WO2017141978A1 - Ferrite sintered body and ferrite core - Google Patents
Ferrite sintered body and ferrite core Download PDFInfo
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- WO2017141978A1 WO2017141978A1 PCT/JP2017/005562 JP2017005562W WO2017141978A1 WO 2017141978 A1 WO2017141978 A1 WO 2017141978A1 JP 2017005562 W JP2017005562 W JP 2017005562W WO 2017141978 A1 WO2017141978 A1 WO 2017141978A1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
- H01F1/34—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials non-metallic substances, e.g. ferrites
Definitions
- the present invention relates to a ferrite sintered body and a ferrite core.
- Ferrite sintered bodies are widely used in electronic parts such as inductors, power transformers, and electromagnetic filters.
- a ferrite sintered body forming a core (magnetic core) in these electronic components is called a ferrite core (see Patent Documents 1 and 2).
- An inductor is used for an LC resonance circuit in a sensing device that requires high accuracy.
- the magnetic characteristics of the ferrite core also vary with changes in the outside air temperature, so it is difficult to maintain accuracy over a wide temperature range.
- the ferrite surface needs to have an insulating property, and the specific resistance is required to be 1 ⁇ 10 9 ⁇ ⁇ cm or more. It was difficult to use.
- an insulation process such as providing an insulating layer as a base is required.
- the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a ferrite sintered body and a ferrite core that have a small variation in magnetic permeability and a large specific resistance in a wide temperature range.
- the ferrite sintered body of the present invention contains 48 to 49 mol% Fe 2 O 3 , 15 to 17 mol% NiO, and 35 to 37 mol% ZnO, and has a C content of 0.003 mass% or less, and S Is 0.015 mass% or less, and the total amount of Fe 2 O 3 , NiO, and ZnO is 99.8 mol% or more.
- the ferrite core of the present invention contains 48 to 49 mol% Fe 2 O 3 , 15 to 17 mol% NiO, and 35 to 37 mol% ZnO, and has a C content of 0.003% by mass or less. Is 0.015 mass% or less, and the total amount of Fe 2 O 3 , NiO, and ZnO is 99.8 mol% or more.
- a ferrite sintered body and a ferrite core that have a small variation in magnetic permeability over a wide temperature range and a large specific resistance.
- the ferrite sintered body of the present embodiment includes 48 to 49 mol% Fe 2 O 3 , 15 to 17 mol% NiO, and 35 to 37 mol% ZnO, and the content of C is 0.003 mass% or less, The S content is 0.015% by mass or less, and the total amount of Fe 2 O 3 , NiO, and ZnO is 99.8 mol% or more.
- Such a ferrite sintered body has a small variation in magnetic permeability over a wide temperature range and a large specific resistance.
- the total amount of Fe 2 O 3 , NiO, and ZnO is 99.8 mol% or more.
- the total amount is preferably 99.9 mol% or more.
- the content of C is 0.003% by mass or less.
- the C content is preferably 0.001 to 0.002% by mass, and it is possible to substantially not contain C.
- the content of S is 0.015% by mass or less.
- the content of S is preferably 0.005 to 0.010 mass%, and S can be substantially not included.
- substantially not contained means that it is less than the detection limit value in the measurement by the combustion method.
- the ferrite sintered body of the present embodiment may not substantially contain components other than Fe 2 O 3 , NiO, and ZnO.
- the ferrite sintered body preferably has a temperature coefficient of permeability (relative permeability) at ⁇ 20 ° C. to 120 ° C. of 25 ppm / K or less, more preferably 20 ppm / K or less, and 10 ppm / K or less. More preferably.
- a temperature coefficient of permeability at ⁇ 20 ° C. to 120 ° C. is in the above range, the ferrite sintered body is not easily affected by fluctuations in the outside air temperature when used in sensing devices that require high accuracy, and has a wide temperature range. High-precision sensing performance can be obtained.
- the temperature coefficient of the permeability means a value obtained by dividing the difference between the maximum value and the minimum value of the permeability in a certain temperature region by the temperature change.
- the magnetic permeability is a value measured at a frequency of 1 MHz with an impedance analyzer, for example.
- the temperature coefficient of magnetic permeability (relative magnetic permeability) can be 5 ppm / K or less, and can also be 3 ppm / K or less.
- the ferrite sintered body has an electric resistance value (specific resistance) of preferably 1 ⁇ 10 9 ⁇ ⁇ cm or more, and more preferably 1 ⁇ 10 10 ⁇ ⁇ cm or more.
- an insulation treatment is not required during use.
- the sintered density of the ferrite sintered body is preferably 5.3 to 5.5 g / cm 3 . Such a density is preferable because the void generation rate is small and the variation in magnetic permeability due to external factors (temperature, humidity, pressure) tends to be small.
- the ferrite sintered body of the present embodiment may contain Fe alone or an oxide of Cd, Co, Cu, Pb, Si, or Mn as an inevitable impurity.
- the total amount of inevitable impurities in the ferrite sintered body is preferably less than 300 mol ppm, and it is preferable that these impurities are not substantially contained.
- the manufacturing method of the ferrite sintered compact in this embodiment is demonstrated.
- the Fe 2 O 3 raw material, the NiO raw material, and the ZnO raw material are mixed at a composition ratio such that the content of Fe 2 O 3 , NiO, and ZnO in the ferrite sintered body is in the above range to obtain a raw material powder.
- the Fe 2 O 3 raw material include Fe 2 O 3 powder and Fe 3 O 4 powder.
- the NiO raw material include NiO powder.
- the ZnO raw material include ZnO powder.
- the average particle diameter of the Fe 2 O 3 raw material, NiO raw material, and ZnO raw material is preferably 0.1 to 10 ⁇ m.
- the purity of the Fe 2 O 3 raw material, NiO raw material, and ZnO raw material is preferably 100 to 1000 ppm by mass of metal impurities.
- the impurities include Cd, Co, Cu, Pb, Si, or Mn.
- the mixing method may be wet or dry, but is preferably dry from the viewpoint of preventing impurities from remaining.
- the raw material powder is temporarily fired to obtain a temporarily fired product.
- the calcination is preferably performed in air under conditions of a calcination temperature of 800 to 1200 ° C. and a calcination time of 2 to 50 hours.
- the calcination product is pulverized.
- the ground calcined product is molded to obtain a molded body.
- the pressure during molding is preferably 50 to 500 MPa.
- the atmosphere during pre-firing may be a (N 2 + O 2 ) mixed gas having an oxygen content of 1 to 50% by volume.
- the molded body does not contain a binder.
- a molded object does not contain a binder substantially, it can suppress that a void generate
- the content of C and S in the ferrite sintered body can be within the above range.
- a molded object does not contain CuO substantially. When CuO is not substantially contained, generation of voids in the molded body during the main firing can be suppressed, and the temperature coefficient of permeability can be further improved.
- the obtained molded body is subjected to main firing to obtain a ferrite sintered body.
- the main calcination is preferably performed in air under conditions of a main calcination temperature of 1000 to 1500 ° C. and a main calcination time of 2 to 50 hours.
- the atmosphere for the main firing may be a (N 2 + O 2 ) mixed gas having an oxygen amount of 1 to 50% by volume. In some cases, H 2 may be introduced.
- the obtained sintered body is cut or polished to obtain a ferrite core having a predetermined shape.
- a shape of a ferrite core It can be set as rod shape, plate shape, etc.
- the ferrite core of this embodiment has a small variation in permeability and a low specific resistance over a wide temperature range. Therefore, it can be suitably used for an LC resonance circuit in a sensing device that requires high accuracy without performing insulation treatment or the like.
- Fe 2 O 3 powder having a purity of 99.9% by mass and an average particle size of 0.5 ⁇ m, NiO powder, ZnO powder and CuO powder were mixed at the composition ratio shown in Table 1 to obtain a raw material powder.
- the raw material powder was calcined at 1100 ° C. for 20 hours.
- the obtained temporary fired body was pulverized and molded under the conditions shown in Table 1 (presence / absence of binder, molding method).
- the forming method A means CIP (cold isostatic pressing)
- the forming method B means uniaxial press.
- the obtained molded body was subjected to main firing at 1350 ° C. for 20 hours to obtain a sintered body.
- the obtained sintered body was cut, and a ring-shaped magnetic permeability evaluation sample having an outer diameter of 11 mm, an inner diameter of 6 mm, and a thickness of 2 mm, and a square shape having a length of 55 mm, a width of 14 mm, and a thickness of 4 mm.
- a sample for evaluating the specific resistance was obtained.
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Abstract
This ferrite sintered body includes 48-49 mol% Fe2O3, 15-17 mol% NiO, and 35-37 mol% ZnO. The C content is 0.003 mass% or less, the S content is 0.015 mass% or less, and the total amount of Fe2O3, NiO, and ZnO is 99.8 mol% or more.
Description
本発明は、フェライト焼結体、及びフェライトコアに関する。
The present invention relates to a ferrite sintered body and a ferrite core.
フェライト焼結体は、インダクタ、電源用トランス、電磁フィルタ等の電子部品において広範囲に使用されている。これらの電子部品においてコア（磁心）を形成するフェライト焼結体は、フェライトコアと呼ばれている（特許文献１及び２を参照）。
Ferrite sintered bodies are widely used in electronic parts such as inductors, power transformers, and electromagnetic filters. A ferrite sintered body forming a core (magnetic core) in these electronic components is called a ferrite core (see Patent Documents 1 and 2).
インダクタは高い精度が求められるセンシング機器におけるＬＣ共振回路に使用される。しかしながら、従来のフェライトコアを用いたインダクタでは、外気温の変動に伴ってフェライトコアの磁気特性も変動してしまうため、広い温度領域で精度を保つことが困難であった。また、種々の応用分野でフェライト表面は絶縁性を有する必要があり、比抵抗は１×１０９Ω・ｃｍ以上であることが必要とされるが、従来のフェライトコアは比抵抗が低く、そのまま使用することが困難であった。例えば、インダクタにおいてフェライト表面に導体層を形成する場合、下地として絶縁層を設けるなどの絶縁処理が必要とされていた。
An inductor is used for an LC resonance circuit in a sensing device that requires high accuracy. However, in a conventional inductor using a ferrite core, the magnetic characteristics of the ferrite core also vary with changes in the outside air temperature, so it is difficult to maintain accuracy over a wide temperature range. Further, in various application fields, the ferrite surface needs to have an insulating property, and the specific resistance is required to be 1 × 10 9 Ω · cm or more. It was difficult to use. For example, when a conductor layer is formed on a ferrite surface in an inductor, an insulation process such as providing an insulating layer as a base is required.
本発明は、上述の問題点に鑑み、広い温度領域で透磁率の変動が小さく、比抵抗の大きいフェライト焼結体及びフェライトコアを提供することを目的とする。
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a ferrite sintered body and a ferrite core that have a small variation in magnetic permeability and a large specific resistance in a wide temperature range.
本発明のフェライト焼結体は、４８～４９ｍｏｌ％のＦｅ２Ｏ３、１５～１７ｍｏｌ％のＮｉＯ、３５～３７ｍｏｌ％のＺｎＯを含み、Ｃの含有量が０．００３質量％以下であり、Ｓの含有量が０．０１５質量％以下であり、Ｆｅ２Ｏ３、ＮｉＯ、及びＺｎＯの合計量が９９．８ｍｏｌ％以上である。
The ferrite sintered body of the present invention contains 48 to 49 mol% Fe 2 O 3 , 15 to 17 mol% NiO, and 35 to 37 mol% ZnO, and has a C content of 0.003 mass% or less, and S Is 0.015 mass% or less, and the total amount of Fe 2 O 3 , NiO, and ZnO is 99.8 mol% or more.
また、本発明のフェライトコアは、４８～４９ｍｏｌ％のＦｅ２Ｏ３、１５～１７ｍｏｌ％のＮｉＯ、３５～３７ｍｏｌ％のＺｎＯを含み、Ｃの含有量が０．００３質量％以下であり、Ｓの含有量が０．０１５質量％以下であり、Ｆｅ２Ｏ３、ＮｉＯ、及びＺｎＯの合計量が９９．８ｍｏｌ％以上である。
The ferrite core of the present invention contains 48 to 49 mol% Fe 2 O 3 , 15 to 17 mol% NiO, and 35 to 37 mol% ZnO, and has a C content of 0.003% by mass or less. Is 0.015 mass% or less, and the total amount of Fe 2 O 3 , NiO, and ZnO is 99.8 mol% or more.
本発明によれば、広い温度範囲で透磁率の変動が小さく、比抵抗の大きいフェライト焼結体及びフェライトコアを提供することができる。
According to the present invention, it is possible to provide a ferrite sintered body and a ferrite core that have a small variation in magnetic permeability over a wide temperature range and a large specific resistance.
＜フェライト焼結体＞
本実施形態のフェライト焼結体は、４８～４９ｍｏｌ％のＦｅ２Ｏ３、１５～１７ｍｏｌ％のＮｉＯ、３５～３７ｍｏｌ％のＺｎＯを含み、Ｃの含有量は０．００３質量％以下であり、Ｓの含有量は０．０１５質量％以下であり、Ｆｅ２Ｏ３、ＮｉＯ、及びＺｎＯの合計量が９９．８ｍｏｌ％以上である。このようなフェライト焼結体は、広い温度領域での透磁率の変動が小さく、比抵抗が大きい。 <Ferrite sintered body>
The ferrite sintered body of the present embodiment includes 48 to 49 mol% Fe 2 O 3 , 15 to 17 mol% NiO, and 35 to 37 mol% ZnO, and the content of C is 0.003 mass% or less, The S content is 0.015% by mass or less, and the total amount of Fe 2 O 3 , NiO, and ZnO is 99.8 mol% or more. Such a ferrite sintered body has a small variation in magnetic permeability over a wide temperature range and a large specific resistance.
本実施形態のフェライト焼結体は、４８～４９ｍｏｌ％のＦｅ２Ｏ３、１５～１７ｍｏｌ％のＮｉＯ、３５～３７ｍｏｌ％のＺｎＯを含み、Ｃの含有量は０．００３質量％以下であり、Ｓの含有量は０．０１５質量％以下であり、Ｆｅ２Ｏ３、ＮｉＯ、及びＺｎＯの合計量が９９．８ｍｏｌ％以上である。このようなフェライト焼結体は、広い温度領域での透磁率の変動が小さく、比抵抗が大きい。 <Ferrite sintered body>
The ferrite sintered body of the present embodiment includes 48 to 49 mol% Fe 2 O 3 , 15 to 17 mol% NiO, and 35 to 37 mol% ZnO, and the content of C is 0.003 mass% or less, The S content is 0.015% by mass or less, and the total amount of Fe 2 O 3 , NiO, and ZnO is 99.8 mol% or more. Such a ferrite sintered body has a small variation in magnetic permeability over a wide temperature range and a large specific resistance.
上記フェライト焼結体において、Ｆｅ２Ｏ３、ＮｉＯ、及びＺｎＯの合計量が９９．８ｍｏｌ％以上である。上記合計量は、９９．９ｍｏｌ％以上であると好ましい。また、上記フェライト焼結体において、Ｃの含有量は、０．００３質量％以下である。上記フェライト焼結体において、Ｃの含有量が０．００１～０．００２質量％であると好ましく、Ｃを実質的に含まないことも可能である。さらに、上記フェライト焼結体において、Ｓの含有量は、０．０１５質量％以下である。上記フェライト焼結体において、Ｓの含有量が０．００５～０．０１０質量％であると好ましく、Ｓを実質的に含まないことも可能である。ここで、本明細書において、実質的に含まないとは、燃焼法による測定における検出限界値未満であることをいう。また、本実施形態のフェライト焼結体は、Ｆｅ２Ｏ３、ＮｉＯ、及びＺｎＯ以外の成分を実質的に含まなくてもよい。
In the ferrite sintered body, the total amount of Fe 2 O 3 , NiO, and ZnO is 99.8 mol% or more. The total amount is preferably 99.9 mol% or more. In the ferrite sintered body, the content of C is 0.003% by mass or less. In the ferrite sintered body, the C content is preferably 0.001 to 0.002% by mass, and it is possible to substantially not contain C. Furthermore, in the ferrite sintered body, the content of S is 0.015% by mass or less. In the ferrite sintered body, the content of S is preferably 0.005 to 0.010 mass%, and S can be substantially not included. Here, in the present specification, “substantially not contained” means that it is less than the detection limit value in the measurement by the combustion method. Further, the ferrite sintered body of the present embodiment may not substantially contain components other than Fe 2 O 3 , NiO, and ZnO.
上記フェライト焼結体は、－２０℃～１２０℃での透磁率（比透磁率）の温度係数が２５ｐｐｍ／Ｋ以下であると好ましく、２０ｐｐｍ／Ｋ以下であるとより好ましく、１０ｐｐｍ／Ｋ以下であるとさらに好ましい。－２０℃～１２０℃での透磁率の温度係数が上記範囲であると、フェライト焼結体を高い精度が求められるセンシング機器で用いた際に外気温の変動の影響を受けにくく、広い温度領域で高精度なセンシング性能が得られる。ここで、透磁率の温度係数とは、ある温度領域での透磁率の最大値と最小値の差を温度変化で割ったものをいう。また、透磁率は例えば、インピーダンスアナライザにより、周波数１ＭＨｚで測定した値を言う。透磁率（比透磁率）の温度係数は５ｐｐｍ／Ｋ以下であることもでき、３ｐｐｍ／Ｋ以下であることもできる。
The ferrite sintered body preferably has a temperature coefficient of permeability (relative permeability) at −20 ° C. to 120 ° C. of 25 ppm / K or less, more preferably 20 ppm / K or less, and 10 ppm / K or less. More preferably. When the temperature coefficient of permeability at −20 ° C. to 120 ° C. is in the above range, the ferrite sintered body is not easily affected by fluctuations in the outside air temperature when used in sensing devices that require high accuracy, and has a wide temperature range. High-precision sensing performance can be obtained. Here, the temperature coefficient of the permeability means a value obtained by dividing the difference between the maximum value and the minimum value of the permeability in a certain temperature region by the temperature change. Further, the magnetic permeability is a value measured at a frequency of 1 MHz with an impedance analyzer, for example. The temperature coefficient of magnetic permeability (relative magnetic permeability) can be 5 ppm / K or less, and can also be 3 ppm / K or less.
上記フェライト焼結体の電気抵抗値（比抵抗）は１×１０９Ω・ｃｍ以上であると好ましく、１×１０１０Ω・ｃｍ以上であるとより好ましい。フェライト焼結体の電気抵抗値（比抵抗）が上記範囲であると、使用時に絶縁処理を必要としない。
The ferrite sintered body has an electric resistance value (specific resistance) of preferably 1 × 10 9 Ω · cm or more, and more preferably 1 × 10 10 Ω · cm or more. When the electric resistance value (specific resistance) of the ferrite sintered body is in the above range, an insulation treatment is not required during use.
上記フェライト焼結体の焼結密度は、５．３～５．５ｇ／ｃｍ３であることが好ましい。このような密度であると、ボイドの発生率が小さく、外因（温度、湿度、圧力）による透磁率の変動が小となる傾向があるため好ましい。
The sintered density of the ferrite sintered body is preferably 5.3 to 5.5 g / cm 3 . Such a density is preferable because the void generation rate is small and the variation in magnetic permeability due to external factors (temperature, humidity, pressure) tends to be small.
本実施形態のフェライト焼結体は、不可避不純物として、Ｆｅ単体、又はＣｄ、Ｃｏ、Ｃｕ、Ｐｂ、Ｓｉ、若しくはＭｎの酸化物を含んでいてもよい。フェライト焼結体における不可避不純物の合計量は、３００ｍｏｌｐｐｍ未満であることが好ましく、これらの不純物を実質的に含まないことが好ましい。
The ferrite sintered body of the present embodiment may contain Fe alone or an oxide of Cd, Co, Cu, Pb, Si, or Mn as an inevitable impurity. The total amount of inevitable impurities in the ferrite sintered body is preferably less than 300 mol ppm, and it is preferable that these impurities are not substantially contained.
＜フェライト焼結体の製造方法＞
本実施形態におけるフェライト焼結体の製造方法について説明する。
まず、Ｆｅ２Ｏ３原料、ＮｉＯ原料、及びＺｎＯ原料を、フェライト焼結体におけるＦｅ２Ｏ３、ＮｉＯ、及びＺｎＯの含有量が上記範囲となるような組成比で混合して原料粉体を得る。Ｆｅ２Ｏ３原料としては、Ｆｅ２Ｏ３粉末、Ｆｅ３Ｏ４粉末等が挙げられる。ＮｉＯ原料としては、ＮｉＯ粉末が挙げられる。ＺｎＯ原料としては、ＺｎＯ粉末が挙げられる。Ｆｅ２Ｏ３原料、ＮｉＯ原料、及びＺｎＯ原料の平均粒径は、０．１～１０μｍであることが好ましい。また、Ｆｅ２Ｏ３原料、ＮｉＯ原料、及びＺｎＯ原料の純度としては、金属不純物が１００～１０００質量ｐｐｍであることが好ましい。上記不純物としては、Ｃｄ、Ｃｏ、Ｃｕ、Ｐｂ、Ｓｉ、若しくはＭｎが挙げられる。混合の方法は、湿式であっても乾式であってもよいが、不純物の残留することを防げる観点から、乾式であることが好ましい。 <Method for producing ferrite sintered body>
The manufacturing method of the ferrite sintered compact in this embodiment is demonstrated.
First, the Fe 2 O 3 raw material, the NiO raw material, and the ZnO raw material are mixed at a composition ratio such that the content of Fe 2 O 3 , NiO, and ZnO in the ferrite sintered body is in the above range to obtain a raw material powder. obtain. Examples of the Fe 2 O 3 raw material include Fe 2 O 3 powder and Fe 3 O 4 powder. Examples of the NiO raw material include NiO powder. Examples of the ZnO raw material include ZnO powder. The average particle diameter of the Fe 2 O 3 raw material, NiO raw material, and ZnO raw material is preferably 0.1 to 10 μm. The purity of the Fe 2 O 3 raw material, NiO raw material, and ZnO raw material is preferably 100 to 1000 ppm by mass of metal impurities. Examples of the impurities include Cd, Co, Cu, Pb, Si, or Mn. The mixing method may be wet or dry, but is preferably dry from the viewpoint of preventing impurities from remaining.
本実施形態におけるフェライト焼結体の製造方法について説明する。
まず、Ｆｅ２Ｏ３原料、ＮｉＯ原料、及びＺｎＯ原料を、フェライト焼結体におけるＦｅ２Ｏ３、ＮｉＯ、及びＺｎＯの含有量が上記範囲となるような組成比で混合して原料粉体を得る。Ｆｅ２Ｏ３原料としては、Ｆｅ２Ｏ３粉末、Ｆｅ３Ｏ４粉末等が挙げられる。ＮｉＯ原料としては、ＮｉＯ粉末が挙げられる。ＺｎＯ原料としては、ＺｎＯ粉末が挙げられる。Ｆｅ２Ｏ３原料、ＮｉＯ原料、及びＺｎＯ原料の平均粒径は、０．１～１０μｍであることが好ましい。また、Ｆｅ２Ｏ３原料、ＮｉＯ原料、及びＺｎＯ原料の純度としては、金属不純物が１００～１０００質量ｐｐｍであることが好ましい。上記不純物としては、Ｃｄ、Ｃｏ、Ｃｕ、Ｐｂ、Ｓｉ、若しくはＭｎが挙げられる。混合の方法は、湿式であっても乾式であってもよいが、不純物の残留することを防げる観点から、乾式であることが好ましい。 <Method for producing ferrite sintered body>
The manufacturing method of the ferrite sintered compact in this embodiment is demonstrated.
First, the Fe 2 O 3 raw material, the NiO raw material, and the ZnO raw material are mixed at a composition ratio such that the content of Fe 2 O 3 , NiO, and ZnO in the ferrite sintered body is in the above range to obtain a raw material powder. obtain. Examples of the Fe 2 O 3 raw material include Fe 2 O 3 powder and Fe 3 O 4 powder. Examples of the NiO raw material include NiO powder. Examples of the ZnO raw material include ZnO powder. The average particle diameter of the Fe 2 O 3 raw material, NiO raw material, and ZnO raw material is preferably 0.1 to 10 μm. The purity of the Fe 2 O 3 raw material, NiO raw material, and ZnO raw material is preferably 100 to 1000 ppm by mass of metal impurities. Examples of the impurities include Cd, Co, Cu, Pb, Si, or Mn. The mixing method may be wet or dry, but is preferably dry from the viewpoint of preventing impurities from remaining.
次に、上記原料粉体を仮焼成して仮焼成物を得る。仮焼成は、空気中で仮焼成温度８００～１２００℃、仮焼成時間２～５０時間の条件で行うことが好ましい。仮焼成後、仮焼成物を粉砕する。次いで、粉砕された仮焼成物を成形し、成形体を得る。成形方法としては、特に制限されないが、一軸プレス、静水圧成形等が挙げられる。成形時の圧力としては５０～５００ＭＰａであると好ましい。仮焼成時の雰囲気は酸素量が１～５０体積％である（Ｎ２＋Ｏ２）混合ガスでもよい。
Next, the raw material powder is temporarily fired to obtain a temporarily fired product. The calcination is preferably performed in air under conditions of a calcination temperature of 800 to 1200 ° C. and a calcination time of 2 to 50 hours. After the calcination, the calcination product is pulverized. Next, the ground calcined product is molded to obtain a molded body. Although it does not restrict | limit especially as a shaping | molding method, Uniaxial press, an isostatic pressing, etc. are mentioned. The pressure during molding is preferably 50 to 500 MPa. The atmosphere during pre-firing may be a (N 2 + O 2 ) mixed gas having an oxygen content of 1 to 50% by volume.
ここで、成形体はバインダを含まないことが好ましい。成形体がバインダを実質的に含まない場合、後述の本焼成中に成形体中にボイドが発生することを抑制し、透磁率の温度係数をさらに向上させることができる。また、成形体がバインダを含まないことにより、フェライト焼結体におけるＣ及びＳの含有量を上記範囲とすることができる。また、成形体は、ＣｕＯを実質的に含まないほうが好ましい。ＣｕＯを実質的に含まない場合、本焼成中に成形体中にボイドが発生することを抑制し、透磁率の温度係数をさらに向上させることができる。
Here, it is preferable that the molded body does not contain a binder. When a molded object does not contain a binder substantially, it can suppress that a void generate | occur | produces in a molded object during the below-mentioned main baking, and can further improve the temperature coefficient of magnetic permeability. Moreover, when the compact does not contain a binder, the content of C and S in the ferrite sintered body can be within the above range. Moreover, it is preferable that a molded object does not contain CuO substantially. When CuO is not substantially contained, generation of voids in the molded body during the main firing can be suppressed, and the temperature coefficient of permeability can be further improved.
得られた成形体を本焼成してフェライト焼結体を得る。本焼成は、空気中で本焼成温度１０００～１５００℃、本焼成時間２～５０時間の条件で行うことが好ましい。本焼成の雰囲気は酸素量が１～５０体積％である（Ｎ２＋Ｏ２）混合ガスでもよい。場合によってはＨ２を導入してもよい。
The obtained molded body is subjected to main firing to obtain a ferrite sintered body. The main calcination is preferably performed in air under conditions of a main calcination temperature of 1000 to 1500 ° C. and a main calcination time of 2 to 50 hours. The atmosphere for the main firing may be a (N 2 + O 2 ) mixed gas having an oxygen amount of 1 to 50% by volume. In some cases, H 2 may be introduced.
得られた焼結体を切削又は研磨して、所定の形状を有するフェライトコアを得る。フェライトコアの形状としては、特に限定されないが、棒状、板状等とすることができる。
The obtained sintered body is cut or polished to obtain a ferrite core having a predetermined shape. Although it does not specifically limit as a shape of a ferrite core, It can be set as rod shape, plate shape, etc.
本実施形態のフェライトコアは、広い温度範囲で透磁率の変動が小さく、比抵抗が小さい。そのため、高い精度が求められるセンシング機器におけるＬＣ共振回路に、絶縁処理等を行うことなく好適に使用することができる。
The ferrite core of this embodiment has a small variation in permeability and a low specific resistance over a wide temperature range. Therefore, it can be suitably used for an LC resonance circuit in a sensing device that requires high accuracy without performing insulation treatment or the like.
純度９９．９質量％、平均粒径０．５μｍのＦｅ２Ｏ３粉末、ＮｉＯ粉末、ＺｎＯ粉末及びＣｕＯ粉末を表１に示す組成比で混合し、原料粉体を得た。原料粉体を１１００℃で２０時間、仮焼成した。次いで得られた仮焼成体を粉砕し、表１に示す条件（バインダの有無、成形方法）で成形した。ここで、成形方法Ａは、ＣＩＰ（冷間等方圧加圧法）を意味し、成形方法Ｂは、一軸プレスを意味する。得られた成形体を１３５０℃で２０時間、本焼成し、焼結体を得た。得られた焼結体を切削し、外径：１１ｍｍ、内径：６ｍｍ、厚さ：２ｍｍのリング状の透磁率評価用サンプルと、長さ：５５ｍｍ、幅：１４ｍｍ、厚さ：４ｍｍの角状の比抵抗評価用のサンプルを得た。
Fe 2 O 3 powder having a purity of 99.9% by mass and an average particle size of 0.5 μm, NiO powder, ZnO powder and CuO powder were mixed at the composition ratio shown in Table 1 to obtain a raw material powder. The raw material powder was calcined at 1100 ° C. for 20 hours. Next, the obtained temporary fired body was pulverized and molded under the conditions shown in Table 1 (presence / absence of binder, molding method). Here, the forming method A means CIP (cold isostatic pressing), and the forming method B means uniaxial press. The obtained molded body was subjected to main firing at 1350 ° C. for 20 hours to obtain a sintered body. The obtained sintered body was cut, and a ring-shaped magnetic permeability evaluation sample having an outer diameter of 11 mm, an inner diameter of 6 mm, and a thickness of 2 mm, and a square shape having a length of 55 mm, a width of 14 mm, and a thickness of 4 mm. A sample for evaluating the specific resistance was obtained.
＜測定方法＞
上記透磁率評価用サンプルについて、燃焼法により、Ｃ及びＳの含有量を測定した。また、金属顕微鏡により、評価用サンプルの表面における５μｍ以上の大きさのボイドの発生量（１ｃｍ２当たり）を測定した。さらに、インピーダンスアナライザを用いて、周波数１ＭＨｚで、室温での透磁率及び－２０～１２０℃の温度領域での透磁率の温度係数を測定した。測定結果を表１に示す。 <Measurement method>
About the said sample for magnetic permeability evaluation, content of C and S was measured by the combustion method. Moreover, the generation amount (per 1 cm 2 ) of voids having a size of 5 μm or more on the surface of the sample for evaluation was measured with a metal microscope. Further, using an impedance analyzer, the magnetic permeability at room temperature and the temperature coefficient of magnetic permeability in the temperature range of −20 to 120 ° C. were measured at a frequency of 1 MHz. The measurement results are shown in Table 1.
上記透磁率評価用サンプルについて、燃焼法により、Ｃ及びＳの含有量を測定した。また、金属顕微鏡により、評価用サンプルの表面における５μｍ以上の大きさのボイドの発生量（１ｃｍ２当たり）を測定した。さらに、インピーダンスアナライザを用いて、周波数１ＭＨｚで、室温での透磁率及び－２０～１２０℃の温度領域での透磁率の温度係数を測定した。測定結果を表１に示す。 <Measurement method>
About the said sample for magnetic permeability evaluation, content of C and S was measured by the combustion method. Moreover, the generation amount (per 1 cm 2 ) of voids having a size of 5 μm or more on the surface of the sample for evaluation was measured with a metal microscope. Further, using an impedance analyzer, the magnetic permeability at room temperature and the temperature coefficient of magnetic permeability in the temperature range of −20 to 120 ° C. were measured at a frequency of 1 MHz. The measurement results are shown in Table 1.
また、上記比抵抗評価用サンプルについて、絶縁抵抗計を用いて絶縁抵抗と電極面積と電極間距離とを求め、比抵抗を算出した。測定結果を表１に示す。
Further, with respect to the specific resistance evaluation sample, an insulation resistance, an electrode area, and a distance between the electrodes were obtained using an insulation resistance meter, and a specific resistance was calculated. The measurement results are shown in Table 1.
Claims (2)
- ４８～４９ｍｏｌ％のＦｅ２Ｏ３、１５～１７ｍｏｌ％のＮｉＯ、及び３５～３７ｍｏｌ％のＺｎＯを含むフェライト焼結体であって、
Ｃの含有量は０．００３質量％以下であり、Ｓの含有量は０．０１５質量％以下であり、
Ｆｅ２Ｏ３、ＮｉＯ、及びＺｎＯの合計量が９９．８ｍｏｌ％以上である、フェライト焼結体。 A ferrite sintered body containing 48 to 49 mol% Fe 2 O 3 , 15 to 17 mol% NiO, and 35 to 37 mol% ZnO,
The content of C is 0.003% by mass or less, the content of S is 0.015% by mass or less,
Fe 2 O 3, NiO, and the total amount of ZnO is more than 99.8 mol%, the ferrite sintered body. - ４８～４９ｍｏｌ％のＦｅ２Ｏ３、１５～１７ｍｏｌ％のＮｉＯ、及び３５～３７ｍｏｌ％のＺｎＯを含むフェライトコアであって、
Ｃの含有量は０．００３質量％以下であり、Ｓの含有量は０．０１５質量％以下であり、
Ｆｅ２Ｏ３、ＮｉＯ、及びＺｎＯの合計量が９９．８ｍｏｌ％以上である、フェライトコア。 A ferrite core comprising 48-49 mol% Fe 2 O 3 , 15-17 mol% NiO, and 35-37 mol% ZnO,
The content of C is 0.003% by mass or less, the content of S is 0.015% by mass or less,
Fe 2 O 3, NiO, and the total amount of ZnO is 99.8 mol% or more, the ferrite core.
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|---|---|---|---|---|
| JPH07307212A (en) * | 1994-03-16 | 1995-11-21 | Hitachi Ferrite Ltd | Ni ferrite sintered body and power source core |
| JPH1135369A (en) * | 1997-07-17 | 1999-02-09 | Tokin Corp | Thermal shock resistant ferrite |
| JP2010143821A (en) * | 2010-01-14 | 2010-07-01 | Tdk Corp | Ferrite composition and electronic component |
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| JPH07307212A (en) * | 1994-03-16 | 1995-11-21 | Hitachi Ferrite Ltd | Ni ferrite sintered body and power source core |
| JPH1135369A (en) * | 1997-07-17 | 1999-02-09 | Tokin Corp | Thermal shock resistant ferrite |
| JP2010143821A (en) * | 2010-01-14 | 2010-07-01 | Tdk Corp | Ferrite composition and electronic component |
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