JP7470081B2 - MnZnNiCo-based ferrite and its manufacturing method - Google Patents
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- 229910000859 α-Fe Inorganic materials 0.000 title claims description 83
- 238000004519 manufacturing process Methods 0.000 title claims description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 160
- 229910052742 iron Inorganic materials 0.000 claims description 74
- 230000004907 flux Effects 0.000 claims description 43
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 38
- 239000002994 raw material Substances 0.000 claims description 18
- 238000001816 cooling Methods 0.000 claims description 17
- 239000000203 mixture Substances 0.000 claims description 17
- 238000005245 sintering Methods 0.000 claims description 17
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 14
- 239000012535 impurity Substances 0.000 claims description 10
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 8
- 229910052681 coesite Inorganic materials 0.000 claims description 6
- 229910052906 cristobalite Inorganic materials 0.000 claims description 6
- 238000010298 pulverizing process Methods 0.000 claims description 6
- 239000000377 silicon dioxide Substances 0.000 claims description 6
- 235000012239 silicon dioxide Nutrition 0.000 claims description 6
- 229910052682 stishovite Inorganic materials 0.000 claims description 6
- 229910052905 tridymite Inorganic materials 0.000 claims description 6
- 238000001354 calcination Methods 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 229910052758 niobium Inorganic materials 0.000 claims description 2
- 229910052710 silicon Inorganic materials 0.000 claims description 2
- 229910052725 zinc Inorganic materials 0.000 claims description 2
- 238000007493 shaping process Methods 0.000 claims 1
- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 description 34
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 31
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 27
- 239000000843 powder Substances 0.000 description 24
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(II) oxide Inorganic materials [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 description 18
- 239000011787 zinc oxide Substances 0.000 description 15
- 239000000292 calcium oxide Substances 0.000 description 14
- GNRSAWUEBMWBQH-UHFFFAOYSA-N nickel(II) oxide Inorganic materials [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 description 14
- 230000000694 effects Effects 0.000 description 12
- 239000000696 magnetic material Substances 0.000 description 12
- 239000011162 core material Substances 0.000 description 10
- 238000010304 firing Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 8
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- 229910004298 SiO 2 Inorganic materials 0.000 description 7
- 238000011068 loading method Methods 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- ZKATWMILCYLAPD-UHFFFAOYSA-N niobium pentoxide Chemical compound O=[Nb](=O)O[Nb](=O)=O ZKATWMILCYLAPD-UHFFFAOYSA-N 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052596 spinel Inorganic materials 0.000 description 5
- 239000011029 spinel Substances 0.000 description 5
- 239000004372 Polyvinyl alcohol Substances 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229920002451 polyvinyl alcohol Polymers 0.000 description 4
- 230000002159 abnormal effect Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- GNTDGMZSJNCJKK-UHFFFAOYSA-N divanadium pentaoxide Chemical compound O=[V](=O)O[V](=O)=O GNTDGMZSJNCJKK-UHFFFAOYSA-N 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- 238000011835 investigation Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000000700 radioactive tracer Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 238000007088 Archimedes method Methods 0.000 description 1
- 229910001047 Hard ferrite Inorganic materials 0.000 description 1
- 229910003962 NiZn Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical group [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000005308 ferrimagnetism Effects 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- FBAFATDZDUQKNH-UHFFFAOYSA-M iron chloride Chemical compound [Cl-].[Fe] FBAFATDZDUQKNH-UHFFFAOYSA-M 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- WJZHMLNIAZSFDO-UHFFFAOYSA-N manganese zinc Chemical compound [Mn].[Zn] WJZHMLNIAZSFDO-UHFFFAOYSA-N 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- PBCFLUZVCVVTBY-UHFFFAOYSA-N tantalum pentoxide Inorganic materials O=[Ta](=O)O[Ta](=O)=O PBCFLUZVCVVTBY-UHFFFAOYSA-N 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- 238000004876 x-ray fluorescence Methods 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Landscapes
- Compounds Of Iron (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Soft Magnetic Materials (AREA)
Description
本発明は、特にスイッチング電源向けのトランスの磁心に適したＭｎＺｎＮｉＣｏ系フェライトおよびその製造方法に関するものである。 The present invention relates to MnZnNiCo-based ferrite that is particularly suitable for use as a transformer core for switching power supplies, and to a method for manufacturing the same.
磁性材料は、大きく分けて、酸化物系磁性材料と金属系軟磁性材料とがある。
酸化物系磁性材料は、Ｂａ系フェライトやＳｒ系フェライト等の硬質磁性材料と、ＭｎＺｎ系フェライトやＮｉＺｎ系フェライト等の軟質磁性材料とに分類される。
Magnetic materials are roughly divided into oxide-based magnetic materials and metal-based soft magnetic materials.
Oxide-based magnetic materials are classified into hard magnetic materials such as Ba-based ferrite and Sr-based ferrite, and soft magnetic materials such as MnZn-based ferrite and NiZn-based ferrite.
ここで、金属系軟磁性材料は、酸化物系のものと比べて飽和磁束密度が高いという特長を有する反面、電気抵抗が小さい。そのため、高周波領域で使用する場合には、発生する渦電流に起因して鉄損が大きくなってしまうという問題がある。故に、電子機器の小型化・高密度化の要請から使用周波数の高周波化が進んでいる近年において、例えば、１００ｋＨｚ程度の高周波数帯域において用いられるスイッチング電源等においては、金属系軟磁性材料を用いることはほとんどない。 Metal-based soft magnetic materials have the advantage of having a higher saturation magnetic flux density than oxide-based materials, but on the other hand, they have a lower electrical resistance. Therefore, when used in the high frequency range, there is a problem that the iron loss increases due to the eddy currents that are generated. For this reason, in recent years, when the operating frequencies are becoming higher due to the demand for smaller and higher density electronic devices, metal-based soft magnetic materials are rarely used in switching power supplies and the like used in the high frequency band of about 100 kHz, for example.
一方、上記酸化物磁性材料のうち、軟質磁性材料は、わずかな磁場に対しても容易に磁化する材料であるため、電源や、通信機器、計測制御機器、磁気記録およびコンピュータなどの広い分野に用いられ、特に、高周波数帯域で用いられる電源用トランスの磁心材料には、鉄損が小さい軟質磁性材料のＭｎＺｎ系フェライトが主に用いられてきた。 On the other hand, among the above oxide magnetic materials, soft magnetic materials are easily magnetized even in a slight magnetic field, and are therefore used in a wide range of fields, such as power supplies, communication devices, measurement and control devices, magnetic recording, and computers. In particular, MnZn-based ferrite, a soft magnetic material with low iron loss, has been mainly used as the magnetic core material for power supply transformers used in the high frequency band.
このＭｎＺｎ系フェライトには、電気抵抗率が０．０１～０．０５Ω・ｍ程度と低いため渦電流損が高いという問題があった。そのため、電気抵抗をさらに高めて渦電流損を低減し、全体として鉄損をさらに低減して発熱量を抑えた磁性材料が望まれていた。
この問題に対して、例えば、特許文献１には、ＭｎＺｎ系フェライトに、副成分として酸化カルシウムや酸化ケイ素などの酸化物を微量添加して粒界に偏析させ、粒界抵抗を高めて、全体としての抵抗率を数Ω・ｍ以上と高めることにより解消する技術が開示されている。
This MnZn-based ferrite has a problem of high eddy current loss due to its low electrical resistivity of about 0.01 to 0.05 Ω·m. Therefore, there has been a demand for a magnetic material that further increases electrical resistance to reduce eddy current loss, and further reduces overall iron loss to suppress heat generation.
For example, Patent Document 1 discloses a technique for solving this problem by adding a small amount of oxide such as calcium oxide or silicon oxide as an auxiliary component to MnZn-based ferrite to segregate the oxide at grain boundaries, thereby increasing the grain boundary resistance and increasing the overall resistivity to several Ω·m or more.
さらに、上記電源用としてのＭｎＺｎ系フェライトは、特に、飽和磁束密度Ｂｓが高いこと、キュリー温度Ｔｃが高いこと、および磁気損失Ｐｃｖが低いことが要求されているが、これら飽和磁束密度Ｂｓや、キュリー温度Ｔｃは、ほぼ主成分の組成により決まることが知られている。また、ＭｎＺｎ系フェライトを含む酸化物フェライト化合物は、フェリ磁性を示し、磁気モーメントを有する金属原子の種類ならびにそれが占める位置により飽和磁束密度、キュリー温度が変化することが知られている。 Furthermore, MnZn-based ferrites for use in power supplies are required to have, in particular, a high saturation magnetic flux density Bs, a high Curie temperature Tc, and low magnetic loss Pcv, but it is known that the saturation magnetic flux density Bs and Curie temperature Tc are determined almost entirely by the composition of the main components. It is also known that oxide ferrite compounds containing MnZn-based ferrites exhibit ferrimagnetism, and that the saturation magnetic flux density and Curie temperature change depending on the type and position of metal atoms that have a magnetic moment.
また、酸化物系フェライトの飽和磁束密度は、温度の上昇と共に減少し、磁気が消失する温度であるキュリー温度でゼロとなるので、キュリー温度が高いほど、室温からトランス動作温度までの飽和磁束密度を高く維持できることが知られている。なお、飽和磁束密度に関する技術としては、例えば、特許文献２に、Ｆｅ２Ｏ３量を増やすことにより飽和磁束密度を高めることができる旨開示されている。 It is also known that the saturation magnetic flux density of oxide ferrite decreases with increasing temperature and becomes zero at the Curie temperature, which is the temperature at which magnetism disappears, so that the higher the Curie temperature, the higher the saturation magnetic flux density can be maintained from room temperature to the transformer operating temperature. As a technique related to saturation magnetic flux density, for example, Patent Document 2 discloses that the saturation magnetic flux density can be increased by increasing the amount of Fe2O3 .
ところが、近年、電子機器の電源部分は、小型化の要請に応えるために、各種部品が、さらに高密度に積載される傾向にある。そして、かかる高密度な積載状態では、各種部品の発熱により、フェライトコアが使用される温度、すなわちトランスの動作温度は、８０℃にも達する。 However, in recent years, there has been a trend for the power supply sections of electronic devices to be more densely packed with various components in order to meet the demand for miniaturization. In such a densely packed state, the heat generated by the various components can cause the temperature at which the ferrite core is used, i.e., the operating temperature of the transformer, to reach as high as 80°C.
また、それらの鉄損に関しては、小型化を実現するための駆動周波数の高周波化や様々な周囲温度での省エネルギーのため、最大磁束密度５０ｍＴ、周波数５００ｋＨｚで測定した、０～１００℃における鉄損が１００ｋＷ／ｍ３以下で、かつ鉄損極小温度での鉄損値は７５ｋＷ／ｍ３以下の性能のものが求められてきている。 Regarding their iron loss, in order to increase the driving frequency to realize miniaturization and to save energy at various ambient temperatures, there is a demand for magnets with an iron loss of 100 kW/m3 or less at 0 to 100°C, measured at a maximum magnetic flux density of 50 mT and a frequency of 500 kHz, and an iron loss value of 75 kW/ m3 or less at the minimum iron loss temperature.
しかしながら、上記特許文献１に記載された技術では、小型化を実現するための駆動周波数の高周波化に関しては特に言及がなされていない。 However, the technology described in Patent Document 1 does not specifically mention increasing the drive frequency to achieve compactness.
また、上記特許文献２に記載された技術では、８０℃（磁化力１２００Ａ／ｍ）という所定の高温条件での動作に関しては特に言及がなされていない。 Furthermore, the technology described in Patent Document 2 does not specifically mention operation at the specified high temperature condition of 80°C (magnetizing force 1200 A/m).
さらに、特許文献３には、５００ｋHzの高周波で、かつ２０～１２０℃の温度範囲で鉄損を低減させる技術が開示されているものの、かかる鉄損の絶対値は大きく、かつ、飽和磁束密度については特に言及がなされていない。 Furthermore, Patent Document 3 discloses a technology for reducing iron loss at a high frequency of 500 kHz and in a temperature range of 20 to 120°C, but the absolute value of the iron loss is large and there is no specific mention of saturation magnetic flux density.
ここで、フェライトの鉄損を支配する因子の１つに、磁気異方性定数Ｋ１がある。鉄損は、この磁気異方性定数Ｋ１の温度変化にともなって変化し、Ｋ１＝０となる温度で極小となる。したがって、フェライトの鉄損の温度変化を小さくするには、磁気異方性定数Ｋ１の温度依存性（鉄損温度係数）を小さくする必要がある。 One of the factors governing the iron loss of ferrite is the magnetic anisotropy constant K1 . The iron loss changes with the temperature change of the magnetic anisotropy constant K1 , and is minimal at the temperature where K1 = 0. Therefore, in order to reduce the temperature change of the iron loss of ferrite, it is necessary to reduce the temperature dependency of the magnetic anisotropy constant K1 (iron loss temperature coefficient).
磁気異方性定数Ｋ１は、主相であるフェライトのスピネル化合物を構成する元素の種類によりほぼ決定され、ＭｎＺｎ系フェライトの場合、Ｃｏイオンを導入することによりその温度依存性を小さくし、鉄損温度係数の絶対値を小さくすることができる（例えば、非特許文献１および２参照）。これにより、室温～１００℃付近での鉄損が小さく、かつ、その前後の温度範囲でも鉄損が比較的小さいフェライト材料を得ることが可能となる。 The magnetic anisotropy constant K1 is determined almost entirely by the type of elements constituting the spinel compound of the ferrite, which is the main phase, and in the case of MnZn-based ferrite, the temperature dependency can be reduced by introducing Co ions, and the absolute value of the temperature coefficient of iron loss can be reduced (see, for example, Non-Patent Documents 1 and 2). This makes it possible to obtain a ferrite material that has small iron loss at room temperature to about 100°C, and that also has relatively small iron loss in the temperature range around that temperature.
かかる技術に関しては、例えば、特許文献４には、Ｆｅ２Ｏ３、ＺｎＯ、ＭｎＯを主成分とし、ＣｏＯを０．０１ｍｏｌ％以上０．５ｍｏｌ％未満含有するＭｎＺｎＣｏ系フェライトは、従来以上に広い温度範囲でＫ１＝０となり、高い透磁率と低い損失が広い温度範囲で実現できることが開示されている。
また、特許文献４に記載されたフェライトでは、同文献の第１図に示されているように、コア損失の極小温度が低温度側に移行した事例が紹介されている。
Regarding such technology, for example, Patent Document 4 discloses that an MnZnCo-based ferrite containing Fe2O3 , ZnO , and MnO as main components and containing 0.01 mol% or more and less than 0.5 mol% of CoO has K1 = 0 over a wider temperature range than ever before, and thus realizes high magnetic permeability and low loss over a wider temperature range.
Furthermore, in the ferrite described in Patent Document 4, as shown in FIG. 1 of the same document, a case is introduced in which the minimum temperature of core loss has shifted to the lower temperature side.
しかし、特許文献４に記載のようにＣｏを加えることは、含有される不純物の影響によって、焼成温度や焼成雰囲気の酸素濃度の僅かな変動に起因して、鉄損温度係数や鉄損が極小となる温度が変動するだけでなく、鉄損の絶対値が大きく劣化したりするという別の問題が生じることがある。 However, adding Co as described in Patent Document 4 can cause other problems, such as slight variations in the sintering temperature or oxygen concentration in the sintering atmosphere causing fluctuations in the temperature coefficient of iron loss and the temperature at which iron loss is at a minimum, as well as a large deterioration in the absolute value of iron loss, due to the influence of the impurities contained therein.
したがって、上記したような従来技術（特許文献１～４）では、１００ｋＨｚ程度の高周波数帯域では、概ね問題がないものの、電子部品の電源の小型化、高効率化のために必要な、高密度な積載状態のトランス動作温度まで高い飽和磁束密度を維持したまま、５００ｋＨｚで高周波駆動した際に０～１００℃の広い温度範囲で、磁気の低損失を示す、と言った特性を有するフェライト材料はいずれも実現できていない。 Thus, while the above-mentioned conventional technologies (Patent Documents 1 to 4) generally have no problems in the high frequency band of about 100 kHz, none of them have been able to realize a ferrite material that exhibits low magnetic loss over a wide temperature range of 0 to 100°C when driven at a high frequency of 500 kHz while maintaining a high saturation magnetic flux density up to the operating temperature of the transformer in a densely loaded state, which is necessary for miniaturizing and increasing the efficiency of power supplies for electronic components.
これに対し、特許文献５および６に記載の発明は、これらの問題を解決することを目途としている。
しかしながら、特許文献５では、１００kHz程度の駆動周波数での鉄損値は改善されるものの、５００kHz程度の高周波での鉄損値は大きいという問題や、最大磁束密度５０ｍＴ、周波数５００ｋＨｚで測定した、０～１００℃における鉄損が１００ｋＷ／ｍ３以下で、かつ鉄損極小温度での鉄損値が７５ｋＷ／ｍ３以下という特性値を同時には満たせないという問題が残っていた。
また、特許文献６では、焼結密度が比較的小さいため（４．６５～４．８５Mg/m3）、得られるフェライト材料の焼成時の積載位置による特性バラツキが小さいなどの不安定要素がある。
In contrast, the inventions described in Patent Documents 5 and 6 aim to solve these problems.
However, in Patent Document 5, although the iron loss value at a drive frequency of about 100 kHz is improved, there remains a problem that the iron loss value at a high frequency of about 500 kHz is large, and problems remain in that it is not possible to simultaneously satisfy the characteristic values of an iron loss of 100 kW/ m3 or less at 0 to 100°C and an iron loss value of 75 kW/ m3 or less at the minimum iron loss temperature, measured at a maximum magnetic flux density of 50 mT and a frequency of 500 kHz.
Furthermore, in Patent Document 6, the sintered density is relatively low (4.65 to 4.85 Mg/m 3 ), and therefore there are unstable factors such as small variations in the characteristics of the obtained ferrite material depending on the loading position during sintering.
本発明は、上記の現状に鑑み開発されたもので、電子部品の電源の小型化、高効率化のために、高密度な積載状態のトランス動作温度(８０℃)まで高い飽和磁束密度を維持したまま、５００ｋＨｚの高周波駆動した際に０～１００℃の広い温度範囲で鉄損の絶対値が小さく、かつ焼結密度が比較的大きく、フェライト材料の焼成時の積載位置による特性バラツキが小さいＭｎＺｎＮｉＣｏ系フェライト材料を提供することを目的とする。 The present invention was developed in consideration of the above-mentioned current situation, and aims to provide an MnZnNiCo-based ferrite material that maintains a high saturation magnetic flux density up to the transformer operating temperature (80°C) in a densely loaded state, has a small absolute value of iron loss over a wide temperature range from 0 to 100°C when driven at a high frequency of 500 kHz, has a relatively large sintered density, and has small characteristic variations due to the loading position when the ferrite material is sintered, in order to reduce the size and improve the efficiency of power supplies for electronic components.
発明者らは、従来技術が抱える上記問題点を解決するため、基本成分であるＦｅ２Ｏ３、ＺｎＯ、ＮｉＯ、ＣｏＯおよびＭｎＯといった成分の含有量が、飽和磁束密度や鉄損、およびそれらの温度特性に及ぼす影響について詳細に調査すると共に、添加成分である種々の金属酸化物および種々の製造条件により得られる焼結体の結晶粒界相が、飽和磁束密度や鉄損、並びにそれらの温度特性、および、焼結密度に及ぼす影響について鋭意研究を重ねた。 In order to solve the above-mentioned problems of the conventional technology, the inventors conducted a detailed investigation into the effects of the contents of basic components such as Fe2O3 , ZnO , NiO, CoO and MnO on saturation magnetic flux density, iron loss, and their temperature characteristics, and also conducted extensive research into the effects of various metal oxides, which are added components, and the grain boundary phases of sintered bodies obtained under various manufacturing conditions on saturation magnetic flux density, iron loss, and their temperature characteristics, as well as on sintered density.
その結果、前記問題を解決するには、ＭｎＺｎＮｉＣｏ系フェライトにおける上記基本成分を適性範囲に制御した上で、その範囲に応じて、添加成分である副成分の選択とその量を適正範囲に制御すること、および焼成温度を高くするとともに所定の温度までの冷却速度を一段早くして結晶粒界相を適正に制御すること、並びに、特定の元素の含有量を低減する必要があることをそれぞれ見出した。 As a result, it was discovered that in order to solve the above problems, it is necessary to control the above-mentioned basic components in MnZnNiCo-based ferrite to an appropriate range, and then select and control the amount of the additional sub-components to an appropriate range according to that range, to increase the sintering temperature and increase the cooling rate to a specified temperature to appropriately control the grain boundary phase, and to reduce the content of specific elements.
特に、フェライト原料である酸化鉄として、Ｃｌ含有量が ５００mass ppm以下の酸化鉄を用いると共に、最終焼結体中のＣｌ含有量を８０mass ppm以下に抑制することが、本発明の効果の発現に極めて有効であることを見出し、本発明を完成させた。また、かかる効果の発現には、Ｓｒの含有量を１０．０mass ppm以下とし、さらにＢａの含有量を１０．０mass ppm以下とする必要があることも併せて見出した。 In particular, it was discovered that using iron oxide with a Cl content of 500 mass ppm or less as the iron oxide ferrite raw material and suppressing the Cl content in the final sintered body to 80 mass ppm or less is extremely effective in realizing the effects of the present invention, leading to the completion of the present invention. It was also discovered that in order to realize such effects, it is necessary to keep the Sr content to 10.0 mass ppm or less and the Ba content to 10.0 mass ppm or less.
本発明は、上記の知見に基づき、さらに検討を加えて完成されたもので、本発明の要旨構成は次のとおりである。
１．基本成分、副成分および不可避的不純物からなるＭｎＺｎＮｉＣｏ系フェライトにおいて、前記基本成分を、Ｆｅ２Ｏ３：５３．００～５７．００ｍｏｌ％、ＺｎＯ：４．００～１１．００ｍｏｌ％、ＮｉＯ：０．５０～４．００ｍｏｌ％およびＣｏＯ：０．１０～０．５０ｍｏｌ％残部はＭｎＯとし、前記副成分を、前記基本成分に対し、ＳｉＯ２：５０～５００mass ppm、ＣａＯ：２００～２０００mass ppmおよびＮｂ２Ｏ５：５０～５００mass ppmとし、さらに、前記不可避的不純物におけるＣｌ、ＳｒおよびＢａをそれぞれ、前記基本成分に対しＣｌ：８０mass ppm以下、Ｓｒ：１０．０mass ppm以下およびＢａ：１０．０mass ppm以下に抑制して含み、焼結密度が４．８５Ｍｇ／ｍ３超、５．００Ｍｇ／ｍ３以下であって、８０℃における磁化力１２００Ａ／ｍでの飽和磁束密度が４００ｍＴ以上であり、かつ最大磁束密度が５０ｍＴで、周波数が５００ｋＨｚのときの、０～１００℃における鉄損が１００ｋＷ／ｍ３以下であって鉄損極小温度での鉄損が７５ｋＷ／ｍ３以下であることを特徴とするＭｎＺｎＮｉＣｏ系フェライト。
The present invention has been completed based on the above findings and through further investigation, and the gist and configuration of the present invention is as follows.
1. An MnZnNiCo-based ferrite comprising basic components, accessory components and unavoidable impurities, the basic components being 53.00-57.00 mol % Fe2O3 , 4.00-11.00 mol% ZnO, 0.50-4.00 mol% NiO, 0.10-0.50 mol% CoO with the remainder being MnO, the accessory components being 50-500 mass ppm SiO2 , 200-2000 mass ppm CaO and 50-500 mass ppm Nb2O5 relative to the basic components, and further containing Cl, Sr and Ba as the unavoidable impurities at not more than 80 mass ppm Cl, not more than 10.0 mass ppm Sr and not more than 10.0 mass ppm Ba, respectively, relative to the basic components, and having a sintered density of 4.85 Mg/m The MnZnNiCo-based ferrite has a saturation magnetic flux density of 400 mT or more at a magnetizing force of 1200 A/m at 80°C and a maximum magnetic flux density of 50 mT, and has an iron loss of 100 kW/ m3 or less at 0 to 100°C and an iron loss of 75 kW/ m3 or less at a minimum iron loss temperature when the frequency is 500 kHz.
２．前記１に記載のＭｎＺｎＮｉＣｏ系フェライトを製造する方法であって、基本成分となるＦｅ、Ｚｎ、Ｎｉ、ＣｏおよびＭｎ原料を、混合し、仮焼して、粉砕した後、さらに副成分となるＳｉ、ＣａおよびＮｂ原料を混合して、粉砕し、次いで、成形し、焼成後、冷却する工程を有し、前記Ｆｅ原料を酸化鉄とし、該酸化鉄中のＣｌ含有量を５００mass ppm以下として、前記焼成の最高温度を１２５０℃超とし、さらに該最高温度から１１００℃までの間を１５０℃／ｈ以上の速度で冷却することを特徴とするＭｎＺｎＮｉＣｏ系フェライトの製造方法。 2. A method for producing the MnZnNiCo-based ferrite described in 1 above, comprising the steps of mixing, calcining, and pulverizing the Fe, Zn, Ni, Co, and Mn raw materials as the basic components, and then mixing and pulverizing the Si, Ca, and Nb raw materials as the auxiliary components, and then molding and sintering the mixture, followed by cooling, wherein the Fe raw material is iron oxide, the Cl content in the iron oxide is 500 mass ppm or less, the maximum temperature of the sintering is more than 1250°C, and the sintering is further performed at a rate of 150°C/h or more from the maximum temperature to 1100°C.
３．前記最高温度から１１００℃までの間を１５０～３５０℃／ｈの速度で冷却することを特徴とする前記２に記載のＭｎＺｎＮｉＣｏ系フェライトの製造方法。 3. The method for producing MnZnNiCo ferrite described in 2 above, characterized in that the temperature is cooled at a rate of 150 to 350°C/h from the maximum temperature to 1100°C.
４．前記最高温度を１２５０℃超、１３５０℃以下とすることを特徴とする前記２または３に記載のＭｎＺｎＮｉＣｏ系フェライトの製造方法。 4. The method for producing MnZnNiCo ferrite described in 2 or 3, characterized in that the maximum temperature is greater than 1250°C and less than or equal to 1350°C.
本発明によれば、高密度な積載状態のトランス動作温度(８０℃)に達するまで高い飽和磁束密度を維持したまま、５００ｋＨｚの高周波駆動をした場合に、広い温度範囲で磁気損失が小さく、かつ焼結密度が大きく、フェライト材料の焼成時の積載位置による特性バラツキが小さいＭｎＺｎＮｉＣｏ系フェライトを提供することができる。
また、本発明は、高周波での磁気特性が優れているので、特に、電源トランスを小型化し、低鉄損化することができる。
According to the present invention, it is possible to provide an MnZnNiCo-based ferrite which, when driven at a high frequency of 500 kHz while maintaining a high saturation magnetic flux density until the transformer operating temperature (80° C.) in a densely loaded state is reached, exhibits small magnetic loss over a wide temperature range, has a large sintered density, and exhibits small characteristic variations due to the loading position during sintering of the ferrite material.
Furthermore, since the present invention has excellent magnetic properties at high frequencies, it is possible to reduce the size of power transformers and reduce iron loss.
以下、本発明を具体的に説明する。
本発明のＭｎＺｎＮｉＣｏ系フェライトは、高周波駆動の際の鉄損を低減しさらにかかる鉄損の温度特性を最適化する観点から、Ｆｅ２Ｏ３、ＺｎＯ、ＮｉＯおよびＣｏＯを以下の適正量とし、残部がＭｎＯからなる基本成分を有していることが肝要である。
The present invention will be specifically described below.
From the viewpoint of reducing iron loss during high frequency operation and optimizing the temperature characteristics of such iron loss, it is essential that the MnZnNiCo ferrite of the present invention has basic components consisting of Fe2O3 , ZnO, NiO and CoO in the following appropriate amounts, with the remainder being MnO.
まず、本発明のＭｎＺｎＮｉＣｏ系フェライトの基本成分について具体的に説明する。
Ｆｅ２Ｏ３：基本成分中５３．００～５７．００ｍｏｌ％
Ｆｅ２Ｏ３は、８０℃磁化力１２００Ａ／ｍの飽和磁束密度を４００ｍＴ以上とするために、基本成分中のｍｏｌ比率で５３．００ｍｏｌ％以上とする必要がある。一方、Ｆｅ２Ｏ３は、基本成分中のｍｏｌ比率で５７．００ｍｏｌ％を超えると、鉄損が大きくなり過ぎる。そのため、上限を５７．００ｍｏｌ％とする。好ましくは、５３．００ｍｏｌ％以上５７．００ｍｏｌ％未満、より好ましくは５４．５０～５６．９５ｍｏｌ％の範囲である。
First, the basic components of the MnZnNiCo ferrite of the present invention will be specifically described.
Fe 2 O 3 : 53.00 to 57.00 mol% in the basic component
In order to make the saturation magnetic flux density at 80°C magnetization force of 1200 A/m 400 mT or more, Fe 2 O 3 needs to be 53.00 mol% or more in the molar ratio of the basic component. On the other hand, if the molar ratio of Fe 2 O 3 in the basic component exceeds 57.00 mol%, the iron loss becomes too large. Therefore, the upper limit is set to 57.00 mol%. It is preferably 53.00 mol% or more and less than 57.00 mol%, more preferably in the range of 54.50 to 56.95 mol%.
ＺｎＯ：基本成分中４．００～１１．００ｍｏｌ％
ＺｎＯは、鉄損を小さくし、かつ、最大磁束密度が５０ｍＴで周波数が５００ｋＨｚにおいて、０～１００℃での幅広い温度範囲の損失を小さく維持するために、その添加量を基本成分中のｍｏｌ比率で４．００～１１．００ｍｏｌ％の範囲とする必要がある。好ましくは５．５０～８．５０ｍｏｌ％、さらに好ましくは、６．００～８．００ｍｏｌ％の範囲である。
ZnO: 4.00 to 11.00 mol% in the basic component
In order to reduce core loss and maintain low loss over a wide temperature range from 0 to 100°C at a maximum magnetic flux density of 50 mT and a frequency of 500 kHz, the amount of ZnO added must be in the range of 4.00 to 11.00 mol% in terms of molar ratio in the basic components, preferably 5.50 to 8.50 mol%, and more preferably 6.00 to 8.00 mol%.
ＮｉＯ：基本成分中０．５０～４．００ｍｏｌ％
ＮｉＯは、８０℃磁化力１２００Ａ／ｍの飽和磁束密度を４００ｍＴ以上とし、かつ、鉄損を小さくし、さらに、最大磁束密度が５０ｍＴで周波数が５００ｋＨｚおいて、０～１００℃での幅広い温度範囲の損失を小さく維持するために、その添加量を基本成分中のｍｏｌ比率で０．５０～４．００ｍｏｌ％の範囲とする必要がある。好ましくは、１．５０～３．５０ｍｏｌ％の範囲であり、さらに好ましくは１．００～３．００ｍｏｌ％の範囲である。加えて、より好ましくは１．４５～３．００ｍｏｌ％の範囲であり、最も好ましくは１．５０～３．００ｍｏｌ％の範囲である。
NiO: 0.50 to 4.00 mol% in the base component
NiO has a saturation magnetic flux density of 400 mT or more at 80°C magnetizing force of 1200 A/m, reduces iron loss, and maintains low loss in a wide temperature range from 0 to 100°C at a maximum magnetic flux density of 50 mT and a frequency of 500 kHz. In order to do so, the amount of NiO added must be in the range of 0.50 to 4.00 mol% in terms of molar ratio in the basic components. The range is preferably 1.50 to 3.50 mol%, and more preferably 1.00 to 3.00 mol%. In addition, the range is more preferably 1.45 to 3.00 mol%, and most preferably 1.50 to 3.00 mol%.
ＣｏＯ：基本成分中０．１０～０．５０ｍｏｌ％
ＣｏＯは、特公昭５２－４７５３号公報に記載されたように、透磁率の温度係数を小さくする働きもある。しかしながら、ＣｏＯを過剰に含む場合、鉄損の温度係数が室温以上で正となって熱暴走を起すだけでなく、経時変化が大きくなって望ましくない。よって、ＣｏＯは、基本成分中のｍｏｌ比率で０．５０ｍｏｌ％を上限とする。一方、ＣｏＯは、添加量が少ないと温度係数の改善効果が小さくなって、鉄損値の改善が望めない。よって、ＣｏＯは、基本成分中のｍｏｌ比率で０．１０ｍｏｌ％を下限とする。
CoO: 0.10 to 0.50 mol% in the base component
As described in JP-B-52-4753, CoO also works to reduce the temperature coefficient of magnetic permeability. However, if CoO is included in excess, not only will the temperature coefficient of iron loss become positive above room temperature, causing thermal runaway, but it will also cause large changes over time, which is undesirable. Therefore, the upper limit of CoO is set to 0.50 mol% in terms of molar ratio in the basic components. On the other hand, if the amount of CoO added is small, the effect of improving the temperature coefficient will be small, and it will be difficult to improve the iron loss value. Therefore, the lower limit of CoO is set to 0.10 mol% in terms of molar ratio in the basic components.
本発明のフェライトは、ＭｎＺｎＮｉＣｏ系フェライトであり、上記Ｆｅ２Ｏ３、ＺｎＯ、ＮｉＯおよびＣｏＯ以外の基本成分の残部は、マンガン酸化物（ＭｎＯ）である。ＭｎＯの好ましい範囲は基本成分中のｍｏｌ比率で３１．５０～４０．００ｍｏｌ％であり、さらに好ましくは３１．８０～３９．８０ｍｏｌ％である。加えて、最も好ましくは３１．８０～３７．４０ｍｏｌ％である。 The ferrite of the present invention is a MnZnNiCo-based ferrite, and the remainder of the basic components other than the Fe 2 O 3 , ZnO, NiO, and CoO is manganese oxide (MnO). The preferred range of MnO is 31.50 to 40.00 mol %, more preferably 31.80 to 39.80 mol %, in terms of molar ratio in the basic components. Additionally, the most preferred range is 31.80 to 37.40 mol %.
以上、本発明のＭｎＺｎＮｉＣｏ系フェライトの基本成分について説明したが、本発明の、ＭｎＺｎＮｉＣｏ系フェライトは、上記基本成分のほかに、以下の添加成分を副成分として含有する必要がある。すなわち、本発明のフェライトの基本成分であるＦｅ２Ｏ３、ＺｎＯ、ＭｎＯ、ＮｉＯおよびＣｏＯは、スピネル構造を形成するものであるが、これに、スピネルを形成しないＳｉＯ２、ＣａＯおよびＮｂ２Ｏ５等の副成分を複合添加して、より鉄損の小さい高性能のＭｎＺｎＮｉＣｏ系フェライトとすることができる。なお、スピネルを形成しないＴａ２Ｏ５、ＺｒＯ２およびＶ２Ｏ５等の成分をさらに微量添加してもよい。 The basic components of the MnZnNiCo ferrite of the present invention have been described above, but the MnZnNiCo ferrite of the present invention must contain the following additive components as subcomponents in addition to the above basic components. That is, the basic components of the ferrite of the present invention, Fe2O3 , ZnO , MnO, NiO, and CoO, form a spinel structure, but by adding subcomponents such as SiO2 , CaO , and Nb2O5 that do not form a spinel to these, a high-performance MnZnNiCo ferrite with smaller iron loss can be obtained. Note that trace amounts of components such as Ta2O5 , ZrO2 , and V2O5 that do not form a spinel may also be added.
ＳｉＯ２：前記基本成分に対して５０～５００mass ppm
ＳｉＯ２は、ＣａＯと共に粒界に高抵抗相を形成して、鉄損の低減に寄与する。しかし、添加量が５０mass ppm未満ではその添加効果は小さい。一方、５００mass ppmを超えて含有すると、焼結時に異常粒成長を起こして鉄損を大幅に増大させる。したがって、ＳｉＯ２は、前記基本成分に対して５０～５００mass ppmの範囲で添加する必要がある。なお、焼結体組織中の異常粒の発生をより厳密に管理するには５０～３００mass ppmの範囲が好ましい。さらに、７０～３００mass ppmの範囲がより好ましい。
SiO 2 : 50 to 500 mass ppm based on the basic component
SiO2 forms a high resistance phase at the grain boundary together with CaO, and contributes to reducing iron loss. However, if the amount added is less than 50 mass ppm, the effect of addition is small. On the other hand, if it is contained in an amount exceeding 500 mass ppm, abnormal grain growth occurs during sintering, greatly increasing iron loss. Therefore, SiO2 must be added in the range of 50 to 500 mass ppm relative to the basic components. In order to more strictly control the occurrence of abnormal grains in the sintered body structure, the range of 50 to 300 mass ppm is preferable. Furthermore, the range of 70 to 300 mass ppm is more preferable.
ＣａＯ：前記基本成分に対して２００～２０００mass ppm
ＣａＯは、ＳｉＯ２と共存した場合、粒界抵抗を高めて低鉄損化に寄与するが、添加量が２００mass ppm未満では、その効果は小さい。一方、２０００mass ppmより多くなると、鉄損は逆に増大する。したがって、ＣａＯは、前記基本成分に対して２００～２０００mass ppmの範囲で添加する必要がある。より低鉄損なフェライトを得るためには、ＣａＯは、２００～１５００mass ppmの範囲が好ましい。さらに、４００～１５００mass ppmの範囲がより好ましい。
CaO: 200 to 2000 mass ppm based on the basic components
When CaO coexists with SiO2 , it increases the grain boundary resistance and contributes to low iron loss, but if the amount added is less than 200 mass ppm, the effect is small. On the other hand, if the amount added is more than 2000 mass ppm, the iron loss increases. Therefore, CaO needs to be added in the range of 200 to 2000 mass ppm to the basic components. In order to obtain ferrite with lower iron loss, CaO is preferably in the range of 200 to 1500 mass ppm. Furthermore, the range of 400 to 1500 mass ppm is more preferable.
Ｎｂ２Ｏ５：前記基本成分に対して５０～５００mass ppm
Ｎｂ２Ｏ５は、ＳｉＯ２およびＣａＯの共存下で、比抵抗の増大に有効に寄与するが、含有量が５０mass ppmに満たないと、その添加効果に乏しい。一方、５００mass ppmを超えると、鉄損の増大を招くことになる。したがって、Ｎｂ２Ｏ５は、前記基本成分に対して５０～５００mass ppmの範囲で添加する必要がある。より低鉄損なフェライトを得るためには、Ｎｂ２Ｏ５は、５０～３５０mass ppmの範囲が好ましく、５０～３００mass ppmの範囲がより好ましい。さらに、６０～２７０mass ppmの範囲が最も好ましい。
Nb 2 O 5 : 50 to 500 mass ppm based on the basic components
Nb 2 O 5 effectively contributes to increasing the resistivity in the presence of SiO 2 and CaO, but if the content is less than 50 mass ppm, the effect of adding it is poor. On the other hand, if the content exceeds 500 mass ppm, it will lead to an increase in iron loss. Therefore, Nb 2 O 5 needs to be added in the range of 50 to 500 mass ppm to the basic components. In order to obtain ferrite with lower iron loss, Nb 2 O 5 is preferably in the range of 50 to 350 mass ppm, more preferably in the range of 50 to 300 mass ppm. Furthermore, the range of 60 to 270 mass ppm is most preferable.
また、本発明におけるフェライトの焼結密度は、４．８５Ｍｇ／ｍ３超、５．００Ｍｇ／ｍ３以下の範囲とする。４．８５Ｍｇ／ｍ３以下の場合、所定の強度が保持できないことと、焼成時の積載位置による特性バラツキが大きくなる場合が発生する。一方、５．００Ｍｇ／ｍ３を超えると、高周波駆動の際の鉄損が大きくなってしまうからである。より低鉄損で高強度のフェライトを得るためには、焼結密度を４．８５Ｍｇ／ｍ３超、４．９５Ｍｇ／ｍ３以下の範囲とする。好ましくは４．８６～４．９５Ｍｇ／ｍ３の範囲である。 In addition, the sintered density of the ferrite in the present invention is set to a range of more than 4.85 Mg/ m3 and not more than 5.00 Mg/ m3 . If it is 4.85 Mg/ m3 or less, a predetermined strength cannot be maintained, and there are cases where the characteristic variations due to the loading position during sintering become large. On the other hand, if it exceeds 5.00 Mg/ m3 , the iron loss during high frequency operation becomes large. In order to obtain ferrite with lower iron loss and higher strength, the sintered density is set to a range of more than 4.85 Mg/ m3 and not more than 4.95 Mg/ m3 . The range is preferably 4.86 to 4.95 Mg/ m3 .
なお、本発明におけるＭｎＺｎＮｉＣｏ系フェライトは、前記基本成分、前記副成分および以下の不可避的不純物からなっている。
すなわち、本発明におけるＭｎＺｎＮｉＣｏ系フェライトの前記基本成分および副成分以外の成分は、不可避的不純物である。この不可避的不純物は、Ｃｌ、Ｓｒ、Ｂａ、ＰおよびＢ等が例示される。そして、以下に記載するように、Ｃｌ、ＳｒおよびＢａは、特に、所定量以下に抑制される必要がある成分である。なお、不可避的不純物の含有量は少なければ少ないほどよく、０mass ％であることは好ましいが、本発明では０．０１mass ％以下程度まで許容される。
The MnZnNiCo ferrite of the present invention is composed of the above-mentioned basic components, the above-mentioned minor components, and the following unavoidable impurities.
That is, the components other than the basic components and the subcomponents of the MnZnNiCo ferrite in the present invention are unavoidable impurities. Examples of the unavoidable impurities include Cl, Sr, Ba, P, and B. As described below, Cl, Sr, and Ba are components that need to be suppressed to a predetermined amount or less. The lower the content of the unavoidable impurities, the better, and 0 mass% is preferable, but in the present invention, a content of about 0.01 mass% or less is allowed.
Ｃｌ：８０mass ppm以下
焼結体組織中の異常粒の発生や、結晶粒の粒度分布ばらつきなどを抑制し、焼結体コアの密度低下による飽和磁束密度の低下を抑制するには、原料酸化鉄中のＣｌを５００mass ppm以下に低減すると共に、焼成後の最終焼結体、すなわち、ＭｎＺｎＮｉＣｏ系フェライト中に残存するＣｌ量を８０mass ppm以下に抑制する必要がある。好ましくは７５mass ppm以下である。
なお、原料酸化鉄中に含まれるＣｌは、上記焼成中に揮発させることで上記範囲とすることができるが、高純度の酸化鉄を選択すると、上記揮発させる条件が不要なので、焼成時間が短くても上記成分組成範囲とすることができる。
Cl: 80 mass ppm or less In order to suppress the occurrence of abnormal grains in the sintered compact structure, the variation in grain size distribution of crystal grains, and the like, and to suppress the decrease in saturation magnetic flux density due to the decrease in density of the sintered compact core, it is necessary to reduce Cl in the raw material iron oxide to 500 mass ppm or less, and to suppress the amount of Cl remaining in the final sintered compact after sintering, i.e., the MnZnNiCo-based ferrite, to 80 mass ppm or less, preferably 75 mass ppm or less.
The Cl contained in the raw material iron oxide can be adjusted to the above range by volatilizing it during the firing process. However, if high-purity iron oxide is selected, the above volatilization conditions are not necessary, and the component composition can be adjusted to the above range even if the firing time is short.
Ｓｒ：１０．０mass ppm以下、Ｂａ：１０．０mass ppm以下
前述したように、本発明のＭｎＺｎＮｉＣｏ系フェライトは、基本成分であるＦｅ２Ｏ３、ＺｎＯ、ＭｎＯ、ＮｉＯおよびＣｏＯの組成を前記範囲にそれぞれ制御することに加えて、副成分としてＳｉＯ２、ＣａＯおよびＮｂ２Ｏを、適正量、複合添加することが必要である。また、０～１００℃の温度域で、低鉄損を安定して実現するには、Ｃｌに加えて微量成分として含有されるＳｒおよびＢａの含有量を上記のとおりに制限することが必要である。
Sr: 10.0 mass ppm or less, Ba: 10.0 mass ppm or less As described above, in the MnZnNiCo ferrite of the present invention, in addition to controlling the compositions of the basic components Fe 2 O 3 , ZnO, MnO, NiO and CoO within the above ranges, it is necessary to add appropriate amounts of SiO 2 , CaO and Nb 2 O as auxiliary components in combination. In order to stably achieve low iron loss in the temperature range of 0 to 100°C, it is necessary to limit the contents of Sr and Ba contained as trace components in addition to Cl as described above.
ここで、ＳｒやＢａは、スピネル構造を取らず、六方晶系フェライト、いわゆるハードフェライトを形成するときに用いられる元素である。これらＳｒやＢａが、最終焼結体であるＭｎＺｎＮｉＣｏ系フェライトの磁気特性、特に０～１００℃の温度域での鉄損や透磁率に影響を及ぼす機構については、まだ明確に解明されたわけではないが、発明者らは以下のように考えている。
すなわち、本発明のＭｎＺｎＮｉＣｏ系フェライトのように磁気異方性に大きな影響を及ぼすＣｏが含有されている場合には、これらＳｒやＢａが、Ｃｏとの間に相互作用を生じることで鉄損値が低減しにくくなるためと考えられる。
Here, Sr and Ba are elements used when forming a hexagonal ferrite, so-called hard ferrite, that does not have a spinel structure. The mechanism by which Sr and Ba affect the magnetic properties of the MnZnNiCo ferrite, which is the final sintered body, particularly the core loss and magnetic permeability in the temperature range of 0 to 100°C, has not yet been clearly elucidated, but the inventors believe that it is as follows.
That is, when Co, which has a large effect on magnetic anisotropy, is contained as in the MnZnNiCo-based ferrite of the present invention, it is considered that the Sr and Ba interact with Co, making it difficult to reduce the iron loss value.
本発明のように、０～１００℃の広い温度域で低鉄損を実現するために、ＳｒおよびＢａの含有量は、それぞれ１０．０mass ppm以下とする必要がある。ＳｒおよびＢａは、いずれも１０．０mass ppmを超えて含有されていると、所定の低鉄損値が得られないからである。よって、ＳｒおよびＢａの含有量はそれぞれ１０．０mass ppm以下の範囲に抑制する。さらに低鉄損を実現するには、ＳｒおよびＢａの含有量はそれぞれ７．０mass ppm以下の範囲に抑えるのが好ましい。 In order to achieve low iron loss over a wide temperature range of 0 to 100°C, as in the present invention, the Sr and Ba contents must each be 10.0 mass ppm or less. This is because if the Sr and Ba contents exceed 10.0 mass ppm, the specified low iron loss value cannot be obtained. Therefore, the Sr and Ba contents are each restricted to a range of 10.0 mass ppm or less. To achieve even lower iron loss, it is preferable to restrict the Sr and Ba contents to a range of 7.0 mass ppm or less.
なお、ＳｒおよびＢａについては、主成分の原料である酸化鉄（Ｆｅ２Ｏ３）、酸化亜鉛（ＺｎＯ）、および酸化マンガン（ＭｎＯ）に含まれることがある。そのため、ＳｒおよびＢａの含有量の異なる種々の酸化鉄、酸化亜鉛および酸化マンガン原料を、その使用量を調整することで、ＳｒおよびＢａの含有量を調整することもできる。 Incidentally, Sr and Ba may be contained in the main raw materials, iron oxide (Fe 2 O 3 ), zinc oxide (ZnO), and manganese oxide (MnO). Therefore, the Sr and Ba contents can be adjusted by adjusting the amounts of various iron oxide, zinc oxide, and manganese oxide raw materials with different Sr and Ba contents used.
次に、本発明におけるＭｎＺｎＮｉＣｏ系フェライトの製造方法について、説明する。
本発明のＭｎＺｎＮｉＣｏ系フェライトは、まず、Ｆｅ２Ｏ３、ＺｎＯ、ＭｎＯ、ＮｉＯおよびＣｏＯの粉末原料を、本発明に規定する所定比率となるように秤量し、これらを十分に混合して仮焼し、粉砕して仮焼粉を得る。
その際、Ｆｅ原料である酸化鉄（Ｆｅ２Ｏ３）中のＣｌ含有量を５００mass ppm以下に抑制することが肝要である。そのためには、たとえば塩化鉄の焙焼法で得られた酸化鉄を洗浄するなどの方法で調整する。なお、フェライト用酸化鉄中のＣｌ含有量は、ＪＩＳ Ｋ１４６２（１９８１年）で０．１５％（＝１５００ppm）以下とされているが、本発明では、前述のとおり、焼結体コアの密度低下による飽和磁束密度の低下を抑制するため、さらに低減する必要がある。
Next, a method for producing the MnZnNiCo ferrite according to the present invention will be described.
The MnZnNiCo ferrite of the present invention is prepared by first weighing out powder raw materials of Fe 2 O 3 , ZnO, MnO, NiO and CoO in a predetermined ratio as specified in the present invention, thoroughly mixing them, calcining them, and pulverizing them to obtain a calcined powder.
In this case, it is essential to suppress the Cl content in the iron oxide ( Fe2O3 ) which is the Fe raw material to 500 mass ppm or less. For this purpose, for example, the iron oxide obtained by the roasting method of iron chloride is adjusted by washing. The Cl content in iron oxide for ferrite is set to 0.15% (=1500 ppm) or less in JIS K1462 (1981), but in the present invention, as described above, it is necessary to further reduce it in order to suppress the decrease in saturation magnetic flux density due to the decrease in density of the sintered core.
次いで、上記仮焼粉に、前述した副成分を、本発明に規定する所定の比率となるように加えて混合し、さらに粉砕する。この粉砕作業においては、添加した成分の濃度に偏りがないよう、充分に均質化する必要がある。その後、粉砕した仮焼粉の粉末に、ポリビニルアルコール等の有機物バインダーを添加して、造粒し、さらに圧力を加えて所定の形状に成形し、次いで、焼成して焼結体（製品）とする。 Next, the aforementioned sub-ingredients are added to the calcined powder in the prescribed ratios specified in the present invention, mixed, and then pulverized. In this pulverization process, it is necessary to sufficiently homogenize the added ingredients so that there is no bias in the concentration. After that, an organic binder such as polyvinyl alcohol is added to the pulverized calcined powder, which is granulated, and further pressed to form into a prescribed shape, and then fired to produce a sintered body (product).
ここで、前記焼成の条件は、最高温度から１１００℃までのすべての温度域での冷却速度を１５０℃／ｈ以上とする冷却工程を含む条件とすることが肝要である。かかる冷却工程を含む条件とすることで、本発明のフェライトの焼結密度と所望の粒界相の形成との両立が得られるからである。一方、かかる冷却速度の上限は、特に限定されないが、冷却能力増強にかかるコスト等の観点から３５０℃／ｈ程度が好ましい。なお、かかる冷却速度は、１６０～３５０℃／ｈがより好ましく、１８５～３５０℃／ｈがさらに好ましく、２００～３４０℃／ｈが最も好ましい。また、上記冷却速度の揺らぎは、前記本発明の構成要件を満足するＭｎＺｎＮｉＣｏ系フェライトが得られる程度であれば許容される。
さらに、上記粒界相は、微量成分として添加したＳｉＯ２、Ｃａ、Ｎｂ２Ｏ５などの成分が、薄く、高濃度かつ均一に析出して形成されるものであって、焼成時の冷却速度を制御することで、所望の酸化状態を得ることができ、絶縁性を向上できるものになる。そして、本発明の効果が得られる上記粒界相は、本発明の上記組成および上記冷却工程を含む焼成条件を用いることで効果的に得られるものである。
Here, it is essential that the firing conditions include a cooling step in which the cooling rate in all temperature ranges from the maximum temperature to 1100°C is 150°C/h or more. This is because the conditions including such a cooling step can achieve both the sintered density of the ferrite of the present invention and the formation of the desired grain boundary phase. On the other hand, the upper limit of the cooling rate is not particularly limited, but is preferably about 350°C/h from the viewpoint of the cost of increasing the cooling capacity. The cooling rate is more preferably 160 to 350°C/h, even more preferably 185 to 350°C/h, and most preferably 200 to 340°C/h. The fluctuation of the cooling rate is acceptable as long as it is sufficient to obtain a MnZnNiCo-based ferrite that satisfies the requirements of the present invention.
Furthermore, the grain boundary phase is formed by the thin, high-concentration and uniform precipitation of trace components such as SiO2 , Ca, and Nb2O5 , and the desired oxidation state can be obtained by controlling the cooling rate during firing, thereby improving the insulating properties. The grain boundary phase that provides the effects of the present invention can be effectively obtained by using the composition of the present invention and firing conditions including the cooling step.
前記焼成のその他の条件は、前記したフェライトの焼結密度と粒界相が得られれば、特に限定はされないが、最高温度は１２５０℃超とすることが肝要である。１２５０℃以下では、所望の焼結密度が得られないからである。一方、最高温度の上限は特に限定しないが、加熱によるコスト等の観点から１３５０℃以下が好ましい。なお、かかる最高温度は１２６０～１３５０℃の範囲がより好ましく、１２６０～１３４０℃が最も好ましい。
また、最高温度の保持時間を１～８時間の範囲、最高温度での酸素濃度を１～１０ｖｏｌ％の範囲とすることが好ましい。前記したフェライトの焼結密度と粒界相が効果的に得られるからである。なお、前記焼成の本明細に記載のないその他の条件は常法に従えば良い。
Other conditions for the sintering are not particularly limited as long as the above-mentioned sintered density and grain boundary phase of ferrite are obtained, but it is essential that the maximum temperature is more than 1250°C. This is because the desired sintered density cannot be obtained at 1250°C or lower. On the other hand, the upper limit of the maximum temperature is not particularly limited, but is preferably 1350°C or lower from the viewpoint of heating costs, etc. The maximum temperature is more preferably in the range of 1260 to 1350°C, and most preferably 1260 to 1340°C.
It is also preferable that the holding time at the maximum temperature is in the range of 1 to 8 hours, and the oxygen concentration at the maximum temperature is in the range of 1 to 10 vol %. This is because the above-mentioned sintered density and grain boundary phase of ferrite can be effectively obtained. Other conditions for the sintering that are not described in this specification may be in accordance with conventional methods.
かくして得られたＭｎＺｎＮｉＣｏ系フェライトは、前記粒界相を有しているため、高焼結密度を維持したまま、高周波での鉄損に大きな影響を与える渦電流損失が小さくなり、従来のＭｎＺｎ系フェライトではその実現が極めて困難であった、８０℃における磁化力１２００Ａ／ｍでの飽和磁束密度が４００ｍＴ以上、好ましくは４２５ｍＴ以上で、かつ最大磁束密度５０ｍＴ、周波数５００ｋＨｚで測定した０～１００℃における鉄損が１００ｋＷ／ｍ３以下で、さらには最大磁束密度５０ｍＴ、周波数５００ｋＨｚで測定した鉄損が最小となる温度（本発明において鉄損極小温度ともいう）での鉄損が７５ｋＷ／ｍ３以下の特性値を有し、高密度な積載状態のトランス動作温度(８０℃)まで高い飽和磁束密度を維持したまま、５００ｋＨｚで高周波駆動する場合であっても、広い温度範囲で磁気損失が小さく、かつ、強度が大きく、焼成時の積載位置による特性バラツキが小さな、本発明のＭｎＺｎＮｉＣｏ系フェライトとなる。 Since the MnZnNiCo-based ferrite thus obtained has the grain boundary phase, the eddy current loss, which has a large effect on the iron loss at high frequencies, is reduced while maintaining a high sintered density. This has been extremely difficult to achieve with conventional MnZn-based ferrites, and the saturation magnetic flux density at a magnetizing force of 1200 A/m at 80°C is 400 mT or more, preferably 425 mT or more, and the iron loss at 0 to 100°C measured at a maximum magnetic flux density of 50 mT and a frequency of 500 kHz is 100 kW/ m3 or less, and further the iron loss at the temperature at which the iron loss is minimum measured at a maximum magnetic flux density of 50 mT and a frequency of 500 kHz (also referred to as the minimum iron loss temperature in the present invention) is 75 kW/m The MnZnNiCo-based ferrite of the present invention has a characteristic value of 3 or less, and maintains a high saturation magnetic flux density up to the transformer operating temperature (80° C.) in a densely loaded state, and even when driven at a high frequency of 500 kHz, has small magnetic loss over a wide temperature range, has high strength, and exhibits small characteristic variations due to the loading position during sintering.
その他の、ＭｎＺｎＮｉＣｏ系フェライト粉を製造する工程および焼結体（ＭｎＺｎＮｉＣｏ系フェライト）を製造する工程は、特に限定はなく、いわゆる常法に従えば良い。 The other steps for producing the MnZnNiCo ferrite powder and the sintered body (MnZnNiCo ferrite) are not particularly limited and may be performed according to conventional methods.
以下、本発明について確認した実施例について説明する。
（実施例１）
Ｆｅ２Ｏ３、ＺｎＯ、ＭｎＯ、ＮｉＯおよびＣｏＯの基本成分を、表１－１および表２－１に示す種々の組成となるように原料を混合した。なお、これら原料は不純物の含有量が異なるものを使用した。
上記混合後、９３０℃で３時間の仮焼を行い、粉砕し、仮焼粉を得た。この得られた仮焼粉に、副成分としてＳｉＯ２、ＣａＯおよびＮｂ２Ｏ５を、前記基本成分に対し表１－１および表２－１に示した量となるように添加し、ボールミルで１０時間粉砕し粉砕粉とした。ついで、この粉砕粉にバインダーとしてポリビニルアルコールを添加し、造粒して造粒粉とした後、この造粒粉を、外径：３６ｍｍ、内径：２４ｍｍ、高さ：１２ｍｍのリング状に成形して成形体とした。その後、この成形体に、酸素分圧を１～５ｖｏｌ％の範囲に制御した窒素と空気の混合ガス中、表１－１および表２－１に示した最高温度で３時間の焼成を施した。最後に、表１－１および表２－１に示した速度で最高温度から１１００℃までの冷却をしてリング状試料（フェライト焼結体）を得た。なお、表１－１および表２－１における、酸化鉄中のＣｌ量、焼結体中のＣｌ量、Ｓｒ量、Ｂａ量は蛍光Ｘ線分析により常法に従い測定し、前記基本成分に対する比率を計算して求めた。また、表１－２および表２－２における、焼結密度は上記リング状試料をアルキメデス法に従い測定した。
上記のようにして得たリング状試料に、１次側２０巻・２次側４０巻の巻線を施し、２０～２００℃において、直流ＢＨループトレーサーで１２００Ａ／ｍの磁界をかけたときの磁束密度を測定した。この大きさの磁界では、磁束はほぼ飽和しており、この時の磁束密度の値が飽和磁束密度と考えられるからである。
また、１次側５巻・２次側５巻の巻線を施し、交流ＢＨループトレーサーを用いて、温度を変化させて周波数５００ｋＨｚで磁束密度５０ｍＴまで励磁したときの鉄損を測定した。
The following describes examples that confirmed the present invention.
Example 1
The raw materials were mixed so as to obtain various compositions of the basic components Fe 2 O 3 , ZnO, MnO, NiO and CoO shown in Tables 1-1 and 2-1. Note that the raw materials used had different impurity contents.
After the above mixing, the mixture was calcined at 930°C for 3 hours, pulverized, and calcined powder was obtained. SiO 2 , CaO, and Nb 2 O 5 were added as auxiliary components to the obtained calcined powder in the amounts shown in Tables 1-1 and 2-1 relative to the basic components, and the mixture was pulverized in a ball mill for 10 hours to obtain a pulverized powder. Next, polyvinyl alcohol was added as a binder to the pulverized powder, which was then granulated to obtain a granulated powder. The granulated powder was then molded into a ring shape with an outer diameter of 36 mm, an inner diameter of 24 mm, and a height of 12 mm to obtain a molded body. After that, the molded body was sintered for 3 hours at the maximum temperature shown in Tables 1-1 and 2-1 in a mixed gas of nitrogen and air in which the oxygen partial pressure was controlled to a range of 1 to 5 vol%. Finally, the ring-shaped sample (ferrite sintered body) was obtained by cooling from the maximum temperature to 1100°C at the rate shown in Tables 1-1 and 2-1. In Tables 1-1 and 2-1, the Cl content in the iron oxide, and the Cl content, Sr content, and Ba content in the sintered body were measured by X-ray fluorescence analysis in a conventional manner, and the ratios to the basic components were calculated. In Tables 1-2 and 2-2, the sintered density was measured by measuring the ring-shaped samples according to the Archimedes method.
The ring-shaped sample obtained as described above was wound with 20 turns on the primary side and 40 turns on the secondary side, and the magnetic flux density was measured when a magnetic field of 1200 A/m was applied using a DC BH loop tracer at 20 to 200° C. In a magnetic field of this magnitude, the magnetic flux is nearly saturated, and the magnetic flux density value at this point is considered to be the saturated magnetic flux density.
In addition, the primary winding had 5 turns and the secondary winding had 5 turns, and the core loss was measured using an AC BH loop tracer when the temperature was changed and the magnet was excited to a magnetic flux density of 50 mT at a frequency of 500 kHz.
上記測定結果に基づき、フェライト焼結体の密度、８０℃での飽和磁束密度、鉄損極小温度、ならびに０℃、１００℃および鉄損極小温度における鉄損値（以下、単に物性値といった場合はかかる６項目の物性値を指す）を、それぞれ表１－２および表２－２に記載した。ここで、表１－１，２のＮｏ．１－１～１－２７は、本発明に適合する発明例を、一方、表２－１，２のＮｏ．２－１～２－２８は、本発明の範囲から外れた比較例を示したものである。なお、表１－１，２のＮｏ．１－１～１－１９は、焼成中の最高温度を１３００℃とし、表１－１，２のＮｏ．１－２０～１－２３は、焼成中の最高温度をそれぞれ１２６０℃、１２７５℃、１３２５℃および１３４０℃のいずれかの温度に変化させた例を示した。また、表１－１，２のＮｏ．１－２４～１－２６は冷却速度を変化させた例、表１－１，２のＮｏ．１－２７は酸化鉄中のＣｌ量を低減させた例をそれぞれ示している。 Based on the above measurement results, the density of the ferrite sintered body, the saturation magnetic flux density at 80°C, the minimum iron loss temperature, and the iron loss values at 0°C, 100°C, and the minimum iron loss temperature (hereinafter, when simply referring to physical properties, it refers to these six physical property values) are listed in Tables 1-2 and 2-2, respectively. Here, No. 1-1 to 1-27 in Tables 1-1 and 2 show invention examples that conform to the present invention, while No. 2-1 to 2-28 in Tables 2-1 and 2 show comparative examples that fall outside the scope of the present invention. Note that No. 1-1 to 1-19 in Tables 1-1 and 2 show examples in which the maximum temperature during firing was set to 1300°C, and No. 1-20 to 1-23 in Tables 1-1 and 2 show examples in which the maximum temperature during firing was changed to 1260°C, 1275°C, 1325°C, or 1340°C, respectively. Also, No. No. 1-24 to 1-26 show examples where the cooling rate was changed, and No. 1-27 in Tables 1-1 and 1-2 shows an example where the amount of Cl in the iron oxide was reduced.
表１－１，２および表２－１，２の記載からわかるように、Ｆｅ２Ｏ３、ＺｎＯ、ＭｎＯ、ＮｉＯおよびＣｏＯの基本成分とＳｉＯ２、ＣａＯおよびＮｂ２Ｏ５の副成分の組成をそれぞれ適切に選んだ上で、フェライト原料である酸化鉄として、Ｃｌ含有量が ５００mass ppm以下の酸化鉄を用いると共に、最終焼結体中のＣｌ含有量を８０mass ppm以下に抑制し、さらに、ＳｒおよびＢａを１０．０mass ppm以下に制御した発明例のＭｎＺｎＮｉＣｏ系フェライトは、本発明の焼成条件下で、いずれも、焼結密度が４．８５Ｍｇ／ｍ3超、５．００Ｍｇ／ｍ3以下の範囲となっている。また、磁化力１２００Ａ／ｍ、測定温度８０℃での飽和磁束密度が４００ｍＴ以上となっている。さらに、最大磁束密度５０ｍＴ、周波数５００ｋＨｚで測定した、０および１００℃における鉄損は１００ｋＷ／ｍ３以下で、鉄損極小温度における鉄損は７５ｋＷ／ｍ３以下となっている。
これらのことから、本発明に従えば、焼結密度と飽和磁束密度を高く維持したまま、０～１００℃の温度域で鉄損の低いＭｎＺｎＮｉＣｏ系フェライト材が得られることが分かる。
As can be seen from the descriptions in Tables 1-1 and 2 and Tables 2-1 and 2, the MnZnNiCo-based ferrites of the invention, which are produced by appropriately selecting the compositions of the basic components Fe 2 O 3 , ZnO, MnO, NiO, and CoO, and the subcomponents SiO 2 , CaO, and Nb 2 O 5 , using iron oxide having a Cl content of 500 mass ppm or less as the iron oxide used as the ferrite raw material, suppressing the Cl content in the final sintered body to 80 mass ppm or less, and further controlling Sr and Ba to 10.0 mass ppm or less, all have a sintered density of more than 4.85 Mg/m 3 and 5.00 Mg/m 3 or less under the sintering conditions of the present invention. In addition, the magnetizing force is 1200 A/m, and the saturation magnetic flux density at a measurement temperature of 80° C. is 400 mT or more. Furthermore, the iron loss at 0 and 100° C., measured at a maximum magnetic flux density of 50 mT and a frequency of 500 kHz, is 100 kW/m 3 or less, and the iron loss at the minimum iron loss temperature is 75 kW/m 3 or less.
From these, it is seen that according to the present invention, it is possible to obtain a MnZnNiCo ferrite material having low core loss in the temperature range of 0 to 100° C. while maintaining high sintered density and saturation magnetic flux density.
一方、本発明の成分組成をいずれか満たさない比較例のＭｎＺｎＮｉＣｏ系フェライトは、いずれも、最大磁束密度５０ｍＴ、周波数５００ｋＨｚで測定した、０および１００℃の何れかの温度での鉄損値が１００ｋＷ／ｍ３を超えている。また、鉄損極小温度での鉄損値は、いずれも、７５ｋＷ／ｍ３を超えたものしか得られていない。 On the other hand, the MnZnNiCo ferrites of the comparative examples, which do not satisfy any of the component compositions of the present invention, all have iron loss values exceeding 100 kW/ m3 at either temperature of 0 or 100°C, measured at a maximum magnetic flux density of 50 mT and a frequency of 500 kHz. Also, the iron loss value at the minimum iron loss temperature only exceeded 75 kW/ m3 .
（実施例２）
以下、焼成の積載位置による特性値のバラツキを確認した実施例について説明する。
Ｆｅ２Ｏ３、ＺｎＯ、ＭｎＯ、ＮｉＯおよびＣｏＯの基本成分を、表１－１の試料Ｎｏ．１－２０に示す組成となるように原料を混合した。上記混合後、９３０℃で３時間の仮焼を行い、粉砕し、仮焼粉を得た。この得られた仮焼粉に、副成分としてＳｉＯ２、ＣａＯおよびＮｂ２Ｏ５を、前記基本成分に対し表１－１の試料Ｎｏ．１－２０に示した量となるように添加し、ボールミルで１０時間粉砕し粉砕粉とした。
ついで、この粉砕粉にバインダーとしてポリビニルアルコールを添加し、造粒して造粒粉とした後、この造粒粉を、外径：３６ｍｍ、内径：２４ｍｍ、高さ：１２ｍｍのリング状に成形して、１９２個の成形体を作製した。
上記１９２個の成形体を３００ｍｍ角の焼成台板上に、平面：８行×８列，高さ：３段重ねで積載した。ついで、酸素分圧を１～５ｖｏｌ％の範囲に制御した窒素と空気の混合ガス中、表１－１の試料Ｎｏ．１－２０に示した最高温度で３時間の焼成を施した。最後に、表１－１の試料Ｎｏ．１－２０に示した速度で、上記最高温度から１１００℃まで冷却して、リング状試料（フェライト焼結体）を得た。
Example 2
Hereinafter, an example will be described in which the variation in characteristic values due to the loading position during firing was confirmed.
The raw materials were mixed so that the basic components of Fe 2 O 3 , ZnO, MnO, NiO, and CoO were the composition shown in Sample No. 1-20 in Table 1-1. After the above mixing, the mixture was calcined at 930°C for 3 hours and pulverized to obtain a calcined powder. To the calcined powder obtained, SiO 2 , CaO, and Nb 2 O 5 were added as auxiliary components in the amounts shown in Sample No. 1-20 in Table 1-1 relative to the basic components, and the mixture was pulverized in a ball mill for 10 hours to obtain a pulverized powder.
Next, polyvinyl alcohol was added to this pulverized powder as a binder, and the powder was granulated to obtain a granulated powder. The granulated powder was then molded into ring shapes with an outer diameter of 36 mm, an inner diameter of 24 mm, and a height of 12 mm, to produce 192 molded bodies.
The 192 compacts were stacked on a 300 mm square firing plate in a plane of 8 rows x 8 columns, and a height of 3 layers. Next, they were fired for 3 hours at the maximum temperature shown in Sample No. 1-20 of Table 1-1 in a mixed gas of nitrogen and air with the oxygen partial pressure controlled to the range of 1 to 5 vol%. Finally, they were cooled from the maximum temperature to 1100°C at the rate shown in Sample No. 1-20 of Table 1-1 to obtain ring-shaped samples (ferrite sintered bodies).
前記物性値を、前記実施例１に記載の方法でそれぞれ測定し、各物性値の焼成の積載位置によるバラツキ(最大値－最小値)を求めた。それぞれの結果を、試料Ｎｏ．１－２０として表３に示す。
また、表１－１の試料Ｎｏ．１－２１、試料Ｎｏ．１－２２、試料Ｎｏ．１－２３および表２－１の試料Ｎｏ．２－２７についても、同様の手順で試料を作製し、各物性値のバラツキ(最大値－最小値)をそれぞれ求めた。それぞれの結果を、試料Ｎｏ．１－２１、試料Ｎｏ．１－２２、試料Ｎｏ．１－２３および試料Ｎｏ．２－２７として表３に併記する。
The physical properties were measured by the method described in Example 1, and the variation (maximum value-minimum value) of each physical property due to the loading position during firing was determined. The results are shown in Table 3 as Samples No. 1-20.
In addition, for Sample No. 1-21, Sample No. 1-22, Sample No. 1-23 in Table 1-1 and Sample No. 2-27 in Table 2-1, samples were prepared in the same manner, and the variation (maximum value-minimum value) of each physical property value was determined. The respective results are shown in Table 3 as Sample No. 1-21, Sample No. 1-22, Sample No. 1-23, and Sample No. 2-27.
前記実施例１の結果および表３に記載した結果より、発明例（試料Ｎｏ．１－２０、試料Ｎｏ．１－２１、試料Ｎｏ．１－２２および試料Ｎｏ．１－２３）は比較例（試料Ｎｏ．２－２７）に比べて、各物性値が優れた値になっているだけでなく、各物性値のバラツキも小さいことが分かる。 From the results of Example 1 and the results shown in Table 3, it can be seen that the inventive examples (samples No. 1-20, 1-21, 1-22 and 1-23) not only have superior physical property values compared to the comparative example (sample No. 2-27), but also have smaller variations in the physical property values.
（実施例３）
以下、１１００℃までの冷却速度を規定する技術的意味を明確にするための実験を行い、かかる実験の結果、明確になった技術的意味を実験結果と共に説明する。
Ｆｅ２Ｏ３、ＺｎＯ、ＭｎＯ、ＮｉＯおよびＣｏＯの基本成分を、表４－１に示す組成となるように原料を混合した。
上記混合後、９３０℃で３時間の仮焼を行い、粉砕し、仮焼粉を得た。この得られた仮焼粉に、副成分としてＳｉＯ２、ＣａＯおよびＮｂ２Ｏ５を、前記基本成分に対し表４－１に示した量となるように添加し、ボールミルで１０時間粉砕し粉砕粉とした。ついで、この粉砕粉にバインダーとしてポリビニルアルコールを添加し、造粒して造粒粉とした後、この造粒粉を、外径：３６ｍｍ、内径：２４ｍｍ、高さ：１２ｍｍのリング状に成形して成形体とした。その後、この成形体に、酸素分圧を１～５ｖｏｌ％の範囲に制御した窒素と空気の混合ガス中、表４－１に示した最高温度で３時間の焼成を施した。
次に、表４－１に示した速度で上記最高温度から１２００℃まで冷却し、さらに表４－１に示した速度で１２００℃から１１００℃まで冷却して、リング状試料（フェライト焼結体）を得た。なお、表４－１における、酸化鉄中のＣｌ量、焼結体中のＣｌ量、Ｓｒ量、Ｂａ量、および、焼結密度は、実施例１と同様の方法で測定した。
さらに、前記物性値を、実施例１と同様の方法で測定した。それぞれの測定結果を表４－２に示す。
Example 3
Hereinafter, an experiment was carried out to clarify the technical meaning of the cooling rate up to 1100° C., and the technical meaning clarified as a result of the experiment will be described together with the experimental results.
The raw materials were mixed so that the basic components of Fe 2 O 3 , ZnO, MnO, NiO and CoO were the compositions shown in Table 4-1.
After the above mixing, the mixture was calcined at 930°C for 3 hours, pulverized, and calcined powder was obtained. SiO 2 , CaO, and Nb 2 O 5 were added as auxiliary components to the obtained calcined powder in the amounts shown in Table 4-1 relative to the basic components, and the mixture was pulverized in a ball mill for 10 hours to obtain a pulverized powder. Next, polyvinyl alcohol was added as a binder to the pulverized powder, which was then granulated to obtain a granulated powder. The granulated powder was then molded into a ring shape with an outer diameter of 36 mm, an inner diameter of 24 mm, and a height of 12 mm to obtain a molded body. After that, the molded body was sintered for 3 hours at the maximum temperature shown in Table 4-1 in a mixed gas of nitrogen and air in which the oxygen partial pressure was controlled to a range of 1 to 5 vol%.
Next, the sample was cooled from the maximum temperature to 1200°C at the rate shown in Table 4-1, and further cooled from 1200°C to 1100°C at the rate shown in Table 4-1 to obtain a ring-shaped sample (ferrite sintered body). The Cl amount in the iron oxide, the Cl amount, Sr amount, Ba amount in the sintered body, and the sintered density in Table 4-1 were measured in the same manner as in Example 1.
Furthermore, the physical properties were measured in the same manner as in Example 1. The results of each measurement are shown in Table 4-2.
比較例である試料４－１、４－２のＭｎＺｎＮｉＣｏ系フェライトは、いずれも、最大磁束密度５０ｍＴ、周波数５００ｋＨｚで測定した、０および１００℃の何れかの温度での鉄損値が１００ｋＷ／ｍ３を超えている。また、鉄損極小温度での鉄損値は、いずれも、７５ｋＷ／ｍ３を超えたものしか得られていない。 In the MnZnNiCo ferrite samples 4-1 and 4-2, which are comparative examples, the iron loss values at either temperature of 0 or 100°C, measured at a maximum magnetic flux density of 50 mT and a frequency of 500 kHz, exceed 100 kW/ m3 . Also, the iron loss values at the minimum iron loss temperature are all more than 75 kW/ m3 .
かかる実施例３の結果により、前記最高温度から１１００℃までの間を所定の速度で冷却することは、特に、高密度な積載状態のトランス動作温度(８０℃)に達するまで高い飽和磁束密度を維持したまま、５００ｋＨｚの高周波駆動をした場合に、広い温度範囲で磁気損失を抑制するための重要な要件であることが分かる。 The results of Example 3 show that cooling at a specified rate from the maximum temperature to 1100°C is an important requirement for suppressing magnetic loss over a wide temperature range, particularly when operating at a high frequency of 500 kHz while maintaining a high saturation magnetic flux density until the transformer operating temperature (80°C) is reached in a densely loaded state.
本発明は、飽和磁束密度が高く、５００ｋＨｚといった高周波であっても、広い温度範囲で磁気損失の小さいＭｎＺｎＮｉＣｏ系フェライトを提供することができるので、車載機器、産業機器などで使用が増加しているＳｉＣやＧａＮ半導体デバイスを用いた高周波駆動電源などに広く応用することができる。 The present invention provides MnZnNiCo-based ferrite that has a high saturation magnetic flux density and low magnetic loss over a wide temperature range, even at high frequencies such as 500 kHz, and can therefore be widely applied to high-frequency drive power supplies using SiC and GaN semiconductor devices, the use of which is increasing in in-vehicle equipment and industrial equipment.
Claims (4)
前記基本成分を、
Ｆｅ２Ｏ３：５３．００～５７．００ｍｏｌ％、
ＺｎＯ：４．００～１１．００ｍｏｌ％、
ＮｉＯ：０．５０～４．００ｍｏｌ％および
ＣｏＯ：０．１０～０．５０ｍｏｌ％
残部はＭｎＯ
とし、
前記副成分を、前記基本成分に対し、
ＳｉＯ２：５０～５００mass ppm、
ＣａＯ：２００～２０００mass ppmおよび
Ｎｂ２Ｏ５：５０～５００mass ppm
とし、
さらに、前記不可避的不純物におけるＣｌ、ＳｒおよびＢａをそれぞれ、前記基本成分に対し
Ｃｌ：８０mass ppm以下、
Ｓｒ：１０．０mass ppm以下および
Ｂａ：１０．０mass ppm以下
に抑制して含み、
焼結密度が４．８５Ｍｇ／ｍ３超、５．００Ｍｇ／ｍ３以下であって、８０℃における磁化力１２００Ａ／ｍでの飽和磁束密度が４００ｍＴ以上であり、かつ最大磁束密度が５０ｍＴで、周波数が５００ｋＨｚのときの、０～１００℃における鉄損が１００ｋＷ／ｍ３以下であって鉄損極小温度での鉄損が７５ｋＷ／ｍ３以下であることを特徴とするＭｎＺｎＮｉＣｏ系フェライト。 In a MnZnNiCo-based ferrite consisting of basic components, accessory components and unavoidable impurities,
The base component is
Fe2O3 : 53.00 to 57.00 mol%,
ZnO: 4.00 to 11.00 mol%,
NiO: 0.50 to 4.00 mol% and CoO: 0.10 to 0.50 mol%
The balance is MnO
year,
The subcomponent is mixed with the base component,
SiO2 : 50 to 500 mass ppm,
CaO: 200 to 2000 mass ppm and Nb 2 O 5 : 50 to 500 mass ppm
year,
Furthermore, the unavoidable impurities of Cl, Sr, and Ba are each limited to Cl: 80 mass ppm or less relative to the basic components;
Sr: 10.0 mass ppm or less and Ba: 10.0 mass ppm or less are suppressed,
A MnZnNiCo-based ferrite having a sintered density of more than 4.85 Mg/ m3 and not more than 5.00 Mg/m3, a saturation magnetic flux density of 400 mT or more at a magnetizing force of 1200 A/m at 80°C and a maximum magnetic flux density of 50 mT, an iron loss of 100 kW/m3 or less at 0 to 100°C when the frequency is 500 kHz, and an iron loss of 75 kW/ m3 or less at a minimum iron loss temperature.
前記Ｆｅ原料を酸化鉄とし、該酸化鉄中のＣｌ含有量を５００mass ppm以下として、
前記焼成の最高温度を１２５０℃超とし、さらに該最高温度から１１００℃までの間を１５０℃／ｈ以上の速度で冷却することを特徴とするＭｎＺｎＮｉＣｏ系フェライトの製造方法。 A method for producing the MnZnNiCo-based ferrite according to claim 1, comprising the steps of mixing, calcining and pulverizing Fe, Zn, Ni, Co and Mn raw materials as basic components, and then mixing and pulverizing Si, Ca and Nb raw materials as accessory components, and then shaping and sintering the mixture, followed by cooling;
The Fe raw material is iron oxide, and the Cl content in the iron oxide is 500 mass ppm or less,
A method for producing MnZnNiCo-based ferrite, characterized in that the maximum temperature of the sintering is more than 1250°C, and further, cooling is performed at a rate of 150°C/h or more from the maximum temperature to 1100°C.
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| JP2019199378A (en) | 2018-05-16 | 2019-11-21 | Ｊｆｅケミカル株式会社 | MnZnNiCo-based ferrite and method for producing the same |
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| JP2000286119A (en) | 1999-03-30 | 2000-10-13 | Kawasaki Steel Corp | Ferrite |
| JP2002231520A (en) | 2001-02-07 | 2002-08-16 | Tdk Corp | MnZn FERRITE |
| JP2006290632A (en) | 2005-04-05 | 2006-10-26 | Hitachi Metals Ltd | Ferrite sintered compact, method for producing the same, and electronic component using the same |
| JP2017145152A (en) | 2016-02-15 | 2017-08-24 | Ｊｆｅケミカル株式会社 | MnZnCo-BASED FERRITE |
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