JPS61281505A - Magnetizing method of rare earth magnet - Google Patents

Abstract

PURPOSE:To realize saturated magnetization even under the magnetic field of low magnetization, by heating and magnetizing a rare earth magnet which comprises rear earth metal, iron, and boron. CONSTITUTION:A rare earth magnet comprising R-Fe-B as basic composition is heated at the temperature of 50-200 deg.C for magnetization. When R-Fe-B magnet is magnetized by high-temperature heating, with coersive force being low, saturated magnetization can be realized under the magnetic field of low magnetization. Replacing a part of Fe by Co enables both a curie temperature and temperature coefficient of Br to be improved, and besides magnetic performance, corrosion-proof property, and the like can be also improved with replacement by other group of transition metals. Thus, with the magnetization being low, the magnetizing device is miniaturized and simplified, to improve mass- productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of magnetizing a rare earth magnet whose basic composition is R-Fe-B. However, R is a rare earth metal.

[Summary of the invention]

The basic composition of the present invention is R-1! In a method of magnetizing a rare earth magnet made of e-B, saturation magnetization is made possible even with a low magnetizing magnetic field by heating the rare earth magnet to 50 to 200° C. for magnetization.

[Conventional technology]

Conventionally, rare earth magnets whose basic composition is R-Fθ-B are
Since the temperature coefficient of coercive force (iHc) is large, 1Hc is originally large, but by adding a small amount of heavy rare earth metal, iH.

This is improved by further increasing the value of iHc, so a high magnetizing magnetic field is required to magnetize this large iHc magnet.

[Problems and objectives to be solved by the invention] However, rare earth magnets with such a large iHa require a magnetizing magnetic field two to three times as strong as 1Hc when magnetizing, and therefore cannot be used with a low magnetizing magnetic field. Since saturation magnetization is not possible, sufficient magnetic performance cannot be obtained, and a high magnetizing magnetic field is required for saturation magnetization, making the magnetization process difficult and the magnetization device becoming larger and more complex. There are problems in that the cost is high and the quality is not stable.

The present invention solves the problem mentioned above, and its purpose is to enable saturation magnetization even with a low magnetizing magnetic field.

[Means for solving problems]

The method for magnetizing a rare earth magnet of the present invention has a basic composition of R-Tl.
It is characterized by magnetizing a rare earth magnet made of e-B by heating it to 50 to 200°C.

R-? The e-B magnet has a large iHo temperature coefficient, and although this performance is normally considered to be negative, it can be used in reverse for magnetization. That is, if the R-IFe-B magnet is heated to a high temperature to lower iHc and magnetized, saturation magnetization can be achieved with a low magnetizing magnetic field.

In addition, rare earth magnets whose basic composition is R, Fe, and B include IJ (1-IFe-B magnets are known, but R
As, Y, La, Os, Pr, Nd, Pm, Sm,
Eu, Gd, Tb, Dy, Ho.

One or more of the rare earth metals Ffr, Tm, Yb and Lu may be used, but didymium (Pr, -N
(1) and cerium didymium (Os-Pr-4a)' can also provide sufficient magnetic performance and are advantageous in terms of supply and price. Furthermore, IHC can be increased by adding a small amount of heavy rare earth metals such as Dy and Tb, and a substantial improvement in temperature characteristics can be achieved.

In addition, by replacing a portion of Feσ3 with OO, the Chieri temperature was improved, and the temperature coefficient of Br was also improved.
Substitution with other transition metal groups also improves magnetic performance, corrosion resistance, etc.

〔Example〕

The present invention will be described in detail below based on examples.

(Oao, ll Pro, 2 N(lo, 6 D70.
1) Melt and cast the alloy in an argon gas atmosphere using a high frequency melting furnace to obtain a composition of 1m 78670010 B8.The resulting alloy was made into magnetic powder using a stamp mill/ball mill, and oriented in a magnetic field of 15 KOe. Compression molded at a molding pressure of 151j/-, 1000~
Sintering was performed at an optimum temperature of 1200°C, and aging was performed at an optimum temperature of 400 to 1000°C. Table 1 shows the main magnetic properties of the obtained magnet.

Table 1 A sample with dimensions of φ2 x L5% was cut from this sintered rare earth magnet, and was heated at room temperature (comparative example) and at 12
13. In a state heated to 0° C. (according to the present invention). FIG. 1 shows a demagnetization curve obtained by measuring at room temperature using a VSM after being magnetized with a magnetizing magnetic field of KOa.

As is clear from FIG. 1, it can be seen that the comparative example is not sufficiently magnetized, whereas the present invention is almost saturated magnetized.

Next, by changing the magnetizing magnetic field to 3 to 30 KOe, magnetization was carried out at room temperature (comparative example) and in a state heated to 120°C (invention), and the demagnetization obtained by measuring at room temperature using VSM. (B H) max was calculated from the curve and shown in FIG. 2 as a relationship with the magnetizing magnetic field.

As is clear from FIG. 2, at a low magnetizing magnetic field of 10KO8 or less, the present invention exhibits higher magnetic performance than the comparative example. In addition, in the state of saturation magnetization with a high magnetizing magnetic field,
Although the comparative example shows slightly higher magnetic performance than the present invention, the comparative example is not practical considering the high magnetizing magnetic field required for saturation magnetization, and the present invention is also sufficiently practical. Demonstrates magnetic performance.

This is because 1) the Ic temperature coefficient of this rare earth magnet is large, so the IHO is small at high temperatures (4.5 K at 120°C).
Oe), making it possible to achieve saturation magnetization with a low magnetizing magnetic field.

〔Effect of the invention〕

As described above, according to the present invention, a large iHQ rare earth magnet is magnetized by heating it to 50 to 200 degrees Celsius, so the magnetizing field required for saturation magnetization is lower than that of conventional methods. As a result, magnetizing equipment has become smaller and simpler, which has great effects on improving mass productivity, reducing costs, and stabilizing quality.In addition, magnetization can only be performed with a low magnetizing field like radial multipole magnetization. It can be applied to devices that have been used with low performance due to unavoidable high performance, so it has great effects such as miniaturization and high performance of stepping motors and the like.

[Brief explanation of the drawing]

The last figure is a correlation diagram between the magnetizing magnetic field of the present invention and the comparative example and the magnet (B H) max magnetized by the magnetizing magnetic field. That's all for visiting [YuC] Ugirin L Shouki htn7” Rough Figure 1

Claims (2)

[Claims] (1) A method for magnetizing a rare earth magnet, which comprises heating a rare earth magnet whose basic composition is rare earth metal (R), iron (Fe), and boron (B) to 50 to 200°C to magnetize it. (2) The method of magnetizing a rare earth magnet according to claim 1, wherein a part of the Fe is replaced with at least one transition metal group other than Fe, such as cobalt (Co).