JP2002528910A - Injection-molded soft magnetic powder composite material and method for producing the same - Google Patents

Abstract

  (57) [Summary] In an injection-molded soft magnetic material comprising at least one alloy powder of a nanocrystalline ferromagnetic alloy, the alloy is embedded in a synthetic resin and the alloy powder is distributed in the synthetic resin at a concentration of 10 to 70% by volume.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an injection-molded soft magnetic powder composite material. Such soft magnetic powder composites as compression cores have been known for a long time and are used in particular in inductive components.

[0002] Compressed powder composites of iron powder are known. About 10 to 300
Is sufficiently covered. The saturation magnetic induction achievable with this core is about 1
. 6T. The applied frequency is typically below 50 kHz due to the relatively low resistivity and the particle size of the iron particles.

[0003] In addition, a compressed powder composite core made of a soft magnetic crystal iron / aluminum / silicon alloy is known. With both powder composites, a magnetic permeability of 20-120 is achieved with 1T of saturation magnetic induction. Applicable frequency is 100kHz due to relatively high specific resistance
To reach more.

With regard to saturation magnetic induction, powder composites based on crystalline nickel-iron alloys are the best. In this case, depending on the nickel content, a magnetic permeability of up to about 500 or a saturation magnetic flux density of about 1.5T is achieved. It can be applied at frequencies up to and above 100 kHz due to the relatively small hysteresis loss.

[0005] However, a common disadvantage of all these known powder composites is that only very simple structural shapes can be realized by the pressing technique used for their production. In the case of iron powder composites, this structure is mainly an annular or outer iron core. With the other powder composites mentioned above, only annular magnetic cores can be made. Further, in order to obtain good soft magnetic properties, heat treatment is usually required following molding, except for the iron powder core.

An object of the present invention is therefore to provide a new powder composite material which can achieve a simple and cost-effectively complex structural shape and at the same time good soft magnetic properties.

According to the invention, the object consists, in accordance with the invention, of at least one alloy powder of a nanocrystalline ferromagnetic alloy, which is embedded in an injection-moldable synthetic resin, the alloy powder being added to the synthetic resin. The problem is solved by an injection molded soft magnetic powder composite characterized by being distributed in a synthetic resin at a concentration of ~ 70% by volume.

[0008] By using nanocrystalline alloys, for example, high permeability, very low coercivity,
Excellent soft magnetic properties such as very low hysteresis loss, relatively high saturation magnetic induction and little magnetostriction are obtained.

[0009] Such nanocrystalline alloys are known, for example, from EP-A-0271657 and EP-A-0 455 113.

As is evident from both of these patents, these alloys are produced in the form of sheets by the melt spinning technique described therein, and the sheets are heat treated to produce a nanocrystalline structure.

Further, the magnetic properties of the injection-molded plate are adjusted by heat treatment in a magnetic field. Because nanocrystalline sheet materials are inherently very fragile, they can be easily broken down into small pieces (flakes) without much difficulty, but even in this case, noticeable damage to soft magnetic properties can not see. By subdividing the nanocrystalline alloy plate, the original plate thickness is typically 10 μm to 30 μm, and the horizontal dimension is particularly 0.1 μm.
An alloy powder consisting of flakes of 0.5 to 2 mm is obtained. Horizontal dimensions smaller than this will adversely affect permeability. If the alloy powder is further subdivided, then the required milling energy will lead to tissue destruction and a distinct increase in the coercive force of the powder.

On the other hand, when the alloy powder is subdivided so as not to be damaged, especially when it is folded so as not to be damaged, it hardly exceeds the coercive force of the initial material of the nanocrystal, and is therefore unmatched in the field of powder composite magnetic core. Is obtained.

[0013] This makes it possible to omit the heat treatment after the final shape formation for producing or reproducing good soft magnetic properties.

Other assumptions sufficient for use at high operating frequencies are, in part, that the specific resistance of the alloy itself is as high as possible, and, in addition, that the particle insulation of the individual flakes to suppress volume eddy currents. That is good. Due to the high metalloid content of the nanocrystals, they naturally have a high specific resistance and therefore can easily be used at high operating frequencies.

[0015] To suppress volume eddy currents, the flakes are, however, typically surface-coated. Particularly suitable as this surface coating are coatings of polymers containing silicon oxide, so-called silanes or silanols made therefrom, in part on the surface oxidation of the flakes. Surface oxidation of the flakes and further coatings of silanes thereon give particularly good results.

[0016] The alloy powder thus treated is then injection molded. The synthetic resin required for injection molding is then kneaded with the treated alloy powder, and the resulting mixture is subsequently injected on a conventional injection molding machine.

Compared to the methods known from the prior art, in this case, the synthetic resin is temporarily used as a binder (ie, the binder is usually used for further compaction of the molded article following injection molding. (Removed again by the sintering process), but also acts as an electrical insulator.

A tool pressure and temperature parameter commonly used when stamping with a tool in making molded articles from alloy powders of the nanocrystalline alloy, due to the very small ductility of the nanocrystalline alloy It has been found that packing densities of typically about 65% in magnetic materials are obtained. Higher packing density is a pressure of 15 t / cm ² and a temperature of about 500 ° C.
Is achieved for the first time.

This degree can, however, be achieved without problems by the injection molding method proposed here, so that the use of this method does not have to suffer from the technical disadvantages of the application.

This synthetic resin remains in the molded article after the injection molding and functions as a binder. The choice of the synthetic resin used depends in part on the needs of the injection molding process and in others on the properties of the molding to be obtained.

It is desired that the viscosity of the melt is small, the molded article has good properties with respect to the permanent use temperature, and has high strength at high temperatures.

In use, polyamides and so-called liquid crystal synthetic resins are particularly excellent.
If there is a remarkable demand for heat resistance, high-temperature thermoplastic synthetic resin
For example, polyphenyl sulfide is used.

Using the nanocrystalline alloy Fe _73.5 Cu ₁ Nb ₃ Si _15.5 B ₇ and polyamide as binder according to the method described above, a saturation magnetic induction of about 0.7 T, a permeability μ of 10 to 100 and a permeability of 100 kHz About 60W at frequency and 0.1T saturation magnetic induction
Injection molded soft magnetic cores with hysteresis loss of / kg were produced.

In this case, the nanocrystalline sheet having the above composition was formed by a known melt spinning technique, and then heat-treated in a hydrogen atmosphere to adjust the nanocrystalline structure. The heat treated alloy sheet was then ground into flakes having a thickness of about 20 μm and a horizontal grain size of about 1.5 mm. The flakes made in this way are 400 ° C-540 ° C
At a temperature of 2 hours.

After this oxidation, the flakes are coated with silane, and the resulting silane coating is
It was fired at a temperature of 0 to 200 ° C. for about 1 hour. Other organic lacquers which form the film can be used instead of the silane film. The prerequisite in this case, however, is that the resin has sufficient thermal stability for the temperatures required for injection molding.

In this sense, therefore, the use of soluble polyamide resins or silane resins is also considered. With this additional surface coating a further improvement of the hysteresis loss can be achieved. The flakes thus treated are then kneaded (mixed) with the polyamide and finally injection molded.

It is noted that in the method presented above, the silane used is compatible with the synthetic resin required for injection molding. When using polyamide as a synthetic resin, for example, aminosilane is used, and when using polyphenyl, glycidylsilane is used.

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Claims (16)

[Claims] The powder composite comprises at least one alloy powder of a nanocrystalline ferromagnetic alloy embedded in an injection-moldable synthetic resin, wherein the alloy powder is 10 to 10 nm.
An injection-molded soft magnetic powder composite material which is distributed in the synthetic resin at a concentration of 70% by volume. 2. The injection-molded soft magnetic powder composite according to claim 1, wherein the alloy powder has an average particle size of 0.05 to 2 mm. 3. The powder composite material has a saturation magnetization B _S > 0.5 T and a magnetic permeability of 10 ≦ μ ≦
3. The injection-molded soft magnetic powder composite according to claim 1, wherein the composite has 200. 4. The nanocrystalline ferromagnetic alloy substantially following formula _{(Fe 1-a M a)} 100-xyz- αCu x Si y B z M'α ( where, M is Co and / or Ni, M 'is The elements Nb, W, Ta, Zr, Hf,
A, x, y, z and α are each at least one of Ti and Mo;
≦ 0.5, 0.1 ≦ x ≦ 3, 0 ≦ y ≦ 30, 0 ≦ z ≦ 25, 5 ≦ y + z ≦ 30,
0.1 ≦ α ≦ 30), wherein at least 50% of the alloy structure is occupied by microcrystalline particles having an average particle size of 100 nm or less. Magnetic powder composite material. 5. The nanocrystalline ferromagnetic alloy substantially following formula _{(Fe 1-a M a)} 100-xyz- α - β - γCu x Si y B z M'αM "βXγ ( where, M is Co and / Or Ni and M ′ are elements of Nb, W, Ta, Zr, Hf,
At least one of Ti and Mo; M ″ is at least one of the elements V, Cr, Mn and Al, one element of the platinum group, one rare earth element of Sc and Y, Au, Zn, Sn and / or Re. X is at least one of the elements C, Ge, P, Ga, Sb, In, Bi, and As; a, x, y, z, α, β, and γ are conditions 0 ≦ a ≦ 0.5, 0, respectively. .
1 ≦ x ≦ 3, 0 ≦ y ≦ 30, 0 ≦ z ≦ 25, 5 ≦ y + z ≦ 30, 0.1 ≦ α ≦ 3
0, β ≦ 10, γ ≦ 10), wherein at least 50% of the alloy structure is microcrystalline particles having an average particle size of 100 nm or less. Powder composite. 6. The nanocrystalline ferromagnetic alloy has a formula (Fe _{1 -a} M _a ) _b B _x M ′ _y M ″ _z (where M is the element Co and / or Ni, M ′ is Ti, Zr, Hf, V, Nb,
At least one of Ta, Mo, W, in this case Zr and / or Hf, is always included;
M "is at least one of the elements Cu, Ag, Au, Pd, Pt; a, b,
x, y, and z are conditions 0 ≦ a ≦ 0.05, 0 ≦ b ≦ 93, and 0.5 ≦ x ≦ 16, respectively.
, 4 ≦ y ≦ 10, 0 ≦ z ≦ 4.5), wherein the soft magnetic powder composite material is injection-molded. 7. The injection-molded soft magnetic powder composite material according to claim 1, wherein a polyamide is used as the synthetic resin. 8. The soft magnetic powder composite material according to claim 1, wherein polyphenyl sulfide is used as the synthetic resin. 9. The method according to claim 1, further comprising the steps of: producing an alloy powder comprising a nanocrystalline ferromagnetic alloy; kneading the alloy powder together with at least one organic binder; and injection-molding the resulting mixture. A method for producing the injection-molded soft magnetic powder composite according to the above. 10. The method according to claim 9, wherein the alloy powder is produced by subdivision of a thin alloy plate produced by a melt spinning technique. 11. The method according to claim 9, wherein the alloy sheet is heat-treated before fragmentation. 12. The method according to claim 9, wherein the surface of the alloy powder is oxidized.
A method according to one of the preceding claims. 13. The alloy powder having a temperature of 400 ° C. <T <540 ° C. and a temperature of 0.1 h <t <
13. The method according to claim 12, wherein the surface is oxidized for a period of 5 h. 14. A method according to claim 12, wherein the surface-oxidized alloy powder comprises a silane coating. 15. A film of silane having a temperature of 80 ° C. ≦ T ′ ≦ 200 ° C. for 0.1 h ≦
The method according to claim 14, wherein the calcination is performed for a time of t '? 3h. 16. Use of the powder composite according to one of claims 1 to 8 for the production of an inductive component.