Effects of Epoxy Resin Viscosity and Magnetizing Frequencyon Properties of Anisotropic Bonded Nd-Fe-B Magnets

Anisotropic bonded Nd-Fe-B magnets were prepared by two step compression process，called a cold preforming step and next a warm alignment and densifification step，and the epoxy resin viscosity and magnetizing frequency were investigated to improve the properties of bonded magnets. The epoxy resin exhibits low viscosity（about 150 Pa·s）at 140 ℃ for 200 s. As the preformed body presents best preheating effect at 140 ℃ for 1 min，the Nd-Fe-B bonded magnet gets the maximum（BH）max，DOA and density（127 kJ·m-3，0.55，5.91 g·cm-3）.When heated at 140 ℃ for 1 and 6 min，the maximum（BH）max and DOA of bonded magnets（133 kJ·cm-3，0.59 for 1 min and 108 kJ·cm-3，0.52 for 6 min）are obtained by applying twice and 4 times alternating magnetic field，respectively，while the density of bonded magnets decreases with the number of times of alternating magnetic field. The increase of epoxy resin viscosity，extension of heating time，reduces the lubricity and fluidity of epoxy resin，which results in the decrease of（BH）max，DOA and density in bonded magnets. Therefore，the DOA and（BH）max can be improved by increasing the number of times y of alternating magnetic field to rotate particles in the direction of magnetic field. © 2024 Editorial Office of Chinese Rare Earths. All rights reserved.