JP3366707B2 - Mn-Zn ferrite - Google Patents
Mn-Zn ferriteInfo
- Publication number
- JP3366707B2 JP3366707B2 JP28663393A JP28663393A JP3366707B2 JP 3366707 B2 JP3366707 B2 JP 3366707B2 JP 28663393 A JP28663393 A JP 28663393A JP 28663393 A JP28663393 A JP 28663393A JP 3366707 B2 JP3366707 B2 JP 3366707B2
- Authority
- JP
- Japan
- Prior art keywords
- oxide
- mol
- loss
- terms
- ferrite
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- 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
- H01F1/342—Oxides
- H01F1/344—Ferrites, e.g. having a cubic spinel structure (X2+O)(Y23+O3), e.g. magnetite Fe3O4
Landscapes
- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Compounds Of Iron (AREA)
- Magnetic Ceramics (AREA)
- Soft Magnetic Materials (AREA)
Description
【発明の詳細な説明】
【0001】
【産業上の利用分野】この発明は、スイッチング電源用
トランス等の使途に供して好適な、高抵抗でしかも電力
損失の少ないMn−Zn系フェライトに関するものである。
【0002】
【従来の技術】Mn−Zn系フェライトは、各種通信機器、
電源等におけるコイル、トランス材料として広く用いら
れ、特に約100 kHz 以上の高周波領域で動作するスイッ
チング電源用トランス材料として電子機器の小型化に大
きく貢献している。かかるスイッチング電源のトランス
材料として使用されるMn−Zn系フェライトには、高飽和
磁束密度、高透磁率及び低損失といった特性が要求され
るが、とりわけ高周波領域において低損失であることが
重要とされる。
【0003】このため、発明者らは、先に特開平3−2
54103号公報において、副成分としてSiO2、CaO 及
びNb2O5 に加えて、TiO2とSb2O3 のいずれか一方を添加
することを提案し、得られたフェライトの電力損失とし
ては240 〜300 mW/cm3 と、現在における最高水準を実
現している。
【0004】
【発明が解決しようとする課題】しかしながら、Mn−Zn
系フェライトには、より一層の電源の小型化のために、
さらに電力損失を低減することが期待されている。
【0005】この発明は、特開平3−254103号公
報において達成した100 kHz ,0.2Tにおける電力損失
の最高水準である240 〜300 mW/cm3 をさらに低減する
ことのできるMn−Zn系フェライトを提案することを目的
とする。
【0006】
【課題を解決するための手段】上記課題を解決するこの
発明は、
Fe2O3 :51.5〜54.5 mol%、
MnO :30〜40 mol%及び
ZnO :6〜18 mol%
を基本成分とし、副成分として
酸化けい素 :SiO2換算で 0.005 〜0.04wt%、
酸化カルシウム:CaO 換算で 0.02〜0.2 wt%、
酸化ニオブ :Nb2O5 換算で0.01〜0.08wt%、
酸化チタン :TiO2換算で 0.05〜0.4 wt%及び
酸化アンチモン:Sb2O3 換算で0.005 〜0.08wt%
を含有するMn−Zn系フェライトである。
【0007】
【作用】まず、この発明において基本成分の組成割合を
Fe2O3 :51.5〜54.5 mol%、MnO :30〜40 mol%及びZn
O :6〜18 mol%の範囲に限定した理由について説明す
る。
【0008】スイッチング電源用トランスの動作温度
は、通常60〜70℃である。したがって、この温度範囲で
電力損失が小さく、しかも室温から動作温度を超える80
〜120℃程度までの温度域にわたって、電力損失が負の
温度依存性を持つことが望ましい。この観点からFe2O3,
MnO及びZnO の好適組成割合を検討した結果、上記の各
範囲が得られたのである。
【0009】次にこの発明では、上記の基本成分中に副
成分として酸化けい素、酸化カルシウム、酸化ニオブ、
酸化チタン及び酸化アンチモンを複合含有させる。これ
ら副成分の含有量範囲の限定理由は以下のとおりであ
る。
【0010】酸化けい素:SiO2換算で0.005 〜0.04wt%
酸化けい素は、酸化カルシウムとの共存によって粒界の
比抵抗を高め、渦電流損の低減に有効に寄与するが、そ
の含有量が0.005 wt%に満たないと添加効果に乏しく、
一方0.04wt%を超えると焼成時に異常粒成長が発生し易
く、特性が不安定になるので、0.005 〜0.04wt%の範囲
に限定した。
【0011】酸化カルシウム:CaO 換算で0.02〜0.2 wt
%
酸化カルシウムは、酸化けい素との共存下で効果的に粒
界抵抗を高め、もって低損失をもたらす有用成分である
が、その含有量が0.02wt%に満たないと粒界抵抗の向上
効果に乏しく、一方0.2 wt%を超えると逆に損失の増大
を来すので、0.02〜0.2 wt%の範囲で添加するものとし
た。
【0012】酸化ニオブ:Nb2O5 換算で0.01〜0.08wt%
酸化ニオブ(主にNb2O5 )は、高周波領域における損失
の低減に寄与する。酸化ニオブの添加によって損失が改
善される理由は、まだ十分に解明されたわけではない
が、酸化ニオブは、酸化けい素及び酸化カルシウムとの
複合含有によって成形される高抵抗の粒界相を変質さ
せ、電気抵抗を増加させると共に、異質の相が粒界に存
在することによる磁気的な悪影響を緩和する働きがある
ためと考えられる。しかしながら、その含有量が0.01wt
%に満たないと効果に乏しく、一方0.08wt%を超えて含
有させると焼結時に異常粒成長を起こし易くなるので、
0.01〜0.08wt%の範囲に限定した。
【0013】酸化チタン:TiO2換算で0.05〜0.4 wt%
酸化チタン(主にTiO2) は、フェライトコア焼結時の冷
却過程での粒界の再酸化を促進して、コアの電気抵抗を
高め、高周波領域における渦電流損を低減する効果があ
り、この効果は酸化アンチモンとの複合含有によりさら
に大きくなる。しかしながら、含有量が0.005 wt%に満
たないとその添加効果に乏しく、一方、0.4 wt%を超え
ると逆に損失の増加を招き、最悪の場合、焼結時に異常
粒成長するので、0.05〜0.4 wt%の範囲に限定した。
【0014】酸化アンチモン:Sb2O3 換算で0.005 〜0.
08wt%
酸化アンチモン(主にSb2O3)は、酸化カルシウムとの共
存下において、異常粒成長を発生させることなく焼結性
を著しく改善し、焼結密度を増大させる。これにより、
飽和磁束密度、透磁率等に好影響を与えたものと考えら
れる。また、特に酸化チタンとの複合含有によって電気
抵抗を増加させ、これが高周波領域における損失のさら
なる低減に効果的に寄与している。しかし、含有量が0.
005 wt%に満たないと焼結性の改善効果に乏しく、一方
0.08wt%を超えて含有させるとかえって損失の増加を招
くので、0.005 〜0.08wt%の範囲に限定した。
【0015】以上述べたとおり、この発明は、副成分と
して酸化けい素、酸化カルシウム、酸化ニオブ、酸化チ
タン及び酸化アンチモンを複合含有させて、粒界に均一
分散させることにより、上記の目的を達成したものであ
る。
【0016】この発明のフェライトを製造するには、常
法に従って処理を施せば良い。すなわち、フェライトの
最終組成として、例えば、酸化鉄をFe2O3 換算で51.5〜
54.5mol%、酸化マンガンをMnO 換算で30〜40 mol%、
酸化亜鉛をZnO 換算で6〜18mol%の割合で含有するよ
うに混合し、次いで副成分として酸化けい素(SiO2換
算) を0.005 〜0.04wt%、酸化カルシウム(CaO 換算)
を0.02〜0.2 wt%、酸化ニオブ(Na2O5 換算)を0.01〜
0.08wt%、酸化チタン(TiO2換算) を0.05〜0.4wt%及
び酸化アンチモン(Sb2O3 換算)を0.005 〜0.08wt%含
有するように添加したものを原料とする。ただし、副成
分の添加時期は、後述する仮焼の後であっても差し支え
ない。
【0017】この原料を800 ℃以上の温度で仮焼し、次
いで微粉砕後、1150℃以上の高温にて酸素濃度を制御し
た窒素ガス中で焼成する。
【0018】なお、酸化鉄の原料としては、Fe2O3 だけ
でなく、FeO やFe3O4 、更には焼成によりFe2O3 に変わ
ることのできる化合物、例えば水酸化鉄、しゅう酸鉄な
どを使用することができる。また、酸化マンガン原料と
しては、MnO のみならず、MnO2、Mn3O4 、更には焼成に
よりMnO に変わることのできる化合物、例えば炭酸マン
ガン、しゅう酸マンガンなどを使用することができる。
さらに、酸化亜鉛原料としては、ZnO のみに限らず、焼
成によりZnO に変わることのできる化合物、例えば炭酸
亜鉛、しゅう酸亜鉛などを使用することができる。
【0019】同様に、Si、Ca、Nb、Ti及びSbの各酸化物
の添加は、酸化物の形でも良く、製造工程中の加熱によ
り酸化物に変化する、金属又は炭酸塩、しゅう酸塩等の
化合物によっても良い。
【0020】
【実施例】最終組成として、Fe2O3 :53.0 mol%、MnO
:35.0 mol%、ZnO :12.0 mol%となる基本組成の原
料を混合した後、大気中にて900 ℃、3時間の仮焼を施
した。この仮焼粉に対し、表1及び表2に示す最終組成
になる割合で、SiO2、CaO (CaCO3 を使用)、Nb2O5 、
TiO2及びSb2O3 を添加配合し、同時に湿式ボールミルで
粉砕した。次いで粉砕粉にバインダーとしてPVA を添加
して造粒した後、外径36mm、内径24mm、高さ12mmのリン
グ状試料に成形した。この成形体を、酸素濃度を制御し
た窒素雰囲気中で1320℃で3時間焼成した。
【0021】かくして得られた焼結コアの密度をアルキ
メデス法により測定した。また、直流比抵抗を4端子法
により測定した。さらに、周波数:100 kHz 、最大磁束
密度:0.2 T、温度:80℃における電子損失を交流B−
Hループトレーサーにて測定した。測定結果を表1及び
表2に併記する。なお、焼結密度は論理密度5.1 g/cm
3 に対する百分率で示した。
【0022】
【表1】【0023】
【表2】【0024】表1及び表2にはそれぞれ実施例及び比較
例を示しているが、これらの結果から明らかなように、
この発明に従い副成分として、酸化けい素、酸化カルシ
ウム、酸化ニオブ、酸化チタン及び酸化アンチモンを複
合含有させたものはいずれも、酸化チタンか酸化アンチ
モンのどちらか一方が欠けたものより、直流比抵抗は増
加し、電力損失の低減を達成している。
【0025】
【発明の効果】かくしてこの発明によれば、駆動周波数
が100 kHz 程度のスイッチング電源用トランス材料とし
て高磁場での電力損失が従来の材料と比較して格段に小
さい、高抵抗でかつ低損失のMn−Zn系フェライトを得る
ことができる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-resistance and low-power-loss Mn-Zn ferrite suitable for use in a transformer for a switching power supply or the like. is there. [0002] Mn-Zn ferrite is widely used in various communication devices,
It is widely used as a material for coils and transformers in power supplies, etc., and has greatly contributed to the miniaturization of electronic devices, especially as a switching power supply transformer material that operates in the high frequency range of about 100 kHz or higher. Mn-Zn ferrite used as a transformer material of such a switching power supply is required to have characteristics such as high saturation magnetic flux density, high magnetic permeability, and low loss. You. [0003] For this reason, the inventors have disclosed in Japanese Patent Laid-Open No.
No. 54103 proposes to add one of TiO 2 and Sb 2 O 3 in addition to SiO 2 , CaO and Nb 2 O 5 as subcomponents, and to obtain a power loss of 240% for the obtained ferrite. and ~300 mW / cm 3, has achieved the highest level in the current. [0004] However, Mn-Zn
In order to further reduce the size of the power supply,
It is expected that the power loss will be further reduced. The present invention relates to a Mn-Zn ferrite capable of further reducing the maximum power loss of 240 to 300 mW / cm 3 at 100 kHz and 0.2 T achieved in JP-A-3-254103. The purpose is to propose. SUMMARY OF THE INVENTION The present invention for solving the above-mentioned problems comprises Fe 2 O 3 : 51.5 to 54.5 mol%, MnO: 30 to 40 mol% and ZnO: 6 to 18 mol% as basic components. and then, silicon oxide as a subcomponent: SiO 2 converted at 0.005 ~0.04wt%, calcium oxide: CaO converted at 0.02 to 0.2 wt%, niobium oxide: 0.01~0.08wt% calculated as Nb 2 O 5, titanium oxide: TiO 2 converted at 0.05 to 0.4 wt% and antimony oxide: a Mn-Zn ferrite containing 0.005 ~0.08wt% by Sb 2 O 3 conversion. First, in the present invention, the composition ratio of the basic component is
Fe 2 O 3: 51.5~54.5 mol% , MnO: 30~40 mol% , and Zn
O: The reason for limiting the range to 6 to 18 mol% will be described. [0008] The operating temperature of a switching power supply transformer is usually 60 to 70 ° C. Therefore, power loss is small in this temperature range,
It is desirable that the power loss has a negative temperature dependence over a temperature range up to about 120 ° C. From this point of view, Fe 2 O 3 ,
As a result of studying the suitable composition ratio of MnO and ZnO, each of the above ranges was obtained. Next, in the present invention, silicon oxide, calcium oxide, niobium oxide,
A composite of titanium oxide and antimony oxide is contained. The reasons for limiting the content ranges of these subcomponents are as follows. Silicon oxide: 0.005 to 0.04% by weight in terms of SiO 2 Silicon oxide increases the specific resistance of grain boundaries by coexistence with calcium oxide, and effectively contributes to reduction of eddy current loss. If less than 0.005 wt%, the effect of addition is poor,
On the other hand, if the content exceeds 0.04% by weight, abnormal grain growth tends to occur during firing, and the characteristics become unstable. Therefore, the range is limited to the range of 0.005 to 0.04% by weight. Calcium oxide: 0.02-0.2 wt% in terms of CaO
% Calcium oxide is a useful component that effectively enhances grain boundary resistance in the presence of silicon oxide and thus reduces loss. However, if the content is less than 0.02 wt%, the effect of improving grain boundary resistance is improved. However, if the content exceeds 0.2 wt%, the loss will increase. Therefore, the content is added in the range of 0.02 to 0.2 wt%. Niobium oxide: 0.01 to 0.08 wt% in terms of Nb 2 O 5 Niobium oxide (mainly Nb 2 O 5 ) contributes to reduction of loss in a high frequency region. The reason why the loss is improved by the addition of niobium oxide has not yet been fully elucidated, but niobium oxide alters the high-resistance grain boundary phase formed by the complex content of silicon oxide and calcium oxide. This is considered to be due to the effect of increasing the electric resistance and alleviating the adverse magnetic effect caused by the presence of the foreign phase at the grain boundary. However, its content is 0.01wt
%, The effect is poor. On the other hand, if it exceeds 0.08 wt%, abnormal grain growth tends to occur during sintering.
It was limited to the range of 0.01 to 0.08 wt%. Titanium oxide: 0.05 to 0.4 wt% in terms of TiO 2 Titanium oxide (mainly TiO 2 ) promotes reoxidation of grain boundaries during the cooling process during sintering of the ferrite core, thereby increasing the electrical resistance of the core. This has the effect of increasing the eddy current loss in the high frequency range, and this effect is further enhanced by the complex content with antimony oxide. However, if the content is less than 0.005 wt%, the effect of the addition is poor. On the other hand, if the content exceeds 0.4 wt%, the loss increases, and in the worst case, abnormal grain growth occurs during sintering. Limited to the wt% range. Antimony oxide: 0.005 to 0.1 in terms of Sb 2 O 3
08 wt% antimony oxide (mainly Sb 2 O 3 ) significantly improves sinterability and increases sintering density without causing abnormal grain growth in the presence of calcium oxide. This allows
This is considered to have had a favorable effect on the saturation magnetic flux density, the magnetic permeability, and the like. In addition, the electric resistance is increased particularly by the composite content with titanium oxide, which effectively contributes to further reduction of the loss in a high frequency region. However, the content is 0.
If it is less than 005 wt%, the effect of improving sinterability is poor, while
If the content exceeds 0.08% by weight, the loss will be increased instead. Therefore, the content is limited to the range of 0.005 to 0.08% by weight. [0015] As described above, the present invention achieves the above object by mixing and uniformly dispersing silicon oxide, calcium oxide, niobium oxide, titanium oxide and antimony oxide as accessory components at grain boundaries. It was done. The ferrite of the present invention may be processed according to a conventional method. That is, the final composition of the ferrite, for example, iron oxide in terms of Fe 2 O 3 51.5~
54.5 mol%, manganese oxide is 30-40 mol% in terms of MnO,
Zinc oxide is mixed so as to contain 6 to 18 mol% in terms of ZnO, and then, as an auxiliary component, 0.005 to 0.04 wt% of silicon oxide (in terms of SiO 2 ) and calcium oxide (in terms of CaO).
The 0.02 to 0.2 wt%, 0.01 to niobium oxide (Na 2 O 5 equivalent)
0.08 wt%, a material obtained by adding titanium oxide (TiO 2 basis) of 0.05~0.4Wt% and antimony oxide (Sb 2 O 3 conversion) to contain 0.005 ~0.08wt% as a raw material. However, the addition time of the auxiliary component may be after calcination described later. This raw material is calcined at a temperature of 800 ° C. or more, then finely pulverized, and then calcined at a high temperature of 1150 ° C. or more in a nitrogen gas having a controlled oxygen concentration. The raw material of iron oxide is not only Fe 2 O 3, but also FeO, Fe 3 O 4 , and compounds that can be converted to Fe 2 O 3 by firing, such as iron hydroxide and iron oxalate. Etc. can be used. As the manganese oxide raw material, not only MnO but also MnO 2 , Mn 3 O 4 , and a compound that can be converted to MnO 2 by firing, such as manganese carbonate and manganese oxalate, can be used.
Further, as the zinc oxide raw material, not only ZnO but also a compound that can be converted to ZnO 2 by firing, such as zinc carbonate and zinc oxalate, can be used. Similarly, the addition of each of the oxides of Si, Ca, Nb, Ti and Sb may be in the form of an oxide, and may be changed to an oxide by heating during the manufacturing process. And the like. EXAMPLE The final composition was Fe 2 O 3 : 53.0 mol%, MnO
: 35.0 mol% and ZnO: 12.0 mol% after mixing, and then calcined in the air at 900 ° C for 3 hours. With respect to the calcined powder, SiO 2 , CaO (using CaCO 3 ), Nb 2 O 5 ,
TiO 2 and Sb 2 O 3 were added and blended, and simultaneously pulverized by a wet ball mill. Next, after adding PVA as a binder to the pulverized powder and granulating, it was formed into a ring-shaped sample having an outer diameter of 36 mm, an inner diameter of 24 mm, and a height of 12 mm. The molded body was fired at 1320 ° C. for 3 hours in a nitrogen atmosphere having a controlled oxygen concentration. The density of the sintered core thus obtained was measured by the Archimedes method. Further, the DC specific resistance was measured by a four-terminal method. Further, the electron loss at a frequency of 100 kHz, a maximum magnetic flux density of 0.2 T, and a temperature of 80 ° C.
It was measured with an H loop tracer. The measurement results are also shown in Tables 1 and 2. The sintering density was 5.1 g / cm.
It is shown as a percentage of 3 . [Table 1] [Table 2] Tables 1 and 2 show Examples and Comparative Examples, respectively. As apparent from these results,
In accordance with the present invention, any of the compounds containing silicon oxide, calcium oxide, niobium oxide, titanium oxide and antimony oxide as auxiliary components in accordance with the present invention has a higher DC specific resistance than one lacking either titanium oxide or antimony oxide. Have increased, and a reduction in power loss has been achieved. Thus, according to the present invention, as a transformer material for a switching power supply having a driving frequency of about 100 kHz, the power loss in a high magnetic field is remarkably smaller than that of a conventional material, and it has a high resistance and a high resistance. A low loss Mn-Zn ferrite can be obtained.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平5−267040(JP,A) (58)調査した分野(Int.Cl.7,DB名) H01F 1/12 - 1/375 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-267040 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) H01F 1/12-1/375
Claims (1)
Priority Applications (1)
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JP28663393A JP3366707B2 (en) | 1993-11-16 | 1993-11-16 | Mn-Zn ferrite |
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JP28663393A JP3366707B2 (en) | 1993-11-16 | 1993-11-16 | Mn-Zn ferrite |
Publications (2)
Publication Number | Publication Date |
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JPH07142223A JPH07142223A (en) | 1995-06-02 |
JP3366707B2 true JP3366707B2 (en) | 2003-01-14 |
Family
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JP28663393A Expired - Fee Related JP3366707B2 (en) | 1993-11-16 | 1993-11-16 | Mn-Zn ferrite |
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JP (1) | JP3366707B2 (en) |
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1993
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JPH07142223A (en) | 1995-06-02 |
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