JP2021057587A - Ferrite calcined body, ferrite sintered magnet, and manufacturing method thereof - Google Patents

Abstract

To provide a ferrite sintered magnet that has a high Br and a small decrease in HcJ, and uses less La than a conventional Ca-La-Co-based ferrite sintered magnet by reducing the amount of Co used by 25% or more compared to a general Sr-La-Co-based ferrite sintered magnet.SOLUTION: In a general formula indicating the atomic ratio of metal elements of Ca, R, A, Fe, Co, and Zn: Ca1-x-x'RxAx'Fe2n-y-zCoyZnz, in a ferrite calcined body, x, x', y, and z, and n (2n is a molar ratio, and 2n=(Fe+Co+Zn)/(Ca+R+A)) satisfies 0.1≤x≤0.4, 0<x'≤0.3, 0<y<0.15, 0<z<0.15, 1-x-x'>x, and 4.5≤n≤5.5.SELECTED DRAWING: None

Description

The present disclosure relates to a ferrite calcined body, a ferrite sintered magnet, and a method for producing the same.

Ferrite sintered magnets have a maximum energy product of only 1/10 of rare earth-based sintered magnets (for example, NdFeB-based sintered magnets), but because the main raw material is inexpensive iron oxide, they are excellent in cost performance and chemical. It has the feature of being extremely stable. Therefore, it is used for various purposes such as various motors and speakers, and the world production weight is still the largest among magnet materials.

A typical ferrite sintered magnet is Sr ferrite having a magnetoplumbite structure, and its basic composition is represented by _{SrFe 12} O _19. Ferrite was put into practical use in the latter half of the 1990s when an Sr-La-Co-based ferrite sintered magnet in which a part of Sr ²⁺ _{of SrFe 12} O ₁₉ was replaced with ^{La 3+} and a part of ^{Fe 3+ was replaced with Co 2+ was put into practical use.} The magnet properties of the magnet have been greatly improved. Further, in 2007, a Ca-La-Co-based ferrite sintered magnet having further improved magnet characteristics was put into practical use.

In both the Sr-La-Co-based ferrite sintered magnet and the Ca-La-Co-based ferrite sintered magnet, Co is indispensable for obtaining high magnet characteristics. In a general Sr-La-Co-based ferrite sintered magnet, Co in an atomic ratio of about 0.2 (Co / Fe = 0.017, that is, about 1.7% of the Fe content) is the conventional Ca-La. The −Co-based ferrite sintered magnet contains Co (Co / Fe = 0.03, that is, about 3% of the Fe content) in an atomic ratio of about 0.3. Further, in a general Sr-La-Co-based ferrite sintered magnet, La having an atomic ratio of about 0.2 (La / Fe = 0.017, that is, about 1.7% of the Fe content) is a conventional Ca. The −La—Co-based ferrite sintered magnet contains La at an atomic ratio equivalent to that of Ca. The price of Co (Co oxide) is ten to several tens of times that of iron oxide, which is the main raw material of ferrite sintered magnets, and La (La oxide and La hydroxide) is also more expensive than iron oxide. Therefore, in the conventional Ca-La-Co-based ferrite sintered magnet, an increase in raw material cost is unavoidable as compared with a general Sr-La-Co-based ferrite sintered magnet. The biggest feature of ferrite sintered magnets is that they are inexpensive, so even if they have high magnet characteristics, they are difficult to accept in the market if they are expensive. Therefore, the demand for Sr-La-Co-based ferrite sintered magnets is still high worldwide.

In recent years, the price of Co has skyrocketed due to the increase in demand for Li-ion batteries due to the increase in the supply of electric vehicles. In the aftermath, it is difficult to maintain the product price even for Sr-La-Co-based ferrite sintered magnets, which are excellent in cost performance. Against this background, how to reduce the amount of Co used while maintaining the magnet characteristics has become an urgent issue.

Although the purpose is not to reduce the amount of Co, for example, in an Sr-La-Co-based ferrite sintered magnet, by substituting a part of Co with Zn, the residual magnetic flux density (hereinafter referred to as " _Br ") can be increased. It is known to improve (Patent Document 1 and the like).

Japanese Unexamined Patent Publication No. 11-154604

However, when a part of Co in the Sr-La-Co ferrite sintered magnet was replaced with Zn, increased width of B _r is not so large, while the coercive force (hereinafter referred to as "H _cJ") is remarkably lowered There is a problem that it has not been put into practical use.

Embodiments of the present disclosure has a high _{B r,} (higher _{H cJ} than when substituting a part of Co in the Zn in Sr-La-Co ferrite sintered magnet) less decrease in _{H cJ} is, In addition, the amount of Co used is reduced by 25% or more compared to general Sr-La-Co-based ferrite sintered magnets (containing about 0.2 in atomic ratio), and conventional Ca-La-Co-based ferrites are used. It enables the provision of ferrite sintered magnets in which the amount of La used is less than that of sintered magnets.

An exemplary ferrite calcined body, which is not limited in the present disclosure,
General formula indicating the atomic ratio of metal elements of Ca, R, A, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La, and A is Sr and / or Ba): in _{Ca 1-x-x 'R} x A x' Fe 2n-y-z Co y Zn z,
The x, x', y and z, and n (where 2n is a molar ratio and is represented by 2n = (Fe + Co + Zn) / (Ca + R + A)) are
0.1 ≤ x ≤ 0.4,
0 <x'≤ 0.3,
0 <y <0.15,
0 <z <0.15,
1-x-x'> x, and 4.5 ≦ n ≦ 5.5,
To be satisfied.

In one embodiment, 0.2 ≦ x ≦ 0.3.
In one embodiment, 0.1 ≦ x'≦ 0.3.

The non-limiting exemplary ferrite sintered magnets of the present disclosure are:
General formula indicating the atomic ratio of metal elements of Ca, R, A, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La, and A is Sr and / or Ba): in _{Ca 1-x-x 'R} x A x' Fe 2n-y-z Co y Zn z,
The x, x', y and z, and n (where 2n is a molar ratio and is represented by 2n = (Fe + Co + Zn) / (Ca + R + A)) are
0 <x ≦ 0.4,
0 <x'≤ 0.3,
0 <y <0.15,
0 <z <0.15,
1-x-x'> x, and 3.5 ≦ n ≦ 5.5,
To be satisfied.

In a certain embodiment, Si of 1.5 mass% or less (excluding 0 mass%) in terms of _{SiO 2 is further contained.}

An exemplary method for producing a ferrite sintered magnet, which is not limited to the present disclosure,
General formula indicating the atomic ratio of metal elements of Ca, R, A, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La, and A is Sr and / or Ba): in _{Ca 1-x-x 'R} x A x' Fe 2n-y-z Co y Zn z,
The x, y and z, and n (where 2n is a molar ratio and is represented by 2n = (Fe + Co + Zn) / (Ca + R + A)) are
0.1 ≤ x ≤ 0.4,
0 <x'≤ 0.3,
0 <y <0.15,
0 <z <0.15,
1-x-x'> x, and 4.5 ≦ n ≦ 5.5,
Raw material powder mixing process to obtain a mixed raw material powder by mixing the raw material powders that satisfy the above.
A calcining step of calcining the mixed raw material powder to obtain a calcined body,
A crushing step of crushing the calcined body to obtain powder of the calcined body,
A molding process of molding the powder of the calcined product to obtain a molded product,
A firing step of calcining the molded body to obtain a sintered body,
including.

_{In a certain embodiment, after the calcining step and before the molding step, a step of adding SiO 2 of} 1.5 mass% or less with respect to 100 mass% of the calcined body or the powder of the calcined body to be added is further added. Including.

In a certain embodiment, after the calcining step and before the molding step, CaCO ₃ of 1.5 mass% or less in terms of CaO is added to 100 mass% of the calcined body or the powder of the calcined body to be added. Further includes steps.

According to embodiments of the present disclosure, high _B has _r, higher _{H cJ} than when a part of Co in less decrease in _{H cJ} is (Sr-La-Co ferrite sintered magnet was replaced with Zn ), And the amount of Co used is reduced by 25% or more compared to general Sr-La-Co-based ferrite sintered magnets (containing about 0.2 in atomic ratio), and further, conventional Ca-La-Co It is possible to provide a ferrite sintered magnet in which the amount of La used is reduced as compared with the system ferrite sintered magnet.

1. 1. Ferrite calcined body The ferrite calcined body of the embodiment of the present disclosure is
General formula indicating the atomic ratio of metal elements of Ca, R, A, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La, and A is Sr and / or Ba): in _{Ca 1-x-x 'R} x A x' Fe 2n-y-z Co y Zn z,
The x, x', y and z, and n (where 2n is a molar ratio and is represented by 2n = (Fe + Co + Zn) / (Ca + R + A)) are
0.1 ≤ x ≤ 0.4,
0 <x'≤ 0.3,
0 <y <0.15,
0 <z <0.15,
1-x-x'> x, and 4.5 ≦ n ≦ 5.5,
To be satisfied.

The atomic ratio x (content of R) is 0.1 ≦ x ≦ 0.4. As described above, in the conventional Ca-La-Co-based ferrite sintered magnet, R (La) was contained in an atomic ratio of about 0.4 to 0.6, but in the ferrite calcined body of the present embodiment, the A element is contained. The content of (Sr and / or Ba) can reduce the content of R to 0.4 or less. If x is less than 0.1, a high _Br cannot be obtained. If x exceeds 0.4, the effect of reducing the R content cannot be obtained. R is at least one of rare earth elements and essentially contains La. La is preferably contained in a molar ratio of 50% or more, and more preferably only R = La. More preferably, x is 0.2 ≦ x ≦ 0.3.

The atomic ratio x'(content of element A) is 0 <x'≤0.3. A is Sr and / or Ba. If x'is 0 (not contained), the effect of reducing the R content cannot be obtained. If x'exceeds 0.3, a high _Br cannot be obtained. It is preferable that x'is 0.1 ≦ x'≦ 0.3.

The atomic ratio 1-x-x'(Ca content) and x (R content) satisfy the relationship of 1-x-x'> x. That is, the content of Ca is increased more than the content of R.

The atomic ratio y (Co content) is 0 <y <0.15. If y is 0.15 or more, the effect of reducing the amount of Co used cannot be obtained. When y is 0 (not contained), the decrease _{in H cJ becomes large, which is not preferable.} y is preferably 0 <y ≦ 0.13, more preferably 0.10 ≦ y ≦ 0.13.

The atomic ratio z (Zn content) is 0 <z <0.15. When z is 0 (not contained), a high _Br cannot be obtained, and the effect of reducing the amount of Co used cannot be obtained. If z is 0.15 or more, high H _cJ cannot be obtained. More preferably, z is 0.02 ≦ z ≦ 0.05.

The atomic ratios y and z preferably satisfy the relationship of 0 <(y + z) ≦ 0.2. (Y + z) when the 0 (not contained) or more than 0.2 _{B r} or _{H cJ} may be lowered.

In the above general formula, 2n is a molar ratio and is represented by 2n = (Fe + Co + Zn) / (Ca + R + A). n is 4.5 ≦ n ≦ 5.5. If n is less than 4.5 or more than 5.5, a high _Br cannot be obtained.

The general formula is shown in atomic ratio of metal elements, the composition containing oxygen (O) has the general _{formula: Ca 1-x-x '} R x A x' Fe 2n-y-z Co y Zn z O It is represented by _α. The number of moles α of oxygen is basically α = 19, but it differs depending on the valences of Fe and Co, the values of x, y and z and n, and the like. Further, the ratio of oxygen to the metal element changes due to the pores (vacancy) of oxygen when firing in a reducing atmosphere, the change in the valence of Fe in the ferrite phase, the change in the valence of Co, and the like. Therefore, the actual number of moles of oxygen α may deviate from 19. Therefore, in the embodiment of the present disclosure, the composition is expressed by the atomic ratio of the metal element whose composition is most easily specified.

The main phase constituting the ferrite calcined body of the embodiment of the present disclosure is a compound phase (ferrite phase) having a hexagonal magnetoplumbite (M type) structure. Generally, a magnetic material, particularly a sintered magnet, is composed of a plurality of compounds, and the compound that determines the characteristics (physical properties, magnet characteristics, etc.) of the magnetic material is defined as the "main phase".

"Having a hexagonal magnetoplumbite (M-type) structure" means that when the X-ray diffraction of the ferrite calcined body is measured under general conditions, the X-ray of the hexagonal magnetoplumbite (M-type) structure It means that the line diffraction pattern is mainly observed.

An example of the method for producing a ferrite sintered magnet according to the present disclosure, which includes the method for producing a ferrite calcined body according to the embodiment of the present disclosure described above, will be described below.

2. Method for Producing Ferrite Sintered Magnets As the raw material powder, compounds such as oxides, carbonates, hydroxides, nitrates and chlorides of the respective metals can be used regardless of the valence. It may be a solution in which the raw material powder is dissolved. Examples of the compound of Ca include carbonates, oxides and chlorides of Ca. Examples of the compound of R, when the La example, include oxides such as _{La 2 O 3, La (OH} ) 3 , etc. _{hydroxides, La 2 (CO 3) 3} · 8H 2 carbonates O, etc. and the like Be done. Examples of the compound of element A include carbonates, oxides and chlorides of Sr and / or Ba. Examples of the Fe compound include iron oxide, iron hydroxide, iron chloride, and mill scale. Examples of Co compounds include oxides such as CoO and Co ₃ O ₄ , hydroxides such as CoOOH and Co (OH) ₂ , carbonates such as _{CoCO 3 , and m 2} CoCO ₃ · m ₃ Co (OH) _2. -Basic carbonates such as m ₄ H _{2 O (m 2} , m ₃ and m ₄ are positive numbers) can be mentioned. Examples of the Zn compound include ZnO.

In order to promote the reaction at the time of calcination _{, a compound containing B (boron) such as B 2} O ₃ and H ₃ BO ₃ may be added up to about 1 mass% as needed. In particular, _{the addition of H 3} BO ₃ is effective in improving the magnet characteristics. The _{amount of H 3} BO ₃ added is preferably 0.3 mass% or less, most preferably about 0.1 mass%. Since H ₃ BO ₃ also has the effect of controlling the shape and size of crystal grains during firing, it may be added after calcining (before pulverization or before firing), and both before calcining and after calcining. It may be added.

Raw material powders satisfying the components and compositions of the above-described ferrite calcined product of the present disclosure are mixed to obtain a mixed raw material powder. The raw material powder may be blended or mixed by either a wet type or a dry type. The raw material powder can be mixed more uniformly by stirring with a medium such as a steel ball. In the wet case, it is preferable to use water as the dispersion medium. A known dispersant such as ammonium polycarboxylic acid or calcium gluconate may be used for the purpose of enhancing the dispersibility of the raw material powder. The mixed raw material slurry may be calcined as it is, or the raw material slurry may be dehydrated and then calcined.

The mixed raw material powder obtained by dry mixing or wet mixing is heated using an electric furnace, a gas furnace, or the like to obtain a hexagonal magnetoplumbite (M-type) -structured ferrite compound by a solid-phase reaction. Form. This process is called "temporary firing" and the resulting compound is called "temporary firing". Therefore, the ferrite calcined body of the embodiment of the present disclosure can be paraphrased as a ferrite compound.

In the calcining step, a solid-phase reaction in which a ferrite phase is formed proceeds as the temperature rises. If the calcining temperature is less than 1100 ° C., unreacted hematite (iron oxide) remains, so that the magnet characteristics are lowered. On the other hand, if the calcining temperature exceeds 1450 ° C., the crystal grains grow too much, so that it may take a long time to pulverize in the pulverization step. Therefore, the calcining temperature is preferably 1100 ° C to 1450 ° C. The calcination time is preferably 0.5 hour to 5 hours. It is preferable that the calcined body after calcining is roughly pulverized by a hammer mill or the like.

By going through the above steps, the ferrite calcined body of the embodiment of the present disclosure can be obtained. Subsequently, a method for manufacturing the ferrite sintered magnet according to the embodiment of the present disclosure will be described.

The calcined body is pulverized (finely pulverized) by a vibration mill, a jet mill, a ball mill, an attritor or the like to obtain a powder of the calcined body (finely pulverized powder). The average particle size of the powder of the calcined product is preferably about 0.4 μm to 0.8 μm. In the embodiment of the present disclosure, a value measured by an air permeation method using a powder specific surface area measuring device (for example, SS-100 manufactured by Shimadzu Corporation) is referred to as an average particle size (average particle size) of the powder. The pulverization step may be either dry pulverization or wet pulverization, or both may be combined. In the case of wet pulverization, water and / or a non-aqueous solvent (organic solvent such as acetone, ethanol, xylene) is used as a dispersion medium. Typically, a slurry containing water (dispersion medium) and a calcined product is produced. A known dispersant and / or surfactant may be added to the slurry in terms of solid content ratio of 0.2 mass% to 2 mass%. After the wet grinding, the slurry may be concentrated.

In the molding step, the slurry after the pulverization step is press-molded in a magnetic field or no magnetic field while removing the dispersion medium. By press molding in a magnetic field, the crystal orientation of the powder particles can be aligned (orientated), and the magnet characteristics can be dramatically improved. Further, in order to improve the orientation, a dispersant and a lubricant may be added to the slurry before molding in an amount of 0.1 mass% to 1 mass%, respectively. Further, the slurry may be concentrated if necessary before molding. Concentration is preferably carried out by centrifugation, filter press or the like.

After the calcining step and before the molding step, a sintering aid may be added to the calcined product or the powder of the calcined product (coarse pulverized powder or finely pulverized powder). As the sintering aid, SiO ₂ and CaCO ₃ are preferable. The ferrite sintered magnet of the embodiment of the present disclosure belongs to the Ca-La-Co based ferrite sintered magnet as is clear from its composition. Since Ca is contained as a main phase component in Ca-La-Co-based ferrite sintered magnets, firing of SiO ₂ and CaCO ₃ like general Sr-La-Co-based ferrite sintered magnets is performed. A liquid phase is formed and can be sintered without the addition of an aid. That is, the ferrite sintered magnet of the embodiment of the present disclosure can be manufactured without adding _{SiO 2} or CaCO _{3 which mainly forms a grain boundary phase in the ferrite sintered magnet.} However, in order to suppress the decrease _{in H cJ , the following amounts of SiO 2} and CaCO ₃ may be added.

The _{amount of SiO 2} added is preferably 1.5 mass% or less with respect to 100 mass% of the calcined body or the powder of the calcined body to be added. The _{amount of CaCO 3} added is preferably 1.5 mass% or less in terms of CaO with respect to 100 mass% of the calcined body or the powder of the calcined body to be added. The sintering aid is added, for example, to the calcined product obtained by the calcining step, and then the crushing step is carried out, added in the middle of the crushing step, or the powder of the calcined body after the crushing step ( A method such as adding to (finely pulverized powder), mixing, and then carrying out a molding step can be adopted. In addition to _{SiO 2} and CaCO _{3 , Cr 2} O ₃ , Al ₂ O _{3, and the} like may be added as the sintering aid. The amount of each of these additions may be 1 mass% or less.

In the embodiment of the present disclosure, _{all the amounts of CaCO 3} added are expressed in terms of CaO. From the amount of CaO added, the amount of CaCO ₃ added is
Formula: ( _{Molecular weight of CaCO 3} x amount added in terms of CaO) / Can be calculated by the molecular weight of CaO. For example, when adding 0.5 mass% CaCO _{3 in terms of CaO,}
{(40.08 [Atomic weight of Ca] + 12.01 [Atomic weight of C] + 48.00 [Atomic weight of O x 3] = 100.09 [ _{Molecular weight of CaCO 3} ]) x 0.5 mass% [Addition in terms of CaO] Amount]} / (40.08 [atomic weight of Ca] + 16.00 [atomic weight of O] = 56.08 [molecular weight of CaO]) = 0.892 mass% [addition amount of _{CaCO 3].}

The molded product obtained by press molding is degreased as necessary and then fired (sintered). Firing is performed using an electric furnace, a gas furnace, or the like. The firing is preferably performed in an atmosphere having an oxygen concentration of 10% by volume or more. It is more preferably 20% by volume or more, and most preferably 100% by volume. The firing temperature is preferably 1150 ° C to 1250 ° C. The firing time is preferably 0 hours (without holding at the firing temperature) to 2 hours.

After the firing step, a ferrite sintered magnet is finally manufactured through known manufacturing processes such as a processing step, a cleaning step, and an inspection step.

3. 3. Ferrite Sintered Magnet As described above, the ferrite calcined product of the embodiment of the present disclosure can generate a liquid phase and can be sintered without adding a sintering aid such as _{SiO 2} or CaCO _3. , The ferrite sintered magnet of the embodiment of the present disclosure can be obtained. At this time, the composition and composition of the ferrite calcined body and the composition and composition of the ferrite sintered magnet are basically the same (the mixing of impurities in the manufacturing process is not considered).

On the other hand, when the sintering aid is added, especially when the Ca component (for example, CaCO ₃ ), which is also the main component of the ferrite calcined product, is added as the sintering aid, the Ca component increases as a whole ferrite sintered magnet. Therefore, other elements are relatively reduced. _{For example, when 1.5 mass% of CaCO 3} is added as a sintering aid in terms of CaO using the ferrite calcined product of the embodiment of the present disclosure, in the most fluctuating case, 0.1 ≦ x <0.4 ( The calcined body) is 0 <x <0.4 (sintered magnet), and 4.5 ≦ n ≦ 5.5 (temporary calcined body) is 3.5 ≦ n ≦ 5.5 (sintered magnet). ..

Therefore, the ferrite sintered magnet of the embodiment of the present disclosure is
General formula indicating the atomic ratio of metal elements of Ca, R, A, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La, and A is Sr and / or Ba): in _{Ca 1-x-x 'R} x A x' Fe 2n-y-z Co y Zn z,
The x, x', y and z, and n (where 2n is a molar ratio and is represented by 2n = (Fe + Co + Zn) / (Ca + R + A)) are
0 <x ≦ 0.4,
0 <x'≤ 0.3,
0 <y <0.15,
0 <z <0.15,
1-x-x'> x, and 3.5 ≦ n ≦ 5.5,
Will be satisfied.

The composition of the ferrite sintered magnet according to the present disclosure when oxygen (O) is contained, the main phase constituting the ferrite sintered magnet, the definition of the hexagonal magnetoplumbite (M type) structure, and the like are described. It is the same as the ferrite calcined body of the embodiment of the present disclosure. Further, as described above, although the range varies from the ferrite calcined body, the reasons for limiting the atomic ratios x, x', y, and z and the reasons for limiting n are the same as those of the ferrite calcined body. Omit.

As described above, in the method for producing a ferrite sintered magnet according to the present disclosure, when SiO ₂ is added as a sintering aid in an amount of 1.5 mass% or less based on 100 mass% of the calcined body or the powder of the calcined body. There is. _{SiO 2} added as a sintering aid becomes a liquid phase component at the time of firing (sintering), and is present as a component of the grain boundary phase in the ferrite sintered magnet. Therefore, when the above-mentioned amount of SiO ₂ is added as the sintering aid, the obtained ferrite sintered magnet contains Si of 1.5 mass% or less (excluding 0 mass%) in terms of _{SiO 2.} At this time, the content of Si, the general _formula: and the content of each element represented by _{Ca 1-x-x 'R} x A x' Fe 2n-y-z Co y Zn z relatively decreases However, the range of x, x', y, z, n, etc. in the general formula basically does not change. The Si content is the composition (mass%) of Ca, La, Sr, Ba, Fe, Co, Zn and Si in the component analysis result of the ferrite sintered magnet (for example, the result by the ICP emission spectroscopic analyzer). From, _{converted to the mass of CaCO 3} , La (OH) ₃ , SrCO ₃ , BaCO ₃ , Fe ₂ O ₃ , Co ₃ O ₄ , ZnO and SiO ₂ , and the content ratio (mass%) to the total 100 mass of them. is there.

The embodiments of the present disclosure will be described in more detail by way of examples, but the embodiments of the present disclosure are not limited thereto.

Experimental Example 1
As an experimental example based on the embodiment of the present disclosure, the general formula _{Ca 1-x-x 'La} x A x' Fe 2n-y-z Co y Zn z, the A Sr (sample No.1~3,6~ 13) or Ba (Sample No. 14), and the atomic ratio of Sample No. 1 in Table 1 is set. _{CaCO 3} powder, La (OH) ₃ powder, SrCO ₃ powder, BaCO ₃ powder, Fe ₂ O ₃ powder so as to be 1-x-x', x, x', y, z and 2n shown in 1 to 14. , Co ₃ O ₄ powder and Zn O powder are weighed in a predetermined composition, 0.1 mass% of H ₃ BO ₃ powder is added to a total of 100 mass% of the weighed powder, and each is mixed for 4 hours with a wet ball mill. , Dried and sized to obtain 14 kinds of mixed raw material powders.

As a comparative example, _{'in La x Fe 2n-y-z} Co y Zn z, x' the general formula Sr _x, x, y, sample atomic ratio and 2n are in Table 1 z No. As shown in 15 and 16, SrCO ₃ powder, La (OH) ₃ powder, Fe ₂ O ₃ powder, Co ₃ O ₄ powder and ZnO powder are weighed in a predetermined composition, and the total of the weighed powder is 100 mass. After adding 0.1 mass% of H ₃ BO ₃ powder to%, each was mixed with a wet ball mill for 4 hours, and then dried and sized to obtain two kinds of mixed raw material powders.

All 16 kinds of the obtained mixed raw material powders were calcined in the air at the calcining temperature shown in Table 1 for 3 hours to obtain 16 kinds of calcined bodies.

Each of the obtained calcined bodies was roughly pulverized with a small mill to obtain 16 types of coarsely pulverized powders of the calcined bodies. _{CaCO 3} (addition amount is converted to CaO) and SiO ₂ shown in Table 1 are added to 100 mass% of the obtained coarsely pulverized powder of each calcined product, and a wet ball mill using water as a dispersion medium is shown in Table 1. It was finely pulverized to the indicated average particle size (measured by the air permeation method using a powder specific surface area measuring device (SS-100 manufactured by Shimadzu Corporation)) to obtain 16 kinds of finely pulverized slurries.

A magnetic field of about 1 T is applied to each finely pulverized slurry obtained in the pulverization step using a parallel magnetic field forming machine (longitudinal magnetic field forming machine) in which the pressurizing direction and the magnetic field direction are parallel while removing the dispersion medium. However, molding was performed at a pressure of about 2.4 MPa to obtain 16 types of molded products.

Each of the obtained compacts was inserted into a sintering furnace and fired in the air at the firing temperatures shown in Table 1 for 1 hour to obtain 16 types of ferrite sintered magnets. _B r of resultant sintered ferrite _magnet, the measurement result of _{H cJ} and _H k _{/ H cJ} shown in Table 1. In Table 1, sample No. Sample No. not marked with * next to. 1 to 3, 6 to 12, and 14 are experimental examples based on the embodiments of the present disclosure, and the sample Nos. marked with *. Examples 4, 5 and 13 are experimental examples (comparative examples) that do not satisfy the embodiments of the present disclosure, and sample numbers marked with *. Examples 15 and 16 are experimental examples (comparative examples) in which a part of Co is replaced with Zn in a general Sr-La-Co-based sintered magnet. In Table 1, H _{k is 0.95 × J r} (J _r is residual magnetization, J _r = B) in the second quadrant of the J (magnitude of magnetization) −H (strength of magnetic field) curve. It is the value of H at the position where the value of _{r) is obtained.}

The atomic ratio in Table 1 indicates the atomic ratio (blending composition) of the raw material powder at the time of blending. The atomic ratio (composition of the sintered magnet) in the sintered body (ferrite sintered magnet) after firing is based on the atomic ratio at the time of compounding, and additives (H ₃ BO _3, etc.) added before the calcining process. Can be obtained by calculation in consideration of the amount of the _{sintering aid (CaCO 3} and SiO ₂ ) added after the calcining process and before the molding process, and the calculated value is the ferrite sintered magnet. Is basically the same as the result of analysis with an ICP emission spectroscopic analyzer (for example, ICPV-1017 manufactured by Shimadzu Corporation).

As shown in Table 1, Sample No. is an experimental example (comparative example) in which a part of Co is replaced with Zn in a general Sr-La-Co-based sintered magnet. Sample No. 15 and 16 which are experimental examples based on the embodiment of the present disclosure containing the same amount of Co as compared with 15 and 16. 6-12 are excellent in _{H cJ} yet approximately equal _{B r,} and the use of Co compared with the general Sr-La-Co-based sintered magnet (containing 0.2 about Co atomic ratio) The amount can be reduced by 25% or more. That is, in the embodiment of the present disclosure, in the composition region in which the amount of Co used is reduced by 25% or more with respect to a general Sr-La-Co-based sintered magnet (containing Co in an atomic ratio of about 0.2). ferrite sintered magnets (Ca-La-Co based sintered magnet) based, compared to the general Sr-La-Co based sintered magnet has a high _{B r} and a high _{H cJ.}

Further, the sample No. which is an experimental example (comparative example) containing no Sr in the Ca-La-Co-based sintered magnet. Sample Nos. 4 and 5, which are experimental examples based on the embodiments of the present disclosure and contain Sr. As is apparent from comparison between 1-3, containing the same amount of Co, even though B _r and H _cJ is almost the same level, La contained according to the experimental example based on the embodiment of the present disclosure It is possible to significantly reduce the amount.

In addition, Sample No. which is an experimental example based on the embodiment of the present disclosure using Ba instead of Sr. It can be seen that No. 14 has substantially the same magnet characteristics as other experimental examples using Sr.

Further, the sample No. which is an experimental example (comparative example) containing no Zn in the Ca-La-Co-based sintered magnet. No. 13 and a sample No. 13 containing Zn, which is an experimental example based on the embodiment of the present disclosure. As is apparent from comparison with 9,10, thereby improving the B _r while suppressing a decrease in H _cJ with the addition of Zn.

Experimental Example 2
Eighteen types of ferrite sintered magnets were obtained in the same manner as in Experimental Example 1. Weighing composition (A is all Sr), calcining temperature, CaCO ₃ (CaO equivalent) and SiO ₂ addition amount at the time of raw material powder mixing step of each sample, average particle size after ball mill, firing temperature, and obtained ferrite firing. _B r of sintered _magnets, the measurement result of _{H cJ} and _H k _{/ H cJ} shown in Table 2. In Table 2, sample No. Sample No. not marked with * next to. 17 to 25 and 27 to 34 are experimental examples based on the embodiments of the present disclosure, and the sample Nos. marked with *. Reference numeral 26 denotes an experimental example (comparative example) that does not satisfy the embodiment of the present disclosure.

As shown in Table 2, almost the same results as in Experimental Example 1 were obtained in Experimental Example 2. Sample No. which is an experimental example (comparative example) that does not satisfy the embodiment of the present disclosure (the content of Sr is too large). In 26, it is seen that the _{B r} and _{H cJ} is reduced together.

According to embodiments of the present disclosure, high B has _r and less decrease in H _cJ is, the Co amount than typical Sr-La-Co ferrite sintered magnet was reduced by 25% or more, further conventional The ferrite sintered magnet in which the amount of La used is reduced as compared with the Ca-La-Co-based ferrite sintered magnet of the above can be suitably used for various motors and the like.

Claims (8)

General formula indicating the atomic ratio of metal elements of Ca, R, A, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La, and A is Sr and / or Ba): in _{Ca 1-x-x 'R} x A x' Fe 2n-y-z Co y Zn z,
The x, x', y and z, and n (where 2n is a molar ratio and is represented by 2n = (Fe + Co + Zn) / (Ca + R + A)) are
0.1 ≤ x ≤ 0.4,
0 <x'≤ 0.3,
0 <y <0.15,
0 <z <0.15,
1-x-x'> x, and 4.5 ≦ n ≦ 5.5,
Ferrite calcined body that satisfies. The ferrite calcined body according to claim 1, wherein 0.2 ≦ x ≦ 0.3. The ferrite calcined body according to claim 1 or 2, wherein 0.1 ≦ x ′ ≦ 0.3. General formula indicating the atomic ratio of metal elements of Ca, R, A, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La, and A is Sr and / or Ba): in _{Ca 1-x-x 'R} x A x' Fe 2n-y-z Co y Zn z,
The x, x', y and z, and n (where 2n is a molar ratio and is represented by 2n = (Fe + Co + Zn) / (Ca + R + A)) are
0 <x ≦ 0.4,
0 <x'≤ 0.3,
0 <y <0.15,
0 <z <0.15,
1-x-x'> x, and 3.5 ≦ n ≦ 5.5,
Ferrite sintered magnet that satisfies. The ferrite sintered magnet according to claim 4, further containing Si of 1.5 mass% or less (excluding 0 mass%) in terms of SiO _2. General formula indicating the atomic ratio of metal elements of Ca, R, A, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La, and A is Sr and / or Ba): in _{Ca 1-x-x 'R} x A x' Fe 2n-y-z Co y Zn z,
The x, y and z, and n (where 2n is a molar ratio and is represented by 2n = (Fe + Co + Zn) / (Ca + R + A)) are
0.1 ≤ x ≤ 0.4,
0 <x'≤ 0.3,
0 <y <0.15,
0 <z <0.15,
1-x-x'> x, and 4.5 ≦ n ≦ 5.5,
Raw material powder mixing process to obtain a mixed raw material powder by mixing the raw material powders that satisfy the above.
A calcining step of calcining the mixed raw material powder to obtain a calcined body,
A crushing step of crushing the calcined body to obtain powder of the calcined body,
A molding step of molding the powder of the calcined body to obtain a molded body, and a firing step of firing the molded body to obtain a sintered body.
A method for manufacturing a ferrite sintered magnet including. The sixth aspect of claim 6 further includes a step of adding a _{SiO 2 of} 1.5 mass% or less with respect to 100 mass% of the calcined product or the powder of the calcined product to be added after the calcining step and before the molding step. The method for manufacturing a ferrite sintered magnet according to the description. A claim further comprising a step of adding _{CaCO 3} of 1.5 mass% or less in terms of CaO to 100 mass% of the calcined product or the powder of the calcined product to be added after the calcining step and before the molding step. Item 6. The method for producing a ferrite sintered magnet according to Item 6.