JP2021150362A - Ferrite calcined body, ferrite sintered magnet and manufacturing method thereof - Google Patents

Abstract

To provide a ferrite calcined body and a ferrite sintered magnet which have high Br and less decrease in HcJ, and in which the usage amount of Co and La is more reduced than conventional Ca-La-Co ferrite sintered magnets, and a manufacturing method thereof.SOLUTION: In a ferrite calcined body, the atomic ratio of metallic elements of Ca, R, A, Fe, Co and Zn (where, R represents an element which is at least one of rare earth elements and which essentially contains La, and A represents Sr and/or Ba) is represented by general formula: Ca1-x-x'RxAx'Fe2n-y-zCoyZnz where the x, x', y and z, and the n (provided that 2n is a molar ratio and represented as 2n=(Fe+Co+Zn)/(Ca+R+A))satisfy 0.40≤x<0.5, 0<x'≤0.10, 0.20<y<0.30, 0<z<0.05, x<1-x-x', 4.5≤n≤5.5, and 2n-y-z≥10x'+8.5.SELECTED DRAWING: None

Description

The present invention 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 that 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. Due to the aftermath, it is difficult to maintain the product price even for Sr-La-Co-based ferrite sintered magnets with excellent cost performance and Ca-La-Co-based ferrite sintered magnets with even higher magnet characteristics. .. 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, the residual magnetic flux density (hereinafter referred to as " _Br ") can be increased by substituting a part of Co with Zn. It is known to improve (Patent Document 1 and the like).

It has also been proposed to replace a part of Co with Zn in a Ca-La-Co-based ferrite sintered magnet (Patent Documents 2 and 3 and the like).

Japanese Unexamined Patent Publication No. 11-154604 Korean Publication No. 10-2017-0044875 JP-A-2009-246243

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.

Patent Document 2 discloses a Ca-Sr-La-Fe-Co-Zn ferrite sintered magnet, but describes the saturation magnetization (4πIs), the anisotropic magnetic field (HA), and the maximum energy product as magnetic characteristics. although that, the value of _{B r} and _{H cj} is not described.

Patent Document 3 discloses a Ca-A (Sr, Ba) -La-Fe-Co-Zn ferrite sintered magnet, but in the examples, the first fine grinding step and the first fine grinding. A crushing step (hereinafter referred to as "heat treatment regrinding step") consisting of a step of heat-treating the powder obtained by the step and a second fine crushing step of crushing the heat-treated powder again is indispensable. .. Since the heat treatment re-grinding step is an uncommon crushing step that requires a long time (88 hours) of the first fine crushing step and a heat treatment (800 ° C. for 1 hour), it is a general crushing process on a mass production scale. It is not described how much magnet characteristics can be obtained in the process (only once for crushing, about 10 hours).

Embodiments of the present disclosure has a high B _r, less decrease in H _cJ can provide the sintered ferrite magnet was also reduce the amount of Co and La than conventional Ca-La-Co ferrite sintered magnet To enable.

An exemplary, non-limiting ferrite calcined body 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
0.40 ≤ x <0.50,
0 <x'≤ 0.10.
0.20 <y <0.30,
0 <z <0.05,
x <1-x-x',
4.5 ≤ n ≤ 5.5, and 2n-yz ≥ 10x'+ 8.5,
To be satisfied.

In one embodiment, 2ny−z ≧ 10x ′ + 9.0.
In one embodiment, 9.5 ≦ 2 n−z ≦ 10.0.

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
0.30 ≤ x <0.50,
0 <x'≤ 0.10.
0.20 <y <0.30,
0 <z <0.05,
x <1-x-x',
3.5 ≤ n ≤ 5.5, and 2n-yz ≥ 10x'+ 7.0,
To be satisfied.

In one embodiment, 2ny−z ≧ 10x ′ + 7.5.
In one embodiment, 8.0 ≦ 2n−y−z ≦ 10.0.
In certain embodiments, it further contains less than 1.5 mass% of SiO _2.
In certain embodiments, SiO ₂ is contained in an amount of 0.5 to 0.8 mass%.

An exemplary method for producing a ferrite sintered magnet, which is not limited to the present disclosure, is described.
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
0.40 ≤ x <0.50,
0 <x'≤ 0.10.
0.20 <y <0.30,
0 <z <0.05,
x <1-x-x',
4.5 ≤ n ≤ 5.5, and 2n-yz ≥ 10x'+ 8.5,
In the raw material powder mixing step of mixing the raw material powders satisfying the above to obtain the mixed raw material powder,
A calcining step of calcining the mixed raw material powder to obtain a calcined body, and
A crushing step of crushing the calcined body to obtain a powder of the calcined body, and
The molding process of molding the powder of the calcined body to obtain the molded body, and
A firing step of calcining the molded body to obtain a sintered body, and
including.

In one embodiment, 2ny−z ≧ 10x ′ + 9.0.
In one embodiment, 9.5 ≦ 2 n−z ≦ 10.0.

_{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. include.

In a certain embodiment, after the calcining step and before the molding step, 0.5 to 0.8 mass% of SiO ₂ is added to 100 mass% of the calcined product or the powder of the calcined product to be added. Further includes steps.

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.

In a certain embodiment, the average heating rate in the temperature range from 800 ° C. to the firing temperature of the firing step is 600 ° C./hour or more and 1000 ° C./hour or less.

In a certain embodiment, the average temperature lowering rate in the temperature range from the firing temperature of the firing step to 800 ° C. is 1000 ° C./hour or more.

According to embodiments of the present disclosure, high B has _r, less decrease in H _cJ is than typical Ca-La-Co ferrite sintered magnet with reduced amount of Co and La ferrite sintered It becomes possible to provide magnets.

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
0.40 ≤ x <0.50,
0 <x'≤ 0.10.
0.20 <y <0.30,
0 <z <0.05,
x <1-x-x',
4.5 ≤ n ≤ 5.5, and 2n-yz ≥ 10x'+ 8.5,
To be satisfied.

In the ferrite calcined body of the present disclosure, the atomic ratio x (content of R) is 0.40 ≦ x <0.50. When x is less than 0.4 or more than 0.5, a high _Br cannot be obtained. Further, when x is 0.5 or more, the effect of reducing the R content cannot be obtained. R is at least one rare earth element and is an element that essentially contains La. The content of rare earth elements other than La is preferably less than 50% of the total amount of R in terms of molar ratio, and more preferably only R = La.

The atomic ratio x'(content of element A) is 0 <x'≤ 0.10. 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 0.1, a high _Br cannot be obtained.

The atomic ratio 1-x-x'(Ca content) and x (R content) satisfy the relationship of x <1-x-x'. That is, the content of Ca is increased more than the content of R. If the content of R is larger than the content of Ca, for different phase of LaFeO ₃ La is excessively remains, it is impossible to obtain a high B _r, also can not be obtained the effect of reducing R content .. 1-x−x ′ is preferably 0.5 or more.

The atomic ratio y (Co content) is 0.20 <y <0.30. If y is 0.30 or more, the effect of reducing the amount of Co used cannot be obtained. When y is 0.20, _{the decrease in H cJ} becomes large, which is not preferable.

The atomic ratio z (Zn content) is 0 <z <0.05. 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 0.05 or more, a high H _cJ cannot be obtained.

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, high _Br cannot be obtained. If n is more than 5.5, high _{B r,} can not be obtained _{H cj.}

The atomic ratio of 2n-yz (Fe content) and x'(content of element A) satisfies the relationship of 2n-yz ≥ 10x' + 8.5. More preferably, the relationship of 2n-yz ≥ 10x'+ 9.0 is satisfied. The Fe content, of less than 10x '+ 8.5, it is impossible to obtain a high _{B r.} The content of Fe can be obtained more preferably from 9.5 ≦ 2n-y-z ≦ 10.0, high _{B r,} the _{H cj.}

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".

"Has a hexagonal magnetoplumbite (M-type) structure" means that when the X-ray diffraction of a ferrite calcined product is measured under general conditions, the X-ray of the hexagonal magnetoplumbite (M-type) structure is used. 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 , m are positive numbers) can be mentioned. Examples of the Zn compound include ZnO.

In order to promote the reaction during 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 and 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, etc. to obtain a hexagonal magnetoplumbite (M-type) -structured ferrite compound by a solid-phase reaction. Form. This process is called "calcination" and the resulting compound is called "calcination".

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 grind in the grind 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 body or the powder of the calcined body (coarsely 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 a Ca-La-Co-based ferrite sintered magnet, firing of SiO ₂ or CaCO ₃ like a general Sr-La-Co-based ferrite sintered magnet 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, more preferably 0.5 to 0.8 mass%, based on 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 addition amount in terms of CaO, the addition amount of CaCO ₃ can be calculated by the formula: ( _{molecular weight of CaCO 3} × addition amount in terms of CaO) / molecular weight of CaO. For example, when 0.5 mass% of CaCO ₃ is added in terms of CaO, {(40.08 [molecular weight of Ca] + 12.01 [molecular weight of C] + 48.00 [molecular weight of O x 3] = 100.09 [ [Molecular weight of CaCO ₃ ]) × 0.5 mass% [Amount added in terms of CaO]} / (40.08 [Molecular weight of Ca] + 16.00 [Molecular 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.

When raising the temperature in the firing step, the average heating rate in the temperature range from 800 ° C. to the firing temperature is set to 600 ° C./hour or more and 1000 ° C./hour or less, and after keeping the firing time in the firing step (when not held). When the temperature is lowered, it is preferable that the average temperature lowering rate in the temperature range from the firing temperature to 800 ° C. is 1000 ° C./hour or more because the lead time can be shortened and the magnet characteristics are further improved. Although these effects can be obtained by adopting only the temperature lowering rate, it is more preferable to adopt both the temperature raising rate and the temperature lowering rate.

At the time of temperature rise, if the average temperature rise rate in the temperature range from 800 ° C. to the firing temperature is less than 600 ° C./hour, the effect of shortening the lead time and improving the magnet characteristics cannot be sufficiently obtained. Even if the average temperature rise rate exceeds 1000 ° C / hour, it is possible to shorten the lead time and improve the magnet characteristics, but depending on the structure and size of the firing furnace, the object to be fired (molded body) It may be difficult for the temperature to follow the temperature inside the furnace (or the set temperature of the firing furnace). Therefore, the upper limit of the average heating rate was set to 1000 ° C./hour. In the embodiment of the present invention, when the temperature is described, it refers to the temperature of the object to be heat-treated. The temperature was measured by bringing an R thermocouple into contact with the object to be heat-treated in the firing furnace.

The temperature rise rate up to 800 ° C. is not particularly limited, but considering the shortening of the lead time, the temperature rise rate similar to the temperature range from 800 ° C. to the firing temperature, that is, room temperature or the temperature inside the furnace (preliminary heating temperature, etc.) ) To the firing temperature, it is desirable that the average temperature rise rate is 600 ° C./hour or more and 1000 ° C./hour or less.

If the average temperature lowering rate in the temperature range from the firing temperature to 800 ° C is less than 1000 ° C / hour when the temperature is lowered after the firing temperature is kept for a predetermined time (including the case without holding), the lead time is shortened and the magnet is used. The effect of improving the characteristics cannot be sufficiently obtained. The temperature lowering rate of 800 ° C. or lower is not particularly limited, but in consideration of shortening the lead time, it is preferable to cool to about room temperature at a temperature lowering rate similar to or close to the temperature range from the firing temperature to 800 ° C.

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 body, 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, 0.4 ≦ x <0.5 ( Calcination body) is 0.3 ≦ x <0.5 (sintered magnet), 4.5 ≦ n ≦ 5.5 (calcination body) is 3.5 ≦ n ≦ 5.5 (sintered magnet) It becomes.

In addition, the relationship between the atomic ratio 2n-yz (Fe content) and x'(A element content) also fluctuates, and 2n-yz ≥ 10x'+ 8.5 (calcination) is 2n-. yz ≥ 10x'+ 7.0 (sintered body), more preferable range 2n-yz ≥ 10x'+ 9.0 (temporary baked body) is 2n-y-z ≥ 10x' + 7.5 (baked body) Calcination). Then, 9.5 ≦ 2n−z ≦ 10.0 (temporary burned body), which is a more preferable range for the Fe content, becomes 8.0 ≦ 2n−yz ≦ 10.0 (sintered body). Become.

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
0.30 ≤ x <0.50,
0 <x'≤ 0.10.
0.20 <y <0.30,
0 <z <0.05,
x <1-x-x',
3.5 ≤ n ≤ 5.5, and 2n-yz ≥ 10x'+ 7.0,
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 product or the powder of the calcined product. 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 _{SiO 2 of 1.5 mass% or less.} At this time, the content of SiO _2, the general _formula: 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 , The range of x, x', y, z, n, etc. in the general formula basically does not change. The content of SiO ₂ 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). ) To _{the masses 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.

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 Nanba1～7,9, 10) or Ba (Sample No. 8), 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 so as to be 1-x-x', x, x', y, z and 2n-y-z shown in 1 to 10. ₂ O ₃ powder, Co ₃ O _{4 powder and Zn O powder are weighed in a predetermined composition, H 3} BO ₃ powder is added in an amount of 0.1 mass% to a total of 100 mass% of the weighed powder, and then 4 in a wet ball mill. After mixing for a time, it was dried and sized to obtain 10 kinds of mixed raw material powders.

As a comparative example, in the general formula _{Ca 1-x La x Fe 2n} -y-z Co y Zn z, 1-x-x', x, y, z, the atomic ratio of 2n-y-z is Table 1 Sample No. _{CaCO 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 so as to be 11 to 14, and based on a total of 100 mass% of the weighed powder. After adding 0.1 mass% of H ₃ BO ₃ powder, each was mixed with a wet ball mill for 4 hours, and then dried and sized to obtain four kinds of mixed raw material powders.

All 14 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 14 kinds of calcined bodies.

Each of the obtained calcined bodies was roughly pulverized with a small mill to obtain 14 kinds 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 14 kinds of finely pulverized slurries.

A magnetic field of about 1 T is applied to each finely pulverized slurry obtained in the pulverization step by 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, it was molded at a pressure of about 2.4 MPa to obtain 14 types of molded products.

Each of the obtained compacts is inserted into a sintering furnace, heated in the air to the firing temperature shown in Table 1 at a heating rate of 1000 ° C./hour, and then fired for 1 hour to generate 40 L / min of air. While feeding, the temperature was lowered from the firing temperature shown in Table 1 to 900 ° C. at 1500 ° C./hour, and then cooled to room temperature over 6 hours to obtain 14 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. Examples 1 to 10 are experimental examples based on the embodiments of the present disclosure, and sample numbers marked with *. 11 to 14 are experimental examples (comparative examples) that do not satisfy the embodiments of the present disclosure. Sample No. marked with * 11 to 14 are experimental examples (comparative examples) in which a part of Co is replaced with Zn in a general Ca-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 Ca-La-Co-based sintered magnet. Compared with 11 to 14, sample No. which is an experimental example in which a part of La was further replaced with Sr. 1～7,9,10 is, _{B r} and _{H cj} has a magnet properties nearly equal level. That is, while _{B r} and _{H cj} is the magnetic properties of the substantially equal levels of Co for general Ca-La-Co ferrite sintered magnet (containing 0.3 about Co atomic ratio) Single The portion can be replaced with Zn to reduce the amount of Co used, and a part of La can be replaced with Sr to reduce the amount of La used.

In addition, sample No. In 1 to 7, 9 and 10, the relationship between the amount of Sr (x') and the amount of Fe (2n-y-z) satisfies 2n-y-z ≥ 10x'+ 7.0, and the relationship between the amount of Sr and the amount of Fe By filling the sample No. It was the magnetic properties of the substantially same level as the 11 to 14 _{B r} and _{H cj.} Furthermore, the sample No. 1, 2, 4 to 7 satisfy 2n−y—z ≧ 10x ′ + 7.5, and by satisfying the relationship between Sr and the amount of Fe, the sample No. 11-14 was the _{B r} and _{H cj} equal or magnetic properties of the.

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. 8 has substantially the same magnet characteristics as other experimental examples using Sr. Further, the relationship between the amount of Ba (x') and the amount of Fe (2n-y-z) also satisfies 2n-y-z ≥ 10x'+ 7.0, and further 2n-y-z, similarly to the relationship between the amount of Sr and the amount of Fe. It can be seen that ≧ 10x'+ 7.5 is satisfied.

According to embodiments of the present disclosure, high B has _r, less decrease in H _cJ is to reduce the use of conventional Ca-La-Co ferrite sintered Co than the magnet and La ferrite calcined body , Ferrite sintered magnets can be suitably used for various motors and the like.

Claims (16)

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
0.40 ≤ x <0.5,
0 <x'≤ 0.10.
0.20 <y <0.30,
0 <z <0.05,
x <1-x-x',
4.5 ≤ n ≤ 5.5, and 2n-yz ≥ 10x'+ 8.5,
Ferrite calcined body that satisfies. The ferrite calcined body according to claim 1, wherein 2ny-z ≥ 10x'+ 9.0. The ferrite calcined body according to claim 1 or 2, wherein 9.5 ≦ 2 n−z ≦ 10.0. 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
0.30 ≤ x <0.5,
0 <x'≤ 0.10.
0.20 <y <0.30,
0 <z <0.05,
x <1-x-x',
3.5 ≤ n ≤ 5.5, and 2n-yz ≥ 10x'+ 7.0,
A ferrite sintered magnet that satisfies. The ferrite sintered magnet according to claim 4, wherein 2ny-z ≥ 10x'+ 7.5. The ferrite sintered magnet according to claim 4 or 5, wherein 8.0 ≦ 2 n−z ≦ 10.0. The ferrite sintered magnet according to any one of claims 4 to 6, further containing _{SiO 2 of} 1.5 mass% or less. The ferrite sintered magnet according to any one of claims 4 to 7, which contains 0.5 to 0.8 mass% 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, x', y and z, and n (where 2n is a molar ratio and is represented by 2n = (Fe + Co + Zn) / (Ca + R + A)) are
0.40 ≤ x <0.5,
0 <x'≤ 0.10.
0.20 <y <0.30,
0 <z <0.05,
x <1-x-x',
4.5 ≤ n ≤ 5.5, and 2n-yz ≥ 10x'+ 8.5,
In the raw material powder mixing step of mixing the raw material powders satisfying the above to obtain the mixed raw material powder,
A calcining step of calcining the mixed raw material powder to obtain a calcined body, and
A crushing step of crushing the calcined body to obtain a powder of the calcined body, and
The molding process of molding the powder of the calcined body to obtain the molded body, and
A firing step of calcining the molded body to obtain a sintered body, and
A method for manufacturing a ferrite sintered magnet including. The method for producing a ferrite sintered magnet according to claim 9, wherein 2ny-z ≥ 10x'+ 9.0. The method for producing a ferrite sintered magnet according to claim 9 or 10, wherein 9.5 ≦ 2 n−z ≦ 10.0. 9. A claim further comprising a step of adding _{1.5 mass% or less of SiO 2} 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 producing a ferrite sintered magnet according to any one of 11 to 11. After the calcining step and before the molding step, the step of adding 0.5 to 0.8 mass% of SiO ₂ with respect to 100 mass% of the calcined product or the powder of the calcined product to be added is further included. The method for producing a ferrite sintered magnet according to any one of claims 9 to 12. _{After the calcining step and before the molding step, the 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 is further included. The method for producing a ferrite sintered magnet according to any one of claims 9 to 13. The ferrite sintering according to any one of claims 9 to 14, wherein the average heating rate in the temperature range from 800 ° C. to the firing temperature in the firing step is 600 ° C./hour or more and 1000 ° C./hour or less. How to make a magnet. The method for producing a ferrite sintered magnet according to claim 15, wherein the average temperature lowering rate in the temperature range from the firing temperature of the firing step to 800 ° C. is 1000 ° C./hour or more.