JPS589303A - Manufacture of oxide permanent magnet with high insulation resistance - Google Patents

Abstract

PURPOSE:To make it possible to obtain excellent magnetism and high insulation resistance, by after mixing, sintering provisionally and crushing a mixture of BaO or SrO and Fe2O3 materials and adding to the mixture a Ba or Sr compound and then forming and sintering them. CONSTITUTION:In manufacturing oxide permanent magnets of magnetoplumbite type with a chemical formula: MO.Fe2O3 (M is Ba or Sr, and n is mol ratio by 5-6) their main ingredients and auxiliary ingredient added as needed are weighted, mixed, sintered provisionally and crushed. Then, after a Ba or Sr compound is added to the mixture, it is formed and sintered. Between Fe2O3 or Fe<2+> that is thereby left and a newly added compound of Ba or Sr solid phase reaction is developed to obtain a magnetoplumbite phase, in which the Fe2O3 ingredient is made as little as possible for much improving the insulation resistance of the sintered mixture. It is preferable to add the Ba or Sr compount in the amount of 0.05-3.0wt% of the ferrite.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has the chemical formula MO@n Fe 103 (where n is 5.0 to 6.0 in molar ratio. M is a metal element and Ba
Alternatively, it represents Sr. ) The present invention relates to a hexagonal oxide permanent magnet exhibiting a magnet branbite crystal structure, and particularly relates to providing a permanent magnet with high insulation properties without impairing magnetic properties.

Recent electronic component elements or circuit devices are required to be miniaturized and to save energy and resources. As one means for achieving this purpose, it has been proposed to incorporate small permanent magnets with high insulation properties. for example,
The permanent magnets used in polarized relays need to be high-performance, inexpensive, and have extremely high insulation properties.

If the insulation of the permanent magnet material used is low, a high voltage will be applied to the drive coil, which may cause a layer short and cause the relay to malfunction.

Permanent magnet materials include alnico and ferrite.

Rare earth and other magnets are commercially available, but the magnetic characteristics,
From the standpoint of insulation and price, ferrite magnets with a magnetobrambite structure are considered to be the most effective.

Conilite magnets are generally calcined to produce BaO or S.
It is obtained by mixing the raw material for rO and iron oxide at a predetermined molar ratio, calcining it, then coarsely or finely pulverizing it, and going through a process of press molding or molding and firing in a magnetic field. Cab, Sin, A during mixing or grinding to improve magnetic properties
403, Bi20B, 8203.

Additives such as pbo are usually added in trace amounts.

Ferrite magnets are BaO・6Fe20B or SrO・
It is a magnetobrambite-type hexagonal oxide with the chemical formula of 6Fe203, but in general mass production, Fe
It is said that a small amount of 2O and divalent iron oxides are present in the magnet. This is due to unreacted Fe and O even after calcination.
That s remains.

BaBaO-6Fe2 is produced by over-pulverization during the wet pulverization process.
F generated by dissociation of 0+ BaO+6Fe201
e z OB remains, and during the coarse pulverization and wet pulverization processes, iron generated from the inner wall of the pulverizer used and the pulverizing media is oxidized during firing, resulting in divalent iron oxides, or Fe2O3. It is thought that this is due to the existence of

Fe2O3 and divalent iron oxides mixed in this way affect the magnetic properties.

Significantly deteriorates the insulation resistance of the magnet. However+
Since the presence of Fe2O2 and divalent iron oxides has been considered only from the viewpoint of magnetic properties, their presence to some extent has been allowed in manufacturing. However, regarding insulation resistance, Fe10
The presence of B or divalent iron oxides has a very negative effect.

In addition, in the case of general manufacturing, B is calcined with Fe103.
The raw material containing Ba and Sr compounds, which become aO or SrO, has a stoichiometric composition of about 5.3 in terms of molar ratio in the case of isotropic and about 5.8 in the case of anisotropic.l) Bad.

Calcination occurs because SrO is weighed and mixed in excess.

It was thought that Fe10B remaining after pulverization would react again during firing. However, Bad, which was decomposed and generated during calcination! Or SrO has a very low reactivity,
It becomes difficult to react with Fe2O3 during firing. Moreover,
Most of the excess Bad and SrO is eluted into water during wet grinding and flows out.

It has become clear that this significantly deteriorates the insulation resistance value of ferrite magnets.

The object of the present invention is to solve these problems, improve the magnetic properties, and significantly improve the specific resistance of the magnet.

The gist of the present invention is MO*nFe2O3 (n=5-6
In the production of magnetobrambite-type oxide permanent magnets with the chemical formula (M is Ba or Sr), after weighing and blending the main component and optionally additional subcomponents, calcining, coarsely pulverizing and finely pulverizing, Ba or Sr is used. After adding and mixing the compound, the remaining Fe2O3 or Fe
and the newly added Ba or Sr compound to cause a solid phase reaction.

The sintered body is characterized by having a magnetobrambite phase and a very small amount of Fe20B, thereby greatly improving the insulation resistance of the sintered body.

Furthermore, in the present invention, it is preferable that the amount of Ba or Sr compound added after pulverization is 0.05 to 5. Ovt% is good. The types of additives are BaCO3 in Ba ferrite, Sr
In the case of 7-elite, it is more preferable to use 8rCO3 in order to improve the insulation resistance.

As a target characteristic of the permanent magnet material according to the present invention.

Insulation resistance is 100 or more when DC is applied at 1,000 V.

Also, for practicality when used as a polarized relay, AC 3.0
When 00V is applied, it is 300Ω or more, and the magnetic properties are as follows: residual magnetic flux density Br is 3800 (Gauss) or more, and coercive force is 111 (C is 1900 (Oersted)).

Maximum energy product (BH) m1LX is 3.6X10
(Gauss Ørsted) It combines the above.

Nine embodiments of the present invention will be described below.

Example-1) Raw materials were weighed and mixed so that the molar ratio of BaC03 and Fe,03 was 5.4 and 5.6, calcined at 1200°C for about 2 hours, and further reduced to an average particle size using a dry vibrating rod mill. is 4
After coarsely pulverizing the particles to a particle diameter of about 1 μm, the particles are finely pulverized using a wet pulverizer until the average particle size is 1 μm.

0.0.5% by weight of BaCO3 at the end of the grinding.

They were added and mixed to give a sample of 1.0% and 2.0%.

A slurry of the sample was wet-molded in a magnetic field at a pressure of about 0.57 ON/2, and sintered at a temperature of 1220°C.

The sintered surface was polished and the insulation resistance and magnetic properties were measured.

The results are shown in Table-1.

As a result, when BaCO3 is not added (0%), the insulation resistance value is lower than C, 1000 V 't' IMΩ, and at AC 3000 V or higher, it is 0. It has a much smaller value than OIMG. On the other hand, the one with 0.5% BaCO3 added has a DCLoooV of 10MΩ.
More than that.

It showed 0.2MΩ or more at AC3000V. Furthermore, 1% or more of added Mono I/i, 10 or more in 1ooov,
3000V 20MΩ, compatible with AC3000V
(Also shows an insulation resistance value of 0.2MQ or more.

Furthermore, by adding BaCO3, although aI(c) of the magnetic properties decreased slightly, the sintered density increased and the residual magnetic flux density Br significantly improved.

This shows that the addition of BaCO3 causes a reaction with Fe203 during sintering and promotes the sintering reaction, and BH
(max) was improved.

As mentioned above, it is clear that by adding BaCO3 after pulverization, the insulation properties are significantly improved without impairing the magnetic properties.

Example 2) BaCO3 and Fe203 were weighed and mixed so that the molar ratio was 5.40, and then calcined in the same manner as in Example 1).

Shattered. At the end of the grinding, the powder was divided into two parts and 0 to 3 of each of BaCO3, BaSO4, etc. was added as additives.
．． After adding and mixing at 0% by weight, this slurry was molded, sintered, and polished in the same manner as in Example 1), and the insulation resistance value and magnetic properties were measured.

Figure 1 shows the insulation resistance value and magnetic property value at DCLoooV as a result of this. Those with insulation resistance of IOMΩ or more at DCLoooV are 0.1M even at AC5000V.
It was confirmed that the insulation resistance was Ω or more.

BaCO3 and Ba5O each have significantly improved insulation resistance values. In particular, it can be seen that the addition of KBaCOs significantly improves the insulation resistance even with a small addition amount.

Although there are differences in the magnetic properties between the two Ba compounds, the density and Br are improved, and the BH (ma
x).

Example 3) After weighing and mixing SrCO and Fe2O3 at a molar ratio of 5.50, they were calcined at 1220°C, dry-pulverized with a vibrating rot mill to have an average particle size of 3 to 4μ, and further It was wet-pulverized so that the average particle size was 1 μm. At the end of the grinding, the powder was divided into 3 parts and BaCO3, SrCO3, S
0 to 3% by weight of rSO4 was added to each and mixed. This slurry was molded, sintered, and polished in the same manner as in Example 1), and the insulation resistance value and magnetic property value were measured.

The results are shown in FIG. If the insulation resistance value is IOMΩ or more at 1000V DC, the resistance will be 0.1 at 5000V AC.
It was confirmed that the insulation resistance was greater than MΩ.

For those without additives (0chi), the insulation resistance value is DCIDOO
V [2 or less, at most 4 to 10 at DC250V
It was MΩ. On the other hand, BaCO3, SrCO3
.

SrSO4 significantly improves the insulation resistance value and also.

The density and Br of the sintered body are also improved.

Compared to 5rSO, BaCO3 and 5rCOs show a more excellent effect.

The present invention has been explained above using examples.

By adding and mixing Ba and Sr compounds at the end of grinding, it is possible to significantly improve the insulation resistance, increase the density of the sintered body, increase Br, and significantly improve the +BH (ma).

In addition, BaCO3 and SrCO3 are other Ba compounds, Sr
It was found that the effect was greater than that of other compounds.

In addition, in the above example, only the method using wet magnetic field molding was explained, but the effect can also be confirmed by dry magnetic field molding method and dry molding method, and it is natural to add additives to improve magnetic properties. 9, and does not limit the scope of the present invention.

Also, if you require the same BHp as without additives.

It has been confirmed that by lowering the sintering temperature and slightly lowering the density of the sintered body to the same degree as without additives, it can have magnetic properties equivalent to those without additives without deteriorating insulation resistance.

The nine present inventions have been described above, but after pulverization as in the present invention, 0.05 to 3.0 w of Ba or Sr compound is added.
By adding t%, it was possible to obtain a hexagonal oxide permanent magnet having a magnetoblanbite structure with high insulation properties and good magnetic properties.

The permanent magnet according to the present invention is extremely effective not only as a magnet for polarized relays as described above, but also as a permanent magnet used in temperature-sensitive reed switches and the like.

[Brief explanation of the drawing]

FIG. 1 shows characteristic curves showing (a) insulation resistance and (b) magnet characteristics of the permanent magnet of Example-2 according to the present invention, and FIG. 2 also shows (a) insulation resistance of the permanent magnet of Example-3 according to the present invention. resistance,
(b) Shows characteristic curves showing the magnet characteristics. Figure 2 (α) Addition amount (We%) (b) (wt%)

Claims (1)

[Claims] 1. Mo*nFe2O3 (where M is Ba or Sr,
In the production of oxide permanent magnets with a magnetobrambite crystal structure having a chemical formula in which n is a molar ratio of 5.0 to 6.0, raw materials for BaO or SrO and Fe2O3 are mixed, pre-calcined, and then pulverized. A method for producing an oxide permanent magnet with high insulation resistance, which comprises adding and mixing a 9M compound and then post-forming and firing. 2. 0.05 to 0.05% by weight of Ba compound and Sr compound
3.0%. A method for producing an oxide permanent magnet having high insulation resistance as claimed in claim 1, wherein the oxide permanent magnets are added and mixed at the end of pulverization. 5. Among Ba compounds and Sr compounds, especially BaC0,
. A method for producing an oxide permanent magnet with high insulation resistance according to claim 1, wherein 0.05 to 3.0% of SrCO3 is added and mixed at the end of pulverization.