Facile preparation of bonded NdFeB/SmFeN hybrid magnets with flexibility, anisotropy and high energy density

The application of rubber isotropic bonded magnets is limited due to low energy density, although it remains unbeatable in terms of price and production rate. In this paper, high-filled, flexible, and anisotropic NdFeB/ SmFeN bonded magnets were prepared using mixtures of fine SmFeN powders and coarse NdFeB powders by calendering molding. The optical microscope images show that adding fine SmFeN powder benefits processability, leading to higher loading while retaining flexibility. The magnetic property and microstructure of the magnets display the anisotropic magnetic property of NdFeB/SmFeN bonded magnets derived from the arrangement of the platelet-shaped NdFeB particles induced by mechanical stress during the calendaring process. To further optimize the magnetic properties of NdFeB/SmFeN bonded magnets, the NdFeB was sieved and then mixed with SmFeN to mold into sheets. Finally, the effect of NdFeB particle size on the magnetic and mechanical properties of NdFeB/SmFeN bonded magnets was investigated. The results showed that when the particle size of the NdFeB particle was 75-100 & mu;m, the magnetic properties of magnets reached the maximum value (Br = 7.77 KG, Hcj = 14.70 KOe, (BH)max = 12.70 MGOe) with density of 5.59 g/cm3. In addition, the tensile strength of the NdFeB/SmFeN bonded magnets increases and the sample standard deviation narrows with decreasing NdFeB particle size. This method provides a facile preparation for anisotropic bonded magnets with a new energy density record of rubber bonded rolled magnets prepared without an external field.