JPS5877205A - Manufacture of oxide permanent magnet - Google Patents

Abstract

PURPOSE:To improve magnetic characteristics by a method wherein a kind or two kinds or more of insoluble or hard to dissolve boron compounds and bismuth oxide are added to water and are used as an additive. CONSTITUTION:BaO, SrO, PbO or a kind or two kinds or more of compounds becoming an oxide by heating and Fe2O3 or a compound becoming Fe2O3 by heating are weighed so that Fe2O3/MO=5-6 may be obtained in mol ratio. However, M is Ba, Sr, Pb. Next, a kind or two kinds or more of insoluble of hard to dissolve MB2O4 (M is Pb, Ba, Mn, Sr, Ca) and bismuth oxide Bi2O3 are added to water before a temporary burning process ro after the process. Magnetic characteristics, all of magnetic flux density, coercive force, and maximum energy product, can be improved by forming an oxide permanent magnet in this way.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing an oxide permanent magnet.

Ferrite magnets have low raw material and manufacturing costs, and their production volume is increasing rapidly, and their uses are becoming more diverse.There is also a demand for magnets with higher magnetic properties in terms of miniaturization and weight reduction.

Conventionally, bismuth oxide Bi2O, and borax Na2B, O have been used as additives to improve the magnetic properties of oxide permanent magnets.

It is known to use a mixture of two or more of boric acid 83BO8 or borax and silica.

Although these borides are very effective as additives, they are extremely easily soluble in water and cannot be used in manufacturing methods that involve dehydration during or before pressing oxide permanent magnets.
During the dehydration process during molding, most of the boride flows out along with water, resulting in an uneven amount of boride remaining in the molded product, which causes variations in magnetic properties.

Moreover, it is technically extremely difficult to accurately control the outflow of water-soluble boride and to maintain a constant amount of boride remaining in the molded article. For example, in wet pressing, where water is removed during pressing, this method is widely used because the magnetic field provides a good degree of particle orientation and produces oxide permanent magnets with good characteristics. The drawback is that relatively expensive boride is leaked out of the tank.

In view of the above, the present invention provides MB as an additive in the mixing step of the main raw materials before calcination or during wet pulverization after calcination.
204 (M is Ca, Sr, 13a.

Boron compounds represented by Pb, 'Mn) and bismuth oxide B
The main purpose is to propose this type of oxide permanent magnet with small variations in magnetic properties and high properties by adding i2O.

In the present invention, in the method for producing an oxide permanent magnet, one or more boron compounds MB204 (where M is Ca, Sr, Ba, Pb, Mn) that are insoluble or poorly soluble in water and bismuth oxide BI203 are used. is used as an additive. If the amount added is too small, the effect will not be fully exhibited, while if it is too large, it will act as an impurity, leading to a decrease in magnetic properties and being economically disadvantageous. Therefore, the total amount of the above-mentioned additives added is in the range of 0.01 to 7% by weight, preferably 0.05 to 4% by weight.

Further, as for the ratio of the boron compound to bismuth oxide, if the amount of bismuth oxide is too small, its effect will not be fully exhibited, and if it is too large, BHO will decrease, and the addition will be of no use. Therefore, when the amount of boron in the boron compound is 1, the amount of quantified bismuth is suitably from 0.1 to 40 times by weight, preferably from 0.5 to 20 times by weight.

In addition, the timing of addition of additives is determined based on the molar ratio of the main raw material Fe2
03 /MO”-5,0~6. (However, M = Ha
.

Sr, Pb), and MB204 (however,
One or more of M=Pb, Ba, Mn, Ca, 8r) and bismuth oxide Bi2O3 are added and mixed thoroughly, then calcined at 1000 to 1400°C, then wet pulverized and molded in a magnetic field. , is effective when firing at 1000 to 1400°C. In addition, the main raw material in mo/l/ratio 2
s 7M O= 5.0~6.0 (However, M=B
MB20. (
However, M=P b, B a, M n.

one or more of Ca, Sr) and bismuth oxide BI2
It can also be applied to cases where 03 is added, followed by wet pulverization, molding in a magnetic field, and firing at 1000 to 1400°C.

Each embodiment of the present invention will be described in detail below.

Example 1 Commercially available industrial nocurium carbonate BaCO with a purity of 97% or more
3 powder and commercially available industrial iron oxide Fe2O with a purity of 99% or higher
3 powder as the main raw material so that the molar ratio of 23/BaC0° is 5.6, and lead borate PbB20
4 and bismuth oxide former 203 in the amounts shown in Table 1 were thoroughly mixed in a Raikai Haya, and then fired at 1220° C. in a Matsufuru furnace. To 1 kg of the obtained barium ferrite was added 1.51 kg of water, and the mixture was pulverized for 34 hours using a ball mill to obtain particles with an average particle size of 1.0 μm.
Lium ferrite powder was obtained. This powder was wet-molded in a magnetic field to obtain a barium ferrite magnet. Table 1 shows a comparison of the magnetic properties when no additive was added and when bismuth oxide Bi2030.3 and 0.5% by weight were added alone.

In addition, when the residual amount of lead borate PbB204 in the manufactured magnet was measured by atomic absorption spectrometry, it was found that the amount of lead borate added was 98%.
．． It was confirmed that 5% by weight remained.

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Table 1 Bi2O30.3% by weight 4120 1560 3
．． 60B'203 0.5 weight section 4160 151
0 3.68 Example 2 Table 2 shows the magnetic properties obtained in the same manner as in Example 1 except that manganese borate MnB204 and bismuth oxide Bi2O were added as additives.

Table 2 Br Bf-10 (BH) Roasted [G] (Oe) (Mere) Not added
Canada 4050 1660 3.62Bi20
30.3% by weight 4120 1560 3.
60Hit030.5% by weight 4160 151
0 3゜68Mn82040.5% by weight 429
0 1590 3.89゛B1□03o, 6% by weight Example 3 Table 3 shows the magnetic properties when the same method as Example 1 was used except that barium borate BaB2O4 and bismuth oxide Hi203 were added as additives. show.

Table 3 [G] ', (Oe) [f'#()Oe) None
Addition 4050'1660 3.62
Bi20, 0.3% by weight 4'120 15'60
3.60 Example 4 Commercially available industrial strontium carbonate 5r with a purity of 97% or more
CO, powder, and commercially available industrial iron oxide F with a purity of 99% or higher
Fe2O3/5rCO5 using e2O8 powder as the main raw material
f) Weigh so that the molar ratio is 5.8, mix thoroughly in a Raikai machine, and then heat at 12.20°C using a Matsufuru furnace.
Calcined for an hour. Obtained strontium ferrite 1
1 kg of lead borate PbB204 and bismuth oxide Bi2O3 was added with 1°51 of water and milled in a ball mill for 40 kg.
Strontium 7 is finely ground for hours and has an average particle size of 1.0 μm.
Elite powder was obtained. This is then subjected to wet molding in a magnetic field.
The obtained sample was fired at 1200° C. for 2 hours to obtain a strontium ferrite magnet. Its magnetic properties are the fourth
Shown in the table.

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Table 4 Bi2030.3% by weight 3800 2580
3.051312o30.5wt% 3840
2520 3.12 Example 5 Table 5 shows the magnetic properties obtained in the same manner as in Example 4 except that manganese borate MnB204 and bismuth oxide Bi2O were added as additives.

Table 5 Not added 3680 2820
2.90Bi2030.3% by weight 3800 25
80 3.05Bi20s O, 5% by weight 38
40 2520 3.12 Example 6 Table 6 shows the magnetic properties obtained in the same manner as in Example 4 except that barium borate BaB2O and bismuth oxide Bi2'03 were added as additives.

Table 6 not added 3680. 2820
2.90B 12030.3% by weight 3800 2
580 3.05 Example T Commercially available industrial barium carbonate BaC0 with a purity of 97% or more,
Powder and commercially available industrial iron oxide Fe2O3 with a purity of over 99%
Table 7 shows the magnetic properties when the powder was weighed as the main raw material and the molar ratio of Fe2O3/BaCO3 was 5.7, and the same procedure as in Example 4 was followed. Additives are ■
Lead borate P, bB, 0. , ■Boric acid mangay Mn H
2O4, ■ Barium borate HaB204. Combinations of (1) strontium borate SrH,0, (2) calcium borate CaB2O, and bismuth oxide Bi,03 were tested.

Table 7 Not added 3810 2120
3.40Bi, 0.0.3% by weight 3930 1
900 3.38 As stated above, according to the present invention,
In the method for manufacturing a ferrite oxide permanent magnet, Mt320.
(However, M=Pb'.

Since one or more of Ba, Mn, Sr, Ca) and bismuth oxide are added before or after the calcination process, the magnetic flux density is lower than that of a permanent magnet without the above additives. Br, coercive force BHO and maximum energy product (B
H') max can be improved.

Additionally, the additive MB20. in the magnet produced according to the present invention.
(However, when the amount of M=Sr, Pb, Ba, Cb, Mn) was measured by atomic absorption spectrometry, it was found that 90% of the added amount
It was confirmed that heavy upwind remains. Therefore,
It can be seen that the residual effect is sufficiently exerted in the sintering process.

Agent solution=Shi Akiyama high

Claims (1)

[Claims] MO- obtained as a raw material of Bad, SrO, PbO or one or more compounds that become oxides of these by heating and l・'e203 or Fe2O from heating.
In the method for manufacturing an oxide permanent magnet having the basic formula 6Fe203 (M = Ba, S r, Pb ), M
B, 0. (However, M=l'b, Ba, Mn, S
1. A method for producing an oxide permanent magnet, which comprises adding one or more kinds of oxides (r, Ca) and bismuth oxide before or after the calcination step.