JPH11121218A - Ferrite permanent magnet and manufacture thereof - Google Patents
Ferrite permanent magnet and manufacture thereofInfo
- Publication number
- JPH11121218A JPH11121218A JP9282248A JP28224897A JPH11121218A JP H11121218 A JPH11121218 A JP H11121218A JP 9282248 A JP9282248 A JP 9282248A JP 28224897 A JP28224897 A JP 28224897A JP H11121218 A JPH11121218 A JP H11121218A
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- Prior art keywords
- permanent magnet
- ferrite
- sintering
- sintered body
- ferrite permanent
- Prior art date
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は，高特性なフェライ
ト永久磁石及びその製造方法に関し，特に，高特性なス
トロンチウムフェライト焼結体又はバリウムフェライト
フェライト焼結体からなるフェライト永久磁石及びその
製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-performance ferrite permanent magnet and a method of manufacturing the same, and more particularly to a high-performance ferrite permanent magnet made of a strontium ferrite sintered body or a barium ferrite sintered body and a method of manufacturing the same. .
【０００２】[0002]
【従来の技術】永久磁石材料は，自動車部品，コンピュ
ータ周辺機器，スピーカ，家庭用電化製品に至るまで幅
広く，かつ大量に使用される電気・電子部品である。永
久磁石材料の中で，ストロンチウムフェライトやバリウ
ムフェライト焼結磁石は，コストパフォーマンスの高さ
という利点を有するので，幅広く用いられている。ま
た，使用される機器の小型化や高性能化のため，磁石材
料自体の磁気特性の向上が求められている。2. Description of the Related Art Permanent magnet materials are electric and electronic components that are widely used in large quantities, such as automobile parts, computer peripherals, speakers, and household appliances. Among the permanent magnet materials, strontium ferrite and barium ferrite sintered magnets are widely used because of their high cost performance. In addition, to reduce the size and performance of the equipment used, there is a demand for improved magnetic properties of the magnet material itself.
【０００３】フェライト永久磁石の高性能化のために
は，残留磁束密度（Ｂｒ）と保磁力（Ｈｃ）の２つの特
性を大きくすることが重要である。残留磁束密度を向上
させるためには，高い焼結密度が必要である。これに対
し，保磁力を大きくするためには，焼結体の結晶粒径が
微細であることが必要である。In order to improve the performance of a ferrite permanent magnet, it is important to increase two characteristics, that is, residual magnetic flux density (Br) and coercive force (Hc). In order to improve the residual magnetic flux density, a high sintering density is required. On the other hand, in order to increase the coercive force, the crystal grain size of the sintered body needs to be fine.
【０００４】一般的な粉末冶金法においては，高い焼結
密度を得るには，焼結反応を進めることが必要である
が，このことは焼結体の結晶粒径の粗大化を招き，必然
的に保磁力は低下する。したがって，残留磁束密度大と
保磁力大とは，相反する関係を有している。In a general powder metallurgy method, it is necessary to promote a sintering reaction in order to obtain a high sintering density. However, this leads to an increase in the crystal grain size of the sintered body, which is inevitable. The coercive force is reduced. Therefore, the large residual magnetic flux density and the large coercive force have an opposite relationship.
【０００５】このような欠点を解消するために，粉末に
微量の金属酸化物を加えることが，通常行われている。
用いられる金属酸化物としては，ＳｉＯ2 ，ＣａＯ，Ｎ
ａ2Ｏ，Ｃｒ2 Ｏ3 ，などが用いられている。これら
は，焼結過程において結晶粒成長を抑えて，焼結密度を
上げる働きがあり，残留磁束密度大と保磁力大を両立さ
せるためには，必要不可欠の添加物である。[0005] In order to solve such disadvantages, it is customary to add a small amount of metal oxide to the powder.
As the metal oxide used, SiO 2 , CaO, N
a 2 O, Cr 2 O 3 , etc. are used. These have the function of suppressing crystal grain growth in the sintering process and increasing the sintering density, and are indispensable additives for achieving both high residual magnetic flux density and high coercive force.
【０００６】ところで，近年の電子部品の小型化，高性
能化の動きで，モーターの高回転化も求められている。[0006] In recent years, with the trend of miniaturization and high performance of electronic components, a higher rotation speed of a motor is also required.
【０００７】[0007]
【発明が解決しようとする課題】しかし，モータの高回
転化に伴い印可磁界の反転も高速，高周波になり，必然
的に磁石に流れる渦電流による発熱が大きくなる。この
ような磁石の発熱は，エネルギー効率の低下や信頼性の
問題と結びつき問題となる。However, as the rotation speed of the motor increases, the reversal of the applied magnetic field also becomes faster and higher in frequency, and the heat generated by the eddy current flowing through the magnet inevitably increases. Such heat generation of the magnet is associated with a reduction in energy efficiency and reliability.
【０００８】そこで，磁石に流れる渦電流を低下させて
発熱を押さえるためには，磁石材料の比抵抗を大きくす
ることが必要である。しかし，上記の微量添加物をフェ
ライト永久磁石材料に添加すると比抵抗が低下してしま
い，モーターの高回転化が困難になると言う問題があっ
た。Therefore, in order to suppress the heat generation by reducing the eddy current flowing through the magnet, it is necessary to increase the specific resistance of the magnet material. However, there is a problem that when the above-mentioned small amount of additive is added to the ferrite permanent magnet material, the specific resistance decreases, and it becomes difficult to increase the rotation speed of the motor.
【０００９】そこで，本発明の技術的課題は，上記微量
添加物を用いないで，残留磁束密度大と保磁力大を両立
させた高特性のフェライト永久磁石及びその製造方法と
を提供することにある。SUMMARY OF THE INVENTION It is an object of the present invention to provide a ferrite permanent magnet having high characteristics, which achieves both high residual magnetic flux density and high coercive force, without using the above-mentioned trace additive, and a method of manufacturing the same. is there.
【００１０】[0010]
【課題を解決するための手段】本発明によれば，ストロ
ンチウムフェライト焼結体又はバリウムフェライト焼結
体からなるフェライト永久磁石において，ＳｉＯ2 ，Ｃ
ａＯ，Ｎａ2 Ｏ，及びＣｒ2 Ｏ3 の中で少なくとも１種
の酸化物の含有量が０．１ｗｔ％以下であることを特徴
とするフェライト永久磁石が得られる。According to the present invention SUMMARY OF], in a ferrite permanent magnet consisting of strontium ferrite sintered bodies or barium ferrite sintered body, SiO 2, C
A ferrite permanent magnet characterized in that the content of at least one oxide among aO, Na 2 O, and Cr 2 O 3 is 0.1 wt% or less.
【００１１】また，本発明によれば，ストロンチウムフ
ェライト又はバリウムフェライトからなる永久磁石の製
造方法において，焼結用粉末を放電プラズマ焼結し，焼
結体を得ることを特徴とするフェライト永久磁石の製造
方法が得られる。Further, according to the present invention, there is provided a method for producing a permanent magnet comprising strontium ferrite or barium ferrite, characterized in that a sintering powder is subjected to discharge plasma sintering to obtain a sintered body. A manufacturing method is obtained.
【００１２】さらに，本発明によれば，前記フェライト
永久磁石の製造方法において，前記焼結体は，Ｓｉ
Ｏ2 ，ＣａＯ，Ｎａ2 Ｏ，及びＣｒ2 Ｏ3 の内の少なく
とも１種の酸化物の含有量が０．１ｗｔ％以下であるこ
とを特徴とするフェライト永久磁石の製造方法が得られ
る。ここで，本発明において，フェライト永久磁石焼結
体のＳｉＯ2 ，ＣａＯ，Ｎａ2 Ｏ，Ｃｒ2 Ｏ3 の中で少
なくとも１種の酸化物の含有量を，０．１ｗｔ％以下と
限定した理由は，放電プラズマ焼結法によれば，これら
の微量成分の添加なしの場合においても，残留磁束密度
大と保磁力大とを両立させ，同時に高い比祇抗を得るこ
とが可能となり，本発明の有効性が大きいためである。Further, according to the present invention, in the method for manufacturing a ferrite permanent magnet, the sintered body may be made of Si.
A method for producing a ferrite permanent magnet, characterized in that the content of at least one oxide of O 2 , CaO, Na 2 O, and Cr 2 O 3 is 0.1 wt% or less. Here, in the present invention, the reason why the content of at least one oxide in SiO 2 , CaO, Na 2 O, and Cr 2 O 3 of the sintered ferrite permanent magnet is limited to 0.1 wt% or less. According to the spark plasma sintering method, even when these trace components are not added, it is possible to achieve both high residual magnetic flux density and large coercive force, and at the same time, to obtain a high specific resistance. This is because the effectiveness is large.
【００１３】[0013]
【発明の実施の形態】以下，本発明の実施の形態につい
て説明する。Embodiments of the present invention will be described below.
【００１４】まず，本発明の実施の形態によるフェライ
ト永久磁石の製造方法の概要を述べる。First, an outline of a method for manufacturing a ferrite permanent magnet according to an embodiment of the present invention will be described.
【００１５】ＳｒＣＯ3 又はＢａＣＯ3 ，Ｆｅ2 Ｏ3 等
のストロンチウムフェライト又はバリウムフェライトの
原料粉末を混合，乾燥し，仮焼する。仮焼した粉末を微
粉砕し，焼結用粉末を得る。次に，必要に応じてプレス
を行い成形体を得る。この成形体もしくは粉末をカーボ
ン製モールドに挿入し，放電プラズマ焼結して，焼結体
を得る。[0015] SrCO 3 or BaCO 3, Fe 2 O 3 mixed raw material powder of strontium ferrite or barium ferrite or the like, dried, calcined. The calcined powder is finely pulverized to obtain a powder for sintering. Next, pressing is performed as necessary to obtain a molded body. This compact or powder is inserted into a carbon mold and subjected to spark plasma sintering to obtain a sintered compact.
【００１６】ここで，放電プラズマ焼結は，大森 守，
平井敏雄：「放電プラズマ焼結」，ニューセラミックス
＆エレクトロニク・セラミクス，（１９９４）７月号，
第２３〜２５頁，（株）ティー・アイ・シィー，平成６
年発行に述べられているように，低温，短時間で高密度
の焼結体が得られる方法として注目されている。これ
は，カーボン等の導電性を備えたモールドに粉末を充填
して加圧焼結を行うもので，この際に，モールドに直
接，オンオフ直流パルス電流を流すことでモールドと粉
体を発熱体として粉末を昇温する。また，加熱の際に流
れる電流は，粉体粒子間の空隙にプラズマを発生させ，
そのプラズマは，粉体表面を活性化させて拡散を促進す
る。この放電プラズマ焼結方法によれば，短時間で焼結
が終了するために，得られた焼結体の結晶粒径は微細な
ものとなり，同時に高い焼結密度が得られる。Here, spark plasma sintering is performed by Mamoru Omori,
Toshio Hirai: "Spark Plasma Sintering", New Ceramics & Electronic Ceramics, July 1994,
23-25 pages, T.I.C., Heisei 6
As described in the annual publication, it is attracting attention as a method for obtaining a high-density sintered body at low temperature and in a short time. In this method, powder is charged into a conductive mold such as carbon, and pressure sintering is performed. In this case, an on / off DC pulse current is directly passed through the mold to cause the mold and the powder to be heated. And heat the powder. In addition, the current flowing during heating generates plasma in the gap between the powder particles,
The plasma activates the powder surface to promote diffusion. According to this spark plasma sintering method, since sintering is completed in a short time, the crystal grain size of the obtained sintered body becomes fine, and at the same time, a high sintering density can be obtained.
【００１７】本発明の実施の形態においては，上記した
ように，放電プラズマ焼結をフェライト永久磁石用原料
粉末に適用することで，微量添加物なしで，残留磁束密
度大と保持力大を両立させた高特性のフェライト焼結磁
石を得ることが可能となる。In the embodiment of the present invention, as described above, by applying the discharge plasma sintering to the raw material powder for the ferrite permanent magnet, it is possible to achieve both high residual magnetic flux density and high coercive force without adding a trace amount of additives. It is possible to obtain a ferrite sintered magnet having high characteristics.
【００１８】また，本発明の実施の形態において，フェ
ライト永久磁石焼結体のＳｉＯ2 ，ＣａＯ，Ｎａ2 Ｏ，
Ｃｒ2 Ｏ3 の内で少なくとも１種の酸化物の含有量を，
０．１ｗｔ％以下としている。放電プラズマ焼結法によ
れば，これらの微量成分の添加なしの場合においても，
残留磁束密度大と保磁力大とを両立させ，同時に高い比
祇抗を得ることが可能となり，本発明の有効性が大きい
ためである。In the embodiment of the present invention, the ferrite permanent magnet sintered body is made of SiO 2 , CaO, Na 2 O,
The content of at least one oxide in Cr 2 O 3
0.1 wt% or less. According to the spark plasma sintering method, even when these trace components are not added,
This is because a high residual magnetic flux density and a high coercive force can be achieved at the same time, and a high resistance can be obtained at the same time, so that the effectiveness of the present invention is great.
【００１９】なお，上記の微量成分を添加した粉末によ
る放電プラズマ焼結においても，従来法の普通焼結によ
る方法よりも，大きな残留磁束密度と保持力が得られ，
本発明は有効である。In the case of spark plasma sintering using the above-mentioned powder to which trace components are added, a larger residual magnetic flux density and coercive force can be obtained than in the conventional method using ordinary sintering.
The present invention is effective.
【００２０】また，通常のフェライト永久磁石において
は，大きな残留磁束密度を得るためには，異方性焼結磁
石と呼ばれる結晶の磁化容易軸を揃えて，残留磁束密度
と最大エネルギー積を向上させることが通常行われてい
る。これは，焼結に供する磁石原料を単磁区粒子径以下
あるいはそれに近い粒径まで粉砕して粉末を得て，その
成形体を磁場中で粉末の磁化容易軸を揃えた方向に配向
させた状態で成形し，これを焼結するものである。In a normal ferrite permanent magnet, in order to obtain a large residual magnetic flux density, the axes of easy magnetization of crystals called anisotropic sintered magnets are aligned to improve the residual magnetic flux density and the maximum energy product. That is usually done. This is a state in which the magnet raw material to be sintered is crushed to a particle size smaller than or close to a single magnetic domain particle size to obtain a powder, and the formed body is oriented in a magnetic field in a direction in which the axes of easy magnetization of the powder are aligned. And sintering it.
【００２１】本発明の実施の形態においても，この成形
方法によって得られた成形体を放電ブラズマ焼結の際の
モールドに挿入し，焼結を行うことにより，大きな残留
磁束密度が得られる。Also in the embodiment of the present invention, a large residual magnetic flux density can be obtained by inserting the molded body obtained by this molding method into a mold during discharge plasma sintering and performing sintering.
【００２２】次に，本発明の実施の形態によるフェライ
ト永久磁石の具体例について説明する。Next, a specific example of the ferrite permanent magnet according to the embodiment of the present invention will be described.
【００２３】（本発明例１）高純度のＳｒＣＯ3 とＦｅ
2 Ｏ3 をＳｒＯ及びＦｅ2 Ｏ3 で，夫々換算してモル比
で１：５．６になるように秤量し，純水を加え，ボール
ミルで混合，乾燥し，１２００℃で仮焼した粉末をボー
ルミルを用いて気体透過法による平均粒径０．８μｍま
で，粉砕し，ストロンチウムフェライト焼結用粉末を作
製した。得られたスラリーをφ３０×１５ｍｍの形状に
湿式磁場プレスを行い成形体を作製した。(Example 1 of the present invention) High purity SrCO 3 and Fe
2 O 3 was weighed with SrO and Fe 2 O 3 in terms of a molar ratio of 1: 5.6, respectively, added with pure water, mixed with a ball mill, dried, and calcined at 1200 ° C. Was pulverized to an average particle diameter of 0.8 μm by a gas permeation method using a ball mill to prepare a powder for strontium ferrite sintering. The obtained slurry was subjected to wet magnetic field pressing into a shape of φ30 × 15 mm to produce a molded body.
【００２４】得られた成形体を，カーボン製モールドに
挿入し，放電プラズマ焼結を行った。焼結条件として
は，大気中で５００ｋｇｆ／ｃｍ2 で圧縮しながら，５
０℃／ｍｉｎの昇温速度で加熱し，９００℃で１０分間
保持した。得られた焼結体の残留磁束密度Ｂｒと固有保
持力ｉＨｃをＢ−Ｈトレーサーで評価した。また，アル
キメデス法により焼結密度を，２端子法により，直流比
抵抗を夫々測定した。得られた結果を下記表１に示す。The obtained compact was inserted into a carbon mold and subjected to spark plasma sintering. The sintering conditions were as follows, while compressing in air at 500 kgf / cm 2.
It was heated at a rate of 0 ° C./min and kept at 900 ° C. for 10 minutes. The residual magnetic flux density Br and the intrinsic coercive force iHc of the obtained sintered body were evaluated with a BH tracer. The sintered density was measured by the Archimedes method, and the DC specific resistance was measured by the two-terminal method. The results obtained are shown in Table 1 below.
【００２５】（比較例１）本発明例１と同様に作製した
成形体を，普通焼結を行つた。焼結条件としては，大気
中で２００℃／ｈｒの昇温速度で加熱し，１２５０℃で
２時間保持した。得られた焼結体を本発明例１と同様に
評価した。得られた結果を下記表１に示す。(Comparative Example 1) A compact produced in the same manner as in Example 1 of the present invention was subjected to ordinary sintering. As sintering conditions, heating was performed in the atmosphere at a rate of 200 ° C./hr, and the temperature was maintained at 1250 ° C. for 2 hours. The obtained sintered body was evaluated in the same manner as in Inventive Example 1. The results obtained are shown in Table 1 below.
【００２６】下記表１より，本発明の本発明例１では，
従来法による比較例１とほぼ同じ焼桔密度と残留磁束密
度でありながら，大きな固有保持力ｉＨｃが得られ，本
発明の優位性が確認された。From Table 1 below, in Example 1 of the present invention,
While having substantially the same printing density and residual magnetic flux density as Comparative Example 1 by the conventional method, a large specific coercive force iHc was obtained, and the superiority of the present invention was confirmed.
【００２７】（本発明例２）本発明例１と同様に秤量，
混合，仮焼した。得られた仮焼粉末を３分割し，それぞ
れにＮａ2 ＣＯ3 をＮａ2 Ｏ換算で０．５ｗｔ％，Ｓｉ
Ｏ2 を０．４ｗｔ％と，ＣａＣＯ3 をＣａＯ換算で０．
７ｗｔ％，Ｃｒ2 Ｏ3 を０．５ｗｔ％加え，本発明例１
と同様に粉砕，成形し，成形体を得た。得られた成形体
をカーボン製モールドに挿入し，放電プラズマ焼結を行
った。焼結条件としては，大気中で５００ｋｇｆ／ｃｍ
2 で圧縮しながら，５０℃／ｍｉｎの昇温速度で加熱し
８８０℃で１０分間保持した。得られた焼結体を本発明
例１と同様に評価した。得られた結果を下記表１に示
す。(Example 2 of the present invention)
Mixed and calcined. The obtained calcined powder was divided into three parts, each containing 0.5% by weight of Na 2 CO 3 in terms of Na 2 O,
O 2 is 0.4 wt%, and CaCO 3 is 0.1% in terms of CaO.
Example 1 of the present invention by adding 7 wt% and 0.5 wt% of Cr 2 O 3
In the same manner as described above, pulverization and molding were performed to obtain a molded body. The obtained compact was inserted into a carbon mold and subjected to spark plasma sintering. The sintering conditions are 500 kgf / cm in air.
While compressing at 2 , the sample was heated at a heating rate of 50 ° C./min and kept at 880 ° C. for 10 minutes. The obtained sintered body was evaluated in the same manner as in Inventive Example 1. The results obtained are shown in Table 1 below.
【００２８】（比較例２）本発明例２と同様に作製した
成形体を，普通焼結を行った。焼結条件としては，大気
中で２００℃／ｈｒの昇温速度で加熱し１２００℃で２
時間保持した。得られた焼結体を本発明例１と同様に評
価した。得られた結果を下記表１に示す。下記表１よ
り，本発明の本発明例２では，従来法の比較例２とほぼ
同じ焼結密度と残留磁束密度でありながら，大きな固有
保持力ｉＨｃが得られ，本発明の優位性が確認された。
また，本発明例１と本発明例２の比較より，本発明では
大きい比抵抗が得られる微量添加物無しの場合において
も大きい固有保持力ｉＨｃが得られることがわかる。(Comparative Example 2) A molded body produced in the same manner as in Example 2 of the present invention was subjected to ordinary sintering. The sintering conditions were as follows: heating at 200 ° C / hr in the atmosphere at 1200 ° C;
Hold for hours. The obtained sintered body was evaluated in the same manner as in Inventive Example 1. The results obtained are shown in Table 1 below. As shown in Table 1 below, in Example 2 of the present invention, a large specific coercive force iHc was obtained while having substantially the same sintering density and residual magnetic flux density as Comparative Example 2 of the conventional method, confirming the superiority of the present invention. Was done.
In addition, from the comparison between Inventive Example 1 and Inventive Example 2, it can be seen that in the present invention, a large intrinsic coercive force iHc can be obtained even in the absence of a small amount of additive that can provide a large specific resistance.
【００２９】[0029]
【表１】 [Table 1]
【００３０】（本発明例３）高純度のＢａＣＯ3 とＦｅ
2 Ｏ3 をＢａＯ，Ｆｅ2 Ｏ3 で換算してモル比で１：
５．５になるように秤量し，純水を加え，ボールミルで
混合，乾燥し，１２５０℃で仮焼した。仮焼した粉末を
ボールミルを用いて，気体透過法による平均粒径０．８
μｍまで粉砕し，バリウムフェライト焼結用粉末を作製
した。得られたスラリーをφ３０×１５ｍｍの形状に湿
式磁場プレスを行い，成形体を作製した。得られた成形
体をカーボン製モールドに挿入し，放電プラズマ焼結を
行った。(Example 3 of the present invention) High purity BaCO 3 and Fe
2 O 3 is converted to BaO, Fe 2 O 3 and the molar ratio is 1:
It was weighed to 5.5, pure water was added, mixed with a ball mill, dried and calcined at 1250 ° C. The calcined powder was subjected to gas permeation using a ball mill to obtain an average particle size of 0.8.
The powder was pulverized to μm to prepare a barium ferrite sintering powder. The obtained slurry was subjected to wet magnetic field pressing into a shape of φ30 × 15 mm to produce a molded body. The obtained compact was inserted into a carbon mold and subjected to spark plasma sintering.
【００３１】焼結条件としては，大気中で５００ｋｇｆ
／ｃｍ2 で圧縮しながら，５０℃／ｍｉｎの昇温速度で
加熱し，９４０℃で１０分間保持した。得られた焼結体
を本発明例１と同様に評価した。その結果を下記表２に
示す。The sintering conditions are as follows: 500 kgf in air.
The sample was heated at a temperature rising rate of 50 ° C./min while being compressed at a pressure of / cm 2 , and kept at 940 ° C. for 10 minutes. The obtained sintered body was evaluated in the same manner as in Inventive Example 1. The results are shown in Table 2 below.
【００３２】（比較例３）本発明例３と同様に作製した
成形体を，普通焼結を行った。焼結条件としては，大気
中で２００℃／ｈｒの昇温速度で加熱し１２８０℃で２
時間保持した。Comparative Example 3 A molded body produced in the same manner as in Example 3 of the present invention was subjected to ordinary sintering. The sintering conditions were as follows: heating at 200 ° C / hr in air, heating at 1280 ° C for 2 hours;
Hold for hours.
【００３３】得られた焼結体を本発明例１と同様に評価
した。得られた結果を下記表２に示す。表２より，本発
明の本発明例３では，従来法の比較例３とほぼ同じ焼結
密度と残留磁束密度でありながら，大きな固有保磁力ｉ
Ｈｃが得られ，本発明の優位性が確認された。The obtained sintered body was evaluated in the same manner as in Inventive Example 1. The results obtained are shown in Table 2 below. From Table 2, it can be seen that in Example 3 of the present invention, although the sintering density and the residual magnetic flux density were almost the same as Comparative Example 3 of the conventional method, the large intrinsic coercivity i
Hc was obtained, confirming the superiority of the present invention.
【００３４】（本発明例４）本発明例３と同様に秤量，
混合，仮焼した。得られた仮焼粉末を３分割し，それぞ
れにＮａ2 ＣＯ3 をＮａ2 Ｏ換算で，０．５ｗｔ％，Ｓ
ｉＯ2 を０．４％と，ＣａＣＯ3 をＣａＯ換算で０．７
ｗｔ％，Ｃｒ2 Ｏ3 を０．５ｗｔ％加え，本発明例１と
同様に粉砕し，成形し，成形体を得た。得られた成形体
を，カーボン製モールドに挿入し，放電プラズマ焼結を
行った。(Example 4 of the present invention)
Mixed and calcined. The resulting calcined powder was divided into three parts, and Na 2 CO 3 was converted to Na 2 O in an amount of 0.5 wt%, S
iO 2 is 0.4%, and CaCO 3 is 0.7% in terms of CaO.
wt% and 0.5 wt% of Cr 2 O 3 were added, and pulverized and molded in the same manner as in Example 1 of the present invention to obtain a molded body. The obtained compact was inserted into a carbon mold and subjected to spark plasma sintering.
【００３５】焼結条件としては，大気中で５００ｋｇｆ
／ｃｍ2 で圧縮しながら，５０℃／ｍｉｎの昇温速度で
加熱し９２０℃で１０分間保持した。得られた焼結体を
本発明例１と同様に評価した。その結果を下記表２に示
す。The sintering conditions are 500 kgf in air.
While compressing at / cm 2 , the sample was heated at a heating rate of 50 ° C./min and kept at 920 ° C. for 10 minutes. The obtained sintered body was evaluated in the same manner as in Inventive Example 1. The results are shown in Table 2 below.
【００３６】（比較例４）本発明例４と同様に作製した
成形体を，普通焼結を行った。焼結条件としては，大気
中で２００℃／ｈｒの昇温速度で加熱し，１２５０℃で
２時間保持した。得られた焼結体を本発明例１と同様に
評価した。得られた結果を下記表２に示す。(Comparative Example 4) A compact produced in the same manner as in Example 4 of the present invention was subjected to ordinary sintering. As the sintering conditions, heating was performed in the atmosphere at a rate of 200 ° C./hr, and the temperature was maintained at 1250 ° C. for 2 hours. The obtained sintered body was evaluated in the same manner as in Inventive Example 1. The results obtained are shown in Table 2 below.
【００３７】[0037]
【表２】 [Table 2]
【００３８】上記表２より，本発明の本発明例４では，
従来法の比較例４とぼぼ同じ焼結密度と残留磁束密度で
ありながら，大きな固有保持力ｉＨｃが得られ，本発明
の優位性が確認された。また，本発明例３と本発明例４
の比較より，本発明では，大きい比抵抗が得られる微量
添加物無しの場合においても，大きい固有保持力ｉＨｃ
が得られることがわかる。According to Table 2 above, in Example 4 of the present invention,
Although the sintering density and the residual magnetic flux density were almost the same as those of Comparative Example 4 of the conventional method, a large specific holding force iHc was obtained, and the superiority of the present invention was confirmed. In addition, Example 3 of the present invention and Example 4 of the present invention
According to the present invention, it can be seen that the present invention has a large intrinsic coercive force iHc
Is obtained.
【００３９】[0039]
【発明の効果】以上述べた様に，本発明によれば，放電
プラズマ焼結法を用いることによって，残留磁束密度大
と保磁力大を両立させた高特性のフェライト永久磁石及
びその製造方法とを提供することができ，工業上極めて
有効である。As described above, according to the present invention, by using the discharge plasma sintering method, a ferrite permanent magnet having high characteristics and having both high residual magnetic flux density and high coercive force, and a method for manufacturing the same are provided. Which is industrially extremely effective.
Claims (3)
リウムフェライト焼結体からなるフェライト永久磁石に
おいて，ＳｉＯ2 ，ＣａＯ，Ｎａ2 Ｏ，及びＣｒ2 Ｏ3
の内で少なくとも１種の酸化物の含有量が０．１ｗｔ％
以下であることを特徴とするフェライト永久磁石。1. A ferrite permanent magnet comprising a strontium ferrite sintered body or a barium ferrite sintered body, wherein SiO 2 , CaO, Na 2 O, and Cr 2 O 3 are used.
The content of at least one oxide is 0.1 wt%
A ferrite permanent magnet, characterized in that:
フェライトからなる永久磁石の製造方法において，焼結
用粉末を放電プラズマ焼結し，焼結体を得ることを特徴
とするフェライト永久磁石の製造方法。2. A method for producing a permanent magnet made of strontium ferrite or barium ferrite, wherein a sintering powder is subjected to discharge plasma sintering to obtain a sintered body.
造方法において，前記焼結体は，ＳｉＯ2 ，ＣａＯ，Ｎ
ａ2 Ｏ，及びＣｒ2 Ｏ3 の内の少なくとも１種の酸化物
の含有量が０．１ｗｔ％以下であることを特徴とするフ
ェライト永久磁石の製造方法。3. The method for producing a ferrite permanent magnet according to claim 2, wherein the sintered body is made of SiO 2 , CaO, N
A method for producing a ferrite permanent magnet, wherein the content of at least one oxide of a 2 O and Cr 2 O 3 is 0.1 wt% or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9282248A JPH11121218A (en) | 1997-10-15 | 1997-10-15 | Ferrite permanent magnet and manufacture thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9282248A JPH11121218A (en) | 1997-10-15 | 1997-10-15 | Ferrite permanent magnet and manufacture thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11121218A true JPH11121218A (en) | 1999-04-30 |
Family
ID=17649985
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP9282248A Withdrawn JPH11121218A (en) | 1997-10-15 | 1997-10-15 | Ferrite permanent magnet and manufacture thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11121218A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1153900A2 (en) * | 2000-05-11 | 2001-11-14 | National Institute of Advanced Industrial Science and Technology | Process for producing magnetoplumbite-type ferrite sintered magnet |
| JP2002029829A (en) * | 2000-05-11 | 2002-01-29 | National Institute Of Advanced Industrial & Technology | Method for manufacturing sintered magnetoplumbite type ferrite magnet |
| WO2014017551A1 (en) * | 2012-07-25 | 2014-01-30 | Tdk株式会社 | METHOD FOR PRODUCING Sr FERRITE SINTERED MAGNET, MOTOR AND POWER GENERATOR |
-
1997
- 1997-10-15 JP JP9282248A patent/JPH11121218A/en not_active Withdrawn
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1153900A2 (en) * | 2000-05-11 | 2001-11-14 | National Institute of Advanced Industrial Science and Technology | Process for producing magnetoplumbite-type ferrite sintered magnet |
| JP2002029829A (en) * | 2000-05-11 | 2002-01-29 | National Institute Of Advanced Industrial & Technology | Method for manufacturing sintered magnetoplumbite type ferrite magnet |
| EP1153900A3 (en) * | 2000-05-11 | 2003-08-06 | National Institute of Advanced Industrial Science and Technology | Process for producing magnetoplumbite-type ferrite sintered magnet |
| WO2014017551A1 (en) * | 2012-07-25 | 2014-01-30 | Tdk株式会社 | METHOD FOR PRODUCING Sr FERRITE SINTERED MAGNET, MOTOR AND POWER GENERATOR |
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