JPS5853055B2 - Manufacturing method of permanent magnet material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an intermetallic compound of a rare earth metal (hereinafter referred to as R) and Co, particularly an R2C017 permanent magnet.

The rare earth cobalt magnet used in the present invention includes samarium Sm 24 to 28 wt% and copper CuO to 20 wt%.
t%, iron FeO~35wt%, zirconium ZrO~
15 wt%, titanium TiO to 1 wt% (not including O), and the remainder substantially consists of cobalt Co. S m -C
u -F e -Z r -T 1-Co alloy,
This alloy has a large residual magnetic flux density (Br), a large coercive force IHc, a large energy product ((BH)max), a high Curie temperature, and is a permanent magnet with excellent magnetic properties.

Generally, permanent magnets of this type are obtained through manufacturing processes including melting, coarse and fine pulverization, molding in a magnetic field, sintering, and solution treatment (aging).

Melting is carried out in an inert atmosphere or vacuum by means such as a levitation arc or high frequency, and coarse and fine grinding is carried out in an iron mortar, Brown mill or ball mill, vibrating mill,
This can be done using a jet mill, etc.

Orientation and molding in a magnetic field are generally performed at the same time when using a mold, and the orientation magnetic field is usually 8 to 20 kOe.
The molding pressure is 0.5 to 10 ton/cfL.

Argon is used for sintering. It is carried out in an inert gas atmosphere such as helium He or in a vacuum at a temperature in the range of 1180°C to 1230°C.

Solution treatment generally proceeds simultaneously with sintering, but in some cases the two steps may be separated.

Heat treatment is carried out at a temperature range of 700 to 950°C,
A magnet having a large coercive force has the disadvantage that the demagnetization curve of the magnet characteristics is not squared.

The purpose of the present invention is to obtain Sm-Cu-Fe Zr-Ti
The purpose of this invention is to increase IHc in a Co six-element alloy and improve the squareness of the hysteresis curve, thereby providing a method for producing a permanent magnet material with a high energy product.

In the present invention, in the above-mentioned six-element alloy, the heating rate during firing is set to 250°C/hour or more, and the temperature rises to 1180°C to 12°C.
It is characterized by raising the temperature to 30°C.

The reason why we chose the firing temperature to be 1180 to 1230°C is because if it is lower than that, sintering will be insufficient and Br will decrease.
This is because the sintering progresses too much and the IHc and squareness deteriorate significantly.

Conventionally, the rate of temperature increase during firing was 50 to 50 bm from the viewpoint of cracks, etc., but this was not industrially preferable because it required a long period of time to increase the temperature.

However, as a result of intensive research into sintering, solution treatment, and heat treatment, the present invention found that the
It has become clear that the magnetic properties are significantly improved if the temperature is rapidly increased to 000° C./hour.

Sintering of rare earth cobalt magnets is carried out under conditions that do not cause the bulk powder to grow significantly in order not to impair IHc.As a result, conventionally the cooling rate was set at the same maximum sintering temperature, but in the present invention Sm-Cu-Fe
-Z r -T i -Co system, IHcp
This has a positive effect on the magnetic properties of improving Br and increasing the energy product.

The reason why the solution treatment was selected within the above-mentioned range in both Examples is that it was experimentally confirmed that polygonality and 1He are significantly reduced outside this temperature range.

In addition, the heat treatment temperature was selected to be in the range of 700 to 950°C. Below 700°C, the holding time becomes significantly longer, which is industrially disadvantageous, and above 950°C, the squareness significantly decreases and becomes high (BH). This is because they cannot be obtained.

Furthermore, the reason why the cooling temperature was set to 5°C/min or less is that if the temperature is higher than this, the precipitation of fine particles will be insufficient, resulting in poor squareness and He
This is because there is a significant decrease in

Moreover, the reason why it was cooled to 500° C. or lower is that if the temperature is higher than this, the squareness and He content will be significantly reduced.

In addition, the temperature increase rate during firing greatly affects the residual magnetic flux density Br and the energy product (BH), and 250°C/H
This is because Br1 (BH)max cannot be kept high below r.

It goes without saying that the present invention is applicable not only to permanent magnets with magnetic field anisotropy but also to isotropic magnets.

Example 1 Sm is 25.7 wt%, Cu is 8 wt%, Fe is 1
4.5wt%, Zr 1.5wt%, Ti O~1.0
The alloy was melted by high-frequency heating in an argon atmosphere so as to have a weight percent of Cobol.

Next, this alloy was roughly pulverized and then finely pulverized using a ball mill to an average particle size of about 4 μm.

These alloy powders were heated for 1 t in a magnetic field of 1.0 kOe or more.
Molding was carried out at a pressure of on/cnt.

The molded product was heated at 250°C/Hr at 1200°C in an Ar atmosphere.
After sintering for an hour, it was solution treated at 1180°C for 1 hour and then rapidly cooled.

After heat treating this sintered body at 800℃ for 1 hour, 5℃/m
The sample was cooled to 300° C. at a cooling rate of less than 1.5 in.

Figure 1 shows the magnetic properties of this sample.

Example 2 5m25.5wt%, Cu8.2wt%, Fe1
4.3wt%, Zr1.4wt%, TiO, 1wt%,
The alloy was melted, pulverized, and magnetically formed in the same manner as in Example 1 so as to obtain C0bal.

The molded product was heated to 1180 to 1230°C for 1 hour in an AAr atmosphere, and then sintered at 1180 to 1230°C for 1 hour.
Solution treatment was performed at 0 to 1200°C for 1 hour.

After that, hold at 700-950℃ for more than 10 minutes and then 5℃
The sample was cooled to 500'C at a cooling rate of /min or less.

The magnetic properties of this sample are shown in Figure 2.

[Brief explanation of drawings]

FIG. 1 shows a characteristic diagram of the amount of titanium added, the energy product, and the residual magnetic flux density. FIG. 2 shows a diagram of the relationship between the heating rate and the energy product residual magnetic flux density.

Claims (1)

[Claims] I5rn-COs C11s Fe, Z An alloy powder containing 1wt% or less of Ti in a composition mainly composed of r was heated at a rate of 250°C/Hr or more in an inert atmosphere and fired at 1180 to 1230°C. After 1150~1200
A method for producing a permanent magnet material, which comprises performing solution treatment at 700 to 950°C for 10 minutes or more, and then cooling to 500°C or less at a cooling rate of 5C/min or less.