JP2021153093A - Ferrite preliminarily-baked material powder, ferrite sintered magnet and production method thereof - Google Patents

Abstract

To provide powder of a ferrite preliminarily-baked material which makes it possible to inexpensively offer a ferrite sintered magnet in such a way that the magnet characteristics are hardly worsened, a ferrite sintered magnet and a production method thereof.SOLUTION: Powder of ferrite preliminarily-baked material comprises: Ca, R, and metal elements of Fe, Co and Zn (R is at least one element of rare earth elements, indispensably including La) of which the atomic ratios are given by the general formula, Ca1-xRxFe2n-y-zCoyZnz, where x, y and z, and n (where 2n is a mole ratio, which is represented by 2n=(Fe+Co+Zn)/(Ca+R)) satisfy 0.4<x≤0.5, 0.15≤y≤0.25, 0<z<0.11 and 4.5≤n≤5.5; and as a sintering assistant, SiO2 of more than 0 mass% and no more than 1.0 mass% and CaCO3 of no less than 0 mass% and less than 0.3 mass%. The ferrite preliminarily-baked material powder has an average particle diameter of over 0.6 μm and no larger than 0.9 μm.SELECTED DRAWING: None

Description

The present disclosure relates to a ferrite calcined body powder, 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. Sr-La-Co-based ferrite sintered magnets have an atomic ratio of about 0.2 (Co / Fe = 0.017, that is, about 1.7% of the Fe content), and Ca-La-Co-based ferrite sintered magnets have an atomic ratio of about 0.2. It contains Co in an atomic ratio of about 0.3 (Co / Fe = 0.03, that is, about 3% of the Fe content). The price of Co (Co oxide) is ten to several tens of times that of iron oxide, which is the main raw material for ferrite sintered magnets. Therefore, the Ca-La-Co-based ferrite sintered magnet inevitably increases the raw material cost as compared with the 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.

From Patent Document 1 and the like, the purpose is not to reduce the amount of Co, but 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, "" It is known that "_{Br") is improved.}

Further, from Patent Document 2 and the like, it has been proposed to replace a part of Co with Zn in a Ca-La-Co-based ferrite sintered magnet.

Japanese Unexamined Patent Publication No. 11-154604 Korean Publication No. 10-2017-0044875

However, in order to provide an inexpensive ferrite magnet, a means for not only replacing a part of Co with Zn as in Patent Document 2 but also reducing the deterioration of magnet characteristics and manufacturing at a lower cost is required. There is.

An object of the present disclosure is to provide a ferrite calcined body powder, a ferrite sintered magnet, and a method for producing the same, which can provide a ferrite sintered magnet at a low cost with little deterioration in magnet characteristics.

That is, the ferrite calcined body powder of the present disclosure is
General formula showing the atomic ratio of metal elements of Ca, R, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La): Ca _1-x R _x Fe _2ny in _-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)) are
0.4 <x ≦ 0.5,
0.15 ≤ y ≤ 0.25,
0 <z <0.11, and 4.5 ≦ n ≦ 5.5,
Ca, R, Fe, Co and Zn that satisfy
Sintering aid,
_{SiO 2} with more than 0 mass% and less than 1.0 mass%,
_{CaCO 3 of} 0 mass% or more and less than 0.3 mass%,
Contains,
The average particle size is larger than 0.6 μm and satisfies 0.9 μm or less.

In the ferrite calcined body powder of the present disclosure, _{it is preferable that SiO 2} is 0.4 to 0.7 mass% and CaCO ₃ is 0 mass% or more and less than 0.2 mass%.

In the ferrite calcined body powder of the present disclosure, it is preferable that the average particle size satisfies 0.7 to 0.8 μm.

The ferrite sintered magnet of the present disclosure is
General formula showing the atomic ratio of metal elements of Ca, R, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La): Ca _1-x R _x Fe _2ny in _-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)) are
0.35 <x ≦ 0.5,
0.15 ≤ y ≤ 0.25,
0 <z <0.11, and 4.0 ≤ n ≤ 5.5,
Ca, R, Fe, Co and Zn that satisfy
_{SiO 2} with more than 0 mass% and less than 1.0 mass%,
Contains.

In the ferrite sintered magnet of the present disclosure, SiO ₂ preferably satisfies 0.4 to 0.7 mass%.

The method for manufacturing a ferrite sintered magnet of the present disclosure is as follows.
General formula showing the atomic ratio of metal elements of Ca, R, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La): Ca _1-x R _x Fe _2ny in _-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)) are
0.4 <x ≦ 0.5,
0.15 ≤ y ≤ 0.25,
0 <z <0.11, and 4.5 ≦ n ≦ 5.5,
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 product to obtain a powder of the calcined product having an average particle size of more than 0.6 μm and 0.9 μm or less.
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
After the calcining step and before the molding step, with respect to 100 mass% of the calcined body or the powder of the calcined body to be added.
_{SiO 2} with more than 0 mass% and less than 1.0 mass%,
_{CaCO 3 of} 0 mass% or more and less than 0.3 mass%,
Is further included.

In the method for producing a ferrite sintered magnet of the present disclosure, it is preferable that SiO ₂ is 0.4 to 0.7 mass% and CaCO ₃ is 0 mass% or more and less than 0.2 mass%.

In the method for producing a ferrite sintered magnet of the present disclosure, it is preferable that the average particle size of the powder of the calcined product satisfies 0.7 to 0.8 μm.

According to the present disclosure, it is possible to provide a ferrite calcined body powder, a ferrite sintered magnet, and a method for producing the same, which can provide a ferrite sintered magnet at a low cost with little deterioration in magnet characteristics.

1. 1. Ferrite Calcination Powder The ferrite calcination powder disclosed in this disclosure is:
General formula showing the atomic ratio of metal elements of Ca, R, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La): Ca _1-x R _x Fe _2ny in _-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)) are
0.4 <x ≦ 0.5,
0.15 ≤ y ≤ 0.25,
0 <z <0.11, and 4.5 ≦ n ≦ 5.5,
Ca, R, Fe, Co and Zn that satisfy
Sintering aid,
_{SiO 2} with more than 0 mass% and less than 1.0 mass%,
_{CaCO 3 of} 0 mass% or more and less than 0.3 mass%,
Contains,
The average particle size is larger than 0.6 μm and satisfies 0.9 μm or less.

In the ferrite calcined body powder of the present disclosure, the atomic ratio x (content of R) is 0.4 <x ≦ 0.5. If x is 0.4 or less or more than 0.5, a high _Br 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 50% or less of the total amount of R in terms of molar ratio.

The atomic ratio y (Co content) is 0.15 ≦ y ≦ 0.25. If y exceeds 0.25, the effect of reducing the amount of Co used cannot be obtained. If y is less than 0.15, _{the decrease in H cJ} becomes large, which is not preferable. Further, in the range where y is 0.15 ≦ y ≦ 0.25, the magnet characteristics are almost the same as those of a general Ca-La-Co-based ferrite sintered magnet, and a general Ca-La-Co-based ferrite is used. A ferrite sintered magnet can be obtained in which the amount of Co used is reduced as compared with a sintered magnet (containing Co in an atomic ratio of about 0.3).

The atomic ratio z (Zn content) is 0 <z <0.11. z is 0 can not be obtained (non-containing) the high B _r, z is not preferable because the reduction in comprising the H _cJ 0.11 or greater.

In the above general formula, 2n is a molar ratio and is represented by 2n = (Fe + Co + Zn) / (Ca + R). 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) the general _formula: represented by _{Ca 1-x R x Fe 2n} -y-z Co y Zn z O 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 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 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 the ferrite sintered magnet of the present disclosure, which includes the method for producing the ferrite calcined body powder 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. The compounds of La, 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. 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 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.

The raw material powder satisfying the components and composition of the above-mentioned ferrite calcined body of the present disclosure is 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, or the like 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.

In the crushing step, the calcined body is crushed (coarsely crushed) by a hammer mill or the like and then crushed (finely crushed) by a vibration mill, a jet mill, a ball mill, an attritor or the like to obtain a calcined body powder (finely pulverized powder). The average particle size of the calcined body powder is preferably larger than 0.6 μm and 0.9 μm or less. In 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.

When the average particle size is 0.6 μm or less, not only the crushing time becomes long, but also the dehydration time at the time of press molding in the molding process described later and the press cycle become long, and the process cost becomes high. In addition, since the press cycle is long, the die life during press molding is shortened, and the manufacturing cost is high. Furthermore, since the specific surface area of each crystal grain is relatively large, it is necessary to increase the amount of the sintering aid added in order to promote liquid phase sintering, which increases the material cost. If the average particle size is larger than 0.9 μm, the magnet characteristics may deteriorate. The average particle size is more preferably 0.7 to 0.8 μm.

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 a solid content ratio of 0.2 to 2 mass%. After the wet grinding, the slurry may be concentrated.

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

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 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 is added to the calcined body or the powder of the calcined body (coarsely pulverized powder or finely pulverized powder). As the sintering aid, it is preferable to add only _{SiO 2 or both SiO 2} and CaCO _3. The _{amount of SiO 2} added is more than 0 mass% and preferably 1.0 mass% or less with respect to 100 mass% of the calcined body or the powder of the calcined body to be added. If SiO ₂ is not added, H _cJ will decrease. Further, when it exceeds 1.0 mass%, the amount of the sintering aid used increases and the material cost increases. The _{amount of SiO 2} added is more preferably 0.4 to 0.7 mass%.

The _{amount of CaCO 3} added is preferably 0 mass% or more and less than 0.3 mass% in terms of CaO with respect to 100 mass% of the calcined body or the powder of the calcined body to be added. As is clear from its composition, the ferrite sintered magnet of the present disclosure belongs to the Ca-La-Co-based ferrite sintered magnet, and since Ca is contained as the main phase component, a liquid phase is generated. Therefore, it is not necessary to add _{CaCO 3.} When 0.3 mass% or more is added, the amount of the sintering aid used increases and the material cost increases. The _{amount of CaCO 3} added is more preferably 0 mass% or more and 0.2 mass% or less, and further preferably 0 mass% or more and less than 0.2 mass%.

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 performing 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.

In this 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 0 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 0] = 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 temperature rise rate in the temperature range from room temperature to 1100 ° C. is raised to 600 ° C./hour or more and 1000 ° C./hour or less, and the average temperature rise in the temperature range from 1100 ° C. to the firing temperature. The temperature may be raised at 1 ° C./min or more and 10 ° C./min or less. Further, when the temperature is lowered after the firing time is kept in the firing step (including the case where it is not held), the magnet characteristics are further improved when the average temperature lowering rate in the temperature range from the firing temperature to 800 ° C. is 1000 ° C./hour or more. Therefore, it is preferable. 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 room temperature to 1100 ° C. is less than 600 ° C./hour, the effect of improving the magnet characteristics cannot be sufficiently obtained. It is possible to improve the magnet characteristics even if the average temperature rise rate exceeds 1000 ° C / hour, but depending on the structure and size of the firing furnace, the temperature of the object to be fired (molded body) is the temperature inside the furnace. (Or it may be difficult to keep up with the set temperature of the firing furnace). Therefore, the upper limit of the average heating rate was set to 1000 ° C./hour. Further, when the average speed in the temperature range from 1100 ° C. to the firing temperature is less than 1 ° C./min, the effect of improving the magnet characteristics is obtained, but it takes time, and when it exceeds 10 ° C./min, the effect of improving the magnet characteristics is obtained. It becomes smaller. The average heating rate is more preferably 1 ° C./min or more and 4 ° C./min or less, and even more preferably 1 ° C./min or more and 2 ° C./min or less. 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.

When the temperature is lowered after keeping the firing temperature for a predetermined time (including the case without holding), if the average temperature lowering rate in the temperature range from the firing temperature to 800 ° C. is less than 1000 ° C./hour, 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 When a sintering aid is added, especially when a Ca component (for example, CaCO ₃ ), which is also the main component of the ferrite calcined body, is added as a sintering aid, the entire ferrite sintered magnet has a Ca component. Will increase, so other elements will decrease relatively. For example, in the case using a ferrite calcined body of the present invention, when the addition was when CaCO ₃ converted CaCO ₃ at the upper limit of the present disclosure as a sintering aid, the most variation, 0.4 <x ≦ 0. 5 (calcination) is 0.35 <x≤0.5 (sintered magnet), 4.5≤n≤5.5 (calcination) is 4.0≤n≤5.5 (sintered) It becomes a magnet).

Therefore, the ferrite sintered magnet of the present disclosure is
General formula showing the atomic ratio of metal elements of Ca, R, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La): Ca _1-x R _x Fe _2ny in _-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)) are
0.35 <x ≦ 0.5,
0.15 ≤ y ≤ 0.25,
0 <z <0.11, and 4.0 ≤ n ≤ 5.5,
Ca, R, Fe, Co and Zn that satisfy
_{SiO 2} with more than 0 mass% and less than 1.0 mass%,
Will be satisfied.

The composition of the ferrite sintered magnet of the present invention containing oxygen (O), the main phase constituting the ferrite sintered magnet, the definition of the hexagonal magnetoplumbite (M type) structure, etc. are defined in the ferrite provisional of the present invention. It is the same as the grilled body. Further, as described above, although the range of x and n varies from the ferrite calcined body, the reasons for limiting the atomic ratios x, y and z and the reasons for limiting n are the same as those of the ferrite calcined body. Is omitted.

As described above, in the method for producing a ferrite sintered magnet of the present invention, SiO ₂ may be added as a sintering aid in an amount of 1.0 mass% or less with respect to 100 mass% of the calcined product or the powder of the calcined product. _{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 less than 1.0 mass% of SiO _2. At this time, the content of SiO _2, the general _formula: Ca _1-x but _{R x Fe} content of each element represented by _{2n-y-z Co y Zn} z is to be relatively reduced, the general The range of x, y, z, n, etc. in the equation basically does not change. The content of SiO ₂ is determined from the composition (mass%) of Ca, R, 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). ₃ , La (OH) ₃ , Fe ₂ O ₃ , Co ₃ O ₄ , ZnO and SiO ₂ are converted into masses, and the content ratio (mass%) to a total of 100 mass% thereof.

The present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Experimental Example 1
In the general formula _{Ca 1-x R x Fe 2n} -y-z Co y Zn z, atomic ratio in Table 1 Sample No. _{CaCO 3} powder, La (OH) ₃ powder, Fe ₂ O ₃ powder, Co ₃ O ₄ so that 1-x, x, y, z and 2n-yz are all the same as shown in 1 to 11. The powder and ZnO powder are weighed with a predetermined composition, 0.1 mass% of H ₃ BO ₃ powder is added to a total of 100 mass% of the weighed powder, mixed for 4 hours with a wet ball mill, and then dried and sized. Then, 11 kinds of mixed raw material powders were obtained.

All 11 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 11 kinds of calcined bodies. Then, each of the obtained calcined bodies was roughly pulverized with a small mill to obtain 11 kinds of coarsely pulverized powders of the calcined bodies.

As an experimental example, sample No. _{In Nos. 1 to 6, a wet ball mill in which CaCO 3} (addition amount is converted to CaO) and SiO ₂ shown in Table 1 were added to 100 mass% of the obtained coarsely pulverized powder of each calcined product, and water was used as a dispersion medium. To obtain a finely pulverized slurry. Sample No. Sample Nos. 1 to 4 were finely pulverized until the average particle size (measured by the air permeation method using a powder specific surface area measuring device (SS-100 manufactured by Shimadzu Corporation)) became 0.80 μm. 5 and 6 were finely pulverized until the average particle size became 0.70 μm.

In addition, as a comparative example, sample No. _{In Nos. 7 to 11, a wet ball mill in which CaCO 3} (addition amount is converted to CaO) and SiO ₂ shown in Table 1 were added to 100 mass% of the obtained coarsely pulverized powder of each calcined product, and water was used as a dispersion medium. To obtain a finely pulverized slurry. Sample No. 7 to 11 were finely pulverized until the average particle size became 0.60 μm.

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, molding was performed at a pressure of about 2.4 MPa to obtain 11 types of molded products.

Each of the obtained compacts is inserted into a sintering furnace, heated to 1100 ° C. at a heating rate of 1000 ° C./hour, and raised from 1100 ° C. to the firing temperature shown in Table 1 at 1 ° C./min. After warming, it is fired for 1 hour, and the temperature is lowered from the firing temperature shown in Table 1 to 900 ° C. at 25 ° C./min while sending air of 40 L / min, and then cooled to room temperature over 6 hours to 11 kinds of ferrites. A sintered magnet was obtained. _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 6 are experimental examples based on the embodiments of the present disclosure, and sample Nos. marked with *. 7 to 11 are experimental examples (comparative examples) that do not satisfy the embodiments of the present disclosure. 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).

Sample No. with an average particle size of 0.60 μm, which is a comparative example. Sample Nos. 7 to 11 with magnet characteristics and an average particle size of 0.7 μm, which is an example. Comparing _the magnetic properties of _{5,6, B r,} H _cJ, it can be seen that H k _{/ H} both almost equal to the properties of the _cJ is obtained. In addition, the sample No. of the example having an average particle size of 0.8 μm. 1-4 likewise, _when comparing the Comparative Example and the magnetic _{properties, B} r, H _cJ, it can be seen that H k _{/ H} both almost equal to the properties of the _cJ is obtained.

_{In addition, the amount of CaCO 3} added as a sintering aid was adjusted to the sample No. which is a comparative example. Sample Nos. 7 to 11 and Sample Nos. Comparing 1 to 6, it can be seen that the addition amount of the example is smaller than the addition amount of the comparative example. Furthermore, the sample No. _{It was found that CaCO 3} does not need to be added in 1, 2 and 5.

From this, even if the average particle size is larger than that of the comparative example, the same characteristics as those of the comparative example can be obtained, and the amount of the sintering aid used can be reduced, so that the ferrite sintered magnet can be provided at a lower cost. It turns out that it can be done.

According to the present disclosure, since the deterioration of magnet characteristics is small and the ferrite sintered magnet can be provided at low cost, it can be suitably used for various motors and the like.

Claims (8)

General formula showing the atomic ratio of metal elements of Ca, R, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La): Ca _1-x R _x Fe _2ny in _-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)) are
0.4 <x ≦ 0.5,
0.15 ≤ y ≤ 0.25,
0 <z <0.11, and 4.5 ≦ n ≦ 5.5,
Ca, R, Fe, Co and Zn that satisfy
Sintering aid,
_{SiO 2} with more than 0 mass% and less than 1.0 mass%,
_{CaCO 3 of} 0 mass% or more and less than 0.3 mass%,
Contains,
Ferrite calcined powder having an average particle size of more than 0.6 μm and 0.9 μm or less. SiO ₂ is 0.4 to 0.7 mass%,
The ferrite calcined body powder according to claim 2, wherein CaCO ₃ is 0 mass% or more and less than 0.2 mass%. The ferrite calcined body powder according to claim 1 or 2, wherein the average particle size is 0.7 to 0.8 μm. General formula showing the atomic ratio of metal elements of Ca, R, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La): Ca _1-x R _x Fe _2ny in _-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)) are
0.35 <x ≦ 0.5,
0.15 ≤ y ≤ 0.25,
0 <z <0.11, and 4.0 ≤ n ≤ 5.5,
Ca, R, Fe, Co and Zn that satisfy
_{SiO 2} with more than 0 mass% and less than 1.0 mass%,
Ferrite sintered magnet containing. The ferrite sintered magnet according to claim 4, wherein SiO _{2 is 0.4 to 0.7 mass%.} General formula showing the atomic ratio of metal elements of Ca, R, Fe, Co and Zn (where R is at least one of rare earth elements and essentially contains La): Ca _1-x R _x Fe _2ny in _-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)) are
0.4 <x ≦ 0.5,
0.15 ≤ y ≤ 0.25,
0 <z <0.11, and 4.5 ≦ n ≦ 5.5,
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 product to obtain a powder of the calcined product having an average particle size of more than 0.6 μm and 0.9 μm or less.
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
After the calcining step and before the molding step, with respect to 100 mass% of the calcined body or the powder of the calcined body to be added.
_{SiO 2} with more than 0 mass% and less than 1.0 mass%,
_{CaCO 3 of} 0 mass% or more and less than 0.3 mass%,
A method for manufacturing a ferrite sintered magnet, which further comprises a step of adding a ferrite magnet. SiO ₂ is 0.4 to 0.7 mass%,
The method for producing a ferrite sintered magnet according to claim 6, wherein _{CaCO 3 is 0 mass% or more and less than 0.2 mass%.} The method for producing a ferrite sintered magnet according to claim 6 or 7, wherein the powder of the calcined product has an average particle size of 0.7 to 0.8 μm.