JPS61198704A - Manufacture of rare earth element-cobalt group magnet powder for resin magnet - Google Patents

Abstract

PURPOSE:To obtain magnet powder for a resin magnet having large residual flux density and a high maximum energy product by thermally treating a reaction product from a mixture, in which a samarium oxide, a praseodymium oxide and cobalt powder are compounded, in a predetermined manner, crushing the reaction product and bringing a composition to a prescribed value. CONSTITUTION:A mixture in which a samarium oxide, a praseodymium oxide and cobalt powder are compounded is heated and reduced, samarium and praseodymium formed are diffused into cobalt powder, and a reaction product from the mixture is kept for 30min or 5hr at a temperature of 600-900 deg.C. The reaction product is quenched at speed of 10 deg.C/min or higher than said temperature, and a thermally treated material acquired is charged into water and brought to a slurry state, treated by water and an acid aqueous solution, and crushed so that mean grain size extends over 3-10mum, thus manufacturing magnetic powder, a composition thereof is represented by Sm1-x, PrxCOz (0.05<=x<=0.4, 4.7<=z<=5.3). The powder is mixed with epoxy resin through a normal method, thus preparing a resin magnet.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the production of 1-5 rare earth element-cobalt magnet powder, which has excellent magnetic properties and is suitable for mBhf7ii stone, by a reduction diffusion method. Regarding how to.

[Conventional technology]

The 1-5 series rare earth base-cobalt gostone powder for resin magnets has a smaller particle size, which is optimal for obtaining high magnetic properties, compared to the 2-17 series, and therefore it has a smaller particle size than the 2-17 series. It is preferred because it is advantageous in terms of conformability, # during kneading and molding, dynamics, and uniformity. As a method of manufacturing such a 1-5 group magnet powder, rare earth element oxides, reducing agents such as metallic calcium, and Sibalt powder are mixed, and the mixture is filled into a container and heated with inert gas at normal pressure. A so-called reduction-diffusion method is employed, in which the reaction product is heated at 900 to 1100° C. in an atmosphere, the resulting reaction product is poured into water to form a slurry, and the slurry is treated with water and an aqueous acid solution.

However, due to rz, this method is limited to producing magnet powder having an average composition of 1-5 based on the reaction produced by reduction and diffusion. Therefore, when the magnet powder obtained by this method is finely pulverized, press-formed, and then heat-treated to improve its magnetic properties and used for sintered magnets, other known electrolytic methods may be used. This method is more effective in terms of magnetic properties and cost than using magnet powder obtained by the method or melting method, but if the magnet powder is used as it is for resin magnets, the magnetic In addition to not improving the properties, since this heat treatment process is not required after kneading with the resin, the magnetic properties are particularly poor, especially in terms of the magnetic flux density that is lower than that of the heat-treated magnet powder. The drawback was that it was significantly inferior to that of resin magnets.

[Problem that the invention seeks to solve]

In view of the above-mentioned circumstances, the present inventors conducted extensive research in order to obtain magnet powder for resin magnets that has an improved residual magnetic flux density and a high maximum energy product.

[Means for solving the problem] As a result, samarium and praseodymium produced by heating and reducing a mixture of samarium oxide, praseodymium oxide and cobalt powder are diffused into the cobalt powder, and the reaction product is After holding at 600 to 900°C for 30 minutes to 5 hours, heat treatment is performed by rapidly cooling at 10C/min or more from that temperature, the resulting heat-treated product is poured into water to form a slurry, and the slurry is treated with water and an acid aqueous solution. After that, it is crushed so that the average particle size is 3 to 10 μm, and the composition is Sm, 1-, Pr, Co, (however, 0.05≦x≦
The inventors have discovered that the above object can be achieved by obtaining magnetic powder having the following formula: 0.4, 4.7≦z≦5.3).

[For production]

The present invention will be explained in more detail below.

In the present invention, first, samarium oxide, praseodymium oxide, a reducing agent such as calcium, and cobalt powder are mixed, and the mixture is filled into a container and heated to 950 to 1200 ml under an inert gas atmosphere such as argon at normal pressure. Heat at ℃ for 30 minutes to 4 hours.

By doing this, samarium and praseodymium produced by reducing samarium oxide and praseodymium oxide are diffused into the cobalt powder. The reaction product produced by this reaction is subjected to a heat treatment in which the temperature is lowered to 600 to 900°C, held at that temperature for 30 minutes to 5 hours, and then rapidly cooled from that temperature at a rate of 10°C/min or more. In this heat treatment, if the heating is less than 600°C and less than 30 minutes, the effect of the heat treatment, which is to change the generated heterophase to a single phase of 1 = 5 system and to remove thermal strain and obtain a stable coercive force, cannot be obtained. On the other hand 9
If the temperature exceeds 00°C and exceeds 5 hours, the composition of the obtained magnet powder will tend to deviate from the limited range described below, and different phases other than the 1-5 system will be likely to be generated, so the heating conditions should be adjusted to 600 to 900°C.
The duration was 30 minutes to 5 hours. In addition, cooling after heating is 1.
It is necessary to perform the cooling at a cooling rate of 0.degree. C./min or more. This is because if the temperature is less than 10° C./min, different phases other than the 1-5 system are likely to be generated.

The obtained heat-treated product is poured into water to form a slurry, and the slurry is treated with water and an aqueous acid solution such as dilute acetic acid. This operation may be performed by a commonly used method. The resulting powder is further ground to an average particle size of 3 to 10 μm. If the average particle size is less than 3 μm, the residual magnetic flux density will decrease, while if it exceeds 10 μm, the coercive force will decrease, so the average particle size was adjusted to 3 to 10 μm.

The magnetic powder thus obtained has a composition of Sm,
, Pr, Coz (however, 0.05≦x≦0.4, 4.
7≦z≦5.3). If X is less than 0.05, the improvement in residual magnetic flux density by the addition of praseodymium will not be sufficient, while if X exceeds 0.4, the coercive force will decrease rapidly, and if 2 is less than 4.7, the manufacturing Different phases of 1-3 series and 2-7 series are generated in the magnet powder, which tends to lower the residual magnetic flux density.On the other hand, when Z exceeds 5.3, different phases of 2-17 series are generated and the coercive force decreases. This is because it tends to decrease.

〔Example〕

Hereinafter, the present invention will be explained with reference to examples.

Example I Sm, 03 powder, Pr5o+ powder, Co powder and 00 grains were blended to a predetermined composition (total amount 120-13Q
y) Ar
After being kept in the atmosphere for 3 hours, it was allowed to cool, and then water-cooled from 900°C. The resulting reaction product was treated with water and dilute acetic acid at a pH of about 2-5 to reduce Cα0. Unreacted C
α was separated and removed. The obtained powder was dried after the adhering moisture was replaced with ethyl alcohol.

Furthermore, these powders were pulverized using a rotating ball mill.

Table 1 shows the composition and average particle size of the fine powder sample thus obtained.

Table 1 Also, after heating at 1100°C for 3 hours in the above operation, the reaction product was heated as it was, taking 1 hour to lower the temperature in the electric furnace to SOO°C, and holding at that temperature for 2 hours. Further A
A fine powder sample was prepared in the same manner as described above, except that the sample was rapidly cooled by blowing t gas and the obtained heat-treated product was treated with water and an aqueous acid solution. The compositions and particle sizes of these powders are shown in Table 2.

Table 2 To the magnet powder prepared as described above, 5.0% by weight of epoxy resin was added and mixed as a resin by external cutting.
After compression molding in a KOe magnetic field at a pressure of 4 tOn/crl, the molded product was held in an oven at 120° C. for 2 hours to harden the epoxy resin. Table 3 shows the results of measuring the magnetic properties of the obtained resin magnet.

Table 3 Example 2 Tests N11l and 2 of Example 1 were mixed together (however, the total amount was 120-2609), and after being kept in an electric furnace maintained at 1100°C for 2 hours under At atmosphere, test N7I was mixed.
Lml was subjected to fine pulverization in the same manner as in Example 1 without heat treatment (test section 17), and test section 2 was heat treated by heating in a predetermined Ar atmosphere and then quenching by blowing Ar gas. Further, fine pulverization was performed in the same manner as in the heat-treated portion in Example 1 (test sections 18 to 27).

To the magnet powder prepared as above, 9.0% by weight of polyamide resin (nylon 6) was added as a resin by external cutting.
After addition, mixing, and pelletizing, injection molding was performed in a magnetic field of 10 KOe. Table 4 shows the results of measuring the magnetic properties of the obtained resin magnet.

(The following is a blank space) Table 4 [Effects of the Invention] As is clear from the above, the present invention has developed a 1-5 system suitable for resin magnets having improved residual magnetic flux density and high maximum energy loss by the reduction diffusion method. It can be manufactured by heat-treating rare earth element-cobalt magnet powder.

In addition, praseodymium, which partially replaces samarium, is more abundant and cheaper than samarium.
The industrial significance of the invention that can be made is very significant.

Claims (1)

[Claims] (1) A mixture of samarium oxide, praseodymium oxide and cobalt powder is heated and reduced, and the generated samarium and praseodymium are diffused into the cobalt powder,
The reaction product is heated at 600 to 900°C for 30 minutes to 5 hours and then rapidly cooled from that temperature at a rate of 10°C/minute or more.The resulting heat-treated product is poured into water to form a slurry. After treatment with water and acid aqueous solution, it is ground to an average particle size of 3 to 10 μm, and its composition is S
m_1_−_xPr_xCo_z (however, 0.05≦x
A method for producing rare earth element-cobalt-based magnet powder for resin magnets, characterized by obtaining magnet powder represented by the following formulas: ≦0.4, 4.7≦z≦5.3).