JP2005076045A5

JP2005076045A5 -

Info

Publication number: JP2005076045A5
Application number: JP2003304477A
Authority: JP
Filing date: 2003-08-28
Publication date: 2006-10-12
Anticipated expiration: 2023-08-28

Description

本発明者等は微粉末を大気中に放置したところ、微粉末に窒素が多く存在すると窒素量が減少するとともに、酸素量が増加しやすいこと、換言すれば微粉末の窒素量を制御することによりその後の大気との接触による酸素量の増加を抑制できることを本発明者等は確認した。具体的には、窒素量が２５０ｐｐｍ以下の場合に酸素量の増加を抑制できることを知見した。微粉末中に窒素はＲＮの形態で存在すると解され、大気に接触することにより式（１）の反応あるいは式（１）の反応に伴う微粉末の表面状態変化や発熱により酸化が進むと考えられる。
ＲＮ＋３Ｈ_２Ｏ→Ｒ（ＯＨ）_３＋ＮＨ_３…（１）
微粉末の窒素量を２５０ｐｐｍ以下に制御するための手法はいくつか考えられる。例えば、微粉砕に気流粉砕機を使用する場合、その雰囲気を純窒素ではなく５００〜４５００ｐｐｍの濃度で酸素を混入すること、より好ましくは２０００〜３５００ｐｐｍの濃度で酸素を混入することが有効である。 When the present inventors left the fine powder in the atmosphere, the amount of nitrogen decreases and the amount of oxygen tends to increase if there is a lot of nitrogen in the fine powder, in other words, the amount of nitrogen in the fine powder is controlled. Thus, the present inventors have confirmed that an increase in the amount of oxygen due to subsequent contact with the atmosphere can be suppressed. Specifically, it has been found that an increase in the amount of oxygen can be suppressed when the amount of nitrogen is 250 ppm or less. It is understood that nitrogen is present in the form of RN in the fine powder, and it is thought that oxidation proceeds by contact with the atmosphere due to the reaction of formula (1) or the change in surface condition of the fine powder accompanying the reaction of formula (1) and heat generation. It is done.
RN + 3H ₂ O → R (OH) ₃ + NH ₃ (1)
Several methods for controlling the nitrogen content of the fine powder to 250 ppm or less are conceivable. For example, when using an airflow pulverizer for fine pulverization, it is effective to mix oxygen at a concentration of 500 to 4500 ppm, more preferably 2000 to 3500 ppm, instead of pure nitrogen. .

本発明は以上の知見に基づくものであり、Ｒ−Ｔ−Ｂ（ただし、ＲはＹを含む希土類元素の１種又は２種以上、ＴはＦｅ又はＦｅ及びＣｏを必須とする１種又は２種以上の遷移金属元素）系永久磁石の製造用合金粉末であって、窒素量が１２０〜２５０ｐｐｍ、酸素量が４０００〜５５００ｐｐｍである永久磁石用合金粉末により前記課題を解決する。
また、本発明の永久磁石用合金粉末は、単一の組成を有する合金から構成することができるが、後述する混合法に適用することもできる。混合法は高磁気特性を得るために有効な手法であり、本発明を適用することにより高磁気特性を安定して得ることができるという利点を有することになる。混合法に適用する場合、永久磁石用合金粉末は、Ｒ_２Ｔ_１４Ｂ相を主体とする第１の合金粉末と、第１の合金粉末よりＲを多く含む第２の合金粉末とを少なくとも含む混合物から構成されることになる。 The present invention is based on the above findings, and R-T-B (where R is one or more of rare earth elements including Y, T is one or two essential elements of Fe, Fe and Co) The above-mentioned problems are solved by an alloy powder for producing permanent magnets having at least two kinds of transition magnets, wherein the amount of nitrogen is 120 to 250 ppm and the amount of oxygen is 4000 to 5500 ppm .
Moreover, although the alloy powder for permanent magnets of this invention can be comprised from the alloy which has a single composition, it can also apply to the mixing method mentioned later. The mixing method is an effective technique for obtaining high magnetic characteristics, and has the advantage that high magnetic characteristics can be stably obtained by applying the present invention. When applied to the mixing method, the alloy powder for permanent magnet includes at least a first alloy powder mainly composed of an R ₂ T ₁₄ B phase and a second alloy powder containing more R than the first alloy powder. It will consist of a mixture.

Claims

Production of R-T-B (where R is one or more of rare earth elements including Y and T is one or more transition metal elements in which Fe or Fe and Co are essential) based permanent magnets Alloy powder for
An alloy powder for permanent magnets, wherein the nitrogen content is 120 to 250 ppm and the oxygen content is 4000 to 5500 ppm .

Claim wherein the first alloy powder mainly comprising R 2 _T 14 _B phase, in that they are composed of the first of the second mixture at least containing an alloy powder containing a large amount of R than the alloy powder 1 The alloy powder for permanent magnets described in 1.

R-T-B (where R is one or more rare earth elements including Y and T is one or more transition metal elements in which Fe or Fe and Co are essential) based permanent magnet alloys A coarse pulverization step for coarsely pulverizing the raw materials;
A fine pulverization step in which the coarse powder obtained in the coarse pulverization step is air-flow pulverized in an inert gas atmosphere having an oxygen concentration of 500 to 4500 ppm;
Molding the fine powder obtained in the fine grinding step to obtain a molded body;
And a sintering step of sintering the molded body.

The method for producing a rare earth permanent magnet according to claim 3 , wherein the airflow pulverization is performed in an inert gas atmosphere having an oxygen concentration of 2000 to 3500 ppm.

Wherein after holding a predetermined time in an inert gas atmosphere the fine powder obtained in the milling step containing a predetermined amount of oxygen, the fine powder according to claim 3 or 4, wherein the handling in the atmosphere A method for producing a rare earth permanent magnet.