JPS58194304A - Oxide permanent magnet - Google Patents

Abstract

PURPOSE:To obtain a composite and integral oxide permanent magnet consisting of parts different in magnetic properties from each other, by specifying the sintering density difference between the sintered part of the magnet having a high coercive force and the sintered part thereof having a high residual magnetic flux density. CONSTITUTION:In a composite and integral sintered magnet including at least two kinds of parts different in magnetic properties from each other, the sintering density difference between the sintered part havig a high coercive force and the sintered part having a high residual magnetic flux density is selected to be not larger than 0.5g/cc. The selection of the sintering density difference to be not larger than 0.5g/cc, preferably about 0.3g/cc, makes it possible to obtain a balance of properties between the high-coercive force side and the high residual magnetic flux density side. On the other hand, a sintering density difference in excess of 0.5g/cc increases the divergence between the properties to lower the magnetic properties.

Description

[Detailed description of the invention] The present invention relates to a composite integral sintered magnet.

Conventionally, most sintered ferrite magnets have been made of a single component, in which the magnetic properties of each part of the sintered body are almost the same as a whole. As ferrite magnets are increasingly used in motors and other types of motors, and as the range of applications for ferrite magnets expands, ferrite magnets made of a single component... ! It has become essential to fully satisfy the required magnetic properties. Therefore, for starter motors etc.
A method has been adopted in which different types of single-component magnets are bonded together after sintering to create a composite. An example of this magnet is shown in FIG. In the figure, 1 is the adhesive surface, 2 is a high coercive force (high xH
o) [Yes, 5 is the high residual magnetic flux density (high Br) side. In particular, a high coercive force is required in order to increase the resistance to demagnetization of the magnet itself during use, that is, to improve the demagnetization resistance depending on the use of the one-rotation machine. For this reason, a composite magnet as shown in FIG. 1 is required. As shown in the figure, the high coercive force side 2 where demagnetization proof stress is required corresponds to about 50 to 50% of one arc segment-shaped sintered body, and the part corresponding to 5 in Fig. This is a part where high Br is desired in order to obtain output. However, in order to manufacture a composite magnet using the bonding method shown in FIG. 1, the bonding surfaces must be mirror-polished and zero-aligned.

Also, there are disadvantages in that it requires a large amount of man-hours and time such as adhesion.

Therefore, recently, a composite integrally sintered magnet as shown in FIG. 2 has been required. In the figure, 5 is the high coercive force side, 6 is the high residual magnetic flux density side, and 4 is the boundary. Methods for obtaining such a composite integral sintered magnet include (a) a method in which a partition is placed at the boundary, two different raw materials are injected into a mold, the partition is removed, the molding is performed, and firing is performed. Br can be achieved1
Part K to be made into high XHO after molding with different kinds of raw materials
There is a method of impregnating ions that inhibit sintering, such as Al'' and Or'+, and then sintering them. Both methods were invented by the present inventors and patent applications are pending. Even when manufacturing using this method, we conducted a study because it is necessary to achieve a high !Ho.In particular, the high x
The present invention was developed as a result of conducting nine various studies on composite integrally sintered magnets with Ho characteristics of ≧asoooe.

The present invention solves the above-mentioned problems and at the same time improves the magnet's high lH.
The purpose is to obtain a composite integrated oxide permanent magnet consisting of parts with different magnetic properties by specifying the difference in sintering density between the sintered part with a and the sintered part with a high 13r. be.

The oxide permanent magnet invented by Li is a composite integrated sintered magnet that includes at least two types of parts with different magnetic properties, and the sintered part has a high coercive force and a sintered part has a high residual magnetic flux density. It is characterized in that the difference is less than nsg/CC.

Note that the sintered density difference is set to be equal to or less than αSa/aO.

It is designed to balance the characteristics between the high Br side and the high IHo side, and preferably (15g7'Q O
Good condition. However, when αSg/'Q exceeds 0, the difference in each characteristic becomes large and the properties decrease by 2%.

The present invention will be explained below based on Examples.

Example 1 A calcined powder of 8rOβ·,O,=i2 to 58 (molar ratio) was used.

As a high Br1l additive, caco, (18~1.2w
t%, Sin.

15~(Add L6wt, average particle size α6~1.1μ
The additives on the blade height IHO side are aaoo, llLa~t6wt%, 810.
．． α4~1.0wt%, Al, 0.1. G4. Ov
t% was added thereto, and the mixture was ground to an average particle size of about a6 to t1 μm to obtain a ground powder. The amount of the above-mentioned additives to be added naturally varies depending on the pulverized particle size, desired range of magnetic properties, sintering temperature, etc. Therefore, the above range is only an example, and the amount added does not deviate from the scope of the present invention even if the amount added is outside the above range. The thus obtained pulverized powder was made into a slurry of magnetic powder 50 to 7 (containing 1 vt) containing pvm of 0 to lft-, and divided into a 7j100×50 mold with a partition of 1 inch thick in the center. and inject the material.

After removing the partition plate, wet molding was performed in a magnetic field of s, ooo to 1α000°. A 10×1G molded body was obtained. Then, sintering was carried out in the range of 1120 to 1200°C.

The oxide magnets obtained above were measured and typical measurement results are shown in Table 1.

Table 1 In the case of a Br ferrite magnet treated in the same manner, Table 4
Results showing similar trends to those in the table were obtained.

Example 2 After molding the slurry containing the high Br side pulverized powder shown in Example 1 in a magnetic field applied from a000 to HLOOOOe, Example 1
A single-component compact having the same dimensions as 9()-j[T
.

In 'C, after drying until the water content became 4 wt % or less, the molded body was immersed in a 20 to 25 wt 1 aqueous aluminum acetate solution at room temperature to a predetermined position, and the solution was impregnated into the molded body. Furthermore, applying or spraying an aqueous solution containing mulch''+ has the same effect as dipping.After drying, the obtained molded product is
Sintered within the range of 1100-1200°C.

The results shown in Table 2 were obtained.

Table 2 #! The high IHa portion in Table 2 is the portion impregnated with Mu 1s+. As is clear from Table 2, the impregnation method also showed the same tendency as the pressing method shown in Example 1, and
In order to achieve the Ho value, it was necessary to control the difference in sintering density between the high IHO side and the high Br side within a certain limit.

It can be said that the magnet obtained in this manner and having a partially high coercive force is extremely useful for various rotating machines that require a large demagnetization resistance.

In addition, in the above embodiment, a plate-shaped magnet is formed, and this is B.
This is to accurately measure r and tl (o and sintered density. Generally, composite magnets used in rotating machines are
A magnet with an arc segment type shape as shown in the figure was used, and the same results as with the above-mentioned plate magnet were obtained with this shape.

In addition to what has been explained above, the sintered magnet of the present invention in which the sintered density is adjusted has excellent effects in reducing size and weight, improving energy saving, etc., and has great industrial value.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing an example of a conventional composite magnet for motors.
FIG. 2 is a sectional view of a composite integrally sintered magnet showing one embodiment of the present invention. 4: Boundary part, 5: High coercive force side, 6: High residual magnetic flux density side Attorney lawyer Takashi Honma? No.

Claims (1)

[Claims] In a composite integrated sintered magnet that includes at least two types of parts with different magnetic properties, the difference in sintering density between the sintered part with a high coercive force and the sintered part with a high residual magnetic flux density is a
An oxide permanent magnet characterized in that the magnetism is O or less.