Synthesis and Application of High-coercive Magnetic Powders in Rare Earth Intermetallic Compound Systems

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Rare earth intermetallic compounds, Sm_2Fe_<17> (C,N) _x and Nd (Fe, M) _<12> (C,N) _x, were prepared by conventional melting method and were finely and uniformly ground up to a particle size below 3 mum by ball-milling in a hexane solution containing a surface active agent. Furthermore, the surface of Sm_2Fe_<17>N_x powders was coated and stabilized by the zinc metal produced from Zn (C_2H_5) _2 according to photochemical vapor deposition process. The resulting Zn/Sm_2Fe_<17>N_x powders showed high coercivity and remanence values to provide a big maximum energy product around 320 kJm^<-3>. It was demonstrated that the epoxy resin-bonded magnets produced from the Zn/Sm_2Fe_<17>N_x composite powders possessed high-performance permanent magnetic characteristics : (BH) max = -176kJm^<-3> and good resistivity for oxidation. Also, these magnets showed the less irreversible flux loss in magnetization even than the Sm_2 (Fe, Co) _<17>N_x ones, of which the stability was much improved by Co addition,