JP2007092162A - Highly compressive iron powder, iron powder for dust core using the same and dust core - Google Patents
Highly compressive iron powder, iron powder for dust core using the same and dust core Download PDFInfo
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 204
- 239000000428 dust Substances 0.000 title claims abstract description 25
- 239000012535 impurity Substances 0.000 claims abstract description 13
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 11
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 8
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 7
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 7
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 5
- 239000002245 particle Substances 0.000 claims description 100
- 239000013078 crystal Substances 0.000 claims description 29
- 238000000465 moulding Methods 0.000 claims description 28
- 239000000843 powder Substances 0.000 claims description 27
- 238000011282 treatment Methods 0.000 claims description 23
- 238000000576 coating method Methods 0.000 claims description 16
- 239000011248 coating agent Substances 0.000 claims description 14
- 229910052742 iron Inorganic materials 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 230000005291 magnetic effect Effects 0.000 abstract description 40
- 229910052799 carbon Inorganic materials 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 31
- 235000013339 cereals Nutrition 0.000 description 15
- 229910052751 metal Inorganic materials 0.000 description 14
- 239000002184 metal Substances 0.000 description 14
- 238000004519 manufacturing process Methods 0.000 description 11
- 238000004663 powder metallurgy Methods 0.000 description 10
- 239000011347 resin Substances 0.000 description 10
- 229920005989 resin Polymers 0.000 description 10
- 239000012298 atmosphere Substances 0.000 description 9
- 230000007423 decrease Effects 0.000 description 8
- 239000000314 lubricant Substances 0.000 description 8
- 230000035699 permeability Effects 0.000 description 7
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- 239000007787 solid Substances 0.000 description 7
- 238000009692 water atomization Methods 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 230000002093 peripheral effect Effects 0.000 description 6
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 6
- 230000004907 flux Effects 0.000 description 5
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- 239000000126 substance Substances 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 229910019142 PO4 Inorganic materials 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 238000000137 annealing Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000011810 insulating material Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- 239000010452 phosphate Substances 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 239000006087 Silane Coupling Agent Substances 0.000 description 2
- ILRRQNADMUWWFW-UHFFFAOYSA-K aluminium phosphate Chemical compound O1[Al]2OP1(=O)O2 ILRRQNADMUWWFW-UHFFFAOYSA-K 0.000 description 2
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 2
- 238000000889 atomisation Methods 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000007739 conversion coating Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 2
- 238000005461 lubrication Methods 0.000 description 2
- 229910001004 magnetic alloy Inorganic materials 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
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- 239000004094 surface-active agent Substances 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 238000007088 Archimedes method Methods 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000001506 calcium phosphate Substances 0.000 description 1
- 229910000389 calcium phosphate Inorganic materials 0.000 description 1
- 235000011010 calcium phosphates Nutrition 0.000 description 1
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
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- 235000013312 flour Nutrition 0.000 description 1
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- 150000002431 hydrogen Chemical class 0.000 description 1
- 230000002706 hydrostatic effect Effects 0.000 description 1
- UCNNJGDEJXIUCC-UHFFFAOYSA-L hydroxy(oxo)iron;iron Chemical compound [Fe].O[Fe]=O.O[Fe]=O UCNNJGDEJXIUCC-UHFFFAOYSA-L 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 229910000398 iron phosphate Inorganic materials 0.000 description 1
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- -1 phosphate compound Chemical class 0.000 description 1
- 235000011007 phosphoric acid Nutrition 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 239000009719 polyimide resin Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000008707 rearrangement Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000000344 soap Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 229910052596 spinel Inorganic materials 0.000 description 1
- 239000011029 spinel Substances 0.000 description 1
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- 229920005992 thermoplastic resin Polymers 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- LRXTYHSAJDENHV-UHFFFAOYSA-H zinc phosphate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O LRXTYHSAJDENHV-UHFFFAOYSA-H 0.000 description 1
- 229910000165 zinc phosphate Inorganic materials 0.000 description 1
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Abstract
Description
本発明は、粉末冶金用鉄粉に係り、とくに高い磁気特性が要求される部品用、あるいは高密度が要求される部品用として好適な高圧縮性鉄粉、およびそれを用いた圧粉磁芯用鉄粉と圧粉磁芯に関する。 The present invention relates to iron powder for powder metallurgy, and particularly suitable for parts that require high magnetic properties or parts that require high density, and a dust core using the same. Iron powder and dust cores.
粉末冶金技術の進歩により、高寸法精度の複雑な形状の部品をニアネット形状に製造することができるようになり、粉末冶金技術を利用した製品が各種分野で利用されている。
粉末冶金技術では、金属粉末に、必要に応じて潤滑剤粉末や合金用粉末を混合したのち、金型で加圧成形して成形体として、ついで、焼結さらには熱処理を行って、所望の寸法形状、特性を有する焼結部品としている。また粉末冶金技術では、金属粉末に、樹脂等の結合剤を混合したのち、金型で加圧成形して成形体とし、部品とする場合もある。
Advances in powder metallurgy technology have made it possible to manufacture parts with high dimensional accuracy and complex shapes in a near net shape, and products using powder metallurgy technology have been used in various fields.
In powder metallurgy technology, metal powder is mixed with lubricant powder or alloy powder as required, and then pressed with a mold to form a molded body, followed by sintering and heat treatment to obtain a desired Sintered parts with dimensional shape and characteristics. In the powder metallurgy technique, a binder such as a resin is mixed with metal powder, and then pressure-molded with a mold to form a molded body, which may be a part.
このような粉末冶金技術を利用して、優れた磁気特性や、高強度を有する部品を製造する場合には、一定の成形圧力で加圧成形した際に高密度の成形体が得られるように、使用する金属粉末（鉄粉）には高圧縮性を具備することが要求されている。
このような要求に対し、例えば特許文献１には、不純物含有量が、Ｃ：0.005％以下，Si：0.010％以下，Mn：0.050％以下，Ｐ：0.010％以下，Ｓ：0.010％以下，Ｏ：0.10％以下，Ｎ：0.0020％以下で残部が実質的にFeおよび不可避的不純物からなり、粒度構成がJIS Z 8801に定める篩を用いた篩わけ重量比で、−60／＋83メッシュが４％以下，−83／＋100メッシュが4％以上10％以下，−100／＋140メッシュが10％以上25％以下，330メッシュ通過分が10％以上30％以下であり、−60／＋200メッシュの平均結晶粒径がJIS G 0052に規定されるフェライト結晶粒径測定法で6.0以下の粗大結晶粒である粉末冶金用純鉄粉が提案されている。なお、−60／＋83メッシュは、60メッシュ（呼び寸法（公称目開き）が250μｍ）の篩を通過し、かつ83メッシュ（呼び寸法が165μｍ）の篩を通過しない粒度のものを意味する。特許文献１に記載された純鉄粉では、潤滑剤としてステアリン酸亜鉛を0.75％配合し、５ｔ／cm2（490MPa）の成形圧力で金型成形したとき、7.05ｇ／cm3（7.05Mg／ｍ3）以上の圧粉密度が得られるとしている。
When manufacturing parts with excellent magnetic properties and high strength using such powder metallurgy technology, a high-density molded body can be obtained when pressure-molding with a constant molding pressure. The metal powder (iron powder) used is required to have high compressibility.
In response to such a request, for example, Patent Document 1 discloses that the impurity content is C: 0.005% or less, Si: 0.010% or less, Mn: 0.050% or less, P: 0.010% or less, S: 0.010% or less, O : 0.10% or less, N: 0.0020% or less, the balance is substantially composed of Fe and inevitable impurities, and the weight ratio of sieves using a sieve defined in JIS Z 8801 is -60 / + 83 mesh, 4% -83 / + 100 mesh is 4% or more and 10% or less, -100 / + 140 mesh is 10% or more and 25% or less, 330 mesh passage is 10% or more and 30% or less, and average crystal of -60 / + 200 mesh There has been proposed a pure iron powder for powder metallurgy, which is a coarse crystal grain having a grain size of 6.0 or less by a ferrite crystal grain size measuring method defined in JIS G 0052. In addition, -60 / + 83 mesh means the thing of the particle size which passes the sieve of 60 mesh (a nominal dimension (nominal opening) is 250 micrometers), and does not pass the sieve of 83 mesh (a nominal dimension is 165 micrometers). In the pure iron powder described in Patent Document 1, when 0.75% of zinc stearate is blended as a lubricant and molded at a molding pressure of 5 t / cm 2 (490 MPa), 7.05 g / cm 3 (7.05 Mg / It is said that a green density of m 3 ) or more can be obtained.
また、特許文献２には、鉄粉の粒度分布（粒度構成）が、JIS Z 8801に定める篩を用いた篩わけ質量％で、呼び寸法が１mmの篩を通過し、かつ呼び寸法が250μｍの篩を通過しない粒度のものが０％を超え45％以下，呼び寸法が250μｍの篩を通過し、かつ呼び寸法が180μｍの篩を通過しない粒度のものが30％以上65％以下，呼び寸法が180μｍの篩を通過し、かつ呼び寸法が150μｍの篩を通過しない粒度のものが４％以上20％以下，呼び寸法が150μｍの篩を通過する粒度のものが０％以上10％以下，呼び寸法が150μｍの篩を通過しない粒度の鉄粉のマイクロビッカース硬度の上限値が110以下である高圧縮性鉄粉が提案されている。なお、この高圧縮性鉄粉では、不純物含有量を、質量％でＣ：0.005％以下，Si：0.01％以下，Mn：0.05％以下，Ｐ：0.01％以下，Ｓ：0.01％以下，Ｏ：0.10％以下，Ｎ：0.003％以下とすることが好ましいとしている。特許文献２に記載された鉄粉によれば、鉄粉に、潤滑剤としてステアリン酸亜鉛を0.75％配合し、490MPaの成形圧力で金型成形したとき、7.20Mg／ｍ3 以上の圧粉密度が得られるとしている。
また、特許文献３には、切断面において、１個の粒子における結晶粒の数が平均10個以下である軟磁性純鉄粉あるいは軟磁性合金鉄粉が提案されている。特許文献３に記載された軟磁性純鉄粉あるいは軟磁性合金鉄粉を得るためには、非酸化性雰囲気で好ましくは900℃以上の高温に加熱することが必要とされている。このような純鉄粉あるいは合金鉄粉を使用し圧粉磁芯を製造することにより、圧粉磁芯の透磁率が向上するとしている。 Patent Document 3 proposes soft magnetic pure iron powder or soft magnetic alloy iron powder in which the average number of crystal grains in one particle is 10 or less on the cut surface. In order to obtain the soft magnetic pure iron powder or soft magnetic alloy iron powder described in Patent Document 3, it is necessary to heat to a high temperature of preferably 900 ° C. or higher in a non-oxidizing atmosphere. By manufacturing a dust core using such pure iron powder or alloy iron powder, the magnetic permeability of the dust core is improved.
また、特許文献４には、軟磁性金属の単結晶からなる金属粉末粒子を利用した軟磁性成形体の製造方法が提案されている。特許文献４に記載された技術では、多結晶からなる軟磁性の原料粉末粒子を高温、好ましくは1100〜1350℃に加熱して単結晶化する工程を採用している。このような金属粉末を使用して成形体を製造することにより、成形体の最大透磁率が向上するとしている。
しかしながら、特許文献１に記載された純鉄粉では、得られる圧粉体密度は、たかだか7.12ｇ／cm3（7.12Mg／ｍ3）程度までであり、圧縮性が不足し、磁芯等の磁性部品用として使用する場合には、所望の磁束密度や透磁率といった磁気特性が得られない場合があるという問題がある。また、特許文献２に記載された鉄粉は、鉄粉粒子の粒径が大きく、焼結した場合の強度低下が懸念され、また、鉄粉の純度が高いため精錬コストが高くなるという問題があった。
However, in the pure iron powder described in Patent Document 1, the density of the green compact obtained is up to about 7.12 g / cm 3 (7.12 Mg / m 3 ), the compressibility is insufficient, the magnetic core, etc. When used for magnetic parts, there is a problem that magnetic properties such as desired magnetic flux density and magnetic permeability may not be obtained. In addition, the iron powder described in
また、特許文献３に記載された技術では、１個の金属粉末粒子内の結晶粒の数は少ないほうが好ましいとしているが、５個以下まで低減するためには、非酸化性雰囲気中で1000℃以上の高温の加熱温度で処理を行う必要がある。また特許文献４に記載された技術では、金属粉末粒子を単結晶化するために還元性雰囲気中で1100℃以上の加熱温度で処理を行う必要がある。特許文献３および特許文献４に記載された技術ではいずれも高温に加熱できる非酸化性雰囲気の加熱炉を必要とし、製造コストが高騰するという問題があった。さらにこのような高温で加熱した金属粉末は粒子同士が結合されていると考えられ、加熱後の粒子分離作業により、粒子に過剰の応力が加えられ、粒子内に残留する応力により、十分な圧縮性が得られないことが推察された。 Further, in the technique described in Patent Document 3, it is preferable that the number of crystal grains in one metal powder particle is small, but in order to reduce the number to 5 or less, 1000 ° C. in a non-oxidizing atmosphere. It is necessary to perform the treatment at the above high heating temperature. In the technique described in Patent Document 4, it is necessary to perform treatment at a heating temperature of 1100 ° C. or higher in a reducing atmosphere in order to single-crystallize the metal powder particles. Each of the techniques described in Patent Document 3 and Patent Document 4 requires a heating furnace in a non-oxidizing atmosphere that can be heated to a high temperature, and there is a problem that the manufacturing cost increases. Furthermore, it is considered that the metal powder heated at such a high temperature is bonded to each other, and excessive stress is applied to the particles by the particle separation operation after heating, and sufficient compression is performed by the stress remaining in the particles. It was inferred that no sex could be obtained.
本発明は、このような従来技術の問題を有利に解決し、磁気特性に優れた部品や高密度焼結部品に用いて好適な、高圧縮性を有する鉄粉、およびそれを用いた圧粉磁芯用鉄粉と圧粉磁芯を提供することを目的とする。 The present invention advantageously solves such problems of the prior art and is suitable for use in parts having excellent magnetic properties and high-density sintered parts, and iron powder having high compressibility, and compacts using the same It aims at providing the iron powder for magnetic cores, and a dust core.
従来、高圧縮性鉄粉を得るためには、鉄粉を高純度化することが必須と考えられてきた。これに対し、本発明者らは、鉄粉を高純度化することなく、従来から一般的に製造されている純度で上記した課題を達成するために、鉄粉粒子の硬さに及ぼす各種要因について鋭意検討した。
その結果、従来から一般的に製造されている純度の純鉄粉であっても、鉄粉粒子内の結晶粒数を４個以内に調整し、マイクロビッカース硬さＨＶを平均で80以下の硬さに調整すること、あるいはさらに鉄粉粒子内に含まれる50ｎｍ以上、好ましくは100ｎｍ以上の大きさの、シリコンを含む介在物の個数を、シリコンを含む介在物全個数に対する個数比率で70％以上となるように調整することにより、圧縮性に富む純鉄粉となることを新たに知見した。またさらに、鉄粉の円形度を0.7以上、好ましくは0.9以上とすることにより、鉄粉の圧縮性が更に向上することを知見した。
Conventionally, in order to obtain highly compressible iron powder, it has been considered essential to refine the iron powder. On the other hand, the present inventors have achieved various factors affecting the hardness of the iron powder particles in order to achieve the above-described problems with the purity that has been generally produced without purifying the iron powder. We studied earnestly.
As a result, even for pure iron powder of a purity that has been generally manufactured conventionally, the number of crystal grains in the iron powder particles is adjusted to 4 or less, and the micro Vickers hardness HV is 80 or less on average. Or the number of inclusions containing silicon having a size of 50 nm or more, preferably 100 nm or more, contained in the iron powder particles is 70% or more in terms of the number ratio relative to the total number of inclusions containing silicon. It was newly found out that by adjusting so as to become a pure iron powder rich in compressibility. Furthermore, it has been found that the iron powder compressibility is further improved by setting the circularity of the iron powder to 0.7 or more, preferably 0.9 or more.
本発明は、上記した知見に基づき、さらに検討を加えて完成されたものである。
すなわち、本発明の要旨はつぎのとおりである。
（１）不純物として、質量％で、Ｃ：0.005％以下，Si：0.01％超0.03％以下，Mn：0.03％以上0.07％以下，Ｐ：0.01％以下，Ｓ：0.01％以下，Ｏ：0.10％以下，Ｎ： 0.001％以下を含む鉄粉であって、該鉄粉の粒子が、平均で４個以下の結晶粒数と、マイクロビッカース硬さＨＶで平均で80以下、好ましくは75以下の硬さを有することを特徴とする高圧縮性鉄粉。
The present invention has been completed based on the above findings and further studies.
That is, the gist of the present invention is as follows.
(1) As impurities, C: 0.005% or less, Si: more than 0.01%, 0.03% or less, Mn: 0.03% or more, 0.07% or less, P: 0.01% or less, S: 0.01% or less, O: 0.10% Hereinafter, iron powder containing N: 0.001% or less, and the iron powder particles have an average number of crystal grains of 4 or less and a micro Vickers hardness HV of 80 or less, preferably 75 or less on average. A highly compressible iron powder characterized by having a thickness.
（２）（１）において、前記鉄粉の粒子が、大きさ：50ｎｍ以上のSiを含む介在物を、Siを含む介在物全個数に対する個数比率で70％以上含むことを特徴とする高圧縮性鉄粉。
（３）（１）又は（２）のいずれかにおいて、前記鉄粉の円形度が0.7以上、好ましくは0.9以上であることを特徴とする高圧縮性鉄粉。
（４）（１）乃至（３）のいずれかにおいて、前記鉄粉が、水アトマイズ製であることを特徴とする高圧縮性鉄粉。
(2) In (1), the iron powder particles contain 70% or more of inclusions containing Si having a size of 50 nm or more in terms of the number ratio relative to the total number of inclusions containing Si. Iron powder.
(3) The highly compressible iron powder according to any one of (1) and (2), wherein the circularity of the iron powder is 0.7 or more, preferably 0.9 or more.
(4) The highly compressible iron powder according to any one of (1) to (3), wherein the iron powder is made of water atomized.
（５）（１）乃至（４）のいずれかに記載の高圧縮性鉄粉に、絶縁被覆処理を施してなる圧粉磁芯用鉄粉。
（６）（５）に記載の圧粉磁芯用鉄粉を加圧成形してなる圧粉磁芯。
(5) A powder magnetic core iron powder obtained by subjecting the highly compressible iron powder according to any one of (1) to (4) to an insulating coating treatment.
(6) A dust core obtained by press-molding the iron powder for dust core according to (5).
本発明によれば、高密度の成形体を安価にしかも安定して製造することが可能となり、高強度の焼結部品、あるいは優れた磁気特性を有する圧粉磁芯等の部品を、低コストで製造できるという産業上格段の効果を奏する。また、本発明の高圧縮性鉄粉は、一般的な粉末冶金用純鉄粉に含まれる不純物含有量と同等の純度の鉄粉であり、高純度化のための特別な精錬を必要とすることがなく、製造コストの高騰を懸念する必要がないという効果もある。 According to the present invention, it becomes possible to manufacture a high-density molded body at a low cost and stably, and a high-strength sintered part or a part such as a dust core having excellent magnetic properties can be manufactured at low cost. There is a remarkable industrial effect that it can be manufactured with. Moreover, the highly compressible iron powder of the present invention is an iron powder having a purity equivalent to the impurity content contained in a general pure iron powder for powder metallurgy, and requires special refining for high purity. There is also an effect that there is no need to worry about a rise in manufacturing costs.
本発明の高圧縮性鉄粉は、鉄粉の粒子が、平均で４個以下の結晶粒数と、マイクロビッカース硬さＨＶで平均で80以下、好ましくは75以下の硬さを有する鉄粉である。なお、本発明でいう「高圧縮性」とは、鉄粉1000ｇに、潤滑剤としてステアリン酸亜鉛を0.75質量％配合しＶ型ミキサーで15min間混合したのち、686MPaの成形圧力で、11mmφ×10mmの円筒形状に常温で１回で成形し、7.24Mg／ｍ3以上の成形密度の成形体が得られる場合をいうものとする。 The highly compressible iron powder of the present invention is an iron powder having iron powder particles having an average number of crystal grains of 4 or less and a micro Vickers hardness HV of 80 or less, preferably 75 or less on average. is there. The term “high compressibility” as used in the present invention means that 0.75 mass% of zinc stearate as a lubricant is mixed with 1000 g of iron powder and mixed for 15 minutes with a V-type mixer, then at a molding pressure of 686 MPa, 11 mmφ × 10 mm When a molded body having a molding density of 7.24 Mg / m 3 or more is obtained by molding into a cylindrical shape at a normal temperature once.
なお、本発明の鉄粉は、JIS Z 8801に定める篩を用いた篩わけ質量％で、呼び寸法（公称目開き）が180μｍの篩を通過しない粒度のものが０％を超え５％以下，呼び寸法が180μｍの篩を通過し、かつ呼び寸法が150μｍの篩を通過しない粒度のものが３％以上10％以下，呼び寸法が150μｍの篩を通過し、かつ呼び寸法が106μｍの篩を通過しない粒度のものが10％以上25％以下，呼び寸法が106μｍの篩を通過し、かつ呼び寸法が75μｍの篩を通過しない粒度のものが20％以上30％以下，呼び寸法が75μｍの篩を通過し、かつ呼び寸法が63μｍの篩を通過しない粒度のものが10％以上20％以下，呼び寸法が63μｍの篩を通過し、かつ呼び寸法が45μｍの篩を通過しない粒度のものが15％以上30％以下，呼び寸法が45μｍの篩を通過する粒度のものが15％以上30％以下、である粒度構成を有するものとする。この粒度構成は、表１に示す市販の粉末冶金用アトマイズ鉄粉の粒度構成と同等である。 In addition, the iron powder of the present invention is a mass% using a sieve defined in JIS Z 8801, and a particle size that does not pass through a sieve having a nominal size (nominal opening) of 180 μm is more than 0% and not more than 5%. A particle size that passes through a sieve with a nominal size of 180 μm and that does not pass through a sieve with a nominal size of 150 μm passes through a sieve with a nominal size of 3 to 10%, passes through a sieve with a nominal size of 150 μm, and passes through a sieve with a nominal size of 106 μm A particle size of 10% or more and 25% or less, which passes through a sieve with a nominal size of 106 μm, and a particle size which does not pass through a sieve with a nominal size of 75 μm, has a screen size of 20% or more and 30% or less, and a nominal size of 75 μm. 10% or more and 20% or less of a particle size that passes through a sieve with a nominal size of 63 μm, 15% of a particle size that passes through a sieve with a nominal size of 63 μm and does not pass through a sieve with a nominal size of 45 μm 30% or less, 15% or more and 30% or less of the particle size passing through a sieve with a nominal size of 45μm And those having a particle size configuration. This particle size configuration is equivalent to the particle size configuration of commercially available atomized iron powder for powder metallurgy shown in Table 1.
本発明では、鉄粉粒子内の結晶数は、平均で４個以下に限定する。鉄粉粒子内の結晶数を４個以下とすることにより、鉄粉の圧縮性が向上する。鉄粉粒子内の結晶数が４個を超えて多くなると、鉄粉の圧縮性が低下する。鉄粉粒子内の結晶数の増加は、結晶粒界の増加を意味する。結晶粒界は、転位の集積場で一種の格子欠陥であり、結晶粒界の増加は、鉄粉粒子の硬さを増加させ、鉄粉の圧縮性を低下させることに繋がる。このため、本発明では、鉄粉粒子の結晶粒数を平均で４個以下に限定した。 In the present invention, the number of crystals in the iron powder particles is limited to 4 or less on average. By setting the number of crystals in the iron powder particles to 4 or less, the compressibility of the iron powder is improved. When the number of crystals in the iron powder particles exceeds 4 and the compressibility of the iron powder decreases. An increase in the number of crystals in the iron powder particles means an increase in grain boundaries. The crystal grain boundary is a kind of lattice defect in the dislocation accumulation field, and the increase of the crystal grain boundary increases the hardness of the iron powder particle and leads to a decrease in the compressibility of the iron powder. For this reason, in the present invention, the number of crystal grains of the iron powder particles is limited to 4 or less on average.
なお、本発明でいう「鉄粉粒子の結晶粒数」は、つぎのように測定し算出した値である。
まず、被測定物である鉄粉を、熱可塑性樹脂粉に混合し混合粉としたのち、該混合粉を適当な型に装入後、加熱し樹脂を溶融させたのち冷却固化させ、鉄粉含有樹脂固形物とする。ついで、該鉄粉含有樹脂固形物を適当な断面で切断し、該切断した面を研磨し腐蝕したのち、光学顕微鏡または走査型電子顕微鏡（400倍）を用いて鉄粉粒子の断面組織を観察及び／又は撮像し、鉄粉粒子内の結晶粒数を測定する。なお、観察及び／又は撮像する鉄粉粒子の数は30個とし、対象とした鉄粉粒子の結晶粒数を平均し、平均値をその鉄粉粒子の平均結晶粒数とする。結晶粒数の測定は撮像した組織写真を画像解析装置を用いて行うことが好ましい。
In the present invention, “the number of crystal grains of iron powder particles” is a value measured and calculated as follows.
First, iron powder, which is the object to be measured, is mixed with a thermoplastic resin powder to form a mixed powder, and then the mixed powder is charged into an appropriate mold, heated to melt the resin, and then solidified by cooling. Let it be a contained resin solid. Next, the iron powder-containing resin solid material is cut in an appropriate cross section, the cut surface is polished and corroded, and then the cross-sectional structure of the iron powder particles is observed using an optical microscope or a scanning electron microscope (400 times). And / or image and measure the number of crystals in the iron powder particles. The number of iron powder particles to be observed and / or imaged is 30, and the number of target iron powder particles is averaged, and the average value is the average number of iron powder particles. The measurement of the number of crystal grains is preferably performed using a captured tissue photograph using an image analyzer.
鉄粉粒子内の結晶粒を模式的に図１に示す。図１からわかるように、鉄粉粒子には、粒界のみに囲まれた結晶粒１と、粒界と鉄粉粒子表面とで囲まれた結晶粒２の２種類が含まれている。
また、本発明の高圧縮性鉄粉は、不純物として、質量％で、Ｃ：0.005％以下，Si：0.01％超0.03％以下，Mn：0.03％以上0.07％以下，Ｐ：0.01％以下，Ｓ：0.01％以下，Ｏ：0.10％以下，Ｎ：0.001％以下に制限して含み、残部Feおよび不可避的不純物である組成を有する鉄粉である。
The crystal grains in the iron powder particles are schematically shown in FIG. As can be seen from FIG. 1, the iron powder particles include two types of crystal grains 1 surrounded only by the grain boundaries and
Further, the highly compressible iron powder of the present invention has impurities as mass%, C: 0.005% or less, Si: more than 0.01%, 0.03% or less, Mn: 0.03% or more, 0.07% or less, P: 0.01% or less, S : 0.01% or less, O: 0.10% or less, N: An iron powder having a composition that is limited to 0.001% or less, the balance being Fe and inevitable impurities.
Ｃが、0.005質量％を超えて多量に含有されると、鉄粉硬さが増加し鉄粉の圧縮性が低下する。このため、Ｃは0.005質量％以下に限定した。
また、Siが、0.01質量％以下では、耐火物の溶損やアトマイズ時のノズル詰まり等を発生しやすく、精錬コストが高騰する要因となる。一方、0.03質量％を超える含有は、鉄粉硬さが増加し鉄粉の圧縮性を低下させる。このため、Siは0.01質量％超0.03質量％以下に限定した。
When C contains more than 0.005 mass%, iron powder hardness will increase and the compressibility of iron powder will fall. For this reason, C was limited to 0.005 mass% or less.
On the other hand, when the Si content is 0.01% by mass or less, refractory melts and nozzle clogging during atomization is likely to occur, which increases the refining cost. On the other hand, the content exceeding 0.03% by mass increases the hardness of the iron powder and decreases the compressibility of the iron powder. For this reason, Si was limited to more than 0.01 mass% and 0.03 mass% or less.
また、Mnが、0.03質量％未満では、耐火物の溶損やアトマイズ時のノズル詰まり等を発生しやすく、精錬コストが高騰する要因となる。一方、0.07質量％を超える含有は、鉄粉硬さが増加し鉄粉の圧縮性を低下させる。このため、Mnは0.03質量％以上0.07質量％以下に限定した。
また、Ｐが、0.01質量％を超えて多量に含有されると、鉄粉硬さが増加し鉄粉の圧縮性が低下する。このため、Ｐは0.01質量％以下に限定した。
On the other hand, if Mn is less than 0.03% by mass, refractory melts and nozzle clogging during atomization are likely to occur, which increases the refining cost. On the other hand, the content exceeding 0.07% by mass increases the hardness of the iron powder and decreases the compressibility of the iron powder. For this reason, Mn was limited to 0.03 mass% or more and 0.07 mass% or less.
Moreover, when P contains more than 0.01 mass%, iron powder hardness will increase and the compressibility of iron powder will fall. For this reason, P was limited to 0.01 mass% or less.
また、Ｓが、0.01質量％を超えて多量に含有されると、鉄粉硬さが増加し鉄粉の圧縮性が低下する。このため、Ｓは0.01質量％以下に限定した。
また、Ｏが、0.01質量％を超えて含有されると、鉄粉硬さが増加し鉄粉の圧縮性が低下する。このため、Ｏは0.10質量％以下に限定した。
また、Ｎが、0.001質量％を超えて含有されると、鉄粉硬さが増加し鉄粉の圧縮性が低下する。このため、Ｎは0.001質量％以下に限定した。
Moreover, when S contains more than 0.01 mass% and a large amount is contained, iron powder hardness will increase and the compressibility of iron powder will fall. For this reason, S was limited to 0.01 mass% or less.
Moreover, when O is contained exceeding 0.01 mass%, iron powder hardness will increase and the compressibility of iron powder will fall. For this reason, O was limited to 0.10 mass% or less.
Moreover, when N contains exceeding 0.001 mass%, iron powder hardness will increase and the compressibility of iron powder will fall. For this reason, N was limited to 0.001 mass% or less.
なお、上記した不純物量の範囲は、一般的な粉末冶金用純鉄粉に含まれる不純物含有量と同等の範囲である。
本発明鉄粉の粒子は、マイクロビッカース硬さＨＶで平均で80以下の硬さを有する。鉄粉の粒子の硬さが、マイクロビッカース硬さＨＶで80を超えると、鉄粉の圧縮性が低下し、潤滑剤としてステアリン酸亜鉛を0.75質量％配合し、686MPaの成形圧力で、常温で１回の成形後に、7.24Mg／ｍ3以上の圧紛密度を有する成形体を得ることができなくなる。このため、焼結体とした場合の強度が低下し、また圧粉磁芯とした場合の磁気特性が低下する。なお、好ましくはマイクロビッカース硬さＨＶで75以下である。
In addition, the range of the amount of impurities described above is a range equivalent to the content of impurities contained in general pure iron powder for powder metallurgy.
The iron powder particles of the present invention have a micro Vickers hardness HV and an average hardness of 80 or less. If the hardness of the iron powder particles exceeds 80 in terms of micro Vickers hardness HV, the compressibility of the iron powder decreases, and 0.75 mass% of zinc stearate is blended as a lubricant, at a molding pressure of 686 MPa at room temperature. After one molding, a molded body having a compact density of 7.24 Mg / m 3 or more cannot be obtained. For this reason, the intensity | strength at the time of setting it as a sintered compact falls, and the magnetic characteristic at the time of setting it as a dust core is reduced. The micro Vickers hardness HV is preferably 75 or less.
なお、鉄粉粒子の硬さは、「鉄粉粒子の結晶粒数」測定と同様に、鉄粉含有樹脂固形物としたのち、鉄粉含有樹脂固形物を適当な断面で切断し、該切断した面を研磨して、粒子断面についてマイクロビッカース硬度計（荷重25gf（0.245Ｎ））を用いて測定した。各粒子について1点測定し、測定粒子数は10個以上とし、各粒子の測定値の平均値をその鉄粉粒子の硬さとして用いた。 In addition, the hardness of the iron powder particles is the same as the measurement of “the number of crystal grains of iron powder particles”, and after the iron powder-containing resin solids are cut, the iron powder-containing resin solids are cut in an appropriate cross section. The polished surface was polished, and the particle cross section was measured using a micro Vickers hardness meter (load 25 gf (0.245 N)). One point was measured for each particle, the number of measured particles was 10 or more, and the average value of the measured values of each particle was used as the hardness of the iron powder particles.
本発明鉄粉では、大きさ：50ｎｍ以上のSiを含む介在物を、Siを含む介在物全個数に対する個数比率で70％以上に調整することが好ましい。鉄粉粒子の磁壁の厚さは40ｎｍ程度（近角聡信：強磁性体の物理（下）−磁気特性と応用−、第174頁、裳華房、1987参照）であると考えられ、Siを含む介在物の大きさが50ｎｍ未満では、磁界を印可した場合に鉄粉粒子内の磁壁の移動が阻害されると考えられる。このため、本発明では、鉄粉粒子中に含まれるSiを含む介在物のうち、磁気特性への影響の少ない大きさ：50ｎｍ以上のものを、Siを含む介在物全個数に対する個数比率で70％以上と多数、存在させるように調整することが好ましい。これにより、鉄粉の保磁力の増加が少なく、圧粉磁芯とした場合にも、圧粉磁芯の保磁力、透磁率、鉄損等の磁気特性の低下が少なくなる。鉄粉粒子中に、大きさ：50ｎｍ未満のSiを含む介在物が30％を超えて多く存在すると、磁気特性への影響が大きくなる。なお、Siを含む介在物の大きさは100ｎｍ以上とすることがより好ましい。 In the iron powder of the present invention, inclusions containing Si having a size of 50 nm or more are preferably adjusted to 70% or more in terms of the number ratio with respect to the total number of inclusions containing Si. The thickness of the magnetic wall of the iron powder particles is considered to be about 40 nm (Nakaku Tsujinobu: Physics of Ferromagnetic Material (below)-Magnetic Properties and Applications-, see page 174, Jinhuabo, 1987) and contains Si. If the size of the inclusion is less than 50 nm, it is considered that the movement of the domain wall in the iron powder particles is inhibited when a magnetic field is applied. For this reason, in the present invention, among inclusions containing Si contained in the iron powder particles, a size having a small influence on the magnetic properties: those having a size of 50 nm or more are 70 in terms of the number ratio relative to the total number of inclusions containing Si. It is preferable to adjust so as to be present in a large number of at least%. As a result, there is little increase in the coercive force of the iron powder, and even when a dust core is used, the decrease in magnetic properties such as the coercive force, magnetic permeability, and iron loss of the dust core is reduced. If there are more than 30% of inclusions containing Si with a size of less than 50 nm in the iron powder particles, the influence on the magnetic properties will increase. Note that the size of inclusions containing Si is more preferably 100 nm or more.
本発明における、Siを含む介在物の大きさの測定方法は次の通りとする。鉄粉含有樹脂固形物を任意の断面で切断し、切断面を研磨、腐蝕したのち、ＥＤＸ（Energy Dispersive Ｘ-ray fluorescence spectroscopy）により鉄粉粒子中の介在物に含まれる元素を同定し、Siを含む介在物についてその最大径を測定し、介在物の大きさとする。測定するSiを含む介在物の数は20個とした。 The method for measuring the size of inclusions containing Si in the present invention is as follows. After cutting the iron powder-containing resin solids at an arbitrary cross section, polishing and corroding the cut surface, the elements contained in the inclusions in the iron powder particles are identified by EDX (Energy Dispersive X-ray fluorescence spectroscopy). Measure the maximum diameter of inclusions containing and determine the size of the inclusions. The number of inclusions containing Si to be measured was 20.
なお、本発明鉄粉は、必要に応じ、Ni，Cu，Mo等の合金元素を鉄粉表面に部分合金化しても、また、Ni，Cu，Mo等の合金元素粉を結合材を介して鉄粉表面に付着させてもなんら問題はない。
また、本発明鉄粉では、鉄粉の円形度を0.7以上とすることが好ましい。鉄粉の円形度を0.7以上と、鉄粉粒子の形状を球形に近づけることにより、粒子間の接触点が少なく相互の接触抵抗が小さくなり、成形加圧時に金型内に充填された鉄粉粒子が移動しやすくなり、塑性変形が起こる前段階の粒子再配列が促進され、成形加圧初期での緻密化が進行するため、鉄粉の圧縮性が向上する。なお、好ましくは鉄粉の円形度は0.9以上である。
In addition, the iron powder of the present invention can be obtained by partially alloying an alloy element such as Ni, Cu, Mo or the like on the surface of the iron powder as necessary, or by passing alloy element powder such as Ni, Cu, Mo, etc. through a binder. There is no problem even if it adheres to the iron powder surface.
Moreover, in this invention iron powder, it is preferable that the circularity degree of iron powder shall be 0.7 or more. By making the iron powder circularity 0.7 or more and making the shape of the iron powder particles closer to a sphere, the number of contact points between the particles is reduced and the mutual contact resistance is reduced, and the iron powder filled in the mold during molding pressurization Particles are easily moved, particle rearrangement in the previous stage where plastic deformation occurs is promoted, and densification at the initial stage of molding pressurization proceeds, so that the iron powder compressibility is improved. The circularity of the iron powder is preferably 0.9 or more.
なお、このような形状を有する鉄粉は、低圧の水アトマイズやガスアトマイズで製造することができる。すなわちアトマイズの水圧や冷却速度を調節することにより、鉄粉の円形度を制御できる。また、このような形状の鉄粉は、粉砕法や酸化物還元法、あるいは通常の高圧の水アトマイズで得られた不定形の鉄粉末を機械的に叩き、鉄粉粒子表面の凹凸を無くす方法でも製造できる。ただし、このような方法で製造された鉄粉は、鉄粉の粒子表面が加工硬化しているため、歪取り焼鈍を施すことが必要となる。 In addition, the iron powder which has such a shape can be manufactured by low-pressure water atomization or gas atomization. That is, the circularity of the iron powder can be controlled by adjusting the atomizing water pressure and the cooling rate. In addition, iron powder of such shape is a method of mechanically hitting irregular shaped iron powder obtained by pulverization method, oxide reduction method, or normal high-pressure water atomization to eliminate irregularities on the surface of iron powder particles But it can be manufactured. However, the iron powder manufactured by such a method needs to be subjected to strain relief annealing because the surface of the iron powder particles is work-hardened.
なお、本発明でいう鉄粉の「円形度」は、次式
円形度＝（相当円の外周長さ）／（粒子の実外周長さ）
で定義される値をいうものとする。鉄粉の円形度はつぎのようにして算出する。
まず、対象とする鉄粉の粉末粒子を樹脂に埋込して、その断面を研磨したのち、走査型電子顕微鏡を用いて各粒子の断面像を撮影する。得られた断面像から、各粒子の実外周長さと投影面積を測定する。つぎに、測定された各粒子の投影面積から、該投影面積に相当する円（相当円）の直径を算出する。そして、得られた直径を用いて計算で、該粒子の相当円の外周長さを算出する。得られた各粒子の相当円の外周長さおよび実外周長さから、上記した式を用いて円形度を算出する。なお、測定する粒子数は10個以上とし、それら粒子の円形度の平均値を鉄粉の円形度として用いるものとする。
The “circularity” of the iron powder in the present invention is the following formula: circularity = (peripheral length of equivalent circle) / (actual outer peripheral length of particle)
Means the value defined in. The circularity of the iron powder is calculated as follows.
First, powder particles of target iron powder are embedded in a resin, the cross section is polished, and a cross-sectional image of each particle is photographed using a scanning electron microscope. From the obtained cross-sectional image, the actual outer peripheral length and projected area of each particle are measured. Next, the diameter of a circle (equivalent circle) corresponding to the projected area is calculated from the measured projected area of each particle. Then, the outer peripheral length of the equivalent circle of the particle is calculated by using the obtained diameter. From the outer peripheral length and the actual outer peripheral length of the equivalent circle of each particle obtained, the circularity is calculated using the above-described equation. The number of particles to be measured is 10 or more, and the average value of the circularity of these particles is used as the circularity of the iron powder.
つぎに、本発明鉄粉の好ましい製造方法について説明する。
本発明鉄粉の製造に際しては、還元法、アトマイズ法等、通常公知の鉄粉製造法がいずれも適用でき、とくに限定する必要はないが、圧縮性の観点から、なかでも溶湯を水アトマイズして鉄粉とする水アトマイズ法を適用することが好ましい。以下、水アトマイズ法を適用する場合を例に、好ましい製造方法を説明するが、これに限定されないことは言うまでもない。
Below, the preferable manufacturing method of this invention iron powder is demonstrated.
In producing the iron powder of the present invention, any of the commonly known iron powder production methods such as a reduction method and an atomizing method can be applied, and there is no particular limitation. However, from the viewpoint of compressibility, the molten metal is water-atomized. It is preferable to apply a water atomizing method to obtain iron powder. Hereinafter, although a preferable manufacturing method will be described by taking the case of applying the water atomizing method as an example, it goes without saying that the present invention is not limited thereto.
通常の純鉄組成の溶湯を、水アトマイズ法で噴霧、急冷・凝固させるとともに高圧水で解砕して、水アトマイズ製鉄粉（生粉）とする。ついで、この生粉に、脱水・乾燥処理、さらに還元処理を施して、粒子表面の酸化皮膜を除去した製品（鉄粉）とする。
本発明では、還元処理は、水素を含む還元性雰囲気中での高負荷処理とすることが好ましく、例えば、水素を含む還元性雰囲気中で700℃以上1000℃未満、好ましくは800℃以上1000℃未満の温度で、保持時間を１〜７ｈ、好ましくは３〜５ｈとする熱処理を１段または複数段施すことが好ましい。なお、雰囲気中の露点は、生粉中のＣ量に応じて選択すれば良く、とくに限定する必要はない。なお、還元処理後、解砕しさらに700〜850℃の温度で焼鈍し、鉄粉中の歪取りを行っても何ら問題はない。また、適宜、解砕、分級等の処理を含んでよいことはいうまでもない。
A molten metal having a normal pure iron composition is sprayed, rapidly cooled and solidified by a water atomizing method, and crushed with high-pressure water to obtain a water atomized iron powder (raw powder). Next, the raw powder is subjected to dehydration / drying treatment and reduction treatment to obtain a product (iron powder) from which the oxide film on the particle surface has been removed.
In the present invention, the reduction treatment is preferably a high load treatment in a reducing atmosphere containing hydrogen, for example, 700 ° C. or more and less than 1000 ° C., preferably 800 ° C. or more and 1000 ° C. in a reducing atmosphere containing hydrogen. It is preferable to perform one or more heat treatments at a temperature lower than the above and a holding time of 1 to 7 hours, preferably 3 to 5 hours. Note that the dew point in the atmosphere may be selected according to the amount of C in the raw flour, and is not particularly limited. After the reduction treatment, there is no problem even if the powder is crushed and further annealed at a temperature of 700 to 850 ° C. to remove the strain in the iron powder. Moreover, it cannot be overemphasized that processes, such as crushing and classification, may be included suitably.
このような高負荷処理を行うことにより、鉄粉の粒子中の結晶粒数を４個以下に低減できるとともに、Siを拡散させながら結晶粒界を介し鉄粉粒子外に排出し、鉄粉粒子内部のSi量を低減し、Siを含有する介在物量を少なくするとともに、その大きさを大きくすることができる。上記した還元処理を施すことにより、50ｎｍ以上の大きさのSiを含む介在物を全Siを含む介在物個数の70％以上に調整することができる。 By performing such a high load treatment, the number of crystal grains in the iron powder particles can be reduced to 4 or less, and the iron powder particles are discharged out of the iron powder particles through the grain boundaries while diffusing Si. The amount of Si inside can be reduced, the amount of inclusions containing Si can be reduced, and the size can be increased. By performing the reduction treatment described above, inclusions containing Si having a size of 50 nm or more can be adjusted to 70% or more of the number of inclusions containing all Si.
また、上記した本発明鉄粉を、圧粉磁芯のような磁性部品に適用する際には、鉄粉に絶縁被覆処理を施し、鉄粉粒子表面を層状に覆う皮膜構造の絶縁層を形成することが好ましい。絶縁被覆用の材料は、鉄粉を加圧成形し所望の形状に成形された後でも要求される絶縁性を保持できるものであればよく、とくに限定されない。このような材料としては、Al，Si，Mg，Ca，Mn，Zn，Ni，Fe，Ti，Ｖ，Bi，B，Mo，Ｗ，Na，Ｋ等の酸化物が例示できる。また、スピネル型フェライトのような磁性酸化物、水ガラスに代表される非晶質材を使用することもできる。また、絶縁被覆用材料として、リン酸塩化成処理皮膜やクロム酸塩化成処理皮膜なども挙げられる。リン酸塩化成処理皮膜にはホウ酸やMgを含むこともできる。 In addition, when applying the iron powder of the present invention described above to magnetic parts such as a dust core, an insulating coating treatment is applied to the iron powder to form an insulating layer having a coating structure that covers the surface of the iron powder particles in layers. It is preferable to do. The insulating coating material is not particularly limited as long as it can maintain the required insulating properties even after the iron powder is pressed and formed into a desired shape. Examples of such materials include oxides such as Al, Si, Mg, Ca, Mn, Zn, Ni, Fe, Ti, V, Bi, B, Mo, W, Na, and K. Further, a magnetic oxide such as spinel type ferrite or an amorphous material typified by water glass can also be used. Examples of the insulating coating material include a phosphate chemical conversion coating and a chromate chemical conversion coating. The phosphate chemical conversion film can also contain boric acid and Mg.
また、絶縁材料としては、リン酸アルミニウム，リン酸亜鉛，リン酸カルシウムおよびリン酸鉄等のリン酸化合物を用いることもできる。また、エポキシ樹脂，フェノール樹脂，シリコン樹脂，ポリイミド樹脂等の有機樹脂を用いてもよい。また、特開2003−303711 号公報に開示された材料を絶縁被覆用材料に用いても何ら問題はない。
なお、絶縁材料の鉄粉粒子表面への付着力を高めるため、あるいは絶縁層の均一性を高める目的で、界面活性剤やシランカップリング剤を添加してもよい。界面活性剤やシランカップリング剤の添加量は、絶縁層全量に対し0.001〜１質量％の範囲とすることが好ましい。
As the insulating material, a phosphate compound such as aluminum phosphate, zinc phosphate, calcium phosphate, and iron phosphate can be used. In addition, an organic resin such as an epoxy resin, a phenol resin, a silicon resin, or a polyimide resin may be used. Further, there is no problem even if the material disclosed in Japanese Patent Application Laid-Open No. 2003-303711 is used for the insulating coating material.
Note that a surfactant or a silane coupling agent may be added in order to increase the adhesion of the insulating material to the surface of the iron powder particles or to increase the uniformity of the insulating layer. The addition amount of the surfactant and the silane coupling agent is preferably in the range of 0.001 to 1% by mass with respect to the total amount of the insulating layer.
形成する絶縁層の厚さは、10〜10000ｎｍ程度とすることが好ましい。10ｎｍ未満では、絶縁効果が十分でなく、10000ｎｍを超えると磁性部品の密度が低下し、高い磁束密度が得られなくなる。
鉄粉粒子表面に絶縁層を形成する方法は、従来から公知の皮膜形成方法（コーティング方法）がいずれも好適に適用できる。使用できるコーティング方法としては、流動層法、浸漬法、噴霧法などが例示できる。なお、いずれの方法においても、絶縁材料を溶解又は分散させる溶媒を乾燥する工程が、被覆工程の後又は被覆工程と同時に必要となる。また、絶縁層が鉄粉粒子に密着し、加圧成形時に剥離することを防止するために、絶縁層と鉄粉粒子表面との間に反応層を形成してもよい。反応層の形成は、化成処理を施すことによるのが好ましい。
The thickness of the insulating layer to be formed is preferably about 10 to 10,000 nm. If the thickness is less than 10 nm, the insulating effect is not sufficient, and if it exceeds 10000 nm, the density of the magnetic component decreases, and a high magnetic flux density cannot be obtained.
Any conventionally known film forming method (coating method) can be suitably applied as the method for forming the insulating layer on the surface of the iron powder particles. Examples of the coating method that can be used include a fluidized bed method, a dipping method, and a spray method. In any method, the step of drying the solvent for dissolving or dispersing the insulating material is necessary after the coating step or simultaneously with the coating step. Further, a reaction layer may be formed between the insulating layer and the surface of the iron powder particles in order to prevent the insulating layer from being in close contact with the iron powder particles and peeling off during pressure molding. Formation of the reaction layer is preferably performed by chemical conversion treatment.
上記したような絶縁被覆処理を施し、鉄粉粒子表面に絶縁層を形成した鉄粉（絶縁被覆鉄粉）を加圧成形して、圧粉磁芯とすることができる。なお、加圧成形に先立ち、鉄粉には必要に応じ金属石鹸、アミド系ワックス等の潤滑剤を配合することもできる。潤滑剤の配合量は、鉄粉100質量部に対し0.5質量部以下とすることが好ましい。潤滑剤の配合量が多くなると、圧粉磁芯の密度が低下するためである。 The above-mentioned insulating coating treatment is performed, and iron powder (insulating coated iron powder) having an insulating layer formed on the surface of the iron powder particles can be pressure-molded to obtain a dust core. Prior to pressure molding, the iron powder can be blended with a lubricant such as metal soap or amide wax as required. The blending amount of the lubricant is preferably 0.5 parts by mass or less with respect to 100 parts by mass of the iron powder. This is because as the blending amount of the lubricant increases, the density of the dust core decreases.
圧粉磁芯は、必要に応じて歪取りの目的で焼鈍を施すこともできる。この場合、絶縁層の耐熱性に応じて、200〜800 ℃の範囲内で焼鈍温度を決定することが好ましい。
また、加圧成形する方法は、従来公知の方法がいずれも適用できる。例えば、一軸プレスを用いて常温で加圧成形する金型成形工法、あるいは温間で加圧成形する温間成形工法、金型を潤滑して加圧成形する金型潤滑工法、それを温間で行う温間金型潤滑工法、あるいは高圧で成形する高圧成形工法、静水圧プレス法などである。
The dust core can be annealed for the purpose of removing strain as necessary. In this case, it is preferable to determine the annealing temperature within a range of 200 to 800 ° C. according to the heat resistance of the insulating layer.
In addition, any conventionally known method can be applied to the pressure forming method. For example, a mold forming method in which a uniaxial press is used for pressure molding at room temperature, a warm molding method in which pressure molding is performed warm, a mold lubrication method in which a mold is lubricated and pressure molded, These include a warm mold lubrication method performed at 1, a high pressure molding method for forming at high pressure, and a hydrostatic pressure pressing method.
（実施例１）
電気炉で溶製された溶湯（鉄）を、水アトマイズ処理して、アトマイズ生粉とした。溶湯の精錬は特別な処理を施すことなく、通常とした。なお、水アトマイズ処理は噴霧圧力等を調整して実施した。得られた生粉に脱水・乾燥を施し、さらに還元処理、および解砕を行って、水アトマイズ純鉄粉とした。還元処理条件は、還元性雰囲気（水素濃度：100％，露点10〜40℃）中で、温度：800〜990℃，保持時間：３〜５ｈの範囲内で変化させた。さらにドライ水素雰囲気中で830℃で２ｈ保持し、歪取り焼鈍を行った。
Example 1
The molten metal (iron) melted in an electric furnace was treated with water atomization to obtain atomized raw powder. The refining of the molten metal was normal without any special treatment. The water atomization treatment was performed by adjusting the spray pressure and the like. The obtained raw powder was dehydrated and dried, further subjected to reduction treatment and pulverization to obtain water atomized pure iron powder. The reducing treatment conditions were changed in a reducing atmosphere (hydrogen concentration: 100%, dew point: 10 to 40 ° C.) within a range of temperature: 800 to 990 ° C. and holding time: 3 to 5 h. Further, it was held at 830 ° C. for 2 hours in a dry hydrogen atmosphere, and subjected to strain relief annealing.
まず、得られた純鉄粉について、JIS Z 8801に定める篩を用いた篩わけにより、鉄粉の粒度構成を測定した。いずれの純鉄粉も、表１に示すように通常の範囲の粒度構成を有する鉄粉となっていた。 First, about the obtained pure iron powder, the particle size structure of the iron powder was measured by a sieve using a sieve defined in JIS Z 8801. As shown in Table 1, all the pure iron powders were iron powders having a particle size configuration in a normal range.
鉄粉粒子の不純物量は、Ｃ，Ｏ，Ｓ，Ｎについては燃焼−赤外線吸収法、Si，Mn，Ｐについては高周波誘導結合プラズマ（ＩＣＰ）発光分析法を用いて行った。鉄粉粒子の硬さ測定、およびSiを含む介在物の個数の測定、鉄粉粒子の円形度測定は前記した方法と同様とした。得られた結果を表２に示す。
The amount of impurities in the iron powder particles was determined using a combustion-infrared absorption method for C, O, S, and N, and a high frequency inductively coupled plasma (ICP) emission analysis method for Si, Mn, and P. The hardness measurement of the iron powder particles, the measurement of the number of inclusions containing Si, and the measurement of the circularity of the iron powder particles were the same as described above. The obtained results are shown in Table 2.
成形体の成形密度を表２に併記した。
本発明例はいずれも、7.24Mg／m３以上の高い成形密度を有する成形体となっており、高圧縮性の鉄粉であることがわかる。本発明の範囲を外れる比較例は、成形密度が7.24 Mg／ｍ3 未満であり鉄粉の圧縮性が低下している。
（実施例２）
表２に示した鉄粉に、さらに噴霧法により絶縁被覆処理を施し、鉄粉粒子表面にリン酸アルミニウムからなる絶縁層を形成した。絶縁被覆処理は、Ｐ：Alがモル比で２：１となるように、オルトリン酸と塩化アルミニウムを配合し、総固形分濃度が５質量％の水溶液とした絶縁被覆処理液を用いて行い、該絶縁被覆処理液を、鉄粉および処理液固形分の合計量に対し、固形分質量が0.25質量％となるように噴霧して絶縁層を形成した。
The molding density of the molded body is also shown in Table 2.
Each of the inventive examples is a molded body having a high molding density of 7.24 Mg / m 3 or more, and is found to be a highly compressible iron powder. In the comparative example outside the scope of the present invention, the molding density is less than 7.24 Mg / m 3 and the compressibility of the iron powder is reduced.
(Example 2)
The iron powder shown in Table 2 was further subjected to an insulating coating treatment by a spraying method to form an insulating layer made of aluminum phosphate on the surface of the iron powder particles. Insulating coating treatment is performed using an insulating coating treatment liquid in which orthophosphoric acid and aluminum chloride are blended so that the molar ratio of P: Al is 2: 1 and the total solid concentration is 5% by mass, The insulating coating treatment liquid was sprayed so that the mass of the solid content was 0.25 mass% with respect to the total amount of the iron powder and the solid content of the treatment liquid, thereby forming an insulating layer.
得られた絶縁被覆鉄粉を、金型内にステアリン酸亜鉛の５質量％アルコール懸濁液を塗布して金型潤滑を行った後、金型に装入し、室温（約25℃）で、成形圧力：980MPaで加圧成形し、リング状（外径38mmφ×内径20mmφ×高さ６mm）の成形体とした。得られた成形体に大気中で 200℃×１ｈの焼鈍を施して圧粉磁芯とした。
ついで、得られた圧粉磁芯について、密度、磁気特性を測定した。
The obtained insulation coated iron powder was coated with a 5% by weight alcohol suspension of zinc stearate in the mold and lubricated, and then charged in the mold at room temperature (about 25 ° C). Molding pressure: 980 MPa was pressure-molded to form a ring-shaped molded body (outer diameter 38 mmφ × inner diameter 20 mmφ × height 6 mm). The obtained molded body was annealed at 200 ° C. for 1 hour in the air to obtain a dust core.
Next, the density and magnetic properties of the obtained dust core were measured.
密度は、質量と圧粉磁芯の寸法（外径、内径および高さ）を測定して求めた。また、測定する磁気特性は、磁束密度、最大透磁率とし、圧粉磁芯に、コイルを 100ターン巻き付けて一次側コイルとし、同じ圧粉磁芯にコイルを20ターン巻き付けて二次側コイルとして、最大印可磁場：10kA／ｍの条件下で、直流磁化測定装置により測定した。
得られた結果を表３に示す。
The density was determined by measuring the mass and the dimensions (outer diameter, inner diameter and height) of the dust core. The magnetic characteristics to be measured are the magnetic flux density and maximum permeability. The coil is wound around the powder core for 100 turns to be the primary coil, and the coil is wound around the same powder magnetic core for 20 turns to be the secondary coil. The maximum applied magnetic field was measured with a DC magnetometer under the condition of 10 kA / m.
The obtained results are shown in Table 3.
１ 粒界のみで囲まれた結晶粒
２ 粒界と鉄粉粒子表面で囲まれた結晶粒
1 Crystal grain surrounded only by
Claims (6)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2006003144A JP2007092162A (en) | 2005-02-03 | 2006-01-11 | Highly compressive iron powder, iron powder for dust core using the same and dust core |
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| JP2006003144A JP2007092162A (en) | 2005-02-03 | 2006-01-11 | Highly compressive iron powder, iron powder for dust core using the same and dust core |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009059848A (en) * | 2007-08-31 | 2009-03-19 | Tamura Seisakusho Co Ltd | Core material, core using the same, and choke coil using the core |
| JP2010010673A (en) * | 2008-05-30 | 2010-01-14 | Hitachi Ltd | Soft magnetic powders for magnetic compact, and magnetic compact using the same soft magnetic powders |
| EP2472530A1 (en) | 2010-12-28 | 2012-07-04 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Iron-based soft magnetic powder for dust core, preparation process thereof, and dust core |
| JP2012238866A (en) * | 2012-07-12 | 2012-12-06 | Sumitomo Electric Ind Ltd | Core for reactor, method of manufacturing the same, and reactor |
| JP2013187480A (en) * | 2012-03-09 | 2013-09-19 | Jfe Steel Corp | Powder for dust magnetic core |
| WO2014097556A1 (en) * | 2012-12-19 | 2014-06-26 | Ｊｆｅスチール株式会社 | Iron powder for dust cores |
| JP2014138052A (en) * | 2013-01-16 | 2014-07-28 | Tamura Seisakusho Co Ltd | Powder magnetic core and manufacturing method therefor |
| JP2014138134A (en) * | 2013-01-18 | 2014-07-28 | Tamura Seisakusho Co Ltd | Powder magnetic core and method for manufacturing the same |
| WO2014171065A1 (en) * | 2013-04-19 | 2014-10-23 | Ｊｆｅスチール株式会社 | Iron powder for dust core |
| JP2019147997A (en) * | 2018-02-28 | 2019-09-05 | 株式会社神戸製鋼所 | Iron powder for powder metallurgy |
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| US9275779B2 (en) | 2010-12-28 | 2016-03-01 | Kobe Steel, Ltd. | Iron-based soft magnetic powder for dust core, preparation process thereof, and dust core |
| EP2472530A1 (en) | 2010-12-28 | 2012-07-04 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Iron-based soft magnetic powder for dust core, preparation process thereof, and dust core |
| JP2013187480A (en) * | 2012-03-09 | 2013-09-19 | Jfe Steel Corp | Powder for dust magnetic core |
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| JP2014138052A (en) * | 2013-01-16 | 2014-07-28 | Tamura Seisakusho Co Ltd | Powder magnetic core and manufacturing method therefor |
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| CN105142823B (en) * | 2013-04-19 | 2017-07-28 | 杰富意钢铁株式会社 | Iron powder for dust core |
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