Interfacial Reaction Enhanced Liquid-Phase Sintering of Metal/Oxide Soft Magnetic Composite

Soft magnetic composites (SMCs) are ungently demanded in high-frequency power electronics for their large magnetization and high electrical resistivity. However, traditional cold-pressed SMCs are faced with low mechanical strength and insulation instability, which severely restricts their applications. In this study, liquid-phase sintering techniques to prepare FeSiAl/MoO3 SMCs are orginally employed, where consolidation and insulation of metallic magnetic particles are achieved in one step. The redox reaction between FeSiAl and MoO3 melt greatly reduces the interfacial energy, facilitates fully wetting of FeSiAl particles by MoO3 melt, and promotes the densification process during sintering. In the final FeSiAl/MoO3 SMC, FeSiAl particles are bonded covalently and insulated electrically/magnetically by the resultant Al2O3 transition layer, endowing the SMC with high crushing strength of 250 MPa, cut-off frequency of 110 MHz, permeability of 35 (@1 MHz), and low power loss of 962 kW m(-3) (5 MHz, 5 mT). This study provides alternative concept for designing new SMCs, and broadens the connotation and extension of liquid-phase sintering.