Soft magnetic properties of MnZn ferrites prepared by powder injection moulding
Science of Sintering
In this study, properties of soft-magnetic manganese zinc ferrite manufactured by powder injection moulding -PIM technology were presented. A powder consisting of Mn 1x Zn x Fe 2 O 4 and a small amount of hematite α-Fe 2 O 3 was mixed with an organic binder (wax and thermoplastic) to form ferrite feedstock. Then, injection moulded toroidal samples were solvent, thermally debinded prior to sintering in air atmosphere. Magnetic properties were investigated by thermomagnetic measurements (Faraday
... surements (Faraday balance μ-T curve) and a hysteresis graph (B-H curve at different frequencies up to 1 kHz). The Curie temperature was T C ≈ 390 K for the green sample but after heating up to 740 K, T C increased up to about 570 K. The high increase in normalized magnetic permeability of about 700 % was observed due to the melting and burning of the binder. The hysteresis loop of sintered MnZn ferrite toroidal cores had an R-shape with saturation of 0.44 T and the remanence ratio of 0.49. The low value of coercivity (only 0.047 kA/m) was related to the presence of α-Fe 2 O 3 crystalline phase as well as optimum density attained (ρ ≈ 4800 kg/m³) i.e. the low porosity observed. The relative magnetic permeability attained μ r ≈ 2⋅10 3 and core power losses P s ≈ 21 W/kg for the sintered sample (at 1000 Hz; 0.39 T) are in agreement with the MnZn ferrite commercial samples prepared by standard ceramic route.