JPH0448704A - Manufacture of barium ferrite magnetic powder - Google Patents
Manufacture of barium ferrite magnetic powderInfo
- Publication number
- JPH0448704A JPH0448704A JP2155241A JP15524190A JPH0448704A JP H0448704 A JPH0448704 A JP H0448704A JP 2155241 A JP2155241 A JP 2155241A JP 15524190 A JP15524190 A JP 15524190A JP H0448704 A JPH0448704 A JP H0448704A
- Authority
- JP
- Japan
- Prior art keywords
- iron oxide
- magnetic powder
- raw material
- barium
- hydroxide
- 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.)
- Pending
Links
- 239000006247 magnetic powder Substances 0.000 title claims abstract description 36
- AJCDFVKYMIUXCR-UHFFFAOYSA-N oxobarium;oxo(oxoferriooxy)iron Chemical compound [Ba]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O AJCDFVKYMIUXCR-UHFFFAOYSA-N 0.000 title claims abstract description 25
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 11
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 42
- 239000002002 slurry Substances 0.000 claims abstract description 38
- 238000000034 method Methods 0.000 claims abstract description 20
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 15
- RQPZNWPYLFFXCP-UHFFFAOYSA-L barium dihydroxide Chemical compound [OH-].[OH-].[Ba+2] RQPZNWPYLFFXCP-UHFFFAOYSA-L 0.000 claims abstract description 15
- 229910001863 barium hydroxide Inorganic materials 0.000 claims abstract description 15
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 claims abstract description 13
- 235000014413 iron hydroxide Nutrition 0.000 claims abstract description 11
- 238000005507 spraying Methods 0.000 claims abstract description 9
- 239000007864 aqueous solution Substances 0.000 claims description 15
- 229910002588 FeOOH Inorganic materials 0.000 claims description 6
- 239000000243 solution Substances 0.000 claims description 5
- 229910006540 α-FeOOH Inorganic materials 0.000 claims description 2
- 150000001875 compounds Chemical class 0.000 claims 1
- 239000002994 raw material Substances 0.000 abstract description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 11
- 230000005415 magnetization Effects 0.000 abstract description 10
- 229910052742 iron Inorganic materials 0.000 abstract description 4
- 238000002156 mixing Methods 0.000 abstract description 3
- 239000006185 dispersion Substances 0.000 abstract description 2
- 238000005979 thermal decomposition reaction Methods 0.000 abstract 2
- 238000002360 preparation method Methods 0.000 abstract 1
- 239000002245 particle Substances 0.000 description 22
- 239000000843 powder Substances 0.000 description 16
- 239000007789 gas Substances 0.000 description 12
- 235000013980 iron oxide Nutrition 0.000 description 11
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 239000001301 oxygen Substances 0.000 description 9
- 229910052760 oxygen Inorganic materials 0.000 description 9
- 239000000654 additive Substances 0.000 description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 8
- 239000007921 spray Substances 0.000 description 5
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 239000000696 magnetic material Substances 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 239000003513 alkali Substances 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 150000002506 iron compounds Chemical class 0.000 description 3
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 238000006467 substitution reaction Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- -1 Fe(III) ions Chemical class 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 229910018967 Pt—Rh Inorganic materials 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 229910052788 barium Inorganic materials 0.000 description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- 229910001422 barium ion Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 229960004887 ferric hydroxide Drugs 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 description 2
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 description 2
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- KDYFGRWQOYBRFD-UHFFFAOYSA-N succinic acid Chemical compound OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 229910003145 α-Fe2O3 Inorganic materials 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- NKQIMNKPSDEDMO-UHFFFAOYSA-L barium bromide Chemical compound [Br-].[Br-].[Ba+2] NKQIMNKPSDEDMO-UHFFFAOYSA-L 0.000 description 1
- 229910001620 barium bromide Inorganic materials 0.000 description 1
- WDIHJSXYQDMJHN-UHFFFAOYSA-L barium chloride Chemical compound [Cl-].[Cl-].[Ba+2] WDIHJSXYQDMJHN-UHFFFAOYSA-L 0.000 description 1
- 229910001626 barium chloride Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 150000001649 bromium compounds Chemical class 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- UBAZGMLMVVQSCD-UHFFFAOYSA-N carbon dioxide;molecular oxygen Chemical compound O=O.O=C=O UBAZGMLMVVQSCD-UHFFFAOYSA-N 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- XLJKHNWPARRRJB-UHFFFAOYSA-N cobalt(2+) Chemical compound [Co+2] XLJKHNWPARRRJB-UHFFFAOYSA-N 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 150000001991 dicarboxylic acids Chemical class 0.000 description 1
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000007496 glass forming Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 1
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- FLTRNWIFKITPIO-UHFFFAOYSA-N iron;trihydrate Chemical compound O.O.O.[Fe] FLTRNWIFKITPIO-UHFFFAOYSA-N 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
- 230000002250 progressing effect Effects 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000005118 spray pyrolysis Methods 0.000 description 1
- 239000001384 succinic acid Substances 0.000 description 1
- 150000003628 tricarboxylic acids Chemical class 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明はバリウムフェライト磁性粉末の製造方法に関し
、更に詳しくは微細で分散性に優れたバリウムフェライ
ト磁性粉末の製造方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing barium ferrite magnetic powder, and more particularly to a method for producing barium ferrite magnetic powder that is fine and has excellent dispersibility.
バリウムフェライト磁性粉末の主な用途は、焼結磁石、
磁気記録用磁性材料、防錆剤などであり、更に近年特に
垂直磁気記録用磁性材料としての用途も注目され、その
開発が進められている。The main uses of barium ferrite magnetic powder are sintered magnets,
It is used as a magnetic material for magnetic recording, as a rust preventive, and in recent years, its use as a magnetic material for perpendicular magnetic recording has also attracted attention, and its development is progressing.
（従来の技術）
従来、バリウムフェライト磁性粉末の製造方法として、
■炭酸バリウムと酸化鉄を粉砕、混合後１０００℃以上
で焼成し、更に粉砕する乾式法、■Ｆｅ（Ｉ［［）イオ
ンとＢａイオンの水溶液にアルカリを加えて共沈させ、
濾過、水洗後焼成する共沈法、
■Ｆｅ（ＩＩＩ）イオンとＢａイオンを含む強アルカリ
性スラリーを１５０〜３３０℃で水処理する水熱合成法
、
■酸化第二鉄と炭酸バリウムをホウ酸等のガラス形成物
質と混合し、１３５０℃前後で加熱溶解した後急冷し、
次いで８００℃前後で再焼成し、得られた焼成品を酢酸
等の希酸で処理するガラス結晶化法、
などが知られている。しかしながら、上記■、■の方法
で得られた磁性粉末は焼結性が激しく、粒度分布が広く
、粒径も１μｍ以上であるため、分散性に劣り、これを
磁気記録材料として用いることは困難であった。また、
■の方法で得られた磁性粉末は分散性に優れているもの
の、その磁気値は低く、更に■の方法はその工程が繁雑
であるという問題点がある。(Prior art) Conventionally, as methods for producing barium ferrite magnetic powder, there are two methods: (1) a dry method in which barium carbonate and iron oxide are crushed, mixed, fired at 1000°C or higher, and further crushed; (2) Fe(I[[) ions and Ba Co-precipitate by adding alkali to an aqueous solution of ions,
Co-precipitation method in which filtration, washing with water followed by calcination, ■ Hydrothermal synthesis method in which a strong alkaline slurry containing Fe(III) ions and Ba ions is treated with water at 150 to 330°C, ■ Ferric oxide and barium carbonate are mixed with boric acid, etc. mixed with a glass-forming substance, melted by heating at around 1350°C, and then rapidly cooled.
A glass crystallization method is known in which the fired product is then re-fired at around 800°C and treated with a dilute acid such as acetic acid. However, the magnetic powder obtained by methods ① and ① above has strong sinterability, a wide particle size distribution, and a particle size of 1 μm or more, so it has poor dispersibility and is difficult to use as a magnetic recording material. Met. Also,
Although the magnetic powder obtained by method (1) has excellent dispersibility, its magnetic value is low, and method (2) has the problem that the process is complicated.
（発明が解決しようとする課題）
本発明は上記従来技術のもつ問題点を解決するためにな
されたものであり、均整な微細粒子で高分散性を有し、
形状は板状であり、かつ磁化値が大きいバリウムフェラ
イト磁性粉末を簡便に製造する方法を提供することを目
的とする。(Problems to be Solved by the Invention) The present invention has been made to solve the problems of the above-mentioned prior art, and has well-balanced fine particles with high dispersibility,
It is an object of the present invention to provide a method for easily producing barium ferrite magnetic powder that is plate-like and has a large magnetization value.
（課題を解決するための手段）
本発明者らは、上記課題を解決するために種々検討を行
った結果、水酸化バリウム水溶液と固体含酸素鉄化合物
とを主として含むスラリーを高温雰囲気に噴霧すること
により、微細で磁気特性の優れたバリウムフェライト磁
性粉末を経済的に製造できることを見出し、本発明を完
成するに至った。すなわち本発明は、水酸化バリウム水
溶液と酸化鉄及び／又は水加酸化鉄とを主として含むス
ラリーを７００℃以上のガス雰囲気中に噴霧し、熱分解
することを特徴とするバリウムフェライト磁性粉末の製
造方法である。本発明の骨子は、第一にバリウムフェラ
イト磁性粉末を得るために用いられるバリウム源が水酸
化バリウムであり、実質的に水溶液状態であること、鉄
源は酸化鉄及び／又は水加酸化鉄、即ち固体の含酸素鉄
化合物であること及び原料としてこの両者が混合したス
ラリーを用いることにある。第二はこのスラリーを７０
０℃以上のガス雰囲気中に噴霧し、熱分解し、−気にバ
リウムフェライト磁性粉末を得ることにある。以下、本
発明を更に詳細に説明する。(Means for Solving the Problems) As a result of various studies to solve the above problems, the present inventors have found that a slurry mainly containing an aqueous barium hydroxide solution and a solid oxygen-containing iron compound is sprayed into a high-temperature atmosphere. The inventors have discovered that, by doing so, it is possible to economically produce fine barium ferrite magnetic powder with excellent magnetic properties, and have completed the present invention. That is, the present invention is directed to the production of barium ferrite magnetic powder, which is characterized in that a slurry mainly containing an aqueous barium hydroxide solution and iron oxide and/or iron hydroxide is sprayed into a gas atmosphere of 700°C or higher and thermally decomposed. It's a method. The gist of the present invention is, firstly, that the barium source used to obtain the barium ferrite magnetic powder is barium hydroxide, which is substantially in an aqueous solution state, and that the iron source is iron oxide and/or iron hydroxide, That is, it is a solid oxygen-containing iron compound, and a slurry containing the two is used as a raw material. Second, add this slurry to 70
The purpose is to obtain barium ferrite magnetic powder by spraying it into a gas atmosphere of 0° C. or higher and thermally decomposing it. The present invention will be explained in more detail below.
本発明は、水酸化バリウム水溶液と酸化鉄及び／又は水
加酸化鉄とを主として含むスラリーを原料として用いる
ことを必須とする。ここで、原料スラリー中に含まれる
酸化鉄としては、酸化第一鉄、酸化第二鉄などが、水加
酸化鉄としては水酸化第一鉄、水酸化第二鉄（Ｆｅ（Ｏ
Ｈ）３あるいはＦｅ Ｏ−ＸＨ２Ｏ） 、ａ−ＦｅＯ
ＯＨ（ゲ一タイト）、δ−ＦｅＯＯＨなどが挙げられる
が粒径のそろった微細な磁性粉末を収率よく得るために
は鉄源として水酸化第二鉄、α−ＦｅＯＯＨ。The present invention requires that a slurry mainly containing an aqueous barium hydroxide solution and iron oxide and/or iron hydroxide be used as a raw material. Here, the iron oxides contained in the raw material slurry include ferrous oxide, ferric oxide, etc., and the hydrated iron oxides include ferrous hydroxide, ferric hydroxide (Fe(O
H)3 or FeO-XH2O), a-FeO
Examples include OH (genitite) and δ-FeOOH, but in order to obtain fine magnetic powder with uniform particle size in good yield, ferric hydroxide and α-FeOOH are used as the iron source.
δ−Ｆｅ００Ｈを用いることが好ましく、更に結晶形の
点から鉄源としてδ−ＦｅＯＯＨを用いることが望まし
い。また、分散性が良好で、微細な磁性粉末を得るため
には上記の酸化鉄及び／又は水加酸化鉄の粒子は、１個
１個がバラバラで微細であることが好ましく、各々の粒
子径は０．０１〜０．３１ｍとすることが好ましく、更
に好ましくは０．０３〜０．１７ｍである。なお、これ
らの酸化鉄及び／又は水加酸化鉄の製造は特に限定され
ることはなく、公知の方法で得られたもの、または市販
品を用いることができる。It is preferable to use δ-FeOOH, and furthermore, it is desirable to use δ-FeOOH as the iron source from the viewpoint of crystal form. In addition, in order to obtain a fine magnetic powder with good dispersibility, it is preferable that the particles of the iron oxide and/or iron hydroxide mentioned above are individually fine and dispersed, and each particle size is is preferably 0.01 to 0.31 m, more preferably 0.03 to 0.17 m. Note that the production of these iron oxides and/or iron hydroxides is not particularly limited, and those obtained by known methods or commercially available products can be used.
一方、原料スラリー中に含まれる水酸化バリウムは水溶
液であるが、水酸化バリウムが水溶液中で固体として存
在する場合、得られる磁性粉末の凝集が激しくなるおそ
れがあるので、濃度は水酸化バリウムの溶解度の範囲内
に設定することが好ましい。On the other hand, barium hydroxide contained in the raw material slurry is an aqueous solution, but if barium hydroxide exists as a solid in an aqueous solution, there is a risk that the obtained magnetic powder will agglomerate violently, so the concentration of barium hydroxide should be adjusted accordingly. It is preferable to set the solubility within the range.
更に、得られる磁性粉末の分散性をより向上させるため
に、原料スラリー中にリチウム、ナトリウム、カリウム
、バリウムの塩化物、臭化物などの塩を添加してもよい
がこれら添加物はスラリー中に溶解していることが望ま
しい。なお、上記添加物のうち水酸化ナトリウム、水酸
化カリウムなどのアルカリを用いた場合、バリウムフェ
ライトが生成しないおそれがあるが、例えば水酸化ナト
リウム水溶液に塩化バリウムを溶解させる水酸化バリウ
ム水溶液の調製方法などにおいてアルカリを用いること
は、水酸化物イオンがＢａイオンに対して当量以下とす
れば何ら差支えない。Furthermore, in order to further improve the dispersibility of the resulting magnetic powder, salts such as chlorides and bromides of lithium, sodium, potassium, and barium may be added to the raw slurry, but these additives must be dissolved in the slurry. It is desirable that you do so. Note that if alkali such as sodium hydroxide or potassium hydroxide is used among the above additives, there is a risk that barium ferrite will not be generated. There is no problem in using an alkali in such cases as long as the amount of hydroxide ions is equal to or less than the amount of Ba ions.
また、本発明は原料スラリーを熱分解して磁性粉末を得
るものであることから、用いる原料スラリー中に、助燃
作用を有するアルコール、アセトンなどの有機溶媒を添
加してもよい。また、その他にも原料スラリー中にカル
ボン酸を含む有機酸などの添加剤を添加することにより
、得られる磁性材料の磁気粉末の向上を図ることができ
る。この添加剤としては、コハク酸、クエン酸などのジ
カルボン酸、トリカルボン酸などが好ましく用いられ、
用いる量は原料スラリー中に含まれるＢａに対して４倍
モル以上であることが好ましい。上記添加剤を用いるこ
とにより得られる磁性粉末の磁気特性が向上する理由は
、添加剤自身の助燃作用、および添加剤と金属原子との
複合錯体形成による核発生の均一化などの効果が反応率
、結晶化度、および分散性などのファクターに影響を与
えることによるものと推定される。Furthermore, since the present invention obtains magnetic powder by thermally decomposing a raw material slurry, an organic solvent such as alcohol or acetone having a combustion-enhancing effect may be added to the raw material slurry used. In addition, by adding additives such as organic acids containing carboxylic acids to the raw material slurry, it is possible to improve the magnetic powder of the magnetic material obtained. As this additive, dicarboxylic acids such as succinic acid and citric acid, tricarboxylic acids, etc. are preferably used.
The amount used is preferably at least 4 times the molar amount of Ba contained in the raw material slurry. The reason why the magnetic properties of the magnetic powder obtained by using the above additives is improved is because of the combustion-enhancing effect of the additives themselves and the uniformity of nucleation due to the formation of complexes between the additives and metal atoms. This is presumed to be due to influencing factors such as , crystallinity, and dispersibility.
また、一般に磁性粉末を磁気記録用磁性材料として用い
る場合、一般に磁性粉末の磁化値を下げずに保磁力（Ｈ
ｅ）の調整が行なわれるが、本発明においてこの調整は
Ｃｏ（ＩＩ）とＴｉ（ＩＶ）またはＺｎ （ＩＩ）と５
ｎ（ＩＶ）などの置換元素を磁性粉末中に導入すること
により達成することができる。なお、この置換元素の導
入はあらかじめ酸化鉄及び／又は水加酸化鉄に行なって
も、原料スラリーを調製する時に行なってもよい。In general, when magnetic powder is used as a magnetic material for magnetic recording, coercive force (H
e), and in the present invention this adjustment is carried out using Co(II) and Ti(IV) or Zn(II) and 5
This can be achieved by introducing a substituting element such as n(IV) into the magnetic powder. Note that this substitution element may be introduced into the iron oxide and/or hydrated iron oxide in advance, or may be introduced at the time of preparing the raw material slurry.
本発明において、原料スラリーにおける水酸化バリウム
と酸化鉄及び／又は水加酸化鉄のＦｅ／Ｂａ（原子比）
は４〜１２とすることが好ましい。In the present invention, Fe/Ba (atomic ratio) of barium hydroxide and iron oxide and/or iron hydroxide in the raw material slurry
is preferably 4 to 12.
この原子比が４よりも小さくなるとバリウムフェライト
の生成量が減少し、結晶形も悪くなることがあり、１２
よりも大きくなると不純物としてのα−Ｆｅ２Ｏ３が多
くなる傾向がある。更にＣ。When this atomic ratio becomes smaller than 4, the amount of barium ferrite produced decreases and the crystal shape may deteriorate.
If it is larger than , there is a tendency for α-Fe2O3 as an impurity to increase. Furthermore C.
（ＩＩ） 、Ｔ ｉ （ＩＶ）などの置換元素を導入す
る場合、これらの置換元素はＦｅとして換算してＦｅ／
Ｂ ａが設定される。また、得られる磁性粉末の分散
性を向上させるために原料スラリー中に添加する塩化バ
リウム、臭化バリウムなどの添加物はＦ ｅ ／ Ｂ
ａの設定に関係しない。When introducing substitution elements such as (II) and Ti (IV), these substitution elements are converted into Fe/Fe/
B a is set. In addition, additives such as barium chloride and barium bromide that are added to the raw material slurry to improve the dispersibility of the obtained magnetic powder are F e / B
It is not related to the setting of a.
また原料スラリーの調製方法は特に限定されないが、例
えばホモジナイザーの如き分散混合型の攪拌機を使用す
ることにより行なうことができる。Further, the method for preparing the raw material slurry is not particularly limited, but it can be carried out, for example, by using a dispersion mixing type stirrer such as a homogenizer.
次いで本発明は上記の原料７．ラリ−を７００℃以上の
ガス雰囲気中に噴霧し、熱分解することを必須とする。Next, the present invention uses the above raw material 7. It is essential to spray the rally into a gas atmosphere of 700°C or higher and thermally decompose it.
このとき用いられるガス雰囲気としては、水蒸気、窒素
、酸素、炭酸ガス、アルゴンなどが挙げられ、いずれの
ものでも用いることができ、またこれらガスの混合系を
用いてもよい。The gas atmosphere used at this time includes water vapor, nitrogen, oxygen, carbon dioxide, argon, and the like, and any of them can be used, or a mixed system of these gases can be used.
このうち特に反応を速めるためには、酸素あるいは酸素
を含むガス雰囲気を用いることが好ましい。Among these, in order to particularly speed up the reaction, it is preferable to use oxygen or a gas atmosphere containing oxygen.
また、原料スラリーを噴霧するときの噴滴は５０＃ｍ以
下であることが好ましく、更に好鳶しくは２ＯｊＩｌｌ
以下で、粒度分布をシャープにすることである。この噴
滴が５０＃ｆｆｉよりも大きくなるとバリウムフェライ
ト磁性粉末の反応率は減少してしまう傾向があり、噴滴
の粒度分布がブロードになると得られる磁性粉末の粒度
分布もブロードになるおそれがある。噴霧の際に用いる
噴霧器としては、二流体ノズル、超音波ノズル、などが
挙げられる。Further, when spraying the raw material slurry, the spray droplets are preferably 50 #m or less, more preferably 20 #m or less.
The following is to sharpen the particle size distribution. If the droplets are larger than 50 #ffi, the reaction rate of the barium ferrite magnetic powder tends to decrease, and if the particle size distribution of the droplets becomes broad, the particle size distribution of the obtained magnetic powder may also become broad. . Examples of the sprayer used for spraying include a two-fluid nozzle, an ultrasonic nozzle, and the like.
また、上記スラリーを噴霧するガス雰囲気中は７００℃
以上であるが、この温度が低い場合、磁性粉末の生成率
が低くなり、あまりにも高い場合、粒子間の焼結が激し
くなり磁性粉末の粒径も大きくなるおそれがある。従っ
て、より好ましい温度は７５０〜１１００℃である。更
に噴滴の滞留時間は雰囲気温度によるが、温度が高い場
合短く、温度が低い場合は長くすることが好ましい。な
お、原料スラリーを上記雰囲気中で、火炎中に噴霧する
ことによっても、優れた磁気特性を有する磁性粉末を効
率よく得ることができる。このときの火炎は７００℃以
上であることが必要であり、用いられる火炎を形成する
ためのバーナーとしては、噴霧された噴滴がうまく火炎
ゾーンに導かれるような形状、すなわち噴滴と火炎とが
効率的に接触混合されるようなバーナーであることが好
ましい。In addition, the temperature in the gas atmosphere in which the above slurry is sprayed is 700°C.
As mentioned above, if this temperature is low, the production rate of magnetic powder will be low, and if it is too high, sintering between particles will be severe and the particle size of the magnetic powder may become large. Therefore, a more preferable temperature is 750 to 1100°C. Further, the residence time of the ejected droplets depends on the ambient temperature, but it is preferable that the residence time is short when the temperature is high, and long when the temperature is low. Note that magnetic powder having excellent magnetic properties can also be efficiently obtained by spraying the raw material slurry into a flame in the above atmosphere. The flame at this time needs to be at least 700°C, and the burner used to form the flame must have a shape that allows the sprayed droplets to be guided well to the flame zone, that is, the shape of the flame is such that the droplets and the flame Preferably, the burner is one that allows efficient contact mixing.
この方法において、噴滴と火炎の接触性が悪い場合、反
応性が低下し、バリウムフェライト磁性粉末の生成量が
減少するおそれかある。また、用いるバーナーとしては
、リングバーナー、予混合式バーナー、全噴霧式バーナ
ーなどが挙げられ、ガスとして、プロパン、アセチレン
、水素等の可燃性ガスと酸素との混合ガスなどが挙げら
れる。In this method, if the contact between the droplets and the flame is poor, the reactivity may decrease and the amount of barium ferrite magnetic powder produced may decrease. Examples of the burner used include a ring burner, a premix burner, and a full spray burner, and examples of the gas include a mixed gas of flammable gas such as propane, acetylene, and hydrogen and oxygen.
上述した本発明において得られるバリウムフェライト磁
性粉末の特性は、水酸化バリウムの濃度、含酸素鉄化合
物の種類、粒径、溶媒の種類、原料組成比、噴滴径、噴
霧速度、火炎と噴滴との接触性、雰囲気温度、雰囲気ガ
スに依存するので、これら条件を適宜設定することによ
りコントロールすることができる。また、生成した磁性
粉末は、未反応物質、他の塩を含むことがあるので、水
洗したり、希薄酸で溶解して不純物を除去することが好
ましい。The characteristics of the barium ferrite magnetic powder obtained in the present invention described above include the concentration of barium hydroxide, the type of oxygen-containing iron compound, the particle size, the type of solvent, the raw material composition ratio, the droplet diameter, the spray speed, the flame and the droplet. Since it depends on the contact with the atmosphere, the ambient temperature, and the ambient gas, it can be controlled by appropriately setting these conditions. Furthermore, since the generated magnetic powder may contain unreacted substances and other salts, it is preferable to remove impurities by washing with water or dissolving with dilute acid.
以上の方法により、粒子径が０．０１〜０．３１、高分
散で板状、且つ磁化値の高いノくリウムフェライト磁性
粉末を経済的に効率良く得ることができる。By the above method, it is possible to economically and efficiently obtain a highly dispersed, plate-shaped, and highly magnetized ferrite magnetic powder having a particle size of 0.01 to 0.31.
（実施例）
以下、本発明の実施例および比較例を示すが、本発明は
これらに限定されるものではない。(Example) Examples and comparative examples of the present invention will be shown below, but the present invention is not limited thereto.
尚、本実施例において磁化値、保磁力は粉末状態で１０
ＫＯｅの磁場において試料振動型磁力計（ＶＳＭ）を用
いて測定した。In this example, the magnetization value and coercive force are 10 in the powder state.
Measurements were made using a vibrating sample magnetometer (VSM) in the magnetic field of KOe.
実施例１
１、６ｗｏｌ／ｊ！のＦ ｅ Ｓ Ｏ４を含む水溶液５
３２１１に、１０ ｓｏｌ＃）のＮａＯＨ水溶液５１）
を混合し、水酸化第一鉄を析出させ、次にこれに１ ｍ
ｏｌ／ｆ）のＣｏＣｊｌｌ 水溶液とＴ Ｉ Ｃ１）
４水溶液を各々７５■１添加混合し、更にこれに１０
％のＨ２Ｏ２溶液を４２５１を加えて急速酸化を行なう
ことにより、δ−ＦｅＯＯＨを含むスラリー得た。その
後、このδ−Ｆｅ００Ｈを含むスラリーを濾過、水洗し
てＮａＯＨを除去したδ−ＦｅＯＯＨのケークを得、こ
れを０．１４ｍｏｌ／！ｌのＢ ａ （ＯＲ） ２水溶
液中にホモミキサーを用いて分散混合して、（Ｆ ｅ＋
Ｃｏ＋Ｔ ｉ）／Ｂａ （原子比）が８．５、Ｂ ａ
（ＯＨ） ２の濃度が０．０８３ｓｏｌ＃ｌの原料スラ
リーを調製した。Example 1 1,6 wol/j! Aqueous solution 5 containing FeSO4 of
3211, 10 sol#) NaOH aqueous solution 51)
to precipitate ferrous hydroxide, and then add 1 m
CoCjll aqueous solution of ol/f) and T I C1)
4 aqueous solutions were added and mixed, and then 10
A slurry containing δ-FeOOH was obtained by rapid oxidation by adding 4251% H2O2 solution. Thereafter, this slurry containing δ-Fe00H was filtered and washed with water to remove NaOH to obtain a δ-FeOOH cake, which was 0.14 mol/! 1 of B a (OR) 2 aqueous solution using a homomixer, and (F e+
Co+T i)/Ba (atomic ratio) is 8.5, Ba
A raw material slurry having a concentration of (OH) 2 of 0.083 sol#l was prepared.
次いで、内部が酸素雰囲気である電気炉中に上記原料ス
ラリーを噴霧した。噴霧は、電気炉内の温度を１０５０
℃となるように調節し、はぼ均一な温度分布が得られて
いることをＰｔ−Ｒｈ熱電対で確認した後、スラリーを
ＩＮ／時間の噴霧速度で二流体ノズルを用い、粒径が１
０μｍ程度の噴滴となるようにして行なった。噴滴は酸
素雰囲気を通って熱分解し、粉末となってフィルターで
補集された。その後補集された粉末を水洗、乾燥した。Next, the raw material slurry was sprayed into an electric furnace with an oxygen atmosphere inside. The spraying lowers the temperature inside the electric furnace to 1050℃.
After confirming with a Pt-Rh thermocouple that a fairly uniform temperature distribution was obtained, the slurry was sprayed at a spray rate of IN/hour using a two-fluid nozzle, and the particle size was 1°C.
This was done so that the droplet size was about 0 μm. The droplets passed through an oxygen atmosphere and decomposed into powder, which was collected by a filter. Thereafter, the collected powder was washed with water and dried.
この得られた微粉末をＸ線回折により分析したところバ
リウムフェライトであることが確認された。また、その
飽和磁化は４６ｅｓｕ／ｇで、保磁力は８０００ｅであ
った。更に、電子顕微鏡で観察した結果、微粉末の粒径
は均整て、平均粒径は０．０８μｍの六角に近い板状で
あった。When the obtained fine powder was analyzed by X-ray diffraction, it was confirmed that it was barium ferrite. Further, its saturation magnetization was 46 esu/g, and its coercive force was 8000 e. Further, as a result of observation using an electron microscope, the particle size of the fine powder was uniform, and the average particle size was 0.08 μm, and it was found to be in the shape of a nearly hexagonal plate.
実施例２
実施例１において調製した原料スラリーを内部が空気雰
囲気である反応器の中に上記原料スラリーを噴霧した。Example 2 The raw material slurry prepared in Example 1 was sprayed into a reactor having an air atmosphere inside.
噴霧は、反応器内の温度が９７０℃になるようにプロパ
ン−酸素炎のガス流量を調節し、はぼ均一な温度分布が
得られていることをＰ ｔ−Ｒｈ熱電対で確認した後、
スラリーを１１／時間の噴霧速度で二流体ノズルを用い
、粒径がｌｃ１ｍ程度の噴滴がうまく火炎ゾーンを通る
ように噴霧して行なった。噴滴は火炎ゾーンを通って熱
分解し、粉末となってフィルターで補集された。For spraying, the gas flow rate of the propane-oxygen flame was adjusted so that the temperature inside the reactor was 970°C, and after confirming with a Pt-Rh thermocouple that a fairly uniform temperature distribution was obtained,
The slurry was atomized using a two-fluid nozzle at an atomization rate of 11/hour so that droplets with a particle size of about 1 cm passed through the flame zone. The droplets passed through the flame zone and decomposed into a powder that was collected by a filter.
その後補集された粉末を水洗、乾燥した。Thereafter, the collected powder was washed with water and dried.
この得られた微粉末をＸ線回折により分析したところバ
リウムフェライトであることが確認された。また、その
飽和磁化は４８ｅ■ｕ ／ ｇで、保磁力は８５００ｅ
であった。更に、電子顕微鏡で観察した結果、微粉末の
粒径は均整で、平均粒径は０．０７ｊｍの六角に近い板
状であった。When the obtained fine powder was analyzed by X-ray diffraction, it was confirmed that it was barium ferrite. In addition, its saturation magnetization is 48e■u/g, and its coercive force is 8500e
Met. Furthermore, as a result of observation with an electron microscope, the particle size of the fine powder was uniform, and the average particle size was 0.07 jm, and it was found to be in the shape of a nearly hexagonal plate.
実施例３
１ 、 Ｏｓｏｌ／１１のＦ ｅ ＣＩＩ ｇを含む
Ｉ１１水溶液に２．０箇ｏ１／ｆｌのＮＨ４ＯＨ水溶液
２ｆＩを混合し、これに１１ｏｌｌのＣｏ Ｃ１） ２
水溶液とＴ ｉＣＩ ２水溶液を各々８８ｍ１添加混合
し、Ｆｅ（ＯＨ）３を含むスラリーを得た。次にこのＦ
ｅ （ＯＨ） ａを含むスラリーをろ過、水洗してＮ
Ｈ４ＯＨを除去したＦｅ（ＯＨ）３のケークを得、この
ケークを０．１０ｍｏｌ＃）のＢ ａ （ＯＨ） ２水
溶液にホモミキサーを用いて分散混合して、（Ｆｅ十Ｃ
ｏ＋Ｔｉ）／Ｂａ（原子比）が８．５の原料スラリーを
調製した。Example 3 2.0 o1/fl of NH4OH aqueous solution 2fI was mixed into an I11 aqueous solution containing 1, Osol/11 g of F e CII, and 11 oll of Co C1) 2 was added to this.
88 ml each of the aqueous solution and TiCI 2 aqueous solution were added and mixed to obtain a slurry containing Fe(OH) 3 . Next this F
Filter the slurry containing e (OH) a, wash it with water, and remove N.
A cake of Fe(OH)3 from which H4OH was removed was obtained, and this cake was dispersed and mixed in an aqueous solution of 0.10 mol#) of B a (OH) 2 using a homomixer.
A raw material slurry having an atomic ratio of 8.5 (o+Ti)/Ba (atomic ratio) was prepared.
次に、実施例２と同一装置を用い、同様に操作し、噴霧
熱分解を行ない微粉末を得た。但し、このとき反応器内
の平均温度は１１００℃とした。Next, using the same apparatus as in Example 2 and operating in the same manner, spray pyrolysis was performed to obtain a fine powder. However, at this time, the average temperature inside the reactor was 1100°C.
得られた微粉末をＸ１１回折により分析したところバリ
ウムフェライトであることが確認された。When the obtained fine powder was analyzed by X11 diffraction, it was confirmed that it was barium ferrite.
また、この微粉末の飽和磁化値は４５ｅｍｕ／ｇで、保
磁力は７０００ｅであった。更に電子顕微鏡で観察した
結果、微粉末の粒径は均整で平均粒径は０．０８ｊｍの
六角に近い板状であった。Moreover, the saturation magnetization value of this fine powder was 45 emu/g, and the coercive force was 7000 e. Furthermore, as a result of observation using an electron microscope, the particle size of the fine powder was uniform, and the average particle size was 0.08 jm, and it was found to be in the shape of a nearly hexagonal plate.
比較例
反応器内の温度を６５０℃とした以外は、実施例２と同
様の方法で粉末を得た。得られた粉末は、Ｘ線回折パタ
ーンから、α−Ｆｅ２Ｏ３を多量に含有する粉末であっ
た。また、その飽和磁化値は１２ｅｍｕ／ｇであった◎
（発明の効果）
以上述べたように、本発明の方法によれば均整な微粒子
で、その粒形は六角に近い板状であり、飽和磁化も高い
バリウムフェライト磁性粉末が得られ、この微粉末は高
分散性を有するものとなる。Comparative Example Powder was obtained in the same manner as in Example 2, except that the temperature inside the reactor was 650°C. The obtained powder was found to contain a large amount of α-Fe2O3 from the X-ray diffraction pattern. In addition, the saturation magnetization value was 12 emu/g◎ (Effect of the invention) As mentioned above, according to the method of the present invention, the particles are well-balanced, the particle shape is plate-like, close to hexagonal, and the saturation magnetization value is 12 emu/g. Barium ferrite magnetic powder with high magnetization is obtained, and this fine powder has high dispersibility.
更に、本発明の方法は極めて簡便で操作も容品であり、
工業的、紅済的に優位な方法である。Furthermore, the method of the present invention is extremely simple and easy to operate;
This is an advantageous method from an industrial and Hongji perspective.
Claims (4)
化鉄とを主として含むスラリーを７００℃以上のガス雰
囲気中に噴霧し、熱分解することを特徴とするバリウム
フェライト磁性粉末の製造方法。(1) A method for producing barium ferrite magnetic powder, which comprises spraying a slurry mainly containing an aqueous barium hydroxide solution and iron oxide and/or iron hydroxide into a gas atmosphere at 700°C or higher and thermally decomposing it.
化鉄とを主として含むスラリーを７００℃以上のガス雰
囲気中で火炎中に噴霧し、熱分解することを特徴とする
バリウムフェライト磁性粉末の製造方法。(2) Barium ferrite magnetic powder is produced by spraying a slurry mainly containing barium hydroxide aqueous solution and iron oxide and/or iron hydroxide into a flame in a gas atmosphere of 700°C or higher and thermally decomposing it. Production method.
項または第（２）項に記載のバリウムフェライトの製造
方法。(3) Claim (1) that the iron oxide is α-Fe_2O_3
The method for producing barium ferrite according to item (2) or item (2).
ばれた１種以上の化合物である請求項（１）〜（３）項
いずれかに記載のバリウムフェライトの製造方法。(4) The iron hydroxide according to any one of claims (1) to (3), wherein the iron hydroxide is one or more compounds selected from the group consisting of α-FeOOH, δ-FeOOH and Fe(OH)_3. Method for manufacturing barium ferrite.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2155241A JPH0448704A (en) | 1990-06-15 | 1990-06-15 | Manufacture of barium ferrite magnetic powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2155241A JPH0448704A (en) | 1990-06-15 | 1990-06-15 | Manufacture of barium ferrite magnetic powder |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0448704A true JPH0448704A (en) | 1992-02-18 |
Family
ID=15601622
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2155241A Pending JPH0448704A (en) | 1990-06-15 | 1990-06-15 | Manufacture of barium ferrite magnetic powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0448704A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008076666A (en) * | 2006-09-20 | 2008-04-03 | Fuji Electric Holdings Co Ltd | Driving circuit for organic el element |
| JP2009200186A (en) * | 2008-02-20 | 2009-09-03 | Tdk Corp | Method of manufacturing sintered magnet |
| JP2013017957A (en) * | 2011-07-12 | 2013-01-31 | Furukawa Electric Co Ltd:The | Apparatus and method for manufacturing fine particle |
-
1990
- 1990-06-15 JP JP2155241A patent/JPH0448704A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008076666A (en) * | 2006-09-20 | 2008-04-03 | Fuji Electric Holdings Co Ltd | Driving circuit for organic el element |
| JP2009200186A (en) * | 2008-02-20 | 2009-09-03 | Tdk Corp | Method of manufacturing sintered magnet |
| JP4716051B2 (en) * | 2008-02-20 | 2011-07-06 | Ｔｄｋ株式会社 | Manufacturing method of sintered magnet |
| JP2013017957A (en) * | 2011-07-12 | 2013-01-31 | Furukawa Electric Co Ltd:The | Apparatus and method for manufacturing fine particle |
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