High-performance epoxy-resin-bonded magnets produced from the Sm2Fe17Nx powders coated by copper and zinc metals

Fine powders Of Sm2Fe17Nx coated with copper metal reduced from CuCl2 and/o r zinc metal subsequently derived by photodecomposition of diethylzinc [Zn( C2H5)(2)] were prepared, and their magnetic properties were characterized i n addition to those of epoxy-resin-bonded magnets produced from the coated powders (Cu/Sm2Fe17Nx, Zn/Sm2Fe17Nx and Zn/Cu/Sm2Fe17Nx). The remanence (B- r) and maximum energy product [(BH)(max)] of double metal-coated Zn/Cu/Sm2F e17Nx powders were maintained at higher levels than those of single Zn meta l-coated Sm2Fe17N. ones (Zn/Sm2Fe17Nx) even after heat treatment at 673 K s ince the oxidation resistance and thermal stability were effectively improv ed by formation of the thick and uniform protection layer on the surface of Sm2Fe17Nx particles. Moreover, the epoxy-resin-bonded magnets produced fro m the Zn/Cu/Sm2Fe17Nx powders possessed good corrosion resistance in air at 393 K which it resulted in the smaller thermal irreversible flux loss than that of uncoated and single Zn metal-coated Sm2Fe17Nx powders in the tempe rature range of above 393 K.