JPH05234734A - Method for stabilizing metal magnetic powder - Google Patents
Method for stabilizing metal magnetic powderInfo
- Publication number
- JPH05234734A JPH05234734A JP4031711A JP3171192A JPH05234734A JP H05234734 A JPH05234734 A JP H05234734A JP 4031711 A JP4031711 A JP 4031711A JP 3171192 A JP3171192 A JP 3171192A JP H05234734 A JPH05234734 A JP H05234734A
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- Japan
- Prior art keywords
- steam
- powder
- concentration
- carbon dioxide
- oxygen
- Prior art date
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は高密度磁気記録媒体用金
属磁性粉末に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic metal powder for high density magnetic recording media.
【０００２】[0002]
【従来の技術】鉄を主体とする磁気記録用金属磁性粉末
は、保磁力(Hc)、飽和磁化(σs)が大きく、高密度磁気
記録の中核材として、オーディオテープ、ビデオテー
プ、フロッピーディスク等に実用化されている。しかし
ながら、この金属磁性粉末は、酸化安定性に劣るという
最大の欠点を有する。すなわち、化学的に極めて活性で
あるため、酸素や水と反応し易く、空気中ではその磁気
特性が劣化してしまう。また、これらの欠点は高密度磁
気記録化の必須要件である微粒子化においては、さらに
顕著になる。BACKGROUND OF THE INVENTION Metal magnetic powder for magnetic recording, which is mainly composed of iron, has a large coercive force (Hc) and saturation magnetization (σs), and is a core material for high-density magnetic recording such as audio tape, video tape, and floppy disk. Has been put into practical use. However, this metal magnetic powder has the greatest drawback of being inferior in oxidative stability. That is, since it is extremely chemically active, it easily reacts with oxygen and water, and its magnetic properties deteriorate in the air. Further, these drawbacks become more remarkable in the case of fine particles, which is an essential requirement for high density magnetic recording.
【０００３】そこで、この問題を解決するために、金属
磁性粉末を液相中あるいは気相中において、粉末表面に
酸化被膜を形成する酸化処理、いわゆる徐酸化と称する
方法が提案されている。液相中での安定化方法として
は、特開昭52-85054号公報、特開昭55-164001 号公報、
特開昭59-16904号公報、特開昭60-128202 号公報等があ
る。この液相処理では、可燃物である溶剤と発火源であ
る金属磁性粉末の共存による取扱上の危険性の存在、さ
らには、金属磁性粉末の触媒効果により有機溶媒の一部
が酸化分解して各種の変質物を生成し、金属磁性粉末の
表面に付着して塗料調整時の分散性を悪化させ、最終的
に得られる塗膜表面性の悪化や角形比の低下を招くとい
う問題がある。Therefore, in order to solve this problem, there has been proposed a method called so-called gradual oxidation, which is an oxidation treatment for forming an oxide film on the surface of the magnetic powder in the liquid phase or in the vapor phase. As a stabilization method in a liquid phase, JP-A-52-85054, JP-A-55-164001,
There are JP-A-59-16904 and JP-A-60-128202. In this liquid phase treatment, there is a handling risk due to the coexistence of a solvent that is a combustible substance and a magnetic metal powder that is an ignition source.Furthermore, the catalytic effect of the metallic magnetic powder causes oxidative decomposition of a part of the organic solvent. There is a problem that various kinds of deteriorated substances are generated and adhere to the surface of the metal magnetic powder to deteriorate the dispersibility at the time of preparing the coating material, resulting in deterioration of surface property of the coating film finally obtained and reduction of squareness ratio.
【０００４】また気相中の安定化方法としては、特開昭
56-51502号公報、特開昭56-55503号公報、特開昭56-693
01号公報、特開昭57-89401号公報、特開昭57-181301 号
公報、特開平1-21002 号公報等がある。これらは、酸素
を不活性ガスで希釈して、ガス中の酸素濃度と反応温度
を適度にコントロールして、酸化被膜を形成せしめる方
法である。この方法では、液相処理における種々の問題
は解決されたが、金属と酸素の反応は激しい酸化反応で
あるため、局部的な酸化反応の進み過ぎが生じ易く、焼
結や融着が生じ易い。このため、磁気特性の低下や塗料
調整時の分散性の悪化を招き易い。Further, as a stabilizing method in the gas phase, Japanese Patent Laid-Open No.
56-51502, JP-A-56-55503, JP-A-56-693
No. 01, JP-A-57-89401, JP-A-57-181301, JP-A 1-21002 and the like. In these methods, oxygen is diluted with an inert gas, and the oxygen concentration in the gas and the reaction temperature are appropriately controlled to form an oxide film. With this method, various problems in the liquid phase treatment have been solved, but since the reaction between metal and oxygen is a vigorous oxidation reaction, the local oxidation reaction is likely to proceed excessively, and sintering or fusion is likely to occur. .. For this reason, the magnetic properties are likely to deteriorate and the dispersibility at the time of preparing the coating material is likely to deteriorate.
【０００５】これらの気相処理の諸問題を解決するため
に、特開平1-241801号公報では、予め、水蒸気を含む不
活性ガスで前処理して、その後、酸化性ガスを通気する
方法が、また特開平2-303006号公報では、予め炭酸ガス
で前処理したのち、酸化性ガスを通気する方法が提案さ
れている。これらはいずれも酸素より酸化力が小さく、
また酸化反応熱が酸素よりはるかに低いか又は吸熱反応
である酸化性ガスにより初期の表面処理を行うことによ
り、その後の酸化力が強く反応熱が高い酸素による酸化
の弊害を解決しようとしている。しかし、いずれも磁気
特性の向上には効果がみられるが酸化安定性とくに耐蝕
性の向上にはまだ不十分である。In order to solve these problems of vapor phase treatment, Japanese Patent Laid-Open No. 1-241801 discloses a method of pretreating with an inert gas containing water vapor and then aerating an oxidizing gas. Further, JP-A-2-303006 proposes a method of pre-treating with carbon dioxide gas and then ventilating an oxidizing gas. Each of these has less oxidizing power than oxygen,
Further, by performing the initial surface treatment with an oxidizing gas having a heat of oxidation reaction much lower than that of oxygen or an endothermic reaction, it is attempted to solve the adverse effect of oxidation by oxygen having a strong oxidizing power and a high reaction heat thereafter. However, although they are effective in improving the magnetic properties, they are still insufficient in improving the oxidation stability, particularly the corrosion resistance.
【０００６】[0006]
【発明が解決しようとする課題】このように、気相法安
定化方法では、酸素の酸化力が強いためと、また金属磁
性粉末表面には酸化され易い部分と、酸化され難い部分
があるため、局部的な酸化ムラが生じ易い。これらを改
良して均一な酸化被膜を得るには、酸化被膜を厚くせざ
るを得ず、結果として飽和磁化が低下する。さらに高密
度磁気記録においては、より微細な粒子で高い飽和磁化
をもち、且つ、高い耐蝕性が要求される。さらには、保
磁力の分布が小さいことも重要である。そのためには薄
いが緻密で、且つ均一な酸化被膜が要求される。As described above, in the gas phase method stabilization method, the oxidizing power of oxygen is strong, and the surface of the metal magnetic powder has a portion that is easily oxidized and a portion that is difficult to be oxidized. Local oxidation unevenness is likely to occur. In order to improve these and obtain a uniform oxide film, the oxide film must be thickened, resulting in a decrease in saturation magnetization. Further, in high density magnetic recording, finer particles have higher saturation magnetization and higher corrosion resistance is required. Further, it is important that the distribution of coercive force is small. For that purpose, a thin but dense and uniform oxide film is required.
【０００７】[0007]
【課題を解決するための手段】本発明者等は上記の問題
を解決するために、鋭意金属磁性粉末表面の酸化過程の
研究を行った結果、特定の温度条件下で還元鉄粉に水蒸
気と炭酸ガスを同時に接触させることにより、均一で緻
密な酸化被膜が形成されることを見出し、さらにこのあ
と、酸化力の強い酸素を含んだ不活性ガスで酸化させて
も、均一緻密な初期酸化被膜が存在するため局部的な酸
化反応の進み過ぎが生じ難く、最終的に得られる酸化被
膜は、薄いが緻密で均一なものであることを見出し本発
明を完成した。In order to solve the above problems, the inventors of the present invention have studied the oxidation process of the surface of the magnetic metal powder, and as a result, have found that the reduced iron powder contains water vapor under certain temperature conditions. It was found that a uniform and dense oxide film is formed by simultaneously contacting carbon dioxide gas, and even after that, even if it is oxidized with an inert gas containing oxygen, which has a strong oxidizing power, a uniform dense initial oxide film is formed. Therefore, the present invention has been completed by finding that the local oxidation reaction does not easily proceed excessively locally, and the oxide film finally obtained is thin but dense and uniform.
【０００８】すなわち、本発明は鉄を主体とした針状オ
キシ水酸化鉄あるいは酸化鉄を還元し、金属合金粉末と
した後、200 〜250 ℃の反応温度で、先ず水蒸気濃度が
0.1〜10容量％である水蒸気含有炭酸ガス雰囲気で予備
的な前段酸化処理をすることにより、均一緻密な初期酸
化被膜を形成させ、その後、酸素濃度が0.02〜10容量
％、水蒸気濃度が0.1 〜10容量％である酸素及び水蒸気
含有不活性ガス雰囲気で後段酸化処理することにより、
薄いが緻密かつ均一な酸化被膜を形成させることを特徴
とする金属磁性粉末の安定化方法である。That is, according to the present invention, after acicular iron oxyhydroxide or iron oxide mainly composed of iron is reduced to form a metal alloy powder, the water vapor concentration is first changed at a reaction temperature of 200 to 250 ° C.
A preliminary dense pre-oxidation treatment is performed in a steam-containing carbon dioxide gas atmosphere of 0.1 to 10% by volume to form a uniform and dense initial oxide film, and then the oxygen concentration is 0.02 to 10% by volume and the steam concentration is 0.1 to 10% by volume. By post-stage oxidation treatment in an inert gas atmosphere containing oxygen and water vapor of 10% by volume,
It is a method for stabilizing a metal magnetic powder, which is characterized by forming a thin but dense and uniform oxide film.
【０００９】本発明に用いる鉄を主体とした針状オキシ
水酸化鉄あるいは酸化鉄とは、常法によって得られる針
状のα-FeOOH、γ-FeOOH、β-FeOOH、あるいはα-Fe
2O3、γ-Fe2O3、β-Fe2O3、Fe3O4 等でこれらにNi、C
o、Zn、Mn、Cr、Ca、Mg、Ba、P 、Si、Al、B 、Zr等の
金属から選ばれる１種ないしし２種以上の金属化合物が
ドープ及び／又は被着されたものが使用される。前記、
水酸化鉄ないしは酸化鉄を主体とする粉末の還元は、常
法で還元性雰囲気に保ちながら加熱することによって行
い、金属合金粉末を得る。The needle-like iron oxyhydroxide or iron oxide mainly composed of iron used in the present invention means needle-like α-FeOOH, γ-FeOOH, β-FeOOH, or α-Fe obtained by a conventional method.
2 O 3 , γ-Fe 2 O 3 , β-Fe 2 O 3 , Fe 3 O 4 etc.
One doped with and / or coated with one or more metal compounds selected from metals such as o, Zn, Mn, Cr, Ca, Mg, Ba, P, Si, Al, B, and Zr. used. The
The reduction of the powder mainly composed of iron hydroxide or iron oxide is carried out by heating in a conventional method while maintaining a reducing atmosphere to obtain a metal alloy powder.
【００１０】次いで、得られた金属合金粉末を、水蒸気
を含んだ炭酸ガスと接触させることにより、初期酸化被
膜の形成を行う。水蒸気含有炭酸ガスには、窒素、アル
ゴン、ヘリウム等の不活性ガスが同伴されてもよいが、
炭酸ガス濃度が低すぎると、均一緻密な初期酸化被膜が
得られ難く、また酸化も遅くなるので、炭酸ガス濃度と
しては20容量％以上が好ましい。炭酸ガスだけの場合、
250 ℃以上において酸化被膜の形成が見られるが、炭酸
ガスは活性が低いため250 〜400 ℃では、気相法徐酸化
処理の常法と同様、均一緻密な酸化被膜は得られず、局
部的に酸化ムラが生じ易い。また炭酸ガスだけで400 ℃
以上の処理では、焼結、融着を起こして磁気特性が低下
する。炭酸ガスは含まず、水蒸気を含む不活性ガスだけ
で処理する場合、50〜150 ℃では、気相法徐酸化処理の
常法と同様、均一緻密な酸化被膜は得られず、局部的な
酸化ムラによる耐蝕性の低下や保磁力分布の悪化が見ら
れる。また炭酸ガスは含まず水蒸気を含んだ不活性ガス
だけで、150 ℃以上で処理する場合はα-Fe2O3の生成や
焼結、融着が生じ、磁気特性が低下する。水蒸気含有炭
酸ガスによる予備的な前段酸化処理の時間は、水蒸気濃
度、炭酸ガス濃度にもよるが、実用上１時間ないし３時
間が好ましい。Next, the obtained metal alloy powder is brought into contact with carbon dioxide gas containing water vapor to form an initial oxide film. The steam-containing carbon dioxide gas may be accompanied by an inert gas such as nitrogen, argon or helium,
If the carbon dioxide concentration is too low, it is difficult to obtain a uniform and dense initial oxide film, and the oxidation is slowed. Therefore, the carbon dioxide concentration is preferably 20% by volume or more. If only carbon dioxide,
Formation of an oxide film is observed at temperatures above 250 ° C, but since carbon dioxide gas is low in activity, a uniform and dense oxide film cannot be obtained at 250 to 400 ° C, similar to the usual method of vapor-phase slow oxidation treatment, and it is localized. Uneven oxidation is likely to occur. Also, carbon dioxide only 400 ℃
In the above process, sintering and fusion occur and the magnetic properties are deteriorated. When treating only with an inert gas containing water vapor without containing carbon dioxide, a uniform and dense oxide film cannot be obtained at 50 to 150 ° C as in the usual method of vapor phase slow oxidation treatment, and local oxidation is not performed. Deterioration of corrosion resistance and deterioration of coercive force distribution due to unevenness are observed. Further, when the treatment is carried out at 150 ° C. or higher with only an inert gas containing water vapor without containing carbon dioxide, α-Fe 2 O 3 is produced, sintered, and fused to deteriorate the magnetic properties. The time for the preliminary pre-stage oxidation treatment with the carbon dioxide gas containing water vapor is preferably 1 hour to 3 hours in practice, though it depends on the water vapor concentration and the carbon dioxide concentration.
【００１１】水蒸気含有炭酸ガスによる予備的な前段酸
化処理の後、水蒸気と酸素を含んだ不活性ガス雰囲気
下、後段酸化処理による酸化被膜の形成、安定化をはか
る。水蒸気濃度は、0.1 〜10容量％が良い。水蒸気濃度
が0.1容量％未満の場合、水蒸気による酸素の酸化抑制
効果が低下して、磁気特性の低下を招く。また水蒸気濃
度が10容量％を越えると粒子表面に過剰に水分が吸着
し、塗料調整時の分散性を悪化させ好ましくない。処理
温度は30〜90℃が良い。処理温度が30℃未満の場合、充
分な酸化被膜が得られず、安定性の低下を招く。また処
理温度が90℃を越えると酸化の進み過ぎ、局部的な酸化
ムラ等が生じ易くなり好ましくない。酸素濃度は0.02容
量％から徐々に上げて最終的には10容量％にするのが安
定性を得る上でこのましい。これらの関係を図１から図
７に示す。After the preliminary pre-stage oxidation treatment with the steam-containing carbon dioxide, an oxide film is formed and stabilized by the post-stage oxidation treatment in an inert gas atmosphere containing steam and oxygen. The water vapor concentration is preferably 0.1-10% by volume. If the water vapor concentration is less than 0.1% by volume, the effect of water vapor to suppress the oxidation of oxygen is reduced, and the magnetic properties are deteriorated. On the other hand, if the water vapor concentration exceeds 10% by volume, excessive moisture will be adsorbed on the surface of the particles, which will deteriorate the dispersibility during preparation of the paint, which is not preferable. The treatment temperature is preferably 30-90 ℃. If the treatment temperature is lower than 30 ° C., a sufficient oxide film cannot be obtained, leading to deterioration in stability. On the other hand, if the treatment temperature exceeds 90 ° C., the oxidation proceeds excessively and local unevenness of oxidation is likely to occur, which is not preferable. The oxygen concentration is gradually increased from 0.02% by volume to finally 10% by volume for stability. These relationships are shown in FIGS.
【００１２】本発明に用いる装置としては、固定床方
式、流動床方式、回転円筒方式等、種々のものが採用で
きる。As the apparatus used in the present invention, various apparatuses such as a fixed bed system, a fluidized bed system and a rotating cylinder system can be adopted.
【００１３】[0013]
【実施例】以下、本発明を実施例により更に具体的に説
明する。しかし、本発明はこれらに限定されるものでは
ない。EXAMPLES The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these.
【００１４】実施例１ 平均長軸長0.14μm 、平均軸比10、含有金属がCo＝15.0
重量％、Ni＝1.0 重量％、Al＝4.0 重量％（何れも対F
e）であるα−FeOOH を400 ℃で２時間仮焼を行い、次
いで水素気流中400 ℃で３時間還元して金属磁性粉末を
得た。このものを原料Ａとする。Example 1 Average major axis length 0.14 μm, average axial ratio 10, content metal Co = 15.0
% By weight, Ni = 1.0% by weight, Al = 4.0% by weight
The e-FeOOH of e) was calcined at 400 ° C. for 2 hours and then reduced in a hydrogen stream at 400 ° C. for 3 hours to obtain a metal magnetic powder. This is referred to as raw material A.
【００１５】原料Ａを窒素充填の中間容器に窒素雰囲気
下で移して保管し、酸化安定化処理装置に窒素雰囲気下
で移して酸化安定化処理を行う。以後の実施例、比較例
ともこの原料Ａを使用した。The raw material A is transferred and stored in a nitrogen-filled intermediate container under a nitrogen atmosphere, and then transferred to an oxidation stabilization treatment apparatus under a nitrogen atmosphere for oxidation stabilization treatment. This raw material A was used in the following examples and comparative examples.
【００１６】前段の反応は炭酸ガス濃度30容量％、水蒸
気濃度0.5 容量％、窒素ガス濃度69.5容量％の混合ガス
を金属磁性粉末１Kg当たり10 Nm3／時の流量で２時間供
給し行う、温度は金属磁性粉末層の温度が200 ℃に保た
れるようにする。The reaction in the first stage is carried out by supplying a mixed gas having a carbon dioxide gas concentration of 30% by volume, a water vapor concentration of 0.5% by volume, and a nitrogen gas concentration of 69.5% by volume for 2 hours at a flow rate of 10 Nm 3 / hour per 1 Kg of the magnetic metal powder, and the temperature. Keeps the temperature of the metallic magnetic powder layer at 200 ° C.
【００１７】後段の反応は先ず酸素濃度0.02容量％、水
蒸気濃度0.5 容量％含有の窒素ガスを前段と同等の流量
で金属磁性粉末１Kg当たり酸素量0.08 Nm3供給し温度は
金属磁性粉末層の温度が60℃に保たれるようにする。次
いで酸素濃度の0.1 容量％、水蒸気濃度0.5 容量％含有
の窒素ガスを同等の流量で供給し、次第に酸素濃度を上
げ、２時間後に10容量％として反応を終了する。温度は
金属磁性粉末層の温度が30℃に保たれるようにする。In the reaction in the latter stage, first, nitrogen gas containing 0.02% by volume of oxygen and 0.5% by volume of water vapor is supplied at a flow rate equivalent to that in the former stage, the amount of oxygen is 0.08 Nm 3 per 1 kg of the metallic magnetic powder, and the temperature is the temperature of the metallic magnetic powder layer. Is maintained at 60 ° C. Then, nitrogen gas containing 0.1% by volume of oxygen concentration and 0.5% by volume of water vapor is supplied at the same flow rate to gradually increase the oxygen concentration, and after 2 hours, the reaction is terminated at 10% by volume. The temperature is such that the temperature of the metal magnetic powder layer is maintained at 30 ° C.
【００１８】反応終了後、金属磁性粉末を大気中に取り
出したが、発熱現象は観察されなかった。この金属磁性
粉末の磁気特性（東英工業製VSM を使用し、測定磁場10
KGで測定）はHc＝1667 Oe 、σs ＝150 emu/g 、σr/σ
s ＝0.515 であった。このものの60℃、RH＝90％の雰囲
気で１週間曝露した後のσs は140 emu/g であった。従
って劣化率は6.7 ％である。また、異方性磁界分布は角
度変移法（東英工業製VSM を使用し、10 kOeで配向させ
た後、初期配向方向の10°方向で印加磁場を250 Oeずつ
増加、90°方向で各々σr を求め、このσr の変化量の
総和に対する各々の変化量Δσr の割合をもつて保磁力
分布とする。測定磁場は10 KG ）により測定した。得ら
れた保磁力分布の変動率は34.5％であった。これを図７
に示す。After completion of the reaction, the metallic magnetic powder was taken out into the atmosphere, but no exothermic phenomenon was observed. Magnetic properties of this metallic magnetic powder (measured magnetic field 10
(Measured in KG) is Hc = 1667 Oe, σs = 150 emu / g, σr / σ
It was s = 0.515. Σs of this product was 140 emu / g after exposure for 1 week in an atmosphere of 60 ° C. and RH = 90%. Therefore, the deterioration rate is 6.7%. The anisotropic magnetic field distribution was measured by the angle displacement method (VSM manufactured by Toei Kogyo Co., Ltd. was used, and after orienting at 10 kOe, the applied magnetic field was increased by 250 Oe by 10 ° in the initial orientation direction and by 90 ° respectively. [sigma] r is obtained, and the coercive force distribution is defined by the ratio of each variation [Delta] [sigma] r to the total sum of variations of [sigma] r. The variation rate of the obtained coercive force distribution was 34.5%. Figure 7
Shown in.
【００１９】実施例２ 原料Ａを使用し、前段の反応は反応温度を250 ℃とし、
温度以外は実施例１と同様に行う。後段以降の反応も実
施例１と同様に行う。反応終了後、金属磁性粉末を大気
中に取り出したが、発熱現象は観察されなかった。この
金属磁性粉末の磁気特性はHc＝1655 Oe 、σs ＝147 em
u/g 、σr/σs ＝0.514 であり、60℃、RH＝90％の雰囲
気で１週間曝露した後のσs は136 emu/g であった。従
って劣化率は7.5 ％である。また保磁力分布の変動率は
34％であった。Example 2 Using the raw material A, the reaction in the first stage was carried out at a reaction temperature of 250 ° C.
The procedure is the same as in Example 1 except for the temperature. The subsequent reactions are also performed in the same manner as in Example 1. After completion of the reaction, the magnetic metal powder was taken out into the atmosphere, but no exothermic phenomenon was observed. The magnetic properties of this metallic magnetic powder are Hc = 1655 Oe, σs = 147 em
u / g and σr / σs = 0.514, and σs after exposure for 1 week in an atmosphere of 60 ° C and RH = 90% was 136 emu / g. Therefore, the deterioration rate is 7.5%. The fluctuation rate of the coercive force distribution is
It was 34%.
【００２０】実施例３ 原料Ａ使用し、前段の反応は水蒸気濃度0.5 容量％含有
の炭酸ガスで温度は250 ℃で行い、他の条件は実施例１
と同様に行う。後段以降の反応も実施例１と同様に行
う。反応終了後金属磁性粉末を大気中に取り出したが、
発熱現象は観察されなかった。この金属磁性粉末の磁気
特性はHc＝1652 Oe 、σs ＝146 emu/g 、σr/σs ＝0.
512 であり、60℃、RH＝90％の雰囲気で１週間曝露した
後のσs は134 emu/g であった。従って劣化率は8.2 ％
である。また保磁力分布の変動率は34.2％であった。Example 3 Using raw material A, the reaction in the first stage was carried out at a temperature of 250 ° C. with carbon dioxide containing 0.5% by volume of steam, and the other conditions were the same as in Example 1.
Do the same as. The subsequent reactions are also performed in the same manner as in Example 1. After completion of the reaction, the magnetic metal powder was taken out into the atmosphere,
No exothermic phenomenon was observed. The magnetic properties of this metallic magnetic powder are Hc = 1652 Oe, σs = 146 emu / g, σr / σs = 0.
The value of 512 was σs of 134 emu / g after exposure for 1 week in an atmosphere of 60 ° C. and RH = 90%. Therefore, the deterioration rate is 8.2%
Is. The variation rate of the coercive force distribution was 34.2%.
【００２１】比較例１ 原料は実施例１と同じである。反応は水蒸気含有炭酸ガ
スによる前段酸化を行わずに水蒸気含有酸化性ガスによ
る酸化だけを行う。Comparative Example 1 Raw materials are the same as in Example 1. The reaction is performed only by the steam-containing oxidizing gas without performing the first-stage oxidation by the steam-containing carbon dioxide gas.
【００２２】先ず酸素濃度0.05容量％、水蒸気濃度0.5
容量％含有の窒素ガスを金属磁性粉末１Kg当たり10 Nm3
/ 時の流量で金属磁性粉末１Kg当たり酸素量0.1 Nm3 供
給し行う。温度は金属磁性粉末層の温度が60℃に保たれ
るようにする。次いで酸素濃度0.1 容量％、水蒸気濃度
0.5 容量％含有の窒素ガスを同等の流量で供給し、次第
に酸素濃度を上げ、２時間後に10容量％として反応を終
了する。温度は金属磁性粉末層の温度が30℃に保たれる
様にする。反応終了後、金属磁性粉末を大気中に取り出
したが、発熱現象は観察されなかった。この金属磁性粉
末の磁気特性はHc＝1645 Oe 、σs ＝140 emu/g 、σr/
σs ＝0.513 であり、60℃、RH＝90％の雰囲気で１週間
曝露した後のσs は121 emu/g であった。従って劣化率
は13.6％である。また保磁力分布の変動率は38.7％であ
った。First, the oxygen concentration is 0.05% by volume and the water vapor concentration is 0.5.
Nitrogen gas containing 10% by volume of 10 Nm 3 per 1 kg of magnetic metal powder
Oxygen amount of 0.1 Nm 3 is supplied per 1 kg of magnetic metal powder at a flow rate of / hour. The temperature is such that the temperature of the metal magnetic powder layer is maintained at 60 ° C. Oxygen concentration 0.1% by volume, water vapor concentration
Nitrogen gas containing 0.5% by volume is supplied at an equivalent flow rate, the oxygen concentration is gradually increased, and after 2 hours, the reaction is terminated with 10% by volume. The temperature is such that the temperature of the metal magnetic powder layer is maintained at 30 ° C. After completion of the reaction, the magnetic metal powder was taken out into the atmosphere, but no exothermic phenomenon was observed. The magnetic properties of this metallic magnetic powder are Hc = 1645 Oe, σs = 140 emu / g, σr /
σ s = 0.513, and σ s was 121 emu / g after exposure for 1 week in an atmosphere of 60 ° C. and RH = 90%. Therefore, the deterioration rate is 13.6%. The variation rate of the coercive force distribution was 38.7%.
【００２３】比較例２ 原料は実施例１と同様である。反応は炭酸ガスにより温
度300 ℃で前段酸化を行い、他の条件は実施例１と同様
に行う。後段以降の反応も実施例１と同様に行う。反応
終了後、金属磁性粉末を大気中に取り出したが発熱現象
は観察されなかった。この金属磁性粉末の磁気特性はHc
＝1650 Oe 、σs ＝139 emu/g 、σr/σs ＝0.517 であ
り、60℃、RH＝90％の雰囲気で１週間曝露した後のσs
は121 emu/g であった。従って劣化率は12.9％である。
また保磁力分布の変動率は37.9％であった。Comparative Example 2 The raw materials are the same as in Example 1. The reaction is carried out by carbon dioxide gas at a temperature of 300 ° C. in the first stage oxidation, and the other conditions are the same as in Example 1. The subsequent reactions are also performed in the same manner as in Example 1. After completion of the reaction, the metallic magnetic powder was taken out into the atmosphere, but no exothermic phenomenon was observed. The magnetic properties of this metallic magnetic powder are Hc
= 1650 Oe, σs = 139 emu / g, σr / σs = 0.517, and σs after 1 week exposure at 60 ° C, RH = 90%
Was 121 emu / g. Therefore, the deterioration rate is 12.9%.
The variation rate of the coercive force distribution was 37.9%.
【００２４】比較例３ 原料は実施例１と同様である。反応は水蒸気による前段
酸化を行うものであり、水蒸気濃度1.0 容量％の窒素ガ
スで温度は50℃で行う。他の条件は実施例１と同様に行
う。後段以降の反応も実施例１と同様に行う。反応終了
後、金属磁性粉末を大気中に取り出したが、発熱現象は
観察されなかった。この金属磁性粉末の磁気特性はHc＝
1651 Oe 、σs ＝141 emu/g 、σr/σs ＝0.514 であ
り、60℃、RH＝90％の雰囲気で１週間曝露した後のσs
は121 emu/g であった。従って劣化率は14.2％である。
また保磁力分布の変動率は38.1％であった。Comparative Example 3 The raw materials are the same as in Example 1. The reaction involves pre-stage oxidation with steam, and is carried out at a temperature of 50 ° C. with nitrogen gas having a steam concentration of 1.0% by volume. Other conditions are the same as in the first embodiment. The subsequent reactions are also performed in the same manner as in Example 1. After completion of the reaction, the metallic magnetic powder was taken out into the atmosphere, but no exothermic phenomenon was observed. The magnetic characteristics of this metallic magnetic powder are Hc =
1651 Oe, σs = 141 emu / g, σr / σs = 0.514, and σs after exposure for 1 week in an atmosphere of 60 ° C and RH = 90%.
Was 121 emu / g. Therefore, the deterioration rate is 14.2%.
The variation rate of the coercive force distribution was 38.1%.
【００２５】以上実施例、比較例における磁気特性、劣
化率、保磁力分布変動率の数値を表１に示す。Table 1 shows the numerical values of the magnetic characteristics, deterioration rate, and coercive force distribution variation rate in the above Examples and Comparative Examples.
【００２６】[0026]
【表１】 [Table 1]
【００２７】[0027]
【発明の効果】鉄を主体とする金属磁性粉末を水蒸気含
有炭酸ガスで、先ず前段酸化処理をした後、水蒸気およ
び酸素含有不活性ガスで酸化処理して、安定化させるこ
とにより、高い飽和磁化で、高い耐蝕性を持ち、且つ、
保磁力分布の小さい金属磁性粉末を得ることが出来る。
そして、このような処理を施すことにより、より安定性
の優れた高密度磁気記録に適した金属磁性粉末を提供す
ることが可能となる。EFFECT OF THE INVENTION A metallic magnetic powder mainly composed of iron is subjected to a first-stage oxidation treatment with water vapor-containing carbon dioxide gas, and then is subjected to an oxidation treatment with water vapor and an oxygen-containing inert gas to be stabilized to obtain a high saturation magnetization. Has high corrosion resistance, and
A magnetic metal powder having a small coercive force distribution can be obtained.
Then, by performing such a treatment, it becomes possible to provide a metal magnetic powder which is more stable and suitable for high density magnetic recording.
【図１】前段酸化処理である水蒸気含有炭酸ガス処理に
おいて、処理時間を一定にし、炭酸ガス濃度を30容量％
として水蒸気濃度及び処理温度を種々変化させ、各々に
ついて、水蒸気含有炭酸ガス処理後の水蒸気及び酸素を
含んだ不活性ガスによる後段酸化処理条件は一定にして
種々得られたものの、飽和磁化の値を等値線図で示した
ものである。横軸に処理温度、縦軸に水蒸気濃度をと
り、図中の数値は飽和磁化σs(emu/g)を表す。FIG. 1 In the steam-containing carbon dioxide gas treatment, which is the first-stage oxidation treatment, the treatment time was kept constant and the carbon dioxide concentration was 30% by volume.
As a result, various values of the saturation magnetization can be obtained by varying the water vapor concentration and the treatment temperature, and for each of them, various post-oxidation treatment conditions using the inert gas containing water vapor and oxygen after the treatment of the carbon dioxide gas containing water vapor were made constant. It is shown in the contour map. The processing temperature is plotted on the horizontal axis and the water vapor concentration is plotted on the vertical axis, and the numerical values in the figure represent the saturation magnetization s (emu / g).
【図２】前段酸化処理である水蒸気含有炭酸ガス処理に
おいて、処理時間を一定にし、水蒸気濃度を0.5 容量％
として、炭酸ガス濃度及び処理温度を種々変化させ、各
々について、水蒸気含有炭酸ガス処理後の水蒸気及び酸
素を含んだ不活性ガスによる後段酸化処理条件は一定に
して種々得られたものの、飽和磁化の値を等値線図で示
したものである。横軸に処理温度、縦軸に炭酸ガス濃度
をとり、図中の数値は飽和磁化σs(emu/g)を表す。[Fig. 2] In the carbon dioxide gas containing water vapor as the first-stage oxidation treatment, the treatment time was kept constant and the water vapor concentration was 0.5% by volume.
As the carbon dioxide concentration and the treatment temperature were variously changed, the saturation magnetization of the saturated magnetization was variously obtained although the post-stage oxidation treatment condition by the inert gas containing the water vapor and oxygen after the steam-containing carbon dioxide treatment was kept constant. The values are shown in contour plots. The processing temperature is plotted on the horizontal axis and the carbon dioxide concentration is plotted on the vertical axis, and the numerical values in the figure represent the saturation magnetization s (emu / g).
【図３】図１に示した金属磁性粉末について、温度60
℃、ＲＨ＝90％の雰囲気で１週間曝露した時の飽和磁化
の劣化率を等値線図で示したものである。図中の数値は
劣化率（％）を示す。FIG. 3 shows the temperature of the magnetic metal powder shown in FIG.
FIG. 3 is a contour plot showing the deterioration rate of saturation magnetization when exposed for 1 week in an atmosphere of 90 ° C. and RH = 90%. The numerical value in the figure shows the deterioration rate (%).
【図４】図２に示した金属磁性粉末について、温度60
℃、ＲＨ＝90％の雰囲気で１週間曝露した時の飽和磁化
の劣化率を等値線図で示したものである。図中の数値は
劣化率（％）を示す。FIG. 4 shows the temperature of the magnetic metal powder shown in FIG.
FIG. 3 is a contour plot showing the deterioration rate of saturation magnetization when exposed for 1 week in an atmosphere of 90 ° C. and RH = 90%. The numerical value in the figure shows the deterioration rate (%).
【図５】図１に示した金属磁性粉末の保磁力分布を等値
線図で示したものである。図中の数値は保磁力分布にお
ける変動率（％）を示している。FIG. 5 is a contour diagram showing the coercive force distribution of the metal magnetic powder shown in FIG. The numerical values in the figure show the fluctuation rate (%) in the coercive force distribution.
【図６】図２に示した金属磁性粉末の保磁力分布を等値
線図で示したものである。図中の数値は保磁力分布にお
ける変動率（％）を示している。FIG. 6 is a contour diagram showing the coercive force distribution of the metal magnetic powder shown in FIG. The numerical values in the figure show the fluctuation rate (%) in the coercive force distribution.
【図７】実施例１で得られた金属磁性粉末の異方性磁界
分布の測定結果を示す。7 shows measurement results of anisotropic magnetic field distribution of the metal magnetic powder obtained in Example 1. FIG.
フロントページの続き (72)発明者 桜井 康晴 大阪府高石市高砂１丁目６番地三井東圧化 学株式会社内Front page continued (72) Inventor Yasuharu Sakurai 1-6 Takasago, Takaishi-shi, Osaka Mitsui Toatsu Kagaku Co., Ltd.
Claims (1)
蒸気濃度が0.1 〜10容量％である水蒸気含有炭酸ガス雰
囲気中で200 〜250 ℃の反応温度で酸化処理をし、さら
に酸素濃度が0.02〜10容量％、水蒸気濃度が0.1 〜10容
量％である酸素及び水蒸気含有不活性ガス雰囲気中で30
〜90℃の反応温度において酸化処理をして、安定化させ
ることを特徴する金属磁性粉末の安定化方法。1. An iron-based metallic magnetic powder is first subjected to an oxidation treatment at a reaction temperature of 200 to 250 ° C. in a water vapor-containing carbon dioxide gas atmosphere having a water vapor concentration of 0.1 to 10% by volume. 30% in an inert gas atmosphere containing oxygen and water vapor with a concentration of 0.02 to 10% by volume and a water vapor concentration of 0.1 to 10% by volume.
A method for stabilizing a metal magnetic powder, which is characterized by carrying out an oxidation treatment at a reaction temperature of up to 90 ° C for stabilization.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4031711A JPH05234734A (en) | 1992-02-19 | 1992-02-19 | Method for stabilizing metal magnetic powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4031711A JPH05234734A (en) | 1992-02-19 | 1992-02-19 | Method for stabilizing metal magnetic powder |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05234734A true JPH05234734A (en) | 1993-09-10 |
Family
ID=12338661
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4031711A Pending JPH05234734A (en) | 1992-02-19 | 1992-02-19 | Method for stabilizing metal magnetic powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05234734A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5735969A (en) * | 1996-03-07 | 1998-04-07 | Imation Corp. | Method of producing acicular magnetic alloy particles |
-
1992
- 1992-02-19 JP JP4031711A patent/JPH05234734A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5735969A (en) * | 1996-03-07 | 1998-04-07 | Imation Corp. | Method of producing acicular magnetic alloy particles |
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