JP2652688B2 - Permanent magnet and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to R (where R is one of the rare earth elements including Y)
Or more), a permanent magnet containing Fe and B, and a method for producing the same.

<Conventional technology> Powder metallurgy is used as a high-performance permanent magnet.
Sm-Co magnets with an energy product of 32MGOe are mass-produced.

However, this has the disadvantage that the raw material prices of Sm and Co are high. Among rare earth elements, rare earth elements having a small atomic weight, such as cerium, praseodymium, and neodymium, are more abundant and cheaper than samarium. Fe is inexpensive.

In recent years, Nd-Fe-B magnets have been developed.
In JP-46008, sintered magnets are disclosed in Japanese Patent Application Laid-Open No. 60-9852.
In Japanese Patent Application Laid-Open Publication No. H10-209, a method using a rapid quenching method is disclosed.

This is a high-performance magnet that shows a high energy product of 25MGOe or more, but because it contains a rare-earth element and iron, which are easily oxidized, as main components, the corrosion resistance is low, and the performance is degraded. I have.

For the purpose of improving the low corrosion resistance of such R-Fe-B-based magnets, there has been proposed a permanent magnet having various corrosion-resistant protective layers on its surface or a method of manufacturing the same (Japanese Patent Application Laid-Open No. 60-1985). JP-A-54406, JP-A-60-63901,
No. 60-63902, No. 61-130453, No. 61-150201
JP-A-61-166115, JP-A-61-166116,
Nos. 61-166117, 61-185910, 61-270308
And JP-A-62-120004.

Such a protective layer is made of a material such as a metal, a compound such as a metal oxide or a metal nitride, an organic material such as glass or a resin, or a mixture thereof.

In addition, as the layering method, liquid phase plating such as electroplating, sputtering, ion plating, vapor phase plating such as vacuum deposition, dip coating, brush coating, injection, hot dipping,
A coating method such as electrodeposition coating is applied.

<Problems to be Solved by the Invention> The protective layer as described above contains chlorine not only when the material itself is contained as a constituent element but also when introduced or mixed in the manufacturing process. Often.

Further, chlorine is often introduced or mixed into the surface of the magnet or the interface between the protective layer and the magnet in the manufacturing process.

Then, the chlorine contained in any of the methods as described above may be interdiffused in the protective layer, the interface between the protective layer and the magnet surface or the magnet surface layer in the vicinity thereof, and may be contained in these portions. is there.

Such chlorine produces rust over time. Furthermore, blisters are generated and the adhesion between the protective layer and the magnet is deteriorated.

An object of the present invention is to provide a permanent magnet capable of preventing generation of rust and deterioration of adhesion due to aging.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides the following (1) to
It has the configuration of (6).

(1) R (where R is one or more rare earth elements including Y), Fe and B, and a protective layer is provided on the surface of a permanent magnet body having a substantially tetragonal main phase. A permanent magnet, wherein the chlorine content near the interface between the protective layer and the permanent magnet body is 0.1% by weight or less.

(2) The permanent magnet according to (1), wherein the protective layer is formed by electroplating.

(3) The permanent magnet according to the above (1) or (2), wherein the chlorine content in the protective layer is 200 ppm or less.

(4) The above (1) to (1) to wherein the protective layer contains Ni as a main component.
The permanent magnet according to any one of (3).

(5) A protective layer is formed by plating on the surface of a permanent magnet body containing R (where R is one or more rare earth elements including Y), Fe and B and having a substantially tetragonal main phase. A method for producing a permanent magnet, wherein a chlorine content of a solution used for forming a layer is 100 ppm or less.

(6) The method for producing a permanent magnet according to the above (5), wherein the solution is a pretreatment solution, a washing solution, and a plating bath in an electroplating method.

<Action> According to the present invention, preferably, the chlorine content near the interface between the protective layer formed by electroplating and the permanent magnet body is reduced.
0.1 wt% or less.

With such a chlorine content, generation of rust over time and deterioration of adhesion between the protective layer and the permanent magnet body are prevented.

<Specific Configuration> Hereinafter, a specific configuration of the present invention will be described in detail.

In the permanent magnet of the present invention, the chlorine content near the interface between the protective layer provided on the surface of the permanent magnet body and the permanent magnet body (hereinafter, the interface) is 0.1 wt% or less, preferably 0.07 wt%.
It is as follows.

Here, the vicinity of the interface between the protective layer and the permanent magnet body refers to a region of about 50 to 200 μm from the interface, respectively.

When the chlorine content in the protective layer is as described above, it is possible to mainly prevent the occurrence of blisters with the passage of time.

Further, when the chlorine content of the surface layer of the permanent magnet near the interface is as described above, it is possible to prevent the generation of rust and blistering over time.

Therefore, when the chlorine content is outside the above range, rust and blistering over time become remarkable.

Chlorine is contained in the material constituting the protective layer itself, or is introduced or mixed not only into the protective layer but also into the surface layer of the permanent magnet body in the manufacturing process of forming the protective layer.

Further, the chlorine contained by any of such methods may be contained by being interdiffused in the protective layer, the interface, or the surface layer of the permanent magnet body.

Therefore, in the present invention, the amount of chlorine contained in the permanent magnet is regulated as described above, and the effect of the present invention can be obtained by regulating as described above.

The chlorine content in the protective layer, the interface and the surface layer of the permanent magnet body can be quantified by EPMA analysis. In this method, in particular, the amount of chlorine collected in the minute part can be measured. Since actual rust is generated from such a local part, the content of chlorine in a minute part is not a problem in a wide part but a problem.

In addition, it can be quantified by Auger electron spectroscopy, EDAX and ESCA.

The material of the protective layer used in the present invention, metal,
Examples thereof include metal compounds such as metal oxides and metal nitrides, organic substances such as glass and resin, and mixtures thereof.

Of these materials, it is natural to use those that do not contain chlorine, and it is better to use those having a mixing amount of 200 ppm or less, preferably 100 ppm or less.

In addition, as a method of forming a protective layer, electroplating,
Any of the known coating methods such as known liquid-phase plating such as electroless plating, known vapor-phase plating such as sputtering, ion plating, and vacuum deposition, dip coating, brush coating, injection, hot-dip plating, and electrodeposition coating. You may choose.

Also in this case, it is necessary to prevent chlorine from being introduced or mixed in the layer, and it is necessary to set conditions so that the chlorine content in the protective layer or the like falls within the above range.

The material of the protective layer and the method of forming the layer may be appropriately combined and used, and the material and the method of forming the layer may be selected according to the use of the permanent magnet.

For example, preferred combinations include Ni, Zn, and Co-
Examples include electroplating of Ni-Cr or the like, ion plating of Ni or Al, coating of organic compounds, and hot-dip plating of low melting point metals such as Zn and solder.

Among these, in the present invention, Ni, Zn, Co
-It is preferably an electroplating film of Ni-Cr or the like.

This is because a high-performance corrosion resistant film excellent in mass productivity can be produced. However, special care must be taken to prevent the introduction or contamination of chlorine.

In the case of using Ni electroplating, which is a particularly preferred embodiment, in the preparation of the electroplated film, the plating bath is usually a watt bath, a sulfamic acid bath or the like contains nickel chloride. Must be included.

For this reason, examples of the plating bath used include the above-described Watt bath, sulfamic acid bath, borofluoride bath, and nickel bromide bath that do not contain a nickel chloride component. However, in this case, since the dissolution of the anode is reduced, it is necessary to replenish the bath with nickel ions. The nickel ions are preferably replenished as a solution of nickel sulfate or nickel bromide.

For example, such a plating bath has the following composition.

Nickel sulfate 220-370 g / boric acid 30-60 g / saccharin 0.1-5 g / 2-butyne-1,4-diol 0.05-0.5 g / Also commercially available as Sulnic C [produced by Uemura Kogyo Co., Ltd.] Are also preferably used.

At this time, the water in the bath preferably does not contain chlorine, and the chlorine content in the bath is preferably 100 ppm or less.

As described above, by removing the chlorine component from the plating bath, it is possible to prevent blisters mainly due to aging.

Plating conditions are pH 2.7-4.5, temperature 35-70 ° C, current density
It may be about 0.2 to 20 A / m ² .

When the above-mentioned electroplating is performed, pretreatment such as acid immersion or degreasing is usually performed in order to clean the surface of the permanent magnet body which is the object to be plated. Also at this time, it is necessary to suppress the contamination of chlorine.

Therefore, the acid used in the acid immersion needs to be an acid containing no chlorine. For example, sulfuric acid, nitric acid, phosphoric acid and the like are preferable, and nitric acid and sulfuric acid are particularly preferable. Nitric acid may be used alone or in combination as an acidic solution.

Thus, by using nitric acid or sulfuric acid, not only the incorporation of chlorine can be prevented, but also the adhesion to a protective layer formed by electroplating can be improved.

 The use of chloric acid such as hydrochloric acid should be avoided.

By avoiding the use of chloric acid, the generation of rust and blisters over time can be prevented.

 In addition, the amount of chlorine in the acidic solution is 100 ppm or less.

The concentration of the acid solution used for acid immersion is 0.0001-3N, especially
It is preferably about 0.001 to 0.1N.

Also, when applying the degreasing method, it is necessary to select conditions under which chlorine is not mixed, and the chlorine content is set to 100 ppm or less.

Further, it is preferable that water used in the pretreatment and the plating step is subjected to a treatment such as ion exchange and dechlorinated. The chlorine content of this ion exchange water is usually
It is better to be 1 ppm or less.

By using ion-exchanged water or the like as described above, it is possible to mainly prevent generation of rust due to aging.

In addition, even when performing other metal plating, the chlorine component of the plating bath is similarly suppressed.

In the present invention, known multi-layer plating such as double nickel plating and tri-nickel plating as described in page 115 of the plating technology guidebook (published by Tokyo Plating Materials Cooperative Union) is also preferably used. it can.

Further, at least one of the multilayer platings may be formed by electroless nickel plating to serve as a protective layer or a corrosion sacrificial layer. In addition, since electroless plating is also deposited on a place where it is difficult to form a layer by electroplating such as the inner wall surface of a tubular magnet, it is preferable to use electroless plating according to the shape of the magnet.

When the protective layer is formed by liquid phase plating, it is preferable to examine the pH stability of the magnet and use, for example, a plating bath within the stable pH range as described above.

The layer thickness of the protective layer may be selected in an optimum range depending on the material, layering method, application and the like, but is usually about 5 to 100 μm.

In the present invention, the permanent magnet body on which the protective layer is provided on the surface contains R (where R is one or more rare earth elements including Y), Fe and B.

 The contents of R, Fe and B are preferably 5.5 at% ≦ R ≦ 30 at% 42 at% ≦ Fe ≦ 90 at% 2 at% ≦ B ≦ 28 at%.

In particular, when the permanent magnet body is manufactured by the sintering method, the following composition is preferable.

As the rare earth element R, at least one of Nd, Pr, Ho, and Tb, or La, Sm, Ce, Gd, Er, Eu,
Those containing at least one of Pm, Tm, Yb, and Y are preferable.

When two or more elements are used as R, a mixture such as misch metal can be used as a raw material.

 The content of R is preferably 8 to 30 at%.

If the content is less than 8 at%, a high coercive force (iHc) cannot be obtained since the crystal structure has a cubic structure identical to that of α-iron, and
If it exceeds t%, the number of R-rich nonmagnetic phases increases, and the residual magnetic flux density (Br) decreases.

 The content of Fe is preferably 42 to 90 at%.

If Fe is less than 42 at%, Br decreases, and if it exceeds 90 at%, iHc decreases.

 The B content is preferably 2 to 28 at%.

If B is less than 2 at%, a rhombohedral structure is formed, resulting in insufficient iHc. If B exceeds 28 at%, the B-rich non-magnetic phase increases and the Br decreases.

By replacing a part of Fe with Co, the temperature characteristics can be improved without impairing the magnetic characteristics. In this case, if the amount of Co substitution exceeds 50% of Fe, the magnetic properties deteriorate, so the amount of Co substitution is preferably set to 50% or less.

Further, in addition to R, Fe and B, N
i, Si, Al, Cu, Ca and the like may be contained in an amount of 3 at% or less.

Further, by replacing a part of B with one or more of C, P, S, and Cu, improvement in productivity and reduction in cost can be realized. In this case, the substitution amount is preferably 4 at% or less of the whole.

In addition, in order to improve coercive force, improve productivity, and reduce costs, Al, Ti, V, Cr, Mn, Bi, Nb, Ta, Mo, W, Sb,
One or more of Ge, Sn, Zr, Ni, Si, Hf and the like may be added. In this case, it is preferable that the total amount is 10 at% or less.

The permanent magnet body according to the present invention has a main phase having a substantially tetragonal crystal structure.

The particle size of the main phase is preferably about 1 to 100 μm.

And usually, it contains a non-magnetic phase of 1 to 50% by volume ratio.

Such a permanent magnet body is disclosed in the above-mentioned JP-A-61-185910.
No. 6,009,036.

The above-described permanent magnet body is preferably manufactured by a sintering method as described below.

First, an alloy having a desired composition is cast to obtain an ingot.

The obtained ingot is subjected to particle size 10 by a stamp mill or the like.
It is roughly pulverized to about 100 μm and then finely pulverized to a particle size of about 0.5 to 5 μm by a ball mill or the like.

The obtained powder is molded preferably in a magnetic field. In this case, the magnetic field strength is 10 kOe or more, and the molding pressure is 1 to 5 t / cm ²
It is preferred that it is about.

The obtained compact is sintered at 1000 to 1200 ° C. for 0.5 to 5 hours and quenched. Note that the sintering atmosphere is preferably an inert gas atmosphere such as Ar gal.

Thereafter, preferably in an inert gas atmosphere, 500 to 900
Aging treatment is performed at 1 ° C. for 1 to 5 hours.

The present invention is not limited to the permanent magnet body manufactured by the sintering method described above, but can be suitably applied to a bulk magnet manufactured by a so-called quenching method.

Bulk magnets manufactured by a quenching method and having particularly excellent magnetic properties and preferably used in the present invention are described in Japanese Patent Application Nos. 62-90709, 62-191380 and 62-25937.
No. 3, etc.

<Example> Hereinafter, the present invention will be described specifically with reference to examples.

Example 1 Production of Permanent Magnet Body An ingot having a composition of 14Nd-1Dy-7B-78Fe (the number is an atomic ratio) was obtained by casting.

This ingot was roughly pulverized by a stamp mill and then finely pulverized by a ball mill to obtain an alloy powder having an average particle size of 3.5 μm.

This alloy powder was compacted under a magnetic field of 12 kOe at a pressure of 1.5 t / cm ² to obtain a compact.

After heating this molded body at 1100 ° C. for 1 hour in an Ar atmosphere,
It was quenched to obtain a sintered body.

The obtained sintered body was subjected to aging treatment at 600 ° C. for 2 hours in an Ar atmosphere to obtain a permanent magnet. Next, a magnet piece was cut out from the permanent magnet to obtain a permanent magnet body.

Degreasing and Derusting of Permanent Magnet The permanent magnet prepared as described above was immersed in Endox 114 solution (120 g /, 60 ° C.) manufactured by Japan Metal Finishing Company for 10 minutes.

 The chlorine content in this solution was 12 ppm.

Acid immersion treatment 1N HNO ₃ using ion exchange water (chlorine content 0.5ppm)
A solution was prepared. The permanent magnet thus treated was immersed in this solution at room temperature for 5 minutes.

After the permanent magnet body subjected to the above treatment was washed with the above ion-exchanged water, using a plating bath having the following composition, a bath temperature of 55 ° C,
Electroplating was performed at a current density of 3 A / dm ² . The bath pH is
4.5, and all water used in the plating step was ion-exchanged water. Further, the chlorine content in the plating bath was 7 ppm.

(Plating bath composition) in the nickel sulfate _{(NiSO 4 · 7H 2 O)} 300g / boric acid (H ₃ BO ₃₎ 40g / saccharin 2 g / sodium lauryl sulfate 0.05 g / Thus, to obtain a protective layer having a thickness of 20μm .

 This plating was bright plating.

The film thickness was measured with a Seiko electron fluorescent X-ray film thickness meter.

The permanent magnet manufactured in this manner is referred to as Sample No. 1.

1N used in acid immersion treatment in sample No. 1 above
Sample No. 2 was prepared in the same manner except that HNO ₃ solution was prepared using tap water (chlorine content: 20 ppm) instead of ion-exchanged water.

In sample No. 1, the plating bath was changed to Sulnic C (chlorine-free bath: chlorine content of 20
ppm) except that Sample N was used.
o.3.

In sample No. 3, a 0.5NH ₂ SO ₄ solution (chlorine content 2
0ppm) except that the sample was prepared in the same way.
No.4.

Sample No. 5 was prepared in the same manner as in Sample No. 1 except that a plating bath having the following composition was used and the current density was 4 A / dm ³ . The chlorine content in the plating bath was 1.3% by weight.

(Plating bath composition) nickel sulfate _{(NiSO 4 · 7H 2 O)} 280g / nickel chloride _{(NiCl 4 · 6H 2 O)} 45g / boric acid (H ₃ BO ₃₎ 40g / saccharin 2 g / sodium lauryl sulfate 0.05 g / sample No .3, a 1N HCl solution (chlorine content 3.6 wt.
%), The sample was prepared in the same manner except that the measurement was performed for 10 minutes, and the sample was designated as Sample No. 6.

After applying the acid immersion treatment in sample No. 2 and further rinsing with tap water (chlorine content 20 ppm),
Sample No. 7 was prepared by applying the plating bath in No. 3.

For the samples No. 1 to No. 7 thus produced, the protective layer was peeled off by applying a physical force from the permanent magnet body.

 Peeling occurred near the interface between the permanent magnet body and the protective layer.

The amount of chlorine on the peeled surface was determined by EPMA. in this case,
Ten points were measured for each sample, and the maximum value was defined as the amount of chlorine.

 In addition, the measurement spot diameter was set to 0.5 μm to 1 μm.

Further, the samples No. 1 to No. 7 were allowed to stand for 2000 hours under the conditions of 60 ° C. and 90% RH to perform a weather resistance test and observe changes in appearance.

 Table 1 shows the results.

<Effects of the Invention> According to the present invention, it is possible to prevent the generation of rust over time and the deterioration of the adhesion between the permanent magnet body and the protective layer.

Claims (6)

(57) [Claims] 1. R (where R is one of the rare earth elements including Y)
A permanent magnet comprising Fe and B, a substantially tetragonal main phase, and a protective layer provided on the surface of the permanent magnet, in the vicinity of the interface between the protective layer and the permanent magnet. A permanent magnet having a chlorine content of 0.1% by weight or less. 2. The permanent magnet according to claim 1, wherein said protective layer is formed by electroplating. 3. The permanent magnet according to claim 1, wherein the chlorine content in the protective layer is 200 ppm or less. 4. The protective layer according to claim 1, wherein the protective layer contains Ni as a main component.
3. The permanent magnet according to any one of 3. 5. R (where R is one of the rare earth elements including Y)
), The chlorine content of the solution used for forming the protective layer by plating on the surface of the permanent magnet body containing Fe and B and having a substantially tetragonal main phase is 100 ppm or less. A method for producing a permanent magnet, comprising: 6. The method for producing a permanent magnet according to claim 5, wherein the solution is a pretreatment solution, a washing solution and a plating bath in an electroplating method.