Preparation of high performance Sm-Fe-N bulk magnets with low oxygen content
The 2nd Symposium for World Leading Research Centers-Materials Science and Spintronics-, 2019, 2. 16
Masashi Matsuura, Yuki Nishijima, Nobuki Tezuka, Satoshi Sugimoto (Tohoku University), Tetsuya Shoji, Noritsugu Sakuma (Toyota Notor Corp.)
Abstract
Sm2Fe17N3 has a high saturation magnetization, a large anisotropy field, and a high Curie temperature, however,this compound cannot be sintered because of decomposition above about 600・C. To obtain high performance Sm-Fe-N bulk magnet, Zn-bonded Sm-Fe-N magnets is expected.
To obtain high performance Zn-bonded Sm-Fe-N bulk magnets, it is required to achieve following conditions;decreasing oxygen content in magnets, decreasing Zn content maintaining with well dispersibility, and increasing relative density. In this study, we adopted two processes; (i) preparing fine and low oxygen Zn powder, (ii) preparing low-oxygen Sm-Fe-N powder and applying the Arc-Plasma-Deposition (APD) for Zn deposition on the Sm-Fe-N powder (iii) Spark plasma sintering (SPS) for increasing relative density of bulk magnets.
At first, we prepared fine and low oxygen Zn power (d50=0.23・m,oxygen content=680 ppm) by the Hydrogen-Plasma-Metal-Reaction (HPMR) method. The oxygen content in the Zn-bonded Sm-Fe-N magnets prepared using the Zn powder also decreased comparing with Zn-bonded Sm-Fe-N magnets prepared using commercial Zn powder. The low oxygen Zn- bonded Sm-Fe-N magnets prepared using HPMR-Zn powder showed high coercivity of 2.66 MA/m (15 wt% Zn) and 2.41 MA/m (10 wt% Zn)[1].
Second, low-oxygen Sm-Fe-N powder was prepared by ball milling and nitriding. Then, well dispersed and lowoxygen Zn was deposited on the Sm-Fe-N powders by the APD. The APDed Sm-Fe-N/Zn composite powder was sintered by Spark plasma sintering (SPS), and 3.3 wt% Zn-bonded Sm-Fe-N magnet showed high (BH)max of 153 kJ/m3 with relatively high coercivity of 1.14 MA/m. We also prepared Zn-free Sm-Fe-N bulk magnets by SPS under low oxygen atmosphere, and we successfully obtained Zn-free Sm-Fe-N magnet that showing high (BH)max of 179 kJ/m3 [2]
[1] Masashi Matsuura, Tomoki Shiraiwa, Nobuki Tezuka, Satoshi Sugimoto, Tetsuya Shoji, Noritsugu Sakuma, Kazuaki Haga, J. Magn. Magn. Mater., 452 (2018) 243-248.
[2] Masashi Matsuura, Yuki Nishijima, Nobuki Tezuka, Satoshi Sugimoto, Tetsuya Shoji, Noritsugu Sakuma, J. Magn. Magn. Mater., 467 (2018) 64-68.
To obtain high performance Zn-bonded Sm-Fe-N bulk magnets, it is required to achieve following conditions;decreasing oxygen content in magnets, decreasing Zn content maintaining with well dispersibility, and increasing relative density. In this study, we adopted two processes; (i) preparing fine and low oxygen Zn powder, (ii) preparing low-oxygen Sm-Fe-N powder and applying the Arc-Plasma-Deposition (APD) for Zn deposition on the Sm-Fe-N powder (iii) Spark plasma sintering (SPS) for increasing relative density of bulk magnets.
At first, we prepared fine and low oxygen Zn power (d50=0.23・m,oxygen content=680 ppm) by the Hydrogen-Plasma-Metal-Reaction (HPMR) method. The oxygen content in the Zn-bonded Sm-Fe-N magnets prepared using the Zn powder also decreased comparing with Zn-bonded Sm-Fe-N magnets prepared using commercial Zn powder. The low oxygen Zn- bonded Sm-Fe-N magnets prepared using HPMR-Zn powder showed high coercivity of 2.66 MA/m (15 wt% Zn) and 2.41 MA/m (10 wt% Zn)[1].
Second, low-oxygen Sm-Fe-N powder was prepared by ball milling and nitriding. Then, well dispersed and lowoxygen Zn was deposited on the Sm-Fe-N powders by the APD. The APDed Sm-Fe-N/Zn composite powder was sintered by Spark plasma sintering (SPS), and 3.3 wt% Zn-bonded Sm-Fe-N magnet showed high (BH)max of 153 kJ/m3 with relatively high coercivity of 1.14 MA/m. We also prepared Zn-free Sm-Fe-N bulk magnets by SPS under low oxygen atmosphere, and we successfully obtained Zn-free Sm-Fe-N magnet that showing high (BH)max of 179 kJ/m3 [2]
[1] Masashi Matsuura, Tomoki Shiraiwa, Nobuki Tezuka, Satoshi Sugimoto, Tetsuya Shoji, Noritsugu Sakuma, Kazuaki Haga, J. Magn. Magn. Mater., 452 (2018) 243-248.
[2] Masashi Matsuura, Yuki Nishijima, Nobuki Tezuka, Satoshi Sugimoto, Tetsuya Shoji, Noritsugu Sakuma, J. Magn. Magn. Mater., 467 (2018) 64-68.
その他特記事項
謝辞「This study is partially supported by the Elemental Strategy Initiative Center for
Magnetic Materials (ESICMM) under the outsourcing project of MEXT, JAPAN.」
Magnetic Materials (ESICMM) under the outsourcing project of MEXT, JAPAN.」
