JPS63204602A - Oxide permanent magnet and its coating method - Google Patents

Abstract

PURPOSE:To make it possible to uniformly form a thin film on the surface of a magnet body using an electrodeposition coating material, by a method wherein a film of the electrodeposition coating material is formed on the surface of the magnet body having the fundamental composition in which Fe2O2/MO is specified by mol ratio, and specific volume resistivity and the density of sintered body. CONSTITUTION:A film of electrodeposition coating material is formed on the surface of a magnet body having the fundamental composition of Fe2O3/M0 (M indicates one or two kinds of Sr, Ba and Pb) of 5.3-6.2 in mol ratio, the volume resistivity of 10<7>OMEGA.cm or less and the sintered body density of 4.80g/cm<3> or more. Pertaining to the method of coating, said magnet body is dipped into the solution in which a cation type electrodeposition coating material is mixed, D/C current is applied between said magnet body and the opposing electrode, and the film of cation type electrodeposition coating material is formed on the surface of the magnet body. Consequently, the electrodeposition coating operation can be performed on the oxide permanent magnet as an insulative body, and a thin and uniform surface film can be obtained irrespective of the intricateness of its shape.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to rigid disk drives or floppy disk drives, which are one of the peripheral devices of electronic computers.
For oxide permanent magnets used in magnetic head positioning devices used in drives, etc., oxides with a thin, uniform coating film formed by electrodeposition on the surface to prevent magnetic particles remaining attached during polishing from scattering. This invention relates to permanent magnets and their coating methods.

[Conventional technology]

In a magnetic head positioning device for a magnetic disk drive, a voice coil motor is used as one of the driving sources for moving the magnetic head between tracks required for writing and reading.

The motion of the coil is linear (for example,
No. 4241 and No. 58-35030) and one with rotating motion (see, for example, Japanese Patent Application Laid-open No. 55-88559 and Japanese Patent Publication No. 58-31662), but in either case, the magnetic field formed by a yoke and a permanent magnet is A coil is placed in the air gap, and when a current is passed through the coil, the coil moves based on Fleming's left-hand rule.

For example, ferrite magnets are used as permanent magnets incorporated in such voice coil type motors. However, since magnetic fine particles remain on the surface of a ferrite magnet after grinding, if it is directly incorporated into the magnetic circuit, the magnetic fine particles will scatter and interfere with magnetic recording. For this reason, ferrite magnets used for the above purposes are generally coated on the surface before being incorporated into a magnetic circuit.

[Failure to solve the problem]

Conventionally, methods for coating ferrite magnets include spraying paint onto the magnet surface or immersing the magnet in a paint bath. However, spraying or dipping methods tend to cause uneven thickness in the paint film, such as sagging or sagging, and if the magnet has a complicated shape, there may be parts that are not painted, or narrow gaps may be blocked by the paint. There was a problem that it would get lost.

Electrodeposition coating is also known as another coating method. Among these electrodeposition coatings, cationic electrodeposition coating can form a highly efficient and uniform coating film, so for example, Patent No. 1) 864
As disclosed in No. 36 and Japanese Unexamined Patent Publication No. 58-25497, it is widely used for painting automobile bodies and their accessory parts.

However, in cationic electrodeposition coating, the object to be coated is immersed in a water-soluble paint, and the object to be coated is used as the cathode (-), and the metal tank (or an electrode plate separately installed in the tank) is used as the anode (+). , by passing a direct current between the two electrodes, the fine particles of paint are attracted to the surface of the object to be coated using electric force, forming a film. It was not applied to oxide permanent magnets, which were classified as electrically insulating materials.

Therefore, an object of the present invention is to provide an oxide permanent magnet having a thin and uniform electrodeposition coating on its surface.

Another object of the present invention is to provide a method capable of forming a thin and uniform electrodeposition coating on the surface of an oxide permanent magnet.

[Means for solving problems]

The oxide permanent magnet of the present invention has a molar ratio of Fe, 03/M
O (M is one or two of Sr+Ba and Pb) =
It has a basic composition of 5.3 to 6.2 and a volume resistivity of 1.
less than 0.07Ω・c and a sintered body density of 4.80 g
/crd or more, a film of electrodeposition paint is formed on the surface of the magnet body.

In addition, the coating method for the oxide permanent magnet of the present invention uses a molar ratio of FezO5/MO (M is one of Sr, Ba, and Pb).
species or two species) = 5.3 to 6.2,
A magnet body having a volume resistivity of less than 107 Ω·cm and a sintered body density of 4.80 g/ant or more is immersed in a solution in which cationic electrodeposition paint is dispersed, and this magnet body and a counter electrode are connected to each other. This is characterized in that a DC voltage is applied during this period to form a film of cationic electrodeposition paint on the surface of the magnet body.

Oxide permanent magnets generally have a molar ratio of FezO3/M
O (M is one or two of Sr, Ba, Pb) ~
It has a basic composition expressed by 5.3 to 6.2. However, from the viewpoint of magnetic properties, strontium ferrite magnets containing SrO and Fe2O as main components are often used. Taking this strontium ferrite magnet as an example, in order to improve its magnetic properties, S is added as an additive.
It has been conventional practice to add ing and CaO in combination. Additionally, 8203 is also added in order to further improve the magnetic properties and stabilize them. In order to further improve the coercive force (+1Ic), A
I! t's or CrzOz may also be added. It is known that these additives form a glassy grain boundary layer called a liquid phase.

As a result of various studies, the present inventors have discovered that additives (especially Cab) that form glassy grain boundary layers in liquid phase sintering of ferrite magnets as described above can further increase the electrical resistance of ferrite magnets and We found out what makes painting difficult. Furthermore, it was revealed that this additive is related to the amount of pores remaining during the sintering process, that is, the density of the sintered body.

It has been found that in order to form a film on the surface of a ferrite magnet by electrodeposition, it is necessary to make the magnet have a volume resistivity of 10 7 Ω·cm without grooves. It has also been found that when the sintered body density of the magnet is set to 4.8 g/cra or more, the number of pores in the magnet is reduced, and thus the volume resistivity can be lowered without deteriorating the magnetic properties.

It has been found that, in order to keep the volume resistivity and sintered body density of one stone within the above ranges, for example, the type and amount of additives can be determined as follows.

First, BzOi, SiO□, and CaO are added in combination, and if necessary, if A 12 z(h or Crz(h) is added, the amount of each additive (hereinafter, % refers to weight %). ) can be done as follows.

The magnetic properties vary greatly depending on the amount of 5to2 and CaO added, but B2O3 has the effect of reducing the amount of change and bringing about stabilization and improvement. However, B2O3 is 0
．． If it is less than 0.01%, there is no effect, and if it is more than 0.01% or i%, sintering progresses too much from a low temperature, which tends to cause abnormal growth of crystals and lowers +Hc, so 0.01% to 0.1%.
%.

SiO□ suppresses crystal growth, so if it is less than 0.1%, it is ineffective, and if it is more than 1.0%, a large amount of CaO as a sintering accelerator must be added, and the grain boundary components are 0.1 because it increases and reduces the magnetic properties.
-1.0% (preferably 0.2-0.8%). C
If aO is less than 0.1%, it has no effect, and if it is more than 1 or 2%, the resistance becomes high (and electrodeposition coating becomes difficult, so 0.1
~1.2%. Furthermore, if too large amounts of ^β203 and Cr20z are added, the density of the sintered body will be low, making electrodeposition coating difficult, so the amounts are set at 1.5% or less and 2% or less, respectively.

In addition, when trying to obtain even higher magnetic properties, Fe
The molar ratio of 2O and MO should be in the range of 5.6 to 6,0, and the content of CaO and Sing should be in the following range. That is, if CaO is less than 0.5%, the sintered density will be low and the magnetic properties will be deteriorated, whereas if CaO is 1 or 2%,
Since the resistance becomes too high when the amount exceeds 0.5%, the amount of CaO added is set in the range of 0.5 to 1.2%. SiO□ is 0.3
If it is less than 0.0%, the effect of suppressing crystallization will not be sufficient.
If it is more than 7%, a large amount of CaO must be added, resulting in a decrease in magnetic properties.

The amount added is in the range of 0.3 to 0.7%.

With such a composition, high magnetic properties such as Hc≧40000e can be obtained with a Br hole of 4000G, for example. Further, in the above composition, A 1203 or Crt
By adding an appropriate amount of Ch, a high Hc material can be obtained, while by reducing the amount of ^1203 or Cr or 02 added, a high Br material can be obtained. Therefore, CaO and Si
Various additives other than 0 g may be added as appropriate depending on the required magnetic properties so that the resistance is less than 10 7 Ω·(minimum).

Furthermore, even if the S additives and the amount added are the same, the magnetic properties vary depending on other factors such as the grinding conditions. That is, the additive conditions of the present invention should be considered as an example since they can be adjusted considerably by changing the manufacturing conditions.

Next, the resistance of ferrite magnets shows significant changes depending on additive conditions and sintering atmosphere conditions. For example, when the amount of additives as sintering aids is small, the resistivity of ferrite magnets is 10
'3~105Ω・cm, but calcium oxide (Ca
When a large amount of compounds containing divalent alkali ions such as b) are present at the grain boundaries, the resistivity increases to 10 7 to 10'Ω·0 m or more.

Therefore, when using silicon oxide (Sing) and calcium oxide (Cab) as additives, CaO is
The aO/SiO□wt% composition makes the groove 1 wt%, and the wt% of SiO2 is 0.1-1.0% and CaO is 0.1-1.
By setting it to 2%, the resistivity can be made less than 10 7 Ω·4. The reasons for limiting the amounts of SiO□ and CaO added are as follows.

SiO□ suppresses crystal growth, so if it is less than 0.1%, it is ineffective, and if it is more than 1.0%, a large amount of CaO as a sintering accelerator must be added, and the grain boundary components are 0.1 because it increases and reduces the magnetic properties.
-1.0% (preferably 0.2-0.8%). C
If aO is less than 0.1%, it will have no effect, and if it is more than 1.2%, the resistance will be high and electrodeposition coating will be difficult, so 0.1
~1.2%.

In addition, sintering of oxide permanent magnets is usually carried out in the atmosphere using an electric furnace or a gas furnace, but the oxygen concentration at the highest temperature in these furnaces is approximately 13 to 18% in the electric furnace.
, it is about 5 to 10% in gas furnaces. The resistivity of ferrite magnets also varies depending on the oxygen concentration during sintering.
For example, when sintering is performed in an atmosphere with low oxygen concentration such as in a gas furnace, the reduction reaction of iron oxide (FezOi) increases and Fe
Oil increases, and the resistivity is lower than when the oxygen concentration is high.

Any of the above-mentioned means for lowering the resistivity may be used as long as it does not lower the magnetic properties, and if several of these are combined, the resistivity will be lower and electrodeposition coating will be easier.

Additionally, the additives in ferrite magnets form glass-like grain boundary layers through liquid phase sintering, and electrical conduction in this grain boundary layer is usually considered to be ionic conduction, and when monovalent alkali ions are included, ion movement occurs. becomes easier. Therefore, sodium oxide (NazO) and potassium oxide (K, 0) are used as additives.
By adding a compound containing a monovalent alkali ion such as 5iOz or SiO□-B 203 + S t Oz-CaO in combination, the resistivity of the ferrite magnet can be reduced.

In this case, the amount of the compound containing monovalent alkali ions added is preferably in the range of 0.05 to 0.5%. If it is less than 0.05%, there is no effect, and if it exceeds 0.5%, the magnetic properties will deteriorate.

The coating method according to the present invention can be carried out, for example, by the following procedure.

First, the surface of the magnet to be coated is cleaned by degreasing and cleaning. As a surface treatment, a chemical conversion treatment may be further performed in order to improve rust prevention and adhesion. Next, the magnet body is immersed in an electrodeposition bath, and a direct current is passed between the magnet body and the opposing electrode to coagulate and precipitate paint particles on the surface of the magnet body, thereby performing electrodeposition coating. Thereafter, the magnet body is washed with water, drained and dried, and then baked (generally at a temperature of 150 to 200° C. for several 10 minutes to about 1 hour) to obtain a magnet body having an electrodeposited coating.

Anionic electrodeposition coating, which was the first to be industrialized among electrodeposition coatings, uses the object to be coated as an anode and the paint as a cathode.
Alkaline (PL+ 7.5-9.0), solid content concentration is about 10-15%) with a DC voltage of about 100-300 cm.
This can be done by applying it for about 3 minutes. The resins used in anionic electrodeposition paints are water-soluble or water-dispersible, and in order to make them water-soluble, carboxyl groups, hydroxyl groups, etc. are introduced into the molecules, and these are combined with ammonia, organic amines, or inorganic alkalis. It is stabilized in water by neutralizing it. Specific resins include maleated oil resins, polybutadiene resins, acrylic resins, alkyd resins, and polyester resins.

On the other hand, in cationic electrodeposition coating, the object to be coated is used as a cathode and the paint is used as an anode.
5.5 to 7.0), solid content concentration is about 15 to 20%]
This can be done by applying a DC voltage of about 00 to 350 V for about 2 to 3 minutes. In order to impart cationic properties to the resins used in cationic electrodeposition paints, basic amino groups, onium bases, etc. are introduced into the molecules, and the resins are neutralized with acids such as lower organic acids and inorganic acids to become water-soluble. Or it is water-dispersed.

Specific examples of the resin include epoxy resins such as epi-bis type and bisphenol type, acrylic resins, polybutadiene resins, and polyurethane resins.

In the present invention, the volume resistivity (hereinafter simply referred to as resistivity) of the oxide permanent magnet is as follows:
After polishing to a certain size of 15 fins wide and 7 fins thick,
At a temperature of 20°C, a 5.
The electrical resistance was measured by applying a DC voltage of 00V (DC200V/cra), and the value was calculated from the trial calculation formula: resistivity=resistance×cross-sectional area/length.

〔Example〕

EXAMPLES The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 Strontium carbonate (SrC(h) and iron oxide (Feze)
s) in a molar ratio of SrO and Fe2O of 1:5.8, calcined at 1200°C for 2 hours, and finely pulverized the mixture with diboron trioxide (8gO
3) is formed, n, o, and expressed in weight% (the same applies hereinafter).
Boric acid (HJ(h) was added to give a concentration of 0.05%, silicon oxide (SiO□) was added at 0.2 to 0.65%, and calcium oxide (Cab) was added at O-0.9%. Each type was pulverized to an average particle size of 0.8 μ using a wet pulverizer, and after applying a pressure of 0.4 t/1 ffl and molded in a magnetic field of about 8 KOe, it was sintered at 1200°C and 1) 50°C for 2 hours each. A total of 18 types of strontium ferrite magnets, including two types with different sintered densities, were obtained.

Furthermore, after degreasing these ferrite magnets with alcohol, cationic electrodeposition coating was performed using an epoxy electrocoating paint (Nippon Pain II Power Top U-30 Black) at a coating voltage of 300V for a coating time of 3 minutes. Washing, draining,
After drying, baking treatment was performed at 190℃ for 1 hour, and the first
The grained rice shown in the table was obtained. Table 1 shows the relationship between additive conditions, sintered body density, resistivity, and electrodeposition results for each sample.

As is clear from Table 1, this increase in resistivity makes electrodeposition coating impossible. From this example, it can be seen that, specifically, when the resistivity becomes about 10<7>Ω·cm or more, electrodeposition coating of the ferrite magnet becomes impossible.

Figure 1 shows the relationship between the amount of CaO added and resistivity when the sintering temperature is 1200°C, and Figure 2 shows the relationship between the amount of CaO added and resistivity when the sintering temperature is 1) 50°C9 Curves a and d in the figure contain 0.2% Sin□, and curves b and e contain 0.4% SiO2.
, C and r indicate that Sing is 0.5. At this time, the residual magnetic flux density (Br) and coercive force (+l
1c) had the results shown in FIGS. 3 and 4.

As is clear from FIGS. 1 and 2, the resistivity of the ferrite magnet increases significantly as the amount of CaO, which is a grain boundary component, added increases.

Furthermore, as shown in curve d in Figure 2, there is a point where the resistivity increases even when no CaO is added, but as is clear from Table 1, this is because the density of the sintered body has decreased significantly and the grains It can be seen that the resistance also increases when the amount of vacancies remaining in the field is large.

From Figures 3 and 4, the magnetic characteristics residual magnetic flux density (Br) and coercive force (+Hc) change depending on the amount of additives, and 5t
The higher the ozfl, the higher the coercive force 1+ Hc≧30000e)
It is easy to obtain <Ca0it increases and the weight % ratio with SiO□ becomes close to Cab/Sing #2, so 1l
It can be seen that lc is rapidly decreasing. Therefore, if the CaO weight % ratio CaO/SiO□ is set to 1.5 or less, the electrical resistance can be lowered (approximately 106 Ω·cm or less) without deteriorating the magnetic properties, and electrodeposition coating can be easily performed. I understand.

In the case where CaO is not added, as shown in the curve d in Figure 2, there is no CaO in the grain boundaries, which increases the resistance significantly, and the resistivity is 1.
06 Ω・cm or less (4.2×10 6 Ω・cm), electrodeposition coating was possible, but the residual magnetic flux density was low due to the extremely low sintered body density (Br = 3600 G,
(below). At the same time, this material also has a low coercive force (
1Hc = 30,000e or less), this is thought to be due to the fact that no CaO, which is a sintering accelerator, was added, resulting in the formation of a liquid phase, resulting in poor magnetic properties.

Example 2 SrCOi and FezO3 were mixed at a molar ratio of 1:5.6, and SiO2 was added to this mixture at a weight percent of 0.
After adding 2% and further mixing, it was calcined at 1200°C for 2 hours, and when it was pulverized, 1) 0.1% of 3BO3,
Add 0.3% of Sin, 0.5% of CaO, and then add A
1.5% of lz(h) was pulverized to an average particle size of 0.8μ using a wet pulverizer, molded in a magnetic field in the same manner as in Example 1, and then sintered to produce a ferrite magnet. After polishing these ferrite magnets to a certain size, the electrical resistance was measured and the results shown in Figure 5 were obtained.
The figure also shows the sintered compact density of each sample. In the figure, curve g is the result at a sintering temperature of 1200°C, and h is the result at 1) 50°C.

A A z(h (also similar to CrzO3) is an additive used to increase the coercive force (+t!c) of ferrite magnets, but at the same time reduces the residual magnetic flux density (Br) and sintered body density. Fifth The figure also shows that the sintered body density decreases as i20.fiO increases, and the sintered body density is 4.8.
It can be seen that the resistivity increases as the resistivity becomes lower than around 0 g/cot. When these samples were electrodeposited using the same method as in Example 1, the density of the sintered body was 4.80 g/cot.
The results showed that those higher than cffl could be electrodeposited, but those lower than cffl could not be electrodeposited.

Therefore, it can be seen that when electrodepositing a ferrite magnet, the density of the sintered body must be 4.80 g/cff1 or more.

Example 3 Strontium carbonate (SrCO3) and iron oxide (Fe20
:+) in molar ratio SrO:FezO1=1:
5.7, calcined at 1200°C for 2 hours, and finely pulverized the silicon oxide (by weight%).
SiO□) 0.5%, calcium oxide (Cab) 0
．． Added 6% and reduced the average particle size to 0.8μ using a wet pulverizer.
8 K by applying a pressure of 0.4 t/ant.
After molding in a magnetic field of Oe, the magnets were sintered at a temperature of 1200° C. for 2 hours while varying the oxygen concentration to obtain three types of strontium ferrite magnets.

Further, these ferrite magnets were subjected to cationic electrodeposition coating under the same conditions as in Example 1, washed with water, drained and dried, and then baked at 190° C. for 1 hour to obtain coated products.

Table 2 shows the results of measuring the sintering conditions, resistivity, and film thickness after electrodeposition of each sample.

Table 2 From Table 2, Sin□ and CaO are 0.5% and 0.5%, respectively.
It can be seen that by adding 6% and setting CaO/SiO□=1.2, the resistivity becomes less than 10 7 Ω·cm and single electrodeposition coating is possible. It can also be seen that as the oxygen concentration in the sintering atmosphere decreases, the resistivity decreases, making it easier to form a thick electrodeposited film.

Comparative Example 1 A product mixed and calcined in the same manner as in Example 3 was finely pulverized, and 0.5% of SiO□ and 0.8% of CaO were added in terms of weight percent, and under the same conditions as in Example 1. , finely pulverize, form,
Sintered at 1200℃ for 2 hours under conditions of different oxygen concentrations.
Various types of strontium ferrite magnets were obtained. Table 3 shows the resistivity of these ferrite magnets.

Table 3 All of these magnets had resistivities of 107Ω·0 or more due to the excessive amount of CaO added, making electrodeposition coating impossible. Therefore, although the resistivity shows a smaller value as the oxygen concentration decreases, a large amount of CaO is added (SiO□/CaO weight %).
It can be seen that when the ratio is 1.5 or more), electrodeposition coating becomes difficult.

Example 4 Molar ratio of SrO: Peg's = 1: 5.6
5rCO, and Fe, 03 are mixed, 0.2% SiO2 (weight%) is added as an additive during mixing, and the mixture is calcined at 1200°C for 2 hours, and then finely pulverized. to which 0.4% of 5ift and 0.8% of CaO were added, and those with and without the addition of 0.1% of Na and O were each finely pulverized to an average particle size of 0.8 μm using a wet pulverizer. 0
．． After molding in a magnetic field of 8 KOe under a pressure of 4 t/aJ, sintering was performed at 1200° C. for 2 hours at an oxygen concentration of 20% to obtain two types of strontium ferrite magnets. Table 4 shows the resistivities of these ferrite l-m stones.

Table 4 It can be seen from Table 4 that the resistivity of the ferrite magnet is lower when Na and 0 are added. Therefore, Na2 as an additive
It can be seen that by adding a compound containing monovalent alkali ions such as O, electrodeposition coating on ferrite magnets becomes easier. As a result of electrocoating these magnets in the same manner as in Example 1, the resistivity was less than 10 7 Ω·1, so the electrocoating could be performed.

However, the thickness of the paint film is 3.
5 μm, and 50 μm with Na2O added.

Example 5 Strontium carbonate (SrCO,) and iron oxide (FezO)
i) is mixed with SrO, Fe, and 03 in a molar ratio of 1:5.8, 1) calcined at 50°C, and when pulverized, 8203 is formed in the sintering process. ShiB2O3
83BO3 was added to give a concentration of 0.05%, and SiO2 was further added to 0.3 to 0.7%, and CaO was added to a concentration of 0.2 to 1.
2%, SrO 0.1-0.9%, Cr, 0. 0.7
% added were each pulverized to an average particle size of 0.8 pm using a wet pulverizer, applied a pressure of 0.4 t/c+J, molded in a magnetic field of approximately 8 KOe, and sintered at 1210°C for 2 hours. Ninety types of strontium ferrite magnets were obtained.

Next, these ferrite magnets were subjected to electrodeposition coating, washing, draining, drying, and baking treatments under the same conditions as in Example 1. Then, the magnetic properties and resistivity of each sample obtained were measured. FIG. 6 shows the relationship between CaO addition and molar ratio, magnetic properties, and volume resistivity.

In Figure 6, curve i is the line where the resistivity is lXl0'Ωcm when the amount of SiO□ added is 0.7% by weight, and curve j is the line where the resistivity is 1X10'Ωcm when the amount of SiO□ added is 0.5% by weight. The curve has a line with a ratio of I
When the amount of g added is 0.3% by weight, the resistivity is 1 x 107Ω
.cm, and a resistivity of less than 10 7 Ω·1 is obtained in the region below each curve.

In addition, in the same figure, the area surrounded by diagonal lines has a Br of 40
This is the range in which magnetic properties of 00 G or more and Hc of 40000e or more can be obtained. However, this region is SiO
This is based on the measurement results when the addition amount of No. 2 was 0.35 to 0.65%.

From FIG. 6, it can be seen that 5402 is in the range of about 0.3 to 0.7% by weight, the molar ratio is about 5.5 to 6.1, and CaO is in the range of about 0.5 to 1.2% by weight. It can be seen that high magnetic properties can be obtained when Also, under these conditions, the molar ratio and S
It can also be seen that by balancing the amounts of iO□ and CaO added, a resistivity of less than 10 7 Ω·cm can be obtained.

In addition, in the above example, the case where cationic electrodeposition coating was performed was explained, but since oxide permanent magnets have almost no elution even when used as an anode material, the object to be coated is used as an anode (+), a paint tank or It is also possible to perform anionic electrodeposition coating using a separately provided electrode plate as a cathode (-), and the present invention is not limited to cationic electrodeposition coating.

(Effects of the Invention) As described above, according to the present invention, electrodeposition coating is possible even on oxide permanent magnets that are considered to be insulators, and an extremely thin and uniform surface coating is possible regardless of the complexity of the shape. can be obtained.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between CaO addition amount and resistivity in ferrite magnets sintered at 1200℃, Figure 2 is 1)
Figure 3 shows the relationship between CaO addition amount and resistivity in ferrite magnets sintered at 50°C, Figure 3 shows the relationship between CaO addition amount and magnetic properties in 1200°C sintering, and Figure 4 shows 1) 50 Figure 5 shows the relationship between the amount of CaO added and magnetic properties during sintering at °C. Figure 5 shows the relationship between the amount of Al 203 added, resistivity and sintered body density. Figure 6 shows the relationship between the molar ratio, Ca
FIG. 3 is a diagram showing the relationship between the amount of added O, resistivity, and magnetic properties. Fig. 1 CaO addition amount (wt%) Fig. 2 Coo addition amount (wt%) Fig. 3 Coo addition amount (wt%) Fig. 4 Coo addition amount (wt%) Fig. 5 0 0.5 1.0 +,
5AI20s addition amount (weight%)

Claims (9)

[Claims] (1) Molar ratio of Fe_2O_3/MO (M is Sr, B is
a, one or two of Pb) = 5.3 to 6.2, a volume resistivity of less than 10^7 Ω cm, and a sintered body density of 4.80 kg/cm An oxide permanent magnet characterized in that a film of electrodeposition paint is formed on the surface of a magnet body having a diameter of ^3 or more. (2) The oxide permanent magnet according to claim 1, wherein the electrodeposition paint is a cationic electrodeposition paint. (3) The magnet body contains 0.1 to 1.0% by weight of SiO_2.
Contains 0.1 to 1.2% by weight of CaO and contains CaO/
The oxide permanent magnet according to claim 2, wherein the weight ratio of SiO_2 is less than 1.5. (4) The magnet body is a permanent oxide according to claim 2, containing 0.1 to 1.0% by weight of SiO_2 and 0.05 to 0.5% by weight of a monovalent alkali ion compound. magnet. (5) The magnet body further contains 0.01 to 0.1 B_2O_3.
5. The oxide permanent magnet according to claim 4, containing 0.1 to 1.2% by weight of CaO. (6) The magnet contains 0.01 to 0.1% by weight of B_2O_3, 0.1 to 1.0% by weight of SiO_2, and 0.1% by weight of CaO.
The oxide permanent magnet according to claim 2, containing 1 to 1.2% by weight. (7) The oxide permanent magnet according to claim 6, wherein the magnet body further contains 1.5% by weight or less of Al_2O_3 or 2.0% by weight or less of Cr_2O_3. (8) The magnet has a molar ratio in the range of 5.6 to 6.0, with 0.5 to 1.2% by weight of CaO and 0.5% by weight of SiO_2.
The oxide permanent magnet according to claim 2, containing 3 to 0.7% by weight. (9) Fe_2O_3/MO (M is Sr, B is
a, one or two of Pb) = 5.3 to 6.2, a volume resistivity of less than 10^7 Ω cm, and a sintered body density of 4.80 kg/cm A magnet body having a diameter of ^3 or more is immersed in a solution in which cationic electrodeposition paint is dispersed, and a DC voltage is applied between the magnet body and a counter electrode to form cationic electrodeposition on the surface of the magnet body. A method of painting an oxide permanent magnet, which is characterized by forming a film of paint.