JP2009027032A - Manufacturing method of ferrite sintered magnet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new method for manufacturing a high-performance Ca-La-Co ferrite sintered magnet. <P>SOLUTION: In the manufacturing method of the ferrite sintered magnet, having an M type ferrite structure and having a composition represented by Ca<SB>1-x</SB>R<SB>x</SB>Fe<SB>2n-y</SB>Co<SB>y</SB>, 0.3≤1-x≤0.65, 0.2≤x≤0.65, 0.03≤y≤0.65, and 4≤n≤7, Na in an amount of 0.01-0.3 mass%, in an equivalent of sodium carbonate, is added to the total mass of mixture adjusted to the corresponding composition of the ferrite sintered magnet in a raw material mixing process. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a new and high-performance Ca-La-Co ferrite sintered magnet having higher magnetic properties than conventional Ca-La-Co ferrite sintered magnets.

  Magneto-plumbite type (M-type) sintered ferrite magnets are used in various applications including rotating machines such as motors and generators. Recently, there has been a demand for sintered ferrite magnets having even higher magnetic properties for the purpose of reducing the size and weight of rotating machines for automobiles and for improving the efficiency of rotating machines for electrical equipment. In particular, a rotating machine for automobiles has a high intrinsic coercive force (HcJ) that does not demagnetize due to a demagnetizing field generated when it is made thin while maintaining a high residual magnetic flux density (Br) from the viewpoint of miniaturization and weight reduction. There is a need for sintered ferrite magnets.

Patent Document 1 has hexagonal ferrite as a main phase, and has a general formula: Ca _1-x R _x (Fe _12-y M _y ) _z O ₁₉ (R is at least one selected from rare earth elements including Y and Bi). A seed element, which must contain La, M is Co and / or Ni, x, y and z are 0.2 ≦ x ≦ 0.8, 0.2 ≦ y ≦ 1.0, and A ferrite sintered magnet having a composition expressed by the following condition is satisfied. In paragraph [0018] and Example 6, the sintered ferrite magnet described in Patent Document 1 has about 2% higher saturation magnetization (4πIs) and about 10% higher anisotropic magnetic field (SrM) than Sr ferrite (SrM). H _A ). It is predicted that a sintered ferrite magnet having such a high value will have a high potential that cannot be realized with SrM. That is, Br of 4.6 kG (460 mT) or more is obtained, and the maximum value of HcJ may increase by about 10%. However, the sample No. described in Example 2 of Patent Document 1 is used. 2 of the magnetic properties _(when O 2 = 20% calcination) is is shown in Figure 2 it is Br = 4.4kG (440mT) and HcJ = 3.93kOe (313kA / m) , this value is expected There is room for improvement.

Japanese Patent No. 3181559

  Accordingly, an object of the present invention is to produce a new and high-performance Ca-La-Co ferrite sintered magnet having a high Br and / or a high HcJ compared to a conventional Ca-La-Co ferrite sintered magnet. It is to provide a method.

In view of the above-mentioned object, as a result of earnest research, the production method of the present invention created has an M-type ferrite structure, Ca, R, which is at least one rare earth element, and essentially contains La, Fe and Co Is an essential element, and the following general formula:
_{Ca 1-x R x Fe 2n} -y Co y ( atomic ratio)
[(1-x), x, y and n represent the content and molar ratio of Ca, R element and Co, respectively.
0.3 ≦ 1-x ≦ 0.65,
0.2 ≦ x ≦ 0.65,
0.03 ≦ y ≦ 0.65, and 4 ≦ n ≦ 7
It is a numerical value satisfying. Is a method of manufacturing a ferrite sintered magnet having a composition represented by the following: a raw material mixing step, a calcination step, a pulverization step, a molding step, and a firing step. Na is added in an amount of 0.01 to 0.3% by mass in terms of sodium carbonate with respect to the total mass of the mixture adjusted to a composition corresponding to the composition.

As the added Na compound, for example, carbonates such as sodium carbonate (Na ₂ CO ₃ ) and sodium hydrogen carbonate (NaHCO ₃ ), hydroxides such as NaOH, and chlorides such as NaCl are preferable.

In the present invention, the sintered ferrite magnet has the following general formula:
_{Ca 1-x R x Fe 2n} -y Co y O α ( atomic ratio)
[(1-x), x, y, n and α represent Ca, R element, Co content, molar ratio and O content, respectively.
0.3 ≦ 1-x ≦ 0.65,
0.2 ≦ x ≦ 0.65,
0.03 ≦ y ≦ 0.65, and 4 ≦ n ≦ 7
It is a numerical value satisfying. However, when the stoichiometric composition ratio is shown when x = y and n = 6, α = 19. ], It can have high Br and / or high HcJ.

  A Ca—La—Co ferrite sintered magnet having a high Br and / or a high HcJ as compared with a conventional Ca—La—Co ferrite sintered magnet can be produced.

<Composition of calcined body>
The calcined body that is a raw material of the sintered ferrite magnet according to the present invention is mainly composed of ferrite having a hexagonal crystal structure, and contains R element, Fe, and Co, which are at least one of Ca and rare earth elements and essentially contain La. An oxide magnetic material as an essential element, which has the following general formula:
_{Ca 1-x R x Fe 2n} -y Co y ( atomic ratio)
[(1-x), x, y and n represent the content and molar ratio of Ca, R element and Co, respectively.
0.3 ≦ 1-x ≦ 0.65,
0.2 ≦ x ≦ 0.65,
0.03 ≦ y ≦ 0.65, and 4 ≦ n ≦ 7
It is a numerical value satisfying. And those having a basic composition represented by

The Ca content (1-x) is preferably 0.3 to 0.65, and more preferably 0.35 to 0.55. When (1-x) is less than 0.3, the M phase is not stably generated, and ortho-ferrite is generated by the excess R element, so that the magnetic characteristics are deteriorated. When (1-x) exceeds 0.6, an undesirable phase such as CaFeO _3-x is formed.

  The value of the molar ratio x / y between the R element and Co is preferably 1 ≦ x / y ≦ 3, and more preferably 1.2 ≦ x / y ≦ 2. When x / y is less than 1, a heterogeneous phase containing a large amount of Co is generated, and the squareness ratio (Hk / HcJ) is deteriorated. When x / y exceeds 3, a heterogeneous phase such as orthoferrite is generated and the magnetic properties are greatly deteriorated.

R is at least one kind of rare earth elements such as La, Ce, Nd, and Pr, and contains La in an essential manner. In order to impart high magnetic properties, the ratio of La in the R element is preferably 50 atomic% or more, more preferably 70 atomic% or more, and La alone (however, inevitable impurities are allowed). Is particularly preferred. Since La is most easily dissolved in the M phase among the R elements, the effect of improving the magnetic properties is larger as the La ratio is larger. The R content (x) is preferably 0.2 to 0.65, more preferably 0.3 to 0.6, and still more preferably 0.35 to 0.55. If x is less than 0.2, the substitution amount of Co to the M phase is insufficient, so the M-type ferrite structure becomes unstable, and different phases such as CaO · Fe ₂ O ₃ and CaO · 2Fe ₂ O ₃ are generated. Magnetic properties are greatly reduced. When x exceeds 0.65, an unreacted oxide of R element increases, and an undesirable phase such as orthoferrite is generated.

  The Na added in terms of sodium carbonate is preferably 0.01 to 0.3% by mass, and 0.03 to 0.2% by mass with respect to the total mass of the mixture adjusted in the raw material mixing step. % Is more preferable. If the addition amount is less than 0.01% by mass, the effect of improving the magnetic properties due to the addition cannot be obtained, and if the addition amount exceeds 0.3% by mass, the magnetic properties are reduced.

The Co content (y) is preferably 0.03 to 0.65, more preferably 0.1 to 0.55, and particularly preferably 0.2 to 0.4. If y is less than 0.03, the effect of improving magnetic properties by adding Co cannot be obtained. Moreover, since unreacted α-Fe ₂ O ₃ remains in the calcined body, slurry leakage from the cavity of the mold is significantly generated during wet molding. If y exceeds 0.65, a heterogeneous phase containing a large amount of Co is generated and the magnetic properties are greatly deteriorated.

The molar ratio n is a value that reflects the molar ratio of (Ca + R) to (Fe + Co) and is represented by 2n = (Fe + Co) / (Ca + R). The molar ratio n is preferably 4 to 7, more preferably 4 to 6, and particularly preferably 4.9 to 5.6. When n is less than 4, the ratio of the non-magnetic portion increases, and the form of the calcined particles becomes excessively flat, and HcJ is greatly reduced. When n exceeds 7, unreacted α-Fe ₂ O ₃ remains in the calcined body, and slurry leakage becomes prominent from the mold cavity during wet molding.

In the raw material mixing step, it is acceptable to add a small amount of SiO ₂ or B ₂ O ₃ within a range in which Br is not lowered. In order to enhance the magnetic properties, it is preferable to add 0.05 to 0.2% by mass of B in terms of B ₂ O ₃ or 0.05 to 0.2% by mass of Si in terms of SiO _2. . If the B or Si content in the calcined body is less than 0.05% by mass, the effect of improving the magnetic properties cannot be obtained, and if it exceeds 0.2% by mass, the magnetic properties decrease.

<Composition of sintered ferrite magnet>
The sintered ferrite magnet according to the present invention has an M-type ferrite structure, Ca is an R element that is at least one of rare earth elements and contains La as an essential element, Fe and Co as essential elements, and has the following general formula:
_{Ca 1-x R x Fe 2n} -y Co y ( atomic ratio)
[(1-x), x, y and n represent the content and molar ratio of Ca, R element and Co, respectively.
0.3 ≦ 1-x ≦ 0.65,
0.2 ≦ x ≦ 0.65,
0.03 ≦ y ≦ 0.65, and 4 ≦ n ≦ 7
It is a numerical value satisfying. ] Has a basic composition represented by

Ca content (1-x) is 0.3-0.65, and it is preferable that it is 0.4-0.55. If (1-x) is less than 0.3, the M phase becomes unstable, and ortho-ferrite is generated by excess R element, resulting in a decrease in magnetic properties. When (1-x) exceeds 0.65, the M phase is not generated, and an unfavorable phase such as CaFeO _3-x is generated.

  The R element is at least one kind of rare earth elements such as La, Ce, Nd, and Pr, and contains La essentially. In order to impart high magnetic properties, the ratio of La in R is preferably 50 atomic% or more, more preferably 70 atomic% or more, and La alone (however, inevitable impurities are allowed). Is particularly preferred. The content (x) of the R element is 0.2 to 0.65, preferably 0.3 to 0.55, and more preferably 0.35 to 0.5. When x is less than 0.2, the substitution amount of Co to the M phase becomes insufficient, and the M-type ferrite structure becomes unstable. When x exceeds 0.65, the unreacted oxide of R element increases, and an undesirable phase such as orthoferrite is generated.

  Co content (y) is 0.03-0.65, it is preferable that it is 0.1-0.55, and it is more preferable that it is 0.2-0.4. If y is less than 0.03, the effect of improving magnetic properties by adding Co cannot be obtained. If y exceeds 0.65, a heterogeneous phase containing a large amount of Co is generated and the magnetic properties are greatly deteriorated.

The molar ratio n has the same meaning as the molar ratio n in the calcined body described above, is 4 to 7, preferably 4 to 6, and more preferably 4.5 to 5.5. When n is less than 4, the ratio of the nonmagnetic portion increases and the magnetic properties are deteriorated. When n exceeds 7, unreacted α-Fe ₂ O ₃ increases and the magnetic properties are greatly deteriorated.

  The value of the molar ratio x / y between the R element and Co is preferably 1 ≦ x / y ≦ 3, and more preferably 1.2 ≦ x / y ≦ 2. Satisfying these values improves the magnetic properties.

  When (R element content)> (Co content), that is, when x> y, the effect of improving magnetic properties is large.

The ferrite sintered magnet according to the present invention is obtained by adding 0.1 to 3% by mass of Cr ₂ O ₃ or Al ₂ O ₃ in the pulverization step with respect to the total mass of the basic composition, and thereafter molding and firing. Can have even higher HcJ. If the amount of Cr ₂ O ₃ or Al ₂ O ₃ added is less than 0.1% by mass, the effect of improving HcJ cannot be obtained, and if it exceeds 3% by mass, Br is greatly reduced.

The calcined body and ferrite sintered magnet according to the present invention have the following general formula:
_{Ca 1-x R x Fe 2n} -y Co y O α ( atomic ratio)
[(1-x), x, y, n and α represent Ca, R element, Co content, molar ratio and O content, respectively.
0.3 ≦ 1-x ≦ 0.65,
0.2 ≦ x ≦ 0.65,
0.03 ≦ y ≦ 0.65, and 4 ≦ n ≦ 7
It is a numerical value satisfying. However, when the stoichiometric composition ratio is shown when x = y and n = 6, α = 19. In order to have high magnetic properties, it is preferable to have a composition represented by

  That is, when the relationship between the content x of the R element and the Co content y is x = y and the molar ratio n = 6, the mole number α of oxygen (O) is 19. The number of moles of oxygen varies depending on the valence of Fe and Co, the n value, the type of R element, the calcination or firing atmosphere. The ratio of oxygen to the metal element changes due to oxygen deficiency (vacancy) when firing in a reducing atmosphere, changes in the valence of Fe in the M-type ferrite, changes in the valence of Co, and the like. Therefore, the actual mole number α of oxygen may deviate from 19.

<Manufacturing method>
The production method of the present invention will be described in detail below.

[Production of calcined body]
The calcined body is produced by a solid phase reaction method. In addition to the calcined body, the pulverized product may be used in combination with a defective product of a molded product or a sintered product or a recycled material such as a processing waste material. The calcined bodies may have different compositions and different production conditions. For example, two or more types of calcined bodies having different calcining conditions and compositions may be coarsely pulverized and blended. For example, calcined bodies having compositions of n = 4 and n = 7 can be mixed and used for pulverization.

  In the solid-phase reaction method, powder of an oxide and a powder of a compound (Ca compound, R element compound, Na compound, iron compound, Co compound) that becomes an oxide by calcination are used as raw materials. These raw material powders are mixed at a predetermined ratio, and the obtained mixture is calcined (ferritized) to produce a calcined body (usually granular or clinker).

  The calcination is practically performed in the atmosphere (substantially equivalent to an oxygen partial pressure of about 0.05 to 0.2 atm), but in an oxygen-excessive atmosphere (for example, the oxygen partial pressure exceeds 0.2 atm). 1 atm or less), particularly in an oxygen 100% atmosphere. The calcining temperature is preferably 1373 to 1623K, and more preferably 1423 to 1573K. The calcination time is preferably 1 second to 10 hours, more preferably 0.1 to 3 hours. The calcined body is preferably substantially composed of an M phase.

  As the Ca compound, a carbonate, oxide, chloride or the like of Ca is used.

As the R element compound, oxides such as La ₂ O ₃ , hydroxides of La (OH) ₃ , carbonates such as La ₂ (CO ₃ ) ₃ · 8H ₂ O, and the like are used. In particular, mixed rare earth (La, Nd, Pr, Ce, etc.) oxides, hydroxides, carbonates, and the like are inexpensive and can reduce costs.

  As the iron compound, iron oxide, iron hydroxide, iron chloride, mill scale or the like is used.

Examples of the Co compound include oxides such as CoO and Co ₃ O ₄ , and hydroxides such as CoOOH, Co (OH) ₂ , and Co ₃ O ₄ .m ₁ H ₂ O (m ₁ is a positive number). , carbonates such as CoCO ₃ and _{m 2 CoCO 3 · m 3 Co} (OH) 2 · m 4 H 2 O and the like of a basic _{carbonate, (m 2, m 3,} m 4 are positive numbers.) Is used.

[Crushing]
For pulverization of the calcined body, if necessary, after coarse crushing with a jaw crusher, hammer mill or the like, dry coarse crushing is performed with a vibration mill, roller mill or the like. The average particle size of the coarsely pulverized powder is preferably 2 to 5 μm in order to reduce the load of wet or dry fine pulverization in the subsequent process. The average particle diameter can be measured on the basis of a bulk density of 65% by an air permeation method (measuring device: Fischer Sub-Sieve Sizer, hereinafter abbreviated as FSSS). Next, wet pulverization or dry pulverization is performed.

  When the slurry obtained by wet pulverization is used as a raw material for wet molding, water is added to the dry coarsely pulverized powder and pulverized by a wet pulverizer such as an attritor or a ball mill. From the viewpoint of obtaining industrial productivity such as dehydration characteristics of slurry obtained by wet pulverization and high magnetic characteristics, the average particle size of the pulverized powder of the calcined body dispersed in the slurry is 0.4 to 1.3 μm. (Measured based on a bulk density of 65% according to FSSS). When the average particle size is finely pulverized to less than 0.4 μm, HcJ and the like are reduced due to abnormal crystal grain growth during firing, and dehydration characteristics during wet molding are markedly deteriorated. When the average particle size exceeds 1.3 μm, the ratio of coarse crystal grains in the ferrite sintered body increases, and HcJ greatly decreases. The average particle size of the finely pulverized powder is more preferably 0.7 to 1.3 μm, further preferably 0.8 to 1.3 μm, and particularly preferably 0.8 to 1.2 μm.

It is preferable to add 0.1 to 1.5% by mass of SiO ₂ and 0.2 to 1% by mass with respect to the total mass of the dry coarsely pulverized powder (calcined body) introduced during wet pulverization. Is more preferable. By adding SiO ₂ , high HcJ can be stably obtained, but if the addition amount of SiO ₂ is less than 0.1% by mass, the effect of addition cannot be obtained, and if it exceeds 1.5% by mass, grain growth is suppressed. The effect becomes excessive, the ratio of the nonmagnetic phase increases, and Br decreases.

It is preferable to add 0.1 to 2% by mass of CaCO ₃ with respect to the total mass of the calcined body during wet pulverization, and it is more preferable to add 0.2 to 1.5% by mass. By adding CaCO ₃ , grain growth of M-type ferrite particles during firing is promoted and Br is improved. When the addition amount of CaCO ₃ is less than 0.1% by mass, the effect of addition cannot be obtained, and when it exceeds 2% by mass, grain growth during firing proceeds excessively and HcJ is greatly reduced. In other words, the addition of CaCO ₃ is preferably performed within a specific range of the addition amount so that the molar ratio n of the sintered ferrite magnet according to the present invention is 4 to 6, more preferably 4.5 to 5.5. The amount should be adjusted appropriately.

  Adjusting the molar ratio n of the sintered ferrite magnet according to the present invention without degrading the magnetic properties by adding 0.05 to 30 parts by mass of iron oxide to 100 parts by mass of the calcined body during wet pulverization Can do. If the amount is less than 0.05 parts by mass, the effect of addition cannot be obtained. If the amount exceeds 30 parts by mass, slurry leakage from the mold during wet molding becomes significant.

  After the wet pulverization, the obtained slurry is concentrated and molded as necessary. Concentration is performed by centrifugation, filter press or the like.

  A slurry obtained by heating and drying and then pulverizing with an atomizer or the like can be used as a raw material for dry molding.

  The calcined body coarse powder is finely pulverized by a dry mill using a vibration mill or the like to obtain a finely pulverized powder having an average particle size of 0.7 to 1.3 μm (measured based on a bulk density of 65% by FSSS). This may be used as a raw material for dry molding.

  A compact obtained by compressing and molding the slurry in a wet magnetic field is crushed by a crusher or the like, and then classified by sieving to an average particle size of about 100 to 700 μm. It is good also as a raw material.

[Molding]
Molding is performed dry or wet. An isotropic sintered ferrite magnet can be obtained when pressure-molding and firing without applying a magnetic field. An anisotropic ferrite sintered magnet having high Br and high HcJ can be obtained when it is pressure-molded by applying a magnetic field and fired. In order to increase the degree of orientation and Br of the molded body and the fired body, molding in a wet magnetic field is preferable to molding in a dry magnetic field.

  When performing compression molding in a wet or dry magnetic field, the applied pressure is preferably about 4.9 to 49 MPa, and the applied magnetic field strength is preferably about 398 to 1194 kA / m. When the molding pressure is less than 4.9 MPa, the molded product becomes brittle, and when it exceeds 49 MPa, the degree of orientation of the molded product is greatly reduced. When the applied magnetic field strength is less than 398 kA / m, it is difficult to impart anisotropy, and when it exceeds 1194 kA / m, the effect of imparting anisotropy (orientation degree) is almost saturated.

  In order to obtain a molded body for an anisotropic ferrite sintered magnet, it is practical to use a longitudinal magnetic field compression molding in which the direction of the orientation magnetic field applied in the mold cavity and the pressing direction of the molding pressure are virtually the same. Is. A preferable range of the applied pressure and the applied magnetic field strength is the same as described above.

  In order to obtain a molded body for an anisotropic ferrite sintered magnet having a higher degree of orientation than a longitudinal magnetic field compacted body, the direction of the orientation magnetic field applied in the cavity of the mold and the pressing direction of the molding pressure are the facts It is preferable to employ transverse magnetic field compression molding that is orthogonal to the top. A preferable range of the applied pressure and the applied magnetic field strength is the same as described above.

[Baking]
The molded body is freed from moisture, a dispersant, and the like by natural drying or heat drying (373-773 K) in the air, and then fired to obtain a sintered ferrite magnet. It is practical to perform the firing in the atmosphere (substantially the oxygen partial pressure is about 0.05 to 0.2 atm). Baking may be performed in an oxygen-excess atmosphere (for example, the oxygen partial pressure is more than 0.2 atm and 1 atm or less), particularly in an oxygen 100% atmosphere. Firing is performed at a temperature of 1423 to 1573 K, preferably 1433 to 1543 K, for 0.5 to 5 hours, preferably 1 to 3 hours. The density of the sintered ferrite magnet according to the present invention is preferably 5.05 to 5.10 g / cm ³ .

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the following Example.

(Example 1, Comparative Example 1, Comparative Example 2)
<Relationship between Na ₂ CO ₃ Addition and Magnetic Properties>
CaCO ₃ powder (purity 98.8%, including MgO as an impurity), La (OH) ₃ powder (purity 99.9%), α-Fe ₂ O ₃ powder (industrial) and Co ₃ O ₄ powder ( 99% purity) was blended so as to have a composition of Ca _0.5 La _0.5 Fe _10.3 Co _0.3 O ₁₉ . To 100 parts by mass of this blend, 0.1 part by mass of H ₃ BO ₃ powder and 0 to 0.4 part by mass of Na ₂ CO ₃ powder were added and wet mixed. The obtained mixture was dried and calcined in the air at 1473K for 1 hour.

The calcined body was coarsely crushed and then dry coarsely pulverized with a vibration mill to obtain coarse powder having an average particle size of 5 μm (according to FSSS). 45% by mass of coarse powder and 55% by mass of water were charged into a ball mill, and 0.325 parts by mass of SiO ₂ powder (purity 92.1%, the balance being almost water) and 0 with respect to 100 parts by mass of coarse powder. .5 parts by mass of CaCO ₃ powder was added as a sintering aid and wet pulverization was performed to obtain a slurry containing ferrite fine particles having an average particle size of 0.9 μm (according to FSSS).

  The compacted slurry was subjected to compression molding (applied magnetic field strength of 796 kA / m) in a parallel magnetic field at a molding pressure of 39.2 MPa to obtain a compact. The obtained compact was fired in the atmosphere at a temperature of 1493K for 1 hour to obtain an anisotropic ferrite sintered magnet. Table 1 shows the results of measuring the magnetic properties at room temperature (293K) using a BH tracer.

(Conventional example 1)
Sample No. 1 of Patent Document 1 is used. Two trace experiments were performed. In a formulation having a composition of Ca _1-x La _x Fe _2n-y Co _y O ₁₉ (x = 0.500, y = 0.43, n = 5.1), 0.4% by mass of SiO ₂ is added. The added mixture was prepared and calcined in air at 1473K for 3 hours. After roughly pulverizing and roughly pulverizing the calcined body, 0.6% by mass of SiO ₂ and 1.0% by mass of CaCO ₃ are added to the coarse powder, and wet pulverization is performed with a ball mill using water as a medium. Thus, a slurry in which fine powder having an average particle size of 0.9 μm was dispersed was obtained (since the average fine particle size of sample No. 2 in Patent Document 1 is unknown, the average particle size of finely pulverized powder of Example 1 was 0.9 μm. Combined.) From this slurry, anisotropic ferrite sintered magnets were produced in the same manner as in Example 1 and the magnetic properties were measured. The results are shown in Table 1.

From Table 1, compared with Comparative Example 1 in which Na ₂ CO ₃ was not added, 0.01 to 0.3% by mass of Na ₂ CO ₃ was obtained in Example 1 obtained by adding to the mixture before calcination. In the case of an anisotropic ferrite sintered magnet, it can be seen that Br or Br and HcJ are improved. However, in the case of Comparative Example 2 in which Na ₂ CO ₃ was added in an amount of 0.4% by mass, it was found that Br decreased.
It can also be seen that the anisotropic ferrite sintered magnet of Conventional Example 1 has a lower Br than that of Example 1.

Claims (2)

It has an M-type ferrite structure, is an R element that is at least one of Ca and rare earth elements and contains La as essential elements, Fe and Co as essential elements, and has the following general formula:
_{Ca 1-x R x Fe 2n} -y Co y ( atomic ratio)
[(1-x), x, y and n represent the content and molar ratio of Ca, R element and Co, respectively.
0.3 ≦ 1-x ≦ 0.65,
0.2 ≦ x ≦ 0.65,
0.03 ≦ y ≦ 0.65, and 4 ≦ n ≦ 7
It is a numerical value satisfying. Is a method of manufacturing a ferrite sintered magnet having a composition represented by the following: a raw material mixing step, a calcination step, a pulverization step, a molding step, and a firing step. The manufacturing method of the ferrite sintered magnet characterized by adding 0.01-0.3 mass% of Na by the conversion value of sodium carbonate with respect to the total mass of the mixture adjusted to the composition corresponding to this composition. The method for producing a sintered ferrite magnet according to claim 1, wherein the sintered ferrite magnet has the following general formula:
_{Ca 1-x R x Fe 2n} -y Co y O α ( atomic ratio)
[(1-x), x, y, n and α represent Ca, R element, Co content, molar ratio and O content, respectively.
0.3 ≦ 1-x ≦ 0.65,
0.2 ≦ x ≦ 0.65,
0.03 ≦ y ≦ 0.65, and 4 ≦ n ≦ 7
It is a numerical value satisfying. However, when the stoichiometric composition ratio is shown when x = y and n = 6, α = 19. ] The manufacturing method of the sintered ferrite magnet characterized by the above-mentioned.