Soft magnetic particles and their composites for high frequency applications

Soft magnetic alloys have useful DC properties such as high saturation magnetization, low coercivity, and good mechanical stability.However, for applications at frequencies in the MHz range, eddy currents and increased loss impose serious limitations. By forming polymer composites with separated particles of these magnetic alloys, it is expected that losses can be reduced at these frequencies. In order to prepare composites with optimized permeability and losses, magnetic particles of amorphous Fe-Si-B, and crystalline Co-Fe, Co-Fe-V and Fe-Al-Mo were produced by spark erosion, and composites made from them were compared. The structures and magnetic properties of the particles were examined with x-ray diffraction and vibrating sample magnetometer (VSM).It is particularly interesting to note that amorphous FeSiB particles exhibit significantly higher saturation magnetization when spark eroded in water.