Journal of the Korean Magnetics Society (한국자기학회지)

The Korean Magnetics Society (한국자기학회)
권호 표지
DOI QR코드

DOI QR Code

Current Status and Research Trend of Rare-earth Permanent Magnet

희토류 영구자석의 현황 및 개발 동향

  • 남궁석 (LG전자, 소재부품연구소) ;
  • 조상근 (LG전자, 소재부품연구소) ;
  • 김진배 (LG전자, 소재부품연구소)
  • Received : 2012.11.08
  • Accepted : 2012.12.03
  • Published : 2012.12.31
Download PDF
⟨ Previous Next ⟩

Abstract

High performance permanent magnets have become the subject of considerable attention because of the potential applications in the traction motors of hybrid and electric vehicles and wind generators. Nd-Fe-B magnets have attracted considerable interest due to a large maximum energy product. However, Nd-Fe-B magnet cannot be used in high temperature (${\sim}200^{\circ}C$) applications due to the thermal degradation of coercivity. Therefore, the development of high coercivity Nd-Fe-B permanent magnet is a challenging issue. In case of high coercivity Nd-Fe-B permanent magnet, an increment in the intrinsic coercivity can be easily achieved by substituting Nd atoms with Dy or Tb atoms. However, these heavy rare-earth elements are known to cause a decrease in remanence due to the antiferromagnetic coupling between Dy and Fe atoms. In addition, Dy is relatively expensive and being limited in quantity. Hence, a new technology that can increase the coercivity of Nd-Fe-B sintered magnet using only a small amount, or even, no amount of heavy rare-earth elements is being investigated. This article describes the research trend in reducing the heavy rare-earth elements in Nd-Fe-B magnets.

고특성 영구자석은 하이브리드 및 전기자동차의 구동모터와 풍력발전에 적용되면서 크게 주목을 받고 있다. Nd-Fe-B 영구자석은 가장 높은 최대자기에너지적을 가지고 있지만 고온(${\sim}200^{\circ}C$)의 구동환경에서는 보자력이 급격히 감소하기 때문에 사용할 수 없는 단점을 가지고 있다. 그러므로 큰 보자력을 가지는 Nd-Fe-B 영구자석에 대한 개발이 요구되고 있다. Nd-Fe-B 소결자석에서 보자력을 증가시키기 위해서는 Nd를 Dy 또는 Tb으로 치환하면 쉽게 증가시킬 수 있다. 그러나 이들 원소는 Fe와 반강자성 결합을 하여 잔류자속밀도를 낮추고, 적은 매장량과 한정된 지역에 편재되어 있어 수요급증에 따른 자원수급 및 가격 급등의 문제를 가지고 있다. 따라서, Dy 및 Tb과 같은 중희토류를 사용하지 않거나 최소한의 양을 사용하여 보자력을 증가시키고자 하는 연구가 많이 진행되고 있다. 본 논문에서는 이러한 중희토류 원소의 저감 및 대체에 대한 연구들을 소개하고자 한다.

Keywords

References

  1. O. Gutfleisch, M. A. Willard, E. Bruck, C. H. Chen, S. G. Sankar, and J. P. Liu, Adv. Mater. 23, 821 (2011). https://doi.org/10.1002/adma.201002180
  2. J. M. D. Coey, IEEE Trans. Magn. 47, 4671 (2011). https://doi.org/10.1109/TMAG.2011.2166975
  3. K. J. Strnat, IEEE Trans. Magn. 6, 182 (1970). https://doi.org/10.1109/TMAG.1970.1066743
  4. R. K. Mishra, G. Thomas, T. Yoneyama, A. Fukuno, and T. Ojima, J. Appl. Phys. 52, 2517 (1981). https://doi.org/10.1063/1.328987
  5. J. J. Croat, J. F. Herbst, R. W. Lee, and F. E. Pinkerton, Appl. Phys. Lett. 44, 148 (1984). https://doi.org/10.1063/1.94584
  6. M. Sagawa, S. Fujimura, N. Togawa, H. Yamamoto, and Y. Matsuura, J. Appl. Phys. 55, 2083 (1984). https://doi.org/10.1063/1.333572
  7. D. Harimoto and Y. Matsuura, Hitachi Met. Tech. Rev. 23, 69 (2007).
  8. I. R. Harris, C. Noble, and T. Bailey, J. Less-Common Met. 106, L1 (1985). https://doi.org/10.1016/0022-5088(85)90380-7
  9. K. Oesterreicher and H. Oesterreicher, Phys. Status Solidi A 85, K61 (1984).
  10. R. S. Mottram, A. J. Williams, and I. R. harris, J. Magn. Magn. Mater. 234, 80 (2001). https://doi.org/10.1016/S0304-8853(01)00067-1
  11. F. Vial, F. Joly, E. Nevalainen, M. Sagawa, K. Hiraga, and K.T. Park, J. Magn. Magn. Mater. 242, 1329 (2002). https://doi.org/10.1016/S0304-8853(01)00967-2
  12. H. Nakamura, K. Hirota, M. Shimao, T. Minowa, and M. Honshima, IEEE Trans. Magn. 41, 3844 (2005). https://doi.org/10.1109/TMAG.2005.854874
  13. K. Hirota, H. Nakamura, M. Shimao, T. Minowa, and M. Honshima, IEEE Trans. Magn. 42, 2909 (2006). https://doi.org/10.1109/TMAG.2006.879906
  14. http://www.shinetsu-rare-earth-magnet.jp/e/rd/grain.html.
  15. http://www.hitachi-metals.co.jp/e/eh2009/p04.html.
  16. N. Mitsutoshi, Hitachi Met. Tech. Rev. 8, 28 (2012).
  17. TDK, Technical Journal 4 (2011).
  18. S. Sugimoto, J. Phys. D: Appl. Phys. 44, 064001 (2011). https://doi.org/10.1088/0022-3727/44/6/064001
  19. M. Sagawa, Proc. 22th Int. Workshop on Rare Earth Permanent Magnet and Their Applications, 3 (2012).
  20. T. Takeshita and R. Nakayama, Proc. 11th Int. Workshop on Rare Earth Permanent Magnet and their Applications, 49 (1990).
  21. T. Takeshita and K. Morimoto, J. Appl. Phys. 79, 5040 (1996). https://doi.org/10.1063/1.361567
  22. O. Gutfleisch, K. Khlopkov, A. Teresiak, K. H. Müller, G. Drazic, C. Mishima, and Y. Honkura, IEEE Trans. Magn. 39, 2926 (2003). https://doi.org/10.1109/TMAG.2003.815749
  23. Y. Honkura, C. Mishima, N. Hamada, G. Drazic, and O. Gutfleisch, J. Magn. Magn. Mater. 290, 1282 (2005). https://doi.org/10.1016/j.jmmm.2004.11.423
  24. C. Mishima, K. Noguchi, M. Yamazaki, H. Mitarai, and Y. Honkura, Proc. 21st Int. Workshop on Rare-Earth Permanent Magnets and their Applications, 253 (2010).
  25. H. Sepehri-Amin, T. Ohkubo, T. Nishiuchi, S. Hirosawa, and K. Hono, Scripta Mater. 63, 1124 (2010). https://doi.org/10.1016/j.scriptamat.2010.08.021
  26. K. Hono, T. Ohkubo, and H. Sepehri-Amin, J. Jpn. Inst. Met. 76, 2 (2012). https://doi.org/10.2320/jinstmet.76.2
  27. C. Mishima, K. Noguchi, M. Yamazaki, and Y. Honkura, Proc. 21st Int. Workshop on Rare Earth Permanent Magnet and Their Applications, 253 (2010).
  28. K. Suresh, T. Ohkubo, Y. K. Takahashi, K. Oh-ishi, R. Gopalan, K. Hono, T. Nishiuchi, N. Nozawa, and S. Hirosawa, J. Magn. Magn. Mater. 321, 3681 (2009). https://doi.org/10.1016/j.jmmm.2009.07.010
  29. R. W. Lee, Appl. Phys. Lett. 46, 790 (1985). https://doi.org/10.1063/1.95884
  30. K. D. Drust and H. Kronmuller, J. Magn. Magn. Mater. 68, 63 (1987). https://doi.org/10.1016/0304-8853(87)90097-7
  31. T. Yabumi, 2008 BM News (The Japan Association of Bonded Magnetic Materials) 40, 42 (2008).