JPS61130453A - Permanent magnet material having superior corrosion resistance and its manufacture - Google Patents

Abstract

PURPOSE:To inhibit the surface oxidation of a permanent magnet body and to prevent deterioration in the magnetic characteristics by coating the surface of the magnet body contg. prescribed percentages of a rare earth element, B and Fe with paint by electrodeposition to form a corrosion resistant resin layer. CONSTITUTION:A permanent magnet body contg., by atom, 3-30% one or more kinds of rare earth elements including Y, 2-28% B and 42-90% Fe as the principal components and having a tetragonal phase as the principal phase is manufactured. The magnet body is immersed in water paint and coated by electrodeposition to form a corrosion resistant resin layer on the surface. By the resin layer, the surface oxidation of the magnet body is suppressed, and deterioration in the magnetic characteristics is prevented.

Description

Detailed Description of the Invention Field of Application This invention relates to a permanent magnet material whose main components are R (R is at least one rare earth element including Y), B, and Fe, and which improves the corrosion resistance of the permanent magnet material. Improved rare earths, boron,
This invention relates to iron-based permanent magnet materials and manufacturing methods thereof.

BACKGROUND OF THE INVENTION Current typical permanent magnet materials are alnico, octoferrite, and rare earth cobalt magnets.

As the raw material situation for cobalt has become unstable in recent years, demand for alnico magnets containing 20 to 3 wt% cobalt has decreased.
Inexpensive hard ferrite, whose main component is iron oxide, has come to dominate magnet materials.

On the other hand, rare earth cobalt magnets contain 50 to 60wt of cobalt.
%, and it is very expensive because it uses copper, which is not included in rare earth ores, but compared to other magnets,
Due to its extremely high magnetic properties, it has come to be used mainly in small, high-value-added magnetic circuits.

Therefore, the present inventors have previously proposed an Fs-BR-based permanent magnet (where R is at least one rare earth element including Y) as a new high-performance permanent magnet that does not contain expensive) or G. (Gan Sho 57-145072). This permanent magnet is
It is an excellent permanent magnet that uses abundant light rare earth materials such as ceramics and circles as R, and shows an extremely high energy product of 25 MGO@ or more with F as its main component.

However, Fs-
Permanent magnets made of BR-based magnetically anisotropic sintered bodies contain rare earth elements and iron, which tend to oxidize in the air and gradually form stable oxides, so when incorporated into a magnetic circuit, The oxides generated on the magnet surface cause a decrease in the output of the magnetic circuit and variations between the magnetic circuits, and there is also the problem of contamination of peripheral equipment due to the falling off of the surface oxide.

Therefore, in order to improve the corrosion resistance of the above-mentioned F/-[3-R permanent magnets, we proposed a permanent magnet whose surface was coated with a corrosion-resistant resin layer by spraying or dipping (Japanese Patent Application No. 171907/1983). )did. However, since resin coating using the spray method is directional, it takes a lot of time and effort to apply a uniform resin coating to the entire surface of the object being treated.
In particular, it is difficult to apply a coating of uniform thickness to irregularly shaped magnets with complex shapes, and the dipping method results in non-uniform resin coating thicknesses, resulting in poor product dimensional accuracy.

Purpose of the Invention The object of the present invention is to provide a permanent magnet material mainly composed of rare earths, boron, and iron, which has improved corrosion resistance. The purpose is to provide a manufacturing method that can provide a corrosion-resistant resin layer with a uniform thickness.

Structure and Effects of the Invention This invention provides R (wherein R is at least one kind of rare earth elements including Y) from 8 atomic % to 30 atomic %, and B from 2 atomic % to
A permanent magnet material characterized by having a corrosion-resistant resin layer by electrodeposition on the surface of a permanent magnet body whose main components are 28 atomic % and 42 atomic % to 90 atomic % Fe, and the main phase is a tetragonal phase. A permanent magnet body whose main phase is a tetragonal phase is immersed in a water-based paint, the permanent magnet body is used as an anode or a cathode, and a direct current is supplied between the permanent magnet body and the counter electrode, and the entire permanent magnet body is This is a method for producing a permanent magnet material with excellent corrosion resistance, which is characterized by electrically coating the material and forming a corrosion-resistant resin layer on the surface.

In order to suppress oxides generated on the surface of a water-based permanent magnet material, this invention forms a strong and stable corrosion-resistant resin layer with a uniform thickness on the surface, and this corrosion-resistant resin layer is formed by electrodeposition coating. By applying this, oxidation of the surface of the magnet body is suppressed, and the magnetic properties have the advantage of being stable over a long period of time without deterioration.

The method of forming a corrosion-resistant resin layer on the surface of a magnet material in this invention involves immersing a permanent magnet in a water-based paint, using the permanent magnet as an anode or a cathode, and supplying direct current between the permanent magnet and a counter electrode. This is an electrodeposition coating method in which the entire permanent magnet is electrically coated to form a corrosion-resistant resin layer on the surface.An anion electrodeposition coating method uses the magnet to be treated as an anode, or an anion electrodeposition coating method uses the magnet to be treated as a cathode. A cationic electrodeposition coating method can be employed.

The resin used for the above 7-ion electrodeposition coating is drying oil,
It is a polycarboxylic acid resin whose core is polyester, polybutadiene, epoxy ester, polyacrylic acid ester, etc. It is usually neutralized with an organic amine or a base such as caustic potassium, and then turned into an aqueous solution or dispersed to become negatively charged. .

In addition, the resin used for cationic electrodeposition coating is mainly a polyamino resin whose core is epoxy resin, acrylic resin, etc., and is usually neutralized with an organic acid and made into an aqueous solution or water dispersion. In this invention, the permanent magnet material surface N! By applying I coating, the thickness of the corrosion-resistant resin layer can be 5 to 30 mm.

Furthermore, for the purpose of rust prevention and improving paint film reinforcement, zinc oxide, zinc chromate, strontium chromate, etc. are added to the above resin.
It may contain a rust preventive pigment such as red lead, or it may contain benzotriazole.

In this invention, the above pigment contained in the resin is
The amount of benzotriazole may be 80% or less based on the amount of resin, and the amount of benzotriazole may be 5% or less based on the amount of resin.

In addition, before applying the resin layer by electrodeposition coating, it is also good to apply F-base treatment to the surface of the permanent magnet body, and the base treatment film may include a phosphate coating such as zinc phosphate, manganese phosphate, etc. Alternatively, a chromate coating is preferable, and in the case of a phosphate coating, the thickness of the chemical conversion coating for base treatment is 3 to 10 mm in terms of corrosion resistance, strength, and cost. The is thickness is preferably 5- or less in the case of chromate.

Further, the alloy for permanent magnets of this invention has a crystal grain size of 1 to 1.
00. At least 50vol.1% or more of a compound having a tetragonal crystal structure in the range of 1% to 50vol.
% of non-magnetic phase (excluding oxide phase).

Therefore, the permanent magnet of this invention mainly uses light rare earths, which are rich in resources, mainly ceramics and circles, as k, and Fe,
13. By using R as the main component, it has an extremely high energy product of 25 MGOe or more, a high residual magnetic flux density,
An excellent permanent magnet having high coercive force and high corrosion resistance can be obtained at low cost.

Reasons for limiting the permanent magnet material The rare earth element R used in the permanent magnet of this invention is 8 atomic %.
~30 atomic % Nd, Pr, Dy, HO.

At least one of Tb, or in addition, la, C
e, Gd, Er, Eu, P3 Tm.

Those containing at least one of Yb and Y are preferred.

Further, one type of R is usually sufficient, but in practice, a mixture of two or more types (Mitsuhmetal, dididium, etc.) can be used for reasons such as convenience of availability.

Note that this R does not have to be a pure rare earth element, and may contain impurities that are unavoidable in production within an industrially available range.

R (at least one rare earth element including Y) is an essential element in the above-mentioned novel permanent magnet, and when it is less than 8 at%, the crystal structure becomes a cubic structure that is the same as α-iron. Therefore, high magnetic properties, especially high coercive force, cannot be obtained.
If it exceeds 30 atomic %, the R-rich nonmagnetic phase increases, the residual magnetic flux density (Sr) decreases, and a permanent magnet with poor characteristics cannot be produced. Therefore, the rare earth element is in the range of 8 atomic % to 30 atomic %.

B is an essential element in the new above-mentioned permanent magnet, and if it is less than 2 atom%, it will form a rhombohedral structure and a high coercive force (1f-1c) cannot be obtained, and if it exceeds 28 atom%,
The B-rich nonmagnetic phase increases, and the residual magnetic flux density (Sr
) decreases, making it impossible to obtain an excellent permanent magnet. Therefore, B is in the range of 2 atomic % to 28 atomic %.

Fe is an essential element in the new above-mentioned permanent magnet.If it is less than 42 at%, the residual magnetic flux density (Br) decreases, and if it exceeds 90 at%, a high coercive force cannot be obtained. The content is from atomic % to 90 atomic %.

In addition, in the alloy for permanent magnets according to the present invention, replacing a part of Fe with 6 can improve the temperature characteristics without impairing the magnetic properties of the resulting magnet.
If the amount of o substitution exceeds 50% of Fs, the magnetic properties will deteriorate, which is not preferable.

Further, the permanent magnet according to the present invention has R and B magnets.

In addition to Fe, the presence of unavoidable impurities in industrial production can be tolerated, but a portion of B may be 4.0 atomic % or less of C13, 5 atomic % or less of P, 2.5 atomic % or less of S, 3. At least one type of Cu of 5 at% or less, 4.0 at% in total amount
By substituting with the following, it is possible to improve the manufacturability and reduce the cost of permanent magnets.

Furthermore, at least one of the following additional elements is R-B-
It is added to Fe-based permanent magnets because it is effective in improving coercive force, etc., improving manufacturability, and reducing costs. However, the residual magnetic flux density (B
r ), it is desirable to add it in a range that is equal to or higher than the residual magnetic flux density of conventional hard ferrite magnets.

9.5 atomic % or less of At, 4.5 atomic % or less of Ti.

9.5 atomic % or less of V, 8.5 atomic % or less of Cr.

8.0 atomic % or less of Mn, 5 atomic % or less of 81.12.
Nb of 5 atomic % or less, Ta of 10.5 atomic % or less.

Mo2S of 9.5 atomic % or less, W of 5 atomic % or less, 2.
sb of 5 atom% or less, Qe135 atom% of 7 atom% or less
The following 3n15.5 atomic % or more of F lr.

Addition of at least one type of Hf of 5.5 atomic % or less; however, if two or more types are contained, the maximum content shall be atomic % or less of the one with the maximum value among the added elements. , it becomes possible to increase the coercive force of permanent magnets.

It is essential for the main crystal phase to be tetragonal in order to produce a sintered permanent magnet with excellent magnetic properties.

Further, the permanent magnet of the present invention can be press-molded in a magnetic field to obtain a magnetically anisotropic magnet, and can be press-molded in a non-magnetic field to obtain a magnetically isotropic magnet.

The permanent magnet according to the present invention has a coercive force of 1l-1c≧1KO
e, the residual magnetic flux density Br > 4KG, the maximum energy product (BH) wrax is equal to or higher than that of hard ferrite, and in the most preferable composition range, (BH)I
laX≧10MGOe, maximum value is 25MGOe
reach more than that.

Further, the main component of R in the alloy for permanent magnets of this invention is 50
% or more is occupied by light rare earth metal, R12 atomic % ~
20 atom%, B44 atom to 24 atom%, F.65 atom%
~82 at% as the main component, the sintered magnet also exhibits excellent magnetic properties, and especially when the light rare earth metal is ceramic, (BH)IlaX has a maximum value of 35 MGOe.
reach more than that.

Examples Example 1 As a starting material, electrolytic iron with a purity of 99.9%, 819.4
A ferroboron alloy with a purity of 99.7% or more is used, and the rest is made of impurities such as F, M, and S5C, which are melted by high frequency, and then cast into a water-cooled copper mold.
An ingot with a composition of 15 porcelain 8877F (atomic %) was obtained.

Thereafter, the ingot was coarsely ground using a stamp mill and then ground using a ball mill to obtain a fine powder with a particle size of 3 millimeters.

This fine powder was inserted into a mold, oriented in a magnetic field of 12 KOs, and molded at a pressure of 1.5 t4.

The obtained compact was sintered at 1100°C for 1 hour in Ar, then allowed to cool, and further sintered at 600°C in Ar.
A permanent magnet was produced by subjecting it to aging treatment at ℃ for 2 hours.

A test piece was cut out from the obtained permanent magnet to have dimensions of outer diameter 2 (1 mm) x inner diameter 10 m x thickness 1.5 m.

Epoxy Nisbia CE is used as a cationic Ti coating.
D, 5-20 (manufactured by Shinto Paint Co., Ltd.), the above test piece previously degreased with trichlorene was used as a cathode, and 5US
A 316 wood plate was used as the anode, and the temperature was 28°C.

Electrodeposition coating was performed at a voltage of 150 V for 3 minutes.

Then, after washing with water and air drying, the sample was held at 180° C. for 30 minutes to produce a permanent magnet sample piece according to the present invention with a resin layer coated on the surface. This test piece was subjected to a corrosion resistance test and an adhesion strength test of the resin layer after the corrosion resistance test. In addition, the resin layer thickness and magnetic properties before and after the corrosion resistance test were measured. The test results and measurement results are shown in Table 1.

For comparison, the above test piece was coated with epoxy paint twice on the front and back surfaces using a spray method.
A comparative test piece was obtained by drying at 80° C. for 1 hour and having a coating film formed by spraying on the surface. This comparative test piece was subjected to the same tests and measurements as in Example 1 above, and the results are also shown in Table 1.

The corrosion resistance test was evaluated based on the appearance of the test piece when it was left in an atmosphere of 60° C. and 90% humidity for 200 hours.

In addition, in the adhesion strength test, the above test piece after the corrosion resistance test was
Folds spaced at 1 mm intervals were pulled with an adhesive tape, and evaluation was made based on whether or not the resin layer peeled (number of folds without peeling/number of total squares).

Example 2 Starting materials contained electrolytic iron and electrolytic cobalt with a purity of 99.9% and 819.4%, with the remainder being Fe, #, and SL.

Ferroboron alloy consisting of impurities such as C, purity 99.1
% or more, melted them using high frequency, and cast them in a water-cooled steel mold to produce 16tJ 7E31QCO67F+
An ingot with a composition of 1 (atomic %) was obtained.

Thereafter, the ingot was coarsely ground using a stamp mill, and then ground using a ball mill to obtain a fine powder with a particle size of 3.

This fine powder was inserted into a mold, oriented in a magnetic field of 12 KO@, and molded at a pressure of 1.5 t4.

The obtained molded body was heated at 1100°C for 1 hour in Ar.
Sintered under the conditions of
A permanent magnet was produced by subjecting it to aging treatment at ℃ for 2 hours.

The obtained permanent magnet has an outer diameter of 20 mm and an inner diameter of 10 mm.
A test piece was cut out to a size of 1.5 m in thickness.

As a 7ion ms paint, acrylic Nisbia ED,
108-U (manufactured by Shinto Paint Co., Ltd.), the above test piece previously degreased with Trichlorene was used as an anode, and 5tJS was used.
A 316 material plate was used as the cathode, and the temperature was 28°C.

Electrodeposition coating was performed at a voltage of 230 V for 2 minutes.

Then, after washing with water and air drying, the sample was held at 180° C. for 30 minutes to produce a permanent magnet sample piece according to the present invention with a resin layer coated on the surface. This test piece was subjected to a corrosion resistance test using the same method as in Example 1 and an adhesion strength test of the resin layer after the corrosion resistance test. In addition, the resin layer thickness and magnetic properties before and after the corrosion resistance test were measured. The test results and measurement results are shown in Table 1.

Example 3 Ex-RiF1. ! :L, r, [99,9% (1)? IJ iron, containing 819.4%, the balance being Fs, M, SL,
Ferroboron alloy consisting of impurities such as C, purity 99.7
% or more of movable metals, these are high frequency melted and cast into a water-cooled steel mold to form a 1.5Dy BB
An ingot having a composition of 75.5Fs (atomic %) was obtained.

Thereafter, the ingot was coarsely ground using a stamp mill, and then ground using a ball mill to obtain a fine powder with a particle size of 3A1111.

This fine powder was inserted into a mold, oriented in a magnetic field of 12 KO@, and molded at a pressure of 1.5 t4.

The obtained compact was sintered at 1100°C for 1 hour in Ar, then allowed to cool, and further heated at 600°C in an Ar atmosphere.
A permanent magnet was produced by subjecting it to aging treatment for 2 hours.

Outer diameter 20mm x inner diameter 10m +++
A test piece was cut out to a size of 1.5 nm + thickness.

Next, after degreasing the test piece with Triclean,
Q/t, phosphorus 1117.8 M i (1) 18
The sample was immersed in a salt solution at 15° C. for 3 minutes.

Epoxy Nisbia CED as a cationic electrodeposition paint
, 5-20 (Shinto Paint Co., Ltd.!!l), the above test piece was used as the cathode, the 5LIS316 material plate was used as the anode,
Electrodeposition coating was performed at a temperature of 28° C., a voltage of 150 V, and a duration of 3 minutes.

Then, after washing with water and air drying, the sample was held at 180° C. for 30 minutes to produce a permanent magnet sample piece according to the present invention with a resin layer coated on the surface. This test piece was subjected to a corrosion resistance test and an adhesion strength test of the resin layer after the corrosion resistance test. In addition, the resin layer thickness and magnetic properties before and after the corrosion resistance test were measured. The test results and measurement results are shown in Table 1.

As is clear from the test and measurement results in Table 1 below, the resin layer according to the present invention has a film thickness of the required thickness compared to the comparative example.
In addition, it can be seen that since extremely excellent uniformity was obtained, oxidation of the permanent magnet body was reliably prevented, there was no deterioration of the magnetic properties, and the magnetic properties were significantly improved compared to the comparative example.

Claims (1)

[Claims] 1 R (wherein R is at least one rare earth element including Y) 8 at% to 30 at%, B 2 at% to 28 at%, Fe 42 at% to 90 at% A permanent magnet material with excellent corrosion resistance characterized by having a corrosion-resistant resin layer coated by electrodeposition on the surface of a permanent magnet whose main phase is a tetragonal phase. 2 R (where R is at least one rare earth element including Y) 8 at% to 30 at%, B 2 at% to 28 at%, Fe 42 at% to 90 at%, and the main phase is square A permanent magnet consisting of a crystalline phase is immersed in a water-based paint,
The permanent magnet is used as an anode or a cathode, a direct current is supplied between the permanent magnet and a counter electrode, the entire permanent magnet is electrically coated, and a corrosion-resistant resin layer is formed on the surface. A method of manufacturing a permanent magnet material with excellent corrosion resistance.