Effects of Co₃O₄ Addition on Magnetic Properties of NiCuZn Ferrite Feedstock for 3-D-Printing Power Magnetic Components

Novel designs of magnetic components (inductors and transformers) lead to size reduction of power electronic (PE) systems but are difficult to be fabricated by conventional methods. Additive manufacturing can ease the fabrication of the novel designs that require intricate geometries or multi-permeability cores. The challenge is the lack of functional soft magnetic feedstock/ink with sufficient choices of different permeability or with tailorable permeability. In this study, we explored an easy way to tailor the permeability of a NiCuZn ferrite feedstock by adding different fractions of Co₃O₄ to the ferrite powder in the feedstock. Toroid cores were 3-D-printed using the feedstock with different fractions of Co₃O₄. Relative permeability of the sintered toroid cores could be tailored from 495 to 138 with 0%-0.8% of the Co₃O₄. Besides, 0.5% of Co₃O₄ reduced the core-loss density of the ferrite by 77.6% at a low magnetic flux density of 5 mT. The effects of Co₃O₄ on saturation flux density, dc bias permeability, electrical resistivity, packing density, and microstructure of the sintered ferrite cores were also characterized. The mechanisms of how Co₃O₄ affected the magnetic properties of the ferrite feedstock were studied.