JP2003124014A - Ferrite magnet and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new high-performance ferrite magnet having a higher (BH)max than the conventional ferrite magnet has. SOLUTION: This ferrite magnet has the main phase of a W-type ferrite containing A (Sr, Ba, or Ca), R (at least one kind of rare-earth element including Y), Co, and Zn. This ferrite magnet has a basic composition in which the total constitutional ratio of the metallic elements (A, R, Fe, Co, and Zn) is adjusted to 1-13 at.% against A, 0.05-10 at.% against R, 78-95 at.% against Fe, 0.5-15 at.% against Co, and 0.5-15 at.% against Zn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide range of magnet application products, for example, W-type ferrite which is preferably used for various rotating machines, magnet rolls, acoustic speakers, buzzers, magnets for attracting or generating magnetic fields, etc. The present invention relates to a ferrite magnet as a main phase and a manufacturing method thereof.

[0002]

2. Description of the Related Art WO98 / 38654 (PCT / JP98 / 00764)
The main phase is magnetoplumbite ferrite and S
At least one element selected from r, Ba, Ca, and Pb, which always contains Sr, is A, and at least one selected from rare earth elements (including Y) and Bi.
When R is the element of the species that always contains La and M is Co or Zn and Co, the total composition ratio of the metal elements of A, R, Fe and M is the total amount of metal elements. In contrast, A: 1 to 13 atom%, R: 0.05 to 10 atom%, F
A ferrite magnet having a composition of e: 80 to 90 atomic% and M: 0.1 to 5 atomic% is described. However, since this ferrite magnet has a magnetoplumbite type ferrite as the main phase, the maximum energy product (BH) max is 39.8 kJ / m ³ (5.
It was difficult to manufacture more than 0MGOe).

Japanese Patent Laid-Open No. 9-260124 discloses a composition formula: SrO.2 by adding carbon as a reducing agent and calcining and sintering in a non-oxidizing atmosphere.
The residual magnetic flux density Br is represented by (FeO) · nFe ₂ O _3.
0.48T, intrinsic coercive force iHc is 199kA / m (2.5kOe), and (BH) max
Of 42.2 kJ / m ³ (5.3 MGOe) was obtained. However, this W type ferrite magnet has F
In order to strictly control the amount of e ²⁺ produced, it is necessary to perform calcination and sintering in a non-oxidizing atmosphere and to dry the compact at 100 to 200 ° C. Reflecting such complicated manufacturing conditions, the W-type ferrite magnet is higher in cost and inferior in practicality as compared with the conventional magnetoplumbite-type ferrite magnet.

Japanese Patent Laid-Open No. 2000-235910 discloses that
A is a divalent alkaline earth metal ion or Pb, and B
Composition formula in which is a divalent metal ion: AO ・ 2 (BO) ・
W-type ferrite phase represented by 8Fe ₂ O ₃ and composition formula:
A composite ferrite magnet containing a magnetite phase represented by Fe ₃ O ₄ and having a W-type ferrite phase molar ratio of 60% or more is disclosed. A is at least one selected from the group of Ba, Sr, Ca and Pb, B is Fe, C
It is at least one selected from the group consisting of o, Ni, Mn, Mg, Cr, Cu and Zn. However, according to the study by the present inventors, this composite ferrite magnet has an iHc of 199 kA / m.
It became less than (2.5 kOe), and it was found that it could not be practically used as a ferrite magnet.

[0005]

Therefore, the problem to be solved by the present invention is to provide a new high-performance ferrite magnet having a high (BH) max exceeding that of a conventional ferrite magnet. Another object of the present invention is to provide a method capable of producing the high-performance ferrite magnet by calcination in air and / or sintering in air.

[0006]

A ferrite magnet according to the present invention, which has solved the above-mentioned problems, is provided with A (A is Sr, Ba or Ca).
Is. ), R (R is at least one of rare earth elements including Y), Co and Zn, and a ferrite magnet having a main phase of a W-type ferrite, each metal element (A, R, Fe). , Co and Zn), based on the total amount of metal elements, A: 1 to 13 atom%, R: 0.05 to 10 atom%, Fe: 78 to 95 atom%, Co: 0.5 to 15 atom%. , And Zn: having a basic composition of 0.5 to 15 atomic%.

The ferrite magnet of the present invention contains W containing A (A is Sr, Ba or Ca), R (R is at least one rare earth element including Y), Co and Zn. A ferrite magnet having a main phase of type ferrite, having the following general formula: A _x R _z Co _α Zn _β Fe _γ O
₂₇ (atomic ratio) (However, x, z, α, β and γ are the following conditions: 0.9 <(x + z) <1.2, 0.01 ≦ x <1.18,
0.01 ≦ z ≦ 0.4, 0.01 ≦ α ≦ 2, 0.01 ≦ β ≦ 2, and 16
It is a number that satisfies ≦ γ ≦ 18. ) Has a basic composition represented by

The ferrite magnet of the present invention has a higher (BH) max than the conventional ferrite magnet. R is at least one rare earth element selected from the group of La, Pr, Nd and Ce, and A is Ba and / or Sr.
In this case, (BH) max can be further increased, which is preferable. The basic composition of the ferrite magnet of the present invention is 0.9 <(x + z) <
1.2, 0.01 ≦ x <1.18, 0.01 ≦ z ≦ 0.4, 0.01 ≦ α ≦ 2
0.01 ≤ β ≤ 2, 0.5 ≤ (α + β) ≤ 2, (α / β)> 0.
When represented by a number that satisfies 5 and 16.5 ≦ γ <18
It is preferable because (BH) max can be further increased.

In the present invention, Fe is divalent or trivalent.
Fe composed of_γ= Fe²⁺ _δ+ Fe³⁺ _γ-δ
And divalent Co²⁺ _αAnd Zn²⁺ _βBetween α +
It is desirable that there is a relationship of β + δ ≦ 2.4. Well
Also, the ferrite magnet of the present invention is anisotropic ferrite sintered.
Can be used as a magnet, rotating machine, mag roll, etc.
Can be applied to.

The manufacturing method of the ferrite magnet of the present invention is
(A is Sr, Ba or Ca.), R (R is at least one kind of rare earth element including Y), Co and Zn having a main phase of W-type ferrite and each metal. Elements (A, R, Fe, Co and Z
The total composition ratio of n) is A: 1 to 13 atomic%, R: 0.05 to 10 atomic%, Fe: 78 to 95 atomic%, Co: 0.5 to 15 atomic%, and Zn with respect to the total amount of metal elements. A method for producing a ferrite magnet having a basic composition of 0.5 to 15 atomic%, wherein a calcined product having the basic composition is formed, and then pulverized,
It is characterized by being molded and sintered. When the method for producing ferrite according to the present invention is adopted, the W phase can be stably obtained even when calcination and sintering are performed in the air atmosphere, which is highly practical. Of course, when calcination and sintering are performed in a non-oxidizing atmosphere (nitrogen gas or argon gas atmosphere, etc.), W
The phase can be stably obtained.

[0011]

The reasons for limiting the composition of the ferrite magnet of the present invention will be described below. The ferrite magnet of the present invention is
A (A is Sr, Ba or Ca), R (R is Y
It is at least one kind of rare earth element including. ), A main phase of W-type ferrite containing Co and Zn, and the total composition ratio of each metal element (A, R, Fe, Co and Zn) is A: 1 with respect to the total amount of metal elements. .About.13 atomic%, R: 0.05 to 10 atomic%, Fe: 78 to 95 atomic%, Co: 0.5 to 15 atomic%, and Zn: 0.5 to 15 atomic%.
The content of A is 1 to 13 atom%, preferably 3 to 7 atom%. A content less than 1 atom% and 13 atom%
If it exceeds, it is difficult to make the W phase the main phase and a high (BH) max cannot be obtained. It is preferable to select La and / or Pr as R because the crystal magnetic anisotropy constant is increased and a particularly high (BH) max can be obtained. It is practical that 50 atomic% or more of R is La and / or Pr. R content is 0.
It is from 05 to 10 atom%, preferably from 0.3 to 3 atom%. If the R content is less than 0.05 at%, the effect of addition cannot be obtained, and if it exceeds 10 at%, it becomes difficult to make the W phase the main phase (B
H) max is greatly reduced. Co content is 0.5-15 atomic%
And is preferably 1.5 to 10 atom%. If the Co content is less than 0.5 at%, the effect of addition cannot be obtained, and if it exceeds 15 at%, the W phase becomes unstable. Zn content is 0.5-15
Atomic%, preferably 1.5 to 5 atomic%. Co
If the content of is less than 0.5 atomic%, the effect of addition cannot be obtained.
If it exceeds atomic%, the W phase becomes unstable.

The ferrite magnet of the present invention has the general formula: A _x
R _z Co _α Zn _β Fe _γ O ₂₇ (atomic ratio) and has a main phase of W-type ferrite, A is Sr, Ba or Ca, and R is at least one rare earth element containing Y. And x, z, α, β and γ are the following conditions: 0.9 <(x + z) <1.2, 0.01 ≦ x <1.18, 0.01 ≦ z
≦ 0.4, 0.01 ≦ α ≦ 2, 0.01 ≦ β ≦ 2, and 16 ≦ γ ≦ 18
It is a number that satisfies. The reason for limiting the composition in the case of having the basic composition represented by (1) will be described below. (X + z) is
If it is less than 0.9 or more than 1.2, the W phase becomes unstable and (BH) max is greatly reduced. When x is less than 0.01 and exceeds 1.1.8, the W phase becomes unstable and (BH) max is greatly reduced. The preferable range of x is 0.1 or more. When A = (Ba + Sr), the general formula is: (Sr + Ba) _x R _z Co _α Zn _β Fe
It is represented by _γ O ₂₇ (atomic ratio), and 0.01 ≦ (Sr + Ba) <
It is highly practical that 1.18 and 0.01 ≦ Sr and 0.01 ≦ Ba are satisfied. If z is less than 0.01, the effect of addition cannot be obtained, so the magnetic anisotropy constant cannot be increased, and if z exceeds 0.4, the magnetic properties are greatly deteriorated. The preferred range of z is 0.05 to 0.3, and the more preferred range is 0.1 to 0.2. If α is less than 0.01, the effect of addition cannot be obtained and the magnetic anisotropy constant cannot be increased. If α exceeds 2, the magnetic properties will be significantly reduced. The preferable range of α is 0.05 to 1. If β is less than 0.01, the effect of addition cannot be obtained, and if it exceeds 2, the magnetic properties are significantly deteriorated. The preferred range of β is 0.05 to 1. Especially 0.5 ≦
It is (BH) ma that (α + β) ≦ 2 and (α / β) ≧ 0.5
Preferred for increasing x. W when γ is less than 16 or over 18
The phase becomes unstable and (BH) max drops significantly. The preferred range of γ is 16.5-18. In order for the W phase to be a stable main phase, the content of divalent iron Fe ²⁺ _δ is preferably limited. Furthermore, considering the valence balance with divalent Co and Zn and the balance with R element, α +
It is desirable that β + δ ≦ 2.4. In the above general formula, the number of oxygen (O) atoms is 27. This is because the range in which the ferrite magnet of the present invention can exist (the range in which the W phase is the main phase) is the general formula: A ^{2 +} O ・ nM ²⁺ O ・ mF
e ³⁺ ₂ O ₃ (where n = 1.2 to 2.5, m = 7.4 to 8.8, A is at least one selected from the group of Sr, Ba and Ca, M is Co and Zn, or C
o, Zn and Fe. ) And n = 2
And the stoichiometric composition of M = 8 is shown. However, the actual number of oxygen atoms may be slightly deviated from the stoichiometric composition.

The ferrite magnet of the present invention preferably contains appropriate amounts of SiO ₂ and CaO in order to have a dense sintered body structure. SiO ₂ is an additive that suppresses the growth of crystal grains during sintering, and its content is preferably 0.05 to 0.5% by weight, more preferably 0.3 to 0.4% by weight. S
When the content of iO ₂ is less than 0.05% by weight, crystal grain growth excessively progresses during sintering, and (BH) max and iHc are greatly reduced. S
If the content of iO ₂ exceeds 0.5% by weight, the crystal grain growth is excessively suppressed, the improvement of the degree of orientation that progresses with the crystal grain growth becomes insufficient, and Br, (BH) max greatly decreases. Ca
O is an element that promotes crystal grain growth, and the content of CaO is preferably 0.3 to 1% by weight, and 0.4 to 0.7% by weight.
Is more preferable. When the content of CaO exceeds 1% by weight, crystal grain growth excessively progresses during sintering and iHc is greatly reduced. When the content of CaO is less than 0.3% by weight, the crystal grain growth is suppressed, the improvement of the degree of orientation that progresses with the crystal grain growth becomes insufficient, and the decrease of Br, (BH) max becomes remarkable.

Typical production conditions for the ferrite magnet of the present invention
The case will be described below. The basic composition is “mixed → calcined”
It is manufactured by the manufacturing process of → crushing → molding → sintering.
Is practical. Oxidation of R element as a feedstock of R element
Thing or a hydroxide etc. are mentioned. Specifically, La_TwoO
_ThreeOxides such as La (OH)_ThreeHydroxides such as La
_Two(CO_Three) _Three・ 8H_TwoCarbonate hydrates such as O, and La
(CH_ThreeCo_Two)_Three・ 1.5H_TwoO, La_Two(C_TwoO_Four)
_Three・ 10H_TwoUse at least one organic acid salt such as O
You can Nd, Pr or Ce oxide, hydroxide
Compounds, carbonates or organic acid salts can be used. It
And mixed rare earths (La, Nd, Pr and Ce)
At least two types are selected. ) Oxides, hydroxides, carbonates
Alternatively, an organic acid salt can be used, and these mixed rare earths can be used.
Inexpensive mixed rare earth compounds containing 50 atom% or more of elements
It is practical to use. As a feedstock for Co and Zn
Use these oxides, hydroxides or carbonates
You can Calcination is 1300 in air or nitrogen gas atmosphere
~ 1450 ℃ x 1-10 hours is preferable to heat
Yes. At less than 1300 ° C x 1 hour, W conversion is not sufficient.
If the temperature exceeds 10 hours, the calcined product will become hard and the pulverizability will decrease.
Heterogeneous phases such as spinel phase and hematite phase are formed. Public knowledge
The average particle size of 0.4 ~
Finely grind to 1 μm (measured by air permeation method). average
If the grain size is less than 0.4 μm, abnormal grain growth will occur during sintering.
IHc, (BH) max of the ferrite magnet finally obtained is
And the moldability deteriorates. If the average particle size exceeds 1 μm
Is a ferrite magnet with an increased proportion of coarse grains in the sintered body structure.
IHc, (BH) max of is greatly reduced. Then fine powder or fine
In a dry or wet magnetic field with a slurry in which powder is dispersed
Perform molding. In case of dry magnetic field molding, anisotropic
It is effective to use granulated raw materials. In normal magnetic field
The molding pressure during molding is 29.4 to 49.0 MPa (0.3 to 0.5 ton / cm²)
And the orientation magnetic field strength is 238.7〜1193.7kA / m (3〜15k
Oe). When the manufacturing method of the present invention is adopted,
Form drying temperature (Fe²⁺Change in magnetic characteristics due to
Can be neglected at room temperature to 200 ℃
It can be dried at temperature. Sintering is performed in the air or nitrogen gas atmosphere.
Performed under the conditions of heating at 1170 to 1250 ° C for 1 to 10 hours in the atmosphere
Is preferred. If it is less than 1170 ℃ x 1 hour, the density of the sintered body will be
Br, (BH) max is low because it does not rise to 1 minute, 1250 ℃ × 10
W-phase ferrite crystal grains may be coarsened over time
Has a large iHc, (BH) max and low due to the formation of a heterogeneous phase such as a spinel phase.
Down.

In order to improve the performance of the ferrite magnet of the present invention, it is preferable to use the following manufacturing method. The obtained calcined product is wet pulverized to have an average particle size of 0.4 to 1 μm (by air permeation method). The finely pulverized slurry obtained is concentrated (the concentration of ferrite particles in the slurry is 80% by weight or more) or dried and crushed. Next, the concentrated slurry or the crushed product is kneaded to break the aggregation of individual ferrite particles. A predetermined amount of water is added to the concentrated slurry or crushed fine powder from which the agglomeration has been released to adjust the slurry concentration, and the mixture is subjected to molding. Thereafter, it is molded in a wet magnetic field and sintered. By applying this manufacturing method, the obtained ferrite magnet has an improved degree of orientation of the formed body during forming in a magnetic field, and thus Br, (BH) max of the ferrite sintered magnet can be increased. More preferred is a production method in which a predetermined amount of a dispersant is added at the time of kneading in order to prevent aggregation of ferrite fine particles in the slurry used for molding. Surfactants, higher fatty acids, higher fatty acid soaps, higher fatty acid esters and the like are known as dispersants. By using a polycarboxylic acid-based dispersant, which is one of the anionic surfactants, the dispersibility of the ferrite fine particles is improved, and thus the aggregation of the ferrite fine particles can be suppressed. Although there are various polycarboxylic acid type dispersants, ammonium polycarboxylic acid is particularly effective for improving the dispersibility of ferrite fine particles. The amount of the dispersant added is preferably 0.2 to 2% by weight based on the total weight of the ferrite fine particles in the slurry. If the amount of the dispersant added is less than 0.2% by weight, the effect of addition will not be obtained, and if it exceeds 2%, Br and (BH) max will be reduced.

[0016]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 BaCO ₃ powder (containing Sr and Ca as impurities), α-Fe ₂ O ₃ powder (containing Mn, Cr, Si and Cl as impurities), lanthanum hydroxide powder, and oxidation. Using cobalt powder and zinc oxide powder, a mixed powder having a corresponding mixed composition was prepared so as to have the basic composition of Table 1 after calcination. Then mix the powder in the air at 1375
It was calcined at ℃ for 2 hours. The obtained calcined product was subjected to X-ray diffraction (Cu
Uses K _α1 ray. ) Result, as shown in FIG.
Only the line diffraction peak was detected, and it was found to be a single phase of W-phase ferrite. Next, the calcined product is roughly crushed with a crusher, and then sieved to 100 mesh under, and the average particle size is 10 μm.
(A laser diffraction particle size distribution analyzer manufactured by Sympatec, Inc .: measured by Heros Rhodes.) Saturation magnetization σs and coercive force of this coarse powder at room temperature by a sample vibrating magnetometer.
Hc was measured. The magnetizing magnetic field strength during measurement is 955.0 kA / m (20 kO
Then, the measured magnetization (σ) and applied magnetic field strength (H) were plotted as (σ−1 / H ² ), and σs was determined by extrapolation. The results are shown in Table 1. (Examples 2 to 4, Reference Example 1, Comparative Example 1) Calcination was performed in the same manner as in Example 1 except that each basic composition shown in Table 1 was used. Table 1 shows the result of X-ray diffraction of each of the obtained calcined products. Further, a coarse powder having an average particle size of 10 μm was prepared in the same manner as in Example 1,
σs and Hc were measured. The results are shown in Table 1.

[0018]

[Table 1] M: magnetoplumbite phase S: spinel phase

From Table 1, it is understood that when the basic compositions of Examples 1 to 3 are selected, W-phase ferrite single-phase calcined products are obtained. Further, it is understood that when the basic composition of Example 4 is selected, a calcined product containing W-phase ferrite as the main phase is obtained. Further, it was found that the calcined products of the respective examples have higher σs and Hc than the calcined products of Reference Example 1 and Comparative Example 1, and have high potential as a novel ferrite magnet material. In addition, Table 1
In the chemical formula of (or Table 2), divalent iron and trivalent iron may be collectively expressed as, for example, Fe ²⁺ _1.0 Fe ³⁺ _15.9 as Fe _16.9 .

Example 5 SrCO ₃ powder (containing Ba and Ca as impurities), α-Fe ₂ O ₃ powder (containing Mn, Cr, Si and Cl as impurities), lanthanum oxide powder, cobalt oxide. Using powder and zinc oxide powder,
A mixture having a corresponding mixed composition was prepared so as to have the basic composition shown in Table 2 after calcination. Then, the mixed powder was calcined in the air at 1375 ° C. for 2 hours. As a result of X-ray diffraction of the obtained calcined product,
Only the X-ray diffraction peak of the W phase was detected, and it was found to be a single phase of the W phase ferrite. Next, the obtained calcined product was coarsely crushed by a crusher and then sieved to 100 mesh under to obtain coarse powder having an average particle size of 10 μm (measured by Heros-Rhodes). The coercive force Hc of this coarse powder was measured at room temperature with a sample vibrating magnetometer. The magnetizing magnetic field strength during measurement is 955.0 kA / m
(20 kOe), the measured magnetization (σ) and applied magnetic field strength (H) were plotted (σ-1 / H ² ) and σs was determined by extrapolation. The results are shown in Table 2. (Examples 6 to 8, Reference Example 2, Comparative Example 2) Calcination was performed in the same manner as in Example 5 except that the basic compositions shown in Table 2 were used. Table 2 shows the result of X-ray diffraction of each of the obtained temporary products. A coarse powder having an average particle size of 10 μm was prepared in the same manner as in Example 5, and σ
The results of determining s and Hc are shown in Table 2.

[0021]

[Table 2] M: magnetoplumbite phase S: spinel phase

From Table 2, it is understood that when the basic composition of Example 5 is selected, a W-phase ferrite single-phase calcined product is obtained. Further, it is understood that when the basic compositions of Examples 6 to 8 are selected, calcined products containing W-phase ferrite as the main phase can be obtained. Further, it was found that the calcined products of the respective examples have higher σs and Hc than the calcined products of Reference Example 2 and Comparative Example 2, and have high potential as a novel ferrite magnet material.

Example 9 The calcined product produced in Example 2 was crushed by a crusher and then by a roller mill. Next, wet finely pulverize with an attritor to give an average particle size of 0.6μ.
A slurry in which fine powder of m (according to the air permeation method) was dispersed was obtained. At the beginning of this milling process, 1.0 wt% CaCO ₃ and 0.3 wt% SiO ₂ were added as sintering aids.
Molding pressure by the obtained slurry: 44.1MPa (0.45ton / cm
² ) The applied magnetic field strength was 795.8 kA / m (10 kOe), and compression molding was performed in the magnetic field. The compact is then dried at room temperature and then in air.
The ferrite magnet of the present invention was obtained by sintering at 1230 ° C for 2 hours. As a result of X-ray diffraction of this ferrite magnet, it was in a single W-phase. The obtained sintered ferrite magnet has a length of 10 mm,
It was processed into a cubic shape with a width of 10 mm and a thickness of 10 mm, and the magnetic characteristics were measured with a BH tracer at 20 ° C. (BH) max = 47.0kJ / m ³ (5.9MGOe), iHc = 199. Of this ferrite magnet.
0 kA / m (2.5 kOe) was obtained.

Example 10 The calcined product produced in Example 5 was crushed with a crusher and then with a roller mill. Next, wet finely pulverize with an attritor, average particle size 0.4μ
A slurry in which fine powder of m (according to the air permeation method) was dispersed was obtained. 0.8 wt% CaCO ₃ and 0.4 wt% SiO ₂ were added as sintering aids early in the milling process.
Molding pressure by the obtained slurry: 34.3MPa (0.35ton / cm
² ), The applied magnetic field strength was 955.0kA / m (12kOe) and compression molding was performed in the magnetic field. The compact is then dried at room temperature and then in air.
The ferrite magnet of the present invention was obtained by sintering at 1220 ° C for 2 hours. As a result of X-ray diffraction of this ferrite magnet, it was in a single W-phase. The obtained sintered ferrite magnet has a length of 10 mm,
It was processed into a cubic shape with a width of 10 mm and a thickness of 10 mm, and the magnetic characteristics were measured with a BH tracer at 20 ° C. (BH) max = 42.2kJ / m ³ (5.3MGOe), iHc = 230 of this ferrite magnet.
A kA / m (2.9 kOe) was obtained.

(Example 11) The two types of calcined coarse powders produced in Examples 2 and 5 were mixed in a weight ratio of (50:50). Using this mixed calcined coarse powder, an anisotropic ferrite sintered magnet was produced thereafter in the same manner as in Example 10. The basic composition of this ferrite magnet is Ba _0.41 Sr _0.47 La _0.15 Co _0.90 Zn _0.25 Fe
_{It was 16.9} O ₂₇ , and as a result of X-ray diffraction, it was a single W phase.
The magnetic characteristics measured at 20 ℃ are (BH) max ＝ 43.8J / m ³ (5.5MGO
e) and iHc = 206.9 kA / m (2.6 kOe).

Comparative Example 3 SrCO ₃ and α-Fe ₂ O ₃
1.5% by weight of C was added to the raw material powder prepared by mixing 1: 1 to 8.5 at a molar ratio, and calcined in a nitrogen gas atmosphere at 1350 ° C. for 1 hour. Next, the calcined product is put into an attritor, and CaO:
0.6% by weight, SiO ₂ : 0.3% by weight, and C: 0.2% by weight
A corresponding amount was added to an attritor to obtain a slurry in which fine powder having an average particle size of 0.6 μm (according to the air permeation method) was dispersed.
Molding pressure by this slurry: 34.3MPa (0.35t / c
m ² ), applied magnetic field strength: 955.0 kA / m (12 kOe), and compression molded in a magnetic field. Next, the molded body was dried at 200 ° C. for 2 hours and then sintered in a nitrogen gas atmosphere at 1190 ° C. for 2 hours. As a result of X-ray diffraction of the obtained ferrite sintered magnet, W phase single phase (SrO.
2FeO.8Fe ₂ O ₃ ). Magnetic properties measured at 20 ℃ are (BH) max = 42.2kJ / m ³ (5.3MGOe), iHc = 19
It was 9.0 kA / m (2.5 kOe).

In the above embodiment, the W phase single phase Ba system and Sr
Although it has been described that a system calcined product is obtained, the W-phase single-phase (Ba + Sr) system calcined product and (Ba + Sr) system ferrite sintered magnet can be obtained without particular limitation by selecting the above basic composition. Although the case where R = La is described in the above embodiment, when R = Pr or R = Nd or R = Ce, it has a higher (BH) max than the conventional ferrite magnet, and the W phase is the main phase. The ferrite magnet of the present invention can be obtained.

[0028]

As described above, according to the present invention, it is possible to provide a new high-performance ferrite magnet having a high (BH) max exceeding that of the conventional ferrite magnet. Further, since the high-performance ferrite magnet can be produced when it is calcined in the air and sintered in the air, it is highly practical.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of typical X-ray diffraction of a ferrite magnet of the present invention.

Claims (9)

[Claims] 1. A main phase of a W-type ferrite containing A (A is Sr, Ba or Ca), R (R is at least one of rare earth elements including Y), Co and Zn. A ferrite magnet having, wherein the total constituent ratio of each metal element (A, R, Fe, Co and Zn) is A: 1 to 13 atom%, R: 0.05 to 10 atom with respect to the total amount of metal elements. %, Fe: 78 to 95 atom%, Co: 0.5 to 15 atom%, and Zn: 0.5 to 15 atom%, a ferrite magnet having a basic composition. 2. R is at least one rare earth element selected from the group of La, Pr, Nd and Ce, and A is B
The ferrite magnet according to claim 1, wherein the ferrite magnet is a and / or Sr. 3. A main phase of a W-type ferrite containing A (A is Sr, Ba or Ca), R (R is at least one of rare earth elements including Y), Co and Zn. A ferrite magnet having the following general formula: A _x R _z Co _α Zn _β Fe _γ O ₂₇ (atomic ratio) (where x, z, α, β and γ are the following conditions: 0.9 <(x + z) < 1.2, 0.01 ≦ x <1.18, 0.01 ≦ z ≦ 0.4, 0.01 ≦ α ≦ 2, 0.01 ≦ β ≦ 2, and 16 ≦ γ ≦ 18)). And a ferrite magnet. 4. R is at least one rare earth element selected from the group of La, Pr, Nd and Ce, and A is B
The ferrite magnet according to claim 3, wherein the ferrite magnet is a and / or Sr. 5. The basic composition of the ferrite magnet according to claim 3 or 4 is 0.9 <(x + z) <1.2, 0.01 ≦ x <1.18, 0.01 ≦ z ≦ 0.4, 0.01 ≦ α ≦ 2, 0.01 ≦ β ≦ 2, a ferrite magnet represented by a number satisfying 0.5 ≦ (α + β) ≦ 2, (α / β)> 0.5, and 16.5 ≦ γ <18. 6. The ferrite magnet according to claim 3, wherein Fe is composed of divalent and trivalent iron, and F
e _γ = Fe ²⁺ _δ + Fe ³⁺ _γ-δ , and divalent Co
A ferrite magnet having a relationship of α + β + δ ≦ 2.4 between 2 ⁺ _α and Zn 2 ⁺ _β . 7. A main phase of a W-type ferrite containing A (A is Sr, Ba or Ca), R (R is at least one of rare earth elements including Y), Co and Zn. While having, the total constituent ratio of each metal element (A, R, Fe, Co and Zn) is A: 1 to 13 atom%, R: 0.05 to 10 atom%, Fe: A method for producing a ferrite magnet having a basic composition of 78 to 95 at%, Co: 0.5 to 15 at%, and Zn: 0.5 to 15 at%, which comprises forming a calcined product having the above basic composition and then pulverizing it. A method for producing a ferrite magnet, which comprises molding and sintering. 8. The method for producing a ferrite magnet according to claim 7, wherein calcination is performed in the atmosphere. 9. The method for producing a ferrite magnet according to claim 7, wherein sintering is performed in the atmosphere.