JPH0516162B2

JPH0516162B2 -

Info

Publication number: JPH0516162B2
Application number: JP58110166A
Authority: JP
Inventors: Tetsuhiko Mizoguchi; Masashi Sahashi; Koichiro Inomata
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1983-06-21
Filing date: 1983-06-21
Publication date: 1993-03-03
Also published as: JPS603105A

Description

【発明の詳細な説明】[Detailed description of the invention]

〔発明の技術分野〕本発明はサマリウム（Sm）−コバルト（Co）
系永久磁石、とりわけSm₂Co₁₇系永久磁石の製造
法に関し、更に詳しくは残留磁速密度（Br）、保
持力（_IHc）、最大エネルギー積（（BH）max）
などの磁気性に優れ、また、耐酸化性にも優れた
永久磁石の製造法に関する。〔発明の技術的背景とその問題点〕従来から、Ｒ−Ｍ系（ＲはSm、Ce、Ｙなどの
希土類元素ＭはCo及びCoとともにCe、Feなどの
金属元素）永久磁石に関しては各種組成のものが
提案されている。これら永久磁石にあつては、最大エネルギー積
（（BH）max）及び残留磁束密度（Br）がモータ
ー等の用途においては特に重要な特性であり、そ
の値は可能な限り大きいことが望ましい。しかし
ながら、これらの値も該磁石の保持力（_IHc）が
ある一定値以上でないと高めることは困難であ
る。したがつて、（BH）max、Brの大きい永久
磁石を得るためには_IHcを大きくすることが必要
となる。ところで、Sm₂（Co、Cu、Fe、Ti）₁₇系の磁石
では、Fe含量を増したり、Cu含量は減らすとBr
を増加させ得ることが知られている。しかし、
Fe含量を増したり、Cu含量を減らすと_IHcが低
下して来るため、単純にFe含量を増しCu含量を
減らすことによつてBrや（BH）maxの向上を図
ることはできない。そのため、従来のSm₂（Co、
Cu、Fe、Ti）₁₇系の磁石は、_IHcをある値以上に維
持しながら、Brを可能な限り大きくすることを
目的としてその組成が決定されてきた。例えば、
特公昭55−15096号公報には、Ｙ及び他の希土類
元素10〜30重量％と、Ti0.2〜７重量％と、Cu5
〜20重量％と、Fe2〜15重量％とを含み、残部が
Coを主成分とする金属粉末を磁界中で成形した
後焼結して成る永久磁石は、耐酸化性及び_IHc、
（BH）maxなどの磁気特性に優れることが開示
されている。また、特開昭52−109191号公報に
は、Sm23〜30重量％と、Ti0.2〜1.5重量％と、
Cu9〜13重量％と、Fe3〜12重量％とを含み、残
部がCoを主成分とする金属粉末を磁界中で成形
した後、焼結して成る永久磁石が開示されてい
る。しかしながら、これらの組成は、Cu含量及び
Fe含量の変動に伴つて起る、残留磁束密度（Br）
と保持力（_IHc）の変化を妥協的に適合させた結
果であるから、必ずしも充分なものとは言えない
ものであつた。ところで、Brを低下させるCu分を減らし、Br
を向上させるFe分を増加させ、同時に_IHcを一定
値以上に保持することができれば、Br及び
（BH）maxの大きい優れた磁気特性を有する永
久磁石を得ることができる。本発明者らは、上記の課題を達成すべく永久磁
石を構成する合金の構成及び熱処理過程に関し鋭
意研究を重ねた結果、該合金の組成をSm（Co、
Cu、Fe、Ti）ｚの式で表した場合、ｚ＜6.9でし
かも焼結後に特定の時効処理を施すと、Fe量を
増しCu量を減らすことによつても従来の知見と
は全く逆に_IHcを増加させ得るとの事実を見出
し、該知見に基づいてBr及び（BH）maxを著し
く高めた永久磁石を開発し、既に特許出願した。本発明者らは、Sm₂Co₁₇系永久磁石の磁気特性
及び耐酸化性をより改善すべく、該永久磁石の組
成及び処理過程に関し更に研究を重ねた結果、あ
る組成の金属粉末を焼結した後、溶体化処理する
ことなく該焼結体を600℃以上700℃未満の温度で
所定時間保持し、５℃／min以下の速度で連続的
に冷却すると得られた永久磁石のBr、（BH）
max、角型性_IHcが著しく増大することの事実を
見出し本発明を完成するに至つた。〔発明の目的〕本発明は、前述した従来の永久磁石の製造法の
欠点を解消したもので、Br（BH）max、_IHcなど
の磁気特性に優れ、また耐酸化性も優れた
Sm₂Co₁₇系永久磁石の製造方法を提供することを
目的とする。〔発明の概要〕即ち、本発明の永久磁石の製造方法、Sm25〜
28重量％と、Ti0.2〜３重量％と、Cu1〜９重量
％と、Fe14〜25重量％と、残部が主としてCoで
ある金属粉末を磁界中で成形し、次いで得られた
成形体を焼結し、直ちに750℃以上850℃未満の温
度範囲において保持した後、毎分５℃以下の速度
で連続的に冷却することを特徴とする。原料の金属粉末において、Smの含量は25〜28
重量％であつて、25重量％未満の場合には_IHcの
増大はなく、また、28重量％を超えると_IHcは減
少すると同時にBrも減少して（BH）maxの増大
がはかれない。Tiは0.2〜３重量％であつて、Ti
が0.2重量％未満の場合には_IHcが顕著には増大せ
ず、３重量％を超えるとBrが減少する。Cuは１
〜９重量％であつて、１重量％未満の場合には_I
Hcの増大がはかれず、９重量％を超えるとBrが
減少すると同時に後述する熱処理効果が小さくな
り、結果として（BH）maxも特に増大すること
がない。Feは14重量％以上、25重量％以下であ
つて、14重量％未満では熱処理効果が小さく、ま
た、25重量％を超えると_IHcが減少し、熱処理効
果も小さく、したがつて（BH）maxが減少す
る。原料の金属粉末の残部は主としてCoである。本発明の永久磁石の製造方法は次のようにして
行なわれる。即ち、まず、上記した配合比の金属
粉末を、所定の押し型に充填した後、磁界中で圧
縮成形して成形体とし、該成形体を、真空、窒
素、希ガス等の不活性雰囲気中で焼結する。焼結
温度は通常1050〜1250℃の温度が適用される。得られた焼結体は、直ちに本発明における第２
の特徴である所定の熱処理が施される。例えば
Sm、Fe、Cu、Co以外の添加成分としてZr、Hf
を用いると、焼結後、溶体化処理が必要となる
が、Tiを用いたときにはその必要がなく、焼結
後直ちに熱処理（時効処理）が施される。但し、
例えば一旦室温まで急冷するなど高温保持を伴わ
ない工程を、焼結と熱処理の間に設けることは特
に制限されない。すなわち、まず、焼結体は上記
したような不活性雰囲気中で、750℃以上850℃未
満の温度で所定時間保持される。処理温度がこの
範囲を外れると、得られら永久磁石の_IHc及び
（BH）maxが著しく減少する。また、このとき、
保持時間は、通常0.1〜30時間で充分である。その後、焼結体を５℃／min以下の速度で連続
的に冷却することにより目的とする永久磁石を得
ることができる。このとき、冷却速度が５℃／minより大きいと
きには、_IHcの増大は充分でない。〔発明の実施例〕以下、実施例により本発明を更に詳細に説明す
る。まず、永久磁石は次のようにして製造した。所定の組成比で各金属元素を配合して、その約
４Kgを真空高周波誘導加熱炉で溶融後冷却し、得
られたインゴツトを粗分粉砕後、ジエツトミルで
粉砕して微粉末とした。この微粉末を所定の押し
型に充填し、20000エルステツドの磁界をかけな
がら2ton／cm²の圧力で圧縮成形した。得られた成
形体にアルゴン雰囲気中で所定温度、所定時間の
焼結処理を施した後、直ちに室温まで一旦冷却
し、ついで再び所定温度で所定時間保持した後、
徐冷処理を施した。以下に％は重量％を表わす。実施例１_I Hc（BH）maxのCu含有量依存性と熱処理の
効果組成：Sm26.5％、Ti1.2％、Fe17.5％、Cu₀〜12
％、Co残部焼結条件：1185℃×１時間熱処理：800℃で１時間保持した後、１℃／min
の速度で連続的に冷却。比較のために、熱処理を行なわない外は、実施
例１と同様にして別の永久磁石の（比較例１）を
製造した。得られた永久磁石のCu含量と、_IHc、（BH）
maxとの関係を第１図に示した。図において、
曲線Ａ：実施例１の_IHc曲線ａ：比較例１の_IHc、
曲線Ｂ：実施例１の（BH）max、曲線ｂ：比較
例１の（BH）maxを表わす。第１図から明らかなように、本発明の製造方法
により製造した永久磁石は、Cu9％以下でも_IHc
が大きく、また、（BH）maxのピークも熱処理
前ににはCu：10〜11％であつたものが、７〜８
％以下のところにシフトし、かつ、（BH）max
の値も可成り増大している。また、比較例２とし
て、焼結に引き続いて1185℃×４時間の溶体化処
理を施し、Cuの含有量を５重量％とした以外は
実施例１と同様の方法で永久磁石を製造したとこ
ろ、Br：11000G、_IHc：7000Oe、（BH）max：
25MGOeとなり、保持力は大きく変わらないも
のの、（BH）maxが大きく劣化することがわか
る。実施例２実施例にかかる試料21〜23と比較試料21〜31を
製造した。各試料の組成、焼結条件を第１表に示
した。熱処理の条件は、次のとおりであつた。表
中、番号で示した熱処理のパターンはそれぞれ以
下のとおりである。１：800℃で１時間＋１℃／minで連続的冷却。２：900℃で１時間＋１℃／minで連続的冷却。３：700℃で10時間＋２℃／minで連続的冷却。４：800℃で２時間＋７℃／minで連続的冷却。 [Technical field of the invention] The present invention relates to samarium (Sm)-cobalt (Co)
Regarding the manufacturing method of permanent magnets, especially Sm ₂ Co ₁₇ permanent magnets, more details include residual magnetic velocity density (Br), coercive force ( _I Hc), maximum energy product ((BH) max)
This invention relates to a method for producing permanent magnets that have excellent magnetic properties and oxidation resistance. [Technical background of the invention and its problems] Conventionally, various compositions have been used for permanent magnets of the RM system (R is a rare earth element such as Sm, Ce, and Y, and M is a metallic element such as Ce and Fe as well as Co). have been proposed. For these permanent magnets, the maximum energy product ((BH)max) and residual magnetic flux density (Br) are particularly important characteristics in applications such as motors, and it is desirable that these values be as large as possible. However, it is difficult to increase these values unless the coercive force ( _I Hc) of the magnet exceeds a certain value. Therefore, in order to obtain a permanent magnet with large (BH)max and Br, it is necessary to increase _I Hc. By the way, in Sm ₂ (Co, Cu, Fe, Ti) ₁₇ -based magnets, if the Fe content is increased or the Cu content is decreased, the Br
It is known that it can increase but,
Since _I Hc decreases when the Fe content is increased or the Cu content is decreased, it is not possible to improve Br or (BH)max by simply increasing the Fe content and decreasing the Cu content. Therefore, the conventional Sm ₂ (Co,
The composition of _17- based magnets (Cu, Fe, Ti) has been determined with the aim of increasing Br as much as possible while maintaining _I Hc above a certain value. for example,
Japanese Patent Publication No. 55-15096 discloses that 10 to 30% by weight of Y and other rare earth elements, 0.2 to 7% by weight of Ti, and Cu5
~20% by weight and ~15% by weight Fe2, with the balance being
Permanent magnets made by molding Co-based metal powder in a magnetic field and then sintering it have excellent oxidation resistance, _I Hc,
It has been disclosed that it has excellent magnetic properties such as (BH)max. In addition, JP-A No. 52-109191 discloses that Sm23 to 30% by weight, Ti 0.2 to 1.5% by weight,
A permanent magnet is disclosed in which a metal powder containing 9 to 13% by weight of Cu and 3 to 12% by weight of Fe, with the remainder being mainly Co, is molded in a magnetic field and then sintered. However, these compositions are limited by Cu content and
Residual magnetic flux density (Br) caused by variation of Fe content
This result was obtained by compromisingly adapting the changes in the holding force ( _I Hc) and the change in the holding force (I Hc), so it could not necessarily be said to be sufficient. By the way, by reducing the Cu content that lowers Br,
If it is possible to increase the Fe content, which improves the magnetic properties, and at the same time maintain _I Hc above a certain value, it is possible to obtain a permanent magnet having excellent magnetic properties with large Br and (BH)max. In order to achieve the above-mentioned problem, the present inventors have conducted intensive research on the composition and heat treatment process of the alloy that constitutes the permanent magnet, and as a result, the composition of the alloy has been determined to be Sm(Co,
(Cu, Fe, Ti) When expressed by the formula z, if z < 6.9 and a specific aging treatment is performed after sintering, increasing the amount of Fe and decreasing the amount of Cu results in a completely opposite result to conventional knowledge. Based on _this finding, we developed a permanent magnet with significantly increased Br and (BH)max, and have already applied for a patent. In order to further improve the magnetic properties and oxidation resistance of Sm ₂ Co ₁₇ -based permanent magnets, the inventors conducted further research on the composition and processing process of permanent magnets, and as a result, they succeeded in sintering metal powder with a certain composition. After that, the sintered body is held at a temperature of 600°C or more and less than 700°C for a predetermined time without solution treatment, and is continuously cooled at a rate of 5°C/min or less. BH)
max and squareness _I Hc were found to be significantly increased, leading to the completion of the present invention. [Object of the Invention] The present invention eliminates the drawbacks of the conventional permanent magnet manufacturing method described above, and has excellent magnetic properties such as Br (BH) max and _I Hc, as well as excellent oxidation resistance.
The purpose of the present invention is to provide a method for manufacturing Sm ₂ Co ₁₇ -based permanent magnets. [Summary of the invention] That is, the method for manufacturing a permanent magnet of the present invention, Sm25~
A metal powder containing 28% by weight of Ti, 0.2 to 3% by weight of Ti, 1 to 9% of Cu, 14 to 25% of Fe, and the remainder mainly Co is molded in a magnetic field, and then the obtained molded body is It is characterized in that it is sintered, immediately maintained at a temperature range of 750°C or higher and lower than 850°C, and then continuously cooled at a rate of 5°C or less per minute. In the raw metal powder, the Sm content is 25 to 28
If it is less than 25% by weight, _I Hc will not increase, and if it exceeds 28% by weight, _I Hc will decrease and Br will also decrease at the same time, making it impossible to increase (BH)max. . Ti is 0.2 to 3% by weight, and Ti
When it is less than 0.2% by weight, _I Hc does not increase significantly, and when it exceeds 3% by weight, Br decreases. Cu is 1
~9% by weight, but less than 1% by weight, _I
If Hc is not increased and exceeds 9% by weight, Br decreases and at the same time the heat treatment effect described below becomes small, and as a result, (BH)max does not particularly increase. Fe is 14% by weight or more and 25% by weight or less, and if it is less than 14% by weight, the heat treatment effect is small, and if it exceeds 25% by weight, _I Hc decreases and the heat treatment effect is also small, so (BH) max decreases. The remainder of the raw metal powder is mainly Co. The method for manufacturing a permanent magnet of the present invention is carried out as follows. That is, first, metal powder having the above-mentioned mixing ratio is filled into a predetermined pressing mold, and then compression molded in a magnetic field to form a compact, and the compact is placed in an inert atmosphere such as vacuum, nitrogen, or rare gas. Sinter with The sintering temperature is usually 1050 to 1250°C. The obtained sintered body is immediately used in the second method of the present invention.
A predetermined heat treatment, which is a characteristic feature of for example
Zr, Hf as additional components other than Sm, Fe, Cu, and Co
When Ti is used, solution treatment is required after sintering, but when Ti is used, this is not necessary and heat treatment (aging treatment) is performed immediately after sintering. however,
For example, there is no particular restriction on providing a step that does not involve holding at a high temperature, such as once rapidly cooling to room temperature, between sintering and heat treatment. That is, first, the sintered body is held in an inert atmosphere as described above at a temperature of 750° C. or more and less than 850° C. for a predetermined time. If the processing temperature is outside this range, _{the I} Hc and (BH)max of the resulting permanent magnet will decrease significantly. Also, at this time,
A holding time of 0.1 to 30 hours is usually sufficient. Thereafter, the desired permanent magnet can be obtained by continuously cooling the sintered body at a rate of 5° C./min or less. At this time, when the cooling rate is higher than 5° C./min, the increase in _I Hc is not sufficient. [Examples of the Invention] The present invention will be explained in more detail below with reference to Examples. First, a permanent magnet was manufactured as follows. Each metal element was blended in a predetermined composition ratio, approximately 4 kg of the ingot was melted in a vacuum high-frequency induction heating furnace, and then cooled. The obtained ingot was coarsely ground and then ground in a jet mill to form a fine powder. This fine powder was filled into a predetermined press mold and compression molded at a pressure of 2 tons/cm ² while applying a magnetic field of 20,000 oersteds. After the obtained molded body was subjected to a sintering treatment at a predetermined temperature and a predetermined time in an argon atmosphere, it was immediately cooled to room temperature, and then held again at a predetermined temperature for a predetermined time.
A slow cooling process was performed. In the following, % represents weight %. Example 1 Cu content dependence of _I Hc(BH)max and effect of heat treatment Composition: Sm26.5%, Ti1.2%, Fe17.5%, Cu ₀ to 12
%, Co remaining Sintering conditions: 1185℃ x 1 hour Heat treatment: 1℃/min after holding at 800℃ for 1 hour
Continuous cooling at a rate of . For comparison, another permanent magnet (Comparative Example 1) was manufactured in the same manner as in Example 1 except that no heat treatment was performed. The Cu content of the obtained permanent magnet and _I Hc, (BH)
The relationship with max is shown in Figure 1. In the figure,
Curve A: _I Hc curve a of Example 1: _I Hc of Comparative Example 1,
Curve B: (BH)max of Example 1, Curve b: (BH)max of Comparative Example 1. As is clear from Fig. 1, the permanent magnet manufactured by the manufacturing method of the present invention has _{an I} Hc value of 9% Cu or less.
In addition, the peak of (BH)max was 7-8% Cu, which was 10-11% before heat treatment.
% or less, and (BH)max
The value of has also increased considerably. In addition, as Comparative Example 2, a permanent magnet was manufactured in the same manner as in Example 1, except that sintering was followed by solution treatment at 1185°C for 4 hours, and the Cu content was 5% by weight. , Br: 11000G, _I Hc: 7000Oe, (BH)max:
It becomes 25MGOe, and although the holding force does not change much, it can be seen that (BH)max deteriorates significantly. Example 2 Samples 21 to 23 according to the example and comparative samples 21 to 31 were manufactured. The composition and sintering conditions of each sample are shown in Table 1. The conditions for the heat treatment were as follows. The heat treatment patterns indicated by numbers in the table are as follows. 1: 800℃ for 1 hour + continuous cooling at 1℃/min. 2: 1 hour at 900℃ + continuous cooling at 1℃/min. 3: 700℃ for 10 hours + continuous cooling at 2℃/min. 4: 2 hours at 800℃ + continuous cooling at 7℃/min.

【表】【table】

〔発明の効果〕〔Effect of the invention〕

以上説明したように、本発明の製造方法により
製造した永久磁石はその磁気特性が大幅に向上す
る。これは、Sm₂CO₁₇系永久磁石にあつては、
R₂CO₁₇相及びRCo₅相から成る２相分離型のセル
構造を有する組織になるが、これらの組織形態及
び両相の磁気特性の改善がなされたためであると
考えられる。なお、本発明の製造方法により製造した永久磁
石は、Tiが含有されていることにより、その耐
酸化性も向上する。 As explained above, the permanent magnet manufactured by the manufacturing method of the present invention has significantly improved magnetic properties. This is true for Sm ₂ CO ₁₇ permanent magnets.
The structure has a two-phase separated cell structure consisting of ₁₇ R ₂ CO phases and ₅ RCo phases, which is thought to be due to improvements in the structure morphology and the magnetic properties of both phases. Note that the permanent magnet manufactured by the manufacturing method of the present invention also has improved oxidation resistance due to the inclusion of Ti.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は_IHc、（BH）maxのCu含有依存性と
熱処理の効果を表わす特性図、第２図は実施例３
で示した組成の永久磁石の（BH）maxと冷却速
度との関係図。 Figure 1 is a characteristic diagram showing the dependence of _I Hc and (BH)max on Cu content and the effect of heat treatment, and Figure 2 is Example 3.
Relationship diagram between (BH)max and cooling rate of a permanent magnet with the composition shown in .

Claims

【特許請求の範囲】[Claims]

１サマリウム25〜28重量％と、チタン0.2〜３
重量％と、銅１〜９重量％と、鉄14〜25重量％
と、残部が主としてコバルトである金属粉末を磁
界中で成形し、次いで得られた成形体を焼結し、
直ちに750℃以上850℃未満の温度範囲において保
持した後、毎分５℃以下の速度で連続的に冷却す
ることを特徴とする永久磁石の製造方法。1 25-28% samarium and 0.2-3% titanium
% by weight, 1-9% by weight of copper, and 14-25% by weight of iron.
and a metal powder, the remainder of which is mainly cobalt, is molded in a magnetic field, and the resulting molded body is then sintered,
A method for producing a permanent magnet, which comprises immediately holding the magnet in a temperature range of 750°C or more and less than 850°C, and then continuously cooling it at a rate of 5°C or less per minute.