JPH08116633A - Bonded body of permanent magnet and member of different kind of material and bonding method - Google Patents

Abstract

PURPOSE: To increase the bonding strength between a permanent magnet and a member of a different kind of material by constituting the bonding layer of a bonded body having the bonding layer formed through a heating process for bonding the permanent magnet to the member of a rare-earth-based alloy which becomes a liquid during the heating process and controlling the average thickness of the bonding layer within a prescribed range. CONSTITUTION: A bonded body 1 has a bonding layer 4 formed through a heating process for a permanent magnet 2 to a member 3 of a different kind of material 3. The layer 4 is composed of a rare-earth-based alloy which becomes a liquid during the heating process and the average thickness t1 of the layer 4 is controlled to 1μm<=t1 2,000μm. The liquid resulting from the rare- earth-based alloy constituting the layer 4 is highly active and exerts excellent wettability against the magnet 2 and member 3. Since the liquefying temperature of the alloy can be adjusted to a relatively low level, the changes of the characteristics of the magnet 2 and member 3 can be avoided at the time of bonding the magnet 2 to the member 3 by heating. Therefore, a high bonding strength can be obtained between the magnet 2 and member 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joined body in which a permanent magnet and a dissimilar material member are joined via a joining layer, and a joining method for joining the permanent magnet and the dissimilar material member.

[0002]

2. Description of the Related Art Permanent magnets containing rare earth elements have the property that they are extremely brittle and have poor machinability, and that when exposed to high temperatures, the metal structure changes and the magnetic properties deteriorate accordingly.

Therefore, for example, in a joined body of a permanent magnet and a metal rotor of a motor, when joining them,
Conventionally, an adhesive has been used because it is not possible to adopt a joining means such as an insertion structure, screwing, and welding.

[0004]

However, when an adhesive is used, the adhesive strength of the bonded body is low due to the poor wettability of the permanent magnet, and the adhesive strength is significantly reduced with a rise in temperature. . Under such circumstances, it is impossible to meet the demand for high-speed rotation of the motor.

In view of the above, the present invention provides the above-mentioned joined body having a high joining strength between the permanent magnet and the dissimilar material member, and the joining method capable of increasing the joining strength between the permanent magnet and the dissimilar material member. With the goal.

[0006]

The present invention comprises a permanent magnet,
A dissimilar material member, and a joined body having a joining layer formed through a heating step for joining them, wherein the joining layer is made of a rare earth element-based alloy that produces a liquid phase in the heating step, and an average. Thickness t ₁ is 1 μm ≦ t ₁ ≦ 2000 μm
It is characterized by being.

According to the present invention, when joining a permanent magnet and a dissimilar material member, a joining material made of a rare earth element alloy is interposed between the permanent magnet and the dissimilar material member, and the joining material is then bonded. It is characterized in that it is heated to the liquid phase generation temperature T or higher.

[0008]

[Function] In the rare earth element-based alloy forming the bonding layer,
Since the liquid phase generated from the alloy is highly active, it exhibits excellent wettability with respect to the permanent magnet and the dissimilar material member. By setting the thickness t ₁ of the bonding layer as described above, a bonded body having high bonding strength can be provided.
In this case, since the liquid phase generation temperature of the rare earth element-based alloy can be made relatively low, it is possible to avoid characteristic changes of the permanent magnet and the dissimilar material member during heating and joining.

However, the average thickness t ₁ of the bonding layer is t ₁ <1.
At μm, cracking due to thermal stress is likely to occur in the permanent magnet, and thus the joint strength of the joined body decreases, while t ₁ > 2
At 000 μm, the bonding strength of the bonded body depends on that of the bonding layer, so that the bonding strength of the bonded body decreases as described above.

According to the above joining method, the joining strength between the permanent magnet and the dissimilar material member can be increased by using the above joining material.

[0011]

EXAMPLE Referring to FIG. 1, a bonded body 1 comprises a permanent magnet 2 and
It has a dissimilar material seed member 3 and a joining layer 4 formed through a heating process to join the members 2 and 3.

The bonding layer 4 is made of a rare earth element-based alloy that produces a liquid phase in the heating step, and has an average thickness t ₁ of 1 μm ≦ t.
₁ ≦ 2000 μm.

In the rare earth element-based alloy forming the bonding layer 4, the liquid phase generated from the alloy is highly active, and therefore exhibits excellent wettability to the permanent magnet 2 and the dissimilar material member 3. By setting the thickness t ₁ of the bonding layer 4 as described above, the bonded body 1 having high bonding strength can be provided. In this case, since the liquid phase generation temperature of the rare earth element-based alloy can be made relatively low, it is possible to avoid the characteristic changes of the permanent magnet 2 and the dissimilar material member 3 during heating and joining.

The average thickness t ₁ of the bonding layer 4 is preferably 3
0 μm ≦ t ₁ ≦ 200 μm, and when the average thickness t ₁ is set in this way, the bonding strength between the permanent magnet 2 and the dissimilar material seed member 3 becomes maximum.

The rare earth element-based alloy is basically composed of a rare earth element which is a main component and an alloy element AE which causes a eutectic reaction with the rare earth element. Rare earth elements are Y, L
a, Ce, Pr, Nd, Sm, Eu, Gd, Tb, D
It is at least one selected from y, Ho, Er, Tm, Yb and Lu. Further, the alloy element AE is Al, M
n, Fe, Co, Ni, Cu, Zn, Ga, Pd, A
It is at least one selected from g, Sn, Sb, Au, Pb, Bi, Cd and In. The alloy element AE
Content is set to 5 atomic% ≤ AE ≤ 50 atomic%.

However, if the content of the alloy element AE is AE <5
When the atomic percentage is AE> 50% by atom, the volume fraction Vf of the liquid phase in the solid-liquid coexistence state becomes low, and the bonding strength decreases. From this, it is desirable that the content of the alloy element AE is set so as to have a eutectic composition or a composition close thereto in relation to the rare earth element.

When two or more kinds of alloying elements AE are contained, the total content of them is 5 atomic% ≦ AE ≦ 50.
It becomes atomic%.

Table 1 shows examples of rare earth element type alloys.

[0019]

[Table 1] In joining the permanent magnet 2 and the dissimilar material member 3, both 2 and 3 are superposed with a thin plate-like joining material made of the rare earth alloy, and then the superposed product is placed in a vacuum heating furnace. Then, the joining material is brought into a liquid phase state or a solid-liquid coexisting state under heating, and then the furnace is cooled.

In this case, the heating temperature T varies depending on the composition of the bonding material, but the various rare earth element-based alloys having the above composition are in a liquid phase state or a solid-liquid coexisting state at a relatively low temperature, so that the permanent magnet 2 and the dissimilar material member. It does not change the characteristics of 3.

Further, the liquid phase generated from the bonding material containing a rare earth element as a main component is highly active, and for example, the permanent magnet 2 containing a rare earth element (having extremely poor wettability with respect to an adhesive or a brazing material) and Excellent wettability is exhibited for the dissimilar material member 3, for example, a steel member. By using such a bonding material, both 2 and 3 can be firmly bonded. If the heating time h is too long, the characteristics of the permanent magnet 2 and the dissimilar material member 3 are changed. Therefore, it is desirable that h ≦ 10 hours, and h ≦ 1 hour from the viewpoint of productivity improvement. is there.

[Example 1] Nd ₇₀ Cu ₃₀ having a eutectic composition of Nd having a purity of 99.9% and Cu having a purity of 99.9%
The alloy is weighed so as to obtain, then the weighed material is melted by using a vacuum melting furnace, and then, 10 mm in length, 10 mm in width,
A 50 mm long ingot was cast. This ingot is cut with a micro-cutter to produce Nd ₇₀ Cu ₃₀
Made of alloy and 10mm in length, 10mm in width, 500μ in thickness
Thus, a thin plate-like bonding material having a thickness of m was obtained. FIG. 2 shows the main part of the Cu—Nd system phase diagram, and the eutectic point is 520 ° C.

As the permanent magnet, an NdFeB system permanent magnet (length 10 mm, width 10 mm, thickness 3 mm, manufactured by Sumitomo Special Metals Co., Ltd., trade name NEOMAX-28UH) 2 was selected, and carbon steel (JIS S25C) ), And has a length of 10 mm, a width of 10 mm, and a length of 15 mm.

As shown in FIG. 3, one joining material 5 is provided on one short column body 3, and a permanent magnet 2 is provided on the joining material 5.
Further, another bonding material 5 is further laid on the permanent magnet 2, and another short column body 3 is further laid on the bonding material 5, respectively, to produce a stacked product, and a total of 20 pieces are manufactured by the same procedure. A stack was made. Next, these superposed products were placed in a vacuum heating furnace, and a heating step of heating temperature T = 530 ° C. and a heating time h = 0.5 hour, followed by a joining process consisting of furnace cooling was performed, and as shown in FIG. As shown, 20 joined bodies 1 were obtained by joining the permanent magnets 2 with two short column bodies 3 via a joining layer 4 formed of a joining material 5 so as to sandwich them. In this joining process, the heating temperature T is T =
Since it is 530 ° C. and exceeds the eutectic point 520 ° C. shown in FIG. 2, since the bonding material 5 has a eutectic composition, it is in a liquid phase state. In this case, the average thickness t ₁ of the bonding layer 4 is t ₁ =
It was 200 μm.

For comparison, a permanent magnet 2 similar to the above and two short columnar bodies 3 similar to the above are superposed with an epoxy resin adhesive (manufactured by Nippon Ciba-Gaigi Co., Ltd., trade name Araldite) on top of each other. Create a thing and follow the same procedure for a total of 2
0 stacks were made. Next, these superposed products are placed in a drying furnace, and a heating step of heating the temperature of 200 ° C. for a heating time of 60 minutes, followed by a joining process consisting of furnace cooling is performed, and the two short columns 3 and the permanent magnets 2 are joined. Twenty bonded bodies similar to the above were obtained by bonding and via an epoxy resin adhesive.

A tensile test specimen A was prepared from each joint 1 using the joint material 5, and a similar tensile test specimen B was prepared from each joint using an epoxy resin adhesive. Then, a tensile test is performed at room temperature on each of the 10 test pieces A and B, and the remaining 10 test pieces A and B
Was subjected to a tensile test under heating at 150 ° C., the results shown in Table 2 were obtained.

[0027]

[Table 2] As is clear from Table 2, the test piece A using the bonding material 5
At room temperature and under heating at 150 ° C., the bonding strength is higher than that of the test piece B using the epoxy resin adhesive, and the bonding strength is almost the same under both environments, and its variation is small. The test piece B has a low bonding strength at room temperature and has a large variation, and is 150 ° C.
Under heating, its bonding strength is reduced to one-third of that at room temperature.

FIG. 5 shows the relationship between the heating temperature T and Hk in the NdFeB system permanent magnet 2. Here, the Hk means a magnetic field H when the residual magnetic flux density Br is lowered by 10%, which is a measure to become the value of the coercive force _I H _C (intensity I = 0 magnetization). As is clear from FIG. 5, the heating temperature T during the joining process
Becomes T> 650 ° C, Hk, and therefore coercive force _I H
_C tends to decrease. However, the residual magnetic flux density Br and the coercive force _B H _C (magnetic flux density B = 0) are almost unchanged, and therefore the maximum magnetic energy product (BH) m as shown in FIG.
ax is substantially constant. In the joining process using the joining material 5, the heating temperature T is T = 530 ° C. and T ≦ 6.
Since the temperature is 50 ° C., the magnetic characteristics of the permanent magnet 2 are not changed.

The poor wettability of the permanent magnet 2 is due to the presence of a phase having a high rare earth element concentration, that is, a high Nd concentration in this embodiment, at its crystal grain boundaries. The bonding material 5
In the joining process using, the joining material 5 is in a liquid phase state, and the liquid phase generated from the Nd ₇₀ Cu ₃₀ alloy containing Nd as a main component is highly active and Nd existing in the grain boundaries. Since the main component is common to the high-concentration phase, it exhibits excellent wettability with respect to the permanent magnet 2 and, due to the high activation, the wettability with respect to the short columns 3 made of carbon steel is also very good. .

Therefore, by using the bonding material 5 as described above, the permanent magnet 2 and the short column 3 can be firmly bonded without deteriorating the magnetic characteristics of the permanent magnet 2. This joining technique is applied to joining a permanent magnet to a rotor for a motor and makes it possible to realize a high-speed rotation motor having a rotation speed of 10,000 rpm or more.

Example 2 Nd ₆₀ Cu having a purity of 99.9% and Cu having a purity of 99.9% were converted into Nd ₆₀ Cu having a hypoeutectic composition.
₄₀ alloy is weighed to obtain, then the weighed material is melted using a vacuum melting furnace, and then 10 mm in length and 10 m in width.
An ingot of m and 50 mm in length was cast. This ingot is cut with a micro-cutter and Nd ₆₀ C
Made of u ₄₀ alloy, length 10 mm, width 10 mm, thickness 50
A thin plate-like bonding material 5 having a thickness of 0 μm was obtained.

As the permanent magnet, an NdFeB system permanent magnet (product name: NEOMAX-28UH, manufactured by Sumitomo Special Metals Co., Ltd.) 2 having a length of 10 mm, a width of 10 mm, and a thickness of 5 mm was selected. A 1.0 mm thick silicon steel plate (JIS MES-3F) was layered on it and tightened with bolts 7 and nuts, 10 mm long, 10 mm wide, 15 length long.
A laminate 3 of mm was selected.

Using the laminate 3, the bonding material 5 and the permanent magnet 2, a total of 20 stacks were produced in the same manner as in Example 1 as shown in FIG. Installed in a vacuum heating furnace, heating temperature T = 560
C., a heating process of heating time h = 0.5 hours, and then a joining process of furnace cooling is performed to form the two and 3 from the joining material 5 so as to sandwich the permanent magnet 2 between the two laminated bodies 3. 20 joined bodies 1 joined through the joining layer 4 were obtained (see FIG. 4). In this bonding treatment, the heating temperature T is T = 560 ° C., which exists in the temperature range between the eutectic point 520 ° C. and the liquidus line a shown in FIG. Become. In this case, the average thickness t ₁ of the bonding layer 4 was 200 μm.

Tensile test specimens A were produced from each of the bonded bodies 1, and then ten tensile specimens A were subjected to a tensile test at room temperature, and the remaining ten specimens A were each tested at 150 ° C. When a tensile test was performed under heating, Table 3
Was obtained. For comparison, Table 3 also shows measured values for the test piece B of Example 1.

[0035]

[Table 3] As is clear from Table 3, the test piece A using the bonding material 5
At room temperature and under heating at 150 ° C., the bonding strength is higher than that of the test piece B using the epoxy resin adhesive, and the bonding strength does not change at all under both environments, and its variation is small.

In the joining process, since the heating temperature T is T = 560 ° C. and T ≦ 650 ° C., the magnetic characteristics of the permanent magnet 2 are not changed.

Moreover, in the joining process, the joining material 5 is in a solid-liquid coexisting state, and the liquid phase produced from the Nd ₆₀ Cu ₄₀ alloy containing Nd as a main component is highly active and the permanent magnet 2 Exhibits a high wettability with respect to the permanent magnet 2 by sharing the main component with the phase having a high Nd concentration existing in the crystal grain boundary, and wets the laminate 3 made of a silicon steel sheet due to the high activation. The property is also very good.

Therefore, by using the bonding material 5 as described above, the permanent magnet 2 and the laminated body 3 can be firmly bonded without impairing the magnetic characteristics of the permanent magnet 2.

In joining the permanent magnet 2 and the dissimilar material member 3, from the viewpoint of improving the joining strength, the above-mentioned Examples 1 and 2 are used.
As described above, it is desirable to match the rare earth element contained in the permanent magnet 2 with the rare earth element which is the main component of the bonding material 5. For example, when joining the permanent magnet 2 containing Sm, the bonding containing Sm as the main component. Even if the bonding material 5 containing La, Ce, Nd, Pr or the like as a main component is used in addition to the material, the bonding strength substantially equal to those in the first and second embodiments can be obtained.

[Example 3] Nd ₇₀ Cu ₃₀ having a eutectic composition of Nd having a purity of 99.9% and Cu having a purity of 99.9%
The alloy is weighed so as to obtain, then the weighed material is melted by using a vacuum melting furnace, and then, 10 mm in length, 10 mm in width,
A 50 mm long ingot was cast. This ingot is cut with a micro-cutter to produce Nd ₇₀ Cu ₃₀
Various thin plate-like bonding materials 5 made of an alloy and having different lengths of 10 mm in length and 10 mm in width were obtained.

As a permanent magnet, an NdFeB system permanent magnet 2 (made by Sumitomo Special Metals Co., Ltd.) having a length of 10 mm, a width of 10 mm, and a thickness of 3 mm is used.
Product name NEOMAX-28UH) is selected, and rolled steel plates with a thickness of 1.0 mm are laminated as bolts 7
Also, a laminated body 3 having a length of 10 mm, a width of 10 mm, and a length of 15 mm, tightened with nuts 8, was selected.

Using the laminate 3, the bonding material 5 and the permanent magnet 2, a plurality of superposed products are produced in the same manner as in Example 1 as shown in FIG. 7, and then these superposed products are heated in vacuum. It is installed in a furnace, a heating step of heating temperature T = 530 ° C. and a heating time h = 0.5 hour, followed by a joining process consisting of furnace cooling is performed, and as in the second embodiment, the two laminated bodies 3 are permanently bonded together. A plurality of bonded bodies 1 in which the magnets 2 are sandwiched by a bonding layer 4 formed of a bonding material 5 so as to sandwich the magnet 2.
Was obtained (see FIG. 4).

Specimens for tensile test were prepared from each bonded body 1 and subjected to a tensile test under heating at 150 ° C., and the results shown in Table 4 were obtained.

[0044]

[Table 4] FIG. 8 is a graph of Table 4, and points (1) to
(11) corresponds to Examples 1 to 11 of the joined body 1, respectively.

In this kind of bonded body 1, the tensile strength σ _B ≧
2kgf / mm ² is required, and to meet this requirement,
As is clear from Table 4 and FIG. 8, if the thickness t ₂ of the bonding material 5 is set to 30 μm ≦ t ₂ ≦ 2500 μm and the average thickness t ₁ of the bonding layer 4 is set to ₁ μm ≦ t ₁ ≦ 2000 μm. Good. Preferably, the thickness t ₂ of the bonding material 5 is 150 μm ≦
t ₂ ≦ 500 μm and the average thickness t ₁ of the bonding layer 4
Is 30 μm ≦ t ₁ ≦ 200 μm.

FIG. 9 shows a joint portion in Example 6 of the joint body 1, (a) is a micrograph showing the metal structure of the joint portion, and (b) is a schematic drawing of (a). From FIG. 9, it can be seen that the permanent magnet 2 and each rolled steel plate are joined together via the joining layer.

[0047]

EFFECTS OF THE INVENTION According to the present invention, with the above-described structure, it is possible to provide a bonded body having a high bonding strength between the permanent magnet and the dissimilar material type member.

Further, according to the present invention, it is possible to provide a joining method capable of increasing the joining strength between the permanent magnet and the dissimilar material seed member by using the above means.

[Brief description of drawings]

FIG. 1 is a perspective view of a joined body.

FIG. 2 shows a main part of a Cu—Nd system phase diagram.

FIG. 3 is a perspective view showing a superposed relationship of a permanent magnet, a bonding material, and a short column body.

FIG. 4 is a perspective view of a joined body.

FIG. 5 is a graph showing the relationship between heating temperature T and Hk.

FIG. 6 is a graph showing the relationship between heating temperature T and (BH) max.

FIG. 7 is a perspective view showing a superposing relationship of a permanent magnet, a bonding material, and a laminated body.

FIG. 8 is a graph showing the relationship between the average thickness t ₁ of the bonding layer and the tensile strength σ _B.

9A is a micrograph showing a metallographic structure of a joint portion, and FIG. 9B is a schematic diagram of FIG. 9A.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bonded body 2 Permanent magnet 3 Short column body, laminated body (dissimilar material member) 4 Bonding layer 5 Bonding material

Claims (11)

[Claims] 1. A permanent magnet (2) and a dissimilar material member (3).
And a bonding layer (4) formed through a heating step to bond them (2, 3),
The bonding layer (4) is made of a rare earth element-based alloy that produces a liquid phase in the heating step, and has an average thickness t ₁ of 1 μm ≦ t.
_1. A bonded body of a permanent magnet and a dissimilar material member, wherein ₁ ≦ 2000 μm. 2. The average thickness t ₁ of the bonding layer (4) is 30.
The joined body of the permanent magnet and the dissimilar material member according to claim 1, wherein μm ≦ t ₁ ≦ 200 μm. 3. The rare earth element-based alloy is an alloy element AE.
As Al, Mn, Fe, Co, Ni, Cu, Zn, G
a, Pd, Ag, Sn, Sb, Au, Pb, Bi, Cd
And at least one selected from In and 5 atomic% ≦
The bonded body of the permanent magnet according to claim 1 or 2, and the dissimilar material member, containing AE ≦ 50 atomic%. 4. The bonded body of a permanent magnet and a dissimilar material member according to claim 1, wherein the permanent magnet (2) is a permanent magnet containing a rare earth element. 5. The bonded body of a permanent magnet and a dissimilar material member according to claim 4, wherein the permanent magnet (2) is an NdFeB-based permanent magnet. 6. A joining material made of a rare earth element-based alloy between the permanent magnet (2) and the different material seed member (3) when joining the permanent magnet (2) and the different material seed member (3). A method of joining a permanent magnet and a dissimilar material member, characterized in that (5) is interposed, and then the joining material (5) is heated to a liquidus generation temperature T or higher thereof. 7. The thickness t ₂ of the bonding material (5) is 10 μm.
The method for joining the permanent magnet and the dissimilar material member according to claim 6, wherein ≦ t ₂ ≦ 2500 μm. 8. The thickness t ₂ of the bonding material (5) is 150 μm.
The method for joining a permanent magnet and a dissimilar material member according to claim 6, wherein m ≦ t ₂ ≦ 500 μm. 9. The rare earth element-based alloy is an alloy element AE.
As Al, Mn, Fe, Co, Ni, Cu, Zn, G
a, Pd, Ag, Sn, Sb, Au, Pb, Bi, Cd
And at least one selected from In and 5 atomic% ≦
The method for joining a permanent magnet and a dissimilar material member according to claim 6, 7 or 8 containing AE ≦ 50 atomic%. 10. The method for joining a permanent magnet and a dissimilar material member according to claim 6, 7, 8 or 9, wherein the permanent magnet (2) is a permanent magnet containing a rare earth element. 11. The permanent magnet (2) is an NdFeB-based permanent magnet, and the bonding material (5) has a liquidus generation temperature T thereof.
The method for joining a permanent magnet and a dissimilar material member according to claim 10, wherein T ≦ 650 ° C.