Magnetic properties of a high-density iron dust core without binders

Abstract

Iron dust cores produced from insulated iron particles via the powder metallurgy pressure-forming process are suitable for small motor cores, reactor cores, and inductors because of their high shape flexibility. However, the dust core’s magnetic properties are inferior to those of conventional laminated cores because the insulation materials and silicon resins between iron particles to reduce eddy current losses degrade the magnetic properties of the core. Unfortunately, there is no researches of the iron dust cores without binders such as resin to improve the magnetic properties. Therefore, this paper investigates the magnetic properties of iron dust cores without binders. Assessments revealed that the dust core of gas-atomized iron powder with an average particle size of 49μm had the best magnetic properties. On further assessments, while the insulation layer’s thickness was around 60 nm, the density of gas atomized iron powder core was over 7.6 g/cm3. At 50 Hz and 1 kHz, DC hysteresis iron losses and eddy current loss of 49μm gas atomized iron dust cores without a binder showed lower values than those of the conventional powder core with a binder.