The influences of matrix materials on the magnetic and mechanical properties of Fe78Si9B13 soft magnetic composites fabricated by injection molding

Abstract Soft magnetic composites are fabricated via metal injection molding (MIM) of amorphous Fe78Si9B13 powder in which three kinds of binders (PA + SA, HDPE + SA, PA+HDPE + SA) are chosen as matrix materials. Because of the interaction between amino in PA and carboxyl in SA, the composite having PA + SA matrix possesses a very good bonding between the matrix and the Fe78Si9B13 particles. Therefore, this sample is pore-free and has the best mechanical and dynamic magnetic properties among the three, having a compressive strength of 52.3 MPa, an effective permeability of 18.3, a coercivity of 34.6 A/m and a total core loss of 1489.3 kW/m3 at the frequency of 100 kHz (50 m T). However, when the PA is replaced by HDPE in the matrix, the bonding between the matrix and the metal particles become weaker, leading to decreased magnetic and mechanical properties. Compared to the composites fabricated by conventional compaction method reported in other researches, the soft magnetic composites fabricated by injection molding exhibit much improved DC-bias property, with the incremental permeability measured at a frequency of 100 kHz decreasing only by 18% at a bias magnetic field of 100 Oe.