JPH0470363B2 - - Google Patents
Info
- Publication number
- JPH0470363B2 JPH0470363B2 JP57041986A JP4198682A JPH0470363B2 JP H0470363 B2 JPH0470363 B2 JP H0470363B2 JP 57041986 A JP57041986 A JP 57041986A JP 4198682 A JP4198682 A JP 4198682A JP H0470363 B2 JPH0470363 B2 JP H0470363B2
- Authority
- JP
- Japan
- Prior art keywords
- powder
- metal powder
- pellet
- iron
- oxide film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000000843 powder Substances 0.000 claims description 35
- 229910052751 metal Inorganic materials 0.000 claims description 21
- 239000002184 metal Substances 0.000 claims description 21
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 12
- 239000008188 pellet Substances 0.000 claims description 11
- 239000007789 gas Substances 0.000 claims description 9
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 8
- 239000002245 particle Substances 0.000 claims description 8
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 7
- 229910001882 dioxygen Inorganic materials 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 5
- CUPCBVUMRUSXIU-UHFFFAOYSA-N [Fe].OOO Chemical compound [Fe].OOO CUPCBVUMRUSXIU-UHFFFAOYSA-N 0.000 claims description 4
- 229910021519 iron(III) oxide-hydroxide Inorganic materials 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 2
- 238000010298 pulverizing process Methods 0.000 claims description 2
- 238000007254 oxidation reaction Methods 0.000 description 13
- 230000003647 oxidation Effects 0.000 description 12
- 238000000034 method Methods 0.000 description 5
- 230000001590 oxidative effect Effects 0.000 description 5
- 238000005453 pelletization Methods 0.000 description 5
- 239000012071 phase Substances 0.000 description 5
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 239000006247 magnetic powder Substances 0.000 description 2
- 230000005415 magnetization Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 208000005156 Dehydration Diseases 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- -1 aluminum compound Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 1
- 229910052794 bromium Inorganic materials 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 150000003377 silicon compounds Chemical class 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- POWFTOSLLWLEBN-UHFFFAOYSA-N tetrasodium;silicate Chemical compound [Na+].[Na+].[Na+].[Na+].[O-][Si]([O-])([O-])[O-] POWFTOSLLWLEBN-UHFFFAOYSA-N 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 229910006540 α-FeOOH Inorganic materials 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
Landscapes
- Powder Metallurgy (AREA)
- Hard Magnetic Materials (AREA)
- Soft Magnetic Materials (AREA)
- Compounds Of Iron (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
Description
この発明は鉄を主体とした金属粉からなる磁性
金属粉の製造法に関する。
この種の磁性金属粉は、一般に耐食性に劣り、
経日的に酸化劣化して磁気特性が著るしく低下す
る欠点があるため、この欠点を回避するために予
め気相中ないし液相中で酸素ガス量を調節しなが
ら適度に酸化処理して上記金属粉の表面に緻密な
酸化被膜、主としてマグネタイト被膜を形成する
ことがよく行なわれている。
ところが、上記の酸化処理、とくに気相中での
酸化処理においては、表面積の大きい非常に活性
な金属粉を取り扱うことおよび粉末であるために
反応熱が蓄積しやすいことにより、処理温度の調
整が難しく、酸化条件を終始一定に保ちにくいこ
とから、得られる磁性金属粉の磁気特性がばらつ
く欠点があつた。この発明は、かかる問題がな
く、緻密な酸化被膜を有してかつ磁気特性上も安
定した磁性金属粉を得ることができる新規かつ有
用な磁性金属粉の製造法を提供せんとするもので
ある。
すなわち、この発明者らは、オキシ水酸化鉄な
いし酸化鉄からなる粉末をペレツト状に成形した
のち加熱還元して鉄を主体とするペレツト状の金
属粉を得、これを液相ないし気相中で酸素ガス量
を調節しながら酸化処理して上記ペレツト状金属
粉の粒子表面に酸化被膜を形成し、その後ペレツ
ト化前の所定の粒度に粉砕することにより、緻密
な酸化被膜の形成と磁気特性の安定化とを共に達
成できることを見い出したものである。
この発明においては、ペレツト状の金属粉を得
てこれを酸化処理することにより、従来の如き粉
末状態での表面活性ないし蓄熱を防ぐことを要旨
とするが、この場合に、上記ペレツト状の金属粉
を、オキシ水酸化鉄ないし酸化鉄からなる粉末を
ペレツト状に成形したのち加熱還元することによ
り得ることが重要である。つまり、ペレツト状の
金属粉は、上記粉末を加熱還元したのちにペレツ
ト化することによつても得ることができるが、か
かるペレツト化物をこの発明法に適用したので
は、ペレツト内部にまで一様に均一な酸化被膜を
形成することができず、これを粉砕して得られる
磁性粉はどうしても不均一な酸化被膜を有するも
のとなる。
これに対し、前述の如く、加熱還元前にペレツ
ト化しておくと、これを加熱還元する過程で水分
子や酸素原子の脱離によつてペレツト内部に微細
な孔路が形成されるため、これを引き続く酸化工
程に供したとき、上記孔路を介して内部まで均一
に酸化することができ、酸化被膜の均一性に非常
に好結果がもたらされる。
この発明において、オキシ水酸化鉄ないし酸化
鉄からなる粉末をペレツト状に成形するに当たつ
ては、予めアルミニウム化合物やケイ素化合物の
如き焼結防止剤で表面処理しておくのが望まし
い。ペレツトの大きさとしては、通常0.1〜200
mm、好適には５〜20mm程度である。ペレツト化後
の加熱還元は、常法に準じて行なえばよく、オキ
シ酸化物の場合は、一旦高温下で脱水処理して酸
化物としたのち、加熱還元させるようにしてもよ
い。ペレツト状態での加熱還元は、この工程の作
業性にも好結果を与えるものである。
このようにして得られる鉄を主体としたペレツ
ト状の金属粉は、つぎに、気相中ないし液相中で
の強制的な酸化工程に供される。この酸化工程で
は、被処理粉がペレツト化されているものである
ため酸化反応がゆるやかとなつて反応条件を厳密
に規制しやすく、従来の如く酸化条件の設定、調
節に問題をきたすことはない。
気相中での強制酸化は、一般に100〜10000ppm
の酸素ガスを含有する不活性ガス雰囲気中もしく
は10-2〜10-4atmの減圧酸素雰囲気中で、鉄を主
体とする前記ペレツト状の金属粉を200℃以下の
反応温度で酸化処理するという方法で行なわれ
る。また、液相中での強制酸化は、塩素や臭素を
含まないフツ素系溶媒のほか、トルエンなどの金
属粉に対して不活性な有機溶剤中に鉄を主体とす
る前記ペレツト状の金属粉を分散させ、これに空
気その他の酸化性ガスを導入して通常は130℃以
下の温度で酸化処理するという方法で行なわれ
る。
このようにしてペレツト内部まで均一に酸化処
理したのち、ペレツト化前の粒子径に粉砕するこ
とにより、目的とする緻密な酸化被膜を有してか
つ磁気特性の安定した磁性金属粉を得ることがで
きる。
以下に、この発明の実施例を記載する。
実施例
１Kgのα−FeOOH粉（平均長径0.5μ、軸比8/
１）を含有する40のアルカリ性懸濁液中に、水
500mlに硫酸アルミニウム15.2gを溶解させてなる
溶液と水２にケイ酸ソーダ（Na4SiO4）330gを
溶解させてなる液とを上記順序で添加し、撹拌し
つつ炭酸ガスを吹き込んで液のPHが８となるまで
中和して上記粉末の粒子表面に水酸化アルミニウ
ムとケイ酸ゾルを沈着させた。水洗、乾燥後、約
10mmの大きさに造粒したペレツトをつくり、これ
をマツフル炉で900℃で２時間加熱して脱水した
のち、還元炉を用いて500℃で８時間水素気流中
で加熱還元した。還元炉が冷却した後、酸素ガス
濃度2000ppmの窒素ガスを80℃に予熱し流量
24Nm／時間で導入して酸化処理を行ない、上記
ペレツト状鉄粉末の粒子表面に酸化被膜を形成し
た。このペレツトを造粒前の粒子径に粉砕して、
この発明の磁性金属粉を得た。
この粉末0.63Kgからランダム抽出して100個の
試料をつくり、保磁力（Hc）、飽和磁化量（σs）、
角型比（σr／σs）、σs劣化率およびかさ密度の平
均値を調べた結果は、つぎの表に示されるとおり
であつた。また、σsのばらつきとして、その最高
値と最低値とを調べた結果は、つぎの表に併記さ
れるとおりであつた。なお、表中の比較例とは、
ペレツト化工程を省略した以外は実施例と同様に
加熱還元および酸化処理を行なつて得た磁性金属
粉の試験結果を示したものである。
The present invention relates to a method for producing magnetic metal powder made of metal powder mainly composed of iron. This type of magnetic metal powder generally has poor corrosion resistance,
It has the disadvantage that its magnetic properties deteriorate significantly over time due to oxidative deterioration, so in order to avoid this disadvantage, it is subjected to appropriate oxidation treatment in advance while adjusting the amount of oxygen gas in the gas phase or liquid phase. It is common practice to form a dense oxide film, mainly a magnetite film, on the surface of the metal powder. However, in the above oxidation treatment, especially in the gas phase, it is difficult to adjust the treatment temperature because highly active metal powder with a large surface area is handled and reaction heat tends to accumulate because it is a powder. It is difficult to maintain the oxidation conditions constant from beginning to end, which has the disadvantage that the magnetic properties of the resulting magnetic metal powder vary. The present invention aims to provide a novel and useful method for producing magnetic metal powder that does not have such problems and can obtain magnetic metal powder that has a dense oxide film and stable magnetic properties. . That is, the inventors formed a powder consisting of iron oxyhydroxide or iron oxide into a pellet, then heated and reduced it to obtain a pellet-shaped metal powder mainly composed of iron, and then injected it into a liquid or gas phase. The pelletized metal powder is subjected to oxidation treatment while controlling the amount of oxygen gas to form an oxide film on the particle surface, and is then crushed to a predetermined particle size before pelletization to form a dense oxide film and improve magnetic properties. We have discovered that it is possible to achieve both the stabilization of The gist of this invention is to obtain pellet-like metal powder and oxidize it to prevent surface activation or heat accumulation in the powder state as in the conventional method. It is important to obtain the powder by forming a powder consisting of iron oxyhydroxide or iron oxide into a pellet and then reducing it by heating. In other words, pellet-shaped metal powder can also be obtained by heating and reducing the above-mentioned powder and then pelletizing it, but if such a pelletized product is applied to the method of the present invention, it will not be uniform even inside the pellet. A uniform oxide film cannot be formed on the magnetic powder, and the magnetic powder obtained by pulverizing the powder inevitably has a non-uniform oxide film. On the other hand, as mentioned above, if pelletized before thermal reduction, fine pores are formed inside the pellet due to the elimination of water molecules and oxygen atoms during the thermal reduction process. When subjected to a subsequent oxidation step, the inside can be uniformly oxidized through the pores, resulting in very good uniformity of the oxide film. In the present invention, when the powder made of iron oxyhydroxide or iron oxide is formed into pellets, it is preferable to previously treat the surface with an anti-sintering agent such as an aluminum compound or a silicon compound. The pellet size is usually 0.1 to 200.
mm, preferably about 5 to 20 mm. Thermal reduction after pelletization may be carried out according to a conventional method, and in the case of oxyoxides, the oxide may be subjected to a dehydration treatment at a high temperature and then thermally reduced. Thermal reduction in pellet form also gives good results in the workability of this process. The pellet-like metal powder mainly composed of iron thus obtained is then subjected to a forced oxidation process in a gas phase or a liquid phase. In this oxidation process, since the powder to be treated is pelletized, the oxidation reaction is gradual, making it easy to strictly control the reaction conditions, and there are no problems in setting and adjusting the oxidation conditions as in the past. . Forced oxidation in gas phase is generally 100-10000 ppm
The pellet-shaped metal powder, which is mainly composed of iron, is oxidized at a reaction temperature of 200°C or less in an inert gas atmosphere containing oxygen gas or in a reduced pressure oxygen atmosphere of 10 -2 to 10 -4 atm. done in a method. In addition, forced oxidation in the liquid phase can be carried out in a fluorine-based solvent that does not contain chlorine or bromine, or in an organic solvent that is inert to metal powders such as toluene. This is done by dispersing the oxidizing gas, introducing air or other oxidizing gas, and oxidizing it, usually at a temperature of 130°C or less. After uniformly oxidizing the inside of the pellet in this way, it is pulverized to the particle size before pelletization to obtain the desired magnetic metal powder with a dense oxide film and stable magnetic properties. can. Examples of this invention will be described below. Example 1Kg of α-FeOOH powder (average major axis 0.5μ, axial ratio 8/
1) in a 40% alkaline suspension containing water.
A solution of 15.2 g of aluminum sulfate dissolved in 500 ml and a solution of 330 g of sodium silicate (Na 4 SiO 4 ) dissolved in water 2 were added in the above order, and carbon dioxide gas was blown into the solution while stirring. The powder was neutralized to a pH of 8, and aluminum hydroxide and silicic acid sol were deposited on the surface of the powder particles. After washing and drying, approx.
Pellets granulated to a size of 10 mm were prepared, which were dehydrated by heating at 900°C for 2 hours in a Matsufuru furnace, and then heated and reduced in a hydrogen stream at 500°C for 8 hours using a reduction furnace. After the reduction furnace has cooled, nitrogen gas with an oxygen gas concentration of 2000ppm is preheated to 80℃ and the flow rate is reduced.
Oxidation treatment was performed by introducing the iron powder at a rate of 24 Nm/hour to form an oxide film on the particle surface of the pelletized iron powder. This pellet is crushed to the particle size before granulation,
Magnetic metal powder of this invention was obtained. 100 samples were randomly extracted from 0.63 kg of this powder, and coercive force (Hc), saturation magnetization (σ s ),
The results of examining the average values of squareness ratio (σ r /σ s ), σ s deterioration rate, and bulk density were as shown in the following table. Furthermore, the results of examining the highest and lowest values of σ s were as shown in the table below. In addition, the comparative examples in the table are
The test results are shown for magnetic metal powder obtained by performing thermal reduction and oxidation treatment in the same manner as in the example except that the pelletizing step was omitted.
【表】
率を求めた。
上表から明らかなように、この発明によれば、
緻密な酸化被膜の形成によつて良好な耐食性が得
られているとともに、飽和磁化量のばらつきが小
さくなつている如く磁気特性の安定化の面でも好
結果が得られていることがわかる。[Table] The rate was calculated.
As is clear from the above table, according to this invention,
It can be seen that not only good corrosion resistance is obtained due to the formation of a dense oxide film, but also good results are obtained in terms of stabilization of magnetic properties as the variation in the amount of saturation magnetization is reduced.
Claims (1)
状に成形したのち加熱還元して鉄を主体とするペ
レツト状の金属粉を得、これを液相ないし気相中
で酸素ガス量を調節しながら酸化処理して上記ペ
レツト状金属粉の粒子表面に酸化被膜を形成し、
その後所定の粒度に粉砕することを特徴とする磁
性金属粉の製造法。1 Iron oxyhydroxide or iron oxide powder is formed into pellets, then heated and reduced to obtain pellet-shaped metal powder mainly composed of iron, which is then oxidized in a liquid or gas phase while controlling the amount of oxygen gas. treatment to form an oxide film on the particle surface of the pellet-like metal powder,
A method for producing magnetic metal powder, which comprises subsequently pulverizing it to a predetermined particle size.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57041986A JPS58161711A (en) | 1982-03-16 | 1982-03-16 | Production of magnetic metallic powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57041986A JPS58161711A (en) | 1982-03-16 | 1982-03-16 | Production of magnetic metallic powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58161711A JPS58161711A (en) | 1983-09-26 |
| JPH0470363B2 true JPH0470363B2 (en) | 1992-11-10 |
Family
ID=12623515
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57041986A Granted JPS58161711A (en) | 1982-03-16 | 1982-03-16 | Production of magnetic metallic powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58161711A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61136601A (en) * | 1984-12-05 | 1986-06-24 | Chisso Corp | Production of stabilized ferromagnetic metallic powder |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53114769A (en) * | 1977-02-26 | 1978-10-06 | Toda Kogyo Corp | Metal iron base composite needle metal magnetic grain powder manufacturing process |
| JPS5462915A (en) * | 1977-10-28 | 1979-05-21 | Mitsui Toatsu Chem Inc | Manufacture of ferromagnetic material |
| JPS54122664A (en) * | 1978-03-16 | 1979-09-22 | Kanto Denka Kogyo Kk | Production of magnetic powder for magnetic recording based on iron |
| JPS5655503A (en) * | 1979-10-05 | 1981-05-16 | Hitachi Ltd | Production of metal magnetic powder of superior corrosion resistance |
-
1982
- 1982-03-16 JP JP57041986A patent/JPS58161711A/en active Granted
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS53114769A (en) * | 1977-02-26 | 1978-10-06 | Toda Kogyo Corp | Metal iron base composite needle metal magnetic grain powder manufacturing process |
| JPS5462915A (en) * | 1977-10-28 | 1979-05-21 | Mitsui Toatsu Chem Inc | Manufacture of ferromagnetic material |
| JPS54122664A (en) * | 1978-03-16 | 1979-09-22 | Kanto Denka Kogyo Kk | Production of magnetic powder for magnetic recording based on iron |
| JPS5655503A (en) * | 1979-10-05 | 1981-05-16 | Hitachi Ltd | Production of metal magnetic powder of superior corrosion resistance |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58161711A (en) | 1983-09-26 |
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