HK1091803B - Ferrite sintered magnet - Google Patents

Description

Ferrite sintered magnet

Technical Field

The present invention relates to a hard ferrite material, and more particularly to a ferrite magnetic material which can be suitably used for a hexagonal W-type ferrite magnet.

Background

Previously, SrO.6Fe₂O₃A typical magnetic Plumbite (magnetic-Plumbite) type hexagonal ferrite, i.e., M-type ferrite, has become the mainstream of ferrite sintered magnets. In the M-type ferrite magnet, attention is paid to making the ferrite crystal grain size close to the single domain grain size, keeping the ferrite crystal grains uniform in the magnetic anisotropy direction, and increasing the density of the sintered body, and efforts for improving the performance have been continued. As a result of this effort, the properties of the M-type ferrite magnet approach the upper limit thereof, and efforts to improve the magnetic properties at a rapid rate are being made.

As a ferrite magnet that may exhibit magnetic characteristics superior to those of the M-type ferrite magnet, a W-type ferrite magnet is known. The saturation magnetization (4 pi Is) of the W-type ferrite magnet Is about 10% higher than that of the M-type ferrite magnet, and the degree of anisotropic magnetic field Is the same. Japanese patent application laid-open No. 2000-501893 discloses a W-type ferrite magnet having a composition formula of SrO.2 (FeO). n (Fe)₂O₃) And a composition satisfying the condition that n is 7.2 to 7.7, wherein the average grain size of the sintered body is 2 [ mu ] m or less, (BH)_maxIs 5MGOe or more. It is described that the W-type ferrite magnet is produced by 1) mixing SrCO at a predetermined molar ratio₃And Fe₂O₃(ii) a 2) Adding C into the raw material powder; 3) pre-burning; 4) after pre-burning, adding CaO, SiO and C respectively; 5) pulverizing into particles with average particle diameter of 0.06 μm or less; 6) shaping the obtained pulverized powder in a magnetic field and 7) sintering in a non-oxidizing atmosphere.

Japanese unexamined patent publication No. 11-251127 discloses a ferrite magnet characterized in that: has a maximum energy product exceeding that of conventional M-type ferrite, andin the conventional W-type ferrite magnet having a different composition, the basic composition was MO. xFeO. (y-x/2) Fe in terms of atomic ratio₂O₃(M is 1, 2 or more of Ba, Sr, Pb and La), 1.7-2.1 of x, 8.8-9.3 of y.

Patent document 1: japanese patent application laid-open No. 2000-501893

Patent document 2: japanese unexamined patent publication No. 11-251127

However, the W-type ferrite magnet is manufactured by adding subcomponents other than the basic composition (main composition). This subcomponent is an important element for a W-type ferrite magnet to be added for the purpose of improving sinterability and the like. In Japanese patent application laid-open Nos. 2000-501893 and 11-251127, CaCO is typically used₃(or CaO) and SiO₂However, studies on other components of the W-type ferrite magnet have not been sufficiently made.

Disclosure of Invention

Accordingly, an object of the present invention is to: a ferrite magnetic material having a W-type main phase with improved magnetic properties is provided by optimizing the added subcomponents.

Further, various studies as described above have been made on the W-type ferrite magnet, and it is required to obtain higher magnetic characteristics. In particular, it is important to obtain a value of coercive force 3000Oe or more for practical use of W-type ferrite. In this case, of course, the decrease in residual magnetic flux density must be avoided. That is, it is essential to put the W-type ferrite into practical use because the ferrite has both coercive force and residual magnetic flux density at a high level.

The present invention aims to improve the magnetic properties of W-type ferrite, particularly the coercive force.

The present inventors have found that: CaCO is added in a predetermined amount₃(or CaO) and/or SiO₂Further contains, as subcomponents, predetermined amounts of Al component, W component, Ce component, Mo component and Ga componentWhen at least 1 or more of the components are added, only CaCO can be added₃(or CaO) and/or SiO₂High magnetic characteristics cannot be obtained in the case of (2).

The present invention is a ferrite magnetic material based on the above findings, characterized in that: containing as a constituent AFe²⁺ _aFe³⁺ _bO₂₇(wherein A is at least 1 element selected from Sr, Ba and Pb, and 1.5. ltoreq. a.ltoreq.2.1, 12.9. ltoreq. b.ltoreq.16.3) and a Ca component (CaCO)₃0.3 to 3.0 wt% in terms of SiO) and/or a Si component₂0.2 to 1.4 wt% in terms of) as the 1 st subcomponent and contains an Al component (in terms of Al)₂O₃0.01 to 1.5 wt% in terms of WO) and a W component₃0.01 to 0.6 wt% in terms of CeO), and a Ce component (in terms of CeO)₂0.001 to 0.6 wt% in terms of MoO), and Mo component₃0.001 to 0.16 wt% in terms of Ga) and a Ga component (in terms of Ga)₂O₃0.001 to 15 wt% in terms) as a second subcomponent 2.

According to the ferrite magnetic material of the present invention, the coercive force (HcJ) of 3kOe or more and the residual magnetic flux density (Br) of 4.0kG or more can be compatible by optimizing the composition of the main component and the subcomponent.

The ferrite magnetic material according to the present invention can be used in various ways. Specifically, the ferrite magnetic material according to the present invention can be suitably used for ferrite sintered magnets. When the sintered body is used for a ferrite sintered magnet, the sintered body preferably has an average particle diameter of 0.8 μm or less, more preferably 0.6 μm or less. The ferrite magnetic material according to the present invention can be suitably used for ferrite magnet powder. The ferrite magnet powder can be used for bonded magnets. That is, according to the ferrite magnetic material of the present invention, it can be used as ferrite magnet powder dispersed in a resin to constitute a bonded magnet. Furthermore, according to the ferrite magnetic material of the present invention, the magnetic recording medium can be constituted as a film-like magnetic phase.

According to the ferrite magnetic material of the present invention, hexagonal W-type ferrite (W phase) is preferable to constitute the main phase. In the present invention, the W phase is referred to as the main phase when the molar ratio of the W phase is 50% or more. From the viewpoint of magnetic properties, the molar ratio of the W phase may be 70% or more, preferably 80% or more, and more preferably 90% or more. The molar ratio in the present application is calculated by mixing powder samples of W-type ferrite, M-type ferrite, hematite, spinel, and the like at a predetermined ratio and comparing the X-ray diffraction intensities thereof (the same applies to the examples described later).

The present inventors have also found that it is effective to contain a predetermined amount of Ga component to improve coercive force while suppressing a decrease in residual magnetic flux density.

That is, the present invention provides a ferrite magnetic material characterized in that: hexagonal W-type ferrite constituting a main phase, Ga₂O₃Contains 15 wt% or less (excluding 0) of Ga component in terms of conversion. By adding Ga₂O₃The coercive force is improved as compared with the state before the addition of the Ga component by adding the Ga component in a conversion of 15 wt% or less (but not 0).

The effect of improving the magnetic properties by containing a predetermined amount of Ga is not only Fe having the above composition₂The above-described effects can be obtained in the case of the W-type ferrite, and the above-described effects can also be obtained in the case of using the ZnW-type ferrite as the main composition. A preferable composition of the ZnW type ferrite is AZn_cFe_dO₂₇(wherein A is at least 1 element selected from Sr, Ba and Pb, and 1.1. ltoreq. c.ltoreq.2.1, 13. ltoreq. d.ltoreq.17).

W-type ferrite has a higher residual magnetic flux density than M-type ferrite, but the content of Ga is set to Ga₂O₃The content of the ferrite is set to 0.02 to 8.0 wt%, and the coercive force can be improved while maintaining a higher residual magnetic flux density than that of M-type ferrite.

In the content of Ga component is Ga₂O₃The coercive force reached a peak value in terms of about 6.0 wt%. Content of Ga component as Ga₂O₃When the amount is 3.0 to 8.0 wt%, both a coercive force of 3800Oe or more and a residual magnetic flux density of 4400G or more can be satisfied.

And the content of Ga component is Ga₂O₃When the amount is 0.02 to 3.0 wt%, the coercive force is improved without any decrease in residual magnetic flux density.

According to the present invention, by optimizing the added subcomponents, it is possible to provide a ferrite magnetic material having W-type as a main phase with improved magnetic characteristics. The ferrite magnetic material can constitute a ferrite sintered magnet, ferrite magnet powder, and a magnetic film of a magnetic recording medium.

Drawings

FIG. 1 is a graph showing the composition and magnetic properties of the magnet produced in example 1-1.

FIG. 2 shows a composition containing SrFe²⁺ _aFe³⁺ _bO₂₇(wherein a is 2.0, b is 12.6 to 16.6) and a coercive force (HcJ) and a residual magnetic flux density (Br).

FIG. 3 shows a composition containing SrFe²⁺ _aFe³⁺ _bO₂₇(wherein a is 1.9 and b is 16.2) in the formula₂Graph of the relationship between the amount and the coercive force (HcJ) and the residual magnetic flux density (Br).

FIG. 4 shows a composition containing SrFe²⁺ _aFe³⁺ _bAl of sintered compact having main composition represented by O27 (in the formula, a is 2.1 and b is 15.8)₂O₃Graph of the relationship between the amount and the coercive force (HcJ) and the residual magnetic flux density (Br).

FIG. 5 is a graph showing the composition and magnetic properties of the magnet produced in example 1-2.

FIG. 6 shows a composition containing SrFe²⁺ _aFe³⁺ _bO₂₇(wherein a is 2.0, b is 12.4 to 16.6) and a coercive force (HcJ) and a residual magnetic flux density (Br).

FIG. 7 shows a composition containing SrFe²⁺ _aFe³⁺ _bO₂₇(wherein a is 1.9 and b is 16.2) in the formula₂Graph of the relationship between the amount and the coercive force (HcJ) and the residual magnetic flux density (Br).

FIG. 8 shows a composition containing SrFe²⁺ _aFe³⁺ _bO₂₇(wherein a is 2.0 and b is 16.0) in the formula)₃Graph of the relationship between the amount and the coercive force (HcJ) and the residual magnetic flux density (Br).

Fig. 9 is a graph showing the composition and magnetic properties of the magnets produced in examples 1 to 3.

FIG. 10 shows a composition containing SrFe²⁺ _aFe³⁺ _bO₂₇(wherein a is 2.0, b is 12.4 to 16.6) and a coercive force (HcJ) and a residual magnetic flux density (Br).

FIG. 11 shows a composition containing SrFe²⁺ _aFe³⁺ _bO₂₇(wherein a is 1.9 and b is 16.2) in the formula₂Graph of the relationship between the amount and the coercive force (HcJ) and the residual magnetic flux density (Br).

FIG. 12 shows a composition containing SrFe²⁺ _aFe³⁺ _bO₂(wherein a is 2.0 and b is 16.0) in the formula)₂Graph of the relationship between the amount and the coercive force (HcJ) and the residual magnetic flux density (Br).

Fig. 13 is a graph showing the composition and magnetic properties of the magnets produced in examples 1 to 4.

FIG. 14 shows a composition containing SrFe²⁺ _aFe³⁺ _bO₂₇(wherein a is 2.0, b is 12.4 to 16.6) and a coercive force (HcJ) and a residual magnetic flux density (Br).

FIG. 15 shows a composition containing SrFe²⁺ _aFe³⁺ _bO₂₇(wherein a is 1.9 and b is 16.2) in the formula₂Graph of the relationship between the amount and the coercive force (HcJ) and the residual magnetic flux density (Br).

FIG. 16 shows a composition containing SrFe²⁺ _aFe³⁺ _bO₂₇(wherein a is 2.1 and b is 15.8) in the formula₃Graph of the relationship between the amount and the coercive force (HcJ) and the residual magnetic flux density (Br).

FIG. 17 is a graph showing the relationship between the amount of addition of subcomponents and the average crystal grain size.

Fig. 18 is a graph showing the magnet composition, magnetic properties, and structure of a comparative example as subcomponents.

FIG. 19 is a graph showing the composition and magnetic properties of the magnets produced in examples 2-1 to 2-4.

FIG. 20 is a graph showing the relationship between the Ga component addition amount and the coercive force (HcJ) in example 2-1.

FIG. 21 is a graph showing the relationship between the amount of Ga component added and the remanence (Br) in example 2-1.

FIG. 22 is a graph showing the relationship between the coercive force (HcJ) and the residual magnetic flux density (Br) in example 2-1.

FIG. 23 is a graph showing the relationship between the Ga component addition amount and the coercive force (HcJ) in example 2-2.

FIG. 24 is a graph showing the relationship between the amount of Ga component added and the remanence (Br) in example 2-2.

FIG. 25 is a graph showing the relationship between the coercive force (HcJ) and the residual magnetic flux density (Br) in example 2-2.

FIG. 26 is a graph showing the relationship between the Ga component addition time and the magnetic properties.

FIG. 27 is a graph showing the relationship between the amount of Ga component added and the coercive force (HcJ) of the sintered bodies obtained in examples 3-1 and 3-2.

FIG. 28 is a graph showing the relationship between the amount of Ga component added and the remanence (Br) of the sintered bodies obtained in examples 3-1 and 3-2.

FIG. 29 is a graph showing the composition and magnetic properties of the magnets produced in examples 4-1 and 4-2.

Fig. 30 is a graph showing magnetic properties when a Ga component and/or an Al component is added to a sintered body having ZnW type main composition.

Detailed Description

The ferrite magnetic material of the present invention was determined to be Fe₂In the case of the W-type ferrite, the main composition thereof is composed of the following composition formula (1).

AFe²⁺ _aFe³⁺ _bO₂₇Formula (1)

In the formula (1), A is at least 1 element selected from Sr, Ba and Pb, and a is more than or equal to 1.5 and less than or equal to 2.1, and b is more than or equal to 12.9 and less than or equal to 16.3. In the formula (1), a and b represent a molar ratio, respectively.

As a, at least 1 of Sr and Ba is preferable; sr is particularly preferable from the viewpoint of magnetic properties.

a is set in the range of 1.5 to 2.1. When a Is less than 1.5, an M phase and Fe phases having a saturation magnetization (4 pi Is) lower than that of the W phase are formed₂O₃The (hematite) phase, the saturation magnetization (4 pi Is) decreases.On the other hand, when a exceeds 2.1, a spinel phase is formed, and the coercive force (HcJ) is lowered. Therefore, a is set in the range of 1.5 to 2.1. The preferable range of a is 1.6 to 2.0, and the more preferable range is 1.6 to 1.9.

b is set in the range of 12.9 to 16.3. When b is less than 12.9, the coercive force (HcJ) is lowered. On the other hand, when b exceeds 16.3, the remanent flux density (Br) decreases. The preferable range of b is 13.5 to 16.2, and the more preferable range is 14.0 to 16.0.

In Fe₂In the W-type ferrite, two elements of Sr and Ba are selected as the a element, and the composition of the following formula (2) is more preferable as the main composition.

Sr_(1-x)Ba_xFe²⁺ _aFe³⁺ _bO₂₇Formula (2)

In the formula, x is more than or equal to 0.03 and less than or equal to 0.80, a is more than or equal to 1.5 and less than or equal to 2.1, and b is more than or equal to 12.9 and less than or equal to 16.3. In the above formula (2), x, a and b represent molar ratios, respectively.

By making 2 atoms of Sr and Ba coexist, magnetic properties, particularly coercive force, can be improved. Although the reason for the increase in the coercive force is not clear, it can be explained as follows: by making Sr and Ba coexist, crystal grains constituting the sintered body become finer, and the finer crystal grains contribute to an improvement in coercive force.

In the above formula (2), x is preferably set in the range of 0.03. ltoreq. x.ltoreq.0.80 in order to obtain an effect of improving the magnetic properties. The reason why a is 1.5. ltoreq. a.ltoreq.2.1 and 12.9. ltoreq. b.ltoreq.16.3 in the above formula (2) is as described above.

When the so-called ZnW type ferrite is used, it is preferable to use a main composition represented by the following composition formula (3).

AZn_cFe_dO₂₇Formula (3)

In formula (3), A is at least 1 element selected from Sr, Ba and Pb, and 1.1. ltoreq. c.ltoreq.2.1, 13. ltoreq. d.ltoreq.17. In the formula (3), c and d each represent a molar ratio.

The preferable range of c representing the Zn ratio is 1.3. ltoreq. c.ltoreq.1.9, and the more preferable range is 1.3. ltoreq. c.ltoreq.1.7. D representing the proportion of Fe is preferably 14. ltoreq. d.ltoreq.16, more preferably 14.5. ltoreq. d.ltoreq.15.5.

In the ZnW-type ferrite, at least 1 of Sr and Ba is preferably selected as the a element.

The ferrite magnetic material of the present invention contains, for example, CaCO derived from the composition represented by the formulae (1), (2) and (3)₃、SiO₂Ca component and/or Si component (b). Further, at least any 1 of the Al component, W component, Ce component, Mo component, and Ga component may be contained. Specifically, as described in examples below, by containing these components, the coercive force (HcJ), the crystal grain size, and the like can be adjusted, and a ferrite sintered magnet having both the coercive force (HcJ) and the residual magnetic flux density (Br) at a high level can be obtained. It is needless to say that the subcomponent No. 2 of the present invention can be contained in combination.

Ca component and Si component as the 1 st subcomponent are CaCO₃、SiO₂Converted into CaCO₃：0.3～3.0wt％、SiO₂：0.2～1.4wt％。

When CaCO is present₃Less than 0.3 wt%, SiO₂Less than 0.2 wt% of CaCO₃And SiO₂The effect of addition of (2) is insufficient. When CaCO is present₃If the content exceeds 3.0 wt%, Ca ferrite which may cause deterioration of magnetic properties may be generated. And when SiO₂When the content exceeds 1.4 wt%, the residual magnetic flux density (Br) tends to decrease. As described above, the amounts of the Ca component and the Si component of the present invention are CaCO₃、SiO₂The conversion is set to CaCO₃：0.3～3.0wt％、SiO₂：0.2～1.4wt％。CaCO₃And SiO₂Each preferably in CaCO₃：0.4～1.5wt％、SiO₂: 0.2 to 1.0 wt%, preferably CaCO₃：0.6～1.2wt％、SiO₂: 0.3 to 0.8 wt% of a solvent.

CaCO when Ga is selected as the second subcomponent 2₃The amount of the surfactant is set to 0 to 3.0 wt%, preferably 0.2 to 1.5 wt%, and more preferably 0.3 to 1.2 wt%.

Next, preferred contents of Al component, W component, Ce component, Mo component, and Ga component, which are the 2 nd subcomponent, will be described.

Al component is Al₂O₃Containing Al only in conversion₂O₃: 0.01 to 1.5 wt%. When Al is present₂O₃If the amount is less than 0.01 wt%, the effect of addition is insufficient. And, when Al₂O₃When the amount exceeds 1.5 wt%, it is difficult to use the W phase as a main phase, and the residual magnetic flux density (Br) tends to decrease. As described above, the Al component of the present invention is Al₂O₃Containing Al only in conversion₂O₃: 0.01 to 1.5 wt%. Preferably Al₂O₃The amount of (B) is 0.1 to 0.9 wt%, and Al is more preferable₂O₃The amount of the (B) is 0.1 to 0.5 wt%.

W component is selected from WO₃The conversion only containing WO₃: 0.01 to 0.6 wt%. In WO₃When the amount is less than 0.01 wt%, the addition effect is insufficient; and, in WO₃When the amount exceeds 0.6 wt%, it is difficult to use the W phase as the main phase, and the residual magnetic flux density (Br) tends to decrease. According to the above, the W component of the present invention is represented by WO₃The conversion only containing WO₃：0.01～0.6wt％。WO₃The amount of (B) is preferably 0.1 to 0.6 wt%, WO₃The amount of (B) is more preferably 0.1 to 0.4 wt%.

Ce component is CeO₂Containing only CeO in conversion calculation₂: 0.001 to 0.6 wt%. When CeO is present₂When the content is less than 0.001 wt%, the addition effect is insufficient; and when CeO₂When the amount exceeds 0.6 wt%, it is difficult to use the W phase as the main phase, and the residual magnetic flux density (Br) tends to decrease. As described above, the Ce component of the present invention is CeO₂Containing only CeO in conversion calculation₂：0.001～0.6wt％。CeO₂The amount of (C) is preferably 0.01 to 0.4 wt%, CeO₂The amount of (B) is more preferably 0.01 to 0.3 wt%.

Mo component is MoO₃Conversion only of MoO₃: 0.001 to 0.16 wt%. When MoO₃When the content is less than 0.001 wt%, the addition effect is insufficient; and, when MoO₃When the amount exceeds 0.16 wt%, it is difficult to use the W phase as the main phase, and the residual magnetic flux density (Br) tends to decrease. As described above, the Mo component of the present invention is MoO₃Conversion calculations containing only MoO₃：0.001～0.16wt％。MoO₃The amount of (B) is preferably 0.005 to 0.10 wt%, MoO₃The amount of (B) is more preferably 0.01 to 0.08 wt%.

Ga component is Ga₂O₃Ga is contained in conversion₂O₃: less than or equal to 15 wt% (excluding 0). When Ga is₂O₃When the content exceeds 15 wt%, it is difficult to obtain the effect of improving the coercive force by the addition of the Ga component, and the residual magnetic flux density (Br) tends to be lowered. Therefore, the Ga component of the present invention is Ga₂O₃: less than or equal to 15 wt% (but not including 0). Preferably 0.02 to 10 wt%, and more preferably 0.05 to 10 wt%. In order to obtain the effect of improving the coercive force by the addition of the Ga component, it is preferable to contain 0.001 wt% or more of the Ga component.

And Ga is mixed with₂O₃When the amount of (B) is set to 0.02 to 3.0 wt%, preferably 0.05 to 2.0 wt%, not only the coercive force (HcJ) but also the residual magnetic flux density (Br) can be expected to be improved. Particularly, when a coercive force (HcJ) of 3500Oe or more is to be obtained while maintaining a residual magnetic flux density (Br) of 4500G or more, Ga is used₂O₃The amount of (B) is determined to be 0.02 to 3.0 wt% and is effective.

On the other hand, Ga₂O₃When the amount of (B) is 3.0 to 8.0 wt%, more preferably 4.0 to 7.0 wt%, a remanence (Br) of about 4500G or 4600G or more can be obtained, and 3800Oe or more, further 4000Oe or more can be obtainedA coercive force (HcJ) of 4200Oe or more is preferable.

In addition, Ca component is other than CaCO₃In addition, CaO can be added. The Si component and the Al component may be SiO₂、Al₂O₃And adding other forms. WO can be similarly applied to the W component, Ce component, Mo component and Ga component, respectively₃、CeO₂、MoO₃And Ga₂O₃And adding other forms.

In the present specification, the molar ratio of oxygen is represented as 27 regardless of the composition, and the actual number of moles of oxygen may deviate from the stoichiometric composition ratio 27.

The composition of the ferrite magnetic material of the present invention can be measured by fluorescent X-ray quantitative analysis or the like. In the present invention, a component other than the element a (at least 1 element selected from Sr, Ba, and Pb), Fe, the 1 st subcomponent, and the 2 nd subcomponent is not excluded. For example, in Fe₂In W-type ferrite, Fe²⁺Position or Fe³⁺A portion of the location may also be replaced by other elements; in type ZnW ferrite, Zn position or Fe³⁺A portion of the location may also be replaced by other elements.

As described above, the ferrite magnetic material of the present invention can be used to form any of a sintered ferrite magnet, a ferrite magnet powder, a bonded magnet in which a ferrite magnet powder is dispersed in a resin, a magnetic recording medium as a film-like magnetic phase, and the like.

The sintered ferrite magnet and the bonded magnet according to the present invention are processed into a predetermined shape and used in a wide range of applications as described below. For example, the present invention can be used as an automotive motor for fuel pumps, power windows, ABS (anti-lock brake system), fans, wipers, hydraulic steering devices, active suspension devices, starters, door locks, and electric mirrors. Further, the present invention can be used as motors for OA and AV equipments such as FDD spindle, VTR tape feed roller, VTR rotary head, VTR tape reel, VTR input storage (loading), VTR camera tape feed roller, VTR camera rotary head, VTR camera zoom, VTR camera focusing, recorder, etc., tape feed roller, CD, LD, and MD spindle, CD, LD, and MD input storage, CD, LD, and MD optical pickup, etc. Further, the motor can be used as a motor for household appliances such as an air conditioner compressor, a refrigerator compressor, a motor for driving an electric tool, an electric fan, a microwave oven turntable, a stirrer, a dryer fan, a shaver, and an electric toothbrush. Further, the motor may be used as a motor for FA machines such as a robot shaft, a joint drive, a robot main drive, a machine table drive, and a machine belt drive. As other applications, the present invention can be applied to a motorcycle generator, a speaker, a magnet for an earphone, a magnetron, a magnetic field generator for MRI, a clamp circuit for CD-ROM, a dispenser sensor, an ABS sensor, a fuel level sensor, an electromagnetic stopper, a disconnector, and the like.

When the ferrite magnet of the present invention is used as a bonded magnet, the average particle size is preferably 0.1 to 5 μm. The average particle diameter of the powder for a bonded magnet is more preferably 0.1 to 2 μm, and the average particle diameter is more preferably 0.1 to 1 μm.

In the production of a bonded magnet, ferrite magnet powder is kneaded with various binders such as resin, metal, and rubber, and molded in a magnetic field or not. As the binder, NBR (acrylonitrile-butadiene) rubber, polyvinyl chloride, and polyamide resin are preferable. After the molding, the resultant is hardened to obtain a bonded magnet. Before the ferrite powder and the binder are kneaded, heat treatment described later is preferably performed.

The ferrite magnetic material of the present invention can be used to produce a magnetic recording medium having a magnetic layer. The magnetic layer contains a W-type ferrite phase represented by the above composition formulas (1) to (3). For the formation of the magnetic layer, for example, a vapor deposition method or a sputtering method can be used. When the magnetic layer is formed by sputtering, the ferrite sintered magnet of the present invention can be used as a sputtering target. Examples of the magnetic recording medium include a hard disk, a flexible disk, and a magnetic tape.

Next, a suitable method for producing the ferrite magnetic material of the present invention will be described. The method for manufacturing the ferrite magnetic material comprises the following steps: a blending step, a pre-firing step, a coarse grinding step, a fine grinding step, a magnetic field shaping step, a molded body heat treatment step, and a sintering step. The fine grinding step is divided into a 1 st fine grinding step and a 2 nd fine grinding step, and a powder heat treatment step is performed between the 1 st fine grinding step and the 2 nd fine grinding step. The Ga component may be added before the molding step in the magnetic field, and specifically, may be added in the blending step and/or the fine pulverization step. Further, when the fine grinding step is carried out in 2 stages, the effect of the present invention can be obtained also when the fine grinding is carried out in 1 stage as shown in examples 1-1 and 1-2 described later.

Hereinafter, Fe will be obtained₂The W-type ferrite is mainly explained, and conditions for obtaining the ZnW-type ferrite are appropriately explained.

< preparation Process >

After weighing each raw material, mixing and pulverizing the raw materials for about 1 to 16 hours by a wet grinding mill, a ball mill or the like. As the raw material powder, an oxide or a compound that forms an oxide by sintering can be used. The following description uses SrCO₃Powder, BaCO₃Powder and Fe₂O₃Examples of (hematite) powders, SrCO₃Powder, BaCO₃The powder may be added in the form of an oxide in addition to the carbonate. The same applies to Fe, and Fe can be used₂O₃And (3) adding other compounds. Further, compounds containing Sr, Ba, and Fe may also be used. And, where ZnW type ferrite is to be obtained, except SrCO₃Powder, BaCO₃Powder and Fe₂O₃In addition to the (hematite) powder, ZnO powder was prepared.

In the blending step, Ga may be added₂O₃Powder and CaCO₃Powder and SiO₂And (3) powder. The amounts added are as described above. In the present invention, Cr may be added₂O₃And the like. However, these subcomponents are not added at this stage, but are added to SrCO₃Powder, BaCO₃Powder and Fe₂O₃The powder may be added after the calcination.

The ratio of each raw material can be adjusted to the composition to be finally obtained, but the present invention is not limited to this form. For example, SrCO may also be used₃Powder, BaCO₃Powder and Fe₂O₃Any of the powders is added after the pre-firing and adjusted to the final composition.

< calcination step >

And pre-sintering the mixed powder material obtained in the mixing process at 1100-1400 ℃. By performing this calcination in a non-oxidizing atmosphere such as nitrogen or argon, Fe is formed₂O₃Fe in (hematite) powder³⁺Is reduced to produce Fe²⁺And generating Fe₂A W-type ferrite. However, Fe cannot be sufficiently ensured at this stage if²⁺In addition to the W phase, an M phase or a hematite phase is present. In order to obtain a W single-phase ferrite, it is effective to adjust the oxygen partial pressure. Because if the oxygen partial pressure is reduced, Fe³⁺Is reduced to easily generate Fe²⁺。

On the other hand, when the ZnW-type ferrite is obtained, the calcination may be performed in the air.

In addition, when the subcomponents are added in the blending step, the calcined body may be pulverized into a predetermined particle size to obtain ferrite magnet powder.

< coarse grinding step >

The calcined body is generally in the form of particles, and therefore, it is preferable to coarsely pulverize the same. In the coarse grinding step, the mixture is treated with a vibration mill or the like until the average particle diameter is 0.5to 10 μm. The powder obtained is referred to herein as a coarse powder.

< 1 st Fine grinding Process >

In the first fine grinding step 1, the resulting mixture is ground by wet or dry grinding using an attritor, a ball mill, a jet mill or the like to an average particle size of 0.08 to 0.8. mu.m, preferably 0.1 to 0.4. mu.m, more preferably 0.1 to 0.2. mu.m. The purpose of performing this 1 st fine grinding step is to: in order to eliminate coarse particles and to further improve magnetic properties and to refine the structure after sintering, it is preferable to set the specific surface area (according to the BET method) to 20 to 25m²(ii) a range of/g.

Although depending on the grinding method, when the coarsely ground powder is wet-ground by a ball mill, the coarsely ground powder may be treated for 60 to 100 hours per 200g of the coarsely ground powder.

Ga is added before the 1 st fine grinding step for the purpose of improving coercive force and adjusting grain size₂O₃Powders are preferred. As shown in example 2 described later, when the Ga component is added before the first fine grinding step 1, the effect of improving the coercive force is greater than when the Ga component is added in the blending step or the second fine grinding step 2. Before the 1 st fine pulverization step, Ga is excluded₂O₃CaCO may be added in addition to the powder₃、SiO₂、SrCO₃、BaCO₃And the like.

In example 2 described later, Ga is added before the 1 st fine grinding step₂O₃The powder is referred to as "added at the time of 1 st micro-pulverization".

< powder Heat treatment step >

In the powder heat treatment step, the fine powder obtained in the step 1 of fine grinding is subjected to heat treatment at 600 to 1200 ℃, preferably 700 to 1000 ℃ for 1 second to 100 hours.

The first micro-pulverization (1 st) inevitably produces ultra-fine powder of less than 0.1 μm. If the ultrafine powder is present, there may be a problem in the subsequent forming step in a magnetic field. For example, when the amount of ultrafine powder is large in wet molding, problems such as poor drainage and poor molding may occur. Therefore, in the present embodiment, heat treatment is performed before forming in a magnetic field. That is, the heat treatment is performed for the purpose of: the superfine powder with a particle size of less than 0.1 μm produced in the step 1 of fine grinding is reacted with a fine powder with a particle size of more than that (for example, a fine powder with a particle size of 0.1 to 0.2 μm) to reduce the amount of the superfine powder. The heat treatment reduces the amount of ultrafine powder and improves the moldability.

The heat treatment atmosphere at this time was adjusted to avoid Fe generated in the calcination²⁺Is oxidized into Fe³⁺The heat treatment atmosphere was determined to be a non-oxidizing atmosphere. The non-oxidizing atmosphere in the present invention includes an inert gas atmosphere such as nitrogen gas or Ar gas. The non-oxidizing atmosphere of the present invention is allowed to contain 10 vol% or less of oxygen. If oxygen is contained to such an extent, Fe is maintained at the above-mentioned temperature²⁺Can be of negligible degree.

The oxygen content in the heat treatment atmosphere is 1 vol% or less, and more preferably 0.1 vol% or less. When the ZnW-type ferrite is obtained, the heat treatment atmosphere in this case may be in the air.

< 2 nd Fine grinding step >

In the subsequent 2 nd fine pulverization step, the heat-treated fine powder is pulverized by wet or dry pulverization using an attritor, a ball mill, a jet mill or the like to a particle size of 0.8 μm or less, preferably 0.1 to 0.4 μm, and more preferably 0.1 to 0.2. mu.m. The purpose of the 2 nd fine grinding step is to: the particle size adjustment and necking removal are performed, and the dispersibility of the additive is improved. The specific surface area (according to BET method) is set to 10 to 20m²A range of/g, more preferably 10 to 15m²(ii) a range of/g. When the specific surface area is adjusted to be within this range, the amount of ultrafine particles is very small even if the particles are present, and the moldability is not adversely affected. That is, the molding property was not deteriorated by the 1 st fine grinding step, the powder heat treatment step and the 2 nd fine grinding stepAnd can satisfy the requirement of the refinement of the structure after sintering.

Although depending on the pulverization method, in the case of wet pulverization by a ball mill, the treatment may be carried out for 10 to 40 hours per 200g of the fine powder. If the 2 nd fine grinding step is carried out under the same conditions as those in the 1 st fine grinding step, the ultrafine powder is regenerated and the 1 st fine grinding step has almost obtained the desired particle diameter, so that the grinding conditions in the 2 nd fine grinding step are reduced as compared with those in the 1 st fine grinding step. Here, whether or not the pulverization condition has been reduced is not limited to the pulverization time, and the determination may be made based on the mechanical energy input at the time of pulverization.

Ga may be added before the 2 nd fine grinding step for the purpose of improving coercive force and adjusting grain size₂O₃Powder of other than Ga₂O₃CaCO is added to the powder before the 2 nd fine grinding step₃、SiO₂Or further adding SrCO₃And BaCO₃And the like.

In example 2 described later, Ga is added before the fine grinding step 2₂O₃The powder is referred to as "added at the time of 2 nd micro-pulverization".

In the sintering step, carbon powder exhibiting a reducing effect may be added before the 2 nd fine grinding step. The addition of the carbon powder is effective for generating the W-type ferrite in a nearly single-phase state (or single phase). Here, the amount of carbon powder added (hereinafter referred to as "carbon amount") is set in the range of 0.05 to 0.7 wt% with respect to the raw material powder. By setting the carbon amount in this range, the effect of the reducing agent of the carbon powder in the sintering step described later can be sufficiently exerted, and a high saturation magnetization (σ s) can be obtained as compared with the case where no carbon powder is added. The preferred amount of carbon in the present invention is 0.1 to 0.65 wt%, and the more preferred amount of carbon is 0.15 to 0.6 wt%. As the carbon powder to be added, a well-known carbon powder such as carbon black can be used.

In the present invention, in order to suppress segregation of the added carbon powder in the compact andthe orientation degree during shaping in a magnetic field is increased by adding gluconic acid (or its neutralized salt or its lactone) or the compound of formula C_n(OH)_nH_n+2The polyol is shown.

When gluconic acid is selected as the dispersant, the amount of the dispersant may be 0.05 to 3.0 wt% based on the raw material powder. The kind of the gluconic acid neutralizing salt is not particularly limited, and calcium salt, sodium salt, and the like can be used, but calcium gluconate is preferably added. The amount of calcium gluconate added is preferably 0.1 to 2.5 wt%, more preferably 0.1 to 2.0 wt%, and still more preferably 0.5to 1.8 wt%.

When a polyhydric alcohol is selected and used as the dispersant, the number of carbon atoms n in the above general formula is 4 or more. When the number of carbon atoms n is 3 or less, the effect of suppressing the segregation of the carbon powder is insufficient. The number n of carbon atoms is preferably 4 to 100, more preferably 4 to 30, still more preferably 4 to 20, and most preferably 4 to 12. As the polyol, sorbitol is preferable, and 2 or more kinds of polyols may also be used in combination. In addition to the polyol used in the present invention, a well-known dispersant may be further used.

The above general formula is a general formula in the case where the skeleton is completely chain-linked and does not contain an unsaturated bond. The number of hydroxyl groups and hydrogen atoms of the polyol may be slightly smaller than those represented by the general formula. The general formula is not limited to a saturated bond, and may contain an unsaturated bond. The basic skeleton may be chain or ring type, preferably chain type. The effect of the present invention can be achieved if the number of hydroxyl groups is 50% or more of the number n of carbon atoms, and it is preferable that the number of hydroxyl groups is large, and it is most preferable that the number of hydroxyl groups is equal to the number of carbon atoms. The amount of the polyol added is 0.05 to 5.0 wt%, preferably 0.1 to 3.0 wt%, and more preferably 0.3 to 2.0 wt% based on the added powder. The added polyol is almost completely decomposed and removed in the heat treatment step performed after the magnetic field forming. In the molded body heat treatment step, the polyol remaining without being decomposed and removed is decomposed and removed in the subsequent sintering step.

< Forming Process in magnetic field >

In the magnetic field forming step, either dry forming or wet forming may be used, but wet forming is preferred in order to improve the degree of magnetic alignment. Therefore, the preparation of the wet molding slurry will be described below, followed by the description of the molding step in the magnetic field.

In the case of wet molding, the 2 nd fine pulverization step is carried out in a wet manner, and the obtained slurry is concentrated to prepare a slurry for wet molding. The concentration can be carried out by centrifugal separation, filter press or the like. In this case, the ferrite magnet powder preferably accounts for 30 to 80% of the wet molding slurry.

Next, wet molding slurry was used to perform in-magnetic-field molding. The molding pressure is 0.1 to 0.5ton/cm²About 5to 15kOe in magnetic field. The dispersion medium is not limited to water, and a nonaqueous dispersion medium may be used. When a nonaqueous dispersion medium is used, an organic solvent such as toluene or xylene may be used. When toluene or xylene is used as the nonaqueous dispersion medium, a surfactant such as oleic acid is preferably added.

< molded body Heat treatment step >

In this step, the molded body is subjected to a heat treatment for 1 to 4 hours at a low temperature of 100 to 450 ℃, more preferably 200 to 350 ℃. By performing this heat treatment in the atmosphere, Fe²⁺Is partially oxidized into Fe³⁺. That is, in this step, the Fe is added²⁺To Fe³⁺To some extent, to react Fe²⁺The amount is controlled to a predetermined amount.

When the ZnW-type ferrite is obtained, the molded body heat treatment step is not performed.

< sintering step >

In the subsequent sintering step, the molded body is sintered by holding it at 1100 to 1270 ℃ and preferably 1160 to 1240 ℃ for 0.5to 3 hours. The firing atmosphere is performed in a non-oxidizing atmosphere for the same reason as in the pre-firing step. In this step, the added carbon powder disappears before the 2 nd fine grinding step.

When the ZnW-type ferrite is obtained, the sintering atmosphere may be set to be in the air.

Through the above steps, the W-type ferrite sintered magnet of the present invention can be obtained.

In the W-type ferrite sintered magnet, according to Fe₂The W-type ferrite sintered body can have both a remanence (Br) of 4.0kG or more and a coercive force (HcJ) of 3.0kOe or more in the case of containing the Al component and/or the case of containing the W component. When the component Ce is contained and/or the component Mo is contained, the remanence (Br) of 4.6kG or more and the coercive force (HcJ) of 3.3kOe or more can be compatible. When the Ga component is contained, it is possible to achieve both a remanence (Br) of 4.0kG or more and a coercive force (HcJ) of 3.5kOe or more.

Further, in the W-type ferrite sintered magnet, according to the ZnW-type ferrite sintered magnet containing Ga component, it is possible to obtain a coercive force (HcJ) of 700Oe or more, or 720Oe or more while maintaining a residual magnetic flux density (Br) of 4.5kG or more, or 4.8kG or more without any complicated atmosphere control.

The W-type ferrite sintered magnet obtained by the present invention may be pulverized and used as a ferrite magnet powder. The ferrite magnet powder can be used for bonded magnets.

The above description has been made of the method for producing a ferrite sintered magnet, and the same steps can be suitably employed also in the case of producing ferrite magnet powder. The ferrite magnet powder according to the present invention can be produced by 2 processes, i.e., the case of producing the ferrite magnet powder from a calcined body and the case of producing the ferrite magnet powder from a sintered body.

In the case of production from a calcined body, the 1 st subcomponent (Ca component, Si component) and the 2 nd subcomponent (Al component, Ce component, Mo component, and Ga component) are added before the calcination step. The calcined body to which these components are added is subjected to coarse grinding, powder heat treatment, and fine grinding to obtain ferrite magnet powder. The ferrite magnet powder can be used as a ferrite magnet powder after the above-described heat treatment. For example, a ferrite magnet powder subjected to a powder heat treatment is used to produce a bonded magnet. The ferrite magnet powder can be used not only for a bonded magnet but also for the production of a ferrite sintered magnet. Therefore, in the process of manufacturing a ferrite sintered magnet, ferrite magnet powder can also be manufactured. However, the particle size may be different between the case of using the sintered ferrite magnet and the case of using the sintered ferrite magnet.

When ferrite magnet powder is produced from a ferrite sintered magnet, the 1 st subcomponent (Ca component, Si component) and the 2 nd subcomponent (Al component, Ce component, Mo component, and Ga component) may be added at any stage before the sintering step. The ferrite sintered magnet obtained in the above-described step can be suitably pulverized to prepare a ferrite magnet powder.

As described above, the ferrite magnet powder includes a calcined powder, a powder pulverized after calcination and sintering, a powder pulverized after calcination and heat-treated, and the like.

Example 1

Specific examples of the present invention are explained below.

Example 1 (examples 1-1, 1-2, 1-3, 1-4, and 1-5)

Example 1-1 is an experimental example in which an Al component was added as a subcomponent, example 1-2 is an experimental example in which a W component was added as a subcomponent, example 1-3 is an experimental example in which a Ce component was added as a subcomponent, and example 1-4 is an experimental example in which a Mo component was added as a subcomponent.

< examples 1 to 1>

The ferrite sintered magnet was produced in the following procedure.

Fe was prepared as a raw material powder₂O₃Powder (1-time particle diameter: 0.3 μm) and SrCO₃Powder (1-order particle diameter: 2 μm). The raw material powders were weighed so that the values of a and b in the above formula (1) finally became the values shown in fig. 1. In the formula (1), Fe²⁺Is generated by burn-in. That is, although a is 0 at the time of blending, Fe was performed in a portion considered to be a after the calcination₂O₃And weighing the powder.

After weighing, mixing and pulverization were carried out in a wet ball mill for 16 hours. Then, the pulverized powder is dried and granulated, and then the product is subjected to N₂Presintering for 1 hour at 1350 ℃ in a gas protective atmosphere to obtain a powdery presintering body. The calcined body was pulverized by a dry vibration mill for 10 minutes to prepare a coarse powder having an average particle size of 1 μm. After weighing, the mixture was pulverized and mixed for 16 hours by a wet ball mill. Mixing and pulverization were carried out in a wet ball mill for 16 hours. Then, the pulverized powder is dried and granulated, and then the product is subjected to N₂Presintering for 1 hour at 1350 ℃ in a gas protective atmosphere to obtain a powdery presintering body. The calcined body was pulverized by a dry vibration mill for 10 minutes to prepare a coarse powder having an average particle size of 1 μm.

Next, CaCO was added to the coarse powder only in the amount shown in FIG. 1₃Powder (1-order particle diameter: 1 μm), SiO₂Powder (1-order particle diameter: 0.01 μm), Al₂O₃The powder (1-time particle diameter: 0.5 μm) was wet-pulverized with a ball mill for 40 hours to obtain a slurry. The amount of the calcined powder in the slurry was 33 wt%. Next, the slurry after completion of the pulverization was concentrated by a centrifugal separator to prepare a slurry for wet molding. The wet molding slurry is molded in a magnetic field. The applied magnetic field (longitudinal magnetic field) was 12kOe (1000kA/m), and the molded body had a cylindrical shape with a diameter of 30mm and a height of 15 mm.

The molded body was subjected to a heat treatment at 250 ℃ for 3 hours in the air, and then N was added₂The temperature rise rate is 5 ℃/min in the atmosphere of gas protectionSintering at high temperature of 1200 ℃ for 1 hour to obtain a sintered body. The composition of the sintered body obtained was measured by SIMULTIX3550, a fluorescent X-ray quantitative analyzer of scientific electric corporation (the same applies to the following examples).

Next, after the upper and lower surfaces of the obtained sintered body were processed, magnetic properties were evaluated by a BH tracer (tracer) applying a maximum magnetic field of 25kOe in the following manner. The results are shown in FIGS. 1 to 4.

As shown in FIGS. 1 and 2, the value of a is 2.0, CaCO₃：1.0wt％、SiO₂: 0.5 wt% and Al₂O₃: in the case of 0.5 wt%, when the b value is less than 13.0, the decrease in coercive force (HcJ) is significant, and when the b value is 16.4 or more, the decrease in residual magnetic flux density (Br) is significant. On the other hand, a coercive force (HcJ) of 3kOe or more and a residual magnetic flux density (Br) of 4.4kG or more can be obtained with a b value in the range of 13.0 to 16.2.

As shown in FIGS. 1 and 3, the values of a and b were 1.9 and 16.2, respectively, and CaCO was added₃: 1.0 wt% and Al₂O₃: 0.3 wt% of SiO₂When the content is less than 0.5 wt%, the coercive force (HcJ) is remarkably decreased; when SiO is present₂When the amount is 1.5 wt% or more, the coercive force (HcJ) and residual magnetic flux density (Br) are remarkably reduced. In contrast, SiO₂In the range of 0.5to 1.0 wt%, a coercive force (HcJ) of 3kOe or more and a residual magnetic flux density (Br) of 4.4kG or more can be obtained.

Next, as shown in FIGS. 1 and 4, the values of a and b were 2.1 and 15.8, respectively, and CaCO was added₃: 1.0 wt% and SiO₂: 0.5 wt%, by adding Al₂O₃The coercive force (HcJ) can be varied. In particular containing only CaCO₃And SiO₂In this case, the coercive force (HcJ) was only increased to about 2.8kOe, while Al was added₂O₃A coercive force (HcJ) exceeding 4kOe can be achieved. However, Al₂O₃When the amount is excessively increased, the decrease in residual magnetic flux density (Br) becomes significant. Therefore, in the present invention, the Al component is Al₂O₃The equivalent is 0.01 to 1.5 wt%. In addition, in Al₂O₃The amount is in the range of 0.1 to 1.5 wt%, and the coercive force (HcJ) of 3kOe or more and the residual magnetic flux density (Br) of 4.4kG or more can be obtained by using the W phase as a main phase.

< examples 1 and 2>

For Fe₂O₃Powder (1-time particle diameter: 0.3 μm) and SrCO₃A calcined body was obtained under the same conditions as in example 1-1, except that the powder (1-order particle diameter: 2 μm) was weighed so that the values of a and b in the above formula (1) were finally set to values shown in FIG. 5, and coarse powder having an average particle diameter of 1 μm was prepared.

CaCO was added to the coarse powder in the amount shown in FIG. 5₃Powder (1-order particle diameter: 1 μm), SiO₂(1-order particle diameter: 0.01 μm), WO₃A sintered body was obtained under the same conditions as in example 1-1 except that (1-order particle diameter: 0.5 μm), and the magnetic properties were evaluated under the same conditions as in example 1-1. The results are shown in fig. 5to 8.

As shown in FIGS. 5 and 6, the value of a is 2.0 and CaCO₃：0.7wt％、SiO₂: 0.45 wt% and WO₃: when the b value is less than 13.2 in the case of 0.1 wt%, the decrease in coercive force (HcJ) is significant; when the b value is 16.4 or more, the decrease in residual magnetic flux density (Br) is significant. In contrast, a coercive force (HcJ) of 3kOe or more and a residual magnetic flux density (Br) of 4.4kG or more can be obtained with a b value in the range of 13.2 to 16.2.

As shown in FIGS. 5 and 7, the values of a and b were 1.9 and 16.2, respectively, and CaCO was added₃: 0.7 wt% and WO₃: 0.1 wt% of SiO₂When the content is less than 0.45 wt%, the coercive force (HcJ) is remarkably decreased; when SiO is present₂When the amount is 1.50 wt% or more, the coercive force (HcJ) and residual magnetic flux density (Br) are remarkably reduced. In contrast, SiO₂In the range of 0.45 to 0.90 wt%, a coercive force (HcJ) of 3kOe or more and a residual magnetic flux density (Br) of 4.4kG or more can be obtained.

Next, as shown in FIGS. 5 and 8, the values of a and b were 2.0 and 16.0, respectively, and CaCO was added₃: 0.7 wt% and SiO₂: 0.45 wt%, by adding WO₃The coercive force (HcJ) can be improved. In particular in the presence of only CaCO₃And SiO₂Only a coercive force (HcJ) of less than 3.0kOe was obtained, but WO was added thereto₃A coercive force (HcJ) exceeding 3kOe can be achieved. However, WO₃When the amount increases, the residual magnetic flux density (Br) decreases significantly. Therefore, in the present invention, the W component is treated with WO₃The amount is set to 0.01 to 0.6 wt%. And, in WO₃The amount is in the range of 0.01 to 0.6 wt%, and a coercive force (HcJ) of 3kOe or more and a residual magnetic flux density (Br) of 4.4kG or more can be obtained.

< examples 1 to 3>

For Fe₂O₃Powder (1-time particle diameter: 0.3 μm) and SrCO₃A calcined body was obtained under the same conditions as in example 1-1, except that the powder (1-order particle diameter: 2 μm) was weighed so that the values of a and b in the above formula (1) finally became the values shown in FIG. 9, and coarse powder having an average particle diameter of 1 μm was prepared.

Subsequently, the coarse powder is finely pulverized. The micro-pulverization was carried out in 2 stages with a ball mill. In the 1 st fine pulverization, 400ml of water was added to 210g of the coarse powder, and the mixture was subjected to 88 hours of treatment. After the 1 st pulverization, the fine powder was heat-treated under a nitrogen atmosphere at 800 ℃ for 1 hour. The rate of temperature increase until the heating holding temperature and the rate of temperature decrease from the heating holding temperature were set to 5 ℃/min. Subsequently, 2 nd micro-pulverization of wet-pulverization was carried out for 25 hours by a ball mill to obtain a slurry for wet molding. Before the second fine grinding, 0.9 wt% of sorbitol (1-time particle diameter: 10 μm) and CaCO were added to the heat-treated fine ground powder in the amounts shown in FIG. 9₃Powder (1-order particle diameter: 1 μm), SiO₂Powder (1-order particle diameter: 0.01 μm), CeO₂Powder (1-time particle diameter: 0.8 μm) was wet-pulverized for 40 hours with a ball mill to obtainTo a slurry (33 wt% of the amount of pre-fired powder in the slurry). Except for these points, a sintered body was obtained under the same conditions as in example 1-1, and magnetic properties were evaluated under the same conditions as in example 1-1. The results are shown in FIGS. 9 to 12.

As shown in FIGS. 9 and 10, the value of a is 2.0, CaCO₃：0.7wt％、SiO₂: 0.6 wt% and CeO₂: when the b value is too low in the case of 0.1 wt%, the decrease in coercive force (HcJ) becomes remarkable; when the value of b is too large, the decrease in residual magnetic flux density (Br) becomes significant. However, when the b value is in the range of 12.9 to 16.3, a coercive force (HcJ) of 3.3kOe or more and a residual magnetic flux density (Br) of 4.6kG or more can be obtained.

As shown in FIGS. 9 and 11, the values of a and b were 1.9 and 16.2, respectively, and CaCO was added₃: 0.7 wt% and CeO₂: 0.1 wt% of SiO₂When the amount of (b) is too small, the decrease in coercive force (HcJ) is significant; and, in SiO₂When the amount of (b) is too large, the coercive force (HcJ) and residual magnetic flux density (Br) are significantly reduced. However, in SiO₂The amount is in the range of 0.2 to 1.4 wt%, and a coercive force (HcJ) of 3.3kOe or more and a residual magnetic flux density (Br) of 4.6kG or more can be obtained.

Next, as shown in FIGS. 9 and 12, the values of a and b were 2.0 and 16.0, respectively, and CaCO was added₃: 0.7 wt% and SiO₂: 0.6 wt%, by adding CeO₂The coercive force (HcJ) can be varied. In particular in CeO₂The amount of the compound is in the range of 0.001 to 0.6 wt%, and a coercive force (HcJ) of 3.3kOe or more and a residual magnetic flux density (Br) of 4.6kG or more can be obtained.

< examples 1 to 4>

For Fe₂O₃Powder (1-time particle diameter: 0.3 μm) and SrCO₃A calcined body was obtained under the same conditions as in example 1-1, except that the powder (1-order particle diameter: 2 μm) was weighed so that the values of a and b in the above formula (1) finally became the values shown in FIG. 13, and coarse powder having an average particle diameter of 1 μm was prepared.

Subsequently, the fine powder was pulverized in 2 steps by a ball mill under the same conditions as in examples 1 to 3. Before the 2 nd micronization, sorbitol 0.9 wt%, CaCO and the like were added in amounts shown in FIG. 13₃Powder (1-order particle diameter: 1 μm), SiO₂Powder (1-order particle diameter: 0.01 μm) and MoO₃A sintered body was obtained under the same conditions as in examples 1 to 3 except that the powder (1-order particle diameter: 0.8 μm) was used, and the magnetic properties were evaluated under the same conditions as in examples 1 to 1. The results are shown in fig. 13 to 16.

As shown in FIGS. 13 and 14, the value of a is 2.0 and CaCO₃：0.7wt％、SiO₂: 0.6 wt% and MoO₃: when the b value is too low in the case of 0.02 wt%, the decrease in coercive force (HcJ) is significant; when the value of b is too large, the decrease in residual magnetic flux density (Br) is significant. However, in the range of b value of 12.9 to 16.3, a coercive force (HcJ) of 3.3kOe or more and a residual magnetic flux density (Br) of 4.6kG or more can be obtained.

As shown in FIGS. 13 and 15, the values of a and b were 1.9 and 16.2, respectively, and CaCO was added₃: 0.7 wt% and MoO₃: 0.02 wt%, SiO₂When the amount of (b) is too small, the decrease in coercive force (HcJ) is significant; and, in SiO₂When the amount of (b) is too large, the coercive force (HcJ) and residual magnetic flux density (Br) are significantly reduced. However, in SiO₂The amount is in the range of 0.2 to 1.4 wt%, and a coercive force (HcJ) of 3.3kOe or more and a residual magnetic flux density (Br) of 4.6kG or more can be obtained.

Next, as shown in FIGS. 13 and 16, the values of a and b were 2.1 and 15.8, respectively, and CaCO was added₃: 0.7 wt% and SiO₂: 0.6 wt%, by adding MoO₃The coercive force (HcJ) can be varied. In particular in MoO₃The amount of the compound is in the range of 0.001 to 0.16 wt%, and a coercive force (HcJ) of 3.3kOe or more and a residual magnetic flux density (Br) of 4.6kG or more can be obtained.

As shown in examples 1-1, 1-2, 1-3 and 1-4, CaCO was added₃、SiO₂And the subcomponent (Al) recommended in the present invention₂O₃、WO₃、CeO₂、MoO₃) By means of special CaCO₃、SiO₂And the subcomponent and a and b in the composition formula (1) can have both coercive force (HcJ) and residual magnetic flux density (Br) at a high level.

< examples 1 to 5>

Make it contain the accessory ingredient (Al) recommended by the invention₂O₃、WO₃、CeO₂、MoO₃) Except for this, sintered bodies were produced under the same conditions as in examples 1 to 3, and magnetic properties were evaluated under the same conditions as in example 1 to 1. The results are shown in fig. 13.

As shown in FIG. 13, Al is added₂O₃、WO₃、CeO₂、MoO₃When they are added in combination in various combinations, they can achieve both coercive force (HcJ) and residual magnetic flux density (Br) at high levels.

The constituent phases of the sintered bodies having the compositions shown in fig. 1, 5, 9, and 13 were observed by X-ray diffraction. The results are shown in fig. 1, 5, 9 and 13.

As shown in FIG. 1, in Al₂O₃The W phase was 70% or more in terms of molar ratio until 1.5 wt% was reached. And, in Al₂O₃When the content is 2.0 wt% or more, the M phase and the spinel phase (shown as "S phase" in FIG. 1) are contained, and even if the W phase is contained, the molar ratio is less than 70%.

As shown in fig. 5 and 9, for WO₃And CeO₂The W phase is 70% or more in terms of molar ratio until the amount added reaches 0.5 wt%. In WO₃At 0.7 wt% or more, the hematite phase (represented as "H" phase in FIG. 5) or the M phase is contained, and even if the W phase is contained, the molar ratio is less than 70%.

As shown in FIG. 13, in MoO₃Until the molar ratio of the W phase reached 0.15 wt%, the molar ratio was 70% or less. In MoO₃At 0.20 wt%, the hematite phase (indicated as "H" phase in FIG. 13) is contained, and even if the W phase is contained, the molar ratio is less than 70%.

In addition, the conditions of X-ray diffraction are as follows:

an X-ray generation device: 3kW, tube voltage: 45kV, tube current: 40mA

Sampling width: 0.02deg, scanning speed: 4.00deg/min

Divergent slit: 1.00deg, scattering slit: 1.00deg

Light receiving slit: 0.30mm

The average crystal grain size of the obtained sintered body was measured for the composition shown in fig. 17. The results are shown in FIG. 17. As shown in fig. 17, the addition amount of the subcomponent is related to the average crystal grain diameter, and the average crystal grain diameter is changed by changing the addition amount. Subcomponent (Al) recommended in the present invention₂O₃、WO₃、CeO₂、MoO₃) When the amount of (B) is within the range of the present invention, fine crystal grains having an average crystal grain diameter of 0.8 μm or less, further 0.6 μm or less can be prepared. The surface a (including the a-axis and the c-axis) of the sintered body was mirror-polished, acid-etched, and an SEM (scanning electron microscope) photograph was taken to identify each particle, and the maximum diameter passing through the center of gravity of the particle was determined by image analysis and used as the grain size of the sintered body. Then, about 100 crystal grains were measured for each 1 sample, and the average of the crystal grain diameters of all the measured grains was taken as the average crystal grain diameter.

< comparative example >

When a sintered body having the composition shown in fig. 18 is produced and the magnetic properties are measured, it is possible to achieve both a coercive force (HcJ) of 3kOe or more and a residual magnetic flux density (Br) of 4.4kG or more.

As described above, according to the present invention, a ferrite magnetic material having an optimum composition in consideration of subcomponents can be obtained, which can achieve both a coercive force (HcJ) and a residual magnetic flux density (Br) at a high level.

Example 2

Example 2 (example 2-1, example 2-2, example 2-3, and example 2-4)

Examples 2-1, 2-2 and 2-3 are experimental examples in which Sr and Ba were selected as the A element and Ga was added as the subcomponent. CaCO was added in example 2-1 during the preparation of the raw material powder₃Powder, without CaCO addition in example 2-2₃And (3) powder. In examples 2 to 3, Sr was selected as the element A, and the relationship between the b value of the above formula (1) and the magnetic properties was observed. Examples 2 to 4 are experimental examples in which Sr and Ba were selected as the A element and the Ga component and the Al component were added in combination.

< example 2-1>

First, Fe was prepared as a raw material powder₂O₃Powder (1-order particle diameter: 0.3 μm), SrCO₃Powder (1-order particle diameter: 2 μm) and BaCO₃Powder (1-time particle diameter: 0.05. mu.m). The raw material powders were weighed so as to have a blending composition as shown in FIG. 19, and 0.33 wt% of CaCO was added₃A calcined body was obtained under the same conditions as in example 1-1 except that the powder (1-order particle diameter: 1 μm) was mixed and pulverized with a wet mill for 2 hours under the same calcination conditions as 1300 ℃ for 1 hour, and a coarse powder having an average particle diameter of 1 μm was prepared.

Subsequently, the types and amounts of subcomponents were finely pulverized in 2 steps by a ball mill under the same conditions as in examples 1 to 3 except that the subcomponents were set as follows. In the 2 nd fine pulverization, SiO was added to each of the fine pulverized powders subjected to the above-mentioned heat treatment₂0.6 wt% of powder (1-time particle diameter: 0.01 μm), CaCO₃0.35 wt% of powder (1-time particle diameter: 1 μm), SrCO₃0.7 wt% of powder (1-order particle diameter: 2 μm), BaCO₃1.4 wt% of powder (1-order particle diameter: 0.05 μm) and carbon powder (1-order particle diameter: 0.05 μm)m)0.4 wt%, while adding sorbitol as a polyol (1-time particle diameter: 10 μm)1.2 wt%. In addition thereto Ga is added₂O₃0 to 16.0 wt% of a powder (1-order particle diameter: 2 μm).

The slurry obtained by the 2 nd fine grinding was molded in a magnetic field under the same conditions as in example 1-1, and the molded body obtained was subjected to a heat treatment at 300 ℃ for 3 hours in the air, and then sintered at a temperature rise rate of 5 ℃/min at a maximum temperature of 1190 ℃ for 1 hour in a nitrogen atmosphere to obtain a sintered body.

Then, the obtained sintered body was processed under the same conditions as in example 1-1, and the magnetic properties were evaluated under the same conditions as in example 1-1. The result was mixed with the amount of Ga component (Ga)₂O₃The amount of addition) are shown in fig. 19 to 21 in correspondence with each other.

Fig. 20 shows the relationship between the Ga component addition amount and the coercive force (HcJ), and fig. 21 shows the relationship between the Ga component addition amount and the remanence (Br). FIG. 22 shows the relationship between coercive force (HcJ) and residual magnetic flux density (Br) for a sample containing 0 to 6.0 wt% of Ga.

As shown in FIG. 20, it is found that the coercive force (HcJ) is improved by adding Ga. However, the effect of improving the coercive force by the addition of the Ga component has a peak, and when the amount of the Ga component added is 16.0 wt%, the coercive force (HcJ) is equivalent to that when the Ga component is not added.

When the amount of the Ga component added is 16.0 wt%, the remanence (Br) is reduced to less than 3800G, and when the Ga component is contained in a range of 15 wt% or less (not including 0), a high remanence (Br) of 4000G or more, and further 4500G or more is obtained, as shown in fig. 21.

From the above results, in the present invention, the amount of the Ga component added was determined to be 15 wt% or less (but 0 is not included). By containing the Ga component in a range of 15 wt% or less (excluding 0), the coercive force (HcJ) of 3500Oe or more and the residual magnetic flux density (Br) of 4000G or more can be satisfied. Further, by containing the Ga component in the range of 0.1 to 8.0 wt%, the coercive force (HcJ) of 3500Oe or more and the residual magnetic flux density (Br) of 4500G or more can be compatible.

Next, the average crystal grain size of the sintered body was measured for samples not containing Ga and samples containing Ga in an amount of 2.0 wt%, 4.0 wt%, and 7.0 wt%. The results are shown in FIG. 19. The measurement conditions of the average crystal grain diameter are as described above.

As can be seen from fig. 19, the average crystal grain size of the sample containing Ga component is finer than that of the sample containing no Ga component, and the higher the coercivity (HcJ) is obtained as the average crystal grain size is finer.

< examples 2 to 2>

During the compounding, CaCO is not added₃Powder of Ga in 2 nd micro-pulverization₂O₃The powder (1-order particle diameter: 2 μm) is added in an amount of 0 to 8.0 wt%, and further, Ga₂O₃A sintered body was produced under the same conditions as in example 2-1, except that the type and amount of the additive used in the 2 nd fine pulverization except for the powder were set as follows.

SiO₂Powder (1-order particle diameter: 0.01 μm): 0.6 wt%

CaCO₃Powder (1-order particle diameter: 1 μm): 0.7 wt%

SrCO₃Powder (1-order particle diameter: 2 μm): 0.35 wt%

BaCO₃Powder (1-order particle diameter: 0.05 μm): 1.4 wt.%

Carbon powder (1-order particle diameter: 0.05 μm): 0.4 wt%

Sorbitol (1-order particle diameter: 10 μm): 1.2 wt.%

The obtained sample was subjected to composition analysis in the same manner as in example 2-1, while measuring the coercive force (HcJ) and the residual magnetic flux density (Br) in the same manner as in example 2-1. The results are shown in FIG. 19. With respect to the samples obtained in example 2-2, the relationship between the amount of Ga component added and the coercive force (HcJ) is shown in fig. 23, the relationship between the amount of Ga component added and the remanent flux density (Br) is shown in fig. 24, and the relationship between the coercive force (HcJ) and the remanent flux density (Br) is shown in fig. 25. In FIG. 25, the values indicated in the vicinity of the points are the amounts of Ga components added.

As can be seen from fig. 23 to 25, example 2-2 also had the same tendency as example 2-1. Further, as is clear from FIGS. 23 to 24, when the amount of Ga added is in the range of 0.02 to 3.0 wt%, the coercive force (HcJ) is improved without causing any decrease in residual magnetic flux density (Br).

< examples 2 to 3>

A sintered body was produced under the same conditions as in example 2-1, except that Sr was selected as the element a and weighed so that b in the above formula (1) reached the value of fig. 19. The obtained sample was subjected to composition analysis in the same manner as in example 2-1, while measuring the coercive force (HcJ) and the residual magnetic flux density (Br) in the same manner as in example 2-1. The results are shown in FIG. 19.

As can be seen from FIG. 19, when b is in the range of 12.9 to 16.3, the coercive force (HcJ) of 3400Oe or more and the residual magnetic flux density (Br) of 4000G or more can be both satisfied.

< examples 2 to 4>

A sintered body was produced under the same conditions as in example 1-3 except that Sr and Ba were selected as the A elements and Ga and Al were added in combination, and the magnetic properties were evaluated under the same conditions as in example 2-1. The results are shown in FIG. 19. Al used as Al component₂O₃The powder had a 1 st particle diameter of 0.5. mu.m.

As shown in fig. 19, even when the Ga component and the Al component are added in combination, the coercive force (HcJ) and the residual magnetic flux density (Br) can be satisfied at a high level.

The phase states of the sintered bodies obtained in examples 2-1, 2-2, 2-3 and 2-4 were examined by X-ray diffraction. As a result, it was confirmed that all the sintered bodies contained the M phase, but the molar ratio was about 5to 20%, and the W main phase. The X-ray diffraction conditions were the same as in example 1.

Example 3

Example 3 (example 3-1, example 3-2, and example 3-3)

In example 3, the Ga component addition time was set as follows, and the relationship between the Ga component addition time and the magnetic properties was confirmed.

Example 3-1: ga is added to the raw material powder.

Example 3-2: in the 2 nd micro-pulverization, Ga component is added.

Examples 3 to 3: in the 1 st micro-pulverization, Ga component is added.

< example 3-1>

Ga is added during the compounding₂O₃2.0 to 6.0 wt% of powder (1 st particle diameter: 2 μm), and SiO is added during the 2 nd fine grinding₂0.6 wt% of powder (1-time particle diameter: 0.01 μm), CaCO₃0.7 wt% of powder (1-time particle diameter: 1 μm), SrCO₃0.35 wt% of powder (1-order particle diameter: 2 μm), BaCO₃A sintered body was produced under the same conditions as in example 2-1 except that 1.4 wt% of the powder (1 st particle diameter: 0.05 μm) and 0.4 wt% of the carbon powder (1 st particle diameter: 0.05 μm) were used.

< examples 3 and 2>

Ga is mixed with₂O₃A sintered body was produced under the same conditions as in example 3-1, except that the addition time of the powder (1 st particle diameter: 2 μm) was set to 2 nd fine pulverization.

The coercive force (HcJ) and residual magnetic flux density (Br) of the sintered bodies obtained in examples 3-1 and 3-2 were measured under the same conditions as in example 1. The results are shown in fig. 26 to 28, respectively. Then, composition analysis was performed in the same manner as in example 1. The results are shown in fig. 26.

As shown in fig. 27, the effect of improving the coercive force by the addition of the Ga component was confirmed both when the Ga component was added at the time of blending and when the Ga component was added at the time of fine pulverization, but a high coercive force (HcJ) was obtained when the Ga component was added at the time of fine pulverization.

As shown in fig. 28, the remanence (Br) showed a higher value when Ga component was added during the micro-pulverization than when Ga component was added during the compounding.

From the above results, it is found that the Ga component is preferably added in the fine pulverization.

< examples 3 to 3>

Ga is added in the 1 st micro-pulverization₂O₃A sintered body was produced under the same conditions as in example 3-2 except that the powder (1 st particle diameter: 2 μm) was changed to 4.0 wt%.

The coercive force (HcJ) and residual magnetic flux density (Br) of the sample obtained in example 3-3 were measured under the same conditions as in example 1. The results are shown in FIG. 26.

In FIG. 26, it is understood that, when 3 samples in which the amount of Ga component added is 4.0 wt% are compared, the coercive force (HcJ) of the sample to which Ga component was added at the 1 st pulverization, the sample to which Ga component was added at the 2 nd pulverization, and the sample to which Ga component was added at the mixing are sequentially increased. The residual magnetic flux density (Br) of the samples obtained in examples 3-2 and 3-3 was higher than that of the sample obtained in example 3-1.

From the above results, it was confirmed that the Ga component addition time is more preferable in the fine pulverization than in the blending, and particularly, by adding Ga in the 1 st fine pulverization, higher coercive force can be expected.

Example 4

Example 4 (example 4-1, example 4-2)

SrCO added to confirm the pre-firing₃And BaCO₃The experiment conducted on the influence of the amount of (2) on the characteristics is shown as example 4.

< example 4-1>

Adding SiO during the 2 nd micro-pulverization₂0.6 wt% of powder (1-time particle diameter: 0.01 μm), CaCO₃0.35 wt% of powder (1-order particle diameter: 1 μm), 0.4 wt% of carbon powder (1-order particle diameter: 0.05 μm), 1.2 wt% of sorbitol (1-order particle diameter: 10 μm), Ga₂O₃6.0 wt% of powder (1-time particle diameter: 2 μm) while SrCO was added in the amount shown in FIG. 29₃Powder (1-order particle diameter: 2 μm) and BaCO₃A sintered body was produced under the same conditions as in example 2-1 except that the powder (1-order particle diameter: 0.05 μm) was used.

< examples 4 and 2>

Adding SiO during the 2 nd micro-pulverization₂A sintered body was produced under the same conditions as in example 4-1 except that the amount of the powder (1-order particle diameter: 0.01 μm) added was changed to 0.45 wt%.

The coercive force (HcJ) and residual magnetic flux density (Br) of the sintered bodies obtained in example 4-1 and example 4-2 were measured under the same conditions as in example 1. The results are shown in fig. 29. The composition of the obtained sintered body was analyzed in the same manner as in example 1. The results are shown in fig. 29.

As shown in fig. 29, by adjusting the additive in the 2 nd micro-pulverization, high characteristics were obtained at all points in the range of this study, although the values of remanence (Br) and coercive force (HcJ) varied.

Example 5

Example 5 (example 5-1, example 5-2, and example 5-3)

Examples 1-4 above relate to Fe₂W-type iron oxideIn particular, example 5 represents an experiment performed to confirm the effect of adding the subcomponents recommended by the present invention to ZnW ferrite represented by formula (3).

< example 5-1>

Fe was prepared as a raw material powder₂O₃Powder (1-order particle diameter: 0.3 μm), SrCO₃Powder (1-order particle diameter: 2 μm) and ZnO powder (1-order particle diameter: 0.8 μm). The raw material powder was weighed so that the final composition was SrZn_1.5Fe₁₅Thereafter, mixing and pulverization were performed in a wet mill for 2 hours.

Next, the calcination was performed in the air. The burn-in temperature, the holding time, the temperature increase to the heating holding temperature, and the temperature decrease rate from the heating holding temperature were the same as those in example 2.

Subsequently, the mixture was disintegrated by a vibration mill under the same conditions as in example 2.

The following micro-pulverization was carried out in 2 stages by a ball mill. The 1 st fine grinding was carried out under the same conditions as in example 2 except that 1.2 wt% of sorbitol (1 st particle diameter: 10 μm) was added as a polyol before the 1 st fine grinding.

After the 1 st fine pulverization, the fine pulverized powder was heat-treated in the atmosphere at 800 ℃ for 1 hour. The rates of temperature increase until the heating retention temperature and temperature decrease from the heating retention temperature were the same as in example 2.

Subsequently, the 2 nd micro-pulverization of the wet-pulverization was carried out by a ball mill to obtain a slurry for wet molding. Adding SiO to the heat-treated fine powder before the 2 nd fine pulverization₂0.6 wt% of powder (1-time particle diameter: 0.01 μm), CaCO₃0.35 wt% of powder (1-order particle diameter: 1 μm) and 1.2 wt% of sorbitol (1-order particle diameter: 10 μm). In addition thereto, Ga is added₂O₃0 to 0.8 wt% of a powder (1-order particle diameter: 2 μm).

The slurry obtained by the 2 nd fine pulverization was concentrated by a centrifugal separator, and the concentrated slurry for wet molding was used for molding in a magnetic field. The applied magnetic field (longitudinal magnetic field) was 12kOe (1000kA/m), and the molded body had a cylindrical shape with a diameter of 30mm and a height of 15 mm. In any of the molding methods, no unfavorable condition occurs. The compact was dried in the air, and then sintered at a maximum temperature of 1240 ℃ for 1 hour at a temperature increase rate of 5 ℃/min to obtain a sintered body.

The coercive force (HcJ) and residual magnetic flux density (Br) of the sintered body obtained in example 5-1 were measured under the same conditions as in example 1. The results are shown in fig. 30.

As shown in fig. 30, even when Ga component is added to the ZnW type ferrite, the coercive force (HcJ) can be improved while suppressing a decrease in residual magnetic flux density (Br).

< examples 5 and 2>

The raw material powders were weighed so as to give a final composition of SrZn_1.3Fe₁₄And in place of Ga₂O₃Powder of Al₂O₃A sintered body was produced under the same conditions as in example 5-1 except that the amount of the powder (1 st particle diameter: 0.5 μm) was changed to 0 to 1.5 wt%.

< examples 5to 3>

The raw material powders were weighed so that the final composition was SrZn_1.2Fe₁₃And Ga is compositely added₂O₃Powder and Al₂O₃Except for the powder, a sintered body was produced under the same conditions as in example 5-1.

The coercive force (HcJ) and residual magnetic flux density (Br) of the sintered bodies obtained in examples 5-2 and 5-3 were measured under the same conditions as in example 1. The results are shown in fig. 30.

As shown in fig. 30, the coercive force (HcJ) can be improved by adding an Al component to the ZnW type ferrite.

Claims (21)

1. A ferrite sintered magnet characterized by:

as a main component, containing a compound represented by the formula AFe²⁺ _aFe³⁺ _bO₂₇The composition of (a);

as the 1 st subcomponent, CaCO₃0.3 to 3.0 wt% of Ca component and SiO component₂0.2 to 1.4 wt% in terms of Si component; and is

As the sub-component 2, Al is contained₂O₃0.01 to 1.5 wt% of Al component in terms of WO₃0.01 to 0.6 wt% of W component in terms of CeO₂0.001 to 0.6 wt% calculated as Ce component and MoO₃0.001 to 0.16 wt% in terms of Mo and Ga₂O₃At least 1 or more kinds of Ga component in terms of 0.001 to 15 wt%,

in the composition formula, A is at least 1 element selected from Sr, Ba and Pb, and a is more than or equal to 1.5 and less than or equal to 2.1, and b is more than or equal to 12.9 and less than or equal to 16.3.

2. The ferrite sintered magnet as claimed in claim 1, wherein: the content of the Al component is Al₂O₃0.1 to 0.9 wt% in terms of weight.

3. The ferrite sintered magnet as claimed in claim 1, wherein: the content of the W component is as WO₃0.1 to 0.6 wt% in terms of weight.

4. The ferrite sintered magnet as claimed in claim 1, wherein: the Ce component is CeO₂0.01 to 0.4 wt% in terms of weight.

5. The ferrite sintered magnet as claimed in claim 1, wherein: the content of the Mo component is MoO₃0.005 to 0.10 wt% in terms of weight.

6. The ferrite sintered magnet as claimed in claim 1, wherein: the content of the Ga component is Ga₂O₃0.02 to 8.0 wt% in terms of weight.

7. The ferrite sintered magnet as claimed in claim 1, wherein: in the composition formula, a is more than or equal to 1.6 and less than or equal to 2.0, and b is more than or equal to 13.5 and less than or equal to 16.2.

8. The ferrite sintered magnet as claimed in claim 1, wherein: sr and Ba are the elements A in common.

9. The ferrite sintered magnet as claimed in claim 1, wherein: the ferrite sintered magnet constitutes any one of a ferrite magnet powder, a bonded magnet obtained by dispersing the ferrite magnet powder in a resin, and a magnetic recording medium as a film-like magnetic phase.

10. The ferrite sintered magnet as claimed in claim 1, wherein: in the ferrite sintered magnet, hexagonal W-type ferrite constitutes a main phase.

11. The ferrite sintered magnet as claimed in claim 1, wherein: the ferrite sintered magnet has a coercive force of 3.0kOe or more and a residual magnetic flux density of 4.0kG or more.

12. The ferrite sintered magnet as claimed in claim 1, wherein: the ferrite sintered magnet has a coercive force of 3.3kOe or more and a residual magnetic flux density of 4.6kG or more.

13. A ferrite sintered magnet characterized by: hexagonal W-type ferrite constituting a main phase and Ga₂O₃Contains 15 wt% or less of Ga but not 0 wt%.

14. The ferrite sintered magnet as set forth in claim 13, wherein: the ferrite sintered magnet has a composition formula of AFe²⁺ _aFe³⁺ _bO₂₇The composition is characterized in that A is at least 1 element selected from Sr, Ba and Pb, and a is not less than 1.5 and not more than 2.1, and b is not less than 12.9 and not more than 16.3.

15. According to claimThe ferrite sintered magnet according to 13, characterized in that: the ferrite sintered magnet has a composition formula of AZn_cFe_dO₂₇The composition is characterized in that A is at least 1 element selected from Sr, Ba and Pb, and c is 1.1-2.1, d is 13-17.

16. The ferrite sintered magnet as claimed in claim 14 or 15, wherein: the content of the Ga component is Ga₂O₃0.02 to 3.0 wt% in terms of weight.

17. The ferrite sintered magnet as claimed in claim 14 or 15, wherein: the content of the Ga component is Ga₂O₃Converted to 3.0 to 8.0 wt%.

18. The ferrite sintered magnet as claimed in claim 1, wherein: the average grain diameter of the ferrite sintered magnet is 0.8 [ mu ] m or less.

19. The ferrite sintered magnet as claimed in claim 1, wherein: the average grain diameter of the ferrite sintered magnet is 0.6 [ mu ] m or less.

20. The ferrite sintered magnet as claimed in claim 1, wherein: the ferrite sintered magnet has a coercive force of 3.5kOe or more and a residual magnetic flux density of 4.0kG or more.

21. The ferrite sintered magnet as claimed in claim 1, wherein: sr and Ba are the elements A in common.