JPS61214402A - Manufacture of sintered magnet - Google Patents

Abstract

PURPOSE:To control friction appearing between a molded body and a metallic mold, and enable industrial mass production of Nd-Fe-B permanent magnets based on by changing a mixture of raw material powders and zinc stearate into the molding space, subjecting the mixture to magnetic orientation and sintering process, followed by heat-treatment. CONSTITUTION:Molding raw material powders, which have been obtained by mixing raw material powders of 1-50mum mean grain size with zinc stearate in the range of 0.005-0.1wt%, is charged into the molding space, oriented in a magnetic field, molded, sintered at a temperature ranging from 900-1,200 deg.C and subjected to heat-treatment. If the added amount of zinc stearate is below 0.005wt%, little is improved in molding efficiency and reducing friction between the metallic mold and the molded body. On the other hand, if that amount exceeds 0.1%, the magnetic property of the sintered magnet obtained deteriorates significantly to lose a feature possessing such a high energy produce reaching 45MGOe as in the case of permanent magnets of a Fe-B-R family.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a method for manufacturing a Fe-B-R magnetic anisotropic sintered magnet, in which the I! I
The present invention relates to a method of manufacturing a sintered magnet that reduces iI.

[Prior art] Conventionally, Japanese Patent Application Laid-open Nos. 59-46008 and 59-64733
When manufacturing Fe-8-R magnetic anisotropic sintered magnets as described in the publications of the above issues, in the forming process, a component composition approximately corresponding to the final sintered magnet is used. After filling the molding space formed by the die and the lower punch with the raw material alloy powder, a constant magnetic field of approximately 10 KOe is continuously applied to the raw material powder until the upper punch descends to complete the consolidation of the raw material powder. was going on.

[Problems to be Solved by the Invention] However, unlike the conventional samarium-cobalt permanent magnet raw powder, in the molding of the Fe-B-R permanent magnet raw powder, the mold wall and molding The friction between the molded body and the molded body is excessive, and the shape and dimensions of the molded body are different from those expected. Also, the die must be replaced frequently, which reduces molding efficiency and increases the cost of the entire mold. There was a problem in that it caused an increase.

[Means for Solving the Problems] As a result of various studies, the inventor of the present invention discovered that Fe-B-R before molding.
By mixing powder of zinc stearate, which is extremely sensitive, into the raw material powder for magnets, the molding efficiency can be significantly improved, and the friction between the inner wall of the mold and the molded object can be significantly reduced. This discovery led to the completion of the present invention.

That is, the present invention has an atomic percentage of 8 to 30% R (wherein R is at least one kind of rare earth element including Y), 2 to 30%
28% B, 50% or less C0 15% or less additional element M
(However, M is Al, Ti, Ni.

C-Ca, Zn-MQ, CuNSi
-V -N b -Ta 1Cr %Mo, W, Mn
, Zr, Hf) and the remainder 1"
In the method for manufacturing a magnetically anisotropic sintered magnet consisting of e, raw material powder with an average particle size of 1 to 50 μm is mixed with zinc stearate in a range of 0.005 to 0.1 wt% to obtain a raw material powder for molding. is filled into the molding space formed by the die and lower punch, and after completing the molding by orienting the raw material powder using a magnetic field, it is sintered at a temperature within the range of 900 to 1200°C, and then heat treated. This is a characteristic feature.

[Effect] The amount of zinc stearate added is 0.005 to 0.1wt
A range of % is appropriate. The amount added is 0.005wt
If it is less than 0, twt, the effect on improving molding efficiency or reducing FJII between the mold and the molded object is weak, and
%, the magnetic properties of the obtained sintered magnet will deteriorate significantly and the feature of Fe-BR permanent magnets, which have a high energy product of up to 45 MGOe, will be lost. Also, the optimal range of the amount of zinc stearate added is 0.01
~o, oewt%.

Next, the method of applying a magnetic field will be described; Fe-B-R permanent magnet raw powder has the characteristic that once a strong direct current magnetic field is applied, the obtained orientation will continue indefinitely, and the higher the applied magnetic field strength, the more Since the degree of orientation is improved, it is advantageous to use a pulsed magnetic field for orientation. If the strength of the pulsed magnetic field is smaller than 20) (Qe), there will not be much improvement in the degree of orientation compared to the case of applying a normal DC magnetic field of 10KOe. Since the magnetic field generator becomes large-scale and the handling danger increases significantly, a pulsed magnetic field with a field strength of 20K Oe to 150K Q8 is appropriate.The timing of applying the pulsed magnetic field to the magnet raw powder is determined by the die After filling the raw material powder into the molding space formed by the lower punch and the lower punch, 1.
Although it is sufficient to apply it several times, the degree of orientation can be further improved by applying it many or several times.

EXAMPLES Hereinafter, misexposure will be described in more detail with reference to examples.

Example 1 Starting material: electrolytic iron with a purity of 99.9 wt%, purity 9
Using 9.5wt% electrolytic cobalt, 99wt% purity poron as B, and 99.7wt% or higher purity Nd as R, 15%Nd-8%B-5%C in atomic%
〇-Weigh to obtain the final sintered body of residual Fe, melt with high frequency, and cool with water! An alloy ingot was obtained by casting into a IIs type. After coarsely crushing the alloy ingot using a stamp mill,
It was made into a fine powder with an average particle size of about 3 μm using a jet mill. Zinc stearate powder was mixed with the obtained fine powder to prepare a raw material for molding. After filling the molding material into the molding space formed by the die and the lower punch, compression molding was performed by applying a pulsed magnetic field with a magnetic field strength of 32 KOe (so-called transverse magnetic field molding method in which the pressing direction and the orientation direction are perpendicular to each other). After sintering the obtained molded body at 1080°C for 1 hour in a non-oxidizing atmosphere,
Once held at 900°C for 1 hour, slowly cooled to room temperature, and then heated again at 6°C.
The mixture was treated at 60°C for 1 hour and rapidly cooled to room temperature.

Table 1 shows the results of comparing magnetic properties by varying the amount of zinc stearate powder added to the raw material fine powder.

Table 1 As shown in Table 1, by using a mixture of zinc stearate powder as the raw material for molding, the friction between the inner circumferential surface of the die and the molded object is significantly reduced, and the molding speed is reduced to approximately 3. I was able to double it. Repairs to the inner peripheral surface of the die were no longer necessary, and manufacturing efficiency was improved.

[Effects of the invention] According to the present invention, the friction between the mold and the molded body to the extent that conventional molding was impossible has been suppressed, opening the way to industrial mass production of Nd-1”e-Japanese permanent magnets. It was written.

Claims (1)

[Claims] 1. 8 to 30% R (wherein R is at least one kind of rare earth element including Y) 2 to 28% B, in terms of atomic percentage;
50% or less Co, 5% or less additional element M (however, M is A
l, Ti, Ni, C, Ca, Zn, Mg, CU, Si,
In a method for manufacturing a magnetically anisotropic sintered magnet consisting of at least one of V, Nb, Ta, Cr, Mo, W, Mn, Zr, Hf) and the remainder being Fe, raw material powder with an average particle size of 1 to 50 μm is used. , 0.005-0.1w zinc stearate
t% mixed to obtain a raw material powder for molding, this is filled into the molding space formed by a die and a lower punch, and after completing the molding by orienting the raw material powder by a magnetic field, it is heated at a temperature within the range of 900 to 1200 ° C. A method for manufacturing a sintered magnet, which comprises performing heat treatment after sintering. 2. After filling the raw material powder into the molding space, 20KOe ~
A pulsed magnetic field of 150 KOe is applied until the end of molding.
2. The method of manufacturing a sintered magnet according to claim 1, wherein the application is applied at least once to orient the raw material powder.