JPS62120003A - Permanent magnet with excellent corrosion resistance and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance of a permanent magnet by providing a corrosion resistant vapor-phase plating layer on the sintered permanent magnet which mainly contains R (R is at least one of rare earth elements including Y) B and Fe, and tetragonal crystal of main phase and filling a resin in the fine pores of the plating layer. CONSTITUTION:Rare earth elements R are included in a range of 10-30atom%. If less than 10atom%, high magnetic property and hence high coercive force is not obtained, and if more than 30atom%, its remaining magnetic flux density Br decreases. B is included in a range of 2-28atom%. If less than 2atom%, high coercive force (iHc) is not obtained, and if more than 28atom%, its remaining magnetic flux density Br decreases. Fe is included in a range of 65-80atom%. If less than 65atom%, the remaining magnetic flux density Br decreases, and if more than 80atom%, high coercive force is not obtained. After the surface layer of the sintered magnet is removed, the surface of the magnet is covered with a thin corrosion resistant plating layer, then shot peened, impreg nated with thermoset resin, cleaned, dried and then thermoset.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application This invention relates to an Fa-B-R permanent magnet with excellent corrosion resistance and a method for manufacturing the same. Fe-B-R system with excellent corrosion resistance that prevents deterioration of magnetic properties due to grinding of the magnet surface, and improves the adhesion of the corrosion-resistant coating of the magnet material and the deterioration of corrosion resistance due to fine pores in the coating. Permanent magnets and their manufacturing methods.

BACKGROUND ART Current typical permanent magnet materials are alnico, hard ferrite, and rare earth cobalt magnets, which have excellent magnetic properties, are inexpensive, and are composed of elements that are abundant in resources and can be stably supplied in the future. Permanent magnetic materials have been desperately needed.

The present applicant previously proposed a Fe-B-R-based permanent magnet (R is at least one rare earth element including Y) as a new high-performance permanent magnet that does not contain expensive Smf)Co (Japanese Patent Application Laid-Open No. No. 59-46008, Japanese Patent Publication No. 59-647
No. 33, JP-A-59-89401, JP-A-59-13
No. 2104).

This permanent magnet uses resource-rich light rare earths such as ceramics and circles as R, and contains 258% B and Fe as main components.
It is an excellent permanent magnet that exhibits an extremely high energy product of over GOa, reaching up to over 458 GOe.

Recently, with the improvement in performance and miniaturization of magnetic circuits, Fe-B
-R-based permanent magnet materials have been attracting more and more attention.

In order to manufacture permanent magnet materials for such uses, it is necessary to remove irregularities and distortions on the surface of the sintered magnet body, to remove surface oxidation layers, and to incorporate the magnet body into a magnetic circuit. It is necessary to cut or grind the entire surface or the required surface, and for processing, an outer peripheral blade cutting machine and an inner peripheral blade cutting machine are used.

Surface grinders, centerless grinders, lapping machines, etc. are used.

However, when the Fe-B-R permanent magnet material is cut or ground, the main component of the Fe-B-R permanent magnet material is rare earth, which is extremely easily oxidized in the air and immediately forms stable oxides. Because it contains elements and iron,
There is a problem in that an oxide layer is generated due to heat generation or contact between the atmosphere and the machined surface, leading to deterioration of magnetic properties.

In addition, when a permanent magnet made of an FaBR-based magnetically anisotropic sintered body is incorporated into a magnetic circuit, oxides generated on the magnet surface may cause a decrease in the output of the magnetic circuit and variations in characteristics between the magnetic circuits. There was also the problem of contamination of peripheral equipment due to shedding of surface oxides.

Therefore, in order to improve the corrosion resistance of the above-mentioned Fa BR permanent magnet, the applicant first developed a permanent magnet (patent application filed in 1983) whose surface was coated with a corrosion-resistant metal plating layer by electroless plating or electrolytic plating. -162350) and proposed a permanent magnet in which the surface of the magnet body was coated with a corrosion-resistant resin layer by spraying or dipping (Japanese Patent Application No. 58-1719).
07@) L/ta.

However, in the former plating method, since the permanent magnet body is a sintered body and is porous, there is a risk that acidic or alkaline solutions may remain in the pores during plating pretreatment, leading to rusting over time. Due to the poor chemical resistance of the magnet body, there was a problem that the magnet surface was corroded during plating, resulting in poor adhesion and corrosion resistance.

Furthermore, since resin coating using the latter 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 to be treated, and it is especially difficult to apply uniformly to odd-shaped magnets with complex shapes. It is difficult to apply a thick coating, and the dipping method results in uneven resin coating thickness, resulting in poor product dimensional accuracy.

Therefore, as a method for improving the corrosion resistance of Fe-B-R permanent magnets, the inventors applied a thin film forming technique to the surface of the sintered magnet by grid blasting with hard powder having a specific particle size and hardness. proposed a permanent magnet material (Japanese Patent Application No. 110793/1982, Patent Application No. 200890/1982) in which a thin M film layer was deposited on the surface of the magnet body.

As a result, the corrosion resistance of F13-B-R permanent magnets has increased significantly, but the M thin film described above is formed by evaporated N particles deposited on the magnet surface during vapor deposition, etc., so it is difficult to maintain sufficient density. For example, even if a chromate film is formed on this thin film, it is impossible to completely eliminate the micropores. It may peel off or cause cracks in the thin film layer.
There was a problem of localized rust formation.

Purpose of the Invention The present invention improves the deterioration of magnetic properties caused by cutting or grinding of a sintered magnet body in a new permanent laminated material containing rare earth elements, boron, and iron as main components, and further,
It has improved adhesion and corrosion resistance without the use or contact with corrosive chemicals, and has a corrosion-resistant thin film layer surface that eliminates micropores within the thin film, allowing it to be used for long periods of time even in extremely harsh environmental conditions. The purpose is to create a permanent magnet with excellent corrosion resistance and a method for manufacturing the same.

Structure and Effects of the Invention The present invention provides the following features:
, Gd, Er, Eu, rm.

consisting of at least one of Yb, Lu, and Y)1
A corrosion-resistant vapor phase plating layer is provided on the surface of a sintered permanent magnet body whose main components are 0% to 30 at%, B2 at% to 28 at%, and Fe65 at% to 80 at%, and whose main phase is a tetragonal phase. The permanent magnet material further comprises a resin filled in the fine pores of the vapor plating layer.

Further, the present invention provides R (R is at least one of Na, Pr, Dy, +, Th, or furthermore, La, Ce,
Sm, (A, Er, Eu, Tm.

consisting of at least one of Yb, Lu, and Y)1
The main components are 0% to 30 atomic%, B2 atomic% to 28 atomic%, and Fe65 atomic% to 80 atomic%, and the main phase is a tetragonal phase.
, tm ~ 35011m, an amorphous hard powder consisting of at least one powder having a Mohs hardness of 5 or more is heated at a pressure of i, oh
, J~e, with pressurized gas of ohm, 0.5 min~60
After removing the surface layer of the magnet body by applying grid blasting for a minute, M, "In" was applied to the surface of the magnet body using a thin film forming technique.

A corrosion-resistant vapor phase plating thin film layer of TL, NL, Cr, etc. is applied, and a spherical powder consisting of at least one type of powder with an average particle size of 30 to 300011 m and a Mohs hardness of 3 or more is coated under a pressure of 1.0 k to 5 k. Shot peening is performed by spraying .0JJ of pressurized gas for 1 minute to 60 minutes,
Thereafter, the surface of the sintered magnet body is impregnated with a thermosetting resin by applying pressure in the air or in a vacuum, or after vacuuming, and then the surface of the magnet body is washed with a solvent or water, and after drying, it is subjected to a thermosetting treatment. , a method for producing a permanent magnet material characterized by improved corrosion resistance of a sintered magnet body.

Specifically, the present invention injects hard powder having desired properties onto the surface of a sintered magnet together with pressurized gas to eliminate surface layers such as black crust, oxidized layer, and strained layer of the sintered magnet. to improve the deterioration of magnetic properties caused by oxidation and cutting.
A vapor-phase plating thin film layer is deposited on the cleaned magnet surface, and a specific powder having a desired shape is injected together with pressurized gas to densify the vapor-phase plating thin film layer. After improving the adhesion between the film and the surface thin film layer, the film is further impregnated with a thermosetting resin to eliminate the micropores in the vapor plating layer, further improving the corrosion resistance of the permanent magnet material. It is.

Further, the permanent magnet material of this invention has an average crystal grain size of 1 to 8.
0. It is characterized by having a compound having a tetragonal crystal structure in the range of .

The manufacturing method of this invention uses resource-rich light rare earths such as ceramics and circles as R, and uses B and Fe as the main components to produce an extremely high energy product reaching 258 GOE1 or more, and at most 45 t4 GOE1 or more. It is an excellent permanent magnet that exhibits high residual magnetic flux density and high coercive force, and its surface is coated with a vapor-phase plating thin film that prevents deterioration of magnetic properties due to grinding and oxidized layers, and eliminates micropores and exhibits extremely high corrosion resistance. Fa-BR permanent magnet material stably adhered to
It can be obtained cheaply.

Preferred Embodiment of the Invention In the present invention, the amorphous hard powder having a Mohs hardness of 5 or more used for shot blasting includes #203 type, silicon carbide type, ZrO2 type, and boron carbide type.

Garnet-based powders are available, and M, O3-based powders with high hardness are preferred.

If the Mohs hardness of the above-mentioned amorphous hard powder is less than 5, the grinding force is too small and the grinding process takes a long time, which is not preferable.

In addition, the average particle size of the amorphous hard powder was 20. um~350
If the diameter is less than 20 μm, the grinding force will be too small and it will take a long time to grind, and if it exceeds 350 μm, the surface roughness of the sintered magnet will become too rough and the ground surface will be uneven. This is because it is not desirable.

In addition, the injection conditions for the amorphous hard powder were set at a pressure of 1.0 k.
If it is less than i4, the grinding process will take a long time and the pressure will be less than 6.
．． When okL34 is exceeded, the amount of grinding on the surface of the magnet body becomes uneven, and there is a concern that the surface roughness may deteriorate.

Furthermore, if the spraying time is less than 0.5 minutes, the amount of grinding will be small and non-uniform, and if it exceeds 60 minutes, the amount of grinding on the magnet surface will increase, which is undesirable as the surface roughness will deteriorate.

In addition, air or an inert gas such as Ar or N2 gas can be used as the pressurized fluid for injecting hard powder.
In order to prevent oxidation of the magnet, an inert gas is preferable.
Furthermore, when air is used, it is desirable to use dehumidified air.

In addition, in this invention, as the powder for shot peening, a spherical hard powder with a Mohs hardness of 3 or more is used, and steel balls, glass beads, etc. can be used, and the powder has a hardness equivalent to or higher than that of the vapor phase plated thin film layer. Glass peas are preferred.

If the Mohs hardness of the peening spherical powder is less than 3, the hardness will be lower than that of the vapor phase plated thin film layer, and the peening effect will not be obtained, which is not preferable.

In addition, the average particle size of spherical powder for peening is 3011 m~
The reason for setting 3000ρ is that if it is less than 30 terms, the pressing force against the vapor phase plated thin film layer is small and it takes a long time to process, and if it exceeds 300011 m, the surface roughness of the sintered magnet body surface becomes too rough. This is because the finished surface becomes uneven, which is not desirable. A more preferable average particle size is from 40 to 2
000 temple.

In addition, the injection conditions for the spherical powder are as follows: pressure 1.0, 13
If the pressure is less than 5.4, the pressing force against the vapor phase plating thin film layer will be small and the processing will take a long time. If the Oki deposition is exceeded, the pressing force on the vapor phase plated thin film layer becomes uneven, leading to deterioration of the surface roughness.Furthermore, if the spraying time is less than 1 minute, the entire surface cannot be uniformly treated, and the spraying time The upper limit of peening is determined by the amount of peening and processing conditions, but if it exceeds 60 minutes, the surface roughness will deteriorate, which is undesirable.

In the present invention, in order to deposit a vapor phase plated thin film layer on the clean surface of the sintered magnet body from which the oxidized surface phase has been removed, thin film forming methods such as vacuum evaporation, sputtering, and ion blasting can be appropriately selected and utilized. Moreover, as a vapor phase plating material, M, 'ln.

Metals such as Tj, Nj, Cr, or alloys thereof are preferred.

Furthermore, the thickness of the thin film layer is approximately 30 m, taking into account peeling of the thin film layer, reduction in strength in several areas, and ensuring corrosion resistance.
The following thickness is preferable, preferably 5 to 25 g
The layer thickness is .

In this invention, the resin to be impregnated into the micropores of the vapor-phase plated thin film layer is preferably an alcohol-soluble thermosetting phenolic resin with a small molecular weight, and the thermosetting conditions vary depending on the type of thermosetting resin to be impregnated. You can make assumptions as appropriate.

In addition, as a method for impregnating the thermosetting resin into the micropores of the thin film, immersion impregnation method, vacuum impregnation method, and vacuum pressure impregnation method can be adopted. If so, the means.

Conditions can be selected as appropriate.

Reasons for limiting the components of the permanent magnet material The rare earth element R used in the permanent magnet material of the present invention accounts for 10 to 30 at% of the composition.

At least one of Pr, Dν, Ho, Tb, or further, La, C8, Sm, CA, Er,
Eu, Tm, Yt), Lu.

Those containing at least one type of Y are preferred.

Also, normally one type of R is sufficient, but in practice two types are sufficient.
A mixture of more than one species (Mitushmetal, Didim, etc.) can be used for reasons such as 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 is an essential element in the new above-mentioned permanent magnet material, and if it is less than 10 atomic %, the crystal structure becomes a cubic structure that is the same as α-iron, so it has high magnetic properties, especially a high coercive force of 1q If it exceeds 30 at%, the R-rich nonmagnetic phase increases, and the residual magnetic flux density (Br) decreases.
Permanent magnets with excellent characteristics cannot be obtained. Therefore, the amount of rare earth elements is 10 atomic % to 30 atomic %.

B is an essential element in the permanent magnet material according to the present invention, and if it is less than 2 atomic %, the rhombohedral structure becomes the main phase and high coercive force (iHc) cannot be obtained, and if it exceeds 28 atomic %, B The rich nonmagnetic phase increases, and the residual magnetic flux density (
Br) 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 65 at%, the residual magnetic flux density (Br) decreases, and if it exceeds 80 at%, high coercive force cannot be obtained. The content is 65 atomic % to 80 atomic %.

In addition, in the permanent magnet material according to the present invention, replacing a part of FB with - can improve the temperature characteristics without impairing the magnetic properties of the resulting magnet.
If the amount of substitution exceeds 20% of FB, the magnetic properties will deteriorate, which is not preferable. When the amount of G substitution is 5 at % to 15 at % in the total amount of Fs and -, it is preferable to increase the high magnetic flux density by 1q, since (Br) increases compared to the case where no substitution is made.

Further, the permanent magnet material according to the present invention includes R, B.

In addition to FB, 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. Permanent by replacing at least one type of Qi with a total amount of 4.0 atomic % or less of 5 atomic % or less! It is possible to improve the manufacturability and lower the price of i-stone.

Furthermore, at least one of the following additional elements is RB-F
It can be added to s-based permanent magnets because it is effective in improving the coercive force and squareness of the demagnetization curve, improving manufacturability, and reducing costs.

A1 of 9.5 atom% or less; Ti of 4.5 atom% or less, 9
．． 5 at% or less V, 8.5 at% or less Cr, 8.0
Hn of atomic % or less, Bi of 5.0 atomic % or less, 9.
Nb of 5 at% or less, Dye a of 9.5 at% or less, 9.5
(at % or less) fo, 9.5 atomic % or less edge, 2.5 atomic % or less sb, 7 atomic % or less Ge, 3.5 atomic %
The following Sn, 5.5 atomic % or less Zr, 9.0 atomic % or less Ni, 9.0 atomic % or less Si, 1.1 atomic % or less Zn, 5.5 atomic % or less Hf.

At least one of these elements is added and contained; however, when two or more types are contained, the maximum content is less than or equal to the atomic percent of the element having the maximum value among the added elements.
It becomes possible to increase the coercive force of permanent magnets.

It is essential that the main phase of the crystalline phase is a tetragonal one in order to produce a sintered permanent magnet having superior magnetic properties than a fine and uniform alloy powder.

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 material according to the present invention has a coercive force iHc≧1 k
Oe, residual magnetic flux density 8r > 4 kG, maximum energy product (BH) maX is (BH) maX ≧ 10H
GOa, and the maximum value reaches 258 GOe or more.

Further, the main component of R of the permanent magnet according to the present invention is 5
In the case where 0% or more is occupied by light rare earth metals mainly composed of Nd and Yen, R12 at % to 20 at%, B44 at to 24
When the main component is F874 at% to 80 at%, it exhibits excellent magnetic properties of (BH)max 35)fGoθ or more, and especially when the light rare earth metal is ceramic, the maximum value is 458GOe. reach more than that.

Example 1- As starting materials, electrolytic iron with a purity of 99.9%, ferroboron alloy, and ceramics with a purity of 99.7% or more were used, and these were mixed and high-frequency melted, and then cast in a water-cooled copper mold. 15.
ONd8. An ingot having a composition of OB 77 and OFe was obtained.

Thereafter, this ingot was coarsely ground using a stamp mill, and then finely ground using a ball mill to obtain a fine powder with an average particle size of 31En.

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 in a direction perpendicular to the magnetic field.

The obtained molded body was sintered at 1100'C for 1 hour in an Ar atmosphere to obtain a sintered body with dimensions of 25 mm in length, 40 mm in width, and 30 mm in thickness.

Furthermore, 800'C, 1 hour and 630°C, 1 hour in Ar
, a two-stage aging treatment of 5 hours was performed.

The above permanent magnet was placed in the atmosphere using a diamond 1200 magnet.
Using a grinding wheel, rotation speed 240 rpm, feed speed 5
mm/min, length 5mm x width 10mm x thickness 3mm
Cut out to size.

Furthermore, using an amorphous /V 203 hard powder with an average particle size of 50 m and a Mohs hardness of 9, a pressure of 2
．． 5 to 9. Grid blasting was performed for 20 minutes with pressurized J and N2 gases to remove the surface layer of the magnet.

Next, the above sample was placed in a vacuum container with a vacuum degree of 5X 10''''5 Torr, Ar gas was introduced, and 1xtO-2T
After discharging for 15 minutes at a voltage of 500 V in Ar gas at
Using an N plate with a purity of 99%, it is heated to evaporate N.
ionized, and these ionized particles are attracted by the electric field,
It was attached to the test piece constituting the cathode to form a MWJ film. The thickness of the thin film formed on the surface of the test piece was 15 mm.

The above ion brating conditions are a voltage of 1.5 kV,
The treatment was for 10 minutes.

Furthermore, conditions were set in which spherical glass bead powder with an average particle size of 120 and a Mohs hardness of 6 was injected onto the magnet sample coated with the AIWJ film layer at a pressure of 1=5ki4 for 5 minutes with pressurized N2 gas. The test piece was subjected to shot peening and weighed 1 q.

The test piece was immersed in a thermosetting resin (trade name: Hytanol, manufactured by Hitachi Chemical Co., Ltd.) in a vacuum container of IP2 Torr, and the impregnation time was 3 minutes (present invention example 1) and 5 minutes (present invention example). After resin impregnation under the conditions of 2), the surface of the test piece was washed with a solvent, dried at 25°C, and then heat-cured at 140°C for 30 minutes in the air.

These test pieces were subjected to a corrosion resistance test and a thin film adhesion strength test after the corrosion resistance test. In addition, the magnetic properties before and after the corrosion resistance test were measured. The test results and measurement results are shown in Table 1.

In addition, for comparison, a test piece (Comparative Example 3) manufactured under the same conditions as the present invention example except that it was not impregnated with a thermosetting resin,
The as-cut test piece (Comparative Example 4) and the above test piece were solvent degreased with trichloride for 3 minutes and treated with 5% Na0).
After alkaline degreasing at 60°C for 3 minutes, 2% HC
J at room temperature in a pickling Watts bath for 10 seconds at a current density of 4 A/dm2. Under the conditions of bath temperature 60'C, 20 minutes,
A comparative test piece (Comparative Example 5) having a 2011 m thick nickel plating layer on the surface was obtained by electro-nickel plating.

These comparative test pieces were subjected to the above corrosion resistance test, a thin film adhesion strength test after the corrosion resistance test, and measurement of magnetic properties before and after the corrosion resistance test, and the results are also shown in Table 1.

The corrosion resistance test was evaluated based on the appearance of the test piece, adhesion strength, and magnetic properties before and after the corrosion test when the test piece was left in an atmosphere of 70'C, 90% humidity, and 1000 hours.

In addition, the adhesion strength test was evaluated by breaking the test pieces of Invention 1.2 and Comparative Examples 3 and 5 after the corrosion resistance test and observing the broken surfaces.

As is clear from Table 1, the method of the present invention prevents the deterioration of magnetic properties due to cutting, and also provides a permanent magnet with excellent dimensional accuracy and extremely high corrosion resistance. I understand.

Claims (1)

[Claims] 1 R (R is at least one of Nd, Pr, Dy, Ho, Tb, or furthermore, La, Ce, Sm, Gd,
At least one of Er, Eu, Tm, Yb, Lu, Y
The main components are 10% to 30 atomic% (consisting of seeds), 2 atomic% to 28 atomic% B, and 65 atomic% to 80 atomic% Fe, and the main phase is a tetragonal phase. A permanent magnet material comprising a mating layer and further comprising a resin filled in micropores of the vapor plating layer. 2 R (R is at least one of Nd, Pr, Dy, Ho, Tb, or furthermore, La, Ce, Sm, Gd,
At least one of Er, Eu, Tm, Yb, Lu, Y
Grid blasting is applied to the surface of a sintered permanent magnet body whose main components are 10% to 30 atomic% (consisting of seeds), 2 atomic% to 28 atomic% B, and 65 atomic% to 80 atomic% Fe, the main phase of which is a tetragonal phase. After removing the surface layer of the magnet body, the surface of the magnet body is subjected to vapor phase plating treatment, and after shot peening, the surface of the sintered magnet body is impregnated with a thermosetting resin, and then A method for producing a permanent magnet with excellent corrosion resistance, characterized in that the surface of the magnet body is washed with a solvent or water, dried, and then subjected to a heat curing treatment.