JP5499329B2 - Ferrite sintered magnet and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sintered ferrite magnet and a method for manufacturing the same.

Ferrite sintered magnets are used in various motors, generators, speakers, and the like. As typical ferrite sintered magnets, Sr ferrite (SrFe ₁₂ O ₁₉ ) and Ba ferrite (BaFe ₁₂ O ₁₉ ) having a hexagonal M-type magnetoplumbite structure are known. These sintered ferrite magnets are manufactured at a relatively low cost by powder metallurgy using iron oxide and strontium (Sr) or barium (Ba) carbonate as raw materials.

In recent years, due to environmental considerations and the like, there has been a demand for higher performance of sintered ferrite magnets for the purpose of reducing the size, weight, and efficiency of automotive electrical parts, electrical equipment parts, and the like. In particular, motors used in automotive electrical components have a high coercive force H that maintains a high residual magnetic flux density B _r (hereinafter simply referred to as “B _r ”) and does not demagnetize by a demagnetizing field when it is thinned. _There is a demand for sintered ferrite magnets having _cJ (hereinafter simply referred to as “H _cJ ”).

Order to improve the magnetic properties of the sintered ferrite magnet was replaced with the rare earth element La, etc. Some of the Sr in the above Sr ferrite, by substituting a part of Fe with Co, the H _cJ and B _r JP-A-10-149910 (Patent Document 1), JP-A-11-154604 (Patent Document 2), and the like have been proposed as methods for improvement.

  The Sr ferrite (hereinafter referred to as “SrLaCo ferrite”) described in Patent Document 1 and Patent Document 2 in which a part of Sr is replaced with a rare earth element such as La and a part of Fe is replaced with Co or the like is a magnet property. Therefore, in addition to the conventional Sr ferrite and Ba ferrite, they are being widely used in various applications, but further improvement of the magnet properties is also desired.

On the other hand, Ca ferrite is also known as a ferrite sintered magnet together with the Sr ferrite and Ba ferrite. Ca ferrite has a stable structure represented by a composition formula of CaO—Fe ₂ O ₃ or CaO-2Fe ₂ O ₃ and is known to form hexagonal ferrite by adding La. However, the magnet properties obtained are comparable to those of conventional Ba ferrite and are not sufficiently high.

Patent No. 3181559 (Patent Document 3), the improvement of B _r and H _cJ of the Ca ferrite, and for improving the temperature characteristics of the H _cJ, by replacing part of Ca with rare earth elements such as La, the Fe partially substituted with Co, etc., discloses a Ca ferrite (hereinafter referred to as "CaLaCo ferrite") having a 20 kOe or more anisotropic magnetic field H _a, the anisotropic magnetic field H _a is compared to the Sr ferrite The value is 10% or higher.

However, the CaLaCo ferrite of Patent Document 3, although an anisotropic magnetic field H _A in excess of SrLaCo ferrite, B _r and H _cJ are comparable to SrLaCo ferrite, while the squareness ratio H _k / H _cJ ( (Hereinafter simply referred to as “H _k / H _cJ ”) is very bad and cannot satisfy both high H _cJ and high H _k / H _cJ, and before it is applied to various applications such as motors. Not reached.

  In order to improve the magnet characteristics of the SrLaCo ferrite described above, Japanese Patent Application Laid-Open No. 11-195516 (Patent Document 4) describes a method for producing SrLaCo ferrite proposed in Patent Document 1 and Patent Document 2, which is used as a calcined powder of Sr Ferrite. A method for producing SrLaCo ferrite by adding La and Co, forming, and firing is proposed. It is described that the sintered magnet obtained by this method has two different Curie temperatures (Tc), has high squareness, and can reduce the Co content.

  Although Patent Document 4 has improved magnet characteristics compared to the SrLaCo ferrite proposed in Patent Documents 1 and 2, the demand for higher performance has become increasingly stronger in recent years, and further improvements in magnet characteristics have been demanded. Yes.

  JP 2006-104050 (Patent Document 5), International Publication No. 2007/060757 (Patent Document 6) and International Publication No. 2007/077811 (Patent Document 7) are all CaLaCo ferrites proposed in Patent Document 3. Patent Document 5 proposes to optimize the atomic ratio and molar ratio n of each constituent element, and to contain La and Co at a specific ratio. Patent Document 6 proposes replacing a part of Ca with La and Ba, and Patent Document 7 proposes replacing a part of Ca with La and Sr.

The invention described in Patent Document 5~7, CaLaCo ferrite sintered magnet having a high B _r and a high H _cJ than the SrLaCo ferrite is obtained. However, any of the ferrite sintered magnets described in Patent Documents 5 to 7 needs to contain Co in an atomic ratio of about 0.3 in order to obtain high magnet characteristics. In other words, there is a problem that the raw material cost increases because more Co is required than SrLaCo ferrite sintered magnets currently available on the market (Co content of about 0.2 in atomic ratio).

One of the biggest features of sintered ferrite magnets is high economy. Even ferrite sintered magnets with high magnet properties are not accepted in the market if the price is high. For example, the price of Co and La is ten to several tens of times the price of iron oxide, which is the main component, so the price of sintered ferrite magnets increases significantly when the content of Co and La increases (2009 LMB (London Metal Bulletin) Cobalt market price in November 2011 is 21.1-22.0 $ / lb for high-grade products, and is simply 3,100-3,200 yen / kg when converted to Co ₃ O ₄ , La C quote for Japan CIF is 10 $ / kg It is about 770 yen / kg when simply converted to La ₂ O ₃ ).

However, if the Co content of CaLaCo ferrite described in Patent Documents 5 to 7 is reduced to the same level as SrLaCo ferrite (at an atomic ratio of about 0.2), the magnetic properties, particularly _HcJ, will be lower than that of SrLaCo ferrite. (High B _r and high H _cJ ) are not exerted.

Japanese Patent Laid-Open No. 10-149910 Japanese Patent Laid-Open No. 11-154604 Japanese Patent No. 3181559 JP-A-11-195516 JP 2006-104050 A International Publication No. 2007/060757 Pamphlet International Publication No. 2007/077811 Pamphlet

  The object of the present invention is to improve the magnet properties of sintered ferrite magnets, and in particular, to improve the magnet properties of SrLaCo ferrite sintered magnets that are cheaper than CaLaCo ferrite sintered magnets, It is to provide a ferrite sintered magnet that satisfies the demand for performance at a low cost.

As a result of diligent research in view of the above-mentioned object, the inventors have developed a ferrite containing Ca, La, Fe and Co in a calcined body containing Sr, La, Fe and Co (hereinafter also referred to as SrLaCo ferrite) ( (Hereinafter also referred to as CaLaCo ferrite) The ferrite sintered magnet obtained by mixing a specific amount of calcined body, pulverizing, forming and firing is derived from the SrLaCo ferrite calcined body and has a Curie temperature at 440 to 455 ° C. a first and particulate ferrite compound phase, and a second particulate ferrite compound phase Curie temperature exists a CaLaCo ferrite calcined body 440 below ° C. 420 ° C. or higher and derived from, a high B _r and high H The inventors have found that high H _cJ can be obtained while maintaining _{k 2} / H _{cJ, and} have _arrived at the present invention.

In proposing the present invention, the inventors paid attention to the difference in magnet characteristics between the SrLaCo ferrite sintered magnet and the CaLaCo ferrite sintered magnet, particularly _HcJ . Although _HcJ of the sintered magnet is affected by the structure of the sintered body, it is theoretically proportional to _HA . In other words, improvement in H _cJ as H _A material is high is expected.

SrLaCo ferrite sintered magnet and CaLaCo the H _A ferrite sintered magnet from the magnetic hysteresis curve SPD (Singular Point Detection) method results measured by, H _A of CaLaCo ferrite was 0.3 atomic ratio of Co is 2.1 MA / m ( about 26.4 kOe), H _a of CaLaCo ferrite was 0.2 atomic ratio of Co is 1.9 MA / m (about 23.9 kOe), common SrLaCo ferrite was 0.2 atomic ratio of Co together H _a [1.8 The value was higher than that of MA / m (about 22.6 kOe), and CaLaCo ferrite was expected to have higher H _cJ than SrLaCo ferrite.

However, as described above, CaLaCo ferrite having a Co atomic ratio of 0.3 increases the raw material cost, so that the economical characteristics that are characteristic of sintered ferrite magnets are lost, making it difficult to accept in the market. On the other hand, CaLaCo ferrite with Co atomic ratio of 0.2 can avoid the increase in raw material cost, but contrary to expectations, _HcJ is less than SrLaCo ferrite and cannot exhibit the characteristics of CaLaCo ferrite.

Typical magnetic properties of SrLaCo sintered ferrite magnets which are currently provided on the market B _r of about 440 mT and H _cJ of about 350 kA / m. The product, the and the magnetic properties high B _r type and height H _cJ type mainly is lineup, when B _r and H _cJ were vertical and horizontal axes, respectively, B _r of about 450 mT and H and points _cJ of about 300 kA / m, there is a magnetic characteristic of SrLaCo ferrite sintered magnet B _r of about 430 mT and H _cJ the line on which connecting the points about 370 kA / m.

In general, when a material having a low magnetic property is mixed with a material having a high magnetic property, the magnetic property is expected to deteriorate. For example, a sintered magnet obtained by mixing a general SrLaCo ferrite with a Co atomic ratio of 0.2 and a CaLaCo ferrite with a Co atomic ratio of 0.2, which is inferior to _HcJ than SrLaCo ferrite, has a CaLaCo ferrite temporary structure. It is expected that H _cJ will decrease as the mixing ratio of the sintered body increases.

However, while trying to improve the magnet characteristics of the SrLaCo ferrite sintered magnet, the inventors of the present application mixed a CaLaCo ferrite calcined body having a Co atomic ratio of 0.2 with a specific mass ratio into the SrLaCo ferrite calcined body. sintered magnet was collected using the called H _k / H _cJ is H _cJ and B _r at least equivalent is improved compared to SrLaCo sintered ferrite magnet was found to have a magnetic characteristic contrary to expectations.

As a result of analyzing the obtained sintered magnet, a particulate ferrite compound phase (Curie temperature: 440 to 455 ° C.) containing Sr, La, Fe and Co, and a particulate form containing Ca, La, Fe and Co. The ferrite compound phase (Curie temperature: 420 ° C. or higher and lower than 440 ° C.) has a special structure coexisting in the sintered body. The improvement in H _cJ is attributed to this special organization.

  Patent Document 4 is an improved invention of SrLaCo ferrite proposed in Patent Document 1 and Patent Document 2 as described above, having a main phase of hexagonal ferrite, and a temperature difference of 5 ° C in the range of 400 to 480 ° C. A sintered magnet having at least two different Curie temperatures is disclosed.

  The SrLaCo ferrite sintered magnet having two different Curie temperatures described in Patent Document 4 is produced by a so-called “post-addition method”. The “post-addition method” means adding a compound of La, Fe, and Co at a predetermined ratio to a calcined body of M-type Sr ferrite obtained by blending and calcining Sr compound and Fe compound as raw materials, This is a method for producing a sintered SrLaCo ferrite magnet by pulverization, molding and firing.

  Patent Document 4 describes the reason why a structure having two different Curie points can be obtained by the “post-addition method” as follows. That is, Sr ferrite reacts with La, Fe, and Co compounds added later during firing, and in the process, M-type ferrite parts with high concentrations of La and Co and M-type ferrite parts with low concentrations can be formed. . That is, if La and Co added later diffuse into the calcined particles of M-type ferrite, a structure in which the concentration of La and Co is higher in the surface layer than in the center of the particle is obtained. Since the Curie temperature depends on the amount of substitution of La and Co, especially the amount of substitution of La, by having such a structure that the composition is non-uniform, there are at least two Curie temperatures. (Paragraph [0031]).

  Patent Document 4 describes that the two Curie temperatures are considered to be manifested due to a two-phase structure of M-type ferrite that is magnetically different depending on the manufacturing method or the like (paragraph [0053]). The Curie temperature (Tc1) decreased with increasing amounts of La and Co, but the higher Curie temperature (Tc2) did not show much change, so Tc1 had a large amount of La and Co substitution. It is described that it is expected to be the Curie temperature of the ferrite structure part (paragraph [0138]).

  From these descriptions, the SrLaCo ferrite sintered magnet obtained by the “post-addition method” is a two-phase structure in which SrLaCo ferrite particles having a high La and Co concentration and SrLaCo ferrite particles having a low La and Co concentration are mixed, or It has a two-phase structure composed of SrLaCo ferrite particles whose La and Co concentrations are higher in the surface layer than in the center, and the Curie temperature of each phase is considered to be different. In any case, the phenomenon in which two different Curie temperatures appear in the “post-addition method” described in Patent Document 4 is caused by the presence of phases having different concentration distributions of La and Co.

  On the other hand, the ferrite sintered magnet of the present invention includes a ferrite compound phase (Curie temperature: 440 to 455 ° C.) derived from a SrLaCo ferrite calcined body containing Sr, La, Fe and Co, and Ca, La. , A ferrite compound phase derived from a CaLaCo ferrite calcined body containing Fe and Co (Curie temperature: 420 ° C. or higher and lower than 440 ° C.) is distributed in the form of particles inside the sintered body. This is completely different from the ferrite sintered magnet described.

  Further, the sintered ferrite magnet of the present invention is obtained by mixing SrLaCo ferrite calcined body and CaLaCo ferrite calcined body having different compositions at a specific mass ratio, pulverizing, molding and sintering, This is completely different from that obtained by the “post-addition method” described in Document 4.

Therefore, the ferrite sintered magnet of the present invention is
A first particulate ferrite compound phase containing Sr, La, Fe and Co and having a Curie temperature at 440 to 455 ° C .;
A ferrite sintered magnet containing Ca, La, Fe and Co and having a second particulate ferrite compound phase having a Curie temperature of 420 ° C. or higher and lower than 440 ° C.,
The volume ratio of the first particulate ferrite compound phase is more than 50% and 90% or less, the volume ratio of the second particulate ferrite compound phase is 10% or more and less than 50%, the sum of both volume ratios Is 95% or more.

  The volume ratio of the first particulate ferrite compound phase is 60 to 80%, the volume ratio of the second particulate ferrite compound phase is 20 to 40%, and the sum of both volume ratios is 95% or more. Preferably there is.

  The second particulate ferrite compound phase preferably further contains Ba and / or Sr.

The composition ratio of Sr, La, Ca, Ba, Fe and Co in the sintered ferrite magnet is represented by the general formula:
Sr _1-xab La _x Ca _a Ba _b Fe _2n-y Co _y
(However, x, a, b and y representing the atomic ratio of Sr, La, Ca, Ba, Fe and Co and n representing the molar ratio are
0.1 ≦ x ≦ 0.5,
0.04 ≦ a ≦ 0.5,
0 ≦ b ≦ 0.2,
0.2 ≦ 1-xab,
0.05 ≦ y ≦ 0.3, and
4 ≦ n ≦ 6
It is a numerical value that satisfies ) Is preferred.

X, a, b and y representing the atomic ratio of Sr, La, Ca, Ba, Fe and Co and n representing the molar ratio are:
0.2 ≦ x ≦ 0.4,
0.1 ≦ a ≦ 0.4,
0 ≦ b ≦ 0.1,
0.3 ≦ 1-xab,
0.1 ≦ y ≦ 0.3, and
4.2 ≦ n ≦ 5.7
It is preferable that the value satisfies the above.

The composition ratio of Sr, La, Fe and Co in the first particulate ferrite compound phase is represented by the general formula:
Sr _{1-x '} La _x' Fe _{2n'-y '} Co _y'
(However, x ′ and y ′ representing the atomic ratio of Sr, La, Fe and Co and n ′ representing the molar ratio are
0.05 ≦ x ′ ≦ 0.3,
0.05 ≦ y ′ ≦ 0.3, and
5 ≦ n ′ ≦ 6
It is a numerical value that satisfies ) Is preferred.

Y ′ representing the atomic ratio of Co in the first particulate ferrite compound phase is:
0.1 ≦ y '≦ 0.2
It is preferable that the value satisfies the above.

When the composition ratio of Ca, La, (Ba + Sr), Fe and Co in the second particulate ferrite compound phase is such that (Ba + Sr) is an A element, the general formula:
Ca _1- x`` <sub>-c</sub> La <sub>x ''</sub> A <sub>c</sub> Fe <sub>2n``-y ''</sub> Co _{y ''}
(However, x ″, c and y ″ representing the atomic ratio of Ca, La, A element, Fe and Co, and n ″ representing the molar ratio,
0.4 ≦ x '' ≦ 0.6,
0 ≦ c ≦ 0.2,
0 <y '' ≦ 0.2, and
4 ≦ n '' ≦ 6
It is a numerical value that satisfies ) Is preferred.

Y '' representing the atomic ratio of Co in the second particulate ferrite compound phase is
0.1 ≦ y '' ≦ 0.2
It is preferable that the value satisfies the above.

Y '' representing the atomic ratio of Co in the second particulate ferrite compound phase is
0.1 <y '' ≦ 0.2
It is preferable that the value satisfies the above.

The method for producing a sintered ferrite magnet of the present invention is as follows:
The composition ratio of Sr, La, Fe and Co has the general formula: Sr _{1-x ′} La _{x ′} Fe _{2n′-y ′} Co _{y ′} (where x ′ representing the atomic ratio of Sr, La, Fe and Co y ′ and n ′ representing the molar ratio are numerical values satisfying 0.05 ≦ x ′ ≦ 0.3, 0.05 ≦ y ′ ≦ 0.3, and 5 ≦ n ′ ≦ 6.) And the composition ratio of Ca, La, (Ba + Sr), Fe, and Co, when (Ba + Sr) is an A element, the general formula: Ca _{1-x ″ -c} La _{x ″} A _c Fe _{2n ″ -y ''} Co _{y ''} (where x ″, c and y ″ representing the atomic ratio of Ca, La, A element, Fe and Co, and n ″ representing the molar ratio are 0.4 ≦ x ″. ≦ 0.6, 0 ≦ c ≦ 0.2, 0 <y ″ ≦ 0.2, and 4 ≦ n ″ ≦ 6.) The second ferrite calcined body represented by The total ratio of the calcined body and the second ferrite calcined body to 100% by mass is mixed so that the mixing ratio of the second ferrite calcined body is 10% by mass or more and less than 50% by mass. Mixing step of obtaining a compound,
Crushing the ferrite calcined body mixture to obtain a powder,
It includes a molding step of molding the powder and obtaining a molded body, and a firing step of firing the molded body and obtaining a sintered body.

  The first ferrite calcined body and the second ferrite calcined body are mixed so that the mixing ratio of the second ferrite calcined body is 20 to 40% by mass. Magnet manufacturing method.

Y ′ representing the atomic ratio of Co in the first ferrite calcined body is
0.1 ≦ y '≦ 0.2
It is preferable that the value satisfies the above.

Y '' representing the atomic ratio of Co in the second ferrite calcined body is
0.1 ≦ y '' ≦ 0.2
It is preferable that the value satisfies the above.

Y '' representing the atomic ratio of Co in the second ferrite calcined body is
0.1 <y '' ≦ 0.2
It is preferable that the value satisfies the above.

The composition ratio of Ca, La, Sr, Ba, Fe and Co in the sintered ferrite magnet is represented by the general formula:
Sr _1-xab La _x Ca _a Ba _b Fe _2n-y Co _y
(However, x, a, b and y representing the atomic ratio of Sr, La, Ca, Ba, Fe and Co and n representing the molar ratio are
0.1 ≦ x ≦ 0.5,
0.04 ≦ a ≦ 0.5,
0 ≦ b ≦ 0.2,
0.2 ≦ 1-xab,
0.05 ≦ y ≦ 0.3, and
4 ≦ n ≦ 6
It is a numerical value that satisfies ) Is preferred.

The present invention, H _cJ, it is possible to improve the B _r and H _k / H _cJ, upon thinner magnet, a high-performance sintered ferrite magnet never demagnetization caused by the demagnetizing field inexpensive Can be provided. For this reason, by using the ferrite sintered magnet of the present invention, it is possible to provide an automotive electrical component and an electrical device component that are reduced in size, weight, and efficiency and are provided at low cost.

It is a photograph which shows the result of having surface-analyzed by EPMA about Ca of the ferrite sintered magnet of this invention. It is a graph which shows the measurement result of the thermomagnetic balance of the ferrite sintered magnet of this invention, SrLaCo ferrite sintered magnet, and CaLaCo ferrite sintered magnet. 2 is a photograph showing the results of surface analysis by EPMA for (a) Sr, (b) Ca, and (c) Si elements of the sintered ferrite magnet of Example 1, and (d) a reflected electron image. It is a schematic diagram which shows an example of a thermomagnetic balance. 2 is a graph showing the measurement results of the thermomagnetic balance of the sintered ferrite magnet of Example 1 and its differential data. 6 is a graph showing the relationship between the mixing ratio of the CaLaCo ferrite calcined body of the sintered ferrite magnet of Example 2 and _HcJ . It is a graph showing the relationship between the mixing ratio and the B _r of the CaLaCo ferrite calcined body of ferrite sintered magnet of Example 2. 6 is a graph showing the relationship between the mixing ratio of the CaLaCo ferrite calcined body of the sintered ferrite magnet of Example 2 and H _k / H _cJ . 6 is a graph showing the relationship between the mixing ratio of the CaLaCo ferrite calcined body of the ferrite sintered magnet of Example 2 and the first Curie temperature (Tc1). 3 is a graph showing the relationship between the mixing ratio of the CaLaCo ferrite calcined body of the sintered ferrite magnet of Example 2 and the second Curie temperature (Tc2). FIG. 3 is a photograph showing the results of surface analysis by EPMA for (a) Sr, (b) Ca, and (c) Si elements of a sintered ferrite magnet (No. 10) of Example 2, and (d) a backscattered electron image. FIG. 2 is a photograph showing the results of surface analysis of EP sintered elements (a) Sr, (b) Ca, and (c) Si elements of the sintered ferrite magnet (No. 11) of Example 2 and (d) reflected electron images. FIG. 6 is a photograph showing the results of surface analysis of the (a) Sr, (b) Ca, and (c) Si elements of the sintered ferrite magnet (No. 15) of Example 2 by EPMA, and (d) a backscattered electron image. FIG. 6 is a photograph showing the results of surface analysis by EPMA for (a) Sr, (b) Ca, and (c) Si elements of a sintered ferrite magnet (No. 9) of Example 2, and (d) a backscattered electron image. It is a graph showing the relationship between the mixing ratio and the B _r and temperature coefficient of CaLaCo ferrite calcined body of ferrite sintered magnet of Example 2. 6 is a graph showing the relationship between the mixing ratio of the CaLaCo ferrite calcined body of the sintered ferrite magnet of Example 2, _HcJ, and its temperature coefficient.

[1] Ferrite sintered magnet The ferrite sintered magnet of the present invention comprises Sr, La, Fe and Co, a first particulate ferrite compound phase having a Curie temperature Tc1 at 440 to 455 ° C., Ca, A second particulate ferrite compound phase containing La, Fe and Co and having a Curie temperature Tc2 at 420 ° C. or higher and lower than 440 ° C., and the first particulate ferrite compound phase in the sintered ferrite magnet The volume ratio is more than 50% and 90% or less, the volume ratio of the second particulate ferrite compound phase is 10% or more and less than 50%, and the sum of both volume ratios is 95% or more.

  The sintered ferrite magnet of the present invention is a mixture ratio of CaLaCo ferrite calcined body with respect to a total of 100% by mass of SrLaCo ferrite calcined body and CaLaCo ferrite calcined body. Is obtained by mixing, pulverizing, molding and firing so as to be 10 mass% or more and less than 50 mass%. The “mass ratio at the time of mixing the SrLaCo ferrite calcined body and the CaLaCo ferrite calcined body” is simply referred to as “mixing ratio”.

(1) Structure FIG. 1 shows the results of surface analysis by EPMA for Ca of the sintered ferrite magnet of the present invention. In the figure, the shade is large and divided into three. The thin part (white part) is the part with the highest Ca concentration, and the dark part (black part) is the part with the lowest Ca concentration. (Gray part) is the Ca concentration between them.

The portion with the highest Ca concentration corresponds to the portion with a higher Si concentration measured separately, and CaCO ₃ and SiO ₂ added in the pulverization process to suppress crystal grain growth and improve magnet properties These additives are known to accumulate at the intergranular (grain boundary), especially at the grain boundary triple point after firing, and are therefore considered to be the grain boundary triple point.

  The portion with the lowest Ca concentration corresponds to the portion with the higher Sr concentration measured separately, and is considered to be the SrLaCo ferrite compound phase.

  The portion where the Ca concentration is an intermediate concentration is a portion other than the grain boundary phase and the SrLaCo ferrite compound phase, and is considered to be a CaLaCo ferrite compound phase.

  FIG. 2 shows the present invention in which SrLaCo ferrite sintered magnet, CaLaCo ferrite sintered magnet, and SrLaCo ferrite calcined body and CaLaCo ferrite calcined body are mixed at a mass ratio of 70:30, pulverized, molded and fired. It is a measurement result of the thermomagnetic balance of a ferrite sintered magnet. The sintered ferrite magnet of the present invention has at least two different compound phases, a compound phase having a first Curie temperature (Tc1: 443 ° C.) and a compound phase having a second Curie temperature (Tc 2: 431 ° C.). have.

  Conventionally known sintered magnets such as Sr ferrite, SrLaCo ferrite, CaLaCo ferrite, etc. are obtained by mixing and calcining raw material powders such as Sr, La, Fe, etc. Produced. These ferrite compounds are produced by a solid phase reaction (ferritization reaction) at the stage of calcination, and their physical properties are almost determined at the stage of calcination. Accordingly, the physical properties of the sintered body obtained through pulverization, molding and firing are basically maintained.

  Since Tc1 (443 ° C.) in the ferrite sintered magnet of the present invention is substantially the same as the Curie temperature (about 443 ° C.) of the SrLaCo ferrite sintered magnet, the compound phase having the first Curie temperature (Tc1) is It can be presumed that this is a compound phase (first ferrite compound phase) containing Sr, La, Fe and Co derived from the SrLaCo ferrite calcined body. Therefore, the compound phase showing the second Curie temperature (Tc2) can be presumed to be a compound phase (second ferrite compound phase) containing Ca, La, Fe and Co derived from the CaLaCo ferrite calcined body. .

  Here, Tc2 (431 ° C.) of the second ferrite compound phase is slightly higher than the Curie temperature (about 418 ° C.) of the CaLaCo ferrite sintered magnet. As shown in the examples described later, the Curie temperature of the first ferrite compound phase is substantially constant regardless of the mixing ratio of the CaLaCo ferrite calcined body, whereas the Curie temperature of the second ferrite compound phase is There is a tendency to decrease as the mixing ratio of the CaLaCo ferrite calcined body increases.

  In addition to the Curie temperature, the second ferrite compound phase derived from the CaLaCo ferrite calcined body does not cause changes in physical properties that can be confirmed by X-ray diffraction or EPMA. In general, a change in Curie temperature often occurs with a change in the composition of the compound phase (in particular, La has a large effect on the Curie temperature). However, since the Curie temperature of the first ferrite compound phase hardly changes depending on the mixing ratio of the two calcined bodies, each constituent element is between the first ferrite compound phase and the second ferrite compound phase. It is considered that no mutual diffusion occurred.

The reason why the Curie temperature of the second ferrite compound phase changes is not clear, but the second ferrite compound phase coexists in the sintered body with the first ferrite compound phase that attempts to maintain physical properties. For this reason, it is considered that some kind of change is caused and the physical property (Curie temperature) is changed accordingly. This change in physical properties, H _cJ, is considered to exhibit the effect of improving the B _r and H _k / H _cJ.

In the sintered ferrite magnet of the present invention, the volume ratio of the first ferrite compound phase is more than 50% and 90% or less, the volume ratio of the second ferrite compound phase is 10% or more and less than 50%. when the sum is 95% or more, B _r and H _k / H _cJ hardly decrease, the effect is obtained that H _cJ can be improved. When having such a volume ratio, the Curie temperature Tc1 of the first ferrite compound phase is 440 to 455 ° C, preferably 440 ° C to 445 ° C, and the Curie temperature Tc2 of the second ferrite compound phase is 420. It is in the range of from ℃ to less than 440 ℃.

  As described above, SrLaCo ferrite calcined body and CaLaCo ferrite calcined body are mixed at the above mass ratio, and the sintered magnet obtained by pulverizing, molding and firing is a stage where the physical properties of the ferrite compound are calcined. Since the physical properties of the sintered body are basically maintained in the sintered body, the SrLaCo ferrite calcined body is basically the first ferrite compound phase, and the CaLaCo ferrite calcined body is the second ferrite compound phase. The ferrite compound phase is present in the sintered ferrite magnet at a ratio (volume ratio) substantially the same as the mixing ratio (mass ratio) at the time of mixing. That is, the crystal grain size of the ferrite compound phase is changed by the pulverization step and the firing step, but the ratio is not changed.

  Therefore, the SrLaCo ferrite calcined body (first ferrite calcined body) and the CaLaCo ferrite calcined body (second ferrite calcined body) are 100% by mass in total of the SrLaCo ferrite calcined body and the CaLaCo ferrite calcined body. On the other hand, the sintered ferrite magnet obtained by mixing, pulverizing, molding and firing so that the mixing ratio of the CaLaCo ferrite calcined body is 10% by mass or more and less than 50% by mass is the first ferrite compound phase. And the volume ratio of the second ferrite compound phase is 10% or more and less than 50%.

The volume ratio of the first ferrite compound phase and the volume ratio of the second ferrite compound phase in the sintered ferrite magnet can be obtained by the following three methods. By using these methods in combination, the accuracy can be further improved.
(i) A method of determining the area ratio of each compound phase by specifying the first ferrite compound phase and the second ferrite compound phase from the cross-sectional photograph of the sintered magnet and the result of elemental analysis by EPMA.
(ii) The relationship between the mixing ratio of the two types of ferrite calcined bodies and the composition (calculated value) of the ferrite calcined body mixture after mixing is obtained, and the volume ratio is obtained from the actually measured values of the composition of the sintered body.
(iii) A method for obtaining from a σ-T curve by a vibrating sample magnetometer (VSM).

  The sum of volume ratios of the first ferrite compound phase and the second ferrite compound phase is 95% or more. The remaining portion of less than 5% is a grain boundary phase mainly composed of additives added after calcination. The presence or absence of the grain boundary phase can be confirmed with a transmission electron microscope (TEM) or the like. The sintered ferrite magnet of the present invention is basically composed of a first ferrite compound phase, a second ferrite compound phase, and a grain boundary phase, but a very small amount (about 5% by mass) by X-ray diffraction or the like. The observed heterogeneous phase (orthoferrite phase, spinel phase, etc.), impurity phase, etc. are allowed. Techniques such as Rietveld analysis can be used to quantify heterogeneous phases from X-ray diffraction.

  The sintered ferrite magnet preferably further contains Ba and / or Sr in the second ferrite compound phase. That is, as a CaLaCo ferrite calcined body, Patent Document 6 (a calcined body obtained by substituting a part of Ca with La and Ba) and Patent Document 7 (a calcined body obtained by substituting a part of Ca with La and Sr). Magnet properties can be further improved by using a known CaLaCo ferrite calcined body described in (C.).

(2) Composition
(i) Composition of the entire ferrite sintered magnet The ferrite sintered magnet of the present invention has a composition ratio of the Sr, La, Ca, Ba, Fe and Co as the entire sintered magnet.
General formula: Sr _1-xab La _x Ca _a Ba _b Fe _2n-y Co _y
(However, x, a, b and y representing the atomic ratio of Sr, La, Ca, Ba, Fe and Co and n representing the molar ratio are
0.1 ≦ x ≦ 0.5,
0.04 ≦ a ≦ 0.5,
0 ≦ b ≦ 0.2,
0.2 ≦ 1-xab,
0.05 ≦ y ≦ 0.3, and
4 ≦ n ≦ 6
It is a numerical value that satisfies ) Is preferred.

Further, the x, a, b, y and n are
0.2 ≦ x ≦ 0.4,
0.1 ≦ a ≦ 0.4,
0 ≦ b ≦ 0.1,
0.3 ≦ 1-xab,
0.1 ≦ y ≦ 0.3, and
4.2 ≦ n ≦ 5.7
It is more preferable that the value satisfies the above.

Sr is an element basically derived from the SrLaCo ferrite calcined body and is contained in the first ferrite compound phase. When a CaLaCo ferrite calcined body containing Sr is used, the Sr is contained in the second ferrite compound phase. (1-xab) indicating the atomic ratio of Sr (hereinafter referred to as “content”) is preferably 0.2 or more. If the Sr content is less than 0.2, La, Ca, and Ba increase relatively, and _HcJ decreases. A more preferable content is 0.3 or more.

La is derived from both the SrLaCo ferrite calcined body and the CaLaCo ferrite calcined body, and is contained in both the first ferrite compound phase and the second ferrite compound phase. The La content (x) is preferably in the range of 0.1 to 0.5. When the content of La is less than 0.1 or exceeds 0.5, H _cJ decreases. A more preferable content is in the range of 0.2 to 0.4.

Ca is included in CaLaCo ferrite calcined body, additives such as CaCO ₃ added after calcining, but Ca derived from CaLaCo ferrite calcined body is contained in the second ferrite compound phase and added after calcining Ca derived from CaCO ₃ or the like is contained in the grain boundary phase or the like. The Ca content (a) is preferably in the range of 0.04 to 0.5. If the Ca content is less than 0.04, the effect of improving H _cJ cannot be obtained, and if it exceeds 0.5, H _cJ decreases. A more preferable content is in the range of 0.1 to 0.4.

Ba basically originates from Ba contained in the CaLaCo ferrite calcined body and is contained in the second ferrite compound phase. The Ba content (b) is preferably 0.2 or less. The content of Ba is H _cJ and B _r decreases exceeds 0.2. A more preferable range is 0.1 or less. Since Ba is mixed as an impurity in the Sr raw material powder, it may be contained in a trace amount in the SrLaCo ferrite calcined body.

Co is derived from both the SrLaCo ferrite calcined body and the CaLaCo ferrite calcined body, and is contained in both the first ferrite compound phase and the second ferrite compound phase. The Co content (y) is preferably in the range of 0.05 to 0.3. Co content is H _cJ is less than 0.05, and reduced B _r and H _k / H _cJ, hetero phases containing much Co exceeds 0.3 (Co spinel phase) generated H _cJ, B _r and H _k / H _cJ decreases. A more preferable content is in the range of 0.1 to 0.3.

n is a value reflecting the molar ratio of (Sr + La + Ca + Ba) and (Fe + Co), and is represented by 2n = (Fe + Co) / (Sr + La + Ca + Ba). n is preferably 4-6. More than 4 and less than 6 when H _cJ, undesirably B _r and H _k / H _cJ is reduced. A more preferable range is 4.2 to 5.7.

In general, when producing a ferrite sintered magnet, a sintering aid such as SiO ₂ or CaCO ₃ is added to generate a liquid phase at the time of firing to promote sintering. Most of the added SiO ₂ , CaCO _{3 and the} like form a grain boundary phase at the grain boundary of the ferrite compound phase. The ferrite sintered magnet of the present invention includes a ferrite sintered magnet to which these sintering aids are added. When a sintering aid such as SiO ₂ or CaCO ₃ is added, the Ca content is relatively increased, and the content of other elements is relatively decreased due to the Si content. The composition range described above is set to a range that takes into account the composition change due to the addition of such a sintering aid.

(ii) Composition of the first ferrite compound phase The composition ratio of Sr, La, Fe and Co in the first ferrite compound phase is:
General formula: Sr _{1-x '} La _x' Fe _{2n'-y '} Co _y'
(However, x ′ and y ′ representing the atomic ratio of Sr, La, Fe and Co and n ′ representing the molar ratio are
0.05 ≦ x ′ ≦ 0.3,
0.05 ≦ y ′ ≦ 0.3, and
5 ≦ n ′ ≦ 6
It is a numerical value that satisfies ) Is preferred.

The content of Co (y ') is, H _cJ, in order to further improve the B _r and _{H k / H cJ, 0.1 ≦} y' is more preferably in the range of ≦ 0.2.

  As described above, the first ferrite compound phase is derived from the SrLaCo ferrite calcined body, and basically maintains the composition of the SrLaCo ferrite calcined body as it is. The composition of is substantially the same as that of the SrLaCo ferrite calcined body. Therefore, the reason for limiting the composition of the first ferrite compound phase is the same as the reason for limiting the composition of the SrLaCo ferrite calcined body described later.

(iii) Composition of second ferrite compound phase In the sintered ferrite magnet of the present invention, the composition ratio of Ca, La, (Ba + Sr), Fe, and Co in the second ferrite compound phase is (Ba + Sr) is an A element. When
General formula: Ca _{1-x ''-c} La _{x ''} A _c Fe _{2n ''-y ''} Co _{y ''}
(However, x ″, c and y ″ representing the atomic ratio of Ca, La, A element, Fe and Co, and n ″ representing the molar ratio,
0.4 ≦ x '' ≦ 0.6,
0 ≦ c ≦ 0.2,
0 <y '' ≦ 0.2, and
4 ≦ n '' ≦ 6
It is a numerical value that satisfies ) Is preferred.

The content of Co (y '') is, H _cJ, in order to further improve the B _r and _{H k / H cJ, 0.1 ≦} y ' is more preferably in the range of' ≦ 0.2, 0.1 <y '' More preferably, it is in the range of ≦ 0.2.

In a second ferrite compound phase, H _cJ, in order to further improve the B _r and H _k / H _cJ, preferably the ratio of the content of La and Co content x '' / y '' to 1.3 or higher .

  As described above, the second ferrite compound phase is derived from the CaLaCo ferrite calcined body, and basically maintains the composition of the CaLaCo ferrite calcined body as it is. The composition of is substantially the same as the composition of the CaLaCo ferrite calcined body. Therefore, the reason for limiting the composition of the second ferrite compound phase is the same as the reason for limiting the composition of the CaLaCo ferrite calcined body described later.

(3) Others In the present invention, “ferrite” is a general term for compounds formed by a divalent cation metal oxide and a trivalent iron oxide.

  The sintered ferrite magnet of the present invention has a hexagonal M-type magnetoplumbite structure. Similarly, the first ferrite compound phase and the second ferrite compound phase have a hexagonal M-type magnetoplumbite structure. Furthermore, the SrLaCo ferrite calcined body from which the first ferrite compound phase is derived and the CaLaCo ferrite calcined body from which the second ferrite compound phase is derived also have a hexagonal M-type magnetoplumbite structure.

  “Has a hexagonal M-type magnetoplumbite structure” means that the X-ray diffraction pattern of the hexagonal M-type magnetoplumbite structure is only measured when X-ray diffraction measurement is performed under general conditions. It means being observed. That is, the ferrite sintered magnet, the compound phase, and the calcined body have a substantially single structure of a hexagonal M-type magnetoplumbite structure. However, the presence of fine grain boundary phases and impurity phases that do not appear in the X-ray diffraction pattern is allowed.

[2] Ferrite sintered magnet manufacturing method The ferrite sintered magnet of the present invention comprises a SrLaCo ferrite calcined body and a CaLaCo ferrite calcined body with respect to a total of 100% by mass of the SrLaCo ferrite calcined body and the CaLaCo ferrite calcined body. The CaLaCo ferrite calcined body is mixed so that the mixing ratio is 10% by mass or more and less than 50% by mass, and is pulverized, molded and fired.

  As the SrLaCo ferrite calcined body, those described in Patent Documents 1, 2, 4, etc. can be used, and as the CaLaCo ferrite calcined body, those described in Patent Documents 3, 5, 6, 7, etc. are used. be able to.

(1) Composition of the calcined ferrite body
The SrLaCo ferrite calcined body has a composition ratio of Sr, La, Fe and Co.
General formula: Sr _{1-x '} La _x' Fe _{2n'-y '} Co _y'
(However, x ′ and y ′ representing the atomic ratio of Sr, La, Fe and Co and n ′ representing the molar ratio are
0.05 ≦ x ′ ≦ 0.3,
0.05 ≦ y ′ ≦ 0.3, and
5 ≦ n ′ ≦ 6
It is a numerical value that satisfies ) Is preferable.

The Sr content (1-x ′) is in the range of 0.7 to 0.95 from the La content (x ′) described later. The content of Sr is B _r and H _k / H _cJ is reduced to relatively increase the content of La is less than 0.7. B _r and H _k / H _cJ because the content of Sr content of La is relatively decreased when it exceeds 0.95 is reduced.

The La content (x ′) is preferably in the range of 0.05 to 0.3. The content of La exceeds 0.05 and less than 0.3 when B _r and H _k / H _cJ is reduced. Note that rare earth elements other than La mixed as inevitable impurities can be tolerated.

The Co content (y ′) is preferably in the range of 0.05 to 0.3. If the Co content is less than 0.05, the effect of improving magnetic properties by adding Co cannot be obtained. The content of Co is hetero-phase containing much Co exceeds 0.3 (Co spinel phase) generated by H _cJ, B _r and H _k / H _cJ is reduced.

n ′ is a value reflecting the molar ratio of (Sr + La) to (Fe + Co), and is represented by 2n = (Fe + Co) / (Sr + La). n ′ is preferably 5 to 6. If it is less than 5, the ratio of the non-magnetic part increases and H _cJ decreases greatly. More than 6 when calcined body in the unreacted α-Fe ₂ O ₃ is residual H _cJ, B _r and H _k / H _cJ is reduced.

The CaLaCo ferrite calcined body has a composition ratio of Ca, La, (Ba + Sr), Fe, and Co when (Ba + Sr) is an A element.
General formula: Ca _{1-x ''-c} La _{x ''} A _c Fe _{2n ''-y ''} Co _{y ''}
(However, x ″, c and y ″ representing the atomic ratio of Ca, La, A element, Fe and Co, and n ″ representing the molar ratio,
0.4 ≦ x '' ≦ 0.6,
0 ≦ c ≦ 0.2,
0 <y '' ≦ 0.2, and
4 ≦ n '' ≦ 6
It is a numerical value that satisfies ) Is preferable.

The Ca content (1-x ″ -c) is in the range of 0.2 to 0.6 from the later-described La content (x ″) and A element (Ba + Sr) content (c). In less than 0.2 content of Ca, for the content of La and the element A is relatively increased, B _r and H _k / H _cJ is reduced. When the content of Ca exceeds 0.6, the content of La and the element A to relatively reduced, B _r and H _k / H _cJ is reduced.

The La content (x ″) is preferably in the range of 0.4 to 0.6. The content of La exceeds 0.4 and less than 0.6 when B _r and H _k / H _cJ is reduced. Note that rare earth elements other than La mixed as inevitable impurities can be tolerated.

The element A is Ba and / or Sr. The content (c) of element A is preferably 0.2 or less. Even if the element A is not contained, the effect of the present invention is not impaired. However, by adding the element A, the crystal refinement and the aspect ratio in the calcined body can be reduced, and the ferrite sintered magnet H _cJ can be further improved.

  The Co content (y ″) is preferably in the range of 0 <y ″ ≦ 0.2. If the Co content is 0, the effect of improving magnetic properties by adding Co cannot be obtained. If the Co content exceeds 0.2, the raw material cost increases, which is not preferable. A more preferable content is in the range of 0.1 ≦ y ″ ≦ 0.2, and a more preferable content is in the range of 0.1 <y ″ ≦ 0.2.

n ″ is a value reflecting the molar ratio of (Ca + La + A) and (Fe + Co), and is represented by 2n = (Fe + Co) / (Ca + La + A). n ″ is preferably 4-6. Is less than 4 percentage of the non-magnetic portion is large and becomes B _r and H _k / H _cJ decreases. 6 by weight, the unreacted calcined body α-Fe ₂ O ₃ is residual B _r and H _k / H _cJ is reduced.

In CaLaCo ferrite calcined body, H _cJ, in order to further improve the B _r and H _k / H _cJ, the ratio of the content of La and Co content x '' / y '' preferably set to 1.3 or more. Further, when La content> Co content> A element content, that is, when x ″> y ″> c, the effect of improving magnet characteristics is great. Further, when Ca content> A element content, that is, when 1-x ″ -c> c, it has high magnet characteristics.

In the method for producing a sintered ferrite magnet of the present invention, the SrLaCo ferrite calcined body and the CaLaCo ferrite calcined body are 100% by mass in total of the SrLaCo ferrite calcined body and the CaLaCo ferrite calcined body, and the CaLaCo ferrite calcined body. Are mixed so that the mixing ratio is 10 mass% or more and less than 50 mass%. If the mixing ratio of the CaLaCo ferrite calcined body is less than 10% by mass or 50% by mass or more, the effect of improving _HcJ cannot be obtained. A more preferable mixing ratio is 20 to 40% by mass.

(2) Preparation process of the calcined ferrite body
The SrLaCo ferrite calcined body and the CaLaCo ferrite calcined body can be prepared by the methods described in the above-mentioned patent documents. The example of a preferable preparation process is shown below.

The raw material powders such as Sr compound, La compound, Ca compound, A element compound, iron compound, Co compound and the like are blended so as to be in a preferable range based on the above-described composition formula. The raw material powder may be a hydroxide, nitrate, chloride or the like in addition to oxides and carbonates regardless of the valence, or may be in a solution state. Specifically, Sr carbonates, oxides, chlorides and the like are used as the Sr compounds. As the La compound, oxides such as La ₂ O ₃ , hydroxides such as La (OH) ₃ , carbonates such as La ₂ (CO ₃ ) ₃ · 8H ₂ O, and the like are used. As the Ca compound, a carbonate, oxide, chloride or the like of Ca is used. As the element A compound, Ba and / or Sr carbonate, oxide, chloride and the like are used. As the iron compound, iron oxide, iron hydroxide, iron chloride, mill scale or the like is used. Examples of the Co compound include oxides such as CoO and Co ₃ O ₄ , hydroxides such as CoOOH, Co (OH) ₂ , and Co ₃ O ₄ · m ₁ H ₂ O (m ₁ is a positive number), CoCO ₃ like carbonates, and _{m 2 CoCO 3 · m 3 Co} (OH) 2 · m 4 H 2 O or the like basic carbonate _{(m 2, m 3, m} 4 are positive numbers) using To do.

When preparing the SrLaCo ferrite calcined body, the raw material powders such as Sr compound, iron compound, Co compound and La compound may be added and calcined from the time of mixing the raw materials, or after part of the calcined It may be added. For example, SrCO ₃ , Fe ₂ O ₃ , a part of La (OH) _{3 and} a part of Co ₃ O ₄ are blended, mixed and calcined to prepare a calcined body, to a CaLaCo ferrite calcined body described later In the mixing step, the remainder of La (OH) _{3 and} the remainder of Co ₃ O ₄ may be added, and pulverized, molded and sintered.

When preparing a CaLaCo ferrite calcined body, the raw material powders such as Ca compound, iron compound, Co compound and La compound may be added all at the time of raw material mixing and calcined, or partly added after calcining May be. For example, CaCO ₃ , Fe ₂ O ₃ , a part of La (OH) ₃ , and a part of Co ₃ O ₄ are mixed, mixed and calcined to prepare a calcined body, and a SrLaCo ferrite calcined body described later In the step of mixing, the remainder of La (OH) _{3 and} the remainder of Co ₃ O ₄ may be added, and pulverized, molded and sintered. Further, at the time of calcination, a compound containing B ₂ O ₃ , H ₃ BO ₃ or the like may be added as necessary to promote reactivity.

The addition of H ₃ BO ₃ is effective in improving the H _cJ and B _r. The amount of H ₃ BO ₃ added is preferably 0.3% by mass or less with respect to 100% by mass of the blended powder or calcined body. The most preferable value of the addition amount is around 0.2% by mass. H ₃ BO amount of ₃ to not obtained the effect of improving the B _r With less than 0.1 wt%, to the B _r many lower than 0.3 wt%. H ₃ BO ₃ has a function of controlling the shape and size of crystal grains during sintering, so in order to exert its effect, it may be added after calcination (before pulverization or before sintering) Further, it may be added both before and after calcination.

  The raw material powder may be blended either wet or dry. When the raw material powder is stirred together with a medium such as a steel ball, it can be mixed more uniformly. In the case of wet, water is used as a solvent. For the purpose of enhancing the dispersibility of the raw material powder, a known dispersant such as ammonium polycarboxylate or calcium gluconate may be used. The mixed raw material slurry is dehydrated to obtain a mixed raw material powder.

  By heating the mixed raw material powder using an electric furnace, a gas furnace or the like, a solid-phase reaction proceeds and a hexagonal M-type magnetoplumbite ferrite compound is formed. This process is called “calcination” and the resulting compound is called “calcination”.

  The calcination step is preferably performed in an atmosphere having an oxygen concentration of 5% or more. When the oxygen concentration is less than 5%, the solid-phase reaction hardly proceeds. A more preferable oxygen concentration is 20% or more.

In the calcination process, a ferrite phase is formed by a solid-phase reaction as the temperature rises and is completed at about 1100 ° C. Below this temperature, unreacted hematite (iron oxide) remains and the magnetic properties are low. In order to sufficiently exhibit the effects of the present invention, it is preferable to calcine at a temperature of 1100 ° C. or higher. On the other hand, when the calcining temperature exceeds 1450 ° C., crystal grains grow too much, and there is a risk that inconveniences such as requiring a long time for pulverization in the pulverization step may occur. Therefore, the calcination temperature is preferably 1100 to 1450 ° C. More preferably, it is 1200-1350 degreeC. The calcination time is preferably 0.5 to 5 hours. When H ₃ BO ₃ is added before calcination, the above reaction is promoted, so that calcination is preferably performed at 1100 to 1300 ° C.

(2) Mixing process of ferrite calcined body The SrLaCo ferrite calcined body and CaLaCo ferrite calcined body obtained by the above preparation process are based on a total of 100% by mass of the SrLaCo ferrite calcined body and the CaLaCo ferrite calcined body. Then, mixing is performed so that the mixing ratio of the CaLaCo ferrite calcined body is 10% by mass or more and less than 50% by mass to obtain a ferrite calcined body mixture. A well-known mixing method can be employ | adopted for a mixing process. Further, for example, mixing can also be performed by manufacturing a SrLaCo ferrite sintered magnet with equipment (line) after manufacturing a CaLaCo ferrite sintered magnet. Mix using “contamination”. In this case, it is preferable to confirm in advance which amount is mixed in which process. If SrLaCo ferrite sintered magnet and CaLaCo ferrite sintered magnet cannot be manufactured with different facilities (lines), this is an effective means.

In the mixing step, it is preferable to add additives such as CaCO ₃ and SiO ₂ to the mixed ferrite calcined body in order to suppress crystal grain growth and improve the magnet characteristics. It is preferable to add 1.8% by mass or less of SiO ₂ with respect to 100% by mass of the calcined body and 2% by mass or less of CaCO ₃ in terms of CaO with respect to 100% by mass of the calcined body.

SiO ₂ is most preferably added to the calcined body before the pulverization step, but a part of the added amount can be added in the raw material powder blending step before the calcining step. By adding before calcination, there is an advantage that the crystal grains at the time of calcination can be controlled.

(4) Grinding step of ferrite calcined body mixture The ferrite calcined body mixture is pulverized by a vibration mill, ball mill, attritor or the like to obtain a pulverized powder. The pulverized powder preferably has an average particle size of about 0.4 to 0.8 μm (air permeation method). The pulverization step may be either dry pulverization or wet pulverization, but is preferably performed in combination.

  In the wet pulverization, an aqueous solvent such as water or various non-aqueous solvents (for example, organic solvents such as acetone, ethanol, xylene, etc.) can be used. By the wet pulverization, a slurry in which the solvent and the calcined body are mixed is generated. It is preferable to add 0.2 to 2% by mass of various known dispersants and surfactants to the slurry in a solid content ratio of 100% by mass of the slurry. After the wet pulverization, it is preferable to concentrate and knead the slurry.

In the pulverization step, in addition to the above-described CaCO ₃ and SiO ₂ , additives such as Cr ₂ O ₃ and Al ₂ O ₃ can be added to the calcined body in order to improve magnet characteristics. The addition amount of these additives is preferably 5% by mass or less for Cr ₂ O _{3 and} 5% by mass or less for Al ₂ O _{3 with} respect to 100% by mass of the calcined body or slurry.

(5) Molding step The slurry is press-molded in a magnetic field or without a magnetic field while removing the solvent contained therein. The crystal orientation of the powder particles is aligned (oriented) by press molding in a magnetic field. Magnet properties can be dramatically improved by press forming in a magnetic field. Furthermore, in order to improve the orientation, a dispersant and / or a lubricant may be added in an amount of 0.01 to 1% by mass with respect to 100% by mass of the slurry. Moreover, you may concentrate a slurry before shaping | molding as needed. Concentration can be performed by centrifugation, filter press or the like.

(6) Firing step The molded body obtained by press molding is degreased as necessary and then fired. Firing is performed using an electric furnace, a gas furnace, or the like.

  The firing step is preferably performed in an atmosphere having an oxygen concentration of 10% or more. If the oxygen concentration is less than 10%, abnormal grain growth and generation of heterogeneous phases are caused, and the magnet characteristics deteriorate. A more preferred oxygen concentration is 20% or more, and most preferred is an oxygen concentration of 100%.

  The firing temperature is preferably 1150 to 1250 ° C., and the firing time is preferably 0.5 to 2 hours. The average crystal grain size of the sintered magnet obtained by the firing process is about 0.5 to 2 μm.

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

  The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Example 1
[Preparation of calcined SrLaCo ferrite]
Composition formula: SrCO ₃ powder, La (OH) ₃ powder so that x ′ = 0.2, y ′ = 0.15 and n ′ = 5.8 in Sr _{1-x ′} La _{x ′} Fe _{2n′-y ′} Co _{y ′} Fe ₂ O ₃ powder and Co ₃ O ₄ powder were blended, and 0.1% by mass of H ₃ BO ₃ was added to 100% by mass of the blended powder to obtain a mixed raw material powder. Water is added to this mixed raw material powder, mixed for 4 hours with a wet ball mill, dried and sized, then calcined in the atmosphere at 1250 ° C for 3 hours, and the resulting calcined body is roughly crushed with a hammer mill Then, coarsely pulverized powder of the SrLaCo ferrite calcined body was prepared.

[Preparation of calcined CaLaCo ferrite]
Composition formula: Ca _{1-x ″ -c} La _{x ″} A _c Fe _{2n ″ -y ″} Co _{y ″} , x ″ = 0.5, c = 0, y ″ = 0.2 and n ″ CaCO ₃ powder, La (OH) ₃ powder, Fe ₂ O ₃ powder and Co ₃ O ₄ powder were blended so that = 5.2, and 0.1% by mass of H ₃ BO ₃ was added to 100% by mass of this blended powder. The mixed raw material powder was obtained by addition. Water is added to this mixed raw material powder, mixed for 4 hours with a wet ball mill, dried and sized, then calcined in the atmosphere at 1250 ° C for 3 hours, and the resulting calcined body is roughly crushed with a hammer mill Then, coarsely pulverized powder of CaLaCo ferrite calcined body was prepared.

[Production of sintered ferrite magnets]
The obtained SrLaCo ferrite calcined body and CaLaCo ferrite calcined body were mixed at a mass ratio of 70:30, and 0.6% by mass of SiO ₂ powder and CaO in terms of CaO were 0.7% by mass with respect to 100% by mass of the ferrite calcined body mixture. The CaCO ₃ powder was mixed, water was added, and the mixture was finely pulverized with a wet ball mill until the average particle size by the air permeation method became 0.6 μm to obtain a slurry. The finely pulverized slurry was molded while applying a pressure of about 50 MPa and removing water while applying a magnetic field of about 1 T so that the pressure direction and the magnetic field direction were parallel. The obtained compact was fired at 1200 ° C. for 1 hour in the air to obtain a sintered ferrite magnet.

[Analysis of each element of ferrite sintered magnet]
Surface analysis of each element of the obtained ferrite sintered magnet was performed using an EPMA device (EPMA-1610 made by Shimadzu Corporation) under the conditions of an acceleration voltage of 15 kV, a beam current of 30 nA, and an irradiation time of 3 msec / point. The concentration distribution of each element of Sr, Ca, La, Fe, Si, Co, and O (oxygen) was analyzed. The results of Sr, Ca, Si and reflected electron beam images are shown in FIG.

  FIGS. 3A to 3C show the concentration distributions of Sr, Ca and Si in the same visual field, respectively, and FIG. 3D shows a reflected electron beam image. 3 (a) to (c), the density of the corresponding element is the highest in the light and dark part of the black and white image (white part), the density of the corresponding element is the lowest in the black part, and the density is between the two The part (gray part) indicates that the concentration of the corresponding element is between them. Note that the concentration distribution of La, Fe, Co, and O has almost no light and shade, and each is uniformly gray, so the illustration is omitted.

  From Fig. 3 (b), which shows the Ca concentration distribution, the white particulate part (the part with the highest Ca concentration), the gray particulate part (the part with the high Ca concentration), and the black particulate part (Ca concentration) It can be seen that there are three main areas.

The portion with the highest Ca concentration has the same Si concentration at the position corresponding to that portion (see Fig. 3 (c)) as well as Ca. Therefore, the SiO ₂ powder and CaCO added to the calcined mixture before firing ₃ It is considered to be a grain boundary (particularly a grain boundary triple point) derived from the powder.

  Since the portion having a high Ca concentration is distributed in the form of particles, the portion having a high Ca concentration is considered to be a second particulate ferrite compound phase derived from the CaLaCo ferrite calcined body.

  The Ca low concentration part is also distributed in the form of particles, and the Sr concentration is high at the position corresponding to that part (see Fig. 3 (a)). It is considered that it is one particulate ferrite compound phase.

  Thus, the sintered ferrite magnet of the present invention contains a particulate ferrite compound phase containing Sr, La, Fe and Co (referred to as the first ferrite compound phase) and Ca, La, Fe and Co. It turns out that it has a particulate ferrite compound phase (referred to as a second ferrite compound phase).

[Measure Curie temperature]
The obtained sintered ferrite magnet was heated at a rate of 20 ° C./min from room temperature to 500 ° C. using a thermomagnetic balance to obtain a TG curve. As shown in FIG. 4, the thermomagnetic balance 1 (Thermomagnetic Analysis) is a thermobalance 2 (Thermogravimetric Analysis: TG, Mettler Toledo TGA / SDTA 851e) attached with permanent magnets 3, 3 ′ The magnetic attractive force F acting on the ferromagnetic phase in the sample 4 by the magnetic field A (10 to 15 mT) applied to 4 is detected as the weight value of TG. TG is measured while raising the temperature of sample 4 with heat source 5, and the temperature of the ferromagnetic phase in sample 4 is detected by detecting the temperature at which the magnetic attractive force does not act with the change from ferromagnetic to paramagnetic. The Curie point can be obtained. In the sintered ferrite magnet of the present invention, the phase / structure change due to chemical reaction does not occur in the above-mentioned temperature rise range, so the ferromagnetic phase in the sample, that is, the first ferrite compound phase and the second ferrite Only the Curie point of the compound phase can be determined.

  Furthermore, except that only the SrLaCo ferrite calcined body is used, the SrLaCo ferrite sintered magnet produced in the same manner as the ferrite sintered magnet of the present invention, and only the CaLaCo ferrite sintered magnet is used. A TG curve was similarly obtained for a CaLaCo ferrite sintered body produced in the same manner as the magnet. FIG. 2 shows the obtained TG curve together with the ferrite sintered magnet of the present invention.

  FIG. 5 shows a TG curve and a differential value (DTG) of a sintered ferrite magnet according to the present invention. The negative peak value of the differential value of the TG curve, that is, the temperature at which the TG decrease rate of the TG curve was maximized was defined as the Curie temperature. The peak on the high temperature side was the first Curie temperature (Tc1), and the peak on the low temperature side was the second Curie temperature (Tc2).

  2 and 5, the sintered ferrite magnet of the present invention has at least two different Curie temperatures, the first Curie temperature (Tc1) is about 443 ° C., and the second Curie temperature (Tc2) is about It turns out that it is 431 degreeC. Therefore, it can be estimated that the sintered ferrite magnet of the present invention has at least two compound phases having different Curie temperatures. Further, the Curie temperature of the SrLaCo ferrite sintered magnet was about 443 ° C., and the Curie temperature of the CaLaCo ferrite sintered magnet was about 418 ° C.

  Since the first Curie temperature (443 ° C) of the sintered ferrite magnet of the present invention is substantially the same as the Curie temperature (443 ° C) of the SrLaCo ferrite sintered magnet, the compound having the first Curie temperature (Tc1) The phase is presumed to be the first ferrite compound phase containing Sr, La, Fe and Co derived from the SrLaCo ferrite calcined body revealed by EPMA.

  Therefore, the compound phase having the second Curie temperature (Tc2) was clarified from the elemental analysis by EPMA, and the second particulate form containing Ca, La, Fe and Co derived from the CaLaCo ferrite calcined body. The ferrite compound phase is considered.

  The Curie temperature (431 ° C) of the second ferrite compound phase derived from the CaLaCo ferrite calcined body is slightly higher than the Curie temperature (about 418 ° C) of the CaLaCo ferrite sintered magnet. This is because the Curie temperature of the second ferrite compound phase tends to decrease as the mixing ratio of the CaLaCo ferrite calcined body mixed with the SrLaCo ferrite calcined body increases. (On the other hand, the Curie temperature of the first ferrite compound phase is almost constant regardless of the mixing ratio of the CaLaCo ferrite calcined body mixed with the SrLaCo ferrite calcined body.)

Example 2
[Preparation of calcined SrLaCo ferrite]
In the composition formula: Sr _{1-x ′} La _{x ′} Fe _{2n′-y ′} Co _{y ′} , 1-x ′, x ′, y ′ and n ′ are S-1, S-2 and S-3 in Table 1. SrCO ₃ powder, La (OH) ₃ powder, Fe ₂ O ₃ powder and Co ₃ O ₄ powder were blended so as to have each composition of 0.1% by mass of H ₃ BO _{3 with} respect to 100% by mass of this blended powder. Was added to obtain a mixed raw material powder. Water is added to this mixed raw material powder, mixed for 4 hours with a wet ball mill, dried and sized, then calcined in the atmosphere at 1250 ° C for 3 hours, and the resulting calcined body is roughly crushed with a hammer mill Then, coarsely pulverized powders of SrLaCo ferrite calcined bodies having compositions of S-1, S-2 and S-3 were prepared.

[Preparation of calcined CaLaCo ferrite]
Composition formula: Ca _{1-x ″ -c} La _{x ″} A _c Fe _{2n ″ -y ″} Co _{y ″} (c = 0), 1-x ″ -c, x ″, y ′ CaCO ₃ powder, La (OH) ₃ powder, Fe ₂ O ₃ powder and Co ₃ O ₄ powder were blended so that 'and n' had the respective compositions of C-1 and C-2 in Table 2. 0.1% by mass of H ₃ BO ₃ was added to 100% by mass of the blended powder to obtain a mixed raw material powder. Water is added to this mixed raw material powder, mixed for 4 hours with a wet ball mill, dried and sized, then calcined in the atmosphere at 1250 ° C for 3 hours, and the resulting calcined body is roughly crushed with a hammer mill Then, coarsely pulverized powders of CaLaCo ferrite calcined bodies having respective compositions of C-1 and C-2 were prepared.

[Production of sintered ferrite magnets]
Each SrLaCo ferrite calcined body and CaLaCo ferrite calcined body obtained were mixed in a proportion of 0 mass%, 10 mass%, 20 mass%, 30 mass%, 40 mass as shown in Table 3. %, 50% by mass, 70% by mass, 90% by mass and 100% by mass (the volume ratio of the first ferrite compound phase and the second ferrite compound phase is 100: 0, 90:10, 80:20, 70:30 , 60:40, 50:50, 30:70, 10:90, and 0: 100) to prepare a calcined ferrite mixture having the composition shown in Table 4. Each ferrite calcined body mixture is mixed with 100% by mass of 0.6% by mass of SiO ₂ powder and 0.7% by mass of CaCO ₃ powder in terms of CaO, water is added, and the average particle size by air permeation method is 0.6 by wet ball mill. The slurry was obtained by pulverizing to μm. The finely pulverized slurry was molded while applying a pressure of about 50 MPa and removing water while applying a magnetic field of about 1 T so that the pressure direction and the magnetic field direction were parallel. The obtained compact was fired at 1200 ° C. for 1 hour in the air to obtain a sintered ferrite magnet.

Here, the density of the SrLaCo ferrite calcined body and the CaLaCo ferrite calcined body is substantially equal, and the amount of SiO ₂ powder and CaCO ₃ powder added to the ferrite calcined body mixture is negligible. The volume ratio of the SrLaCo ferrite phase and the CaLaCo ferrite phase inside was considered to be the same as the mixing ratio (mass ratio). The “volume ratio of SrLaCo ferrite phase and CaLaCo ferrite phase” is simply referred to as “volume ratio”.

[Evaluation of magnet characteristics]
The magnetic properties of the obtained sintered ferrite magnet are shown in Table 5 and FIGS. 6, 7, and 8. 6, 7, and 8 show that H _cJ (FIG. 6), B _r (FIG. 7), and H _k / H _cJ for the mixing ratio (mass%) of the mixed CaLaCo ferrite calcined body, respectively. It is the graph which plotted (FIG. 8). The magnet characteristics were measured at room temperature (about 23 ° C.) using a BH tracer after processing the sintered body. H _k in H _k / H _cJ, in J second quadrant (magnetization magnitude) -H (field intensity) curve, a value of H when the value of J is 0.95B _r.

(i) _Coercive force H _cJ
As can be seen from FIG. 6, when a SrLaCo ferrite calcined body (No. S-1 to S-3 calcined body) having a Co content (y ′) in the range of 0.10 to 0.20 is used, CaLaCo ferrite is used. For the straight line connecting H _{cJ at} a mixing ratio of the calcined body of 0 mass% (ie, SrLaCo ferrite sintered magnet) and H _cJ at a mixing ratio of 100 mass% (ie, CaLaCo ferrite sintered magnet), the mixing ratio is in a range of less than 10 wt% to 50 wt% in H _cJ becomes high, in particular to obtain a higher H _cJ at 20 to 40 wt%, the highest H _cJ was obtained in 30% vicinity. Furthermore, when the Co content (y ′) of the SrLaCo ferrite calcined body is in the range of 0.15 to 0.20, and the Co content (y ″) of the CaLaCo ferrite calcined body is 0.20 (S-2 / C-1 , the combination of S-3 / C-1) , sintered ferrite magnets in the range of mixing ratio 20 to 40% by weight, higher than a mixing ratio 0% by weight of the ferrite sintered magnet (SrLaCo ferrite sintered magnet) H _cJ Had. In order to obtain high H _cJ , it is preferable to use a CaLaCo ferrite calcined body having a Co content in the range of 0.10 ≦ y ″ ≦ 0.20, particularly preferably 0.10 <y ″ ≦ 0.20. I understood.

(ii) Residual magnetic flux density B _r
As is clear from FIG. 7, when a SrLaCo ferrite calcined body (No. S-1 to S-3 calcined body) having a Co content (y ′) in the range of 0.10 to 0.20 is used, the mixing ratio and B _r but in the 0 wt%, with respect to a straight line mixing ratio of connecting the B _r of 100 wt%, B _r is improved in the range of the mixing ratio less than 10 wt% to 50 wt% of the CaLaCo ferrite calcined body .

(iii) _Squareness ratio H _k / H _cJ
As is clear from FIG. 8, the CaLaCo ferrite calcined mixture ratio is 10 mass% or more and less than 50 mass% with respect to the straight line connecting H _k / H _cJ with a mixing ratio of 0 mass% and 100 mass% as a whole. H _k / H _cJ improved in range. When a SrLaCo ferrite calcined body with a Co content (y ') of 0.10 (No.S-1 calcined body) is used, H _k / H _cJ slightly decreases in the range of 10 to 30% by mass. _However , it had a high H _k / H _cJ of 93% or more.

Thus, the sintered ferrite magnet of the present invention produced by mixing SrLaCo ferrite calcined body and CaLaCo ferrite calcined body, to the SrLaCo ferrite sintered magnet, maintaining a high B _r and H _k / H _cJ As _such , it was found to have a higher H _cJ .

[Curie temperature]
Table 5 and FIGS. 9 and 10 show the Curie temperatures of the obtained sintered ferrite magnets. The Curie temperature was measured by the same method as in Example 1. FIG. 9 is a graph plotting the first Curie temperature (Tc1) against the mixing ratio (mass%) of the CaLaCo ferrite calcined body, and FIG. 10 is plotted against the mixing ratio (mass%) of the CaLaCo ferrite calcined body. Is a graph plotting the second Curie temperature (Tc2).

  As is clear from Table 5 and FIG. 9, the first Curie temperature (Tc1) of the sintered ferrite magnet of the present invention varies slightly between about 440 ° C. and about 445 ° C. in the range examined in this example. It can be seen that it is almost constant regardless of the composition of the SrLaCo ferrite calcined body and the mixing ratio of the CaLaCo ferrite calcined body. Therefore, the sintered ferrite magnet of the present invention has a first particulate ferrite compound phase containing Sr, La, Fe and Co having a Curie temperature of 440 ° C. or higher and 445 ° C. or lower. Since the Curie temperature (Tc1) varies depending on the La content, the Curie temperature (Tc1) range is the range of the La content (x) of the first particulate ferrite compound phase (0.1 ≦ x ≦ In consideration of 0.5), the temperature was set to 440 to 455 ° C. A preferred range is from 440 ° C to 445 ° C.

  On the other hand, as is apparent from Table 5 and FIG. 10, the second Curie temperature (Tc2) of the sintered ferrite magnet of the present invention tends to decrease as the mixing ratio of the CaLaCo ferrite calcined body increases in all combinations. It was in. In the region where the mixing ratio of the CaLaCo ferrite calcined body was 10% by mass or more and less than 50% by mass, the second Curie temperature (Tc2) varied from about 420 ° C. to about 440 ° C. That is, the sintered ferrite magnet of the present invention has a second particulate ferrite compound phase containing Ca, La, Fe and Co having a Curie temperature of 420 ° C. or higher and lower than 440 ° C.

[Component analysis]
The component analysis results of the obtained sintered ferrite magnet are shown in Table 6, and the results of converting the composition into atomic ratio and molar ratio are shown in Table 7. Component analysis was performed with an ICP emission spectroscopic analyzer (ICPV-1017 manufactured by Shimadzu Corporation).

When converting the component analysis results (mass%) into atomic ratio and molar ratio, each element of Ca, La, Sr, Fe and Co should be converted into atomic ratio and molar ratio so that it can be compared with the calcined ferrite mixture. In terms of SiO ₂ and CaCO ₃ added to the ferrite calcined mixture, the content ratio of CaCO ₃ , La (OH) ₃ , SrCO ₃ , Fe ₂ O ₃ and Co ₃ O ₄ is 100% by mass in total. (Mass%).

It was assumed that the total amount of SiO ₂ and CaCO ₃ added to the ferrite calcined mixture was accumulated between the particles of the sintered magnet (grain boundaries or grain boundary triple points). However, the Ca content, the CaCO ₃ was added to CaCO ₃ and a ferrite calcined body mixture was added as a raw material powder can not be separated from the component analysis results for the amount (ferrite calcined body mixture The amount added) was expressed in terms of CaO, and was subtracted from the component analysis results to calculate the atomic ratio and molar ratio of the compound phase. The amount of SiO ₂ varies because SiO ₂ is mixed as an impurity in the Fe ₂ O ₃ powder used as the raw material powder in addition to SiO ₂ added to the ferrite calcined mixture.

  The composition of the calcined ferrite mixture shown in Table 4 (atomic ratio and molar ratio) and the composition of the sintered ferrite magnet shown in Table 7 (atomic ratio and molar ratio) are compared. It can be seen that the composition of the magnet is almost the same.

  As described above, since it is considered that the first ferrite compound phase and the second ferrite compound phase do not mutually diffuse, the first particulate ferrite compound phase and the second particle in the sintered ferrite magnet The volume ratio of the ferrite-like ferrite compound phase is considered to be the same as the mixing ratio (mass ratio) of the SrLaCo ferrite calcined body and the CaLaCo ferrite calcined body.

  Therefore, the component analysis of the sintered ferrite magnet is obtained by obtaining the relationship between the mixing ratio of SrLaCo ferrite calcined body and CaLaCo ferrite calcined body and the composition (calculated value) of the mixed ferrite calcined body mixture in advance. The volume ratio can be obtained from the result.

[Analysis of each element of ferrite sintered magnet]
Surface analysis of each element by EPMA of the sintered ferrite magnets of Sample Nos. 9, 10, 11, 13, and 15 was performed under the same conditions using the same apparatus as in Example 1. Each of the samples is composed of SrLaCo ferrite calcined body having a composition of x ′ = 0.2, y ′ = 0.15, n ′ = 5.8 in the composition formula: Sr _{1-x ′} La _{x ′} Fe _{2n′-y ′} Co _{y ′} ( In the calcined body No. S-2) and the composition formula: Ca _{1-x ″ -c} La _{x ″} A _c Fe _{2n ″ -y ″} Co _{y ″} , x ″ = 0.5, c = A CaLaCo calcined body (calcined body No. C-1) having a composition of 0, y ″ = 0.2, n ″ = 4.8 and a CaLaCo ferrite calcined body mixing ratio of 100% by mass and 0% by mass, respectively. It is a ferrite sintered magnet obtained by mixing so as to be 10% by mass, 10% by mass, 30% by mass and 50% by mass. The results of sample Nos. 10, 11, 15, and 9 are shown in FIGS. Sample No. 13 (mixing ratio 30% by mass) is the same as the sintered ferrite magnet produced in Example 1, and the results of area analysis of each element by EPMA are the results of Example 1 (FIG. 3). Referred to.

From the concentration distribution of Ca in FIG. 3 and FIGS. 11 to 14 ((b) in each figure), the Ca concentration increases as the mixing ratio of the CaLaCo ferrite calcined body increases (the gray portion increases). I understand). On the other hand, it can be seen from the Sr concentration distribution chart ((a) in each figure) that the Sr concentration decreases (the black part increases) as the mixing ratio of the CaLaCo ferrite calcined body increases. Also, from the Ca and Si concentration distributions ((b) and (c) in each figure), CaCO ₃ and SiO ₂ added to the ferrite calcined body mixture accumulate between the grains (grain boundaries). It can be seen that there is a large accumulation in the three points.

  From these results, the sintered ferrite magnet of the present invention demonstrated in Example 1 includes a first particulate ferrite compound phase containing Sr, La, Fe and Co, and Ca, La, Fe and Co. The result of having a second particulate ferrite compound phase contained is supported.

[Remanence B _r and temperature coefficient of the coercivity H _cJ]
Temperature coefficient of B _r and H _cJ of the sample No.9~17 the (-40~20 ℃ and 20 to 100 ° C.) shown in FIGS. 15 and 16. Figure 15 is a plot of the temperature coefficient (vertical axis left) and B _r (vertical axis right) B _r with respect to the mixing ratio of the CaLaCo ferrite calcined body, FIG. 16, the CaLaCo ferrite calcined body The temperature coefficient of H _cJ (vertical axis left) and H _cJ (vertical axis right) are plotted on the left of the vertical axis against the mixing ratio.

15 and is apparent from Figure 16, the temperature coefficient of B _r is substantially constant regardless of the mixing ratio of the CaLaCo ferrite calcined body, the temperature coefficient of the H _cJ mixing ratio less than 10 wt% to 50 wt% The temperature coefficient of -40 to 20 ° C. and the temperature coefficient of 20 to 100 ° C. were both the lowest at a mixing ratio of 40% by mass.

  Thus, it can be seen that the sintered ferrite magnet of the present invention is less likely to be demagnetized by a demagnetizing field even at a low temperature. Therefore, by using the ferrite sintered magnet of the present invention, it is possible to provide an automobile electrical component and an electrical device component that are reduced in size, weight, and efficiency.

  INDUSTRIAL APPLICABILITY The present invention can be used for various applications such as various motors, generators, speakers, and the like, and can be particularly suitably used for motors used for automobile electrical parts and electrical equipment parts.

1 Thermomagnetic Balance 2 Thermal Balance 3, 3 'Permanent Magnet 4 Sample 5 Heat Source

Claims (16)

A first particulate ferrite compound phase containing Sr, La, Fe and Co and having a Curie temperature at 440 to 455 ° C .;
A ferrite sintered magnet containing Ca, La, Fe and Co and having a second particulate ferrite compound phase having a Curie temperature of 420 ° C. or higher and lower than 440 ° C.,
The volume ratio of the first particulate ferrite compound phase is more than 50% and 90% or less, the volume ratio of the second particulate ferrite compound phase is 10% or more and less than 50%, the sum of both volume ratios Ferrite sintered magnet, characterized in that is 95% or more.   The ferrite sintered magnet according to claim 1, wherein the volume ratio of the first particulate ferrite compound phase is 60 to 80%, and the volume ratio of the second particulate ferrite compound phase is 20 to 40%. A sintered ferrite magnet characterized in that the sum of both volume ratios is 95% or more.   3. The sintered ferrite magnet according to claim 1, further comprising Ba and / or Sr in the second particulate ferrite compound phase. The ferrite sintered magnet according to claim 3, wherein the composition ratio of the Sr, La, Ca, Ba, Fe and Co is represented by the general formula:
Sr _1-xab La _x Ca _a Ba _b Fe _2n-y Co _y
(However, x, a, b and y representing the atomic ratio of Sr, La, Ca, Ba, Fe and Co and n representing the molar ratio are
0.1 ≦ x ≦ 0.5,
0.04 ≦ a ≦ 0.5,
0 ≦ b ≦ 0.2,
0.2 ≦ 1-xab,
0.05 ≦ y ≦ 0.3, and
4 ≦ n ≦ 6
It is a numerical value that satisfies The ferrite sintered magnet characterized by the above-mentioned. In the ferrite sintered magnet according to claim 4, x, a, b and y representing the atomic ratio of the Sr, La, Ca, Ba, Fe and Co, and n representing the molar ratio,
0.2 ≦ x ≦ 0.4,
0.1 ≦ a ≦ 0.4,
0 ≦ b ≦ 0.1,
0.3 ≦ 1-xab,
0.1 ≦ y ≦ 0.3, and
4.2 ≦ n ≦ 5.7
A sintered ferrite magnet characterized by satisfying the following requirements. The ferrite sintered magnet according to any one of claims 1 to 5, wherein the composition ratio of Sr, La, Fe and Co in the first particulate ferrite compound phase is represented by the general formula:
Sr _{1-x '} La _x' Fe _{2n'-y '} Co _y'
(However, x ′ and y ′ representing the atomic ratio of Sr, La, Fe and Co and n ′ representing the molar ratio are
0.05 ≦ x ′ ≦ 0.3,
0.05 ≦ y ′ ≦ 0.3, and
5 ≦ n ′ ≦ 6
It is a numerical value that satisfies The ferrite sintered magnet characterized by the above-mentioned. The ferrite sintered magnet according to claim 6, wherein y ′ representing the atomic ratio of Co in the first particulate ferrite compound phase is:
0.1 ≦ y '≦ 0.2
A sintered ferrite magnet characterized by satisfying the following requirements. The ferrite sintered magnet according to any one of claims 3 to 7, wherein the composition ratio of Ca, La, (Ba + Sr), Fe, and Co in the second particulate ferrite compound phase is (Ba + Sr) is an A element. When general formula:
Ca _1- x`` <sub>-c</sub> La <sub>x ''</sub> A <sub>c</sub> Fe <sub>2n``-y ''</sub> Co _{y ''}
(However, x ″, c and y ″ representing the atomic ratio of Ca, La, A element, Fe and Co, and n ″ representing the molar ratio,
0.4 ≦ x '' ≦ 0.6,
0 ≦ c ≦ 0.2,
0 <y '' ≦ 0.2, and
4 ≦ n '' ≦ 6
It is a numerical value that satisfies The ferrite sintered magnet characterized by the above-mentioned. The ferrite sintered magnet according to claim 8, wherein y '' representing the atomic ratio of Co in the second particulate ferrite compound phase is:
0.1 ≦ y '' ≦ 0.2
A sintered ferrite magnet characterized by satisfying the following requirements. The ferrite sintered magnet according to claim 8, wherein y '' representing the atomic ratio of Co in the second particulate ferrite compound phase is:
0.1 <y '' ≦ 0.2
A sintered ferrite magnet characterized by satisfying the following requirements. The composition ratio of Sr, La, Fe and Co has the general formula: Sr _{1-x ′} La _{x ′} Fe _{2n′-y ′} Co _{y ′} (where x ′ representing the atomic ratio of Sr, La, Fe and Co y ′ and n ′ representing the molar ratio are numerical values satisfying 0.05 ≦ x ′ ≦ 0.3, 0.05 ≦ y ′ ≦ 0.3, and 5 ≦ n ′ ≦ 6.) And the composition ratio of Ca, La, (Ba + Sr), Fe, and Co, when (Ba + Sr) is an A element, the general formula: Ca _{1-x ″ -c} La _{x ″} A _c Fe _{2n ″ -y ''} Co _{y ''} (where x ″, c and y ″ representing the atomic ratio of Ca, La, A element, Fe and Co, and n ″ representing the molar ratio are 0.4 ≦ x ″. ≦ 0.6, 0 ≦ c ≦ 0.2, 0 <y ″ ≦ 0.2, and 4 ≦ n ″ ≦ 6.) The second ferrite calcined body represented by The total ratio of the calcined body and the second ferrite calcined body to 100% by mass is mixed so that the mixing ratio of the second ferrite calcined body is 10% by mass or more and less than 50% by mass. Mixing step of obtaining a compound,
Crushing the ferrite calcined body mixture to obtain a powder,
The manufacturing method of the ferrite sintered magnet characterized by including the shaping | molding process which shape | molds the said powder and obtains a molded object, and the baking process which bakes a molded object and obtains a sintered compact.   12. The method for producing a sintered ferrite magnet according to claim 11, wherein the first ferrite calcined body and the second ferrite calcined body have a mixing ratio of the second ferrite calcined body of 20 to 40 mass. %. A method for producing a sintered ferrite magnet, characterized in that mixing is performed so that the content becomes%. In the method for producing a ferrite sintered magnet according to claim 11 or 12, y 'representing the atomic ratio of Co in the first ferrite calcined body,
0.1 ≦ y '≦ 0.2
A method for producing a sintered ferrite magnet, characterized in that the numerical value satisfies the above. In the method for producing a sintered ferrite magnet according to any one of claims 11 to 13, y '' representing the atomic ratio of Co in the second ferrite calcined body,
0.1 ≦ y '' ≦ 0.2
A method for producing a sintered ferrite magnet, characterized in that the numerical value satisfies the above. In the method for producing a sintered ferrite magnet according to claim 14, y '' representing an atomic ratio of Co in the second ferrite calcined body,
0.1 <y '' ≦ 0.2
A method for producing a sintered ferrite magnet, characterized in that the numerical value satisfies the above. In the manufacturing method of the ferrite sintered magnet according to any one of claims 11 to 15, the composition ratio of Ca, La, Sr, Ba, Fe and Co of the ferrite sintered magnet is a general formula:
Sr _1-xab La _x Ca _a Ba _b Fe _2n-y Co _y
(However, x, a, b and y representing the atomic ratio of Sr, La, Ca, Ba, Fe and Co and n representing the molar ratio are
0.1 ≦ x ≦ 0.5,
0.04 ≦ a ≦ 0.5,
0 ≦ b ≦ 0.2,
0.2 ≦ 1-xab,
0.05 ≦ y ≦ 0.3, and
4 ≦ n ≦ 6
It is a numerical value that satisfies The method for producing a sintered ferrite magnet characterized by the following.