating temperature is 400 ° C. or lower. Even if the heating temperature is 400 ° C. or higher, there is no advantage, and the equipment cost and running cost are high. Furthermore, if heated at an excessively high temperature, the powder particle size of the manufactured powder becomes larger than the powder particle size suitable for the production of ferrite, which is not preferable.

As described above, according to the method for producing a ferrite oxide powder of the present invention, it is possible to provide a ferrite oxide powder suitable for producing a ferrite fired body having higher performance and lower cost than the conventional production method.

On the other hand, the method for producing the composite oxide powder for ferrite of the present invention is carried out at 400 ° C. for dissolving the nitrates and amino acids as the raw materials in the solvent, mixing the solution, and evaporating the solvent.
It consists of heating and drying below. The residue generated by heating and drying the solution is self-ignited, and a complex oxide powder for ferrite is obtained after the reaction.

In the method for producing a composite oxide powder for ferrite of the present invention, a powder having a powder particle size suitable for a ferrite sintered body is directly obtained, and when the solution is spray-dried as a heat drying method, a more uniform particle size is obtained. A powder of is obtained. Moreover, since the components are mixed in a solvent, it is possible to mix the main components at the atomic level, and a powder having a uniform composition of Cu, Fe, Mn, Ni and Zn can be directly obtained. Furthermore, the residue self-ignites after the solvent is heated and evaporated from the raw material, but the reaction at that time is a high temperature and short time and is a local reaction, so a fine spinel single-phase powder with a uniform particle size is obtained. . Since spinel single-phase powder having a fine and uniform grain size is obtained, abnormal grain growth of ferrite crystal grains found in a sintered body, which has been easily generated in the past, is eliminated. In addition, since the powder having the powder particle size suitable for the ferrite sintered body is directly obtained, the step of pulverizing the powder, which is required in the conventional manufacturing method, can be omitted, and the amount of impurities mixed in from the manufacturing step can be reduced. Few. For the above reasons, the performance of the ferrite sintered body using the composite oxide powder for ferrite obtained by the present invention is improved.

In the method for producing the composite oxide powder for ferrite of the present invention, it is not necessary to heat at a high temperature as in the Rusner method, and therefore the production cost and the equipment cost are low. The step of mixing and pulverizing the powder can be omitted as compared with the conventional manufacturing steps such as the mixing pre-firing method and the Rusner method. For the above reasons, the ferrite sintered body using the composite oxide powder for ferrite obtained by the present invention becomes inexpensive.

According to the method for producing a composite oxide powder for ferrite of the present invention, a powder having a powder particle size suitable for producing ferrite is directly obtained. In the method for producing the composite oxide powder for ferrite of the present invention, the required heating temperature is 400 ° C. or lower. Even if the heating temperature is 400 ° C. or higher, there is no advantage, and the equipment cost and running cost are high.
Furthermore, if heated at an excessively high temperature, the powder particle size of the manufactured powder becomes larger than the powder particle size suitable for the production of ferrite, which is not preferable.

As described above, according to the method for producing a composite oxide powder for ferrite of the present invention, the ferrite for oxide suitable for producing a ferrite sintered body having higher performance and lower cost than the conventional powder mixing method or Rusner method is used. It is possible to provide a complex oxide powder.

[0027]

EXAMPLES Examples of the method for producing the oxide powder for ferrite will be described below.

Example 1 High-purity iron (III) nitrate and Ba nitrate were weighed so as to have an oxide equivalent composition of BaO.5.6Fe ₂ O ₃ and dissolved in pure water. 20 wt% of amino acid was added to this solution and mixed well. Next, this solution was heated at 100 to 400 ° C. to evaporate water. After evaporation of water, the residue of the solution self-ignited to form a ferrite oxide powder.

In order to add 0.2 wt% of SiO ₂ as a trace additive to the oxide powder for ferrite, mixing was carried out for 1 hour in a ball mill.

When the generated phase of this powder was confirmed by X-ray diffraction, it was confirmed that all of the M particles had a magnetoplumbite structure.
It was found to be type ferrite.

As a comparative example (conventional example) 1, iron oxide and barium oxide were weighed so as to have the same composition as described above, mixed with a ball mill using ethanol as a dispersion medium, and dried, and this powder was then exposed to the atmosphere. Primary calcination was performed at 1100 ° C. for 1.5 hours. Further, 0.2 wt% of SiO ₂ was added to this powder, and then finely pulverized with a ball mill for 30 hours. When the generated phase of this finely pulverized powder was examined by X-ray diffraction, it was found to be an M-type ferrite having a magnetoplumbite structure.

Next, the powder of Example 1 and the powder of Comparative Example 1 were pressed in a magnetic field, respectively, and then subjected to a secondary baking for 1.5 hours in an air atmosphere at a baking temperature of 1150 ° C.

In Table 1, the powder obtained by changing the heating temperature of the solution containing the metal nitrate and the amino acid in Example 1 and the powder of Comparative Example 1 were used to produce a sintered body density, Br. , _I Hc, (BH) _max .

[0034]

[Table 1]

The sample using the powder according to Example 1 has a higher density and B than that of Comparative Example 1 regardless of the heating temperature.
It can be seen that the material has a high r, _I Hc, (BH) _{max and} is an excellent material.

Example 2 High-purity iron (III) nitrate and Sr nitrate were weighed so as to have an oxide equivalent composition of SrO.5.6Fe ₂ O ₃ and dissolved in pure water. 20 wt% of amino acid was added to this solution and mixed well. Next, this solution was heated at 100 to 400 ° C. to evaporate water. After evaporation of water, the residue of the solution self-ignited to form a ferrite oxide powder.

In order to add 0.2 wt% of SiO ₂ as a trace additive to this oxide powder for ferrite, mixing was performed for 1 hour in a ball mill. When the generated phase of this powder was confirmed by X-ray diffraction, it was found to be an M-type ferrite having a magnetoplumbite structure.

As Comparative Example (Conventional Example) 2, iron oxide and strontium oxide were weighed so as to have the same composition as above,
After mixing with a ball mill using ethanol as a dispersion medium and drying, the powder was subjected to primary firing in the air at 1100 ° C. for 1.5 hours. Furthermore, 0.2 wt of SiO _{2 was} added to this powder.
%, And pulverized with a ball mill for 30 hours.
When the generated phase of this finely pulverized powder was examined by X-ray diffraction, it was found to be an M-type ferrite having a magnetoplumbite structure.

Next, after the powder of Example 2 and the powder of Comparative Example 2 were pressed in a magnetic field, respectively, the secondary firing temperature was 1150 ° C.
Then, the secondary firing was performed for 1.5 hours in the air atmosphere.

In Table 2, the powder obtained by changing the heating temperature of the solution containing the metal nitrate and the amino acid in Example 2 and the powder of Comparative Example 2 were used to prepare a sintered body. , _I Hc, (BH) _max .

[0041]

[Table 2]

The sample using the powder according to Example 2 has a higher density and B than that of Comparative Example 2 regardless of the heating temperature.
It can be seen that the material has a high r, _I Hc, (BH) _{max and} is an excellent material.

Example 3 High-purity iron (III) nitrate and Ba nitrate were weighed so as to have an oxide equivalent composition of BaO.5.6Fe ₂ O ₃ and dissolved in pure water. 20 wt% of amino acid was added to this solution and mixed well. The solution was then heated at 200 ° C to evaporate the water. After evaporation of water, the residue of the solution self-ignited to form a ferrite oxide powder.

In order to add 0.2 wt% of SiO ₂ as a trace additive to this oxide powder for ferrite, mixing was performed for 1 hour in a ball mill. When the generated phase of this powder was confirmed by X-ray diffraction, it was found that all were M-type ferrites having a magnetoplumbite structure.

In Comparative Example (Conventional Example) 3, iron oxide and barium oxide were weighed so as to have the same composition as the above composition, mixed with a ball mill using ethanol as a dispersion medium, and dried. Primary baking was performed at 1.5 ° C. for 1.5 hours. Further, SiO ₂ was added to this powder, and then finely pulverized with a ball mill for 30 hours. When the generated phase of this finely pulverized powder was examined by X-ray diffraction, it was found to be an M-type ferrite having a magnetoplumbite structure.

Next, the powder of Example 3 and the powder of Comparative Example 3 were respectively pressed in a magnetic field, and then the secondary firing temperature was 1100 ° C.
Secondary baking was performed at ˜1300 ° C. (holding time 1.5 hours) in an air atmosphere.

FIG. 1 shows the densities and (BH) _max of the powder of Example 3 and the powder of Comparative Example 3 when the secondary firing temperature was changed. The sample using the powder according to Example 3 has a sufficient density at a low temperature and has a magnetic property of (BH) _max.
It can be seen that this is a high and excellent material.

Example 4 High-purity iron (III) nitrate and Sr nitrate were weighed so as to have an oxide equivalent composition of SrO.5.6Fe ₂ O ₃ and dissolved in pure water. 20 wt% of amino acid was added to this solution and mixed well. The solution was then heated at 200 ° C to evaporate the water. After evaporation of water, the residue of the solution self-ignited to form a ferrite oxide powder.

In order to add 0.2 wt% of SiO ₂ which is a trace amount additive to the oxide powder for ferrite, mixing was carried out for 1 hour in a ball mill. When the generated phase of this powder was confirmed by X-ray diffraction, it was found that all were M-type ferrites having a magnetoplumbite structure.

As Comparative Example (Conventional Example) 4, iron oxide and strontium oxide were weighed so as to have the same composition as described above,
After mixing with a ball mill using ethanol as a dispersion medium and drying, the powder was subjected to primary firing in the air at 1100 ° C. for 1.5 hours. Further, SiO ₂ was added to this powder, and then finely pulverized with a ball mill for 30 hours. When the generated phase of this finely pulverized powder was examined by X-ray diffraction, it was found to be an M-type ferrite having a magnetoplumbite structure.

Next, the powder of Example 4 and the powder of Comparative Example 4 were each pressed in a magnetic field, and then the secondary firing temperature was 1100 ° C.
Secondary baking was performed at ˜1300 ° C. (holding time 1.5 hours) in an air atmosphere.

FIG. 2 shows the densities and (BH) _max of the powder of Example 4 and the powder of Comparative Example 4 when the secondary firing temperature was changed. In the sample using the powder according to Example 4, a sufficient density was obtained at low temperature, and the magnetic characteristics were also (BH) _max.
It can be seen that this is a high and excellent material.

In Examples 1 to 4, as a method of heating and drying the solution of the nitrate-amino acid complex, a spray heat drying method of spraying the solution in a heating atmosphere to dry it may be used.

Next, examples of the method for producing the composite oxide powder for ferrite will be described.

Example 5 High-purity iron (III) nitrate (hereinafter referred to as Fe (NO ₃ ) ₃ ) and manganese nitrate (hereinafter Mn)
(NO ₃ ) ₂ ), zinc nitrate (hereinafter Zn (NO ₃ ) 2
₂ ) as iron oxide (III) (hereinafter referred to as Fe ₂ O ₃ ), manganese oxide (hereinafter referred to as MnO), and zinc oxide (hereinafter referred to as ZnO), 53 mol%, 35
It was weighed to be mol% and 12 mol% and dissolved in pure water. Aminoacetic acid was added to this solution by adding Fe (NO ₃ ) ₃ ,
1 based on the total weight of Mn (NO ₃ ) ₂ and Zn (NO ₃ ) _2.
It was added to be 5 wt% and mixed well. Next, this solution was heated to 300 ° C. to evaporate water. After evaporation of the water, the residue of the solution self-ignited and became a complex oxide powder for ferrite.

The production phase of this powder was confirmed with an X-ray dectractometer. The result is shown in FIG. The peak shown in FIG. 3 is a peak diagram of the spinel phase of Mn-Zn ferrite. The peak is (220) for P1,
P2 is (311), P3 is (222), and P4 is (40
The peak of 0) is shown. As is clear from FIG. 3, the powder obtained in Example 5 is a powder composed of the spinel single phase of Mn—Zn ferrite. The powder particle size of this powder was measured by the BET method to be 0.4.
was μm. Furthermore, when the composition of this powder was confirmed by ICP analysis, it was found that Fe ₂ O ₃ -52.9 mol%, Mn
It was O-35.2 mol% and ZnO-11.9 mol%, and it was found that there was almost no composition deviation from the target composition.

Comparative example (conventional example) 5 was obtained as follows. Fe, Mn, and Zn in the Rusner method
₂ O _3, MnO, _53mol% as calculated on ZnO basis, 35
It was weighed to be mol% and 12 mol% and dissolved in a hydrochloric acid solution. Next, the acid solution was heated to about 800 ° C. while being sprayed in a Rusner furnace. This obtained the powder in the Rusner method.

[0058] The composition of the powder was confirmed by ICP _{analysis, Fe 2 O 3 -54.2mol%,} MnO-3
It was 6.4 mol% and ZnO-9.4 mol%, and it was found that compositional deviation occurred with respect to the target composition.

From the above, it was confirmed that by the manufacturing method of Example 5, a composite oxide powder for ferrite without spinel single phase and composition deviation was obtained.

Example 6 High-purity Fe (NO ₃ ) ₃ ,
Nickel nitrate (hereinafter referred to as Ni (NO ₃ ) ₂ ), Zn
(NO ₃ ) ₂ and copper nitrate (hereinafter referred to as Cu (NO ₃ ) ₂ )
Is Fe ₂ O ₃ , nickel oxide (hereinafter referred to as NiO),
As converted to ZnO and copper oxide (hereinafter referred to as CuO), 48
It was weighed to be mol%, 15 mol%, 6 mol%, 31 mol% and dissolved in pure water. Aminoacetic acid was added to this solution as Fe (NO ₃ ) ₃ , Ni (NO ₃ ) ₂ , Zn
15w based on the total weight of (NO ₃ ) ₂ and Cu (NO ₃ ) _2.
It was added to be t% and mixed well. The solution was then heated to 350 ° C. to evaporate the water. After evaporation of water,
The residue of the solution self-ignited and became a complex oxide powder for ferrite.

The production phase of this powder was confirmed by an X-ray dectractometer. The result is shown in FIG. The peak shown in FIG. 4 is a peak diagram of the spinel phase of Mn-Zn ferrite. The peaks are (220) for P5 and P, respectively.
6 is (311), P7 is (222), P8 is (400)
Shows the peak of. The powder particle size of this powder was measured by the BET method and found to be 0.35 μm. Furthermore, when the composition of the powder was confirmed by ICP analysis, it was found that Fe ₂ O
_{3 -48.1mol%, NiO-15.2mol%} , Z
It was nO-34.8 mol% and CuO-5.9 mol%, and it was confirmed that there was almost no composition deviation from the target composition.

Comparative example (conventional example) 6 was obtained as follows. Fe, Ni, Zn, Cu in the Rusner method
48 mol calculated as ₂ O ₃ , NiO, ZnO, CuO
%, 15 mol%, 6 mol%, 31 mol% were weighed and dissolved in a hydrochloric acid solution. Next, the acid solution was heated to about 800 ° C. while being sprayed in a Rusner furnace.
As a result, powder in the Rusner method was obtained.

When the composition of this powder was confirmed by ICP analysis, it was found that Fe ₂ O ₃ -50.4 mol%, NiO-1
6.5 mol%, ZnO-25.3 mol%, CuO-
It was 7.8 mol%, and it was confirmed that compositional deviation occurred with respect to the target composition.

[Embodiment 7] High-purity Fe (NO ₃ ) ₃ ,
Mn (NO ₃ ) ₂ , Zn (NO ₃ ) ₂ , Fe ₂ O ₃ ,
As calculated as MnO and ZnO, 53 mol%, 35 mol
% And 12 mol% were weighed and dissolved in pure water. Aminoacetic acid was mixed with Fe (NO ₃ ) ₃ and Mn in this solution.
40w with respect to the total weight of (NO ₃ ) ₂ and Zn (NO ₃ ) _2.
It was added to be t% and mixed well. Next, add this solution to 100 ℃, 200 ℃, 300 ℃, 400 ℃,
It heated at each temperature of 800 degreeC, and the water | moisture content was evaporated. After evaporation of water, the residue of the solution self-ignited to form a composite oxide powder for ferrite.

To this powder, 0.01 wt% of SiO ₂ and C
0.05 wt% of aO was added and mixed with a ball mill. Then, polyvinyl alcohol was added as a binder, and the binder was mixed. The obtained slurry was dried and granulated, and then shaped into a toroidal core of 25φ × 15φ × 5 ^t mm at a pressure of ² t / cm ² . The molded body thus obtained was heated to 850 to 580 in a nitrogen stream in which the oxygen partial pressure was controlled.
Sintered at a temperature of 1200 ° C.

The magnetic characteristics of the sintered body produced by changing these conditions were measured, and the temperature characteristics of the most excellent power loss characteristics are shown in FIG. The curves in the graph are solid line / heating temperature 100 ° C, broken line / heating temperature 200 ° C, dotted line / heating temperature 300 ° C, one-dot chain line / heating temperature 400 ° C, two-dot chain line /
It shows the relationship between core loss and temperature when the heating temperature is 800 ° C. As a result of the measurement, it was found that by setting the heating temperature to 400 ° C. or less, a ferrite sintered body having excellent magnetic properties can be manufactured.

In Examples 5 to 7, as a method of heating and drying the solution of the nitrate-amino acid complex, a spray heat drying method in which the solution is sprayed in a heating atmosphere to be dried may be used.

[0068]

As described in the examples, if the oxide powder for ferrite obtained by the manufacturing method of the present invention is used,
It is possible to obtain an M-type ferrite having a magnetoplumbite structure that is sufficiently densified at a low temperature.

This is because the oxide powder for ferrite obtained by the manufacturing method of the present invention has extremely fine and uniform particle size, so that it has better reactivity during firing than conventional powders, and at low temperatures. This is probably because the firing of As described above, according to the present invention, it is possible to provide a ferrite oxide powder capable of producing a high-performance, low-cost magnet material.

Further, in the method for producing a composite oxide powder for ferrite of the present invention, since the main component elements are mixed in a solvent, it is possible to mix the main components at the atomic level, and Cu,
A powder having a uniform composition of Fe, Mn, Ni and Zn can be directly obtained. Furthermore, the residue self-ignites after the solvent is heated and evaporated from the raw material, but the reaction at that time is a high temperature and short time, and it is a local reaction, so a powder of spinel single phase with fine and uniform particle size is obtained. To be For this reason, the abnormal grain growth of ferrite crystal grains found in a sintered body, which was easy to occur in the past, is eliminated. In addition, since the number of powder manufacturing steps is such that powder is not crushed, the amount of impurities is smaller than that in the conventional manufacturing method. As a result, the performance of the ferrite sintered body using the composite oxide powder for ferrite obtained by the present invention is improved.

Further, unlike the Rusner method, it is not necessary to heat at a high temperature, so that the manufacturing cost and the equipment cost can be reduced. The step of mixing and pulverizing the powder can be omitted as compared with the conventional manufacturing methods such as the mixing pre-firing method and the Rusner method.
By these, the ferrite sintered body using the composite oxide powder for ferrite obtained by the present invention becomes inexpensive.

As described above, according to the production method of the present invention, it is possible to provide a composite oxide powder for ferrite, which enables production of a high-performance and low-cost ferrite sintered body.

[Brief description of drawings]

FIG. 1 shows the density of the fired body and the (BH) _max when the secondary firing temperature is changed using the powder of Example 3 and the powder of Comparative Example 3.
It is the figure which showed.

FIG. 2 is a sintered body density and (BH) _max when the secondary firing temperature is changed using the powder of Example 4 and the powder of Comparative Example 4.
It is the figure which showed.

FIG. 3 is an X-ray peak diagram of the Mn—Zn ferrite powder produced in Example 5, measured by an X-ray dectractometer.

FIG. 4 is an X-ray peak diagram of the Ni—Cu—Zn ferrite powder manufactured according to Example 6 measured by an X-ray decractometer.

FIG. 5 shows a heating temperature of 100 according to the manufacturing method of Example 7.
It is the graph which showed the core loss of the Mn-Zn ferrite sintered compact manufactured using the complex oxide powder for ferrites obtained by (degreeC), 200 degreeC, 300 degreeC, 400 degreeC, and 800 degreeC, and the temperature.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuya Chiba 6-7-1, Koriyama, Taichiro-ku, Sendai-shi, Miyagi Tokin Co., Ltd.

Claims (4)

[Claims] 1. A method of producing an oxide powder for ferrite having a magnetoplumbite structure, wherein a solution of a nitrate-amino acid complex containing Fe as an essential component and containing at least one of Ba and Sr is not less than the boiling point of the solvent. To 400 ° C
A method for producing an oxide powder for ferrite, which comprises heating at the following temperature and drying to obtain a powder. 2. The method of heating and drying a solution of a complex of a nitrate containing at least one of Ba and Sr, which contains Fe as an essential component, and an amino acid is a spray heat drying method. Method for producing oxide powder for ferrite of. 3. Fe is essential and Cu, Mn, Ni, Z
In the method for producing a composite oxide powder for ferrite, the main component of which is a combination of at least two kinds of oxides of n.
e is essential, and a solution of a complex of a nitrate containing at least two of Cu, Mn, Ni, and Zn and an amino acid is heated at a temperature from the boiling point of the solvent to 400 ° C. and then dried to obtain a powder. A method for producing a composite oxide powder for ferrite, comprising: 4. Cu, Mn, N as essential Fe
The method for producing a composite oxide powder for ferrite according to claim 3, wherein the method of heating and drying the solution of the complex of a nitrate containing at least two of i and Zn and the amino acid is a spray heat drying method. .