JPS6260212A - Manufacture of permanent magnet material - Google Patents

Abstract

PURPOSE:To contrive improvement in tight adhesiveness and corrosion-proof property of the titled permanent magnet material by a method wherein a grit blast is performed on the surface of a specific sintered permanent magnet body, the surface layer of the magnet body is removed, an Al thin film layer is coated, and then a shot peening is performed thereon. CONSTITUTION:On the surface of the sintered permanent magnet containing R (R indicates a kind of Nd, Pr, Dy, Ho and Tb, or a kind of La, Ce, Sm, Dc, Er, Eu, Tm, Yb, La and Y0 of 10-30atom%, B of 2-28atom%, and Fe of 65-80atom% as the main ingredients and having the main phase of tetragonal phase, indeterminate-formed hard powder consisting of a kind of the powder of 20-350mum is average grain diameter, having Mohs hardness of 5, if grit- blasted together with pressurized gas. After the surface layer of the magnet body is removed, an Al thin film layer is coated thereon, and then globular powder consisting of a kind of powder of Mohs hardness of 3 or more and having the average grain diameter of 30-3,000mum, is shot-peened together with pressurized gas, or a chromate treatment is performed on the surface of the sintered magnet body. As a result, the corrosion-proof property of the titled permanent magnet material can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application The present invention relates to a method for producing Fe-f3-R-based permanent magnet materials, and includes methods for removing black flakes remaining on at least one main surface of a sintered permanent magnet surface or grinding the magnet surface. The present invention relates to a method for manufacturing a Fe-BR permanent magnet material with excellent corrosion resistance, which prevents deterioration of magnetic properties due to processing, etc., and improves the adhesion of a corrosion-resistant coating on the magnet material.

BACKGROUND ART Current typical permanent magnet materials are alnico, hard ferrite and rare earth cobalt magnets.

This rare earth cobalt magnet has extremely excellent magnetic properties and is used for a variety of purposes, but the main component is S.
, Co are both in short supply and expensive, and it will be difficult to supply them in large quantities stably over a long period of time.

Therefore, there has been a strong desire for a permanent magnet material that has excellent magnetic properties, is inexpensive, and is composed of constituent elements that are abundant in resources and can be stably supplied in the future.

The present applicant previously proposed an Fa-BR-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 Sm (Japanese Patent Application Laid-Open No. 59-1991). -46008, JP-A-59-64733,
JP-A-59-89401, JP-A-59-132104
@).

This permanent magnet uses resource-rich light rare earth materials such as ceramics and circles as R, and has B and Fs as its main components25)
It is an excellent permanent magnet that exhibits an extremely high energy product of IGO8 or higher, reaching a maximum of 458GOe or higher.

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 it into magnetic circuits. , it is necessary to cut or grind the entire surface or the required surface of the magnet body, and the processing requires an outer peripheral blade cutting machine or an internal peripheral blade cutting machine.

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

However, when Fe-B-R permanent magnet material is cut or ground, the Fe-B-R permanent magnet material, as a main component, is extremely easily oxidized in the air and immediately produces stable oxides. Because it contains rare earth 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 Fe-B-R 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 the characteristics between the magnetic circuits. In addition, the problem of contamination of peripheral equipment due to shedding of surface oxides was a frequent problem.

Therefore, in order to improve the corrosion resistance of the above-mentioned Fa-B-R permanent magnet, the applicant first developed a permanent magnet (with a corrosion-resistant metal plating layer coated on the surface of the magnet body by electroless plating or electrolytic plating). Patent application No. 58-162350@) and proposed a permanent magnet in which the surface of the magnet body is coated with a corrosion-resistant resin layer by spraying or dipping method (Patent application No. 58-171907)
No.).

However, in the former plating method, since the permanent magnet body is a sintered body and is porous, acidic or alkaline solutions may remain in the pores during plating pretreatment, which may cause rust 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.

In addition, since resin coating using the latter spray method has a certain direction, it takes a lot of time and effort to apply a uniform resin coating to the entire surface of the object, and it is especially difficult to apply a uniform resin coating to irregularly 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 Fs-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. 110793/1983) in which an M thin film layer was deposited on the surface of the magnet body.

As a result, the corrosion resistance of Fa-B-R permanent magnets has increased significantly, but the above-mentioned AI thin film lacks density because it is formed by evaporated ρ particles deposited on the magnet surface during vapor deposition etc. When used for a long period of time, the A (1m film) may peel off locally or cracks may occur in the thin film layer, causing concerns about local rust formation.

Purpose of the Invention The present invention improves the deterioration of magnetic properties caused by cutting or grinding of sintered magnet bodies in a new permanent magnet material mainly composed of rare earth elements, boron, and iron, and also improves corrosion resistance. The object of the present invention is to provide a method for producing a permanent magnet material on which a corrosion-resistant thin film layer with excellent adhesion and corrosion resistance is deposited without using or contacting chemicals.

Structure and Effects of the Invention The present invention provides the following features:
TI, (A, Er, Eu, T[n.

consisting of at least one of Yb, La, 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.
Im~3502@, an amorphous hard powder consisting of at least one kind of powder with a Mohs hardness of 5 or more is heated to a pressure of i, oh4~
Grid blasting is performed for 0.5 to 60 minutes with 6.0 kg of pressurized gas of 4 to remove the surface layer of the magnet, and then a M thin film layer is deposited on the surface of the magnet to create a rough texture. The average particle size is 30. ~3000. A spherical powder made of at least one type of powder having a Mohs hardness of 3 or more is heated at a pressure of 1.0 kg to 4 to 5. With pressurized gas of Okg, 1
A method for producing a permanent magnet material, characterized in that the corrosion resistance of the sintered magnet is improved by subjecting the sintered magnet to shot peening for 60 minutes or, if necessary, to chromate treatment on the surface of the sintered magnet. It is.

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. After removing the magnet, a M thin film layer is applied to the surface of the cleaned magnet body to improve the deterioration of magnetic properties caused by oxidation and cutting, and a specific powder of the desired shape is injected together with pressurized gas. Then, the AI thin film layer was densified, the adhesion between the material and the surface thin film layer was improved, and the magnet body coated with the Al thin film layer was subjected to chromate treatment to form an Al thin film. A chromate coating is formed on the surface of the layer to further improve the corrosion resistance of the material.

Further, the permanent magnet material of this invention has an average crystal grain size of 1 to 8.
It is characterized by having a main phase of a compound having a tetragonal crystal structure in the range of 0 Hu, and containing a non-magnetic phase (excluding the oxide phase) in a volume ratio of 1% to 50%.

The manufacturing method of this invention uses resource-rich light rare earths such as ceramics and circles as R, and has an extremely high energy product of 258 GOe or more, reaching a maximum of 45 HGOe or more, with B and Fe as the main components. It is an excellent permanent magnet that exhibits high residual magnetic flux density and high coercive force. It also prevents deterioration of magnetic properties due to grinding and oxidation layers, and has a stable coating of M thin film or chromate film with excellent corrosion resistance on the surface. The deposited Fe-El-R permanent magnet material can be obtained at low cost.

In this invention, the amorphous hard powder with a Mohs hardness of 5 or more used for shot blasting includes M2O3 type, silicon carbide type, ZrO2 type, and boron carbide type.

Garnet-based powders are available, and N2O3-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 is 201 Jm to 350 Jm.
The reason for I is that if the grinding force is less than 201 Jm, the grinding force will be too small and it will take a long time to grind, and if it exceeds 35,077 m, the surface roughness of the sintered magnet surface will become too rough and the amount of grinding will be uneven. This is because it is not desirable.

In addition, as the injection conditions for the amorphous hard powder, the pressure is 1, OK
If the pressure is less than 4, the grinding process will take a long time and the pressure will be lower than 6.
．． If it exceeds 0 to 94, the amount of grinding on the surface of the magnet body will become non-uniform, and there is a concern that the surface roughness will 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 poles, glass beads, etc. can be used, and the attached Ag
The hardness may be equal to or higher than that of the a-film layer, and glass beads are preferred.

If the Mohs hardness of the peening spherical powder is less than 3, it is A(
This is not preferable because the hardness is lower than that of a 1 m film layer and no peening effect can be obtained.

In addition, the average particle size of the spherical powder for peening is 300,000 to 30,000
00 μm is because if it is less than 3011 m, the pressing force against the Ag thin film layer is small and it takes a long time to process.
This is because if it exceeds 000 left, the surface roughness of the sintered magnet surface becomes too rough, resulting in an uneven finished surface, which is not desirable. A more preferable average particle size is 40. 200 from zm
It is for 0A.

In addition, the injection conditions for the spherical powder are as follows: pressure 1. If the pressure is less than Or4, the pressing force against the All film layer will be small and the process will take a long time, and if the pressure is less than 5. If it exceeds os4, the pressing force on the Ag 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 upper limit of the spraying time is determined by the throughput of peening and the processing conditions, but if it exceeds 60 minutes, the surface roughness will deteriorate, which is not preferable.

In the present invention, in order to deposit the N layer on the clean surface of the sintered magnet 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. In addition, the thickness of the thin film layer is preferably 30 or less, most preferably 5 to 25, in consideration of peeling of the thin film layer, reduction in mechanical strength, and ensuring corrosion resistance. be.

In addition, the thickness of the chromate coating deposited on the A & thin film layer is:
1 item 10 Bm is preferable, and the appearance is preferably finished from bright iridescent to golden yellowish brown.

Reason 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 atomic % to 301'7% of the composition, and Nd.

At least one of Pr, Dy, Ho, and Tb,
Or Zara (Ko, La, Ce, Sm, Cd,
Er, Eu, 1m, Yb, La.

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.
It is possible to use a mixture of more than one species (such as Mitsumemetal, dididium, etc.) for reasons such as availability.

Note that this R does not need to be a pure rare earth element, and may be an industrial F-
It may contain impurities that are unavoidable during manufacturing to the extent that it is possible to do so manually.

First, it is an essential element for permanent magnet materials, and if it is less than 10 atomic %, the crystal structure becomes cubic, which is the same structure as α-iron, so it has high magnetic properties. 14 properties, especially high coercive force cannot be obtained, and when the content exceeds 30 at%, R-rich nonmagnetic phase increases, the residual magnetic flux density (Br) decreases, and permanent magnets with excellent characteristics cannot be obtained. .The rare earth element is in the range of 10 atomic % to 30 atomic %.

B is an essential element for the permanent magnet material according to the present invention, and if it is less than 2 atomic %, the rhombohedral groove structure becomes the main phase, and a high coercive force (iHC) cannot be obtained; If it exceeds B, the amount of B-rich non-magnetic phase increases and the residual magnetic flux density (Br) decreases, making it impossible to obtain an excellent permanent magnet.Therefore, B should be 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 from atomic % to 80 atomic %.

In addition, in the permanent magnet material according to the present invention, replacing a part of Fe with Co can improve the temperature characteristics without impairing the magnetic properties of the resulting magnet.
If the amount of O substitution exceeds 20% of Fe, the magnetic properties will deteriorate, which is not preferable. C.

The amount of substitution is 5 at% to 15 at% in total amount of e and CO.
In this case, since (Br) increases compared to the case without substitution, it is preferable to obtain a high magnetic flux density.

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

In addition to Fe, the presence of unavoidable impurities in industrial production can be tolerated, but a part of B can be replaced by 4.0 atom% or less of C13, 5 atom% or less of P, 2.5 atom% or less of S, 3゜5 atomic%
At least one of the following marrow, total amount 4.0 atomic%
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 can be added to Fa-based permanent magnets because it is effective in improving the coercive force and squareness of the demagnetization curve, improving manufacturability, and reducing costs.

A1.4 of 9.5 atom% or less, D119 of 5 atom% or less
．． VlB of 5 atomic % or less, Cr of 5 m atomic % or less.

Hn of 8.0 atom% or less, B119 of 5.0 atom% or less
．． Nb of 5 atomic % or less, Ta of 9.5 atomic % or less.

t(o) of 9.5 atom% or less, glue of 9.5 atom% or less, sb of 2.5 atom% or less, Ge of 7 atom% or less.

Sn of 3.5 atomic% or less, Zr of 5.5 atomic% or less
.

Ni of 9.0 atomic % or less, Si of 9.0 atomic % or less, 1
．． At least one of Zn of 1 atomic % or less and Hf of 5.5 atomic % or less is added. However, if two or more types are contained, the maximum content is the maximum value of the added elements. By containing atomic percent or less, it becomes possible to increase the coercive force of the permanent magnet.

It is essential that the main phase of the crystalline phase be a tetragonal one in order to produce a sintered permanent magnet having superior magnetic properties to that of 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
os, the residual magnetic flux density Br > 4 kG, and the maximum energy product (BH) max is (Btl) max ≧ 10
HGOs, and the maximum value reaches 25HGOe or more.

In addition, the main component of R of the permanent @stone according to this invention is the 5
In the case where 0% or more is occupied by light rare earth metals mainly composed of Nd and circles, R121i atoms % to 20 at%, B44 atoms to 2
When the main component is 4 at% Fe and 74 at% to 80 at% Fe, it exhibits excellent magnetic properties of (BH)max 35HGOe or more, and especially when the light rare earth metal is Nd, the maximum value is 45HGOe or more. ) reaches IGQθ or higher.

Examples 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 after blending these, they were high-frequency melted, and then cast in a water-cooled copper mold. ．．
ONd7. 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, with an average particle size of 2.8. q
A fine powder of m was obtained.

This fine powder was inserted into a mold, oriented in a magnetic field of 15 koe, and molded at a pressure of 1.214 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 having dimensions of 2 S mm in length, 40 mm in width, and 30 mm in thickness.

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

The above permanent 1'5 body is placed in the atmosphere with diamond 112
Using No. 00 as a grindstone, it was cut to a size of 5 m length + nx width 10 mm x thickness 3 mm at a rotation speed of 240 rpm and a feed rate of 5 mm/min.

Furthermore, amorphous Al2O3 hard powder with an average particle size of 50 and a Mohs hardness of 9 was used for this cut sample, and a pressure of 2.5
Third, grid blasting was performed for 20 minutes with pressurized N2 gas to remove the surface layer of the magnet.

Next, the above sample was placed in a vacuum container with a vacuum degree of 5X10-5 TOrr, Ar gas was introduced, and IX10-2
After discharging for 15 minutes at a voltage of 500 V in Ar gas under Torr, a N plate with a purity of 99.99% was used as a coating material, and this was heated to ionize the evaporated Al. The particles were attracted by the electric field and landed on the test piece constituting the cathode, forming an Al thin film. The thickness of the thin film formed on the surface of the test piece was 15 μm.

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

Furthermore, the average grain size of 1
A test piece was obtained by shot peening using a spherical russian bead powder with a diameter of 2077 m and a Mohs hardness of 6 under conditions of spraying for 5 minutes at a pressure of 1.5 kcJ4 with a pressurized N2 gas (Invention 1).

Further, after shot peening, the magnet sample was heated to 2% alodine #1200 (trade name,
A test piece was obtained by immersing it in a solution (manufactured by Nippon Paint Co., Ltd.) for 1 minute and depositing a golden yellow chromate coating on the surface of the M thin film layer after peening (Invention 2).

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, the as-cut test piece (Comparative Example 3) and the above test piece were subjected to solvent degreasing with trichlorene for 3 minutes, and alkaline degreasing with 5% Na0)l at 60°C for 3 minutes. , 2% HCR in a pickling Watts bath for 10 seconds at room temperature, current density aA/dm2. Bath temperature 60℃, 20
Electrolytic nickel plating is performed under conditions of 2 minutes on the surface.
0. Comparative test piece with qm thick nickel plating layer (
Comparative Example 4) was obtained. Furthermore, after depositing the above AJ thin film layer, a comparative test piece (not treated with shot peening) (
Comparative Example 5> was obtained.

These comparative test pieces were 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, 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 500 hours. In addition, the time required for rust to develop for Test Pieces 1 and 2 of the present invention was examined under the above conditions.

Further, the adhesion strength test was evaluated by breaking the test pieces of Invention 1.2 and Comparative Examples 4 and 5 after the corrosion resistance test and observing the fracture surfaces.

As is clear from Table 1 in the margin below, the method of this invention improves the deterioration of magnetic properties caused by cutting or grinding, and also provides a permanent magnet with excellent corrosion resistance, which shows that the effect is remarkable. .

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, La, 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. A permanent magnet material characterized in that the surface layer of the sintered magnet body is removed, an Al thin film layer is deposited on the surface of the magnet body, and shot peening is further performed to improve the corrosion resistance of the sintered magnet body. manufacturing method. 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, La, 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, an Al thin film layer is deposited on the surface of the magnet body, and after shot peening, the surface of the sintered magnet body is subjected to chromate treatment and sintered. A method for producing a permanent magnet material, characterized in that the corrosion resistance of a compacted magnet body is improved.