Journal of Magnetics

The Korean Magnetics Society (한국자기학회)
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High Coercive Nd-Fe-B Sintered Magnets for High Temperature Application

  • Kim, D.H. (Jahwa Electronics Co.) ;
  • Kim, A.S. (Jahwa Electronics Co.) ;
  • Lim, T.H. (Department of Hybrid Engineering, Sunmoon University) ;
  • Jang, T.S. (Department of Hybrid Engineering, Sunmoon University)
  • Published : 2009.03.31
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Abstract

Various sintered magnets containing $28{\sim}31\;wt%$ Nd and $0{\sim}7\;wt%$ Dy were evaluated for coercivity and irreversible flux loss as a preliminary study to develop highly-coercive, high-temperature magnets that can be applied for driving motors in a hybrid vehicle. The sintered magnets were prepared in sequence of strip casting, HD treatment, jet milling, magnetic field pressing, sintering and post-annealing. Increasing Dy content and adjusting post-annealing temperature monotonically increased coercivity of magnets from about 14 kOe to 30 kOe. A magnet containing 28 wt% Nd and 7 wt% Dy exhibits a $(BH)_{max}$+$_i{H_c}$ value of almost 64. This is very close to what the automobile industry considers as the minimum value (65) for a hybrid vehicle system. Moreover, irreversible flux loss of the magnet was about 3% at $200^{\circ}C$, which is well less than the allowable limit (5%) to a driving motor in hybrid vehicles.

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  1. Reduction in Flux Loss of an Nd-Fe-B Bonded Ring Magnet for an SPM Motor vol.50, pp.11, 2014, https://doi.org/10.1109/TMAG.2014.2324274