Geometry-preserving hybrid manufacturing of insulated Fe–6.5Si axial-flux cores using dual-material extrusion and spark plasma sintering

초록

Fe–6.5Si is an attractive soft magnetic alloy because of its high electrical resistivity and low magnetostriction; however, its intrinsic brittleness limits fabrication of three-dimensional magnetic cores. Integrating electrical insulation into such geometries is more challenging because the magnetic and insulating phases must be co-shaped and densified while retaining their designed arrangement. This study combines dual-material extrusion with spark plasma sintering to fabricate a three-dimensional axial-flux Fe–6.5Si core with an integrated metal–insulator–metal architecture. A removable sacrificial insulating component supported the segmented geometry during uniaxial densification and was removed after sintering. Printing parameters were adjusted to improve interfacial continuity, reduce defects, and maintain the magnetic-phase fraction. The sintered core retained the intended axial-flux geometry and distinct Fe–6.5Si and insulating regions with nearly uniform densification. The optimized specimen showed a magnetic flux density of 1.34 T at an applied magnetic field of 10 kA/m, increased differential permeability (dB/dH: 838.5 vs. 430.7), and reduced coercivity (157.9 vs. 196.9 A/m). Finite element analysis comparing smooth and rough interface geometries showed that interface irregularity disrupted magnetic flux continuity, reduced relative permeability from approximately 1900 to 1200, and increased the volume-averaged core loss by approximately 15%. These results establish a hybrid manufacturing route for three-dimensional Fe–6.5Si cores with integrated insulation and demonstrate the importance of printing-controlled interfacial integrity to electromagnetic performance.

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