JP2002083706A - Method for manufacturing magnet powder for rare earth bonded magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing magnet powder for rare earth bonded magnet, where Sm2Co17-based rare earth magnet powder which has high coercive force and high remanent magnetization and is superior in squareness property can be easily obtained. SOLUTION: In this method for manufacturing magnet powder for rare earth bonded magnet, molten metal of alloy for Sm2Co17-based rare earth magnet powder containing rare earth bonded magnet which contains Sm, Co, Fe, Cu and Zr is poured slantedly on a cooling roll which is rotated at a peripheral speed of 0.1-20 m/sec, and coagulated continuously in thickness of at most 1 mm, and an alloy thin belt is obtained. Continuously, solution heat treatment, aging heat treatment and grinding are performed at a temperature, e.g. at most alloy liquid phase appearing temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rare earth bonded magnet powder for producing a rare earth bonded magnet containing an Sm ₂ Co ₁₇ based rare earth magnet powder and a resin.

[0002]

2. Description of the Related Art Sm-Co type 2-17 type magnet powder for bonded magnets contains Sm, Co, Fe, Cu and Zr as essential components. This powder is prepared by blending a predetermined amount of raw material components, melting in a vacuum or an inert gas atmosphere, casting into a mold, solidifying to produce an alloy ingot, and forming the ingot under a predetermined condition in a vacuum or an inert gas atmosphere. It is manufactured by a method of performing a solution heat treatment and an aging heat treatment to form a single-phase structure of a 1-7 type irregular high temperature phase by heat treatment, and then pulverizing. The alloy obtained by the solution treatment exhibits soft magnetism having a coercive force of 1 kOe or less. However, by performing the aging heat treatment, a cell structure in which the Cu-enriched 1-5 phase precipitates on the mesh is formed in the 2-17 matrix, which increases the coercive force and develops permanent magnet characteristics. . Therefore, conventionally, the magnet properties have been improved by focusing on the structural change in the steps after the solution treatment, and further, in the bond magnetizing step, the powder properties have been optimized to improve the filling ratio of the magnet powder. Is poured, and now (BH) max
High performance bonded magnets of> 12 MGOe have been produced. By the way, in recent years, the use of bonded magnets has been widespread due to its ease of molding, reliability of mechanical strength, etc., and the demand for miniaturization and energy saving of equipment using it has become more and more severe. There is a demand for the development of an Sm-Co-based bonded magnet having a high energy product and a high coercive force and having improved squareness.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide Sm ₂ Co _{1 having} a high coercive force, a high remanence magnetization, and a good squareness.
_An object of the present invention is to provide a method for producing a rare earth bonded magnet magnet powder that can easily obtain a ₇ series rare earth magnet powder.

[0004]

Means for Solving the Problems The present inventors have intensively studied to solve the above problems. First, Sm-Co system 2
Each alloy structure during the manufacturing process of the -17 type rare earth magnet powder was observed in detail, and the relationship between the magnet properties and the alloy structure was explored. As a result, the Zr-rich phase existing in the solidified alloy structure
(Close to the SmCo ₃ phase or Sm ₂ Co ₇ phase in the component composition analysis) even after the aging treatment, and as a result, the coercive force was reduced due to the shortage of the Zr content in the 2-17 parent phase. understood. Therefore, in order to obtain a magnet powder having a high coercive force, a method in which a Zr-rich phase does not appear in a solidified alloy structure or an alloy structure before a solution treatment was examined, and various melting casting methods were tried. As a result, the appearance of the Zr-rich phase is suppressed by casting the molten alloy at a certain cooling rate or higher, and when the cooling rate is too high, the crystal grains become too fine and the crystal orientation during magnetic field forming becomes insufficient. It was found that the remanent magnetization deteriorated. Therefore, as a method capable of easily satisfying such conditions, the present inventors have found a condition by a strip casting method capable of cooling a molten metal at a constant rate and capable of efficient and continuous production. Furthermore, when the organization of each part of the ingot was examined in detail, the last solidification part in the ingot,
That is, in the shrinkage cavity region, there is a region where the abundance ratio of the Zr-rich phase is high and composition segregation, and there is a concentrated phase of surface region oxide. It is found that these structural irregularities deteriorate magnet properties, particularly the squareness. Was. It has been found that these problems can also be solved by the strip casting method. Further, the ribbon obtained by the strip casting method is easier to mechanically pulverize than the ingot obtained by the mold, and the generation of fine powder is suppressed, and the problems of property deterioration and workability can be solved. Furthermore, in the conventional solution heat treatment, heat treatment is performed at the liquid phase appearance temperature in a manner similar to that of the sintered magnet, but in that process, the fine structure of the ribbon formed by the strip casting method becomes coarse, and the subsequent heat treatment is performed. Then, it was found that the non-uniformity of the structure was inevitable, and the magnetic properties were deteriorated.
Therefore, it was found that by performing the solution heat treatment at a temperature lower than the liquid phase appearance temperature, the fine strip cast alloy was directly changed to a single phase, a homogeneous structure was obtained, and the magnetic properties were improved. Completed the invention.

That is, according to the present invention, Sm, Co, F
e, Cu and Zr-containing Sm ₂ Co _17- based rare earth magnet powder-containing alloy melt for rare earth bonded magnets, at a peripheral speed of 0.1 to 2
A rare earth bonded magnet magnet characterized by being poured into a cooling roll rotating at 0 m / sec, continuously solidifying to a thickness of 1 mm or less to obtain an alloy ribbon, then solution heat treatment, aging heat treatment and pulverization. A method for producing a powder is provided. Further, according to the present invention, there is provided the above-mentioned manufacturing method, wherein the solution heat treatment is performed at a temperature not higher than an alloy liquid phase appearance temperature.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The production method of the present invention is characterized in that a molten alloy for a rare-earth bonded magnet containing a Sm ₂ Co _17- based rare-earth magnet powder is solidified under specific conditions to obtain a ribbon, and then subjected to solution heat treatment, aging heat treatment and pulverization. In addition, other steps performed by a usual method for producing a powder for bonded magnets may be included as long as the object of the present invention is not impaired. The magnet powder for a rare earth bonded magnet obtained by the production method of the present invention is Sm
Powder used for a bonded magnet containing a Co-based 2-17 type rare earth magnet powder, comprising Sm, Co, Fe, Cu and Z
r as an essential component.

In the manufacturing method of the present invention, the ribbon is S
An alloy melt for Sm ₂ Co _17- based rare earth magnet raw material containing m, Co, Fe, Cu and Zr is poured onto a cooling roll rotating at a peripheral speed of 0.1 to 20 m / sec, and continuously has a thickness of 1 mm or less. , Preferably 0.01 to 1.0 mm. If the thickness of the ribbon exceeds 1.0 mm, the Zr amount increases on the free surface surface (the side not in contact with the cooling roll) due to a decrease in cooling rate. The composition of the molten alloy contains Sm, Co, Fe, Cu and Zr.
There is no particular limitation as long as a ₂ Co ₁₇ system can be obtained.
It can be determined appropriately with reference to known compositions and the like.

Cooling of the molten alloy is performed at a peripheral speed of 0.1 to 20 m /
A strip casting method under specific conditions is adopted, in which the cooling roll is tilted in seconds, and the thickness is continuously adjusted to the above-mentioned thickness. At this time, a method of manufacturing a thin ingot using a thick mold wall by a casting method to a Cu mold is also considered,
Since the efficiency is low and it is difficult to maintain specific cooling conditions, it is difficult to obtain a magnet powder similar to the magnet powder obtained by the method of the present invention. In the case of casting the molten alloy into a rotating cooling roll, it is preferable to inject the molten alloy into the cooling roll via a tundish or a nozzle, for example, in order to keep the cooling conditions constant and the amount of supply to the roll. At this time, the material of the cooling roll may be a metal having high thermal conductivity, and Cu, Mo, or the like is optimal.

In the production method of the present invention, the solution heat treatment includes maintaining the obtained ribbon in a liquid phase appearance temperature range in which a part of the alloy phase is dissolved in a vacuum or an inert gas atmosphere,
Thereafter, in order to convert the multi-phase structure into a single-phase structure having a 1-7 irregular structure high-temperature phase, a solution can be maintained at a temperature lower than the solidus line, and the solution can be rapidly cooled by a known method. In addition,
The liquid phase appearance temperature and solution temperature change depending on the alloy composition,
Conditions can be set as appropriate. In the present invention, the solution heat treatment is preferably performed at a temperature lower than the liquid phase appearance temperature, for example, at a temperature lower by 3 to 20 ° C. than the liquid phase appearance temperature, in addition to the method based on the above method. . By performing such a solution heat treatment, the alloy structure can be made more uniform, and excellent magnetic properties can be imparted.

In the production method of the present invention, the aging heat treatment can be appropriately selected from ordinary conditions and the like in consideration of the composition of the alloy by the solution heat treatment, and the desired permanent magnet characteristics are obtained. Can be expressed. The aging heat treatment is performed, for example, at 800 to 900 ° C. for 1 to 10 hours.
It can be appropriately selected from a condition range of about time.

In the production method of the present invention, the pulverization may be performed by a known method, for example, mechanical coarse pulverization and fine pulverization using a jet mill or the like. The average particle size of the powder obtained by grinding is not particularly limited,
Usually, the average particle size can be about 10 to 30 μm.

In order to produce a rare-earth bonded magnet using the magnet powder obtained by the production method of the present invention, it can be obtained by a known method such as a method of mixing with a resin, molding under pressure, and curing. At this time, each condition, resin and the like can be selected and appropriately determined.

[0013]

The method of the present invention for producing a magnet powder for a rare-earth bonded magnet is, in particular, a method comprising: cooling a molten alloy under specific conditions to solidify it into a specific thickness;
Since it is subjected to aging heat treatment and pulverization, it is possible to easily obtain Sm ₂ Co ₁₇ based rare earth magnet powder having high coercive force, high remanence magnetization and good squareness. Further, by setting the heating of the solution heat treatment to be equal to or lower than the liquid phase appearance temperature, a magnet powder for a rare-earth bonded magnet having more excellent magnet properties can be obtained.

[0014]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 Raw materials of Sm, Co, Fe, Cu and Zr were weighed to have a predetermined composition and dissolved at 1450 ° C. under a reduced pressure argon atmosphere.
The obtained molten alloy is mixed with Cu rotating at a peripheral speed of 1.5 m / sec.
Rolls were tipped on the rolls via a tundish to continuously prepare thin slices having an average thickness of 0.3 mm. The composition of the obtained alloy ribbon was Sm 24 mass%, Fe 14.5 mass%, C
u 4.6% by mass, Zr 2.9% by mass and Co remaining amount. Next, the obtained alloy ribbon was placed in an argon atmosphere for 1 hour.
After holding at 220 ° C. for 1 hour, it was quenched after solution treatment at 1180 ° C. for 5 hours. Then, at 850 ° C. in an argon atmosphere
, And then slowly cooled to add an aging heat treatment. Subsequently, it was pulverized to 100 mesh or less by mechanical pulverization to prepare a rare earth bonded magnet magnet powder. After adding and mixing an epoxy resin to the obtained magnet powder to a concentration of 1.2% by mass, the mixture is molded under pressure at a pressure of 7 ton / cm ² , the resin is cured in a high-temperature bath, and has an outer shape of 10 mm and a height of 10 mm. A 15 mm rare earth bonded magnet sample was prepared. Table 1 shows the characteristics of the sample. The remanent magnetization (Br) and coercive force (Hc) of the sample
j) and the energy product ((BH) max) were measured according to a conventional method. Table 1 shows the results.

Comparative Example 1 A rare earth bonded magnet sample was prepared in the same manner as in Example 1 except that a molten alloy similar to that of Example 1 was cast into a water-cooled Cu mold and a slab having a thickness of 50 mm was used instead of the alloy ribbon. Was prepared, and each property was measured. Table 1 shows the results. The composition of the obtained slab was the same as in Example 1.

[0016]

[Table 1]

Example 2 A rare earth bonded magnet sample was prepared in the same manner as in Example 1 except that the step of holding the alloy ribbon at 1220 ° C. for 1 hour in an argon atmosphere was replaced with the step of holding at 1190 ° C. for 1 hour in an argon atmosphere. Was prepared, and each property was measured. Table 2 shows the results
Shown in The liquid phase appearance temperature of the used alloy thin body was 120
0-1210C.

[0018]

[Table 2]

From the results shown in Table 2, the solution temperature of 1190 ° C. in Example 2 is the same as the liquid phase appearance temperature (12
00-1210 ° C.) or less, and a high coercive force could be achieved while maintaining the remanence magnetization at a high value. Further, since the maximum energy product is also improved, it is estimated that the squareness of the demagnetization curve is also improved.

Example 3 Sm, Co, Fe, Cu and Zr source metals were weighed to a predetermined composition and dissolved at 1450 ° C. under a reduced pressure argon atmosphere.
The obtained molten alloy was tilted through a tundish onto a Cu roll having a peripheral speed shown in Table 3 to continuously prepare various flakes (ribbons) having an average thickness of 0.3 mm. The alloy composition of each of the obtained ribbons was the same as in Example 1 within the range of the analysis error. Various rare earth bonded magnet samples were prepared in the same manner as in Example 2, except that each of the obtained ribbons was used instead of the ribbon prepared in Example 2. The residual magnetization (Br) and coercive force (Hcj) of the obtained rare-earth bonded magnet samples were measured by a conventional method. Table 3 shows the results.

Comparative Example 2 Various rare earth bonded magnet samples were prepared in the same manner as in Example 3 except that the peripheral speed of the Cu roll in preparing the ribbon was changed as shown in Table 3, and the characteristics were measured. did. Table 3 shows the results.

[0022]

[Table 3]

From the results shown in Table 3, it can be seen that the remanent magnetization Br decreases in the range of the peripheral speed of the strip cast roll. It is expected that this is mainly due to a decrease in the degree of crystal orientation in the pressing step as the structure of the ribbon becomes finer. On the other hand, it can be seen that the coercive force (Hcj) decreases at a low peripheral speed of the roll. From the above, it can be seen that there is an optimum region for the roll peripheral speed.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Sadaaki Nakamatsu 4-14-34 Fukaekita-cho, Higashinada-ku, Kobe-shi, Hyogo Santokunai F-term (reference) 5E040 AA03 AA20 BB05 CA01 HB07 HB17 HB19 NN17

Claims (2)

[Claims] 1. An alloy melt for a rare earth bonded magnet containing Sm ₂ Co ₁₇ based rare earth magnet powder containing Sm, Co, Fe, Cu and Zr is injected into a cooling roll rotating at a peripheral speed of 0.1 to 20 m / sec. And continuously solidifying it to a thickness of 1 mm or less to obtain an alloy ribbon, followed by solution heat treatment, aging heat treatment and pulverization. 2. The method according to claim 1, wherein the solution heat treatment is performed at a temperature not higher than the temperature at which an alloy liquid phase appears.