JPH0124733B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Ca-Pb-La-based oxide magnet material, and more specifically, it has magnetic properties equivalent to or better than conventional barium-based or strontium-based ferrite magnets, and is mechanically resistant. This invention relates to an oxide permanent magnet that has the remarkable property of being easily oriented.

As ferrite oxide permanent magnets, barium-based or strontium-based ferrites are well known and have been widely industrialized, but research reports have been made on many other systems. For example, the present inventors previously discovered that the Ca-La ferrite (CaO 6F ₅ O ₃ ) ₉₇ (La ₂ O ₃ ) ₃ compound was
We discovered that it has magnetic properties equivalent to those of ferrite-based ferrite magnets.
We also proposed an oxide permanent magnet substituted with
−130862).

After that, the present inventors conducted extensive experimental research on various materials and conditions with the aim of improving the magnetic properties of the Ca-La ferrite magnets mentioned above.
The oxide magnet material, in which a portion of the magnet is replaced with PbO, has the extremely unique property of being mechanically oriented easily (anisotropy occurs even when the isotropic manufacturing method of simply press-forming occurs). This led to the completion of the present invention.

That is, the object of the present invention is to easily obtain mechanical directionality (anisotropy) and to have magnetic properties comparable to or better than conventionally known Ba and Sr magnets.
The object of the present invention is to provide a new oxide permanent magnet material that can be easily processed in various ways, such as by lowering the calcination temperature.

The present invention, which can achieve such objects,
(CaO _1-x PbO _x 6Fe ₂ O ₃ ) _100-y (La ₂ O ₃ ) Ca-Pb-La represented by the composition formula _y , where x is 0.2 to 0.8 and y is 2 to 5. It is an oxide permanent magnet material.

The present invention will be explained in more detail below. Basically, as described above, the present invention is a Ca-La based oxide permanent magnet material in which a part of the calcium oxide is replaced with lead oxide, and (CaO _1-x
It is expressed by the chemical formula PbO _x 6Fe ₂ O ₃ ) _100-y (La ₂ O ₃ ) _y . Here, the content y (mol%) of lanthanum oxide is selected in the range of 2 to 5. The reason for this is that if the content of lanthanum oxide is less than 2 mol%, the crystal form of the compound represented by the above chemical formula will not be hexagonal (magnetoplumbite system), and the magnetic properties will be significantly reduced. This is because even if the content of lanthanum oxide exceeds 5 mol % or less, the magnetic properties deteriorate, and addition of a large amount of expensive lanthanum oxide is not preferable from an economical point of view. In terms of magnetic properties, it is most preferable for the lanthanum oxide content to be 2.5 to 3 mol% within the above range.

Next, the amount of lead oxide to replace calcium oxide x
is selected to be 0.2 or more and less than 0.8. The reason for this range will be clear from FIG. Figure 1 shows (CaO _1-x PbO _x 6Fe ₂ O ₃ ) ₉₇ (La ₂ O ₃ ) ₃ magnet.
This is a graph plotting the relationship between composition and average magnetic properties when fired at 1200°C for 30 minutes. The maximum energy product (B・H) max is approximately three times the value for the composition where x = 0.1 compared to the composition where x = 0, which is
This value is equivalent to Ba and Sr ferrite magnets.
When the amount of PbO substitution increases further, (B·H)max further increases, and when x is 0.2 or more and less than 0.8, it exhibits very good magnetic properties that are equivalent to or better than Ba and Sr ferrite magnets. The amount of PbO substitution increases further x = 0.8
When it reaches ~0.9, (B·H)max tends to decrease. This increases the substituent x of PbO to 0.2 or more, 0.8
This is the reason why it was set to less than 20%. In particular, in compositions where the PbO substitution amount
max has been obtained, which is the most preferable range.

Now, what is noteworthy about the present invention is that the composition as described above has the characteristic that mechanical directionality is easily imparted. As mentioned above, for example
When the substitution amount X of PbO to CaO is 0.5, (B・
H) max is 1.5MG・Oe or more, which is a very large value for an isotropic magnet, and 4πIr at this time is
Since the samples showed high values of 2700 to 2850G, these samples were cut into cubes and the magnetic properties in the press direction and in the direction perpendicular to it were measured. The situation is shown in Figure 2. Figure A shows a hysteresis curve in the press direction, and Figure B shows a hysteresis curve in a direction perpendicular to the press direction. As can be seen from Figure 2, the anisotropy is clearly obtained, and even the isotropic manufacturing method of simply press forming produces anisotropy.In other words, these types of magnetic materials are mechanically This suggests that it is easy to find direction.

In other words, the oxide magnet material according to the present invention is extremely remarkable in that an anisotropic magnet can be obtained simply by pressure molding with a normal press, without using a complicated manufacturing method such as a magnetic field molding method. It has the following characteristics. Incidentally, such properties have not been observed at all in the oxide permanent magnet materials in which CaO is replaced with BaO or SrO as described in connection with the prior art.

Furthermore, this is applicable not only when the oxide magnet material according to the present invention is used as a sintered type magnet, but also when the oxide magnet material powder is mixed with an organic binder such as rubber or plastic and molded into so-called plastics. It is also useful when used as a magnet. This is because anisotropy is likely to occur during rolling with rollers or pressure molding with a press, making it possible to obtain a product with good magnetic properties.

Next, examples of the present invention will be described. The raw materials used in the experiment were CaCO ₂ , PbO, α-Fe ₂ O ₃ ,
It is a powder of La ₂ O ₃ . The composition is (CaO _1-x PbO _x・
In the composition formula of 6F ₂ O ₃ ) ₉₇ (La ₂ O ₃ ) ₃ , x is varied in various ways. Weighed the raw material powder to have the above composition and weighed 300g.
These were mixed in a ball mill (wet method) for 3 hours. After drying the mixed powder, it is heated at a pressure of about 0.5t/cm ² for 30
It was molded into a cylindrical sample of mmφ×6 mm. These molded samples were calcined for 1 hour in a dry oxygen temperature range of 900 to 1100° C. using a Tecorundum tubular furnace. Next, these pre-fired samples were crushed using a stainless steel mortar, passed through a 100 mesh sieve, and then processed using a stainless steel ball mill (wet method).
Grind for 30 hours. After drying the muddy calcined powder thus crushed, 5% polyvinyl alcohol solution (concentration 5%) was added to these powders, mixed, and pressed at a press pressure of about 2/cm ² to form a powder with a diameter of 13 mmφ and a height of 11~ 13
It was molded into a cylindrical shape of mm. The main firing was carried out in dry oxygen at 1175-1300°C for 30 minutes using a Tecorundum tubular furnace. An example of the measurement results of the obtained sample is shown in the above-mentioned FIG. 1. As can be seen from the figure, the oxide magnet material according to the present invention is characterized by a large maximum energy product (B·H) max and a high residual magnetic flux density (4πIr). Although not shown, it has also been found that the pre-calcination temperature can be lowered by replacing CaO with a small amount of PbO. That is, Ca without substitution with PbO
- In the case of La-based magnets, magnetic properties comparable to or better than those obtained when pre-sintered at high temperatures (1200°C or higher) can be obtained even under pre-sintered conditions of 900 to 1100°C; It has also become clear that the temperature can be lowered by about 400 to 100°C.

Among these, (CaO _0.5 PbO _0.5・6Fe ₂ O ₃ ) ₉₇
(La ₂ O ₃ ) ₃ composition (in terms of mole fraction,
CaO……6.93 mol%, PbO……6.93 mol%,
Fe ₂ O ₃ ......83.14 mol%, La ₂ O ₃ ...... 3 mol%
Temporary firing at 1000℃ x 1 hour, main firing at 1225℃
℃×30 minutes, residual magnetic flux density Br = 2850G, coercive force _B H _C = 1300Oe, maximum energy product (B・H)
It exhibits excellent magnetic properties of max=1.52MG・Oe, and has mechanical anisotropy as shown in Figure 2. The degree of this anisotropy is 1.5 Mg.Oe or more in the press pressing direction, and about 1.0 MG.Oe in the direction perpendicular to the pressing direction.

Furthermore, the oxide permanent magnet material according to the present invention can be given even better magnetic properties by using a manufacturing method that inherently imparts anisotropy, such as magnetic field forming.

Since the present invention is a Ca-Pb-La based oxide permanent magnet material having the above-mentioned composition, it is easy to obtain mechanical orientation, and therefore an anisotropic magnet can be obtained only by ordinary press molding. It is a material that is useful not only as sintered permanent magnets but also as plastic magnets, and has magnetic properties comparable to or better than conventionally known Ba and Sr magnets, and can be heated at a lower calcination temperature. It is easy to manufacture and has many advantages as a magnet for motors or speakers.

[Brief explanation of drawings]

Figure 1 shows (CaO _1-x PbO _x・6Fe ₂ O ₃ ) ₉₇ (La ₂ O ₃ ) ₃
A graph plotting the relationship between the composition and average magnetic properties when a magnet is fired at 1200°C for 30 minutes. Figure 2A is a magnetic hysteresis curve in the pressing direction of the magnet according to the present invention, and Figure 2B is its graph. This is a magnetic hysteresis curve in a direction perpendicular to the press pressing direction.

Claims (1)

[Claims] 1 (CaO _1-x PbO _x 6Fe ₂ O ₃ ) _100-y (La ₂ O ₃ ) _y , where x is 0.2 or more and less than 0.8,
Ca characterized by y being 2 or more and 5 or less
-Pb-La based oxide permanent magnet material.