JPH0426523B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing 1-5 rare earth element-cobalt magnet powder having excellent magnetic properties and suitable for use in resin magnets by a reduction diffusion method. [Prior art] 1-5 series rare earth element-cobalt magnet powder for resin magnets has a smaller particle size, which is optimal for obtaining high magnetic properties, compared to 2-17 series magnet powder.
Therefore, it is preferably used because it is advantageous in terms of compatibility with resins, fluidity and uniformity during kneading and molding. As a method for manufacturing such 1-5 series magnet powder, rare earth element oxides, reducing agents such as metallic calcium, and cobalt powder are mixed, the mixture is filled, and the mixture is filled with the mixture and then heated under an inert gas atmosphere at normal pressure.
After heating at 900 to 1100° C., the resulting reaction product is poured into water to form a slurry, and the slurry is treated with water and an acid aqueous solution, a so-called reduction diffusion method. However, this method only produces magnet powder having an average composition of 1-5 as a reaction product by reduction and diffusion. Therefore, the magnet powder obtained by this method is finely pulverized, press-formed, and then heat-treated to improve its magnetic properties, and when used for sintered magnets, other known electrolytic This method is more effective in terms of magnetic properties and cost than using magnet powder obtained by the method or melting method. Therefore, the magnetic properties have not been improved, and since this heat treatment process cannot be applied after kneading with the resin, the magnetic properties are
In particular, the residual magnetic flux density was significantly inferior to that of resin magnets made from heat-treated magnet powder. [Problems to be Solved by the Invention] In view of the above 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 600
After holding at ~900℃ for 30 minutes to 5 hours, from that temperature 10
Heat treatment is performed by rapidly cooling at a rate of ℃/min or higher, the resulting heat-treated product is poured into water to form a slurry, the slurry is treated with water and an acid aqueous solution, and then pulverized to an average particle size of 3 to 10 μm. Then, its composition is
Sm _1-x Pr _x Co _z (However, 0.05≦x≦0.4, 4.7≦x≦
It has been discovered that the above object can be achieved by obtaining magnetic powder represented by 5.3). [Function] 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 under an inert gas atmosphere such as argon at normal pressure.
Heat at 950-1200℃ for 30 minutes to 4 hours. By doing so, 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 heated to 600 to 900°C, maintained at that temperature for 30 minutes to 5 hours, and then subjected to heat treatment in which it is 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℃ and less than 30 minutes,
The effect of heat treatment, which was to turn the generated heterogeneous phase into a 1-5 single phase and remove thermal strain to obtain a stable coercive force, could not be obtained sufficiently.
If the time is exceeded, the composition of the obtained magnet powder will deviate from the limited range described below, and different phases other than the 1-5 system will be likely to be generated.
The duration ranged from minutes to 5 hours. Also, cooling after heating is 10
It is necessary to perform the cooling at a cooling rate of ℃/min or higher. 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 obtained powder is further ground to an average particle size of 3 to 10 μm. Average particle size is 3μ
If the average particle size is less than 3 m, the residual magnetic flux density will decrease, while if it exceeds 10 μm, the coercive force will decrease.
The thickness was set to 10 μm. The magnet powder thus obtained has a composition of Sm _1-x Pr _x Co _z (0.05≦x≦0.4, 4.7≦x≦
5.3). x is 0.05
If x is less than 4.7, the residual magnetic flux density will not be improved sufficiently by the addition of praseodymium, while if x exceeds 0.4, the coercive force will decrease rapidly. This is because a 2-7 type different phase is likely to be generated and the residual magnetic flux density is likely to decrease, while if z exceeds 5.3, a 2-17 type different phase is likely to be generated and the coercive force is likely to be lowered. [Examples] The present invention will be described below with reference to Examples. Example 1 Sm ₂ O ₃ powder, Pr ₆ O ₁₁ powder, Co powder and Ca grains were blended to a predetermined composition (total amount 120 to 130 g).
The mixture was mixed and kept in an electric furnace kept at 1100°C under an Ar atmosphere for 3 hours, then allowed to cool, and then water-cooled from 900°C. The resulting reaction composition is mixed with water and has a pH of approximately 2.5.
of dilute acetic acid to separate and remove CaO and unreacted Ca in the reaction product. The obtained powder was dried after replacing the adhering moisture 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】

[Table] Also, after heating at 1100℃ for 3 hours in the above operation,
The reaction product was left as it was, and the temperature in the electric furnace was lowered to 800℃ over 1 hour, maintained at that temperature for 2 hours, and then rapidly cooled by blowing Ar gas. A fine powder sample was prepared in the same manner as described above, except that it was subjected to treatment with an acid aqueous solution. The composition and average particle size of these powders are shown in Table 2.

[Table] For the magnetic powder prepared as above,
As a resin, 5.0% by weight of epoxy resin was added and mixed, compression molded at a pressure of 4 ton/cm ² in a magnetic field of 13 KOe, and the molded product was kept 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] Example 2 The formulations of Test Nos. 1 and 2 of Example 1 were mixed (however, the total amount was 120 to 260 g), and after being held in an electric furnace maintained at 1100°C for 2 hours under an Ar atmosphere, test
For No. 1, the process was carried out until fine pulverization was performed in the same way as in Example 1 without heat treatment (Test No. 17), and for Test No. 2, after heating in the prescribed Ar, quenching was performed by blowing Ar gas. The heat treatment was performed as described above, and further pulverization was performed in the same manner as in the heat treatment in Example 1 (Test No.
18-27). For the magnetic powder prepared as above,
After adding and kneading 9.0% by weight of polyamide resin (nylon 6) as a resin and pelletizing,
Injection molding was carried out in a magnetic field of 10KOe. Table 4 shows the results of measuring the electrical characteristics of the obtained resin magnet.

〔Effect of the invention〕

As is clear from the above, the present invention heat-treats 1-5 series rare earth element-cobalt magnet powder, which is suitable for resin magnets and has a maximum energy product with improved residual magnetic flux density, by a reduction diffusion method. It can be manufactured by In addition, praseodymium, which partially replaces samarium, is more abundant and cheaper than samarium, and therefore, the present invention provides an industrial advantage for producing 1-5 series rare earth element-cobalt magnet powder suitable for resin magnets at low cost. The significance is very great.

Claims (1)

[Claims] 1. A mixture of samarium oxide, praseodymium oxide and cobalt powder is heated and reduced, and the produced samarium and praseodymium are diffused into the cobalt powder, and the reaction product is heated at 600 to 900°C.
After holding for 30 minutes to 5 hours, heat treatment is performed to rapidly cool the temperature at 10°C/min or more, and the resulting heat-treated product is poured into water to form a slurry. After the slurry is treated with water and an acid aqueous solution, the average Particle size is 3-10μm
The composition is Sm _1-x Pr _x Co _z
(However, 0.05≦x≦0.4, 4.7≦z≦5.3.