JPH0231483B2 - - Google Patents

Description

[Detailed Description of the Invention] Background Technical Field of the Invention The present invention is directed to the R ₂ Co 17 system Cu substitution precipitation effect, which is mainly composed of an intermetallic compound of Co and a rare earth element R consisting of one or more of the cerium group and the _yttrium group. The present invention relates to a method of manufacturing a powder-molded magnet using a powder formed by heat-treating a permanent magnet material of a mold and using the powder. Prior art and its problems By weight percentage, 22 to 28% of R (R is one or more rare earth elements), Co, Cu, one or more of Fe, Ni, Mn and Cr, Zr, Ti, Hf, Nb,
A rare earth cobalt based R ₂ Co ₁₇ based Cu substitution precipitation hardening permanent magnet having a composition consisting of at least one of V and Ta is known. This magnet has large residual magnetic flux density (Br), coercive force (bHc, iHc), and energy product (BH)
It is a permanent magnet with a large max, a high Kyrie temperature, and excellent temperature characteristics. In order to manufacture such permanent magnets, a compound is prepared by a known reduction-diffusion method or dissolution method, and then subjected to solution treatment, aging treatment, pulverization, and magnetic field orientation to form a rubber compound. or plastic resin as a binder to make powder molded magnets, or after crushing the compound and molding it in a magnetic field,
After that, sintering and solution treatment are performed, followed by aging treatment to form a sintered magnet. Among these, powder molded magnets in particular are expected to have high magnetic properties not found in conventional powder molded magnets.In addition, compared to conventional sintered ferrite, they can be made smaller, require no post-processing after molding, and have complex shapes. It has excellent advantages such as being able to obtain high quality products. In such cases, the aging treatment of _{R2Co17 -} based Cu-substituted magnets uses spinodal decomposition to disperse and precipitate fine precipitates in the matrix, and controls this phase separation to increase the coercive force. This is a heat treatment for Since the state of this precipitation and phase separation greatly influences the performance of the magnet, performing this aging treatment under optimal conditions is an extremely important point in manufacturing. Conventionally, aging treatments for R ₂ Co ₁₇ -based Cu substitution precipitation hardening magnets include multi-stage aging from 700 to 900°C to around 400°C (Japanese Patent Application Laid-open No. 133106/1983); A method of slowly cooling from a temperature of 10°C to around 400°C is known (Japanese Patent Application Laid-open No. 106624/1983). However, with these conventional aging treatments, it is difficult to obtain sufficiently satisfactory magnetic properties in terms of coercive force, residual magnetic flux density, energy product, hysteresis curve squaring, magnetization properties, etc. In particular, it is desirable to improve magnetic properties in low-cost practical magnet material compositions with low Cu contents of 10 wt% or less, especially 8 wt% or less, and high Fe contents of 6 wt% or more, especially 10 wt% or more. It is rare. In other words, to explain more specifically, these low Cu
In a practical magnet material composition with a high Fe content, approximately 12 KG of Br can be obtained by conventionally known aging treatment, and although a (B・H) max value of 30 MGOe or more is expected, the square shape The performance is poor and the expected (B・H) max value cannot be obtained. In this case, 10wt
%, a (B・H) max value that is only about 1 to 2 MGOe smaller than the expected (B・H) max can be obtained, but in conventional aging treatment, this 1 to 2 MGOe It is not possible to realize an increase in the energy product of , resulting in a major practical disadvantage. In addition, when the amount of Cu is reduced to about 2 to 3 wt%, Br is also extremely reduced by the conventional aging treatment method, and a magnet that can withstand practical use cannot be realized. Furthermore, the conventional aging treatment of rare earth cobalt-based materials requires a long holding time at the aging start temperature and end temperature, and has the disadvantage that the aging time is long. In addition, in the conventional aging treatment of rare earth cobalt-based materials, attention is focused only on the method of controlling cooling, and there is no example of repeated heating and cooling multiple times. Furthermore, JP-A-57-161044 discloses that primary sintering and secondary sintering are performed, and after isothermal treatment, cooling is performed from a higher temperature. However, this method is extremely complicated in that sintering must be performed twice, leading to increased manufacturing costs. Also, the demagnetization curve is not sufficiently squared. Furthermore, the aging treatment method is also different from the aging treatment method of the present invention in that after isothermal treatment at a low temperature, the next aging treatment is performed at a raised temperature. Further, the powder molded magnet in the present invention is not disclosed. Purpose of the Invention The present invention has been made in view of the above circumstances, and its main purpose is to improve magnetic properties such as coercive force, residual magnetic flux density, energy product, squareness ratio, and magnetization characteristics with high Fe. Using a heat treatment method that can reduce the aging treatment time, we have realized a practical magnet that has significantly improved Cu content and low Cu content compared to conventional aging treatment, and has magnetic properties that are sufficiently satisfactory for practical use _. An object of the present invention is to provide a method for manufacturing a _Co17 -based Cu-substituted powder molded magnet. These objects are achieved by the invention described below. That is, the present invention has a weight percentage of 22 to 28%.
R (R is one or more rare earth elements), 2-10% Cu, 6-35% T (T is one or more of Fe, Ni, Mn and Cr), 0.5-6% M (M is Zr, Ti,
one or more of Hf, Nb, V and Ta), remainder
A rare earth cobalt-based intermetallic compound having a composition mainly composed of Co is solution-treated and rapidly cooled, and then
A method for producing a powder molded magnet, which comprises repeating heat treatment twice or more to cool from a temperature of 750 to 950°C to a temperature of 700°C or less, followed by pulverization, mixing with a binder, magnetic field orientation, and molding. It is. The permanent magnet manufacturing method described in Japanese Patent Application Laid-Open No. 58-219704, which is an earlier application of the present application, involves multi-stage aging of the same type as the present invention, but the method disclosed is for sintered magnets. However, the powder molded magnet is not disclosed, and is different from the present invention. Specific Configuration of the Invention The specific configuration of the present invention will be described in detail below. The powder-molded magnet of the present invention is obtained by obtaining a rare earth cobalt-based intermetallic compound having a composition described in detail later, and then solution-treating and quenching it, then subjecting it to the heat treatment shown below, and then pulverizing it to align it in a magnetic field. It is manufactured by molding and dispersing it in a binder. In the heat treatment method used to manufacture the powder molded magnet of the present invention, solution treatment is performed as described above prior to multiple heat treatments for aging. The solution treatment is preferably performed at 1000°C or higher. This is because the squareness of the hysteresis curve and the coercive force decrease below 1000°C. In such cases, solution treatment is typically carried out at 1000°C.
It is applied at ~1200℃ for about 0.5 to 10 hours. After solution treatment, the material is rapidly cooled. This rapid cooling is generally performed at a cooling rate of about 1 to 300°C/min. Then, the first rapid cooling
The cooling may be carried out to any temperature below the cooling start temperature of 750 to 950°C. Thereafter, heating is performed to a cooling start temperature for a predetermined heat treatment, if necessary, and then heat treatment is performed a plurality of times. In other words, each heat treatment performed multiple times is
It consists of a cooling process from a cooling start temperature of 750 to 950°C to a cooling end temperature of 700°C or less. By repeating such heat treatment two or more times, the desired effects of the present invention can be achieved. In this case, the number of repetitions may be any number of times as long as it is two or more times, but from the viewpoint of shortening the aging treatment time, it is preferably 2 to 4 times. The cooling start temperature each time may be different from each other, but is preferably 750 to 950°C, preferably 780 to 950°C.
It is 920℃. If the cooling start temperature is less than 75°C, precipitation hardening will be insufficient, and if it exceeds 950°C, the precipitated particles will become coarse and the coercive force will decrease, which is unsuitable. The cooling end temperature for each round may be different, but is 700°C or less. If the cooling end temperature exceeds 700°C, the precipitated particles may become coarse or precipitation hardening may become insufficient, resulting in a decrease in coercive force, which is not preferable. In this case, when the cooling end temperature is set in the range from 600° C. to room temperature, particularly in the range from 500° C. to room temperature, more favorable results can be obtained in terms of improved magnetic properties. Note that such improvement in characteristics becomes greater as the cooling end temperature is lowered, but the effect remains almost unchanged below 400°C. There is no particular limit to the cooling rate each time, but
Usually 0.05-15℃/min, more preferably 2-15℃/min
The temperature should be approximately 10℃/min. In this case, the cooling profile may be multistage cooling in which the temperature is temporarily maintained, or continuous cooling in which the cooling rate is changed midway as necessary. However, in order to shorten the aging treatment time, continuous cooling is preferable, and it is particularly preferable to reduce the cooling rate in the final stage compared to the initial stage. Note that the optimum conditions for the cooling profile can be easily determined through experiments depending on the difference in composition and the like. Furthermore, although the heating profile for each heat treatment time is arbitrary, it is usually about 2 to 10°C/min. Note that it is preferable to provide a holding time at the cooling start temperature. Holding time is usually 5 minutes ~
The time is about 20 hours, but preferably 10 minutes to 6 hours. This holding time is determined empirically based on a combination of the number of repetitions, cooling rate, etc. On the other hand, at the cooling end temperature, it is not necessarily necessary to provide a holding time. The composition of the rare earth cobalt-based intermetallic compound to be subjected to the heat treatment multiple times as described above in order to produce the powder-molded magnet of the present invention is as described above. In this case, the rare earth element R contained in the range of 22 to 28 wt% may be one or more of cerium and yttrium, but it is particularly preferable to include samarium or cerium. Moreover, the content of Cu is 2 to 10 wt%. Otherwise, the effectiveness of the present invention will be reduced. In this case, the Cu content is 2.5 to 8 wt%, especially 3
When it becomes ~7.5 wt%, the rate of increase in magnetic properties compared to conventional aging treatment becomes extremely large. As a result, a magnet with extremely good magnetic properties is realized. Furthermore, T of one or more of Fe, Ni, Mn, and Cr is contained in an amount of 6 to 35 wt%. If the T content is other than this, the effectiveness of the present invention will be reduced. In this case, T contains Fe as an essential element, and if necessary, contains one or more of Ni, Mn, and Cr to obtain more preferable results. When the Fe content is 10 to 25 wt%, particularly 14 to 25 wt%, the rate of increase in magnetic properties compared to conventional aging treatment becomes extremely large, and a magnet with extremely good magnetic properties is realized. In addition, the permanent magnet material in the present invention includes:
At least one type of M selected from Zr, Ti, Hf, Nb, V, and Ta is contained in an amount of 0.5 to 6 wt%. If the M content is outside this range, the magnetic properties will deteriorate. As the binder used to manufacture the powder molded magnet of the present invention, various known resins can be mentioned. Specifically, rubber elastomers, thermoplastic resins such as polypropylene (PP), polyethylene (PE), nylon-11, 12, 6 (PA), polybutylene terephthalate (PBT), polyphenylene sulfonate (PPS), unsaturated polyester,
It is a thermosetting resin such as epoxy. The mixing ratio of the pulverized rare earth cobalt-based intermetallic compound (hereinafter sometimes referred to as metal powder) and the binder for dispersing it is preferably such that the binder accounts for 2 to 50% by weight of the total. The molding method differs depending on the type of binder to be dispersed, and in the case of a thermoplastic resin, injection molding, extrusion molding, rolling molding, etc. are used, and in the case of a thermosetting resin, compression molding, etc. are used. Injection molding is commonly used, and a magnetic field is usually applied during injection. When manufacturing the powder molded magnet of the present invention, a coupling agent, a lubricant, an antioxidant, etc. may be further added. Further, the metal powder and magnet used may be surface coated. Specific Effects of the Invention According to the present invention, magnetic properties such as coercive force, residual magnetic flux density, energy product, squareness ratio, and magnetization properties are improved compared to when conventional aging treatment is performed. That is, in a practical magnet material composition with a low Cu content of 10 wt% or less and a high Fe content, magnetic properties that are sufficiently satisfactory for practical use can be obtained. In this case, in a Cu content range relatively close to 10 wt%, for example 4 to 10 wt%, especially 4 to 8 wt%, squareness can be improved while keeping Br at the same level or higher compared to conventional aging treatment. , the coercive force improves, so
The desired (B·H)max value was obtained, and the characteristics were sufficiently satisfactory for practical use. Therefore, it has excellent characteristics as a powder molded magnet. Furthermore, at lower Cu compositions, such as 2 to 4 wt%, especially 2.5 to 4 wt%, which could not withstand practical use with conventional aging treatment, both Bf and coercive force increase at an extremely high rate, which is still impractical for practical use. Shows sufficiently satisfactory characteristics. Furthermore, in each cooling process, the holding time at the cooling start and end temperatures can be made shorter than before, and the aging treatment time as a whole can be made shorter than before. Specific Experimental Examples and Examples of the Invention Hereinafter, the present invention will be explained in more detail with reference to Experimental Examples and Examples. Experimental example 1 Weight percentage: 24.5% Sm, 5% Cu, 15% Fe,
An alloy consisting of 2% Zr and the remainder Co was produced by high frequency induction melting. This was solution treated and cooled to room temperature. The heat treatment was repeated twice by changing T ₁ and t ₁ with a cooling start temperature T ₁ and a cooling end temperature t ₁ in a profile as shown in FIG. 1. Figure 3 shows the relationship between iHc and T ₁ , and Figure 4 shows the relationship between iHc and T 1.
The relationship with t ₁ is shown by a solid line. In addition, in FIGS. 3 and 4, in the profile of the conventional multi-stage aging treatment shown in FIG. 2, the holding time is a=2Hr, b=1Hr,
The result when =1Hr is shown by the broken line. From these results, it is clear that the present invention is effective in performing predetermined aging heat treatment two or more times. It can also be seen that T ₁ is preferably 750 to 950°C, and t ₁ is preferably 700°C or less. Furthermore, it can be seen that the total aging treatment time is also shortened. Example 1 After solution treatment in the same manner as in Experimental Example 1, the following heat treatments A, B, and C were performed to obtain alloys 1A to 10C as shown in Table 1. A: In the profile shown in Figure 1, T ₁ = 850
℃, t ₁ = 400℃. B: In the three profiles in Figure 5, T ₁
= 900℃, T ₂ = 850℃, T ₃ = 800℃, t ₁ = 500℃,
t ₂ = 450℃, t ₃ = 400℃. C: In the one-time profile shown in Figure 2,
T ₁ = 850℃, t ₁ = 400℃, a = 6Hr, b = 1Hr,
When c=4Hr. Such alloys 1A to 10C were crushed and mixed using nylon 12 as a binder to be dispersed at a sample:binder mixing ratio of 94:6, and a silane coupling agent was added to the mixture as described above. It was added in an amount of 0.1 wt% to the mixture, mixed, and then heated and kneaded at 270°C. It was then pelletized and injection molded in a magnetic field. In this case, the applied magnetic field during injection was 15 KOe.
The magnet thus molded was taken out and magnetized. Alloy 1A using magnets prepared as above
Samples 1A to 7C correspond to 10C. Magnetic properties of samples 1A to 7C, Br, iHc,
(B・H)max is shown in Table 2. Further, Table 2 shows the increase rate of each of these characteristics with respect to treatment C.

【table】

[Table] From the results in Table 2, the effects of the present invention are clear.

[Brief explanation of drawings]

FIG. 1 is a temperature-time profile graph showing one example of the heat treatment method according to the present invention. FIG. 2 is a temperature-time profile graph showing an example of a conventional heat treatment method. Figures 3 and 4 show the coercive force - when T ₁ and t ₁ of the profiles in Figures 1 and 2 are changed, respectively.
It is a graph of T ₁ and coercive force −t ₁ . in this case,
In FIGS. 3 and 4, the solid line represents the profile shown in FIG. 1, and the broken line represents the profile shown in FIG. 2. FIG. 5 is a temperature-time profile graph showing another example of the heat treatment method according to the present invention.

Claims (1)

[Claims] 1 Weight percentage: 22-28% R (R is one or more rare earth elements), 2-10% Cu, 6-35% T
(T is one or more of Fe, Ni, Mn and Cr),
0.5-6% M (M is Zr, Ti, Hf, Nb, V and
A rare-earth cobalt-based intermetallic compound having a composition mainly consisting of one or more of Ta) and the remainder Co is solution-treated and rapidly cooled, and then cooled from a temperature of 750 to 950°C to a temperature of 700°C or less. A method for producing a powder molded magnet, which comprises repeating heat treatment two or more times, then pulverizing it, mixing it with a binder, and performing magnetic field orientation and molding. 2. The method for producing a powder molded magnet according to claim 1, wherein the rare earth cobalt-based intermetallic compound has a Cu content of 2.5 to 8%. 3 T of the rare earth cobalt-based intermetallic compound is Fe,
or manufacturing a powder-molded magnet according to claim 1 or 2, which is made of a combination of Fe and one or more of Ni, Mn, and Cr, and has an Fe content of 10 to 25%. Method. 4. The method for manufacturing a powder molded magnet according to any one of claims 1 to 3, wherein the solution treatment temperature is 1000°C or higher. 5 The end temperature of quenching after solution treatment is the same as that of the first
The method for manufacturing a powder molded magnet according to any one of claims 1 to 4, wherein the temperature range is from a cooling start temperature of 750 to 950°C to room temperature. 6. Claim 1 in which the cooling end temperature of each heat treatment is within the temperature range from 650°C to room temperature.
5. A method for producing a powder molded magnet according to any one of items 5 to 5. 7. The method for producing a powder molded magnet according to any one of claims 1 to 6, wherein the heat treatment is repeated 2 to 4 times. 8 At the cooling start temperature of each heat treatment, for 5 minutes or more
A method for manufacturing a powder-molded magnet according to any one of claims 1 to 7, in which a holding time of 20 hours is provided. 9 Cooling rate for each heat treatment is 0.05 to 15℃/min
A method for manufacturing a powder molded magnet according to any one of claims 1 to 8.