Method for producing magnetic component using amorphous or nanocrystalline soft magnetic material

Abstract

The present disclosure provides a method for producing a magnetic component that enables efficient processing of an amorphous soft magnetic material or a nanocrystalline soft magnetic material. The method for producing a magnetic component comprising an amorphous soft magnetic material or nanocrystalline soft magnetic material comprises: a step of preparing a stacked body comprising a plurality of plate-shaped amorphous soft magnetic materials or nanocrystalline soft magnetic materials; a step of heating at least a portion of shearing in the stacked body to a temperature equal to or higher than the crystallization temperature of the soft magnetic materials; and a step of shearing the stacked body at the portion of shearing after the step of heating.

Claims

1. A method for producing a magnetic component comprising an amorphous soft magnetic material or a nanocrystalline soft magnetic material comprising: preparing a first stacked body comprising a plurality of plate-shaped amorphous soft magnetic materials or nanocrystalline soft magnetic materials; heating at least a portion of shearing in the first stacked body to a temperature equal to or higher than the crystallization temperature of the soft magnetic materials, wherein the heating includes fusion-cutting the first stacked body at a position outside the portion of shearing so as to remove a fusion-cut stacked body from the first stacked body; and shearing the fusion-cut stacked body at the portion of shearing after the heating.

2. The method for producing a magnetic component according to claim 1, wherein the fusion-cutting includes laser cutting, plasma cutting, or gas cutting.

3. The method for producing a magnetic component according to claim 1, wherein the fusion-cut stacked body is sheared via punching out using a press die.

4. The method for producing a magnetic component according to claim 1, wherein the fusion cutting includes cutting with a laser beam.

5. The method for producing a magnetic component according to claim 1, wherein the first stacked body is fusion-cut at a position about 0.1 to 0.5 mm outside of the portion of shearing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a graph showing examples of hardness (HV) of an electromagnetic steel sheet (composition: Fe-3 mass % Si) and that of an amorphous soft magnetic material (composition: Fe.sub.84B.sub.13Ni.sub.3).

(2) FIG. 2 shows a graph showing examples of hardness (HV) of an amorphous soft magnetic material (composition: Fe.sub.84B.sub.13Ni.sub.3), that of an amorphous soft magnetic material after a heat treatment, and that of an electromagnetic steel sheet (composition: Fe-3 mass % Si).

(3) FIG. 3 shows a schematic process diagram explaining the steps in Example 1.

(4) FIG. 4 shows a graph demonstrating the results of Example 1 and Comparative Example 1.

(5) FIG. 5 shows a schematic process diagram explaining the steps in Example 2.

(6) FIG. 6 shows a graph showing the results of Example 2 and Comparative Example 2.

(7) FIG. 7 shows an electron micrograph showing a cross section of the fusion-cut stacked body obtained in Example 2.

DETAILED DESCRIPTION

(8) The present embodiment relates to a method for producing a magnetic component comprising an amorphous soft magnetic material or a nanocrystalline soft magnetic material, comprising: a step of preparing a stacked body comprising a plurality of plate-shaped amorphous soft magnetic materials or nanocrystalline soft magnetic materials; a step of heating at least a portion of shearing in the stacked body to a temperature equal to or higher than the crystallization temperature of the soft magnetic materials; and a step of shearing the stacked body at the portion of shearing after the step of heating. In the present embodiment, the portion of shearing of the amorphous soft magnetic material or the nanocrystalline soft magnetic material is heated to a temperature equal to or higher than a crystallization temperature of the soft magnetic materials (e.g., 400 C. or higher), thereby lowering the hardness of the heated portion. This is because crystallization of the soft magnetic material proceeds and the hardness thereof is lowered as a result of the heating. Then, the stacked body is sheared at the portion of shearing where hardness is lowered with the use of a tool such as a press die. As a result, a magnetic component can be prepared while suppressing abrasion of a tool used for shearing.

(9) Hereafter, the present embodiment is described in detail.

(10) [Step of Preparation]

(11) In the present embodiment, at the outset, a stacked body in which a plurality of plate-shaped amorphous soft magnetic materials or nanocrystalline soft magnetic materials superposed on the surfaces of each other is prepared.

(12) Examples of the amorphous soft magnetic materials or the nanocrystalline soft magnetic materials include, but are not limited to, materials comprising at least one magnetic metal selected from the group consisting of Fe, Co, and Ni and at least one non-magnetic metal selected from the group consisting of B, C, P, Al, Si, Ti, V, Cr, Mn, Cu, Y, Zr, Nb, Mo, Hf, Ta, and W. Representative examples of the amorphous soft magnetic materials or nanocrystalline soft magnetic materials include, but are not limited to, FeCo-based alloys (e.g., FeCo and FeCoV), FeNi-based alloys (e.g., FeNi, FeNiMo, FeNiCr, and FeNiSi), FeAl-based alloys or FeSi-based alloys (e.g., FeAl, FeAlSi, FeAlSiCr, FeAlSiTiRu, and FeAlO), FeTa-based alloys (e.g., FeTa, FeTaC, and FeTaN), and FeZr-based alloys (e.g., FeZrN). As other amorphous soft magnetic materials or nanocrystalline soft magnetic materials, for example, Co alloys comprising Co and at least one metal selected from among Zr, Hf, Nb, Ta, Ti, and Y can be used. In some embodiments, Co content in the Co alloys may be 80 at % or more. Such a Co alloy easily becomes amorphous at the time of film formation and it exhibits excellent soft magnetic properties due to low-level crystalline magnetic anisotropy, crystal defect, and grain boundary. Examples of amorphous soft magnetic materials include CoZr, CoZrNb, and CoZrTa-based alloys.

(13) An amorphous soft magnetic material has an amorphous structure as a main structure. In the amorphous structure, no clear peak is observed in X-ray diffraction patterns, but only broad halo patterns are observed. While a nanocrystalline structure can be formed with the application of a thermal treatment to an amorphous structure, a diffraction peak is observed at a position corresponding to an interstitial space of a crystal plane in the nanocrystalline soft magnetic material having a nanocrystalline structure. A crystallite diameter can be calculated on the basis of the width of the diffraction peak using the Scherrer equation. In general, the term nanocrystals refers to crystals having a crystallite diameter of less than 1 m, which is calculated on the basis of the half width of the diffraction peak obtained via X-ray diffraction analysis using the Scherrer equation. In some embodiments, the crystallite diameter of nanocrystals (i.e., a crystallite diameter calculated on the basis of the half width of the diffraction peak obtained via X-ray diffraction analysis using the Scherrer equation) may be 100 nm or less, and may be 50 nm or less. In some embodiments, the crystallite diameter of nanocrystals may be 5 nm or more. When the crystallite diameter of nanocrystals is of the size as described above, a soft magnetic property is improved. A crystallite diameter of a conventional electromagnetic steel sheet is micro order (m), and it is generally 50 m or more.

(14) An amorphous soft magnetic material can be obtained, for example, by melting a starting metal material blended to have a desired composition at a high temperature in a high-frequency melting furnace or the like to obtain a uniform molten metal, and then quenching it. Alternatively, the molten metal of the starting metal material can be applied to a rotating cooling roll to obtain a thin plate-shaped amorphous soft magnetic material (which is also referred to as a ribbon-shaped).

(15) A nanocrystalline soft magnetic material can be prepared by further subjecting the amorphous soft magnetic material to an adequate thermal treatment. Conditions for the thermal treatment are not particularly limited, and adequate conditions can be selected in accordance with, for example, the composition of a starting metal material or magnetic properties to be expressed. For example, the thermal treatment is carried out at a temperature higher than the crystallization temperature of the soft magnetic material to be used, although the temperature is not limited. By subjecting an amorphous soft magnetic material to the thermal treatment, an amorphous soft magnetic material can be converted into a nanocrystalline soft magnetic material. In addition, nanocrystals are allowed to deposit in the amorphous soft magnetic material to improve magnetic properties of interest. In some embodiments, the thermal treatment may be carried out in an inert gas atmosphere.

(16) In some embodiments, the surface of the amorphous soft magnetic material or the nanocrystalline soft magnetic material may be covered by an insulation film. An example of the insulation film is an oxide film such as SiO.sub.2. With the insulation film, a loss caused by an eddy current can be reduced.

(17) Before the thermal treatment step described below, the hardness of the amorphous soft magnetic material is, for example, 300 HV or higher, and may be 500 HV or higher. Before the thermal treatment step described below, the hardness of the nanocrystalline soft magnetic material is, for example, 300 HV or higher, and may be 600 HV or higher.

(18) A thickness of a plate-shaped soft magnetic material is, for example, 5 to 50 m, and may be 15 to 35 m. A plurality of plate-shaped soft magnetic materials are superposed on the surfaces of each other to form a stacked body. While a thickness of the stacked body is not particularly limited, it is, for example, 20 to 1,000 m, and may be 50 to 500 m. The number of the plate-shaped soft magnetic materials to be superposed on the surfaces of each other may be 20 or less.

(19) An adhesive layer such as a thermostable resin may or may not be provided between the plate-shaped soft magnetic materials. An example of the thermostable resin that can be used is a thermosetting resin, and examples of the thermosetting resin include an epoxy resin, a polyimide resin, a polyamide imide resin, and an acrylic resin.

(20) [Step of Thermal Treatment]

(21) Subsequently, at least a portion of shearing in the stacked body is heated to a temperature equal to or higher than the crystallization temperature of the soft magnetic material. The portion of shearing in the stacked body means a portion which is sheared with the use of, for example, a press die in the later step.

(22) When the amorphous soft magnetic material or nanocrystalline soft magnetic material is heated to a temperature equal to or higher than the crystallization temperature, crystallization will proceed. As crystallization proceeds, the hardness is lowered. Thus, it becomes easy to perform shearing in the later step. For example, by heating an amorphous soft magnetic material (composition: Fe.sub.84B.sub.13Ni.sub.3) to a temperature equal to or higher than the crystallization temperature to proceed crystallization, the hardness thereof is lowered, and the hardness of the heated area becomes equivalent to, for example, that of an electromagnetic steel sheet (composition: Fe-3 mass % Si), as shown in FIG. 2. The hardness of the amorphous soft magnetic material is about 609 HV before the thermal treatment step, and it is lowered to about 231 HV after the thermal treatment step. The thermal treatment step was carried out by placing the amorphous soft magnetic material (thickness: 30 m) into a heating furnace and then heating the material at 400 C. for 60 seconds. The hardness was measured at 23 C. This demonstrates that the hardness of the soft magnetic material can be reduced by heating the soft magnetic material to a temperature equal to or higher than the crystallization temperature.

(23) The crystallization temperature means a temperature in which crystallization takes places. At the time of the crystallization, an exothermic reaction takes places. Thus, the crystallization temperature can be determined by measuring the temperature change accompanying the crystallization. For example, a differential scanning calorimeter (DSC) can be used to measure the crystallization temperature at a predetermined heating speed (e.g., 0.67 Ks.sup.1). The crystallization temperature of the amorphous soft magnetic material varies depending on materials. For example, the crystallization temperature is 300 C. to 500 C. Also, the crystallization temperature of the nanocrystalline soft magnetic material can be measured via differential scanning calorimetry (DSC). Although crystallization has already occurred in the nanocrystalline soft magnetic material, further crystallization would take place by heating such material to a temperature equal to or higher than the crystallization temperature. The crystallization temperature of the nanocrystalline soft magnetic material is, for example, 300 C. to 500 C., although it varies depending on the materials.

(24) A heating temperature in the thermal treatment step is not particularly limited as long as it is equal to or higher than the crystallization temperature. For example, the heating temperature is 350 C. or higher, and may be 400 C. or higher. By adjusting the heating temperature at 400 C. or higher, crystallization can proceeds efficiently. The heating temperature is, for example, 600 C. or lower, and may be 520 C. or lower. By adjusting the heating temperature at 520 C. or lower, it becomes easy to prevent excessive crystallization, and generation of by-products (e.g., Fe.sub.2B) can be suppressed.

(25) The heating time in the thermal treatment step is not particularly limited. In some embodiments, the heating time may be 1 second to 10 minutes, and may be 1 second to 5 minutes.

(26) The thermal treatment may be performed such that the hardness of the soft magnetic material after the thermal treatment (at room temperature; e.g., 23 C.) becomes 300 HV or less (in some embodiments, 250 HV or less) from the viewpoint of processability. The hardness of the soft magnetic material after the thermal treatment can be regulated by adjusting heating temperature, heating duration, and other conditions.

(27) The heat treatment may be performed by heating at least the portion of shearing of the stacked body. Namely, the stacked body may be heated in at least the portion of shearing. Only the portion of shearing may be heated, or the entire stacked body may be heated. In some embodiments, the thermal treatment may be performed by heating only the portion of shearing. However, due to a thermal conduction, the thermal treatment is actually performed with a certain width, and crystallization takes place. In order to leave the region of the initial state as much as possible, the portion of shearing may be heated by heating a region slightly outside the actual portion of shearing.

(28) A method for heating the portion of shearing is not particularly limited. For example, a metal tool configured to abut against the portion of shearing (or a metal tool configured to abut against the portion outside in the vicinity of the portion of shearing) is pressed against the surface of the stacked body in a heated state. A metal tool configured to abut against the portion of shearing can be prepared by imitating, for example, the press die used in the later step. For example, a method for heating the portion of shearing includes an irradiation of a laser beam to the portion of shearing. As described above, the thermal treatment is performed with a certain width due to the thermal conduction. Thus, in some embodiments, when heating via laser irradiation, the portion of shearing may be heated by irradiating a laser beam to the portion slightly outside the actual portion of shearing (e.g., the portion outside the actual portion of shearing by about 0.1 to 0.5 mm). In some embodiments, the portion of shearing may be heated by irradiating a laser beam to the portion about 0.1 to 0.3 mm outside the actual portion of shearing.

(29) When the portion of shearing is heated via laser application, the stacked body may be fusion-cut simultaneously with heating of the portion of shearing via laser application. In such a case, as shown in, for example, FIG. 7, the layers of the soft magnetic materials may be fused to each other at the portion of laser cutting. The fused portion can be removed in the later step of shearing. In addition to laser cutting, for example, plasma cutting or gas cutting may be employed. The stacked body is first fusion-cut via laser cutting or other means and then punched out at the portion of shearing. Thus, excellent dimensional accuracy can be achieved. Accordingly, in some embodiments of the present disclosure, the step of the thermal treatment comprises fusion-cutting the stacked body at a position outside the portion of shearing to heat the portion of shearing. Then, the stacked body can be sheared via a process of punching out with the use of a press die. The stacked body can be fusion-cut at a position, for example, outside of the portion of shearing by about 0.1 to 0.5 mm. In some embodiments, the stacked body may be fusion-cut at a position about 0.1 to 0.3 mm outside of the portion of shearing.

(30) [Step of Shearing]

(31) Subsequently, the stacked body is sheared at the portion of shearing after the step of the thermal treatment. Thus, a magnetic component can be obtained. Shearing is performed at a position where crystallization proceeds and the hardness is lowered as a result of the thermal treatment. Therefore, even in the case of using the amorphous soft magnetic material or the nanocrystalline soft magnetic material having a high hardness, abrasion of a tool for shearing can be suppressed.

(32) In some embodiments, shearing may be carried out by punching out the stacked body with the use of a press die. For example, as a press die that can be used, super steel may be used. Prior to the process of punching out, a mold and/or a stacked body (in particular, the portion of shearing) may be coated with a lubricant.

(33) In the manner described above, even in the case of using the amorphous soft magnetic material or the nanocrystalline soft magnetic material having a high degree of hardness, a magnetic component can be produced while suppressing abrasion of a tool (or apparatus) used in the step of shearing.

(34) The magnetic component obtained may be subjected to a further processing as necessary, and can be used for desired electric apparatus of interest. Examples of magnetic components include, but are not particularly limited to, core materials of rotors or electric reactors, voltage convertors, and firing plugs.

EXAMPLES

(35) Hereafter, examples of the present disclosure are described; although the technical scope of the present disclosure is not restricted by the following examples.

Example 1

(36) Example 1 is performed in accordance with a schematic process diagram shown in FIG. 3. Namely, an amorphous plate (thickness: 30 m; crystallization temperature: 400 C.; hardness: 609 HV) was prepared as an amorphous soft magnetic material, the portion of shearing thereof was heated and punched out with the use of a press die, and then an extent of press die abrasion was evaluated. The crystallization temperature was determined by measuring the exothermal peak at a heating rate of 0.67 Ks.sup.1 via differential scanning calorimetry (DSC).

(37) First, the amorphous plate 11 was prepared. Also, a mold 12 configured to abut against a portion to be sheared by a press die in a later step in the surface of the amorphous plate 11 was prepared. Then, while heating the mold 12 at 400 C., the mold was pressed against the amorphous plate 11 for 10 seconds in the air atmosphere (FIG. 3 (A)). Thus, the portion of shearing was heated, and a partially crystallized amorphous plate 11 was obtained (FIG. 3 (B)). In FIG. 3B, the heated regions are indicated by numeral references 13a and 13b, respectively.

(38) Subsequently, the surface of the amorphous plate 11 was coated with a lubricant, the plate was mounted on a press machine, and the plate was then punched out with the use of a press die 14 (FIG. 3 (C)). Super steel was used as a material of the press die 14 and the plate was punched out at a rate of 260 mm/sec. Thereby, the amorphous plate was punched out in a ring shape (outer diameter: 30 mm; inner diameter: 25 nn) (FIG. 3 (D)).

(39) This process of punching out was repeated 1,000 times, and the degree of abrasion of the press die was examined.

Comparative Example 1

(40) The amorphous plate 11 was punched out in a ring shape in the same manner as in Example 1, except that the portion of shearing was not subjected to the thermal treatment. This process of punching was repeated 1,000 times and the degree of abrasion of the press die was examined.

(41) (Results)

(42) FIG. 4 shows the results of press die abrasion in Example 1 and Comparative Example 1. It was confirmed that the degree of press die abrasion was very low in Example 1 while the degree of press die abrasion was high in Comparative Example 1. The results demonstrate that hardness of an amorphous plate can be reduced by thermal treatment, and then press die abrasion can be suppressed.

Example 2

(43) Example 2 is performed in accordance with a schematic process diagram shown in FIG. 5. Namely, a stacked body was prepared using amorphous plates (thickness: 25 m; crystallization temperature: 490 C.; hardness: 535 HV) as amorphous soft magnetic materials, the stacked body was cut (fusion-cut) by heating the portion of shearing with a laser beam, and the stacked body was then punched out with the use of a press die.

(44) At the outset, 6 amorphous plates were superposed on the surfaces of each other to form a stacked body 21 (FIG. 5 (A)).

(45) Subsequently, the stacked body was fusion-cut in a ring shape along a line 0.1 mm outside the portion to be sheared in a later step using a laser beam of 0.5 kW or more from a laser irradiation apparatus 22 (FIG. 5 (b)). FIG. 7 shows an electron micrograph of a cross section of the stacked body 23 cut out by fusion-cutting. As shown in FIG. 7, layers were fused to each other in the edges of the fusion-cut region. In addition, crystallization was observed in the region of about 200 m from the edge. As shown in the portion indicated by the white circle, fracture was also observed. This indicates that the hardness of that portion is significantly reduced. In the electron micrograph shown in FIG. 7, the black regions between layers are the parts infiltrated with the resin used for photographing.

(46) Subsequently, the surface of the stacked body 23 cut out via fusion-cutting was coated with a lubricant, and the stacked body was mounted on a press machine. Then, the stacked body was punched out in a ring shape (outer diameter: 30 mm; inner diameter: 25 mm) with the use of the press die 24 (super steel) at a rate of 260 mm/sec (FIG. 5 (c)). As a result, the fused portions were removed, and a magnetic component 25 was obtained with excellent dimensional accuracy.

(47) This process of punching was repeated 1,000 times and the degree of press die abrasion was examined.

Comparative Example 2

(48) The stacked body composed of 6 amorphous plates superposed on the surfaces of each other was coated with a lubricant, and the stacked body was punched out with the use of the press die 24 at a rate of 260 mm/sec without thermal treatment. This process of punching was repeated 1,000 times and the degree of press die abrasion was examined.

(49) (Results)

(50) FIG. 6 shows the results of press die abrasion examined in Example 2 and Comparative Example 2. It was confirmed that the degree of press die abrasion was very low in Example 2 while the degree of press die abrasion was high in Comparative Example 2. The results demonstrate that the hardness of an amorphous plate can be lowered by performing thermal treatment with laser irradiation and that press die abrasion can be suppressed by punching out the stacked body at the region where the hardness is lowered.

(51) While embodiments of the present disclosure were described in detail with reference to the figures, specific constitutions of the invention are not limited to the embodiments described above. The present disclosure encompasses design modification made within the scope of the present disclosure.

DESCRIPTION OF SYMBOLS

(52) 11: Amorphous plate 11: Amorphous plate after thermal treatment 12: Heated mold (metal tool) 13: Heated region 14: Press die 21: Stacked body (6-layered amorphous plates) 22: Laser applicator 23: Fusion-cut stacked body 24: Press die 25: Magnetic component