JPH0817248B2 - Method for manufacturing temperature sensitive element material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a temperature-sensitive element material composed of a ferromagnetic material whose magnetic anisotropy changes with temperature. More specifically, the transition temperature range is room temperature. Manufacture of temperature-sensitive element materials in which the transition temperature range is shifted to the high temperature side by sintering in a magnetic field at room temperature without heating, using a spin-rearrangement-type ferromagnetic substance and a metal fine powder that are lower than It is about the method.

[Prior Art] A ferromagnetic material in which the easy magnetization direction changes with temperature is called a spin rearrangement type ferromagnetic material, and a typical example thereof is a rare earth cobalt compound. The RCo ₅ type compound (R represents a rare earth element) has a hexagonal crystal structure.
The spin rearrangement phenomenon is a phenomenon in which the direction of the easy axis of magnetization changes from the P plane (base surface of the crystal) to the C axis direction with a temperature change, and transitions in the temperature region where the easy axis of magnetization changes from the P plane to the C axis. The angle formed between the temperature axis and the C axis and the easy magnetization axis is expressed as β.

Regarding the crystal magnetic anisotropy of rare earth cobalt compounds,
Generally, it is divided into an R sublattice that considers only R and a Co sublattice that considers only Co. The contribution from the R sublattice to the magnetocrystalline anisotropy constant is significant at low temperatures, and the contribution from the Co sublattice extends over a wide temperature range. Therefore, the contribution from the Co sublattice is important in the temperature range above room temperature, and the Co sublattice is C-axis oriented.

From the above, there are the following three techniques for changing the transition temperature of the rare earth cobalt compound.

The basal plane orientation of the R sublattice is changed depending on the composition of the rare earth element. Y _0.25 Nd _0.75 Co ₅ , NdCo ₅ , Dy _0.9 Sm _0.1 Co ₅ , Dy
When the temperature characteristic of β (degrees) is examined for the composition shown in Co ₅ , it becomes as shown in FIG. 4, and it is found that the transition temperature band changes depending on the composition of the rare earth element.

The C-axis orientation is changed by substituting a part of Co with the third element. For this, detailed data are described, for example, in Japanese Examined Patent Publication No. 60-1940.

The value of the ratio Z of rare earth element and cobalt is changed. As shown in FIG. 5, the transition temperature range can be changed by changing the Z value in DyCo ₂ in the range of 4.4 to 5.5.

In this way, temperature-sensitive element materials having a desired transition temperature range can be obtained depending on the type and composition ratio of the material elements, and these are applied to energy conversion devices as well as temperature-sensitive switches, temperature-sensitive valves, thermometers, etc. Etc. are also considered.

By the way, in order to utilize such a spin rearrangement phenomenon, it is necessary to manufacture a temperature-sensitive element material in which crystal directions are well aligned. A single crystal is a material having a uniform crystal orientation, but it is unsuitable as an industrial material because of its low productivity.

Therefore, as disclosed in JP-B-58-47842, a method for simply producing a temperature-sensitive element material having good crystal orientation has been invented. The feature of this manufacturing method is that when press-molding a fine powder of spin-rearrangement-type ferromagnetic material in a magnetic field, the material is heated to a temperature above the transition temperature range (for example, about 150 ° C). Aligning the directions of the crystal axes. By firing this molded body at 1100 to 1200 ° C., a high density and highly oriented sintered body can be obtained.

[Problems to be Solved by the Invention] As described above, in the prior art, the temperature of the fine particles of the spin rearrangement type ferromagnetic substance exceeding the transition temperature range (about 150 ° C.)
However, the following problems were encountered.

If the fine powder is a metal, it becomes easy to burn, so press molding in a magnetic field must be performed in an inert gas.

When heating the fine powder, the entire powder must reach a predetermined temperature or higher to the inside, which takes time.

The molding die must be made of heat-resistant material and structure.

As a result, the press molding apparatus becomes complicated and expensive, and it takes time in the molding process, resulting in poor workability.

The object of the present invention is to eliminate the drawbacks of the prior art as described above, to perform molding in a magnetic field at room temperature without heating the raw material powder during the powder compacting step, and finally to obtain an axis of easy magnetization exceeding room temperature. Direction is parallel to the C-axis direction of the crystal,
An object of the present invention is to provide a method capable of easily manufacturing a highly oriented temperature sensitive element material.

[Means for Solving the Problems] In the present invention capable of solving the above-mentioned technical problems, fine particles of a spin rearrangement type ferromagnetic material having a transition temperature range lower than room temperature and R′M′z ′ ( However, R'is one or more rare earth elements, and M'is Al, Si, V, Fe, Co, Ni, Cu, Nb, M.
1 or 2 or more of o, mixed powder with fine metal powder represented by 4.4 ≦ Z ′ ≦ 5.5) is molded in a magnetic field at room temperature and then the transition temperature range is shifted to a high temperature side by sintering. A method for producing a temperature-sensitive element material in which the direction of the easy axis of magnetization exceeds room temperature and the direction of the easy axis of magnetization is parallel to the C-axis direction of the crystal.
In the present invention, "room temperature" means about 25 ° C.

The spin rearrangement type ferromagnetic material used here is, for example, RM ₂ (where R is one or more rare earth elements, M is an intermetallic compound in which cobalt or a part thereof is replaced with a third element, 4.4 ≦ Z ≦ 5.5),
An appropriate composition is selected according to the application and the fine metal powder to be added.

The composition of the fine metal powder containing rare earth elements was obtained by many experiments. The value of Z'is set to 4.4 ≤ Z '≤ 5.5 because the composition of the temperature-sensitive element material finally obtained as shown in Fig. 5 shows that the orientation is deteriorated when the value of Z is less than 4.4 or more than 5.5. Because it is remarkable. The composition of the metal fine particle powder to be actually used and the mixing ratio with the spin rearrangement type ferromagnetic material are determined in consideration of the transition temperature zone, the orientation and the like. The mixing ratio is preferably 0.01 mol or more and 0.60 mol or less with respect to 1 mol of the spin rearrangement-type ferromagnetic material, and the fine metal particle powder. This is because if it is less than 0.01 mol, the effect of raising the transition temperature band is small, and if it is more than 0.60 mol, the orientation is deteriorated, and in the extreme case, the rotation phenomenon does not occur.

[Operation] FIG. 1 shows a state in which a mixed powder of a fine powder of a spin rearrangement type ferromagnetic substance and a fine powder of a metal containing a rare earth element is press-molded in a magnetic field at room temperature according to the method of the present invention. In the spin rearrangement type ferromagnetic material 10 defined as described above, the direction of the easy axis of magnetization is parallel to the C-axis direction of the crystal at room temperature,
The C-axis direction is aligned with the direction of the external magnetic field H by press molding in a magnetic field as shown in FIG. Then, the fine metal powder 12 is dispersed and mixed so as to fill the gap of the spin rearrangement type ferromagnetic material 10.

A characteristic of the spin rearrangement type ferromagnetic material 10 alone is schematically shown by a broken line A in FIG. The transition temperature band Ta is on the lower temperature side than room temperature (25 ° C).

When such a compact is sintered, the atoms of the fine metal powder diffuse into the fine powder of the spin rearrangement-type ferromagnetic substance, and the composition changes. Depending on the changed composition, the solid line B in FIG. 2
As shown in (1), the transition temperature zone Tb shifts to the high temperature side, and finally, the temperature becomes higher than room temperature, and the direction of the easy axis of magnetization becomes a temperature-sensitive magnetic substance whose direction is parallel to the C-axis direction of the crystal. Therefore, the transition temperature range of the finally obtained temperature-sensitive magnetic substance can be adjusted by the composition of the spin rearrangement type ferromagnetic substance used, the composition of the fine metal powder particles, their mixing ratio and the like.

Example-1 Composition NdCo ₅ (the axis of easy magnetization becomes parallel to the C axis at about 13 ° C.) was melted in a high frequency melting furnace, and this was crushed to about 3 μm by a jet mill. To 1 mol of this powder, 0.5 parts of fine metal powder (about 3 μm) shown in Table 1 was used.
Mixed at a molar ratio. Mix these powders at room temperature (25
Press molding was performed in a magnetic field of 10 kOe at (° C). Then, it was sintered at a high temperature of 1000 ° C. or higher in an Ar atmosphere for 2 hours.

The transition temperature band of the temperature-sensitive element material thus obtained was determined using a temperature-sensitive rotator as shown in FIG. The temperature-sensitive rotator 20 has a structure in which a disc-shaped temperature-sensitive element material 24 serving as a sample is rotatably supported between the permanent magnets 22a and 22b.
Then, the orientation of the temperature sensitive element material 24 was measured while changing the ambient temperature. The measurement results are as shown in Table 1.

Example-2 Composition Nd (Co _0.97 Al _0.03 ) ₅ (the axis of easy magnetization becomes parallel to the C axis at about 20 ° C.) was melted in a high frequency melting furnace, and this was pulverized to about 3 μm by a jet mill. 0.005 mol of DyCu ₅ fine powder (about 3 μm) is added to 1 mol of this powder.
They were mixed at a ratio of 0.70 mol. These mixed powders were press-molded at room temperature (25 ° C) in a magnetic field of 10 kOe.
Then, it was sintered at a high temperature of 1000 ° C. or higher in an Ar atmosphere for 2 hours.

The transition temperature range of the obtained temperature-sensitive magnetic material is as shown in Table 2. This transition temperature was also measured by using a temperature sensitive rotator as shown in FIG.

From these experimental results, it was confirmed that the transition temperature zone can be shifted to a high temperature side and adjusted by mixing a predetermined amount of a predetermined metal fine particle powder, and high orientation can be obtained by molding in a magnetic field at room temperature. I knew that.

EFFECTS OF THE INVENTION Since the present invention is a method of adding fine metal powder to a spin rearrangement type ferromagnetic material having a low transition temperature band as described above, it can be molded in a magnetic field at room temperature without heating the raw material mixed powder,
Finally, a high-density, highly-oriented temperature-sensitive element material in which the direction of the easy axis of magnetization is parallel to the C-axis direction of the crystal beyond room temperature can be easily manufactured.

As described above, in the present invention, since molding is performed in a magnetic field at room temperature,
It is possible to avoid various harmful effects associated with heating as in the conventional technique, simplify the molding apparatus and reduce the cost, and facilitate the molding operation to increase the molding efficiency.

[Brief description of drawings]

FIG. 1 is a schematic view of a molded body obtained by the method of the present invention, FIG. 2 is an explanatory view showing a state in which the transition temperature zone is shifted to a high temperature side by the present invention, and FIG. 3 is a feeling used for measuring the transition temperature zone. It is explanatory drawing of a warm rotator. Further, FIG. 4 is a graph showing the influence of the composition of the rare earth element on the transition temperature zone, and FIG. 5 is a graph showing the influence of the value of Z on the transition temperature zone in DyCo ₂ . 10 ... Spin rearrangement type ferromagnetic substance, 12 ... Fine powder of metal,
14… Molded body.

Front page continuation (72) Inventor Haruhiro Yukimura 5-36-11 Shimbashi, Minato-ku, Tokyo, Fuji Electric Chemical Co., Ltd. (56) Reference JP-A-59-106106 (JP, A) JP-B-58- 47842 (JP, B2) JP 60-1940 (JP, B2)

Claims (3)

[Claims] 1. Fine particles of a spin rearrangement type ferromagnetic material having a transition temperature range lower than room temperature and R'M'z '(where R'is one or more rare earth elements and M'is Al. , Si,
One or more of V, Fe, Co, Ni, Cu, Nb, Mo, 4.4 ≦ Z ′
≦ 5.5) A powder mixture of fine metal powder is molded in a magnetic field at room temperature, and then the transition temperature band is shifted to a higher temperature side by sintering, and the direction of the easy axis of magnetization exceeds the room temperature and crystallizes. The method for producing a temperature-sensitive element material, wherein the temperature-sensitive magnetic material is parallel to the C-axis direction. 2. A spin rearrangement type ferromagnetic material is RM _Z (where R
Is one or more rare earth elements, M is an intermetallic compound in which cobalt or a part thereof is replaced with a third element, 4.4 ≦ Z
The method according to claim 1, represented by ≦ 5.5). 3. The method according to claim 1, wherein fine metal powder is mixed in a ratio of 0.01 mol or more and 0.60 mol or less with respect to 1 mol of the spin rearrangement type ferromagnetic material.