JP3519069B2 - Rare earth sintered magnet - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth-based sintered magnet capable of forming a corrosion resistant coating such as a plating coating with high film thickness dimensional accuracy.

[0002]

2. Description of the Related Art Rare-earth permanent magnets such as R-Fe-B permanent magnets represented by Nd-Fe-B permanent magnets are
Compared with the m-Co permanent magnet, a resource-rich and inexpensive material is used, and it has high magnetic characteristics. Therefore, in particular, R-Fe-B based permanent magnets are used in various fields today. However, the rare earth-based permanent magnet contains R, which is easily oxidized and corroded in the atmosphere. Therefore, when it is used without surface treatment, corrosion progresses from the surface due to the influence of slight acid, alkali and moisture, and rust occurs, which causes deterioration and dispersion of magnetic properties. It will be. Furthermore, when a magnet with rust is incorporated in a device such as a magnetic circuit, the rust may scatter to contaminate peripheral parts. In order to solve this problem, a method of forming a plating film as a corrosion resistant film on the surface of a rare earth sintered magnet by, for example, electroplating is put into practical use. In order to form a plating film having excellent corrosion resistance on the surface of the magnet, it is essential that the entire surface of the magnet has conductivity. Since the surface of the rare earth-based sintered magnet is basically conductive, it is possible to form a plating film on the surface without any measures, but a conductive layer is uniformly and firmly formed on the entire magnet surface. The method of forming is highly useful, and the advent of such a method is desired.

By the way, various methods have been proposed for imparting conductivity to the entire surface of the bonded magnet and performing electroplating. These methods are also applicable to sintered magnets. For example, in Japanese Patent Laid-Open No. 5-302176,
A resin containing conductive powder by placing a bond magnet, a resin in an uncured state at least partially, a conductive powder, and a film-forming medium such as a steel ball in a container and applying vibration or stirring to them. Form a coating on the magnet surface,
A method for forming a plating film on the surface is described. Japanese Unexamined Patent Publication (Kokai) No. 7-161516 discloses that an uncured resin layer is formed on the whole or a part of the surface of a bonded magnet, and then a conductive layer made of metal powder is formed on the surface using copper balls which are media of a vibrating ball mill. It describes a method of forming and further forming a plating film on the surface of the conductive layer.
Japanese Patent Laid-Open No. 11-3811 discloses that a bonded magnet is immersed in a solution of a coupling agent to which a metal powder is added, the metal powder is attached to the surface of the magnet, and then the impact force of a blast medium such as a stainless ball is applied. It describes a method of filling and coating a metal surface with a metal powder, and then forming a plating film on the surface. In addition, JP-A-8-1860
Japanese Unexamined Patent Publication No. 16 describes a method of forming a conductive coating layer by coating a mixture of resin and conductive material powder on the surface of a bonded magnet, and then performing a surface smoothing treatment to form a plating coating on the surface. ing.

The following methods have been proposed as a method for forming a corrosion resistant coating other than the plated coating on the surface of the bonded magnet. For example, in Japanese Patent Application Laid-Open No. 7-302705, after the surface of a bond magnet is coated with an uncured resin, the bonded magnet is placed in a container together with a metal powder and a coating forming medium such as an alumina ball, and the container is vibrated and / or vibrated. It describes a method of adhering metal powder to the surface of an uncured resin by stirring and forming a chromate film on the surface. Japanese Unexamined Patent Application Publication No. 10-226890 discloses a method in which a bond magnet is immersed in a solution of a coupling agent to which a metal powder is added, and then the metal powder is attached to the surface of the bonded magnet in advance by using a blast medium such as a stainless ball. A method of forming a resin film on the surface of a powder is described. Further, Japanese Patent Application Laid-Open No. 9-205013 describes a method in which a void is formed on the surface of a bonded magnet by filling a metal powder with an attacking force of a blast medium such as a steel ball and forming a resin film on the surface.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The method described in Japanese Patent No. 6 or the like basically uses metal powder to impart conductivity to the entire surface of the bonded magnet.
In addition, JP-A-7-302705 and JP-A-10-2
Also by the method described in Japanese Patent No. 26890, conductivity can be imparted to the entire surface of the bonded magnet. However, in any of the methods, the metal powder is attached to the surface of the magnet by utilizing the adhesiveness of the third component such as the resin and the coupling agent. In such a method, since the third component is required, the cost is increased and it is difficult to uniformly form the conductive layer on the entire magnet surface, resulting in high dimensional accuracy. Surface treatment becomes difficult. Moreover, since a curing process for the uncured resin is required, the manufacturing process becomes complicated. Furthermore, when a medium such as a steel ball, a copper ball, a stainless steel ball, or an alumina ball is used as a means for attaching the metal powder, the bonded magnet may be cracked or chipped. According to the method described in Japanese Patent Application Laid-Open No. 9-205013, it is possible to fill the voids on the surface of the magnet with the metal powder without using the third component such as the resin and the coupling agent. However, this method does not try to adhere the metal powder onto the magnetic powder that originally constitutes the magnet surface. Therefore, even if the metal powder adheres to the magnetic powder, the adhesive force is inevitably weak, so that the metal powder cannot firmly adhere to the magnetic powder. In addition, this method requires a step of removing excess metal powder that weakly adheres to the magnetic powder by washing, which complicates the manufacturing process. Therefore, the present invention forms a conductive layer uniformly and firmly on the entire magnet surface without using a third component such as a resin or a coupling agent.
An object of the present invention is to provide a rare earth-based sintered magnet capable of forming a corrosion resistant coating such as a plating coating with high film thickness dimensional accuracy.

[0006]

MEANS TO SOLVE THE PROBLEMS The inventors of the present invention have mechanochemical (mechchemical) which is a unique surface chemical reaction caused by a solid metal surface (fresh surface) which has not been oxidized.
As a result of various studies focusing on the (anochemical) reaction, as a result, the rare earth-based permanent magnet and the metal fine powder generating substance were put in the processing container, and both were vibrated in the processing container.
When and / or both are agitated, metal fine powder having a fresh surface is produced from the metal fine powder producing substance, and an adhered layer of the metal fine powder is strongly and densely formed on the metal constituting the magnet surface. I found out.

The present invention has been made on the basis of such findings, and the rare earth sintered magnet of the present invention has a size of 0.3 mm to 10 mm with the rare earth sintered magnet as described in claim 1.
Put the metal fine powder generating substance of into the processing container and put it in the processing container.
And vibrate both, and / or stir both
As a result, the major axis is 0.001μ from the fine metal powder generating substance.
The surface of the magnet is generated while producing metal powder of m-5 μm.
Depositing the fine metal powder generated on the metal forming the
It is characterized in that it has an adherend layer consisting essentially of fine metal powder on the metal constituting the magnet surface obtained in (1 ). The rare earth-based sintered magnet according to claim 2 is the rare earth-based sintered magnet according to claim 1, wherein the fine metal powder is Cu, Fe,
It is characterized by containing at least one metal component selected from Ni, Co and Cr. Further, the rare earth metal-based sintered magnet of claim 3, wherein, in the rare earth metal-based sintered magnet of claim 1, wherein Vickers hardness values of metal fines, characterized in that 60 or less. The rare earth-based sintered magnet according to claim 4 is the rare earth-based sintered magnet according to claim 1, wherein the fine metal powder is Sn, Zn, Pb, Cd, In, Au,
It is characterized by containing at least one metal component selected from Ag and Al. A rare earth-based sintered magnet according to a fifth aspect is the rare earth-based sintered magnet according to the first aspect, wherein the rare earth-based sintered magnet is an R—Fe—B based sintered magnet. Further, the rare earth-based sintered magnet according to claim 6 is the rare earth-based sintered magnet according to claim 2,
The film thickness of the deposition layer is 0.001 μm to 0.2 μm. Further, the rare earth metal-based sintered magnet of claim 7, wherein, in the rare earth metal-based sintered magnet of claim 3, wherein the thickness of the deposited layer is 0.001Myuemu～100myuemu. Further, the rare earth metal-based sintered magnet of the present invention, according to claim 8
As described above, the rare earth-based sintered magnet according to claim 1 is characterized in that it has a plating film on the surface of the adhered layer which is substantially composed of only metal fine powder. Further, the rare earth metal-based sintered magnet of the present invention have claim 9 as described, substantially metal oxide film on the surface of the adherend layer consisting only of fine metal powder of a rare earth-based sintered magnet of claim 1, wherein It is characterized by Further, the rare earth-based sintered magnet of the present invention has a chemical conversion treatment coating on the surface of the adherend layer of the rare earth-based sintered magnet according to claim 1, which is substantially composed of only fine metal powder, as described in claim 10. Is characterized by.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is intended for rare earth-based permanent magnets having various configurations such as a bonded magnet obtained by binding and molding magnetic powder with a required binder and a sintered magnet obtained by sintering magnetic powder. However, the present invention is directed to sintered magnets.

As a rare earth type sintered magnet, Nd-Fe-
R-Fe-B system sintered magnet represented by B system sintered magnet, S
Examples thereof include R-Fe-N-based sintered magnets represented by m-Fe-N-based sintered magnets. The magnetic powder, which is a raw material for the sintered magnet, can be obtained by, for example, the conventionally-dissolved pulverization method or the direct reduction diffusion method. In addition to such a method, in particular, a magnetic powder obtained by crushing an alloy thin plate having a columnar crystal structure grown in a plate thickness direction by a melt quenching method described in Japanese Patent No. 2665590 is used. As a result, a sintered magnet with high magnetic properties can be obtained. The composition of the magnetic powder used as the raw material of the sintered magnet can be selected from the range described below.
The sintered magnet can be easily obtained by adopting a known powder metallurgy method. The anisotropy can be imparted by magnetically orienting magnetic powder having magnetic anisotropy in a magnetic field. In these sintered magnets, the effect of the present invention does not differ depending on the composition of the magnetic powder as the raw material and the presence or absence of anisotropy, and the desired effect can be obtained.

The magnetic powder constituting the rare earth-based sintered magnet is a melting and pulverizing method in which a rare earth-based permanent magnet alloy is melted and crushed after casting, and a sintered body crushing method in which a sintered magnet is prepared and then crushed. , A direct reduction diffusion method for directly obtaining magnetic powder by Ca reduction, a ribbon jet of a rare earth permanent magnet alloy with a melting jet caster, a quenching alloy method for crushing and refining this, melting a rare earth permanent magnet alloy, This can be obtained by a method such as an atomizing method in which this is powdered by atomization and heat treatment, or a mechanical alloy method in which the raw material metal is powdered and then finely powdered by mechanical alloying and heat treated. The magnetic powder that constitutes the R—Fe—N-based sintered magnet is obtained by pulverizing a rare earth-based permanent magnet alloy, nitriding the same in nitrogen gas or ammonia gas, and then pulverizing the powder into a fine powder. You can also get by method. Below, R-Fe-B
An outline of each method will be described by taking the production of magnetic powder for a system sintered magnet as an example.

(Melting and pulverizing method) A manufacturing method in which raw materials are melted and mechanically pulverized after casting. For example, as a starting material, electrolytic iron, B is contained, and the balance is Fe and Al,
Ferroboron alloy made of impurities such as Si and C, rare earth metal, or raw material powder mixed with electrolytic Co is high-frequency melted, then cast in a water-cooled copper mold, hydrogen-absorbed and crushed, or a normal stamp mill or the like. Coarsely pulverize by mechanical pulverization. As the next fine pulverization process, dry pulverization such as a ball mill or jet mill and wet pulverization using various solvents can be adopted. According to this method, a fine powder having a tetragonal main phase and having an average particle size of 1 μm to 500 μm, which is substantially composed of single crystals or several crystal grains, can be obtained. Further, a finely pulverized powder having a required composition of 3 μm or less is subjected to orientation molding in a magnetic field, then crushed, and further 800 ° C.
A magnetic powder having a high coercive force can be obtained by crushing after heat treatment at 1100 ° C.

(Sintered body crushing method) This is a method in which the required R-Fe-B alloy is sintered and crushed again to obtain magnetic powder. For example, as a starting material, electrolytic iron, B is contained, and the balance is Fe.
And a ferroboron alloy consisting of impurities such as Al, Si and C, a rare earth metal, or a raw material powder further mixed with electrolytic Co is alloyed by high frequency melting in an inert gas atmosphere and coarsely crushed using a stamp mill or the like. ,further,
Finely pulverize with a ball mill. The obtained fine powder is pressure-molded under a magnetic field or without applying a magnetic field, sintered in a non-oxidizing atmosphere such as vacuum or inert gas, and pulverized again.
A fine powder having an average particle size of 0.3 μm to 100 μm is obtained. After that, in order to increase the coercive force, at 500 ° C to 1000 ° C,
You may heat-process.

(Direct Reduction Diffusion Method) A raw material alloy for which a raw material powder made of at least one metal powder and / or oxide powder made of ferroboron powder, ferronickel powder, cobalt powder, iron powder, rare earth oxide powder or the like is desired It is selected according to the composition of the powder, and the raw material powder is mixed with metal Ca or CaH ₂ by 1.1 times to 4.0 times (the weight ratio) the stoichiometric amount required for the reduction of the rare earth oxide powder. Then, by heating to 900 ° C. to 1200 ° C. in an inert gas atmosphere and adding the obtained reaction product to water to remove a reaction by-product, an average particle size of 10 μm to 200 μm that does not require coarse pulverization. To obtain a powder having The obtained powder may be further finely pulverized by dry pulverization using a ball mill, jet mill or the like. Further, finely pulverized powder having a required composition of 3 μm or less is subjected to orientation molding in a magnetic field, then crushed, and further 800 ° C. to 1100.
A magnetic powder having a high coercive force can be obtained by crushing after heat treatment at ℃.

(Quenched alloy method) The required R-Fe-B type alloy is melted and melt-spun with a jet caster to obtain 2
A ribbon foil having a thickness of about 0 μm is obtained, and the ribbon foil is crushed and then annealed and heat-treated to obtain a powder having fine crystal grains of 0.5 μm or less. Further, the powder having fine crystal grains obtained from the above ribbon foil may be hot-pressed and warm upset to obtain an anisotropic bulk magnet, which may be finely pulverized.

(Atomizing method) The required R-Fe-B type alloy is melted, the molten metal is dropped from a thin nozzle, atomized with a high-speed inert gas or liquid, and this is sieved or crushed, then dried or annealed. This is a method of obtaining magnetic powder by heat treatment. It is also possible to subject the powder having the above-mentioned fine crystal grains to hot pressing and warm upsetting to obtain an anisotropic bulk magnet, which is then finely pulverized.

(Mechanical alloy method) The required raw material powders are mixed at an atomic level in an inert gas by a ball mill, a vibration mill, a dry attritor, or the like to be made amorphous.
Then, it is a method of obtaining a magnetic powder by annealing heat treatment. It is also possible to subject the powder having the above-mentioned fine crystal grains to hot pressing and warm upsetting to obtain an anisotropic bulk magnet, which is then finely pulverized.

As a method of imparting magnetic anisotropy to bulk or magnetic powder, alloy powder obtained by a quenching alloy method is sintered at a low temperature by hot pressing or the like, and further warm upset processing is performed. Warm working and crushing method for crushing bulk magnets with magnetic anisotropy (Japanese Patent Publication 4-2
No. 0242), the alloy powder obtained by the quenching alloy method is directly filled and sealed in a metal container, and magnetic anisotropy is imparted by plastic working such as warm rolling (Patent No. 2596835). Hot-working and crushing method for hot-plasticizing an alloy ingot and then crushing it to obtain magnetic powder having magnetic anisotropy (Japanese Patent Publication No.
-66892), a rare earth-based permanent magnet alloy is heated in hydrogen to occlude hydrogen, dehydrogenated, and then cooled to obtain magnetic powder. HDDR method (Japanese Patent Publication No. 6-82575). (See) can be adopted. The magnetic anisotropy is not limited to the combination of the above-mentioned raw material alloy and the anisotropic means, but can be appropriately combined.

The composition of the magnetic powder obtained by the above method is, for example, R: 8 atom% to 30 atom% (where R is at least one rare earth element containing Y, preferably N).
Mainly light rare earths such as d and Pr, or Nd,
A mixture with Pr or the like), B: 2 atomic% to 28 atomic% (a part of B can be replaced by C), Fe:
65 atom% to 84 atom% (a part of Fe is 50% of Fe
The following Co, and Ni containing 8% or less of Fe are substituted).

In order to increase the coercive force and the corrosion resistance of the obtained sintered magnet, the raw material powder contains Cu: 3.5 atomic% or less, S: 2.5 atomic% or less, and Ti: 4.5 atomic%. Less than,
Si: 15 atomic% or less, V: 9.5 atomic% or less, Nb:
12.5 atomic% or less, Ta: 10.5 atomic% or less, C
r: 8.5 atom% or less, Mo: 9.5 atom% or less, W:
9.5 atom% or less, Mn: 3.5 atom% or less, Al:
9.5 atom% or less, Sb: 2.5 atom% or less, Ge: 7
Atomic% or less, Sn: 3.5 atomic% or less, Zr: 5.5 atomic% or less, Hf: 5.5 atomic% or less, Ca: 8.5 atomic% or less, Mg: 8.5 atomic% or less, Sr : 7 atom% or less, Ba: 7 atom% or less, Be: 7 atom% or less, Ga:
At least one of 10 atomic% or less can be added and contained.

In the present invention, the metal forming the magnet surface means a magnetic crystal phase or the like located on the surface of the sintered magnet. That is, as long as the metal constituting the magnet surface can firmly adhere the fine metal powder by the mechanochemical reaction, there is no particular limitation or restriction on the form or material, and the effect obtained is greatly different. not. Since the present invention is intended for all the metals that cause rusting due to oxidative corrosion on the magnet surface, the existence form and arrangement form of the metal forming the magnet surface differ depending on the method of manufacturing the magnet. However, as long as the fine metal powder can be firmly adhered by the mechanochemical reaction, it is not limited or restricted by the examples described later.

As the metal fine powder, Cu, Fe, Ni, C
Materials composed of metal components such as o and Cr, and having high malleability, for example, Sn, Zn, Pb, Cd, In, Au, A
Examples thereof include those having a Vickers hardness value of 60 or less, which are made of metal components such as g and Al. The Vickers hardness is one of the indices showing the hardness of the material, and the measurement test is performed by, for example, a Vickers hardness tester (JISB772
5) Vickers hardness test method (JISZ22
44).

The fine metal powder may be composed of the above-mentioned single metal component or an alloy containing two or more kinds of metal components. Further, it may be made of an alloy containing these metal components as main components and containing other metal components. When using such alloys,
It is desirable to select an appropriate combination of metal components depending on the required ductility. The fine metal powder may contain impurities that are unavoidable in industrial production.

In the present invention, a mechanochemical reaction, which is a unique surface chemical reaction caused by a fresh metal surface, is utilized to efficiently form a deposition layer made of fine metal powder on the metal constituting the surface of the rare earth-based sintered magnet. Well formed. The adhered layer formed by the mechanochemical reaction is firmly and densely formed on the metal forming the magnet surface, and therefore cannot be removed by rubbing the surface with a hand. Therefore, the adhered layer does not fall off during various handlings such as a cleaning step after the formation of the adhered layer until the electroplating treatment is completed. Therefore, a conductive layer can be uniformly and firmly formed on the entire magnet surface without using a third component such as a resin or a coupling agent, so that a plating film with high adhesion strength can be formed with high film thickness dimensional accuracy. be able to.

The adhered layer formed on the metal constituting the magnet surface is a metal fine powder which retains the shape immediately after being produced from the metal fine powder producing substance, or a metal fine powder deposited on the metal constituting the magnet surface. Is a metal fine powder that has been deformed (for example, spread) by collision with the contents in the processing container (most of which are metal fine powder-producing substances), a metal fine powder that has been deformed after being deposited on the metal fine powder, or an aggregate of metal fine powder , A deformed body of the aggregate (for example, a scale-like product that has been spread), a laminated body of the aggregate, and the like. Therefore, the adhered layer made of the fine metal powder in the present invention means the adhered layer formed by using the fine metal powder generated from the fine metal powder-forming substance as a formation source.

Since the mechanochemical reaction is a reaction caused by a fresh metal surface as described above, how to produce a fresh metal surface is important. In the present invention, this object can be achieved by placing the rare earth-based sintered magnet and the fine metal powder generating substance in the processing container, and applying vibration to both and / or stirring both in the processing container. it can. As the mechanism, by vibrating and / or stirring the rare earth-based sintered magnet and the metal fine powder generating substance, first, the metal fine powder is generated from the metal fine powder generating substance. It can be mentioned that the metal fine powder immediately after the generation is not oxidized and has a fresh surface. Furthermore, the above-mentioned operation causes a fresh surface to be produced by the collision with the contents in the processing container, even for the metal that constitutes the magnet surface and the fine metal powder that is deposited on the metal that constitutes the magnet surface. Is mentioned. As a result, it is considered to be very convenient for continuously causing mechanochemical reactions.

Incidentally, in the study by the present inventors, even if a commercially available metal fine powder is put in the container instead of the metal fine powder generating substance and the same operation is performed, the metal fine powder is coated on the metal constituting the magnet surface. It has been found that it cannot be dressed. This is because the commercially available metal fine powder is usually oxidized on its surface and does not have a fresh surface and has no sharp edges. Collision, it is not possible to efficiently produce a fresh surface for the metal that constitutes the magnet surface, and the fine metal particles themselves also produce a fresh surface due to collisions with each other or with the metal that constitutes the magnet surface. It is thought that it is because there is no.

As the metal fine powder producing substance which is a production source of the metal fine powder having a fresh surface, a metal piece consisting of only a desired metal, a composite metal piece obtained by coating a core material made of a different metal with the desired metal, and the like are used. . These metal pieces have various shapes such as needle-like (wire-like), columnar, and lump-like shapes. However, in order to efficiently produce fine metal powder, a fresh surface is efficiently produced against the metal that constitutes the magnet surface. From the viewpoint of, for example, it is desirable to use a needle-shaped or columnar one having a sharp end. Such a desired shape can be easily obtained by adopting a known wire cutting technique.

The size (major axis) of the metal fine powder generating material is gold.
Efficiently generate fine metal powder and configure the magnet surface
Such as effectively creating a fresh surface for metal
From a perspective,0.3 mm to 10 mm.Preferably
0.3 mm to 5 mm,More desirably0.5 mm
~ 3 mm. The same fine metal powder generation material has the same shape
Sizes may be used, and different shapes and sizes may be mixed.
You may use together.

As described above, it is not possible to deposit the metal fine powder on the metal constituting the magnet surface with only the commercially available metal fine powder, but the commercially available metal fine powder is treated with the above-mentioned metal fine powder producing substance. When placed in a container, a fresh surface can be generated in the metal fine powder due to collision with the metal fine powder generating substance and the like, so that the metal fine powder is also expected to contribute to the formation of the adhered layer.

The treatment vessel usable in the present invention is particularly limited as long as it can vibrate the rare earth-based sintered magnet and the metal fine powder generating substance and / or agitate both in the treatment vessel. It is not limited. Specific processing containers include, for example, a processing tank of a barrel device used to process the surface of the object to be processed, a processing tank of a ball mill device used to crush the object to be processed, and the like. As the barrel device, known devices such as a rotary type, a vibration type, and a centrifugal type can be used. In the case of the rotary type, it is desirable that the number of rotations is 20 rpm to 50 rpm. In case of vibration type, the frequency is 50H
It is desirable to set z to 100 Hz and the vibration amplitude to 0.3 mm to 10 mm. In case of centrifugal type, the rotation speed is 70r
It is desirable to set it to pm to 200 rpm.

Vibration and / or agitation of the rare earth-based sintered magnet and the fine metal powder generating material are preferably performed dry in consideration of the fact that both are easily oxidized and corroded. The amount of the rare earth-based sintered magnet and the fine metal powder generating substance to be charged into the processing container is 20 vol% to 90 vol of the internal volume of the processing container.
% Is desirable. If it is less than 20 vol%, the treatment amount is too small to be practical, and if it exceeds 90 vol%, the fine metal powder may not be efficiently deposited on the magnet. Further, the ratio of the rare earth-based sintered magnet and the metal fine powder generating substance to be put into the container is preferably 3 or less in terms of volume ratio (magnet / metal fine powder generating substance). If the volume ratio exceeds 3, not only is it impractical to deposit the fine metal powder on a time-consuming basis, but collisions between magnets frequently occur, resulting in magnet cracking and magnetic powder shedding from the magnet surface. This is because it may cause it. The treatment time is generally about 1 hour to 10 hours, although it depends on the treatment amount.

The size and shape of the metal fine powder produced from the metal fine powder producing substance vary, but in general, ultrafine powder (fine powder having a major axis of 0.001 μm to 0.1 μm) seems to be suitable for causing mechanochemical reaction. Is. Cu, F
Fine powder composed of metal components such as e, Ni, Co, Cr,
On the metal that constitutes the magnet surface, the film thickness is 0.001 μm
A strong and dense adherend layer of 0.2 μm is formed.
Highly malleable, such as Sn, Zn, Pb, Cd, I
Fine powder having a Vickers hardness value of 60 or less, which is composed of a metal component such as n, Au, Ag, and Al, forms a strong and high-density adhered layer by stacking the aggregates. Therefore, if the processing time is extended, it is possible to form an adherend layer having a film thickness of about 100 μm. However, in order to impart sufficient conductivity to the magnet surface and meet the demand for miniaturization of the magnet, the thickness of the adherend layer is 0.001 μm to 1 μm.
μm is desirable.

A known electroplating treatment or the like can be performed on the rare earth-based sintered magnet in which conductivity is imparted to the entire surface of the magnet in this manner. Moreover, since it is not necessary to form a conductive layer containing a third component such as a resin or a coupling agent, it is possible to form a plating film on the magnet surface with high film thickness dimensional accuracy. Therefore, by adopting the configuration of the present invention, it is possible to improve the magnet dimensional accuracy after forming the plating film.

When the ring-shaped sintered magnet having the plating film thus obtained is used in a motor, the magnetic characteristics of the magnet itself can be utilized to the maximum extent, and the energy efficiency can be improved. It is also possible to reduce the size of the motor. It should be noted that it is possible to form a plating film on the surface of any adhered layer made of metal fine powder, but in terms of easiness and cost of the electric Ni plating treatment, Cu fine powder is used. The deposited layer formed is desirable.

Further, since the adhered layer made of fine metal powder formed by the mechanochemical reaction is firmly and densely formed on the metal constituting the magnet surface, the adhered layer itself rusts the magnet. Has the effect of preventing. Of course, in order to impart high corrosion resistance, it is necessary to perform electroplating treatment or the like. However, for magnets such as resin-embedded motor magnets whose corrosion resistance is required until the completion of the manufacturing of parts, the adhered layer itself made of fine metal powder is used to prevent the magnets from rusting. It has sufficient industrial value due to its effect as a layer. The adhered layer made of Al fine powder forms an oxide film on the surface thereof and has an excellent rust preventive action. Therefore, the Al fine powder is desirable from the viewpoint of simple rust prevention as described above.

As a typical electroplating method for forming a plating film on the magnet surface, for example, Ni, C
u, Sn, Co, Zn, Cr, Ag, Au, Pb, Pt
A plating method using at least one metal or an alloy of metals (which may contain B, S, and P) selected from the above, and the like can be given. It is also possible to adopt a plating method using an alloy containing the above metal in addition to the above metal depending on the application. Plating thickness is 50 μm or less,
It is preferably 10 μm to 30 μm.

When performing the electric Ni plating treatment, it is desirable to perform the washing, electrolytic Ni plating, washing and drying steps. As the plating bath, various baths can be used depending on the shape of the magnet. For example, in the case of a ring-shaped sintered magnet, it is desirable to use a catch plating bath or a barrel plating bath. As the plating bath, a known plating bath such as a Watt bath, a sulfamic acid bath, or a wood bath may be used. An electrolytic Ni plate is used as the anode, but in order to stabilize the elution of Ni, it is desirable to use an estrand nickel chip containing S as the electrolytic Ni plate.

When performing the electric Cu plating treatment, it is desirable to perform the washing, electrolytic Cu plating, washing and drying steps. As the plating bath, various baths can be used depending on the shape of the magnet. For example, in the case of a ring-shaped sintered magnet, it is desirable to use a catch plating bath or a barrel plating bath. As the plating bath, a known plating bath such as a copper sulfate bath or a pyrophosphoric acid shell bath may be used.

When the electroplating treatment is performed on the adhered layer made of fine Al powder, Al during the electroplating treatment is applied.
It is desirable to carry out a zinc substitution treatment in order to prevent the dissolution and outflow of The zinc replacement treatment may be carried out according to a known method, for example, using a zinc replacement solution containing sodium hydroxide, zinc oxide, ferric chloride, Rochelle salt, sodium nitrate, at a bath temperature of 10 ° C to 25 ° C. Then, it may be immersed for 10 seconds to 120 seconds.

In addition to the plating film, various corrosion resistant films such as a metal oxide film and a chemical conversion film can be formed on the adhered layer made of fine metal powder. Since the adhered layer is uniformly and strongly formed on the entire surface of the magnet, it is possible to form a film with high film thickness dimensional accuracy.

As a method for forming a metal oxide film,
Known methods such as a CVD method, a sputtering method, a coating thermal decomposition method, and a sol-gel film forming method can be used. But,
Use a sol-gel film formation method in which a sol solution obtained by a hydrolysis reaction or a polymerization reaction of a metal compound that is a constituent source of a metal oxide film is applied to the surface of a magnet and then heat-treated to form a film. Is desirable. The sol liquid used in the sol-gel film forming method is relatively stable, and since the film can be formed at a relatively low temperature, there are advantages such as avoiding the influence of the high temperature on the magnetic characteristics of the magnet itself. The metal oxide coating may be a coating made of a single metal oxide component or a composite coating made of a plurality of metal oxide components. The metal oxide film has a thickness of 0.01μ
If it is m or more, excellent corrosion resistance is exhibited. Although the upper limit of the film thickness is not particularly limited, a film thickness of 10 μm or less, preferably 5 μm or less is a practically suitable film in view of a request based on miniaturization of the magnet itself. When a metal oxide coating containing the same metal component as the metal component forming the deposition layer is formed on the deposition layer (for example, formation of a metal oxide coating containing Al on the deposition layer made of Al fine powder). ), It is convenient in that the adhesion at the interface between the two becomes stronger.

The sol solution contains a metal compound such as a metal alkoxide (which may be substituted with an alkyl group for a part of the alkoxyl group), a catalyst such as nitric acid or hydrochloric acid, and a β-diketone if desired. A solution in which a stabilizer, water and the like are adjusted in an organic solvent and a colloid obtained by a hydrolysis reaction or a polymerization reaction of a metal compound is dispersed is used.
Inorganic fine particles may be dispersed in the sol liquid. Examples of the method of applying the sol solution include a dip coating method, a spray method, a spin coating method and the like. The heat treatment after coating the sol solution is preferably performed at 80 ° C to 200 ° C in consideration of the boiling point of the organic solvent in the sol solution and the heat resistance of the magnet. The heat treatment time is usually 1 minute to 1
It's time. In order to obtain a film having a desired film thickness,
It goes without saying that the coating and the heat treatment may be repeated.

As the method for forming the chemical conversion coating, chromate treatment, phosphoric acid treatment, zinc phosphate treatment, manganese phosphate treatment, calcium phosphate treatment, zinc phosphate calcium treatment, titanium-phosphate chemical conversion treatment, zirconium-
A known method such as phosphoric acid-based chemical conversion treatment can be used. In order to improve the corrosion resistance of the adhered layer made of Al fine powder, chromate treatment, titanium-phosphoric acid chemical conversion treatment, zirconium-phosphoric acid chemical conversion treatment, etc. are desirable, and above all, the load on the environment of the treatment liquid and the coating film is increased. Smaller titanium-phosphoric acid type chemical conversion treatment and zirconium-phosphoric acid type chemical conversion treatment are preferable.

The treatment liquid for the titanium-phosphoric acid chemical conversion treatment is a titanium compound such as fluorotitanic acid, phosphoric acid or condensed phosphoric acid, or a fluorine compound such as fluorotitanic acid or hydrofluoric acid described above. Dissolve in and adjust. Examples of the method of applying the treatment liquid on the surface of the magnet include a dip coating method, a spray method and a spin coating method. The temperature of the treatment liquid when applying the treatment liquid is 20 ° C. to 80 ° C.
It is desirable that the temperature and the treatment time be 10 seconds to 10 minutes. The drying temperature after applying the treatment liquid is 50 ° C to 200 ° C, and the drying time is 5 seconds to
It's an hour. When the zirconium-phosphoric acid type chemical conversion treatment is performed, the method of the titanium-phosphoric acid type chemical conversion treatment may be applied. In the formed film, titanium or zirconium is contained in an amount of 0.1 mg to 1 per film formed on 1 m ^{2 of the} magnet surface.
It is desirable that the content is 00 mg.

[0045]

EXAMPLES The details of the present invention will be described below based on specific examples. In the following examples, the electron beam microanalyzer (EPMA) (EPM-810: manufactured by Shimadzu Corporation) was used to measure the film thickness of the adhered layer made of fine metal powder.
Was used. A fluorescent X-ray film thickness meter (SFT-7100: manufactured by Seiko Instruments Inc.) was used to measure the film thickness of the plating film. A fluorescent X-ray intensity measuring device (RIX-3000: manufactured by Rigaku Denki Co., Ltd.) was used to measure the metal content in the chemical conversion coating.

Example 1 (Step A) For example, as described in US Pat. No. 4,770,723, a known casting ingot is crushed, and after fine pulverization, molding, sintering, heat treatment, and surface processing are performed. Thus, a sintered magnet having a composition of 17Nd-1Pr-75Fe-7B and having a size of 23 mm length × 10 mm width × 6 mm height was produced. When this magnet was left under the conditions of 80 ° C. and relative humidity of 90%, spot rust occurred in 6 hours (according to a microscope observation of the surface condition of 30 times).

(Step B) 30 magnets obtained in step A (apparent volume 0.1 l, weight 320 g) and apparent volume 2
1 column of 0.8 mm diameter and 1 mm length of a short columnar Al fine powder producing substance (wire is cut) is charged into a treatment tank of a vibrating barrel device having a volume of 3.5 liter (total amount of treatment is the volume of the treatment tank). 60 vol%), a frequency of 60 Hz, and a vibration amplitude of 1.5 mm were dry-processed for 5 hours. The Al fine powder generated by this operation was the largest from the ultrafine powder having a major axis of 0.1 μm or less, and the major axis was about 5 μm. With respect to the magnet obtained by the above treatment, AlKα ray intensity measurement was performed using a standard sample, and it was found that a coating layer made of Al fine powder having a film thickness of 0.6 μm was formed on the surface of the magnet. . Al on the entire surface of this magnet
Even if a magnet having an adhered layer made of fine powder was left under the conditions of 80 ° C. and 90% relative humidity, rust did not occur up to 24 hours (according to a microscope observation of the surface condition of 30 times). ).

Reference Example 1: (Step A) Nd of 12 atomic% and F produced by a quenching alloy method
2w of an epoxy resin is added to an alloy powder having an average particle size of 150 μm, which is composed of 77 atomic% B, 6 atomic% B, and 5 atomic% Co.
After t% was added and kneaded, and compression molding was performed at a pressure of 686 N / mm ² , curing was performed at 170 ° C. for 1 hour, and a ring-shaped bonded magnet having an outer diameter of 22 mm × an inner diameter of 20 mm × height of 3 mm was produced. Table 1 shows the characteristics of the obtained ring-shaped bonded magnet (raw material).

(Step B) 50 magnets obtained in step A (apparent volume 0.15 l, weight 71 g) and diameter 1 mm,
A short columnar Cu fine powder generating substance (having a wire cut) of 10 mm (apparent volume 2 liters) having a length of 1 mm has a volume of 3.
The mixture was charged into a treatment tank of a 5 l vibrating barrel device (the total amount of the mixture was 61 vol% of the inner volume of the treatment tank), and the treatment was performed dry for 3 hours under conditions of a frequency of 70 Hz and a vibration amplitude of 3 mm. The Cu fine powder generated by this operation was the largest from the ultrafine powder having a major axis of 0.1 μm or less, and the major axis was about 5 μm. With respect to the magnet obtained by the above treatment, CuKα ray intensity measurement was performed using a standard sample. As a result, an adhered layer made of Cu fine powder having a film thickness of 0.1 μm was formed on the magnetic powder on the surface of the magnet. I understood it. Further, it was found that the resin portion on the surface of the magnet was covered with the adhered layer made of Cu fine powder.

Reference Example 2: The magnet obtained in Reference Example 1 was washed with a magnet having an adhered layer of fine Cu powder on the entire surface of the magnet, and then electro-Ni plating was performed by a hook plating method. The treatment is performed with a current density of 2 A / dm ² and a plating time of 60.
Min, pH 4.2, bath temperature 55 ° C., plating solution composition (nickel sulfate 240 g / l, nickel chloride 45 g / l, nickel carbonate proper amount (pH adjustment), boric acid 30 g / l). The plating film obtained had an outer diameter side film thickness of 22μ.
m, and the film thickness on the inner diameter side was 20 μm. About the magnet having this plating film, 80 ° C, relative humidity 90%, 500
An environmental test (humidity resistance test) was performed under the conditions of time, and the surface condition was observed (30 times microscope observation) and the magnetic property deterioration rate was measured after the humidity resistance test. Further, the dimensional accuracy of the film thickness on the inner diameter side was measured (n = 50). The results are shown in Tables 2 and 3.
As is clear from Tables 2 and 3, the magnet having this plating film had excellent corrosion resistance and was formed with high film thickness dimensional accuracy. This result shows that the short columnar Cu fine powder generating substance used in Reference Example 1 has a sharp end, so that Cu fine powder having a fresh surface was efficiently generated by collision with the contents in the processing container, Efficiently causing mechanochemical reaction because a fresh surface was efficiently generated even with respect to the magnetic powder on the magnet surface, and a strong and high-density adhered layer of Cu fine powder could be formed. It seems to be due to that. Also, since the resin portion on the magnet surface could be covered with the adhered layer made of Cu fine powder, it is considered that the conductive layer could be uniformly and strongly formed on the entire magnet surface.

Reference Example 3: (Step A) Nd of 13 atomic% and F produced by a quenching alloy method
2w of an epoxy resin is added to an alloy powder having an average particle size of 150 μm and having a composition of 76 atomic% B, 6 atomic% B, and 5 atomic% Co.
After t% was added and kneaded, and compression molding was performed at a pressure of 686 N / mm ² , curing was performed at 180 ° C. for 2 hours to prepare a ring-shaped bonded magnet having an outer diameter of 21 mm × an inner diameter of 18 mm × height of 4 mm. Table 1 shows the characteristics of the obtained ring-shaped bonded magnet (raw material).

(Step B) 50 magnets (apparent volume 0.15 l, weight 132 g) obtained in step A and a short columnar Fe fine powder generating substance (apparent volume 2 l, diameter 1 mm, length 0.8 mm, wire) Cut volume) 3.0l
Was charged into the processing tank of the vibrating barrel device (total volume of 72 vol% of the inner volume of the processing tank), and the dry treatment was performed for 2 hours under the conditions of a frequency of 60 Hz and a vibration amplitude of 2 mm. The fine Fe powder generated by this operation was the largest and had a major axis of about 5 μm. With respect to the magnet obtained by the above treatment, the FeKα ray intensity was measured using a standard sample.
e It was found that the adhered layer made of fine powder was formed. Further, it was found that the resin portion on the magnet surface was covered with the adhered layer made of Fe fine powder.

Reference Example 4: The magnet obtained in Reference Example 3 having the adhered layer made of Fe fine powder on the entire surface of the magnet was washed and then electro-Ni-plated by the hook plating method. The treatment is carried out at a current density of 2.2 A / dm ² , a plating time of 60 minutes, a pH of 4.2, a bath temperature of 50 ° C., a plating solution composition (nickel sulfate 240 g / l, nickel chloride 45 g / l, nickel carbonate suitable amount (pH adjustment)). , Boric acid 30 g / l). The plating film thus obtained had an outer diameter side film thickness of 21.
μm, and the film thickness on the inner diameter side was 18 μm. With respect to the magnet having this plating film, the surface condition after the moisture resistance test, the magnetic property deterioration rate measurement, and the dimensional accuracy measurement of the inner diameter side film thickness were performed in the same manner as in Reference Example 2. As a result, as is clear from Tables 2 and 3, the magnet having this plating film had excellent corrosion resistance and was formed with high film thickness dimensional accuracy.

Reference Example 5: Ring-shaped bonded magnet manufactured by the same method as in Step A of Reference Example 3 (characteristics are shown in Table 1).
Was used in the same manner as in Step B of Reference Example 3 except that the short columnar Fe fine powder producing substance in Step B was replaced with a short columnar Ni fine powder producing substance of the same size. The fine Ni powder generated by this operation is the largest and has a major axis of 5 μm.
It was about. When the NiKα ray intensity of the magnet obtained by the above treatment was measured using a standard sample, an adhered layer made of Ni fine powder having a film thickness of 0.1 μm was formed on the magnetic powder on the surface of the magnet. I understood it. Further, it was found that the resin portion on the magnet surface was covered with the adhered layer made of Ni fine powder.

Reference Example 6: The magnet obtained in Reference Example 5 having an adhered layer of Ni fine powder on the entire surface of the magnet was subjected to electric Ni plating under the same conditions as in Reference Example 4. The obtained plated coating had an outer diameter side film thickness of 21 μm and an inner diameter side film thickness of 18 μm. With respect to the magnet having this plating film, the surface condition after the moisture resistance test, the magnetic property deterioration rate measurement, and the dimensional accuracy measurement of the inner diameter side film thickness were performed in the same manner as in Reference Example 2. As a result, as is clear from Tables 2 and 3, the magnet having this plating film had excellent corrosion resistance and was formed with high film thickness dimensional accuracy.

Reference Example 7: Ring-shaped bonded magnet manufactured by the same method as in Step A of Reference Example 3 (characteristics are shown in Table 1).
Was used, and the short columnar Fe fine powder producing substance in step B was replaced with a short columnar Co fine powder producing substance of the same size, and the treatment was performed in the same manner as in step B of Reference Example 3. The fine Co powder produced by this operation is the largest and has a major axis of 5 μm.
It was about. When the CoKα ray intensity of the magnet obtained by the above treatment was measured using a standard sample, an adhered layer of Co fine powder having a film thickness of 0.1 μm was formed on the magnetic powder on the surface of the magnet. I understood it. Further, it was found that the resin portion on the surface of the magnet was covered with the adhered layer made of Co fine powder.

Reference Example 8: The magnet obtained in Reference Example 7 having the adhered layer of Co fine powder on the entire surface of the magnet was subjected to electric Ni plating under the same conditions as in Reference Example 4. The obtained plated coating had an outer diameter side film thickness of 21 μm and an inner diameter side film thickness of 18 μm. With respect to the magnet having this plating film, the surface condition after the moisture resistance test, the magnetic property deterioration rate measurement, and the dimensional accuracy measurement of the inner diameter side film thickness were performed in the same manner as in Reference Example 2. As a result, as is clear from Tables 2 and 3, the magnet having this plating film had excellent corrosion resistance and was formed with high film thickness dimensional accuracy.

Reference Example 9: Ring-shaped bonded magnet manufactured by the same method as in Step A of Reference Example 3 (characteristics are shown in Table 1).
Was used, and the short columnar Fe fine powder producing substance in step B was replaced with a short columnar Cr fine powder producing substance of the same size, and the treatment was performed in the same manner as in step B of Reference Example 3. The finest Cr powder produced by this operation has the longest diameter of 5 μm.
It was about. The magnet obtained by the above treatment was subjected to CrKα ray intensity measurement using a standard sample. As a result, an adhered layer made of Cr fine powder having a film thickness of 0.1 μm was formed on the magnetic powder on the surface of the magnet. I understood it. Further, it was found that the resin portion on the surface of the magnet was covered with the adhered layer made of Cr fine powder.

Reference Example 10: The magnet obtained in Reference Example 9 having an adhered layer of Cr fine powder on the entire surface of the magnet was subjected to electric Ni plating under the same conditions as in Reference Example 4.
The obtained plated coating had an outer diameter side film thickness of 21 μm and an inner diameter side film thickness of 18 μm. With respect to the magnet having this plating film, the surface condition after the moisture resistance test, the magnetic property deterioration rate measurement, and the dimensional accuracy measurement of the inner diameter side film thickness were performed in the same manner as in Reference Example 2. As a result, as is clear from Tables 2 and 3, the magnet having this plating film had excellent corrosion resistance and was formed with high film thickness dimensional accuracy.

Comparative Example 1: (Step A) A ring-shaped bonded magnet having an outer diameter of 22 mm, an inner diameter of 20 mm, and a height of 3 mm, which was produced by the same method as in the step A of Reference Example 1, was washed and then subjected to an immersion method. After forming a cured phenolic resin layer on the magnet, a commercially available Ag powder (major axis 0.7
μm or less) was attached to the resin surface. The obtained 50 ring-shaped bonded magnets (apparent volume 0.15 l, weight 71
g) was charged into a treatment tank of a vibrating barrel device having a volume of 3.5 l, and a steel ball having a diameter of 2.5 mm (apparent volume of 2 l)
Was used as a medium for 3 hours (the total amount charged was 61 vol% of the inner volume of the processing tank), and then cured at 150 ° C. for 2 hours to form a conductive coating layer of 7 μm on the magnet surface.

(Step B) For the magnet obtained in Step A,
The electric Ni plating treatment was performed under the same conditions as in Reference Example 2. With respect to the magnet having this plating film, the surface condition was observed after the moisture resistance test and the dimensional accuracy of the inner diameter side film thickness was measured in the same manner as in Reference Example 2. As a result, as is apparent from Table 2, the magnet having this plating film was rusted by the moisture resistance test, and the film thickness dimensional accuracy was low.

Comparative Example 2: (Step A) A ring-shaped bonded magnet having an outer diameter of 22 mm, an inner diameter of 20 mm and a height of 3 mm, which was produced by the same method as in the step A of Reference Example 1, was washed, and then 10 wt of epoxy adhesive was used. % Methyl ethyl ketone (MEK) solution was impregnated for 5 minutes, then drained well and dried MEK. 50 ring-shaped bond magnets (apparent volume of 0.
15 l, weight 71 g) and a Cu ball 10 k with a diameter of 1 mm
g (apparent volume 2 l) and 25 g of commercially available Cu powder having a major axis of 0.8 μm were charged into a treatment tank of a vibrating barrel device having a volume of 3.5 l (total amount added was 61 vol% of the inner volume of the treatment tank), 3
Time processed. After that, it was cured at 150 ° C. for 2 hours and then washed to remove excess Cu powder, and the magnet powder was placed on the magnet surface for 18 hours.
A μm conductive coating layer was formed.

(Step B) For the magnet obtained in Step A,
The electric Ni plating treatment was performed under the same conditions as in Reference Example 2. With respect to the magnet having this plating film, the surface condition was observed after the moisture resistance test and the dimensional accuracy of the inner diameter side film thickness was measured in the same manner as in Reference Example 2. As a result, as is apparent from Table 2, the magnet having this plating film was rusted by the moisture resistance test, and the film thickness dimensional accuracy was low.

[0064]

[Table 1]

[0065]

[Table 2]

[0066]

[Table 3]

Reference Example 11: (Step A) Nd of 13 atomic%, F prepared by a quenching alloy method
2w of an epoxy resin is added to an alloy powder having an average particle size of 150 μm and having a composition of 76 atomic% B, 6 atomic% B, and 5 atomic% Co.
After t% was added and kneaded, and compression molding was performed at a pressure of 686 N / mm ² , the mixture was cured at 180 ° C. for 2 hours to prepare a ring-shaped bonded magnet having an outer diameter of 25 mm × an inner diameter of 23 mm × height of 3 mm. Table 4 shows the properties of the obtained ring-shaped bonded magnet (raw material).

(Step B) 50 magnets obtained in step A (apparent volume 0.15 l, weight 83 g) and apparent volume 2
1 μm in diameter of 2 mm and 1 mm in length of a short cylindrical Sn fine powder producing substance (wire is cut) is charged into a processing tank of a vibrating barrel device having a volume of 3.0 l (total charging amount is 72 vol% of the processing tank inner volume). ), Frequency 60Hz, vibration amplitude 2mm
The treatment was performed under dry conditions for 2 hours. The Sn fine powder generated by this operation was the largest from the ultrafine powder having a major axis of 0.1 μm or less, and the major axis was about 5 μm. When the SnKα ray intensity of the magnet obtained by the above treatment was measured using a standard sample, a coating layer made of Sn fine powder having a film thickness of 0.5 μm was formed on the magnetic powder on the surface of the magnet. I understood it. Further, it was found that the resin portion on the magnet surface was covered with the adhered layer made of Sn fine powder.

Reference Example 12: After cleaning the magnet having an adhered layer of Sn fine powder on the entire surface of the magnet obtained in Reference Example 11, an electric Cu plating treatment was carried out by a hook plating method. The treatment is performed with a current density of 2.3 A / dm ² , a plating time of 6 minutes, a pH of 10.5, a bath temperature of 45 ° C., a plating solution composition (copper 2
The conditions were 0 g / l and 10 g / l of free cyan.
Subsequently, an electric Ni plating process was performed by a hook plating method. The treatment is carried out at a current density of 2.2 A / dm ² , a plating time of 60 minutes, a pH of 4.2, a bath temperature of 50 ° C., a plating solution composition (nickel sulfate 240 g / l, nickel chloride 45 g / l, nickel carbonate suitable amount (pH adjustment)). , Boric acid 30 g / l). The plating film obtained has a film thickness on the outer diameter side of 2
The thickness was 4 μm and the film thickness on the inner diameter side was 22 μm. With respect to the magnet having this plating film, the surface condition after the moisture resistance test, the magnetic property deterioration rate measurement, and the dimensional accuracy measurement of the inner diameter side film thickness were performed in the same manner as in Reference Example 2. As a result, Table 5 and Table 6
As is clear from the above, the magnet having this plating film is
The film was excellent in corrosion resistance and was formed with high film thickness dimensional accuracy.

Reference Example 13: Using a ring-shaped bonded magnet (characteristics are shown in Table 4) produced by the same method as in Step A of Reference Example 11, the short columnar Sn fine powder producing substance of Step B was used in the same size. The treatment was carried out in the same manner as in Step B of Reference Example 11 except that the short columnar Zn fine powder generating substance was replaced with. The fine Zn powder generated by this operation was the largest and had a major axis of about 5 μm. With respect to the magnet obtained by the above-mentioned treatment, ZnKα ray intensity measurement was performed using a standard sample.
It was found that a coating layer made of n fine powder was formed. Further, it was found that the resin portion on the surface of the magnet was covered with the adhered layer made of Zn fine powder.

Reference Example 14: For the magnet having the adhered layer of Zn fine powder on the entire surface of the magnet obtained in Reference Example 13,
The electric Cu plating treatment and the electric Ni plating treatment were performed under the same conditions as in Reference Example 12. The obtained plated coating had an outer diameter side film thickness of 24 μm and an inner diameter side film thickness of 22 μm. With respect to the magnet having this plating film, the surface condition after the moisture resistance test, the magnetic property deterioration rate measurement, and the dimensional accuracy measurement of the inner diameter side film thickness were performed in the same manner as in Reference Example 2. As a result, as is clear from Tables 5 and 6, the magnet having this plating film had excellent corrosion resistance and was formed with high film thickness dimensional accuracy.

Reference Example 15: Using a ring-shaped bonded magnet (characteristics are shown in Table 4) manufactured in the same manner as in Step A of Reference Example 11, the short columnar Sn fine powder producing substance of Step B was used in the same size. The treatment was carried out in the same manner as in Step B of Reference Example 11 except that the short columnar Pb fine powder producing substance in Example 2 was used. The Pb fine powder generated by this operation was the largest and had a major axis of about 5 μm. With respect to the magnet obtained by the above treatment, PbKα ray intensity measurement was performed using a standard sample, and as a result, P of 0.7 μm thickness was found on the magnetic powder on the magnet surface.
It was found that a coating layer made of fine powder was formed. Further, it was found that the resin portion on the surface of the magnet was covered with the adhered layer made of Pb fine powder.

Reference Example 16: For the magnet having the adhered layer of Pb fine powder on the entire surface of the magnet obtained in Reference Example 15,
The electric Cu plating treatment and the electric Ni plating treatment were performed under the same conditions as in Reference Example 12. The obtained plated coating had an outer diameter side film thickness of 24 μm and an inner diameter side film thickness of 22 μm. With respect to the magnet having this plating film, the surface condition after the moisture resistance test, the magnetic property deterioration rate measurement, and the dimensional accuracy measurement of the inner diameter side film thickness were performed in the same manner as in Reference Example 2. As a result, as is clear from Tables 5 and 6, the magnet having this plating film had excellent corrosion resistance and was formed with high film thickness dimensional accuracy.

Comparative Example 3: (Step A) A ring-shaped bonded magnet (having characteristics shown in Table 4) having an outer diameter of 25 mm, an inner diameter of 23 mm, and a height of 3 mm, which was manufactured by the same method as the step A of Reference Example 11, was washed. After that, by the dipping method, after forming an uncured phenol resin layer on the magnet,
Commercially available Ag powder (major axis 0.8 μm or less) was adhered to the resin surface. The obtained 50 ring-shaped bonded magnets (apparent volume 0.15 l, weight 83 g) were put into a treatment tank of a vibrating barrel device having a volume of 3.0 l, and a 2.5 mm diameter steel ball (apparent volume 2 l) was used as a medium. After 2 hours of treatment (total amount added is 72 vol% of the treatment tank internal volume), 1
It was cured at 50 ° C. for 2 hours to form a conductive coating layer of 8 μm on the magnet surface.

(Step B) For the magnet obtained in Step A,
The electric Cu plating treatment and the electric Ni plating treatment were performed under the same conditions as in Reference Example 12. With respect to the magnet having this plating film, the surface condition after the moisture resistance test, the magnetic property deterioration rate measurement, and the dimensional accuracy measurement of the inner diameter side film thickness were performed in the same manner as in Reference Example 2. As a result, as is clear from Tables 5 and 6, the magnets having this plating film were rusted and deteriorated in magnetic properties by the moisture resistance test, and the film thickness dimensional accuracy was low.

[0076]

[Table 4]

[0077]

[Table 5]

[0078]

[Table 6]

Reference Example 17: (Process A) Nd of 13 atomic%, F produced by a quenching alloy method
2w of an epoxy resin is added to an alloy powder having an average particle size of 150 μm and having a composition of 76 atomic% B, 6 atomic% B, and 5 atomic% Co.
t% was added and kneaded, and compression molding was performed at a pressure of 686 N / mm ² , followed by curing at 180 ° C. for 2 hours to prepare a ring-shaped bonded magnet having an outer diameter of 20 mm × an inner diameter of 17 mm × height of 6 mm. Table 7 shows the characteristics of the obtained ring-shaped bonded magnet (raw material).

(Step B) 50 magnets obtained in step A (apparent volume 0.15 l, weight 188 g) and an apparent volume 2 l of a short columnar Al having a diameter of 1.2 mm and a length of 1.5 mm.
Volume of fine powder generating substance (cut wire) 3.
The mixture was charged into a treatment tank of a 0 liter vibrating barrel device (total amount added was 72 vol% of the inner volume of the treatment tank), and the treatment was performed dry for 2 hours under the conditions of a frequency of 60 Hz and a vibration amplitude of 2 mm. The Al fine powder generated by this operation was the largest and had a major axis of about 5 μm. When the AlKα ray intensity of the magnet obtained by the above treatment was measured using a standard sample, the film thickness of 0.4 μm was found on the magnetic powder on the surface of the magnet.
It was found that the adhered layer made of Al fine powder was formed. Further, it was found that the resin portion on the magnet surface was covered with the adhered layer made of Al fine powder. A magnet having an adhered layer of Al fine powder on the entire surface of the magnet is
Even if it was left under the conditions of ℃ and relative humidity of 90%, rusting was not caused up to 36 hours (3 for surface condition).
(By 0-time microscope observation).

Reference Example 18: A magnet having an adhered layer of Al fine powder on the entire surface of the magnet obtained in Reference Example 17 was used in a zinc replacement solution (solution composition: 50 g of sodium hydroxide at a bath temperature of 20 ° C.).
/ L, zinc oxide 5 g / l, ferric chloride 2 g / l, Rochelle salt 50 g / l, sodium nitrate 1 g / l) for 1 minute for zinc substitution treatment. After cleaning the magnet, an electric Ni plating process was performed by a hook plating method. The treatment is performed with a current density of 2.2 A / dm ² , a plating time of 60 minutes,
The pH was 4.2, the bath temperature was 50 ° C., and the plating solution composition was 240 g / l of nickel sulfate, 45 g / l of nickel chloride, an appropriate amount of nickel carbonate (pH adjustment), and 30 g / l of boric acid. The obtained plated coating had an outer diameter side film thickness of 21 μm and an inner diameter side film thickness of 19 μm. With respect to the magnet having this plating film, the surface condition after the moisture resistance test, the magnetic property deterioration rate measurement, and the dimensional accuracy measurement of the inner diameter side film thickness were performed in the same manner as in Reference Example 2. As a result, as is clear from Tables 8 and 9, the magnet having this plating film showed excellent corrosion resistance and was formed with high film thickness dimensional accuracy.

Comparative Example 4: (Step A) A ring-shaped bonded magnet (having characteristics shown in Table 7) having an outer diameter of 20 mm, an inner diameter of 17 mm and a height of 6 mm, which was manufactured by the same method as in the step A of Reference Example 17, was washed. After that, by the dipping method, after forming an uncured phenol resin layer on the magnet,
Commercially available Ag powder (major axis 0.8 μm or less) was adhered to the resin surface. The obtained 50 ring-shaped bonded magnets (apparent volume 0.15 l, weight 188 g) were put into a treatment tank of a vibrating barrel device having a volume of 3.0 l, and 2.5 mm diameter steel balls (apparent volume 2 l) were used as media. After treating for 2 hours as a total (72 vol% of the total volume of the treatment tank),
It was cured at 150 ° C. for 2 hours to form a 7 μm conductive coating layer on the magnet surface.

(Step B) For the magnet obtained in Step A,
An electric Ni plating treatment was performed under the conditions described in Reference Example 18. With respect to the magnet having this plating film, the surface condition after the moisture resistance test, the magnetic property deterioration rate measurement, and the dimensional accuracy measurement of the inner diameter side film thickness were performed in the same manner as in Reference Example 2. As a result, as is clear from Tables 8 and 9, the magnets having this plating film were rusted and deteriorated in magnetic properties by the moisture resistance test, and the film thickness dimensional accuracy was low.

[0084]

[Table 7]

[0085]

[Table 8]

[0086]

[Table 9]

Reference Example 19: (Step A) Nd of 12 atomic%, F produced by a quenching alloy method
2w of an epoxy resin is added to an alloy powder having an average particle size of 150 μm, which is composed of 77 atomic% B, 6 atomic% B, and 5 atomic% Co.
t% was added and kneaded, and compression molding was performed at a pressure of 686 N / mm ² , followed by curing at 170 ° C. for 1 hour, vertical 30 mm × horizontal 2
A bonded magnet having a size of 0 mm and a height of 3 mm was manufactured. When this magnet was left under the condition of 80 ° C. and relative humidity of 90%, minute spot rust was generated in 12 hours (according to a microscope observation of the surface condition of 30 times).

(Step B) 50 magnets obtained in step A (apparent volume 0.1 l, weight 650 g) and apparent volume 2
1 μm in diameter of 2 mm and 1 mm in length of a short cylindrical Sn fine powder producing substance (wire is cut) is charged into a processing tank of a vibrating barrel device having a volume of 3.0 l (total charging amount is 72 vol% of the processing tank inner volume). ), Frequency 60Hz, vibration amplitude 2mm
The treatment was performed under dry conditions for 2 hours. The Sn fine powder generated by this operation was the largest from the ultrafine powder having a major axis of 0.1 μm or less, and the major axis was about 5 μm. When the SnKα ray intensity of the magnet obtained by the above treatment was measured using a standard sample, a coating layer made of Sn fine powder having a film thickness of 0.5 μm was formed on the magnetic powder on the surface of the magnet. I understood it. Further, it was found that the resin portion on the magnet surface was covered with the adhered layer made of Sn fine powder.

Reference Example 20: The sol liquid is shown in Table 10 as Si.
For each compound, catalyst, organic solvent and water component, Table 11
The composition, viscosity and pH shown in 1 were adjusted. The sol liquid was applied by a dip coating method at a pulling rate shown in Table 12 to a magnet having an adhered layer made of Sn fine powder on the entire surface of the magnet obtained in Reference Example 19, and heat treatment was performed. Si oxide coating (SiO _x coating: 0 <x ≦) with a thickness of 1.5 μm (measured by electron microscope observation of fracture surface) on the surface
2) was formed. A magnet having a Si oxide film obtained by this sol-gel film formation method was set at 80 ° C. and a relative humidity of 90.
%, It did not cause rusting up to 200 hours (according to a microscope observation of the surface condition of 30 times).

Reference Example 21: Using a bonded magnet prepared in the same manner as in Step A of Reference Example 19, the short columnar Sn fine powder producing substance of Step B was replaced with a short columnar Zn fine powder producing substance of the same size. Except for the above, the treatment was performed in the same manner as in Step B of Reference Example 19. Zn fine powder generated by this operation,
The largest one had a major axis of about 5 μm. For the magnet obtained by the above treatment, Z
When the nKα ray intensity was measured, it was found that an adhered layer made of Zn fine powder having a film thickness of 0.3 μm was formed on the magnetic powder on the surface of the magnet. Further, it was found that the resin portion on the surface of the magnet was covered with the adhered layer made of Zn fine powder.

Reference Example 22: The sol liquid is Ti shown in Table 10.
The components, the catalyst, the stabilizer, the organic solvent, and the water were adjusted to the composition, viscosity, and pH shown in Table 11. A sol solution was applied by a dip coating method at a pulling rate shown in Table 12 to a magnet having an adhered layer made of Zn fine powder on the entire surface of the magnet obtained in Reference Example 21, and heat treatment was performed. Ti oxide coating (TiO _x coating: 0) with a thickness of 0.7 μm (measured by electron microscope observation of fracture surface) on the surface
<X ≦ 2) was formed. Even if the magnet having the Ti oxide coating film obtained by this sol-gel film formation method was allowed to stand under the conditions of 80 ° C. and 90% relative humidity, rusting was not caused up to 200 hours. 30 times under a microscope).

Reference Example 23: Fifty bonded magnets (apparent volume 0.1
1, weight 650g) and apparent volume 2l diameter 1.2m
A short columnar Al fine powder producing substance (having a wire cut) having a length of m and a length of 1.5 mm was charged into a treatment tank of a vibrating barrel apparatus having a volume of 3.0 l (the total amount of the charge was 72 times the internal volume of the treatment tank).
vol%), the frequency was 60 Hz, and the vibration amplitude was 2 mm, and the dry treatment was performed for 2 hours. The Al fine powder generated by this operation was the largest from the ultrafine powder having a major axis of 0.1 μm or less, and the major axis was about 5 μm. For the magnet obtained by the above treatment, using a standard sample, AlK
When the α-ray intensity was measured, it was found that an adhered layer made of Al fine powder having a film thickness of 0.4 μm was formed on the magnetic powder on the surface of the magnet. Furthermore, the resin portion of the magnet surface is
It was found to be covered with an adherend layer made of Al fine powder.

Reference Example 24: The sol solution is shown in Table 10 as Si.
The composition, viscosity and pH shown in Table 11 were adjusted with each component of the compound, Al compound, catalyst, stabilizer, organic solvent and water. A sol solution was applied by a dip coating method at a pulling rate shown in Table 12 to a magnet having an adhered layer made of Al fine powder on the entire surface of the magnet obtained in Reference Example 23, and heat treatment was performed. 0.5 μm film thickness on the surface
Si-Al complex oxide coating (measured by electron microscope observation of fracture surface) (SiO _x Al ₂ O _y coating: 0 <x ≦ 2.0 <
y ≦ 3) was formed. A magnet having a Si—Al composite oxide film obtained by this sol-gel film formation method was
Even if it was left under the conditions of ° C and relative humidity of 90%, rusting was not caused up to 200 hours (according to a microscope observation of the surface condition of 30 times).

[0094]

[Table 10]

[0095]

[Table 11]

[0096]

[Table 12]

Reference Example 25: Palcoat 3753 (Product name: Ti-phosphoric acid chemical conversion treatment liquid manufactured by Nihon Parkerizing Co., Ltd.) was dissolved in 1 l of water to prepare a treatment liquid (p.
H3.8), A on the entire magnet surface obtained in Reference Example 17
1 A magnet having an adhered layer of fine powder was used at a bath temperature of 40 ° C.
After dipping for a minute, it was dried at 100 ° C. for 20 minutes to form a Ti-containing chemical conversion treatment film on the surface. The Ti content in the obtained coating was 10 mg per coating formed on 1 m ² of the magnet surface. Even if a magnet having this chemical conversion treatment film is left under the conditions of 80 ° C. and 90% relative humidity,
It did not cause rusting until 00 hours (according to a microscope observation of the surface condition of 30 times).

Reference Example 26: Palcoat 3756MA and Palcoat 3756MB (both product names: Zr-phosphoric acid type chemical conversion treatment liquid manufactured by Nippon Parkerizing Co., Ltd.) 1 each
Treatment liquid prepared by dissolving 0 g in 1 L of water (pH 3.2)
A magnet having an adhered layer made of Al fine powder on the entire surface of the magnet obtained in Reference Example 17 was immersed in a bath temperature of 50 ° C. for 1 minute and 30 seconds, and then dried at 120 ° C. for 20 minutes, and Z was formed on the surface.
An r-containing chemical conversion coating was formed. Zr in the obtained coating
The content is 1 per coating film formed on 1 m ² of the magnet surface.
It was 6 mg. A magnet having this chemical conversion coating is
Even when left under conditions of 0 ° C. and 90% relative humidity, rusting did not occur up to 200 hours (according to a microscope observation of the surface condition of 30 times).

[0099]

EFFECTS OF THE INVENTION In the rare earth-based sintered magnet of the present invention, an adherent layer consisting essentially of fine metal powder is firmly and densely formed on the metal constituting the magnet surface. Therefore, a film having excellent corrosion resistance can be formed with high film thickness dimensional accuracy by electroplating or the like, and the magnet dimensional accuracy can be improved. Further, since the adhered layer made of fine metal powder itself has an anticorrosion effect, it itself serves as an anticorrosion layer for the magnet.

Continuation of front page (51) Int.Cl. ⁷ identification code FI C23C 28/00 C23C 28/00 C H01F 41/02 H01F 41/02 G (56) Reference JP-A-9-205013 (JP, A) Kai 61-166116 (JP, A) JP 9-8810 (JP, A) JP 9-289108 (JP, A) JP 7-161516 (JP, A) JP 62-87237 ( (58) Fields investigated (Int.Cl. ⁷ , DB name) H01F 1/00-1/117 H01F 41/00-41/04 H01F 41/08-41/10 C23C 24/00-28 / 00

Claims (10)

(57) [Claims] 1. A rare earth sintered magnet and a size of 0.3 mm
Put the metal fine powder generating substance of 10 mm into the processing container, and
In the processing container, apply vibration to both and / or both
By stirring the
Along with generating fine metal powder of 0.001 μm to 5 μm
The fine metal powder generated on the metal that constitutes the magnet surface.
A rare earth-based sintered magnet, characterized in that it has an adherend layer consisting essentially of fine metal powder on the metal constituting the magnet surface , which is obtained by adhesion. 2. The fine metal powder is Cu, Fe, Ni, Co, C.
The rare earth-based sintered magnet according to claim 1, comprising at least one metal component selected from r. 3. The rare earth-based sintered magnet according to claim 1, wherein the Vickers hardness value of the fine metal powder is 60 or less. 4. The fine metal powder is Sn, Zn, Pb, Cd, I.
The rare earth-based sintered magnet according to claim 1, comprising at least one metal component selected from n, Au, Ag, and Al. 5. The rare earth based sintered magnet according to claim 1, wherein the rare earth based sintered magnet is an R—Fe—B based sintered magnet. 6. The thickness of the adherend layer is 0.001 μm to 0.2.
The rare earth-based sintered magnet according to claim 2, wherein the sintered magnet has a thickness of μm. 7. The thickness of the adherend layer is 0.001 μm to 100 μm.
The rare earth-based sintered magnet according to claim 3, wherein the sintered magnet has a diameter of μm. 8. A rare earth-based sintered magnet according to claim 1, wherein the surface of the adhered layer substantially consisting of only the fine metal powder has a plating film. 9. A rare earth-based sintered magnet according to claim 1, wherein the adhered layer of the rare earth-based sintered magnet according to claim 1 has a metal oxide film on the surface of the adhered layer. 10. A rare earth-based sintered magnet having a chemical conversion treatment film on the surface of an adhered layer of the rare earth-based sintered magnet according to claim 1, which is substantially composed of only metal fine powder.