JPH04119604A - Manufacture of bonded magnet - Google Patents

Abstract

PURPOSE:To recover the magnetic characteristics deteriorated by pulverization to provide a high magnetic characteristics by a method wherein, after bulk material has been powdered, classified and heat-treated, the powder is coated with the oxidation- resistant substance consisting of the single metal or the alloy of two or more kinds selected from Al, Sn, Zn, In, Pb and Ga, or an eutectic compound containing a kind of the above-mentioned elements. CONSTITUTION:After sintered type or high-speed quenched type permanent magnet bulk material, containing rare-earth element, iron and boron as fundamental components, has been powdered, classified and heat-treated, the powder is coated with the single metal of a kind selected from Al, Sn, In, Pb and Ga, or the alloy of two or more kinds, or the oxidation-resistant substance consisting of the eutectic compound containing at least a kind of the above-mentioned six kinds of elements. After a heat treatment has been conducted again, the above material is mixed with a binder, and molded in a magnetic filed. Or, after powdering, classification and heat treatment have been finished, oxidation-resistant substance consisting of resin is coated or R(R indicates a kind of Nd, Pr, Dy, Ho and Tb and/or a kind of La, Ce, Sm, Er, Eu, Yb, La and Y) is added or coated, and then a heat treatment is conducted at 400 to 900 deg.C for the period not exceeding three hours in a vacuum or inert atmosphere.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a bonded magnet in which raw material powder containing rare earth elements (R) iron and boron as basic components is bonded with a synthetic resin. , sintered type and quenched type R-
The present invention relates to a method of manufacturing a bonded magnet that exhibits high magnetic properties using a bulk Fe-B permanent magnet as a raw material.

(Prior Art) Conventionally, R-Fe-B magnets have been developed as rare earth magnets.

This R-Fe-B magnet includes a sintered type and a high-speed quenched type.

On the other hand, bonded magnets have conventionally been manufactured, for example, by the following method.

That is, the above-mentioned high-speed quenching type or sintering type R-Fe
-B-based permanent magnet bulk body is used as a raw material, which is pulverized and classified according to particle size. Then, synthetic resin (for example, epoxy resin, etc.), which is the binder of this powder, is added to the classified powder.
Add and mix and knead uniformly. After the kneaded product is molded into a predetermined shape in a magnetic field, the molded product is cured.

In addition, the above-mentioned molding in a magnetic field generally employs a compression molding method to increase the density of the molded body to produce a bonded magnet having good magnetic properties.

(Problem to be solved by the invention) However, when bonded magnets are manufactured using sintered R-Fe-B permanent magnet bulk materials as raw materials, the coercive force deteriorates significantly, making it difficult to produce products with sufficient magnetic properties. can't get it.

In addition, in bonded magnets made from high-speed quenched R-Fe-B permanent magnet bulk material, although there is no deterioration in coercive force, there is deterioration in squareness and a decrease in energy product, and it is necessary to obtain a sufficiently high magnetic field. It is difficult to bring out its characteristics.

As mentioned above, the deterioration of squareness when using high-speed quenched bulk bodies as raw materials, the deterioration of coercive force and the decrease in energy product when using sintered bulk bodies as raw materials, are caused by the fact that these bulk bodies are crushed. This is thought to be due to the effects of oxidation and stress that occur during this process.

The present invention has been made in view of the above points, and
The purpose is to restore the magnetic properties deteriorated by the above-mentioned pulverization and to propose a method for producing a bonded magnet with high magnetic properties.

(Means for Solving the Problems) In order to achieve the above-mentioned objects, the present invention (1) crushes and classifies a sintered or high-speed quenched permanent magnet bulk body containing rare earth elements 1 iron and boron as basic components; After heat treatment, A
l, Sn, Zn, In.

After coating with an oxidation-resistant substance made of a single metal of Pb or Ga, an alloy of two or more, or a eutectic compound containing at least one of the six elements, heat-treated again, and then coated with a binder. A method for manufacturing a bonded magnet, which comprises mixing and forming in a magnetic field.

(2) A sintered or high-speed quenched permanent magnet bulk body containing rare earth elements, iron and boron as basic components is crushed and classified into two parts,
1. A method for producing a patented magnet, characterized in that, after heat treatment, it is coated with an oxidation-resistant material made of resin, then mixed with a binder, and then molded in a magnetic field.

(3) The bonded magnet according to claim 1.2, wherein after the bulk body is crushed and classified, any one of the following (A) to (P) is added or coated to the classified powder. How to manufacture.

(B) RXTM, (R; Same as (A), TM; Fe
, Co at least one kind or a part thereof is replaced with St, Ti,
V, Cr, Mn, Ni, Zr.

At least one of Fe and Co substituted with at least one of Nb, Mo, If, Ta, W, Mg, and Ca
Seed, 10<x<100.0<y<90°)H+y=100).

(C) RM (R; Same as (A), y M; Ag, Cu, Zn, Ga, Ge, Ag, In.

At least one of Sn, Sb, Au, and Bi, 20
<x<100.0<y<80°x+y-100).

(D) RxTMy M (R; Same as (A), T
M: yZ Same as (B), M, Same as (C), 10<x<10
0. O<y<90°Q<z<80. x+y+z=100) (E) RTM (B, C) z (R:
Same as (A), y TM ; Same as (B), 10<x<100. O<y<90°0<z<80. x+y+z-100) (F)RxTMy M (B, C), (R
; Same as (A) X yz same, TM; Same as (B), M, same as (C), 1
0<x<100.0<y<90°0<z<80. 0<w<80°x+y+z+w-100).

(4) After crushing and classifying the bulk material, or after adding or coating any one of (A) to (P) of claim 3 to the classified powder, heat treatment is performed in a vacuum or an inert atmosphere. A method for producing a bonded magnet according to any one of claims 1 to 3, characterized in that the bonded magnet is manufactured at a temperature of 400 to 900°C for within 3 hours.

(Function) The present invention is characterized in that the magnetic properties when formed into a bonded magnet are greatly affected by oxidation and mechanical distortion of the raw material sintered and rapidly quenched R-Fe-B permanent magnet bulk powder. (1) Heat treatment of the powder - AIl, Sn, Zn.

Any one of In, Pb, Ga or two
Coating with an oxidation-resistant substance made of an alloy of six or more elements, or a eutectic compound containing at least one of the six elements - heat treatment, or (2) heat treatment of the above powder - coating with an oxidation-resistant substance made of a resin. Coating or (3) Adding or coating any one of the above-mentioned (A) to (F) to the above-mentioned powder - This problem can be solved by performing the above-mentioned step (1) or (2).

That is, the sintered R-Fe-B permanent magnet bulk body is
As shown in the schematic diagram of FIG. 2(A)-1, for example, Nd
2Fe14B is the main phase 1, and this is used as the Nd-rich phase 2 and B
It is a nucleation type magnet surrounded by rich phase 3.

In nucleation magnets, the interface between the main phase 1 and the Nd-rich phase 2 that surrounds it plays an important role in generating coercive force, and the main phase also has defects (such as cracks, The one with few dislocations is shown in Figure 2 (A).
Exhibits good magnetic properties as shown in -2.

When such a bulk body is crushed, the main phase 1 is cracked, and N is formed around the main phase 1, as shown in the schematic diagram of Figure 2 (B)-1.
Some defects occur in the d-rich phase, and defects such as cracks occur in the main phase 1, resulting in a sharp decrease in coercive force as shown in FIG. 2(B)-1.

In the present invention, such pulverized powder is subjected to the above-mentioned treatment (1), (2), or (3).

In the case of treatments (1) and (2), first, as shown in the schematic diagram of FIG. 3(a), by heat treatment,
The defects in the Nd-rich phase 2 of 1 have been partially eliminated, and as shown in Fig. 3 (b
), the magnetic properties are restored. Next, Figure 3 (
The surface of the powder in the state shown in a) is coated with an oxidation-resistant substance. Therefore, contact with the atmosphere is prevented during subsequent processing, there is almost no surface deterioration, and magnetic properties are developed that are better than conventional ones.

Note that when a resin is used as the oxidation-resistant substance in (2) above, heat treatment is not required. For example, when using an epoxy, acrylic, or phenolic resin as the resin, this may be done by diluting these resins with a solvent and spraying this onto the powder in an inert atmosphere, or This is because the surface of the powder can be uniformly coated by, for example, dipping the powder in the solution.

On the other hand, when using the oxidation-resistant substance described in (1) above, it is necessary to melt the oxidation-resistant substance on the powder surface in order to uniformly coat the powder surface. A heat treatment must be performed afterwards.

In addition, in the case of the above treatment (3), any one of the above-mentioned (A) to (P) is added or coated to the powder in the state shown in Figure 2 (B)-2, and this is heat-treated. , (A) ~
Any one of (F) melts on the powder surface, flows to the powder surface, and penetrates into the powder, filling the gaps in the Nd-rich phase 2 and preventing disadvantages such as mechanical distortion and oxide film. The interface of the main phase 1 is restored to the same level as the original interface. The recovered interface is then held with the above-mentioned oxidation-resistant material so that it will not be attacked during subsequent processing.

In order to obtain the above effects in the heat treatment in the above treatments (1) to (3) (in the case of treatment (1), the heat treatment is performed before and after coating with the oxidation-resistant substance), the temperature is set at 400°C. The temperature is preferably 600 to 800°C, particularly 600 to 800°C. That is, if the temperature is lower than 400° C., atomic diffusion will be insufficient and the above effects will not occur. If the temperature is higher than 900° C., the crystal grain size becomes coarse and oxidation occurs, which not only deteriorates the magnetic properties but also causes problems such as changes in the shape of the molded product.

Further, the time for the above heat treatment is appropriately selected depending on the above heat treatment temperature, but if it exceeds 3 hours, the magnetic properties will deteriorate due to coarsening of the crystal grain size and oxidation, so in the present invention, the time is within 3 hours. That is to say.

Note that if the heat treatment time is shorter than 0.2 hours, atomic diffusion between the particles and at the grain interface may become insufficient, so the lower limit of the heat treatment time is preferably 0.2 hours.

Furthermore, the reason why the above heat treatment is performed in a vacuum or in an inert atmosphere is to prevent oxidation of the above-mentioned broken surfaces, cracks 4, and interfacial fractures 5, since this oxidation is promoted by heat.

Further, the above heat treatment is not limited to continuous heat treatment as shown in FIG. 4(A), and as shown in FIG. 4(B), Even with discontinuous heat treatment within hours, the above effect can be obtained.

In the present invention, resin impregnation is performed after the above heat treatment.

As a result, the resin penetrates into the particles after molding and locks the particles together, making it possible to firmly maintain the shape after molding.

Sintered R- which is the raw material for expressing the above effects.
In the present invention, R(
R is Nd, Pr, Dy, Ho.

At least one of Tb or further La, Ce.

Sm, Gd, Er, Eu, Tm, Yb,
consisting of at least one of Lu, Y) 8 to 3o
A composition having a composition of 2 to 28 atomic % of B, 42 to 9 atomic % of Fe is preferably used. Furthermore, for the purpose of improving the Curie point, etc., up to 50% of Co may be substituted for Fe.

Furthermore, the high-speed quenching type exhibits similar effects although there is a difference in crystal grain size.

(Example) Example 1 The method according to the present invention was carried out according to the flow shown in FIG. 1(A).

In this example, the composition formula (NdPrDy)
14.1 0.4 1.5 Fe B 18.0 77.0 7.0 Nd-Fe-
The B-based alloy was ground with a jet mill to give an average particle size of 3 μs.
A sintered Nd-Fe-B permanent magnet bulk body obtained by molding this powder in a magnetic field, sintering it, and aging it was used as a raw material. In addition, the magnetic properties of this raw material bulk body are
It was as follows.

The above raw material was crushed using a show crusher and classified to obtain a powder of 125 μm or less.

This classified powder was heated in a vacuum of I x 10 = 7 Torr.
Heat treatment was performed at 00°C for 1 hour. The heat treatment at this time was carried out in the pattern shown in FIG. 4(A).

This powder was introduced into a vapor deposition apparatus and
Afi, Zn as oxidation-resistant metals in vacuum.

Pb, Al1-3i, and Pb-8e were used and deposited to an average film thickness of 0.5 μI.

These vapor-deposited powders were heat-treated at 700°C for 1 hour in a vacuum of I x 10-6 Torr. The heat treatment at this time was carried out in the pattern shown in FIG. 4(A).

Next, 3 vt% of epoxy resin was thoroughly mixed with these powders in a mortar, and while oriented in a magnetic field of 15 kOe, compression molding was performed at a molding pressure of 3 ton/c-.
After-cure was performed at 20°C for 2 hours.

Three bonded magnets (sample) were manufactured in the above manner. The magnetic properties of each of these three samples were measured, and the results are shown in Table 1.

For comparison, similar magnetic measurements were carried out on three samples manufactured using the conventional method flow shown in Figure 5 (A).
The results are also shown in Table 1.

As is clear from Table 1, in conventional method comparative example 1), Br
, iHc, and (B-H), it can be seen that bonded magnets with extremely low ax can be obtained. From this, it can be seen that the magnetic properties deteriorated due to the pulverization of the raw material bulk body cannot be recovered by compression molding of Comparative Example 1 alone. On the other hand, in Example 1 of the present invention, in which the particle surface is coated and heat treated, Br.

Both iHc and (B-H) significantly increased, and Aa
I understand that

Example 2 The method according to the present invention was carried out according to the flow shown in FIG. 1(A).

In this example, the composition formula is Nd Fe C.

The 5.4 solution of the Nd-Fe-Co-B alloy represented by 13.3 78.5 2.8 B is rapidly cooled to obtain a ribbon, which is crushed, hot pressed, and heated by die-up setting. The raw material was a high-speed quenched Nd-Fe-Co-B permanent magnet bulk body obtained through preliminary processing.

The magnetic properties of this raw material bulk body were as follows.

A bonded magnet was manufactured in exactly the same manner as in Example 1, except for using the above raw materials, and the results of measuring the magnetic properties of each sample are also shown as Inventive Example 2.

For comparison, similar magnetic properties were measured for three samples manufactured by the conventional flow shown in FIG. 5(B), and the results are also shown in Table 1 as Comparative Example 2.

As is clear from Table 1, in Invention Example 2, Comparative Example 2
It can be seen that both Br and (B., H) have increased compared to aX.

Table 1 Example 3 The method according to the present invention was carried out according to the flow shown in FIG. 1(B).

In addition, the raw material bulk body is the same as in Example 1. The same powder as in Example 2 was used.

This powder was introduced into a vapor deposition apparatus and
The following compositions (A) to (P) were prepared in a vacuum with an average film thickness of 0,
It was deposited to a thickness of 5 μm.

(A) Nd, Dy (B) Nd Fe, Pr79Fe21 (C) N d
85Ail 15. P r 8□Aff H(D
) Nd67Fe26C7 (E) Nd e7F 628 B 7(P) D V
67'F e 28Cu 7 Powder after vapor deposition I
Heat treatment was performed at 700° C. for 1 hour in a vacuum of 10 Torr. The heat treatment at this time was carried out in the pattern shown in FIG. 4(A).

Next, these powders are introduced into the vapor deposition apparatus again, and the I
An oxidation-resistant metal (An) was deposited in a vacuum of X 10-6 Torr to an average film thickness of 0.5 μl.

The powder after vapor deposition is placed in a vacuum of I x 10' Torr.
Heat treatment was performed at 700°C for 1 hour. The heat treatment at this time was carried out in the pattern shown in FIG. 4(A).

Then, 3 vt% of epoxy resin was thoroughly mixed with these powders in a mortar, and while oriented in a magnetic field of 15 kOe, compression molding was carried out under a molding pressure of 3 ton/c.
After-cure was performed at 20°C for 2 hours.

Three bonded magnet samples were manufactured in the above manner. The magnetic properties of each of these three samples were measured,
The results are summarized as Invention Example 3 in Table 2 and Invention Example 4 in Table 3.
are shown respectively.

As is clear from Tables 2 and 3, compared to the conventional example shown in Table 1, Br, iHc, (B-H
) Significant improvements were seen in both cases, and similar to aX, improvements in Br, (B-H), and aX were also seen in the high-speed quenching type. Furthermore, it can be seen that by vapor depositing rare earth elements and alloys containing these elements, bonded magnets with high characteristics as shown in Invention Examples 1 and 2 shown in Table 1 can be obtained.

Example 4 The method according to the present invention was carried out in exactly the same manner as in Example 1 except that the heat treatment temperature was variously changed, and the magnetic properties of the obtained bonded magnets were measured. The results are shown in FIG.

As is clear from the figure, the magnetic properties are considerably dependent on the heat treatment temperature; no heat treatment effect is observed at temperatures lower than 400°C, and the effect appears at 400°C. Also, 400℃
As the temperature increases, iHc, (B-H)
Both of them increase, and (B-H) reaches its maximum at 7aX 00℃, and decreases markedly when it exceeds 900℃aX. The difference between the peak positions of iHc and (B-H)□8 is due to the decrease in the squareness of the 4π1-H loop at temperatures above 700°C. According to the above, the heat treatment effect is 400 to 900°C, preferably 600 to 800°C.
It can be seen that the expression occurs within the range of .

Example 5 The method according to the present invention was carried out in the same manner as in Example-1 except that the heat treatment time was varied, and the magnetic properties of the obtained bonded magnets were measured. The results are shown in FIG.

As is clear from the figure, if the heating time is longer than 3 hours, the magnetic properties deteriorate, and even if the heating time is shorter than 1 hour, the magnetic properties deteriorate.

Example 6 After heat-treating the classified powder prepared in Example 1 under the same conditions as in Example 1, the powder was placed in a container containing an epoxy resin with a viscosity of 20 centipoise, and transferred into a desiccator. , degassed to a vacuum degree of 1 x 1 O-2 Torr, and
After holding for 0 minutes, the remaining epoxy resin on the surface of these powders was absorbed with a hygroscopic sheet, and then heated at 120'C in vacuum.
Heat curing treatment was performed for 1 hour.

Then, 3vt% of epoxy resin was thoroughly mixed with these powders in a mortar, and compression molded at a molding pressure of 3 ton/c while oriented in a 15 kOe magnetic field.
After-cure was performed at 20°C for 2 hours.

Three bonded magnets (sample) were manufactured in the above manner.

The magnetic properties of each of these three samples were measured, and the results are shown in Table 4 as Invention Example 5.

Table 4 As is clear from Table 4, it can be seen that the same effects as in Example 1 can be obtained even when the oxidation-resistant substance is a polymer resin.

In this example, after coating with this oxidation-resistant epoxy resin, heat curing treatment was performed at 120°C for 1 hour, but even if this heat curing treatment is omitted, the same effect as shown in Table 4 can be obtained. I was able to get

(Effects of the Invention) According to the method according to the present invention detailed above, defects caused by chemical activity of the powder produced by crushing the sintered mold and high-speed quenched permanent magnet bulk material, which are the raw materials, can be eliminated during molding. This can be solved by coating with an oxidation-resistant material or a rare earth element and an oxidation-resistant material and heat treatment beforehand.

Thereby, it is possible to manufacture a bonded magnet having higher magnetic properties than conventional ones.

[Brief explanation of drawings]

Figures 1 (A) and (B) are diagrams showing the method according to the present invention in order of steps, Figures 2 and 3 are diagrams for explaining the action of the method according to the present invention, and Figure 4 (A) , (B) is a diagram showing a heat treatment pattern according to the present invention, and FIG. 5 (A). (B) is a diagram showing the flow of the conventional method, and FIGS. 6 and 7 are diagrams showing examples and results of the present invention.

Claims (4)

[Claims] (1) After pulverizing, classifying, and heat-treating a sintered or high-speed quenched permanent magnet bulk body containing rare earth elements, iron, and boron as basic components, any one of Al, Sn, Zn, In, Pb, and Ga is used. After coating with an oxidation-resistant substance consisting of a single metal, an alloy of two or more types, or a eutectic compound containing at least one of the six elements, heat-treated again, mixed with a binder, and molded in a magnetic field. A method of manufacturing a bonded magnet, characterized by: (2) After pulverizing, classifying, and heat-treating a sintered or rapidly quenched permanent magnet bulk body containing rare earth elements, iron, and boron as basic components, it is coated with an oxidation-resistant material made of resin, and then mixed with a binder. A method for producing a bonded magnet, characterized by forming the bonded magnet in a magnetic field. (3) The bonded magnet according to claim 1 or 2, wherein after the bulk material is crushed and classified, any one of the following (A) to (F) is added or coated to the classified powder. How to manufacture. (A) R(R; at least one of Nd, Pr, Dy, Ho, Tb and/or La, Ce, Sm, Er, E
u, Yb, Lu, Y), (B) R_xT_M_y (R; same as (A), T_M;
At least one or a part of Fe, Co is replaced with Si, T
i, V, Cr, Mn, Ni, Zr, Nb, Mo, Hf,
At least one of Fe and Co substituted with at least one of Ta, W, Mg, and Ca, 10<x<100, 0<y<90, x+y=100), (C) R_xM_y(R; Same as (A), M; Al, Cu, Zn, Ga, Ge, Ag, In, Sn
, Sb, Au, Bi, 20<x
<100, 0<y<80, x+y=100), (D)R_x(T_M)_yM_z(R; Same as (A), T_M; Same as (B), M; Same as (C), 10<x <100, 0<y<90, 0<z 80, x+y+z=100), (E)R_x(T_M)_y(B,C)_z(R;(A
), T_M; same as (B), 10<x<100, 0<y<90, 0<z<80, x+y+z=100), (F)R_x(T_M)_yM_z(B,C)_W( R
; Same as (A), T_M; Same as (B), M; Same as (C), 10<x<100, 0<y<90, 0<z<80, 0<w<80, x+y+z+w=100 ), (4) After crushing and classifying the bulk material, or after adding or coating any one of (A) to (F) of claim 3 to the classified powder, heat treatment is performed in a vacuum or an inert atmosphere. 4. The method of manufacturing a bonded magnet according to claim 1, wherein the method is carried out at 400 to 900°C for within 3 hours.