JP4919636B2 - Oxide magnetic material and sintered magnet - Google Patents

Description

  The present invention relates to an oxide magnetic material and a sintered magnet containing a ferrite having an M-type magnetoplumbite structure as a main phase, and methods for producing them.

Ferrite is a general term for compounds formed by divalent cation metal oxides and trivalent iron, and ferrite magnets are used in various applications such as various rotating machines and speakers. As a material of the ferrite magnet, Sr ferrite (SrFe ₁₂ O ₁₉ ) and Ba ferrite (BaFe ₁₂ O ₁₉ ) having a hexagonal magnetoplumbite structure are widely used. These ferrites are produced at a relatively low cost by powder metallurgy using iron oxide and carbonate such as strontium (Sr) or barium (Ba) as raw materials.

  In recent years, it has been proposed to improve the coercive force HcJ and the residual magnetic flux density Br by replacing a part of Sr in the Sr ferrite with a rare earth element such as La and a part of Fe with Co. (Patent Document 1, Patent Document 2).

Similarly to the case of Sr ferrite, it has been proposed to substitute part of Ca with rare earth elements such as La and substitute part of Fe with Co or the like in Ca ferrite (Patent Document 3). .
JP-A-10-149910 JP-A-11-154604 JP 2000-223307 A

Regarding Ca ferrite, the structure of CaO—Fe ₂ O ₃ or CaO-2Fe ₂ O ₃ is stable, and it is known that hexagonal ferrite is formed by adding La. However, the magnetic properties obtained are comparable to those of conventional Ba ferrite and are not sufficiently high. Therefore, Patent Document 3 discloses a Ca ferrite containing La and Co simultaneously in order to improve the residual magnetic flux density Br, the coercive force HcJ, and the temperature characteristics of the coercive force HcJ (hereinafter referred to as “CaLaCo ferrite”). Is disclosed.

In the CaLaCo ferrite Patent Document 3 discloses, by replacing part of Ca with rare earth elements such as La, and by substituting a part of Fe Co, etc., for the anisotropic magnetic field H _A can, Sr It has been reported that a value of 20 kOe or more, which is 10% or more higher than the anisotropic magnetic field H _{A of} ferrite, can be obtained.

According to the example, the CaLaCo ferrite disclosed in Patent Document 3 is Ca _1-x1 La _x1 (Fe _12-x1 Co _x1 ) _z O ₁₉ where x = y = 0 to 1 and z = 1. In this case, high characteristics are obtained at x = y = 0.4 to 0.6, and the values are as follows: Br = 4.0 kG (0.40 T), HcJ = 3.7 kOe (294 kA / m), When calcined in oxygen (oxygen 100%), Br = 4.0 kG (0.40 T) and HcJ = 4.2 kOe (334 kA / m).

  Further, in the above composition formula, when the value of z is shifted to 0.85 (x = 0.5, y = 0.43, x / y = 1.16), Br = 4.4 kG (0.44 T), HcJ = 3.9 kOe (310 kA / m), calcined in oxygen (oxygen 100%), Br = 4.49 kG (0.449 T), HcJ = 4.54 kOe (361 kA / m) The characteristics are obtained. The latter characteristic is the highest characteristic in Patent Document 3.

  According to Patent Document 1 and Patent Document 2, Sr ferrite 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 (hereinafter referred to as “SrLaCo ferrite”) has excellent magnetic properties. Therefore, they are being widely used in various applications in place of conventional Sr ferrite and Ba ferrite.

  The application in which the ferrite magnet is most used is a motor. If the magnetic characteristics of the ferrite magnet are improved, the output of the motor can be improved or the motor can be reduced in size. Therefore, the improvement of the residual magnetic flux density Br, the coercive force HcJ, and the maximum energy product (BH) max is very effective. Along with these characteristics, the squareness ratio (Hk / HcJ) must also be high. When the squareness ratio is low, the limit demagnetizing field strength becomes small, which causes a problem that demagnetization is easy. In particular, in motors, ease of demagnetization when a ferrite magnet is incorporated in a magnetic circuit is regarded as a problem, and in particular, both the coercive force HcJ (or the coercive force HcJ and the residual magnetic flux density Br) and the squareness ratio are both. There is a need for high performance ferrite magnets at a high level. It should be noted that Hk, which is a parameter to be measured in order to obtain the squareness ratio, is a position where 4πI becomes a value of 0.95Br in the second quadrant of the 4πI (magnetization strength) -H (magnetic field strength) curve. H axis reading. A value (Hk / HcJ) obtained by dividing Hk by HcJ of the demagnetization curve is defined as the squareness ratio.

  The CaLaCo ferrite according to Patent Document 3 shows excellent magnetic properties comparable to SrLaCo ferrite and is a material expected to be applied in the future, but has a problem that the squareness ratio (Hk / HcJ) is very low. As described above, according to Patent Document 3, the characteristics of Br = 4.49 kG (0.449T) and HcJ = 4.54 kOe (361 kA / m) are obtained in Table 2 of Example 2. The squareness ratio is only 80.6%.

FIG. 14 (Example 10) of Patent Document 3 describes the squareness ratio when Ca _1-x1 La _x1 Fe _12-x1 Co _x1 is set to x1 = 0 to 1. The squareness ratio at x = y = 0.4 to 0.6, which is a preferable range, is about 80%. When x1 is 0.8, the squareness ratio exceeds 85%, but the coercive force HcJ is rapidly reduced.

Further, FIG. 15 (Example 11) of Patent Document 3 describes the squareness ratio when Sr _0.4-x2 Ca _x2 La _0.6 Fe _11.4 Co _0.6 and x2 = 0, _0.2 , _0.4. The squareness ratio exceeds 90% at x2 = 0, 0.2 (region with a large amount of Sr), but the squareness ratio is 80% or less at x2 = 0.4 (total amount Ca). . At this time, the coercive force HcJ exhibits a behavior opposite to the squareness ratio, and the highest value is obtained when x2 = 0.4 (total amount Ca).

Thus, the CaLaCo ferrite according to Patent Document 3 has characteristics that exceed the SrLaCo ferrite in the anisotropic magnetic field _HA , and Br and HcJ have characteristics comparable to the SrLaCo ferrite, but the squareness ratio is very poor. It cannot satisfy both high coercive force and high squareness ratio, and has not yet been applied to various uses such as motors.

  An object of the present invention is to provide an oxide magnetic material and a sintered magnet that solve the problems of conventional CaLaCo ferrite, improve Br and HcJ, and exhibit a high squareness ratio.

  The above object is achieved by any of the following configurations.

(1) (1-x) CaO · ( x / 2) R 2 O 3 · (n-y / 2) is represented by Fe ₂ O ₃ · yMO,
R is at least one element selected from La, Nd, and Pr and must contain La,
M is at least one element selected from Co, Zn, Ni, and Mn, and necessarily contains Co;
X, y and n representing the molar ratio are respectively
0.4 ≦ x ≦ 0.6,
0.2 ≦ y ≦ 0.35,
4 ≦ n ≦ 6
And has a composition satisfying a relational expression of 1.4 ≦ x / y ≦ 2.5,
An oxide magnetic material mainly composed of ferrite having a hexagonal M-type magnetoplumbite structure.

(2) The oxide magnetic material according to (1), wherein 4.8 ≦ n ≦ 5.8.

(3) A sintered magnet containing the oxide magnetic material of (1) or (2).

(4) The sintered magnet according to (3), wherein the coercive force HcJ is 370 kA / m or more.

(5) The sintered magnet according to (3), wherein the residual magnetic flux density Br is 0.45 T or more.

(6) The sintered magnet according to (3), wherein the squareness ratio Hk / HcJ is 85% or more.

(7) The sintered magnet according to (6), wherein the squareness ratio Hk / HcJ is 90% or more.

(8) A method for producing an oxide magnetic material according to (1) or (2) above, wherein the oxide magnetic material comprises 0.2% by mass or less of H ₃ BO ₃ before and / or after calcination. Production method.

(9) The method for producing a sintered magnet according to (3) above, wherein before pulverization, SiO ₂ is added at 1.0% by mass or less and CaCO ₃ is added at 1.5% by mass or less in terms of CaO. Production method.

(10) A method for producing an oxide magnetic material according to (1) or (2) above, wherein the calcining atmosphere has an oxygen concentration of 5% or more.

(11) A method for manufacturing a sintered magnet according to (3) above, wherein the sintering atmosphere has an oxygen concentration of 10% or more.

(12) An oxide magnetic material mainly composed of Ca, La, Fe, and Co and having ferrite having a hexagonal M-type magnetoplumbite structure as a main phase and substantially including a heterogeneous phase containing a large amount of Co Oxide magnetic material not contained in

  According to the present invention, an oxide magnetic material having high Br, high HcJ, and a high squareness ratio can be provided.

  The coercive force HcJ obtained when a sintered magnet is produced from the oxide magnetic material according to the present invention achieves a value of 370 kA / m or more in a preferred configuration, and the residual magnetic flux density Br is 0.45 T or more in a preferred configuration. The value can be achieved.

  The squareness ratio when a sintered magnet is formed using an oxide magnetic material can be 85% or more in a preferable configuration, and 90% or more in a more preferable configuration.

  According to this invention, Br and HcJ exceeding SrLaCo ferrite according to Patent Document 1 and Patent Document 2 can be achieved.

  According to the present invention, the characteristics equivalent to or higher than those of Br and HcJ (the highest characteristics in Patent Document 3) when CaLaCo ferrite according to Patent Document 3 is fired in oxygen (100% oxygen) are easier and more stable than firing in oxygen. It can also be obtained by firing in the atmosphere where production is possible.

  The sintered magnet according to the present invention has a high Br, a high HcJ, and a high squareness ratio, and is therefore optimal for applications such as motors.

The oxide magnetic material according to the present invention is represented by the following formula.
Formula (1-x) CaO. (X / 2) R ₂ O _3. (Ny / 2) Fe ₂ O ₃ .yMO

We, CaLaCo ferrite, Noting that an anisotropic magnetic field H _A in excess of SrLaCo ferrite, and extensive research on improvement of CaLaCo ferrite. As a result, in the CaLaCo ferrite represented by the above formula, it is found that there is an optimum region for the molar ratio x (R) amount, molar ratio y (M) amount, and n value, and x and y are specified. It has been found that an oxide magnetic material having a high Br and a high HcJ and a high squareness ratio can be obtained by containing R and M so that the ratio is as follows. R and M will be described later.

  Patent Document 3 describes CaLaCo ferrite, but a preferable range of x and y is 0.4 to 0.6 from the description of the examples. The ratio of x and y is basically x = y (x / y = 1), and only examples of x / y = 1.05 and 1.16 are shown in the embodiment. In Patent Document 3, since the amounts of Fe and Co in the composition formula are expressed by z, there is no description about the n value.

  As described above, the CaLaCo ferrite of Patent Document 3 has a very low squareness ratio (Hk / HcJ) although it has a high Br and a high HcJ. This is because, in the case of CaLaCo ferrite, when x = y = 0.4 to 0.6, a heterogeneous phase containing a large amount of Co is generated in the crystal structure, and this heterogeneous phase causes a decrease in the squareness ratio. it is conceivable that.

  As a result of studying a composition that does not generate the heterogeneous phase, the present inventors determined that x is 0.4 to 0.6, y is 0.2 to 0.35 smaller than x, and x and y When the ratio is x / y = 1.4 to 2.5, a material having high Br and high HcJ is obtained. In a preferred embodiment of the present invention, HcJ of 370 kA / m exceeding the highest characteristic described in Patent Document 3 is obtained. As described above, characteristics of Br0.45T or more are realized. According to the present invention, a squareness ratio of 85% or more is obtained in a wide range of 4 ≦ n ≦ 6, and a squareness ratio of 90% or more is obtained in a range of 4.8 ≦ n ≦ 5.8. It was found that in the range of ≦ n ≦ 5.4, a material having the above-mentioned high Br and high HcJ and a squareness ratio of 90% or more can be obtained.

  The present invention relates to an improvement of CaLaCo ferrite, and Ca is an essential element. Basically, only Ca is used in place of Sr and Ba, but a part of Ca may be substituted with Sr and / or Ba to the extent that the magnetic properties do not deteriorate.

R is at least one element selected from La, Nd, and Pr, and must contain La. In addition to the above elements, the inclusion of elements having an ionic radius close to that of Sr ²⁺ , such as Ce, Sm, Eu, and Gd, is acceptable.

  M is at least one element selected from Co, Zn, Ni, and Mn, and must contain Co. Even elements other than the above can be allowed to be mixed as inevitable impurities.

  In the present invention, Co can be substituted with Zn, Ni, and Mn as described above, and SrLaCo disclosed in Patent Document 1 and Patent Document 2 can be substituted with any of Zn, Ni, and Mn. Br and HcJ exceeding ferrite can be achieved. In particular, by replacing Co with Ni, the manufacturing cost can be reduced without deteriorating the magnetic properties. Further, when Co is substituted with Zn, HcJ is slightly reduced, but Br can be improved. The substitution amount of Zn, Ni, and Mn is 50% or less of Co in molar ratio.

  x represents the content of R, and 0.4 ≦ x ≦ 0.6 is preferable. This is because when x is less than 0.4 and exceeds 0.6, the Br and squareness ratios are reduced.

  y represents the content of M, and 0.2 ≦ y ≦ 0.35 is preferable. As described above, in CaLaCo ferrite, the preferable range of y was considered to be 0.4 to 0.6, but a heterogeneous phase containing a large amount of Co in the crystal structure is generated. The present invention is characterized in that the range of y is 0.2 ≦ y ≦ 0.35, and x and y, which will be described later, are specified ratios. When y is less than 0.2, Br and HcJ decrease, and when it exceeds 0.35, a heterogeneous phase containing a large amount of Co is generated, and HcJ decreases.

The n value that defines the ratio of CaO, R ₂ O ₃ and Fe ₂ O ₃ , MO is preferably 4 ≦ n ≦ 6. Within this range, a squareness ratio (Hk / HcJ) of 85% or more is obtained. Furthermore, it is preferably 4.8 ≦ n ≦ 5.8, and a squareness ratio of 90% or more is obtained. When the n value is within this range and x and y are within the above preferred ranges, characteristics of Br = 0.45T or more and HcJ = 370 kA / m (4.65 kOe) or more can be obtained. In the most preferable range, the above characteristics can be obtained and a squareness ratio of 95% or more can be obtained. The squareness ratio is a value when a sintered magnet is used because it is difficult to measure with a calcined body after calcining.

  Next, the manufacturing method of the oxide magnetic material of this invention is demonstrated.

First, raw material powders such as CaCO ₃ , Fe ₂ O ₃ , La ₂ O ₃ , and Co ₃ O ₄ are prepared. Based on the above-described composition formula, the prepared powder is blended so that x, y, and n are each in a preferable range. In addition to the oxide and carbonate, the raw material powder may be a hydroxide, nitrate, chloride, or the like, or may be in a solution state. Moreover, when manufacturing a sintered magnet, raw material powders other than CaCO ₃ , Fe ₂ O ₃ and La ₂ O ₃ may be added from the time of raw material mixing, or added after calcination described later. Also good. For example, CaCO ₃ , Fe ₂ O ₃ , La ₂ O ₃ may be blended, mixed, and calcined, then Co ₃ O _{4 and the} like may be added and pulverized, and then molded and sintered. Moreover, in order to promote the reactivity at the time of calcination, about 1% by mass of a compound containing B ₂ O ₃ , H ₃ BO ₃ or the like may be added as necessary.

In particular, the addition of H ₃ BO ₃ is effective for improving HcJ and Br. The amount of H ₃ BO ₃ added is preferably 0.2% by mass or less. The most preferable value of the addition amount is in the vicinity of 0.1% by mass, and when the n value, x, and y are in the above-described preferable ranges, characteristics of Br = 0.45T or more and HcJ = 370 kA / m or more are obtained. . When the amount of H ₃ BO ₃ added is less than 0.1% by mass, the improvement of Br becomes remarkable. However, when the amount added exceeds 0.1% by mass, the improvement of HcJ becomes remarkable. If the amount exceeds 0.2% by mass, Br is lowered, which is not preferable. Therefore, 0.05% by weight to 0.15% by weight of H ₃ BO ₃ addition is preferable for applications that place importance on Br, and 0.10% by weight to 0.20% by weight when used for uses that place importance on HcJ. % H ₃ BO ₃ addition is preferred. Since H ₃ BO ₃ also has effects such as control of crystal grains during sintering, it is also effective to add it after calcination (before fine pulverization or before sintering). It can also be added both later.

  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 dispersing 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 become a mixed raw material powder.

  The mixed raw material powder is heated using an electric furnace, a gas furnace or the like, and a magnetoplumbite type ferrite compound is formed by a solid phase reaction. 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. This is because the solid phase reaction hardly proceeds when the oxygen concentration is less than 5%. A more preferable oxygen concentration is 20% or more.

  In the calcination step, a ferrite phase is formed by a solid phase reaction with an increase in temperature and is completed at about 1100 ° C., but below this temperature, unreacted hematite (iron oxide) remains and the magnet characteristics are low. When the temperature exceeds 1100 ° C., the effect of the present invention occurs. 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 a long time for the pulverization process may occur. Therefore, the calcination temperature is preferably 1100 ° C to 1450 ° C. More preferably, it is 1200 to 1350 degreeC. The calcining 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 can be performed at 1100 ° C. to 1300 ° C.

The calcined body obtained by the calcining step has a main phase of hexagonal M-type magnetoplumbite type ferrite represented by the following chemical formula, and becomes the oxide magnetic material of the present invention.
Formula (1-x) CaO. (X / 2) R ₂ O _3. (Ny / 2) Fe ₂ O ₃ .yMO
0.4 ≦ x ≦ 0.6, 0.2 ≦ y ≦ 0.35, 4 ≦ n ≦ 6.

  By pulverizing and / or crushing such a calcined body, a magnetic powder can be obtained, which can be applied to a bond magnet or a magnetic recording medium. In addition, manufacture of said calcined body can also employ | adopt well-known manufacturing techniques, such as a spray pyrolysis method and a coprecipitation method.

  When the magnetic powder is applied to a bonded magnet, the magnetic powder is mixed with flexible rubber, hard light plastic, or the like and then molded. The molding process may be performed by a method such as injection molding, extrusion molding, or roll molding. Moreover, when applying magnetic powder to a bond magnet, in order to relieve | moderate the crystal distortion of magnetic powder, it is preferable to heat-process in the temperature range of 700 to 1100 degreeC for about 0.1 to 3 hours. A more preferable temperature range is 900 ° C to 1000 ° C.

  In addition, when applying magnetic powder to a magnetic recording medium, after applying the above heat treatment to the magnetic powder, it is possible to prepare a coating type magnetic recording medium by kneading with various known binders and applying to a substrate. it can. Moreover, the thin film magnetic layer used for a magnetic recording medium can also be formed by sputtering method etc. using the oxide magnetic material of this invention and the sintered magnet using the same as a target.

  Next, the manufacturing method of the sintered magnet using the said oxide magnetic material is demonstrated.

  The calcined body is finely pulverized by a vibration mill, a ball mill and / or an attritor into fine particles. The average particle size of the fine particles is preferably about 0.4 to 0.8 μm (air permeation method). The fine 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) 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 wt% to 2.0 wt% or less of various known dispersants and surfactants in the slurry in a solid content ratio. After the wet pulverization, the slurry is preferably concentrated and kneaded.

In the fine pulverization step, additives such as CaCO ₃ , SiO ₂ , Cr ₂ O ₃ , and Al ₂ O ₃ can be added to the calcined body in order to improve magnetic properties. When these additives are added, CaCO ₃ is 0.3 to 1.5% by mass in terms of CaO, 0.2 to 1.0% by mass of SiO ₂ , 5.0% by mass or less of Cr ₂ O ₃ , Al ₂ O ₃ is preferably 5.0% by mass or less.

Addition of CaCO ₃ and SiO _{2 is} particularly preferable, and high Br and high HcJ can be obtained by using together with the addition of H ₃ BO ₃ . Since SiO ₂ also has effects such as control of crystal grains during calcination, it is effective to add it before calcination, and it can be added both before calcination and before pulverization.

  Next, it press-molds in a magnetic field or without a magnetic field, removing the solvent in a slurry. By press molding in a magnetic field, the crystal orientations of the powder particles can be aligned (oriented). Magnetic properties can be dramatically improved by press molding in a magnetic field. Furthermore, in order to improve the orientation, 0.01 to 1.0% by mass of a dispersant and a lubricant can be added.

  The molded body obtained by press molding is subjected to a degreasing process as necessary and then a sintering process. The sintering process is performed using an electric furnace, a gas furnace, or the like.

  The sintering process 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 or heterogeneous phase generation is caused, and the magnetic properties are deteriorated. A more preferable oxygen concentration is 20% or more, and most preferable is an oxygen concentration of 100%.

  The oxide magnetic material of the present invention exhibits magnetic characteristics equivalent to or better than those obtained by firing CaLaCo ferrite in oxygen (100% oxygen) according to Patent Document 3 even in the atmosphere, as in the examples described later. Therefore, further excellent magnetic properties can be obtained by performing baking in oxygen similar to the baking in oxygen disclosed in Patent Document 3.

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

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

[Example 1]
In the formula (1-x) CaO. (X / 2) La ₂ O _3. (Ny / 2) Fe ₂ O ₃ .yCoO, x = 0.5, 1 ≦ x / y, 0 ≦ y ≦ 0 0.5, n = 5.4, CaCO ₃ powder, La ₂ O ₃ powder, Fe ₂ O ₃ powder (particle size 0.6 μm), and Co ₃ O ₄ were prepared, and each powder was blended. . The obtained raw material powder was mixed in a wet ball mill for 4 hours, dried and sized. Subsequently, it was calcined at 1300 ° C. for 3 hours in the air to obtain a powdery calcined body.

Next, with respect to the calcined body, 0.6% by mass of CaCO ₃ powder in terms of CaO and 0.45% by mass of SiO ₂ powder are added, and a wet ball mill using water as a solvent is averaged by an air permeation method. Fine grinding until the particle size was 0.55 μm. While removing the solvent in the finely pulverized slurry, press molding was performed in a magnetic field. The press molding was performed so that the pressing direction of the press and the magnetic field direction were parallel, and the magnetic field strength was 13 kOe. The obtained molded body was sintered in the atmosphere at 1150 ° C. for 1 hour to obtain a sintered magnet.

  The magnetic properties of the obtained sintered magnet were measured. FIG. 1 shows the measurement results of residual magnetic flux density Br, coercive force HcJ, and squareness ratio Hk / HcJ, where the horizontal axis represents the relative ratio x / y of x and y (La and Co). Moreover, the measurement result of Br, HcJ, and Hk / HcJ with the addition amount of y on the horizontal axis is shown in FIG.

  As is clear from FIG. 1, when x / y is too small, HcJ and Hk / HcJ decrease due to the presence of a heterogeneous phase, and x / y is about 1.25 or less and HcJ is below 340 kA / m (4.27 kOe). 1.4 or less, Hk / HcJ was less than 85%. When x / y was too large, Br and HcJ decreased, and x / y was approximately 2.5 or more, Br was 0.44 T, and HcJ was less than 340 kA / m (4.27 kOe). Conventionally, x / y has been best near 1 due to the charge correction relationship of La and Co. However, the CaLaCo ferrite according to the present invention has high magnetic characteristics near 1.4 ≦ x / y ≦ 2.5. You can see that

  As is clear from FIG. 2, when the amount of Co substitution is too small, Br and HcJ decrease, y is about 0.2 or less, Br is 0.44 T, and HcJ is 340 kA / m (4.27 kOe). Below. If the amount of y is too large, HcJ and Hk / HcJ decrease due to the presence of a heterogeneous phase. When y is approximately 0.4 or more, HcJ is less than 340 kA / m (4.27 kOe), and when approximately 0.35 or more, Hk / HcJ. Was less than 85%. According to the present invention, it can be seen that high magnetic properties are obtained in the vicinity of 0.20 ≦ y ≦ 0.35.

[Example 2]
In the formula (1-x) CaO · ( x / 2) La 2 O 3 · (n-y / 2) Fe 2 O 3 · yCoO, x = 0.5, y = 0.3, x / y = 1 A sintered magnet was produced in the same manner as in Example 1 except that .67, 3.6 ≦ n ≦ 6.0. The magnetic properties of the obtained sintered magnet were measured. FIG. 3 shows the measurement results of the residual magnetic flux density Br, the coercive force HcJ, and the squareness ratio Hk / HcJ, where n is the horizontal axis.

  As is clear from FIG. 3, a high squareness ratio of 85% or more is shown in the range of 4.0 ≦ n ≦ 6.0, and a high squareness of 90% or more in the range of 4.8 ≦ n ≦ 5.8. Further, in the range of 5.0 ≦ n ≦ 5.4, high magnetic characteristics with Br of 0.44 T and HcJ of 340 kA / m (4.27 kOe) or more can be obtained, and when n = 5.2 The characteristics of HcJ370 kA / m or more and Br0.45 or more can be obtained.

[Example 3]
Table 1 shows the magnetic characteristics when the sintering temperature was changed from 1150 ° C. to 1190 ° C. with the composition of n = 5.2 in Example 2.

  As is apparent from Table 1, a high HcJ of 370 kA / m (4.65 kOe) on the low temperature side and a high Hk / HcJ of 95% or more are obtained on the low temperature side, and a high Br, 90 of 0.46 T or higher on the high temperature side. % Or more of Hk / HcJ was obtained.

[Example 4]
In the formula (1-x) CaO. (X / 2) La ₂ O _3. (Ny / 2) Fe ₂ O ₃ .yCoO, 0 ≦ x ≦ 1, y = 0.3, n = 5.2 A sintered magnet was produced in the same manner as in Example 1 except that. The magnetic properties of the obtained sintered magnet were measured. FIG. 4 shows the measurement results of the residual magnetic flux density Br, the coercive force HcJ, and the squareness ratio Hk / HcJ where the added amount of x is taken on the horizontal axis.

  As is clear from FIG. 4, Br and Hk / HcJ are extremely deteriorated when the amount of x is too small or too large. It can be seen that 95% high Hk / HcJ and high Br and HcJ are obtained in the vicinity of 0.4 ≦ x ≦ 0.6.

[Example 5]
In the formula (1-x) CaO · ( x / 2) La 2 O 3 · (n-y / 2) Fe 2 O 3 · yCoO, x = 0.5, y = 0.3,0.2, x A sintered magnet was produced in the same manner as in Example 1 except that /y=1.67, 2.5, and n = 5.2. Component analysis by EPMA was performed on the obtained sintered magnet. The analysis results are shown in FIG. 5 (in the case of x / y = 1.67) and FIG. 6 (in the case of x / y = 2.5). The analysis by EPMA was performed using an EPMA apparatus (EPMA1610 manufactured by SHIMADZU) under the conditions of an acceleration voltage of 15 kV, a sample current of 0.1 μA, and an irradiation range of φ100 μm (electron beam diameter).

  As apparent from FIGS. 5 and 6, the sintered magnet according to the present invention does not show a heterogeneous phase containing a large amount of Co. Therefore, high magnetic characteristics as shown in the first to fourth embodiments can be obtained.

[Comparative Example 1]
In the formula (1-x) CaO · ( x / 2) La 2 O 3 · (n-y / 2) Fe 2 O 3 · yCoO, x = 0.5, y = 0.5, x / y = 1 A sintered magnet was produced in the same manner as in Example 1 except that n = 5.4. Component analysis by EPMA was performed on the obtained sintered magnet. The analysis results are shown in FIG. The EPMA conditions are the same as in Example 5.

  As is clear from FIG. 7, the sintered magnet according to the comparative example has a large number of heterogeneous phases (name spots in the photograph at the right end of the lower stage in FIG. 7) containing a large amount of Co. When the magnetic properties of the sintered magnet were measured, Br = 0.441T, HcJ = 325.5 kA / m (4.09 kOe), Hk / HcJ = 63%, and in particular, Hk / HcJ was deteriorated. . This is presumably because a heterogeneous phase containing a large amount of Co exists.

[Example 6]
In the formula (1-x) CaO · ( x / 2) La 2 O 3 · (n-y / 2) Fe 2 O 3 · yCaO, x = 0.5, y = 0.3, x / y = 1 .67, prepare CaCo ₃ powder, La ₂ O ₃ powder, Fe ₂ O ₃ powder (particle size 0.6 μm), and Co ₃ O ₄ powder so that n = 5.2, and blend each powder Further, 0 to 0.2% by mass of H ₃ BO ₃ powder was added to the blended powder. The obtained raw material powder was mixed in a wet ball mill for 4 hours, dried and sized. Subsequently, it calcined at 1150 degreeC for 3 hours in air | atmosphere, and obtained the powdery calcined body.

Next, with respect to the calcined body, 0.6% by mass of CaCO ₃ powder in terms of CaO and 0.45% by mass of SiO ₂ powder are added, and a wet ball mill using water as a solvent is averaged by an air permeation method. Fine grinding until the particle size was 0.55 μm. While removing the solvent from the finely pulverized slurry, press molding was performed in a magnetic field. The press molding was performed so that the pressing direction of the press and the magnetic field direction were parallel, and the magnetic field strength was 13 kOe. The obtained molded body was sintered in the atmosphere at 1200 ° C. for 1 hour to obtain a sintered magnet.

The magnetic properties of the obtained sintered magnet were measured. FIG. 8 shows the measurement results of the residual magnetic flux density Br, the coercive force HcJ, and the squareness ratio Hk / HcJ where the amount of H ₃ BO ₃ added is taken on the horizontal axis.

As is apparent from FIG. 8, when H ₃ BO ₃ is 0.1% by mass, excellent characteristics can be obtained for both Br and HcJ. When H ₃ BO ₃ is less than 0.1% by mass, Br is improved and HcJ is lowered. On the other hand, it can be seen that when the content exceeds 0.1% by mass, HcJ is improved and Br is decreased. The squareness ratio is 85% or more.

[Example 7]
Example 6 except that 0.1% by mass of H ₃ BO ₃ powder, 0.5 to 0.9% by mass of CaCO ₃ powder in terms of CaO, and 0.3 to 0.9% by mass of SiO ₂ powder are added. A sintered magnet was produced in the same manner. The magnetic properties of the obtained sintered magnet were measured. FIG. 9 shows the measurement results of the residual magnetic flux density Br, the coercive force HcJ, and the squareness ratio Hk / HcJ with the addition amount of SiO ₂ on the horizontal axis. In the figure, the black circle shows the case of CaO 0.5 mass%, the black triangle shows the CaO 0.7 mass%, and the black square shows the case of CaO 0.9 mass%.

From FIG. 9, it can be seen that the CaLaCo ferrite of the present invention exhibits excellent characteristics when the CaCO ₃ addition amount is around 0.7 mass% in terms of CaO and the SiO ₂ addition amount is around 0.6 weight.

[Example 8]
0.1 mass% of H ₃ BO ₃ powder, 0.7 mass% of CaCO ₃ powder in terms of CaO and 0.6 mass% of SiO ₂ powder are added, calcining temperature is 1225 ° C., sintering temperature is 1190 ° C. A sintered magnet was produced in the same manner as in Example 1 except that the temperature was 1200 ° C. Table 2 shows the results of measuring the magnetic properties of the obtained sintered magnet.

It can be seen that even more excellent Br and HcJ can be obtained by setting the calcination temperature and the sintering temperature as preferable conditions in the preferable addition amounts of CaCO ₃ and SiO ₂ according to Example 7.

[Example 9]
In the formula (1-x) CaO. (X / 2) La ₂ O _3. (Ny / 2) Fe ₂ O ₃ .yCaO.y′NiO, x = 0.5, y + y ′ = 0.3, CaCO ₃ powder, La ₂ O ₃ powder, Fe ₂ O ₃ powder (particle diameter 0.6 μm), so that y ′ = 0 to 0.1, x / y = 1.67, and n = 5.2. NiO powder and Co ₃ O ₄ powder were prepared, each powder was blended, and 0.1% by mass of H ₃ BO ₃ powder was further added to the blended powder. The obtained raw material powder was mixed in a wet ball mill for 4 hours, dried and sized. Subsequently, it calcined at 1150 degreeC for 3 hours in air | atmosphere, and obtained the powdery calcined body.

Next, 0.7% by mass of CaCO ₃ powder in terms of CaO and 0.6% by mass of SiO ₂ powder are added to the calcined body, and a wet ball mill using water as a solvent is averaged by an air permeation method. Fine grinding until the particle size was 0.55 μm. While removing the solvent from the finely pulverized slurry, press molding was performed in a magnetic field. The press molding was performed so that the pressing direction of the press and the magnetic field direction were parallel, and the magnetic field strength was 13 kOe. The obtained molded body was sintered in the atmosphere at 1190 ° C. for 1 hour to obtain a sintered magnet.

  The magnetic properties of the obtained sintered magnet were measured. FIG. 10 shows the measurement results of the residual magnetic flux density Br, the coercive force HcJ, and the squareness ratio Hk / HcJ with y ′ (NiO amount) on the horizontal axis.

  As is clear from FIG. 10, even if Co is replaced with Ni, neither Br nor HcJ is significantly reduced. Since Ni is less expensive than Co, it is possible to reduce the manufacturing cost without deteriorating the magnetic properties by substituting Co with Ni.

  The oxide magnetic material of the present invention is suitable not only for the residual magnetic flux density Br and the coercive force HcJ but also for its high squareness ratio, and is therefore suitably used for high performance motor applications.

In (1-x) CaO · ( x / 2) La 2 O 3 · (n-y / 2) Fe 2 O 3 · yCoO composition, and n = 5.4, the substitution amount x of La, the Co The ratio x / y of the substitution amount y is changed from 1.0 to 5.0, and the relationship between the composition ratio x / y and the residual magnetic flux density Br, coercive force HcJ and Hk / HcJ of the sintered magnet is shown. It is a graph to show. In the composition of (1-x) CaO. (X / 2) La ₂ O _3. (Ny / 2) Fe ₂ O ₃ .yCoO, x = 0.50, n = 5.4, and y is 0. 3 is a graph showing the relationship between the composition y and the residual magnetic flux density Br, coercive force HcJ, and Hk / HcJ of the sintered magnet. (1-x) in the CaO · (x / 2) La 2 O 3 · (n-y / 2) Fe 2 Composition of _{O 3 · yCoO, x = 0.50} , and y = 0.30, the n 3 6 is a graph showing the relationship between the composition n and the residual magnetic flux density Br, coercive force HcJ, and Hk / HcJ of the sintered magnet, which was changed from 6.0 to 6.0. In the composition of (1-x) CaO. (X / 2) La ₂ O _3. (Ny / 2) Fe ₂ O ₃ .yCoO, 0.00 ≦ x ≦ 1.0, y = 0.3, It is n = 5.2 and is a graph showing the relationship between the composition x and the residual magnetic flux density Br, the coercive force HcJ and Hk / HcJ of the sintered magnet. In the composition of (1-x) CaO. (X / 2) La ₂ O _3. (Ny / 2) Fe ₂ O ₃ .yCoO, x = 0.50, y = 0.30, x / y = 1. It is an EPMA image of a sintered body with 1.67 and n = 5.2, showing an SEI, BEI image, an Fe X-ray image from the upper left side, and an X-ray image of La, Ca, Co from the lower left side. In (1-x) CaO · ( x / 2) La 2 O 3 · (n-y / 2) the composition of _{Fe 2 O 3 · yCoO, x} = 0.50, y = 0.20, x / y = 2 is an EPMA image of a sintered body with 2.50 and n = 5.2, showing an SEI, BEI image, an Fe X-ray image from the upper left side, and an X-ray image of La, Ca, Co from the lower left side. In the composition of (1-x) CaO. (X / 2) La ₂ O _3. (Ny / 2) Fe ₂ O ₃ .yCoO, x = y = 0.5, x / y = 1, n = 5 is an EPMA image of the sintered body of 5.4, showing an SEI, BEI image, an Fe X-ray image from the upper left side, and an X-ray image of La, Ca, Co from the lower left side. And H ₃ BO ₃ added amount, the residual magnetic flux density Br of the sintered magnet, is a graph showing the relationship between the coercivity HcJ, and squareness ratio Hk / HcJ. And CaO addition amount and additive amount of SiO _2, the residual magnetic flux density Br of the sintered magnet, is a graph showing the relationship between the coercivity HcJ, and squareness ratio Hk / HcJ. It is a graph which shows y '(NiO amount), the residual magnetic flux density Br of a sintered magnet, coercive force HcJ, and squareness ratio Hk / HcJ.

Claims (11)

Represented by the formula (1-x) CaO. (X / 2) R ₂ O _3. (N−y / 2) Fe ₂ O ₃ .yMO,
R is at least one element selected from La, Nd, and Pr and must contain La;
M is at least one element selected from Co, Zn, Ni, and Mn and must contain Co;
X, y and n representing the molar ratio are respectively
0.4 ≦ x ≦ 0.6,
0.2 ≦ y ≦ 0.35,
4 ≦ n ≦ 5.8
And has a composition satisfying a relational expression of 1.4 ≦ x / y ≦ 2.5,
An oxide magnetic material mainly composed of ferrite having a hexagonal M-type magnetoplumbite structure.   The oxide magnetic material according to claim 1, wherein 4.8 ≦ n ≦ 5.8.   A sintered magnet containing the oxide magnetic material according to claim 1.   The sintered magnet according to claim 3, wherein the coercive force HcJ is 370 kA / m or more.   The sintered magnet according to claim 3, wherein the residual magnetic flux density Br is 0.45T or more.   The sintered magnet according to claim 3, wherein the squareness ratio Hk / HcJ is 85% or more.   The sintered magnet according to claim 3, wherein the squareness ratio Hk / HcJ is 90% or more. Represented by the formula (1-x) CaO. (X / 2) R ₂ O _3. (N−y / 2) Fe ₂ O ₃ .yMO,
R is at least one element selected from La, Nd, and Pr and must contain La;
M is at least one element selected from Co, Zn, Ni, and Mn and must contain Co;
X, y and n representing the molar ratio are respectively
0.4 ≦ x ≦ 0.6,
0.2 ≦ y ≦ 0.35,
4 ≦ n ≦ 5.8
And has a composition satisfying a relational expression of 1.4 ≦ x / y ≦ 2.5,
A method for producing an oxide magnetic material having a ferrite phase having a hexagonal M-type magnetoplumbite structure as a main phase,
Preparing a raw material powder of the element;
Blending raw material powder,
Mixing raw material powders,
A process of calcining mixed raw material powder,
Calcining step before and / or method of manufacturing an oxide magnetic material temporary after heating step the H ₃ BO ₃ is added 0.2 mass% or less. Represented by the formula (1-x) CaO. (X / 2) R ₂ O _3. (N−y / 2) Fe ₂ O ₃ .yMO,
R is at least one element selected from La, Nd, and Pr and must contain La;
M is at least one element selected from Co, Zn, Ni, and Mn and must contain Co;
X, y and n representing the molar ratio are respectively
0.4 ≦ x ≦ 0.6,
0.2 ≦ y ≦ 0.35,
4 ≦ n ≦ 5.8
And has a composition satisfying a relational expression of 1.4 ≦ x / y ≦ 2.5,
A method for producing a sintered magnet containing an oxide magnetic material having a main phase of a ferrite phase having a hexagonal M-type magnetoplumbite structure,
Preparing a raw material powder of the element;
Blending raw material powder,
Mixing raw material powders,
Calcination of mixed raw material powder,
Crushing the calcined body,
Process of forming the pulverized powder
Comprising the step of sintering the compact,
A method for producing a sintered magnet in which SiO ₂ is added at 1.0% by mass or less and CaCO ₃ is added at 1.5% by mass or less in terms of CaO before the step of grinding the calcined body . The method for producing an oxide magnetic material according to claim 8, wherein the calcining atmosphere has an oxygen concentration of 5% or more in the step of calcining the mixed raw material powder . The method for producing a sintered magnet according to claim 9, wherein in the step of sintering the formed body, the sintering atmosphere has an oxygen concentration of 10% or more.