JPH0831366B2 - Ferromagnetic metal powder and method for producing the same - Google Patents
Ferromagnetic metal powder and method for producing the sameInfo
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- JPH0831366B2 JPH0831366B2 JP62164277A JP16427787A JPH0831366B2 JP H0831366 B2 JPH0831366 B2 JP H0831366B2 JP 62164277 A JP62164277 A JP 62164277A JP 16427787 A JP16427787 A JP 16427787A JP H0831366 B2 JPH0831366 B2 JP H0831366B2
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- cobalt
- metal powder
- ferromagnetic metal
- layer
- iron
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は磁気記録に用いられる強磁性金属粉末及びそ
の製造方法に関し、特に安定性の向上を目指した強磁性
金属粉末及びその製造方法に関するものである。Description: TECHNICAL FIELD The present invention relates to a ferromagnetic metal powder used for magnetic recording and a method for producing the same, and more particularly to a ferromagnetic metal powder for improving stability and a method for producing the same. Is.
〔従来の技術及びその問題点〕 近年、各種の記録方式の発展は著しいものがあるが、
中でも磁気記録再生装置の小型軽量化の進歩は顕著であ
る。これにつれて磁気テープや磁気ディスク等の磁気記
録媒体に対する高性能化の要求が大きくなってきてい
る。磁気記録に対するこのような要求を満足するために
は高い保磁力と高い飽和磁化を有する磁性粉末が必要で
ある。[Prior Art and its Problems] In recent years, various recording systems have been remarkably developed,
In particular, the progress in reducing the size and weight of the magnetic recording / reproducing apparatus is remarkable. Along with this, there is an increasing demand for higher performance of magnetic recording media such as magnetic tapes and magnetic disks. In order to satisfy such requirements for magnetic recording, magnetic powder having high coercive force and high saturation magnetization is required.
従来、磁気記録用の磁性粉末として一般には針状のマ
グネタイトやマグヘマイト又はこれらの磁性酸化鉄粉末
をコバルトで変性したいわゆるコバルト含有酸化鉄が用
いられているが、より高出力の媒体を得るためにはより
高い保磁力と飽和磁化を持つ強磁性金属粉末いわゆるメ
タル粉が用いられ始めている。Conventionally, as magnetic powder for magnetic recording, generally needle-shaped magnetite or maghemite or so-called cobalt-containing iron oxide obtained by modifying these magnetic iron oxide powders with cobalt is used, but in order to obtain a medium with higher output. Ferromagnetic metal powders with higher coercive force and saturation magnetization, so-called metal powders, have begun to be used.
しかし、この強磁性金属粉末は化学的に不安定である
ため酸化を受け、時間の経過と共に飽和磁化と保磁力が
低下するという欠点がある。このような強磁性金属粉末
を用いて磁気記録媒体を作った場合に、高密度記録は可
能となるものの、長期保存するうちに記録内容の逸失や
変質を起こし、記録媒体として極めて致命的な欠陥を生
むこととなる。このような欠点を解決しようとして合金
化或いは表面保護層の形成等多くの提案がなされている
が、保磁力、飽和磁化等の磁気特性と耐酸化安定性を同
時に満足できる結果はまだ得られていない。However, this ferromagnetic metal powder has the drawback that it is chemically unstable and is therefore oxidized, and its saturation magnetization and coercive force decrease over time. When a magnetic recording medium is manufactured using such a ferromagnetic metal powder, high density recording is possible, but the recorded contents are lost or deteriorated during long-term storage, and a very fatal defect as a recording medium. Will be born. Although many proposals such as alloying or formation of a surface protective layer have been made in order to solve such drawbacks, results that magnetic properties such as coercive force and saturation magnetization and oxidation stability can be satisfied at the same time have not yet been obtained. Absent.
本発明は以上のような従来技術の問題点を解決するた
めになされたもので、耐酸化安定性の優れた強磁性金属
粉末とこれを得るための製造法を提供し、併せて高出力
かつ高記録密度の、安定性の優れた磁気記録媒体を提供
することを目的とするものである。The present invention has been made in order to solve the problems of the prior art as described above, and provides a ferromagnetic metal powder having excellent oxidation resistance stability and a manufacturing method for obtaining the same, and also provides high output and It is an object of the present invention to provide a magnetic recording medium having a high recording density and excellent stability.
鉄を主成分とする強磁性金属粉末をコバルト、ニッケ
ル等の遷移金属と合金化することにより耐酸化性が改善
されることは良く知られているが、遷移金属が多くなる
と鉄本来の磁気特性が失われ高保磁力、高飽和磁化の両
者を満足できるものは得られないのが実情である。It is well known that the oxidation resistance is improved by alloying a ferromagnetic metal powder containing iron as a main component with a transition metal such as cobalt or nickel. In reality, it is not possible to obtain a material that satisfies both high coercive force and high saturation magnetization.
そこで、強磁性金属粉末の前駆体である酸化鉄を主成
分とする酸化物の表面に遷移金属を含む層を形成した
後、この酸化物粉末を還元して表面のみを合金化する方
法も提案されているが、十分な磁気特性と耐酸化性を満
足するものは得られていない。Therefore, we also proposed a method of forming a layer containing a transition metal on the surface of an oxide containing iron oxide as a precursor of a ferromagnetic metal powder, and then reducing the oxide powder to alloy only the surface. However, no one satisfying sufficient magnetic characteristics and oxidation resistance has been obtained.
本発明者等はこの合金層の形成方法により、得られた
強磁性金属粉末の耐酸化性が大きく異なることを見出し
た。また前駆体即ち、その表面に特定条件で形成した遷
移金属含有層を有する酸化鉄粉末を還元することによっ
て、優れた耐酸化性を有する、鉄を主成分とする強磁性
金属粉末が得られることを見出し、既に特許出願済みで
ある（特願昭61−206534号）。The present inventors have found that the oxidation resistance of the obtained ferromagnetic metal powder varies greatly depending on the method of forming the alloy layer. Further, a precursor, that is, an iron oxide-based ferromagnetic metal powder having excellent oxidation resistance can be obtained by reducing an iron oxide powder having a transition metal-containing layer formed on its surface under specific conditions. Has already been applied for a patent (Japanese Patent Application No. 61-206534).
ここで本発明者らは、更に検討を重ねた結果、表面合
金層にアルカリ土類金属を導入することにより従来以上
に磁気特性、耐酸化性が向上することを見出し本発明の
完成に至った。Here, as a result of further studies, the present inventors have found that the introduction of alkaline earth metal into the surface alloy layer improves the magnetic characteristics and the oxidation resistance more than before, and has completed the present invention. .
即ち、本発明は、実質的に鉄からなる強磁性金属粉末
の表面に、コバルトの層を有し、その上にマグネシウム
又はカルシウムから選ばれるアルカリ土類金属元素の層
を有することを特徴とする磁気記録用強磁性金属粉末を
提供するものであり、更に本発明は、実質的に酸化鉄か
らなる酸化物粉末を、ａ）コバルトの塩、又は第一鉄塩
及びコバルトの塩と、ｂ）アルカリとを含む水溶液中で
処理し、表面にコバルト化合物の層を形成せしめた後、
ｃ）マグネシウム又はカルシウムから選ばれるアルカリ
土類金属元素の塩を含む水溶液を加え、コバルト化合物
の層の上にアルカリ土類金属元素化合物の層を有する酸
化物を得、これを還元して、実質的に鉄からなる粒子表
面にコバルトの層を形成させ、更にその上にマグネシウ
ム又はカルシウムから選ばれるアルカリ土類金属元素の
層を形成させることを特徴とする磁気記録用強磁性金属
粉末の製造方法を提供するものである。That is, the present invention is characterized by having a layer of cobalt on the surface of a ferromagnetic metal powder consisting essentially of iron, and having a layer of an alkaline earth metal element selected from magnesium or calcium thereon. The present invention provides a ferromagnetic metal powder for magnetic recording, and the present invention further comprises an oxide powder consisting essentially of iron oxide, a) a salt of cobalt, or a ferrous salt and a salt of cobalt, and b). After treatment in an aqueous solution containing an alkali to form a cobalt compound layer on the surface,
c) An aqueous solution containing a salt of an alkaline earth metal element selected from magnesium or calcium is added to obtain an oxide having a layer of an alkaline earth metal element compound on a layer of a cobalt compound, which is reduced to substantially Method for producing a ferromagnetic metal powder for magnetic recording, characterized in that a cobalt layer is formed on the surface of particles made of iron, and an alkaline earth metal element layer selected from magnesium or calcium is further formed thereon. Is provided.
本発明の強磁性金属粉末中のコバルトの量は鉄に対し
て２〜15重量％が好ましく、４〜10重量％が更に好まし
い。またアルカリ土類金属元素の量は鉄に対して0.05〜
５重量％が好ましく、0.1〜２重量％が更に好ましい。
コバルトおよびアルカリ土類金属元素の量が上記範囲よ
りも多くなると望ましい磁気特性が得難く、少ないと十
分な耐酸化性が得られない。The amount of cobalt in the ferromagnetic metal powder of the present invention is preferably 2 to 15% by weight, more preferably 4 to 10% by weight, based on iron. Also, the amount of alkaline earth metal element is 0.05-
It is preferably 5% by weight, more preferably 0.1 to 2% by weight.
If the amount of cobalt and alkaline earth metal elements is more than the above range, it is difficult to obtain desired magnetic properties, and if the amount is less than that, sufficient oxidation resistance cannot be obtained.
本発明で用いる酸化鉄としては、γ−Fe2O3、α−Fe2
O3、Fe3O4等が挙げられる。Examples of the iron oxide used in the present invention include γ-Fe 2 O 3 and α-Fe 2
Examples include O 3 and Fe 3 O 4 .
本発明において、コバルトの層の形成に用いるコバル
トの塩としては水溶性のものであれば対イオンは特に問
題とはならない。しかし、ハロゲン化物を用いた場合、
洗浄が不十分なまま還元すると残留ハロゲンにより酸化
が促進されるので洗浄を完全にする必要がある。その点
で硝酸塩、硫酸塩、酢酸塩等のハロゲンを含まない塩が
有利である。In the present invention, as the cobalt salt used for forming the cobalt layer, the counter ion is not a problem as long as it is water-soluble. However, when using a halide,
If reduction is carried out with insufficient cleaning, residual halogen accelerates oxidation, and therefore cleaning must be completed. In this respect, halogen-free salts such as nitrates, sulfates and acetates are advantageous.
本発明において、アルカリ土類金属元素含有層の形成
に用いるアルカリ土類金属元素の塩としては水溶性のも
のであれば対イオンは特に問題とはならない。しかし、
コバルトの塩と同様の理由から、アルカリ土類金属がマ
グネシウムであれば、硝酸塩、硫酸塩、酢酸塩等、また
カルシウムの場合であれば硝酸塩、酢酸塩等が有利であ
る。In the present invention, as the salt of the alkaline earth metal element used for forming the alkaline earth metal element-containing layer, the counter ion is not a problem as long as it is water-soluble. But,
For the same reason as the cobalt salt, if the alkaline earth metal is magnesium, nitrates, sulfates, acetates, etc., and in the case of calcium, nitrates, acetates, etc. are advantageous.
また、本発明の方法において、水溶液中のアルカリ濃
度は水１当たりアリカリ0.5〜５モルの範囲が好まし
い。Further, in the method of the present invention, the alkali concentration in the aqueous solution is preferably in the range of 0.5 to 5 mol per 1 water.
コバルトの層及びアルカリ土類金属の層の形成反応は
酸化鉄又は酸化鉄を主成分とする酸化物を懸濁したアル
カリ溶液にコバルトの塩又は第一鉄塩及びコバルトの塩
の水溶液を加えて反応せしめた後、アルカリ土類金属元
素の塩の水溶液を加えることにより行われる。この場
合、アルカリ土類金属元素の塩の水溶液を加える前に実
質的に非酸化性の雰囲気中で70℃以下で２〜15時間反応
を行った後、系の温度を80〜180℃に上げ更に反応を５
〜20時間続けることが望ましい。またアルカリ土類金属
元素の塩の水溶液を加えた後も実質的に非酸化性の雰囲
気中で70℃以下で２〜15時間反応を行った後、系の温度
を80〜100℃に上げ更に反応を５〜20時間続けることが
望ましい。The formation reaction of the cobalt layer and the alkaline earth metal layer is carried out by adding an aqueous solution of cobalt salt or ferrous salt and cobalt salt to an alkaline solution in which iron oxide or an oxide containing iron oxide as a main component is suspended. After the reaction, it is carried out by adding an aqueous solution of a salt of an alkaline earth metal element. In this case, before adding the aqueous solution of the salt of the alkaline earth metal element, the reaction is performed in a substantially non-oxidizing atmosphere at 70 ° C or lower for 2 to 15 hours, and then the system temperature is raised to 80 to 180 ° C. Further reaction 5
It is desirable to continue for ~ 20 hours. Also, after adding an aqueous solution of a salt of an alkaline earth metal element, the reaction is performed at 70 ° C or lower for 2 to 15 hours in a substantially non-oxidizing atmosphere, and then the system temperature is raised to 80 to 100 ° C. It is desirable to continue the reaction for 5-20 hours.
コバルト塩または第一鉄塩及びコバルト塩の水溶液の
添加は一回で行ってもよいが、二回以上に分けて行って
もよい。The aqueous solution of the cobalt salt or the ferrous salt and the cobalt salt may be added once, or may be added twice or more.
また、系内に分散剤その他の添加剤が含まれても差し
支えない。Further, the dispersant and other additives may be contained in the system.
本発明において、コバルト化合物の層及びアルカリ土
類金属元素化合物の層を有する酸化鉄又は酸化鉄を主成
分とする酸化物を還元する際の条件は特に限定されず、
従来の酸化鉄粉末の還元技法に見られる一般的な条件を
採用できる。In the present invention, the conditions for reducing iron oxide or an oxide containing iron oxide as a main component having a layer of a cobalt compound and a layer of an alkaline earth metal element compound are not particularly limited,
The general conditions found in conventional iron oxide powder reduction techniques can be employed.
本発明により、高保磁力及び高飽和磁化と、高い耐酸
化安定性とを併せ持った、磁気記録媒体用として極めて
優れた特性を持つ強磁性金属粉末を提供することができ
る。According to the present invention, it is possible to provide a ferromagnetic metal powder that has both high coercive force and high saturation magnetization and high oxidation resistance stability and that has extremely excellent properties for a magnetic recording medium.
以下、実施例により本発明を更に詳細に説明するが、
本発明はこれらの実施例に限定されるものではない。Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.
実施例１ ６％苛性ソーダ水溶液700gに針状γ−Fe2O3を100g加
えて得たスラリーにチッ素ガスを吹き込みながら硫酸コ
バルト７水塩33gを水160mlに溶解した溶液を加え、40℃
で６時間反応し、その後温度を上げリフラックスを６時
間行った。更にこのスラリーに硫酸マグネシウム７水塩
3.5gを水80mlに溶解した溶液を加え、リフラックスを６
時間行い、コバルト及びマグネシムウを含む酸化鉄を得
た。Example 1 To a slurry obtained by adding 100 g of acicular γ-Fe 2 O 3 to 700 g of a 6% aqueous sodium hydroxide solution, a solution of 33 g of cobalt sulfate heptahydrate in 160 ml of water was added while blowing nitrogen gas, and the mixture was added at 40 ° C.
Then, the temperature was raised and reflux was performed for 6 hours. Furthermore, magnesium sulfate heptahydrate was added to this slurry.
Add a solution of 3.5 g dissolved in 80 ml of water and add 6
This was carried out for a time to obtain iron oxide containing cobalt and magnesium.
このコバルトおよびマグネシウム含有酸化鉄10gを回
転式管状炉に入れ、水素ガスを流しながら400℃に４時
間保ち、強磁性金属粉末を得た。冷却後、オキシン0.1g
を含むトルエン約20mlを炉中に流し込みトルエンを浸漬
した状態で強磁性金属粉末を抜き出し、その後乾燥して
コバルトおよびマグネシウム含有強磁性金属粉末を得
た。10 g of this iron oxide containing cobalt and magnesium was put into a rotary tubular furnace and kept at 400 ° C. for 4 hours while flowing hydrogen gas to obtain a ferromagnetic metal powder. After cooling, 0.1 g of oxine
Approximately 20 ml of toluene containing the above was poured into a furnace, and the ferromagnetic metal powder was extracted while the toluene was immersed, and then dried to obtain a cobalt- and magnesium-containing ferromagnetic metal powder.
得られた強磁性金属粉末中の鉄に対するコバルトの含
有量（以下Co/Feと略記する）は５重量％、鉄に対する
マグネシウムの含有量（以下Mg/Feと略記する）は１重
量％であった。The content of cobalt with respect to iron (hereinafter abbreviated as Co / Fe) in the obtained ferromagnetic metal powder was 5% by weight, and the content of magnesium with respect to iron (hereinafter abbreviated as Mg / Fe) was 1% by weight. It was
上記のようにして得た乾燥強磁性金属粉末を用い発火
点測定および加熱安定性試験を行った。Using the dried ferromagnetic metal powder obtained as described above, ignition point measurement and heating stability test were performed.
発火点の測定はアルミナを標準試料、乾燥強磁性金属
粉末を測定試料として理学電機（株）製熱分析装置を用
い昇温速度10℃／分で示差熱測定を行い、試料が急に発
熱する温度をもって発火点とした。The ignition point is measured using alumina as a standard sample and dry ferromagnetic metal powder as a measurement sample, using a thermal analyzer made by Rigaku Denki Co., Ltd., at a heating rate of 10 ° C./min. The temperature was taken as the ignition point.
加熱安定性試験は乾燥強磁性金属粉末を60℃、90％RH
に保存し、経時的に飽和磁束密度を測定することにより
行った。The heating stability test was performed using dry ferromagnetic metal powder at 60 ° C and 90% RH.
The measurement was performed by measuring the saturated magnetic flux density over time.
発火点測定の結果を表１に、加熱安定性試験の結果を
第１図に示す。The results of the ignition point measurement are shown in Table 1, and the results of the heating stability test are shown in FIG.
実施例２〜４ 実施例１において硫酸コバルト７水塩、硫酸マグネシ
ウム７水塩の量を変えて、コバルト及びマグネシウムの
含量の異なる酸化鉄を得、実施例１と同様にして強磁性
金属粉末を得た。Examples 2 to 4 Iron oxides having different cobalt and magnesium contents were obtained by changing the amounts of cobalt sulfate heptahydrate and magnesium sulfate heptahydrate in Example 1, and ferromagnetic metal powder was prepared in the same manner as in Example 1. Obtained.
得られた強磁性金属粉末について、実施例１と同様に
発火点測定および加熱安定性試験を行った。The obtained ferromagnetic metal powder was subjected to ignition point measurement and heating stability test in the same manner as in Example 1.
強磁性金属粉末中のコバルト及びマグネシウムの含量
及び発火点測定の結果を表１に、加熱安定性試験の結果
を第１図に示す。Table 1 shows the results of measuring the contents of cobalt and magnesium in the ferromagnetic metal powder and the ignition point, and FIG. 1 shows the results of the heating stability test.
比較例１ 実施例１において硫酸マグネシウム７水塩の水溶液を
加えることなくリフラックスを12時間行ってコバルト含
有酸化鉄を得、実施例１と同様に還元を行ってコバルト
含有強磁性金属粉末を得た。Comparative Example 1 In Example 1, reflux was performed for 12 hours without adding an aqueous solution of magnesium sulfate heptahydrate to obtain cobalt-containing iron oxide, and reduction was performed in the same manner as in Example 1 to obtain cobalt-containing ferromagnetic metal powder. It was
得られた強磁性金属粉末について、実施例１と同様に
発火点測定および加熱安定性試験を行った。The obtained ferromagnetic metal powder was subjected to ignition point measurement and heating stability test in the same manner as in Example 1.
強磁性金属粉末中のコバルト及びマグネシウムの含量
及び発火点測定の結果を表１に、加熱安定性試験の結果
を第１図に示す。Table 1 shows the results of measuring the contents of cobalt and magnesium in the ferromagnetic metal powder and the ignition point, and FIG. 1 shows the results of the heating stability test.
比較例２ 実施例３において硫酸マグネシウム７水塩の水溶液を
加えることなくリフラックスを12時間行ってコバルト含
有酸化鉄を得、実施例１と同様に還元を行ってコバルト
含有強磁性金属粉末を得た。Comparative Example 2 In Example 3, reflux was performed for 12 hours without adding an aqueous solution of magnesium sulfate heptahydrate to obtain cobalt-containing iron oxide, and reduction was performed in the same manner as in Example 1 to obtain cobalt-containing ferromagnetic metal powder. It was
得られた強磁性金属粉末について、実施例１と同様に
発火点測定および加熱安定性試験を行った。The obtained ferromagnetic metal powder was subjected to ignition point measurement and heating stability test in the same manner as in Example 1.
強磁性金属粉末中のコバルト及びマグネシウムの含量
及び発火点測定の結果を表１に、加熱安定性試験の結果
を第１図に示す。Table 1 shows the results of measuring the contents of cobalt and magnesium in the ferromagnetic metal powder and the ignition point, and FIG. 1 shows the results of the heating stability test.
比較例３ 実施例１と同じγ−Fe2O3を原料として用い、コバル
ト及びマグネシウムを含有させることなく実施例１と同
様に還元を行って強磁性金属粉末を得た。Comparative Example 3 The same γ-Fe 2 O 3 as in Example 1 was used as a raw material, and reduction was performed in the same manner as in Example 1 without containing cobalt and magnesium to obtain a ferromagnetic metal powder.
得られた強磁性金属粉末について、実施例１と同様に
発火点測定および加熱安定性試験を行った。The obtained ferromagnetic metal powder was subjected to ignition point measurement and heating stability test in the same manner as in Example 1.
強磁性金属粉末中のコバルト及びマグネシウムの含量
及び発火点測定の結果を表１に、加熱安定性試験の結果
を第１図に示す。Table 1 shows the results of measuring the contents of cobalt and magnesium in the ferromagnetic metal powder and the ignition point, and FIG. 1 shows the results of the heating stability test.
実施例５ ポリアクリル酸ナトリウム（MW約3000）1gを含む６％
苛性ソーダ水溶液700gに針状γ−Fe2O3を100g加えて得
たスラリーにチッ素ガスを吹き込みながら硝酸コバルト
６水塩35gを水160mlに溶解した溶液を加え、40℃で６時
間反応し、その後温度を上げリフラックスを６時間行っ
た。更に、このスラリーに硝酸カルシウム４水塩4.1gを
水80mlに溶解した溶液を加え、リフラックスを６時間行
いコバルト及びカルシウムを含む酸化鉄を得た。その
後、実施例１と同様に還元を行ってコバルト及びカルシ
ウムを含む強磁性金属粉末を得た。 Example 5 6% containing 1 g of sodium polyacrylate (MW about 3000)
A solution of 35 g of cobalt nitrate hexahydrate in 160 ml of water was added to the slurry obtained by adding 100 g of needle-shaped γ-Fe 2 O 3 to 700 g of a caustic soda aqueous solution, and the mixture was reacted at 40 ° C. for 6 hours. Then, the temperature was raised and reflux was performed for 6 hours. Further, a solution prepared by dissolving 4.1 g of calcium nitrate tetrahydrate in 80 ml of water was added to this slurry and refluxed for 6 hours to obtain iron oxide containing cobalt and calcium. Then, reduction was performed in the same manner as in Example 1 to obtain a ferromagnetic metal powder containing cobalt and calcium.
得られた強磁性金属粉末中のコバルト及びカルシウム
の含有量はそれぞれCo/Fe＝５重量％、Ca/Fe＝１重量％
であった。The contents of cobalt and calcium in the obtained ferromagnetic metal powder were Co / Fe = 5% by weight and Ca / Fe = 1% by weight, respectively.
Met.
得られた強磁性金属粉末について、実施例１と同様に
加熱安定性試験を行った。結果を第２図に示す。A heating stability test was performed on the obtained ferromagnetic metal powder in the same manner as in Example 1. Results are shown in FIG.
比較例４ 実施例５において硝酸カルシウム４水塩の水溶液を加
えることなく、リフラックスを12時間行ってコバルト含
有酸化鉄を得、実施例１と同様に還元を行ってコバルト
含有強磁性金属粉末を得た。Comparative Example 4 Without adding an aqueous solution of calcium nitrate tetrahydrate in Example 5, reflux was performed for 12 hours to obtain cobalt-containing iron oxide, and reduction was performed in the same manner as in Example 1 to obtain a cobalt-containing ferromagnetic metal powder. Obtained.
得られた強磁性金属粉末について、実施例１と同様に
加熱安定性試験を行った。結果を第２図に示す。A heating stability test was performed on the obtained ferromagnetic metal powder in the same manner as in Example 1. Results are shown in FIG.
第１図は実施例１〜４及び比較例１〜３の加熱安定性試
験結果を示すグラフ、第２図は実施例５及び比較例４の
加熱安定性試験結果を示すグラフである。FIG. 1 is a graph showing the heating stability test results of Examples 1 to 4 and Comparative Examples 1 to 3, and FIG. 2 is a graph showing the heating stability test results of Example 5 and Comparative Example 4.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭57−161006（ＪＰ，Ａ) ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-161006 (JP, A)
Claims (4)
に、コバルトの層を有し、その上にマグネシウム又はカ
ルシウムから選ばれるアルカリ土類金属元素の層を有す
ることを特徴とする磁気記録用強磁性金属粉末。1. A magnetic material having a layer of cobalt on the surface of a ferromagnetic metal powder consisting essentially of iron, and a layer of an alkaline earth metal element selected from magnesium or calcium thereon. Ferromagnetic metal powder for recording.
％、アルカリ土類金属元素の含有量が鉄に対して0.05〜
５重量％である特許請求の範囲第１項記載の強磁性金属
粉末。2. The content of cobalt is 2 to 15% by weight with respect to iron, and the content of alkaline earth metal element is 0.05 to with respect to iron.
The ferromagnetic metal powder according to claim 1, which is 5% by weight.
ａ）コバルトの塩、又は第一鉄塩及びコバルトの塩と、
ｂ）アルカリとを含む水溶液中で処理し、表面にコバル
ト化合物の層を形成せしめた後、ｃ）マグネシウム又は
カルシウムから選ばれるアルカリ土類金属元素の塩を含
む水溶液を加え、コバルト化合物の層の上にアルカリ土
類金属元素化合物の層を有する酸化物を得、これを還元
して、実質的に鉄からなる粒子表面にコバルトの層を形
成させ、更にその上にマグネシウム又はカルシウムから
選ばれるアルカリ土類金属元素の層を形成させることを
特徴とする磁気記録用強磁性金属粉末の製造方法。3. An oxide powder consisting essentially of iron oxide,
a) a salt of cobalt, or a ferrous salt and a salt of cobalt,
b) After treatment in an aqueous solution containing an alkali to form a layer of a cobalt compound on the surface, c) an aqueous solution containing a salt of an alkaline earth metal element selected from magnesium or calcium is added to form a layer of the cobalt compound. An oxide having a layer of an alkaline earth metal element compound thereon is obtained, which is reduced to form a layer of cobalt on the surface of particles substantially consisting of iron, and an alkali selected from magnesium or calcium is further formed thereon. A method for producing a ferromagnetic metal powder for magnetic recording, which comprises forming a layer of an earth metal element.
％、アルカリ土類金属元素の含有量が鉄に対して0.05〜
５重量％である特許請求の範囲第３項記載の強磁性金属
粉末の製造方法。4. The content of cobalt is 2 to 15% by weight with respect to iron, and the content of alkaline earth metal element is 0.05 to with respect to iron.
The method for producing a ferromagnetic metal powder according to claim 3, wherein the amount is 5% by weight.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62164277A JPH0831366B2 (en) | 1987-07-01 | 1987-07-01 | Ferromagnetic metal powder and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62164277A JPH0831366B2 (en) | 1987-07-01 | 1987-07-01 | Ferromagnetic metal powder and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS649603A JPS649603A (en) | 1989-01-12 |
| JPH0831366B2 true JPH0831366B2 (en) | 1996-03-27 |
Family
ID=15790031
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62164277A Expired - Lifetime JPH0831366B2 (en) | 1987-07-01 | 1987-07-01 | Ferromagnetic metal powder and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0831366B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07118704A (en) * | 1993-10-25 | 1995-05-09 | Matsushita Electric Ind Co Ltd | Hydrogen storage alloy powder, nickel hydrogen storage battery having the hydrogen storage alloy powder as a negative electrode active material, and method for producing hydrogen storage alloy powder |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5919964B2 (en) * | 1981-03-30 | 1984-05-10 | 大日本インキ化学工業株式会社 | Method for producing ferromagnetic metal powder |
-
1987
- 1987-07-01 JP JP62164277A patent/JPH0831366B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS649603A (en) | 1989-01-12 |
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