Effects of SiO2 inclusions on sintering and permeability of NiCuZn ferrite for additive manufacturing of power magnets

3D-printing has the potential to ease fabrication of novel magnetic components that lead to miniaturization of power electronic devices. The main challenge lies in the lack of functional magnetic feedstock that has many choices of different magnetic permeabilities. NiCuZn ferrite feedstock was developed of which the permeability was tailored by adding different fractions of silica particles. This paper developed a formulation guideline of the feedstock, which prescribes the fraction of silica to add from the target permeability of the feedstock. To study the mechanisms of the effects of silica on permeability of the ferrite feedstock, the feedstock was 3D printed into toroid cores and the permeability, density, and microstructure were characterized. Formulas from existing models describing the different aspects of the silica's effects on the ferrite were evaluated and combined to build the guideline. The guideline accurately predicted permeability of the composite ferrite when silica was < 10 wt. % of the ferrite.

Automated summary

3D printing has the potential to simplify the fabrication of novel magnetic components, leading to miniaturization of power electronic devices. The main challenge is the lack of functional magnetic feedstock with various choices of magnetic permeabilities. By adding different fractions of silica particles, the permeability of NiCuZn ferrite feedstock can be tailored. This paper developed a formulation guideline for the feedstock and accurately predicted the permeability of the composite ferrite.