Bonded permanent magnets with vertically aligned magnetic particles having highly uniform surface magnetic field fabricated by electrical alignment

We fabricated a flexible bonded magnet with a uniform surface magnetic field using an electrical alignment method with electrode rotation to align SrFe 12 O 19 magnetic particles in a polydimethylsiloxane (PDMS) polymer matrix. According to optical microscopy images, the SrFe 12 O 19 particles were aligned in the perpendicular direction in the PDMS using an AC bias of 5 kVpp. All samples had the same magnetization curve shape, and the magnetization curves under in-plane and perpendicular magnetic fields were almost the same. This indicates that the magnetic easy axes of the SrFe 12 O 19 particles were almost randomly aligned, although those in the samples with an AC bias were aligned in the perpendicular direction. Surface magnetic field images of the front and back sides of the samples showed that the SrFe 12 O 19 particles were uniformly distributed on both surfaces of the sample with AC bias and electrode rotation. Therefore, this technique can be helpful for practical applications of bonded magnets because a uniform surface magnetic field can suppress noise in applications such as motors and actuators.