JPH04124202A - Compacting assist agent of alloy powder for rare earth element series permanent magnet - Google Patents

Abstract

PURPOSE:To manufacture a rare earth elemental permanent magnet having excellent magnetic characteristic by using the rare earth metal powder as a raw material, by using a mixed material of one kind of polyoxyethylene compound and lubricant as compacting assist agent. CONSTITUTION:This invention is related to the compacting assist agent for the alloy powder for rare earth elemental permanent magnet composed of the mixed material of at least one kind of the poloxyethylene compound selected among polyoxyethylene sorbithan fatty acid ester, polyoxyethylene sorbitor fatty acid ester, polyoxyethylene alkyl amine and polyoxyethylene derivative and the lubricant, and HLB value in the case of testing as nonionic surface active agent to the polyoxyethlene compound is desirable to be <=15.0. Further, as the lubricant, paraffin, camphor, etc., is available. Further, the suitable mixing ratio of the above polyoxyethylene compound to the lubricant is 1:5-1:1 by wt. ratio and particularly near 1:2 the most suitable ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a forming aid for rare earth alloy powder for permanent magnets, particularly REzPe+a[+ series, RECoB series or REzCO+7 series (where RE is a lanthanoid containing Y). It is suitable for use in molding alloy powders such as at least one selected from among the elements.

(Prior Art) With the recent demand for smaller size and higher efficiency of electrical and electronic equipment, permanent magnet materials are also required to have higher performance. Therefore, as a response to such requests, RE
-Co-based permanent magnets and RE2Fe+Jt-based permanent magnets (Japanese Patent Publication No. 59-64739), and furthermore, in the RECo system, part of the Co, and in the REJe, B, system, part of the Fe is Rare earth permanent magnets substituted with one or more transition metal elements and other property-improving elements have been proposed.

Such rare earth magnets are characterized by uniaxial magnetic anisotropy, and by taking advantage of this property, raw material alloy powder is press-molded in a magnetic field and then sintered to create permanent magnets with good crystal orientation. is manufactured.

However, during molding, if only the raw material powder is pressure molded as it is, the die wall surface will be 11! Rubbing tends to cause scratches, chips, cracks, etc. on the die surface and the surface of the molded body, which is a serious cause of deterioration in quality and productivity.

Conventionally, as a solution to such problems during molding, binders such as paraffin, stearic acid, bisamide, or metal soap have been added.

However, not only does paraffin have a small shaping effect, but if a large amount is used, it cannot be removed sufficiently in the subsequent sintering process, and carbon remains in the sintered body, resulting in deterioration of magnetic properties. Furthermore, stearic acid, bisamide, metal soap, and the like have the drawback that it is difficult to uniformly disperse them into the raw material alloy powder, and the strength of the molded product decreases.

For these problems, Japanese Patent Application Laid-Open No. 61-34101,
JP-A-60-184604 and JP-A-60-1
84605, etc., at least one selected from polyoxine ethylene alkyl ether, polyoxine ethylene monofatty acid ester, and polyoxine ethylene alkyl allyl ether, and furthermore, these polyoxine ethylene compounds, paraffin, ginger, and stearin. A molding improver mixed with existing lubricants such as acid salts has been proposed.

However, the effect of adding such a molding improver was not sufficient from the viewpoint of crystal orientation, although Br was somewhat the same.

(Problems to be Solved by the Invention) This invention advantageously solves the above-mentioned problems, and it goes without saying that it has excellent dispersibility in alloy powder, and has a high lubricating effect, so it can be used in a magnetic field. The purpose of the present invention is to propose a molding aid for alloy powder for rare earth permanent magnets, which can significantly improve moldability and crystal orientation during powder molding, and can also obtain high residual magnetic flux density.

(Means for Solving the Problem) That is, the present invention provides at least one polyoxyethylene compound selected from polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene alkylamine, and polyoxyethylene derivative. This is a forming aid for alloy powder for rare earth permanent magnets, which consists of a mixture of powder and lubricant.

In this invention, the HLBM of the above polyoxyethylene compound when viewed as a nonionic surfactant is 1.
5.0 or less is desirable.

Further, as the lubricant, paraffin, ginger, etc. are advantageously suitable.

Further, the preferred mixing ratio of the polyoxyethylene compound and the lubricant is 1:5 to 1:1 by weight, especially 1:1.
:2 neighborhood is optimal.

(Function) A rare earth magnet can be manufactured using the molding aid according to the present invention in the following manner.

That is, a predetermined amount of the polyoxyethylene compound and a lubricant are mixed in an organic solvent (cyclohexane, hexane, benzene, toluene, petroleum benzene, etc.), and this solution is added to 100 parts by weight of the raw material alloy powder in the solution. Adding an amount such that the proportion of the molding aid is about 0.01 to 0.5 parts by weight,
After mixing, the mixture is press-molded in a magnetic field. The obtained molded body is then degreased at a temperature of 600° C. or less in an inert atmosphere or in a vacuum, and then sintered. It is desirable to do this in the current.

(Example) Example 1 Nd1s (Feo,
56Coo, 1oNio, + 4)? 100 parts by weight of a fine alloy powder having a composition of 7Bl1 is mixed with 20 to 35 parts by weight of cyclohexane in which each molding aid shown in Table 1 (sample grades 1 to 6) has been dissolved in advance, and a slurry (based on the fine alloy powder) is mixed. The blending ratio of the molding aid was 0.10 to 0.30 parts by weight).

This slurry was then heated in a transverse magnetic field of 12 koe for 2
．． Width: 15 cm, length: 15 cm, height: 1 at a pressure of 0t/cm"
After pressure molding into a rectangular parallelepiped of 0mm, room temperature, 300℃,
10-2 hours each at 400'C and 600'C
'~10-'' Degreased in a Torr wave flow, sintered in vacuum at 1060°C for 1 hour, then sintered in 1 atm Ar at 1060°C for 1 hour, and then further aged. A sintered magnet was produced.

Table 1 also shows the results of examining the degree of crystal orientation a and magnetic properties of the sintered magnet thus obtained.

Table 1 also shows, as a comparative example, a case in which no molding aid was added (sample 7), and a mixture of liquid paraffin and conventionally widely used polyoxyethylene lauryl ether or polyethylene glycol monolaurate. The investigation results for the cases (Samples Nos. 8 and 9) are also shown.

Here, the degree of crystal orientation a was determined as follows from the X-ray diffraction intensity I (hkl) in a plane perpendicular to the magnetization direction.

Here, P and Po are respectively included in the total diffraction peak of C
Plane = shows the ratio of diffraction peaks accounted for by the (001) plane.

Example 2 Nd1s (Fe
o, 5bCoo, 1oNio, + 4) 7Js
100 parts by weight of alloy fine powder having the composition and 20 to 35 parts by weight of benzene in which molding aids (sample numbers 10 to 15) shown in Table 2 have been dissolved in advance are mixed, and a slurry (molding aid for the alloy) is mixed. The blending ratio was 0.25 to 0.30 parts by weight).

This slurry was then pressure-molded in a transverse magnetic field of 12 kOe in the same manner as in Example 1, and then molded at room temperature, 300°C and 600°C for 2 hours each for 10-' to 10-''T.
Degreased in A1 stream of orr and heated at 1060°C in vacuum for 1
A sintered magnet was produced by sintering for a time and then further aging treatment.

Table 2 also shows the results of examining the degree of crystal orientation a and magnetic properties of the sintered magnet thus obtained.

As is clear from Tables 1 and 2, when the molding aid according to the present invention is used, the crystal orientation of the sintered magnet is significantly improved compared to the conventional one due to the improvement of the internal lubrication effect, and the magnetic The characteristics, especially the residual magnetic flux density, are improved.

(Effects of the Invention) The molding aid of this invention not only has high dispersibility in alloy powder but also has excellent lubricating action, so it can not only significantly reduce the friction between the die surface and the molded body, but also The orientation is also significantly improved, and as a result, the magnetic properties can be improved.

Claims (1)

[Claims] 1. For use in rare earth permanent magnets, comprising a mixture of at least one polyoxyethylene compound selected from polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene alkylamine, and polyoxyethylene derivatives and a lubricant. A molding aid for alloy powder.