Powder compact

Abstract

To provide a powder compact capable of preventing the occurrence of chips and cracks.SOLUTION: A powder compact includes soft magnetic powder and an insulation coating layer coating around the soft magnetic powder. The insulation coating layer includes a silicone resin and a silane coupling agent, the molecular weight of the silane coupling agent being 244.4 or more and 260.4 or less. The occurrence of chips and cracks in the powder compact can be prevented by adjusting the molecular weight of the silane coupling agent to 244.4 or more and 260.4 or less. In particular, it is preferable to adjust the molecular weight of the silane coupling agent to 244.4 or more and 248.4 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a powder compact. [Background technology]

[0002] Coil components such as reactors are used in a variety of applications, including office equipment, solar power generation systems, automobiles, and uninterruptible power supplies. For example, a reactor is an electromagnetic component that converts electrical energy into magnetic energy and stores and releases it. A reactor primarily comprises a core and a coil. The coil is wound around the core. When power is supplied to the coil, it generates magnetic flux. The core is ring-shaped. The core serves as a magnetic path through which the magnetic flux generated by the coil flows.

[0003] Powder magnetic cores are sometimes used as reactor cores. Powder magnetic cores are produced by heat treating a powder compact. The powder compact is formed, for example, by pressing soft magnetic powder with an insulating coating formed on the surface. In this pressing, a pressure of 10 to 20 ton / cm is generally applied. 2 This is done under high pressure. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-125622 Summary of the Invention [Problem to be solved by the invention]

[0005] In high-pressure compaction, if the binding strength between the soft magnetic powder particles is weak, chips and cracks may occur in the powder compact. In some cases, the legs of the powder compact may come off, making it impossible to form the powder compact into the desired shape.

[0006] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a powder molded body that can prevent chipping and cracks from occurring in the powder molded body. [Means for solving the problem]

[0007] The powder compact of the present invention comprises a soft magnetic powder and an insulating coating layer that covers the periphery of the soft magnetic powder, the insulating coating layer being made of only a silicone resin and a silane coupling agent, The coating is formed by laminating a single layer of a mixed layer of the silane coupling agent and the silicone resin, or two layers of the silane coupling agent and the silicone resin, The molecular weight of the silane coupling agent is 244.4 or more and 260.4 or less. [Effects of the Invention]

[0008] According to the present invention, it is possible to obtain a powder molded body that can prevent chipping and cracks from occurring in the powder molded body. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a graph showing the relationship between the rattle value and the molecular weight of the silane coupling agent when the amount of the silane coupling agent added is 0.5 wt %. [Figure 2] 1 is a graph showing the relationship between the Rattle value and the molecular weight of the silane coupling agent when the amount of the silane coupling agent added is 1.0 wt %. DETAILED DESCRIPTION OF THE INVENTION

[0010] The configuration of the powder molded body of this embodiment will be described below, but the present invention is not limited to the embodiment described below.

[0011] Coil components such as reactors have a core containing a magnetic material. Powder magnetic cores are used as the core. Powder magnetic cores are produced by compressing soft magnetic powder into a compact and then subjecting the compact to a heat treatment called annealing.

[0012] The powder compact of this embodiment includes a soft magnetic powder and an insulating coating layer. The insulating coating layer covers the surface of the soft magnetic powder. The insulating coating layer contains a silane coupling agent and a silicone resin.

[0013] The soft magnetic powder is primarily composed of iron. Examples of soft magnetic powder that can be used include pure iron powder, iron-based permalloy (Fe-Ni alloy), Si-containing iron alloy (Fe-Si alloy), Sendust alloy (Fe-Si-Al alloy), and a mixture of two or more of these powders. Amorphous alloys and nanocrystalline alloy powders may also be used as soft magnetic powders. The particle size (median diameter D50) of the soft magnetic powder is preferably 1 μm or more and 200 μm or less.

[0014] The Fe-Si-Al alloy powder contains, for example, about 7 wt% to 11 wt% of Si and about 4 wt% to 8 wt% of Al relative to Fe. The Fe-Si-Al alloy powder may also contain, for example, about 1 wt% to 3 wt% of Ni relative to Fe. Furthermore, the Fe-Si-Al alloy powder may also contain Co, Cr, or Mn.

[0015] The Si-containing iron alloy may contain Co, Al, Cr, or Mn. When using permalloy (Fe-Ni alloy), the ratio of Fe to Ni is preferably 50:50 or 25:75, but other ratios are also acceptable. For example, Fe-80Ni, Fe-36Ni, Fe-78Ni, or Fe-47Ni may be used. In addition to Fe and Ni, Si, Cr, Mo, Cu, Nb, Ta, etc. may also be contained. Examples of Fe-Si alloy powder include Fe-3.5% Si alloy powder and Fe-6.5% Si alloy powder, but the ratio of Si to Fe may be other than 3.5% or 6.5%. Pure iron powder contains 99% or more Fe.

[0016] The soft magnetic powder may be produced by a pulverization method or an atomization method, which may be any of water atomization, gas atomization, and water gas atomization.

[0017] However, since the pulverized powder produced by the pulverization method is non-circular, the soft magnetic powder particles tend to bond together, making it difficult for chips and cracks to occur in the green compact. On the other hand, the gas atomized powder produced by the atomization method, particularly the gas atomization method, is circular, so it tends to bond weakly and the green compact is likely to be brittle. For this reason, gas atomized powder is preferred as the soft magnetic powder, as this significantly demonstrates the effect of the present invention of preventing chips and cracks from occurring in the green compact.

[0018] The circularity of the soft magnetic powder is preferably 0.8 or more in terms of the powder's average particle size (median diameter D50). If the circularity is 0.8 or more, the binding strength between the soft magnetic powder particles is weak, and the compact tends to be brittle. Therefore, when the circularity of the soft magnetic powder is 0.8 or more, the effects of the present invention are more pronounced. Furthermore, the Vickers hardness of the soft magnetic powder is preferably 400 HV or more. With a hard soft magnetic powder having a Vickers hardness of 400 HV or more, the binding strength between the soft magnetic powder particles is weak, and the compact tends to be brittle, so the effects of the present invention are more pronounced.

[0019] An insulating coating layer is formed on the surface of the soft magnetic powder. The insulating coating layer contains a silane coupling agent and a silicone resin. The insulating coating layer can be applied to the surface of each individual particle of the soft magnetic powder, or to the surface of a bonded particle made up of several particles. It can also be applied to the entire surface or a portion of the surface of a particle. In other words, the insulating coating layer does not need to completely cover the surface of the soft magnetic powder, and can also be applied to only a portion of the surface of the soft magnetic powder.

[0020] The silane coupling agent may have a molecular weight of 244.4 or more and 260.4 or less. Examples of silane coupling agents that can be used include dimethoxydiphenylsilane, 3-glycidoxypropylmethyldiethoxysilane, hexyltriethoxysilane, and 3-methacryloxypropylmethyldiethoxysilane. By setting the molecular weight of the silane coupling agent to 244.4 or more and 260.4 or less, chipping and cracking can be prevented from occurring in the powder compact. In particular, it is preferable to set the molecular weight of the silane coupling agent to 244.4 or more and 248.4 or less. By setting the molecular weight within this range, chipping and cracking can be prevented from occurring in the powder compact, and stable low iron loss can be achieved.

[0021] The amount of the silane coupling agent added is preferably 0.3 wt% or more, and more preferably 0.5 wt% or more, relative to the soft magnetic powder. When the amount of the silane coupling agent added is 0.3 wt% or more, the effect of preventing chipping and cracking in the powder compact is achieved, and when the amount is 0.5 wt% or more, this effect becomes even more pronounced.

[0022] In particular, it is preferable that the molecular weight of the silane coupling agent is 244.4 or more and 248.4 or less, and the amount of the silane coupling agent added is 1.0 wt% or more. By setting the molecular weight and amount of the silane coupling agent within these ranges, the effect of preventing chipping and cracking in the powder compact becomes even more pronounced.

[0023] The upper limit of the amount of silane coupling agent added is preferably 1.5 wt% relative to the soft magnetic powder. When the amount of silane coupling agent added is 1.5 wt%, iron loss tends to worsen slightly compared to when 1.0 wt% of silane coupling agent is added. Therefore, if the amount of silane coupling agent added exceeds 1.5 wt%, there is a risk that iron loss will worsen further, so it is preferable to set the upper limit at 1.5 wt%.

[0024] Examples of silicone resins that can be used include silicone resins and silicone oligomers. Silicone resins are resins that have a siloxane bond (Si-O-Si) as their main skeleton. By using silicone resins, it is possible to form insulating coating layers with excellent flexibility. Examples of silicone resins that can be used include methyl-based, methylphenyl-based, propylphenyl-based, epoxy resin-modified, alkyd resin-modified, polyester resin-modified, and rubber-based.

[0025] Examples of silicone oligomers that can be used include methyl-based and methylphenyl-based ones that have an alkoxysilyl group but no reactive functional group, epoxy-based, epoxymethyl-based, mercapto-based, mercaptomethyl-based, acrylic methyl-based, methacrylic methyl-based, and vinylphenyl-based ones that have an alkoxysilyl group and a reactive functional group, and alicyclic epoxy-based ones that have a reactive functional group instead of an alkoxysilyl group.

[0026] As the silicone resin, it is preferable to use a methylphenyl-based resin. Specifically, it is preferable to use a methylphenyl-based silicone resin or silicone oligomer. When a methylphenyl-based silicone resin is used, an insulating coating layer with little loss in weight upon heating and excellent heat resistance can be formed. Furthermore, when a methylphenyl-based silicone oligomer is used, a thick and hard insulating coating layer can be formed.

[0027] The amount of silicone resin added is preferably 0.3 wt% or more and 2.0 wt% or less of the soft magnetic powder. If the amount added is less than 0.3 wt%, the insulating coating layer will not function, and eddy current loss will increase, resulting in reduced magnetic properties. If the amount added is more than 2.0 wt%, the density of the powder compact will decrease.

[0028] After adding and mixing the silane coupling agent and silicone resin to the soft magnetic powder, the powder is heated and dried to form an insulating coating layer on the surface of the soft magnetic powder. The heating and drying conditions are, but are not limited to, a temperature of 25°C to 350°C for about 2 hours.

[0029] The insulating coating layer may be a mixed layer of a silane coupling agent and a silicone resin, or may be a laminate of a silane coupling agent layer and a silicone resin layer. For example, when the insulating coating layer is a laminate of a silane coupling agent layer and a silicone resin layer in that order, the silane coupling agent is first added to and mixed with the soft magnetic powder, and the mixture is dried by heating. Then, the silicone resin is added to and mixed with the soft magnetic powder on which the silane coupling agent layer has been formed, and the mixture is dried by heating, forming a silicone resin layer on the surface of the silane coupling agent layer.

[0030] A lubricant may be added to the soft magnetic powder on which the insulating coating layer is formed. Examples of lubricants include, but are not limited to, stearic acid, calcium stearate, lithium stearate, aluminum stearate, zinc stearate, ethylene bisstearamide, ethylene bisstearamide, and ethylene bisstearamide. Adding a lubricant improves the sliding properties of the soft magnetic powder particles, thereby increasing the density of the green compact. Furthermore, it is possible to reduce the upper punch ejection pressure during compaction and prevent vertical streaks on the core wall due to contact between the die and the soft magnetic powder.

[0031] The amount of lubricant added is preferably about 0.2 wt% to 0.8 wt% of the soft magnetic powder. By setting the amount in this range, it is possible to further improve the sliding between the soft magnetic powder particles. The lubricant may be added twice, once before and after the insulating coating layer is formed. That is, the lubricant may be added to the soft magnetic powder before the silane coupling agent and silicone resin are added, and then added to the soft magnetic powder after the insulating coating layer has been formed.

[0032] After adding the lubricant, the soft magnetic powder is poured into a mold and subjected to pressure molding. This pressure molding produces a green compact. In the pressure molding, the soft magnetic powder is subjected to a pressure of 10 to 20 ton / cm. 2 The average pressure is 12 to 15 ton / cm.2 A degree is more preferable.

[0033] Thereafter, the powder compact produced by pressure molding is heat-treated in a non-oxidizing atmosphere such as nitrogen gas or a mixed gas of nitrogen and hydrogen, or in the air, at a temperature of 600°C or higher but lower than the temperature at which the insulating coating layer covering the soft magnetic powder is destroyed (for example, 900°C). Through this heat treatment, a powder magnetic core is produced.

[0034] (Example) The present invention will be described in more detail based on examples. However, the present invention is not limited to the following examples. Powder molded bodies of Examples 1 to 18 and Comparative Examples 1 to 14 were produced. The powder molded bodies of Examples 1 to 18 and Comparative Examples 1 to 14 differ only in the type and amount of silane coupling agent added.

[0035] First, a powder compact was produced for Example 1. Fe—Si—Al alloy powder produced by gas atomization was used as the soft magnetic powder. The particle size and circularity of the Fe—Si—Al alloy powder are shown in Table 1 below.

[0036] [Table 1]

[0037] First, a lubricant was added to the Fe-Si-Al alloy powder. Stearic acid (D50=100 μm, melting point 57°C) was used as the lubricant. 0.3 wt% of stearic acid was added to the Fe-Si-Al alloy powder and mixed.

[0038] After adding and mixing stearic acid, a silane coupling agent was added and mixed. Then, silicone resin was added and mixed. The silane coupling agent used was "C dimethoxydiphenylsilane" (product name: KBM202SS) shown in Table 2 below. Dimethoxydiphenylsilane was added at 0.3 wt% relative to the Fe-Si-Al alloy powder.

[0039] [Table 2]

[0040] A methylphenyl silicone resin was used as the silicone resin. 1.2 wt% of the silicone resin was added to the Fe-Si-Al alloy powder. After adding and mixing the silicone resin, the mixture was heated and dried. The drying temperature was 130°C, and the drying time was 2 hours.

[0041] After heating and drying, the Fe-Si-Al alloy powder was passed through a sieve with 850 μm openings to break down agglomerates. Then, a lubricant was added again and mixed. The lubricant used was aluminum stearate (D50 = 21 μm, melting point 110°C). Aluminum stearate was added at 0.2 wt% relative to the Fe-Si-Al alloy powder.

[0042] After adding and mixing the lubricant, the lubricated Fe-Si-Al alloy powder was filled into a die and pressed to produce a cylindrical green compact with an outer diameter of 11.3 mm and a height of 10.0 mm (height tolerance ±0.1 mm). The pressure for the press was 12.0 ton / cm. 2 Five powder compacts of Example 1 were produced.

[0043] Examples 2 to 5 differ from Example 1 only in the amount of silane coupling agent added, and other aspects, including the type of silane coupling agent, are the same as those in Example 1, using the same materials, manufacturing method, and conditions. The amount of silane coupling agent added is 0.5 wt% in Example 2, 0.7 wt% in Example 3, 1.0 wt% in Example 4, and 1.5 wt% in Example 5.

[0044] Example 6 differs from Example 1 only in the type of silane coupling agent, and other factors, including the amount of silane coupling agent added, are the same as those in Example 1, using the same materials, manufacturing method, and conditions. The silane coupling agent used in Example 6 was "D 3-glycidoxypropylmethyldiethoxysilane" (product name: KBE-402) shown in Table 2 above.

[0045] Examples 7 to 10 differ from Example 6 only in the amount of silane coupling agent added, and other factors, including the type of silane coupling agent, are the same as those in Example 6, using the same materials, manufacturing method, and conditions. The amount of silane coupling agent added is 0.5 wt% in Example 7, 0.7 wt% in Example 8, 1.0 wt% in Example 9, and 1.5 wt% in Example 10.

[0046] Example 11 differs from Example 1 only in the type of silane coupling agent, and other factors, including the amount of silane coupling agent added, are the same as those in Example 1, using the same materials, manufacturing method, and conditions. The silane coupling agent used in Example 11 was "E hexyltriethoxysilane" (product name: KBE-3063) shown in Table 2 above.

[0047] Examples 12 to 14 differ from Example 11 only in the amount of silane coupling agent added, and other factors, including the type of silane coupling agent, are the same as those in Example 11, using the same materials, manufacturing method, and conditions. The amount of silane coupling agent added is 0.5 wt% in Example 12, 1.0 wt% in Example 13, and 1.5 wt% in Example 14.

[0048] Example 15 differs from Example 1 only in the type of silane coupling agent, and other factors, including the amount of silane coupling agent added, are the same as those in Example 1, using the same materials, manufacturing method, and conditions. The silane coupling agent used in Example 15 was "F 3-methacryloxypropylmethyldiethoxysilane" (product name: KBE-502) shown in Table 2 above.

[0049] Examples 16 to 18 differ from Example 15 only in the amount of silane coupling agent added, and other factors, including the type of silane coupling agent, are the same as those in Example 15, using the same materials, manufacturing method, and conditions. The amount of silane coupling agent added is 0.5 wt% in Example 16, 1.0 wt% in Example 17, and 1.5 wt% in Example 18.

[0050] Next, the preparation of powder compacts of Comparative Examples 1 to 14 will be described. Comparative Example 1 differs from Example 1 only in that a silane coupling agent was not added. That is, the insulating coating layer of Comparative Example 1 contains only silicone resin, and does not contain a silane coupling agent. In Comparative Example 1, the same materials, manufacturing method, and conditions as Example 1 were used for the rest of the process.

[0051] Comparative Example 2 differs from Example 1 only in the type and amount of silane coupling agent; otherwise, the same materials, manufacturing method, and conditions were used as in Example 1. The silane coupling agent used in Comparative Example 2 was "A tetraethoxysilane" (product name: TES28) shown in Table 2 above. The amount of silane coupling agent added was 0.5 wt%.

[0052] Comparative Example 3 differs from Example 1 only in the type of silane coupling agent, and other factors, including the amount of silane coupling agent added, are the same as those in Example 1, using the same materials, manufacturing method, and conditions. The silane coupling agent used in Comparative Example 3 was "B Phenyltriethoxysilane" (product name: KBE-103) shown in Table 2 above.

[0053] Comparative Examples 4 to 6 differ from Comparative Example 3 only in the amount of silane coupling agent added, and other factors, including the type of silane coupling agent, are the same as those in Comparative Example 3, using the same materials, manufacturing method, and conditions. The amount of silane coupling agent added is 0.5 wt% in Comparative Example 4, 1.0 wt% in Comparative Example 5, and 1.5 wt% in Comparative Example 6.

[0054] Comparative Example 7 differs from Example 1 only in the type of silane coupling agent, and other factors, including the amount of silane coupling agent added, are the same as those in Example 1, using the same materials, manufacturing method, and conditions. The silane coupling agent used in Comparative Example 7 was "G 3-methacryloxypropyltriethoxysilane" (product name: KBE-503) shown in Table 2 above.

[0055] Comparative Examples 8 to 10 differ from Comparative Example 7 only in the amount of silane coupling agent added, and other factors, including the type of silane coupling agent, are the same as those in Comparative Example 7, using the same materials, manufacturing method, and conditions. The amount of silane coupling agent added is 0.5 wt% in Comparative Example 8, 1.0 wt% in Comparative Example 9, and 1.5 wt% in Comparative Example 10.

[0056] Comparative Example 11 differs from Example 1 only in the type of silane coupling agent, and other factors, including the amount of silane coupling agent added, are the same as those in Example 1, using the same materials, manufacturing method, and conditions. The silane coupling agent used in Comparative Example 11 was "H 1,6-bis(trimethoxysilyl)hexane" (product name: KBM-3066) shown in Table 2 above.

[0057] Comparative Examples 12 to 14 differ from Comparative Example 11 only in the amount of silane coupling agent added, and other factors, including the type of silane coupling agent, are the same as those in Comparative Example 11, using the same materials, manufacturing method, and conditions. The amount of silane coupling agent added is 0.5 wt% in Comparative Example 12, 1.0 wt% in Comparative Example 13, and 1.5 wt% in Comparative Example 14.

[0058] The rattle values ​​of the powder compacts prepared as described above in Examples 1 to 18 and Comparative Examples 1 to 14 were measured. A rattle tester (manufactured by Intesco Co., Ltd.) was used to measure the rattle values. The rattle values ​​were measured based on the Japan Powder Metallurgy Association (JPMA) standard method for measuring rattle values ​​of metal powder compacts (JPMA P11 1992).

[0059] First, the total weight of each of the five powder compacts of Examples 1 to 18 and Comparative Examples 1 to 14 was measured before being placed in the Rattler tester. The five powder compacts were then placed in a cylindrical cage lined with a 14-mesh stainless steel wire mesh and rotated 100 times at a rotation speed of 87 rpm. Finally, the total weight of the five powder compacts removed from the Rattler tester was measured. The Rattler value was calculated by subtracting the total weight measured after rotation from the total weight measured before rotation to determine the weight loss rate. That is, the Rattler value was calculated using the following formula (1): S = ((AB) / A) × 100 (1) S: Rattler value (%) A: Total weight (g) of the five green compacts before testing B: Total weight of the five green compacts after the test (g)

[0060] The calculation results are shown in Table 3 below. Figure 1 shows a graph illustrating the relationship between the Rattle value and the molecular weight of the silane coupling agent when the amount of silane coupling agent added is 0.5 wt%. Figure 2 shows a graph illustrating the relationship between the Rattle value and the molecular weight of the silane coupling agent when the amount of silane coupling agent added is 1.0 wt%.

[0061] [Table 3]

[0062] As shown in Table 3, in Examples 1 to 18 in which the molecular weight of the silane coupling agent was 244.4 or more and 260.4 or less, even the highest rattle value was less than 35%, which was lower than the values ​​of Comparative Examples 1 to 14. Therefore, it was confirmed that by setting the molecular weight of the silane coupling agent in the range of 244.4 or more and 260.4 or less, the rattle value was reduced and chipping and cracking in the powder compact could be prevented.

[0063] It was confirmed that the rattle value decreased when the amount of silane coupling agent added was 0.3 wt% or more. Furthermore, as shown in Figure 1, it was confirmed that the rattle value decreased below 30% in Examples 2 to 5, 7 to 10, 12 to 14, and 16 to 18, in which the amount of silane coupling agent added was 0.5 wt% or more.

[0064] In particular, when comparing Examples 2, 4 and 5, in which the molecular weight of the silane coupling agent is 244.4, with Comparative Examples 4, 5 and 6, in which the molecular weight of the silane coupling agent is 240.4, the rattle value of the Examples is significantly reduced to about 1 / 4 of that of the Comparative Examples at each added amount.Thus, although the molecular weight of the silane coupling agent differs by only 4, when the molecular weight of the silane coupling agent is 244.4, it was confirmed that the rattle value is dramatically reduced compared to those with molecular weights lower than 244.4.

[0065] Furthermore, as shown in Figure 2, in Examples 4, 5, 9, 10, 13, 14, 17 and 18 in which the molecular weight of the silane coupling agent was 244.4 or more and 248.4 or less and the amount of silane coupling agent added was 1.0 wt% or more, the Rattle value was confirmed to be approximately 15 or less, which is an extremely good value.

[0066] Although the rattle values ​​are slightly different between Examples 6 to 10 and Examples 11 to 14, in which the molecular weight of the silane coupling agent is the same, this is within the range of measurement error. Furthermore, the rattle value is an index relating to the chipping resistance of the molded body, and therefore does not correlate with strength. In other words, it cannot be immediately said that the rattle value decreases as the strength increases.

[0067] Next, powder compacts were further produced for Examples 19 and 20 and Comparative Example 15. Example 19 differs from Example 7 only in that the powder used was a pulverized powder produced by pulverizing Fe-Si-Al alloy powder. Other aspects, including the type and amount of silane coupling agent, were the same as those of Example 7, using the same materials, manufacturing method, and conditions.

[0068] Example 20 differs from Example 2 only in that it is a pulverized powder made by pulverizing Fe-Si-Al alloy powder. Other than that, including the type and amount of silane coupling agent, the materials, manufacturing method, and conditions are the same as those of Example 2.

[0069] Comparative Example 15 differs from Comparative Example 2 only in that it is a pulverized powder made by pulverizing Fe-Si-Al alloy powder. In all other respects, including the type and amount of silane coupling agent, the materials, manufacturing method, and conditions are the same as those of Comparative Example 2.

[0070] Five powder compacts were also produced for each of Examples 19 and 20 and Comparative Example 15, and the Rattler values ​​were calculated. The Rattler values ​​were calculated using the same equipment and under the same measurement conditions as above. The calculation results are shown in Table 4 below.

[0071] [Table 4]

[0072] As shown in Table 4, even when the Fe-Si-Al alloy powder is a pulverized powder, it was confirmed that Examples 19 and 20, in which the molecular weight of the silane coupling agent is in the range of 244.4 or more and 260.4 or less, have lower rattle values ​​than Comparative Example 15. In other words, it was confirmed that the type of soft magnetic powder is not limited to gas atomized powder, and that the effect is also produced even with pulverized powder.

[0073] However, looking at Comparative Example 15, the rattle value is 3.9%, which is a low value to begin with, and it is difficult to say that the rattle values ​​of Examples 19 and 20 are dramatically lower than those of Comparative Example 15. On the other hand, the rattle value of Comparative Example 2, which is a gas atomized powder, is a high value of 58.0%. The rattle values ​​of Examples 2 and 7 are 16.0% and 29.0%, respectively, which are less than half of that of Comparative Example 2. Therefore, it was confirmed that adding a silane coupling agent with a molecular weight of 244.4 or more and 260.4 or less to a soft magnetic powder, which is a gas atomized powder, results in a more significant effect of reducing the rattle value.

[0074] Powder magnetic cores were produced in Examples 21 to 38 and Comparative Examples 16 to 27. The types and amounts of silane coupling agents in Examples 21 to 38 and Comparative Examples 16 to 27 correspond to those in Examples 1 to 18 and Comparative Examples 1 to 12, respectively. That is, the type and amount of silane coupling agent in Example 21 was the same as that in Example 1, the type and amount of silane coupling agent in Example 22 was the same as that in Example 2, and the type and amount of silane coupling agent in Comparative Example 27 was the same as that in Comparative Example 12. The powder compacts in Examples 21 to 38 and Comparative Examples 16 to 27 were produced using the same materials, the same manufacturing method, and the same conditions as the corresponding Examples or Comparative Examples up to the point where aluminum stearate (D50=21 μm, melting point 110° C.) was added and mixed as a lubricant.

[0075] The methods for producing the powder compacts of Examples 21 to 38 and Comparative Examples 16 to 27 differ in the steps after pressure molding. After adding and mixing aluminum stearate as a lubricant, the Fe-Si-Al alloy powder was filled into a die and pressure molding was performed to produce toroidal powder compacts with an outer diameter of 16.5 mm, an inner diameter of 11.0 mm, and a height of 5.0 mm. The pressure for press molding was 12.0 ton / cm. 2 In Examples 21 to 38 and Comparative Examples 16 to 27, only one powder compact was produced.

[0076] The powder compact was then heat-treated to remove distortion caused by compaction. This heat treatment was carried out in a nitrogen atmosphere at a temperature of 700°C. The heat treatment time was 2 hours. In this manner, the powder cores of Examples 21 to 38 and Comparative Examples 16 to 27 were produced. The iron loss of each of the powder cores of Examples 21 to 38 and Comparative Examples 16 to 27 was then measured.

[0077] When measuring the iron loss, a copper wire with a diameter of 0.5 mm was wound around the powder magnetic core for 15 turns as the primary winding and for 15 turns as the secondary winding. Then, using a BH analyzer (Iwatsu Measurement Corporation: SY-8219), a magnetic measuring instrument, the iron loss Pcv (kW / m) was measured under the measurement conditions of a frequency of 100 kHz and a maximum magnetic flux density Bm of 100 mT. 3 The measurement results are shown in Table 5.

[0078] [Table 5]

[0079] As shown in Table 5, in Examples 21 to 38 in which the molecular weight of the silane coupling agent was in the range of 244.4 or more and 260.4 or less, the iron loss was 300 kW / m 3 In particular, in Examples 21 to 34, in which the molecular weight of the silane coupling agent is in the range of 244.4 or more and 248.4 or less, the iron loss is always 300 kW / m 3 The results are as follows, and it has been confirmed that iron loss is stably reduced.

[0080] Furthermore, the iron loss values ​​of Examples 25, 30, 34, and 38, which contained 1.5 wt% of silane coupling agent, were higher than those of the other Examples containing the same type of silane coupling agent. In other words, increasing the amount of silane coupling agent further could lead to a worsening of iron loss. Therefore, it is presumed that adding 1.5 wt% of silane coupling agent results in a good rattle value, preventing chipping and cracking of the powder compact and improving the magnetic properties.

[0081] (Other embodiments) Although the present specification describes an embodiment of the present invention, this embodiment is presented as an example and is not intended to limit the scope of the invention. The above-described embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. The embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

Claims

1. soft magnetic powder; an insulating coating layer that covers the soft magnetic powder; Equipped with the insulating coating layer is made only of a silicone resin and a silane coupling agent, and is configured by laminating a single layer of a mixed layer of the silane coupling agent and the silicone resin, or two layers of the silane coupling agent layer and the silicone resin layer, The molecular weight of the silane coupling agent is 244.4 or more and 260.4 or less; A powder compact characterized by:

2. The amount of the silane coupling agent added is 0.5 wt % or more relative to the soft magnetic powder; The powder compact according to claim 1, characterized in that

3. The molecular weight of the silane coupling agent is 244.4 or more and 248.4 or less, The amount of the silane coupling agent added is 1.0 wt % or more relative to the soft magnetic powder; The powder molded body according to claim 2, characterized in that

4. the soft magnetic powder is a gas atomized powder; 4. The powder molded body according to claim 1, wherein:

5. the silicone resin is a methylphenyl-based resin; 4. The powder molded body according to claim 1, wherein:

6. The upper limit of the amount of the silane coupling agent added is 1.5 wt % or less with respect to the soft magnetic powder; 4. The powder molded body according to claim 1, wherein:

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