Title :
Rare earth magnets resisting eddy currents
Author :
Pan, W. ; Li, W. ; Cui, L.Y. ; Li, X.M. ; Guo, Z.H.
Author_Institution :
Div. of Functional Mater., Central Iron & Steel Res. Inst., Beijing, China
fDate :
9/1/1999 12:00:00 AM
Abstract :
Magnets with high electrical resistance were prepared by electrically isolating Sm2Co17 and Nd2Fe14B powder particles. This is achieved by a polymer mixture consisting of epoxy polyester-insulant (EPI), polyvinylbutyral (PVB), epoxy resin (ER) and silane coupling (SC). The properties of interest for anisotropic Sm2Co17 and isotropic Nd2Fe14B magnets respectively are ρ=1×105 Ω-cm2/m, Br=6.8 kG, iHc=10.0 kOe, (BH)max=9.2 MGOe in 5%EPI, 4%PVB, 2%ER, 1%SC and ρ=9.4×104 Ω-cm2/m, Br=4.5 kG, iHc=9.5 kOe, (BH)max=13 MGOe in 4%EPI, 3%PVB, 2%ER, 1%SC. The insulated magnets exhibit far better magnetic stability than those of sintered and bonded magnets after magnetizing in radio frequency field. The insulated Sm2Co17 magnet has the best performance in resisting eddy current. At 500 kHz frequency, 830 Oe magnetizing-field and in one minute, the irreversible loss of recoil remanence is 1.47% and 22.2% respectively for insulated Sm2Co17 and Nd2Fe14B magnets
Keywords :
boron alloys; cobalt alloys; coercive force; eddy current losses; electrical resistivity; ferromagnetic materials; iron alloys; neodymium alloys; permanent magnets; powder metallurgy; remanence; samarium alloys; 500 kHz; Nd2Fe14B; Sm2Co17; coercivity; eddy current resistance; electrical resistivity; epoxy polyester-insulant; epoxy resin; high electrical resistance; insulated magnets; irreversible loss; magnetic stability; polymer mixture use; polyvinylbutyral; powder particles electrical isolation; rare earth magnets; recoil remanence; silane coupling; Eddy currents; Electric resistance; Insulation; Iron; Magnetic anisotropy; Magnets; Neodymium; Perpendicular magnetic anisotropy; Polymers; Powders;
Journal_Title :
Magnetics, IEEE Transactions on
