Properties of MnZn ferrites prepared by powder injection molding technology

Abstract

In this work, manganese zinc ferrite components were manufactured by powder injection molding-PIM technology. A fine powder consisting of Mn1-xZnxFe2O4 with small addition of hematite alpha-Fe2O3 as used in mass ferrite production was mixed with an organic binder (Solvent System) to form ferrite feedstock for powder injection molding-PIM technology. Excess of Fe2O3 was present in the starting powder in order to suppress conversion of Fe3+ to Fe2+ ions which would lower the permeability. The ferrite feedstock was injected in a mold with a cavity shaped like a small cylinder with a hole on the main axis. Injection molded samples were then solvent and thermally debinded and sintered in different atmospheres: air, argon and nitrogen. The starting powder, injected green samples and sintered samples were characterized using X-ray diffractometry, scanning electron microscopy, thermogravimetry, differential thermal analysis as well as by magnetic measurements. Rietveld refinement of measured X-ray patterns was done to detect possible phase transformations of Fe2O3 to other iron oxides through reduction by binder residues (carbon) at elevated temperatures during thermal debinding and sintering. Finally, the magnetic properties were measured by hysteresis graph and mutually compared for the injected samples that were sintered in air, argon and nitrogen. The obtained magnetic characteristics where found to be comparable with commercial samples prepared by traditional sintering technology.