JPH02288306A - Manufacture of rare earth permanent magnet - Google Patents

Abstract

PURPOSE:To advance a granulation property and a magnetic field or orientation property by adding 1.5-4.0wt.% of di-n-butyl phthalate to an alloy powder before molding in a magnetic field. CONSTITUTION:An alloy consisting of Sm (Co, Fe, Cu, Zr) is smashed finely into particles having an average diameter of 3mum and into the resultant alloy powder, 1.5-4.0wt.% of di-n-butyl phthalate is mixed with using fluorine hydrocarbon as a solvent and these are granulated by tumbling. By adding the di-n- butyl phthalate, the di-n-butyl phthalate is adsorbed to the surface of the alloy powder so as to cover that surface, thereby decreasing a frictional force of the alloy powder and accordingly increasing a magnetic field orientation property at the time of molding. In addition, as there is no bad influence upon a sintering process, the characteristics of magnets can be improved. Also, the di-n-butyl adsorbed layer on the alloy powder surface acts to improve the granulation property and to prevent oxidization.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing rare earth permanent magnets, typified by samarium-cobalt permanent magnets.

[Conventional technology]

In the conventional powder metallurgy method for manufacturing rare ±R magnets, additives such as lubricants are generally not used because the alloy is highly reactive.

To improve these points, the Special Public Interest Publication Act of 1986-
No. 36366, 1 ht! of di-n-butyl phthalate was added to the alloy powder before compaction in a magnetic field. This is a manufacturing method by adding the following.

(Problems to be Solved by the Invention) When manufacturing rare earth permanent magnets by powder metallurgy, it is important to use granulated powder with good fluidity for cost reduction.
The publication does not mention granulation properties, and in fact,
If alloy powder is granulated within this range, good granulated powder cannot be obtained.

This invention was made to solve the above problems, and aims to provide an additive that can improve granulation properties without adversely affecting magnetic properties.

[Means to solve the problem]

In the method for producing a rare earth permanent magnet according to the present invention, di-n-butyl phthalate is added in 1.
It is characterized by adding 5 wt% to 4.0 wt%.

[Effect]

In the method for producing a rare earth permanent magnet according to the present invention, by adding di-n-butyl phthalate, the surface of the alloy powder is adsorbed and covered with di-n-butyl phthalate, so that the frictional force of the alloy powder is reduced. Improves magnetic field orientation during molding. Moreover, since it does not have an adverse effect on the sintering process, the magnetic properties can be improved. Furthermore, the di-n-butyl phthalate adsorption layer on the surface of the alloy powder improves granulation properties and acts as an antioxidant.

〔Example〕

Examples of the present invention will be described below.

An alloy consisting of 5sz (Car Fe+Car Zr)+t was pulverized to an average particle size of 3-. The obtained alloy powder was mixed with di-n-butyl phthalate in an amount of 0 wt % to 4.0 wt χ using a fluorocarbon as a solvent, and granulated by transfer. As a result, good granulated powder was obtained by transfer granulation when the amount of di-n-butyl phthalate added was 1.5 wLX or more.

Furthermore, the obtained granulated powder was pressure-molded in a magnetic field. This molded body was heated at 1200°C in a vacuum and argon atmosphere.
After sintering for 1 hour, it was solution-treated at 1170°C for 1.5 hours, quenched, and then multi-stage aged between 800°C and 400°C. Figure 1 shows the measurement results of the magnetic properties of the obtained magnet.
From this, the addition of di-n-butyl phthalate improved Br, (OH)+++ax, and increased to 2.5wt.
It was found that after reaching a peak value near
As described in Publication No. 6, addition of 1.0 wt% or more does not cause deterioration of magnetic properties.

Therefore, by adding 1.5 wt% to 4.0 wt% of di-n-butyl phthalate to the alloy powder before magnetic compaction, the magnetic properties and granulation properties are improved.

The above example is based on Smt(Cot Fe, Car Z
Regarding the production of samarium cobalt magnets represented by r)+t, similar effects of addition of di-n-butyl phthalate were generally observed in RJ+-based and RMs-based rare earth permanent magnets.

〔Effect of the invention〕

According to this invention, the magnetic properties of the rare earth permanent magnet and the granulation properties of the alloy powder are improved.

[Brief explanation of drawings]

Figure 1 shows the amount of di-n-butyl phthalate added, the residual magnetic flux density Br, and the maximum energy product (B
It is a graph which shows the relationship of H)+wax. Applicant: Seiko Electronic Components Co., Ltd. Representative: Patent Attorney: Keinosuke Hayashi

Claims (1)

[Claims] From alloy powder whose main components are rare earth metals and transition metals,
In a method for producing rare earth permanent magnets by powder metallurgy, in order to improve granulation properties and magnetic field orientation, 1.5 di-n-butyl phthalate is added to the alloy powder before compaction in a magnetic field.
A method for producing a rare earth permanent magnet, characterized in that wt% to 4.0wt% is added.