JPH0616446B2 - Method for producing metallic magnetic powder - Google Patents
Method for producing metallic magnetic powderInfo
- Publication number
- JPH0616446B2 JPH0616446B2 JP60069177A JP6917785A JPH0616446B2 JP H0616446 B2 JPH0616446 B2 JP H0616446B2 JP 60069177 A JP60069177 A JP 60069177A JP 6917785 A JP6917785 A JP 6917785A JP H0616446 B2 JPH0616446 B2 JP H0616446B2
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- JP
- Japan
- Prior art keywords
- magnetic powder
- surface area
- specific surface
- feooh
- metal
- Prior art date
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- Hard Magnetic Materials (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、高い抗磁力及び飽和磁束密度が要求される高
密度記録用磁気記録媒体に用いて好適な金属磁性粉末の
製造方法に関するものである。TECHNICAL FIELD The present invention relates to a method for producing a metal magnetic powder suitable for use in a magnetic recording medium for high density recording, which requires high coercive force and saturation magnetic flux density. is there.
〔発明の概要〕 本発明は、オキシ水酸化鉄を還元して金属磁性粉末を製
造するにあたり、原料として枝分かれのないγ−ＦｅＯ
ＯＨ（レピッドクロサイト）を用いるとともに、これを
脱水して得られる多孔質状態のγ−Ｆｅ２Ｏ３表面に金
属の水酸化物，酸化物または複合酸化物を被着させ、還
元時の形状の崩れを改善し、針状性を損なうことなく高
い比表面積を有する金属磁性粉末を得ようとするもので
ある。[Outline of the Invention] In the present invention, in the production of metal magnetic powder by reducing iron oxyhydroxide, γ-FeO having no branching as a raw material is used.
While using OH (lepid crosite), a metal hydroxide, oxide or composite oxide is deposited on the surface of porous γ-Fe 2 O 3 obtained by dehydrating the OH (lepid crosite), and It is intended to improve the shape collapse and obtain a metal magnetic powder having a high specific surface area without impairing the acicularity.
磁気テープや磁気ディスク等の磁気記録媒体としては、
ポリエステルフィルム等の非磁性支持体上に、強磁性体
の微粉末である磁性粉や樹脂結合剤，有機溶剤，各種添
加剤等を混合分散して調製される磁性塗料を塗布して磁
性層を形成した、いわゆる塗布型の磁気記録媒体が多用
されている。そして、この種の磁気記録媒体にあって
は、高密度記録化に対応し高性能化を図るために、抗磁
力Ｈｃの大きなＦｅ，Ｎｉ，Ｃｏ等の強磁性金属あるい
は合金の粉末（金属磁性粉末）が磁性粉として使われる
ようになっている。As magnetic recording media such as magnetic tapes and magnetic disks,
The magnetic layer is formed by coating a magnetic coating material prepared by mixing and dispersing magnetic powder, which is a fine powder of ferromagnetic material, resin binder, organic solvent, various additives, etc., on a non-magnetic support such as polyester film. The formed so-called coating type magnetic recording medium is often used. In this type of magnetic recording medium, in order to cope with high density recording and to improve performance, powder of ferromagnetic metal or alloy such as Fe, Ni, Co having a large coercive force Hc (metal magnetism) is used. Powder) is used as a magnetic powder.
この金属磁性粉末の製造方法としては、種々の方法があ
るが、例えば特開昭５７−６３６０５号公報や特開昭５
７−６３６０６号公報等に記載されるように、オキシ水
酸化鉄を水素等の還元性気流中で還元する還元法が実用
的な方法として知られている。There are various methods for producing the metallic magnetic powder, and for example, JP-A-57-63605 and JP-A-5-63605.
As described in 7-63606, etc., a reduction method of reducing iron oxyhydroxide in a reducing gas stream such as hydrogen is known as a practical method.
ところで、上述の還元法による場合、原料であるオキシ
水酸化鉄の選択が難しい。すなわち、上記オキシ水酸化
鉄としては、α−ＦｅＯＯＨ（ゲータイト）やγ−Ｆｅ
ＯＯＨ（レピッドクロサイト）等が知られているが、α
−ＦｅＯＯＨは枝分かれが発生し易い結晶で、これを出
発原料とする場合には、この枝分かれが焼結の原因とな
り易い。一方、γ−ＦｅＯＯＨは枝分かれのない良好な
針状性を有する粒子であるが、これを出発原料とする場
合には、還元時に形状が崩れ易い。特に、粒子の微細化
を図り比表面積を大きくしていくと、この傾向が顕著で
ある。By the way, in the case of the above-mentioned reduction method, it is difficult to select iron oxyhydroxide as a raw material. That is, as the iron oxyhydroxide, α-FeOOH (goethite) or γ-Fe
OOH (Lepid Crosite) is known, but α
-FeOOH is a crystal in which branching easily occurs, and when this is used as a starting material, this branching easily causes sintering. On the other hand, γ-FeOOH is a particle having good acicularity without branching, but when it is used as a starting material, the shape is likely to collapse during reduction. In particular, this tendency is remarkable when the particles are made finer and the specific surface area is increased.
そこで本発明は、上述のような実情に鑑みて提案された
ものであって、比表面積が大きく、針状性が良好で、優
れた磁気特性を発揮する金属磁性粉末を得ることが可能
な金属磁性粉末の製造方法を提供することを目的とす
る。Therefore, the present invention has been proposed in view of the above circumstances, a metal having a large specific surface area, good acicularity, and a metal magnetic powder that exhibits excellent magnetic properties can be obtained. It is an object to provide a method for producing magnetic powder.
本発明者は、上述の如き目的を達成せんものと長期に亘
り鋭意研究の結果、γ−ＦｅＯＯＨは脱水のみにより針
状性を保持したまま多孔質（マイクロポーラス）なγ−
Ｆｅ２Ｏ３に容易に変換することができ、さらにこのγ
−Ｆｅ２Ｏ３金属酸化物等または水酸化物を被着するこ
とにより結晶を補強することができ、還元時に形状の崩
れが生ずることがなく微細な金属磁性粉末を作成するこ
とができることを見出し本発明を完成するに至ったもの
であって、γ−ＦｅＯＯＨを１５０〜２５０℃で脱水し
比表面積が６０〜２５０m2／ｇの多孔質なγ−Ｆｅ２Ｏ
３を得、このγ−Ｆｅ２Ｏ３表面にＣｏ，Ｎｉ，Ｆｅ，
Ｚｎ，Ｓｎ，Ｔｉ，Ａｌ，Ｃｒ，Ｃｕ及びＭｎの水酸化
物，酸化物または複合酸化物から選ばれた化合物を被着
した後、還元性気流中で還元することを特徴とするもの
である。As a result of earnest research over a long period of time, the inventors of the present invention have achieved the above-mentioned object, and as a result, γ-FeOOH has a porous (microporous) γ-position while maintaining the acicularity only by dehydration.
It can be easily converted to Fe 2 O 3 , and this γ
It was found that the crystal can be reinforced by depositing —Fe 2 O 3 metal oxide or the like or hydroxide, and a fine metal magnetic powder can be produced without causing shape collapse during reduction. The present invention has been completed, and γ-FeOOH was dehydrated at 150 to 250 ° C. to form a porous γ-Fe 2 O having a specific surface area of 60 to 250 m 2 / g.
3 give, Co in the gamma-Fe 2 O 3 surface, Ni, Fe,
It is characterized in that a compound selected from hydroxides, oxides or complex oxides of Zn, Sn, Ti, Al, Cr, Cu and Mn is deposited and then reduced in a reducing air flow. .
本発明においては、先ず、出発原料としてγ−ＦｅＯＯ
Ｈ（レピッドクロサイト）を用意する。In the present invention, first, γ-FeOO is used as a starting material.
Prepare H (Rapid Crosite).
このγ−ＦｅＯＯＨの結晶は、Ｆｅ（ＯＨ）２を２０〜
３０℃で酸化することにより形成される。このとき、水
ガラス（Ｓｉ０．５〜１．０原子％）を加えておけば、
得られるγ−ＦｅＯＯＨの粒子サイズを極めて微細にコ
ントロールすることができる。ここでは、後述のγ−Ｆ
ｅ２Ｏ３に変換したときに、このγ−Ｆｅ２Ｏ３の比表
面積が６０〜２５０ｍ2／ｇとなるようにする。This γ-FeOOH crystal has a Fe (OH) 2 content of 20-
It is formed by oxidation at 30 ° C. At this time, if water glass (Si 0.5 to 1.0 atomic%) is added,
The particle size of the obtained γ-FeOOH can be controlled extremely finely. Here, γ-F described later
When converted to e 2 O 3 , the specific surface area of γ-Fe 2 O 3 is set to 60 to 250 m 2 / g.
次に、このγ−ＦｅＯＯＨを、１５０〜２５０℃程度の
比較的低温で脱水することにより、γ−Ｆｅ２Ｏ３に変
換する。生成するγ−Ｆｅ２Ｏ３粒子は、γ−ＦｅＯＯ
Ｈの針状性が維持され、極めて多数の微細孔（マイクロ
ポア）を有する。Next, this γ-FeOOH is converted to γ-Fe 2 O 3 by dehydration at a relatively low temperature of about 150 to 250 ° C. The γ-Fe 2 O 3 particles produced are γ-FeOO
The acicularity of H is maintained and it has an extremely large number of micropores.
このように、γ−ＦｅＯＯＨは脱水により容易にマイク
ロポアをもったγ−Ｆｅ２Ｏ３となる。一方、α−Ｆｅ
ＯＯＨ、脱水のみでは、α−Ｆｅ２Ｏ３となる。このγ
−Ｆｅ２Ｏ３は、α−Ｆｅ２Ｏ３に比較して、コバルト
フェライト等のピネル型化合物の被着が可能になるとい
う利点がある。Thus, γ-FeOOH easily becomes γ-Fe 2 O 3 having micropores by dehydration. On the other hand, α-Fe
OOH and dehydration alone produce α-Fe 2 O 3 . This γ
-Fe 2 O 3 has an advantage over the α-Fe 2 O 3 in that a pinel type compound such as cobalt ferrite can be deposited.
そして、このような多孔質のγ−Ｆｅ２Ｏ３粒子に対
し、金属の水酸化物，酸化物または複合酸化物のうち１
種以上を被着し、上記γ−Ｆｅ２Ｏ３粒子のマイクロポ
アにこれら化合物を充填するとともにその表面を被覆す
る。Then, for such a porous γ-Fe 2 O 3 particle, one of metal hydroxides, oxides or composite oxides is used.
One or more seeds are applied, and the micropores of the γ-Fe 2 O 3 particles are filled with these compounds and the surface thereof is coated.
上記金属の水酸化物，酸化物または複合酸化物として
は、Ｃｏ，Ｎｉ，Ｆｅ，Ｚｎ，Ｓｎ，Ｔｉ，Ａｌ，Ｃ
ｒ，Ｃｕ及びＭｎの水酸化物，酸化物または複合酸化物
が使用可能である。Examples of hydroxides, oxides or complex oxides of the above metals include Co, Ni, Fe, Zn, Sn, Ti, Al and C.
Hydroxides, oxides or complex oxides of r, Cu and Mn can be used.
なお、上述の金属の水酸化物，酸化物または複合酸化物
を被着した後、さらにこれらの化合物上をケイ素化合物
（例えば水ガラス等）で被覆して、後述の還元工程時の
焼結（シンタリング）を防止するようにしてもよい。In addition, after depositing the above-mentioned metal hydroxide, oxide, or composite oxide, further coating these compounds with a silicon compound (for example, water glass, etc.), and sintering at the time of the reduction step described later ( (Sintering) may be prevented.
最後に、上述の化合物を被着したγ−Ｆｅ２Ｏ３粒子
を、例えば水素ガス等の還元性ガスの気流下で還元して
金属磁性粉末を得る。この還元の温度条件としては、３
７５〜４５０℃程度である。Finally, the γ-Fe 2 O 3 particles coated with the above compound are reduced under a stream of a reducing gas such as hydrogen gas to obtain metallic magnetic powder. The temperature condition for this reduction is 3
It is about 75 to 450 ° C.
上記γ−Ｆｅ２Ｏ３粒子は、多数のマイクロポアを有す
るが、これらマイクロポア中には上述の金属の水酸化
物，酸化物または複合酸化物が充填され補強されている
ので、たとえ比表面積が大きな粒子であってもこの還元
時にその形状が崩れることはなく、良好な針状性を有す
る微細な金属磁性粉末を製造することができる。The γ-Fe 2 O 3 particles have a large number of micropores, and since these micropores are filled with and reinforced with the above-mentioned metal hydroxides, oxides or complex oxides, even if the specific surface area is Even if it is a large particle, its shape does not collapse during this reduction, and it is possible to produce a fine metal magnetic powder having good acicularity.
このように、金属磁性粉末の原料としてγ−ＦｅＯＯＨ
（レピッドクロサイト）を用い、これを脱水してマイク
ロポアを有するγ−Ｆｅ２Ｏ３に変換し、このマイクロ
ポア中に金属の水酸化物，酸化物または複合酸化物を充
填して結晶を補強しているので、還元時に比表面積の大
きな微細粒子であっても形状の崩れが生ずることはな
く、針状性は維持される。As described above, γ-FeOOH is used as the raw material of the metallic magnetic powder.
(Lepid crosite) is dehydrated and converted into γ-Fe 2 O 3 having micropores, and the micropores are filled with a metal hydroxide, oxide or composite oxide to be crystallized. Since it reinforces, even if it is fine particles having a large specific surface area, the shape of the fine particles does not collapse, and the acicularity is maintained.
以下、本発明の具体的な実施例について説明するが、本
発明はこれら実施例に限定されるものではない。Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.
実施例１． 比表面積が１３０ｍ2／ｇのγ−ＦｅＯＯＨを温度２２
０℃，窒素Ｎ２気流中で３時間脱水し、マイクロポーラ
スなγ−Ｆｅ２Ｏ３粒子を得た。得られた粒子の比表面
積は１５０m2／ｇであった。Example 1. Γ-FeOOH having a specific surface area of 130 m 2 / g was used at a temperature of 22
It was dehydrated at 0 ° C. in a nitrogen N 2 stream for 3 hours to obtain microporous γ-Fe 2 O 3 particles. The specific surface area of the obtained particles was 150 m 2 / g.
つづいて、このγ−Ｆｅ２Ｏ３粒子をＮａＯＨ溶液（５
Ｎ）中に分散し、Ｃｏ５原子％相当の塩化コバルト（Ｃ
ｏＣｌ２）を投入し、１００℃で１時間加熱撹拌した。Subsequently, the γ-Fe 2 O 3 particles were mixed with a NaOH solution (5
Cobalt chloride (C) equivalent to 5 atomic% Co
oCl 2 ) was added and the mixture was heated with stirring at 100 ° C. for 1 hour.
これを洗浄後、焼結防止のために水ガラス（ＪＩＳ−１
号）をＳｉが６原子％となるように投入し、ｐＨを７〜
８に調整して激しく撹拌した。After washing this, water glass (JIS-1
No.) so that Si is 6 atomic%, and the pH is 7 to
It was adjusted to 8 and stirred vigorously.
さらに、洗浄，濾過，乾燥し、温度５００℃，Ｎ２雰囲
気中で焼結した後、水素Ｈ２気流中で温度４００℃の条
件で４時間還元し、金属磁性粉末を得た。Further, after washing, filtering and drying, sintering in a N 2 atmosphere at a temperature of 500 ° C., reduction was carried out in a hydrogen H 2 stream at a temperature of 400 ° C. for 4 hours to obtain a magnetic metal powder.
実施例２． 比表面積が６８m2／ｇのγ−ＦｅＯＯＨを温度２８０
℃，窒素Ｎ２気流中で１時間脱水し、マイクロポーラス
なγ−Ｆｅ２Ｏ３粒子を得た。得られた粒子の比表面積
は１００m2／ｇであった。Example 2. Γ-FeOOH having a specific surface area of 68 m 2 / g is heated at a temperature of 280
Dehydration was carried out in a nitrogen N 2 stream at 1 ° C. for 1 hour to obtain microporous γ-Fe 2 O 3 particles. The specific surface area of the obtained particles was 100 m 2 / g.
つづいて、このγ−Ｆｅ２Ｏ３粒子をＮａＯＨ溶液（５
Ｎ）中に分散し、Ｃｏ１０原子％相当のＣｏＦｅ２Ｏ３
ができるように塩化コバルト（ＣｏＣｌ２）及び塩化第
１鉄（ＦｅＣｌ２）を投入し、１００℃で１時間加熱撹
拌した。Subsequently, the γ-Fe 2 O 3 particles were mixed with a NaOH solution (5
N), CoFe 2 O 3 equivalent to 10 atomic% of Co
Cobalt chloride (CoCl 2 ) and ferrous chloride (FeCl 2 ) were added thereto so that the mixture was heated and stirred at 100 ° C. for 1 hour.
これを洗浄後、焼結防止のために水ガラス（ＪＩＳ−１
号）をＳｉが６原子％となるように投入し、ｐＨを７〜
８に調整して激しく撹拌した。After washing this, water glass (JIS-1
No.) so that Si is 6 atomic%, and the pH is 7 to
It was adjusted to 8 and stirred vigorously.
さらに、洗浄，濾過，乾燥し、温度５００℃，Ｎ２雰囲
気中で焙焼した後、水素Ｈ２気流中で温度４００℃の条
件で４時間還元し、金属磁性粉末を得た。Further, after washing, filtering and drying, roasting in a N 2 atmosphere at a temperature of 500 ° C., reduction was carried out in a hydrogen H 2 stream at a temperature of 400 ° C. for 4 hours to obtain a metal magnetic powder.
実施例３． 比表面積が１３０m2／ｇのγ−ＦｅＯＯＨを温度２２０
℃，窒素Ｎ２気流中で２時間脱水し、マイクロポーラス
なγ−Ｆｅ２Ｏ３粒子を得た。得られた粒子の比表面積
は１６０m2／ｇであった。Example 3. Γ-FeOOH having a specific surface area of 130 m 2 / g is used at a temperature of 220
Dehydration was carried out in a nitrogen N 2 gas stream at a temperature of 2 ° C. for 2 hours to obtain microporous γ-Fe 2 O 3 particles. The specific surface area of the obtained particles was 160 m 2 / g.
つづいて、このγ−Ｆｅ２Ｏ３粒子をＮａＯＨ溶液（５
Ｎ）中に分散し、Ｃｏ５原子％相当の塩化コバルト（Ｃ
ｏＣｌ２）を投入し、１００℃で１時間加熱撹拌した。Subsequently, the γ-Fe 2 O 3 particles were mixed with a NaOH solution (5
Cobalt chloride (C) equivalent to 5 atomic% Co
oCl 2 ) was added and the mixture was heated with stirring at 100 ° C. for 1 hour.
これを洗浄後、焼結防止のために水ガラス（ＪＩＳ−１
号）をＳｉが６原子％となるように投入し、ｐＨを７〜
８に調整して激しく撹拌した。After washing this, water glass (JIS-1
No.) so that Si is 6 atomic%, and the pH is 7 to
It was adjusted to 8 and stirred vigorously.
さらに、洗浄，濾過，乾燥し、温度５００℃，Ｎ２雰囲
気中で焙焼した後、水素Ｈ２気流中で温度３７０℃の条
件で４時間還元し、金属磁性粉末を得た。Further, after washing, filtering and drying, roasting in a N 2 atmosphere at a temperature of 500 ° C., reduction was carried out in a hydrogen H 2 stream at a temperature of 370 ° C. for 4 hours to obtain a metal magnetic powder.
比較例． 比表面積９５m2／ｇのγ−ＦｅＯＯＨに対し、脱水をせ
ずにそのまま水ガラスによる表面処理を施した。Comparative example. Γ-FeOOH having a specific surface area of 95 m 2 / g was directly subjected to surface treatment with water glass without dehydration.
次いで、水素気流中，温度４００℃で還元し、金属磁性
酸化物を得た。Then, it was reduced in a hydrogen stream at a temperature of 400 ° C. to obtain a metal magnetic oxide.
上述の各実施例及び比較例で得られた金属磁性粉末につ
いて、磁気特性及び比表面積を測定した。結果を次表に
示す。The magnetic properties and the specific surface area of the metal magnetic powders obtained in each of the above Examples and Comparative Examples were measured. The results are shown in the table below.
この表より、本発明の各実施例では、比表面積の極めて
大きな金属磁性粉末が得られ、特に、実施例３において
は、従来の方法では考えられないような大きな比表面積
が達成されたことがわかる。また、各実施例で得られた
金属磁性粉末は、磁気特性にも優れ、針状性も良好なも
のであった。 From this table, in each of the examples of the present invention, a metal magnetic powder having an extremely large specific surface area was obtained, and in particular, in Example 3, a large specific surface area that could not be considered by the conventional method was achieved. Recognize. Further, the metal magnetic powders obtained in the respective examples were also excellent in magnetic properties and had good acicularity.
以上の説明からも明らかなように、本発明によれば、金
属磁性粉末の原料としてγ−ＦｅＯＯＨ（レピッドクロ
サイト）を用い、（これを脱水してマイクロポアを有す
るγ−Ｆｅ２Ｏ３に変換し、このマイクロポア中に金属
の水酸化物，酸化物または複合酸化物を充填して結晶を
補強した後、還元しているので、還元時に形状の崩れが
発生することがなく、γ−ＦｅＯＯＨの有する良好な針
状性を維持したまま比表面積の大きな金属磁性粉末を製
造することができる。As is clear from the above description, according to the present invention, γ-FeOOH (rapid crosite) is used as a raw material of the metallic magnetic powder (γ-Fe 2 O 3 having micropores by dehydrating this). The micropores are filled with metal hydroxides, oxides or composite oxides to reinforce the crystal and then reduced, so that the shape of the micropores does not collapse during the reduction. It is possible to produce a metal magnetic powder having a large specific surface area while maintaining the good acicularity of —FeOOH.
この際、金属磁性粉末の磁気特性を損なうこともなく、
特に例えばコバルトフェライト等のスピネル型化合物や
水酸化コバルト等を用いれば、磁気特性の向上を図るこ
ともできる。At this time, without impairing the magnetic properties of the magnetic metal powder,
In particular, if spinel type compounds such as cobalt ferrite and cobalt hydroxide are used, the magnetic properties can be improved.
Claims (1)
し比表面積が６０〜２５０m2／ｇの多孔質なγ−Ｆｅ２
Ｏ３を得、 このγ−Ｆｅ２Ｏ３表面にＣｏ，Ｎｉ，Ｆｅ，Ｚｎ，Ｓ
ｎ，Ｔｉ，Ａｌ，Ｃｒ，Ｃｕ及びＭｎの水酸化物，酸化
物または複合酸化物から選ばれた化合物を被着した後、 還元性気流中で還元することを特徴とする金属磁性粉末
の製造方法。1. Porous γ-Fe 2 having a specific surface area of 60 to 250 m 2 / g obtained by dehydrating γ-FeOOH at 150 to 250 ° C.
O 3 was obtained, and Co, Ni, Fe, Zn, S were formed on the surface of γ-Fe 2 O 3.
Production of metal magnetic powder characterized by depositing a compound selected from hydroxides, oxides or complex oxides of n, Ti, Al, Cr, Cu and Mn, followed by reduction in a reducing air stream Method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60069177A JPH0616446B2 (en) | 1985-04-03 | 1985-04-03 | Method for producing metallic magnetic powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60069177A JPH0616446B2 (en) | 1985-04-03 | 1985-04-03 | Method for producing metallic magnetic powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61229305A JPS61229305A (en) | 1986-10-13 |
| JPH0616446B2 true JPH0616446B2 (en) | 1994-03-02 |
Family
ID=13395175
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60069177A Expired - Fee Related JPH0616446B2 (en) | 1985-04-03 | 1985-04-03 | Method for producing metallic magnetic powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0616446B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1045135C (en) * | 1994-03-07 | 1999-09-15 | 中国科学院山西煤炭化学研究所 | Gama Fe2O3 magnetic powder prepn. method |
| JP2010083719A (en) * | 2008-09-30 | 2010-04-15 | Dowa Metals & Mining Co Ltd | Porous maghemite, method for producing tmaghemite and method for treating water to be treated |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5233319B2 (en) * | 1973-01-12 | 1977-08-27 | ||
| JPS52135895A (en) * | 1976-05-09 | 1977-11-14 | Toda Kogyo Corp | Process for preparing cobaltt modified acicular crystal magnetic ironoxide particle |
| JPS5853045B2 (en) * | 1980-10-01 | 1983-11-26 | 関東電化工業株式会社 | Manufacturing method of magnetic powder |
| JPS5932105A (en) * | 1982-08-17 | 1984-02-21 | Mitsui Toatsu Chem Inc | Novel method of manufacturing ferromagnetic iron powder |
| JPS59103310A (en) * | 1982-10-06 | 1984-06-14 | Ishihara Sangyo Kaisha Ltd | Manufacture of cobalt-containing magnetic iron oxide |
-
1985
- 1985-04-03 JP JP60069177A patent/JPH0616446B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61229305A (en) | 1986-10-13 |
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