JP2614811B2 - Manufacturing method of magnetite powder - Google Patents
Manufacturing method of magnetite powderInfo
- Publication number
- JP2614811B2 JP2614811B2 JP14147493A JP14147493A JP2614811B2 JP 2614811 B2 JP2614811 B2 JP 2614811B2 JP 14147493 A JP14147493 A JP 14147493A JP 14147493 A JP14147493 A JP 14147493A JP 2614811 B2 JP2614811 B2 JP 2614811B2
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- Prior art keywords
- powder
- hematite
- magnetite powder
- magnetite
- added
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- Soft Magnetic Materials (AREA)
Description
【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION
【０００１】[0001]
【産業上の利用分野】本発明は、ヘマタイト粉に有機物
等を加えて不活性ガス中で加熱処理することにより実質
的に単相のマグネタイト粉を製造する方法に関し、更に
詳しく述べると、加熱処理における冷却過程で酸素濃度
を制御することにより、所望の電気抵抗率を有するマグ
ネタイト粉の製造方法に関するものである。製造したマ
グネタイト粉は、特に限定されるものではないが、例え
ば磁性流体、電気抵抗素子、電子写真用のトナーやキャ
リアなどに広く利用できる材料である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a substantially single-phase magnetite powder by adding an organic substance or the like to a hematite powder and performing a heat treatment in an inert gas. The present invention relates to a method for producing a magnetite powder having a desired electric resistivity by controlling an oxygen concentration in a cooling process in the above. Although the produced magnetite powder is not particularly limited, it is a material that can be widely used for, for example, magnetic fluids, electric resistance elements, toners and carriers for electrophotography, and the like.
【０００２】[0002]
【従来の技術】従来、マグネタイト粉を製造するには、
一般に以下の３つの方法が知られている。 湿式法：Ｆｅ2+＋２Ｆｅ3+の水溶液をアルカリ性に
し、共沈させる方法。 乾式法：ヘマタイトを水素・一酸化炭素又は水蒸気中
で加熱・還元する方法。 粉砕法：天然に産する磁鉄鉱を粉砕する方法。2. Description of the Related Art Conventionally, to produce magnetite powder,
Generally, the following three methods are known. Wet method: A method in which an aqueous solution of Fe 2+ + 2Fe 3+ is made alkaline and coprecipitated. Dry method: A method of heating and reducing hematite in hydrogen, carbon monoxide or steam. Grinding method: A method of grinding naturally occurring magnetite.
【０００３】これらによって得られたマグネタイト粉
は、ネットワーク抵抗素子、あるいは電子写真用のトナ
ーやキャリア等に広く使用されている。これらの用途に
おいて電気抵抗率の調整を必要とする場合は、マグネタ
イト粉と樹脂等との混合やマグネタイト粉への樹脂コー
ティングという手法を採用していた。[0003] The magnetite powder obtained by these methods is widely used in network resistance elements, toners and carriers for electrophotography, and the like. When the electric resistivity needs to be adjusted in these applications, a method of mixing magnetite powder with a resin or the like and coating the magnetite powder with a resin has been employed.
【０００４】[0004]
【発明が解決しようとする課題】しかし、上記のような
従来のマグネタイト粉の製造方法は、それぞれ次のよう
な欠点があり、必ずしも満足しうるものではない。 湿式法：共沈により容易に比較的純度の高い微粒子が
得られるものの、製造コストが高く量産には適さない。 乾式法：高圧力水蒸気または水素・一酸化炭素等の比
較的強力な還元性雰囲気下で反応させるため、量産には
危険を伴い、且つ設備が大掛かりとなる。 粉砕法：天然鉱物を出発原料に用いるため、長期間に
わたって安定して高品質の粉体を生産することが難し
い。However, the conventional methods for producing magnetite powder as described above have the following disadvantages, and are not always satisfactory. Wet method: Although relatively pure particles can be easily obtained by coprecipitation, the production cost is high and it is not suitable for mass production. Dry method: Since the reaction is carried out in a relatively strong reducing atmosphere such as high-pressure steam or hydrogen / carbon monoxide, mass production involves danger and requires large-scale equipment. Grinding method: Since a natural mineral is used as a starting material, it is difficult to stably produce high-quality powder over a long period of time.
【０００５】またマグネタイト粉と樹脂との混合、ある
いはマグネタイト粉への樹脂コーティングでは、樹脂の
選定や付着方法に工夫が必要であり、きめ細かな電気抵
抗率の制御は不可能であった。[0005] In addition, in the case of mixing magnetite powder with a resin or coating the magnetite powder with a resin, it is necessary to devise the selection and adhesion method of the resin, and it is impossible to control the electrical resistivity in a fine manner.
【０００６】本発明の目的は、上記のような従来法に比
較して簡便な設備、単純な工程によって、所望の電気抵
抗率を有する高品質の単相マグネタイト粉を大量に且つ
安価に安全に製造できる方法を提供することである。An object of the present invention is to provide high-quality, single-phase magnetite powder having a desired electrical resistivity in a large amount, at low cost, and safely by using simple equipment and simple processes as compared with the conventional method as described above. It is to provide a method that can be manufactured.
【０００７】[0007]
【課題を解決するための手段】本発明は、ヘマタイト粉
に、炭素原子同士の単結合又は二重結合を有する液状
（液体又は溶液）又は粉末状物質を、０．１〜４．０重
量％加え、ほぼ均一に混合した後、不活性ガス中で１２
００〜１４５０℃で加熱処理し、冷却中に３００℃以下
において酸素濃度を０．１〜２１％に制御するマグネタ
イト粉の製造方法である。ここで、不活性ガス中での加
熱処理前に、造粒処理によりヘマタイト粉を球状顆粒に
しておけば、球状のマグネタイト粉を得ることができ
る。According to the present invention, a liquid (liquid or solution) or a powdery substance having a single bond or a double bond between carbon atoms is added to a hematite powder in an amount of 0.1 to 4.0% by weight. In addition, after mixing almost uniformly, 12 minutes in an inert gas
This is a method for producing magnetite powder in which heat treatment is performed at 00 to 1450 ° C. and the oxygen concentration is controlled to 0.1 to 21% at 300 ° C. or less during cooling. Here, if the hematite powder is converted into spherical granules by a granulation treatment before the heat treatment in an inert gas, a spherical magnetite powder can be obtained.
【０００８】本発明は加熱処理でヘマタイト粉を単相の
マグネタイト粉に熱転移できることが前提となる。その
ためには、まず、添加する物質とその添加量、加熱温度
が上記のような条件を満たさねばならない。ここでヘマ
タイト粉に添加する物質は、酸素を与えて燃焼させるこ
とができるような炭素原子同士の単結合又は二重結合を
有する物質であればよい。一般には例えば、粉末成形な
どに用いる有機結合剤や分散剤などの有機物を用いる。
球形に造粒する場合には、そのような有機結合剤を使用
するから、その場合には有機結合剤が造粒工程での結合
剤としての作用と加熱処理工程での還元作用を兼用する
ことができる。その他、アセチレンブラックやグラファ
イトなども使用可能である。これらの物質を添加するの
は、それらが無いと加熱温度を変えても単相マグネタイ
トが得られない（Ｘ線的に見るとα−Ｆｅ2 Ｏ3 又はＦ
ｅＯの相が存在する）ためである。また、その添加範囲
を０．１〜４．０重量％とするのは、０．１重量％未満
では添加による還元効果に乏しく、逆に４．０重量％を
超えると、それ以上添加する意味が無いし、造粒工程が
入る場合にはかえって造粒がうまくできず、更に多くな
ると生成するマグネタイト粉中に有機物の不完全燃焼に
より生成した炭素などの異物が残存し好ましくないため
である。更に、加熱温度（トップ温度）を１２００〜１
４５０℃とするのは、１２００℃未満ではα−Ｆｅ2 Ｏ
3 が残り、１４５０℃を超えるとＦｅＯの相が現れるか
らである。The present invention is based on the premise that hematite powder can be thermally transformed into single-phase magnetite powder by heat treatment. For that purpose, first, the substance to be added, its addition amount, and the heating temperature must satisfy the above conditions. Here, the substance to be added to the hematite powder may be a substance having a single bond or a double bond between carbon atoms that can be burned by supplying oxygen. Generally, for example, organic substances such as an organic binder and a dispersant used for powder molding and the like are used.
In the case of granulating in a spherical shape, such an organic binder is used. In this case, the organic binder serves both as a binder in the granulation step and a reducing action in the heat treatment step. Can be. In addition, acetylene black, graphite, and the like can be used. If these substances are added, single phase magnetite cannot be obtained even if the heating temperature is changed without them (from the viewpoint of X-rays, α-Fe 2 O 3 or F
eO phase is present). Further, the addition range of 0.1 to 4.0% by weight means that if it is less than 0.1% by weight, the reduction effect by addition is poor, and if it exceeds 4.0% by weight, it is added more. This is because, when a granulation step is performed, granulation cannot be performed well, and when the amount is further increased, foreign substances such as carbon generated by incomplete combustion of organic substances remain in the generated magnetite powder, which is not preferable. Further, the heating temperature (top temperature) is set to 1200 to 1
The reason why the temperature is set to 450 ° C. is that α-Fe 2 O
This is because FeO phase appears when 3 remains and exceeds 1450 ° C.
【０００９】冷却時における酸素濃度の下限値を０．１
％としたのは、量産時に０．１％未満の制御は非常に困
難だからである。また酸素を供給する切換え温度を３０
０℃以下としたのは、酸素濃度０．１％以上で切換え温
度が３００℃を超えると、ヘマタイト相が残るからであ
る。[0009] The lower limit of the oxygen concentration during cooling is 0.1
The reason is that the control of less than 0.1% is very difficult during mass production. The switching temperature for supplying oxygen is 30.
The reason why the temperature is set to 0 ° C. or less is that when the switching temperature exceeds 300 ° C. at an oxygen concentration of 0.1% or more, a hematite phase remains.
【００１０】[0010]
【作用】金属酸化物と有機物とを混合した状態で不活性
ガス雰囲気中で加熱すると、金属酸化物は還元される。
例えば有機物としてプロピレン（ＣＨ3 ＣＨ＝ＣＨ2 ）
を用いた場合、プロピレンが金属酸化物表面では、酸化
物中のＯ-2にＨ+ を奪われてπアリル中間体となる。こ
のような反応は、有機物の種類によらずほぼ同様であ
る。上記のπアリル中間体に酸素が付加されればアクロ
レイン、さもなければ２つのπアリル中間体が二量化し
てベンゼンとなる。この場合、πアリル中間体となるに
は炭素−炭素間の二重結合が必要であるが、金属酸化物
上でＨ+ を奪われることにより炭素−炭素間の単結合が
二重結合に変化するため、最初の状態では炭素−炭素間
の単結合のみでもよい。例えばポリビニルアルコールは
炭素−炭素間の二重結合を持たないが、還元能力は充分
にある。When a mixture of a metal oxide and an organic substance is heated in an inert gas atmosphere, the metal oxide is reduced.
For example, propylene (CH 3 CH = CH 2 ) as an organic substance
When propylene is used, on the surface of the metal oxide, propylene is deprived of H + by O -2 in the oxide to become a π allyl intermediate. Such a reaction is almost the same regardless of the type of the organic substance. If oxygen is added to the above-mentioned π-allyl intermediate, acrolein is produced, otherwise two π-allyl intermediates are dimerized to benzene. In this case, a carbon-carbon double bond is required to become a π-allyl intermediate, but a carbon-carbon single bond is changed to a double bond by depriving H + on the metal oxide. In the initial state, only a single bond between carbon and carbon may be used. For example, polyvinyl alcohol does not have a carbon-carbon double bond, but has a sufficient reducing ability.
【００１１】ヘマタイト（α−Ｆｅ2 Ｏ3 ）を有機物と
混合した状態で不活性ガス中で加熱処理すると、不完全
燃焼状態となり、有機物の熱分解時にヘマタイトから酸
素を奪うことにより該ヘマタイトが還元され、Ｘ線的に
みて単相の（純度ほぼ１００％の）マグネタイト（Ｆｅ
3 Ｏ4 ）に熱転移する。この反応は、極めて効率が良
く、例えば一般のフェライト製造設備を用いて匣鉢に厚
さ数cmにヘマタイト粉を充填して供給しても、それ全体
が良好なマグネタイト粉になる。つまり本発明は有機物
などの不完全燃焼を積極的に利用し、発生したガスを用
いてヘマタイト粉を還元処理しているのである。When hematite (α-Fe 2 O 3 ) is mixed with an organic substance and heat-treated in an inert gas, an incomplete combustion state occurs, and the hematite is reduced by removing oxygen from the hematite during thermal decomposition of the organic substance. And a single phase (purely 100% pure) magnetite (Fe
3 O 4) To heat transfer. This reaction is extremely efficient. For example, even if hematite powder is filled into a sagger with a thickness of several centimeters and supplied using a general ferrite production facility, the whole becomes a good magnetite powder. That is, the present invention positively utilizes incomplete combustion of organic substances and the like, and reduces hematite powder using the generated gas.
【００１２】因に、有機物等を混入することなく、ヘマ
タイト粉のみを用いて不活性ガス中で加熱処理した場
合、少量のヘマタイト粉を匣鉢の表面に薄く撒いて且つ
長時間にわたって処理すると、一部がマグネタイト粉に
変化することが認められたが、生産効率は極めて低く、
とうてい工業化しうるものではなかった。When heat treatment is carried out in an inert gas using only hematite powder without mixing organic matter or the like, when a small amount of hematite powder is thinly spread on the surface of the sagger and treated for a long time, Although it was recognized that some of them changed to magnetite powder, the production efficiency was extremely low,
It was not something that could be industrialized.
【００１３】加熱処理における冷却過程で酸素を雰囲気
に切り換えると、マグネタイト粉の表面が酸化される。
但し、この酸化は、上記のような本発明の条件を満たし
ていれば極く僅かで、粉末Ｘ線回折による定性分析では
マグネタイト相以外は検出できないほどであり、実質的
にはマグネタイト単相と言える。このように粒子表面の
改質は極く僅かであるにもかかわらず、マグネタイト粉
の電気抵抗率は、上記の処理によって２桁程度以上上昇
し、所望の電気的特性の調整が可能となる。When oxygen is switched to the atmosphere during the cooling process in the heat treatment, the surface of the magnetite powder is oxidized.
However, this oxidation is negligible if the conditions of the present invention as described above are satisfied, and the qualitative analysis by powder X-ray diffraction is such that only the magnetite phase can be detected. I can say. As described above, the electric resistivity of the magnetite powder is increased by about two digits or more by the above-mentioned treatment, and the desired electric characteristics can be adjusted, although the modification of the particle surface is extremely slight.
【００１４】[0014]
【実施例】原料であるヘマタイト粉にポリビニルアルコ
ール２重量％、分散剤としてポリカルボン酸塩１重量％
を加え、水と混合してヘマタイト濃度５０重量％のスラ
リーとした。そのスラリーをアトライターで１時間攪拌
後、スプレードライヤーで造粒、顆粒化した。得られた
顆粒を窒素雰囲気中で１２００〜１４００℃（トップ温
度）で２時間加熱処理した。そして、そのまま窒素雰囲
気中で冷却したものと、冷却中に所定の切換温度で窒素
雰囲気から酸素を含む雰囲気に切り換えたものとを作製
した。加熱処理時の温度制御プログラムを図１に示す。
ガス中の酸素濃度はジルコニア式酸素濃度計で測定し
た。処理後の各試料の電気抵抗率は、特開平１−１１２
１７号公報に記載されている方法に準じて行った。粉体
の電気抵抗率測定は環境湿度の影響を多大に受けるた
め、測定はすべての試料を同時に２時間以内で行った。
また粉体の物質相の同定は粉末Ｘ線回折定性分析により
行った。実験結果を表１に示す。EXAMPLE 2% by weight of polyvinyl alcohol and 1% by weight of polycarboxylate as a dispersant were added to a raw material of hematite powder.
Was added and mixed with water to obtain a slurry having a hematite concentration of 50% by weight. After the slurry was stirred for 1 hour with an attritor, it was granulated and granulated with a spray drier. The obtained granules were heated in a nitrogen atmosphere at 1200 to 1400 ° C. (top temperature) for 2 hours. Then, one was cooled in a nitrogen atmosphere as it was, and another was switched from a nitrogen atmosphere to an atmosphere containing oxygen at a predetermined switching temperature during cooling.
I did . FIG. 1 shows a temperature control program during the heating process.
The oxygen concentration in the gas was measured with a zirconia oxygen meter. The electrical resistivity of each sample after the treatment is described in JP-A-1-112.
No. 17 was carried out according to the method described. powder
Electrical resistivity measurement is greatly affected by environmental humidity
Therefore, the measurement was performed on all the samples simultaneously within 2 hours.
The substance phase of the powder was identified by powder X-ray diffraction qualitative analysis. Table 1 shows the experimental results.
【００１５】[0015]
【表１】 [Table 1]
【００１６】上記の実験結果から、次のことが判明し
た。 冷却中に雰囲気切換えを行わずに最後まで窒素雰囲気
中で冷却した試料（比較例）では、単相マグネタイトが
得られるが、粉体の電気抵抗率は加熱温度によらず全て
１．５〜２．０×１０4 Ω・cm程度である。 冷却中の雰囲気切換え温度を３５０℃とすると、電気
抵抗率は著しく高くなるものの、酸素濃度０．１％でも
ヘマタイト相が残り、単相マグネタイト粉は得られな
い。 雰囲気切換え温度が一定でも酸素濃度が高くなるほど
電気抵抗率は高くなり、同じ酸素濃度の場合には雰囲気
切換え温度が高いほど電気抵抗率は高くなる。切換え温
度が３００℃以下の場合は、空気中での冷却でも、ヘマ
タイト相は生じない。 冷却過程における雰囲気切換えとその時の酸素濃度を
制御することで、電気抵抗率を１．５×１０4 〜６．４
×１０6 Ω・cmの範囲で自由に調整することができる。From the above experimental results, the following has been found. In a sample (comparative example) cooled to the end without switching the atmosphere during cooling (comparative example), single-phase magnetite is obtained, but the electrical resistivity of the powder is 1.5 to 2 regardless of the heating temperature. It is about 0.010 4 Ω · cm. When the atmosphere switching temperature during cooling is 350 ° C., the electrical resistivity is significantly increased, but the hematite phase remains even at an oxygen concentration of 0.1%, and a single-phase magnetite powder cannot be obtained. Even when the atmosphere switching temperature is constant, the electrical resistivity increases as the oxygen concentration increases, and in the case of the same oxygen concentration, the electrical resistivity increases as the atmosphere switching temperature increases. When the switching temperature is 300 ° C. or lower, no hematite phase occurs even when cooled in air. By changing the atmosphere during the cooling process and controlling the oxygen concentration at that time, the electric resistivity is set to 1.5 × 10 4 to 6.4.
It can be adjusted freely within the range of × 10 6 Ω · cm.
【００１７】上記の実施例では添加する物質として全て
ボリビニルアルコールを用いているが、種々の実験の結
果、ポリアクリルアミド、ポリイソブチレン、ポリカル
ボン酸塩、アルキルナフタレンスルホン酸塩（以上は水
溶液で添加する）、ポリビニルブチラール、ステアリン
酸（以上はアルコール溶液又は分散液で添加する）、ア
セチレンブラック、グラファイト（以上は粉体で添加し
アルコールを加えて混合する）などでも同様に単相マグ
ネタイト粉が得られることが確認されており、本発明で
使用可能である。In the above embodiment, polyvinyl alcohol is used as the substance to be added. However, as a result of various experiments, polyacrylamide, polyisobutylene, polycarboxylate, and alkylnaphthalene sulfonate (the above-mentioned substances are added in aqueous solution) ), Polyvinyl butyral, stearic acid (the above is added as an alcohol solution or dispersion), acetylene black, graphite (the above is added as a powder and the alcohol is added and mixed), etc., to obtain a single-phase magnetite powder in the same manner. Has been confirmed and can be used in the present invention.
【００１８】[0018]
【発明の効果】本発明は上記のように、ヘマタイト粉に
有機物などを適量添加して不活性ガス中で加熱処理する
方法なので、容易に且つ安価に、高品質の単相マグネタ
イト粉を製造できる。また通常のフェライト生産設備を
利用でき、匣鉢に一度に多量のヘマタイト粉を入れて処
理できるため、極めて生産効率が良好となる。その上、
冷却中に所定温度で所定の酸素濃度の雰囲気に切り換え
る方法なので、酸素濃度と切換温度を制御することによ
り、実質的に単相マグネタイト粉であって、しかもその
電気抵抗率を所望の値に容易に調整することができる。As described above, according to the present invention, a high quality single phase magnetite powder can be easily and inexpensively manufactured because the organic material or the like is added to hematite powder in an appropriate amount and heat treatment is performed in an inert gas. . In addition, since ordinary ferrite production equipment can be used and a large amount of hematite powder can be put into the sagger at once and processed, the production efficiency becomes extremely good. Moreover,
Since it is a method of switching to an atmosphere with a predetermined oxygen concentration at a predetermined temperature during cooling, by controlling the oxygen concentration and the switching temperature, it is substantially a single-phase magnetite powder, and its electrical resistivity can be easily adjusted to a desired value. Can be adjusted.
【図１】本発明における加熱処理時の温度制御プログラ
ムを示す説明図。FIG. 1 is an explanatory diagram showing a temperature control program at the time of a heat treatment in the present invention.
Ｔ トップ温度 ｘ 切換温度 T top temperature x switching temperature
───────────────────────────────────────────────────── フロントページの続き (72)発明者 下川 明 東京都港区新橋５丁目36番11号 富士電 気化学株式会社内 (56)参考文献 特開 昭55−104924（ＪＰ，Ａ) 特公 昭59−7646（ＪＰ，Ｂ２) 特公 昭53−24637（ＪＰ，Ｂ２) 米国特許2900236（ＵＳ，Ａ) ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akira Shimokawa 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (56) References JP-A-55-104924 (JP, A) Sho 59-7646 (JP, B2) Japanese Patent Publication Sho 53-24637 (JP, B2) US Patent 2,900,236 (US, A)
Claims (3)
又は二重結合を有する液状又は粉末状物質を０．１〜
４．０重量％加え、ほぼ均一に混合した後、不活性ガス
中で１２００〜１４５０℃で加熱処理し、冷却中に３０
０℃以下において酸素濃度を０．１〜２１％に制御する
ことを特徴とするマグネタイト粉の製造方法。1. A liquid or powdery substance having a single bond or a double bond between carbon atoms is added to a hematite powder in an amount of 0.1 to 0.1.
After adding 4.0% by weight and mixing almost uniformly, the mixture was heat-treated at 1200 to 1450 ° C. in an inert gas.
A method for producing magnetite powder, wherein the oxygen concentration is controlled to 0.1 to 21% at 0 ° C or lower.
する液状又は粉末状物質が有機結合剤である請求項１記
載の方法。2. The method according to claim 1, wherein the liquid or powdery substance having a single bond or a double bond between carbon atoms is an organic binder.
合剤を加え、造粒処理によりヘマタイト粉を球状顆粒と
し、生成するマグネタイト粉を球状とする請求項２記載
の方法。3. The method according to claim 2, wherein an organic binder is added before the heat treatment in an inert gas, and the hematite powder is formed into spherical granules by a granulation treatment, and the generated magnetite powder is formed into a spherical shape.
Priority Applications (11)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14147493A JP2614811B2 (en) | 1993-05-20 | 1993-05-20 | Manufacturing method of magnetite powder |
| TW083102501A TW251373B (en) | 1993-05-20 | 1994-03-22 | |
| AU62922/94A AU6292294A (en) | 1993-05-20 | 1994-03-31 | Process for manufacturing homogeneous magnetite |
| BR9405363-4A BR9405363A (en) | 1993-05-20 | 1994-03-31 | Process for producing a single-phase magnetite powder |
| EP94910579A EP0653379B1 (en) | 1993-05-20 | 1994-03-31 | Process for manufacturing homogeneous magnetite |
| CA002133642A CA2133642C (en) | 1993-05-20 | 1994-03-31 | Process for producing single phase magnetite powder |
| DE69403611T DE69403611T2 (en) | 1993-05-20 | 1994-03-31 | METHOD FOR PRODUCING HOMOGENIC MAGNETITE |
| CN94190295A CN1037836C (en) | 1993-05-20 | 1994-03-31 | Process for manufacturing homogeneous mgnetite |
| KR1019940704668A KR100279651B1 (en) | 1993-05-20 | 1994-03-31 | Method for manufacturing single phase magnetite powder |
| US08/313,152 US5512195A (en) | 1993-05-20 | 1994-03-31 | Process for producing single phase magnetite powder |
| PCT/JP1994/000531 WO1994027911A1 (en) | 1993-05-20 | 1994-03-31 | Process for manufacturing homogeneous magnetite |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14147493A JP2614811B2 (en) | 1993-05-20 | 1993-05-20 | Manufacturing method of magnetite powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06329419A JPH06329419A (en) | 1994-11-29 |
| JP2614811B2 true JP2614811B2 (en) | 1997-05-28 |
Family
ID=15292733
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14147493A Expired - Fee Related JP2614811B2 (en) | 1993-05-20 | 1993-05-20 | Manufacturing method of magnetite powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2614811B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2860356B2 (en) * | 1994-02-15 | 1999-02-24 | 富士電気化学株式会社 | Oxide magnetic material and method for producing the same |
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1993
- 1993-05-20 JP JP14147493A patent/JP2614811B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06329419A (en) | 1994-11-29 |
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