JPS60154504A - Oxide permanent magnet - Google Patents

Abstract

PURPOSE:To obtain the stabilized oxide permanent magnet having excellent magnetic characteristics by a method wherein the commonly known relation between the aditive SiO2 and CaO, including free metal oxide, is brought in the prescribed range, the established quantity of B2O3 is added, and the prescribed quantity of Al2O3 is also added as occasion demands. CONSTITUTION:When one or two kinds of Pb, Ba and Sr are used as metal M and an oxide permanent magnet having fundamental composition of Fe2O3MO of 5.3-6.0 in mol ratio is going to be formed, 0.1-1.0wt% of SiO2 and 0.1- 1.2wt% of CaO are used, 0.01-0.07% of B2O3 and 0-4% of Al2O3 are added thereon. At the same time, the range of mol ratio of CaO/SiO2 is set at 0.6-1.4, and the mol ratio of liberated MO and CaO (MO+CaO/SiO2) generated from the difference between the stoichiometric mol ratio and the actual value is selected in the range of 1-1.8. When an improvement is made on the conventional method in which attention is paid only on the quantity of additive as above-mentioned, the manufacture of the title magnet is stabilized, and the oxide permanent magnet having high coersive force and high residual magnetic flux density can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to MO-n Fe 203 (M is Pb, B
It relates to an oxide permanent magnet having a basic composition of "one or two of the following, n = 5.3 to 6.0), particularly containing Si02, CaO, A11203 (optional components) and B2O3 as additives. This relates to 11 permanent oxides containing .

In oxide permanent magnets such as barium ferrite magnets and strontium ferrite magnets, in order to obtain high magnetic properties, composite addition of Si02, CaO, and AQ203 (including 0) has traditionally been carried out (for example, as described in the U.S. patent Specification No. 2,980,617, Special Publication No. 49-4
(See Japanese Patent Publication No. 716 and Japanese Patent Publication No. 1575/1983). In that case, for Fe to obtain a high coercive force, 1200
It is necessary to perform sintering at a low temperature of 0.degree. C. or lower, and to pulverize the material after calcination so that the particle size is less than the single magnetic domain critical particle size. However, lowering the sintering temperature lowers the density of the sintered body, resulting in a problem in that the residual magnetic flux density, which has a close relationship with the density of the sintered body, decreases. Further, reducing the finely pulverized particle size increases the time required for finely pulverizing and causes deterioration in moldability. Furthermore, Si02 and CaO
In the case of composite addition of 100% or more, the coercive force changes significantly due to a slight change in the blended molar ratio, so there is a problem in that strict manufacturing control is required.

An object of the present invention is to solve the problems of the prior art described above and to provide an oxide permanent magnet having high coercive force and high residual magnetic flux density that can be manufactured stably.

The oxide permanent magnet of the present invention has a molar ratio of Fe2O3/M
O (M is one or two of Pb, Ba, Sr), -5
, 3 to 6.0, silicon oxide Si 02 is contained in a weight ratio of 0.1 to 1.
0%, calcium oxide CaO 0.1-1.2%, aluminum oxide A (1203 4% or less (including 0%)) and boron oxide B2O3 0.01-0.07%, and the molar The ratio of CaO/Si02 is 0.5 to 0
．． 4, and free MO and Ca resulting from the difference between the stoichiometric molar ratio and the molar ratio in actual production.
The ratio of the number of moles of O to the number of moles of 3i02 (MO+Ca O/
Si 02 ) is in the range C of 1 to 1.8. .

In oxide permanent magnets, CaO, Si02, A(LO3, B2
Combined addition of O3 etc. (CaO-8i02, Ca0-
As mentioned above, A(L 203 , B203-8i 02 ) has been conventionally performed. However, in the past, attention was focused solely on the amount of each additive added, and the reality was that high magnetic properties could not be stably obtained.

As a result of various studies conducted by the present inventors, we found that even when using the known additives Si02 and CaO, in addition to keeping the amount of these additives within a predetermined range, free M
High magnetic properties can be stably obtained by keeping the relationship between the amounts of 3i02 and CaO added, including O, within a predetermined range, and by adding a predetermined amount of B2O3 and, if necessary, a predetermined amount of Al2O3. I found out.

To explain in detail, in ferrite magnet -C, the molar ratio of Fe2O3 and MO is stoichiometrically 6.0, but in actual production, MO is slightly larger than this stoichiometric composition (usually The raw materials are blended such that the molar ratio is 5.3 or more and less than 6.0. In this way, stoichiometric Fe2O3
Since there is a difference between the molar ratio of MO and MO, free MO is generated during the actual manufacturing process. Therefore, the present inventors focused on this free MO and found that Si
Control the molar ratio of the sum of free liIl1MO and CaO (S ``0-1-CaO/Si 02 ) with respect to 02M+-
High coercive force (It-1G≧3000006
) I found that it is possible to get a Tekiru. In addition, by including B2O3 as an additive, the range of molar ratio (SrO + Ca O / Si 02 ) at which high coercivity can be obtained is expanded, stable production is possible, and the density of the sintered body is improved, thereby increasing the residual magnetic flux density. It is also reported that the results are improved.

The present invention will be specifically explained below using comparative examples and examples.

Comparative Example Carbonate carbonate SrCO3 and iron oxide Fe2O3 were mixed so that the molar ratio of S10 and Fe2O3 was 1:5.7, and 0.3 of silicon oxide 3i02 was added to this mixture.
After adding % by weight, it was calcined at 1270°C for 1 hour, and during pulverization, the total amount of silicon oxide Si02 was added, and then 0.8% of aluminum oxide Al2O3 was added to this, and the mixture was processed into a wet pulverizer. Finely pulverized to an average particle size of 0.8μ,
．． A Sr ferrite magnet was manufactured by applying a pressure of 4t 7cm2 in a magnetic field of about 8KO (+) and sintering it at 1200°C for 1 hour.At this time, the molar ratio of CaO and Si02, the residual magnetic flux density 3r, and the ) The relationship between J-works and HC is shown in Figure 1. As is clear from FIG. 1, in the case of composite addition of Si02 and CaO, the change in coercive force is extremely large compared to the change in residual magnetic flux density, and the coercive force shows the maximum value when the mixing ratio is 1. It can be seen that it is close to 0. Furthermore, this is S
This shows that the blending ratio must be within a certain range regardless of the amounts of i02 and Ca0g1A added.

Example 1 Sr CO:3 and Fe2O3 in molar ratio Fe2O3/
Two types of raw material mixtures were prepared by mixing so that Sl'O was 5.5 and 5.7. This was calcined for 1 hour at 1250°C for each mixture, and then 5iC
1+ and the free sro caused by the difference in the stoichiometric composition ratio of CaO and Fe 20373r o=6.
When expressed as rO+CaO/Si02''C, the molar ratio is 0.8 to 2.0, and further A<L20
3 was added in an amount of 0.8% by weight. In addition, Fe2O3 is formed in the sintering process to form 0.03% by weight of B2O3.
Hou 1H3803 was added and 838
Four types of samples were prepared, each having two types of needles (b) without the addition of 03, and were pulverized, formed in a magnetic field, and sintered under the same conditions as in the comparative example to obtain Sr ferrite magnets. Table 1 shows the relationship between each sample, the added magnetic flux density, and the coercive force in Fig. 2. 2nd e 2
03/St' O is 5.5 and 5.7, respectively, curves C and d are obtained by adding H3, B O3, F, e203
are 5.5 and 5.7, respectively. From curves a and b in Figure 2, it is clear that in the case of composite addition of 5102 and CaO, the -C coercive force changes greatly depending on the blending ratio; It can be seen that it is important to manage the overall blending ratio, including the

However, as shown in curves C and d in Figure 2, 82
When 03 is added, 3r is added to some extent.

Although it is recognized that the coercive force tends to fluctuate depending on the value of +CaO/Si02, the coercive force improves over a wide range of -C, and the combined addition of B2O3 stabilizes oxide permanent magnets with high coercive force. I understand that the manufacturing process is difficult.

Example 2 3r CO3 and Fe2O3 in a molar ratio of Fe2O3/
Mix 2 so that SrO is 5.65 and 5.75.
Various raw material mixtures were prepared. 0.3% by weight of 5102 as an additive was added to each mixture at 1250°C.
Calcined for 1 hour, then finely pulverized to remove the total Si
The molar ratio of 02 to CaO and free SrO is 3r o+
ca O/Si 02 = 1.4 How Si
02 and CaO were added to this, and 8203 and 0(
(no additives), 0. o2.0.04.0.06.0.08% by weight of boron oxide was added and pulverized to an average particle size of 0.9μ using a wet pulverizer, and 0.4t
After applying a pressure of /cm2 and molding in a magnetic field of approximately 8KOe,
A ferrite magnet was obtained by sintering at 20° C. for 1 hour. Table 2 shows the relationship between the amount of B2O3 added to these ferrite magnets, residual magnetic flux density, coercive force, and sintered body density. FIG. 3 is a graphical representation of Table 2, which shows the magnetic properties and density of the sintered body.

From Table 2 and Figure 3, with the addition of 8203, a significant improvement in coercive force can be seen, but at the same time, the density of the sintered body also increases, which leads to an increase in the residual magnetic flux density, which has a close relationship with the density of the sintered body. It can be seen that an improvement can be obtained. However, if 8203 is o, og mass% or more, the amount of B2O3 added is A range of 0.01 to 0.01% by weight, preferably 0.01 to 0.05% by weight is suitable.

In addition, when considering the combined effect of additives, -(, A
A combined effect due to Q, 203 is also considered, but A<L20
3 is Aα, which is an ion equivalent to FC3+, which comes from Fe2O3, which is the main component in oxide permanent magnets.
This is a coercive force change due to a change in lattice constant caused by a substitution solid solution reaction with S3+, which forms grain boundary compounds.
The effect of i 02, Ca 2 O, and B 2 O 3 differs in wood quality. Figure 4 shows the J Hanoru 8203 in this example.
．． A (1203
J0 No. 4 shows the relationship between the addition amount, residual magnetic flux density, and coercive force.
As shown in the figure, the relationship between the amount of AQpOs added, residual magnetic flux density, and coercive force changes almost linearly, but AQ, 203
Increasing the amount of addition improves the coercive horn, but on the other hand, the residual magnetic flux density 1
In order to reduce the effects, the amount added should preferably be 4% by weight or less (including 0%).

As described above, according to the present invention, the blending ratio of 3i 02 and CaO is changed to the molar ratio including free NIMO (81.O+CaO
/Si 02 > and add 8203 to this
By adding 0.01 to 0.07% by weight of oxide permanent magnets with higher coercive force than conventional ones,
It is possible to obtain a sintered body with a density approximately 0.4 to 1% higher than that without the addition of 203. Furthermore, as the density of the sintered body improves, the residual magnetic flux density, which has a close relationship with it, can also be improved, and as a result, both the residual magnetic flux density and coercivity can be higher than before, resulting in high magnetic properties. It is possible to shorten the time required for fine grinding to obtain . In other words, one method of achieving high magnetic properties has conventionally been to reduce the particle size of the finely pulverized powder, but the present invention allows the above-mentioned method to be achieved even if the particle size of the finely pulverized powder is kept at the same level as before. High magnetic properties can be easily obtained through the use of additives, and in many applications of oxide permanent magnets, when supplying magnets with magnetic properties comparable to conventional ones, the required pulverization time is reduced. greatly shortened C
It is possible.

Incidentally, the method for manufacturing an oxide permanent magnet according to the present invention is 5102
and CaO are mixed according to the molar ratio including free MO, and the amount of each additive added is (MO+CaO)/S
It is sufficient if i02 is set within the range of 1 to 1.8.

However, if too large a quantity of additives is added, the proportion of grain boundary components of the additives that fall into the oxide permanent magnet will increase, which will actually lower the density of the sintered body and cause a decrease in the residual magnetic flux density. -I invite F. Therefore, the addition of USi 02 and CaO is 0.1 to 1.0% by weight of 3i 02 and 0.1 to 1.2% by weight of CaO (or a Can! compound that becomes equivalent in the sintering process). ), and when the blending ratio is expressed as a molar ratio within this range, C
aO/SiO2 becomes 0.6 to 1.4 and further MO+Ca
It is best to keep the O/Si02 value between 1 and 1.8.

As described above, the present invention provides an oxide permanent magnet that has higher coercive force and higher sintered body density than conventional ones, and also has improved residual magnetic flux density, which has a close relationship with sintered body density. It can be manufactured stably.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between CaO/Si02 blend molar ratio and magnetic properties, Figure 2 is (Srf)+Ca0)/SiO
A diagram showing the relationship between the molar ratio of 2 and magnetic properties, Figure 3 is B2
Figure 4 shows the relationship between the O3 addition pot, magnetic properties and sintered body density, and Figure 4 shows the relationship between the amount of Al2O3 added and the magnetic properties. / Figure CaO15i0z molar ratio Figure 2 (,5rO+Ca0)15i0z molar ratio #, 3 Figure 4 AlzOa is also in the foreground (wt%) zu31+11. (7) Name (indication) Oxide permanent magnet sleeve 11
Substitution of the person who will do the work 8 Norio Kono Deputy representative person - 5a Akira (1) Name Acid, material permanent magnet sleeve 11: Name of the person who will do the work +sog+ l-l, i7 Metal Co., Ltd. representative #
Norio Mutsukono - Date of amendment order April 24, 1980 (shipment date) Target of amendment

Claims (1)

[Claims] 1. In an oxide permanent magnet having a basic composition with a molar ratio of 'CFe203/MO (M is Pb, one or both of 3a and 3r)' = 5.3 to 6.0.゛C, weight ratio of 0.1 to 1.0% of quartz oxide Si02, 0.1 to 1.2% of calcium oxide CaO, 4% or less of aluminum oxide A<L 203 (including 0%) ) and boron oxide B2O3 in an amount of 0.01 to 0.07%, the molar ratio of CaO/Si02 is in the range of 0.6 to 1.4, and the stoichiometric molar ratio and actual An oxide permanent magnet characterized in that the ratio of the number of moles of free MO and CaO resulting from the difference in the molar ratio in the production of the oxide (MO+CaO/5i02) is in the range of 1 to 1.8.