JPS5919168B2 - Manufacturing method of metal magnetic powder - Google Patents

Description

【発明の詳細な説明】 この発明は金属鉄を主体とする金属磁性粉末の製造方法
に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing metal magnetic powder mainly composed of metal iron.

一般的に、金属鉄を主体とする磁性粉末は、Ｆｅ３ｏ４
やに−Ｆｅ２ｑなどの酸化鉄系磁性粉末に比較して保磁
力（Ｈｃ）などの磁気特性に優れる利点を有しており、
磁気テープを始めとする種々の磁気記録媒体用の記録素
子として脚光を浴びている。Generally, magnetic powder mainly composed of metallic iron is Fe3o4
It has the advantage of superior magnetic properties such as coercive force (Hc) compared to iron oxide magnetic powders such as Yani-Fe2q.
It has been in the spotlight as a recording element for various magnetic recording media including magnetic tape.

しかしながら、この種の磁性粉末は通常、オキシ水酸化
鉄もしくは酸化鉄の針状粒子からなる粉末を気相中で加
熱環元して製造されるため、加熱環元時に粒子相互間の
焼結や個々の粒子の部分的な溶融による形崩れが起こり
易く、粒度の不均一化や針状性が損なわれることによつ
て磁気特性が著しく低下する傾向がある。このような事
情から、従来より加熱環元時に原料粒子の均一性と針状
形状を維持させる目的で種々の提案がなされているが、
いずれもまだ十分ではない。この発明者らは、上記の加
熱環元時の問題点を克服して金属鉄を主体とする磁性粉
末の磁気特性を改善するために綿密な研究を重ねた結果
、被環元物の粒子表面をアルミニウム成分とケイ素成分
の２成分で被覆した場合に良好な結果が得られ、さらに
、被環元物の粒子表面にまずアルミニウム化合物を被着
してこれを加熱処理し、処理後の粉末粒子を水溶性ケイ
酸塩のアルカリ水溶液中に分散して液を中和することに
よつて粒子表面にケイ酸ゾルを沈着させ、アルミニウム
成分とケイ素成Ｊ 分との２層の被覆を施した場合に、
加熱環元時の焼結や形崩れが最も効果的に抑制されて優
れた磁気特性を有する磁性粉末が得られることを究明し
た。However, this type of magnetic powder is usually produced by heating and annealing powder consisting of acicular particles of iron oxyhydroxide or iron oxide in a gas phase, so that sintering between particles occurs during heating annealing. Individual particles tend to lose their shape due to partial melting, and magnetic properties tend to deteriorate significantly due to uneven particle size and loss of acicularity. Under these circumstances, various proposals have been made to maintain the uniformity and acicular shape of raw material particles during heating annealing.
Both are still not enough. The inventors conducted detailed research to overcome the above-mentioned problems during heating and improve the magnetic properties of magnetic powder mainly composed of metallic iron. Good results were obtained when the aluminum compound was coated with two components, an aluminum component and a silicon component.Furthermore, an aluminum compound was first coated on the surface of the particles of the ring target, and this was heat-treated, and the powder particles after the treatment were In the case where a silicic acid sol is deposited on the particle surface by dispersing it in an alkaline aqueous solution of a water-soluble silicate and neutralizing the liquid, and a two-layer coating of an aluminum component and a silicon component is applied. To,
It has been found that sintering and deformation during heating are most effectively suppressed, and a magnetic powder with excellent magnetic properties can be obtained.

上記のこの発明の方法によれば、最初に被着し・ たア
ルミニウム化合物が加熱処理によつて不働態化され、か
つ強固で緻密な被膜となり、この被膜上に後工程でケイ
酸被膜が被着されて２重層となハーり、この働きによつ
て焼結および形崩れが強力に抑制される。According to the method of the present invention described above, the aluminum compound deposited first is made passivated by heat treatment and becomes a strong and dense film, and a silicic acid film is formed on this film in a subsequent process. The material is hardened to form a double layer, and this function strongly suppresses sintering and deformation.

これに対して、上記の加熱処理を伴なわない場合は、後
工程のケイ素化合物の被着処理時に最初に被着したアル
ミニウム化合物が脱離し易くなるばかりでなく、アルミ
ニウム化合物の被膜が粗雑なものとなり、所期の目的を
達成することが困難となる。特に、この傾向は、ケイ素
化合物の被着処理として、水溶性ケイ酸塩のアルカリ性
水溶液を使用した際に顕著となり易い。さらに、この発
明の方法は、アルミニウム化合物とケイ素化合物とを逆
の順序で被着させる方法ならびに両者を同時に被着させ
る方法に比較しても、より良好な結果が得られている〇
使用するアルミニウム化合物としては、硫酸アルミニウ
ム、硝酸アルミニウム、塩化アルミニウムなどの水可溶
性塩、およびアルミン酸ナトリウムなどの水可溶性アル
ミン酸塩が挙げられ、通常はこれらをアルカリ水溶液中
に溶解させて、この溶液中に被環元物粉末を分散させ、
炭酸ガスの吹き込みや酸の添加にて中和させることによ
つて結晶質ないし非晶質の水酸化アルミニウムとして粒
子表面に被着させる。On the other hand, if the above heat treatment is not involved, not only will the initially deposited aluminum compound be easily removed during the silicon compound deposition process in the subsequent process, but also the aluminum compound coating will be rough. This makes it difficult to achieve the intended purpose. In particular, this tendency tends to become noticeable when an alkaline aqueous solution of a water-soluble silicate is used as a treatment for adhering a silicon compound. Furthermore, the method of the present invention provides better results than a method of depositing an aluminum compound and a silicon compound in the reverse order or a method of depositing both at the same time. Compounds include water-soluble salts such as aluminum sulfate, aluminum nitrate, aluminum chloride, and water-soluble aluminates such as sodium aluminate, and are typically dissolved in an alkaline aqueous solution and coated in this solution. Disperse the ring element powder,
By neutralizing it by blowing carbon dioxide gas or adding acid, it is deposited on the particle surface as crystalline or amorphous aluminum hydroxide.

その使用量は被環元物であるオキシ水酸化鉄もしくは酸
化鉄に対してＡレＦｅの原子換算重量比で０，０１〜１
．０ｗｔ％程度が良好であり、過少では実質的な効果が
期待できず、過多では逆に粒子の多孔化や形崩れを惹起
する恐れがある。オキシ水酸化鉄および酸化鉄としては
、α−Ｆｅ−００１１ｓα−Ｆｅ２Ｏ３、γ−Ｆｅ２Ｏ
３、Ｆｅ３Ｏ４卦よびこれらの中間型に相当するものが
挙げられ、コバルトやクロムなどの他の種々の金属成分
を少量含むものであつてもよく、針状性の良いものが望
ましい０アルミニウム化合物被着後の加熱処理は、１５
０℃以上の温度でかつ好適には６００℃以下の温度で行
なうことが推奨され、この加熱によつてアルミニウム成
分は低温度域では含水酸化物、高温度域では酸化物（非
晶質を含む）となつて、アルカリ水溶液中で溶出しない
形態となり、かつ被膜が非常に緻密となる。The amount used is 0.01 to 1 in terms of the atomic weight ratio of A to Fe to the ring element iron oxyhydroxide or iron oxide.
．． Approximately 0 wt% is good; if it is too little, no substantial effect can be expected, and if it is too much, it may cause the particles to become porous or lose their shape. As iron oxyhydroxide and iron oxide, α-Fe-0011sα-Fe2O3, γ-Fe2O
3. Fe3O4 trigrams and intermediate types thereof may be mentioned, and they may contain small amounts of various other metal components such as cobalt and chromium, and those with good acicularity are desirable.0 Aluminum compound adhesion The subsequent heat treatment was performed at 15
It is recommended that the heating be carried out at a temperature of 0°C or higher, preferably 600°C or lower, and this heating converts the aluminum component into hydrous oxides at low temperatures and oxides (including amorphous) at high temperatures. ), which does not dissolve in alkaline aqueous solutions, and the film is very dense.

被環元物としてオキシ水酸化鉄より加熱脱水を経て得ら
れる酸化鉄を使用する場合、脱水前のオキシ水酸化鉄も
しくは脱水後の酸化鉄に対して上記の２段階の被覆処理
を行なうこともできるが、この発明の好適な態様として
、オキシ水酸化鉄にアルミニウム化合物を被着して上記
の加熱処理を兼ねて加熱脱水を行ない、得られたアルミ
ニウム成分の被膜を有する酸化鉄粉末の粒子表面にケイ
酸の被膜を形成する方法が推奨され、この方法によれば
熱処理が１回で済み、加熱後の再粉砕処理を省くことが
でき、工程が簡略化されると共に加熱脱水時における粒
子の焼結や形崩れが被着されたアルミニウム成分によつ
て抑制される効果があるＯケイ素化合物の被着は、水溶
性ケイ酸塩、シリコンオイル、シランなどの無機あるい
は有機ケイ素化合物を水あるいは有機溶媒中に溶解ある
いは分散させた液中にアルミニウム成分の被膜を有する
オキシ水酸化鉄もしくは酸化鉄を分散させることによつ
て行なうことができるが、特に既述のように水溶性ケイ
酸塩のアルカリ性水溶液中にアルミニウム成分の被膜を
有するオキシ水酸化鉄もしくは酸化鉄を分散させ、炭酸
ガスの吹き込みや酸の添加によつて液を中和し、粒子表
面にケイ酸ゾルを沈着させる方法が推奨さわる。When using iron oxide obtained from iron oxyhydroxide through thermal dehydration as the ring target, the two-step coating treatment described above may be applied to the iron oxyhydroxide before dehydration or to the iron oxide after dehydration. However, as a preferred embodiment of the present invention, iron oxyhydroxide is coated with an aluminum compound and heated and dehydrated in combination with the above heat treatment, so that the surface of the particles of iron oxide powder having a coating of the aluminum component obtained is A method in which a silicic acid film is formed is recommended. This method requires only one heat treatment, eliminates the need for re-grinding after heating, and simplifies the process and reduces particle size during heat dehydration. The adhesion of silicon compounds, which have the effect of suppressing sintering and deformation due to the applied aluminum component, can be achieved by adding inorganic or organic silicon compounds such as water-soluble silicate, silicone oil, or silane to water or organic silicon compounds. This can be carried out by dispersing iron oxyhydroxide or iron oxide having a coating of aluminum component in a liquid dissolved or dispersed in a solvent, but in particular, as mentioned above, the alkalinity of water-soluble silicate The recommended method is to disperse iron oxyhydroxide or iron oxide with an aluminum component coating in an aqueous solution, neutralize the liquid by blowing carbon dioxide gas or adding acid, and deposit silicate sol on the particle surface. .

使用する水溶性ケイ酸塩としては、オルトケイ酸ナトリ
ウム、メタケイ酸ナトリウム、メタケイ酸カリウムおよ
び種々の組成の水ガラスが挙げられ、これらはＳｉ／Ｆ
ｅの原子換算重量比として０．１〜１０ｗｔｆ）となる
量を使用でき、少ない場合は焼結や形崩れの防止効果が
十分ではなく、多い場合は環元生成物である金属鉄を主
体とする粉末の飽和磁化（σ３）の低下が大きいため、
最適には上記比で０．３〜２ｗｔ（ｆ）となる量が推奨
される〇上記の被着処理を経たオキシ水酸化鉄または酸
化鉄は、水洗、乾燥などの通常の処理を行なつたのち、
水素気流中などの環元性雰囲気中で３００〜６００℃程
度の温度下で加熱することにより、アルミニウムおよび
ケイ素を含有した金属鉄を主体とする粉末となり、この
粉末は原料のオキシ水酸化鉄または酸化鉄の針状形状と
均一性を継承し、優れた磁気特性を有している。The water-soluble silicates used include sodium orthosilicate, sodium metasilicate, potassium metasilicate and water glasses of various compositions, including Si/F
An amount of 0.1 to 10 wtf (as the atomic weight ratio of e) can be used; if it is small, the effect of preventing sintering and deformation will not be sufficient, and if it is large, metal iron, which is a ring element product, will be used as the main component. Because the saturation magnetization (σ3) of the powder is greatly reduced,
The optimal amount is recommended to be 0.3 to 2 wt(f) based on the above ratio.The iron oxyhydroxide or iron oxide that has undergone the above deposition treatment should be subjected to normal treatments such as washing with water and drying. after,
By heating at a temperature of about 300 to 600°C in a cyclic atmosphere such as a hydrogen stream, a powder mainly composed of metallic iron containing aluminum and silicon is obtained. It inherits the acicular shape and uniformity of iron oxide, and has excellent magnetic properties.

以下、実施例にてこの発明を詳細に説明する。The present invention will be explained in detail below with reference to Examples.

実施例 １８００ｄの水中に１０ｇのα−ＦｅＯＯＨ粉
末（平均長径０．５μ、軸比２０／１）を分散した懸濁
液中に、１Ｎ−ＮａＯＨ７ｉ＜．溶液１００ｍｅ中に０
．０１ＭＯｌｅ／ｔ濃度の硫酸アルミニウム水溶液１０
ｍ１を加えた液を添加し、攪拌しつつ炭酸ガスを液のＰ
Ｈが６〜８となるまで吹き込んで中和し、水洗、乾燥し
て水酸化アルミニウムの被膜を有するα一ＦｅＯＯＨ粉
末を得た。Example 1N-NaOH7i<. 0 in 100me of solution
．． Aluminum sulfate aqueous solution with a concentration of 01 MOle/t 10
m1 of the liquid was added, and while stirring the carbon dioxide gas was added to the P of the liquid.
The mixture was neutralized by blowing until H became 6 to 8, washed with water, and dried to obtain α-FeOOH powder having an aluminum hydroxide coating.

これを電気炉中で３００にて２時間加熱し、酸化アルミ
ニウムの被膜を有するα−Ｆｅ２Ｏ３を得た。次いでこ
れを８００ｍ！．の水中に再び分散し、１Ｎ−ＮａＯＨ
水溶液５０ｍｅおよび１ｍ０１ｅ／ｔ濃度のオルトケイ
酸ナトリウム溶液１０ｍｅを加え、攪拌しつつ炭酸ガス
を吹き込み、ＰＨ８以下となるまで中和して粒子表面に
ケイ酸ゾルを沈着させ、水洗、乾燥を行なつて酸化アル
ミニウムとケイ酸の２層の被膜を有するα−Ｆｅ２ｑを
得た。このα−Ｆｅ２Ｏ３を電気炉中で１ｔ／分の水素
気流中、５００℃にて２時間環元してアルミニウムち・
よびケイ素を含有する金属鉄粉末を得た。実施例 ２ 実施例１における加熱脱水温度を５００℃とし、加熱環
元温度を４００℃とし、他の条件を全て実施例１と同一
にしてアルミニウム訃よびケイ素を含有する金属鉄粉末
を得た。This was heated in an electric furnace at 300℃ for 2 hours to obtain α-Fe2O3 having an aluminum oxide coating. Next, do this for 800m! ．． redispersed in water of 1N-NaOH
Add 50me of aqueous solution and 10me of sodium orthosilicate solution with a concentration of 1m01e/t, blow carbon dioxide gas while stirring, neutralize until the pH becomes 8 or less, deposit silicate sol on the particle surface, wash with water, and dry. α-Fe2q having a two-layer coating of aluminum oxide and silicic acid was obtained. This α-Fe2O3 was subjected to ring reduction in an electric furnace at 500°C for 2 hours in a hydrogen flow of 1 t/min to form aluminum.
A metallic iron powder containing silicon and silicon was obtained. Example 2 The heating dehydration temperature in Example 1 was 500° C., the heating ring temperature was 400° C., and all other conditions were the same as in Example 1 to obtain a metallic iron powder containing aluminum particles and silicon.

実施例 ３ ８００ｍｅの水中に９ｇのα−Ｆｅ２へ粉末（平均長径
０．５μ、軸比２０／１）を分散した懸濁液中に、１Ｎ
−ＮａＯＨ水溶液１００？および０．０１ｍ０１ｅ／ｔ
濃度の硫酸アルミニウム水溶液１０−ｄを添加し、攪拌
しつつ炭酸ガスを吹き込み、ＰＨ６〜８となるまで中和
し、水洗、乾燥の後、電気炉中で２５０℃にて２時間の
加熱処理を行ない、含水酸化アルミニウムの被膜を有す
るα−Ｆｅ２Ｏ３を得た。Example 3 In a suspension of 9 g of α-Fe2 powder (average major axis 0.5 μ, axial ratio 20/1) dispersed in 800 me water, 1N
-NaOH aqueous solution 100? and 0.01m01e/t
Add a concentrated aluminum sulfate aqueous solution 10-d, and neutralize by blowing in carbon dioxide gas while stirring until the pH becomes 6 to 8. After washing with water and drying, heat treatment was performed at 250°C for 2 hours in an electric furnace. As a result, α-Fe2O3 having a coating of hydrous aluminum oxide was obtained.

これを８００Ｔｎ１の水中に再び分散し、１Ｎ−ＮａＯ
Ｈ水溶液５０ｒ１１ｅおよび１ｍ０１ｅ／ｔ濃度のオル
トケイ酸ナトリウム水溶液１０ｒ１１１を添加し、攪拌
しつつ炭酸ガスを吹き込んでＰＨ８以下となるまで中和
して粒子表面にケイ酸ゾルを沈着させ、含水酸化アルミ
ニウムとケイ酸の２層の被膜を有するα−Ｆｅ２Ｏ３を
得た。このα−Ｆｅ２Ｏ３を電気炉中で１ｔ／分の水素
気流中、５０『Ｃにて２時間環元し、アルミニウムおよ
びケイ素を含有する金属鉄粉末を得た。比較例 １ 実施例１の方法とは逆に、加熱脱水の前にケイ酸成分の
被着処理を行ない、加熱脱水後にアルミニウム成分の被
着処理を行ない、使用した化合物の種類と量ならびに脱
水および環元の条件は全て実施例１と同一にして、アル
ミニウムおよびケイ素を含有する金属鉄粉末を得た。This was dispersed again in 800Tn1 water and 1N-NaO
Add H aqueous solution 50r11e and sodium orthosilicate aqueous solution 10r111 with a concentration of 1 m01e/t, and neutralize by blowing carbon dioxide gas while stirring until the pH becomes 8 or less to deposit silicic acid sol on the particle surface. α-Fe2O3 with a two-layer coating of acid was obtained. This α-Fe2O3 was subjected to ring reduction in an electric furnace in a hydrogen flow of 1 t/min at 50°C for 2 hours to obtain a metallic iron powder containing aluminum and silicon. Comparative Example 1 Contrary to the method of Example 1, the silicic acid component was coated before heat dehydration, and the aluminum component was coated after heat dehydration, and the type and amount of the compound used and the dehydration and All the ring element conditions were the same as in Example 1 to obtain a metal iron powder containing aluminum and silicon.

比較例 ２ 実施例１と同じα−ＦｅＯＯＨ粉末の同量を８００ｄの
水中に分散し、液中に１Ｎ−ＮａＯＨ水溶液１００ｍｅ
１０．０１ｍ０１ｅ／ｔ濃度の硫酸アルミニウム水溶液
１０Ｗ１ｅおよび１ｍ０１ｅ／ｔ濃度のオルトケイ酸ナ
トリウム水溶液１０ｒｎｅを添加し、攪拌しつつ炭酸ガ
スをＰＨ８以下となるまで吹き込み、水洗、乾燥し、水
酸化アルミニウムとケイ酸との混成被膜を有するα−Ｆ
ｅＯＯＨを得、実施例１の条件下で加熱脱水し、これを
実施例１と同一条件で加熱環元してアルミニウムおよび
ケイ素を含有する金属鉄粉末を得た。Comparative Example 2 The same amount of α-FeOOH powder as in Example 1 was dispersed in 800 d of water, and 100 me of 1N-NaOH aqueous solution was added to the liquid.
Add 10W1e of an aqueous solution of aluminum sulfate with a concentration of 10.01m01e/t and 10rne of an aqueous solution of sodium orthosilicate with a concentration of 1m01e/t, blow in carbon dioxide gas while stirring until the pH becomes 8 or less, wash with water, dry, and prepare aluminum hydroxide and silicic acid. α-F having a hybrid film with
eOOH was obtained, heated and dehydrated under the conditions of Example 1, and heated and cyclized under the same conditions as in Example 1 to obtain metallic iron powder containing aluminum and silicon.

以上の実施例および比較例にて得られた金属鉄粉末につ
いて、保磁力（Ｈｃ）、飽和磁化（σｓ）｝よび角型比
を測定した。The coercive force (Hc), saturation magnetization (σs)} and squareness ratio of the metallic iron powders obtained in the above Examples and Comparative Examples were measured.

Claims (1)

【特許請求の範囲】 １ オキシ水酸化鉄または酸化鉄を主体とする粉末の粒
子表面にアルミニウム化合物を被着させ、１５０℃以上
の温度下で加熱処理を行ない、得られた粉末の表面にケ
イ素化合物を被着させ、これを気相中で加熱環元して金
属鉄を主体とする粉末とすることを特徴とする金属磁性
粉末の製造方法。 ２ オキシ水酸化鉄を主体とする粉末粒子を原料とし、
アルミニウム化合物の被着後の加熱処理時に脱水して酸
化鉄とする特許請求の範囲第１項記載の金属磁性粉末の
製造方法。 ３ ケイ素化合物の被着を、水溶性ケイ酸塩のアルカリ
水溶液中に粉末を分散し、液を中和して粉末の粒子表面
にケイ酸ゾルを被着させることによつて行なう特許請求
の範囲第１項または第２項記載の金属磁性粉末の製造方
法。[Scope of Claims] 1. An aluminum compound is deposited on the particle surface of a powder mainly composed of iron oxyhydroxide or iron oxide, and a heat treatment is performed at a temperature of 150°C or higher, and silicon is added to the surface of the obtained powder. 1. A method for producing metal magnetic powder, which comprises depositing a compound and heating and ring-forming the compound in a gas phase to obtain a powder mainly composed of metal iron. 2. Using powder particles mainly composed of iron oxyhydroxide as a raw material,
The method for producing metal magnetic powder according to claim 1, wherein the metal magnetic powder is dehydrated to form iron oxide during heat treatment after the aluminum compound is deposited. 3 Claims in which the silicon compound is deposited by dispersing the powder in an alkaline aqueous solution of a water-soluble silicate, neutralizing the liquid, and depositing a silicate sol on the surface of the powder particles. A method for producing metal magnetic powder according to item 1 or 2.