Heat resistant plastic magnets

Abstract

We developed new Sm-Fe-N plastic magnets that are heat resistant up to 473 K (200/spl deg/C). In order to achieve high heat resistance, we performed Zn treatment using a resin that was judged to be optimal. The Zn treatment of the Sm-Fe-N powder was carried out by Zn powder mixing using poly butylene naphthalate (PBN) resin. The Zn treatment raised the powder coercivity from 1040 to 1600 kA/m. In addition, since the melting point of PBN resin is 516 K (243/spl deg/C), a heat resistant plastic magnet was realized while maintaining the process temperature at 573 K (300/spl deg/C) or less.