JPH0430726B2 - - Google Patents
Info
- Publication number
- JPH0430726B2 JPH0430726B2 JP59119538A JP11953884A JPH0430726B2 JP H0430726 B2 JPH0430726 B2 JP H0430726B2 JP 59119538 A JP59119538 A JP 59119538A JP 11953884 A JP11953884 A JP 11953884A JP H0430726 B2 JPH0430726 B2 JP H0430726B2
- Authority
- JP
- Japan
- Prior art keywords
- ferrite
- mol
- basic composition
- magnetic
- magnetic properties
- 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 - Lifetime
Links
- 239000000203 mixture Substances 0.000 claims description 19
- 229910000859 α-Fe Inorganic materials 0.000 claims description 19
- 239000000654 additive Substances 0.000 claims description 15
- 239000002994 raw material Substances 0.000 claims description 15
- 238000005245 sintering Methods 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 238000010298 pulverizing process Methods 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 238000000465 moulding Methods 0.000 claims description 4
- ZKATWMILCYLAPD-UHFFFAOYSA-N niobium pentoxide Chemical compound O=[Nb](=O)O[Nb](=O)=O ZKATWMILCYLAPD-UHFFFAOYSA-N 0.000 claims description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 3
- 229910052681 coesite Inorganic materials 0.000 claims description 3
- 229910052593 corundum Inorganic materials 0.000 claims description 3
- 229910052906 cristobalite Inorganic materials 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- 235000012239 silicon dioxide Nutrition 0.000 claims description 3
- 229910052682 stishovite Inorganic materials 0.000 claims description 3
- 229910052905 tridymite Inorganic materials 0.000 claims description 3
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 3
- 230000002159 abnormal effect Effects 0.000 description 7
- 230000000996 additive effect Effects 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 7
- 239000013078 crystal Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 4
- 229910004298 SiO 2 Inorganic materials 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 239000000696 magnetic material Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 238000001513 hot isostatic pressing Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- -1 V 2 O 5 Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
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
利用産業分野
この発明は、Mn−Zn系フエライトの製造方法
に係り、高い焼結温度でも異常結晶組織を生成す
ることなく、すぐれた磁気特性、特に低磁気損失
特性を有するMn−Zn系フエライトの製造方法に
関する。
背景技術
Mn−Zn系フエライトは、通信機器、電子計算
機、VTR、磁気ヘツド等、各種民生用機器に多
用され、それぞれの用途に応じた改良が施されて
いる。今日の機器の小型化並びに高性能化のた
め、ますます、磁気損失の少ない磁性材料が求め
られている。
かかるMn−Zn系フエライトにおいて、残留
損、ヒステリシス損、渦電流損の少ない材料を得
る方法として、従来、CaOとSiO2の複合添加に
より、電気抵抗を大きくし、磁気特性を向上させ
る手段がよく知られた。しかし、材料の密度を向
上させるために、焼結温度を高くすると、異常な
焼結反応が起り、焼結組織が大きな結晶と小さな
結晶との混在状態を呈し、磁気特性の劣化を招来
しやすい問題があつた。
そこで、出願人は、特願昭58−241607号にて、
高い焼結温度でも異常結晶組織の生成がなく、低
磁気損失特性を有するMn−Zn系フエライトを提
案したが、さらに、磁気特性のすぐれたMn−Zn
系フエライトが望まれている。
発明の目的
この発明は、上記のMn−Zn系フエライトの現
状に鑑み、高い焼結温度でも異常結晶組織を生成
することなく、すぐれた磁気特性が得られ、特に
低磁気損失特性を有するMn−Zn系フエライトを
目的として、Mn−Zn系フエライトの磁気特性を
向上させることができる製造方法を目的としてい
る。
発明の構成と効果
この発明は、特願昭58−241607号で提案した
Mn−Zn系フエライトの磁気特性向上を目的に、
一般に実施されているMn−Zn系フエライトの製
造工程、すなわち、基本組成の原料に対して、添
加物を仮焼前の混合時に添加するか、あるいは基
本組成原料粉砕時に添加し、ついで成型、焼結あ
るいは、さらに熱間静水圧プレス処理する工程に
ついて、特に、添加物原料の配合処理について
種々検討した結果、添加物原料を事前に、反応化
の加熱処理した後、基本組成の仮焼原料の粉砕時
に配合添加し、これを微粉砕したのち、成型、焼
結あるいは、さらに、熱間静水圧プレス処理する
ことにより、従来の製造方法に比べて一段と磁気
特性が向上することを知見したものである。
すなわち、この発明は、
Fe2O3 50〜70モル％、
MnO 10〜40モル％、
ZnO ５〜30モル％、
の基本組成からなる仮焼原料に、予め大気中で
900℃以上に加熱処理した下記添加物を配合添加
し、微粉砕したのち成型、焼結することを特徴と
するMn−Znフエライトの製造方法。
添加物（上記基本組成に対するwt％で示す）
は、
CaO 0.005〜0.3wt％、
Nb2O5 0.005〜0.25wt％と、
SiO2 0.001〜0.2wt％、V2O5 0.01〜2wt％、
Al2O3 0.01〜2wt％、CoO 0.01〜2wt％、
CuO 0.01〜0.2wt％、ZrO2 0.01〜0.22wt％
のうち少なくとも１種からなる。
この発明において、すぐれた磁気特性のMn−
Zn系フエライトが得られる理由は、添加物原料
の事前の反応化により、添加物がMn−Znフエラ
イトの結晶粒界に安定して存在し、反応性が少な
く、焼結フエライト自身の歪発生を抑制するため
と考えられる。
この発明において、基本組成の仮焼原料の粉砕
時に、添加する添加物原料の事前反応化条件とし
て、大気中で900℃以上に加熱処理する理由は、
900℃未満では添加物同士の反応が不十分で、磁
気特性の向上効果が得られないためであり、ま
た、加熱温度としては高温程よいが、作業性の点
から、適宜選定する必要があり、また、加熱雰囲
気としては、大気中でよく、加熱速度は、50℃／
hr〜200℃／hrが好ましく、冷却速度としては徐
冷が望ましい。
組成の限定理由
この発明による酸化物磁性材料において、組成
を限定した理由を以下に説明する。
Mn−Zn系フエライトの基本組成を、Fe2O350
〜70モル％、MnO10〜40モル％、ZnO5〜30モル
％とした理由は、これ以外の組成では、透磁率が
極めて小さくなり、また、保磁力も大きくなりす
ぎて軟質磁性材料として実用的でないためであ
る。
CaOは、低磁気損失を得るために添加するが、
0.005wt％未満では電気抵抗が小さくなり、所要
の磁気特性が得られず、また、0.3wt％を越える
添加では、高密度化のため焼結温度を高くする
と、異常組織が発生しやすくなるため、0.005〜
0.3wt％とする。
Nb2O5は、CaOとの複合添加により、CaO単独
の場合よりもさらにすぐれた磁気特性が得られる
ため添加するが、0.005wt％未満では上記効果が
得られず、また、0.25wt％を越えると、焼結時に
異常組織が発生しやすくなるため、0.005〜
0.25wt％の添加とする。
また、SiO2，V2O5，Al2O3，CoO，CuO，
ZrO2のうち少なくとも１種を含有することは、
Mn−Zn系フエライトの磁気損失特性の改善に著
しい効果があるが、SiO20.001wt％未満、
V2O50.01wt％未満，Al2O30.01wt％未満，
CoO0.01wt％未満，CuO0.01wt％未満，
ZrO20.01wt％未満では、電気抵抗が小さくなり、
磁気損失が大きくなり好ましくなく、また、
SiO20.2wt％，V2O52wt％，Al2O32wt％，
CoO2wt％，CuO0.2wt％，ZrO20.2wt％をそれぞ
れ越えると、焼結時に異常結晶が生成し、磁気損
失も大きくなるため好ましくないため、
SiO20.001〜0.2wt％，
V2O50.01〜2wt％，Al2O30.01〜2wt％，
CoO0.01〜2wt％，CuO0.01〜0.2wt％，
ZrO0.01〜0.2wt％とする。
なお、この発明の主原料、添加物には、焼成に
より酸化物となり得る化合物を使用できることは
当然である。
実施例
Fe2O353モル％，MnO31モル％、ZnO16モル
％，からなる基本組成の原料を配合、混合したの
ち、850℃で仮焼成した。
ついで、CaO，Nb2O5及びSiO2，V2O5，
Al2O3，CoO，CuO，ZrO2のうち少なくとも１種
を、第１表に示す基本組成に対する配合量及び加
熱条件で、大気中にて反応化処理した。
上記の基本組成仮焼原料を、ボールミルで粉砕
する際に、反応化処理した上記添加物原料を配
合、混合粉砕し、外径36mm×内径24mm×高さ６mm
寸法のリング状に成型し、その後、酸素濃度を制
御した窒素ガス雰囲気で、1250℃、３時間の条件
で焼成した。得られた焼成品の磁気特性を測定
し、その結果を第２表に示す。
また、比較のため、添加物原料を未反応化のま
さ、基本組成の仮焼原料の粉砕時に、添加粉砕す
る以外は、基本組成、添加物配合量及び成型、焼
成条件を本発明例（No.１〜10）と同一条件とし
て、焼成した第１表の比較焼成品の磁気特性を測
定し、第２表に示す。
なお、第２表におけるコア損失は、上記リング
状焼成品を巻線し、100kHzの交流電流を流し、
2000Gのときのコア損失を測定した。
第２表より明らかな如く、この発明の特徴であ
る添加物原料を事前に反応化処理し、基本組成粉
砕時に添加配合することにより、Mn−Zn系フエ
ライトは、一段とコア損失の低減、磁気特性の改
善に著しい効果があることが分る。
Field of Application This invention relates to a method for producing Mn-Zn ferrite, which does not produce abnormal crystal structures even at high sintering temperatures and has excellent magnetic properties, especially low magnetic loss properties. Regarding the manufacturing method. BACKGROUND TECHNOLOGY Mn-Zn ferrite is widely used in various consumer devices such as communication equipment, electronic computers, VTRs, and magnetic heads, and has been improved according to each use. Due to the miniaturization and higher performance of today's equipment, magnetic materials with less magnetic loss are increasingly required. Conventionally, in order to obtain a material with low residual loss, hysteresis loss, and eddy current loss in such Mn-Zn-based ferrite, a common method has been to increase the electrical resistance and improve the magnetic properties by adding a combination of CaO and SiO2 . known. However, when the sintering temperature is raised to improve the density of the material, an abnormal sintering reaction occurs, and the sintered structure becomes a mixture of large and small crystals, which tends to deteriorate magnetic properties. There was a problem. Therefore, the applicant, in Japanese Patent Application No. 58-241607,
We proposed Mn-Zn ferrite, which does not generate abnormal crystal structures even at high sintering temperatures and has low magnetic loss characteristics.
ferrite is desired. Purpose of the Invention In view of the current state of the Mn-Zn ferrite described above, the present invention aims to develop a Mn-Zn ferrite which can obtain excellent magnetic properties even at high sintering temperatures without forming an abnormal crystal structure, and has particularly low magnetic loss properties. The purpose of this invention is to provide a manufacturing method that can improve the magnetic properties of Mn-Zn ferrite, with the aim of producing Zn-based ferrite. Structure and Effects of the Invention This invention was proposed in Japanese Patent Application No. 58-241607.
In order to improve the magnetic properties of Mn-Zn ferrite,
In the commonly practiced manufacturing process for Mn-Zn ferrite, additives are added to the raw material of the basic composition during mixing before calcination, or added during the pulverization of the raw material of the basic composition, and then molded and sintered. Finally, as a result of various studies regarding the process of further hot isostatic pressing, especially regarding the blending process of additive raw materials, we found that after preheating the additive raw materials for reaction, the calcined raw materials of the basic composition were It was discovered that magnetic properties can be further improved compared to conventional manufacturing methods by adding the mixture during pulverization, pulverizing it, and then molding, sintering, or hot isostatic pressing. be. That is, in this invention, a calcined raw material having a basic composition of 50 to 70 mol% of Fe 2 O 3 , 10 to 40 mol% of MnO, and 5 to 30 mol% of ZnO is preheated in the atmosphere.
A method for producing Mn-Zn ferrite, which comprises adding the following additives that have been heat-treated to 900°C or higher, pulverizing them, then molding and sintering them. Additives (expressed in wt% relative to the above basic composition)
are: CaO 0.005~0.3wt%, Nb2O5 0.005 ~0.25wt%, SiO2 0.001~0.2wt%, V2O5 0.01~ 2wt%, Al2O3 0.01 ~2wt%, CoO 0.01~2wt% %, CuO 0.01 to 0.2 wt%, and ZrO 2 0.01 to 0.22 wt%. In this invention, Mn-
The reason why Zn-based ferrite can be obtained is that due to the prior reaction of the additive raw materials, the additive exists stably at the grain boundaries of Mn-Zn ferrite, has low reactivity, and does not cause strain in the sintered ferrite itself. This is thought to be to suppress the situation. In this invention, the reason for heat treatment at 900°C or higher in the air as a pre-reaction condition for the additive raw material to be added when pulverizing the calcined raw material with the basic composition is as follows.
This is because if the heating temperature is lower than 900°C, the reaction between the additives is insufficient and the effect of improving magnetic properties cannot be obtained.Also, the higher the heating temperature, the better, but from the viewpoint of workability, it is necessary to select the heating temperature appropriately. In addition, the heating atmosphere may be air, and the heating rate is 50℃/
The cooling rate is preferably hr to 200°C/hr, and slow cooling is desirable as the cooling rate. Reason for Limiting the Composition The reason for limiting the composition in the oxide magnetic material according to the present invention will be explained below. The basic composition of Mn-Zn ferrite is Fe 2 O 3 50
~70 mol%, MnO 10~40 mol%, and ZnO 5~30 mol%.The reason for this is that with other compositions, the magnetic permeability would be extremely small and the coercive force would also be too large to be practical as a soft magnetic material. It's for a reason. CaO is added to obtain low magnetic loss, but
If it is less than 0.005wt%, the electrical resistance becomes small and the required magnetic properties cannot be obtained, and if it exceeds 0.3wt%, abnormal structures are likely to occur when the sintering temperature is increased to increase density. , 0.005~
The content shall be 0.3wt%. Nb 2 O 5 is added because combined addition with CaO provides even better magnetic properties than CaO alone, but if it is less than 0.005wt%, the above effect cannot be obtained, and if 0.25wt% is added, Nb 2 O 5 is added. If it exceeds 0.005~, abnormal structures will easily occur during sintering.
Addition is 0.25wt%. Also, SiO 2 , V 2 O 5 , Al 2 O 3 , CoO, CuO,
Containing at least one kind of ZrO 2 means that
It has a remarkable effect on improving the magnetic loss characteristics of Mn-Zn ferrite, but SiO 2 less than 0.001wt%, V 2 O 5 less than 0.01wt%, Al 2 O 3 less than 0.01wt%, CoO less than 0.01wt%, CuO0 Less than .01wt%, ZrO 2 Less than 0.01wt%, the electrical resistance becomes small,
Magnetic loss increases, which is undesirable, and
SiO 2 0.2wt%, V 2 O 5 2wt%, Al 2 O 3 2wt%,
Exceeding CoO2wt%, CuO0.2wt%, and ZrO 2 0.2wt% is not preferable because abnormal crystals will be generated during sintering and magnetic loss will increase . ~2wt%, Al2O3 0.01 ~2wt%, CoO0.01~2wt%, CuO0.01~0.2wt%, and ZrO0.01~0.2wt%. It goes without saying that compounds that can be converted into oxides by firing can be used as the main raw materials and additives of this invention. Example Raw materials having a basic composition of 53 mol % Fe 2 O 3 , 1 mol % MnO, and 16 mol % ZnO were blended and mixed, and then pre-sintered at 850°C. Then, CaO, Nb 2 O 5 and SiO 2 , V 2 O 5 ,
At least one of Al 2 O 3 , CoO, CuO, and ZrO 2 was subjected to reaction treatment in the air using the blending amount and heating conditions for the basic composition shown in Table 1. When the calcined raw material with the above basic composition is crushed in a ball mill, the additive raw material that has been subjected to the reaction treatment is blended, mixed and crushed.
It was molded into a ring shape with the following dimensions, and then fired at 1250° C. for 3 hours in a nitrogen gas atmosphere with controlled oxygen concentration. The magnetic properties of the obtained fired product were measured and the results are shown in Table 2. For comparison, the basic composition, amount of additives, and molding and firing conditions were changed from the present invention example (No. The magnetic properties of the comparative fired products shown in Table 1 were measured under the same conditions as in 1 to 10) and are shown in Table 2. In addition, the core loss in Table 2 is calculated by winding the above ring-shaped fired product and passing an alternating current of 100 kHz.
We measured the core loss at 2000G. As is clear from Table 2, by pre-reacting the additive raw material, which is a feature of this invention, and adding it to the basic composition during pulverization, Mn-Zn ferrite can further reduce core loss and have magnetic properties. It can be seen that this method has a remarkable effect on improving.
【表】【table】
【表】【table】
Claims (1)
900℃以上に加熱処理した下記添加物を配合添加
し、微粉砕したのち成型、焼結することを特徴と
するMn−Znフエライトの製造方法。 添加物（上記基本組成に対するwt％で示す）
は、 CaO 0.005〜0.3wt％、 Nb2O5 0.005〜0.25wt％と、 SiO2 0.001〜0.2wt％、V2O5 0.01〜2wt％、 Al2O3 0.01〜2wt％、CoO 0.01〜2wt％、 CuO 0.01〜0.2wt％、ZrO2 0.01〜0.22wt％ のうち少なくとも１種からなる。[Scope of Claims] 1. A calcined raw material having the basic composition of 50 to 70 mol% Fe 2 O 3 , 10 to 40 mol % MnO, and 5 to 30 mol % ZnO is preliminarily heated in the atmosphere.
A method for producing Mn-Zn ferrite, which comprises adding the following additives that have been heat-treated to 900°C or higher, pulverizing them, then molding and sintering them. Additives (expressed in wt% relative to the above basic composition)
are: CaO 0.005~0.3wt%, Nb2O5 0.005 ~0.25wt%, SiO2 0.001~0.2wt%, V2O5 0.01~ 2wt%, Al2O3 0.01 ~2wt%, CoO 0.01~2wt% %, CuO 0.01 to 0.2 wt%, and ZrO 2 0.01 to 0.22 wt%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59119538A JPS60262405A (en) | 1984-06-11 | 1984-06-11 | Manufacture of mn-zn ferrite |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59119538A JPS60262405A (en) | 1984-06-11 | 1984-06-11 | Manufacture of mn-zn ferrite |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60262405A JPS60262405A (en) | 1985-12-25 |
| JPH0430726B2 true JPH0430726B2 (en) | 1992-05-22 |
Family
ID=14763763
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59119538A Granted JPS60262405A (en) | 1984-06-11 | 1984-06-11 | Manufacture of mn-zn ferrite |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60262405A (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2556917B2 (en) * | 1990-01-18 | 1996-11-27 | 日立金属株式会社 | Manufacturing method of high frequency and low loss ferrite for power supply |
| JP3042627B2 (en) * | 1990-02-26 | 2000-05-15 | 日立金属株式会社 | Low loss ferrite |
| JPH03248403A (en) * | 1990-02-26 | 1991-11-06 | Hitachi Ferrite Ltd | Low-loss ferrite |
| JP3044666B2 (en) * | 1990-02-26 | 2000-05-22 | 日立金属株式会社 | Low loss ferrite for power supply |
| JP2802839B2 (en) * | 1991-05-14 | 1998-09-24 | 川崎製鉄株式会社 | Oxide soft magnetic material |
| EP0716053B1 (en) * | 1992-01-14 | 1999-03-31 | Matsushita Electric Industrial Co., Ltd. | An oxide magnetic material |
| DE59601546D1 (en) * | 1995-09-15 | 1999-05-06 | Siemens Matsushita Components | Manganese zinc ferrite |
| US20060118756A1 (en) * | 2002-09-26 | 2006-06-08 | Kenya Takagawa | Ferrite material |
| JP4711897B2 (en) * | 2006-06-15 | 2011-06-29 | Ｊｆｅフェライト株式会社 | MnCoZn ferrite and transformer core |
| JP4752934B2 (en) * | 2009-03-05 | 2011-08-17 | Ｔｄｋ株式会社 | Radio wave absorber and manufacturing method thereof |
| CN110128124B (en) * | 2019-05-13 | 2021-12-07 | 海宁联丰磁业股份有限公司 | Wide-temperature ultralow-loss soft magnetic ferrite material and preparation method thereof |
-
1984
- 1984-06-11 JP JP59119538A patent/JPS60262405A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60262405A (en) | 1985-12-25 |
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