Rare earth magnets resisting eddy currents

Magnets with high electrical resistance were prepared by electrically isola ting Sm2Co17 and Nd2Fe14B powder particles. It is done by a polymer mixture consisting of epoxy polyester-insulant (EPI), polyvinylbutyral (PVB), epox y resin (ER) and silane coupling (SC). The properties of interest for aniso tropic Sm2Co17 and isotropic Nd2Fe14B magnets are rho =1 x 10(5) Omega -cm( 2)/m, Br=6.8kGs, iHc=10.0kOe, (BH)max =9.2MGOe in 5%EPI, 4%PVB, 2%ER,1%SC a nd rho =9.4 x 10(4) Omega -cm(2)/m, Br=4.5kG, iHc=9.5kOe, (BH)max =4.3MGOe in 4%EPI, 3%PVB, 2%ER, 1%SC. The insulated magnets exhibit far better magne tic stability than those of sintered and bonded magnets after magnetizing i n radio frequency. The insulated Sm2Co17 magnet has the best performance in resisting eddy current. In 500kHz frequency, 830Oe magnetizing-field and i n one minute, the irreversible loss of recoil remanence is 1.47% and 22.2% respectively for insulated Sm2Co17 and Nd2Fe14B magnets.