Ternary synergistic design of lightweight and high-strength composite magnets for rotor applications

To address the challenges of traditional bonded magnets, such as high density, low mechanical strength and imbalanced magnetic mechanical properties, a multiphase collaborative design strategy was proposed in this study. The coupling mechanism of magnetic mechanical properties of ferrite magnetic powder (SrFe 12 O 19 ) and neodymium iron boron magnetic powder (Nd 2 Fe 14 B) was systematically investigated under three matrix systems: epoxy resin (EP), phenolic resin (PF), and chlorinated polypropylene (CPP). The results showed that, by regulating the binder gradient (3∼10 wt%) and the content of shortened carbon fiber (SCF) (3∼15 wt%), the Nd 2 Fe 14 B/EP system achieved optimal magnetic properties at a binder content of 4 wt%, exhibiting the remanence Br of 7.213 kG and the maximum energy product ( BH) max of 11.212 MGOe. After further introducing 9 wt% carbon fiber, the density of Nd 2 Fe 14 B/EP composite magnet decreased to 5.462 g/cm 3 (a reduction of 8.621%), the compressive strength increased to 165.841 MPa (an increase of 69.251%), and the flexural strength reached up to 114.782 MPa (an increase of 58.262%). The high viscosity and fluidity of EP contributed to its superior comprehensive performance, PF’s high-temperature resistance makes it suitable for more demanding environments, while CPP's flexibility helps alleviate interface stress concentration. This study elucidates the ternary synergy of "magnetic particle type-binder-fiber reinforcement," providing a theoretical and technological basis for the development of lightweight and high-strength magnets in aerospace and new energy vehicles.