EP0654801A2 - Poudre magnétique, aimant permanent et procédé de fabrication - Google Patents

Poudre magnétique, aimant permanent et procédé de fabrication Download PDF

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EP0654801A2
EP0654801A2 EP94114972A EP94114972A EP0654801A2 EP 0654801 A2 EP0654801 A2 EP 0654801A2 EP 94114972 A EP94114972 A EP 94114972A EP 94114972 A EP94114972 A EP 94114972A EP 0654801 A2 EP0654801 A2 EP 0654801A2
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magnetic powder
powder
magnetic
mixed
bonded magnet
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EP0654801B1 (fr
EP0654801A3 (fr
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Atsunori C/O Seiko Epson Corp. Kitazawa
Toshiyuki C/O Seiko Epson Corp. Ishibashi
Koji C/O Seiko Epson Corp. Akioka
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Seiko Epson Corp
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Definitions

  • This invention relates to a magnetic powder and a permanent magnet having magnetic properties enhanced by taking advantage of a magnetic interaction and a process for producing them.
  • permanent magnetic materials have a tendency that an enhancement in saturation magnetization (or residual magnetic flux density) is not compatible with a high coercive force. More specifically, the following tendency is observed.
  • Soft magnetic materials are those materials which have a high saturation magnetization.
  • permendur has such a high saturation magnetization of 24 kG. It, however, has little or no coercive force.
  • hard magnetic materials with a high coercive force have much lower saturation magnetization than that of the soft magnetic materials.
  • R2Fe14B-based, R2Fe17N x -based and R2TM17-based materials have a relatively high saturation magnetization.
  • the powder particle diameter must be pulverized to several ⁇ m, so that the coercive force obtained is substantially small for practical use.
  • the material since the material has to be a finely milled, when it is compacted into a bonded magnet or the like, the packing density of magnetic powder can't be raised.
  • the addition of V, Mn or the like makes it possible to obtain a high coercive force in a relatively large powder particle diameter. It, however, results in a lowered saturation magnetization.
  • Bonded magnets produced by mixing two rare earth magnetic powders together are disclosed in Japanese Patent Laid-Open Nos. 144621/1993 and 152116/1993 and the like.
  • the bonded magnet disclosed in Japanese Patent Laid-Open No. 144621/1993 (Applicant: Tokin Corp.) comprises a mixture of an R2Fe17N-based powder with an R2Co17-based powder
  • the bonded magnet disclosed in Japanese Patent Laid-Open No. 152116/1993 comprises a mixture of an R2Fe17N-based powder with an R2Fe14B-based powder.
  • the magnetic materials called an "exchange spring magnets" have been reported in the art. These magnets comprise a soft magnetic phase and a hard magnetic phase. The thickness of the soft magnetic phase is made smaller than the domain wall width of the soft magnetic phase to inhibit the magnetization reversal of the soft magnetic phase, thereby enabling coercive force to be increased. More specifically, ⁇ Fe-Nd2Fe14B, Fe3B-Nd2Fe14B, ⁇ Fe-Sm2Fe17N x and other materials have been reported. In the above exchange spring magnets, the phases must be crystallographically coherent. Among processes for producing the above materials include rapid quenching and mechanical alloying.
  • the conventional permanent magnets had the following problems.
  • the present invention provides a magnetic powder comprising a mixture of two or more powders including a magnetic powder A (residual magnetic flux density: BrA, coercive force: HcA) and a magnetic powder B (residual magnetic flux density: BrB, coercive force: HcB), said residual magnetic flux densities and said coercive forces having the following relationships: BrA>BrB and HcA ⁇ HcB.
  • the present invention provides a process for producing a mixed powder comprising the above magnetic powders and a process for producing a bonded magnet or a sintered magnet produced from the mixed powder.
  • the magnetic interaction among different magnetic particles is such that the magnetization reversal of particles having a low coercive force is suppressed by a magnetic field like a kind of mean field formed among particles having a high coercive force.
  • y is less than 0.1, the suppression of magnetization reversal by the magnetic powder having a high coercive force becomes so weakened that a dent occurs in a demagnetization curve resulting in a lowered squareness.
  • the term "dent" used herein is intended to mean that an inflection point is present in a magnetization curve of the second quadrant (the fourth quadrant). More specifically, a demagnetization curve having a dent is, for example, that for Comparative Example 1-1 shown in Fig. 2.
  • x is 1 or less, although the squareness in the mixture of two powders is good, total Br of the two powders is decreased, which eventually results in a decrease in magnetic properties.
  • x exceeds 2, a large dent occurs and, also in this case, the properties are deteriorated.
  • the magnetic interaction working between different magnetic powders is most important, and this interaction works most when both the magnetic powders are in contact with each other as closely as possible and homogeneously dispersed in the whole material.
  • it is preferred to meet the relationship i/j a(i'/j')(0.5 ⁇ a ⁇ 1.5) .
  • a is below 0.5 or exceeds 1.5, one of the magnetic powders is present as cluster and is difficult to be homogeneously dispersed, so that no satisfactory magnetic interaction occurs.
  • the value should be 0.9 ⁇ a ⁇ 1.1 because the different magnetic powders can be homogeneously dispersed in each other.
  • the number n contacting point of both powders is preferably 2(rA+rB)2/rA2 ⁇ n wherein rA ⁇ rB, and is preferably 2(rA+rB)2/rB2 ⁇ n wherein rA>rB.
  • the n value is equal to 2(rA+rB)2/rA2 , the about half of the surface of the powder having a larger particle radius occupied with about half of the different powder.
  • the n value is less than 2(rA+rB)2/rA2 , the powder of the same kind are unfavorably clustered.
  • the magnetic interaction is like the mean field, there is a limitation on the distance to which the interaction can reach. Therefore, the shorter the distance between the two powders is, the bigger the magnitude of the interaction.
  • the interaction is enhanced with increasing the packing density of magnetic powder. This interaction is particularly enhanced when the packing density of magnetic powder is 50% or more in bonded magnets and 95% or more in sintered magnets.
  • the R-TM-N(C,H)-based fine powder is aligned on the surface of the powder particles having a higher coercive force, so that the alignment effect can be added to the interaction.
  • an enhancement in packing density of magnetic powder among powder enhances the magnetic interaction. In order to obtain this effect, it is preferred to meet the relationship 0.1 ⁇ m ⁇ rA ⁇ 10 ⁇ m and 10 ⁇ m ⁇ rB ⁇ 100 ⁇ m.
  • rA is less than 0.1 ⁇ m, no rotation torque is obtained and, further, the packing density of magnetic powder is also decreased.
  • rA is larger than 10 ⁇ m, no enough coercive force can be obtained and the magnetic interaction does not work.
  • rB When rB is less than 10 ⁇ m, the magnetic field formed by the magnetic powder having a higher coercive force is weakened. On the other hand, when rB is larger than 100 ⁇ m, the packing density of magnetic powder becomes so low that the interaction is weakened. In order to further enhance the interaction, it is preferred to meet the relationship 1 ⁇ m ⁇ rA ⁇ 5 ⁇ m and 20 ⁇ m ⁇ rB ⁇ 30 ⁇ m. In these ranges, the magnetic interaction becomes so strong that high magnetic properties are obtained.
  • the magnetic interaction is enhanced when there is a difference between powder content values at which the maximum value (peak) of the packing density of magnetic powder and the maximum value (peak) of the maximum energy product (BH) max are obtained respectively.
  • the difference between the weight percentage value of any one powder constituting a mixed powder at which the maximum value of the packing density of magnetic powder is obtained and that of said one powder constituting a mixed powder at which the maximum value of the maximum energy product (BH) max is obtained is preferably not less than 5 wt%.
  • certain magnetic interaction works between the powders mixed, so that there is no possibility that the squareness deterioration due to a dent in a demagnetization curve.
  • two or more powders should be first mixed together to improve the dispersibility (degree of mixing) of different powders, so that more effective magnetic interaction is attained.
  • magnetization of the mixed powder followed by molding contributes to an improvement in magnetic interaction among particles, which enables the squareness and the orientation to be improved.
  • plasma sintering can minimize the deterioration of the powders and enhance the magnetic interaction.
  • An ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere in order to be the composition comprising 24.5 wt% Sm and 75.5 wt% Fe.
  • the ingot was subjected to a homogenization treatment at 1100°C for 24 hrs and coarsely crushed to an average particle diameter of 100 ⁇ m by means of stamp mill.
  • the powder was nitrided at 450°C for one hr in a mixed gas of hydrogen and ammonia. It was then pulverized by means of jet mill to obtain a finely divided powder having an average particle diameter of 2.0 ⁇ m.
  • the fine powder was designated as "A1.”
  • the coercive force of the fine powder was measured to be 7.9 kOe.
  • an ingot was prepared by melting and casting using a high frequency melting furnace in an argon gas atmosphere, resulting in the ingot's composition comprised 24.2 wt% Sm, 45.7 wt% Co, 22.9 wt% Fe, 5.3 wt% Cu and 1.9 wt% Zr.
  • This ingot was subjected to a solution heat treatment in an argon atmosphere at 1150°C for 24 hrs. Thereafter, the treated ingot was aged in at 800°C for 12 hrs and then continuously cooled to 400°C at a rate of 0.5°C/min. Thereafter, the aged ingot was pulverized by means of a stamp mill and an attritor to prepare a powder having an average particle diameter of 21 ⁇ m. This powder was designated as "B1.” The powder had a coercive force of 12.8 kOe.
  • the above two powders were mixed together so as to meet the relationship represented by the formula (a)A1+(100-a)B1 wherein a is, in wt%, 0, 5, 10, 15, 20, 25, 30, 35 and 40.
  • the mixed powder was mixed and milled together with 1.6 wt% an epoxy resin, subjected to compression molding in a magnetic field of 15 kOe at a molding pressure of 7 ton/cm2 and then cured in a nitrogen gas atmosphere at 150°C for one hr to prepare a bonded magnet.
  • Fig. 1 The magnetic properties of a bonded magnets prepared in this example are shown in Fig. 1.
  • bonded magnets (resin content: 1.6 wt%) were prepared respectively from powder A1 alone and powder B1 alone. The bonded magnets thus molded were adhered to each other so that the amount of powder A1 was 25 wt% of total body.
  • This composite bonded magnet will be hereinafter referred to as "Comparative Example 1-1.”
  • Magnetization curves (demagnetization curves) for Example A and Comparative Example 1-1 are shown in Fig. 2. If an enhancement in magnetic properties is attributable only to an increase in packing density of magnetic powder alone, both the magnetization curves should be in agreement with each other. However, the magnetization of Example A shows higher value than that of Example B at any magnetic field. This demonstrates that Example A has an improved alignment over the magnet molded by employing a single powder. Further, the magnetization curve for Comparative Example 1-1 has a dent in a region of from 8 to 11 kOe of magnetic field, whereas no dent is observed in the magnetization curve for Example A. This is because in Example A, the magnetic interaction occurred among different particles.
  • the aged ingot was pulverized by means of a stamp mill and an attritor to prepare a powder having an average particle diameter of 21 ⁇ m.
  • This powder had a coercive force of 7.9 kOe.
  • This powder was mixed with 25 wt% powder A1, and the mixture was further mixed and milled together with 1.6 wt% an epoxy resin.
  • the resultant mixture was subjected to compression molding at a pressure of 7 ton/cm2 in a magnetic field of 15 kOe.
  • the molded body was cured in a nitrogen gas atmosphere at 150°C for one hr to prepare a bonded magnet.
  • This bonded magnet will be hereinafter referred to as "Comparative Example 1-2.”
  • bonded magnets were prepared from the respective two powders used in Comparative Example 1-2 and adhered to each other.
  • This composite magnet will be hereinafter referred to as "Comparative Example 1-3.” Magnetization curves for both magnets are shown in Fig. 3. As can be seen from Fig. 3, the magnetization curve for Comparative Example 1-2 is substantially in agreement with that for Comparative Example 1-3. From the above results, it can be understood that a high magnetic property by virtue of magnetic interaction cannot be obtained without mixing two magnetic powders different from each other in coercive force.
  • Example B Powder A1 and powder B1 used in Example 1 were mixed together in a weight ratio of 1 : 3 using a twin-cylinder mixer. The mixture was further mixed and kneaded together with 1.6 wt% of an epoxy resin. The resultant compound was subjected to compression molding at a molding pressure of 7 ton/cm2 in a magnetic field of 15 kOe. The molded body was cured in a nitrogen atmosphere at 150°C for one hr to prepare a bonded magnet. This bonded magnet will be hereinafter referred to as "Example B.”
  • Example B The magnetic properties of Example B and Comparative Example 2 are tabulated below.
  • Example B had high magnetic property, whereas the properties of Comparative Example 2 were low due to a deterioration in squareness. Therefore, it can be understood that sufficient mixing of powders followed by molding of a bonded magnet enables strong magnetic interaction to work among different particles, so that a high-performance bonded magnet can be obtained.
  • Cylindrical bonded magnets having a diameter of 10 mm and a height of 7 mm were prepared from Example B, Comparative Example 1-2 and a bonded magnet (Comparative Example 3) comprising powder A1 and, 4 wt% of an epoxy resin. They were subjected to an exposing test at 150°C for 1000 hrs. The magnetization loss of the cylindrical bonded magnets are tabulated below.
  • Ex. B Comp.Ex. 1-2
  • Comp.Ex. 2 Comp.Ex. 3
  • Demagnetization (%) 4.8 10.2 7.3 46.3
  • Example B is superior in temperature characteristics to the other bonded magnets.
  • An ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere, resulting in the ingot's composition comprised 24.2 wt% of Sm, 45.7 wt% of Co, 22.9 wt% of Fe, 5.3 wt% of Cu and 1.9 wt% of Zr.
  • This ingot was subjected to a solution heat treatment in an argon atmosphere at 1150°C for 24 hrs. Thereafter, the treated ingot was then aged at 800°C for 12 hrs and continuously cooled to 400°C at a rate of 0.5°C/min. Thereafter, the aged ingot was coarsely crushed by means of a stamp mill to an average particle diameter of 200 ⁇ m. This powder was designated as "B2.”
  • Fig. 4(A) Demagnetization curves for Example C and Example A are shown in Fig. 4(A). Both the demagnetization curves are substantially in agreement with each other. However, when the magnetization difference between both samples curves are strictly observed, Fig. 4(B) is provided, suggesting that an improvement in squareness can be obtained by simultaneous pulverization and mixing. From the above results, it can be understood that simultaneous pulverization and mixing contribute to an improvement in magnetic interaction among particles because fresh surfaces come into contact with one another, so that high magnetic properties can be obtained.
  • Example C and Example A were kept in air at 150°C for 100 hrs. Demagnetization curves for Example C and Example A after the above treatment are shown in Fig. 4(C). From Fig. 4(C), it can be clearly understood that Example C is superior to Example A in temperature characteristics.
  • An ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere, resulting in the ingot's composition comprised 24.5 wt% of Sm and 75.5 wt% of Fe.
  • the ingot was subjected to a homogenization heat treatment at 1100°C for 24 hrs and coarsely crushed to an average particle diameter of 100 ⁇ m by means of a stamp mill.
  • the powder was nitrided at 450°C for one hr in a mixed gas of hydrogen and ammonia. It was then pulverized by means of a jet mill. At that time, the coercive force was varied by varying the pulverization time.
  • the resultant powders are collectively referred to as "X.”
  • an ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere resulting in the composition comprised 24.2 wt% of Sm, 45.7 wt% of Co, 22.9 wt% of Fe, 5.3 wt% Cu and 1.9 wt% of Zr.
  • This ingot was subjected to a solution heat treatment in an argon atmosphere at 1150°C for 24 hrs. Thereafter, the treated ingot was aged at 800°C for 1 to 24 hrs and continuously cooled to 400°C at a rate of 0.5°C/min. In this case, the coercive force was varied by varying the aging treatment time. Thereafter, pulverization was carried out by means of stamp mill and attritor.
  • the resultant powders are collectively referred to as "Y.”
  • Powder X and powder Y were mixed together so that the X content was 25 wt%.
  • the mixed powder was mixed and kneaded together with 1.6 wt% of an epoxy resin, and the resultant compound was subjected to compression molding in a magnetic field of 15 kOe at a molding pressure of 7 ton/cm2 and cured in a nitrogen atmosphere at 150°C for one hr to prepare bonded magnets.
  • the magnetic properties of the bonded magnets were measured, and the results are shown in Fig. 5.
  • An ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere, resulting in the composition comprised 24.5 wt% of Sm and 75.5 wt% of Fe.
  • the ingot was subjected to a homogenization heat treatment at 1100°C for 24 hrs and coarsely crushed to an average particle diameter of 100 ⁇ m by means of a stamp mill.
  • the powder was nitrided at 450°C for one hr in a mixed gas of hydrogen and ammonia. It was then pulverized by means of jet mill. At that time, the average powder particle diameter was varied by varying the pulverization time.
  • the resultant powders are collectively referred to as "X2.”
  • the average particle diameters were shown in Table 1.
  • an ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere, resulting in the composition comprised 24.2 wt% of Sm, 45.7 wt% of Co, 22.9 wt% of Fe, 5.3 wt% of Cu and 1.9 wt% of Zr.
  • This ingot was subjected to a solution heat treatment in an argon atmosphere at 1150°C for 24 hrs. Thereafter, the treated ingot was then aged at 800°C for 12 hrs and continuously cooled to 400°C at a rate of 0.5°C/min. Thereafter, pulverization was carried out by means of stamp mill and attritor.
  • Powder X2 and powder Y2 were mixed together so that the X2 content was 25 wt%.
  • the mixed powder was mixed and kneaded together with 1.6 wt% of an epoxy resin, and the resultant compound was subjected to compression molding in a magnetic field of 15 kOe at a pressure of 7 ton/cm2 and cured in a nitrogen atmosphere at 150°C for one hr to prepare bonded magnets.
  • the magnetic properties of the bonded magnets were measured, and the results are shown in Table 1.
  • Magnetic powder A1 obtained and magnetic powder B1 were mixed so that powder A1 content was 25 wt%. At that time, the mixing time was varied to vary the degree of dispersion between different powders. The degree of dispersion was roughly estimated in terms of the value a defined in claim 4 of the present application. Since the total amount of the mixed powder was 100 g, 1 g of the mixed power was randomly sampled therefrom. The mixing ratio of A1 to B1 was measured from the 1g sample to determine the value a . The results are shown in Fig. 6.
  • the magnetic properties of Example D were as follows.
  • the properties of a bonded magnet as Comparative Example 4 prepared by using powder B3 alone are also given below.
  • Example D had very high magnetic properties by virtue of magnetic interaction.
  • An ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere, resulting in the composition comprised 6.7 wt% of Sm, 2.3 wt% of Ce, 6.8 wt% of Pr, 6.9 wt% of Nd, 51.2 wt% of Co, 15.39 wt% of Fe, 6.8 wt% of Cu and 3.4 wt% of Zr.
  • This ingot was subjected to a solution heat treatment in an argon atmosphere at 1145°C for 24 hrs. Thereafter, the treated ingot was then aged at 780°C for 12 hrs and continuously cooled to 400°C at a rate of 0.5°C/min.
  • the aged ingot was pulverized by means of stamp mill and attritor to prepare a powder having an average particle diameter of 20 ⁇ m.
  • This powder was designated as "B4.”
  • the powder had a coercive force of 10.5 kOe.
  • an ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere, resulting in the composition comprised 22.5 wt% of Sm, 2.3 wt% of Pr, 70.1 wt% of Fe and 5.1 wt% of Co.
  • the ingot was subjected to a homogenization heat treatment at 1100°C for 24 hrs and coarsely crushed to an average particle diameter of 100 ⁇ m by means of stamp mill.
  • the powder was nitrided at 450°C for 2 hrs in a mixed gas of hydrogen and ammonia. It was then pulverized by means of jet mill to prepare a fine powder having an average particle diameter of 2.2 ⁇ m.
  • the fine powder was designated as "A2.”
  • the coercive force of this powder was measured to be 6.5 kOe.
  • Example E Powder A2 and powder B4 were mixed and kneaded together in a weight ratio of A2 to B4 of 1 : 3. The resultant compound was subjected to compression molding in a magnetic field of 15 kOe at a pressure of 7 ton/cm2 and cured in a nitrogen atmosphere at 150°C for one hr to prepare a bonded magnet. This bonded magnet will be hereinafter referred to as "Example E.”
  • An alloy comprising, 10.5 wt% Sm and 89.5 wt% Fe, which had been prepared by using Sm having a purity of 99.9% and Fe having a purity of 99.9%, was prepared using an induction furnace in an Ar atmosphere.
  • the resultant ingot was then subjected to a homogenization heat treatment in an Ar atmosphere at 1100°C for 24 hrs. Thereafter, the ingot was coarsely crushed to a powder particle diameter of about 100 ⁇ m and then carbonized in an acetylene gas at 450°C for one hr.
  • the resultant powder was pulverized to an average particle diameter of 5 ⁇ m. This powder was designated as "A3.”
  • An ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere, resulting in the composition comprised 24.2 wt% of Sm, 45.7 wt% of Co, 22.9 wt% of Fe, 5.3 wt% of Cu and 1.9 wt% of Zr.
  • This ingot was subjected to a solution heat treatment in an argon atmosphere at 1150°C for 24 hrs. Thereafter, the treated ingot was then aged at 800°C for 12 hrs and continuously cooled to 400°C at a rate of 0.5°C/min. Thereafter, the aged ingot was pulverized by means of stamp mill and attritor to prepare a powder having an average particle diameter of 21 ⁇ m.
  • Powder A2 was mixed and milled together with 1.6 wt% of an epoxy resin, subjected to compression molding in a magnetic field of 15 kOe at a pressure of 7 ton/cm2 and cured at 150°C for one hr to prepare a bonded magnet.
  • This bonded magnet was designated as "Comparative Example 5.”
  • an ingot was prepared by melting and casting, resulting in the composition comprised 25.8 wt% of Sm, 44.9 wt% of Co, 24.8 wt% of Fe, 3.2 wt% of Cu and 1.3 wt% of Zr.
  • the ingot was then subjected to a solution heat treatment in an argon atmosphere at 1120°C for 48 hrs. Thereafter, the treated ingot was then aged at 800°C for 15 hrs and continuously cooled to 400°C at a rate of 0.5°C/min. Thereafter, the aged ingot was pulverized by means of stamp mill and attritor to prepare a powder having an average particle diameter of 23 ⁇ m.
  • Powder B4 was mixed and kneaded together with 1.6 wt% of an epoxy resin, subjected to compression molding in a magnetic field of 15 kOe at a pressure of 7 ton/cm2 and cured at 150°C for one hr to prepare a bonded magnet.
  • This bonded magnet was designated as "Comparative Example 6.”
  • the above two powders were mixed together so as to meet the relationship ⁇ (a)xA2 ⁇ + ⁇ (100-a)B4 ⁇ wherein a is, in wt%, 0 (Comparative Example 6), 20, 40, 60, 80 and 100 (Comparative Example 5).
  • the mixed powder was mixed and kneaded together with 1.6 wt% of an epoxy resin, subjected to compression molding in a magnetic field of 15 kOe at a pressure of 7 ton/cm2 and cured at 150°C for one hr to prepare a bonded magnet.
  • the magnetic properties of the bonded magnet are shown in Fig. 7. As is apparent from Fig. 7, the maximum energy product had a peak value when the value a was 40 wt%.
  • Example G This bonded magnet having a value a of 40% had a higher performance than a bonded magnet either comprising A1 alone or a bonded magnet comprising B1 alone.
  • the bonded magnet having a value a of 40 wt% will be hereinafter referred to as "Example G.”
  • the magnetic properties of Example G, Comparative Example 5 and Comparative Example 6 were as follows. Br (kG) iHc (kOe) (BH) max (MGOe) Ex. G 9.6 9.5 21.2 Comp.Ex. 5 9.2 12.5 18.5 Comp.Ex. 6 10.2 7.2 18.8
  • bonded magnets were prepared respectively from powder A2 alone and powder B4 alone. The two bonded magnets thus formed were adhered to each other so that the amount of powder A2 was 40 wt%.
  • This composite bonded magnet will be hereinafter referred to as "Comparative Example 7.”
  • Magnetization curves (demagnetization curves) for Example G and Comparative Example 7 are shown in Fig. 8.
  • the magnetization curve for Comparative Example 7 had a dent in a region of from 5 to 9 kOe, whereas no dent was observed in the magnetization curve for Example G. This is because, in Example G, magnetic interaction occurred among different particles.
  • the term "dent" used herein is intended to mean that an inflection point is present in a magnetization curve of the second quadrant (the fourth quadrant).
  • An ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere, resulting in the composition comprised 10.0 wt% of Sm, 14.0 wt% of Pr, 46.3 wt% of Co, 21.6 wt% of Fe, 6.2 wt% of Cu and 1.9 wt% of Zr.
  • This ingot was subjected to a solution heat treatment in an argon atmosphere at 1130°C for 48 hrs. Thereafter, the treated ingot was then aged at 800°C for 12 hrs and continuously cooled to 400°C at a rate of 0.5°C/min. Thereafter, the aged ingot was pulverized by means of stamp mill and attritor to prepare a powder having an average particle diameter of 20 ⁇ m.
  • Powder C1 was mixed and milled together with 1.6 wt% of an epoxy resin, subjected to compression molding in a magnetic field of 15 kOe at a pressure of 7 ton/cm2 and cured at 150°C for one hr to prepare a bonded magnet.
  • This bonded magnet was designated as "Comparative Example 7.”
  • Example H Powder C1 and Powder A2 were mixed together in a weight ratio of 13 : 7, and the mixed powder was further mixed and kneaded together with 1.6 wt% of an epoxy resin, subjected to compression molding in a magnetic field of 15 kOe at a pressure of 7 ton/cm2 and cured at 150°C for one hr to prepare a bonded magnet.
  • This bonded magnet will be hereinafter referred to as "Example H.”
  • the above procedure was repeated to prepare a bonded magnet, except that in the case of the magnets in which powder C1 alone was used.
  • This bonded magnet will be hereinafter referred to as "Comparative Example 8.”
  • the magnetic properties of Example H and Comparative Example 8 are tabulated below.
  • Br (kG) iHc (kOe) (BH) max (MGOe) Comp.Ex. 7 9.1 11.5 19.2 Ex. H 9.8 10.8 22.1 Comp.Ex. 8 10.5 7.1 17.8
  • Example H had high magnetic properties, whereas Comparative Example 8 had a deteriorated performance due to a low coercive force.
  • An ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere, resulting in the composition comprised 12.4 wt% of Sm, 11.9 wt% of Nd, 46.2 wt% of Co, 21.5 wt% of Fe, 6.1 wt% of Cu and 1.9 wt% of Zr.
  • This ingot was subjected to a solution heat treatment in an argon atmosphere at 1140°C for 48 hrs. Thereafter, the treated ingot was then aged at 800°C for 12 hrs and continuously cooled to 400°C at a rate of 0.5°C/min. Thereafter, the aged ingot was pulverized by means of stamp mill and attritor to prepare a powder having an average particle diameter of 22 ⁇ m.
  • Powder D1 was mixed and kneaded together with 1.6 wt% of an epoxy resin, subjected to compression molding in a magnetic field of 15 kOe at a pressure of 7 ton/cm2 and cured at 150°C for one hr to prepare a bonded magnet.
  • This bonded magnet was designated as "Comparative Example 9.”
  • Example I Powder D1 and powder A2 were mixed together in a weight ratio of 60 : 40, and the mixture was further mixed and kneaded together with 1.6 wt% of an epoxy resin, subjected to compression molding in a magnetic field of 15 kOe at a molding pressure of 7 ton/cm2 and cured at 150°C for one hr to prepare a bonded magnet.
  • This bonded magnet will be hereinafter referred to as "Example I.”
  • the above procedure was repeated to prepare a bonded magnet, except that powder C1 alone was used.
  • This bonded magnet will be hereinafter referred to as "Comparative Example 10.”
  • the magnetic properties of Example I and Comparative Example 10 are tabulated below.
  • Br (kG) iHc (kOe) (BH) max (MGOe) Comp.Ex. 9 9.3 10.6 19.6 Ex. I 10.1 9.8 21.1 Comp.Ex. 10 10.9 6.7 17.3
  • Example I had high magnetic properties, whereas Comparative Example 10 had no satisfactory performance due to a low coercive force.
  • An ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere in such a manner that the composition comprised 24.2 wt% of Sm, 44.9 wt% of Co, 26.5 wt% of Fe, 3.2 wt% of Cu and 1.2 wt% of Zr.
  • the ingot was subjected to a solution heat treatment in an argon atmosphere at 1120°C for 48 hrs. Thereafter, the treated ingot was then aged at 800°C for a given period of time and then continuously cooled to 400°C at a rate of 0.5°C/min.
  • the coercive force was varied by varying the aging time (1-24 hrs).
  • Powders X2 and powders Y2 were mixed together in a mixing ratio of 3 : 2.
  • 1.6 wt% of an epoxy resin was added to the mixed powders, and they were mixed and kneaded together.
  • the resultant compounds were subjected to compression molding in a magnetic field of 15 kOe at a pressure of 7 ton/cm2 and cured at 150°C for one hr to prepare bonded magnets.
  • the relationship between the coercive force and the obtained (BH) max is shown in Fig. 9.
  • Ingots used for the preparation of powders A2, B4, C1 and D1 were designated respectively as A3, B5, C2 and D2. These ingots were coarsely crushed to an average particle diameter of about 200 ⁇ m.
  • Examples J, K and L show higher magnetic properties than Examples G, H and I. This demonstrates that simultaneous pulverization and mixing of powders enhance magnetic interaction among particles (by virtue of contact of fresh surfaces) to provide high magnetic properties.
  • Example 16 The compounds prepared in Example 16 were magnetized in a magnetic field of 40 kOe, subjected to compression molding in a magnetic field of 15 kOe at a pressure of 7 ton/cm2 and cured at 150°C for one hr to prepare bonded magnets. These bonded magnets were designated as "Example M,” “Example N,” and “Example O.” The magnetic properties thereof are tabulated below. Br (kG) iHc (kOe) (BH) max (MGOe) Ex. M 10.6 10.2 23.4 Ex. N 11.2 11.5 24.1 Comp.Ex. 15 11.2 10.7 23.0
  • Powder A1 and powder B1 were mixed together and pulverized in a weight ratio of 1 : 3.
  • the mixed powder was mixed and kneaded together with 1.6 wt% of an epoxy resin.
  • the resultant compound was molded in a magnetic field of 15 kOe.
  • the density of magnetic powder was varied by varying the molding pressure.
  • the magnitude of the magnetic interaction was evaluated in terms of the magnitude of a peak value of a magnetization difference between a demagnetization curve measured in reality magnetization and a demagnetization curve determined by calculation without the interaction. That the calculated magnetization curve is well in agreement with the curve measured in reality demagnetization curve without magnetic interaction has already been illustrated in Example 1.
  • a typical variation in the differences between the measured values and the calculated values is shown in Fig. 10.
  • Fig. 11 The relationship between the packing density of magnetic powder and the peak value is shown in Fig. 11. As is apparent from the drawing, it can be understood that the peak value increases with increasing the packing density of magnetic powder, which contributes to an improvement in squareness. In particular, the peak value rapidly decreases when the packing density of magnetic powder is not more than 50%, suggesting that the packing density of magnetic powder is critical to effective magnetic interaction.
  • Powder A1 and powder B1 were mixed together and pulverized together in a weight ratio of 1 : 3 to prepare a mixed powder.
  • the mixed powder was pressed at a pressure of 5 ton/cm2, a pulse current of 2000 A was allowed to flow, and plasma sintering was carried out at a sintering temperature of 400°C for 5 min.
  • the resultant sintered magnet was designated as "Example P.”
  • powder A1 and powder B1 were subjected to plasma sintering in such a manner that two layers were formed in the same composition as in Example P (i.e., so as to prepare a kind of a gradient material).
  • the resultant magnet was designated as "Comparative Example 11.”
  • Comparative Example 11 exhibited lowered magnetic properties due to occurrence of a dent, whereas Example P showed a very good squareness, which contributed to an enhancement in magnetic properties.
  • An ingot was prepared by melting and casting using an induction furnace in an argon gas atmosphere, resulting in the composition comprised 24.2 wt% of Sm, 45.7 wt% of Co, 22.9 wt% of Fe, 5.3 wt% of Cu and 1.9 wt% of Zr. This ingot was subjected to a solution heat treatment in an argon atmosphere at 1150°C for 12 hrs. This treated ingot was designated as "K1.”
  • an ingot was prepared by melting and casting, resulting in the composition comprised 10.0 wt% of Sm, 14.0 wt% of Pr, 46.3 wt% of Co, 21.6 wt% of Fe, 6.2 wt% of Cu and 1.9 wt% of Zr.
  • This ingot was subjected to a solution heat treatment in an argon atmosphere at 1130°C for 24 hrs. This treated ingot was designated as "K2.”
  • Ingots K1 and K2 were milled together in a weight ratio of 13 : 7, by means of jet mill (so that pulverization and mixing were simultaneously carried out).
  • the mixed powder was molded in a magnetic field of 15 kOe, and the resultant molded body was sintered at 1200°C. Thereafter, the sinter body was subjected to a solution heat treatment at 1130°C for 24 hrs and aged at 800°C for 12 hrs and then continuously cooled to 400°C at a rate of 0.5°C/min.
  • the sintered magnet thus prepared had the following performance.
  • Example 20 The mixed powder prepared in Example 20 was molded in a magnetic field of 15 kOe at varied molding pressures. Sintered magnets were prepared from the molded body in the same manner as in Example 20. The packing density of magnetic powder was varied by varying the molding pressure as described above. The relationship between the packing density of magnetic powder and the peak value of the difference as an index of the magnetic interaction determined in Example 18 is shown in Fig. 12. As is apparent from the drawing, the peak value increased, that is, the squareness improved, with increasing the packing fraction. In particular, a rapid increase in the peak was observed when the packing density of magnetic powder was not less than 95%, illustrating that the packing fraction is critical to effective magnetic interaction.
  • Powder L1 and Powder B1 were mixed together in a ratio of 3 : 2, and the mixture was further mixed and milled together with 1.6 wt% of an epoxy resin and molded in a magnetic field of 15 kOe. Thereafter, the molded body was cured at 150°C for one hr to prepare a bonded magnet.
  • the composition was Fe65Co35.
  • the resultant ingot was pulverized.
  • This powder was designated as "M1.”
  • Powder M1 and powder K1 were mixed together in a weight ratio of 1 : 9.
  • the mixed powder was pulverized by means of a jet mill and molded in a magnetic field of 15 kOe.
  • the molding was sintered at 1200°C.
  • the sintered body was subjected to a solution heat treatment at 1130°C for 24 hrs and aged at 800°C for 12 hrs and continuously cooled to 400°C at a rate of 0.5°C/min.
  • the sintered magnet had the following magnetic properties.
  • Powder M1 and powder A1 were mixed together in the weight ratio of 2 : 8.
  • the mixed powder was pulverized by means of a jet mill, mixed and milled together with 1.6 wt% of an epoxy resin and molded in a magnetic field of 15 kOe. Thereafter, the molding was cured at 150°C for one hr to prepare a bonded magnet.
  • Atomized Fe powder (average particle diameter is 2 ⁇ m) P1 and powder L1 were mixed together in a ratio of 1 : 9, and the mixed powder was mixed and kneaded together with 1.6 wt% of an epoxy resin and molded in a magnetic field of 15 kOe. Thereafter, the molded body was cured at 150°C for one hr to prepare a bonded magnet.
  • An ⁇ -Fe2O3 powder and an SrCO3 powder were weighed so as to have a Fe2O3/SrO value of 5.9, mixed together by means of a ball mill, pre-sintered at 1250°C for 4 hrs and again pulverized by means of a ball mill.
  • the resultant powder was designated as "R1.”
  • Powder R1 and powder K1 were mixed together in a ratio of 2 : 8, and the mixed ingot was pulverized by means of jet mill.
  • the mixed powder was molded in a magnetic field of 15 kOe, and the molding was sintered at 1200°C.
  • the sintered body was heat-treated at 1130°C for 24 hrs and aged at 800°C for 12 hrs and then continuously cooled to 400°C at a rate of 0.5°C/min.
  • Powder R1 and powder A1 were mixed together in a weight ratio of 3 : 7, and the mixture was pulverized by means of a jet mill.
  • the mixed powder was mixed and kneaded together with 4 wt% of an epoxy resin and molded in a magnetic field of 15 kOe. Thereafter, the molded body was cured at 150°C for one hr to prepare a bonded magnet.
  • Powder R1 and powder L1 were mixed together in a ratio of 1 : 9, and the mixed powder was mixed and kneaded together with 1.6 wt% of an epoxy resin and molded in a magnetic field of 15 kOe. The molding was cured at 150°C for one hr to prepare a bonded magnet.
  • Powder R1 and powder M1 were mixed together in a weight ratio of 7 : 3.
  • the mixed powder was pulverized by means of a jet mill and molded in a magnetic field of 15 kOe.
  • the molded body was sintered at 1250°C and heat-treated at 850°C for 5 hrs.
  • Powder S1 and powder A1 were mixed together in a ratio of 2 : 8, and the mixed powder was mixed and kneaded together with 1.6 wt% of an epoxy resin and molded in a magnetic field of 15 kOe.
  • the molded body was cured at 150°C for one hr to prepare a bonded magnet.
  • the magnetic properties of the bonded magnet are shown below.
  • Powder S1 and powder L1 were mixed together in a weight ratio of 3 : 17, and the mixed powder was mixed and kneaded together with 1.6 wt% of an epoxy resin and molded in a magnetic field of 15 kOe.
  • the molding was cured at 150°C for one hr to prepare a bonded magnet.
  • the magnetic properties of the bonded magnet are shown below.
  • Powder S1 and powder Q1 were mixed together in a ratio of 3 : 7, and the mixed powder was mixed and kneaded together with 1.6 wt% of an epoxy resin and molded in a magnetic field of 15 kOe.
  • the molded body was cured at 150°C for one hr to prepare a bonded magnet.
  • Powder A1 and powder B1 were mixed together in a weight ratio of 1 : 3, 2.5 wt% of nylon 12 was added to the mixed powder, and they were kneaded together at 250°C.
  • the mixture was pelletized by means of a pulverizer and molded in a magnetic field of 10 kOe at 250°C to prepare a bonded magnet. In this case, the pressure was 1 ton/cm2.
  • the magnetic properties of the bonded magnet are shown below.
  • Powder A1 and powder B1 were mixed together in a ratio of 1 : 3, 10 wt% of nylon 12 was added to the mixed powder, and they were kneaded together at 280°C.
  • the compound was injection-molded at 280°C and an injection pressure of 1 ton/cm2 in a magnetic field of 15 kOe.
  • Powder A1 and powder B1 were mixed together in a weight ratio of 1 : 3.
  • the average particle diameters of powder A1 and powder B1 were respectively 2.0 ⁇ m (rA) and 21.0 ⁇ m (rB).
  • the mixing was carried out by means of a twin-cylinder mixer with varied mixing times.
  • the mixed powders were mixed and milled together with 1.6 wt% of an epoxy resin, and the resultant compound was molded in a magnetic filed of 15 kOe.
  • the moldings were cured at 150°C for one to prepare a bonded magnet.
  • the sections of the bonded magnets were observed under a scanning electron microscope (SEM) to measure the number of contacting points of A1 with B1 (average for 10 points).
  • SEM scanning electron microscope

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998008232A1 (fr) * 1996-08-20 1998-02-26 Rhodia Chimie Produit a proprietes magnetiques, son procede de preparation et aimant obtenu a partir de ce produit
EP1494251A1 (fr) * 2002-04-09 2005-01-05 Aichi Steel Corporation Aimant anisotrope lie composite de terres rares, compose pour aimant anisotrope lie composite de terres rares, et procede de production de l'aimant
EP1523017A3 (fr) * 2003-10-10 2007-07-11 Aichi Steel Corporation Aimant agglomeré anisotrope de terre rare composite, composition pour un aimant agglomeré anisotrope de terre rare composite, et procédés de production associés

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58108708A (ja) * 1981-12-23 1983-06-28 Tohoku Metal Ind Ltd 希土類永久磁石材料
JPS59106106A (ja) * 1982-12-10 1984-06-19 Toshiba Corp 永久磁石の製造方法
JPH01274401A (ja) * 1988-04-26 1989-11-02 Tdk Corp 永久磁石
GB2232165A (en) * 1989-03-22 1990-12-05 Cookson Group Plc Magnetic compositions
WO1992015995A1 (fr) * 1991-03-08 1992-09-17 Basf Aktiengesellschaft Categorie nouvelle de materiaux magnetiques, leur production et leur utilisation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58108708A (ja) * 1981-12-23 1983-06-28 Tohoku Metal Ind Ltd 希土類永久磁石材料
JPS59106106A (ja) * 1982-12-10 1984-06-19 Toshiba Corp 永久磁石の製造方法
JPH01274401A (ja) * 1988-04-26 1989-11-02 Tdk Corp 永久磁石
GB2232165A (en) * 1989-03-22 1990-12-05 Cookson Group Plc Magnetic compositions
WO1992015995A1 (fr) * 1991-03-08 1992-09-17 Basf Aktiengesellschaft Categorie nouvelle de materiaux magnetiques, leur production et leur utilisation

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 007 no. 214 (E-199) ,21 September 1983 & JP-A-58 108708 (TOUHOKU KINZOKU KOGYO KK) 28 June 1983, *
PATENT ABSTRACTS OF JAPAN vol. 008 no. 226 (E-272) ,17 October 1984 & JP-A-59 106106 (TOSHIBA KK) 19 June 1984, *
PATENT ABSTRACTS OF JAPAN vol. 014 no. 041 (E-0879) ,25 January 1990 & JP-A-01 274401 (TDK CORP) 2 November 1989, *
PHYSICAL REVIEW, B CONDENSED MATTER., vol. 48,no. 21, 1 December 1993 NEW YORK US, pages 15812-15816, R.SKOMSKI ET AL 'Giant energy product in nanostructured two-phase magnets' *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998008232A1 (fr) * 1996-08-20 1998-02-26 Rhodia Chimie Produit a proprietes magnetiques, son procede de preparation et aimant obtenu a partir de ce produit
FR2752641A1 (fr) * 1996-08-20 1998-02-27 Rhone Poulenc Chimie Produit a proprietes magnetiques, son procede de preparation et aimant obtenu a partir de ce produit
EP1494251A1 (fr) * 2002-04-09 2005-01-05 Aichi Steel Corporation Aimant anisotrope lie composite de terres rares, compose pour aimant anisotrope lie composite de terres rares, et procede de production de l'aimant
EP1494251A4 (fr) * 2002-04-09 2007-07-25 Aichi Steel Corp Aimant anisotrope lie composite de terres rares, compose pour aimant anisotrope lie composite de terres rares, et procede de production de l'aimant
EP1523017A3 (fr) * 2003-10-10 2007-07-11 Aichi Steel Corporation Aimant agglomeré anisotrope de terre rare composite, composition pour un aimant agglomeré anisotrope de terre rare composite, et procédés de production associés
US7357880B2 (en) 2003-10-10 2008-04-15 Aichi Steel Corporation Composite rare-earth anisotropic bonded magnet, composite rare-earth anisotropic bonded magnet compound, and methods for their production

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TW294815B (fr) 1997-01-01
EP0654801B1 (fr) 2000-06-07
DE69424845D1 (de) 2000-07-13
DE69424845T2 (de) 2000-12-07
EP0654801A3 (fr) 1995-07-05

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