JPS61287104A - Method for pulverization of permanent magnet alloy powder - Google Patents

Abstract

PURPOSE:To obtain the titled alloy powder of magnetic characteristics of very large maximum energy product with which the industrial value of the alloy powder is greatly enhanced by a method wherein the R-B-Fe alloy powder of the specially designated mesh or less is jet-milled into the specific average grain size using Ar gas or N2 gas or the mixture of said two types of gas. CONSTITUTION:The component range of R-B-Fe permanent magnet alloy powder is composed of Fe of 40-90atom%, B of 2-28% and R (rare-earth metal containing Y) of 8-30% as essential ingredients, for example, one or more kinds of specific element of the prescribed percentage or less is contained, and the average grain size of the powder is set at 1-10mum. It is difficult to pulverize the alloy powder into the average grain size of 1mum or less by performing jet milling and its magnetic coercive force is reduced when the average grain size exceeds 10mum. Also, the grain of the jet-milled alloy powder is set at 28 meshes or less. The alloy powder exceeding 28 meshes can not be formed by the jet milling. Ar gas, N2 gas or the mixture of them is used as the gas for the jet milling.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pulverization method for improving the magnetic properties of a B-B-Fe permanent magnet alloy.

(Prior Art) In recent years, Sm and C, which have higher magnetic properties and are more expensive in terms of resources than conventional &n-Co magnets, have been used.

A Nd-B-Fe based permanent magnet containing no Nd-B-Fe was invented.

(Sayo et al., J. Appl., Phys.55(d),
15March.

1984 F2085-2087. and JP-A-59-
No. 416008.

59-215460, 59-217504, and 59-222564), especially JP-A-59-2
Publication No. 15460 proposes that alloy powder with an average particle size of 0.5 to 80μ is compacted and sintered in a reducing or non-oxidizing atmosphere, and at the same time melting, crushing, and compacting are performed in the same atmosphere. This is disclosed.

The fine pulverization is carried out by wet pulverization in a solvent.

Furthermore, JP-A-59-217S04 states that in addition to the above-mentioned wet pulverization, dry pulverization in an inert gas atmosphere is also possible.

(Problems to be solved by the invention) However, there is no detailed mention of the specific type of gas used in dry pulverization, and wet pulverization in an organic solvent by the conventional method does not have sufficient magnetic properties. There were problems such as not being able to obtain

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above and to provide a method for pulverizing a B-B-Fe permanent stone alloy powder that provides excellent magnetic properties.

(Means for solving the problem) The method for pulverizing permanent magnet alloy powder of the present invention includes as essential elements:
R (However, 几 is at least 1'm of rare earth elements including Y.
), B and n containing unavoidable impurities, the following alloy powder is jet-milled with Ar gas or N, gas, or a mixture of both to obtain an average particle size of 1 to 1.
It is characterized by having a thickness of 0 μm.

(Effect) In order to make the average particle size less than 1 μm, the jet of this method
This is because it is difficult to grind by milling, and if the number exceeds 10, the coercive force decreases. In addition, the particle size of the alloy powder supplied to the jet mill grinding was set to 28 mesh or less.
This is because alloy powder exceeding 28 mesh is difficult to be pulverized with a jet mill.

Further, the bottom range of the B-B-Fe permanent magnet alloy powder to which the present invention can be applied is as follows.

That is, F e * of 40 to 90 qII in atomic percentage
2-28 T.

B, 8 to i% of R (rare earth metals including Y) are required, and one or more of the following A elements below the specified excellence (however, 2
The permanent magnet alloy contains (the content of element A is less than or equal to the maximum value of the contained elements).

T, 45% or less Ni 8% or less Co 50% or less Bi
5% or less V9.5% or less Nb 12.5% or less Ta 1 (L5% or less Cr 8.5% or less Mo
9.5To or less W9.5% or less M118% or less Al1
．． 5% or less Sb2.5g1 or less (37% or less Sn&
5% or less Zr & 5% or less Hf 5.5% or less Cu
15% or less S 2. Low or less C4% or less Ca 8
1 or less Mg 8 f6 or less 8i 8To or less 0
1'14 or less P 55- or less Within the above composition of the permanent magnet alloy, magnetic properties (BH) of conventional hard ferrite magnets (BH) MAX 41GDe or more can be obtained.

(Examples) Next, examples of the present invention will be described, but the present invention is not limited to these examples.

Example 1 Electrolytic iron with a purity of 99.9wt% as a raw material, 99.0w
t% of B and Nd with a purity of 99.7wt% or more
Using 147%Nd-7,5%B-
Weigh and inert (Ar) to obtain the final sintered body of the remaining re.
An alloy ingot was obtained by melting in a gas. The alloy ingot was crushed into a coarse powder of 52 mesh or less using a jig crusher and a brown mill, and then a jet mill was used to turn it into a fine powder for molding with an average particle size of 2.8 to 50 μm under a molding pressure of 5 tons.
/cIi in a magnetic field (H3KOe) to obtain a molded body. However, on the actual flow side, the gas used in the jet mill is Ar gas (99.998% purity).

The crushing pressure was 8 Kf/sj using an oxygen amount of 2 ppm and a nitrogen amount of 10 ppm. The obtained compact was sintered in Ar gas (1085°C x 3 hours), cooled to room temperature at a cooling rate of 15°C/min, heated again, subjected to aging treatment at 680°C x 2 hours, and then rapidly cooled to room temperature. Specified dimensions (10X10X
10) After processing, the magnetic properties were measured.

The results are shown in Table 1 as Example 1.

The following is a blank Table 1 (% indicates volume ratio) Examples 2 to 6 The same as Example 1 except that the gas used during jet mill pulverization was changed as shown in Table 1.

However, the Ar gas used was the same as in Example 1, and N
A commercially available gas having a purity of 99.999% and an oxygen content of 5 ppm was used. The results are shown in Table 1.

Comparative Example 1 The same as Example 1 except that the jet mill grinding in Example 1 was changed to ball mill grinding.

Ball milling was performed using steel balls with a diameter of 10 m in a trichloroethane solution. The finely pulverized powder had an average particle size of 2.9 μm, and was subjected to molding after vacuum drying.

As shown in Table 1, the maximum energy product (BH) MAX-550 to 55.8 MQO6 can be obtained when the gas used for jet mill grinding is Ar gas or synthetic gas, but the conventional method It can be seen that fine pulverization using a ball mill results in a decrease of 518 MGOe.

(Effect of the invention)

Claims (1)

[Claims] 1. An alloy powder of 28 mesh or less consisting of R as an essential element (R is at least one rare earth element including Y), B, and Fe containing unavoidable impurities is mixed with Ar gas or N_2 gas or a mixture of both. A method for pulverizing permanent magnet alloy powder, which comprises jet milling with gas to obtain an average particle size of 1 to 10 μm.