JP2003275851A - Cooling roll, strip-like magnet material, magnet powder and bond magnet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling roll, a strip-like magnet material, magnet powder and a bond magnet with which the magnet excellent in the magnetic characteristic and the reliability can be provided. <P>SOLUTION: A rapidly cooled strip producing apparatus 1 is provided with a cylindrical body 2, a coil 4 for heating and the cooling roll 5. At the lower end part of the cylindrical body 2, a nozzle 3 for injecting molten metal 6 of the magnet material is formed. On the peripheral surface 53 of the cooling roll 5, and dimple correcting means is arranged. The rapidly cooled strip 8 is produced by injecting the molten metal 6 from the nozzle 3 into inert gas (atmospheric gas) such as helium gas, and colliding to the peripheral surface 53 of the cooling roll 5, cooling and solidifying. In this case, the dimple generated on the contacting surface with the peripheral surface 53 is divided by arranging the dimple correcting means on the peripheral surface 53 of the cooling roll 5, and the generation of the big dimple is prevented. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling roll, a ribbon-shaped magnet material, magnet powder and a bonded magnet.

[0002]

2. Description of the Related Art As a magnet material, a rare earth magnet material composed of an alloy containing a rare earth element has high magnetic properties and therefore exhibits high performance when used in a motor or the like.

Such a magnetic material is manufactured by a quenching method using a quenching ribbon manufacturing apparatus, for example. Hereinafter, this manufacturing method will be described.

FIG. 23 is a cross-sectional side view showing a state in the vicinity of a portion where molten metal collides with a cooling roll in a conventional apparatus for manufacturing a magnet material by a single roll method (quenching ribbon manufacturing apparatus).

As shown in the figure, a magnet material having a predetermined alloy composition (hereinafter referred to as "alloy") is melted and its molten metal 60 is injected from a nozzle (not shown), and the direction of arrow A in FIG. Peripheral surface 53 of the cooling roll 500 rotating at
The alloy is rapidly cooled and solidified by colliding with the outer peripheral surface 530 and colliding with the peripheral surface 530 to continuously form a ribbon-shaped (ribbon-shaped) alloy. This ribbon-shaped alloy is called a quenched ribbon, and as a result of being solidified at a high cooling rate, its microstructure is a structure composed of an amorphous phase or a fine crystalline phase,
Excellent magnetic properties are exhibited as it is or by heat treatment. In FIG. 23, the solidification interface 710 of the molten metal 60 is shown by a dotted line.

Here, the rare earth element is easily oxidized, and if it is oxidized, the magnetic characteristics are deteriorated.
Was mainly produced in an inert gas.

Therefore, gas invades between the peripheral surface 530 and the paddle (hot pool) 70 of the molten metal 60, and the quenching ribbon 80 is formed.
The roll surface (the surface contacting the peripheral surface 530 of the cooling roll 500) 810 of No. 3 may have dimples (recesses) 9. This tendency becomes more remarkable as the peripheral speed of the cooling roll 500 increases, and the area of the dimples generated also increases.

When the dimples 9 (especially, huge dimples) are generated, poor contact with the peripheral surface 530 of the cooling roll 500 occurs at the dimple portion due to the interposition of gas, the cooling rate is lowered, and rapid solidification occurs. Disturbed.
Therefore, the crystal grain size of the alloy is coarsened at the portion where the dimple 9 is generated, and the magnetic characteristics are deteriorated.

The magnetic powder obtained by crushing a quenched ribbon including such a portion having low magnetic characteristics has a large variation in magnetic characteristics. Therefore, a bonded magnet manufactured using such a magnet powder has low magnetic properties and also has low corrosion resistance.

[0010]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a cooling roll, a ribbon-shaped magnet material, a magnet powder and a bonded magnet, which can provide a magnet having excellent magnetic characteristics and excellent reliability. is there.

[0011]

The above objects are achieved by the present invention described in (1) to (27) below.

(1) A cooling roll for producing a ribbon-shaped magnetic material by colliding a molten metal of the magnetic material with its peripheral surface and cooling and solidifying the molten metal. The cooling roll comprises a roll base material and the roll base. A surface layer provided on the outer periphery of the material, wherein the surface layer is made of ceramics, and a contact surface of the ribbon-shaped magnet material with a cooling roll on the peripheral surface of the surface layer. A cooling roll having a dimple straightening means for dividing the dimples generated in 1.

(2) A cooling roll for producing a ribbon-shaped magnetic material by colliding a molten metal of the magnetic material with its peripheral surface and cooling and solidifying the molten metal. The cooling roll comprises a roll base material and the roll base. A surface layer provided on the outer periphery of the material, and the surface layer has a coefficient of thermal expansion of 3.5 to 18 [x] near room temperature.
10 ^-6 K ^-1 ], and divides the dimples generated on the peripheral surface of the surface layer on the contact surface of the ribbon-shaped magnet material with the cooling roll. A cooling roll characterized by having.

(3) The cooling roll according to (2), wherein the surface layer is made of ceramics.

(4) Any one of the above (1) to (3), wherein the surface layer is made of a material having a thermal conductivity lower than that of the constituent material of the roll base material at around room temperature. Cooling roll described in Crab.

(5) The surface layer is made of a material having a thermal conductivity of 80 W · m ⁻¹ · K ⁻¹ or less near room temperature, as described in any one of (1) to (4) above. Cooling roll.

(6) The average thickness of the surface layer is 0.5
The cooling roll according to any one of (1) to (5) above, which has a thickness of 50 μm.

(7) The cooling roll according to any one of (1) to (6) above, wherein the surface layer is formed without machining the surface thereof.

(8) The cooling roll according to any one of (1) to (7), wherein the dimple correcting means is at least one ridge or groove.

(9) The average width of the ridges is 0.5 to 9
The cooling roll according to (8) above, which has a thickness of 5 μm.

(10) The average width of the groove is 0.5 to 9
The cooling roll according to (8) or (9), which has a thickness of 0 μm.

(11) The cooling roll according to any one of (8) to (10), wherein the convex strips have an average height or the grooves have an average depth of 0.5 to 20 μm.

(12) The cooling roll according to any one of the above (8) to (11), wherein the ridges or grooves are juxtaposed and the average pitch is 0.5 to 100 μm.

(13) The cooling roll according to any one of the above (8) to (12), wherein the projected area occupied by the ridges or grooves on the peripheral surface is 10% or more.

(14) A ribbon-shaped magnetic material obtained by colliding a molten metal of a magnetic material with the peripheral surface of a cooling roll and cooling and solidifying the molten metal, wherein grooves or ridges are formed on the contact surface with the cooling roll. A thin strip magnet material, characterized in that the dimples are divided by the grooves or the ridges.

(15) A ribbon-shaped magnet material produced by using the cooling roll according to any one of (1) to (13) above.

(16) The thin film according to (14) or (15), wherein the ratio of the area occupied by the huge dimples having a size of 2000 μm ² or more formed at the time of solidification to the contact surface with the cooling roll is 10% or less. Strip magnet material.

(17) The contact surface with the cooling roll is
The thin strip magnet material according to any one of (14) to (16), wherein at least a part of the surface shape of the cooling roll is transferred.

(18) A groove or a ridge is formed on the contact surface with the cooling roll, and the dimple is divided by the groove or the ridge.
The ribbon-shaped magnet material according to any one of 7).

(19) The ribbon magnet material according to any one of (14) to (18), which has an average thickness of 8 to 50 μm.

(20) A magnet powder obtained by pulverizing the ribbon-shaped magnet material according to any one of (14) to (19).

(21) The magnet powder as described in the above (20), wherein the magnet powder is heat-treated at least once after the manufacturing process.

(22) The magnetic powder as described in (20) or (21) above, which has an average particle size of 1 to 300 μm.

(23) The magnetic powder according to any one of the above (20) to (22), wherein the magnetic powder has a composite structure having a soft magnetic phase and a hard magnetic phase.

(24) The average crystal grain size of each of the hard magnetic phase and the soft magnetic phase is 1 to 100 nm.
The magnetic powder according to (23) above, which is

(25) A bonded magnet comprising the magnet powder according to any one of (20) to (24) bonded with a binder resin.

(26) The intrinsic coercive force H _cJ at room temperature is 32.
The bonded magnet as described in (25) above, which has 0 to 1200 kA / m.

(27) Maximum magnetic energy product (BH)
(25) or (2) where _max is 40 kJ / m ³ or more
The bonded magnet according to 6).

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the cooling roll, ribbon-shaped magnet material, magnet powder and bonded magnet of the present invention will be described in detail below.

[Structure of quenching ribbon manufacturing apparatus] FIG. 1 shows a first embodiment of a cooling roll of the present invention and a single roll method for manufacturing a ribbon magnet material (quenching ribbon) using the cooling roll. FIG. 2 is a front view of the cooling roll shown in FIG. 1, and FIG. 3 is a perspective view showing a configuration example of an apparatus (quenching ribbon manufacturing apparatus).
It is an expanded sectional view of the cooling roll shown in FIG.

As shown in these drawings, the quenching ribbon manufacturing apparatus 1 comprises a cylindrical body 2 capable of accommodating a magnet material, and a cooling roll 5 which rotates relative to the cylindrical body 2 in the direction of arrow A in the drawing. ing. A nozzle (orifice) 3 for injecting a molten metal 6 of magnet material is formed at the lower end of the cylindrical body 2.

Examples of the constituent material of the cylindrical body 2 include heat resistant ceramics such as quartz, alumina and magnesia.

Examples of the opening shape of the nozzle 3 include a circle, an ellipse, and a slit shape.

Further, on the outer periphery of the cylindrical body 2 in the vicinity of the nozzle 3,
A heating coil 4 is arranged, and by applying, for example, a high frequency to the coil 4, the inside of the cylinder 2 is heated (induction heating), and the magnet material in the cylinder 2 is melted.

The heating means is not limited to the coil 4 as described above, but a carbon heater, for example, may be used.

The cooling roll 5 is composed of a roll base material 51 and a surface layer 52 forming a peripheral surface 53 of the cooling roll 5.

The surface layer 52 may be made of the same material as the roll base material 51, but is preferably made of a material having a lower thermal conductivity than the constituent material of the roll base material 51.

The constituent material of the roll base material 51 is not particularly limited, but is composed of a metal material having a high thermal conductivity such as copper or a copper alloy so that the heat of the surface layer 52 can be dissipated more quickly. Is preferred.

The thermal conductivity of the constituent material of the surface layer 52 near room temperature is not particularly limited, but is, for example, 80 W · m.
⁻¹ · K ⁻¹ or less is preferable and 3 to 60 W · m ⁻¹ ·
K ⁻¹ is more preferable, and 5 to 40 W · m ⁻¹ · K ⁻¹
Is more preferable.

Since the cooling roll 5 is composed of the surface layer 52 having such thermal conductivity and the roll base material 51, the molten metal 6 can be rapidly cooled at an appropriate cooling rate. Further, the difference in cooling speed between the vicinity of the roll surface 81 (the surface on the side in contact with the peripheral surface of the cooling roll) and the vicinity of the free surface 82 (the surface on the side opposite to the roll surface) becomes small. Therefore, the obtained quenched ribbon 8 has a small variation in the crystal grain size at each site and has excellent magnetic properties.

Examples of materials having such thermal conductivity include Zr, Sb, Ti, Ta, Pd, Pt, and the like.
Alternatively, a metal material such as an alloy containing these, an oxide thereof, a ceramics, or the like can be given. Examples of ceramics include Al ₂ O ₃ , SiO ₂ , TiO ₂ , Ti ₂ O ₃ ,
Oxide ceramics such as ZrO ₂ , Y ₂ O ₃ , barium titanate, and strontium titanate, AlN, Si
₃ N ₄ , TiN, BN, ZrN, HfN, VN, TaN,
Nitride ceramics such as NbN, CrN, Cr ₂ N,
Graphite, SiC, ZrC, Al ₄ C ₃ , CaC ₂ ,
Examples thereof include carbide-based ceramics such as WC, TiC, HfC, VC, TaC, and NbC, or composite ceramics in which two or more of these are arbitrarily combined. Among these, it is particularly preferable that the material contains nitride ceramics.

Further, such ceramics have higher hardness and durability (wear resistance) than those conventionally used as materials for forming the peripheral surface of the cooling roll (Cu, Cr, etc.). Is excellent. Therefore, the cooling roll 5
Even after repeated use, the shape of the peripheral surface 53 is maintained, and the effect of the dimple correcting means described later does not easily deteriorate.

Incidentally, the constituent material of the roll base material 51 usually has a relatively high coefficient of thermal expansion. Therefore, the thermal expansion coefficient of the constituent material of the surface layer 52 is preferably a value close to the thermal expansion coefficient of the roll base material 51. Surface layer 5
Thermal expansion coefficient (linear expansion coefficient α) of the 2 constituent materials near room temperature
Is, for example, preferably about 3.5 to 18 [× 10 ^-6 K ^-1 ], and more preferably about ^{6 to} 12 [× 10 ^-6 K ^-1 ]. When the coefficient of thermal expansion of the constituent material of the surface layer 52 near room temperature (hereinafter, also simply referred to as “coefficient of thermal expansion”) is within such a range, the roll base material 51 and the surface layer 5
It is possible to maintain high adhesiveness with No. 2 and to more effectively prevent peeling of the surface layer 52.

The surface layer 52 is not limited to a single layer, but may be a laminate of a plurality of layers having different compositions. For example, the surface layer 52 may be a layer in which two or more layers made of the above-mentioned metal material, ceramics or the like are laminated. As such a surface layer 52, for example, a surface layer formed of a two-layer laminated body in which a metal layer (base layer) / ceramic layer is laminated from the roll base material 51 side can be cited. In the case of such a laminate, it is preferable that the adjacent layers have high adhesiveness, and examples thereof include those in which the adjacent layers contain the same element.

Further, when the surface layer 52 is a laminate of a plurality of layers, it is preferable that at least the outermost layer thereof is made of a material having a thermal conductivity in the above-mentioned range.

Further, even when the surface layer 52 is composed of a single layer, the composition is not limited to a uniform one in the thickness direction, but for example, a composition in which the contained components sequentially change in the thickness direction (gradient material ) May be sufficient.

The average thickness of the surface layer 52 (total thickness in the case of the above-mentioned laminated body) is not particularly limited, but is 0.5-5.
The thickness is preferably 0 μm, more preferably 1 to 20 μm.

If the average thickness of the surface layer 52 is less than the lower limit value, the following problems may occur. That is, depending on the material of the surface layer 52, the cooling ability is too large, and even the quenching ribbon 8 having a considerably large thickness has a large cooling rate near the roll surface 81 and is likely to become amorphous. On the other hand, in the vicinity of the free surface 82, the thermal conductivity of the quenched ribbon 8 is relatively small, so that the greater the thickness of the quenched ribbon 8, the smaller the cooling rate, and as a result, the coarsening of the crystal grain size easily occurs. That is, a quenched ribbon, such as coarse grains near the free surface 82 and amorphous near the roll surface 81, is likely to be formed, and satisfactory magnetic characteristics may not be obtained in some cases. Also, the free surface 82
In order to reduce the crystal grain size in the vicinity, for example, even if the peripheral speed of the cooling roll 5 is increased and the thickness of the quenched ribbon 8 is decreased, the amorphous material near the roll surface 81 becomes more random. In some cases, even if heat treatment is performed after forming the quenched ribbon 8, sufficient magnetic characteristics may not be obtained.

When the average thickness of the surface layer 52 exceeds the upper limit value, the quenching rate is slow and the crystal grain size becomes coarse,
As a result, the magnetic properties may deteriorate.

The method for forming the surface layer 52 is not particularly limited, but chemical vapor deposition (CVD) such as thermal CVD, plasma CVD, laser CVD or physical vapor deposition (PVD) such as vacuum vapor deposition, sputtering, ion plating.
Is preferred. When these methods are used, the thickness of the surface layer can be made relatively easy, so that the surface does not need to be machined after the surface layer 52 is formed. The surface layer 52 may be formed by other methods such as electrolytic plating, immersion plating, electroless plating, and thermal spraying. Among these, when the surface layer 52 is formed by thermal spraying, the adhesiveness (adhesive strength) between the roll base material 51 and the surface layer 52 becomes particularly excellent.

Prior to forming the surface layer 52 on the outer periphery of the roll base material 51, the outer surface of the roll base material 51 is subjected to cleaning treatment such as alkali cleaning, acid cleaning, organic solvent cleaning or the like, or a blasting treatment. A base treatment such as etching, formation of a plating layer or the like may be performed. Thereby, the adhesiveness between the roll base material 51 and the surface layer 52 after the surface layer 52 is formed is improved. Further, since the uniform and dense surface layer 52 can be formed by performing the above-described base treatment, the obtained cooling roll 5 has a particularly small variation in the thermal conductivity in each part.

[Dimple Correcting Means] As will be described later,
The quenched ribbon 8 is manufactured by causing the molten metal 6 of the magnetic material to collide with the peripheral surface 53 of the cooling roll 5 and quenching. At this time, gas may enter between the peripheral surface 53 and the paddle (melt pool) 7 of the molten metal 6 to cause dimples on the roll surface 81. As shown in FIG. 4, the portion where the gas has entered is cooled in the state where the gas is accumulated, so that dimples 9 are generated on the roll surface 81 of the obtained quenched ribbon 8 (see FIG. 6). ). In addition, the cooling rate of the gas infiltrated portion becomes smaller than that of other portions of the paddle 7, and the crystal grain size becomes coarse. As a result, there are large variations in the crystal grain size and magnetic characteristics in the respective portions of the quenched ribbon 8. Such a tendency becomes more remarkable as the area per dimple 9 and the total area of the dimples 9 increase.

On the other hand, the peripheral surface 53 of the cooling roll 5 of the present invention is provided with dimple correcting means for dividing the dimples 9 generated on the roll surface 81 of the quenched ribbon 8.

As a result, as shown in FIGS. 5 and 7, the dimple 9 is divided by the groove 84. Further, due to the degassing effect described later, at least a part of the gas that has entered between the peripheral surface 53 and the paddle 7 is discharged, and the amount of gas remaining between the peripheral surface 53 and the paddle 7 decreases. . For these reasons, the area of each dimple 9 formed on the roll surface 81 of the obtained quenched ribbon 8 becomes small, and the total area of the dimple 9 also decreases (FIG. 7).
reference). Therefore, the variation of the cooling rate in each part of the paddle 7 becomes small, and as a result, the quenching ribbon 8 having the small variation of the crystal grain size and excellent magnetic characteristics can be obtained.

In the illustrated structure, as a dimple correcting means, a groove 54 is formed on the peripheral surface 53 of the cooling roll 5 substantially parallel to the rotation direction of the cooling roll. (At this time, the ridges 55 are formed between the adjacent grooves 54 and 54. Conversely, between the adjacent ridges 55 and the adjacent ridges 55,
It can also be regarded as a groove 54. In this way, since the groove and the ridge have an opposing relationship,
Unless otherwise specified, a groove will be representatively described as a dimple correcting means. )

Since the groove 54 is provided on the peripheral surface 53, the gas that has entered between the peripheral surface 53 and the paddle 7 is
After entering the groove 54, it is possible to move further along the groove 54. Therefore, the gas that has entered between the peripheral surface 53 and the paddle 7 is discharged to the outside through the groove 54 as the cooling roll 5 rotates. Due to such an effect (gas releasing effect), the peripheral surface 5 at the portion where the gas enters
3 and the paddle 7 are likely to come into contact with each other. When the contact between the peripheral surface 53 and the paddle 7 occurs in this way, the dimples 9 are divided and the area of each dimple is reduced, as shown in FIG. Moreover, since the amount of gas remaining between the peripheral surface 53 and the paddle 7 is reduced, the total area of the dimples 9 formed is also reduced. Therefore, the variation of the cooling rate in each part of the paddle 7 becomes small, and as a result, the quenched ribbon 8 having the small variation of the crystal grain size and excellent magnetic characteristics can be obtained.

In the illustrated configuration, the groove 54 and the ridge 55
Are formed in plural, but at least one may be formed.

The average value of the width L ₁ of the groove 54 (width at the portion open to the peripheral surface 53) L ₁ is preferably 0.5 to 90 μm, more preferably _{1 to} 50 μm. Groove 5
If the average value of the width L ₁ of 4 is less than the lower limit value, the degassing effect of discharging the gas that has entered between the peripheral surface 53 and the paddle 7 is reduced, and the effect as dimple correcting means is not sufficiently exerted. There are cases. On the other hand, when the average value of the width L ₁ of the groove 54 exceeds the upper limit value, dimples having a large area are generated in the groove 54, and the crystal grains may become coarse.

Width of convex ridge 55 (maximum width) L₂The average value of
0.5 to 95 μm is preferable, and 1 to 50 μm
It is more preferable. Width L of ridge 55₂The average value of
If it is less than the limit value, the convex stripes are used as a dimple correcting means.
Does not work well, resulting in a large
Pulls may form. On the other hand, the width L of the ridge 55 ₂
If the average value of exceeds the upper limit, the surface area of the ridges will increase.
When a dimple is formed between the ridge and the paddle
There is.

The average value of the maximum depth L (or the maximum height of the ridge 55) L ₃ of the groove 54 is preferably 0.5 to 20 μm, more preferably 1 to 10 μm. Groove 54
If the average value of the depth L ₃ is less than the lower limit value, the degassing effect of discharging the gas that has entered between the peripheral surface 53 and the paddle 7 is reduced, and the effect as the dimple correcting means is not sufficiently exerted. There are cases. On the other hand, when the average value of the depth L ₃ of the groove 54 exceeds the upper limit value, the flow velocity of the gas flow flowing in the groove 54 increases, and a turbulent flow accompanied by vortices easily occurs, so that the effect as the dimple correcting means becomes sufficient. It may not be demonstrated.

The pitch L ₄ of the grooves 54 (or the protrusions 55) arranged in parallel is the size of each dimple 9 formed on the roll surface 81 or the total area of the dimples 9. Is an important requirement that defines The average value of the pitch L ₄ of the grooves 54 (or the protruding ridges 55 arranged in parallel) is preferably 0.5 to 100 μm, more preferably 3 to 50 μm. If the average value of the pitch L ₄ of the groove 54 is within such a range, the groove 5
4 (or the ridge 55) sufficiently functions as a dimple correcting means, and the distance between the contact portion and the non-contact portion with the paddle 7 is sufficiently reduced. As a result, the difference in cooling rate between the portion that is in contact with the peripheral surface 53 and the portion that is not in contact with the peripheral surface 53 is sufficiently small, and variations in the crystal grain size and magnetic characteristics of the obtained quenched ribbon 8 are small.

Groove 54 (or ridge 5 on peripheral surface 53)
The ratio of the projected area (area when projected onto the peripheral surface) occupied by 5) is preferably 10% or more, and 30 to 99.
It is more preferably 5%. Groove 5 on peripheral surface 53
4 (or ridge 55) occupies 10% of the projected area
If it is less than the above, a sufficient flow path for degassing cannot be secured for the amount of gas caught between the peripheral surface 53 and the paddle 7, and the gas remains between the peripheral surface 53 and the paddle 7. As a result, it becomes easy to form huge dimples.

The groove 54 and the ridge 55 may be formed by any method. The groove 54 is formed, for example, by subjecting the peripheral surface 53 of the cooling roll 5 to various machining such as cutting, transfer (compression), grinding, blasting, laser machining, electric discharge machining, and chemical etching. You can Among them, machining is preferable, and cutting is particularly preferable because it is relatively easy to increase the accuracy of the width and depth of the grooves 54 and the pitch of the grooves 54 arranged in parallel.

Further, the ridges 55 may be formed (as a portion remaining on the peripheral surface 53) as a result of processing the peripheral surface 53 by the method of forming the groove 54 described above. .

When the surface layer 52 is provided on the outer peripheral surface of the roll base material 51 (when the surface layer 52 is not integrally formed with the roll base material 51), the groove 54 or the ridge 55 is directly formed on the surface layer. It may or may not be formed by the method described above. That is, as shown in FIG. 8, after the surface layer 52 is provided, the grooves 54 or the ridges may be formed in the surface layer by the above-described method, but as shown in FIG. The surface layer 52 may be formed on the outer peripheral surface after forming the grooves or ridges by the method described above. In this case, the thickness of the surface layer 52 is set to the roll base 5
By making it smaller than the depth of the groove formed in 1 or the height of the ridge, as a result, the groove which is a dimple correcting means is formed on the peripheral surface 53 without machining the surface of the surface layer 52. 54 or ridges 55 are formed. In this case, since the surface of the surface layer 52 is not machined,
After that, the surface roughness R of the peripheral surface 53 is not even polished.
It is possible to make a relatively small.

Incidentally, FIGS. 3 and 5 (FIG. 14 and FIG. 1 which will be described later)
6, FIG. 18, FIG. 20, and FIG. 21 are the same), the boundary between the roll base material and the surface layer is omitted.

[Alloy Composition of Magnet Material] As the ribbon-shaped magnet material and the magnet powder in the present invention, those having excellent magnetic characteristics are preferable, and examples thereof include R (where R includes Y). At least one of the rare earth elements
Alloy, especially R (where R is at least one of rare earth elements including Y) and TM (provided that TM
Is at least one of transition metals) and B (boron)
Examples of the alloys include and, and those having the following compositions [1] to [5] are preferable.

[1] A rare earth element mainly containing Sm and C
Those containing a transition metal mainly containing o as a basic component (hereinafter,
Sm-Co based alloy).

[2] R (where R is at least one of rare earth elements including Y), a transition metal (TM) mainly containing Fe, and B as basic components (hereinafter,
R-TM-B type alloy).

[3] A rare earth element mainly composed of Sm and F
A transition metal mainly composed of e and an interstitial element mainly composed of N (hereinafter, referred to as Sm-Fe-N-based alloy).

[4] R (where R is at least one of rare earth elements including Y) and a transition metal such as Fe are basic components, and the soft magnetic phase and the hard magnetic phase are adjacent to each other ( Those having a composite structure (including a structure called a nanocomposite structure) existing (including the case where they are adjacent to each other via a grain boundary phase).

[5] A mixture of at least two of the compositions [1] to [4]. In this case, it is possible to have the advantages of each magnet powder to be mixed, and it is possible to easily obtain more excellent magnetic characteristics.

Typical examples of Sm-Co alloys include SmCo ₅ and Sm ₂ TM ₁₇ (where TM is a transition metal).

Typical R-Fe-B alloys are Nd-Fe-B alloys, Pr-Fe-B alloys, and N-Fe-B alloys.
d-Pr-Fe-B type alloy, Nd-Dy-Fe-B type alloy, Ce-Nd-Fe-B type alloy, Ce-Pr-Nd-
Fe-B based alloys, some of Fe in these are Co, N
Examples thereof include those substituted with other transition metals such as i.

[0085] Typical examples of the Sm-Fe-N based alloy, Sm ₂ Fe ₁₇ was prepared by nitriding the Sm ₂ Fe ₁₇ alloy
Sm-Zr-Fe-C having N ₃ and TbCu ₇ type phases as main phases
An o-N type alloy is mentioned. However, these Sm-Fe
In the case of a -N-based alloy, N is generally introduced as interstitial atoms by producing a quenched ribbon, then subjecting the obtained quenched ribbon to an appropriate heat treatment and nitriding.

As the rare earth element, Y, La and C are used.
e, Pr, Nd, Pm, Sm, Eu, Gd, Tb, D
Examples thereof include y, Ho, Er, Tm, Yb, Lu, and misch metal, and one or more of these may be included. Examples of the transition metal include Fe, Co, Ni and the like, and one or more of these may be included.

In order to improve magnetic properties such as coercive force and maximum magnetic energy product, or to improve heat resistance and corrosion resistance, the magnetic material may contain A as necessary.
l, Cu, Ga, Si, Ti, V, Ta, Zr, Nb,
It is also possible to contain Mo, Hf, Ag, Zn, P, Ge, Cr, W and the like.

The composite structure (nanocomposite structure)
Has a soft magnetic phase 10 and a hard magnetic phase 11 in a pattern (model) as shown in FIG. 10, FIG. 11 or FIG. 12, and the thickness and particle size of each phase are on the nanometer level. Existing. And the soft magnetic phase 1
0 and the hard magnetic phase 11 are adjacent to each other (including the case where they are adjacent to each other via the grain boundary phase), and a magnetic exchange interaction occurs.

Since the magnetization of the soft magnetic phase easily changes its direction by the action of the external magnetic field, when mixed in the hard magnetic phase, the magnetization curve of the entire system becomes the second quadrant of the BH diagram (JH diagram). It is now a "snake-shaped curve" with steps. However, when the size of the soft magnetic phase is sufficiently small, such as several tens of nm or less, the magnetization of the soft magnetic material is sufficiently tightly bound by the coupling with the magnetization of the surrounding hard magnetic material so that the entire system behaves as a hard magnetic material. Become.

The magnet having such a composite structure (nanocomposite structure) mainly has the following features 1) to 5).
have.

1) In the second quadrant of the BH diagram (JH diagram),
The magnetization reversibly springs back (also called "spring magnet" in this sense). 2) It has good magnetizability and can be magnetized in a relatively low magnetic field. 3) The temperature dependence of the magnetic properties is smaller than that of the hard magnetic phase alone. 4) The change over time in magnetic properties is small. 5) Magnetic properties do not deteriorate even when finely pulverized.

As described above, the magnet having the composite structure has excellent magnetic characteristics. Therefore, it is particularly preferable that the magnet powder has such a composite structure.

The patterns shown in FIGS. 10 to 12 are
This is an example, and the present invention is not limited to these.

[Manufacture of ribbon-shaped magnet material] Next, the manufacture of a ribbon-shaped magnet material (quenched ribbon) using the cooling roll 5 described above will be described.

The strip-shaped magnet material is produced by causing molten metal of the magnet material to collide with the peripheral surface of the cooling roll to cool and solidify it. Hereinafter, an example thereof will be described.

As shown in FIG. 1, a quenching ribbon manufacturing apparatus 1
Is installed in a chamber (not shown) and operates in a state where the chamber is filled with an inert gas or other atmospheric gas. In particular, the atmosphere gas is preferably an inert gas in order to prevent oxidation of the quenched ribbon 8. Examples of the inert gas include argon gas, helium gas, nitrogen gas and the like.

The pressure of the atmospheric gas is not particularly limited, but is preferably 1 to 760 Torr.

A predetermined pressure higher than the internal pressure of the chamber is applied to the liquid surface of the molten metal 6 in the cylindrical body 2. Molten metal 6
Is the pressure difference between the sum of the pressure acting on the liquid level of the molten metal 6 in the cylinder 2 and the pressure applied in proportion to the height of the liquid level in the cylinder 2 and the pressure of the atmospheric gas in the chamber. Due to
It is ejected from the nozzle 3.

Molten metal injection pressure (the sum of the pressure acting on the liquid surface of the molten metal 6 in the cylinder 2 and the pressure applied in proportion to the height of the liquid surface in the cylinder 2 and the pressure of the atmospheric gas in the chamber). Is not particularly limited, but is 10 to 100 kPa.
Is preferred.

In the quenching ribbon manufacturing apparatus 1, when the magnet material is put into the cylindrical body 2 and heated by the coil 4 to be melted, and the molten metal 6 is injected from the nozzle 3, the molten metal 6 is melted as shown in FIG. After colliding with the peripheral surface 53 of the cooling roll 5 to form the paddle (bath pool) 7, the peripheral surface 53 of the cooling roll 5 rotating.
While being dragged by, it is rapidly cooled and solidified, and the quenched ribbon 8
Are formed continuously or intermittently. At this time, when gas enters between the paddle 7 and the peripheral surface 53, the dimples 9 are formed on the roll surface 81 of the quenching ribbon 8 and the dimple correcting means (the groove 54 is formed on the peripheral surface 53 of the cooling roll 5). And the ridge 55) are provided, the dimple 9
Is split. Quenched ribbon 8 formed in this way
The roll surface 81 eventually separates from the peripheral surface 53 and advances in the direction of arrow B in FIG.

As described above, by providing the dimple correcting means on the peripheral surface 53, generation of huge dimples on the roll surface 81 is prevented, and uneven cooling of the paddle 7 is prevented. As a result, the quenched ribbon 8 having a small variation in crystal grain size and excellent magnetic properties can be obtained.

Further, when the quenching ribbon 8 is actually manufactured, the nozzle 3 does not necessarily have to be installed right above the rotary shaft 50 of the cooling roll 5.

The peripheral speed of the cooling roll 5 is suitable depending on the composition of the molten alloy, the constituent material (composition) of the surface layer 52, the surface properties of the peripheral surface 53 (particularly, the wettability of the peripheral surface 53 to the molten metal 6) and the like. Although the ranges are different, in order to improve magnetic properties, it is usually preferably 5 to 60 m / sec, and 10 to 40 m.
/ Sec is more preferred. If the peripheral speed of the cooling roll 5 is less than the lower limit value, the cooling speed of the molten metal 6 (paddle 7) decreases, the crystal grain size tends to increase, and the magnetic properties may decrease. On the other hand, when the peripheral speed of the cooling roll 5 exceeds the upper limit value, the cooling speed is increased, and the proportion occupied by the amorphous structure is increased, and even if the heat treatment described later is performed thereafter, the magnetic characteristics are not sufficient. May not improve to.

The quenched ribbon 8 obtained as described above is
It is preferable that the width w and the thickness are as uniform as possible. In this case, the average thickness t of the quenched ribbon 8 is 8 to 50.
The thickness is preferably about μm, more preferably about 10 to 40 μm. If the average thickness t is less than the lower limit value, the proportion occupied by the amorphous structure becomes large, and thereafter,
Even if the heat treatment described below is performed, the magnetic properties may not be sufficiently improved. Productivity per unit time also decreases. On the other hand, when the average thickness t exceeds the upper limit value, the free surface 8
Since the crystal grain size on the 2 side tends to become coarse, the magnetic properties may deteriorate.

The quenched ribbon 8 of the present invention thus obtained has the cooling roll 5 on at least a part of the roll surface 81.
The surface shape of the peripheral surface 53 may be transferred (including partial transfer). Thereby, the peripheral surface 53 of the cooling roll 5
Ridge 8 corresponding to the surface shape of the groove (groove 54 or ridge 55)
3 or groove 84 is formed. In this way, the ridges 8
The dimple 9 is formed by forming the groove 3 or the groove 84.
Are efficiently divided, and the area of each dimple 9 is reduced. In addition, the total area of the dimples 9 is also reduced due to the degassing effect of the grooves 54 formed on the peripheral surface 53 of the cooling roll 5. As a result, the variation in crystal grain size in each part of the quenched ribbon 8 is reduced, and excellent magnetic characteristics are obtained.

On the roll surface 81 of the quenched ribbon 8, the proportion of the projected area occupied by the dimples 9 (giant dimples) of 2000 μm ² or more formed during solidification is preferably 10% or less, and 5% or less. Is more preferable. If the proportion of the projected area occupied by the huge dimples exceeds 10%, the proportion of the area occupied by the portion having a significantly low cooling rate (particularly in the vicinity of the central portion of the giant dimples) is higher than that of the portion in contact with the cooling roll 5. As a result, the magnetic properties of the entire quenched ribbon 8 deteriorate.

The ratio of the projected area of the dimples is calculated as the area ratio of the predetermined area on the roll surface 81. In particular, it is preferable to take the average value of the area ratios calculated at several points on the roll surface 81.

The proportion of the projected area (total area) occupied by the dimples 9 formed at the time of solidification on the roll surface 81 of the quenched ribbon 8 is preferably 40% or less, and 30%.
The following is more preferable. If the ratio of the projected area (total area) occupied by the dimples 9 is too large, the cooling rate at the time of solidification is reduced as a whole, and as a result, the crystal grain size is coarsened and the magnetic properties of the obtained quenched ribbon 8 are reduced. The characteristics deteriorate.

The obtained quenched ribbon 8 may be heat-treated for the purpose of promoting recrystallization of an amorphous structure (amorphous structure) and homogenizing the structure. The condition of this heat treatment is, for example, 400 to
At 900 ° C., it can be about 0.2 to 300 minutes.

Further, this heat treatment is performed under vacuum or reduced pressure (for example, 1 × 10 ^-1 to 1 × 1) in order to prevent oxidation.
0 ^-6 Torr) or an inert gas such as nitrogen gas, argon gas or helium gas is preferably used.

The quenched ribbon (thin band magnet material) 8 obtained as described above has a fine crystal structure or a structure in which fine crystals are contained in an amorphous structure, and excellent magnetic properties are obtained. To be

Although the single roll method has been described as an example of the quenching method in the above, the twin roll method may be adopted. Since such a quenching method can make the metal structure (crystal grains) finer, it is effective for improving the magnet characteristics of the bonded magnet, particularly the coercive force.

[Manufacture of Magnet Powder] By crushing the quenched ribbon 8 manufactured as described above, the magnet powder of the present invention can be obtained.

The crushing method is not particularly limited, and various crushing devices such as a ball mill, a vibration mill, a jet mill, a pin mill, and a crushing device can be used. In this case, the pulverization is performed under vacuum or reduced pressure (for example, 1 × 10 ^-1 to 1 × 10 ^-6 Torr) or in an inert gas such as nitrogen gas, argon gas, or helium gas in order to prevent oxidation. Such a non-oxidizing atmosphere can also be used.

The average particle diameter of the magnet powder is not particularly limited, but in the case of producing a bonded magnet (rare earth bonded magnet) described later, consideration is given to prevention of oxidation of the magnet powder and prevention of deterioration of magnetic characteristics due to pulverization. Then, the thickness is preferably 1 to 300 μm, and more preferably 5 to 150 μm.

Further, in order to obtain a better moldability during the molding of the bonded magnet, it is preferable that the particle size distribution of the magnet powder is dispersed to some extent (there are variations). As a result, the porosity of the obtained bonded magnet can be reduced, and as a result, the density and mechanical strength of the bonded magnet can be further increased when the content of the magnetic powder in the bonded magnet is the same. Therefore, the magnetic characteristics can be further improved.

The obtained magnet powder may be subjected to heat treatment for the purpose of removing the influence of strain introduced by pulverization and controlling the crystal grain size. The condition of this heat treatment is, for example, 350 to 850 ° C.
Then, it can be about 0.2 to 300 minutes.

Further, this heat treatment is performed under vacuum or reduced pressure (for example, 1 × 10 ^-1 to 1 × 1) in order to prevent oxidation.
0 ^-6 Torr) or an inert gas such as nitrogen gas, argon gas or helium gas is preferably used.

When a bonded magnet is manufactured by using such a magnet powder, the magnet powder has good bondability with the binding resin (wetting property of the binding resin), and therefore, this bonded magnet has a mechanical strength. It is high and has excellent thermal stability (heat resistance) and corrosion resistance. Therefore, the magnet powder is suitable for manufacturing a bonded magnet, and the manufactured bonded magnet becomes highly reliable.

The average grain size of the magnet powder as described above is preferably 500 nm or less, more preferably 200 nm or less, and further preferably about 10 to 120 nm. If the average crystal grain size exceeds 500 nm, magnetic properties, particularly coercive force and squareness may not be sufficiently improved.

In particular, when the magnet material has a composite structure as described in [4] above, the average crystal grain size is 1 to 1
The thickness is preferably 00 nm, more preferably 5 to 50 nm. When the average crystal grain size is in such a range, a magnetic exchange interaction is more effectively generated between the soft magnetic phase 10 and the hard magnetic phase 11, and the remarkable magnetic characteristics are improved. Improvement is recognized.

[Bonded Magnet and Its Production] Next, the bonded magnet of the present invention will be described.

The bonded magnet of the present invention is preferably one obtained by binding the above-mentioned magnet powder with a binding resin.

The binder resin (binder) may be either a thermoplastic resin or a thermosetting resin.

Examples of the thermoplastic resin include polyamide (eg, nylon 6, nylon 46, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 6-12, nylon 6-66), thermoplastic polyimide. , Liquid crystal polymers such as aromatic polyester, polyphenylene oxide, polyphenylene sulfide, polyethylene, polypropylene, polyolefin such as ethylene-vinyl acetate copolymer, modified polyolefin, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyester such as polybutylene terephthalate, poly Ether, polyetheretherketone, polyetherimide, polyacetal, etc.
Further, copolymers, blends, polymer alloys and the like containing these as main constituents may be mentioned, and one kind or a mixture of two or more kinds thereof may be used.

Among these, those mainly containing a liquid crystal polymer and polyphenylene sulfide are preferable from the viewpoint of polyamide, and the improvement of heat resistance, because they are particularly excellent in moldability and have high mechanical strength. Further, these thermoplastic resins are also excellent in kneadability with magnet powder.

[0127] Such thermoplastic resin can be selected in a wide range depending on its type, copolymerization and the like, for example, one with an emphasis on moldability, one with an emphasis on heat resistance and mechanical strength. There is an advantage.

On the other hand, examples of the thermosetting resin include various epoxy resins such as bisphenol type, novolac type, naphthalene type, phenol resin, urea resin, melamine resin, polyester (unsaturated polyester) resin, polyimide resin, and silicone resin. , Polyurethane resin, etc., and one kind or a mixture of two or more kinds of them can be used.

Of these, the moldability is particularly excellent, the mechanical strength is high, and the heat resistance is excellent.
Epoxy resin, phenol resin, polyimide resin and silicone resin are preferable, and epoxy resin is particularly preferable.
In addition, these thermosetting resins have kneadability with magnet powder,
Excellent kneading uniformity.

The thermosetting resin used (uncured)
May be liquid at room temperature or solid (powdered).

Such a bonded magnet of the present invention is manufactured, for example, as follows. Magnet powder, binding resin,
If necessary, mix with additives (antioxidants, lubricants, etc.),
Kneading (for example, warm kneading) to produce a composition for a bonded magnet (compound), and using this composition for a bonded magnet, by a molding method such as compression molding (press molding), extrusion molding, injection molding, It is formed into a desired magnet shape without a magnetic field. When the binder resin is a thermosetting resin, it is cured by heating after molding.

Of the three molding methods, the extrusion molding and the injection molding (in particular, the injection molding) have the advantages that the degree of freedom in selecting the shape is wide and the productivity is high. In this method, in order to obtain good moldability, it is necessary to secure sufficient fluidity of the compound in the molding machine.Therefore, as compared with compression molding, the content of magnetic powder should be increased, that is, the bonded magnet should be made higher. It cannot be densified. However, in the present invention, as will be described later, a high magnetic flux density is obtained, and therefore, excellent magnetic properties can be obtained without densifying the bond magnet. Therefore, in a bond magnet manufactured by extrusion molding or injection molding, Can also enjoy its benefits.

The content (content rate) of the magnet powder in the bonded magnet is not particularly limited, and is usually determined in consideration of the molding method and compatibility between the moldability and the high magnetic properties. Specifically, it is preferably about 75 to 99.5 wt%, and 8
More preferably, it is about 5 to 97.5 wt%.

In particular, when the bonded magnet is manufactured by compression molding, the content of the magnet powder is 90-9.
It is preferably about 9.5 wt%, and 93 to 98.5.
More preferably, it is about wt%.

When the bonded magnet is manufactured by extrusion molding or injection molding, the content of the magnet powder is preferably about 75 to 98 wt%, and 85 to 98 wt%.
It is more preferably about 97 wt%.

The density ρ of the bonded magnet is determined by factors such as the specific gravity of the magnet powder contained therein, the content of the magnet powder, and the porosity. In the bonded magnets according to this invention, but are not limited to its density ρ is particularly preferably in the range of about 4.5~6.6Mg / m ^3, more preferably about 5.5~6.4Mg / m ³ .

In the present invention, since the residual magnetic flux density and the coercive force of the magnet powder are large, not only when the content of the magnet powder is high, but also when the content of the magnet powder is relatively small, when the magnet powder is molded, excellent magnetic properties (especially, high maximum magnetic energy product (BH) _{ma x)} is obtained.

The shape, dimensions, etc. of the bonded magnet of the present invention are not particularly limited. For example, regarding the shape, for example, columnar shape, prismatic shape, cylindrical shape (ring shape), arc shape, flat plate shape, curved plate shape, etc. Any shape can be used, and the size can be any size from large size to ultra small size. In particular, it is frequently mentioned in the present specification that it is advantageous for a downsized and ultra-small magnet.

In the bonded magnet of the present invention, the coercive force (inherent coercive force at room temperature) H _cJ is preferably 320 to 1200 kA / m, more preferably 400 to 800 kA / m.
When the coercive force is less than the lower limit value, demagnetization becomes remarkable when a reverse magnetic field is applied, and heat resistance at high temperature is poor.
Further, if the coercive force exceeds the upper limit value, the magnetizability decreases. Therefore, by _setting the coercive force H _cJ within the above range,
When magnetizing a bonded magnet (in particular, a cylindrical magnet) with multiple poles, even if a sufficient magnetizing magnetic field cannot be obtained, good magnetizing becomes possible and a sufficient magnetic flux density is obtained. A high-performance bonded magnet can be provided.

[0140] bonded magnet of the present invention, the maximum magnetic energy product (BH) _max is preferably at 40 kJ / m ³ or more, more preferably 50 kJ / m ³ or more, 70
More preferably, it is 120 kJ / m ³ . When the maximum magnetic energy product (BH) _max is less than 40 kJ / m ³ , when used for a motor, sufficient torque cannot be obtained depending on its type and structure.

As described above, according to the cooling roll 5 of this embodiment, since the groove 54 and the ridge 55 are provided as the dimple correcting means, the dimple 9 formed on the roll surface 81 is divided. You can Therefore, it is possible to prevent the occurrence of huge dimples and reduce the difference in cooling rate between the parts of the paddle 7. As a result, in the quenched ribbon 8, the variation in crystal grain size is small, and high magnetic characteristics can be stably obtained.

Therefore, the bond magnet obtained from the quenched ribbon 8 has excellent magnetic characteristics. Also, when manufacturing bonded magnets, high magnetic characteristics can be obtained without pursuing high density, so that formability, dimensional accuracy, and
It is possible to improve mechanical strength, corrosion resistance, heat resistance and the like.

Next, a second embodiment of the cooling roll 5 of the present invention will be described. 13 is a front view showing a second embodiment of the cooling roll of the present invention, and FIG. 14 is an enlarged sectional view of the cooling roll shown in FIG. Hereinafter, the cooling roll of the second embodiment will be described focusing on the differences from the first embodiment, and description of the same matters will be omitted.

As shown in FIG. 13, the groove 54 (or the protrusion 55) which is the dimple correcting means is formed in a spiral shape around the rotation shaft 50 of the cooling roll 5. Groove 54
When the (or the ridge 55) has such a shape, the groove 54 (or the ridge 5) can be relatively easily formed over the entire peripheral surface 53.
5) can be formed. For example, the cooling roll 5 is rotated at a constant speed, and the outer peripheral portion of the cooling roll 5 is cut while moving a cutting tool such as a lathe in parallel with the rotating shaft 50 at a constant speed. Groove 5
4 can be formed.

The spiral groove 54 (or the ridge 55)
May be one article (one) or two articles (two) or more.

The longitudinal direction of the groove 54 (or the ridge 55),
The angle θ (absolute value) formed with the rotation direction of the cooling roll 5 is 3
It is preferably 0 ° or less, and more preferably 20 ° or less. When θ is 30 ° or less, the gas that has entered between the peripheral surface 53 and the paddle 7 can be efficiently discharged at any peripheral speed of the cooling roll 5. Therefore, the dimples are more likely to be divided, and the area of each dimple and the total area of the dimples are further reduced.

At each part on the peripheral surface 53, the value of θ is
It may or may not be constant. Also, the groove 54
When two or more ridges (or ridges 55) are provided, θ may be the same or different for each groove 54 (or ridge 55).

The groove 54 is formed at the edge 56 of the peripheral surface 53.
It opens at the opening 57. As a result, the gas discharged to the groove 54 from between the peripheral surface 53 and the paddle 7 is discharged to the side of the cooling roll 5 from the opening 57, and the discharged gas is again discharged to the peripheral surface 53 and the paddle 7. It can be effectively prevented from invading between and, and the effect of correcting dimples is further improved. In the illustrated configuration, the groove 54 is open at both edges, but it may be open only at one edge.

Next, a third embodiment of the cooling roll 5 of the present invention will be described. FIG. 15 is a front view showing a third embodiment of the cooling roll of the present invention, and FIG. 16 is an enlarged sectional view of the cooling roll shown in FIG. Hereinafter, the cooling roll of the third embodiment will be described focusing on the differences from the first embodiment and the second embodiment, and the description of the same matters will be omitted.

As shown in FIG. 15, on the peripheral surface 53, at least two grooves 54 whose spiral rotation directions are opposite to each other are formed. These grooves 54 intersect at multiple points.

By thus forming the groove 54 in which the spiral is rotated in the opposite direction, the manufactured quenching ribbon 8 receives the lateral force from the right-handed groove and the lateral force received from the left-handed groove. This cancels the force in the directional direction, suppresses the lateral movement of the quenched ribbon 8 in FIG. 15, and stabilizes the traveling direction.

Further, in FIG. 15, the angle (absolute value) formed between the longitudinal direction of the groove 54 and the rotation direction of the cooling roll 5 in the respective rotation directions indicated by θ ₁ and θ ₂ is in the same range as θ described above. Is preferred.

Next, a fourth embodiment of the cooling roll 5 of the present invention will be described. 17 is a front view showing a fourth embodiment of the cooling roll of the present invention, and FIG. 18 is an enlarged sectional view of the cooling roll shown in FIG. Hereinafter, the cooling roll of the fourth embodiment will be described focusing on the differences from the first to third embodiments, and the description of the same matters will be omitted.

As shown in FIG. 17, a plurality of grooves 54 are formed in an inverted V shape from substantially the center in the width direction of the peripheral surface of the cooling roll 5 toward both edges 56.

When the cooling roll 5 having such a groove 54 is used, depending on the combination with the rotation direction thereof,
The gas that has entered between the peripheral surface 53 and the paddle 7 can be discharged with higher efficiency. Therefore, the dimples are more likely to be divided, and the area of each dimple and the total area of the dimples are further reduced.

Further, when the grooves having such a pattern are formed, they are generated as the cooling roll 5 rotates, as shown in FIG.
Since the forces from both the left and right grooves 54 are balanced, the quenching ribbon 8 is set at the substantially center of the cooling roll 5 in the width direction, so that the traveling direction of the quenching ribbon 8 is stabilized.

Incidentally, in the present invention, various conditions such as the shape of the dimple correcting means are not limited to those in the above-described first to fourth embodiments.

For example, the groove 54 may be formed intermittently as shown in FIG. Further, the cross-sectional shape of the groove 54 is not particularly limited, and for example, FIGS.
It may be as shown in FIG.

Further, the dimple correcting means is not limited to the above-mentioned groove or ridge, and any means having a function of correcting dimples may be used.

Even with such a cooling roll 5, the same effect as that of the cooling roll 5 of the above-described first to fourth embodiments can be obtained.

[0161]

EXAMPLES Specific examples of the present invention will be described below.

Example 1 A cooling roll having dimple correcting means on the peripheral surface shown in FIGS. 1 to 3 was manufactured, and a quenching ribbon manufacturing apparatus having the structure shown in FIG. 1 equipped with this cooling roll was prepared.

The cooling roll was manufactured as follows. First, copper (thermal conductivity at 20 ° C: 395 W · m
^-1 · K ^-1 , coefficient of thermal expansion at 20 ℃: 16.5 × 10 ^-6
K ^-1 ) roll base material (diameter 200 mm, width 30 mm)
Was prepared, and the peripheral surface thereof was subjected to cutting work to obtain a substantially mirror surface (surface roughness Ra 0.07 μm).

Thereafter, a cutting process was further performed to form a groove substantially parallel to the rotation direction of the roll base material.

ZrC (thermal conductivity at 20 ° C .: 20.6 W ·
m ⁻¹ · K ⁻¹ , coefficient of thermal expansion at 20 ° C .: 7.0 × 10 ⁻⁶
K ^-1 ) surface layer is formed by ion plating,
A cooling roll as shown in FIGS. 1 to 3 was obtained.

Using the quenching ribbon manufacturing apparatus 1 equipped with the cooling roll 5 thus obtained, the alloy composition was (Nd _0.75 Pr _0.2 Dy _0.05 ) _9.0 Fe by the method described below.
A quenched ribbon represented by _bal Co _8.2 B _5.6 was produced.

First, Nd, Pr, Dy, Fe, Co, B
Each raw material was weighed and a mother alloy ingot was cast.

In the quenching ribbon manufacturing apparatus 1, the mother alloy ingot was placed in a quartz tube having a nozzle (circular hole orifice) 3 at the bottom. After degassing the inside of the chamber in which the rapid cooling ribbon manufacturing apparatus 1 is housed, an inert gas (helium gas) was introduced to create an atmosphere of a desired temperature and pressure.

After that, the mother alloy ingot in the quartz tube is melted by high frequency induction heating, the peripheral speed of the cooling roll 5 is set to 28 m / sec, and the injection pressure of the molten metal 6 (the internal pressure of the quartz tube and the liquid in the cylindrical body 2). With the sum of the pressure applied in proportion to the surface height and the atmospheric pressure) set to 40 kPa and the atmospheric gas pressure set to 60 kPa, the molten metal 6 is almost directly above the rotating shaft 50 of the cooling roll 5. From the above, it was jetted toward the peripheral surface 53 at the top of the cooling roll 5 to continuously produce the quenched ribbon 8.

(Examples 2 to 7) Cooling rolls were manufactured in the same manner as in Example 1 except that the shapes of grooves and ridges were as shown in FIGS. 13 and 14. At this time, the average width of the groove, the average width of the ridge, the average depth of the groove (average height of the ridge),
And, 6 types of cooling rolls were manufactured by variously changing the average pitch of the grooves (projections) arranged in parallel. In addition, both
Using a lathe in which three cutting tools were installed at equal intervals, three grooves were formed so that the pitch of the adjacent grooves was substantially constant at each site on the peripheral surface. The angle θ formed by the longitudinal direction of the groove and the rotation direction of the cooling roll was 5 ° for all the cooling rolls. The cooling rolls of the quenching ribbon manufacturing apparatus used in Example 1 were sequentially replaced with these cooling rolls,
A quenched ribbon was manufactured in the same manner as in Example 1.

(Embodiment 8) The shapes of grooves and ridges are shown in FIG.
5, a cooling roll was manufactured in the same manner as in Example 2 except that the cooling roll of the quenching ribbon manufacturing apparatus was replaced with this cooling roll, and in the same manner as in Example 1. A quenched ribbon was produced. The angles θ ₁ and θ ₂ formed by the longitudinal direction of the groove and the rotation direction of the cooling roll are both 15 °.
Met.

(Embodiment 9) The shapes of grooves and ridges are shown in FIG.
7. A cooling roll was manufactured in the same manner as in Example 1 except that the cooling roll shown in FIG. 18 was used, and the cooling roll of the quenching ribbon manufacturing apparatus was replaced with this cooling roll. A quenched ribbon was produced. The angles θ ₁ and θ ₂ formed by the longitudinal direction of the groove and the rotation direction of the cooling roll are both 20 °.
Met.

(Comparative Example) The same procedure as in Example 1 was carried out except that after the outer periphery of the roll base material was cut into a substantially mirror surface, the surface layer was formed as it was without forming grooves and ridges. A cooling roll was manufactured by replacing the cooling roll of the quenching ribbon manufacturing apparatus with this cooling roll, and a quenching ribbon was manufactured in the same manner as in Example 1.

The thickness of the surface layer of each cooling roll of Examples 1 to 9 and Comparative Example was 7 μm. After forming the surface layer, the surface layer was not machined. For each cooling roll, the groove width L ₁ (average value), the ridge width L ₂ (average value), the groove depth (height of the ridge) L ₃ (average value), the grooves arranged in parallel ( Ridge) pitch L ₄
Table 1 shows (average value) and measured values of the ratio of the projected area occupied by the grooves on the peripheral surface of the cooling roll.

[0175]

[Table 1]

With respect to the quenched ribbons of Examples 1 to 9 and Comparative Example, the surface shape of the roll surface was observed using a scanning electron microscope (SEM). As a result, Examples 1 to 9
In each of the quenched ribbons, the surface shape (groove or ridge) of the peripheral surface of the cooling roll is transferred, and the corresponding ridge or groove is formed, whereby the dimples are divided. Was confirmed. On the other hand, it was confirmed that a large number of huge dimples were present in the quenched ribbon of the comparative example. An electron micrograph of the quenched ribbon of Example 3 is shown in FIG.

The quenched ribbons of Examples 1 to 9 and the comparative example were evaluated as follows and, respectively.

Magnetic Properties of Quenched Strips For each of the quenched ribbons, a quenched ribbon having a length of about 5 cm was taken out, and five samples having a length of about 7 mm were continuously prepared from the quenched ribbon, and the average of each sample was obtained. Thickness t, giant dimples (20
The ratio of the projected area occupied by (00 μm ² or more), the ratio of the projected area (total area) occupied by the dimples on the roll surface, and the magnetic properties were measured.

The average thickness t is 1 by a micrometer.
The measurement was carried out at 20 measurement points for each sample, and this was taken as the average value. Giant dimples on the roll surface (20
The proportion of the projected area occupied by (00 μm ² or more) and the proportion of the projected area (total area) occupied by the dimples on the roll surface were determined from the results of observation with a scanning electron microscope (SEM). For the magnetic characteristics, a coercive force H _cJ (kA / m) and a maximum magnetic energy product (BH) _max (kJ / m ³ ) were measured using a vibrating sample magnetometer (VSM). In the measurement, the major axis direction of the quenched ribbon was the applied magnetic field direction. In addition,
No demagnetizing field correction was performed.

Magnetic Properties of Bonded Magnet For each quenched ribbon, in an argon gas atmosphere,
Heat treatment was performed at 675 ° C. for 300 seconds.

[0183] These quenched ribbons are crushed,
A magnet powder having an average particle size of 75 μm was obtained.

In order to analyze the phase constitution of the magnet powder thus obtained, X-ray diffraction was performed using Cu-Kα in the diffraction angle (2θ) of 20 ° to 60 °. From the diffraction pattern, the hard magnetic phase R ₂ (Fe.
Co) ₁₄ B-type phase and soft magnetic phase α- (Fe, C
o) The diffraction peak of the type phase could be confirmed, and it was confirmed from the observation results by the transmission electron microscope (TEM) that each formed a composite structure (nanocomposite structure). The average crystal grain size of each phase was measured for each magnet powder.

Next, each magnet powder was mixed with an epoxy resin to prepare a bond magnet composition (compound).
At this time, the compounding ratio (weight ratio) of the magnet powder and the epoxy resin was set to be substantially equal for each sample. That is, the content (content rate) of the magnet powder in each sample is
It was about 97.5 wt%.

Next, this compound was pulverized into granules, and the granules were weighed and filled in a die of a press machine, compression-molded at a temperature of 120 ° C. and a pressure of 600 MPa (in a non-magnetic field), and then cooled. After releasing from the mold, it was heated and cured at 175 ° C. to obtain a cylindrical bonded magnet having a diameter of 10 mm and a height of 8 mm.

These bonded magnets were subjected to pulse magnetization with a magnetic field strength of 3.2 MA / m, and then a maximum applied magnetic field of 2.0 MA was applied with a DC self-recording flux meter (TRF-5BH manufactured by Toei Industry Co., Ltd.). The magnetic properties (residual magnetic flux density Br, coercive force H _cJ and maximum magnetic energy product (BH) _max ) were measured at / m. The temperature at the time of measurement was 23 ° C. (room temperature).
The results are shown in Tables 2 to 4.

[0186]

[Table 2]

[0187]

[Table 3]

[0188]

[Table 4]

As is clear from Tables 2 and 3, in the quenched ribbons of Examples 1 to 9, the ratio of the area occupied by the giant dimples was as small as 0.1 to 3.8%, and the area occupied by the dimples (total The area) ratio is also decreasing. In addition, variations in magnetic characteristics are small, and magnetic characteristics are high as a whole. This is presumed to be due to the following reasons.

The cooling rolls of Examples 1 to 9 have dimple correcting means on the peripheral surface thereof. Therefore, generation of giant dimples on the roll surface of the quenched ribbon is prevented or suppressed, the area per dimple is reduced, and the area (total area) occupied by dimples is also reduced. Therefore, it is considered that the difference in the cooling rate between the respective parts of the paddle becomes small, and as a result, a quenched ribbon having small variations in crystal grain size and magnetic characteristics can be obtained.

On the other hand, in the quenched ribbon of the comparative example, the ratio of the area occupied by the giant dimples is 15.5 to 25.5%.
The ratio of the area (total area) occupied by the dimples is also larger than that of the quenched ribbon of the present invention. In addition, even though the sample was cut from a continuous quenched ribbon, the magnetic properties varied greatly. This is presumed to be due to the following reasons.

A huge dimple is formed on the roll surface of the quenched ribbon by the gas that has entered between the peripheral surface and the paddle. For this reason, the cooling rate in the portion in contact with the peripheral surface is high, whereas the cooling rate in the portion not in contact with the peripheral surface (particularly in the vicinity of the central portion of the giant dimple) decreases, resulting in a coarse crystal grain size. Change occurs. As a result, it is considered that the variation in the magnetic properties of the obtained quenched ribbon becomes large.

Also, as is clear from Table 4, Example 1
The bonded magnets Nos. 9 to 9 have excellent magnetic characteristics, while the bonded magnets of Comparative Examples have only low magnetic characteristics.

In Examples 1 to 9, the magnetic powder obtained from the quenched ribbon having high magnetic characteristics and small variations in magnetic characteristics was used, whereas in Comparative Examples, variations in magnetic characteristics were observed. Since the magnetic powder obtained from the large quenched ribbon is used, it is considered that the magnetic properties as a whole are deteriorated.

[0195]

As described above, according to the present invention, the following effects can be obtained.

Since the dimple straightening means is provided on the peripheral surface of the cooling roll, the generation of giant dimples in the manufactured quenched ribbon is prevented or suppressed, and the area of each dimple is reduced. Moreover, the total area of the dimples on the roll surface is also reduced. Therefore, the difference in cooling rate between the respective parts of the paddle becomes small, and in the manufactured quenched ribbon, high magnetic characteristics can be stably obtained.

In particular, by appropriately selecting conditions such as the material for forming the surface layer, the thickness, and the dimple correcting means such as the dimensions of the grooves and the ridges, the pitch, etc., the dimples on the roll surface of the rapidly cooled thin ribbon to be produced. It is possible to control the area per one, the total area and the like, and it is possible to obtain a magnet material having excellent magnetic characteristics.

Since the magnet powder is composed of a composite structure having a soft magnetic phase and a hard magnetic phase, it exhibits high magnetization and exhibits excellent magnetic properties, and in particular, its intrinsic coercive force and squareness are improved. .

Since a high magnetic flux density can be obtained, a bond magnet having high magnetic characteristics can be obtained even if it is isotropic. In particular, as compared with the conventional isotropic bonded magnet, since the bonded magnet having a smaller volume can exhibit the magnetic performance equal to or higher than that of the conventional isotropic bonded magnet, it becomes possible to obtain a motor having a smaller size and higher performance.

Further, since a high magnetic flux density can be obtained, it is possible to obtain sufficiently high magnetic characteristics without pursuing higher density in the production of a bonded magnet, and as a result, it is possible to improve the formability. The dimensional accuracy, mechanical strength, corrosion resistance, heat resistance (thermal stability), etc. can be further improved, and a highly reliable bonded magnet can be easily manufactured.

Since the magnetizability is good, it is possible to magnetize with a lower magnetizing magnetic field, especially multipole magnetizing can be easily and surely performed, and a high magnetic flux density can be obtained.

Since it is not required to have a high density, it is also suitable for the production of a bond magnet by an extrusion molding method or an injection molding method, which makes it difficult to form a high density as compared with the compression molding method. Even with a bonded magnet, the effects described above can be obtained. Therefore, the range of choices in the method of forming the bonded magnet, and the degree of freedom in selecting the shape accordingly is expanded.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a first embodiment of a cooling roll of the present invention and a configuration example of an apparatus (quenching ribbon manufacturing apparatus) for manufacturing a ribbon-shaped magnetic material using the cooling roll. .

FIG. 2 is a front view of the cooling roll shown in FIG.

FIG. 3 is a diagram schematically showing a cross-sectional shape near the peripheral surface of the cooling roll shown in FIG.

FIG. 4 is a cross-sectional view schematically showing a state in the vicinity of a portion where a molten metal collides with a cooling roll in an apparatus for manufacturing a conventional ribbon-shaped magnet material by a single roll method (quenching ribbon manufacturing apparatus).

5 is a cross-sectional view schematically showing a state in the vicinity of a portion where the molten metal collides with a cooling roll in the apparatus for manufacturing the ribbon-shaped magnet material (quenching ribbon manufacturing apparatus) shown in FIG.

FIG. 6 is a perspective view schematically showing the surface shape of a ribbon-shaped magnetic material produced by a conventional apparatus for producing a ribbon-shaped magnetic material by a single roll method (quenching ribbon production apparatus).

FIG. 7 is a perspective view schematically showing the surface shape of the ribbon-shaped magnetic material produced by the apparatus for producing the ribbon-shaped magnetic material shown in FIG. 1 (quenching ribbon production apparatus).

FIG. 8 is a diagram for explaining a method of forming dimple correcting means.

FIG. 9 is a diagram for explaining a method of forming dimple correcting means.

FIG. 10 is a diagram schematically showing an example of a composite structure (nanocomposite structure) in the magnet powder of the present invention.

FIG. 11 is a diagram schematically showing an example of a composite structure (nanocomposite structure) in the magnet powder of the present invention.

FIG. 12 is a diagram schematically showing an example of a composite structure (nanocomposite structure) in the magnet powder of the present invention.

FIG. 13 is a front view schematically showing a second embodiment of the cooling roll of the present invention.

14 is a diagram schematically showing a cross-sectional shape near the peripheral surface of the cooling roll shown in FIG.

FIG. 15 is a front view schematically showing a third embodiment of the cooling roll of the present invention.

16 is a diagram schematically showing a cross-sectional shape near the peripheral surface of the cooling roll shown in FIG.

FIG. 17 is a front view schematically showing a fourth embodiment of the cooling roll of the present invention.

FIG. 18 is a diagram schematically showing a cross-sectional shape near the peripheral surface of the cooling roll shown in FIG.

FIG. 19 is a front view schematically showing another embodiment of the cooling roll of the present invention.

FIG. 20 is a diagram schematically showing a cross-sectional shape near the peripheral surface of another embodiment of the cooling roll of the present invention.

FIG. 21 is a diagram schematically showing a cross-sectional shape near the peripheral surface of another embodiment of the cooling roll of the present invention.

FIG. 22 is an electron micrograph showing the surface shape of the ribbon-shaped magnet material of the present invention.

FIG. 23 is a cross-sectional side view showing a state in the vicinity of a portion where molten metal collides with a cooling roll in an apparatus for manufacturing a conventional ribbon magnet material by a single roll method (quenching ribbon manufacturing apparatus).

[Explanation of symbols]

1 Quenched ribbon manufacturing equipment 2 cylinders 3 nozzles 4 coils 5,500 chill roll 50 rotation axis 51 roll base material 52 surface layer 53,530 circumference 54 groove 55 convex 56 edge 57 opening 6,60 molten metal 7,70 paddles 710 Solidification interface 8,80 Quenched ribbon 81,810 Roll surface 82 Free side 83 convex stripes 84 groove 9 dimples 10 Soft magnetic phase 11 Hard magnetic phase

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C22C 38/10 C22C 38/10 H01F 1/053 H01F 1/08 A 1/06 1/06 A 1/08 1/04 A

Claims (27)

[Claims] 1. A molten metal of magnetic material is made to collide with its peripheral surface,
A cooling roll for cooling and solidifying to produce a ribbon-shaped magnet material, wherein the cooling roll has a roll base material and a surface layer provided on the outer periphery of the roll base material, and the surface layer is It is made of ceramics, and has dimple correcting means for dividing the dimples generated on the contact surface of the ribbon-shaped magnet material with the cooling roll on the peripheral surface of the surface layer. And a cooling roll. 2. A molten metal of a magnetic material is made to collide with its peripheral surface,
A cooling roll for cooling and solidifying to produce a ribbon-shaped magnet material, wherein the cooling roll has a roll base material and a surface layer provided on the outer periphery of the roll base material, and the surface layer is , The coefficient of thermal expansion near room temperature is 3.5 to 1
8 [× 10 ⁻⁶ K ⁻¹ ] material is formed, and the dimples generated at the contact surface of the thin strip magnet material with the cooling roll are divided on the peripheral surface of the surface layer. A cooling roll having a dimple straightening means. 3. The cooling roll according to claim 2, wherein the surface layer is made of ceramics. 4. The surface layer is made of a material having a thermal conductivity lower than that of the constituent material of the roll base material around room temperature. Cooling roll. 5. The cooling roll according to claim 1, wherein the surface layer is made of a material having a thermal conductivity of 80 W · m ⁻¹ · K ⁻¹ or less near room temperature. 6. The surface layer has an average thickness of 0.5 to 50.
The cooling roll according to claim 1, wherein the cooling roll has a thickness of μm. 7. The cooling roll according to claim 1, wherein the surface layer is formed without machining the surface thereof. 8. The cooling roll according to claim 1, wherein the dimple correcting means is at least one ridge or groove. 9. The average width of the ridges is 0.5 to 95 μm.
The cooling roll according to claim 8. 10. The average width of the groove is 0.5 to 90 μm.
The cooling roll according to claim 8 or 9. 11. The average height of the ridges or the average depth of the grooves is 0.5 to 20 μm.
The cooling roll according to any one of 1. 12. The cooling roll according to claim 8, wherein the ridges or the grooves are juxtaposed, and the average pitch thereof is 0.5 to 100 μm. 13. The cooling roll according to claim 8, wherein a ratio of a projected area occupied by the convex stripes or the grooves on the peripheral surface is 10% or more. 14. A thin strip magnet material obtained by colliding a molten metal of a magnet material with a peripheral surface of a cooling roll and cooling and solidifying the molten material, wherein grooves or ridges are formed on a contact surface with the cooling roll. And a dimple is divided by the groove or the ridge, a thin strip magnet material. 15. A thin strip magnet material produced by using the cooling roll according to claim 1. Description: 16. At the contact surface with the cooling roll,
15. The ratio of the area occupied by the huge dimples of 2000 μm ² or more formed during solidification is 10% or less.
Alternatively, the ribbon-shaped magnet material according to item 15. 17. The thin strip magnet material according to claim 14, wherein at least a part of the surface shape of the cooling roll is transferred to the contact surface with the cooling roll. 18. The thin strip magnet according to claim 14, wherein a groove or a ridge is formed on the contact surface with the cooling roll, and the dimple is divided by the groove or the ridge. material. 19. The ribbon magnet material according to claim 14, which has an average thickness of 8 to 50 μm. 20. A magnet powder obtained by pulverizing the ribbon-shaped magnet material according to claim 14. 21. The magnet powder is heat-treated at least once in the manufacturing process or after the manufacturing.
The magnet powder according to item 0. 22. The magnet powder according to claim 20, which has an average particle size of 1 to 300 μm. 23. The magnet powder according to claim 20, wherein the magnet powder is composed of a composite structure having a soft magnetic phase and a hard magnetic phase. 24. The magnetic powder according to claim 23, wherein the hard magnetic phase and the soft magnetic phase each have an average crystal grain size of 1 to 100 nm. 25. A bonded magnet comprising the magnet powder according to any one of claims 20 to 24 bonded with a binder resin. 26. The intrinsic coercive force H _cJ at room temperature is 320 to 1
The bonded magnet according to claim 25, which has a power of 200 kA / m. 27. The bonded magnet according to claim 25 or 26, which has a maximum magnetic energy product (BH) _max of 40 kJ / m ³ or more.