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 magnetiz-ing frequency were investigated to improve the properties of bonded magnets.The epoxy resin exhibits low viscos-ity(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 DO A 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 alternat-ing magnetic field,respectively,while the density of bonded magnets decreases with the number of times of al-ternating 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,DO A and density in bonded magnets.Therefore,the DO A 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.
bonded Nd-Fe-B magnetsepoxy resinviscosityalternating magnetic field
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