JPS5848602A - Production of magnet of intermetallic compound - Google Patents

Abstract

PURPOSE:To improve the magnetic characteristics of a resin bound fine powder magnet with an alloy consisting of rare earth components and transition metal components as a raw material by applying a pretreatment of specific conditions to the raw material alloy. CONSTITUTION:An intermetallic compd. consisting of rare earth components such as Y, Sm, Pr, Nd, Ce and transition metals such as Co, Fe, Ni, Mn as raw materials for magnets are pulverized down to 3mu average grain sizes. After the powder is compression molded in a magnetic field, the moldings are sintered in an inert gas such as gaseous Ar and are slowly cooled down to about 300 deg.C at 5 deg.C/hr cooling rate. Thereafter the moldings are further reheated to 850 deg.C and are subjected to an aging treatment for the purpose of improving coercive force. After the sintered bodies are cooled quickly, the bodies are pulverized again and an epoxy resin is added at about 5wt% to the powder and both are mixed. The mixture is compression molded in a magnetic field and is calcined and solidified to the curing temp. of the resin, whereby the permanent magnet having excellent magnetic characteristics is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a permanent magnet containing rare earth elements and cobalt as main components, and particularly to a method for manufacturing a resin-bound fine powder magnet.

It is known that intermetallic compounds such as rare earth elements and cobalt have very large crystal magnetic anisotropy, and that when they are made into fine particles, they become excellent permanent magnets.

The manufacturing method can be roughly divided into sintering method and resin binding method.

FIG. 1 shows the manufacturing process of a sintered magnet, and FIG. 2 shows the manufacturing process of a resin-bound magnet. Each manufacturing method will be explained with reference to the drawings.

First, the manufacturing method for sintered magnets is based on the theory that an alloy having an appropriate composition for a sintered magnet is made into single-domain particles of several microns or less, then compression molded in a magnetic field, and then fired at an appropriate temperature. Dense L is promoted to 95% or more of the density, and the magnetic properties are improved.

However, during sintering, dimensional changes are very large, so secondary processing must be performed to obtain the required dimensions. However, since the material is hard and extremely brittle, ordinary machining is impossible, and machining is carried out exclusively by grinding with a Go grindstone or a diamond grindstone. It has the major disadvantage that processing costs are extremely high due to its hardness.

On the other hand, resin-bound magnets are made by pulverizing an alloy with an appropriate composition for resin-bound magnets into a powder of about 10 to 50 microns, mixing it with resin, and compression-molding it in a magnetic field. It is produced through a step of impregnating it with heat and solidifying it, but it does not require high-temperature firing, so it has the advantage of omitting secondary processing. However, in addition to the presence of non-magnetic resin, it is difficult to micronize powder particles to single-domain particles due to mechanical strain caused by oxidation and crushing, and the distribution of powder is poor, resulting in poor magnetic properties. The disadvantage is that it is considerably lower than that of sintered magnets.

The present invention has been made to solve the above drawbacks,
This is based on the fact that the magnetic properties of resin-bound magnets are significantly improved by pre-treating the raw material alloy in the process of manufacturing resin-bound magnets. That is, an alloy having an appropriate composition is once reduced to single magnetic domain particles of several microns or less, compression molded in a magnetic field, sintered at an appropriate temperature, cooled as slowly as possible to around room temperature, and then heated to 85°C.
It has been discovered that magnetic properties are improved by thermal aging at around 0°C.

The present invention will be explained below with reference to Examples.

[Example 1] First, a comparative sample was prepared by a known method according to the procedure shown in FIG. 2. In other words, Bm is shy@ in weight ratio
The containing 8m0O alloy is ground to an average particle size of 15 microns using a vibration mill, and about 5 wt% of epoxy resin is added to this powder.
They were added, mixed, and compression molded in a magnetic field. The obtained molded body was cured by heating to the curing temperature of the resin, and then its magnetic properties were measured.

The magnetic properties were as follows.

Br: 4500G, BHc: 43000・(BH)sa
g: 9 MG, Oe Next, the manufacturing method of the present invention will be explained with reference to FIG. /fi damp, 8m
An 8m0o alloy containing 55% by weight was prepared, and after being pulverized using a vibration mill until the average particle size of the powder became 3 microns, compression molding was performed in a magnetic field at 5 ton/ai.

Next, the compact was sintered in an argon gas atmosphere at 1050°C for 1 hour, and after sintering was cooled to 300°C at a cooling rate of 5°C/H. After this, the holes were reheated to -850°C and subjected to aging treatment to increase the coercive force. The sintered body 1 produced in this manner was used as a raw material, and thereafter crushed, molded, and heated to solidify under the same conditions as in the conventional method to produce a resin-bound magnet according to the present invention.

The magnetic properties at this time were as follows.

Br:6800G, BHc:55000e(BH)wa
x: 1 (14M-G, Oe [Example 2] The 8m0o alloy used in Example 1 as a comparison sample was pulverized to an average particle size of 10 microns using a vibrating mill, and after cooling, it was immediately compression-molded with S tO in a magnetic field. did.

Next, the molded product was immersed in an epoxy resin melt to impregnate the epoxy resin (in a reduced pressure atmosphere), and then heated and solidified to a curing temperature. The magnetic properties were as follows.

Br: 61300G, BHc: 50000s (13
1) Wax: Next, in the manufacturing method of the present invention, an 8m00 alloy containing 35% of Elm by weight was made into an average particle size of 3 microns using a vibrating orifice, and then the powder was compression molded in a magnetic field at S ton/i. The obtained compacted body was heated at 1050°C x 1 in argon gas.
After sintering under the conditions of 100 hrs., the sample was cooled to room temperature at a cooling rate of 1° C./M. Thereafter, it was reheated to 850C, and after heating, it was rapidly cooled in silicone oil.

Thereafter, samples of the present invention were produced by the conventional method described in Example 2 using the sintered bodies produced through the above steps as raw materials.

The magnetic properties at this time are Br near 200G, BHc: 65000s (13H)
m&s: 11 SM-G, os.

As described above, it is clear that the manufacturing method of the present invention improves the magnetic properties of the resin binder magnet. This improvement in magnetic properties is due to the fact that special heat treatment of the raw material alloy has the effect of improving coercive force, and that the powder is pulverized to single-domain particles as a pretreatment. It is assumed that the orientation is improved at the πth point.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the manufacturing process of a sintered magnet, FIG. 2 is an explanatory diagram of the manufacturing process of a conventional resin-bound magnet, and FIG. 3 is an explanatory diagram of the manufacturing process of a resin-bound magnet according to the present invention. that's all

Claims (1)

[Claims] RMs consisting of a rare earth component (one or a combination of two or more of Y, Sm, Pr, KLD, Ce, etc.) and a transition metal component (a combination of Co, Fθ, Ni, Mn).
In the production of resin-bound magnets, in which a finely powdered intermetallic compound is solidified with a resin binder, the composition as a raw material is made into single-domain particles of several microns or less, and then compression molded in a magnetic field, resulting in a molded product. After sintering at an appropriate temperature, it was slowly cooled to around room temperature, and then thermally aged at around 850°C.
A method for producing an intermetallic compound magnet characterized by rapid cooling from a processing temperature to room temperature.